REVIEW | doi:10.20944/preprints201705.0127.v1
Subject: Life Sciences, Biochemistry Keywords: Cholangiocarcinoma; DNA methylation; Tumor suppressor gene; microRNA; DNA methylation inhibitor
Online: 16 May 2017 (18:08:59 CEST)
Cholangiocarcinoma is an epithelial malignancy arising in the region between the intrahepatic bile ducts and the ampulla of Vater at the distal end of the common bile duct. The effect of current chemotherapy regimens against cholangiocarcinoma is limited, and the prognosis of patients with cholangiocarcinoma is poor. Aberrant DNA methylation and histone modification induce silencing of tumor suppressor genes and chromosomal instability during carcinogenesis. Studies have shown that the tumor suppressor genes and microRNAs (miRNAs) including MLH1, p14, p16, DAPK, miR-370 and miR-376c are frequently methylated in cholangiocarcinoma. Silencing of these tumor suppressor genes and miRNAs plays critical roles in the initiation and progression of cholangiocarcinoma. In addition, recent studies have demonstrated that DNA methylation inhibitors induce expression of endogenous retroviruses and exert the anti-tumor effect of via an anti-viral immune response. Aberrant DNA methylation of tumor suppressor genes and miRNAs could be a powerful biomarker for diagnosis and treatment of cholangiocarcinoma. Epigenetic therapy with DNA methylation inhibitors hold considerable promise for the treatment of cholangiocarcinoma through re-activation of tumor suppressor genes and miRNAs as well as induction of an anti-viral immune response.
REVIEW | doi:10.20944/preprints201811.0235.v1
Subject: Life Sciences, Biochemistry Keywords: DNMT1; DNMT3A; DNA methyltransferase; maintenance DNA methylation; de novo DNA methylation; allosteric regulation; autoinhibition
Online: 9 November 2018 (03:57:27 CET)
DNA methylation, one of the major epigenetic mechanisms, plays critical roles in regulating gene expression, genomic stability and cell lineage commitment. Establishment and maintenance of DNA methylation in mammals is achieved by two groups of DNA methyltransferases: DNMT3A and DNMT3B, which are responsible for installing DNA methylation patterns during gametogenesis and early embryogenesis, and DNMT1, which is essential for propagating DNA methylation patterns during replication. Both groups of DNMTs are multi-modular proteins, containing a large N-terminal regulatory region in addition to the C-terminal methyltransferase domain. Recent structure-function investigations of the individual domains or large fragments of DNMT1 and DNMT3A have revealed the molecular basis for their substrate recognition and specificity, intramolecular domain-domain interactions, as well as their crosstalk with other epigenetic mechanisms. These studies highlight a multifaceted regulation for both DNMT1 and DNMT3A/3B, which is essential for the precise establishment and maintenance of lineage-specific DNA methylation patterns in cells. This review summarizes current understanding of the structure and mechanism of DNMT1- and DNMT3A-mediated DNA methylation, with emphasis on the functional cooperation between the methyltransferase and regulatory domains.
REVIEW | doi:10.20944/preprints202010.0154.v1
Subject: Life Sciences, Biochemistry Keywords: DNA methylation; epigenetics; biomarkers; circulating DNA; cfDNA; prostate cancer; early detection; prognosis
Online: 7 October 2020 (09:27:34 CEST)
There is a major clinical need for accurate biomarkers for prostate cancer prognosis, to better inform treatment strategies and disease monitoring. Current clinically recognised prognostic factors, including prostate-specific antigen (PSA) levels, lack sensitivity and specificity in distinguishing aggressive from indolent disease, particularly in patients with localised intermediate grade prostate cancer. There has therefore been a major focus on identifying molecular biomarkers that can add prognostic value to existing markers, including investigation of DNA methylation, which has a known role in tumorigenesis. In this review, we will provide a comprehensive overview of the current state of DNA methylation biomarker studies in prostate cancer prognosis, and highlight the advances that have been made in this field. We cover the numerous studies into well-established candidate genes, and explore the technological transition that has enabled hypothesis-free genome-wide studies and the subsequent discovery of novel prognostic genes.
ARTICLE | doi:10.20944/preprints202203.0068.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: global DNA methylation; global DNA hydroxymethylation; cord blood DNA; lead; antimony; birth cohort
Online: 3 March 2022 (15:04:56 CET)
DNA methylation is an epigenetic mechanism for gene expression modulation and can be used as a predictor of future disease risks. A prospective birth cohort study was performed to clarify the effects of neurotoxicants on child development, namely, the Tohoku Study of Child Development, in Japan. This study aimed to evaluate the association of prenatal exposure to five toxic metals—arsenic, cadmium, mercury, lead (Pb), antimony (Sb), and polychlorinated biphenyls (PCBs, N = 166)—with global DNA methylation in umbilical cord blood DNA. DNA methylation markers, 5-methyl-2’-deoxycytidine (mC) and 5-hydroxymethyl-2’-deoxycytidine (hmC), were determined using liquid chromatography-tandem mass spectrometry. The mC content in cord blood DNA was positively correlated with Pb and Sb levels (r = 0.442 and 0.288, respectively) but not with cord blood PCBs. We also observed significant positive correlations among Pb levels, maternal age, and hmC content (r = 0.159 and 0.243, respectively). The multiple regression analysis among the potential predictors demonstrated consistent positive associations between Pb and Sb levels and mC and hmC content. Our results suggest that global DNA methylation is a promising biomarker for prenatal exposure to Pb and Sb.
ARTICLE | doi:10.20944/preprints202106.0600.v1
Online: 24 June 2021 (15:47:38 CEST)
Background: Telomere length (TL) shortening process is associated with several known environment and individual determinants. DNA methylation is the most studied epigenetic process and may be associated with TL. We investigated the associations between DNA methylation and TL in peripheral blood. Methods: Methylation wide association study was conducted in 47 women (37.1±8.8 years) with different nutritional status. Association between TL and DNA methylation levels were explored by univariate and multiple linear regression models, corrected by age and Body Mass Index. Corrections for multiple comparisons by Benjamini‐Hochberg test was also performed. WEBGestalt was used to identify pathways that are responsible for regulating TL. Results: We found negative correlations between TL and BMI (r = -0.641; p = 0.001), abdominal circumference (r = -0.622; p = 0.001) and fat mass (r = -0.656; p = 0.001). 44 CpGs sites were associated with TL, independent of age and BMI. The most of these sites were negatively correlated with TL. For the 7 remained sites, DNA hypomethylation were associated with shorter TL. These CpGs were related to nine different pathways, including thermogenesis, cancer, glutamatergic and serotonergic synapse. Conclusion: There is an epigenetic contribution in TL, independent of nutritional status and age. Genes related to TL are involved in important metabolic pathways.
ARTICLE | doi:10.20944/preprints202210.0305.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: gastric cancer; DNA methylation; TFF1; TFF2
Online: 20 October 2022 (11:07:15 CEST)
Gastric cancer (GC) is one of the most common malignancies around the world, and the incidence of GC is increasing in the past decades. In addition to genetic modifications, epigenetic alterations catalyzed by DNA methyltransferases (DNMTs) are a well-characterized epigenetic hallmark in gastric cancer. Nowadays, DNA methylation landscape is essential for maintaining the silence of tumor suppressor genes (TSGs). As an important group of peptide, TFF family has been confirmed to function as a TSG in various kinds of cancers. However, whether TFFs could be modified by DNA methylation in gastric cancer remains unknown. In this study, we initially screened out two expression profiles about GC from Gene Expression Omnibus (GEO) database. The higher expressions of TFF1 and TFF2 were observed in GC tumor tissues than normal tissues. Additionally, we illustrated that the expressions of TFF1/TFF2 were associated to the overall survival (OS) and tumor free survival (TFS) of GC patients via through the Kaplan-Meier analysis. Subsequently, the integrative analysis was performed to estimate the DNA methylation level of each site in TFF1/TFF2 CpG islands. Importantly, our findings indicated that hyper-methylation of cg01886855 and cg26403416 were separately responsible for the downregulation of TFF1 and TFF2 in GC samples. Besides, utilizing the gain of function assay, we demonstrated that TFF1/TFF2 could suppress the proliferation of GC cells. Based on these results, We identified that TFF1 and TFF2 acted as the putative tumor suppressors in gastric cancer, which suggested that TFFs could be two candidate biomarkers for predicting tumor recurrence in gastric cancer patients. Furthermore, these findings highlight a potential therapeutic approach in targeting the TFFs for the treatment of gastric cancer.
ARTICLE | doi:10.20944/preprints202211.0513.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: breast cancer; small tumors; DNA methylation; CCDC181; ZNF177; fibroadenoma; biomarker; MS-HRM; pyrosequencing
Online: 28 November 2022 (10:51:17 CET)
The DNA methylation profile of breast cancer differs from that in healthy tissue and can be used as a diagnostic and prognostic biomarker. Aim of the study: to compare gene methylation in small malignant breast tumors less than 2 cm and in healthy tissue and fibroadenoma. Methylation of the following 15 genes was studied: MAST1, PRDM14, ZNF177, DNM2, SSH1, AP2M1, CACNA1E, CPEB4, DLGAP2, CCDC181, GCM2, ITPRIPL1, POM121L2, KCNQ1, TIMP3. Methods: analysis was made by our modified MS-HRM method followed confirmation of the results by pyrosequencing. The genes were selected from publications that studied DNA methylation in breast cancer with high genome coverage. The study group included 48 samples of breast cancer, the control group included 24 samples of fibroadenoma and 24 samples of healthy tissue. Results: significant differences were found in methylation of 8 genes: CCDC181, GSM2, ITPRIPL1, ZNF177, CACNA1E, DLGAP2, TIMP3 (all р<0.001), and PRDM14 (р=0.002). The most accurate diagnostic value, based on logistic regression, was shown with the compound of two genes – CCDC181 and ZNF177 (AUC=0.99) in pyrosequencing analysis. Conclusion: small breast cancer tumors have a specific DNA methylation profile that distinguishes them from healthy tissue and benign proliferative lesions.
REVIEW | doi:10.20944/preprints202105.0476.v1
Subject: Biology, Anatomy & Morphology Keywords: Histone Methylation, DNA repair, homologous recombination, Non homologous end joining
Online: 20 May 2021 (10:26:07 CEST)
Packaging of the eukaryotic DNA genome with histone and other proteins forms a chromatin structure that regulates the outcome of all DNA mediated processes. The cellular pathways that ensure genomic stability detect and repair DNA damage through mechanisms which are critically dependent upon chromatin structures established by histones and, particularly, transient histone post-translational modifications . Though subject to a range of modifications, histone methylation is especially crucial for DNA damage repair as the methylated histones often form platforms for subsequent repair protein binding at damaged sites. In this review, we highlight and discuss how histone methylation impacts the maintenance of genome integrity through effects related to DNA repair and repair pathway choice.
Subject: Medicine & Pharmacology, Allergology Keywords: DNA methylation; air pollution; particulate matter; saliva; biomarker
Online: 2 August 2021 (09:04:00 CEST)
Background: Exposure in utero to particulate matter (PM2.5 and PM10) is associated with maladaptive health outcomes. Although exposure to prenatal PM2.5 and PM10 have cord blood DNA methylation signatures at birth, signature persistence into childhood and saliva cross-tissue applicability has not been tested. Methods: In the Fragile Families and Child Wellbeing Study, a United States 20-city birth cohort, average residential PM2.5 and PM10 during pregnancy was estimated using air quality monitors with inverse distance weighting. Saliva DNA methylation at ages 9 (n=749) and 15 (n=793) was measured using the Illumina HumanMethylation 450k BeadArray. Cumulative DNA methylation scores for particulate matter were estimated by weighting participant DNA methylation at each site by meta-analysis effect estimates from Gruzieva et al. 2019 and standardizing the sums. Using mixed effects regression analysis, we tested the associations between cumulative DNA methylation scores at ages 9 and 15 and PM exposure during pregnancy, adjusted for child sex, age, race/ethnicity, maternal income to needs ratio, nonmartial birth status, and saliva cell type proportions. Results: Our study sample was 50.5% male, 56.3% non-Hispanic Black, and 19.8% Hispanic, with median income to needs ratio of 1.4. In the third trimester, mean PM2.5 exposure levels were 27.9 ug/m3/day (standard deviation: 7.0, 23.7% of observations exceeded safety standards) and PM10 were 15.0 ug/m3/day (standard deviation: 3.1). An interquartile range increase in PM2.5 exposure (10.73 g/m3/day) was associated with -0.0287 standard deviation lower cumulative DNA methylation score for PM2.5 (95% CI: -0.0732, 0.0158, p=0.20) across all participants. An interquartile range increase in PM10 exposure (3.20 g/m3/day) was associated with -0.1472 standard deviation lower cumulative DNA methylation score for PM10 (95% CI: -0.3038, 0.0095, p=0.06) across all participants. The PM10 findings were driven by the age 15 subset where an interquartile range increase in PM10 exposure was associated with -0.024 standard deviation lower cumulative DNA methylation score for PM10 (95% CI: -0.043, -0.005, p=0.012). Findings were robust to adjustment for PM exposure at ages 1 and 3. Conclusion: In utero PM10 associated DNA methylation differences persist until age 15 and can be detected in saliva. Benchmarking the persistence and cell type generalizability is critical for epigenetic exposure biomarker assessment.
ARTICLE | doi:10.20944/preprints202211.0074.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: telomerase; TERT promoter; DNMT3B; pluripotent stem cells; characterization; epigenetic; meth-ylation; physiological oxygen; DNA methyltransferase
Online: 3 November 2022 (09:16:20 CET)
Telomere repeats at the ends of human chromosomes protect chromosomes from degradation, and telomerase has a prominent role in telomere maintenance. Telomerase also affects cell proliferation, DNA replication, differentiation, and tumourigenesis. TERT (telomerase reverse transcriptase enzyme) is the catalytic subunit of telomerase and is critical for enzyme activity. TERT promoter mutations and promoter methylation are strongly associated with increased telomerase activation in cancer cells. Notably, TERT and telomerase are downregulated in stem cells during their differentiation. Therefore, the link between differentiation and telomerase provides a valuable tool for studying the epigenetic regulation of TERT enzyme. Oxygen tension affects several cellular behaviours including proliferation, metabolic activity, stemness, and differentiation. The role of oxygen tension in driving promoter modifications of the TERT gene in embryonic stem cells (ESCs) is poorly understood either in vitro or in vivo. We adopted a monolayer ESCs differentiation model to explore the role of low, physiological, oxygen (physoxia) in the epigenetic regulation of telomerase and associated genes, including TERT, DNMTs, and HDACs. Cells were cultured in either air, a 2% O2 incubator, or a 2% O2 oxygen workstation to provide a fully defined 2% O2 environment. Pre-gassed media (pre-conditioned to 2% O2 in a HypoxyCool unit) was used in all 2% O2 experimentation. As anticipated, physoxia culture increased the proliferation rate and stemness of ESCs and a slower onset of differentiation in physoxia was evident. Further, downregulated TERT expression was correlated to reduced telomerase activity during differentiation. TERT expression and telomerase activity remained significantly elevated in physoxia during differentiation. A substantial increase in TERT promoter methylation levels was noted during differentiation. Chemical inhibition of DNMT3B reduced TERT promoter methylation and was associated with increased TERT gene and telomerase activity during differentiation. DNMT3B CHiP demonstrated that downregulated TERT expression and increased proximal promoter methylation were associated with DNMT3B binding to the promoter. In conclusion, we have demonstrated that DNMT3B can directly bind TERT promoter, change its methylation levels, and contribute to regulation of telomerase activity.
Subject: Medicine & Pharmacology, Urology Keywords: Immune cell; DNA CpGs; Bladder cancer; Subtype; mutation; CNV; Immune score; Immune Checkpoints
Online: 5 September 2020 (06:00:06 CEST)
Background: Bladder cancer (BC) development is highly related to immune cell infiltration and inflammation. This study aimed to construct a new classification of bladder cancer (BC) molecular subtypes based on immune cells-associated CpG sites. Methods: The genes of 28 types of immune cells were obtained from previous studies. Then methylation sites corresponding to immune cells-associated genes were acquired. Differentially methylation sites (DMSs) were identified between normal samples and bladder cancer samples. Unsupervised clustering analysis of differentially methylation sites was performed to divide into several subtypes. Then the potential mechanism of different subtypes was exploded. Result: Bladder cancer patients were divided into three groups. Cluster 3 (methylation-L) subtype had the best prognosis. Cluster 1 (methylation-M) had the worst prognosis. The distribution of immune cells, level expression of checkpoints, stromal score, immune score, ESTIMATEScore, tumor purity, APC_co_inhibition, APC_co_stimulation, HLA, MHC_class_I, Type_I_IFN_Reponse, and Type_II_IFN_Reponse were significant difference among three subgroups. The distribution of genomic alterations was different among them. Conclusion: The classification was accurate and stable. BC patients could be divided into three subtypes based on the immune cells-associated CpG sites. Specific biological signaling pathways, immune mechanisms, and genomic alterations were various among three subgroups. High level immune infiltration was a correlation with high level methylation. The lower RNAss score was associated with higher immune infiltration and higher level expression of CD274.
