Cheverud Lab Page
Dr. James M. Cheverud
The Jim Cheverud Lab congratulates Elizabeth Norgard, Ph.D for the successful defense of her doctoral dissertation.
New Recombinant Inbred Lines
We began the construction of new Lg/J x Sm/J inbred lines in April 2007 using 63 of the randomly bred families from the F34 generation of the Advanced Intercross Line (AIL). Initially there were 63 genetically distinct strains, and for 33 of these strains, two sets of siblings were separated in the P0 generation to act as additional strains, albeit genetically similar to their AIL sibling strains. Our mating experience has demonstrated that bad parenting behavior is associated at least partially with the Agouti locus on chromosome 2. Since coat color cannot be used to determine allele state in the Lg/J and Sm/J strains, we must genotype the mice to determine their status. All animals were genotyped in the F1 for three microsatellite loci (D2Mit22, D2Mit286, D2Mit409) surrounding the Agouti locus, and we selected for animals with large alleles on a minimum of two, but preferably all three of the loci to breed in the F1 generation.
As of July, 2008 almost 6,000 mice have been born for this experiment and the majority of strains are in the F5 or F6 generations. We have lost 7 strains completely (11.1% of the original genetically distinct strains), as well as 8 of the sib strains (8.1% of all strains), so that their genetically similar sib strain remains alive. We are maintaining 3 or 4 breeding pairs per strain and generation, and all breeding animals that contribute pups used as parents in the next generation are given a standard necropsy at death. Many of the strains are now fixed for the loci surrounding the Agouti locus and no longer require genotyping each generation. Forty-eight of the strains required genotyping during the F2 generation; this dropped to 34 in the F3 generation, 20 in the F4, and 6 in the F5. In the near future, we will check the genotypes of each strain to ensure that these loci remain fixed.