A regulatory code for neuron-specific odor receptor expression

Area of Science:

• Genetics
• Neuroscience
• Evolutionary Biology

Background:

• Olfactory receptor neurons (ORNs) in Drosophila must precisely select which odor receptors to express from a large repertoire.
• This process forms a stereotyped map between odor receptors and neurons, but the underlying gene regulation is poorly understood.

Purpose of the Study:

• To identify conserved regulatory elements controlling odor receptor gene expression in Drosophila maxillary palp ORNs.
• To elucidate the regulatory logic governing the selection of specific odor receptors by individual ORNs.

Main Methods:

• Phylogenetic analysis of genome sequences from 12 Drosophila species.
• Systematic identification of evolutionarily conserved, gene-specific regulatory elements.
• Genetic analysis of identified regulatory elements and transcription factors.

Main Results:

• Identified conserved regulatory elements acting as a "zip code" for each odor receptor gene, promoting expression in specific ORN subsets and restricting it to single classes.
• Discovered the transcription factor Scalloped mediates repressive functions in this process.
• Observed remarkable conservation of maxillary palp ORN organization and odor response spectra over millions of years, despite less conserved receptor sequences.

Conclusions:

• The study defines the regulatory logic for odor receptor gene selection in Drosophila maxillary palp ORNs.
• Conserved regulatory elements and transcription factors play crucial roles in establishing the olfactory map.
• The long-term evolutionary stability of olfactory perception highlights the importance of this regulatory system.