Construction and characterization of radiation hybrids for chromosome 9, and their use in mapping cosmid probes on the chromosome.

Radiation hybrids were produced from a monochromosomal microcell hybrid (PK87-9) which contains only human chromosome 9 with an inserted marker on 9p. Doses of radiation ranging from 1000 to 8000 rads were used to produce a series of hybrids with different size fragments of human chromosome 9. The inserted dominant selectable marker was used to select for hybrids that preferentially maintain fragments of 9p. A panel of 53 radiation hybrids were characterized for 17 chromosome 9 markers. In addition, 17 hybrids were analyzed by fluorescent in situ hybridization (FISH). Hybrids were produced with breaks on both 9p and 9q, many of which appear to contain a single fragment of human chromosome 9. These hybrid cell lines were used to regionally localize 31 cosmids isolated from a chromosome 9 cosmid library. Six cosmids were mapped to intervals on 9p, six cosmids mapped to the centromeric region of the chromosome, and 19 mapped to 9q.