title: Development of the GABA-ergic signaling system and its role in larval swimming in sea urchin.
abstract: The present study aimed to elucidate the development and γ-amino butyric acid (GABA)-ergic regulation of larval swimming in the sea urchin Hemicentrotus pulcherrimus by cloning glutamate decarboxylase (Hp-gad), GABAA receptor (Hp-gabrA) and GABAA receptor-associated protein (Hp-gabarap), and by performing immunohistochemistry. The regulation of larval swimming was increasingly dependent on the GABAergic system, which was active from the 2 days post-fertilization (d.p.f.) pluteus stage onwards. GABA-immunoreactive cells were detected as a subpopulation of secondary mesenchyme cells during gastrulation and eventually constituted the ciliary band and a subpopulation of blastocoelar cells during the pluteus stage. Hp-gad transcription was detected by RT-PCR during the period when Hp-Gad-positive cells were seen as a subpopulation of blastocoelar cells and on the apical side of the ciliary band from the 2 d.p.f. pluteus stage. Consistent with these observations, inhibition of GAD with 3-mercaptopropioninc acid inhibited GABA immunoreactivity and larval swimming dose dependently. Hp-gabrA amplimers were detected weakly in unfertilized eggs and 4 d.p.f. plutei but strongly from fertilized eggs to 2 d.p.f. plutei, and Hp-GabrA, together with GABA, was localized at the ciliary band in association with dopamine receptor D1 from the two-arm pluteus stage. Hp-gabarap transcription and protein expression were detected from the swimming blastula stage. Inhibition of the GABAA receptor by bicuculline inhibited larval swimming dose dependently. Inhibition of larval swimming by either 3-mercaptopropionic acid or bicuculline was more severe in older larvae (17 and 34 d.p.f. plutei) than in younger ones (1 d.p.f. prism larvae).
authors: Research Center for Marine Biology, Tohoku University, Asamushi, Aomori, Aomori 039-3501, Japan. hkatow@m.tohoku.ac.jp
authors: Hideki
authors: H
authors: Katow
authors: Kouki
authors: K
authors: Abe
authors: Tomoko
authors: T
authors: Katow
authors: Alemeh
authors: A
authors: Zamani
authors: Hirokazu
authors: H
authors: Abe
mesh_terms: D015097:3-Mercaptopropionic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002923:Cilia / Q000187:drug effects / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D005968:Glutamate Decarboxylase / Q000737:chemistry / Q000378:metabolism; D047330:Hemicentrotus / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D007150:Immunohistochemistry; D007814:Larva / Q000187:drug effects / Q000502:physiology; D008018:Life Cycle Stages / Q000187:drug effects / Q000235:genetics; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D011963:Receptors, GABA-A / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013550:Swimming / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D008869:Microtubule-Associated Proteins; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D015097:3-Mercaptopropionic Acid; D005968:Glutamate Decarboxylase; D001640:Bicuculline