Abstract
This study investigated bovine somatic nucleus transplantation (NT) using an intracytoplasmic injection system in which cumulus cell nuclei were injected into enucleated oocytes by a piezo micromanipulator. Activation of NT embryos was carried out by (1) simultaneous injection of 2-4 pl of inositol 1,4,5 tri-phosphate (IP3) and a donor nucleus into a recipient cytoplasm (IP method), (2) IP method followed by 1.9 mM 6-dimethylaminopurine (DM) treatment for 3.5 h (IP+DM method), or (3) activated after NT by an ionomycin treatment (IA) followed by DM treatment (IA+DM method). We found the frequency of remodeling nuclei and development into blastocyst stage of NT embryos to be: IP, 44% and 9%; IP+DM, 58% and 29%; and IA+DM, 61% and 27%. These results indicate that IP3 injection into the intracytoplasm followed by DM treatment produces a similar bovine oocyte parthenogenetic activation as IA+DM activation treatment, and that intracytoplasmic nucleus injection is an effective method for bovine somatic NT.
