Tabby Stocks Available from The Jackson Laboratory
JAX® NOTES Issue 440a, January 1990
Tabby as a marker gene
The tabby (Ta) mutation is used as a marker gene in strains carrying the X-linked mutations jimpy (jp) and testicular feminization (Tfm) and in the X/O chromosomal stock. Whether the Ta locus is on the same X chromosome as the mutation of interest (in coupling) or on the other X as in a balanced stock (in repulsion) determines what genotype of mice one needs to obtain when ordering the mutant or breeding pairs. The following is a description of the breeding system for each of these strains and the genotypes of the mutants available.
Jimpy (jp)
In the B6CBACa-Aw-J/A-Ta jp jimpy mutant stock Ta and jp are carried on the same X chromosome. The stock is maintained by mating Ta jp /++ females x B6CBACa-Aw-J/A F1 males (C57BL/6J-Aw-J x CBA/Ca-A (++/Y). The Ta?/++ female progeny should carry jp but must be tested since the probability of recombination between these two loci is about 15%. Mutants are available as hemizygous tabby jimpy (Ta jp/Y) males, generally with ++/Y controls. Jimpy males are shipped at 10-14 days of age with foster moms. Only untested breeders (Ta?/++ females and B6CBACaF1 males) are available.
Testicular feminization (Tfm)
The testicular feminization stock, C57BL/6J-Aw-J /Ta +/+ Tfm, is a balanced stock, meaning the Ta gene is on one X chromosome balanced against the Tfm gene on the other. It is maintained by mating Ta +/+? females with sibling Ta +/Y males from matings that have produced both Ta and Tfm progeny. From this cross offspring that appear to be wild type (+/?) females are the Tfm/Y males. The controls for the Tfm/Y males are Ta/Y. The two loci are closely linked (approximately 2cM) and over 90% of the matings are expected to produce Tfm/Y males. Only untested breeders (Ta +/+? females and Ta +/Y males) are available for distribution.
X/O Stock
The B6CBACa-Aw-J/A-TaO is an X/O stock. It is maintained by mating in alternate generations: first, XTa /O females x a B6CBA-Aw-J/A F1 (X+/Y) male and, second, X+/O females to XTa/Y siblings. X/O females are detected from the first cross because they inherit a normal non-tabby allele on the X chromosome from the male and have a normal coat color. Ta/O females from the second cross are detected because they resemble Ta/Y males.
Two alleles of tabby
The tabby mutation is also available by itself as two different alleles on the C57BL/6J genetic background. These strains are C57BL/6J-Aw-J/Ta6J and B6.C-Aw-J-TaBy/+. The Ta6J allele arose in strain C57BL/6J, was backcrossed 2 generations to the agouti C57BL/6J strain indicated above and is now maintained by sibling matings of Ta6J/+ females X +/Y males. The TaBy allele arose in BALB/cBy and was backcrossed 18 generations to C57BL/6By and then 9 generations to C57BL/6 before embryos were preserved. This strain is currently only available from the Frozen Embryo Repository.
