Three base pair substitutions were introduced into exon 2 of the mouse eIF2α (Eif2s1) resulting in a single amino acid substitution of serine to alanine at codon 51 (S51A) within the phosphorylation site of the protein. A loxP-flanked neo cassette in reverse-orientation to the gene was inserted 200 bp upstream of exon 2. 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 C57BL/6 blastocysts and chimeric males were bred with C57BL/6 females to establish the colony. Mutant mice were bred with ZP3-Cre transgenic mice (on a C57BL/6 genetic background) to remove the neo selection cassette. The donating investigator reported that these eIF2αS51A mice were bred to C57BL/6J mice for at least ten generations (see SNP note below), and the ZP3-Cre transgene was removed. Upon arrival at The Jackson Laboratory Repository, mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least one generation to establish the colony.
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. 2 the 27 markers throughout the genome were segregating between B6J and 129, suggesting an incomplete backcross. Also, 4 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.
