Name: using linear agarose channels to study drosophila larval crawling behavior
Uploaded: 2016-11-26T14:00:00
Description: Watch this Scientific Journal Video about Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior at JoVE.com

We would like to thank Chris Wreden and Michelle Bland for comments on the manuscript and for technical help.

1. Preparation of Larvae
<ol>
	<li>One week before recording behavior, set up a cross (minimum of 25 virgins and 5 males). Maintain all crosses and progeny at 25 &#176;C. 
	NOTE: The temperature of culture conditions can be altered, but the time line described below would need to be adjusted to account for changes in developmental speed.</li>
	<li>5 days before recording, first thing in the morning, place the cross into a collection cage with an agar/juice cap and a dab (0.5-1 ml) of yeast paste in the center of t...

<ol>
	<li>Heckscher, E. S., Lockery, S. R., Doe, C. Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+Drosophila+larval+crawling+at+the+level+of+organism,+segment,+and+somatic+body+wall+musculature.">Characterization of Drosophila larval crawling at the level of organism, segment, and somatic body wall musculature.</a> J Neurosci. 32 (36), 12460-12471 (2012).</li><li>Marder, E., Calabrese, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Principles+of+rhythmic+motor+pattern+generation.">Principles of rhythmic motor pattern generation.</a> Physiol rev. 76 (3), 687 (1996).</li><li>Mullins, O. J., Hackett, J. T., Buchanan, J. T., Friesen, W. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuronal+control+of+swimming+behavior:+Comparison+of+vertebrate+and+invertebrate+model+systems.">Neuronal control of swimming behavior: Comparison of vertebrate and invertebrate model systems.</a> Prog Neurobiol. 93 (2), 244-269 (2011).</li><li>Ohyama, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+multilevel+multimodal+circuit+enhances+action+selection+in+Drosophila.">A multilevel multimodal circuit enhances action selection in Drosophila.</a> Nature. 520 (7549), 633-639 (2015).</li><li>Landgraf, M., Thor, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+Drosophila+motoneurons:+specification+and+morphology.">Development of Drosophila motoneurons: specification and morphology.</a> Semin cell devl bio. 17 (1), 3-11 (2006).</li><li>Heckscher, E. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Even-Skipped(+)+Interneurons+Are+Core+Components+of+a+Sensorimotor+Circuit+that+Maintains+Left-Right+Symmetric+Muscle+Contraction+Amplitude.">Even-Skipped(+) Interneurons Are Core Components of a Sensorimotor Circuit that Maintains Left-Right Symmetric Muscle Contraction Amplitude.</a> Neuron. 88 (2), 1-16 (2015).</li><li>Green, C. H., Burnet, B., Connolly, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organization+and+patterns+of+inter-and+intraspecific+variation+in+the+behaviour+of+Drosophila+larvae.">Organization and patterns of inter-and intraspecific variation in the behaviour of Drosophila larvae.</a> Anim Behav. 31 (1), 282-291 (1983).</li><li>Graf, S. A., Sokolowski, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rover/Sitter+Drosophila+melanogaster+Larval+Foraging+Polymorphism+as+a+Function+of+Larval+Development,+Food-Patch+Quality,+and+Starvation.">Rover/Sitter Drosophila melanogaster Larval Foraging Polymorphism as a Function of Larval Development, Food-Patch Quality, and Starvation.</a> J Insect Behav. 2 (3), 301-313 (1989).</li><li>Lee, T., Luo, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mosaic+analysis+with+a+repressible+cell+marker+for+studies+of+gene+function+in+neuronal+morphogenesis.">Mosaic analysis with a repressible cell marker for studies of gene function in neuronal morphogenesis.</a> Neuron. 22 (3), 451-461 (1999).</li><li>Rebay, I., Rubin, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Yan+Functions+as+a+General+Inhibitor+of+Differentiation+and+Is+Negatively+Regulated+by+Activation+of+the+Rasl+/+MAPK+Pathway.">Yan Functions as a General Inhibitor of Differentiation and Is Negatively Regulated by Activation of the Rasl / MAPK Pathway.</a> Cell. 81 (6), 857-866 (1995).</li><li>Chen, T. -. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasensitive+fluorescent+proteins+for+imaging+neuronal+activity.">Ultrasensitive fluorescent proteins for imaging neuronal activity.</a> Nature. 499 (7458), 295-300 (2013).</li><li>Tufte, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The visual display of quantitative information. , (2004).</li></ol>