ARTICLE | doi:10.20944/preprints201910.0191.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: polycystic ovarian syndrome; granulosa cells; microrna regulation; dna methylation; biomarker
Online: 17 October 2019 (12:30:58 CEST)
Aberration in microRNA (miRNA) expression or DNA methylation is a causal factor for polycystic ovarian syndrome (PCOS), a common endocrine disorder and leading cause of infertility. However, the epigenetic interactions between miRNA and DNA methylation remain unexplored in PCOS. In this study, we conducted an integrated analysis of RNA-seq, miRNA-seq and MBD-seq on ovarian granulosa cells of PCOS and control groups to reveal the epigenetic interactions involved in the pathogenesis of PCOS. Firstly, we identified 830 genes and 30 miRNAs that were expressed differently in PCOS, and seven miRNAs were found to negatively regulate targeted mRNA expression. Next, in total, 130 miRNAs were found to be significantly differently methylated in promoter regions, while 13 were found to be associated with miRNA expression. Furthermore, the promoter hypermethylation of miR-429, miR-141-3p, and miR-126-3p was proven to suppress miRNA expression and therefore upregulate their corresponding genes, including XIAP, BRD3, MAPK14 and SLC7A5. Our results demonstrate that DNA methylation regulates miRNA expression and therefore controls its corresponding gene expression. The reactivation of the transcription of epigenetically silenced genes may be one of the key elements in PCOS pathogenesis. Meanwhile, the epigenetic mechanisms underlying the regulation of miRNA expression can provide a potential therapeutic target for PCOS in the future.
ARTICLE | doi:10.20944/preprints202110.0030.v1
Subject: Life Sciences, Genetics Keywords: Meniere Disease; cytokines; WGBS; Hearing Loss; DNA methylation
Online: 1 October 2021 (16:03:48 CEST)
Meniere Disease (MD) is a multifactorial disorder of the inner ear characterized by vertigo attacks associated with sensorineural hearing loss and tinnitus with a significant heritability. Although MD has been associated with several genes, no epigenetic studies have been performed in MD. Here we performed whole genome bisulfite sequencing in 14 MD patients and 6 healthy controls, with the aim of identifying a MD methylation signature and potential disease mechanisms. We observed a high number of differentially methylated CpGs (DMC) when comparing MD patients to controls (N= 9,545), several of them in hearing loss genes such as PCDH15, ADGRV1 and CDH23. Bioinformatic analyses of DMCs and cis-regulatory regions predicted phenotypes related to abnormal excitatory postsynaptic currents, abnormal NMDA-mediated receptor currents and abnormal glutamate-mediated receptor currents when comparing MD to controls. Moreover, we identified various DMCs in genes previously associated with cochleovestibular phenotypes in mice. We have also found 12 undermethylated regions (UMR) that were exclusive to MD, including 2 UMR in an inter CpG island in the PHB gene. We suggest that the DNA methylation signature allows to distinguish between MD patients and controls. The enrichment analysis confirms previous findings of a chronic inflammatory process underlying MD.
REVIEW | doi:10.20944/preprints202109.0109.v1
Subject: Life Sciences, Molecular Biology Keywords: proteomics; transcriptomics; DNA methylation; mitochondria; metabolism; OXPHOS; ASD; neurogenesis; gliosis; neurodevelopment
Online: 6 September 2021 (17:14:37 CEST)
Abstract: Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder with extensive genetic and aetiological heterogeneity. While the underlying molecular mechanisms involved remain unclear, significant progress has been facilitated by recent advances in high-throughput transcriptomic, epigenomic and proteomic technologies. Here, we review recently published ASD proteomic data and compare proteomic func-tional enrichment signatures to those of transcriptomic and epigenomic data. We iden-tify canonical pathways that are consistently implicated in ASD molecular data and find an enrichment of pathways involved in mitochondrial metabolism and neurogenesis. We identify a subset of differentially expressed proteins that are supported by ASD tran-scriptomic and DNA methylation data. Furthermore, these differentially expressed proteins are enriched for disease phenotype pathways associated with ASD aetiology. These proteins converge on protein-protein interaction networks that regulate cell pro-liferation and differentiation, metabolism and inflammation which demonstrates a link between canonical pathways, biological processes and the ASD phenotype. This review highlights how proteomics can uncover potential molecular mechanisms to explain a link between mitochondrial dysfunction and neurodevelopmental pathology.
REVIEW | doi:10.20944/preprints202105.0717.v1
Subject: Life Sciences, Biochemistry Keywords: Alzheimer; TAU; MAPT; epigenetics; neurodegeneration; neurogenetic disease; DNA methylation
Online: 31 May 2021 (09:08:07 CEST)
Genetic and sporadic forms of tauopathies, the most prevalent of which is Alzheimer’s Disease, are a scourge of the aging society, and in case of genetic forms, can also affect children and young adults. All tauopathies share ectopic expression, mislocalization, or aggregation of the microtubule associated protein TAU, encoded by the MAPT gene. As TAU is a neuronal protein widely expressed in the CNS, the overwhelming majority of tauopathies are neurological disorders. They are characterized by cognitive dysfunction often leading to dementia, and are frequently accompanied by movement abnormalities such as parkinsonism. Tauopathies can lead to severe neurological deficits and premature death. For some tauopathies there is a clear genetic cause and/ or an epigenetic contribution. However, for several others the disease etiology is unclear, with few tauopathies being environmentally triggered. Here we review current knowledge of tauopathies listing known genetic and important sporadic forms of this disease. Further, we discuss how DNA methylation as a major epigenetic mechanism emerges to be involved in the disease pathophysiology of Alzheimer’s, and related genetic and non-genetic tauopathies. Finally, we debate the application of epigenetic signatures in peripheral blood samples as diagnostic tool and usage of epigenetic therapy strategies for these diseases.
ARTICLE | doi:10.20944/preprints202103.0659.v1
Subject: Life Sciences, Biochemistry Keywords: Chondrogenesis; chondrocyte; cell differentiation; C3H10T1/2; high density culture; mouse em-bryo; epigenetic signals; DNA methylation; 5-azacytidine
Online: 26 March 2021 (11:24:08 CET)
The aim of this study was to investigate the role of DNA methylation in the regulation of in vitro and in vivo cartilage formation. Based on the data of an RNA chip-assay performed on chondrifying BMP2-overexpressing C3H10T1/2 cells, the relative expression of Tet1 (tet methylcytosine dioxygenase 1), Dnmt3a (DNA methyltransferase 3) and Ogt (O-linked N-acetylglucosamine transferase) genes was examined with RT-qPCR in mouse cell-line based and primary micromass cultures. RNA probes for in situ hybridization were used on frozen sections of 15-day-old mouse embryos. DNA methylation was inhibited with 5-azacytidine during culturing. We found very strong but gradually decreasing expression of Tet1 throughout the entire course of in vitro cartilage differentiation along with strong signals in the cartilaginous embryonic skeleton. Dnmt3a and Ogt expressions did not show significant changes with RT-qPCR and gave weak in situ hybridization signals. Inhibition of DNA methylation applied during early stages of differentiation reduced cartilage-specific gene expression and cartilage formation. In contrast, it had stimulatory effect when added to differentiated chondrocytes. Our results indicate that the DNA demethylation-inducing Tet1 is a significant epigenetic factor of chondrogenesis, and inhibition of DNA methylation exerts distinct effects in different phases of in vitro cartilage formation.
ARTICLE | doi:10.20944/preprints201805.0398.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: retinal degeneration; DNA methylation; epigenetics; oxidative stress; inflammation
Online: 28 May 2018 (10:33:13 CEST)
The role of epigenetic alterations in the pathogenesis of age-related macular degeneration (AMD) has been pending so far. Our study investigated the effect of oxidative stress and inflammation on DNA methyltransferases (DNMTs) and Sirtuin 1 (SIRT1) functions, as well as on long interspersed nuclear element-1 (LINE-1) methylation, in human retinal pigment epithelial (ARPE-19) cells. Therefore, we evaluated whether treatment with resveratrol may restore changes in LINE-1 methylation by modulating DNMTs and SIRT1 functions. Cells were treated with 25 mU/ml glucose oxidase (GOx) or 10 µg/ml lipopolysaccharide (LPS) to mimic oxidative or inflammatory conditions, respectively. Oxidative stress decreased DNMT1, DNMT3a, DNMT3b and SIRT1 expression (p-values <0.05), as well as total DNMTs (-28.5%; p<0.0001) and SIRT1 (-29.0%;p<0.0001) activities. Similarly, inflammatory condition decreased DNMT1 and SIRT1 expression (p-values<0.05), as well as total DNMTs (-14.9%;p=0.007) and SIRT1 (-20.1%;p<0.002) activities. Interestingly, GOx- and LPS-treated cells exhibited lower LINE-1 methylation compared to controls (p-values<0.0001). We also demonstrated that treatment with 10 μM resveratrol for 24 hours counteracted the detrimental effect on LINE-1 methylation via increasing DNMTs and SIRT1 functions in cells upon oxidative and inflammatory conditions. However, further studies should explore the perspectives of resveratrol as a suitable strategy for the prevention and/or treatment of AMD.
ARTICLE | doi:10.20944/preprints201804.0323.v2
Subject: Biology, Plant Sciences Keywords: epigenetics; differentially methylated markers (DMMs); LEAVES; roots; DNA methylation; salinity stress; barley
Online: 15 June 2018 (06:10:53 CEST)
Salinity can negatively impact crop growth and yield. Changes in DNA methylation are known to occur when plants are challenged by stress and have been associated with the regulation of stress-response genes. However, the role of DNA-methylation in moderating gene expression in response to salt stress has been relatively poorly studied among crops such as barley. Here, we assessed the extent of salt-induced alterations of DNA methylation in barley and their putative role in perturbed gene expression. Using Next Generation Sequencing, we screened the leaf and root methylomes of five divergent barley varieties grown under control and three salt concentrations, to seek genotype independent salt-induced changes in DNA methylation. Salt stress caused increased methylation in leaves but diminished methylation in roots with a higher number of changes in leaves than in roots, indicating that salt induced changes to global methylation are organ specific. Differentially Methylated Markers (DMMs) were mostly located in close proximity to repeat elements, but also in 1094 genes, of which many possessed gene ontology (GO) terms associated with plant responses to stress. Identified markers have potential value as sentinels of salt stress and provide a starting point to allow understanding of the functional role of DNA methylation in facilitating barley’s response to this stressor.
ARTICLE | doi:10.20944/preprints202110.0338.v1
Subject: Behavioral Sciences, Behavioral Neuroscience Keywords: cumulative family risk; child maltreatment; early adversity; DNA methylation; SLC6A4
Online: 25 October 2021 (10:26:29 CEST)
Exploring the contribution of proximal family risk factors on SLC6A4 DNA methylation in children with a history of maltreatment
ARTICLE | doi:10.20944/preprints202002.0038.v1
Subject: Life Sciences, Molecular Biology Keywords: allele specific expression; 6-BA; DNA methylation; long noncoding RNA; siRNA; poplar
Online: 4 February 2020 (05:22:28 CET)
The cytokinins play important roles in plant growth and development by regulating gene expression at genome wide level. DNA methylation is responsive to the external environment, but whether DNA methylation changes in response to cytokinin treatment to regulate gene expression is still unclear. Here, we used bisulfite sequencing and RNA sequencing to examine genome-wide DNA methylation and gene expression patterns in poplar (Populus tomentosa) after treatment with the synthetic cytokinin 6-benzylaminopurine (6-BA). We identified 566 significantly differentially methylated regions (DMRs) in response to 6-BA treatment. Transcriptome analysis showed that 501 protein-coding genes, 262 long non-coding RNAs, and 15,793 24-nt small interfering RNAs were differentially expressed under 6-BA treatment. Among these, 79% were differentially expressed between alleles in P. tomentosa. Combined DNA methylation and gene expression analysis demonstrated that DNA methylation plays an important role in regulating allele-specific gene expression. To further investigate the relationship between these 6-BA-responsive genes and phenotypic variation, we performed SNP analysis of 507 6-BA-responsive DMRs via re-sequencing using a natural population of P. tomentosa and identified 206 SNPs that were significantly associated with growth and wood properties. Association analysis indicated that 53% of loci with allele-specific expression had primarily dominant effects on poplar traits. Our comprehensive analyses of P. tomentosa DNA methylation and the regulation of allele-specific gene expression suggest that DNA methylation is an important regulator of imbalanced expression between allelic loci.
ARTICLE | doi:10.20944/preprints201902.0006.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: APOE gene; Apolipoprotein E; DNA methylation; Mild cognitive impairment; Hispanics.
Online: 1 February 2019 (09:22:48 CET)
Background: Biomarkers are essential for identification of individuals at high risk of mild cognitive impairment (MCI) for potential prevention of dementia. We investigated DNA methylation in the ApoE gene and plasmatic apolipoprotein E (ApoE) levels as MCI biomarkers in Colombian subjects with MCI and controls. Methods: 100 participants were included (71% women, average age, 70 yrs., range 43-91). MCI was diagnosed by neuropsychological testing, medical and social history, activities of daily living, cognitive symptoms and neuroimaging. Multivariate logistic regression models adjusted by age and gender were performed to examine the risk association of MCI with plasma ApoE and APOE methylation Results: MCI was diagnosed in 41 subjects (average age, 66.5±9.6 yrs.) and compared with 59 controls. Elevated plasma ApoE and APOE methylation of CpGs 165, 190, and 198 were risk factors for MCI (P<0.05). Higher CpG-227 methylation correlated with lower risk for MCI (P=0.002). Only CpG-227 was significantly correlated with plasmatic ApoE levels (correlation coefficient=-0.665; P=0.008). Conclusion: Differential APOE methylation and increased plasma ApoE levels were correlated with MCI. These epigenetic patterns can be used as potential biomarkers to identify early stages of MCI.
ARTICLE | doi:10.20944/preprints202010.0641.v1
Subject: Life Sciences, Biochemistry Keywords: aging; paternal exposure; sperm; advanced paternal age; epigenetics; DNA methylation; RRBS, 2,2′,4,4′-tetrabromodiphenyl ether; PBDE; BDE-47; perinatal; environment
Online: 30 October 2020 (13:37:14 CET)
Advanced paternal age at fertilization has been suggested to be a risk factor for neurodevelopmental, psychiatric and other disorders in offspring. One emerging hypothesis suggests that altered offspring phenotype is linked with age-related accumulation of epigenetic changes in the sperm of fathers. Given that paternal age is increasing in the developed world, understanding aging-related epigenetic changes in sperm is needed as well as environmental factors that modify such changes. In this study, we characterize age-dependent changes in sperm DNA methylation profiles between young pubertal (postnatal day (PNDs) 65) and mature (PND120) Wistar rats. We also analyze these changes in rats exposed perinatally to 0.2 mg/kg of ubiquitous environmental xenobiotic 2,2’,4,4’-tetrabromodiphenyl ether (BDE-47). Reduced representation bisulfite sequencing (RRBS) libraries were prepared from caudal epididymal sperm DNA and differentially methylated regions (DMRs; ≥ 10x coverage depth, ≥ 3 CpGs per cluster, ≥ 5% methylation change, q < 0.05) were identified via MethPipe package. In control animals, 5,319 age-dependent DMRs were identified, with 99.3% DMRs hypermethylated in mature animals compared to young pubertal rats. These age-related DMRs were enriched for functional categories essential for embryonic development, such as pattern specification, forebrain and sensory organ development, Hippo and Wnt pathways. Age-related changes in sncRNA, reported in different study, target similar list of genes and biological categories.In BDE-47 exposed rats, sperm DNA methylation was higher in young pubertal and lower in mature animals when compared to controls, which resulted in a significant attenuation in the number of age-dependent DMRs (N = 189) identified in the exposed group. In conclusion, our results indicate that the natural aging process has profound effects on sperm methylation levels and this effect may be modified by environmental exposures. Moreover, our results further support the role of epigenetic mechanisms as a likely link betwen paternal age and offspring health and development.
BRIEF REPORT | doi:10.20944/preprints202003.0295.v1
Subject: Medicine & Pharmacology, Other Keywords: Wuhan 2019-nCoV; ACE2; DNA methylation; epigenetics; profiling; lung tissue; age; gender; COVID-19; coronavirus
Online: 19 March 2020 (02:51:45 CET)
Background: Coronavirus disease 2019 (COVID-19) has emerged as a global threat to human health and disease risk increases with advancing age. The regulation of the ACE2 gene that codes for COVID-19 host receptor ACE2 has been shown to be under epigenetic regulation. Here, we examined whether intensive DNA methylation profiling of the ACE2 gene differed by human host tissue and cell type, gender, and age. Results: Accessing four public datasets, we observed unique human cell-type-specific ACE2 DNA methylation patterns. In human lung tissues, gender differences in DNA methylation at 2 sites related to the ACE2 gene were identified. Further, in freshly isolated airway epithelial cells, DNA methylation near the transcription start site of the ACE2 gene associated with biological age. Conclusion: Epigenetic profiling of host tissue may permit discovery of age and gender-related potential risk factors for COVID-19. How perturbations in ACE2 methylation relate to clinical severity across the ages and gender needs to be determined to guide screening tools and potential epigenetic modification targeting to alleviate COVID-19 morbidity in the elderly.
