Homology-driven assembly of a sequence-ready mouse BAC contig map spanningregions related to the 46-Mb gene-rich euchromatic segments of human chromosome 19

Draft sequence derived from the 46-Mb gene-rich euchromatic portion of huma n chromosome 19 (HSA19) was utilized to generate a sequence-ready physical map spanning homologous regions of mouse chromosomes. Sequence similarity s earches with the human sequence identified more than 1000 individual orthol ogous mouse genes from which 382 overgo probes were developed for hybridiza tion. Using human gene order and spacing as a model, these probes were used to isolate and assemble bacterial artificial chromosome (BAC) clone contig s spanning homologous mouse regions. Each contig was verified, extended, an d joined to neighboring contigs by restriction enzyme fingerprinting analys is. Approximately 3000 mouse BACs were analyzed and assembled into 44 conti gs with a combined length of 41.4 Mb. These BAC contigs, covering 90% of HS A19-related mouse DNA, are distributed throughout 15 homology segments deri ved from different regions of mouse chromosomes 7, 8, 9, 10, and 17. The al ignment of the HSA19 map with the ordered mouse BAC contigs revealed a numb er of structural differences in several overtly conserved homologous region s and more precisely defined the borders of the known regions of HSA19-synt enic homology. Our results demonstrate that given a human draft sequence, B AC contig maps can be constructed quickly for comparative sequencing withou t the need for preestablished mouse-specific genetic or physical markers an d indicate that similar strategies can be applied with equal success to gen omes of other vertebrate species. (C) 2001 Academic Press.