Development of a multi-biomarker approach of genotoxicity on the three spined stickleback for aquatic biomonitoring application
Résumé
The aquatic environment is considered as the receptacle of anthropogenic
pressures, including chemical contamination as genotoxic compounds, which can
impact the health of aquatic species. Genotoxic substances may directly or indirectly
affect the integrity of cell’s genetic material, which can lead to long-term mutagenic,
carcinogenic or teratogenic effects. In this context, the measure of damages at different
genomic scales may be relevant and provide an integrated view of the genotoxic risk of
exposed organism. The finality of our work is to propose their use as early-warning
signals of potential long-term alterations to population and ecosystem health.
Genotoxicity assessment was performed on erythrocytes of the three- spined
stickleback by combining the measure of DNA integrity by the alkaline and Fpg
(formamidopyrimidines DNA glycosylase)-modified comet assays and the measure of
variations in nuclear DNA content by flow cytometry (FCM). In this sense, blood cells of
fish offer many advantages as cellular models as their ease of collection, gives a high
density of erythrocytes already dissociated allowing to obtain multiple assays on the
same sample. The alkaline comet assay has been largely used with erythrocytes of fish
to detect alkali-labile sites, DNA-double- and single- strand breaks. The Fpg-modified
comet assay has been optimized in the present study, which expand the comet assay
sensitivity to oxidized pyrimidines. Furthermore, FCM may be applied to assess the
variations in the nuclear DNA content of a large population of cells and has already
demonstrated its relevance for detecting chromosomal damages in blood cells of fish.
The presentation will detail results regarding the definition of baseline levels of
genotoxicity biomarkers (DNA strand breaks, Fpg-sensitive sites, DNA content,
erythrocyte mortality), which are useful in an ecotoxicological context. These biomarkers
have been measured in various field context (active biomonitoring) and integrated in the
existing multi-biomarker approach of the three-spined stickleback (Gasterosteus
aculeatus L., 1758).