title: Molecular impact of juvenile hormone agonists on neonatal Daphnia magna.
abstract: Daphnia magna has been used extensively to evaluate organism- and population-level responses to pollutants in acute toxicity and reproductive toxicity tests. We have previously reported that exposure to juvenile hormone (JH) agonists results in a reduction of reproductive function and production of male offspring in a cyclic parthenogenesis, D. magna. Recent advances in molecular techniques have provided tools to understand better the responses to pollutants in aquatic organisms, including D. magna. DNA microarray was used to evaluate gene expression profiles of neonatal daphnids exposed to JH agonists: methoprene (125, 250 and 500 ppb), fenoxycarb (0.5, 1 and 2 ppb) and epofenonane (50, 100 and 200 ppb). Exposure to these JH analogs resulted in chemical-specific patterns of gene expression. The heat map analyses based on hierarchical clustering revealed a similar pattern between treatments with a high dose of methoprene and with epofenonane. In contrast, treatment with low to middle doses of methoprene resulted in similar profiles to fenoxycarb treatments. Hemoglobin and JH epoxide hydrolase genes were clustered as JH-responsive genes. These data suggest that fenoxycarb has high activity as a JH agonist, methoprene shows high toxicity and epofenonane works through a different mechanism compared with other JH analogs, agreeing with data of previously reported toxicity tests. In conclusion, D. magna DNA microarray is useful for the classification of JH analogs and identification of JH-responsive genes.
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; Department of Basic Biology, Faculty of Life Science, Graduate University for Advanced Studies (SOKENDAI), 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Toyota
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kato
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Miyakawa
authors.forename: Ryohei
authors.initials: R
authors.lastname: Yatsu
authors.forename: Takeshi
authors.initials: T
authors.lastname: Mizutani
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Ogino
authors.forename: Shinichi
authors.initials: S
authors.lastname: Miyagawa
authors.forename: Hajime
authors.initials: H
authors.lastname: Watanabe
authors.forename: Hiroyo
authors.initials: H
authors.lastname: Nishide
authors.forename: Ikuo
authors.initials: I
authors.lastname: Uchiyama
authors.forename: Norihisa
authors.initials: N
authors.lastname: Tatarazako
authors.forename: Taisen
authors.initials: T
authors.lastname: Iguchi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D003621:Daphnia / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D063990:Gene Ontology; D007605:Juvenile Hormones / Q000819:agonists*; D008297:Male; D008726:Methoprene / Q000633:toxicity*; D020411:Oligonucleotide Array Sequence Analysis; D048448:Phenylcarbamates / Q000633:toxicity*; D012098:Reproduction / Q000187:drug effects / Q000235:genetics; D013729:Terpenes / Q000633:toxicity*; D023382:Toxicity Tests, Acute; D036401:Toxicity Tests, Chronic; D059467:Transcriptome / Q000187:drug effects; D015854:Up-Regulation
chemical_list: D007605:Juvenile Hormones; D048448:Phenylcarbamates; D013729:Terpenes; D008726:Methoprene; C012154:epofenonane; C052034:fenoxycarb
keywords: Daphnia magna; gene expression; juvenile hormone agonists; juvenile hormone-responsive gene; microarray