Col1a1^tm1Bst

Gene targeting by double replacement introduced a 1283 bp deletion within intron 1 and a silent single base mutation in exon 7. RT-PCR studies of skin from heterozygous mice detected no change in expression from this allele compared to the wild-type allele. However, in lungs of young heterozygous mice this allele was expressed at about 75% of the level of the wild-type allele; and in lungs of adult mice, expression was reduced to about 50%. RNase protection assays detected a 2-3 fold decrease in mRNA in lungs of homozygous mutant mice. Expression studies determined that the mutated intron was spliced correctly. (J:47669)