Mosquitofish (Gambusia affinis) vitellogenin: identification, purification, and immunoassay

Vitellogenin is a phospholipoglycoprotein precursor of egg yolk. In mature female fish, vitellogenin is synthesized and secreted by the liver in respo nse to circulating estrogens. Vitellogenin is normally undetectable in the blood of male fish, but can be induced by exposure to compounds possessing estrogenic activity. Thus, the presence of vitellogenin in blood of male fi sh can serve as a useful biomarker for assessing previous exposure to estro genic compounds. In the present study, we report identification and purific ation of vitellogenin in the mosquitofish (Gambusia affinis). Anti-vitellog enin immune serum was generated and used to develop an immunoblot assay for detection of vitellogenin. A combination of immunoblotting and densitometr ic scanning was used to assess the time- and dose-dependent effects of 17 a lpha -ethynyl-estradiol on vitellogenesis in male G. affinis. The results i ndicate that changes in the level of vitellogenin in mosquitofish blood can be reliably detected by the immunoblot assay, and that the mosquitofish ma y be a useful bioindicator organism for detecting estrogenic contamination of the aquatic environment. (C) 2001 Elsevier Science Inc. Al rights reserv ed.