Subject: Biology, Agricultural Sciences & Agronomy Keywords: Fitotoxicity; Seedling development; Germination; Micronuclei; Citotoxicity; Genotoxicity.
Online: 23 September 2022 (02:09:04 CEST)
Brazil is the number-one country in pesticide consumption, and corn is the second most cultivated crop in the country. Chemical control of weeds associated with corn cultivation is performed by application of herbicides with pre- and postemergence action, such as S-metolachlor. Currently, the toxicity of herbicides is a task of great concern. In this regard, the present study aimed to evaluate the effects of an S-metolachlor-based herbicide through bioassays with the plant model Lactuca sativa L. (lettuce) and Zea mays L. (maize). The herbicidal test solutions containing 7.5, 15, 30, 60, 120, 240, 360, 480, 600, and 720 mg L-1 of the active ingredient S-metolachlor were prepared from commercial products. Distilled water was used as a negative control, and aluminum was used as a positive control. Macroscopic analyses (germination and growth) were performed for the two species, and microscopic analyses (chromosomal and nuclear changes) were performed for L. sativa. Negative interference of the S-metolachlor-based herbicide on lettuce was observed for all macroscopic and microscopic parameters tested. In maize, there was no significant interference in germination; however, the herbicide interferes negatively in seedling development. In brief, the herbicide based on S-metolachlor has phytotoxic potential, just as discussed.
ARTICLE | doi:10.20944/preprints202208.0429.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: folate; folic acid; excess; UMFA; lymphocyte; micronuclei; fortification; methylation
Online: 25 August 2022 (08:06:05 CEST)
Mandatory fortification of food with the synthetic folic acid (FA) was instituted in 1998 to reduce the incidence of neural tube defects. Adequate folate status is correlated with numerous health benefits. However, elevated consumption of FA is controversially associated with deleterious effects on health. We previously reported that excess FA mimicked folate depletion in a lymphoblastoid cell line. To explore the impact of FA intake from fortified food, we conducted an observational human study on 33 healthy participants aged 18-40 not taking any supplements. Food intake, anthropomorphic measurements, and blood samples were collected and analyzed. Our results show that individuals belonging to the highest tertile of folic acid intake, as well as ones with the highest folic acid to total folate intake ratio (FAR), display a significantly greater incidence of lymphocyte genomic damage. A decrease in global DNA methylation is observed in the highest tertile of FAR compared to the lowest (P=0.055). A downward trend in the overall gene expression of select DNA repair and one carbon cycle genes (MGMT, MLH1, UNG, MTHFR, MTR) is noted with increased folate status and FA intake. These results provide supporting evidence that high consumption of FA from fortified foods can precipitate genomic instability in peripheral lymphocyte in-vivo.
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.