REVIEW | doi:10.20944/preprints202201.0020.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: P53; mutant p53; targeting therapy; immunotherapy; cancer
Online: 4 January 2022 (20:34:14 CET)
TP53 is a tumor suppressor gene that encodes a sequence-specific DNA-binding transcription factor activated by stressful stimuli and upregulates target genes involved in growth suppression, cell death, DNA repair, metabolism, among others. P53 is the most frequently mutated gene in tumors with mutations not only leading to loss-of-function (LOF), but also gain-of-function (GOF) which promotes tumor progression, and metastasis. The tumor-specific status of mutant p53 protein has suggested it is a promising target for cancer therapy. We summarize the current progress of targeting wild-type and mutant p53 for cancer therapy through biotherapeutic and biopharmaceutical methods for 1) boosting p53 activity in cancer, 2) p53-dependent and p53-independent strategies for targeting p53 pathway functional restoration in p53-mutated cancer, 3) targeting p53 in immunotherapy, and 4) combination therapies targeting p53, p53 checkpoints, or mutant p53 for cancer therapy.
ARTICLE | doi:10.20944/preprints202105.0560.v1
Subject: Biology, Anatomy & Morphology Keywords: ae mutant; amylose; breeding potential; maize; SBEIIb
Online: 24 May 2021 (10:44:31 CEST)
Maize varieties with high amylose proportion are more valuable for starch industry. The SBEⅡb gene encodes one of the starch branching isozymes (SBEⅠ, SBEⅡa, and SBEⅡb). Its recessive mutant amylose-extender (ae/sbe2b) decreases the total activities of SBEs and increases amylose proportion up to 60%. Here, the breeding potential of introduced germplasm line GEMS-0067 was evaluated by genotyping and phenotyping. The deletion of the ninth exon of the SBEⅡb gene, high amylose proportion, and the typical irregular granules suggested that this germplasm line was derived from the same resource of high amylose line AE11. The gelatinization and thermal properties, and degree of polymerization of starch chain showed its advantages used for high amylose breeding. However, the negative correlation between amylose proportion and starch content, as well as ker-nel filling characteristics should be overcome during breeding process.
ARTICLE | doi:10.20944/preprints201706.0015.v1
Subject: Life Sciences, Molecular Biology Keywords: gibberellin; photoperiod; mutant; floral induction; flowering time
Online: 2 June 2017 (07:45:32 CEST)
Flower bud formation and flowering in chrysanthemum occur under short day conditions (SD), but the molecular basis for the switch to reproductive growth is less well understood than in model plants. Here, a spontaneous mutant able to flower under long days is described. In an attempt to reveal the pathway(s) involved in the formation of flower buds under contrasting daylengths, transcriptome sequencing was carried out in plants grown both under SD and under long day conditions (LD). A number of differentially transcribed genes involved in the various known flowering pathways were identified. Both circadian clock genes and CmFTL3 were up-regulated under SD, thereby inducing floral bud formation and flowering. The gibberellin (GA) signalling pathway-related genes GA20ox and GID1 were up-regulated in the mutant under LD, while the catabolic gene GA2ox and GAI was down-regulated, thereby inducing the transcription of CmFTL1, SOC1 and LFY. The GA content of the leaf was higher in the mutant than in the wild type under LD. When treated with GA, the mutant flowered earlier under both SD and LD, but there was no other detectable phenotype difference between the two lines. The indication was that the photoperiod pathway majorly regulates flower bud formation and flowering time in chrysanthemum under SD. GA signalling pathway only plays a subsidiary role for flowering. However, the GA signalling pathway predominated for flowering under LD.
