Chemosensory identity and the Y chromosome.

Genes in the extended major histocompatibility complex (MHC) of the mouse (H-2: Qa:T1a) impart to each mouse an odor that reflects its genetic constitution at this region of chromosome 17. Sensory recognition of these differential odors influences reproductive behavior and evokes neuroendocrine responses critical to the maintenance of pregnancy. To determine whether other parts of the mouse genome contribute to individual odor, and so may similarly exert a selective force on loci other than the MHC, mice differing genetically only in their X and/or Y chromosomes were tested for individuality of scent in the Y-maze system previously employed to investigate MHC-related scent distinctions. It was found that the X and Y chromosomes each confer individuality of scent related to genotype, but differences at the H-2 locus are considerably more salient. Nevertheless, chemosensory cues controlled by differences on the Y chromosome could play a role in individual recognition, mate selection, aggressive interactions, and perhaps other aspects of mouse chemosensory behavior.