Abstracts (poster) - Wissenschaft Online

Andreas May, Daniela Weise, Kurt Reifenberg, Thomas Haaf, Ulrich Zechner
The impact of ovarian stimulation on the cellular epigenome in
preimplantation mouse embryos
Ovarian stimulation seems to impair genome-wide methylation reprogramming,
implantation and fetal development in mice and to increase the risk for imprinting
disorders in humans. To reveal the impact of ovarian stimulation on imprinted gene
methylation, we analyzed differentially methylated regions of H19 and Snrpn by
conventional bisulphite sequencing as well as bisulphite pyrosequencing in mouse 4-cell,
8-cell, and morula stage embryos derived from superovulated and non-superovulated
matings of C57BL/6J females with either C57BL/6J or Mus musculus castaneus (CAST/Ei)
males. In preimplantation embryos from C57BL/6J inbred matings, a significant loss of
methylation of H19 and Snrpn was found after superovulation. In contrast, our H19
methylation analysis of preimplantation embryos from superovulated and nonsuperovulated
intersubspecific (C57BL/6J x CAST/Ei) matings, which allowed
discrimination of parental alleles by a SNP, revealed no dramatic effect of ovarian
stimulation, but very similar methylation levels and expected methylation patterns with
the paternal and maternal allele predominantly methylated and unmethylated,
respectively. However, a significant percentage of both superovulated and
nonsuperovulated intersubspecific morula stage embryos displayed aberrant methylation
on the maternal H19 allele. The observed discrepancy in methylation levels between
superovulated embryos from inbred and intersubspecific matings may be due to the
action of complex modifiers acting in the intersubspecific genetic background. On the
other hand, in inbred embryos one can not distinguish between parental alleles and,
therefore, not exclude a PCR amplification bias due to the very small number of analyzed
cells.
contact:
Andreas May
Klinikum der Johannes Gutenberg Universität Mainz
Institut für Humangenetik
may@humgen.klinik.uni-mainz.de
Langenbeckstraße 1
55101 Mainz (Deutschland)