title: Survey of estrogenic activity in fish feed by yeast estrogen-screen assay.
abstract: Fishes have been used as laboratory animal for research of estrogenic endocrine disrupters by many researchers. However, much less attention was paid to the possibility that compounds with estrogenic activity are present in fish diets. In order to examine this possibility, we measured the estrogenic activity in commercial fish feed by in vitro yeast estrogen-screen (YES) assay based on the binding ability of tested compounds to estrogen receptors. Estrogenic activity was detected in all the commercial fish feed examined (0.2-6.2 ng estradiol equivalent/g fish feed), some phytoestrogens (genistein, formononetin, equol and coumestrol; relative activity to estradiol, 8.6 x 10(-6)-1.1 x 10(-4) by giving a value of 1.0 to estradiol) and some androgens (testosterone, 11-ketotestosterone and 5 alpha-dihydrotestosterone; relative activity to estradiol, 3.0 x 10(-6)-1.2 x 10(-4)). Therefore, it is possible that these compounds could affect the results of in vivo estrogen assay, such as vitellogenin production in male fish, especially when fish are fed commercial feed.
authors.affiliation: Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan.
authors.forename: Takeru
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Makito
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Moriwaki
authors.forename: Shin'ichiro
authors.initials: S
authors.lastname: Kawai
authors.forename: Shugo
authors.initials: S
authors.lastname: Watabe
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D001681:Biological Assay; D004958:Estradiol / Q000592:standards; D004967:Estrogens; D005399:Fishes / Q000378:metabolism*; D008297:Male; D048789:Phytoestrogens / Q000032:analysis*; D011960:Receptors, Estrogen / Q000378:metabolism; D012015:Reference Standards; D013256:Steroids / Q000032:analysis*
chemical_list: D004967:Estrogens; D048789:Phytoestrogens; D011960:Receptors, Estrogen; D013256:Steroids; D004958:Estradiol