ARTICLE | doi:10.20944/preprints202007.0687.v1
Subject: Chemistry, Applied Chemistry Keywords: Gamma-ray, Mutant, Rose, Volatile compounds, GC-MS
Online: 29 July 2020 (09:46:55 CEST)
Roses are one of the most important floricultural crops, and their essential oils have long been used for cosmetics and aromatherapy. We investigated the volatile compound compositions of 12 flower-color mutant variants and their original cultivars. Twelve rose mutant genotypes were developed by treatment with 70 Gy of 60Co gamma irradiation of six commercial rose cultivars. Essential oils from the flowers of the 18 genotypes were analyzed by gas chromatography–mass spectrometry. Seventy-seven volatile compounds were detected, which were categorized into five classes: hydrocarbons, terpenoids, alcohols, esters, and others. Hydrocarbons, alcohols, and esters were major components in all rose flowers. The mutant genotypes CR-S8 and CR-S9 showed higher contents of hydrocarbons than the original cultivar. In addition, CR-S1, CR-S3, and CR-S4 mutant genotypes showed higher ester contents than their original cultivar. Nonacosane, 2-methylhexacosane, and 2-methyltricosane were major volatile compounds among all genotypes. Hierarchical cluster analysis of the rose genotypes gave four groups according to grouping among the 77 volatile compounds. These findings will be useful for the selection of rose genotypes with improved volatile compounds.
ARTICLE | doi:10.20944/preprints202007.0251.v1
Subject: Life Sciences, Molecular Biology Keywords: SARS-CoV-2; COVID-19; Spike protein; Mutant; Genome
Online: 12 July 2020 (12:03:16 CEST)
The severity of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), greatly varies from patient to patient. In the present study, we explored and compared mutation profiles of SARS-CoV-2 isolated from mildly affected and severely affected COVID-19 patients in order to explore any relationship between mutation profile and disease severity. Genomic sequences of SARS-CoV-2 were downloaded from GISAID database. With the help of Genome Detective Coronavirus Typing Tool, genomic sequences were aligned with the Wuhan seafood market pneumonia virus reference sequence and all the mutations were identified. Distribution of mutant variants was then compared between mildly and severely affected groups. Among the numerous mutations detected, 14,408C>T and 23,403A>G mutations resulting in RNA-dependent RNA polymerase (RdRp) P323L and spike protein D614G mutations, respectively, were found predominantly in severely affected group (>82%) compared with mildly affected group (<46%, p<0.001). The 241C>T mutation in the non-coding region of the genome was also found predominantly in severely affected group. The 3,037C>T, a silent mutation, also appeared in relatively high frequency in severely affected group. We concluded that RdRp P323L and spike protein D614G mutations predominate in severely affected COVID-19 patients. Further studies will be required to explore whether these mutations have any impact on the severity of COVID-19.
REVIEW | doi:10.20944/preprints201912.0261.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: huntington disease; cag repeat; mutant huntingtin (mhtt); therapeutics; neurodegeneration
Online: 19 December 2019 (13:18:38 CET)
Huntington disease (HD) is an autosomal dominantly inherited fatal neurodegenerative disease. It affects motor, cognitive and psychiatric functions, and ultimately leads to death. The pathology of the disease is due to an expansion of CAG repeats in exon 1 of the huntingtin gene on chromosome 4, which produces a mutant huntingtin protein (mhtt). HD patients manifest a typical phenotype of sporadic, rapid, involuntary control of limb movement, stiffness of limbs, impaired cognition and severe psychiatric disturbances. A variety of symptomatic treatments (which target excitotoxicity, the dopamine pathway, caspases, aggregation, mitochondrial dysfunction, transcriptional dysregulation, mHtt, nucleic acid, neurodegeneration, fetal neural transplants, etc.) are currently available, and new symptomatic and potentially disease-modifying therapies are being actively developed. Recent advances in novel therapeutic strategies, including targeting mutant huntingtin (mhtt) and the htt gene, promise another wave of disease-modifying trials in the near future. A better appreciation of heterogeneous clinical phenomenology and immediate tractable treatment goals coupled with advances in new therapeutics heralds a golden age of HD treatment that will positively impact the quality of life and longevity of HD patients and inform advances in other inherited and neurodegenerative neurological disorders. In the present review literature, our aims to address the latest research on promising therapeutics based on influencing the hypothesized pathological mechanisms associated with HD.
