Name: taste preference assay for adult drosophila
Uploaded: 2016-09-08T12:30:00
Description: Watch this Scientific Journal Video about Taste Preference Assay for Adult Drosophila at JoVE.com

We would like to thank members of the Tessier lab for critical reading of this manuscript and helpful suggestions during the preparation of this protocol.

1. Starvation
<ol>
	<li>Prepare fly starvation vials by saturating a cotton ball with 18.2 M&#937; water at the bottom of a standard fly vial. Alternatively, similarly saturate a small strip of filter paper with 18.2 M&#937; water and place at an angle within the vial.</li>
	<li>Collect flies into sets of ~100 animals on a CO2 pad and then add the flies to a prepared vial. 
	Note: Best results are obtained with animals that are less than 5 days old. However, the exact age of the animals can be controlle...

<ol>
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We have described a simple but effective protocol for determining taste preference in Drosophila. Versions of this assay are routinely used in experiments to determine the contributions of gustatory receptors (GRs) to perceiving the different qualities (bitter, sweet, sour, salty, and umami) of taste compounds. The Drosophila genome contains approximately 60 genes which encode 68 identified gustatory receptors by alternative splicing8,9. However, other proteins such as ionotropic glutamate re...

Animals use chemosensation to distinguish advantageous conditions apart from disadvantageous conditions. This perception can be critical for such things as determining the best food source, avoiding toxic substances or determining the best mating partner1. Chemosensation is often divided into two sensory components: olfactory senses and gustatory senses. A main distinguishing characteristic of these senses is that olfaction (smell) is used to sample the surrounding gaseous chemical environment while gustation (taste) requires physical contact with a nonvolatile substrate. Both sensory modalities stimulate neurological responses which are processed and decoded in the brain to produce the appropriate attractive or repulsive behavior2. These senses are therefore critical for animal survival.
The fruit fly Drosophila melanogaster is a model organism which continues to grow in popularity for use in understanding how insects perceive smell and taste. Fruit flies offer tremendous advantages over other model systems due to the wealth of genetic tools available for the dissection of molecular, cellular, and behavioral pathways. Work over the last 15 years has been particularly instrumental in characterizing the specific cellular identities, neuronal receptors, and signaling mechanisms involved in both smell and taste. Now, the power of Drosophila genetics is being used to further elucidate how these processes are coded at the single neuron and single circuit level3-6. Therefore, assays which provide easily scored readouts of alterations to sensory pathways are vital to the continuing advance of these fields.
While a great deal is known about how olfactory signals are coded and processed in the brain, much less is understood about similar mechanisms in the gustatory pathway. We describe here a protocol which can be used to ascertain taste preference in Drosophila. Drosophila, like mammals, generally prefer sweet tasting compounds as opposed to bitter tasting compounds. Any combination of these food sources can be utilized in this experimental design to determine how known genetic alterations affect taste choice. In addition, pharmacological intervention strategies can similarly be assessed for their effects on animals&#39; taste preference. The ease and flexibility of this assay makes it a useful paradigm for understanding the nature of gustatory perception in Drosophila.

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		<tr height="17">
			<td height="17" style="height:17px;width:543px;">Blue Food Coloring (Water, Propylene Glycol, FD&#38;C Blue 1 and Red 40, Propylparaben)</td>
			<td style="width:128px;">McCormick</td>
			<td style="width:111px;">N/A</td>
			<td style="width:251px;"></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Cryo/Freezer Boxes w/o Dividers</td>
			<td>Fisher</td>
			<td>03-395-455</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Dumont #5 Forceps</td>
			<td>Fine Science Tools</td>
			<td>11251-20</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Glacial Acetic Acid</td>
			<td>Fisher</td>
			<td>BP2401-500</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Leica S6 E Stereozoom 0.63x-4.0x microscope</td>
			<td>W. Nuhsbaum, Inc.</td>
			<td>10446294</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Petri Dish (100 x 15 mm)</td>
			<td>BD Falcon</td>
			<td>351029</td>
			<td>Reuseable if thoroughly washed and dried</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Quick-Snap Microtubes</td>
			<td>Alkali Scientific Inc.</td>
			<td>C3017</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Red Food Coloring (Water, Propylene Glycol, FD&#38;C Reds 40 and 3, Propylparaben)</td>
			<td>McCormick</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Sucrose</td>
			<td>IBI Scientific</td>
			<td>IB37160</td>
			<td></td>
		</tr>
	</tbody>
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taste preference assay for adult drosophila

Olfactory and gustatory perception of the environment is vital for animal survival. The most obvious application of these chemosenses is to be able to distinguish good food sources from potentially dangerous food sources. Gustation requires physical contact with a chemical compound which is able to signal through taste receptors that are expressed on the surface of neurons. In insects, these gustatory neurons can be located across the animal's body allowing taste to play an important role in many different behaviors. Insects typically prefer compounds containing sugars, while compounds that are considered bitter tasting are avoided. Given the basic biological importance of taste, there is intense interest in understanding the molecular mechanisms underlying this sensory modality. We describe an adult Drosophila taste assay which reflects the preference of the animals for a given tastant compound. This assay may be applied to animals of any genetic background to examine the taste preference for a desired soluble compound.

Some typical results from taste preference assays are shown below. In most experiments some variation in intensity of abdominal coloring will be seen (Figure 1). Any coloring in the abdomen whether intense or weak is considered a positive ingestion. It is therefore advisable for researchers to score animals while blind to the experimental condition so as to limit any potential biases.
It is also important to cho...

Watch this Scientific Journal Video about Taste Preference Assay for Adult Drosophila at JoVE.com

Taste Preference Assay for Adult Drosophila

Taste is an important sensory process which facilitates attraction to beneficial substances and avoidance of toxic substances. This protocol describes a simple ingestion assay for determining Drosophila gustatory preference for a given chemical compound.

Taste Preference Assay for Adult Drosophila

Olfactory and gustatory perception of the environment is vital for animal survival.  The most obvious application of these chemosenses is to be able to ...

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