Cosmids and transcribed sequences from chromosome 11q23.

To obtain cosmid markers and transcribed sequences from a specific chromosome region, a series of radiation-reduced hybrids (RHs) containing various regions of human chromosome 11 was prepared from microcell hybrid A9 (neo11) cells containing a normal human chromosome 11 tagged with pSV2neo at 11p11.2. Among 15 radiation hybrid clones isolated, RH(11)-9 which contains a q23 fragment in addition to the neo integration site, was used for the construction of a cosmid library. Cosmid clones having human DNA sequences were screened, and localized by Southern hybridization with the radiation hybrid panel. Fifty-nine cosmids were assigned to 11q23 and 6 cosmids to 11p11.2. Exon amplification proceeded with 23 of the 59 cosmids and 16 putative exons were cloned. Three of them were identical to those constituting a known gene which locates on q23 (ATDC), and the others were unknown. Thus, the RHs containing various subchromosomal fragments of chromosome 11 were useful for constructing region-specific DNA markers. The RH(11)-9 cells and putative exons also facilitate the positional cloning of genes in the 11q23 region.