title: Effect of activation treatments of recipient oocytes on subsequent development of bovine nuclear transfer embryos.
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 microm) 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.
authors.affiliation: Laboratory of Theriogenology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
authors.forename: Edwin C
authors.initials: EC
authors.lastname: Atabay
authors.forename: Seiji
authors.initials: S
authors.lastname: Katagiri
authors.forename: Masashi
authors.initials: M
authors.lastname: Nagano
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002417:Cattle / Q000502:physiology*; D003513:Cycloheximide / Q000494:pharmacology; D004624:Embryo Transfer / Q000662:veterinary*; D005314:Embryonic and Fetal Development / Q000187:drug effects / Q000502:physiology*; D005260:Female; D007476:Ionophores / Q000494:pharmacology; D053652:Nuclear Transfer Techniques; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology
chemical_list: D007476:Ionophores; D011500:Protein Synthesis Inhibitors; D000001:Calcimycin; D003513:Cycloheximide