Non-methylated islands in fish genomes are GC-poor
- 11 April 1991
- journal article
- research article
- Published by Oxford University Press (OUP) in Nucleic Acids Research
- Vol. 19 (7) , 1469-1474
- https://doi.org/10.1093/nar/19.7.1469
Abstract
In the vertebrate genomes studied to date the 5′ end of many genes are associated with distinctive sequences known as CpG islands. CpG islands have three properties: they are non-methylated; the dinucleotide CpG occurs at the frequency predicted by base composition; and they are GC-rich. Unexpectedly we have found that CpG islands in certain fish only have the first two properties; that is, their GC-content is not elevated compared to bulk genomic DNA. Based on this finding, we speculate that the GC-richness of CpG islands in vertebrates other than fish is a passive consequence of a higher mutation rate in regions of open chromatin under conditions where the nucleotide precursor pools are biased.Keywords
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