RT Journal Article SR Electronic T1 Chemoreceptor Co-Expression in Drosophila Olfactory Neurons JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.11.07.355651 DO 10.1101/2020.11.07.355651 A1 Darya Task A1 Chun-Chieh Lin A1 Alina Vulpe A1 Ali Afify A1 Sydney Ballou A1 Maria Brbić A1 Philipp Schlegel A1 Gregory S. X. E. Jefferis A1 Hongjie Li A1 Karen Menuz A1 Christopher J. Potter YR 2021 UL http://biorxiv.org/content/early/2021/07/27/2020.11.07.355651.abstract AB Drosophila melanogaster olfactory neurons have long been thought to express only one chemosensory receptor gene family. There are two main olfactory receptor gene families in Drosophila, the Odorant Receptors (ORs) and the Ionotropic Receptors (IRs). The dozens of odorant binding receptors in each family require at least one co-receptor gene in order to function: Orco for ORs, and Ir25a, Ir8a, and Ir76b for IRs. Using a new genetic knock-in strategy, we targeted the four co-receptors representing the main chemosensory families in Drosophila (Orco, Ir8a, Ir76b, Ir25a). Co-receptor knock-in expression patterns were verified as accurate representations of endogenous expression. We find extensive overlap in expression among the different co-receptors. As defined by innervation into antennal lobe glomeruli, Ir25a is broadly expressed in 88% of all olfactory sensory neuron classes and is co-expressed in 82% of Orco+ neuron classes, including all neuron classes in the maxillary palp. Orco, Ir8a, and Ir76b expression patterns are also more expansive than previously assumed. Single sensillum recordings from Orco-expressing Ir25a mutant antennal and palpal neurons identify changes in olfactory responses. These results suggest co-expression of chemosensory receptors is common in olfactory neurons. Together, our data present the first comprehensive map of chemosensory co-receptor expression and reveal their unexpected widespread co-expression in the fly olfactory system.Competing Interest StatementThe authors have declared no competing interest.