作者: Marilyn Monk
关键词:
摘要: This review covers data on changing patterns of DNA methylation and the regulation gene expression in mouse embryonic development. Global demethylation occurs from eight-cell stage to blastocyst preimplantation embryos, global de novo begins at implantation. We have used X-chromosome inactivation female embryos as a model system study specific CpG sites X-linked Pgk-1 G6pd housekeeping genes imprinted regulatory Xist elucidate role initiation maintenance differential activity. Methylation very close time their inactivation, thus raising question whether could be causal well being involved its maintenance. A difference between sperm eggs promoter region gene, located centre, is correlated with preferential paternal X chromosome extra-embryonic tissues. Based our data, picture inheritance imprints speculation significance imprint development presented. On more general level, an hypothesis evolution by "adaptive epigenetic/genetic inheritance" considered. proposes modification germ line response change environment mutation site (e.g., methylated cytosine thymine). Epigenetic function shift buffer evolving against changes environment. If altered activity inactivity persist, modifications may become "fixed" mutations; alternatively, previously silenced networks might recruited into function, appearing if they are "acquired characteristics." An extension this "foreign acquisition sorting" (selection or silencing according use). "Kidnapping" sorting foreign way explain observation that increased complexity associated "junk" DNA. Adaptive challenges "central dogma" information unidirectional protein idea Darwinian random selection sole mechanisms evolution.