title: Colcemid-treatment of heifer oocytes enhances nuclear transfer embryonic development, establishment of pregnancy and development to term.
abstract: Four experiments were designed to examine the effects of colcemid, a microtubule assembly inhibitor, on the development of bovine nuclear transfer (NT) embryos in vitro and in vivo. Recipient oocytes matured at different times were exposed to colcemid. Approximately 80-93% of the exposed oocytes, with or without the first polar body (PB1), developed obvious membrane projections. In Experiment 1, oocytes matured for either 14-15 or 16-17 hr, treated with colcemid and used as recipient cytoplasm for NT resulted in over 40% blastocyst development. In Experiment 2, oocytes matured for 16-17 hr were treated with either 0.2 or 0.4 microg/ml colcemid for 2-3 or 5-6 hr, respectively. The percentages of blastocyst development (39-42%) were not statistically different among the different colcemid treatment groups, but were both higher (P < 0.05) than the control group (30%). Colcemid concentrations and length of colcemid treatment of oocytes did not affect their ability to support NT embryo development to the blastocyst and hatched blastocyst stages. Results from Experiment 3 indicate that semi-defined medium increases morula and blastocyst development of NT embryos derived from colcemid-treated oocytes under 5% CO2 in air atmosphere. In addition, cell numbers of blastocysts in colcemid-treated groups were numerically higher than the control groups. After embryo transfer, higher (P < 0.05) pregnant rates were obtained from the colcemid-treated group than the nontreated group. Five of 40 recipients (12.5%) which received embryos from colcemid-treated oocytes delivered healthy calves, significantly higher than those recipients (3.3%) that received embryos derived from nontreated oocytes.
authors.affiliation: Department of Animal, Dairy and Veterinary Sciences, Utah State University, Logan, Utah 84321, USA. guangpengli@yahoo.com
authors.forename: Guang-Peng
authors.initials: GP
authors.lastname: Li
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: White
authors.forename: Kenneth I
authors.initials: KI
authors.lastname: Aston
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Bunch
authors.forename: Brady
authors.initials: B
authors.lastname: Hicks
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Sessions
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002417:Cattle; D022081:Cell Surface Extensions / Q000378:metabolism; D003703:Demecolcine / Q000494:pharmacology*; D018274:Electroporation; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000187:drug effects / Q000378:metabolism; D047108:Embryonic Development; D005260:Female; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D053652:Nuclear Transfer Techniques; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology; D011247:Pregnancy; D013997:Time Factors; D050257:Tubulin Modulators / Q000494:pharmacology*
chemical_list: D050257:Tubulin Modulators; D015544:Inositol 1,4,5-Trisphosphate; D016203:CDC2 Protein Kinase; D020928:Mitogen-Activated Protein Kinases; D003703:Demecolcine