Molecular neurobiology of Drosophila taste

Abstract

Drosophila is a powerful model in which to study the molecular and cellular basis of taste coding. Flies sense tastants via populations of taste neurons that are activated by compounds of distinct categories. The past few years have borne witness to studies that define the properties of taste neurons, identifying functionally distinct classes of sweet and bitter taste neurons that express unique subsets of gustatory receptor (Gr) genes, as well as water, salt, and pheromone sensing neurons that express members of the pickpocket (ppk) or ionotropic receptor (Ir) families. There has also been significant progress in terms of understanding how tastant information is processed and conveyed to higher brain centers, and modulated by prior dietary experience or starvation.

Molecular and Cellular Organization of Taste Neurons in Adult Drosophila Pharynx

“…In Drosophila , taste neurons located in sensilla in several body regions sense and distinguish nutritive substances such as sugars, amino acids, and low salt, and potentially harmful ones such as high salt, acids, and a diverse variety of bitter compounds (Freeman and Dahanukar, 2015, Liman et al, 2014). Hair-like sensilla on the labellum, the distal segments of the legs (tarsi), the anterior wing margins, and the ovipositor have access to chemicals in external substrates.…”

“…The expression and function of members of several chemosensory receptor gene families such as Gustatory receptors (Grs), Ionotropic receptors (Irs), Pickpocket (Ppk), and Transient receptor potential channels (Trps) have been found in external gustatory receptor neurons (GRNs) of the labellum and the tarsal segments (Freeman and Dahanukar, 2015). A number of Gr - and Ir-GAL4 drivers are also shown to label pharyngeal organs (Kwon et al, 2014, Koh et al, 2014), however only a few, including Gr43a and members of sweet Gr clade, Gr2a , Ir60b , and TrpA1 , have been mapped to specific taste neurons (LeDue et al, 2015, Kang et al, 2010, Miyamoto et al, 2012, Kim et al, 2017, Joseph et al, 2017).…”

The Basis of Food Texture Sensation in Drosophila

“…Food preferences are affected greatly by the qualities of food, including nutrient value, texture, and the taste valence of sweet, bitter, salty and sour qualities (Foster et al, 2011; Freeman and Dahanukar, 2015; Galindo et al, 2012; Joseph and Carlson, 2015; Koc et al, 2013; Liman et al, 2014). During the last fifteen years, many of the gustatory receptor proteins that participate in the discrimination of the chemical composition of food have been defined (Liman et al, 2014).…”

Motor control of fly feeding

“…A considerable body of work on blowflies has provided a deep understanding of fly feeding behavior (reviewed in Dethier 1976), and has laid the foundation for new work in Drosophila to delve into brain circuitry underlying feeding, using modern molecular genetic techniques. Good progress has been made on understanding gustatory receptors neurons (reviewed in Freeman andDahanukar 2015, Joseph andCarlson 2015), but this review will focus on what lies downstream: the circuitry underlying the sensorymotor transformations that control the motor actions of feeding, in adult blowflies (particularly Calliphora and Phormia) and Drosophila. These are all higher flies of the suborder Cyclorrhapha, with extremely similar mouthpart anatomy ( Figure 1).…”