RT Journal Article SR Electronic T1 The Ionotropic Receptors IR21a and IR25a mediate cool sensing in Drosophila JF bioRxiv FD Cold Spring Harbor Laboratory SP 032540 DO 10.1101/032540 A1 Lina Ni A1 Mason Klein A1 Kathryn Svec A1 Gonzalo Budelli A1 Elaine C. Chang A1 Richard Benton A1 Aravinthan D. T. Samuel A1 Paul A. Garrity YR 2015 UL http://biorxiv.org/content/early/2015/11/22/032540.abstract AB Animals rely on highly sensitive thermoreceptors to seek out optimal temperatures, but the molecular mechanisms of thermosensing are not well understood. The Dorsal Organ Cool Cells (DOCCs) of the Drosophila larva are a set of exceptionally thermosensitive neurons critical for larval cool avoidance. Here we show that DOCC cool-sensing is mediated by Ionotropic Receptors (IRs), a family of sensory receptors widely studied in invertebrate chemical sensing. We find that two IRs, IR21a and IR25a, are required to mediate DOCC responses to cooling and are required for cool avoidance behavior. Furthermore, we find that ectopic expression of IR21a can confer cool-responsiveness in an Ir25a-dependent manner, suggesting an instructive role for IR21a in thermosensing. Together, these data show that IR family receptors can function together to mediate thermosensation of exquisite sensitivity.