Vitellogenin gene transcription: A relative quantitative exposure indicator of environmental estrogens

We report the development of a quantifiable exposure indicator for measurin g the presence of environmental estrogens in aquatic systems. Synthetic oli gonucleotides, designed specifically for the vitellogenin gene (Vg) transcr iption product, were used in a reverse transcription-polymerase chain react ion (RT-PCR) protocol. This extremely sensitive and rapid method was able t o detect vitellogenin gene transcription in male common carp (Cyprinus carp io) injected with 17 beta -estradiol. Sequence analysis of the induced mRNA product confirmed a vitellogenin gene transcript with homology to rainbow trout and fathead minnow vitellogenin cDNA sequences. Relative levels of vi tellogenin gene induction among individuals were quantified by incorporatin g 18S ribosomal RNA universal primers and Competimers (R) in a PCR multiple x reaction with primers for vitellogenin. This method is more sensitive tha n current protocols, such as mortality, visible signs of stress, or other t echniques that look for unscheduled gene expression, because it measures th e appearance of primary transcripts at the nanogram level. In addition, thi s procedure does not sacrifice accuracy or reliability, even though the exp osure to estrogen is within 1 d. This research will support the constructio n of regional stressor profiles, thereby providing a method for comparative environmental exposure assessment. It may also provide an in vivo screenin g method for potential endocrine-disrupting compounds.