A 2-Mb YAC/BAC-based physical map of the ovum mutant (Om) locus region on mouse chromosome 11

The embryonic lethal phenotype observed when DDK females are crossed with males from other strains results from a deleterious interaction between the egg cytoplasm and the paternal pronucleus soon after fertilization. We have previously mapped the Om locus responsible for this phenotype, called the DDK syndrome, to an approximately 2-cM region of chromosome 11. Here, we report the generation of a physical map of 28 yeast and bacterial artificial chromosome clones encompassing the entire genetic interval containing the Om locus. This contig, spanning approximately 2 Mb, was used to map precisely genes and genetic markers of the region. We determined the maximum physical interval for Om to be 1400 kb. In addition, 11 members of the Scya gene family were found to be organized into two clusters at the borders of the Om region. Two other genes (Rad51l3 and Schlafen 2) and one EST (D11Wsu78e) were also mapped in the Om region. This integrated map provides support for the identification of additional candidate genes for the DDK syndrome.