Parental exposure to estrogenic EDCs (EEDCs) perturbs reproductive success and survival fitness of medaka offspring in a multigenerational manner

Increasing evidence suggests that direct exposure to EEDCs during embryonic development can induce multigenerational impacts on reproduction and survival fitness of offspring. Whether parental exposure to EEDCs can induce similar impairments in a multigenerational scale remains unclear in fish. Using the Oryzias melastigma as a model, a holistic approach was undertaken to assess the impacts of 17α-Ethinylestradiol (EE2) on reproduction and immune function of (i) parentally exposed progeny (PE) and (ii) parentally and embryonically exposed progeny (PEE). Adult medaka were exposed to a range of EE2 concentrations for 21 days. Reproductive success of exposed adults (F0) was evaluated through monitoring fertility, fecundity, and hatching success. PE eggs were raised in seawater, while the PEE eggs were raised in the same parental EE2 concentration until hatching. Immune competence of larvae and adults (F1) was assessed through host-resistance against bacteria assays. Offspring were raised to maturity and the sex ratio was monitored. Potential transgenerational impacts of EE2 were assessed by the same battery of reproductive and immune endpoints in the F2 and F3 generations. The results indicate that parental exposure alone can reduce survival fitness of F1 progeny and impair their resistance against pathogenic bacteria in a multigenerational, and possibly transgenerational manner. These novel findings (i) suggest that direct embryonic exposure is not the only scenario inducing multigenerational and transgenerational impacts on offspring and (ii) highlight the significance of taking a multigenerational approach to assess the impacts of EEDCs on survival fitness of offspring.