ACHEMS 2019
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SPLTRAK Abstract Submission
Targeted transcriptomics of olfactory receptors for high-throughput mapping of olfactory bulb glomeruli
Kevin Zhu1, Justin Silverman1, Shawn Burton2, Matt Wachowiak2, Hiroaki Matsunami1
1Duke University, Durham, NC, United States
2University of Utah, Salt Lake City, UT, United States

The formation of position-stereotyped, receptor-specific glomeruli in the olfactory bulb (OB) presents a complex wiring problem due to the expansive olfactory receptor (OR) repertoire and expression of a single OR in olfactory sensory neurons (OSNs) scattered in the nasal epithelium. Identifying the glomeruli corresponding to a specific OR and overall organization of OR projections is critical to understanding how receptor signals are translated into specific spatio-temporal responses in the OB. Since 1994, efforts have identified mouse OB glomeruli for ~3% of the 1100 ORs. We aim to generate a comprehensive map of mammalian OR glomeruli via a novel high-throughput approach that determines the OR identity of a glomerulus by sequencing low-abundance OR transcripts in the axon termini of OSNs. We first identified the ORs present in the set of dorsal glomeruli viewed in functional imaging studies through dissection, cDNA synthesis, and enrichment of OR and TAAR transcripts using target capture probes. Differential expression analysis of this sample and the remainder of the OB found 86 ORs and 11 TAARs enriched, with 94% of these ORs expressed in the dorsal olfactory epithelium and no TAARs enriched in the remainder. Spatial information for 909 ORs was attained by targeted sequencing of 100µm serial sections from individual OBs along the coronal, sagittal, and horizontal planes. We found reproducibly unique sets of OR transcripts enriched in each section, suggesting OR identities of glomeruli within each section. A Bayesian reconstruction method will help determine the 3D position of each OR’s glomeruli. Establishing an OR-to-OB map will provide a framework for integrating peripheral ligand-OR deorphanization assays with OB odor representations, a key resource for cracking the olfactory code.