REVIEW | doi:10.20944/preprints201812.0267.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Alzheimer’s disease; CTH gene; DNA methylation; epigenetics; epigenome-wide association study; methylome; MTHFR gene; nutrition; S-adenosylmethionine; vitamin B complex
Online: 24 December 2018 (04:48:53 CET)
DNA methylation and other epigenetic factors are important in the pathogenesis of late-onset Alzheimer’s disease (LOAD). Methylenetetrahydrofolate reductase (MTHFR) gene mutations occur in most elderly patients with memory loss. MTHFR is critical for production of S-adenosyl-L-methionine (SAM), the principal methyl donor. A common mutation (1364T/T) of the cystathionine-γ-lyase (CTH) gene affects the enzyme that converts cystathionine to cysteine in the trans-sulfuration pathway causing plasma elevation of total homocysteine (tHcy) or hyperhomocysteinemia – a strong and independent risk factor for cognitive loss and AD. Other causes of hyperhomocysteinemia include aging, nutritional factors, and deficiencies of B vitamins. We emphasize the importance of supplementing vitamin B12 (methylcobalamin), vitamin B9 (folic acid), vitamin B6 (pyridoxine), and SAM to patients in early stages of LOAD.
ARTICLE | doi:10.20944/preprints202107.0005.v1
Online: 1 July 2021 (09:28:54 CEST)
Track-structure Monte Carlo simulations are useful tools to evaluate initial DNA damage induced by irradiation. In the previous study, we have developed a Gean4-DNA-based application to estimate the cell surviving fraction of V79 cells after irradiation, bridging the gap between the initial DNA damage and the DNA-rejoining kinetics by means of the two-lesion kinetics (TLK) model. However, since the DNA repair performance depends on cell line, the same model parameters cannot be used for the different cell lines. Thus, we extended the Geant4-DNA application with an updated TLK model for the evaluation of DNA damage repair performance in HSGc-C5 carcinoma cells which are typically used for evaluating proton/carbon radiation treatment effects. For this evaluation, we also performed experimental measurements for cell surviving fractions and DNA-rejoining kinetics of the HSGc-C5s cells. Concerning fast- and slow-DNA rejoining, the TLK model parameters were adequately optimized with the simulated initial DNA damage. Using the optimized TLK model, the Geant4-DNA simulation is now able to predict cell survival and DNA-rejoining kinetics for HSGc-C5s cells.
REVIEW | doi:10.20944/preprints202011.0339.v2
Online: 18 November 2020 (10:51:18 CET)
Cancer-associated fibroblasts (CAF) form the basis of tumor microenvironment and possess immunomodulatory functions by interacting with other cells surrounding tumor, including T lymphocytes, macrophages, dendritic cells and natural killer cells. Ionizing radiation is a broadly-used method in radiotherapy to target tumors. In mammalian cells, ionizing radiation induces various types of DNA damages and DNA damage response. Being unspecific, radiotherapy affects all the cells in tumor microenvironment, including the tumor itself, CAFs and immune cells. CAFs are extremely radio-resistant and do not initiate apoptosis even at high doses of radiation. However, following radiation, CAFs become senescent and produce a distinct combination of immunoregulatory molecules. Radiosensitivity of immune cells varies depending on the cell type due to inefficient DNA repair in, for example, monocytes and granulocytes. In this minireview, we are summarizing recent findings on the interaction between CAF, ionizing radiation and immune cells in the tumor microenvironment.
ARTICLE | doi:10.20944/preprints201811.0046.v1
Subject: Life Sciences, Genetics Keywords: DNA replication, DNA repair, genetic recombination, mutagenesis
Online: 2 November 2018 (10:19:18 CET)
Covalent DNA protein crosslinks (DPCs) are common lesions that block replication. We examine here the consequence of DPCs on mutagenesis involving replicational template-switch reactions in Escherichia coli. 5-azacytidine (5azaC) is a potent mutagen for template-switching, dependent on DNA cytosine methylase (Dcm), implicating the trapped Dcm-DNA covalent complex as the initiator for mutagenesis. The leading strand of replication is more mutable than the lagging strand, explained by blocks to the replicative helicase and/or fork regression. We find that template-switch mutagenesis induced by 5-azaC does not require DSB repair via RecABCD. The ability to induce the SOS response is anti-mutagenic by an unknown mechanism. Mutants in recB, but not recA, exhibit high constitutive rates of template-switching and we suggest that RecBCD-mediated DNA degradation prevents template-switching associated with fork regression. A mutation in the DnaB fork helicase also promotes high levels of template-switching. We also find that other DPC-inducers, formaldehyde (a non-specific crosslinker) and ciprofloxacin (a topoisomerase II poison) are also strong mutagens for template-switching. Induction of mutations and genetic rearrangements that occur by template-switching may constitute a previously unrecognized component of the genotoxicity and genetic instability promoted by DPCs.
ARTICLE | doi:10.20944/preprints201812.0293.v1
Subject: Biology, Other Keywords: human poly(ADP-ribose) polymerase 1 (PARP1), PARP-DNA complex,DNA-protein binding,DNA repair, 5′,8-Cyclopurine-2′-deoxynucleoside, DNA damage , DNA repair efficiency.
Online: 24 December 2018 (16:01:44 CET)
Abstract5′,8-Cyclo-2′-deoxyadenosine (cdA), in the 5′R and 5′Sdiastereomeric forms, are typical non strand-break oxidative DNA lesions, induced by hydroxyl radicals, with emerging importance as a molecular marker. These lesions are exclusively repaired by nucleotide excision repair (NER) mechanism with a low efficiency, thus readily accumulating in the genome. Poly(ADP-ribose) polymerase1 (PARP1) acts as an early responder to DNA damage and plays a key role as a nick sensor in the maintenance of the integrity of the genome by recognizing nicked DNA. So far, it was unknown whether the diastereomeric cdA lesions could induce specific PARP1 binding. Here we provide the first evidence of PARP1 to selectively recognize the diastereomeric lesions 5′S-cdA and 5′R-cdA in vitro as compared to deoxyadenosine in model DNA substrates (23-mers) by using circular dichroism,fluorescence spectroscopy, immunoblotting analysis and gel mobility shift assay. Several features of the recognition of the damaged and undamaged oligonucleotides by PARP1were characterized. Remarkably, PARP1 efficiently binds to both cdA lesions in the double stranded (ds)-oligonucleotides. In particular, PARP1 proved to bind 5′S-cdAwith a higher affinity constant for the 5'S lesion in a model of ds DNA than 5′R-cdA, showing different recognition patterns, also compared with undamaged dA. This new finding highlights the ability of PARP1 to recognize and differentiate the distorted DNA backbone in a biomimetic system caused by different diastereomeric forms of a cdA lesion.
ARTICLE | doi:10.20944/preprints202210.0199.v1
Subject: Life Sciences, Biochemistry Keywords: human milk; DNA extraction; PCR; DNA quality, microbiota
Online: 14 October 2022 (03:19:46 CEST)
Recent advances in DNA sequencing technology have shown that the human milk microbiota of healthy women varies substantially. The gDNA extraction method may influence the observed variation, biasing the microbiological reconstruction after all. In this study, a genomic DNA extraction method for DNA isolation from human milk samples was standardized and compared with commercial and standard hose make methods. Spectrophotometric measurements, gel electrophoresis, and PCR amplifications were used as criteria for evaluating the quantity, quality, and functionality of the extracted DNA. Furthermore, the standardized method of extracting gDNA from human milk was evaluated for its ability to isolate functional DNA from gram-positive, and gram-negative bacteria and fungi, to improve the reconstruction of microbiological profiles. The novel DNA extraction method increased the quantity and quality of the gDNA extracted compared with commercial and standard house-make protocols. This method even allowed PCR amplification of the V3-V4 regions of the 16S ribosomal gene in all samples, and the ITS-1 region of the fungal 18S ribosomal gene in 95 % of the samples as well. It is concluded that the proposed method provides better performance for the extraction of gDNA from complex samples such as human milk.
Subject: Life Sciences, Genetics Keywords: forensic genetic genealogy; investigative genetic genealogy; DNA; forensic DNA
Online: 1 August 2020 (16:29:22 CEST)
Forensic genetic genealogy, a technique leveraging new DNA capabilities and public genetic databases to identify suspects, raises specific considerations in a law enforcement context. Use of this technique requires consideration of its scientific and technical limitations, including the composition of current online datasets, and consideration of its scientific validity. Additionally, forensic genetic genealogy needs to be considered in the relevant legal context to determine the best way in which to make use of its potential to generate investigative leads while minimising its impact on individual privacy. This article presents these issues from an Australian perspective, with the observations and conclusions likely to be applicable to other jurisdictions.
ARTICLE | doi:10.20944/preprints201904.0011.v2
Subject: Life Sciences, Genetics Keywords: DNA sequence; helix; nucleotide frequencies; DNA epi-chains; helical antennas; Fröhlich's theory; long-range coherence; epigenetics; quantum biology; binary representation
Online: 14 May 2019 (06:22:48 CEST)
One of creators of quantum mechanics P. Jordan in his work on quantum biology claimed that life's missing laws were the rules of chance and probability of the quantum world. The article presents author’s results of studying frequencies (or probabilities) of nucleotides on so-called epi-chains of long DNA sequences of various eukaryotic and prokaryotic genomes. DNA epi-chains are algorithmically constructed subsequencies of DNA nucleotide sequences. According to the algorithm of construction of any epi-chain of the order n, the epi-chain is such nucleotide subsequence, in which the numerations of adjacent nucleotides differ by natural number n (n = 1, 2, 3, 4,…). Correspondingly each epi-chain of order n ≥ 2 contains n times less nucleotides than the original DNA sequence. The presented results unexpectedly discover that in long single-stranded and double-stranded DNA of any tested genome its DNA epi-chains of different orders n (values n are not too large) have practically identical frequencies (or probabilities) of each kind of nucleotides. These data allow considering DNA as a regular rich set of epi-chains, which can play a certain role in genetic and epigenetic phenomena as the author belives. Appropriate rules of nucleotide frequencies on epi-chains of long DNA sequences are formulated for further their tests on a wider set of genomes. These results testify on existence of long-range coherence in long DNA and remind the Fröhlich's theory of long-range coherence in biological systems. The phenomenological data are discussed from different standpoints: the DNA double helices and helical antennas with circular polarizations of electromagnetic waves; relations with the Fröhlich's theory; numerical analysis of DNA epi-chains under binary representations of nucleotides. Results are useful for developing quantum and algebraic biology.
ARTICLE | doi:10.20944/preprints201810.0406.v1
Online: 18 October 2018 (07:54:20 CEST)
Platinum(II) complexes have been found to be effective against cancer cells. Cisplatin curbs cell replication by interacting with the deoxyribonucleic acid (DNA), eventually leading to cell death and reducing cell proliferation. In order to investigate the ability of platinum complexes to affect cancer cells, two examples from the class of polyflurophenylorganoamidoplatinum(II) complexes were synthesised and tested on isolated DNA. The two compounds trans-[N,N’-bis(1,2,3,5,6-pentafluorophenyl)ethane-1,2-diaminato(1-)](2,3,4,5,6-pentafluorobenzoato)(pyridine)platinum(II) (PFB), and trans-[N,N’-bis(1,2,3,5,6-pentafluorophenyl)ethane-1,2-diaminato(1-)](2,4,6-trimethylbenzoato)(pyridine)platinum(II) (TMB) were compared with cisplatin through their reaction with DNA. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy was applied to analyse the interaction of the Pt(II) complexes with DNA in the hydrated, dehydrated and rehydrated state. These were compared with control DNA in acetone/water (PFB, TMB) and isotonic saline (cisplatin) under the same conditions. Principle Component Analysis (PCA) was applied to compare the ATR-FTIR spectra of the untreated control DNA with spectra of PFB and TMB treated DNA samples. Disruptions in the conformation of DNA treated with the Pt(II) complexes upon rehydration were mainly observed by monitoring the position of the IR-band around 1711 cm-1 assigned to the DNA base-stacking vibration. Furthermore, other intensity changes in the phosphodiester bands of DNA at ~1234 cm-1 and 1225 cm-1 and shifts in the dianionic phosphodiester vibration at 966 cm-1 were observed. The isolated double stranded DNA (dsDNA) or single stranded DNA (ssDNA) showed different structural changes when incubated with the studied compounds. PCA confirmed PFB had the most dramatic effect by denaturing both dsDNA and ssDNA. Both compounds, along with cisplatin, induced changes in DNA bands at 1711, 1088, 1051 and 966 cm-1 indicative of DNA conformation changes. The ability to monitor conformational change with infrared spectroscopy paves the way for a sensor to screen for new anticancer therapeutic agents.
REVIEW | doi:10.20944/preprints201809.0470.v1
Subject: Biology, Plant Sciences Keywords: B chromosome; satellite DNA; mobile element; organelle DNA; chromosome evolution
Online: 24 September 2018 (17:18:03 CEST)
B chromosomes are supernumerary chromosomes which are found in addition to the normal standard chromosomes (A chromosomes). B chromosomes are well known to accumulate several types of repeats. Although the evolution of B chromosomes has been subject of numerous studies, the mechanisms of accumulation and evolution of repetitive sequences is not fully understood. Recently, new genomic approaches have shed light on the origin and accumulation of different classes of repetitive sequences in the process of B chromosome formation and evolution. Here we discuss the impact of repetitive sequences accumulation on the evolution of plant B chromosomes.
ARTICLE | doi:10.20944/preprints202204.0307.v1
Subject: Life Sciences, Cell & Developmental Biology Keywords: receptors; extracellular DNA; cell-surface bound DNA; cell-surface bound RNA
Online: 29 April 2022 (15:04:38 CEST)
Here, our data provide the first evidence for the existence of a previously unknown receptive system formed by novel DNA- and RNA-based receptors in eukaryotes. This system, named the TR-system, is capable of recognizing and generating a response to different environmental factors and has been shown to orchestrate major vital functions of fungi, mammalian cells, and plants.Recently, we discovered the existence of a similar regulatory system in prokaryotes. These DNA- and RNA-based receptors are localized outside of the membrane forming a type of a network around cells that respond to a variety of chemical, biological, and physical factors and enabled the TR-system to regulate major aspects of eukaryotic cell life as follows: growth, including reproduction and development of multicellular structures; sensitivity to temperature, geomagnetic field, UV, light, and hormones; interaction with viruses; gene expression, recognition and utilization of nutrients. The TR-system was also implicated in cell memory formation and was determined to be responsible for its maintenance and the forgetting of preceding events. This system is the most distant receptive and regulatory system of the cell that regulates interactions with the outer environment and governs the functions of other receptor-mediated signaling pathways.
ARTICLE | doi:10.20944/preprints201909.0171.v1
Subject: Mathematics & Computer Science, Other Keywords: Bioinformatics; NGS; DNA sequencing; DNA sequence analysis; amplicons; ultrametric spaces; indexing
Online: 16 September 2019 (16:45:10 CEST)
Here we present 1. a model for amplicon sequencing 2. a definition of the best assignment of a read to a set of reference sequences 3. strategies and structures for indexing reference sequences and computing the best assign- ments of a set of reads efficiently, based on (ultra)metric spaces and their geometry The models, techniques, and ideas are particularly relevant to scenarios akin to 16S taxonomic profiling, where both the number of reference sequences and the read diversity is considerable.
REVIEW | doi:10.20944/preprints201807.0033.v1
Subject: Materials Science, Nanotechnology Keywords: DNA nanotechnology; DNA origami; self-assembly; molecular devices; mechanical movement; robotics
Online: 3 July 2018 (10:03:21 CEST)
Structural DNA nanotechnology provides an excellent foundation for diverse nanoscale shapes that can be used in various bioapplications and materials research. From all existing DNA assembly techniques, DNA origami has proven to be the most robust one for creating custom nanoshapes. Since its invention in 2006, building from the bottom up using DNA has drastically advanced, and therefore, more and more complex DNA-based systems have become accessible. So far, vast majority of the demonstrated DNA origami frameworks are static by nature, but interestingly, there also exist dynamic DNA origami devices that are increasingly coming into view. In this review, we discuss DNA origami nanostructures that perform controlled translational or rotational movement triggered by predefined DNA strands, various molecular interactions and/or other external stimuli such as light, pH, temperature and electromagnetic fields. The rapid evolution of such dynamic DNA origami tools will undoubtedly have a significant impact on molecular scale precision measurements, targeted drug delivery and diagnostics, but they can also play a role in development of optical/plasmonic sensors, nanophotonic devices and nanorobotics for numerous different tasks.
