A Genetic Tool Kit for Cellular and Behavioral Analyses of Insect Sugar Receptors (original) (raw)
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Drosophila sugar receptors in sweet taste perception, olfaction, and internal nutrient sensing
Current biology : CB, 2015
Identification of nutritious compounds is dependent on expression of specific taste receptors in appropriate taste-cell types [1]. In contrast to mammals, which rely on a single, broadly tuned heterodimeric sugar receptor [2], the Drosophila genome harbors a small subfamily of eight, closely related gustatory receptor (Gr) genes, Gr5a, Gr61a, and Gr64a-Gr64f, of which three have been proposed to mediate sweet taste [3-6]. However, expression and function of several of these putative sugar Gr genes are not known. Here, we present a comprehensive expression and functional analysis using Gr(LEXA/GAL4) alleles that were generated through homologous recombination. We show that sugar Gr genes are expressed in a combinatorial manner to yield at least eight sets of sweet-sensing neurons. Behavioral investigations show that most sugar Gr mutations affect taste responses to only a small number of sugars and that effective detection of most sugars is dependent on more than one Gr gene. Surpris...
The Molecular Basis of Sugar Sensing in Drosophila Larvae
Current Biology, 2013
Evaluation of food chemicals is essential to make appropriate feeding decisions. The molecular genetic analysis of Gustatory receptor (Gr) genes and the characterization of the neural circuits that they engage has led to a broad understanding of taste perception in adult Drosophila [1, 2]. For example, eight relatively highly conserved members of the Gr gene family (Gr5a, Gr61a, and Gr64a-f), referred to as sugar Gr genes, are thought to be involved in sugar taste in adult flies [3–8], while the majority of the remaining Gr genes are likely to encode bitter taste receptors [9–11], albeit some function as pheromone [12–14] and carbon dioxide [15, 16] receptors. In contrast to the adult fly, relatively little is known about the cellular and molecular basis of taste perception in larvae. Here, we identify Gr43a, which was recently shown to function as a hemolymph fructose sensor in adult flies [17], as the major larval sugar receptor. We show that it is expressed in taste neurons, proventricular neurons, as well as sensory neurons of the brain. Larvae lacking Gr43a fail to sense sugars, while larvae mutant for all eight sugar Gr genes exhibit no obvious defect. Finally, we show that brain neurons are necessary and sufficient for sensing all main dietary sugars, which probably involves a postingestive mechanism of converting carbohydrates into fructose.
Partial “Sweet Taste Blindness” and Configurational Requirement of Stimulants in a Drosophila Mutant
The Japanese journal of genetics, 1978
Since recent success in the identification of "sugar receptor protein" from a bacterium (Hazelbauer and Adler 1971), there has been increasing interest in the properties of sugar receptor sites or receptor substances both in mammals and insects. Recent studies on blockade of sugar receptor of the fleshfly, Boettcherisca peregrina, by treatment with the sulphhydryl reagent, p-chloromercuribenzoate (PCMB), could show the existence of two different sugar receptor sites, a "pyranose site" and a "f uranose site" (Shimada et al. 1974). A similar conclusion was reached from an entirely
Nature communications, 2016
Finding food sources is essential for survival. Insects detect nutrients with external taste receptor neurons. Drosophila possesses multiple taste organs that are distributed throughout its body. However, the role of different taste organs in feeding remains poorly understood. By blocking subsets of sweet taste receptor neurons, we show that receptor neurons in the legs are required for immediate sugar choice. Furthermore, we identify two anatomically distinct classes of sweet taste receptor neurons in the leg. The axonal projections of one class terminate in the thoracic ganglia, whereas the other projects directly to the brain. These two classes are functionally distinct: the brain-projecting neurons are involved in feeding initiation, whereas the thoracic ganglia-projecting neurons play a role in sugar-dependent suppression of locomotion. Distinct receptor neurons for the same taste quality may coordinate early appetitive responses, taking advantage of the legs as the first appen...
Genetic Variation in Taste Sensitivity to Sugars in Drosophila melanogaster
Chemical Senses, 2017
Taste sensitivity plays a major role in controlling feeding behavior, and alterations in feeding habit induced by changes in taste sensitivity can drive speciation. We investigated variability in taste preferences in wild-derived inbred lines from the Drosophila melanogaster Genetic Reference Panel. Preferences for different sugars, which are essential nutrients for fruit flies, were assessed using two-choice preference tests that paired glucose with fructose, sucrose, or trehalose. The twochoice tests revealed that individual lines have differential and widely variable sugar preferences, and that sugar taste sensitivity is polygenic in the inbred population tested. We focused on 2 strains that exhibited opposing preferences for glucose and fructose, and performed proboscis extension reflex tests and electrophysiological recordings on taste sensilla upon exposure to fructose and glucose. The results indicated that taste sensitivity to fructose is dimorphic between the 2 lines. Genetic analysis showed that high sensitivity to fructose is autosomal dominant over low sensitivity, and that multiple loci on chromosomes 2 and 3 influence sensitivity. Further genetic complementation tests for fructose sensitivity on putative gustatory receptor (Gr) genes for sugars suggested that the Gr64a-Gr64f locus, not the fructose receptor gene Gr43a, might contribute to the dimorphic sensitivity to fructose between the 2 lines.
