A targeting vector was designed to insert a neomycin resistance cassette and delete exon 2 of the beta-arrestin 2 gene Arrb2) on chromosome 11. This strain was created in a 129-derived embryonic stem cell line. Mutant mice were backcrossed to C57BL/6 for more than ten generations by the donating laboratory (see SNP results below) prior to sending males to The Jackson Laboratory Repository in 2012. Upon arrival, males were used to cryopreserve sperm. To establish the living mouse colony, an aliquot of the frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).
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 living colony at The Jackson Laboratory Repository. This revealed 2 of 27 markers, one each on chromosomes 1 and 2, that were not fixed for C57BL/6 allele-type (e.g.: still segregating for 129 allele-type markers). In addition, 1 marker on chromosome 17 (~34 Mbp) was found to be segregating for a marker of unknown genetic contribution. These data suggest the mice may have been backcrossed to C57BL/6 for fewer generations than reported prior to arrival at The Jackson Laboratory.