A microfluidic device was built to make linear agarose channels that can accommodate Drosophila larvae (Figure 1). When Drosophila larvae are placed in these linear agarose channels their behavioral repertoire is limited to crawling, which allows for detailed observation of the dynamics of larval structures over the crawl cycle.
A successful recording occurs when a larva perform a series of rhythmic strides (Figure 3). If this does not occur,...

The overall goal of this method is to study Drosophila larval crawling in detail. Experiments on locomotion have played an important role in developing and testing theories on motor control2. Traditionally locomotion has been studied in aquatic animals (e.g., leech, lamprey, tadpole)3. The repetitive nature of locomotion in these animals has allowed for the study of rhythmogenesis, for analysis of the biophysical events driving locomotion, and for monitoring the neural firing patterns that accompany locomotion.
The use of Drosophila larvae for studies of locomotion presents a unique combination of advantages over other model systems: facile genetics, well-characterized development, a body that is optically clear at first and second instars, and an ongoing transmission electron microscopic reconstruction of the entire nervous system4-6. However, Drosophila larval locomotion on flat open surfaces is somewhat complex including pauses, turns, and meandering crawls7. This publication presents a method to use linear agarose channels to guide Drosophila larval locomotor behavior such that larvae perform sustained, straight, rhythmic crawling behavior.
Studying Drosophila larval behavior in agarose channels, instead of behavior on flat open surfaces, has several advantages. First, it allows researchers to specifically select crawling behavior from the many movements that are part of the larval behavioral repertoire. Second, by adjusting the width of the channel versus the larval body size, crawling speed can be adjusted. Third, channels allow for the larva to be viewed from dorsal, ventral, or lateral side depending on how the larva is loaded and oriented within the channel. This versatility in larval orientation allows for any structure of interest to be continually visible during crawling. Fourth, channels are amenable for use with a wide variety of microscopes and objectives. For example, linear channels can be used for low-resolution imaging on bright-field stereoscopes and/or for high-resolution imaging on spinning-disc confocal microscopes1. Fifth, this method can be used in combination with optogenetic/thermogenetic neuronal manipulations in any genetic background. Finally, because both the larval body (at first and second instars) and agarose channels are optically clear, channels can be used when studying the dynamic movements, or changes in fluorescent intensity of larval structures labeled by genetically-encoded fluorescent probes.
The method described is appropriate for detailed kinematic studies of first and second instar Drosophila larval behavior. This publication analyzes the dynamic changes in fluorescent intensity of the CNS during forward larval crawling to demonstrate the use of channels and as a precursor to neuronal calcium imaging.

