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AROMATASE ACTIVITY IN THE OVARY OF MOSQUITOFISH GAMBUSIA HOLBROOKI, COLLECTED FROM THE FENHOLLOWAY AND ECONFINA RIVERS, FLORIDA (
Citation:
Orlando, E. F., W P. Davis, AND L. Guillette Jr. AROMATASE ACTIVITY IN THE OVARY OF MOSQUITOFISH GAMBUSIA HOLBROOKI, COLLECTED FROM THE FENHOLLOWAY AND ECONFINA RIVERS, FLORIDA (. Presented at Environmental Hormones: Past, Present, Future, Xavier University and Tulane University, New Orleans, LA, October 18-20, 1999.
Description:
Scientists are increasingly aware of the adverse effects of environmental contaminants, including their ability to alter the normal development and reproduction of wildlife species by modifying the endocrine system. Female mosquitofish living downstream of a paper mill plant located on the Fenholloway River, Florida have masculinized secondary sex characteristics. This masculinization includes altered anal fin development and reproductive behavior. Prior field and laboratory studies suggested the presence of an androgen in the effluent, possible derived from the microbial conversion of phytosterols. We agree the observed and induced male secondary sex characteristics are the result of an androgenic hormonal environment, but we propose a different mechanism of this androgenic milieu. We tested the hypothesis that component(s) of the effluent are inhibiting the activity of aromatase, the steroidogenic enzyme that converts androgens (A) to estrogens (E). Inhibition of aromatase would cause a decrease in estrogens and a concomitant increase in androgens, which could alter the normal hormonal profile of a female (decreasing the E/A ratio) to that resembling a male, thereby masculinizing its secondary sex characteristics. We predict aromatase activity will be lower in the ovaries from the Fenholloway females compared to the Econfina River mosquitofish. This seems reasonable, because it would support the observed phenomenon, and at least one phytosterol, enterolactone, has been shown to decrease aromatase enzyme activity. We collected 36 free-ranging, adult, female mosquitofish from both the Fenholloway and Econfina Rivers on the same day. Fish were transported to the lab and transferred to glass aquaria containing fresh water from their respective rivers. During the next three days, approximately one dozen fish from each site per day were anesthetized (150 ppm MS-222) and euthanized by decapitation. Standard morphometric data were obtained, as well as anal fin length and