Taupe is a recessive spontaneous mutation that causes a lightening of the coat color such that a/a tp/tp mice are slate grey. The coat color is similar to that of the ruby (Hps5ru) mutation but the eye color is not affected and the belly fur is lighter in color with yellow at the margins. The homozygous females do not have normal nipple development, although the mammary ducts and alveoli develop normally. These females also have difficulty with pregnancy and birth. They can not rear their pups even if the pups are born alive so this strain is maintained by breeding heterozygous females to homozygous males. (Fielder, 1952; Fielder, 1950.)
The taupe (tp) mutation arose spontaneously in C57BL/10J at F46 at the Jackson Laboratory in 1948. One cross was made to C57BL/6J and then it was brother x sister bred always mating tp/tp males to tp/+ females. It was cryopreserved in 1982 by mating tp/tp males at F59 to C57BL/6J 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.|