Towards high resolution maps of the mouse and human genomes - a facility for ordering markers to 0.1 cm resolution

982 progeny produced by a mouse Interspecific backcross between C57BL/6 and Mus spretus have been scored for at least 3 markers on each chromosome, completing an anchor map of 78 loci across the mouse genome. The anchor mapping identifies all the available recomblnants in each interanchor Interval allowing access to panels of mice that can be used for the high resolution mapping of any chromosome region. The large number of progeny recovered and scored from the Interspecific backcross allows us to resolve genetically markers that lie on average 200 kb apart on mouse chromosomes and within the cloning capacity of currently available YAC libraries. EUCIB provides the first genetic mapping resource specifically designed for the high resolution mapping of all regions of the mouse genome and will underpin the global physical mapping of the mouse genome. In addition, with the use of conserved sequences the facility is applicable to the high resolution comparative mapping of the mouse and human genomes. A new database has been implemented to support the computation of high resolution and ordered genetic maps. © 1994 Oxford University Press

Genomic imprinting of Mash2, a mouse gene required for trophoblast development

The mouse gene Mash2 encodes a transcription factor required for development of trophoblast progenitors. Mash2- homozygous mutant embryos die at 10 days post−coitum from placental failure. Here we show that Mash2 is genomically imprinted. First, Mash2+/- embryos inheriting a wild−type allele from their father die at the same stage as -/- embryos, with a similar placental phenotype. Second, the Mash2 paternal allele is initially expressed by groups of trophoblast cells at 6.5 and 7.5 days post−coitum, but appears almost completely repressed by 8.5 days post−coitum. Finally, we have genetically and physically mapped Mash2 to the distal region of chromosome 7, within a cluster of imprinted genes, including insulin−2, insulin−like growth factor−2 and H19