2009 Poster Sessions : Dispensability of Mammalian DNA

Student Name : Cory McLean
Advisor : Gill Bejerano
In the lab, the /cis-/regulatory network seems to exhibit great functional redundancy. Many experiments testing enhancer activity of neighboring /cis-/regulatory elements show largely overlapping expression domains. Of recent interest, mice in which /cis-/regulatory ultraconserved elements were knocked out showed no obvious phenotype, further suggesting functional redundancy. Here, we present a global evolutionary analysis of mammalian conserved nonexonic elements (CNEs), and find strong evidence to the contrary. Given a set of CNEs conserved between several mammals, we characterize functional dispensability as the propensity for the ancestral element to be lost in mammalian species internal to the spanned species tree. We show that ultraconserved-like elements are over 300-fold less likely than neutral DNA to have been lost during rodent evolution. In fact, many thousands of noncoding loci under purifying selection display near uniform indispensability during mammalian evolution, largely irrespective of nucleotide conservation level. These findings suggest that many genomic noncoding elements possess functions that contribute noticeably to organism fitness in naturally evolving populations.

I am a 3rd year Ph.D. student in Gill Bejerano's lab. I am interested in using computational methods to learn about evolutionary and developmental biology. In particular, I have been studying gene regulation in the context of human and rodent evolution.