YAC CLONING MUS MUSCULUS TELOMERIC DNA - PHYSICAL, GENETIC, IN-SITU AND STS MARKERS FOR THE DISTAL TELOMERE OF CHROMOSOME-10

Three Mus musculus DBA/2 YAC libraries were constructed using a half-Y AC telomere cloning vector, This functional complementation approach y ields libraries which include terminal restriction fragments of the mo use genome, Screening all three libraries led to the isolation of 32 i ndependent clones which carry linear YACs containing the mouse termina l repeat sequence, (TTAGGG)(n), These YACs provide a resource to isola te regions of the mouse genome close to chromosome termini and exclude d from existing conventional YAC libraries, To demonstrate their utili ty, a hybridization probe was isolated from Mtel-1, the first (TTAGGG) (n)-containing YAC isolated, This probe detects a similar to 70 kb Kpn I fragment in the mouse genome which is sensitive to pretreatment with BAL31 exonuclease, A PCR-based genetic marker generated from the sequ ence of this probe maps 4.4 cM from the most distal anchor locus on ch romosome 10 in the EUCIB interspecific backcross, SIS primers for this locus, D10Hgu1, were used to isolate YAC 110F4 from a commercially av ailable mouse YAC library, Fluorescence in situ hybridization demonstr ates that YAC 110F4 hybridizes to the distal telomere of chromosome 10 , Clones in this collection of telomere YACs therefore partially overl ap clones in conventional YAC libraries, and thus the previously unava ilable terminal regions of the mouse genome can now be linked with the developing mouse STS YAC contig. Genetic markers such as D10Hgu1 allo w the ends of the mouse genetic map to be defined, thus closing the ma p.