Effects of methoprene, nonylphenol, and estrone on the vitellogenesis of the mysid Neomysis integer.

The induction of the female-specific protein, vitellogenin, in male fish is a well-established endpoint to assess exposure to estrogen-like chemicals. The use of vitellogenesis as a biomarker for xenobiotic exposure in egg-laying invertebrates, however, is still relatively unexplored. Recently, we developed a quantitative enzyme-linked immunosorbent assay (ELISA) for vitellin in Neomysis integer (Crustacea: Mysidacea) to study mysid vitellogenesis and its potential disruption by xenobiotics. In this study, gravid mysids were exposed to methoprene, nonylphenol, and estrone for 96 h. All methoprene-exposed (0.01, 1, and 100 microg/L) animals had lower vitellin levels compared to the control animals, though this effect was not statistically significant. Exposure to nonylphenol resulted in significantly induced vitellin levels in the lowest exposure concentration (0.01 microg/L), whereas no effects were observed at higher concentrations. Estrone significantly decreased vitellin levels at the highest test concentration (1 microg/L). These results indicate that mysid vitellogenesis can be disrupted following chemical exposure. Difficulties in the interpretation of the observed chemical-specific and concentration-specific responses in this study highlight the need for a better understanding of hormone regulation of crustacean vitellogenesis.