ARTICLE | doi:10.20944/preprints201803.0203.v1
Subject: Physical Sciences, General & Theoretical Physics Keywords: DNA; DNA nanotechnology; patchy particles; Wertheim theory; thermodynamic integration; phase coexistence
Online: 25 March 2018 (16:14:27 CEST)
We present a numerical study in which large-scale bulk simulations of self-assembled DNA constructs have been carried out with a realistic coarse-grained model. The investigation aims at obtaining a precise, albeit numerically demanding, estimate of the free energy for such systems. We then, in turn, use these accurate results to validate a recently proposed theoretical approach that builds on a liquid-state theory, the Wertheim theory, to compute the phase diagram of all-DNA fluids. This hybrid theoretical/numerical approach, based on the lowest order virial expansion and a nearest-neighbor DNA model, can provide, in an undemanding way, a thermodynamic description of DNA associating fluids that is in semi-quantitative agreement with experiments. We show that the predictions of such scheme are as accurate as the ones obtained with more sophisticated methods. We also demonstrate the flexibility of the approach by incorporating non-trivial additional contributions that go beyond the nearest-neighbor model to compute the DNA hybridization free energy.
OPINION | doi:10.20944/preprints201608.0016.v1
Subject: Life Sciences, Molecular Biology Keywords: parallel DNA; antiparallel DNA; PCR; CRISPR; nucleic acid hybridization; microarray; siRNA
Online: 2 August 2016 (10:42:27 CEST)
Many fundamental molecular techniques (PCR, Microarray, Southern and northern hybridization, siRNA, CRISPR/Cas9 etc.) developed so far shows errors. I wish to highlight these molecular techniques are developed on basis of Watson-Crick DNA model, ignoring the concept of parallel stranded DNA. Through this opinion article, I wish to highlight specificity and accuracy of these molecular techniques can be enhanced by considering both parallel and anti parallel hybridization of DNA. Hopefully my views will also solve issue of irreproducibility in life science research.
ARTICLE | doi:10.20944/preprints202106.0705.v1
Online: 29 June 2021 (12:54:42 CEST)
Phenotypes are necessary for genomic evaluations and management. Sometimes genomics can be used to measure phenotypes when other methods are difficult or expensive. Prolificacy of bulls used in multiple-bull pastures for commercial beef production is an example. A retrospective study of 79 bulls aged 2-year-old and older used 141 times in 4-5 pastures across 4 years was used to estimate repeatability from variance components. Traits available before each season’s use were tested for predictive ability. Sires were matched to calves using individual genotypes and evaluating exclusions. A lower cost method of measuring prolificacy was simulated for 5 pastures using the bulls’ genotypes and pooled genotypes to estimate average allele frequencies of calves and of cows. Repeatability of prolificacy was 0.62 ± 0.09. A combination of age-class and scrotal circumference accounted for less than 5 % of variation. Simulated estimation of prolificacy by pooling DNA of calves was accurate. Adding pooling of cow DNA or actual genotypes both increased accuracy about the same. Knowing a bull’s prior prolificacy would help predict future prolificacy for management purposes and could be used in genomic evaluations and research with coordination of breeders and commercial beef producers.
ARTICLE | doi:10.20944/preprints202002.0004.v1
Online: 3 February 2020 (03:27:19 CET)
The ability to predict physical characteristics from DNA presents significant opportunities for forensic science. Giving scientists an ability to make predictions about the donor of genetic material at a crime scene can then give investigators new intelligence leads for cold cases where DNA evidence has not identified any person of interest. However, the interpretation of this new form of intelligence requires careful analysis. The responses to an online survey, conducted in 2018-19, were used to examine how actors in the criminal justice system assess and interpret different types of DNA evidence and intelligence. The groups of focus for the survey were investigators, legal practitioners and the general public (as potential jurors). Several statistically significant effects were identified based on occupation and whether an individual had prior exposure to new DNA technology. Monitoring how those involved in interpreting reports from different types of DNA evidence and intelligence interpret them helps to ensure that decisions are made based on a sound understanding of their capabilities and limitations and may inform broader training and awareness strategies.
Subject: Life Sciences, Biophysics Keywords: double-stranded DNA; DNA dynamical models; correlated oscillations in macromolecules; epigenetic changes
Online: 4 January 2021 (16:35:40 CET)
A fully analytical treatment of the base-pair and codon dynamics in double-stranded DNA molecules is introduced, by means of a realistic treatment which considers different mass values for G, A, T, and C nucleotides and takes into account the intrinsic three-dimensional, helicoidal geometry of DNA in terms of a Hamitonian in cylindrical coordinates. Within the framework of the Peyrard-Dauxois-Bishop model we consider the coupling between stretching and stacking radial oscillations as well as the twisting motion of each base pair around the helix axis. By comparing the linearized dynamical equations for the angular and radial variables when going from the bp local scale to the longer triplet codon scale, we report an underlying hierarchical symmetry. The existence of synchronized collective oscillations of the base-pairs and their related codon triplet units are disclosed from the study of their coupled dynamical equations. The possible biological role of these correlated, long-range oscillation effects in double standed DNA molecules containing mirror-symmetric codons of the form XXX, XX’X, X’XX’, YXY, and XYX is discussed in terms of the dynamical equations solutions and their related dispersion relations.
ARTICLE | doi:10.20944/preprints201811.0575.v1
Subject: Medicine & Pharmacology, Other Keywords: antiretroviral treatment; residual HIV replication; episomal DNA; proviral DNA; antibody quantitation; LPS
Online: 26 November 2018 (08:32:26 CET)
Background: The presence of HIV residual replication markers was investigated among distinct subgroups of individuals on antiretroviral treatment (ART). Methods: One hundred sixteen patients were distributed into 5 treatment groups: first-line suppressive ART with a non-nucleoside analog reverse-transcriptase inhibitor (NNRTI) (n = 26), first-line suppressive ART with boosted protease inhibitors (PI-r) (n = 25), suppressive salvage therapy using PI-r (n = 27), suppressive salvage therapy with PI-r and raltegravir (n = 22) and virologic failure (n = 16). Episomal and total DNA quantitation was evaluated. HIV antibody and LPS quantitation was performed. Results: Episomal DNA was positive in 26% to 38% of individuals under suppressive ART, and it was higher among ART virologic failure group (p = 0.04). HIV proviral load was higher among patients with detectable episomal DNA (p = 0.01). Individuals receiving initial PI-r treatment presented lower HIV antibody (p = 0.027) and LPS (p = 0.029) levels than individuals receiving NNRTI. There was a negative correlation between episomal DNA quantitation and the duration of suppressive ART (p = 0.04), CD4+ T-cell count (p = 0.08), and CD8+ T-cell count (p = 0.07). Conclusions: Residual HIV replication has been inferred among individuals under suppressive ART according to episomal DNA detection. Residual replication may decrease with longer periods of suppressive ART and higher levels of CD4+ and CD8+ T cells. The relationship between episomal DNA and total DNA suggests there is a replenishment of the proviral reservoir. Lower antibody and LPS levels among patients with initial PI-r ART suggest these regimens may more effectively suppress HIV, more effectively decreasing HIV antigenic component.
ARTICLE | doi:10.20944/preprints201806.0298.v1
Subject: Chemistry, Physical Chemistry Keywords: B-DNA; Z-DNA; circular dichroism; calorimetry; enthalpy; conformational transitions; heat capacity
Online: 19 June 2018 (11:37:10 CEST)
High concentrations of Na+ or [Co(NH3)6]3+ can induce the B to Z conformational transition in alternating (dC-dG) oligo and polynucleotides. The use of short DNA oligomers (dC-dG)4 and (dm5C-dG)4 as models can allow a thermodynamic characterization of the transition. Both form right handed double helical structures (B-DNA) in standard phosphate buffer with 115 mM Na+ at 25 oC. However, at 2.0 M Na+ or 200 mM [Co(NH3)6]3+, (dm5C-dG)4 assumes a left handed double helical structure (Z-DNA) while the unmethylated (dC-dG)4 analogue remains right handed under those conditions. We have previously demonstrated that the enthalpy of the transition at 25 oC for either inducer can be determined using isothermal titration calorimetry (ITC) [Ferreira, J. M. & Sheardy, R. D., Biophys. J. 2006, 91, 1–7]. Here, ITC is used to investigate the linkages between temperature, water activity and DNA conformation. We found that the determined enthalpy for each titration varied linearly with temperature allowing determination of the heat capacity change (DCp) between the initial and final states. As expected, the DCp values were dependent upon the cation (i.e. Na+ vs [Co(NH3)6]3+) as well as the sequence of the DNA oligomer (i. e., methylated vs unmethylated). Osmotic stress experiments were carried out to determine the gain or loss of water by the oligomer induced by the titration. The results are discussed in terms of solvent accessible surface areas, electrostatic interactions and the role of water.
REVIEW | doi:10.20944/preprints201703.0195.v1
Subject: Medicine & Pharmacology, Obstetrics & Gynaecology Keywords: melatonin; antioxidants; RNS; ROS; embryo development; DNA integrity; DNA oxidation; gene expression
Online: 27 March 2017 (10:04:31 CEST)
Oxidative and nitrosative stress are a common problem when manipulating gametes in vitro. In vitro development in mammalian embryos is highly affected by culture conditions, especially by reactive oxygen species (ROS) and reactive nitrogen species (RNS), because its absence or over production causes embryo arrest and changes in gene expression. Melatonin in gamete co-incubation during IVF has deleterious or positive effects depending on the concentration used in culture medium, demonstrating the delicate balance that must exist between antioxidant and pro-oxidant activity. Further research is needed to better understand the possible impact of melatonin on the different IVP steps in domestic animals, especially in seasonal breeds where this neuro-hormone system highly regulates its reproduction physiology.
Subject: Life Sciences, Biochemistry Keywords: RecG; SSB; stalled DNA replication fork; DNA repair; DNA replication; helicase; atomic force microscopy; OB-fold; SH3 domain; PXXP motif
Online: 2 April 2020 (04:26:52 CEST)
In E. coli DNA replication forks stall on average once per cell cycle. When this occurs, replisome components disengage from the DNA, exposing an intact, or nearly intact fork. Consequently, the fork structure must be regressed away from the initial impediment so repair can occur. Regression is catalyzed by the powerful, monomeric DNA helicase, RecG. During this reaction, the enzyme couples unwinding of fork arms to rewinding of duplex DNA resulting in the formation of a Holliday junction. RecG works against large opposing forces enabling it to clear the fork of bound proteins. Following subsequent processing of the extruded junction, the PriA helicase mediates reloading of the replicative helicase DnaB leading to the resumption of DNA replication. The single-strand binding protein (SSB) plays a key role in mediating PriA and RecG functions at forks. It binds to each enzyme via linker/OB-fold interactions and controls fork loading sites in a substrate-dependent manner that involves helicase remodeling. Finally, it is displaced by RecG during fork regression. The intimate and dynamic SSB-helicase interactions play key roles in ensuring fork regression and DNA replication restart.
REVIEW | doi:10.20944/preprints201707.0016.v1
Subject: Life Sciences, Biochemistry Keywords: DNA polymerase δ; PDIP46; poldip3; PDIP38; poldip2; DNA replication; enzyme regulation; DNA damage response; p12 subunit; E3 ligases; cell cycle
Online: 10 July 2017 (08:44:53 CEST)
This review focuses on the regulation and modulation of human DNA polymerase δ (Pol δ). The emphasis is on mechanisms that regulate the activity and properties of Pol δ in DNA repair and replication. The areas covered are the degradation of the p12 subunit of Pol δ, which converts it from a heterotetramer (Pol δ4) to a heterotrimer (Pol δ3), in response to DNA damage and also during the cell cycle. The biochemical mechanisms that lead to degradation of p12 are reviewed, as well as the properties of Pol δ4 and Pol δ3 that provide insights into their functions in DNA replication and repair. The second focus of the review involves the functions of two Pol δ binding proteins, PDIP46 and PDIP38, both of which are multi-functional proteins. PDIP46 is a novel activator of Pol δ4, and the impact of this function is discussed in relation to its potential roles in DNA replication. Several new models for the roles of Pol δ3 and Pol δ4 in leading and lagging strand DNA synthesis that integrate a role for PDIP46 are presented. PDIP38 has multiple cellular localizations including the mitochondria, the splicesosomes and the nucleus. It has been implicated in a number of cellular functions, including the regulation of specialized DNA polymerases, mitosis, the DNA damage response, Mdm2 alternative splicing and the regulation of the Nox4 NADPH oxidase.
ARTICLE | doi:10.20944/preprints202009.0300.v1
Subject: Chemistry, Physical Chemistry Keywords: DNA Nucleotides; Transcription; Structural Symmetry
Online: 14 September 2020 (04:39:55 CEST)
To activate gene expression, the initiation of transcription is a highly regulated process involving the interaction of proteins and DNA nucleotides at the promoter site, which consists of a small number of base pairs. As it involves interactions at the atomic scale, it is challenging to determine the mechanism of binding responsible for the great specificity between the amino acid residuals comprising the transcription binding protein and the DNA nucleotides comprising the promoter. Here, a new approach to characterize the transcription initiation process is developed and verified from analysis of comparative pharmacological efficacy data and elemental modeling. The newly developed description of a mechanism for transcription initiation involves the direct binding of small molecule ligands of approximately twenty carbon atoms, which are both structurally symmetric to DNA nucleotides, and also chemically complementary in its functional groups for interaction with the oxygen element at the carbon two position of thymine and with the phosphodiester chain. The results indicate that the activating ligands are transported to the DNA nucleotide promoter site by protein transcription factors, which serve as delivery vectors, for transfer of the ligand to the DNA nucleotide pairs. The ligands examined in this study include the steroid hormones, synthetic steroid molecules, derivatives of vitamin D, and prostaglandins, particularly PGJ2 and 15d-PGJ2. The transcription factors evaluated include glucocorticoid receptors, VDR, PPAR, and TBP. Through the developments, it is shown that because of the chemically complementary binding of the ligand to DNA nucleotide pairs, the resultant intermolecular complex produces three hydrogen bonds for the A-T and T-A configurations, which matches that of G-C and C-G. The orientation of the nucleotide base pairs is also seen to adjust as an inversion of the nominal position of the nucleobases to a dimer configuration presented via TBP transcription factor. The developments comprise a new approach to characterizing the initiation of the transcription process comprising the direct binding and interaction of ligands with DNA nucleotides as verified through comparative analysis of pharmacological activity and through perfect structural correspondence between the steroid hormone class as ligands with Watson-Crick DNA nucleotide pairings.
ARTICLE | doi:10.20944/preprints201811.0164.v1
Online: 7 November 2018 (14:24:53 CET)
We apply hierarchical clustering (HC) of DNA k-mer counts on multiple Fastq files. The tree structures produced by HC may reflect experimental groups and thereby indicate experimental effects, but clustering of preparation groups indicates the presence of batch effects. Hence, HC of DNA k-mer counts may serve as an unspecific diagnostic device. In order to provide a simple applicable tool we implemented sequential analysis of Fastq reads with low memory usage in an R package (seqTools) available on Bioconductor. The approach is validated by analysis of Fastq file batches containing RNAseq data. Analysis of three Fastq batches downloaded from ArrayExpress indicated experimental effects. Analysis of RNAseq data from two cell types (dermal fibroblasts and Jurkat cells) sequenced in our facility indicate presence of batch effects. The observed batch effects were also present in reads mapped to the human genome and also in reads filtered for high quality (Phred > 30). We propose, that hierarchical clustering of DNA k-mer counts provides an unspecific diagnostic tool and a quality criterion and for RNAseq experiments.
REVIEW | doi:10.20944/preprints201810.0500.v3
Subject: Chemistry, Other Keywords: DNA repair; long non-coding RNA; microRNA; DNA damage; double-strand breaks; NHEJ; HR
Online: 26 October 2018 (10:22:45 CEST)
DNA double-strand breaks (DSBs) are deleterious lesions that are generated in response to ionizing radiation or replication fork collapse that can lead to genomic instability and cancer. Eukaryotes have evolved two major pathways, namely homologous recombination (HR) and non-homologous end joining (NHEJ) to repair DSBs. Whereas the roles of protein-DNA interactions in HR and NHEJ have been fairly well defined, the functions of small and long non-coding RNAs and RNA-DNA hybrids in the DNA damage response is just beginning to be elucidated. This review summarizes recent discoveries on the identification of non-coding RNAs and RNA-mediated regulation of DSB repair
ARTICLE | doi:10.20944/preprints202202.0118.v1
Subject: Chemistry, Analytical Chemistry Keywords: protein-DNA interactions; DNA recognition; transcription factors; DNA binding domains; con-formational change; nuclear magnetic resonance; circular dichroism; control of gene expression; homeodomains.
