Display Settings:   Send to:  Choose Destination Proc Natl Acad
Sci U S A. 2005 Feb 8;102(6):1957-62. Epub 2005 Jan 31.
Epigenetic memory of active gene transcription is inherited
through somatic cell nuclear transfer.     The transplantation
of somatic cell nuclei to enucleated eggs has shown that genes
can be reprogrammed to an embryonic pattern of expression,
thereby indicating a reversal of their epigenetic state.
However, in Xenopus nuclear transfer experiments using both
endoderm and neuroectoderm donor cells, we have observed
substantial overexpression of donor cell type-specific genes,
both spatially and temporally, in the wrong cell type in some
nuclear transplant embryos. For example, more than half of the
embryos prepared from transplanted neuroectoderm nuclei
overexpressed the neuroectodermal marker gene Sox2 to an
excessive level in their endoderm cells. Because, in Xenopus,
there is no transcription for the first 12 cell cycles, some
somatic cell nuclei must remember a developmentally activated