Comparison of gene transcription in cloned bovine embryos produced by different nuclear transfer techniques

The efficiency of animal production using cloning technology is still relat ively low and research to determine a more efficient nuclear transfer proce dure is ongoing. One approach which may be informative in assessing the via bility of nuclear transfer embryos Is the analysis of embryonic gene expres sion. Using RT-PCR techniques we have previously detected the aberrant expr ession of FGF4, FGFr2 and IL6 in a significant proportion of bovine granulo sa cell-derived nuclear transfer embryos, which correlated with a limited d evelopmental potential in vivo. In order to analyse the effect of different donor cell nuclei on embryonic gene expression we have now analysed the ex pression of these genes in nuclear transfer embryos reconstructed with feta l epithelial cell nuclei. In addition, we have compared the expression of t hese genes in bovine nuclear transfer embryos produced by cell fusion or di rect injection with variations in the timing of oocyte activation. In all n uclear transfer embryos analysed, FGFr2 and IL6 transcripts were detected a t a similar rate to that in IVF embryos. However, the absence of FGF4 trans cripts was again evident in a large proportion of nuclear transfer embryos and most significantly in those embryos whose development was activated alm ost Immediately following the transfer of the donor nucleus. The results de monstrate the effects that different donor cell lines and different nuclear transfer procedures may have on the expression of developmentally importan t genes in nuclear transfer embryos. (C) 2001 Wiley-Liss, Inc.