<table border="0" cellpadding="0" cellspacing="0" width="643">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">6 oz square Drosophila bottle</td>
			<td style="width:101px;">Scimart</td>
			<td style="width:119px;">DR-103</td>
			<td style="width:212px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">agar</td>
			<td style="width:101px;">sigma</td>
			<td style="width:119px;">A1296</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">sucrose</td>
			<td style="width:101px;">sigma</td>
			<td style="width:119px;">S9378</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">apple juice</td>
			<td></td>
			<td></td>
			<td>not from concentrate</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Tegosept</td>
			<td>Fisher</td>
			<td>T2300</td>
			<td>methyl-p-hydroxybenzoate</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">35 x 10 mm round petri dish</td>
			<td style="width:101px;">Fisher</td>
			<td align="right">351008</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">baker&#39;s yeast</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">PDMS casting mold</td>
			<td style="width:101px;">FlowJem</td>
			<td style="width:119px;"></td>
			<td>can be requested from authors</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">isopropyl alcohol</td>
			<td style="width:101px;">Fisher</td>
			<td style="width:119px;">A417-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">laboratory wipes</td>
			<td style="width:101px;">Fisher</td>
			<td style="width:119px;">06-666-11</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">canned air</td>
			<td style="width:101px;">Fisher</td>
			<td style="width:119px;">18-431</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">10 cm petri dish</td>
			<td style="width:101px;">BioPioneer</td>
			<td style="width:119px;">GS82-1473-001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">agarose</td>
			<td style="width:101px;">Fisher</td>
			<td style="width:119px;">50-444-176</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">razor blade</td>
			<td style="width:101px;">Fisher</td>
			<td style="width:119px;">12-640</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">forceps</td>
			<td style="width:101px;">FST</td>
			<td style="width:119px;">11241-40</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">22 x 40 cover glass, #1.5</td>
			<td style="width:101px;">Fisher</td>
			<td style="width:119px;">50-365-605</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Fiji (version 1.51d)</td>
			<td style="width:101px;">NIH</td>
			<td style="width:119px;"></td>
			<td>fiji.sc</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">Excel 2016</td>
			<td style="width:101px;">Microsoft</td>
			<td></td>
			<td>www.microsoftstore.com</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:211px;">MATLAB R2016</td>
			<td style="width:101px;">Mathworks</td>
			<td style="width:119px;"></td>
			<td>www.mathworks.com</td>
		</tr>
	</tbody>
</table>

using linear agarose channels to study drosophila larval crawling behavior

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat open surfaces is complex,&#160;including: pausing, turning, and meandering. This complexity in the repertoire of movement hinders detailed analysis of the events occurring during a single crawl stride cycle. To overcome this obstacle, linear agarose channels were made that constrain larval behavior to straight, sustained, rhythmic crawling. In principle, because agarose channels and the Drosophila larval body are both optically clear, the movement of larval structures labeled by genetically-encoded fluorescent probes can be monitored in intact, freely-moving larvae. In the past, larvae were placed in linear channels and crawling at the level of whole organism, segment, and muscle were analyzed1. In the future, larvae crawling in channels can be used for calcium imaging to monitor neuronal activity. Moreover, these methods can be used with larvae of any genotype and with any researcher-designed channel. Thus the protocol presented below is widely applicable for studies using the Drosophila larva as a model to understand motor control.

This article describes a method for guiding Drosophila larval behavior using agarose channels and for measuring the dynamics of larval structures over a crawl cycle. Larvae in linear channels perform sustained bouts of rhythmic crawling (Figure 3). Because both larvae and channels are optically clear, channels can be used with larvae expressing fluorescent probes expressed in any structure of interest. We recorded larvae expressing GFP in all neurons (elav-Ga...

Watch this Scientific Journal Video about Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior at JoVE.com

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

The Drosophila larva is a powerful model system to study neural control of behavior. This publication describes the use of linear agarose channels to elicit sustained bouts of linear crawling and methods to quantify the dynamics of larval structures during repetitive crawling behavior.

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat ...

