58 DEVELOPMENT OF α1,3-GALACTOSYLTRANSFERASE KNOCK-OUT CLONED PIG EMBRYOS

Abstract

This study was performed to increase the developmental rate of cloned embryos with the 1,3-Galactosyltransferase (GalT) gene knocked out (KO). Ovaries were collected from local slaughterhouse and immature oocytes were cultured in TCM-199 + 0.1% PVA + FSH + LH (0.5 μg mL-1) + EGF (10 ng mL-1) + 10% porcine follicular fluid (pFF) at 38.5°C in 5% CO2 humidified chamber for 40 h (1-step) or 20 h (with hormone) +20 h (without hormone; 2-step). After IVM, the oocytes with 1st polar body were enucleated and transferred the GalT KO donor cell originated from miniature pig. The embryos transferred with normal mini-pig ear fibroblast cell were used as control. The reconstructed embryos were fused with 2 electric pulses (DC) of 1.2 kV cm-1 for 30 μs. For the development of cloned embryos, the embryos were cultured in PZM-3 under 5% CO2 in air at 38.5°C for 6 days. The embryos were transferred to a surrogate (Landrace) at an earlier stage of the estrus cycle, and pregnancy diagnosis was determined at 28 days after embryo transfer using ultrasonography. Differences among treatment means were determined by a chi-square test. A probability of P < 0.05 was considered statistically significant. The maturation rate was significantly higher in the 2-step method (89.8 ± 2.75) compared with single maturation method (79.6 ± 8.95; P < 0.05). The blastocyst development of cloned embryos reconstructed with GalT KO donor cell (28.4 ± 2.14) was not different from cloned embryos by normal donor cell (27.4 ± 0.01). The cell number of GalT blastocyst (36.1 ± 11.1) was not different statistically from control (26.9 ± 9.3). The apoptosis rate was also not different in both groups (2.9 to 4.9%). Five surrogates were pregnant and the GalT KO fetuses were still ongoing pregnancy at 45 days after embryo transfer. This work received grant support from the Agenda Program (No. 200901FHT010305146 and No. 200901FHT010305535), Rural Development Administration, Republic of Korea.