The Chinese rare minnow (Gobiocypris rarus) as an in vivo model for endocrine disruption in freshwater teleosts: a full life-cycle test with diethylstilbestrol.

Chinese rare minnow (Gobiocypris rarus), a freshwater teleost, was exposed to diethylstilbestrol (DES) at 0.05, 0.5, 1 and 5 microg/L from fertilized eggs for up to mature period under flow-through condition. Several endpoints that related to development, reproductive fitness and transgenerational effects were evaluated. It was found that body length and body weight were significantly reduced and vitellogenin (Vtg) levels were significantly increased for fish exposed to DES. Histological examination showed that the sex ratios of F0 fish skewed to female and about 2% of the fish exposed to 0.05 microg/L DES developed testes-ova. The reproductive success, as determined from data on egg production, was reduced in female fish exposed to 0.05, 0.5, 1 and 5 microg/L DES. The lowest-observed-effect concentrations (LOEC) for changes of sex ratios, reproductive success and histology alteration of F0 are 0.05 microg/L. In the offspring, transgenerational effects on egg hatching rate, egg fertilization and Vtg levels of juvenile individuals were not observed. However, survival of F1 generation fry significantly declined. The analysis of sex steroid levels revealed a significant decrease of testosterone (T) in the whole body homogenates (WBH) of male progeny and somewhat elevation of estradiol (E2) in the WBH of female offspring. These findings indicate that exposure to DES causes a variety of developmental, reproductive and transgenerational effects.