title: Development of the Larval Amphibian Growth and Development Assay: Effects of benzophenone-2 exposure in Xenopus laevis from embryo to juvenile.
abstract: The Larval Amphibian Growth and Development Assay (LAGDA) is a globally harmonized chemical testing guideline developed by the U.S. Environmental Protection Agency in collaboration with Japan's Ministry of Environment to support risk assessment. The assay is employed as a higher tiered approach to evaluate effects of chronic chemical exposure throughout multiple life stages in a model amphibian species, Xenopus laevis. To evaluate the utility of the initial LAGDA design, the assay was performed using a mixed mode of action endocrine disrupting chemical, benzophenone-2 (BP-2). X. laevis embryos were exposed in flow-through conditions to 0, 1.5, 3.0 or 6.0 mg l-1BP-2 until 2 months post-metamorphosis. Overt toxicity was evident throughout the exposure period in the 6.0 mg l-1treatment due to elevated mortality rates and observed liver and kidney pathologies. Concentration-dependent increases in severity of thyroid follicular cell hypertrophy and hyperplasia occurred in larval tadpoles indicating BP-2-induced impacts on the thyroid axis. Additionally, gonads were impacted in all treatments with some genetic males showing both testis and ovary tissues (1.5 mg l-1) and 100% of the genetic males in the 3.0 and 6.0 mg l-1treatments experiencing complete male-to-female sex reversal. Concentration-dependent vitellogenin induction occurred in both genders with associated accumulations of protein in the livers, kidneys and gonads, which was likely vitellogenin and other estrogen-responsive yolk proteins. This is the first study that demonstrates the endocrine effects of this mixed mode of action chemical in an amphibian species and demonstrates the utility of the LAGDA design for supporting chemical risk assessment. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: US EPA ORD/NHEERL/Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA. haselman.jon@epa.gov.
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Haselman
authors.affiliation: Institute of Environmental Ecology, IDEA Consultants Inc., 1334-5 Riemon, Yaizu, Shizuoka, 421-0212, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Sakurai
authors.affiliation: Institute of Environmental Ecology, IDEA Consultants Inc., 1334-5 Riemon, Yaizu, Shizuoka, 421-0212, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Watanabe
authors.affiliation: Institute of Environmental Ecology, IDEA Consultants Inc., 1334-5 Riemon, Yaizu, Shizuoka, 421-0212, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Goto
authors.affiliation: Institute of Environmental Ecology, IDEA Consultants Inc., 1334-5 Riemon, Yaizu, Shizuoka, 421-0212, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Onishi
authors.affiliation: Institute of Environmental Ecology, IDEA Consultants Inc., 1334-5 Riemon, Yaizu, Shizuoka, 421-0212, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Institute of Environmental Ecology, IDEA Consultants Inc., 1334-5 Riemon, Yaizu, Shizuoka, 421-0212, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Onoda
authors.affiliation: US EPA ORD/NHEERL/Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Kosian
authors.affiliation: US EPA ORD/NHEERL/Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA.
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Korte
authors.affiliation: US EPA ORD/NHEERL/Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA.
authors.forename: Rodney D
authors.initials: RD
authors.lastname: Johnson
authors.affiliation: Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.
authors.forename: Taisen
authors.initials: T
authors.lastname: Iguchi
authors.affiliation: US EPA ORD/NHEERL/Mid-Continent Ecology Division, 6201 Congdon Blvd, Duluth, MN, 55804, USA.
authors.forename: Sigmund J
authors.initials: SJ
authors.lastname: Degitz
mesh_terms: D000818:Animals; D001577:Benzophenones / Q000633:toxicity*; D001681:Biological Assay; D004305:Dose-Response Relationship, Drug; D004625:Embryo, Nonmammalian / Q000187:drug effects*; D052244:Endocrine Disruptors / Q000633:toxicity*; D004784:Environmental Monitoring / Q000379:methods*; D005260:Female; D006066:Gonads / Q000187:drug effects / Q000196:embryology / Q000254:growth & development; D007814:Larva; D008297:Male; D008675:Metamorphosis, Biological / Q000187:drug effects*; D013961:Thyroid Gland / Q000187:drug effects / Q000196:embryology / Q000254:growth & development; D014982:Xenopus laevis
chemical_list: D001577:Benzophenones; D052244:Endocrine Disruptors; C035476:2,2',4,4'-tetrahydroxybenzophenone
keywords: LAGDA; OCSPP 890.2300; OECD Test 241; Xenopus laevis; benzophenone-2; gonad dysgenesis; thyroid