Ultraconserved elements in the genome: Are they indi...(tells us nothing about when such changes...)

Redundancy is another possibility, says Ahituv, analogous to gene redundancy that can rescue the organism from expected abnormalities when vital genes are knocked out. "It may be that we saw no deleterious effects in the knockouts because nature provides a backup for these ultraconserved elements. We know that for one of the elements we chose, there are other noncoding ultraconserved elements positioned near it in the genome that show similar enhancer activity. These may rescue the organism from the abnormalities we speculated would be caused by the missing ultraconserved sequences -- though this still does not explain why they are so ultimately conserved."

The discovery that deletion of ultraconserved elements does not render mice unviable or infertile is a major challenge to our understanding of how highly conserved elements of the genome persist and what their functions are, says Ahituv. He and his colleagues are pursuing research aimed at answering these compelling new questions.

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