Clinical, Histological and Biochemical Observations in Spontaneous Senile Cataract in Mastomys Species

Clinical, histological and biochemical examination of spontaneous lens opacity was carried out in Mastomys  coucha species. The incidence of the spontaneous lens opacity was noticed in adult animals, in the  age range of 48-72 weeks, up to a maximum prevalence of 2.6% and 13.71% in male and female animals  respectively. The affected animals exhibited mild lens opacity initially, which progressed with age, and later  on became dense and looked like a mature cataract. The opacity was irreversible and showed no signs of  disappearing in the affected animals. Both male and female were affected but, as noted above, the incidence  of the abnormality was higher in the females. The mode of inheritance was not investigated. The ophthalmoscopic  examination of the affected animals revealed total lenticular opacity characterized by a shallow  anterior chamber and bulging of the lens towards the anterior side due to the swelling of the lens. The serum  glucose values in affected animals were within the normal range. The histological examination of opaque  lenses revealed total alteration in the micro architecture of the lens cells. The SDS-PAGE analysis of lens  crystallins, revealed distribution of major lens crystallins within range of 20-30 kDa molecular weights.  The immunoblotting of SDS-PAGE separated proteins with anti-crystallin , ß and antibodies indicated  expression of major lens crystallins in affected animals. We have concluded that this is a case of spontaneous  senile cataract, reported for the first time in Mastomys species.

Dense cataract and microphthalmia (dcm) in BALB/c mice is caused by mutations in the GJA8 locus

A spontaneous mutation in BALB/c mice that causes congenital dense cataract and microphthalmia (dcm) was reported previously. This abnormality was found to be inheritable and the mode of inheritance indicated that this phenotype is due to mutation of an autosomal recessive gene. We performed genetic screen to identify the underlying mutations through linkage analysis with the dcm progenies of F1 intercross. We identified the region of mutation on chromosome 3 and further mapping and sequence analysis identified the mutation in the GJA8 gene that encodes for connexin 50. The mutation represents a single nucleotide change at position 64 (G to C) that results in a change in the amino acid glycine to arginine at position 22 (G22R) and is identical to the mutation previously characterized as lop10. However, the phenotype of these mice differ from that of lop10 mice and since it is one of the very few genetic models with recessive pattern of inheritance, we propose that dcm mice can serve as a useful model for studying the dynamics and interaction of the gap junction formation in mouse eye development