This strain was generated at the Mayo Clinic, Jacksonville, FL. A targeting vector containing a PGK-neo cassette was used to insert loxP sites flanking exon 41 and the selection cassette. The construct was electroporated into C57BL/6 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. The resulting chimeric animals were crossed to mice expressing Cre recombinase (on the C57BL/6 background) to remove exon 41 and the PGK-neo cassette. Heterozygotes were crossed to generate homozygotes. Upon arrival at The Jackson Laboratory, the mice were crossed with C57BL/6J to establish the colony (see SNP note below).
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 the rederived living colony at The Jackson Laboratory Repository. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, 2 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.
