Effect of activation treatments of recipient oocytes on subsequent development of bovine nuclear transfer embryos

• Published in: The Japanese Journal of Veterinary Research Vol. 50; no. 4; pp. 185 - 194
• Main Authors: Atabay, E.C. (Hokkaido Univ., Sapporo (Japan)), Katagiri, S, Nagano, M, Takahashi, Y
• Format: Journal Article
• Language: English
• Published: Japan Graduate School of Veterinary Medicine Hokkaido University 01-02-2003
• Subjects: Animals; Calcimycin - pharmacology; CALCIUM; CATTLE; Cattle - physiology; Cycloheximide - pharmacology; EMBRYO CULTURE; Embryo Transfer - veterinary; Embryonic and Fetal Development - drug effects; Embryonic and Fetal Development - physiology; ETHANOL; Female; IONOPHORES; Ionophores - pharmacology; Nuclear Transfer Techniques; Oocytes - drug effects; Oocytes - physiology; Protein Synthesis Inhibitors - pharmacology
• ISSN: 0047-1917

「Abstract」Effects of recipient oocyte activation methods on the development of nuclear transfer(NT)embryos were investigated. In Exp. 1, cell-cycle phase of serum-starved bovine cumulus cells was examined by flow cytometry. Majority(95.5%)of medium-sized(16-20 μm)cells that made up 56% of total cells was at the G0/G1 phase. NT embryos were constructed by electric fusion with the medium-sized serum-starved cumulus cells and bovine oocytes of 3 different preparations：enucleated oocytes treated with calcium ionophore A 23187 for 5 min and cycloheximide for 5 hr(A 23187/CHX), those treated with ethanol for 7 min and cycloheximide for 2 hr(ethanol/CHX)and those without treatment. In Exp. 2 and 3, developmental competence of NT embryos constructed with A 23187/CHX-and ethanol/CHX-treated oocytes was compared to that of NT embryos constructed with non-treated oocytes, respectively. Further, nuclear behavior in 3 different NT embryos was examined in Exp. 4. Within 1 hr after fusion, majority of the NT embryos constructed with non-treated oocytes showed condensed chromosome. Three hours after fusion, about 50% of NT embryos constructed with non-treated or ethanol/CHX-treated oocytes showed a single pronucleus-like structure. NT embryos constructed with ethanol/CHX-treated oocytes showed similar rates of fusion, cleavage and blastocyst formation to those of the non-treated oocytes. In contrast, NT embryos constructed with A 23187/CHX-treated oocytes did not show any pronucleus-like structure and showed lower cleavage rate and no development to blastocysts. The results indicate that ethanol/CHX-treated oocytes could support development of somatic cell NT embryos to the blastocyst stage at a similar rate to that of non-treated oocytes.