ARTICLE | doi:10.20944/preprints202107.0278.v1
Subject: Chemistry, Analytical Chemistry Keywords: Typhonium flagelliforme; MCF-7 cell line; stigmasterol; agonistic; mutant plant
Online: 13 July 2021 (08:27:04 CEST)
Typhonium flagelliforme is an Indonesian herbal plant used and applied traditionally to treat cancer diseases. Gamma rays have irradiated rodent tuber mutant plant at six doses gray to in-crease the chemical compounds of anticancer activity. The effect of isolated compounds from ro-dent tuber mutant plants has never been studied and published yet. Our study unveiled the poten-tial of stigmasterol as a remarkable cytotoxic agent and the significant contribution of NMR spectroscopy, IR, Mass spectra, QTOF MS towards the isolation and identification of this anti-cancer agent. Stigmasterol was isolated from T. flagelliforme mutant plant. Stigmasterol was more effective against MCF-7 cells with an IC50 value of 0.1623 µM than Cisplatin with IC50 value 13.2 µM. It is the most potential and active fraction in the human breast cancer cell line. The mo-lecular docking study analyzed the chemical profile of stigmasterol to confirm the receptor in agonist binding sites. The prediction of the toxicity of stigmasterol compounds using in silico and analysis of its interaction with the receptor can act as a competitive regulator with a high-affinity binding site on FXR. Stigmasterol has potential as a candidate for an anticancer drug that pro-moting further clinical action.
ARTICLE | doi:10.20944/preprints202012.0797.v1
Subject: Keywords: KRAS-mutant lung adenocarcinoma; E571K exportin-1; Taxifolin; Molecular modelling
Online: 31 December 2020 (12:25:13 CET)
Aim: To establish, through molecular modelling, safe and clinically acceptable putative antagonists of E571K-mutated exportin-1 among the bioactive compounds in various parts of Juglans mandshurica. Methods: The bioactive compounds were subjected to compendium of druglikeness and lead-likeness filter workflows prior to docking of the resultant compounds into E571K exportin-1 active site using PyRx AutoDock vina to establish their binding affinity and interaction profile. The evolutionary algorithm of Osiris property explorer DataWarrior software as well as lead-likeness filter were employed for generation of novel non-promiscuous analogues of the lead compound with better putative selectivity and clinical acceptability as E571K Exportin-1 antagonists.Results: The findings of this study present taxifolin as the putatively effective and lead-like E571K Exportin-1 inhibitor with high potential of qualifying for clinical evaluation but is associated with high promiscuity tendency in high throughput screening. The evolutionary derivation of novel analogues of the compound, however, results in the generation of putatively non-promiscuous, non-toxic, and lead-like E571K Exportin-1 antagonists with high synthetic accessibility and clinical developability for evaluation in the strategy for treatment of drug-resistant KRAS-mutant lung adenocarcinoma condition.
ARTICLE | doi:10.20944/preprints202010.0484.v1
Subject: Biology, Anatomy & Morphology Keywords: inorganic polyphosphate; VTC4; knockout mutant; oxidative stress; gene expression; yeast
Online: 23 October 2020 (10:42:43 CEST)
Inorganic polyphosphate (polyP) is an important factor of stress tolerance in microbial cells. In yeast, the major enzyme of polyP biosynthesis is Vtc4, a subunit of the vacuole transporter chaperone (VTC) complex. In this study, we demonstrated that Vtc4 knockout in Saccharomyces cerevisiae not only decreased polyP content but also caused shifts in the composition of the intracellular polyP pool and changed the stress tolerance profile. In the mutant S. cerevisiae, the level of short-chain acid-soluble polyPs was decreased nearly 10-fold, whereas that of longer acid-insoluble polyPs was decreased only 2-fold, suggesting the existence of other enzymes compensating the production of long-chain polyPs. The Δvtc4 mutant showed inhibition of Mg2+-dependent phosphate uptake and decreased resistance to alkaline stress but increased tolerance to oxidation and heavy metal ions, especially Mn2+. Quantitative PCR revealed the upregulation of the DDR2 gene implicated in multiple stress responses and downregulation of PHO84 encoding a phosphate and Mn2+ transporter, which could account for the effects on phosphate uptake and Mn2+-related stress response in the Δvtc4 mutant. Our study indicates that short-chain polyPs, plays an important role in the regulation of stress response in yeast.
