Meeting Abstract
Recent evidence indicates that some of California’s coastal estuaries are contaminated with 4-nonylphenol (4-NP), but it is not yet known whether the organisms inhabiting these environments are experiencing health impacts from this contamination. The chemical 4-NP is established as an endocrine disrupting compound that has estrogenic properties, and 4-NP exposure has been shown to alter testicular structure, decrease sperm counts, and cause intersex gonads in fish. In California’s estuaries, some of the highest tissue burdens of 4-NP recorded worldwide were found in the benthic intertidal arrow goby (Clevelandia ios). Here, we examined the impacts of 4-NP exposure for endocrine and reproductive function in the arrow goby, with the dual aims of validating biomarkers induced by xenoestrogen exposure in this species and determining the time course of detectable biomarker responses to 4-NP. Adult male arrow gobies were exposed in seawater (33 ppt) to either ethanol vehicle control (negative control), 17β-estradiol [E2] at 50 ng/L (positive control), 4-NP at 5 μg/L (low 4-NP dose), or 4-NP at 50 μg/L (high 4-NP dose). Fish were sampled at time points of 0 hrs (baseline), 24 hrs, 72 hrs, 12 days, and 20 days after commencing exposures, and relative expression levels of several estrogen-responsive genes (e.g., vitellogenin A [vtgA], vitellogenin C [vtgC], choriogenin L [cgL], choriogenin H [cgH]) were quantified using quantitative real-time RT-PCR. Exposure to E2 significantly elevated liver cgL and cgH mRNA levels within 24 hrs, liver vtgA within 72 hrs, and vtgC within 12 days. Our data thus far suggests that exposure of gobies to the high dose of 4-NP induced moderate elevations in liver choriogenin and vitellogenin transcript abundance, indicating the utility of quantifying mRNA levels of these genes as biomarkers for xenoestrogen exposure in this species.
