At approximately two months of age, flying squirrel homozygotes stiffen throughout their trunk and limbs, particularly on the ventral side of the body, and when picked up take on a rigid spread out posture. As a result they walk with a slight stagger. Homozygotes are not fertile but do live to adulthood.
The flying squirrel mutation arose spontaneously in the KK.Cg-Ay background and in 1998 in vitro fertilization was performed using a homozygous fsq male and nonagouti (a/a) females from the KK.Cg-Ay/J strain. The resultant offspring were intercrossed to generate a nonagouti strain, which was maintained by breeding hosts of fsq homozygous ovarian transplants with +/? sibling males and then intercrossing the heterozygous offspring. This strain proved very difficult to cryopreserve and in 2011 an outcross to C57BL/6J was done and the resulting offspring intercrossed then this STOCK line was again maintained by breeding hosts of fsq homozygous ovarian transplants with +/? sibling males and then intercrossing the heterozygous offspring. Cryopreservation of homozygous sperm and cryorecovery from this bankstock were successful.
When using the STOCK fsq/GrsrJ mouse strain in a publication, please cite the originating article(s) and include JAX stock #017007 in your Materials and Methods section.