Search

Recently, research has contributed to better knowledge on the occurrence of pesticides in coastal water by identifying frequently detected substances, their concentration range and their acute and chronic toxicity for organisms. Pesticide pollution is of particular concern in France due to important agricultural activities and presence of several exoreic catchment areas that vehicle pesticides up to coastal waters, impacting non-target marine species. Several ecotoxicology questions remain to be addressed concerning the long-term effects of chronic pesticide exposure and the mechanisms involved in adaptation to chemical stress. In the present study, we brought new insights on the genetic and epigenetic effects of the herbicide diuron in oyster genitors. During gametogenesis, we exposed Crassostrea gigas to environmentally realistic herbicide concentrations (0.2–0.3 μg L−1 during two 7-day periods at half-course and end of gametogenesis). Diuron exposure was shown to decrease global DNA methylation and total methyltransferase activity in whole oyster tissue; this is consistent with the previous observation of a significant decrease in DNMT1 gene expression. Diuron effect seemed to be tissue-specific; hypermethylation was detected in the digestive gland, whereas diuron exposure had no effect on gill and gonad tissue. The genotoxicity of diuron was confirmed by the detection of one adduct in gonad DNA. By using in vitro approaches and human DNMT1 (DNMT1 has not been purified yet in bivalves), the presence of DNA lesions (adduct, 8-oxodGuo) was shown to interfere with DNMT1 activity, indicating a complex interaction between DNA damage and DNA methylation. Based on our results, we propose mechanisms to explain the effect of diuron exposure on DNA methylation, a widespread epigenetic mark. [ABSTRACT FROM AUTHOR]

An epidemiological survey was conducted in the Seine estuary and in two smaller and relatively preserved estuaries on the French Atlantic coast in order to estimate the occurrence of liver lesions in European flounder, Platichthys flesus, and also to seek putative risk factors for the recorded pathologies. Four hundred and seventy-eight fish of both sexes and of different size ranges were sampled in the three studied areas, 338 of which in the Seine estuary. All fish were examined for histopathological liver lesions, while DNA adducts and otoliths were analyzed on a subsample. Five categories of hepatic lesions were recorded with the following prevalence for the Seine estuary: 36.7 % inflammations, 8 % parasites (mainly encysted nematodes), 6.5 % foci of cellular alteration (FCA), 5.3 % foci of necrosis or regeneration (FNR), and 1.5 % tumors. Inflammation occurrence increased according to age, contrary to parasitic infestations and FCA which were more prevalent in young fish, notably those of <1 year old (group 0). Tumors were only observed in females of more than two winters. Females exhibited a higher prevalence of tumors (3.0 %) and FCA (6.5 %) than males (0 and 2.6 %, respectively). Parasitic and infectious lesions and FNR were equally distributed in males and females. The prevalence of FNR was also shown to vary according to sampling season, with significantly more occurrences of liver necrosis in the fish collected in summer than in spring. Spatial differences were observed with a higher occurrence of encysted parasites in flounders from the upper Seine estuary, while inflammations predominated in flounders living downstream. Temporal trends were also noted, with an increased prevalence of parasitic infestations, inflammations, and FCA in the 2002-2003 period in comparison to the 1996-1997 one. The three flounder populations from the Seine estuary (Normandy), Ster estuary (Brittany), and Bay of Veys (Normandy) showed different spectra of hepatic lesions. Flounders from the Bay of Veys had relatively few liver lesions as compared to flounders from the two other estuaries. Flounders from the Ster estuary exhibited the highest prevalence of parasites (37.2 %) and inflammations (51.1 %). Finally, FCA and liver tumors occurred at very similar levels in both flounder populations from the Seine and the Ster estuaries. Group 0 flounders inhabiting the upper Seine estuary were more prone to parasitic and pre-neoplastic hepatic lesions and had higher levels of liver DNA adducts than the older ones living downstream. It was postulated that group 0 European flounders may serve as valuable bioindicators for assessing the quality of estuarine waters and the health status of euryhaline fish populations. [ABSTRACT FROM AUTHOR]

