The study by Vosshall, Wong, and Axel identifies and characterizes the complete repertoire of odorant receptor (DOR) genes in Drosophila, which are responsible for encoding odorant receptors. They find that 57 DOR genes are present in the Drosophila genome, with each gene encoding a seven-transmembrane domain protein. Individual sensory neurons are likely to express only a single receptor gene, and these neurons project their axons to one or two spatially invariant glomeruli in the antennal lobe. This organization allows for a two-dimensional map of receptor activation, similar to the mammalian olfactory system. The study also explores the spatial segregation of axons in the antennal lobe and the role of the DOR gene Or83b, which is expressed in all olfactory sensory neurons. The findings suggest that the logic of odor discrimination in Drosophila is similar to that in mammals, reflecting an efficient solution to the complex problem of olfactory perception over 500 million years of evolution.The study by Vosshall, Wong, and Axel identifies and characterizes the complete repertoire of odorant receptor (DOR) genes in Drosophila, which are responsible for encoding odorant receptors. They find that 57 DOR genes are present in the Drosophila genome, with each gene encoding a seven-transmembrane domain protein. Individual sensory neurons are likely to express only a single receptor gene, and these neurons project their axons to one or two spatially invariant glomeruli in the antennal lobe. This organization allows for a two-dimensional map of receptor activation, similar to the mammalian olfactory system. The study also explores the spatial segregation of axons in the antennal lobe and the role of the DOR gene Or83b, which is expressed in all olfactory sensory neurons. The findings suggest that the logic of odor discrimination in Drosophila is similar to that in mammals, reflecting an efficient solution to the complex problem of olfactory perception over 500 million years of evolution.