Speaker
Description
In the Drosophila antenna, olfactory sensilla are the fundamental functional unit of odor detection and processing. These sensilla house not only the well-studied Olfactory Receptor Neurons (ORNs), but also three distinct support cells: the thecogen, trichogen, and tormogen cells. Our understanding of the role of support cells in olfactory signaling has been limited by the lack of markers to distinguish these cells in adult flies. Genetic markers for these cell types have been identified for developmental studies, but their specificity and expression in the adult antenna remains poorly defined. Here, we systematically identified and validated tools to label the three support cells types as well as the epithelial cells found between sensilla. First, we confirmed previous suggestions that ASE5-GAL4 specifically and broadly labels tormogen cells, which express Su(H). In contrast, expression of nompA-GAL4, previously used as a thecogen cell marker, is strongly biased toward coeloconic sensilla and does not capture all thecogen cells. As an alternative, we identified prospero as a candidate thecogen marker using the Fly Cell Atlas. We found that an anti-prospero antibody widely labels thecogen cells, which are ASE5-negative. Because an adult trichogen cell marker has not been previously reported, we generated knock-in GAL4 lines for two candidate genes identified through a literature search. One line, atk-GAL4, broadly drives expression in cells that are distinct from those expressing ASE5 or prospero (which are also distinct from each other), supporting their identity as trichogen cells. Finally, we examined an Obp19d-GAL4 line based on prior reports that Obp19d is predominantly expressed in epithelial cells. Like the support cell markers, Obp19d-GAL4 widely labels non-neuronal cells. The Obp19d-positive cells are also distinct from support cells, confirming their epithelial identity. Together, our findings provide a validated framework for distinguishing antennal support cell classes in the adult fly, a crucial step for understanding their individual roles in olfactory sensilla.
