Comparative genome sequence analysis of the Bpa/Str region in mouse and man

The progress of human and mouse genome sequencing programs presages the pos sibility of systematic cross-species comparison of the two genomes as a pow erful tool For gene and regulatory element identification. As the opportuni ties to perform comparative sequence analysis emerge, it is important to de velop parameters For such analyses and to examine the outcomes of cross-spe cies comparison. Our analysis used gene prediction and a database search of 430 kb of genomic sequence covering the Bpa/Str region of the mouse X chro mosome, and 745 kb of genomic sequence from the homologous human X chromoso me region. We identified 11 genes in mouse and 13 genes and two pseudogenes in human. In addition, we compared the mouse and human sequences using pai rwise alignment and searches For evolutionary conserved regions (ECRs) exce eding a defined threshold of sequence identity. This approach aided the ide ntification of at least Four further putative conserved genes in the region . Comparative sequencing revealed that this region is a mosaic in evolution ary terms, with considerably more rearrangement between the two species tha n realized previously from comparative mapping studies. Surprisingly, this region showed an extremely high LINE and low SINE content, low G+C content, and yet a relatively high gene density, in contrast to the low gene densit y usually associated with such regions.