A deleterious impact on the C. elegans fertility over generation after a chronic exposure to ionizing irradiation: A multigenerational transcriptomic evidence

Parental exposure to environmental stress factors during gestation as well as embryonal developmental may lead to deleterious consequences onto the offspring. In the present study, we assessed the adverse effects and mode of toxic action of chronic exposure to ionizing radiation over 4 generations in Caenorhabditis elegans (C. elegans). Our data show a decrease of 23% in the number of offspring on the first generation F0 and a decrease of more than 40% in subsequent generations F1, F2 and F3 from parental exposure.Transcriptomic analysis revealed modulation of a common set of genes functions betweenthrough generations that included transcription factors, as well as genes involved in stress response, unfolded protein response, lipid metabolism and reproduction. Furthermore, a drastic increase in the number of differentially expressed genes involved in defense response was measured in the last two generations, suggesting a cumulative stress effect of ionizing radiation exposure. Integration of these multi-scale data demonstrates that chronic gamma exposure can impact the germline and induce an increase in defense mechanisms, including apoptosis, antioxidant enzymes, and a modulation of lipid metabolism to improve resistance to stress. Harmful effects intensify over generations, after F0 at the phenotypic level F0 and F1 at the transcriptomic level , emphasizing the importance of studying effects of chronic exposure to pollutants over several generations. Overall design: RNAseq analysis of C elegans exposed chronically to 50 mGy/h of gamma ionizing radiation over 4 generations (exposed), or exposed over 1 generation and then grown under control conditions for a maximum of 3 generations (recovery), plus non exposed controls (control). All experiments made in 3 biological replicates.