• Spontaneous mutants

    With the constant breeding that goes on in the colony, we occasionally discover interesting spontaneous mutations that can be followed up to fix, map and/or characterize the new trait.

  • During the construction of one of our congenic lines on an A/J background, we recently identified a new spontaneous mutation that leads to right-sided heart failure, with a majority of the mice that are homozygous for the recessive mutation dying between 9 and 18 weeks of age. To more easily maintain and study this line, we are currently trying to identify an early diagnostic marker/measure that predicts outcome and determine whether the mutation is within or outside of the congenic region. Gene identification and specific mutation will be pursued.

    Using a phenotype-driven breeding approach, we are close to capturing a “high bleeding time” trait in homozygosity for several lines of inbred mice. Once fixed, we will set out to map the loci and identify the critical gene(s).

    We identified a single mouse with a greyish-tan coat color and ruby red eyes in one of our C57BL/6J-derived congenic lines for the ozone project. The substituted A/J-derived congenic region was eliminated and the color coat regenerated, demonstrating that the mutation was not in the congenic interval. This color coat mutation is now on a pure C57BL/6J background. We are now generating an F2 population with A/J mice to map the trait and determine whether this is worthy of further analysis. The F2 population has at least 6 different coat colors, rather than the expected 3 coat colors from a typical cross of A/J and C57BL/6J strains (i.e., black, white and brown).