Journal Article

Candidate ionotropic taste receptors in theDrosophilalarva

Ghosh, Arpan C., Koh, Tong-Wey, Stewart, Shannon, Carlson, John R.

2015

Overview

We examine inDrosophilaa group of ∼35 ionotropic receptors (IRs), the IR20a clade, about which remarkably little is known. Of 28 genes analyzed,GAL4drivers representing 11 showed expression in the larva. Eight drivers labeled neurons of the pharynx, a taste organ, and three labeled neurons of the body wall that may be chemosensory. Expressionwas not observed in neurons of one taste organ, the terminal organ, although these neurons express many drivers of theGr(Gustatory receptor) family. For most drivers of theIR20aclade, we observed expression in a single pair of cells in the animal, with limited coexpression, and only a fraction of pharyngeal neurons are labeled. The organization ofIR20aclade expression thus appears different from the organization of theGrfamily or theOdor receptor(Or) family in the larva. A remarkable feature of the larval pharynx is that some of its organs are incorporated into the adult pharynx, and several drivers of this clade are expressed in the pharynx of both larvae and adults. Different IR drivers show different developmental dynamics across the larval stages, either increasing or decreasing. Among neurons expressing drivers in the pharynx, two projection patterns can be distinguished in the CNS. Neurons exhibiting these two kinds of projection patterns may activate different circuits, possibly signaling the presence of cues with different valence. Taken together, the simplest interpretation of our results is that theIR20aclade encodes a class of larval taste receptors.

• Publisher: National Academy of Sciences
• Subject: INAUGURAL ARTICLE