The overall goal of this procedure is to observe larval stage Drosophila crawling in a linear agarose channel to study the development of neural circuits. This method can help answer key questions in the fields of neuro ethology and developmental biology, such as understanding the neural codes that generate motor patterns and identifying key genetic and cellular processes that scope neuronal circuits for movement control. The main advantage of this technique is that it restricts the larval behavior repertoire so that the researchers can study a single multi pattern in detail.Demonstrating the procedure will be Zarion Marshall a technician from my laboratory. First it is important to assess the larva's health. Three to four days before recording, replace the collection plate of the adult cage.Proceed to do this daily and at the same time of day. Count the eggs and newly hatched larvae on the plate. The expected number of eggs is between 500 and 2, 000.Adjust the number of adults in the cage as needed. We examine the plate 24 hours later to determine whether the larvae are healthy. Most of the eggs should have hatched into larvae, and the larvae should have crawled into the yeast paste.Signs of poor health include a large number of unhatched eggs, dead larval bodies away from the yeast paste, and larvae with unusually dark patches in the abdomen which is an indicator of an immune reaction. If the larvae appear unhealthy, change the cage using freshly prepared plates, and check the adults genotype. For the experiment collect newly hatched second instar larvae from one to two day old plates.All these stages can be used in the analysis. For this protocol, have a linear channel PDMS casting mold. Clean the casting mold with isopropyl alcohol.Once it is dried, place the mold into a ten centimeter lid or similar container. Then fill the mold with three percent agarose cooled to 55 degrees Celsius. Pour the agarose carefully to avoid trapping air bubbles in the mold.The mold should be just covered by the agarose. Once solidified, remove the agarose channels from the mold. Trim the edges of the disc shaped channels, and then immerse the channels in water.They can be stored in water at four degrees Celsius for up to seven days. Before using the channels, allow them to warm to room temperature. Select a channel that matches the width of the larva.The channels range from 100 to 300 microns in width and are all 150 microns deep. Then use a clean razor blade to cut a single channel from the prepared disc. With forceps transfer the channel to an appropriately sized glass cover slip or slide with the grooved side up.Next, use fine forceps to gently pick up a larva without squeezing it. A finely tipped paintbrush also works well. If squeezed, pain reflexes such as rolling or hunching may dominate the larva's behavior in the channel.Now wash the larva by briefly submerging it in water, and then place it into the cut channel gently teasing it into position. Once in the channel, adjust the orientation of the larva to make the structure of interest easy to image. Then place one or two drops of water at either end of the channel to fill the channel with water.If any air bubbles get trapped, gently lift the sides of the channel to remove them. To further adjust the orientation of the larva, gently nudge the channel to roll the larva around. The larva is now ready to be imaged.Larvae in linear channels perform sustained bouts of rhythmic crawling. Fluorescent probes are easily examined. For example, larvae expressing GFP in their neurons from the GAL4 driver show dynamic changes in fluorescent intensities emanating from the nerve cord during the crawl cycle.The CNS moves forward at nearly the same time as the larval head and tail as a wave of muscle contraction passes along the body axis, the CNS moves in and out of the plane of focus, causing the fluorescence of the nerve cord to change. The changes in fluorescence were quantified from three crawl strides for three larvae. The dynamics of the nerve cord fluorescence over the stride cycle followed a reproduce able pattern that could be used for phenotyping.After watching this video, you should have an understanding of how to collect larvae for behavior, to prepare agarose channels, and to load the larvae into the channels to visualize the linear crawling behavior. While attempting this procedure, it is important to remember to handle the larvae gently.

using-linear-agarose-channels-to-study-drosophila-larval-crawling

Research

JoVE Journal

Neuroscience

Laser Capture Microdissection of Drosophila Peripheral Neurons

The dendritic arborization (da) neurons of the Drosophila peripheral nervous system (PNS) provide an excellent model system in which to investigate the molecular mechanisms underlying class-specific dendrite morphogenesis1,2. To facilitate molecular analyses of class-specific da neuron development, it is vital to obtain these cells in a pure population. Although a range of different cell, and tissue-specific RNA isolation techniques exist for Drosophila cells, including magnetic bead based cell purification3,4, Fluorescent Activated Cell Sorting (FACS)5-8, and RNA binding protein based strategies9, none of these methods can be readily utilized for isolating single or multiple class-specific Drosophila da neurons with a high degree of spatial precision. Laser Capture Microdissection (LCM) has emerged as an extremely powerful tool that can be used to isolate specific cell types from tissue sections with a high degree of spatial resolution and accuracy. RNA obtained from isolated cells can then be used for analyses including qRT-PCR and microarray expression profiling within a given cell type10-16. To date, LCM has not been widely applied in the analysis of Drosophila tissues and cells17,18, including da neurons at the third instar larval stage of development. 
Here we present our optimized protocol for isolation of Drosophila da neurons using the infrared (IR) class of LCM. This method allows for the capture of single, class-specific or multiple da neurons with high specificity and spatial resolution. Age-matched third instar larvae expressing a UAS-mCD8::GFP19 transgene under the control of either the class IV da neuron specific ppk-GAL420 driver or the pan-da neuron specific 21-7-GAL421 driver were used for these experiments. RNA obtained from the isolated da neurons is of very high quality and can be directly used for downstream applications, including qRT-PCR or microarray analyses. Furthermore, this LCM protocol can be readily adapted to capture other Drosophila cell types a various stages of development dependent upon the cell type specific, GAL4-driven expression pattern of GFP.