Online: 8 February 2022 (14:53:06 CET)
Transcription factors must scan genomic DNA, recognize the cognate sequence of their control element(s), and bind tightly to them. The DNA recognition process is primarily carried out by their DNA binding domains (DBD), which interact with the cognate site with high affinity and more weakly with any other DNA sequence. DBDs are generally thought to bind to their cognate DNA without changing conformation (lock-and-key). Here we used nuclear magnetic resonance and circular dichroism to investigate the interplay between DNA recognition and DBD conformation in the Engrailed homeodomain (EnHD), as model case for the homeodomain family of eukaryotic DBDs. We found that the conformational ensemble of EnHD is rather flexible and becomes more structured as ionic strength increases following a Debye-Hückel’s dependence. Our analysis indicates that EnHD’s response to ionic strength is mediated by a built-in electrostatic spring-loaded latch that operates as conformational transducer. We also found that, at moderate ionic strengths, EnHD changes conformation upon binding to cognate DNA. This change is of larger amplitude and somewhat orthogonal to the response to ionic strength. As a consequence, very high ionic strengths (e.g. 700 mM) block the electrostatic-spring-loaded latch and binding to cognate DNA becomes lock-and-key. However, the interplay between EnHD conformation and cognate DNA binding is robust across a range of ionic strengths (i.e. 45 to 300 mM) that covers the most physiologically-relevant conditions. Therefore, our results demonstrate the presence of a mechanism for the conformational control of cognate DNA recognition on a eukaryotic DBD. This mechanism can function as a signal transducer that immediately locks the DBD in place upon encountering the cognate site during active DNA scanning. The electrostatic-spring-loaded latch of EnHD can also enable the fine control of DNA recognition in response to local/temporal changes in ionic strength induced by variate physiological processes.
REVIEW | doi:10.20944/preprints202202.0009.v2
Subject: Life Sciences, Genetics Keywords: satellite DNA; repetitive DNA; tandem repeats; classical human satellites; HSATI; HSATII; HSATIII; HSat1; HSat2; HSat3
Online: 28 April 2022 (10:18:37 CEST)
The classical human satellite DNAs, also referred to as human satellites 1, 2 and 3 (HSat1, HSat2, HSat3, collectively HSat1-3) constitute the largest individual arrays of tandemly repeated DNA sequences in the genome. Even though they were among the first human DNA sequences to be isolated and characterized at the dawn of molecular biology, HSat1-3 have been left behind in the genomics era and remain among the most enigmatic sequences in the human genome. Although HSat1-3 total roughly 3% of the genome on average, they were almost entirely missing from the human genome reference assembly for 20 years. Recently, the Telomere-to-Telomere Consortium produced the first truly complete assembly of a human genome, including the enormous HSat1-3 arrays, opening them up for a new wave of discovery. Towards this end, here, I provide an account of the history and current understanding of HSat1-3 genomics, evolution, and roles in disease.
REVIEW | doi:10.20944/preprints202202.0018.v1
Subject: Biology, Ecology Keywords: DNA metabarcoding; pollen; pollinators; pollen metabarcoding; plant-pollinator interactions; eDNA; DNA barcoding, honeybees; bumblebees; hoverflies
Online: 1 February 2022 (16:24:01 CET)
The identification of floral visitation by pollinators provides an opportunity to improve our understanding of the fine-scale ecological interactions between plants and pollinators, contributing to biodiversity conservation and promoting ecosystem health. In this review we outline the various methods which can be used to identify floral visitation, providing a comparison between molecular and non-molecular methods. We review the literature covering the ways in which DNA metabarcoding has been used to answer ecological questions relating to plant use by pollinators and discuss the findings of this research. We present detailed methodological considerations for each step of the metabarcoding workflow, from sampling through to amplification and finally bioinformatic analysis. Detailed guidance is provided to researchers for utilization of these techniques, emphasizing the importance of standardization of methods and improving the reliability of results. Future opportunities and directions of using molecular methods to analyze plant-pollinator interactions are then discussed.
REVIEW | doi:10.20944/preprints201810.0251.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: EGFET; ISFET; electrochemical cell; enzymatic biosensor; DNA–DNA biosensor; immunosensor; antigen–antibody biosensor; ionic sensor
Online: 12 October 2018 (04:38:42 CEST)
Since 1970s, a great deal of attention has been paid to the development of semiconductor–based biosensors because of the numerous advantages they offer, including high sensitivity, faster response time, miniaturization, and low–cost manufacturing for quick biospecific analysis with reusable features. Commercial biosensors have become highly desirable in the fields of medicine, food, environmental monitoring as well as military applications (e.g., Hoffmann–La Roche, Abbott Point of Care, Orion High technologies, etc.), whereas increasing concerns on the food safety and health issues have resulted in the introduction of novel legislative standards for these sensors. Numerous devices have been developed for monitoring of biological–processes such as nucleic–acid hybridization, protein–protein interaction, antigen–antibody bonds and substrate–enzyme reactions, just to name a few. Since 1980s scientific interest moved to the development of semiconductor–based devices which also include integrated front–end electronics, such as the extended–gate–field–effect–transistor biosensor which is one of the first miniaturized chemical sensors. This work is intended to be a review of the state of the art focused on the development of biosensors based extended–gate–field–effect–transistor within the field of bioanalytical applications, which will highlight the most recent research works reported in the literature. Moreover, a comparison among the diverse EGFET devices will be presented giving particular attention to the materials and technologies.
ARTICLE | doi:10.20944/preprints201701.0086.v4
Subject: Life Sciences, Molecular Biology Keywords: spermine; cyclooctaoxygen; DNA; selenium; glyphosate; AMPA
Online: 29 January 2023 (03:10:50 CET)
Background: Oxygen exists in two gaseous (dioxygen and ozone) and six solid allotropic modifications. An additional allotropic modification of oxygen, the cyclooctaoxygen, was predicted to exist in 1990. The first synthesis and characterization of cyclooctaoxygen as its sodium crown complex, isolated in the form of three cytosine nucleoside hydrochloride complexes, was reported in 2016.Results: The sperminium hydrogen phosphate/cyclooctaoxygen sodium complex is calculated to cover the actively transcribed regions (2.6%) of bovine lymphocyte interphase genome. Cyclooctaoxygen seems to be naturally absent in hypoxia-induced highly condensed chromatin, taken as a model for eukaryotic metaphase/anaphase/early telophase mitotic chromatin. Hence, it is proposed that the cyclooctaoxygen sodium-bridged sperminium hydrogen phosphate and selenite coverage serves as an epigenetic shell of actively transcribed gene regions in eukaryotic ‘open’ euchromatin DNA. Cyclooctaoxygen sodium-bridged sperminium hydrogen selenite was calculated to serve as a marker shell component at ATG start codons in human euchromatin DNA mRNA genes, both at the translation initiation triplet and at 5'-untranslated region upstream ATGs. The total herbicide glyphosate (ROUNDUP®) and its metabolite (aminomethyl)phosphonic acid (AMPA) are proved to represent ‘epigenetic poisons’, since they both selectively destroy the cyclooctaoxygen sodium complex. This definition is of reason, since the destruction of cyclooctaoxygen is certainly sufficient to bring the protection shield of human euchromatin into collateral epigenetic collapse.Conclusions: The total herbicide glyphosate and its environmental metabolite (aminomethyl)phosphonic acid (AMPA) can be associated in vitro with catalytic detoriation of eukaryotic euchromatin genetic information.General Significance: The epigenetic shell of eukaryotic euchromatin is susceptible to decay induced by catalytic epigenetic poisons threatening eukaryotic genomic heritage.
ARTICLE | doi:10.20944/preprints202301.0089.v1
Subject: Medicine & Pharmacology, Other Keywords: Strongyloidiasis; Strongyloidesstercoralis; Strongyloidesratti; DNA-molecular techniques
Online: 5 January 2023 (02:09:06 CET)
Background: Strongyloidiasis, a neglected disease caused by intestinal nematodes of the genus Strongyloides, is endemic to tropical and subtropical areas such as Vietnam. The morphological diagnosis of larvae by Hara Mori culture technique and microscopicare are considered the standard diagnostic procedures in the endemic areas of Strongyloides spp. However, they could only identify the genus, not the species of Strongyloides. DNA-molecular techniques which are highly sensitive and more cost-effective have been increasingly utilized in detection of Strongyloides species. This study aims to determine prevalence and the species of Strongyloides among resident population in Duc Hoa district, Long An province, Southern Vietnam. Methods: A cross-sectional study was conducted using 1,190 stool samples collected in Duc Hoa district, Long An province, Vietnam, from July, 2017 to November 2018. The stool specimens were transported to the Laboratory of Medical Parasitology, Pham Ngoc Thach University of Medicine within two hours of collection at an appropriate temperature of 25 oC. All samples were stored at 2 - 8°C and processed within 48 hours for microscopic examination. Molecular detection was carried out at Laboratory of Molecular Biology, Pham Ngoc Thach University of Medicine, Hochiminh city, VietNam. Results: Of the 1,190 samples tested, Strongyloides spp. larvae were detected in 79 specimens (6.6%) by two classical parasitological methods, namely direct microscopy and the modified Harada-Mori filter paper culture. DNA was extracted from 70 of the 79 samples of Strongyloides spp. larvae, which was subsequently characterized by real-time PCR amplification of the 18S and 28S regions of the rDNA gene. The results showed that 97.1% of the DNA samples were S. stercoralis, 2.9% were co-infections with S. ratti and S. stercoralis, and 2.9% belonged to S. ratti. For all 14 isolates, nucleotide sequencing was compared with other human pathogenic species of Strongyloides whose sequences are available in GenBank. The identity of 12/14 sequences were confirmed as S. stercoralis with a high level of similarity (91.3% - 100%) and over 98% for S. ratti. Between the two co-infection samples, the higher similarity belonged to S. stercoralis. Conclusion: A molecular amplification of small subunit ribosome RNA followed by sequence analysis has been proved to be a suitable method for discrimination of Strongyloides spp. retrieved from stool samples.
ARTICLE | doi:10.20944/preprints202204.0283.v1
Subject: Earth Sciences, Environmental Sciences Keywords: molecular ecology; functional diversity; DNA sequencing
Online: 28 April 2022 (10:31:56 CEST)
Wildfires have continued to increase in frequency and severity in Southern California due in part to climate change. To gain a further understanding of microbial soil communities’ response to fire and functions that may enhance post-wildfire resilience, soil fungal and bacterial microbiomes were studied from different wildfire areas in the Gold Creek Preserve within the Angeles National Forest using 16S, FITS, 18S, 12S, PITS, and CO1 amplicon sequencing. Sequencing datasets from December 2020 and June 2021 samplings were analyzed using DNA Subway, ranacapa, stats, vcd, EZBioCloud, and mixomics. Significant differences were found among bacterial and fungal taxa associated with different fire areas in the Gold Creek Preserve. There was evidence of seasonal shifts in the alpha diversity of the bacterial communities. In the sparse partial least squares analysis, there were strong associations (r>0.8) between longitude, elevation, and a defined cluster of Amplicon Sequence Variants (ASVs). The Chi-square test revealed differences in fungi:bacteria (F:B) proportions between different trails (p=2*10^-16). sPLS results focused on a cluster of Green Trail samples with high elevation and longitude. Analysis revealed the cluster included the post-fire pioneer fungi Pyronema, and Tremella. Chlorellales algae, and pathogenic Fusarium sequences were elevated. Bacterivorous Corallococcus, which secretes antimicrobials, and bacterivorous flagellate Spumella, were associated with the cluster. There was functional redundancy in clusters that were differently composed, but shared similar ecological functions. These results implied a set of traits for post fire resiliency. These included photo-autotrophy, mineralization of pyrolyzed organic matter and aromatic/oily compounds, pathogenicity and parasitism, antimicrobials, and N-metabolism.
REVIEW | doi:10.20944/preprints202201.0474.v1
Subject: Life Sciences, Biotechnology Keywords: Biosensors; DNA; RNA; Cancer; Biomarkers; Proteomics
Online: 31 January 2022 (21:21:33 CET)
The deadliest disease in the world, cancer, kills many people every year. The early detection is the only hope for the survival of malignant cancer patients. As a result, in the preliminary stages of , the diagnosis of cancer biomarkers at the cellular level is critical for improving cancer patient survival rates. For decades, scientists have focused their efforts on the invention of biosensors. Biosensors, in addition to being employed in other practical scenarios, can essentially function as cost effective and highly efficient devices for this purpose. Traditional cancer screening procedures are expensive, time-consuming, and inconvenient for repeat screenings. Biomarker-based cancer diagnosis, on the other hand, is rising as one of the most potential tools for early detection, disease progression monitoring, and eventual cancer treatment. As Biosensor is an analytical device, it allows the selected analyte to bind to the biomolecules being studied (– for example RNA, DNA, tissue, proteins, cells). They can be divided based on the kind of biorecognition or transducer elements on the sensor. Most biosensor analyses necessitate the analyte being labeled with a specific marker. In this review article, the application of distinct variants of biosensors against cancer has been described.
ARTICLE | doi:10.20944/preprints202103.0656.v1
Subject: Materials Science, Biomaterials Keywords: Silicene; Graphene; DNA; hybridization; Biosensor; ISFETs
Online: 26 March 2021 (10:58:26 CET)
Two-dimensional silicon allotrodes– also called Sinicene– have recently experienced intensive scientific research interest due to their unique electrical, mechanical, and sensing characteristics. A novel silicene based nano-material has been enticed great amenities, partially because of its uniformity with graphene. Silicene is a highly sensitive for numerous sensors based on molecular sensing as pH sensor, gas sensor, ion sensor and biosensing are Deoxyribonucleic acid (DNA) nucleobase sensor, photonic sensor, cell-based biosensor, glucose sensor, and bioelectric nose sensor. Nowadays genetic research based on DNA hybridization, which is a vital tools for sensing material and it has various detection methods. Among of them, the detection method is frequency readout used to a label-free detection of DNA hybridization. In this paper we have compared the graphene and silicene quantum capacitance that has been proposed for a DNA hybridization detection method on wireless readout. These method shows, the strands of mismatched and complementary DNA have in different range of frequency to identify output efficiency. With respect to DNA concentration the output of silicene is almost sharply linear than graphene. In addition of field effect transistor, silicene opens a new opportunities due to its band gap whereas graphene indicates zero band gap. It can be stated that silicene is much more reliable as well as much stronger than multi-layered graphene.
ARTICLE | doi:10.20944/preprints202211.0528.v2
Subject: Life Sciences, Genetics Keywords: DNA strands, complementary replication, DNA alphabets, binary opposition, binary numbers, dyadic groups, matrices, algebras, split-quaternions, root-complementarity.
Online: 20 December 2022 (01:29:16 CET)
This article is devoted to results of in-depth analysis of the system of binary-oppositional structures in DNA n-plet alphabets and their algebraic-matrix representations. These results show that the molecular complementary replication of DNA strands is accompanied by the presence of an algebraic version of the principle "like begets like" in matrix representations of DNA alphabets having internal structures. This algebraic version is based on binary-oppositional structures in the genetic molecular system, which can be represented by bynary numbers and corresponding matrices of DNA alphabets. The received results allow thinking that the phenomenon "like begets like" (or a complementary replication in a wide sense) is a systemic in the genetic organization and is connected with algebraic features of biological organization. Correspondingly, the biological principle "like begets like" can be additionally modeled by algebraic-matrix methods and approaches. Such algebraic-matrix modeling of the genetic coding system gives new ways for studying and understanding a key role of the named principle in genetic and other inherited physiological complexes. The author believes that further study of the algebraic relationships of the genetic system and inherited physiological complexes will be increasingly revealing the key biological role of the ancient principle "like begets like" at different levels of biological organization.
REVIEW | doi:10.20944/preprints202001.0353.v1
Subject: Life Sciences, Genetics Keywords: chromothripsis; structural variants; DNA-repair; DNA-repair disorders; DNA-double strand breaks (DSBs); ataxia telangiectasia mutated (ATM); ataxia-telangiectasia and Rad3-related (ATR); TP53; micronuclei; chromosome pulverization.
Online: 29 January 2020 (11:58:58 CET)
Chromothripsis is a mutational mechanism leading to complex and relatively clustered chromosomal rearrangements resulting in diverse phenotypic outcomes depending on the involved genomic landscapes. It may occur both in the germ and the somatic cells resulting in congenital and developmental disorders and cancer, respectively. Asymptomatic individuals may be carriers of chromotriptic rearrangements and experience recurrent reproductive failures when two or more chromosomes are involved. Several mechanisms are postulated to underly chromothripsis. The most attractive hypothesis involves chromosome pulverization in micronuclei followed by incorrect reassembly of fragments through DNA repair to explain the clustered nature of the observed complex rearrangements. Moreover, exogenous or endogenous DNA damage induction and dicentric bridge formation may be involved. Chromosome instability is commonly observed in the cells of patients with DNA-repair disorders, such as ataxia telangiectasia, Nijmegen breakage syndrome and Bloom syndrome. In addition, germline variations of TP53 have been associated with chromothripsis in Sonic-Hedgehog medulloblastoma and acute myeloid leukemia. In the present review, we focus on the underlying mechanisms of chromothripsis and the involvement of defective DNA-repair genes resulting in chromosome instability and chromothripsis-like rearrangements.
