Developmental characteristics of SCNT pig embryos knocked-out of Alpha-1,3-galactosyltransferase gene

Abstract

This study was performed to comprehend the developmental characteristics of clone embryos knocked out (KO) of α-1,3-Galactosyltransferase (GalT) gene. Immature ooccytes were collected and cultured for 40 hrs (1-step) or 20hrs (with hormone) + 20hrs (without hormone) (2-step). The embryos transferred with miniature pig ear fibroblast cell were used as control. The reconstructed embryos were cultured in PZM-3 with 5% CO₂ in air 38.5℃ for 6 days. To determine the quality of the blstocysts, TUNEL and quantitative realtime RT-PCR were performed. The embryos were transferred to a surrogate (Landrace) at an earlier stage of the estrus cycle. The maturation rate was significantly higher in 2-step method than that of 1-step (p less than 0.05). The blastocyst development of GalT KO embryos was significantly lower than that of normal cloned embryos (p less than 0.05). The total and apoptotic cell number of GalT KO blastocysts was not different statistically from control. The relative abundance of Bax-α/BCL-xl ratio was significantly higher in both cloned blastocysts than that of in vivo blastocysts (p less than 0.05). Taken together, it can be postulated that the lower developmental potential and higher expression of apoptosis related genes in GalT KO SCNT embryos might be a cause of a low efficiency of GalT KO cloned miniature pig production.