Single-cell transcriptomics reveals receptor transformations during olfactory neurogenesis

The sense of smell allows chemicals to be perceived as diverse scents. We used single neuron RNA-Sequencing (RNA-Seq) to explore developmental mechanisms that shape this ability as nasal olfactory neurons mature in mice. Most mature neurons expressed only one of the roughly 1000 odorant receptor genes (Olfrs) available, and that at high levels. However, many immature neurons expressed low levels of multiple Olfrs. Coexpressed Olfrs localized to overlapping zones of the nasal epithelium, suggesting regional biases, but not to single genomic loci. A single immature neuron could express Olfrs from up to seven different chromosomes. The mature state in which expression of Olfr genes is restricted to one per neuron emerges over a developmental progression that appears independent of neuronal activity requiring sensory transduction molecules