Environmental estrogens pose potential health risks to humans and wildlife by disrupting physiological and developmental processes; therefore, our laboratory has been designing in vivo bioassays on induction of the egg-yolk precursor protein vitellogenin. I have provided information on vitellogenin induction by estrogens in tiger salamanders (Ambystoma tigrinum), spotted salamanders (Ambystoma maculatum), hellbenders (Cryptobranchus alleganiensis), Morelet\u27s crocodiles (Crocodylus moreletii), and developed vitellogenin immunoassays in these species. Salamanders were estrogen-injected; blood was collected at intervals. Estrogen exposed male salamanders of all species, produced substantial quantities of a 200-kDa protein, the approximate size of vertebrate vitellogenins. Sequencing of estrogen-induced proteins showed substantial homology to known vertebrate vitellogenins. Tiger salamander vitellogenin N-terminus antibodies were produced, and crossreacted with serum from estrogen-treated but not control tiger salamanders. Vitellogenin assays for these species could study annual reproductive cycles, test waters for the presence of estrogenic agents or assess exposure of wild populations to environmental estrogens
