VITELLOGENESIS AND THE REGULATION OF VITELLOGENIN GENE EXPRESSION IN THE SCALLOP.
Grant-in-Aid for Scientific Research (C)
|Allocation Type||Single-year Grants|
|Research Institution||TOHOKU UNIVERSITY|
OSADA Makoto GRADUATE SCHOOL OF AGRICULTURAL SCIENCE, TOHOKU UNIVERSITY, ASSOCIATE PROFESSOR, 大学院・農学研究科, 助教授 (30177208)
|Project Period (FY)
1998 – 2000
Completed(Fiscal Year 2000)
|Budget Amount *help
¥3,400,000 (Direct Cost : ¥3,400,000)
Fiscal Year 2000 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1999 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1998 : ¥1,800,000 (Direct Cost : ¥1,800,000)
|Keywords||Scallop / Ovary / Vitellogenin / cDNA / Estrogen / Central Nervous System / Oocyte Growth|
(1) Hormonal regulation of yolk protein formation and producing site of vitellogenin
The increase in yolk protein and total RNA contents in the scallop ovary during oocyte growth and the promoting effect of estradiol-17β(E_2) and cerebral and pedal ganglion (CPG) extract on yolk protein formation in in vivo and in vitro experiment indicated that ovary should be a producing site of vitellogenin and E_2 and a factor in CPG which is heat stable, trypsin and chymotrypsin resist and less than 10,000 of molecular weight promotively regulate vitellogenesis. The founding of estrogen receptor (ER) like immuno-reactivity only in the young oocytes suggested the autosynthetic system in the scallop vitellogenesis and the possibility of the E_2-induced vitellogenesis promoted by CPG based on the ER induction.
(2) Cloning of vitellogenin cDNA and regulation of vitellogenin gene expression.
Cloned vitellogenin cDNA (clone No. cSYP-1, Accession No. AB055960) from cDNA library of scallop ovary was an incom
plete length (1698 bp) with initiation codon and a actual vitellogenin mRNA was found to be 12-13 kb according to northern blot analysis. A homology and molecular phylogenic tree analysis of the amino acid sequence deduced from cDNA sequence strongly supported that the sequence was vitellogenin cDNA.The expression of vitellogenin mRNA increased during oocyte growth, but still kept the same level at spawning season when the ovary was full of many full grown oocyte. In vitro culture associated with CPG showed no influence on vitellogenin mRNA level, very unlike vitellogenesis.
From these results, the following tentative conclusion is proposed Endogenous estrogen induces vitellogenin in the oocyte via ER autosynthetically and vitellogenin is modified and accumulated into the oocyte. A factor from CPG which promotes the E_2-induced vitellogenesis enhances the vitellogenin gene transcription and the translation at the same time. Full grown oocyte terminate translation of vitellogenin mRNA which appeared to be long half-life. Less
Research Products (6results)