Sensory distinction between H-2b and H-2bm1 mutant mice.

Genetic polymorphism in the H-2:Qa:Tla region of chromosome 17 is associated with constitutive variation of bodily odor phenotypes which permit individual olfactory recognition among mice. To determine whether known genes in the H-2:Qa:Tla complex are concerned in the constitution of odor phenotypes, mice were tested for their ability to sense a difference between the B6/By (H-2b) and congeneic B6.C-H-2bm1 strains, which differ genetically by mutation of the H-2K gene. As in previous studies of the sensory discrimination of H-2:Qa:Tla phenotypes, mice were trained by reward in a Y maze to distinguish the odors of urine samples, and the successful distinctions of B6/By from B6.C-H-2bm1 were confirmed by transfer of training, without reward, to coded samples of urine from genetically equivalent urine donor mice which the trained mice had not previously encountered. Cosegregation of odor phenotype with H-2b and H-2bm1 was demonstrated by transfer of training to typed H-2b and H-2bm1 homozygous segregants of F2 generations of appropriate crosses. Although it is not excluded that the differences in odor phenotype which distinguish H-2b and H-2bm1 mice are directly related to the structure of the H-2b and H-2bm1 products, it is equally possible that H-2-related odor phenotypes arise from effects of H-2 genetic variation on metabolic pathways either directly, or indirectly through developmental polymorphism.