Study of genetic damage in the Japanese oyster induced by an environmentally-relevant exposure to diuron: Evidence of vertical transmission of DNA damage

Abstract

Pesticides represent a major proportion of the chemical pollutants detected in French coastal waters and hence a significant environmental risk with regards to marine organisms. Commercially-raised bivalves are particularly exposed to pollutants, among them pesticides, as shellfish farming zones are subject to considerable pressure from agricultural activities on the mainland. The aims of this study were to determine (1) the genotoxic effects of diuron exposure on oyster genitors and (2) the possible transmission of damaged DNA to offspring and its repercussions on oyster fitness. To investigate these points, oysters were exposed to concentrations of diuron close to those detected in the Marennes-Oleron Basin (two 7-day exposure pulses at 0.4 and 0.6 μg L(-1)) during the gametogenesis period. Genomic abnormalities were characterized using two complementary approaches. The Comet assay was applied for the measurement of early and reversible primary DNA damage, whereas flow cytometry was used to assess the clastogenic and aneugenic effect of diuron exposure. Polar Organic Chemical Integrative Samplers (POCIS) were used in exposed and assay tanks to confirm the waterborne concentration of diuron reached during the experiment. The results obtained by the Comet assay clearly showed a higher level of DNA strand breaks in both the hemocytes and spermatozoa of diuron-exposed genitors. The transmission of damaged genetic material to gamete cells could be responsible for the genetic damage measured in offspring. Indeed, flow cytometry analyses showed the presence of DNA breakage and a significant decrease in DNA content in spat from diuron-exposed genitors. The transmission of DNA damage to the offspring could be involved in the negative effects observed on offspring development (decrease in hatching rate, higher level of larval abnormalities, delay in metamorphosis) and growth. In this study, the vertical transmission of DNA damage was so highlighted by subjecting oyster genitors to short exposures to diuron at medium environmental concentrations. The analysis of POCIS showed that oysters were exposed to integrated concentrations as low as 0.2 and 0.3 μg L(-1), emphasizing the relevance of the results obtained and the risk associated to chemical contamination for oyster recruitment and fitness.

Temporal and spatial distribution of semicarbazide in western Laizhou Bay

“…These results were in agreement with previous studies that reduced NRR was detected in mussels and clams following exposure to contaminants such as metals, organic xenobiotics and antibiotic drugs (Lowe and Moore, 1979;Dailianis et al, 2003;Nigro et al, 2006;Rank et al, 2007;Aguirre-Martinez et al, 2013). DNA damage can lead to reproductive impairment, abnormal development and lethal mutations, which has been used as a general stress biomarker to indicate the genotoxic risk (Anguiano et al, 2007;Barranger et al, 2014;Vazquez-Boucard et al, 2014). The present study clearly demonstrated that oysters from XZ and MP were suffered from significant DNA damage.…”

Occurrence of pharmaceutical compounds and pesticides in aquatic systems

“…In addition, repression of genes implicated in immune defense system and the inhibition of enzyme activities, such as laccase-type phenoloxidase (PO) and superoxide dismutase (SOD) in the plasma, were observed in Crassostrea gigas following 2 h exposure to diuron (1 lg/L) (Luna-Acosta et al, 2012). Moreover, in the same species exposed to diuron (0.2 and 0.3 lg/L measured with POCIS), higher levels of DNA strand breaks in both hemocytes and spermatozoa occurred in genitors during the gametogenesis period (Barranger et al, 2014).…”

Assessment of sperm quality in palaemonid prawns using Comet assay: methodological optimization

“…Previously, Akcha et al (2012) revealed that mature spermatozoa of the same species were highly sensitive to the genotoxicity of diuron, with an increase of DNA damage measured by the Comet assay after a 1-h-in vitro exposure from 0.05 μg L −1 . Likewise, it was demonstrated that genetic damage induced by a parental exposure to diuron in close concentrations to the ones tested here may be transmitted to progeny (Barranger et al 2014 ;Bouilly et al 2007). To our knowledge, no supplementary data exists in literature concerning the genotoxicity of diuron on spermatozoon of any other aquatic species.…”