Purpose: The low cloning efficiency with SCNT is due to incomplete or partial reprogramming of the donor somatic cell nuclei after microinjection into the enucleated oocyte. A possible solution may be to initiate nuclear reprogramming prior to SCNT.
Methods: Pre-exposure of donor somatic cell nuclei to a novel porcine ooplasmic extract prior to microinjection could possibly extend the duration of exposure to ooplamic nuclear reprogramming factors. The effects of the porcine ooplamic extract on two major markers of nuclear preprogramming: (1) TATA box protein binding to chromation and (2) DNA methylation was investigated.
Results: The results showed that pre-exposure of mouse cumulus cell nuclei to porcine ooplamic extract drastically reduced TATA box protein binding to chromatin, but had no effect on DNA methylation.
Conclusions: Pre-exposure to the porcine ooplasmic extract had some limited effects on nuclear reprogramming. Whether this can lead to enhanced cloning efficiency needs to be further investigated.