Straightforward Assay for Quantification of Social Avoidance in Drosophila melanogaster

Summary

Here, we present a protocol to quantify the avoidance of stressed individuals. This paradigm is powerful yet user-friendly and can be used to assess the influence of genes and environment on one kind of social interaction in Drosophila melanogaster.

Abstract

Drosophila melanogaster is an emerging model to study different aspects of social interactions. For example, flies avoid areas previously occupied by stressed conspecifics due to an odorant released during stress known as the Drosophila stress odorant (dSO). Through the use of the T-maze apparatus, one can quantify the avoidance of the dSO by responder flies in a very affordable and robust assay. Conditions necessary to obtain a strong performance are presented here. A stressful experience is necessary for the flies to emit dSO, as well as enough emitter flies to cause a robust avoidance response to the presence of dSO. Genetic background, but not their group size, strongly altered the avoidance of the dSO by the responder flies. Canton-S and Elwood display a higher performance in avoiding the dSO than Oregon and Samarkand strains. This behavioral assay will allow identification of mechanisms underlying this social behavior, and the assessment of the influence of genes and environmental conditions on both emission and avoidance of the dSO. Such an assay can be included in batteries of simple diagnostic tests used to identify social deficiencies of mutants or environmental conditions of interest.

Introduction

The goal of this method is to easily quantify a new aspect of simple social behavior in Drosophila melanogaster, independent from courtship and aggression.

Social interactions are crucial to the proper development and health of individuals within a society, as well as the functionality of a social group as a whole. The high complexity of these interactions necessitates large sample sizes and a system that allows for simplification of the behavior as the genetic and neural bases of social behavior are still poorly understood. Drosophila melanogaster is a powerful genetic model that can be used to identify the genetic and ne....

Protocol

1. Equipment and Reagents Created In-house (See List of Material for Others)

1. Prepare a Drosophila cold anesthesia apparatus to perform fly work.
   1. Cut a porous polyethylene sheet to cover a small plastic box (12.7 cm long, 10.2 cm wide), typically the top cover of a pipette tips box (12.7 cm long, 10.2 cm wide, 3.8 cm deep).
   2. Fill the box with crushed ice, cover with the porous polyethylene sheet. 
2. Prepare a T-maze apparatus; adapt the apparatus previously described in details ^28-31.
3. Prepare a fly aspirator as described ³².
4. Prepare a phototaxis response apparatus to ....

Results

The social avoidance assay is a robust test quantifying the ability of Drosophila melanogaster to recognize a stress signal (dSO) emitted by other flies, and thus assessing one aspect of social interactions. The assay is performed using an apparatus commonly used in various behavior assays known as a T-maze, which present the flies with a choice between two different options — left or right^19,28-31. In this case, the efficiency at which the flies avoid the dSO is quantified by calculating and comparin.......

Discussion

This protocol describes a detailed procedure for the social avoidance assay. Canton-S will only avoid a vial in which flies have previously been mechanically stressed, and that sex and number of responders does not affect that social avoidance performance. However, genetic background of the responders has a major influence.

The following are several critical steps for performing this experiment successfully: 1) always transfer the flies 2 hr before the experiment and make sure not to disturb t.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Stereo Zoom Microscope	Nikon	SMZ-645	Any other standard scope for fly handling would work
Small paint brushes			for pushing flies
Porous Polyethylene, 12" x 12" Sheet	Flystuff - Genesee	46-100	http://www.flystuff.com/ProductInfo.php?productID=46-100 Porous Plastic sheet for the cold anesthesia box
Mini-Alarm Timer/Stopwatch
Sharpie pens
Adhesive Tape
Mini vortex	Fisher	14-955-151	http://www.fishersci.com/ecomm/servlet/itemdetail For mechanical agitation of the flies - any vortex would work.
Corning Life Sciences DL No.:352017, Falcon test tube; round bottom; disposable; no closure, 14 ml; 17 x 100 mm	Fisher	14-959-8	http://www.fishersci.com/ecomm/servlet/itemdetail?storeId=10652&langId=-1&catalogId=29104&productId=2771811&distype=0&highlightProductsItemsFlag=Y&fromSearch=1&searchType=PROD&hasPromo=0 These snap in place in the in-house made T-maze and counter-current apparatus (see text)
cotton balls			to close the vials after the experiment.
trifold board and white bench cover			to provide a white background, and a homogeneous light.
white bench cover
pounding pad			any mouse pad works.
large black cloth			to cover the counter-current apparatus in phototaxis response.
cool-white light	Home Depot	1000516563	http://www.homedepot.ca/product/illume-26-fluorescent-plug-in-linear/911423 any similar linear light with fluorescent light bulb cool-white at 13-15 W would work