Relative expression of cell growth regulatory genes insulin-like growth factors (IGF-1 and IGF-2) and their receptors (IGF-1R and IGF-2R) in somatic cell nuclear transferred (SCNT) and in vitro fertilized (IVF) pre-implantation buffalo embryos

Relative mRNA transcript expression of insulin-like growth factors, IGF-1, IGF-2 and their receptors, IGF-1R and IGF-2R, was studied in SCNT and IVF buffalo embryos at different developmental stages using SYBR green with real-time PCR. SCNT embryos were produced by enucleating IVM oocytes and transferring granulosa cells (passage 5) followed by the electrofusion and chemical activation method. IVF embryos were produced by culturing 15-20 COCs in BO capacitated sperms from frozen and thawed buffalo semen. SCNT embryo production rate was lower than IVF. IGF-1 mRNA expression was significantly upregulated at 2-cell, 16-cell, morula and blastocyst stages of SCNT embryos than in IVF embryos. IGF-1R expression declined from the 2-cell to the 16-cell stage, which increased in later stages and was highest in IVF blastocysts. Similar regulation was observed at different stages in SCNT embryos, except at the 4-cell stage where expression was higher. IGF-2 expression decreased up to the 8-cell stage and increased until the blastocyst stage, being higher in SCNT than IVF embryos. IGF-2R mRNA transcript expression was consistently lower in SCNT than in IVF embryos. Reprogramming of IGF-1, IGF-1R, IGF-2 and IGF-2R expression may have a significant role in cell proliferation in cloned embryos and is developmentally regulated. (C) 2009 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.