Noncoding conservation

Whole genome comparisons between species that are either closely related or more phylogenetically separated—such as human, mouse, and dog—have revealed a subset of sequences that neither code for proteins nor are transcribed, yet are nevertheless conserved, but whose function is as yet unknown (conserved nongenic sequences, or CNGs). Emmanouil Dermitzakis and colleagues at the University of Geneva employed data-mining techniques to examine the extent to which these CNGs are spread across 14 mammalian species. In the October 2 Science, they report that CNGs are highly conserved in 14 species and constitute a new class of sequences that are even more evolutionarily constrained than protein coding regions (Science, DOI:10.1126/science.1087047, October 2, 2003).

Dermitzakis et al. analyzed 220 of 2262 previously identified CNGs found in human and mouse that had no transcriptional potential and compared them with protein-coding and noncoding RNA sequences in green monkey, ring-tailed lemur, brush-tailed porcupine,...