A 1.2-Mb YAC Contig Spans the quaking Region

We describe here a 1.2-Mb yeast artificial chromosome (YAC) contig within the region of mouse chromosome 17 between Brachyury (T) and D17Rp17e , and spanning the quaking (qk) region. We describe six new probes distributed across 1.2 Mb: D17Leh502, D17Leh503, D17Leh504, D17Leh505, D17Leh506, and D17Leh507. Probes D17Leh502 and D17Leh507 are at the extreme ends of the YAC contig. With the exception of D17Leh507, all of these probes are within a deletion associated with the quaking viable (qk v) allele of quaking. We have positioned these probes on a detailed YAC physical map together with two previously published probes, D17Leh508 and D17Aus119. We show here that D17Leh508 is also within the qk v deletion. Genetic mapping of D17Leh504 and D17Leh507 on two high-resolution genetic crosses carrying qk v and quaking lethal-1 (qk l-1) alleles shows that these probes do not recombine with quaking and are therefore within 0.04 cM of qk v and 0.05 cM of qk l-1 mutations. The deletion breakpoint contained within the YAC contig has been positioned to within 90 kb by restriction mapping of wildtype and mutant DNA. This contig will form the basis for identification and mapping of expressed sequences and for an investigation of genome organization.