Mice that are homozygous for the targeted mutation are viable and normal in size. When heterozygous mice are bred together, homozygous animals occur at a greatly reduced frequency (~6%). No gene product (protein) is detected in retinal tissue from homozygotes by Western blot analysis. Onset of progressive retinal degeneration occurs at 2 months of age beginning with a thinning of the outer nuclear layer of retinal cells. Rod outer segments in 2 month old mice display disorganized arrangement, irregular gaps and amorphous aggregates. At 4 months of age organization of rod outer segments improves. TUNEL assay of mutant retinal tissue show photoreceptor degeneration is due to apoptotic cell death. Ultra structural organization of rod outer segment disks is disorganized, often with patches of enlarged disks. Electroretinogram a-wave analysis of photoreceptor function reveals a diminished maximal photoreceptor response (50% lower than wildtype). This mutant mouse strain may be useful in studies of autosomal recessive retinitis pigmentosa.
A targeting vector containing neomycin resistance and herpes simplex virus thymidine kinase genes was used to disrupt exon 1 and approximately 500bp of upstream sequence encoding the transcription initiation site. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting male chimeric animals were crossed to CD1 females, and then backcrossed to mixed 129 and CD1 for at least 5 generations. Upon arrival at The Jackson Laboratory, mutant mice were bred to 129S1/SvImJ (Stock No. 002448) inbred mice for at least one generation to establish the colony.
|Allele Name||targeted mutation 1, Roderick R McInnes|
|Allele Type||Targeted (Null/Knockout)|
|Gene Symbol and Name||Rom1, rod outer segment membrane protein 1|
|Strain of Origin||(129X1/SvJ x 129S1/Sv)F1-Kitl+|
|Molecular Note||A neomycin selection cassette replaced exon 1 and a 5' portion of exon 2. Western blot analysis of crude retinal extracts showed an absence of encoded protein in homozygous mutant mice.|
When maintaining a live colony, heterozygous mice may be bred together or to wildtype siblings. It has been the experience of The Jackson Laboratory that homozygous animals occur at a greatly reduced frequency (~6%) from intercrosses of heterozygous animals.
When using the Rom1- mouse strain in a publication, please cite the originating article(s) and include JAX stock #004510 in your Materials and Methods section.