Neurophysiology of gustatory receptor neurones in Drosophila.
SEB experimental …, 2009
Source: PubMed CITATIONS 8 READS 287 4 authors, including: Some of the authors of this publication are also working on these related projects: Behavioural ecology and chemical communication in vespa velutina View project Teiichi Tanimura Kyushu University 95 PUBLICATIONS 2,795 CITATIONS SEE PROFILE
Two antagonistic gustatory receptor neurons responding to sweet‐salty and bitter taste in Drosophila
Journal of …, 2004
In Drosophila, gustatory receptor neurons (GRNs) occur within hair-like structures called sensilla. Most taste sensilla house four GRNs, which have been named according to their preferred sensitivity to basic stimuli: water (W cell), sugars (S cell), salt at low concentration (L1 cell), and salt at high concentration (L2 cell). Labellar taste sensilla are classified into three types, l-, s-, and i-type, according to their length and location. Of these, l-and s-type labellar sensilla possess these four cells, but most i-type sensilla house only two GRNs. In i-type sensilla, we demonstrate here that the first GRN responds to sugar and to low concentrations of salt (10 -50 mM NaCl). The second GRN detects a range of bitter compounds, among which strychnine is the most potent; and also to salt at high concentrations (over 400 mM NaCl). Neither type of GRN responds to water. The detection of feeding stimulants in i-type sensilla appears to be performed by one GRN with the combined properties of S ؉ L1 cells, while the other GRN detects feeding inhibitors in a similar manner to bitter-sensitive L2 cells on the legs. These sensilla thus house two GRNs having an antagonistic effect on behavior, suggesting that the expression of taste receptors is segregated across them accordingly.
Spatially restricted expression of candidate taste receptors in the Drosophila gustatory system
Current Biology, 2001
Drosophila, taste is perceived by gustatory neurons located in sensilla Research Drive, Box 3054, Durham, North distributed on several different appendages throughout the body of the Carolina 27710, USA. animal. Here we show that the gustatory receptors are encoded by a family of at least 54 genes (Gr genes), most of which are expressed Present address: *Theodor-Boveri-Institut fü r exclusively in a small subset of taste sensilla located in narrowly defined Biowissenschaften, Lehrstuhl fü r Genetik und Neurobiologie, Universitä t Wü rzburg, Wü rzburg regions of the fly's body.
Limited taste discrimination in Drosophila
Proceedings of the National Academy of Sciences, 2010
In the gustatory systems of mammals and flies, different populations of sensory cells recognize different taste modalities, such that there are cells that respond selectively to sugars and others to bitter compounds. This organization readily allows animals to distinguish compounds of different modalities but may limit the ability to distinguish compounds within one taste modality. Here, we developed a behavioral paradigm in Drosophila melanogaster to evaluate directly the tastes that a fly distinguishes. These studies reveal that flies do not discriminate among different sugars, or among different bitter compounds, based on chemical identity. Instead, flies show a limited ability to distinguish compounds within a modality based on intensity or palatability. Taste associative learning, similar to olfactory learning, requires the mushroom bodies, suggesting fundamental similarities in brain mechanisms underlying behavioral plasticity. Overall, these studies provide insight into the d...
G-protein gamma subunit 1 is required for sugar reception in Drosophila
The EMBO Journal, 2005
Though G-proteins have been implicated in the primary step of taste signal transduction, no direct demonstration has been done in insects. We show here that a G-protein gamma subunit, Gc1, is required for the signal transduction of sugar taste reception in Drosophila. The Gc1 gene is expressed mainly in one of the gustatory receptor neurons. Behavioral responses of the flies to sucrose were reduced by the targeted suppression of neural functions of Gc1expressing cells using neural modulator genes such as the modified Shaker K þ channel (EKO), the tetanus toxin light chain or the shibire (shi ts1) gene. RNA interference targeting to the Gc1 gene reduced the amount of Gc1 mRNA and suppressed electrophysiological response of the sugar receptor neuron. We also demonstrated that responses to sugars were lowered in Gc1 null mutant, Gc1 N159. These results are consistent with the hypothesis that Gc1 participates in the signal transduction of sugar taste reception.