title: In Vivo Administration of Scallop GnRH-Like Peptide Influences on Gonad Development in the Yesso Scallop, Patinopecten yessoensis.
abstract: Existing research on the role of gonadotropin-releasing hormone (GnRH) in bivalve reproduction is inadequate, even though a few bivalve GnRH orthologs have been cloned. The objective of this paper was to elucidate the in vivo effect of GnRH administration in Yesso scallop reproduction. We performed in vivo administration of scallop GnRH (py-GnRH) synthetic peptide into the developing gonad, and analyzed its effect on gonad development for 6 weeks during the reproductive season. The resulting sex ratio in the GnRH administered (GnRH(+)) group might be male biased, whereas the control (GnRH(-)) group had an equal sex ratio throughout the experiment. The gonad index (GI) of males in the GnRH(+) group increased from week 2 to 24.8% at week 6. By contrast the GI of the GnRH(-) group peaked in week 4 at 16.6%. No significant difference was seen in female GI between the GnRH(+) and GnRH(-) groups at any sampling point. Oocyte diameter in the GnRH(+) group remained constant (about 42-45 μm) throughout the experiment, while in the GnRH(-) group it increased from 45 to 68 μm i.e. normal oocyte growth. The number of spermatogonia in the germinal acini of males in the GnRH(+) group increased from week 4 to 6. Hermaphrodites appeared in the GnRH(+) group in weeks 2 and 4. Their gonads contained many apoptotic cells including oocytes. In conclusion, this study suggests that py-GnRH administration could have a potential to accelerate spermatogenesis and cause an inhibitory effect on oocyte growth in scallops.
authors.affiliation: Laboratory of Aquacultural Biology, Graduate School of Agricultural Science, Tohoku University, 1-1 Amamiya-machi, Tsutsumidori, Aoba-ku, Sendai, Miyagi, Japan.
authors.forename: Kazue
authors.initials: K
authors.lastname: Nagasawa
authors.affiliation: Laboratory of Aquacultural Biology, Graduate School of Agricultural Science, Tohoku University, 1-1 Amamiya-machi, Tsutsumidori, Aoba-ku, Sendai, Miyagi, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Oouchi
authors.affiliation: Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Itoh
authors.affiliation: Laboratory of Aquacultural Biology, Graduate School of Agricultural Science, Tohoku University, 1-1 Amamiya-machi, Tsutsumidori, Aoba-ku, Sendai, Miyagi, Japan.
authors.forename: Keisuke G
authors.initials: KG
authors.lastname: Takahashi
authors.affiliation: Laboratory of Aquacultural Biology, Graduate School of Agricultural Science, Tohoku University, 1-1 Amamiya-machi, Tsutsumidori, Aoba-ku, Sendai, Miyagi, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Osada
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage* / Q000494:pharmacology*; D006066:Gonads / Q000187:drug effects / Q000254:growth & development*; D020287:In Situ Nick-End Labeling; D008297:Male; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D049897:Pectinidae / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D010446:Peptide Fragments / Q000008:administration & dosage* / Q000494:pharmacology*; D012098:Reproduction / Q000187:drug effects / Q000502:physiology*; D017422:Sequence Analysis, DNA; D013091:Spermatogenesis / Q000187:drug effects; D013093:Spermatogonia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D007987:Gonadotropin-Releasing Hormone