On this C57BL/6J congenic background this spontaneous mutation in Gnat1 causes homozygotes to have abnormal dark-adapted electroretinogram as early as 3 weeks of age, the earliest timepoint assessed. While rod and cone transducins can substitute for each other to some degree, these homozygotes have normal cone function but rod dysfunction. No abnormalities are detected in retinal structure by 6 months of age.
Dr. Bo Chang found that both the Gnat2cpfl3 and Gnat1irdr alleles were in STOCK Tg(tetO-HIST1H2BJ/GFP)47Efu/J, which derived from CD1. Non-transgenic mice from this line that were carrying the Gnat2cpfl3 and Gnat1irdr alleles were sibling intercrossed for several generations and then the Gnat1indr mutation was bred away from Gnat2cpfl3 by backcrossing to C57BL/6J to generate this congenic strain. This strain was then sibling inbred to homozygosity for Gnat1irdr.
|Allele Name||ICR derived retinal dysfunction rod|
|Allele Synonym(s)||rd17; retinal degeneration 17|
|Gene Symbol and Name||Gnat1, guanine nucleotide binding protein, alpha transducing 1|
|Strain of Origin||ICR|
|General Note||Mice homozygous for this mutation have impaired rod electrophysiology but normal retinal morphology.|
|Molecular Note||The molecular mutation is a 57 bp deletion in intron 4 of the gene, which alters the splice donor site. This results in retention of the remaining 48 bp of the intron in the expressed mRNA. The insertion converts a cytosine to a guanine at nucleotide position 450 of the ORF and changes codon 150 (TAC) to a stop codon (TAG) (amino acid change: Tyr150Ter). Western blot analysis showed that no detectable protein is expressed from this allele. Because this mutation was found in ICR and CD1 it is carried in many strains, including IRD1 and IRD2.|