Bioaccumulation of human waterborne protozoa by zebra mussel (Dreissena polymorpha): Interest for water biomonitoring

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The immune proteome of the zebra mussel deciphered by deep proteogenomics

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Assessment of Toxoplasma gondii levels in zebra mussel (Dreissena polymorpha) by real-time PCR: an organotropism study

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Parental exposure to genotoxicant leads to reproduction impairment in the three-spined stickleback

International audienceThe aquatic environment is considered as the ultimate receptacle for anthropogenic compounds that frequently exhibit a genotoxic potential towards organisms. The reproductive process could influence the recruitment rate and hence the population dynamics. The link between the loss of DNA integrity in spermatozoa following paternal exposure to genotoxicant and reproduction impairment has been recently investigated in two fish species. These results have demonstrated a decrease in the progeny survival when sperm DNA was damaged and so, possible long term effects of environmental genotoxicant in aquatic systems. Such results needed to be confirmed through studies carried out in other fish species and the contribution of oocytes to further progeny defects had to be highlighted, as recently done in aquatic invertebrates. The aim of the present study was to investigate the link between DNA damage and reproductive impairment after in vivo exposure of stickleback to the genotoxic compound methyl methane sulfonate (MMS) during the breeding season, paying special attention to the contribution of genetic load brought by each sex to the observed progeny defects. Adult fish were acclimated and were then exposed or not through water to different MMS concentrations (0 / 0.05 uM / 0.5 uM / 5 uM). In vitro fertilization were realized with mature fish and DNA damage in spermatozoa and erythrocytes (as a biomarker of exposure for both sex) were assessed by the comet assay. The morphological abnormalities of larvae due to parental MMS exposure were studied and the progeny survival at embryogenesis and larval development key stages was evaluated. Parental exposure of three-spined stickleback to the genotoxicant MMS induced a significant decrease in early life stage survival which was less important when only females were exposed. When males or both genders were exposed, DNA damage level measured in spermatozoa (p<0.01) and exposure duration (p<0.01) were shown to be significant factors associated with progeny mortality. Whatever the gender, parental exposure to MMS resulted in a 60 fold increase in progeny abnormality frequency. This study underlines that male genotoxic message transmitted to progeny could predominate on the female one. Hence, this work confirms that spermatozoa are susceptible to accumulate DNA damage under chronic and low-dose exposure to genotoxic compounds, leading to drastic offspring defects in stickelback, as recently shown in other aquatic species

Protozoa interaction with aquatic invertebrate: interest for watercourses biomonitoring

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Kinetic response of a genotoxicity biomarker in the three-spined stickleback and implication for environmental monitoring

International audienceThe ultimate sink for the majority of anthropogenic compounds are the aquatic ecosystems, either through direct discharges or indirectly through hydrologic or atmospheric processes, possibly leading to long-term adverse effects in aquatic living resources. In order to assess exposure, fate and effects of chemical contaminants, aquatic ecotoxicologists have developed a large array of early-warning biomarkers proving that toxicants have entered organisms, have been distributed between organs and have triggered toxic effects regarding critical targets. However, optimal use of biomarkers in environmental studies previously requires in-depth knowledge of the kinetics of response of biomarkers. This work aimed to define as a first step of a validation process the kinetic response of a genotoxicity biomarker recently developed in the three-spined stickleback (Gasterosteus aculeatus). DNA damage was assessed in stickleback erythrocytes after in vivo exposure for 12 days to methylmethanesulfonate (MMS), an alkylating compound, followed by a 20 day-recovery period. Results show a dose-response relationship, time to maximal induction being reached after 6 days at the highest MMS concentration. No acclimation process was noticed during exposure whatever the MMS concentration, and genotoxicity decreased during the recovery phase only in fish exposed to the highest MMS concentration, suggesting more an effect of erythrocyte turn-over than of DNA repair system on the observed DNA damage level. Further field experiments are needed before including this genotoxicity biomarker in a battery of biochemical markers to monitor adverse effects of pollutants on fish health

Parental exposure to methyl methane sulfonate of three-spined stickleback: contribution of DNA damage in male and female germ cells to further development impairment in progeny

International audienceData regarding the link between DNA integrity of germ cells and the quality of progeny in fish exposed to genotoxicant are scarce although such information is of value to understand genotoxic effects of contaminants in aquatic fauna. This work aimed at studying the consequences of a parental exposure during the breeding season on offspring quality in three-spined stickleback. After in vivo exposure of adult fish to methyl methane sulfonate, a model alkylating compound, a clear increase in DNA damage was observed in erythrocytes of both genders, here used as a biomarker of exposure. MMS exposure significantly affected sperm DNA integrity but neither female fecundity nor fertilization success. In order to understand the contribution of each sex to potential deleterious effects in progeny due to parental exposure, mating of males and females exposed or not to MMS, was carried out. Exposure of both males and females or of males alone led to a significant increase in both mortality during embryo-larval stages and abnormality rate at hatching that appeared to be sensitive stages. Thus, in accordance with recent studies carried out in other freshwater fish species, such development defects in progeny were clearly driven by male genome, known to be devoid of DNA repair capacity in spermatozoa. The next step will be to investigate the link between DNA damage in stickleback sperm and reproductive impairment in natural populations exposed to complex mixture of genotoxicants

Zebra mussel as a new tool to show evidence of freshwater contamination by waterborne Toxoplasma gondii

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