Multigenerational exposure to gamma radiation affects offspring differently over generations in zebrafish

Mutigenerational studies are now of great interest in ecotoxicology and previous studies have shown the importance of conducting multigenerational studies when assessing radiation toxicity in fish. In our study, the first objective was to study the early life stages (embryo-larval stages) and critical functions such as reproduction (which are generally studied in the context of ecological risk assessment (ERA)), in order to assess the sensitivity of zebrafish to ionizing radiation. The second objective was to assess acquisition of phenotypic effects at select life stages over generations. To our knowledge, this was the first time that irradiation of zebrafish (0.05 and 5 mGy.h(-1)) up to generation F2 was maintained with the following two exposure conditions: (1) recovery, only FO genitors were irradiated and the progeny were placed in control condition, (2) irradiated condition, all generations were exposed. Multigenerational irradiation affected Fl parental reproductive capacity (reproductive success) mainly over the first reproductive cycle (104d) and larval survival rate. Unexpected yet significant effects on sex ratio were observed in Fl progeny after parental irradiation (mainly at 5 mGy.h(-1)). These effects were observed for both conditions -irradiated and recovery- suggesting transmitted effects from FO genitors to offspring. All studied life stages were affected by ionizing radiation (IR), suggesting an alteration of vital physiological functions (reproduction and sexual determination). Such results highlight the hypothesis that IR affects population dynamics. In addition, the clear evidence of transmitted effects suggests worsening of effects at the population scale over generations. This approach is closer to environmental conditions to assess wild population fate, and thus highlights the importance of multigenerational studies to support ERA of ionizing radiation in fish.

Automated summary

In this study, the effects of radiation exposure on zebrafish across multiple generations were examined. The results showed that radiation impacted the reproductive capacity, larval survival rate, and sex ratio of the fish. These findings suggest that radiation can alter population dynamics and have worsening effects over generations. This highlights the importance of conducting multigenerational studies for assessing the ecological risk of radiation in fish.