REVIEW | doi:10.20944/preprints202104.0602.v3
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: carcinogenesis; cancer treatment; cervical cancer; DNA synthesis; free-radical; retinoblastoma; ribonucleotide reductase; somatic mutation theory (SMT)
Online: 28 December 2021 (10:53:54 CET)
The presence of mutated genes strongly correlates with the incidence of cancer. Decades of research, however, has not yielded any specific causative gene or set of genes for the vast majority of cancers. The Cancer Genome Atlas program was supposed to provide clarity but it only gave much more data without any accompanying insight into how the disease begins and progresses. It may be time to notice that epidemiological studies consistently show that the environment, not genes, has the principal role in causing cancer. Since carcinogenic chemicals in our food, drink, air and water are the primary culprits, we need to look at the biochemistry of cancer, with a focus on enzymes which invariably facilitate transformations in a cell. In particular, attention should be paid to the rate-limiting enzyme in DNA synthesis, ribonucleotide reductase (RnR) whose activity is tightly linked to tumor growth. Besides circumstantial evidence that cancer is induced at this enzyme’s vulnerable free-radical-containing active-site by various carcinogens, its role in initiating retinoblastoma and HPV-related cervical cancers is well documented. Blocking the activity of malignant RnR is a certain way to arrest cancer.
ARTICLE | doi:10.20944/preprints202107.0151.v1
Subject: Life Sciences, Biochemistry Keywords: biological invasions; fish; DNA; barcoding; primers; identification
Online: 6 July 2021 (13:28:46 CEST)
Reliable species identification is critical for detection and monitoring of biological invasions. In this study, we propose four sets of primers for efficient amplification of several loci, including the mitochondrial cytochrome oxidase-c (COI) subunit I gene which is a basis for DNA barcoding. This set of primers gives a shorter product which can be used in high-throughput sequencing systems for metabarcoding purposes. Another mitochondrial locus encoding the large ribosomal subunit (16S) may be useful to study the population structure and as an additional source of information in the metabarcoding of communities. We propose to use a set of primers for the nuclear locus of the small ribosomal subunit (18S) as a positive control and to verify the results of the barcoding. Our proposed sets of primers demonstrate a high amplification efficiency and a high specificity both for freshwater alien and indigenous fishes. The proposed research design makes it possible to carry out extremely cheap studies on the assessment of biological diversity using genetic analysis without expensive equipment, and with the technique for conducting laboratory work and processing of the results available to any researcher. The paper also presents original data on the genetic polymorphism of all mass alien fish species in the Volga-Kama region. High efficiency of DNA identification based on our primers is shown as compared to traditional monitoring of biological invasions.
REVIEW | doi:10.20944/preprints202106.0629.v1
Subject: Life Sciences, Biochemistry Keywords: pancreatic cancer; epigenetics; metastasis; enhancer; DNA methylation
Online: 25 June 2021 (16:05:34 CEST)
Pancreatic cancer is the third leading cause of cancer-related deaths in the United States. Pancreatic ductal adenocarcinoma (PDA) is the most common (90%) and aggressive type of pancreatic cancer. Genomic analyses of PDA specimens have identified the recurrent genetic mutations that drive PDA initiation and progression. However, the underlying mechanisms that further drive PDA metastasis remain elusive. Despite many attempts, no recurrent genetic mutation driving PDA metastasis has been found, suggesting that PDA metastasis is driven by epigenetic fluctuations rather than genetic factors. Therefore, establishing epigenetic mechanisms of PDA metastasis would facilitate the development of successful therapeutic interventions. In this review, we provide a comprehensive overview on the role of epigenetic mechanisms in PDA as a critical contributor on PDA progression and metastasis. In particular, we explore the recent advancements elucidating the role of nucleosome remodeling, histone modification, and DNA methylation in the process of cancer metastasis.
REVIEW | doi:10.20944/preprints202103.0176.v1
Subject: Materials Science, Biomaterials Keywords: DNA nanotechnology; Protein Nanotechnology; Self-assembly; Bionanomaterials
Online: 5 March 2021 (09:13:43 CET)
Proteins and DNA exhibit key physical chemical properties that make them advantageous for building nanostructures with outstanding features. Both DNA and protein nanotechnology have growth notably and proved to be fertile disciplines. The combination of both types of nanotechnologies is helpful to overcome the individual weaknesses and limitations of each one, paving the way for the continuing diversification of the structural nanotechnologies. Recent studies have implemented a synergistic combination of both biomolecules to assemble unique and sophisticate protein-DNA nanostructures. These hybrid nanostructures are highly programmable and display remarkable features that create new opportunities to build in the nanoscale. This review focuses on the strategies deployed to create hybrid protein-DNA nanostructures. Here, we will discuss strategies such as polymerization, spatial directing and organizing, coating, rigidizing or folding DNA into particular shapes or moving parts. The enrichment of structural DNA nanotechnology by incorporating protein nanotechnology has been clearly demonstrated and still shows a large potential to create useful and advanced materials with cell-like properties or dynamic systems. It can be expected that structural protein-DNA nanotechnology will open new avenues in the fabrication of nano-assemblies with unique functional applications and enrich the toolbox of bionanotechnology.
ARTICLE | doi:10.20944/preprints202012.0003.v2
Subject: Life Sciences, Biochemistry Keywords: DNA repair; NHEJ; synthetic lethality; genetic interaction
Online: 15 December 2020 (10:41:58 CET)
Non-homologous end-joining (NHEJ) is a major DNA repair pathway in mammalian cells that recognizes, processes and fixes DNA damages throughout the cell cycle, and is specifically important for homeostasis of post-mitotic neurons and developing lymphocytes. Neuronal apoptosis increases in the mice lacking NHEJ factors Ku70 and Ku80. Inactivation of other NHEJ genes, either Xrcc4 or Lig4, leads to massive neuronal apoptosis in the central nervous system (CNS) that correlates with embryonic lethality in mice. Inactivation of either Paxx, Mri or Dna-pkcs NHEJ gene results in normal CNS development due to compensatory effects of Xlf. Combined inactivation of Xlf/Paxx, Xlf/Mri and Xlf/Dna-pkcs, however, results in late embryonic lethality and high levels of apoptosis in CNS. To determine the impact of NHEJ factors on early stages of neurodevelopment, we isolated neural stem and progenitor cells from mouse embryos and investigated proliferation, self-renewal and differentiation capacity of these cells lacking either Xlf, Paxx, Dna-pkcs, Xlf/Paxx or Xlf/Dna-pkcs. We found that XLF, DNA-PKcs and PAXX maintain the neural stem and progenitor cell populations and neurodevelopment in mammals, which is particularly evident in the double knockout models.
REVIEW | doi:10.20944/preprints202011.0356.v1
Subject: Life Sciences, Biochemistry Keywords: Sanger Sequencing; DNA Sequencing; Chain Termination Sequencing
Online: 12 November 2020 (17:20:07 CET)
The world has now entered into a replacement era of genomics due to the continued advancements within the next generation high throughput sequencing technologies, which incorporates sequencing by synthesis-fluorescent in place sequencing (FISSEQ), pyrosequencing, sequencing by ligation using polony amplification, supported oligonucleotide detection (SOLiD), sequencing by hybridization alongside sequencing by ligation, and nanopore technology. Great impacts of those methods are often seen for solving the genome related problems of plant and Animalia which will open the door of a replacement era of genomics. This might ultimately overcome the Sanger sequencing that ruled for 30 years. NGS is predicted to advance and make the drug discovery process more rapid.
Subject: Materials Science, Biomaterials Keywords: DNA charge transfer; effective Hamiltonians; renormalization techniques
Online: 6 November 2020 (09:05:14 CET)
By introducing a suitable renormalization process the charge carrier and phonon dynamics of a double-stranded helical DNA molecule is expressed in terms of an effective Hamitonian describing a linear chain, where the renormalized transfer integrals explicitly depend on the relative orientations of the Watson-Crick base pairs, and the renormalized on-site energies are related to the electronic parameters of consecutive base pairs along the helix axis, as well as to the low-frequency phonons dispersion relation. The existence of synchronized collective oscillations enhancing the π-π orbital overlapping among different base pairs is disclosed from the study of the obtained analytical dynamical equations. The role of these phonon-correlated, long-range oscillation effects on the charge transfer properties of double standed DNA homopolymers is discussed in terms of the resulting band structure.
REVIEW | doi:10.20944/preprints202011.0163.v1
Subject: Biology, Anatomy & Morphology Keywords: Sanger Sequencing; DNA Sequencing; Chain Termination Sequencing
Online: 3 November 2020 (14:41:11 CET)
DNA sequencing methods were first developed more than 20 years ago with the publication of two approaches to sequencing methodology that became known as Sanger sequencing (1), based on enzymatic synthesis from a single-stranded DNA template with chain termination using dideoxynucleotides (ddNTPs) and Maxim-Gilbert sequencing (2),which involved chemical degradation ofend-radio-labeled DNA fragments. Both methods relied on four-lane,high resolution polyacrylamide gel electrophoresis to separate the labeled fragment and allow the base sequence to be read in a staggered ladder-like fashion. Sanger sequencing was technically easier and faster, and thus became the main DNA sequencing method for the vast majority of applications.
REVIEW | doi:10.20944/preprints202010.0349.v1
Subject: Biology, Anatomy & Morphology Keywords: neurodegeneration; tauopathies; cancer, Tau protein, DNA protection
Online: 16 October 2020 (12:31:41 CEST)
For its microtubule-binding properties, the expression level of the neurodegeneration-associated protein Tau is pondered as a potential modifier of cancer resistance to chemotherapy since decades. Indeed, Tau binds microtubules at the same site as taxanes, a class of chemotherapeutic drugs designed to stabilize the microtubule network in order to stall cell division and to induce tumor cell death. Whilst independent studies report the association between low Tau expression and superior taxane response, the data were refused by a meta-analysis, suggesting interference of other parameters. Unpredictably, Tau expression level was identified as a prognostic cancer marker, whereby its positive or negative predictive value for survival depended on the cancer type. With recent experimental evidence linking Tau to P53 signaling, DNA stability and protection and to the implication of Tau in cancer is strengthened. The identification of a role of Tau at the interface between two major aging-related disorder families, neurodegeneration and cancer, offers clues for the epidemiological observation inversely correlating these disorders. Elucidating how Tau is mechanistically implicated in cellular pathways common to these devastating illnesses may extend the Tau-targeting therapeutic opportunities to cancer.
TECHNICAL NOTE | doi:10.20944/preprints202009.0683.v1
Subject: Chemistry, Analytical Chemistry Keywords: DNA extraction; normal; patients; protocol; frozen blood
Online: 28 September 2020 (10:52:59 CEST)
Herein, we describe a highly efficient, non-complicated, and non-organic procedure to overcome the negative effect of chemotherapeutic drugs on the quality of the extracted DNA by applying several modulations in cell washing, suspension, and lysis of cells treated with these drugs. In this protocol, 500µl were extracted from patients who received systemic sessions of chemotherapy. The validity of this protocol for digestion with restriction endonucleases and both conventional and real-time polymerase chain reaction were tested. This protocol proved obvious purity (1.8±0.02 and 2.1±1.2, for A260/280 and A260/230, respectively) and adequate yields (10±2.24) µg/100 ml. The positive results of validation experiments proved the validity of the extracted DNA for downstream applications of molecular biology. In addition to the proven efficiency of this protocol to extract DNA from normal samples, its validity was also confirmed from patients who were exposed to chemotherapy. This entails a novel approach to extract a molecular biology grade DNA without having inhibitors against enzymes used in digestion, amplification, and subsequent sequencing even after the systemic sessions with several doses of chemotherapy.
ARTICLE | doi:10.20944/preprints202008.0562.v1
Online: 26 August 2020 (09:10:14 CEST)
Introduction: The tumour suppressor protein p53 commonly referred to as guardian of the genome plays important role in preserving the genome through the regulation of programmed cell death, DNA repair, energy metabolism, cell cycle entry or exit and senescence. Mutations in p53 can either result to a loss of tumour suppressor function or gain of oncogenic properties. Hence, mutations in p53 are the most frequent genetic mutational alteration in human cancers, associated with worse prognosis and more aggressive disease outcome. Methods: To assess the mutational hotspots and conserved regions of p53, I analyzed 76 complete p53 protein sequences covering whole exons from the NCBI GenBank database. Multiple sequence alignment (MSA) was done using ClustalX version 2.1. Results: Thirty-five (19) mutations were identified with more frequent mutations in amino acid (aa) position 72 and 79 (Exon 4), amino acid deletion in codon 112-122 (Exon 4), codon 213 (Exon 6), codon 248 (Exon 7), codon 273 (Exon 8) and codon 278 (Exon 8). Mutations at amino acid position 79, 248, 278 located in the DNA-binding domain exhibited more than one alteration in same position. Conclusions: Findings from this study revealed the prevalence of mutations in the DNA binding domain of p53 and the structure-function effect of the mutations. Assessing the pattern and frequency of p53 alterations, and analyzing it thoroughly for each carrier, could help in identifying correlations between p53 status and outcome and possible candidate for gene therapy.
COMMUNICATION | doi:10.20944/preprints201911.0193.v1
Online: 17 November 2019 (00:55:26 CET)
Chan and colleagues in their paper titled “Human origins in a southern African palaeo-wetland and first migrations” (https://www.nature.com/articles/s41586-019-1714-1) report 198 novel whole mitochondrial DNA (mtDNA) sequences and infer that ‘anatomically modern humans’ originated in the Makgadikgadi–Okavango palaeo-wetland of southern Africa around 200 thousand years ago. This claim relies on weakly informative data. In addition to flawed logic and questionable assumptions, the authors surprisingly disregard recent evidence and debate on human origins in Africa. As a result, the emphatic and high profile conclusions of the paper are unjustified.
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: whole exome sequencing; melanoma; circulating tumor dna
Online: 4 October 2019 (10:35:02 CEST)
The use of circulating cell-free (cf) DNA to monitor cancer progression and response to therapy has significant potential but there is only limited data on whether this technique can detect the presence of low frequency subclones that may ultimately confer therapy resistance. In this study, we sought to evaluate whether whole-exome sequencing of cfDNA can accurately profile the mutation landscape of metastatic melanoma. We used whole-exome sequencing (WES) to identify variants in matched tumor-derived genomic (g) DNA and plasma-derived cfDNA isolated from a cohort of 10 metastatic cutaneous melanoma patients. WES parameters such as sequencing coverage and total sequencing reads were comparable between gDNA and cfDNA. There was significant concordance between gDNA and cfDNA based on the total number of variants identified and the degree of overlap in variants which was independent of the site of tumor biopsy. The mutant allele frequency of common single nucleotide variants was lower in cfDNA reflecting lower read depth and dilution of circulating tumor DNA in the circulation by other cfDNA species. In addition to known melanoma driver mutations, several other melanoma-associated mutations were found to be concordant between matched gDNA and cfDNA. This study highlights that WES of cfDNA can capture clinically-relevant mutations present in melanoma metastases, but does not appear to provide any additional unique information on tumor heterogeneity. Targeted deep sequencing may be required to detect low frequency genomic aberrations known for predicting therapy resistance.
ARTICLE | doi:10.20944/preprints201909.0170.v1
Subject: Life Sciences, Other Keywords: 16S analysis, metagenomics, amplicons, bioinformatics, DNA sequencing
Online: 16 September 2019 (16:41:43 CEST)
Here we describe ARSA-16S, a tool and accompanying reference database for the analysis of bacterial 16S amplicons. Among other features, ARSA-16S is based on a new model, approach, and algorithm for sequence-level assignment of reads understood as probability distributions, assigns reads individually, and is designed with non-overlapping amplicons covering two non-contiguous regions. A new set of primers for the amplification and sequencing of the V4 and V6 regions is also provided.
ARTICLE | doi:10.20944/preprints201812.0117.v1
Subject: Biology, Other Keywords: radioresistance; DNA-damage recognition; CRISPRa; multiplex overexpression
Online: 11 December 2018 (09:27:42 CET)
Current understanding of mechanisms of cellular resistance to genotoxic stress is incomplete but is critical for a variety of medical applications. Recent developments in the CRISPR/Cas technologies open new opportunities for targeted interrogation of resistance genes and pathways. In the present work, we used nuclease dead Cas9 constructs to achieve targeted overexpression of endogenous genes encoding two essential subunits of DNA damage sensor complex, XPC and HR23B, in HEK293T cells. Both individual and simultaneous overexpression of the two genes was achieved and the effects on cellular resistance to ionizing radiation and paraquat was examined. Using the fluorometric microculture cytotoxicity assay, we showed that simultaneous, but not separate overexpression of the two genes lead to a 30% increase in survivability. Irradiated cells that overexpressed both XPC and HR23B genes showed higher clonogenic capacity and proliferation rate compared to the irradiated transfection control as revealed by the clonogenic survival assay. Modulation of the gene expression did not affect cell resistance to paraquat. In summary, our results demonstrate a high potential of CRISPR/dCas9-enabled multiplex overexpression of stress-response genes in functionally justified combinations, exemplified here by the XPC-HR23B complex, for achieving an enhanced cellular radioresistance.
