title: Estrogenic effect of the phytoestrogen biochanin A in zebrafish, Danio rerio, and brown trout, Salmo trutta.
abstract: Isoflavones with estrogenic activity produced in Fabaceae plants are known to leach from agricultural areas to freshwater systems, but the effect of waterborne isoflavones in fish has not been thoroughly characterized. Therefore, the estrogenic effect of waterborne biochanin A was investigated in zebrafish (Danio rerio) and juvenile brown trout (Salmo trutta). Exposure of juvenile brown trout to 10 μg biochanin AL(-1) or higher caused marked vitellogenin induction after 9-10 days of exposure and so did exposure to 186 μg biochanin AL(-1) for 6h. Following 8d of exposure, a NOEC for induction of vitellogenin production in male zebrafish was 70 and LOEC 114 μg biochanin AL(-1). Exposure to 209 μg biochanin AL(-1) from hatch to 60 days post hatch (dph) caused a skewing of the sex ratio toward more phenotypic female zebrafish, but did not cause induction of vitellogenin in male and undifferentiated fish.
  
  
  CONCLUSIONS
  (1) biochanin A elicits estrogenic effects in trout at environmentally realistic concentrations, (2) brown trout plasma vitellogenin concentrations respond to lower biochanin A exposure concentrations than vitellogenin concentrations in zebrafish homogenates and (3) concerning vitellogenin induction, the hypothesis should be tested if short term tests with zebrafish may show a higher sensitivity than partial life cycle tests.
authors.affiliation: Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Holbech
authors.forename: Kristoffer D
authors.initials: KD
authors.lastname: Schröder
authors.forename: Marie L
authors.initials: ML
authors.lastname: Nielsen
authors.forename: Nanna
authors.initials: N
authors.lastname: Brande-Lavridsen
authors.forename: Bente Frost
authors.initials: BF
authors.lastname: Holbech
authors.forename: Poul
authors.initials: P
authors.lastname: Bjerregaard
mesh_terms: D000818:Animals; D004967:Estrogens / Q000633:toxicity*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D019833:Genistein / Q000633:toxicity*; D008297:Male; D012744:Sex Ratio; D046468:Sexual Development / Q000187:drug effects*; D014337:Trout; D014819:Vitellogenins / Q000097:blood / Q000235:genetics / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish
chemical_list: D004967:Estrogens; D014819:Vitellogenins; D014874:Water Pollutants, Chemical; D019833:Genistein; C004541:biochanin A
keywords: Biochanin A; Brown trout; Sex ratio; Vitellogenin; Zebrafish