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ASPECTS OF BASIC REPRODUCTIVE BIOLOGY AND ENDOCRINOLOGY IN THE FATHEAD MINNOW (PIMEPHALES PROMELAS)
Citation:
Jensen, K M., J J. Korte, M D. Kahl, M S. Pasha, AND G T. Ankley. ASPECTS OF BASIC REPRODUCTIVE BIOLOGY AND ENDOCRINOLOGY IN THE FATHEAD MINNOW (PIMEPHALES PROMELAS). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C128:127-141, (2001).
Description:
The fathead minnow has been proposed as a model species for assessing the adverse effects of endocrine-disrupting chemicals (EDCs) on reproduction and development. The purpose of these studies was to develop baseline reproductive biology and endocrinology data for this species to support interpretation of tests with potential EDCs. Pairs of reproductively-active fathead minnows (n = 70) were evaluated with respect to reproductive cyclicity in terms of spawning interval and fecundity. The mode and mean (plus or minus SE) spawning intervals for the fish in this study were 3.0 and 3.7 plus or minus 0.1 days respectively. The mean number of eggs produced per spawn was 85 plus or minus 2.8. Animals were sacrificed at periodic intervals during the established spawning cycle and measurements made of gonadal condition (gonadosomatic index [GSI] histopathology and plasma concentrations of vitellogenin and sex steroids (B-estradiol, testosterone, 11-ketotestosterone). The GSI in females varied significantly as a function of spawning interval, with the largest values occurring day 2 post-spawn, just prior to the interval of maximum spawning activity. Plasma B-estradiol concentrations in females
also varied significantly relative to peak values in the GSI and spawning activity. Vitellogenin
concentrations in the female, and male GSI and steroid concentrations did not vary significantly
relative to position in the spawning cycle. Concentrations of B-estradiol in females and 11-ketotestosterone in males were positively correlated with testosterone concentrations.