ARTICLE | doi:10.20944/preprints201801.0266.v2
Subject: Life Sciences, Genetics Keywords: genetics; injury; sport; soccer; DNA; inflammation; football
Online: 9 February 2018 (02:24:40 CET)
Genetics plays an integral role in athletic performance and is increasingly becoming recognised as an important risk factor for injury. Ankle and knee injuries are the most common injuries sustained by soccer players. Often these injuries result in players missing training and matches, which can incur significant costs to clubs. This study aimed to identify genotypes associated with ankle and knee injuries in soccer players and how these impacted the number of matches played. 289 soccer players including 46 professional, 98 semi-professional and 145 amateur players were genetically tested. Ankle and knee injuries and the number of matches played were recorded during the 2014/15 season. Four genes were assessed in relation to injury. Genotypes found to be associated with injury included the TT genotype of the GDF5 gene, TT and CT genotypes of AMPD1 gene, TT genotype of COL5A1 and GG genotype of IGF2 gene. These genes were also associated with a decrease in the number of matches played.
REVIEW | doi:10.20944/preprints202201.0310.v1
Subject: Biology, Plant Sciences Keywords: DNA barcoding; metabarcoding; BOLD; taxonomy; biodiversity; molecular marker.
Online: 20 January 2022 (15:15:36 CET)
Systematics plays the most crucial role in biodiversity conservation which is at stake due to anthropogenic activities and environmental degradations. The ever-increasing decline of classical taxonomic expertise drives the need to develop molecular marker-based tools for quick, efficient, and reliable detection of organisms, to assess their ecological impacts for deepening our understanding of systematic and evolutionary relationships between organisms which is central to biology. The pace of alpha taxonomy has quickened by its integration with an increasingly fashionable and novel concept called DNA barcoding which utilizes a short genetic marker or barcode to categorize species for enhanced biodiversity assessment. As a supplementary but not complete alternative of systematics research, DNA barcoding, however, not error-free, brings precision in identification by solving existing problems of classical taxonomy and phylogenetics, irrespective of the growth stage of organisms, particularly for known taxa rather than unknown ones. Mitochondrial gene Cytochrome C Oxidase 1 (COI) serves as a universal animal barcode but there is no such universal barcode for plants and developing a suitable one is more challenging. With the recent advancement of Next Generation Sequencing (NGS), DNA metabarcoding technology is advancing rapidly. Still, ambiguity and error prevail with the correct identification of species due to some problems. After extensive analysis of the existing DNA barcoding papers, this review discusses commonly used DNA barcodes in plants and animals, their roles, advantages, limitations to solve existing problems of conservation biology and add the author’s views and recommendations.
ARTICLE | doi:10.20944/preprints202111.0167.v1
Subject: Biology, Plant Sciences Keywords: chloroplast genome; Compositae; phylogenetic incongruence; plastid DNA; Senecioneae
Online: 9 November 2021 (12:51:07 CET)
Plastid genomes are in general highly conserved given their slow evolutionary rate, thus large changes in their structure are unusual. However, when specific rearrangements are present, they are often phylogenetically informative. Asteraceae is a highly diverse family whose evolution is long driven by polyploidy (up to 48x) and hybridisation, both processes usually complicating systematic inferences. In this study, we have generated one of the most comprehensive plastome-based phylogenies of family Asteraceae, providing information about the structure, genetic diversity, and repeat composition of these sequences. By comparing the whole plastome sequences obtained, we confirmed the double inversion located in the long single copy region, for most of the species analysed (with the exception of basal tribes), a well-known feature for Asteraceae plastomes. We also show that genome size, gene order and gene content are highly conserved along the family. However, species representative of the basal subfamily Barnadesioideae -as well as in the sister family Calyceraceae - are lacking the pseudogene rps19 located in one inverted repeat. The phylogenomic analysis conducted here, based on 63 protein-coding genes, 30 transfer RNA genes and 21 ribosomal RNA genes from 36 species of Asteraceae, are overall consistent with the general consensus for the family’s phylogeny, while resolving the position of tribe Senecioneae and revealing some incongruences at tribe level between reconstructions based on nuclear and plastid DNA data.
BRIEF REPORT | doi:10.20944/preprints202107.0075.v1
Subject: Biology, Anatomy & Morphology Keywords: DNA methylation; epigenetic aging; bottlenose dolphin; chronological age
Online: 5 July 2021 (07:59:15 CEST)
Epigenetics, specifically DNA methylation, allows for estimation of animal age from blood or remotely sampled skin. This multi tissue epigenetic aging clock uses 110 longitudinal samples from 34 Navy bottlenose dolphins (Tursiops truncatus), identifying 195 cytosine-phosphate-guanine sites associated with chronological aging via leave-one-individual-out-cross-validation (R2=0.95). With a median absolute error of 2.5 years this clock improves age estimation capacity in wild dolphins, expanding conservation efforts, enabling better understanding of population demographics.
ARTICLE | doi:10.20944/preprints202105.0305.v1
Subject: Life Sciences, Biochemistry Keywords: ISSR; Rosa spp.; DNA fingerprinting; genotypes; genetic diversity
Online: 13 May 2021 (14:01:21 CEST)
Genetic diversity is inevitable in making any crop improvement program successful. DNA fingerprinting technology to assess the genetic relationship among the selected genotypes for identification and cataloging of different species and cultivars of roses is a promising tool for Rosa genomes. The inter-simple sequence repeats markers (ISSRs) were used to investigate the genetic diversity among twenty-one diverse Rosa genotypes belonging to two different species, Rosa hybrida and R. damascena, and three distinct groups of rose varieties, namely Hybrid Tea, Floribunda, and Damask roses. Twenty-four ISSR primers yielded a total of 280 scorable amplified fragments from 250-1800 bp in length, from which 244 were polymorphic, resulting in an average of 86.4% polymorphism. UPGMA cluster analysis based on Jaccard’s pairwise similarity coefficient values ranged from 0.264 to 0.818, clearly distinguished different species and genotypes, grouping them into three distinct clusters. The results confirmed a high degree of variation in the rose germplasm studied highlighting the potential of improvement in roses for the ornamental and perfume industry.
ARTICLE | doi:10.20944/preprints202007.0594.v2
Subject: Biology, Anatomy & Morphology Keywords: Crustacea; Zooplankton; Plankton; Pacific Ocean; Larvae; DNA barcoding
Online: 16 April 2021 (11:23:51 CEST)
Determining the DNA sequencing of a small element in the mitochondrial DNA (DNA barcoding) makes it possible to easily identify individuals of different larval stages of marine crustaceans without the need for laboratory rearing. It can also be used to construct taxonomic trees, although it is not yet clear to what extent this barcode-based taxonomy reflects more traditional morphological or molecular taxonomy. Collections of zooplankton were made using conventional plankton nets in Newport Bay and the Pacific Ocean near Newport Beach, California (Lat. 33.628342, Long. -117.927933) between May 2013 and January 2020, and individual crustacean specimens were documented by videomicroscopy. Adult crustaceans were collected from solid substrates in the same areas. Specimens were preserved in ethanol and sent to the Canadian Centre for DNA Barcoding at the University of Guelph, Ontario, Canada for sequencing of the COI DNA barcode. From 1042 specimens, 544 COI sequences were obtained falling into 199 Barcode Identification Numbers (BINs), of which 76 correspond to recognized species. The results show the utility of DNA barcoding for matching life-cycle stages as well as for documenting the diversity of this group of organisms.
REVIEW | doi:10.20944/preprints202104.0068.v1
Subject: Life Sciences, Biochemistry Keywords: DNA methylation; histone modification; epigenetic diet; microRNAs; prediabetes
Online: 2 April 2021 (14:08:11 CEST)
Epigenetics refers to the DNA chemistry changes that result in the modification of gene transcription and translation independently of the underlying DNA coding sequence. Epigenetic modifications are reported to involve various molecular mechanisms, including classical epigenetic changes affecting DNA methylation and histone modifications and small RNA-mediated processes, particularly that of microRNAs. Epigenetic changes are reversible and are closely interconnected. They are recognised to play a critical role as mediators of gene regulation, and any alteration in these mechanisms has been identified to mediate various pathophysiological conditions. Moreover, genetic predisposition and environmental factors, including dietary alterations, lifestyle or metabolic status, are identified to interact with the human epigenome, highlighting the importance of epigenetic factors as underlying processes in the etiology of various diseases such as MetS. This review will reflect on how both the classical and microRNA regulated epigenetic changes are associated with the pathophysiology of Metabolic syndrome. We would then focus on the various aspects of epigenetic-based strategies used to modify MetS outcomes, including epigenetic diet, epigenetic drugs, epigenome editing tools, and miRNA-based therapies.
ARTICLE | doi:10.20944/preprints202103.0109.v1
Subject: Life Sciences, Microbiology Keywords: Pythiosis; Pythium insidiosum; Environment isolate; DNA barcode; Biotyping
Online: 2 March 2021 (16:41:34 CET)
Pythium insidiosum causes pythiosis, a fatal infectious disease of humans and animals worldwide. Prompt diagnosis and treatment are essential to improve the clinical outcome of pythiosis. Diagnosis of P. insidiosum relies on immunological, molecular, and proteomic assays. The main treatment of pythiosis aims to surgically remove all affected tissue to prevent recurrent infection. Due to the marked increase in case reports, pythiosis has become a public health concern. Thailand is an endemic area of human pythiosis. To obtain a complete picture of how the pathogen circulates in the environment, we surveyed the presence of P. insidiosum in urban (Bangkok) and rural areas of Thailand. We employed the hair-baiting technique to screen for P. insidiosum in 500 water samples. Twenty-seven culture-positive samples were identified as P. insidiosum by multiplex PCR, multi-DNA barcode (rDNA, cox1, cox2), and mass spectrometric analyses. These environmental strains of P. insidiosum fell into clade-I and -II genotypes and exhibited a close phylogenetic/proteomic relationship with Thai clinical strains. Biodiversity of the environmental strains also existed in a local habitat. In conclusion, P. insidiosum is widespread in Thailand. A better understanding of the ecological niche of P. insidiosum could lead to the effective prevention and control of this pathogen.
ARTICLE | doi:10.20944/preprints202001.0217.v1
Subject: Biology, Plant Sciences Keywords: antioxidant; Nigella sativa; secondary metabolites; thymoquinone; DNA damage
Online: 19 January 2020 (14:33:58 CET)
Nigella sativa (NS) is an effective medicinal plant possessing noteworthy antioxidant property. In NS, there are more than hundred phyto-chemicals reported, out of which thymoquinone is the utmost active phyto-constituent having sturdy antioxidative property. Thymoquinone is a cyclicdione, when reacts with sodium azide, converts into α-azido ketones i.e its analogs which are handy with extensive range of reactions. Sodium azide induces stress in plants thereby, modulating the antioxidant system. The present investigation was planned to elucidate the effect of sodium azide at different concentrations (5µM, 10µM, 20µM, 50µM, 100µM and 200µM) on its secondary metabolites (mainly thymoquinone) in NS callus culture extract (NSE). The results showed sodium azide effect on thymoquinone content and a concentration dependent boost in antioxidant property. It was also observed that thymoquinone content and percent yield (analyzed by RP-HPLC; Reverse Phase- High Performance Liquid Chromatography) were minimum (0.033±0.006% and 0.420±0.045%, respectively) at 200 µM sodium azide used. Whereas, antioxidant activity (analyzed by DPPH; 2, 2-diphenyl-1-picrylhydrazyl) was found to be maximum (3.873±0.402%) at same dose. Further, analysis was done for inhibition of oxidative DNA damage at different concentrations of sodium azide on NSE, maximum inhibition of DNA damage (0.243±0.017%) was found at 200 µM concentration of sodium azide. When correlated, strong positive correlation was observed between percent yield and percent thymoquinone, antioxidant property and inhibition of DNA damage. Whereas, strong negative correlation was observed between percent yield and antioxidant property, percent thymoquinone and antioxidant property, percent thymoquinone and inhibition of DNA damage. The findings evidently point out that the content of thymoquinone, antioxidant property and inhibition of DNA damage was affected by sodium azide.
Subject: Biology, Animal Sciences & Zoology Keywords: marine nematodes; mtCOI; DNA taxonomy; meiofauna; Mexican Caribbean
Online: 4 July 2019 (09:51:50 CEST)
Nematode biodiversity is mostly unknown; while about 20,000 nematode species have been described, estimates for species diversity range from 0.1 to 100 million. The study of nematode diversity, like that of meiofaunal organisms in general, has been mostly based on morphology-based taxonomy, a time-consuming and costly task that requires well-trained specialists. This work represents the first on the taxonomy of Mexican nematodes to integrate morphological and molecular data. We add seven new morphological records for the Mexican Caribbean: Anticomid sp1, Cylicolaimus sp1, Oncholaimus sp2, Platycoma sp1, Catanema sp1, Enopliodes spp., and Metachromadora spp. We recover 55 COI sequences that represent 20 species. Of the studied sites, Cozumel had 12 species and Cancún had two species (Rhips sp1 and Monoposthia mirabilis) represented by several individuals. All sequences are new for the genetic international databases GenBank and BOLD. Phylogenetic analyses and species delineation methods support the occurrence of the 20 entities and confirm the high resolution of COI sequences in delimiting species. ABGD and mPTP methods disentangled 20 entities, whereas Barcode Index Numbers (BINs) recovered 22 genetic species. DNA taxonomy was demonstrated to be an efficient, fast, and low-cost method to address a taxonomical shortfall of meiofaunal organisms.
Subject: Life Sciences, Biophysics Keywords: G-quadruplex; NMR; folding; DNA; structure; human papillomaviruses
Online: 18 March 2019 (10:00:21 CET)
The potential to affect gene expression via G-quadruplex stabilization has been extended to all domains of life, including viruses. Here, we investigate the polymorphism and structures of G-quadruplexes of the human papillomavirus type 52 with UV, CD and NMR spectroscopy and gel electrophoresis. We show that oligonucleotide with five G-tracts folds into several structures and that naturally occurring single nucleotide polymorphisms (SNPs) have profound effects on the structural polymorphism in the context of G-quadruplex forming propensity, conformational heterogeneity and folding stability. With help of SNP analysis, we were able to select one of the predominant forms, formed by G-rich sequence d(G3TAG3CAG4ACACAG3T). This oligonucleotide termed HPV52(1-4) adopts a three G-quartet snap back (3+1) type scaffold with four syn guanine residues, two edgewise loops spanning the same groove, a no-residue V loop and a propeller type loop. The first guanine residue is incorporated in the central G-quartet and all four-guanine residues from G4 stretch are included in the three quartet G-quadruplex core. Modification studies identified several structural elements that are important for stabilization of the described G-quadruplex fold. Our results expand set of G-rich targets in viral genomes and address the fundamental questions regarding folding of G-rich sequences.
ARTICLE | doi:10.20944/preprints201902.0042.v1
Subject: Life Sciences, Molecular Biology Keywords: RNA-Seq; Oncology; DNA repair; Survival; PCNA metagene
Online: 4 February 2019 (16:55:20 CET)
Removal of the proliferation component of gene expression by PCNA adjustment has been addressed in numerous survival prediction studies for breast cancer and all cancers in the TCGA. These studies indicate that widespread co-regulation of proliferation upwardly biases survival prediction when gene selection is performed on a genome-wide basis. In addition, removal of the correlative effects of proliferation does not reduce the random bias associated with survival prediction using random gene selection. Since most cancers become addicted to DNA repair as a result of forced cellular replication, increased oxidation, and repair deficiencies from oncogenic loss or genetic polymorphisms, we pursued an investigation to remove the proliferation component of expression in DNA repair genes to determine survival prediction. This translational hypothesis-driven focus on DNA repair genes is directly amenable to finding new sets of DNA repair genes that could potentially be studied for inhibition therapy. Overall survival (OS) prediction was evaluated in 18 cancers by using normalized RNA-Seq data for 126 DNA repair genes with expression available in TCGA. Transformations for normality and adjustments for age at diagnosis, stage, and PCNA metagene expression were performed for all DNA repair genes. We also analyzed genomic event rates (GER) for somatic mutations, deletions, and amplification in driver genes and DNA repair genes. After performing empirical p-value testing with use of randomly selected gene sets, it was observed that OS could be predicted significantly by sets of DNA repair genes for 61% (11/18) of the cancers. Interestingly, PARP1 was not a significant predictor of survival for any of the 11 cancers. Results from cluster analysis of GERs indicates that the most opportunistic cancers for inhibition therapy may be AML, colorectal, and renal papillary, because of potentially less confounding due to lower GERs for mutations, deletions, and amplifications in DNA repair genes. However, the most opportunistic cancer for inhibition therapy is likely to be AML, since it showed the lowest GERs for mutations, deletions, and amplifications in DNA repair genes. In conclusion, our hypothesis-driven focus to target DNA repair gene expression adjusted for the PCNA metagene as a means of predicting OS in various cancers resulted in statistically significant sets of genes.
