preparing the recording electrodes and drosophila for analyzing responses of taste neurons

A Novel Method for Enhanced Analysis of Insect Taste Neuron Activity

Insects, including drosophilid flies, are endowed with a sophisticated taste system that enables them to extract complex chemical information from their surroundings. This system allows them to discern the chemical composition of various substances, distinguishing between those that are nutritious and those that are harmful1,2.
At the core of this system are specialized structures known as taste hairs or sensilla, strategically located on various body parts. In drosophilid flies, these sensilla are located on the labellum, which is the major taste organ of the fly head1,2,3,4, as well as on the legs and wings1,2,5,6. The labellum is located at the tip of the proboscis and contains two lobes4,7,8. Each lobe is covered with 31 taste sensilla categorized as short, long, and intermediate4,7,8. These sensilla each house 2-4 taste neurons1,2,9,10. These taste neurons express members of at least four different gene families, namely the Gustatory receptor (Gr), Ionotropic receptor (Ir), Pickpocket (Ppk), and Transient receptor potential (Trp) genes1,2,11,12,13. This diversity of receptors and channels equips insects with the ability to recognize a wide array of chemical compounds, including both nonvolatile and volatile cues1,2,14.
For over 50 years, scientists have quantified the response of taste neurons and their receptors using a technique called tip recording3,4,6,8,13,15,16,17,18,19,20,21,22,23,24,25,26,27,28, 
29,30,31,32,33,34,35. However, this method has major limitations. First, neural activity can be measured only during contact with the stimulus, and not before or after contact. This limitation precludes the measurement of spontaneous spiking activity and prevents the measurement of OFF responses. Second, only tastants that are soluble in aqueous solutions can be tested.
These limitations can be overcome by a rarely used alternative electrophysiological technique called &#34;base recording.&#34; Here we describe this technique, which we have adapted from a method used by Marion-Poll and colleagues24, and show the crucial taste coding features that it can now conveniently measure14.

Author Spotlight: Advances in Chemoreception &#8211; From Insect Odor Receptors to Non-Coding RNAs

Base Recording: A Technique for Analyzing Responses of Taste Neurons in Drosophila

Our lab investigates how animals detect and respond to odors, taste, and some pheromone. We've made significant strides in understanding the molecular basis of chemoreception. We've made several advances in the field, including the discovery of the first insect odor receptors, the discovery of the first insect taste receptors, and the elucidation of basic principles of the logic of odor and taste coding.This technique allows the measurement of test neuron activity before, during, and after the stimulus. Thus, it allows extensive analysis of OFF responses that occur after a taste stimulus. It also allows the measurement of taste neuron activity to the river of volatile compounds.The classical technique for taste electrophysiology was unable to measure taste responses to hydrophobic compounds such as long-chain pheromones that have very low solubility in water. However, with the help of this technique, we can overcome this limitation by separating the recording electrode from the glass stimulus capillary. Our research explores the functioning of the chemosensory systems in animals, focusing on their role in feeding and mating choices.We're currently examining non-coding RNAs and micro peptides in fruit flies'olfactory systems, and how mosquitoes and tsetse flies use these systems to find human hosts.

Preparing the Recording Electrodes and Drosophila for Analyzing Responses of Taste Neurons

Research

JoVE Journal

Neuroscience

Insects taste the external world through taste hairs, or sensilla, that have pores at their tips. When a sensillum comes into contact with a potential ...

Base Recording from Taste Sensilla of Drosophila for Analyzing Responses of Taste Neurons