Taste preference for amino acids is dependent on internal nutritional state inDrosophila melanogaster

Abstract

SUMMARYLike mammals, insects need to ingest proteins from foods because they cannot synthesise several amino acids. Amino acids are also essential nutrients for Drosophila melanogaster, especially for female egg production, but how flies detect amino acids and how the feeding response to amino acids is regulated are unknown. In this study, the two-choice preference test, the proboscis extension reflex test and a CAFE assay were performed to explore the ability of D. melanogaster to detect and discriminate amino acids. To determine whether D. melanogaster change their feeding preference to amino acids after being deprived of them, as previously reported in the locust, two groups of flies raised on the usual medium or on glucose medium were compared. Aminoacid-deprived flies demonstrated enhanced preference to an amino acid mixture and to several amino acids. These flies ingested amino acids even when they were replete with glucose. The proboscis extension reflex to particular amino acids was induced only in amino-acid-deprived flies. Our findings indicate that the sensitivity of labellar taste cells to amino acids may change when flies are deficient in amino acid supply, and also reveal that the detection pathways for individual amino acids may differ. We suggest the existence of an amino acid receptor and a monitoring system regulating the feeding responses to amino acids. Supplementary material available online at

Taste Sensation inDrosophila melanoganster

“…However, functional sensors of amino acids in fruit flies have not been reported, even though amino acids are essential nutrients. Recent report suggests that amino acid-deprived flies show enhanced preference to several amino acids [22]. This study indicates that the internal nutritional state might modulate the sensitivity of labellar taste cells, because most amino acids do not induce any action potentials from labellar sensilla [22].…”

“…Recent report suggests that amino acid-deprived flies show enhanced preference to several amino acids [22]. This study indicates that the internal nutritional state might modulate the sensitivity of labellar taste cells, because most amino acids do not induce any action potentials from labellar sensilla [22]. Although it is not clear whether Drosophila are able to sense the 20 proteinogenic amino acids, Drosophila avoid L-canavanine, which is structurally related to L-arginine [23].…”

How to know which food is good for you: bumblebees use taste to discriminate between different concentrations of food differing in nutrient content

“…However, we do not know which compounds are actually used for discrimination. Insects are generally able to perceive tastes similar to humans and have receptors for bitter and sweet substances as well as for several amino acids (Zhang et al, 2010;Toshima and Tanimura, 2012; for bees, see Linander et al, 2012), glycerol and water (as reviewed for Drosophila by Liman et al, 2014). Bees are even able to sense very small amounts of sugar (de Brito Sanchez, 2011).…”

The Systemic Control of Growth

“…By sensing fluctuating fructose levels, the brain neurons promote feeding in hungry flies and suppress feeding in satiated ones. Besides carbohydrates, adult flies also sense amino acids and a deprivation of amino acids induces a change in their feeding preference (Ribeiro and Dickson 2010;Vargas et al 2010;Toshima and Tanimura 2012). In larval brain, a specialized circuitry consisting of three dopaminergic neurons senses hemolymph content in essential amino acids.…”