Transgenic systems in nuclear reprogramming.

Transgenic reporters have proved to be invaluable in the study of nuclear reprogramming, from demonstrating revival or silencing of gene expression in fusion hybrids to providing a means to display levels and distribution of specific gene products after nuclear transfer. Here, the method of piezo-assisted direct injection, which has been used previously to generate blastocysts and subsequently embryonic stem cell lines by transfer of nuclei from transgenic reporter mice, is described. This protocol differs from previously described techniques in that the donor nucleus is placed in the recipient oocyte before removal of the host metaphase plate.