Laser Capture Microdissection of Drosophila Peripheral Neurons

In this video-article we present a method for isolating single or multiple Drosophila da neurons from third instar larvae using the infrared capture (IR) class of Laser Capture Microdissection (LCM). RNA obtained from the isolated neurons can be readily used for downstream applications including qRT-PCR or microarray analyses.

The dendritic arborization (da) neurons of the Drosophila peripheral nervous system (PNS) provide an excellent model system in which to investigate the ...

Visualization of Larval Segmental Nerves in 3rd Instar Drosophila Larval Preparations

Drosophila melanogaster is emerging as a powerful model system for studying the development and function of the nervous system, particularly because of its convenient genetics and fully sequenced genome. Additionally, the larval nervous system is an ideal model system to study mechanisms of axonal transport as the larval segmental nerves contain bundles of axons with their cell bodies located within the brain and their nerve terminals ending along the length of the body. Here we describe the procedure for visualization of synaptic vesicle proteins within larval segmental nerves. If done correctly, all components of the nervous system, along with associated tissues such as muscles and NMJs, remain intact, undamaged, and ready to be visualized. 3rd instar larvae carrying various mutations are dissected, fixed, incubated with synaptic vesicle antibodies, visualized and compared to wild type larvae. This procedure can be adapted for several different synaptic or neuronal antibodies and changes in the distribution of a variety of proteins can be easily observed within larval segmental nerves.

Visualization of Larval Segmental Nerves in 3rd Instar Drosophila Larval Preparations

Drosophila melanogaster larvae provide an ideal model system to investigate the mechanisms of axonal transport within larval segmental nerves. Using this procedure, 3rd instar larvae carrying various mutations can be compared to wild type larvae.

Drosophila melanogaster is emerging as a powerful model system for studying the development and function of the nervous system, particularly because of ...

Morphological Analysis of Drosophila Larval Peripheral Sensory Neuron Dendrites and Axons Using Genetic Mosaics

Nervous system development requires the correct specification of neuron position and identity, followed by accurate neuron class-specific dendritic development and axonal wiring. Recently the dendritic arborization (DA) sensory neurons of the Drosophila larval peripheral nervous system (PNS) have become powerful genetic models in which to elucidate both general and class-specific mechanisms of neuron differentiation.
There are four main DA neuron classes (I-IV)1. They are named in order of increasing dendrite arbor complexity, and have class-specific differences in the genetic control of their differentiation2-10. The DA sensory system is a practical model to investigate the molecular mechanisms behind the control of dendritic morphology11-13 because: 1) it can take advantage of the powerful genetic tools available in the fruit fly, 2) the DA neuron dendrite arbor spreads out in only 2 dimensions beneath an optically clear larval cuticle making it easy to visualize with high resolution in vivo, 3) the class-specific diversity in dendritic morphology facilitates a comparative analysis to find key elements controlling the formation of simple vs. highly branched dendritic trees, and 4) dendritic arbor stereotypical shapes of different DA neurons facilitate morphometric statistical analyses.
DA neuron activity modifies the output of a larval locomotion central pattern generator14-16. The different DA neuron classes have distinct sensory modalities, and their activation elicits different behavioral responses14,16-20. Furthermore different classes send axonal projections stereotypically into the Drosophila larval central nervous system in the ventral nerve cord (VNC)21. These projections terminate with topographic representations of both DA neuron sensory modality and the position in the body wall of the dendritic field7,22,23. Hence examination of DA axonal projections can be used to elucidate mechanisms underlying topographic mapping7,22,23, as well as the wiring of a simple circuit modulating larval locomotion14-17.
We present here a practical guide to generate and analyze genetic mosaics24 marking DA neurons via MARCM (Mosaic Analysis with a Repressible Cell Marker)1,10,25 and Flp-out22,26,27 techniques (summarized in Fig. 1).

