Abstract
The objective of this study was to determine changes in the transcription of insulin-like growth factor (IGF)-related genes in blastocyst (BC)- and elongated (EL)-stage embryos produced by nuclear transfer using somatic cells (NT-SC). Bovine BC (day 7)- and EL (day 15)-stage embryos were obtained from NT-SC or in vivo production (Vivo). The relative abundance of mRNA was examined by RT- real-time PCR. The transcript of IGF-II was only detected at the EL stage in both the NT-SC and Vivo embryos. The level of transcription of the IGF-I receptor (r) in the NT-SC embryos was decreased at the EL stage and was significantly (P<0.05) lower than at the BC stage. In contrast, the IGF-IIr levels did not differ significantly between the NT-SC and Vivo embryos, regardless of the developmental stage. IGF-binding protein (IGFBP)-2 levels were markedly decreased in the NT-SC and Vivo embryos at the EL stage (P<0.05). The IGFBP-3 level in Vivo was significantly (P<0.05) increased at the EL stage compared with at the BC stage. However, the IGFBP-3 levels in NT-SC embryos were unchanged and lower (P<0.05) than in the Vivo embryos at the EL stage. These results suggest that there are differences in the levels and changes in the transcription of IGF-related genes in bovine embryos produced by NT-SC compared with those produced by Vivo.