ARTICLE | doi:10.20944/preprints202005.0063.v1
Subject: Life Sciences, Molecular Biology Keywords: p53-Mdm2; mutant p53; oncogene; stress; regulatory network; cancer dynamics
Online: 5 May 2020 (05:55:27 CEST)
We study a minimal model of the stress-driven p53 regulatory network that includes competition between active and mutant forms of the tumor-suppressor gene p53. Depending on the nature of the external stress signal, four distinct dynamical states are observed. These states can be distinguished by dierent dynamical properties and correspond to active, apoptotic, pre-malignant and cancer states. Transitions between any two of these states are found to be unidirectional and irreversible if the stress signal is either oscillatory or constant. When the signal decays exponentially, the apoptotic state vanishes, and for low stress the pre-malignant state is bounded by two critical points, allowing the system to transition reversibly from the active to the pre-malignant state. For signicantly large stress, the range of the pre-malignant state expands and the system moves to the cancerous state which is a stable attractor. This suggests that identification of the pre-malignant state may be important both for therapeutic intervention as well as for drug discovery.
ARTICLE | doi:10.20944/preprints202101.0060.v1
Subject: Biology, Plant Sciences Keywords: Korean soybean varieties; nsSNP; Biomarker; SIFT; Polyphen; PANTHER; I-mutant 2.0
Online: 4 January 2021 (16:25:22 CET)
Soybean is a highly nutritious legume grown globally as a food and feed crop. An examination of a collection of 10 cultivated and 6 wild Korean soybean varieties showed that there is phenotypic variability notable in different soybeans. Therefore, to develop a list of biomarker candidates useful for growing soybeans of better quality and quantity, the genes of 16 Korean soybean varieties were compared with those of the reference Glycine max var. Williams 82. The comparison was made through gene sequencing to facilitate selection of nsSNPs. The objective of the study was to find out the structural and functional variations caused by nsSNPs and discuss whether the collection of Korean soybean varieties qualifies as biomarkers based on their phenotypic traits. Analysis of the data collected was done using four software: SIFT, Polyphen, PANTHER, and I-mutant 2.0, which are designed to detect the rate of functional and structural variations caused by the nsSNPs in cultivated and wild soybean varieties. Genotypic information obtained in the analysis was used to develop a core collection of biomarkers based on whether nsSNP content was found in more than half of the 16 samples. Therefore, the list of biomarker candidates developed from this study showed that Korean soybean could provide valuable information needed in both future crop genetic research and identification of biomarkers.
