Taste is a short-range contact chemosensation required by all animals to detect nutrient rich foods and avoid consuming toxic chemicals. In insects, it is also required to select mates and appropriate oviposition sites. Organization of the fruit fly Drosophila melanogaster taste system and availability of experimental tool box, makes Drosophila gustatory system an ideal model system for studying the perception of taste and taste elicited behaviors. Like humans, fruit flies also respond to wide range of taste chemical and can differentiate between different taste categories including sweet, bitter, sour, umami and salt. This chapter will present a research progress made in the field of taste using neuroanatomical, genetic, behavioral, molecular and cellular biology techniques in the fruit fly. The compiled survey will provide an outlook of taste research done in fruit fly and its comparison with human taste behavior.
Part of the book: Animal Models in Medicine and Biology
Fruit fly, Drosophila melanogaster is a most powerful animal model for exploring fundamental biological processes and modeling molecular and cellular aspects of human diseases. It provides the flexibility and tool box with which scientists can experimentally manipulate and study behavior as well as gene expression in specific, defined population of cells in their normal tissue contexts. The utility and increasing value of a sophisticated genetic system of flies, the tool box available for studying physiological function, functional imaging, neural circuitry from gut to brain, taste receptors expression and controlling gene expression by determining the specific cells in the intestine, makes fly gut the most useful tissue for studying the regulation of feeding behavior under changing internal state. To understand the intestine and its connectivity with the brain, Drosophila has proved an ideal model organism for studying gut brain axis aspects of human metabolic diseases. Various markers and fly lines are available to characterize the expression of transgenes in the intestine. The newly generated genetic tools aim to streamline the design of experiments to target specific cells in intestine for genetic manipulations based on their type and location within physiologically specialized intestinal regions. This chapter will be useful for understanding post-ingestive sensing system that mediate food preferences and to investigate fundamental biological processes and model human diseases at the level of single cells in the fly gut. Furthermore, the utility of adult fly gut can be extended to the study of dietary and environmental factors relevant to health and disease by screening for cells and micro circuits stimulated by internal state or the consumption of various nutrients.
Part of the book: Preclinical Animal Modeling in Medicine
When there is a perturbation in the balance between hunger and satiety, food intake gets mis-regulated leading to excessive or insufficient eating. In humans, abnormal nutrient consumption causes metabolic conditions like obesity, diabetes, and eating disorders affecting overall health. Despite this burden on society, we currently lack enough knowledge about the neuronal circuits that regulate appetite and taste perception. How specific taste neuronal circuits influence feeding behaviours is still an under explored area in neurobiology. The taste information present at the periphery must be processed by the central circuits for the final behavioural output. Identification and understanding of central neural circuitry regulating taste behaviour and its modulation by physiological changes with regard to internal state is required to understand the neural basis of taste preference. Simple invertebrate model organisms like Drosophila melanogaster can sense the same taste stimuli as mammals. Availability of powerful molecular and genetic tool kit and well characterized peripheral gustatory system with a vast array of behavioural, calcium imaging, molecular and electrophysiological approaches make Drosophila an attractive system to investigate and understand taste wiring and processing in the brain. By exploiting the gustatory system of the flies, this chapter will shed light on the current understanding of central neural taste structures that influence feeding choices. The compiled information would help us better understand how central taste neurons convey taste information to higher brain centers and guide feeding behaviours like acceptance or rejection of food to better combat disease state caused by abnormal consumption of food.
Part of the book: Role of Obesity in Human Health and Disease