The mahogany mutation arose on a mixed C3H;Swiss background at the Jackson Laboratory, and was initially maintained by sibling inbreeding. The brachymorphic mutation arose spontaneously in the mahogany line when it was at generation F12 in 1964. Brachymorphic was outcrossed once to C57BL/6J and then the line was sibling mated. At generation F15, in 1969, a homozygous brachymorphic mouse was outcrossed to a mouse homozygous for pale ear and ruby on a congenic C57BL/6J background. The F1 offspring of this cross were mated and selected F2 hybrids were then mated to produce the triple homozygote with all three loci on the same chromosome. The triple homozygote in which all three loci were closely linked was crossed once to C57BL/6J and then the stock was sibling intercrossed by forced heterozygosis to F7 before it was crossed to the B6C3Fe-a/a F1 hybrid beginning in 1972. Backcrossing to the hybrid was continued using the cross intercross method and a subline was selected that had pale ear and ruby bred out. This strain, carrying only brachymorphic, was maintained by backcross-intercross breeding to B6C3Fe-a/a F1 and embryos were generated for cryopreservation by breeding homozygous males at generation N23F1 to B6C3Fe-a/a F1 females.
|Gene Symbol and Name||a, nonagouti|
|Strain of Origin||old mutant of the mouse fancy|
|General Note||Insertion of the LV30 retrotransposon without the beta4 retrovirus sequence does not cause the nonagouti phenotype. J:278039|
|Molecular Note||Characterization of this allele shows an insertion of DNA comprised of a 5.5kb virus-like element, VL30, into the first intron of the agouti gene. The VL30 element itself contains an additional 5.5 kb sequence, flanked by 526 bp of direct repeats (beta4 retroviral sequence). The host integration site is the same as for at-2Gso and Aw-38J and includes a duplication of four nucleotides of host DNA and a deletion of 2 bp from the end of each repeat. Northern analysis of mRNA from skin of homozygotes shows a smaller agouti message and levels 8 fold lower than found in wild-type.|
|Gene Symbol and Name||Papss2, 3'-phosphoadenosine 5'-phosphosulfate synthase 2|
|Strain of Origin||LDJ/Le-Grem1ld-J + a/ + Atrnmg a|
|Molecular Note||A point mutation resulting in a glycine to arginine substitution at the highly conserved codon 79 is predicted to be responsible for the mutant phenotype seen in the brachymorphic mouse.|
Extra shavings should be added until the wean is about 5-6 weeks old so that they can reach the food and water more easily.
When using the brachymorphic mouse strain in a publication, please cite the originating article(s) and include JAX stock #000205 in your Materials and Methods section.