Functions for DNA Methylation in Vertebrates
This extract was created in the absence of an abstract.
Excerpt
The distribution of 5-methylcytosine (m5C) in vertebrate genomes is strikingly different from that in all other animal genomes that have been examined. In the vertebrates, almost all regions of the genome are subject to methylation, whereas in nonvertebrates, which include the vast majority of animal species, most of the genome appears free of methylation at all times (Bird et al. 1979; Bird and Taggart 1980). Methylation in nonvertebrate genomes, where it occurs, is confined to a small fraction of nuclear DNA. This “compartmentalized” distribution of m5C is in fact the most frequently observed pattern among multicellular eukary-otes (see, e.g., Bird and Taggart 1980; Antequera et al. 1984; Simoens et al. 1988). Why should the pattern of methylation in vertebrates be so different from the conventional pattern? The possibility considered here is that DNA methylation acquired new functions in the vertebrate lineage. Vertebrates have retained the ancestral function of DNA methylation—neutralization...
