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Culture medium is an important factor in in vitro embryo development. The efficacy of two culture media, the modified New Carolina State University-37 (NCSU-37) and the Porcine Zygote Medium-3 (PZM-3), for the development of pig embryos produced by somatic cell nuclear transfer was compared. A piezo manipulator was used to prepare enucleated oocytes and to perform somatic cell nuclear transfer. Intact reconstructed oocytes were selected and cultured at 38.5°C, 5% CO2,5% O2, 90% N2 for 7 days and then split into two groups. Group 1 was cultured in a glucose-free NCSU-37 medium supplemented with pyruvate and lactate for the first 2 days then subsequently cultured in a conventional NCSU-37 medium containing glucose for another 5 days. Group 2 was cultured in a PZM-3 medium for 7 days; with 10% fetal calf serum supplemented on day 5 (day 0 being the day of nuclear transfer). Cleavage rates, blastocyst rates and the number of cells in blastocyst on day 7 were compared between the groups. Cleavage and blastocyst rates in PZM-3 medium were significantly higher than those in NCSU-37 (79.2% vs 72.7% and 14.6% vs 10.5%, respectively; p < 0.05). The mean number of cells per blastocyst in group 1 was significantly higher than that in group 2 (48.4 vs 38.9, p < 0.05). In conclusion, the results suggested that the PZM-3 medium combined with serum is more suitable for the development of pig embryos produced by somatic cell nuclear transfer. [ABSTRACT FROM AUTHOR]

Tropomyosins are actin-binding proteins that play an important role in regulating the function of actin filaments in both muscle and non-muscle cells. Non-muscle tropomyosin (TPM3) is crucial for asymmetric cell division and maintenance of cortical integrity of murine oocytes. However, expression and function of TPM3 in porcine oocytes are unknown. In this study we investigated dynamic localization and expression level of TPM3 in porcine oocytes during meiotic maturation. Porcine oocytes collected from the ovaries of pre-pubertal gilts were incubated in TCM 199 maturation medium at 38.5°C in a humidified atmosphere of 5% C02. Denuded oocytes at different meiotic stages (germinal vesicle (GV), germinal vesicle breakdown (GVBD), metaphase I (MI), and metaphase II (MII)) were used for determining localization of TPM3 using immunostaining and expression level of TPM3 mRNA using quantitative PCR. Results showed that TPM3 protein was located at the membrane of oocytes in all four stages of maturation and the amounts of TPM3 mRNA were similar (p > 0.05) regardless of the stages. The further studies should be concentrated on the role of TPM3 in porcine oocytes. [ABSTRACT FROM AUTHOR]