Related Experiment Videos
Odor types determined by the major histocompatibility complex in germfree mice
K Yamazaki1, G K Beauchamp, Y Imai
1Monell Chemical Senses Center, Philadelphia, PA 19104.
Abstract:
The major histocompatibility complex (MHC) is the prime but not exclusive determinant of genetically specific constitutive body odors, termed odor types, represented strongly in urine of the mouse. Perception of MHC-determined odor types influences reproductive behavior in the contexts of mate choice and maintenance of early pregnancy, tending to favor the propagation of one MHC type over another. How MHC genotype determines MHC odor type is unknown. One possible explanation is that differential odorants are generated by populations of commensal microorganisms whose composition is somehow geared to MHC diversity. This hypothesis was tested in the Y-maze system in which mice are trained to distinguish the urinary odors of MHC-congenic mice. First, it was shown that mice could readily be trained to distinguish the urines of germfree MHC-congenic mice. Second, it was shown that mice trained to distinguish the urines of conventionally maintained MHC-congenic mice could as readily distinguish the urines of germfree MHC-congenic mice. These results imply that MHC-determined odor types do not depend on odorants generated by microorganisms.
Insights
Mice can distinguish genetically determined body odors (odor types) regardless of microorganisms. This suggests that the major histocompatibility complex (MHC) directly influences odor type, not microbial activity.
Area of Science:
- Immunogenetics
- Olfactory Perception
- Animal Behavior
Background:
- The Major Histocompatibility Complex (MHC) dictates genetically specific body odors, influencing mate choice and reproduction.
- The mechanism by which MHC genotype determines these unique odor types remains unclear.
- A leading hypothesis proposed microbial involvement in generating MHC-dependent odorants.
Purpose of the Study:
- To investigate whether microorganisms are essential for generating MHC-determined urinary odor types in mice.
- To test the hypothesis that microbial composition, influenced by MHC diversity, creates distinct odor profiles.
Main Methods:
- Utilizing a Y-maze system to train mice to differentiate urinary odors.
- Comparing the olfactory discrimination abilities of mice presented with urines from germfree and conventionally housed MHC-congenic mice.
- Assessing if mice can distinguish odors from MHC-congenic mice raised without any microbial exposure.
Main Results:
- Mice demonstrated a clear ability to distinguish the urinary odors of germfree MHC-congenic mice.
- Mice previously trained on conventionally housed mice could equally distinguish odors from germfree mice.
- These findings indicate that olfactory perception of MHC type is independent of microbial generation of odorants.
Conclusions:
- MHC-determined odor types are not reliant on odorants produced by commensal microorganisms.
- The genetic makeup of the host, specifically the MHC, directly influences the production of these specific body odors.
- This research clarifies a fundamental aspect of olfactory communication and its genetic underpinnings.