Linkage analysis of the mutation locus in the eye lens obsolescence (Elo) mouse

To map precisely the mutation locus of eye lens obsolescence (Elo) on mouse chromosome 1, subsequent linkage analysis was achieved using backcross mating between 129/SvSl-Elo (Elo/+) and 129/SvSl (+/+). Mouse genomic DNAs from 17 strains including the Elo mutant mouse were first digested with several restriction enzymes and analyzed by hybridization using gamma 2- and gamma 4-crystallin cDNAs as probes. Restriction endonuclease DraI showed distinct RFLP patterns in both cases. When gamma 2-crystallin cDNA was used as the probe, two strong bands were observed at 4.0 and 2.4 kb in the majority of strains, but the former fragment shifted to the 3.4-kb position in 129/SvSl-Elo (Elo/Elo) and CFO. The polymorphism between 4.0- and 3.4-kb fragments corresponded to the gamma 1-crystallin locus (Cryg-1), and that of the 2.4-kb one, to the gamma 2-crystallin locus (Cryg-2). Mouse DNAs were also analyzed by hybridization using gamma 4-crystallin cDNA (Cryg-4). In this case, 3.4- and 3.0-kb fragments were observed in Elo and wild-type mice, respectively. The backcross offsprings were analyzed with respect to Elo, Idh-1, Cryg-1, and Cryg-4 loci. Among 223 mice analyzed, recombination between Elo and Idh-1 loci was observed in three offsprings; and that between Cryg-1 or Cryg-4 and Idh-1 loci, in one offspring. No recombination occurred between Cryg-1 and Cryg-4 alleles.