title: Medaka (Oryzias latipes) for use in evaluating developmental effects of endocrine active chemicals with special reference to gonadal intersex (testis-ova).
abstract: Japanese medaka (Oryzias latipes) has been widely used for the evaluation of the toxicity of endocrine active chemicals (EACs) and other chemicals as well as for monitoring the adverse effects of effluent discharges in relation to sexual development and function. It is useful for these evaluations for many reasons including the following: 1) it has a short life cycle facilitating studies extending over long phases of development and over multigenerations, 2) it is easy to rear, 3) male and female phenotypes can easily be distinguished on the basis of secondary sex characteristics, and 4) a genetic marker (DMY) is available for identifying the true genotypic sex. Several biomarkers have been found to be useful for identifying the effects of exposure to estrogenic and androgenic chemicals in medaka and they include increased levels of hepatic vitellogenin (VTG) and testis-ova induction in males for exposure to estrogenic chemicals, and decreased levels of hepatic VTG in females and an altered morphology of dorsal and anal fins and formation of papillae for androgenic chemicals. In this paper, we present a critical analysis of the use of medaka as a test species for studies of endocrine disruption and report on the use of sex-related genetic markers and alterations in gonadal development, including the induction of testis-ova formation, for assessing the disruptive effects of EACs. In this paper, we focus on some of the more recent studies and findings.
authors.affiliation: Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Urushitani
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Katsu
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kato
authors.forename: Osamu
authors.initials: O
authors.lastname: Tooi
authors.forename: Noriaki
authors.initials: N
authors.lastname: Santo
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kawashima
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Ohta
authors.forename: Yumi
authors.initials: Y
authors.lastname: Kisaka
authors.forename: Anke
authors.initials: A
authors.lastname: Lange
authors.forename: Charles R
authors.initials: CR
authors.lastname: Tyler
authors.forename: Rodney D
authors.initials: RD
authors.lastname: Johnson
authors.forename: Taisen
authors.initials: T
authors.lastname: Iguchi
mesh_terms: D000818:Animals; D052244:Endocrine Disruptors / Q000633:toxicity*; D005260:Female; D057850:Hermaphroditic Organisms; D008297:Male; D009990:Oryzias / Q000196:embryology*; D010063:Ovum / Q000187:drug effects*; D019849:Sex Determination Processes / Q000139:chemically induced / Q000503:physiopathology*; D013737:Testis / Q000187:drug effects*
chemical_list: D052244:Endocrine Disruptors