Subject: Biology, Anatomy & Morphology Keywords: BMP15 gene; Ewe; Sudanese Sheep; Residue; Wild type; Mutant type; dryland
Online: 6 November 2020 (15:29:04 CET)
This study tested the association between FecXG point mutation located in exon 2 of BMP15 gene and the prolificacy of Dubasi, Shugor and Watish sheep ecotypes, under dryland farming, Sudan. Blood samples were randomly collected from unrelated 100 ewes (Dubasi; n= 30, Shugor: n= 30, and Watish: n= 40). Bone Morphogenetic protein (BMP15) gene was amplified using PCR-RFLP. Two genotypes were found in all studied breeds (heterozygous and wild type). The calculated total genotype frequencies of BB, Bb and bb genotypes were 0.31, 0.69 and 0.00, respectively, while allele frequencies were 0.66 for B and 0.34 for b. Litter size was influenced by the genotypes of BMP15 gene, parities and subtypes (p<0.05), highest for Watish and 4th parity. Alignment of BMP15 samples along with database reference sequence revealed that most sequence regions were identical except for one variable nucleotide at position 111 bp where a guanine (G) was replaced by adenine (A) in Watish and Shugor samples. All amino acids were the same at residue 275. Watish and Shugor breeds are more related. The study concluded that the presence of one copy of FecXG point mutation of BMP15 gene increased the litter size by 0.17 lambs in the studied ecotypes.
ARTICLE | doi:10.20944/preprints201910.0025.v1
Subject: Life Sciences, Microbiology Keywords: Acinetobacter baumannii; multiresistant; mutant lytic phage; phage therapy; antibiotic-phage synergy.
Online: 2 October 2019 (08:42:31 CEST)
The global health emergency caused by multi-drug resistant bacteria has led to the search for and development of new antimicrobial agents. Phage therapy is an abandoned antimicrobial therapy that has been resumed in recent years. In this study, we mutated a lysogenic phage from Acinetobacter baumannii into a lytic phage (Ab105-2phiΔCI) showing antimicrobial activity against A.baumannii clinical strains (such as Ab177_GEIH-2000 which showed MICs to meropenem and imipenem of 32 µg/ml and 16 µg/ml, respectively as well as belonging to GEIH-REIPI Spanish Multicenter A. baumannii Study II 2000/2010, Umbrella Genbank Bioproject PRJNA422585). We then enhanced the time kill curves (in vitro) and in Galleria mellonella survival assays (in vivo) antimicrobial activity of the new lytic phage by combining it with carbapenem antibiotics (meropenem and imipenem). We observed in vitro, an antimicrobial synergistic effect (from 4 log to 7 log CFU/ml) with meropenem plus lytic phage in all combinations analysed (0.1, 1 and 10 MOI of Ab105-2phiΔCI mutant as well as 1/4 and 1/8 MIC of meropenem). Moreover, we had a decrease in bacterial growth of 8 log CFU/ml for the combination of imipenem at 1/4 MIC plus lytic phage (Ab105-2phiΔCI mutant) and of 4 log CFU/ml for the combination of imipenem at 1/8 MIC plus lytic phage (Ab105-2phiΔCI mutant) in both MOI 1 and 10. These results were confirmed in in vivo (G. mellonella) obtaining a higher effectiveness in the combination of imipenem and Ab105-2phiΔCI mutant (P<0.05 by Log Rank-Matel Cox test). This approach could help to reduce the emergence of phage resistant bacteria and restore sensitivity to the antibiotics when used to combat multiresistant strains of Acinetobacter baumannii.
ARTICLE | doi:10.20944/preprints202008.0028.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Oncolytic virus; Mesenchymal stem cell; Prodrug activation; P53 mutant tumor; Colorectal cancer
Online: 2 August 2020 (12:31:32 CEST)
Although oncolytic viruses are currently being evaluated for cancer treatment in clinical trials, systemic administration is hindered by many factors that prevent them from reaching the tumor cells. When administered systemically, mesenchymal stem cells (MSCs) target tumors, and therefore constitute good cell carriers for oncolytic viruses. Methods: MSCs were primed with trichostatin A under hypoxia, which upregulated the expression of CXCR4, a chemokine receptor involved in tumor tropism, and coxsackievirus and adenovirus receptor that plays an important role in adenoviral infection. After priming, MSCs were loaded with conditionally replicative adenovirus that exhibits limited proliferation in cells with a functional p53 pathway and encodes Escherichia coli nitroreductase (NTR) enzymes (CRAdNTR) for targeting tumor cells. Results: Primed MSCs increased tumor tropism and susceptibility to adenoviral infection, and successfully protected CRAdNTR from neutralization by anti-Adenovirus antibodies both in vitro and in vivo, and specifically targeted p53-deficient colorectal tumors when infused intravenously. Analyses of deproteinized tissues by UPLC-MS/QTOF revealed that these MSCs converted the co-administered prodrug CB1954 into cytotoxic metabolites, such as 4-hydroxylamine and 2-amine, inducing oncolysis and tumor growth inhibition without being toxic for the host vital organs. Conclusion: This study shows that the combination of oncolytic viruses delivered by MSCs with the activation of prodrugs is a new cancer treatment strategy that provides a new approach for the development of oncolytic viral therapy for various cancers.
