Mouse molecular cytogenetic resource: 157 BACs link the chromosomal and genetic maps

We have established a collection of strong molecular cytogenetic markers th at span the mouse autosomes and X chromosome at an average spacing of one p er 19 Mb and identify 127 distinct band landmarks. In addition, this Mouse Molecular Cytogenetic Resource relates the ends of the genetic maps to thei r chromosomal locations. The resource consists of 157 bacterial artificial chromosome (BAC) clones, each of which identifies specific mouse chromosome bands or band borders, and 42 of which are linked to genetic markers that define the centromeric and telomeric ends of the Whitehead/MIT recombinatio nal maps. In addition, 108 randomly selected and 6 STS-linked BACs have bee n assigned to single chromosome bands. We have also developed a high-resolu tion fluorescent reverse-banding technique for mouse chromosomes that allow s simultaneous localization of probes by fluorescence in situ hybridization (FISH) with respect to the cytogenetic landmarks. This approach integrates studies of the entire mouse genome. Moreover, these reagents will simplify gene mapping and analyses of genomic fragments in fetal and adult mouse mo dels. As shown with the MMU16 telomeric marker For the trisomy 16 mouse mod el of Down syndrome, these clones can obviate the need For metaphase analys es. The potential contribution of this resource and associated methods exte nds well beyond mapping and includes clues to understanding mouse chromosom es and their rearrangements in cancers and evolution. Finally it will facil itate the development of an integrated view of the mouse genome by providin g anchor points From the genetic to the cytogenetic and functional maps of the mouse as we attempt to understand mutations, their biological consequen ces, and gene function.