Morphological Analysis of Drosophila Larval Peripheral Sensory Neuron Dendrites and Axons Using Genetic Mosaics

The dendritic arborization sensory neurons of the Drosophila larval peripheral nervous system are useful models to elucidate both general and neuron class-specific mechanisms of neuron differentiation. We present a practical guide to generate and analyze dendritic arborization neuron genetic mosaics.

Nervous system development requires the correct specification of neuron position and identity, followed by accurate neuron class-specific dendritic ...

Methods to Assay Drosophila Behavior

Drosophila melanogaster, the fruit fly, has been used to study molecular mechanisms of a wide range of human diseases such as cancer, cardiovascular disease and various neurological diseases1. We have optimized simple and robust behavioral assays for determining larval locomotion, adult climbing ability (RING assay), and courtship behaviors of Drosophila. These behavioral assays are widely applicable for studying the role of genetic and environmental factors on fly behavior. Larval crawling ability can be reliably used for determining early stage changes in the crawling abilities of Drosophila larvae and also for examining effect of drugs or human disease genes (in transgenic flies) on their locomotion. The larval crawling assay becomes more applicable if expression or abolition of a gene causes lethality in pupal or adult stages, as these flies do not survive to adulthood where they otherwise could be assessed. This basic assay can also be used in conjunction with bright light or stress to examine additional behavioral responses in Drosophila larvae. Courtship behavior has been widely used to investigate genetic basis of sexual behavior, and can also be used to examine activity and coordination, as well as learning and memory. Drosophila courtship behavior involves the exchange of various sensory stimuli including visual, auditory, and chemosensory signals between males and females that lead to a complex series of well characterized motor behaviors culminating in successful copulation. Traditional adult climbing assays (negative geotaxis) are tedious, labor intensive, and time consuming, with significant variation between different trials2-4. The rapid iterative negative geotaxis (RING) assay5 has many advantages over more widely employed protocols, providing a reproducible, sensitive, and high throughput approach to quantify adult locomotor and negative geotaxis behaviors. In the RING assay, several genotypes or drug treatments can be tested simultaneously using large number of animals, with the high-throughput approach making it more amenable for screening experiments.

Methods to Assay Drosophila Behavior

Drosophila melanogaster is a genetically and behaviorally tractable model system that has been used to understand the molecular and cellular basis of many important biological processes for over a century 1. Drosophila has been well exploited to gain insights into the genetic basis of fly behavior.

Drosophila melanogaster, the fruit fly, has been used to study molecular mechanisms of a wide range of human diseases such as cancer, cardiovascular ...

Live Imaging of Drosophila Larval Neuroblasts

Stem cells divide asymmetrically to generate two progeny cells with unequal fate potential: a self-renewing stem cell and a differentiating cell. Given their relevance to development and disease, understanding the mechanisms that govern asymmetric stem cell division has been a robust area of study. Because they are genetically tractable and undergo successive rounds of cell division about once every hour, the stem cells of the Drosophila central nervous system, or neuroblasts, are indispensable models for the study of stem cell division. About 100 neural stem cells are located near the surface of each of the two larval brain lobes, making this model system particularly useful for live imaging microscopy studies. In this work, we review several approaches widely used to visualize stem cell divisions, and we address the relative advantages and disadvantages of those techniques that employ dissociated versus intact brain tissues. We also detail our simplified protocol used to explant whole brains from third instar larvae for live cell imaging and fixed analysis applications.

Live Imaging of Drosophila Larval Neuroblasts

This protocol details a streamlined method used to conduct live cell imaging in the context of an intact larval brain. Live cell imaging approaches are invaluable for the study of asymmetric neural stem cell divisions as well as other neurogenic and developmental processes, consistently uncovering mechanisms that were previously overlooked.