REVIEW | doi:10.20944/preprints202003.0048.v1
Subject: Life Sciences, Genetics Keywords: Duchenne muscular dystrophy; CRISPR; animal models; in vivo testing; dystrophin; mutant generation
Online: 4 March 2020 (04:58:48 CET)
Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive neuromuscular disorder most commonly caused by mutations disrupting the reading frame of the dystrophin (DMD) gene. DMD codes for dystrophin, which is critical for maintaining the integrity of muscle cell membranes. Without dystrophin, muscle cells receive heightened mechanical stress, becoming more susceptible to damage. An active body of research continues to explore therapeutic treatments for DMD as well as to further our understanding of the disease. These efforts rely on having reliable animal models that accurately recapitulate disease presentation in humans. While current animal models of DMD have served this purpose quite well, each comes with their own limitations. To help overcome this, clustered regularly interspaced short palindromic repeats (CRISPR)-based technology has been extremely useful in creating novel animal models for DMD. This review focuses on animal models developed for DMD that have been created using CRISPR, their advantages and disadvantages as well as their applications in the DMD field.
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: Meta-analysis; p53 wild type antibodies; p53 mutant antibodies; cancer survival prognostic factor.
Online: 24 September 2021 (12:46:26 CEST)
Importance: p53 is an unequivocal tumor suppressor altered in half cancers. The immune system produces systemic p53 autoantibodies (p53 Abs) in many cancer patients. Objective: The focus of this systemic review and meta-analysis is on the prognostic value of p53 Abs expressed in the serum of patients with solid tumors. Data Sources: All the clinical investigations were searched on PubMed, MBase and Cochrane from 1993 reporting the first study until May 2021. Study Selection: Studies were included that met the following criteria: 1) participants with cancer; 2) outcome results expressed in relation to the presence of a p53 antibody; 3) a primary outcome (disease free survival, overall survival or progression free survival) expressed as hazard ratio (HR). The following exclusion criteria were used: 1) insufficient data available to evaluate outcomes; 2) animal studies; 3) studies with less than 10 participants. 1333 potentially relevant articles; studies as duplicates, non-patients studies or reviews were excluded. After viewing the titles and abstracts of the 52 remaining studies, the full texts of 34 studies were retrieved and 12 studies were included in the analysis. Data Extraction and Synthesis: PRISMA guidelines were used for abstracting and assessing data quality and validity by three independent observers. The summary estimates were generated using a fixed-effect model (Mantel–Haenszel method) or a random-effect model (DerSimonian–Laird-method) depending on the absence or presence of heterogeneity (I2). Main Outcome(s) and Measure(s): The primary study outcome was to determine the prognostic value of p53 Abs from a large population size of patients with solid tumors, as determined before data collection. Results: In total 12 clinical studies and of which 2094 patients were included and it was determined that p53-wt Abs expression in the serum significantly correlated with a worse survival of cancer patients (95% CI 1.48 [1.24, 1.77]; p<0.00001). On the contrary, data from literature indicated that there was a potential association between p53-mut Abs antibodies with better survival. Conclusions and Relevance: This is the first meta-analysis proving the diagnostic utility of p53-Abs for cancer patients, predicting a worse outcome. The serum-p53 value (s-p53-value) could be useful for future theranostics.
