Temperature and Sweet Taste Integration in Drosophila

Abstract

Highlights d Flies find sweet foods less appealing if they are cool d Rejection of cool food requires bitter taste neurons and mechanosensory neurons d Bitter taste neurons and mechanosensory neurons in the fly tongue are cool activated d A rhodopsin is needed in a subset of bitter taste neurons for rejecting cool food

Ionotropic Receptor-dependent cool cells control the transition of temperature preference in Drosophila larvae

“…showed that Rh5 and Rh6 are coexpressed with TRPA1 in the body wall. A recent study identified that Rh6 and a different PLC, PLC21C, are necessary for the cool activation of adult bitter neurons [28]. If the function of Rh6 in cool sensing is conserved throughout the development, then the rhodopsin pathway, at the late third instar, drives an attractive behavior.…”

Mechanism for food texture preference based on grittiness

“…We prepared flies for the PER assays as described. 8 Briefly, we starved males for 2 hr for the assays, unless indicated otherwise, and trapped the animals in a cutoff pipet tip (Olympus 200 mL Reach Tip, 24-150RL) with only the labellum exposed. We water saturated the flies before stimulating them with the food (0.5 mL in volume) for $0.2-0.6 s on the labellum.…”

“…To monitor a fly's motivation to feed, we used the proboscis extension response (PER). 8,21 If the labellum is touched with an appealing food at the end of a probe, the animal will extend its proboscis in an attempt to feed. The interest in feeding increases with the starvation time.…”

“…To perform the analyses, we prepared samples as described previously. 8 Briefly, fly heads were cut with fine scissors in 1xPBS. After allowing the samples to recover for 2-5 minutes (until the proboscis was extended and the two labia were in a closed state), we sealed the cut area on the neck with silicone lubricant (Dow Corning, DC 976 High Vacuum Grease).…”

“…Recently, our group and others have begun to exploit the fruit fly, Drosophila melanogaster, to unravel the receptors and neurons that allow animals to evaluate palatability based on physical features of food including hardness, [5][6][7] viscosity, 7 and temperature. 8 For humans, one of the key physical features of food that impacts food appeal is particle size. For example, ice crystals of 10-20 mm cause ice cream to be perceived as very smooth, whereas larger crystals of 50 mm confer a perception of grittiness.…”