HIGH-RESOLUTION PHYSICAL MAP OF THE IMMUNOGLOBULIN-LAMBDA VARIANT GENE-CLUSTER ASSEMBLED BY QUANTITATIVE DNA FIBER MAPPING

Quantitative DNA fiber mapping (QDFM) allows rapid construction of nea r-kilobase-resolution physical maps by hybridizing specific probes to individual stretched DNA molecules, We evaluated the utility of QDFM f or the large-scale physical mapping of a rather unstable, repeat-rich 850-kb region encompassing the immunoglobulin lambda variant (IGLV) ge ne segments. We mapped a minimal tiling path composed of 32 cosmid clo nes to three partially overlapping yeast artificial chromosome (YAC) c lones and determined the physical size of each clone, the extent of ov erlap between clones, and contig orientation, as well as the sizes of gaps between adjacent contigs. Regions of germline DNA for which we ha d no YAC coverage were characterized by cosmid to cosmid hybridization s. Compared to other methods commonly used for physical map assembly, QDFM is a rapid, versatile technique delivering unambiguous data neces sary for map closure and preparation of sequence-ready minimal tiling paths. (C) 1997 Academic Press.