ARTICLE | doi:10.20944/preprints201903.0163.v1
Subject: Biology, Ecology Keywords: Ranavirus; FV3; vIF-2α knockout mutant; bath exposure; wood frog; sublethal effects; reservoir host
Online: 15 March 2019 (11:58:03 CET)
Ranaviruses have been associated with rising numbers of mass die-offs in amphibian populations globally. With life-stages occupying different environments and presenting distinct physiologies, amphibian of different ages are likely to play an important role in pathogen persistence. To assess the potential role of post-metamorphic amphibians as a Ranavirus reservoir, we performed a bath-exposure study on wood frogs using environmentally relevant doses (~103 and ~104 PFU/mL) of wild-type (WT) and knockout Frog virus 3 (FV3), deficient for the vIF-2α immune-evasion gene, the effects of which have never been addressed in post-metamorphic anurans. We observed 42% infection prevalence and low mortality (10%) across the virus challenges, with half of the mortalities attributable to ranavirosis. Prevalence and viral loads followed a dose-dependent pattern. Notably, when exposed to the vIF-2α knockout (DvIF-2α) FV3, individuals exhibited significantly decreased growth and increased lethargy in comparison to WT FV3 treatments. Although 85% of individuals in the virus treatments exhibited stereotypic signs of ranavirosis throughout the experiment, at termination (40 days post exposure) most individuals were clear of signs of infection. Overall, this study provides evidence that even a single short time exposure to environmentally relevant doses of Ranavirus may cause sublethal infections in post-metamorphic amphibians, thus indicating their possible role as a reservoir for this pathogen.
ARTICLE | doi:10.20944/preprints202003.0166.v1
Subject: Life Sciences, Biochemistry Keywords: vimentin; zinc; cysteine; redox sensing; intermediate filaments; cysteine mutant; filament bundling; filament width; divalent cations; magnesium
Online: 10 March 2020 (11:07:05 CET)
The intermediate filament protein vimentin constitutes a critical sensor for electrophilic and oxidative stress. We previously showed that vimentin interacts with zinc, which affects its assembly and redox sensing. Here we have used vimentin wt and C328S, an oxidation-resistant mutant showing improved NaCl-induced polymerization, to assess the impact of zinc on soluble and polymerized vimentin by light scattering and electron microscopy. Zinc acts as a switch, reversibly inducing the formation of vimentin oligomeric species. High zinc concentrations elicit optically-detectable vimentin structures with a characteristic morphology depending on the support. These effects also occur in vimentin C328S, but are not mimicked by magnesium. Treatment of vimentin with micromolar zinc induces fibril-like particles that do not assemble into filaments, but form aggregates upon subsequent addition of NaCl. In contrast, when added to NaCl-polymerized vimentin, zinc increases the diameter or induces lateral association of vimentin wt filaments. Remarkably, these effects are absent or attenuated in vimentin C328S filaments. Therefore, the zinc-vimentin interaction depends on the chemical environment and on the assembly state of the protein, leading to atypical polymerization of soluble vimentin, likely through electrostatic interactions, or to broadening and lateral association of preformed filaments through mechanisms requiring the cysteine residue. Thus, impact of zinc on vimentin assembly and redox regulation is envisaged.
