The best results of inter-species nuclear transfer (iSCNT) in mammals were obtained using closely related species that can hybridize naturally. However, in the last years many reports describing blastocyst development following iSCNT between species with distant taxonomical relations (inter-classes, inter-order, inter-family) have been published. This indicates that embryonic genome activation (EGA) in xeno-cytoplasm is possible, albeit very rarely. Using a bovine-pig (inter-family) iSCNT model we studied the basic characteristics of EGA: expression and activity of RNA Polymerase II, formation of nucleoli (as an indicator of RNA Polymerase I activity), expression of the key pluripotency gene NANOG, and alteration of mitochondrial mass. In control embryos (obtained by in vitro fertilisation or intra-species nuclear transfer), EGA was characterised by RNA Polymerase II accumulation and massive production of poly-adenylated transcripts (detected with oligo dT probes) in blastomere nuclei, and formation of nucleoli as a result of RNA Polymerase I activity. Conversely, iSCNT embryos were characterised by the absence of accumulation and low activity of RNA Polymerase II and inability to form active mature nucleoli. Moreover, in iSCNT embryos, NANOG was not expressed, and mitochondria mass was significantly lower than in intra-species embryos. Finally, the complete developmental block at the 16-25-cell stage for pig-bovine iSCNT embryos and at the 4-cell stage for bovine-pig iSCNT embryos strongly suggests that EGA is not taking place in iSCNT embryos. Thus, our experiments clearly demonstrate poor nucleus-cytoplasm compatibility between these animal species.
|Titolo:||Development, embryonic genome activity and mitochondrial characteristics of bovine-pig inter-family nuclear transfer embryos|
|Settore Scientifico Disciplinare:||Settore VET/01 - Anatomia degli Animali Domestici|
|Data di pubblicazione:||ago-2010|
|Digital Object Identifier (DOI):||10.1530/REP-09-0578|
|Appare nelle tipologie:||01 - Articolo su periodico|