2E-03 Long Conserved Noncoding Sequences (LCNS) are not mutational cold spots

Highly conserved genomic DNA sequences have been found between human and the other species by comparative sequence analyses even in noncoding sequences. We identified such conserved noncoding sequences which are aligned longer than 500 bp with more than 95% identity by the whole-genome comparison between human and mouse genomes. These Long Conserved Noncoding Sequences (LCNS) were distributed all over the genome, and many of the LCNS were also highly conserved not only in the other mammals but also chicken and fish. We measured the frequencies of ENU-induced mutations in the LCNS of the mouse. The frequencies were equivalent to those in the other genomic regions including coding sequences, introns and so on. This result suggests that the LCNS are not mutational cold spots. Thus, mutations have occurred equally in the LCNS but should have been removed from such populations by natural selection during the evolution.