Induction of gene expression in sheepshead minnows (Cyprinodon variegatus)treated with 17 beta-estradiol, diethylstilbestrol, or ethinylestradiol: The use of mRNA fingerprints as an indicator of gene regulation

The recent interest in hormonally active environmental contaminants has spa rked a drive to find sensitive methods to measure their effects on wildlife . A molecular-based assay has been developed to measure the induction of ge ne expression in sheepshead minnows (Cyprinodon, variegatus) exposed in viv o to the natural and pharmaceutical estrogens 17 beta -estradiol, ethinyles tradiol, and diethylstilbestrol. This method used differential display reve rse transcriptase polymerase chain reaction assays to compare the expressio n of individual mRNAs from control and estrogen-exposed fish. Forty-eight d ifferentially expressed cDNAs were isolated by this method, including cDNAs for vitelline envelope proteins and vitellogenin. The mRNA expression patt erns for fish injected with a pharmacological dose of estradiol (5 mg/kg) w ere identical to those obtained in fish receiving constant aqueous exposure to 212 ng estradiol/liter. Further, the cDNA "fingerprint" pattern observe d in the estradiol-treated fish also matched that obtained in fish receivin g continuous-flow aqueous exposures to 192 ng ethinyl estradiol/liter and a nominal concentration of 200 ng diethylstilbestrol/liter. The results demo nstrate a characteristic expression pattern for genes upregulated by exposu re to a variety of natural and anthropogenic estrogens and suggest this app roach may be valuable to examine the potential effects of environmental con taminants on other endocrine-mediated pathways of reproduction, growth, and development. (C) 2001 Academic Press.