Plus Ça Change?

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Science  28 May 2004:
Vol. 304, Issue 5675, pp. 1207
DOI: 10.1126/science.304.5675.1207n

Generally speaking, noncoding segments of genomes change more rapidly than coding regions. Bejerano et al. (p. 1321, published online 6 May 2004) now describe a class of short genetic elements (>200 base pairs) in the human genome that has been extraordinarily conserved for 300 to 400 million years. Orthologs showed 100% identity for human, mouse, and rat sequences; slightly lower identity in chicken and dog; and some similarity observable in fish. RNA binding genes and transcription regulators were frequently found near these ultraconserved elements. Although the function of these elements has not yet been determined (nor the mechanism that preserved them), a working hypothesis is that they were important in vertebrate evolution.

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