1991 Fiscal Year Final Research Report Summary
Fundamental Studies on Nuclear Transplantation in Early Mammalian Embryos
| Project/Area Number |
01440016
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
畜産学(含草地学)
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| Research Institution | Okayama University |
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Principal Investigator |
NIWA Koji Okayama Univ., Fac. Agr., Professor, 農学部, 教授 (40089115)
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| Co-Investigator(Kenkyū-buntansha) |
YUHARA Masataka Okayama Univ., Fac. Agr., Professor, 農学部, 教授 (20032980)
OKUDA Kiyoshi Okayama Univ., Fac. Agr., Assoc. Professor, 農学部, 助教授 (40177168)
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| Project Period (FY) |
1989 – 1991
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| Keywords | Mammals / Early embryo / Blastomere fusion / Nuclear transfer / Electrofusion / Low temperature storage / Early development / In-vitro fertilization |
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| Research Abstract |
When 2-cell rat embryos were exposed to the electric pulse (s) 1.5-2.0 kv/cm of 100-200 ps duration, blastonere fusion did occur in 80-100% of the embryos. High proportion (6480%) of fused embryos developed to the morula-blastocyst stage after transfer into pseudopregnant females and being recovered 3 days later. Using the electrofusion technique, male and female prenuclei from 1-cell rat eggs, which had been stored at 2-6t for various durations, were transplanted into enucleated fresh eggs. Cleaving rate of the fused eggs with karyoplast stored for 0-144 h was 92-100%, but cleaving ability was completely lost in fused eggs with the karyoplast stored for 216 h. In further experiment, homologous and heterologous replacement of a small amount of cytoplasm or prenuclei were performed in rat and F, mouse pronuclear eggs. Fusion rates of recipient eggs with donor cytoplast were generally higher in homologous than heterologous combination. However, it was indicated that 1-cell rat cytoplasm may have factor (s) to induce 2-cell block not only in rat but in mouse eggs and that the embryonic genome can be activated in the heterospecific cytoplasm inducing new protein synthesis under an appropriate condition. Finally, in the experiments on in-vitro fertilization for obtaining normal cattle embryos, it was clarified that 1) oocytes reached metaphase-I at and after sperm penetration during the first meisis can complete maturation, 2) the highest proportion of normal in-vitro fertilization of oocytes could be obtained when oocytes were matured in culture for 20-24 h, and 3) protein supplement in fertilization medium containing caffeine and heparin is not required for in-vitro penetration of cumus-enclosed oocytes matured in culture.
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