Topographic patterns of odorant receptor expression in mammals: a comparative study

Area of Science:

• Olfactory Neuroscience
• Comparative Anatomy
• Molecular Biology

Background:

• The olfactory epithelium contains diverse odorant receptor (OR) subtypes crucial for scent detection.
• Understanding the evolutionary conservation and divergence of OR expression across species is key to olfactory research.

Purpose of the Study:

• To investigate the cross-species distribution and localization of various odorant receptor subtypes within the mammalian olfactory epithelium.
• To identify species-specific OR expression patterns and conserved olfactory zonal organization.

Main Methods:

• Comparative in situ hybridization using molecular probes for different OR subtypes.
• Analysis of olfactory epithelium tissue sections from multiple mammalian species, including rodents and rabbits.
• Mapping the precise location of OR-expressing neurons within the nasal cavities and olfactory epithelium.

Main Results:

• OR37-reactive neurons were exclusively identified in rodent species, exhibiting a consistent clustering pattern within the nasal cavities.
• An OR37-related receptor subtype was not detectable in rabbits.
• The majority of other tested OR subtypes demonstrated conserved zonal distribution across species within the olfactory epithelium.
• A few OR subtypes showed variations in zonal expression, such as medial zone expression in rats versus dorsal zone expression in guinea pigs.

Conclusions:

• Odorant receptor expression patterns exhibit both conserved and divergent features across mammalian species.
• The olfactory receptor OR37 appears to be a rodent-specific marker.
• Olfactory epithelium organization, while largely conserved, shows some species-specific adaptations in OR subtype localization.