Stem cells divide asymmetrically to generate two progeny cells with unequal fate potential: a self-renewing stem cell and a differentiating cell. Given ...

A Simple Way to Measure Alterations in Reward-seeking Behavior Using Drosophila melanogaster

We describe a protocol for measuring ethanol self-administration in fruit flies (Drosophila melanogaster) as a proxy for changes in reward states. We demonstrate a simple way to tap into the fly reward system, modify experiences related to natural reward, and use voluntary ethanol consumption as a measure for changes in reward states. The approach serves as a relevant tool to study the neurons and genes that play a role in experience-mediated changes of internal state. The protocol is composed of two discrete parts: exposing the flies to rewarding and nonrewarding experiences, and assaying voluntary ethanol consumption as a measure of the motivation to obtain a drug reward. The two parts can be used independently to induce the modulation of experience as an initial step for further downstream assays or as an independent two-choice feeding assay, respectively. The protocol does not require a complicated setup and can therefore be applied in any laboratory with basic fly culture tools.

A Simple Way to Measure Alterations in Reward-seeking Behavior Using Drosophila melanogaster

We describe a protocol for inducing rewarding and nonrewarding experiences in fruit flies (Drosophila melanogaster) using voluntary ethanol consumption as a measure for changes in reward states.

We describe a protocol for measuring ethanol self-administration in fruit flies (Drosophila melanogaster) as a proxy for changes in reward states. We ...

Quantification of Drosophila Grooming Behavior

Drosophila grooming behavior is a complex multi-step locomotor program that requires coordinated movement of both forelegs and hindlegs. Here we present a grooming assay protocol and novel chamber design that is cost-efficient and scalable for either small or large-scale studies of Drosophila grooming. Flies are dusted all over their body with Brilliant Yellow dye and given time to remove the dye from their bodies within the chamber. Flies are then deposited in a set volume of ethanol to solubilize the dye. The relative spectral absorbance of dye-ethanol samples for groomed versus ungroomed animals are measured and recorded. The protocol yields quantitative data of dye accumulation for individual flies, which can be easily averaged and compared across samples. This allows experimental designs to easily evaluate grooming ability for mutant animal studies or circuit manipulations. This efficient procedure is both versatile and scalable. We show work-flow of the protocol and comparative data between WT animals and mutant animals for the Drosophila type I Dopamine Receptor (DopR).

This protocol describes a scalable individual grooming assay technique in Drosophila that yields robust, quantitative data to measure grooming behavior. The method is based on comparing the difference in dye accumulation on the bodies of un-groomed versus groomed animals over a set period of time.

Drosophila grooming behavior is a complex multi-step locomotor program that requires coordinated movement of both forelegs and hindlegs. Here we present a ...

Examining Monosynaptic Connections in Drosophila Using Tetrodotoxin Resistant Sodium Channels

Here, a new technique termed Tetrotoxin (TTX) Engineered Resistance for Probing Synapses (TERPS) is applied to test for monosynaptic connections between target neurons. The method relies on co-expression of a transgenic activator with the tetrodotoxin-resistant sodium channel, NaChBac, in a specific presynaptic neuron. Connections with putative post-synaptic partners are determined by whole-cell recordings in the presence of TTX, which blocks electrical activity in neurons that do not express NaChBac. This approach can be modified to work with any activator or calcium imaging as a reporter of connections. TERPS adds to the growing set of tools available for determining connectivity within networks. However, TERPS is unique in that it also reliably reports bulk or volume transmission and spillover transmission.

Examining Monosynaptic Connections in Drosophila Using Tetrodotoxin Resistant Sodium Channels

This article features a method to test the monosynaptic connections between neurons by employing tetrodotoxin and the tetrodotoxin-resistant sodium channel, NaChBac.

Here, a new technique termed Tetrotoxin (TTX) Engineered Resistance for Probing Synapses (TERPS) is applied to test for monosynaptic connections between ...

