Genetic variability within and between outbred Wistar strains of rats.

The allelic frequencies at 6 isozyme loci (Es-1, Es-2, Es-3, Es-4, Es-Si and Amy-1) were examined in 4 outbred Wistar strains and additionally 2 SD strains as controls. From the allelic frequencies, the averages of the heterozygosities in individual strains and the geometric genetic distances between every pair of all possible strain combinations were calculated. The averages of the heterozygosities in 2 SD strains were both intermediate (around 0.2) and the genetic distance between them was rather short. But among the Wistar strains, the averages of the heterozygosities were highly variable and the genetic relationships among them were very variable in their genetic distances. From these results, it was suggested that the outbred Wistar strains were different each other in their genetic constitutions and that no suggestion was obtained to descriminate genetically the Wistar strains from the SD strains.