Smelling the Roses

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Science  07 Jul 2000:
Vol. 289, Issue 5476, pp. 13-15
DOI: 10.1126/science.289.5476.13e

With almost 1000 odorant receptor genes, most mammals are able to identify a huge array of odorants. Each of the several million olfactory neurons of the mammalian nasal epithelium expresses just one type of odorant receptor (and from only one of the gene's two alleles), and each receptor is expressed in only one of four zones of the nasal epithelium. But how does each olfactory neuron know which single receptor allele to select?

Serizawa et al. have engineered mice to express an odorant receptor that carries a green dye if encoded by the endogenous gene (representing one allele) and a red dye if encoded by a transgene that has the same regulatory and coding sequences (representing the other allele). Both the gene and the transgene were found only within zone 4 of the nasal epithelium and were rarely co-expressed in the same olfactory neuron. The authors propose that an olfactory neuron may select a single odorant receptor gene in the same way as an immune cell selects a single antigen receptor gene: through DNA recombination, which brings the gene's promoter and enhancer regions into close proximity. — OMS

Nature Neurosci. 3, 687 (2000).

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