International Mammalian Genome Society

F40 High-Resolution Mapping and Transcript Identification at the sdy Locus on Mouse Chromosome 13

Wei Li¹, Vishnu S. Mishra², Yuke Zhang¹, Qing Zhang¹, Edward K. Novak¹, Nancy A. Jenkins³, Neal G. Copeland³, Stephen F. Kingsmore², Richard T. Swank¹. ¹Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Buffalo, NY 14263; ²Molecular Staging Inc., Guiford, CT 06437; ³Mammalian Genetics Laboratory, ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, Frederick, MD 21702

Sandy (sdy) is a mouse hypopigmentation mutant and an animal model for human Hermansky-Pudlak syndrome. High resolution genetic backcross and physical mapping studies have localized sdy to a 2.1 cM interval on mouse chromosome 13. Using closely linked microsatellite markers, we constructed a BAC contig which spans about 300 kb with 2 overlapping BACs encompassing the sdy critical region. 25 transcription units were identified within the 2 BACs by exon trapping and cDNA selection. One known gene, jumonji(jmj), and 5 known ESTs were found in a database search. The remaining 19 transcripts are novel. 18 of the 25 transcription units were confirmed to be in the two BACs by PCR or Southern blotting and to be expressed in kidneys from sandy and normal mice by RT-PCR and/or Northern blotting. No quantitative or size differences of the transcripts were found in kidneys of sdy/sdy and sdy /+ on Northern blots. One new polymorphism was found in an intron near the 3' end of the jmj gene. This polymorphism recombined with sdy, which may exclude jmj gene from sdy candidacy. 5' and 3' RACE of the ESTs and sample sequencing of the 2 BACs, which cover the critical region, are underway. This should allow the discovery of new genes around the sdy locus, and of the sdy gene itself.