# Different expression domains for two closely related amphibian TAARs generate a bimodal distribution similar to neuronal responses to amine odors

## TL;DR

This study shows how two similar amphibian olfactory receptors have different expression patterns, leading to a bimodal response to amine odors.

## Contribution

The paper reveals a bimodal distribution in amine odor responses linked to distinct expression domains of two TAARs in amphibians.

## Key findings

- TAAR4b and TAAR4a show distinct spatial expression patterns in two dimensions.
- The combined expression of TAAR4a and TAAR4b creates a bimodal distribution similar to neuronal amine responses.
- Quantitative analysis suggests other receptors may also contribute to amine odor perception in amphibians.

## Abstract

Olfactory perception is mediated by a multitude of olfactory receptors, whose expression in the sensory surface, the olfactory epithelium, is spatially regulated. A common theme is the segregation of different olfactory receptors in different expression domains, which in turn leads to corresponding segregation in the neuronal responses to different odor groups. The amphibian olfactory receptor gene family of trace amine associated receptors, in short TAARs, is exceedingly small and allows a comprehensive analysis of spatial expression patterns, as well as a comparison with neuronal responses to the expected ligands for this receptor family, amines. Here we report that TAAR4b exhibits a spatial expression pattern characteristically different in two dimensions from that of TAAR4a, its close homolog. Together, these two genes result in a bimodal distribution resembling that of amine responses as visualized by calcium imaging. A stringent quantitative analysis suggests the involvement of additional olfactory receptors in amphibian responses to amine odors.