The chromosomal constitution of postmitotic neurons, assessed by neuronal nuclear transfer into oocytes and in ES cell lines derived from them

Abstract

Spectral karyotyping (SKY) was used to assess the chromosomal constitution of embryos generated by nuclear transfer (NT) of neuronal nuclei (N-NT) or cumulus cell nuclei (C-NT) into oocytes and of their embryonic stem cell derivatives (ntES cells). We detected chromosomal changes during the first mitotic cleavage and in the condensed chromatids of NT embryos. We also found clonal translocations in the ntES cells that were derived from NT embryos cloned from neuronal nuclei. The differentiation potentials of the ntES cells showing chromosomal rearrangements were partly restricted. Our findings indicate that balanced or unbalanced chromosomal translocations can occur in early NT embryogenesis, suggesting that a DNA repair system is activated during both NT embryogenesis and ntES cell establishment. We observed a higher incidence of chromosomal changes in N-NT than in C-NT embryos, which may reflect a higher frequency of double-stranded (ds) DNA breaks in the neuronal genome.