|Budget Amount *help
¥1,200,000 (Direct Cost : ¥1,200,000)
Fiscal Year 1992 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1991 : ¥900,000 (Direct Cost : ¥900,000)
The Shumiya Cataract Rat (SCR), a rat with hereditary cataract was derived from congenic line of SHR-fa rats in 1985. The lens opacity appeared spontaneously in the nuclear and perinuclear portions in adults. Raman optical dissection studies in the opaque lens nucleus in SCR revealed decreased lens protein disulfide bonds and increased sulfhydryl groups. Poorly differentiated epithelial cells at 2 weeks of age, a separated anterior suture and liquid accummlation in the posterior subcapsular region at 8 weeks were observed. These changes developed into mature cataract at 11 weeks. SCR and normal controlrats of NC/1 and NC/2, separated at the F2 and F16 generation, were established for inbred strains by continuous sib mating. The frequency of cataract appearance was 60-70% in the each generation. Littersize of SCR was about two fewer compared NC/1 and a 22.1% embryo loss was observed. Genetic analysis of cataractformation in SCR was studied by breeding experiments with ACI, BUF, NC/1, and NC/2 rats. From these results, we introduce our hypotheses : (1) Two autosomal genes, dominant lethal and recessive, participated in cataract genesis in the SCR rat, (2) One recessive gene is maintained in the NC/1 and NC/2 rat, (3) The same recessive gene was retained with abh-alb rat. These hypotheses are statistically supported and further investigations are in progress.
SCR is a useful cataract model with new genetic backgrounds.