ARTICLE | doi:10.20944/preprints201810.0587.v1
Subject: Biology, Plant Sciences Keywords: CITES; chikanda; conservation; DNA barcoding; orchids; species delimitation
Online: 25 October 2018 (05:10:27 CEST)
In Zambia wild edible terrestrial orchids are used to produce a local delicacy called chikanda, which has become increasingly popular throughout the country. Commercialization puts orchid populations in Zambia and neighbouring countries at risk of overharvesting. Hitherto, no study has documented which orchid species are traded on local markets, as orchid tubers are difficult to identify morphologically. In this study, the core land-plant DNA barcoding markers rbcL and matK were used in combination with nrITS to determine which species were sold on Zambian markets. Eighty-two interviews were conducted to determine harvesting areas, as well as possible sustainability concerns. By using nrITS DNA barcoding, a total of 16 orchid species in six different genera could be identified. Both rbcL and matK proved suitable to identify the tubers up to genus- or family level. Disa robusta, Platycoryne crocea and Satyrium buchananii were identified most frequently and three previously undocumented species were encountered on the market. Few orchid species are currently listed on the global IUCN Red List. Local orchid populations and endemic species could be at risk of overharvesting due to the intensive and indiscriminate harvesting of chikanda orchids and we therefore encourage increased conservation assessment of terrestrial African orchids.
REVIEW | doi:10.20944/preprints201809.0422.v1
Subject: Chemistry, Food Chemistry Keywords: LDL-oxidation; DNA-damage; antioxidant vitamins; oxidative stress
Online: 20 September 2018 (16:53:42 CEST)
Radical oxygen species formed in human tissue cells by many endogenous and exogenous pathways, cause extensive oxidative damage, which has been linked to various human diseases. This review paper provides an overview of lipid peroxidation and focuses on the free-radicals initiated processes of LDL oxidative modification and DNA oxidative damage, which are widely associated to the initiation and development of atherosclerosis and carcinogenesis, respectively. The article subsequently provides an overview of the recent human trials or even in vitro investigations on the potential of natural antioxidant compounds (such as carotenoids, vitamins C and E) to monitor LDL and DNA oxidative changes.
ARTICLE | doi:10.20944/preprints201804.0326.v1
Subject: Biology, Horticulture Keywords: DNA markers; edible mushroom; genome stability; protoplast regeneration
Online: 25 April 2018 (08:26:25 CEST)
A total of five protoclones were successfully cultured on PDA medium out of regenerated twenty two colonies of Termitomyces protoplast and further studied. Liquid MYG grown mycelial tissue is used for protoplast isolation by enzymatic digestionin a mixture containing Lysing enzyme 2% and Cellulase R10 2% in 0.6 M mannitol. The incubation conditions like temperature, shaking and time were standardized at 24ºC, 60 rpm and 10 hours, respectively for healthy protoplasts liberation. The purified protoplasts showed an average yield of 1.2 × 107 cells/gm tissue with 31.60 ± 9.31% regeneration efficiency on specific medium and 77.12 ± 2.72% viability by FDA test. Four ISSR primers were used in this study resulting a total of 27 reproducible bands with mean value of 6.75. They showed similar banding pattern in all the lines with zero percent polymorphism ranged from 280 bp–2700 bp. The amplified rRNA-ITS gene showed ~600 bp size in gel and found a single restriction site for enzyme HaeIII in all the protoclones and parent with similar fragment size in all.
TECHNICAL NOTE | doi:10.20944/preprints201804.0047.v1
Online: 4 April 2018 (06:00:40 CEST)
The exceptional increase in molecular DNA sequence data in open repositories is mirrored by an ever-growing interest among evolutionary biologists to harvest and use those data for phylogenetic inference. Many quality issues, however, are known and the sheer amount and complexity of data available can pose considerable barriers to their usefulness. A key issue in this domain is the high frequency of sequence mislabelling encountered when searching for suitable sequences for phylogenetic analysis. These issues include the incorrect identification of sequenced species, non-standardised and ambiguous sequence annotation, and the inadvertent addition of paralogous sequences by users, among others. Taken together, these issues likely add considerable noise, error or bias to phylogenetic inference, a risk that is likely to increase with the size of phylogenies or the molecular datasets used to generate them. Here we present a software package, phylotaR, that bypasses the above issues by using instead an alignment search tool to identify orthologous sequences. Our package builds on the framework of its predecessor, PhyLoTa, by providing a modular pipeline for identifying overlapping sequence clusters using up-to-date GenBank data and providing new features, improvements and tools. We demonstrate our pipeline’s effectiveness by presenting trees generated from phylotaR clusters for two large taxonomic clades: palms and primates. Given the versatility of this package, we hope that it will become a standard tool for any research aiming to use GenBank data for phylogenetic analysis.
ARTICLE | doi:10.20944/preprints201612.0006.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: Dengue virus; E; NS1-2a; electroporation; DNA vaccine
Online: 1 December 2016 (10:37:10 CET)
Dengue virus (DENV), the causative agent of dengue fever (DF), is one of the most important mosquito-borne viruses that can infect humans. Although much effort has been made on prevention and control of dengue, there are currently no anti-viral drugs or worldwide approved vaccines yet. In this study, we immunized six-week-old Balb/c mice with DNA vaccine candidates E and NS1-2a of DENV serotype 2 or the combination of them (E+NS1-2a) via an electroporation (EP)-assisted intramuscular gene delivery system and evaluated the immune response and protection. The highest specific antibody titres and cytokine levels secreted by splenocytes as well as the highest survival rate were observed in the E+NS1-2a group, followed by E group and NS1-2a group. Our data suggested that the combination of E and NS1-2a delivered by EP may be a superior preventive strategy against DENV.
ARTICLE | doi:10.20944/preprints201608.0011.v1
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: curcumin; furazolidone; oxidative stress; DNA damage; mitochondrial pathway
Online: 2 August 2016 (05:59:38 CEST)
Furazolidone (FZD) is a synthetic nitrofuran with the antiprotozoal and antibacterial activity. The proper mechanism of FZD induced toxicity is still unclear. This study aimed to investigate the protective effect of curcumin on FZD induced oxidative stress, DNA injury and apoptosis in human hepatocyte L02 cells. The results showed that curcumin treatment significantly ameliorated FZD induced cytotoxicity, characterized by decreasing the production of reactive oxygen species (ROS) and malondialdehyde, as well as increasing superoxide dismutase, catalase activities and glutathione contents. Moreover, curcumin pretreatment significantly inhibited FZD induced the loss of mitochondrial membrane potential, the activation caspase-9 and -3 and apoptosis. Comet assay showed that curcumin attenuated FZD induced DNA injury in a dose-dependent manner. Correspondingly, curcumin markedly reversed the up-regulation of p53, Bax, caspase-9 and -3 mRNA expressions and the down-regulation of Bcl-2 mRNA (all p<0.05 or 0.01). These results reveal that curcumin protects against FZD induced oxidative stress, DNA injury and cell apoptosis via inhibiting oxidative stress and mitochondrial pathway, which may be attributed to ROS scavenging and anti-oxidative ability of curcumin. Importantly, our study highlights that curcumin may be a potential way to prevent FZD-mediated oxidative DNA injury and apoptosis in human or animals.
REVIEW | doi:10.20944/preprints201810.0204.v2
Subject: Life Sciences, Biotechnology Keywords: DNA origami; aptamer; DNA nanotechnology; protein nano array; biosensor; logic gate; enzyme cascade; drug delivery system; targeted therapy; molecular robotics
Online: 22 October 2018 (10:57:21 CEST)
DNA origami has emerged in recent years as a powerful technique for designing and building 2D and 3D nanostructures. While the breadth of structures that have been produced is impressive, one of the remaining challenges, especially for DNA origami structures intended to carry out useful biomedical tasks in vivo, is to endow them with the ability to detect and respond to molecules of interest. Target molecules may be disease indicators or cell surface receptors, and the responses may include conformational changes leading to release of therapeutically relevant cargo. Nucleic acid aptamers are ideally suited to this task and are beginning to be used in DNA origami designs. In this review we consider examples of uses of DNA aptamers in DNA origami structures and summarise what is currently understood regarding aptamer-origami integration. We review three major roles for aptamers in such applications: protein immobilisation, triggering of structural transformation, and cell targeting. Finally, we consider future perspectives for DNA aptamer integration with DNA origami.
ARTICLE | doi:10.20944/preprints201704.0154.v1
Subject: Life Sciences, Molecular Biology Keywords: water bridging; dipole waves; coherent states; polymerase chain reaction; DNA amplification; DNA transduction; enzyme catalytic activity; fractal-like self-similarity
Online: 25 April 2017 (04:24:21 CEST)
We discuss the role of water bridging the DNA-enzyme interaction by resorting to recent 1 results showing that London dispersion forces between delocalized electrons of base pairs of DNA 2 are responsible for the formation of dipole modes that can be recognized by Taq polymerase. 3 We describe the dynamical origin of the high efficiency and precise targeting of Taq activity in 4 PCR. The spatiotemporal distribution of interaction couplings, frequencies, amplitudes, and phase 5 modulations comprise a pattern of fields instantiating the electromagnetic image of DNA in its 6 water environment, which is what the polymerase enzyme actually recognizes at long range. The 7 experimental realization of PCR amplification, achieved through replacement of the DNA template 8 by the treatment of pure water with electromagnetic signals recorded from viral and bacterial DNA 9 solutions, is found consistent with the gauge theory paradigm of quantum fields.
ARTICLE | doi:10.20944/preprints201705.0156.v1
Subject: Life Sciences, Other Keywords: DNA fragmentation factors 40, DFF40, DNA fragmentation factors 45, DFF45, b-cell lymphoma 2, bcl-2, endometrium, menstrual cycle, uterine myometrium.
Online: 22 May 2017 (05:44:31 CEST)
Abstract: DNA fragmentation factors 40 and 45 (DFF40 and DFF45) and B-cell lymphoma 2 (Bcl-2) expression were evaluated in the normal human endometrium and myometrium. DFF40, DFF45, and Bcl-2 expression was assessed via immunohistochemistry in the proliferative, secretory, and atrophic endometrium and myometrium collected postmenopausally and premenopausally during the proliferative and secretory phases of the menstrual cycle. The endometrium showed significantly higher DFF40 and DFF45 expression than that in the uterine myometrium; compared to the stroma, endometrial glands showed the highest expression in pre- and postmenopausal specimens. Glandular expression of DFF45 was dependent on the menstrual cycle, reaching its highest level in the secretory endometrium. The glandular expression of DFF40 and DFF45 was significantly lower in postmenopausal specimens than that in premenopausal tissue. No cycle-dependent changes were reported for stromal or myometrial DFF40 or DFF45 expression. Compared to the endometrial stroma and myometrium, Bcl-2 showed the highest expression in the glandular proliferative endometrium and the lowest expression in the stromal secretory endometrium and myometrium during the secretory phase of the cycle. DFF45 and Bcl-2 showed menstrual cycle-dependent expression, which was limited to the glandular layer of the endometrium.
ARTICLE | doi:10.20944/preprints202209.0260.v1
Subject: Life Sciences, Molecular Biology Keywords: Mollusks; gastropods; Zooplankton; Plankton; Pacific Ocean; larvae; DNA barcoding
Online: 19 September 2022 (04:57:36 CEST)
The life cycles and biodiversity of Pacific coast gastropods were analyzed by videomicroscopy and DNA barcoding of indi-viduals collected from tide pools and in plankton nets from a variety of shore stations. In many species (Families Calyptrae-idae, Cerithiopsidae, Strombidae, Vermetidae, Columbellidae, Nassariidae, Olivellidae, Hermaeidae, Onchidorididae, Gas-tropteridae, Haminoeidae), the free-swimming veligers were recovered from plankton collections; in Roperia poulsoni (family Muricidae) veligers were usually recovered from egg sacs where they had been retained although some escapees were found in plankton collections; in Pteropurpura festiva (family Muricidae) free-living veligers were also found; and in Atlanta californiensis (family Atlantidae) both veligers and adults were obtained from plankton collections making this a holoplank-tonic species. The results confirm that DNA barcoding using the COI barcode is a useful strategy to match life-cycle stages within species as well as to identify species and to document the level of biodiversity within the gastropods.
REVIEW | doi:10.20944/preprints202206.0280.v1
Subject: Life Sciences, Genetics Keywords: autism; ASD; epigenetics; DNA methylation; genetics; oxytocin; social experience
Online: 21 June 2022 (04:16:24 CEST)
The number of children diagnosed with autism spectrum disorder (ASD) has increased substantially over the past two decades with current research unable to fully account for this dramatic increase in prevalence. One explanation proposes that both intrinsic (e.g., genetic) and extrinsic (e.g., environmental) risk factors may be involved in the etiology of ASD. The goal of this review paper is to explore modifiable pathways for intervention in children at risk for ASD, specifically examining how early social experience may be correlated with epigenetic change in genes associated with autism. We present an innovative model which proposes that polygenic risk and social experience (via epigenetic mechanisms) may both contribute to the observed ASD phenotype. Previous research on genetic, environmental, and epigenetic mechanisms implicated in the etiology of ASD will be reviewed, with an emphasis on the oxytocin receptor gene, which is epigenetically altered by early social experience, plays a crucial role in mammalian social and cognitive development, and is associated with both genetic and epigenetic risk for ASD. Identifying intrinsic (e.g., genetic) and extrinsic (e.g., social experience) risk markers for ASD, a combination of which has not previously been examined, would transform our understanding of this condition, facilitate earlier identification of ASD risk, and guide early intervention efforts. This may have a far-reaching impact on individuals with ASD, their families, and society.
HYPOTHESIS | doi:10.20944/preprints202108.0454.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: Alzheimer’s disease; DNA damage; somatic mutation; integrin; synaptic adhesion
Online: 23 August 2021 (14:34:00 CEST)
Alzheimer’s disease (AD) is a genetically complex senile neurodegeneration with unknown etiology. The first gene discovered to be mutated in early-onset AD, the amyloid precursor protein (APP), has been widely assumed as a causal factor in the disease cascade due to its generation of Aβ species. APP has an evolutionarily conserved biological role and activates a signaling program with notable similarities to integrin—a cell adhesion receptor with a wide array of functions. Intriguingly, several AD genome-wide association study (GWAS) candidate genes, including the SHARPIN locus recently reported by us and others, influence signaling of the integrin pathway. Integrins are focal adhesion regulators and serve in nervous system development, synaptic plasticity, and Tau phosphorylation. These observations suggest that the function of APP probably goes beyond Aβ generation in AD. Aging—the strongest risk factor for AD—is associated with various clock-like events in cells. For instance, neurons are continuously impacted by stochastic ‘hits’ to their genomes in aging, in the forms of DNA damage, insertion-deletions, copy-number variations (CNVs) and other types of somatic mutations. DNA damage and somatic mutations can result in neoplastic changes and cancer in mitotically active cells. However, their consequences in post-mitotic cells such as aging neurons are less defined. The current hypothesis holds that the stochastic loss of DNA sequence data at random loci in aging affects longer genes by chance more frequently. As a result, the biological processes coordinated by long genes may be more vulnerable to such random aging effects. Curiously, as shown by us and others, long genes are strongly enriched for synapse- and cell adhesion-related ontologies, more than any other biological process or cellular compartment. In addition, among various cell types, neurons possess the highest levels of long gene expression and are therefore more vulnerable to such harmful effects. The long gene vulnerability hypothesis provides a simple link between aging and the genetic landscape of AD and warrants new strategies for disease modification.
REVIEW | doi:10.20944/preprints202101.0525.v1
Subject: Biology, Anatomy & Morphology Keywords: DNA Damage; Base Excision Repair; SMUG1; 5-hmdU; Cancer
Online: 26 January 2021 (08:17:11 CET)
Single-stand selective monofunctional uracil DNA glycosylase 1 (SMUG1) works to remove uracil and certain oxidized bases from DNA during base excision repair (BER). This review provides a historical characterization of SMUG1 and 5-hydroxymethyl-2'-deoxyuridine (5-hmdU) one important substrate of this enzyme. Biochemical and structural analyses provide remarkable insight into the mechanism of this glycosylase revealing SMUG1 has a unique helical wedge which influences damage recognition during repair. Rodent studies suggest that, while SMUG1 shares substrate specificity with another uracil glycosylase UNG2, loss of SMUG1 can have unique cellular phenotypes. This review highlights the multiple roles SMUG1 may play in preserving genome stability, and how the loss of SMUG1 activity may promote cancer. Finally, we discuss recent studies indicating SMUG1 has moonlighting functions beyond BER, playing a critical role in RNA processing including the RNA component of telomerase.