The Vil-LacZ knock-in/knockout allele (also called Villinβ-gal) was designed by Dr. Deborah L. Gumucio (University of Michigan). A targeting vector was designed to replace exons 1-3 of the villin 1 locus (Vil1) with a cDNA encoding β-galactosidase (lacZ) and a reverse-oriented PGK-neomycin resistance cassette. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-Kitl+)-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts, and chimeric males were bred with C57BL/6J females for germline transmission. The donating investigator reports that the mutant colony was maintained by breeding heterozygous males with C57BL/6NCrl females for more than ten generations (see SNP results below). In 2016, heterozygous males with black coat color were sent to The Jackson Laboratory Repository. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6NJ oocytes (Stock No. 005304).
Of note, it is not known if the Y chromosome has been fixed to the C57BL/6 background during backcrossing.
In 2016, a 32 SNP (single nucleotide polymorphism) panel analysis, with 27 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on a cohort of the first generation rederived living colony at The Jackson Laboratory Repository. 26 of 27 markers throughout the genome suggested a C57BL/6 genetic background - the only exception was the marker in the panel closest to the Vil1 gene (segregating C57BL/6;129S allele-type). In addition, 4 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating in some mice (chromosomes 8 [~15.2 Mbp], 13 [~41.0 Mbp], 15 [~57.6 Mbp] and 19 [~49.9 Mbp]). These data suggest that the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J;C57BL/6N genetic background.
