A team led by Julie Korenberg (Cedars-Sinai Medical Center, Los Angeles) has produced a family ofDNA probes that "light up" mouse chromosome sites under fluorescence microscopy. The markers, spaced at an average 19 million bases throughout the 3billion bases of the mouse genome, aid researchers who are hunting for mouse counterparts of human genes. The work is described in the May 1999 cover article of Genome Research.

The mouse is a favorite research model for understanding human biology, and researchers are finding more and more corresponding genes on human and mouse chromosomes. Unlike human chromosomes, however, mouse chromosomes have few distinguishing features that help cytogeneticists hunt for particular disease genes. The new markers thus far have led researchers to the mouse counterpart of the human Down's syndrome region.

The DNA resource consists of 157 BAC clones, each an identifier of specific bands or band borders, with 42 linked to genetic markers from the centromeric and telomeric ends of the Whitehead-MIT recombinational maps. Inclusion of BAC clones containing markers from the ends of genetic maps is expected to facilitate development of an integrated view of mouse cytogenetic, genetic, and physical maps.