PARENT SESSION

TP5 Mechanisms of Toxic Action
203 Oregon Ballroom
1:20 PM - 4:40 PM, Tuesday

() Molecular cloning of aromatases (Arom) and estrogen receptors (ER) in killifish (Fundulus heteroclitus): differences in constitutive and inducible expression in populations from polluted and reference sites.

Greytak, Sarah¹, Hahn, Mark², Callard, Gloria¹, ¹ Boston University, Boston, MA, USA² Woods Hole Oceanographic Institute, Woods Hole, MA, USA

ABSTRACT- Epidemiological studies, supported by evidence from wildlife and laboratory animals, suggest that hormonally active agents (HAA) in the natural environment are responsible for abnormalities of reproduction and development. Although the New Bedford Harbor (NBH) fish population has survived and reproduced successfully for >50 yr (15 – 20 generations), they have high body burdens of the major NBH contaminants (polychlorinated biphenyls, PCBs). Also, NBH males express hepatic vitellogenin, indicating the presence of estrogen-like environmental contaminants (possibly hydroxylated PCBs). Previous studies show that NBH fish are resistant to the toxic effects of dioxin and PCBs, chemicals known to act via arylhydrocarbon receptor (AhR) signaling pathways. To understand how long term exposure, and multigenerational adaptations, to NBH pollutants affect molecular components of estrogen biosynthesis and response pathways, we are comparing the killifish population in NBH with fish at a reference site (Scorton Creek, SC). A multistep PCR cloning approach was used to isolate cytochrome P450 aromatases (AromB, AromA) and ER , -a, and b cDNAs. No site-specific polymorphisms in coding sequences were found. Quantitative real-time PCR analysis showed that tissue distributions of all five biomarkers were similar in the two populations, but constitutive levels of expression and responses to 17-estradiol and PCB 126 treatments revealed complex, site-specific differences. Although certain reproductive correlates were different in NBH and SC fish (GSI and HSI were significantly reduced in NBH), other parameters were unchanged. In conclusion, despite changes in estrogen biosynthetic and response pathways, and other evidence of endocrine disruption, NBH killifish continue to reproduce and develop successfully. –

Key words: Estrogen Receptor, Fundulus heteroclitus, Aromatase, polychlorinated biphenyls