Abstract: Genotoxic impact of the occupational exposure was measured in farmers from Normandy, France. White blood cell DNA-adduct levels were measured for 116 non-smoking French crop farmers, using the 32P-postlabelling method. A single blood sample was collected per farmer, at a randomised period of the year. Significantly higher bulky DNA-adduct levels were observed for samples collected from April to July, compared with samples collected during the other months. Agricultural practices were not significantly different between these two groups of farmers, but interestingly, the mean and the median duration without exposure to pesticides were significantly shorter for farmers sampled between April and July. These data, obtained in a homogeneous population of farmers, indicate a genotoxic impact for a sub-group, with a potential association with the use of pesticides. From the rest of the group, this study also gives for the first time additional information on the background fluctuations of this biomarker over the year. [Copyright &y& Elsevier]

Objectives: The purpose of this study was to examine whether polymorphisms in the XRCC1 DNA-repair protein can affect the base excision repair capacity to remove etheno-DNA adducts induced by vinyl chloride exposure that account for the occurrence of mutant biomarkers of effect seen in exposed workers.Materials and Methods: Using polymerase chain reaction-restriction fragment length polymorphism and fluorescence polarization techniques, we examined the effect of three x-ray cross complementing-1 protein polymorphisms, at codons 194, 280 and 399, on the occurrence of mutant biomarkers in ras-p21 and p53 induced by vinyl chloride exposure in a cohort of 211 French vinyl chloride workers to correlate differences in genotype with differences in the presence of these biomarkers. Also, cell cultures of lymphoblast lines from a pair of individuals, one homozygous wild-type and one homozygous variant for the codon 399 polymorphism, were exposed to the reactive intermediate of vinyl chloride, and, using an enzyme-linked immunosorbent assay, levels of etheno-DNA adducts generated and repaired were measured and compared.Results: After adjusting for age, smoking, alcohol drinking and cumulative vinyl chloride exposure, compared to workers who were homozygous wild-type for all alleles, the odds ratio for the presence of either biomarker increased to 2.0 (95% CI: 1.0-3.9) for workers with any one variant allele and to 2.4 (95% CI: 1.1-5.2) for workers with more than one variant allele. Data from the cell culture experiments indicating that repair of etheno-DNA adducts is considerably better in wild-type cells compared to polymorphic cells were supportive of the epidemiologic results.Conclusions: This study provides further evidence that polymorphisms in XRCC1 can be an important biomarker of susceptibility in populations exposed to agents that produce damage removed by base excision repair. [ABSTRACT FROM AUTHOR]

An in situ study of the relationship between marine contamination and genotoxic effects was performed on female dab (Limanda limanda) collected from different sites in the eastern English Channel (France) known to be contaminated by polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs). DNA adducts in liver and DNA strand breaks in blood cells were determined respectively by the nuclease P1-enhanced post-labelling technique and an alkaline version of the comet assay. The extent of DNA base oxidation was also assessed for three of the six sampling sites in the study, using a comet assay in combination with a specific DNA repair enzyme, formamidopyrimidine glycosylase (Fpg).With Comet data, two groups of sites that seem in accordance with the pollution level have been distinguished. The extent of DNA strand breaks was higher in adult than juvenile female dab. From a technical point of view, comet assay sensitivity was affected by high intra-individual variability that accounted for nearly 70% of total variance (the site factor represented no more than 26%). The combined use of the comet assay and Fpg showed the presence of DNA oxidised bases in environmentally exposed dab.Although qualitative differences between the sampling sites were observed in DNA adduct profiles, no significant differences were found for total DNA adduct levels. DNA adducts did not appear to be associated with PAH exposure.Histopathological studies showed hepatic steatosis in most of the animals examined. Only one pre-cancerous lesion (an early stage of hyperplasia) was detected (associated frequency of 0.8%). [Copyright &y& Elsevier]

We compared the abilities of two commonly used semen preparation techniques to decrease the amount of benzo(a)pyrene-diol-epoxide (BPDE)-DNA adducts in the spermatozoa of ten smokers. Semen processing by swim-up or discontinuous gradient centrifugation recovered spermatozoa showing an equally significantly lower amount of BPDE-DNA adducts than in unprepared spermatozoa from neat semen., (Copyright © 2011 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)