Tracking Drosophila Larval Behavior in Response to Optogenetic Stimulation of Olfactory Neurons

The ability of insects to navigate toward odor sources is based on the activities of their first-order olfactory receptor neurons (ORNs). While a considerable amount of information has been generated regarding ORN responses to odorants, the role of specific ORNs in driving behavioral responses remains poorly understood. Complications in behavior analyses arise due to different volatilities of odorants that activate individual ORNs, multiple ORNs activated by single odorants, and the difficulty in replicating naturally observed temporal variations in olfactory stimuli using conventional odor-delivery methods in the laboratory. Here, we describe a protocol that analyzes Drosophila larval behavior in response to simultaneous optogenetic stimulation of its ORNs. The optogenetic technology used here allows for specificity of ORN activation and precise control of temporal patterns of ORN activation. Corresponding larval movement is tracked, digitally recorded, and analyzed using custom written software. By replacing odor stimuli with light stimuli, this method allows for a more precise control of individual ORN activation in order to study its impact on larval behavior. Our method could be further extended to study the impact of second-order projection neurons (PNs) as well as local neurons (LNs) on larval behavior. This method will thus enable a comprehensive dissection of olfactory circuit function and complement studies on how olfactory neuron activities translate in to behavior responses.

Tracking Drosophila Larval Behavior in Response to Optogenetic Stimulation of Olfactory Neurons

This protocol analyzes navigational behavior of Drosophila larva in response to simultaneous optogenetic stimulation of its olfactory neurons. Light of 630 nm wavelength is used to activate individual olfactory neurons expressing a red-shifted channel rhodopsin. Larval movement is simultaneously tracked, digitally recorded, and analyzed using custom-written software.

The ability of insects to navigate toward odor sources is based on the activities of their first-order olfactory receptor neurons (ORNs). While a ...

Simultaneous Data Collection of fMRI and fNIRS Measurements Using a Whole-Head Optode Array and Short-Distance Channels

Functional near-infrared spectroscopy (fNIRS) is a portable neuroimaging methodology, more robust to motion and more cost-effective than functional magnetic resonance imaging (fMRI), which makes it highly suitable for conducting naturalistic studies of brain function and for use with developmental and clinical populations. Both fNIRS and fMRI methodologies detect changes in cerebral blood oxygenation during functional brain activation, and prior studies have shown high spatial and temporal correspondence between the two signals. There is, however, no quantitative comparison of the two signals collected simultaneously from the same subjects with whole-head fNIRS coverage. This comparison is necessary to comprehensively validate area-level activations and functional connectivity against the fMRI gold standard, which in turn has the potential to facilitate comparisons of the two signals across the lifespan. We address this gap by describing a protocol for simultaneous data collection of fMRI&#160;and fNIRS signals that: i) provides whole-head fNIRS coverage; ii) includes short-distance measurements for regression of the non-cortical, systemic physiological signal; and iii) implements two different methods for optode-to-scalp co-registration of fNIRS measurements. fMRI and fNIRS data from three subjects are presented, and recommendations for adapting the protocol to test developmental and clinical populations are discussed. The current setup with adults allows scanning sessions for an average of approximately 40 min, which includes both functional and structural scans. The protocol outlines the steps required to adapt the fNIRS equipment for use in the magnetic resonance (MR) environment, provides recommendations for both data recording and optode-to-scalp co-registration, and discusses potential modifications of the protocol to fit the specifics of the available MR-safe fNIRS system. Representative subject-specific responses from a flashing-checkerboard task illustrate the feasibility of the protocol to measure whole-head fNIRS signals in the MR environment. This protocol will be particularly relevant for researchers interested in validating fNIRS signals against fMRI across the lifespan.

We present a method for simultaneously collecting fMRI and fNIRS signals from the same subjects with whole-head fNIRS coverage. The protocol has been tested with three young adults and can be adapted for data collection for developmental studies and clinical populations.

Functional near-infrared spectroscopy (fNIRS) is a portable neuroimaging methodology, more robust to motion and more cost-effective than functional ...