title: Planarian D-amino acid oxidase is involved in ovarian development during sexual induction.
abstract: To elucidate the molecular mechanisms underlying switching from asexual to sexual reproduction, namely sexual induction, we developed an assay system for sexual induction in the hermaphroditic planarian species Dugesia ryukyuensis. Ovarian development is the initial and essential step in sexual induction, and it is followed by the formation of other reproductive organs, including the testes. Here, we report a function of a planarian D-amino acid oxidase, Dr-DAO, in the control of ovarian development in planarians. Asexual worms showed significantly more widespread expression of Dr-DAO in the parenchymal space than did sexual worms. Inhibition of Dr-DAO by RNAi caused the formation of immature ovaries. In addition, we found that feeding asexual worms 5 specific D-amino acids could induce the formation of immature ovaries that are similar to those observed in Dr-DAO knockdown worms, suggesting that Dr-DAO inhibits the formation of immature ovaries by degrading these D-amino acids. Following sexual induction, Dr-DAO expression was observed in the ovaries. The knockdown of Dr-DAO during sexual induction delayed the maturation of the other reproductive organs, as well as ovary. These findings suggest that Dr-DAO acts to promote ovarian maturation and that complete sexual induction depends on the production of mature ovaries. We propose that Dr-DAO produced in somatic cells prevents the onset of sexual induction in the asexual state, and then after sexual induction, the female germ cells specifically produce Dr-DAO to induce full maturation. Therefore, Dr-DAO produced in somatic and female germline cells may play different roles in sexual induction.
authors.affiliation: Division of General Education and Research, Tsuyama National College of Technology, 624-1 Numa, Tsuyama, Okayama 708-8509, Japan.
authors.forename: Takanobu
authors.initials: T
authors.lastname: Maezawa
authors.affiliation: Department of Biochemistry and Molecular Biology, Shiga University of Medical Science, Seta, Ohtsu, Shiga 520-2192, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto 860-0811, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Nakagawa
authors.affiliation: Department of Biological Sciences and Informatics, Keio University, 3-14-1, Hiyoshi, Kouhoku-ku, Yokohama 223-8522, Japan.
authors.forename: Mizuki
authors.initials: M
authors.lastname: Ono
authors.affiliation: Department of Biological Sciences and Informatics, Keio University, 3-14-1, Hiyoshi, Kouhoku-ku, Yokohama 223-8522, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Aoki
authors.affiliation: Department of Biological Sciences and Informatics, Keio University, 3-14-1, Hiyoshi, Kouhoku-ku, Yokohama 223-8522, Japan.
authors.forename: Midori
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Department of Biochemistry and Molecular Biology, Shiga University of Medical Science, Seta, Ohtsu, Shiga 520-2192, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Ishida
authors.affiliation: Department of Biochemistry and Molecular Biology, Shiga University of Medical Science, Seta, Ohtsu, Shiga 520-2192, Japan.
authors.forename: Kihachiro
authors.initials: K
authors.lastname: Horiike
authors.affiliation: Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan. Electronic address: kobkyram@cc.hirosaki-u.ac.jp.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Kobayashi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003605:D-Amino-Acid Oxidase / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D005854:Germ Cells / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010053:Ovary / Q000196:embryology* / Q000378:metabolism; D010932:Planarians / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D012100:Reproduction, Asexual / Q000235:genetics*; D013737:Testis / Q000196:embryology / Q000378:metabolism
chemical_list: D003605:D-Amino-Acid Oxidase
keywords: Dugesia ryukyuensis; Ovarian development; Planarian; Sexual induction; d-Amino acid oxidase (DAO); d-Amino acids