ARTICLE | doi:10.20944/preprints202009.0273.v1
Subject: Life Sciences, Microbiology Keywords: Chromobacterium vaccinii; biofilm; sharing goods; social cheater; bog microbiome; bacterial genome, violacein, cold adaptation, IDBac, QS mutant
Online: 12 September 2020 (12:04:38 CEST)
Chromobacterium species are common in tropical and subtropical zones in environmental water samples and believed to «tropical» species. Here we describe an environmental case of resident Chromobacterium vaccinii in biofilms associated with Carex spp. roots in Moscow region, Russia (warm-summer humid continental climate zone). We performed broad characterization of individual properties as well as surrounding context for better understanding the premise of C. vaccinii survival during winter season. Genome properties of isolated strains propose some insights into adaptation to habit and biofilm mode of life, including social cheaters carrying ΔluxR mutation. Isolated C. vaccinii differs with previously described strains in some biochemical properties and some basic characteristics like fatty acid composition as well as unique genome features. Despite potential to modulate membrane fluidity and presence of several genes responsible for cold shock response, isolated C. vaccinii didn`t survive during exposure to 4 °C, while in initial complex biofilm it was able to survive for months in vitro at 4 °C. Surrounding bacterial community within the same biofilm with C. vaccinii represented a series of psychrophilic bacterial species which may share resistance to low temperatures with other species within biofilm and provide C. vaccinii opportunity to survive during cold winter season.
ARTICLE | doi:10.20944/preprints202208.0171.v2
Subject: Medicine & Pharmacology, Pharmacology & Toxicology Keywords: combination; antimicrobial resistance; selection index; collateral sensitivity; mutant prevention concentration; minimal inhibitory concentration; fractional inhibitory concentration index; stress factor
Online: 13 September 2022 (07:53:32 CEST)
Antimicrobial resistance (AMR) has been a serious threat to human health, and combination therapy is proved to be an economic and effective strategy to fight the resistance. However, the abuse of drug combinations would conversely accelerate the spread of AMR. In our previous work, it had been concluded that the mutant selection indexes (SIs) of one agent against a specific bacterial strain are closely related to the proportions of two agents in a drug combination. To discover probable correlations, predictors and laws for further proposing feasible principles and schemes guiding the AMR-preventing practice, here three aspects were further explored. First, the power function (y=axb, a > 0) correlation between the SI (y) of one agent and the ratio value (x) of two agents in a drug combination was further established based on the mathematical and statistical analyses for those experimental data, and two rules a1 × MIC1 = a2 × MIC2 and b1 + b2 = -1 were discovered from both equations of y=a1xb1 and y=a2xb2 respectively for two agents in drug combinations. Simultaneously, it was found that one agent with larger MPC alone for drug combinations show greater potency for narrowing itself MSW and preventing the resistance. Second, a new concept as mutation-preventing selection index (MPSI) was proposed and used for evaluating the mutation-preventing potency difference of two agents in drug combinations, and the positive correlation between the MPSI and the mutant prevention concentration (MPC) or minimal inhibitory concentration (MIC) was subsequently established. Inspired by this, the significantly positive correlation, contrary to previous reports, between the MIC and the corresponding MPC of antimicrobial agents against pathogenic bacteria was established using one hundred and eighty-one of data pairs reported. These results together of above three aspects indicate that the MPCs in alone and combination are very important indexes for drug combinations to predict the mutation-preventing effects and the trajectories of collateral sensitivity, and while the MPC of an agent can be roughly calculated from its corresponding MIC. Subsequently, the former conclusion was further verified and improved by the antibiotic exposure to forty-three groups designed as different drug concentrations and various proportions. The results further proposed that the C/MPC for the agent with larger proportion in drug combinations can be considered as a predictor and is the key to judge whether the resistance and the collateral sensitivity occur to two agents. Based on these above correlations, laws, and their verification experiments, some principles were proposed, and a diagram of the mutation-preventing effects and the resistant trajectories for drug combinations with different concentrations and ratios of two agents was presented. Simultaneously, the reciprocal of MPC alone (1/MPC), proposed as the stress factors of two agents in drug combinations, together with their SI in combination, is the key to predict the mutation-preventing potency and control the trajectories of collateral sensitivity. Finally, a preliminary scheme for antimicrobial combinations preventing the AMR was further proposed for subsequent improvement research and clinic popularization, based on the above analyses and discussion. Moreover, some similar conclusions were speculated for triple or multiple drug combinations.