Nuclear-cytoplasmic interactions during the first cell cycle of nuclear transfer reconstructed bovine embryos: implications for deoxyribonucleic acid replication and development

摘要: The present study investigated the decay of maturation-promoting factor (MPF) activity in electrically activated vitro-matured bovine oocytes and examined influence cell cycle stage both donor nucleus recipient cytoplasm upon morphology DNA synthesis potential reconstructed embryos. MPF was studied biochemically by morphological examination nuclear structure As measured H1 kinase groups 10 oocytes, level declined rapidly to 30 +/- 4% (of maximum unactivated control oocytes) at 60 min reached a basal 20 6% 120 min. This then maintained until least 9 h postactivation. In contrast, when assayed nuclei individual embryos, decline occurred over period arrested G1/S border G2 phases embryos time oocyte activation, i.e., levels were maximal, fusion postactivation, no could be detected. All transferred activation underwent envelope breakdown (NEBD) subsequent synthesis. However, after NEBD observed any nuclei. Nuclei or S phase absence synthesis, while into this cytoplasmic environment. results presented show that all nuclei, regardless stage, undergo replication transplanted metaphase II (MeII) cytoplasts which is high. From these observations we would suggest one may contribute low frequency development transfer ploidy embryo first cycle. order maintain correct embryo, only G1 should are integrity membrane absent, rereplication prevented maintained.