Ir56d-dependent fatty acid responses in Drosophila uncovers taste discrimination between different classes of fatty acids

Abstract

18Chemosensory systems are critical for evaluating the caloric value and potential toxicity of food 19 prior to ingestion. While animals can discriminate between 1000's of odors, much less is known 20 about the discriminative capabilities of taste systems. Fats and sugars represent calorically 21 potent and innately attractive food sources that contribute to hedonic feeding. Despite the 22Ionotropic receptor 56d (Ir56d) neurons reveals broad responsive to short-, medium-, and long-33 chain fatty acids, suggesting selectivity is unlikely to occur through activation of distinct sensory 34 neuron populations. However, genetic deletion of IR56d selectively disrupts response to 35 medium chain fatty acids, but not short and long chain fatty acids. These findings reveal Ir56d is 36 selectively required for fatty acid taste, and discrimination of fatty acids occurs through 37 differential receptor activation within shared populations of neurons. These findings uncover a 38 capacity for the taste system to encode tastant identity within a taste category. 39