| Project/Area Number |
20570054
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Morphology/Structure
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| Research Institution | Niigata University |
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Principal Investigator |
NOZAKI Masumi Niigata University, 自然科学系, 教授 (70136232)
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| Co-Investigator(Kenkyū-buntansha) |
UCHIDA Katsuhisa 宮崎大学, 農学部, 准教授 (50360508)
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| Project Period (FY) |
2008 – 2010
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| Project Status |
Completed (Fiscal Year 2010)
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| Budget Amount *help |
¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Fiscal Year 2010: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2009: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2008: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
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| Keywords | 比較内分泌 / ヌタナギ / 無顎類 / 下垂体 / 生殖腺刺激ホルモン / 性ステロイドホルモン / コレステロール側鎖切断酵素 / 時間分解蛍光免疫測定法 / ヌタウナギ / ゴナドトロピン / 組替えホルモン / 腺下垂体ホルモン / 組み換えホルモン |
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| Research Abstract |
Hagfishes, which lack both jaws and vertebrae, are considered the most primitive vertebrate known, living or extinct. Hagfishes have long been the enigma of vertebrate evolution not only due to their evolutionary position but also due to our lack of knowledge on fundamental processes. Key elements of the reproductive endocrine system in hagfish have yet to be elucidated. Here we report the first identification of a gonadotropic hormone (GTH) from the pituitary of the hagfish Paramyxine atami. The hagfish GTH consists of two subunits, α and β, which are synthesized and colocalized in the same cells of the adenohypophysis. The cellular and transcriptional activities of hagfish GTHα and β were significantly correlated with the developmental stages of the gonad. The purified native GTH induced the release of gonadal sex steroids in vitro. From our phylogenetic analysis, we propose that ancestral thyrostimulin alpha subunit and beta subunit gave rise to GTHα and GTHβ of the vertebrate glycoprotein hormone family, respectively. We hypothesize that the identity of a single functional GTH of the hagfish provides critical evidence for the existence of a pituitary-gonadal system in the earliest divergent vertebrate that likely evolved from an ancestral, pre-vertebrate exclusively neuroendocrine mechanism by gradual emergence of a new control level, the pituitary, that is not found in the Protochordates.
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