In homozygous Prph2Rd2 mice, the receptor layer remains rudimentary, but the other retinal layers show a normal trend of growth during the first 2 weeks after birth. Thereafter the morphological layers containing visual cell structures--the receptor, the outer nuclear, and the outer plexiform layers--begin to reduce. Degeneration is more rapid up to the age of 2-3 months, when the outer nuclear layer is reduced to half of its original thickness; thereafter degeneration progresses more slowly. At 9 months, the peripheral parts of the retina, and at 12 months, the entire retina is completely lacking in visual cells. In the central retina of the mutant, rod and cone cell populations are equally affected up to the age of 6 months, as their relative frequency remains similar to the normal. Cell loss is more pronounced in the peripheral retina. The pigment epithelium is also affected at this late stage and appears depleted and patchy. In the mutant, increased frequency and stainability of the macrophages are discernible in the inner retina at 11 days. The macrophages migrate outwards and are observed in the outer nuclear layer and in the optic ventricle during the period of degeneration. (Sanyal S. et al. 1980. J Comp Neurol 194 (1) 193-207)
This recessive autosomal mutation was found in the 020/A mouse strain and initially named rds (retinal degeneration slow). Homozygous embryos were cryopreserved in 1994.
|Allele Name||retinal degeneration 2|
|Allele Synonym(s)||Prph2Rds; Rd-2; Rds; rds-; RdsRd2; retinal degeneration slow|
|Gene Symbol and Name||Prph2, peripherin 2|
|Strain of Origin||O20/A|
|Molecular Note||The mutation is an insertion of approximately 10 kb in the gene after nucleotide 899 (numbering of the encoded mRNA), disrupting the protein coding sequence in exon 2. The inserted DNA was similar to both the TSE of mice, repeated elements found in the H2 complex, and to the mouse early transposon (ETn). Northern blot analysis demonstrated that an aberrant 12 kb transcript was produced from this allele, although at reduced levels compared to wild-type. This allele is predicted to encode a truncated protein with its carboxy terminal 116 amino acids replaced by 35 amino acids from sequences in the insertion. Mutant mice doubly homozygous for two retinal degeneration mutations (Pde6brd1 and RdsRd2) shows an intermediate level of mRNAs for the beta subunit of cGMP-PDE and for several other phototransduction related proteins, suggesting an interaction between Pde6brd1 and RdsRd2.|