Novel Methods for Physical Mapping of the Human 

 Genome Applied to the Long Arm of Chromosome 5 



Michael McClelland. Carol A. Westbrook.* Mike Weil. John Hanish. Mike Nelson. 



Yogesh Patel. Settara C. Chandrasekharappa.* Michelle M. Le Beau.* and 



Michelle Rebelsky* 



California Institute of Biological Research. La Jolla. CA 92037 



(619)535-5476 



*Department of Medicine. University of Chicago. Chicago, IL 60637 



The goal of this project is to develop and assess new approaches to megabase mapping 

 of a suhchromosomal region, specifically applied to chromosome 5. bands q23-31. This 

 region has been selected because, at 25 Mb. it is of manageable size and represents an 

 approach to the larger chromosomes. Our megabase map will consist of restriction sites 

 for enzymes that cleave infrequently and will link a series of probes that have been 

 mapped to 5q. The region is delineated, and the probes sublocalized. by means of 

 hybrids containing translocations and deletions in chromosome 5. some of which have 

 been prepared from leukemic cells of patients that carry chromosome-5 abnormalities. 

 The technology we plan to develop includes ( I ) enzymologic strategies and (2) methods 

 for the directed production of unique-sequence probes from the region of interest and 

 will include linking clones. The multimegabase strategies have been quite successful: 

 we have developed a reliable method for producing a partial digest of DNA in agarose. 

 In addition, several methylase/D/7/( 1 combinations are being evaluated, including one 

 that cleaves a 12-bp specificity. These approaches should generate fragments of over 

 500,000 bp in the human genome and facilitate the linking of probes. The map will have 

 interesting biological uses because the region contains the gene(s) for radiation/ 

 mutagen-induced leukemia, as well as for a variety of growth factors and receptors. 



