Name: removal of drosophila muscle tissue from larval fillets for immunofluorescence analysis of sensory neurons and epidermal cells
Uploaded: 2016-11-02T13:00:00
Description: Watch this Scientific Journal Video about Removal of Drosophila Muscle Tissue from Larval Fillets for Immunofluorescence Analysis of Sensory Neurons and Epidermal Cells at JoVE.com

We thank Gary Laevsky for helpful discussions on microscopy. This work was funded by NIH grants R01GM061107 and R01GM067758 to E.R.G.

Note: The procedure for muscle removal (Figure 1) is a modification of previously described methods for preparing larval fillets. The steps that precede and follow muscle removal are outlined briefly and the reader is referred to previous work 10, 11 for more detailed descriptions.
1. Dissect Larva in Cold Saline
<ol>
	<li>Prepare a working dilution of cold HL3.1 saline15 or cold Ca2+-free HL3.1 saline11 (Table 1)....

<ol>
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(57), e3111 (2011).</li><li>Gustafsson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surpassing+the+lateral+resolution+limit+by+a+factor+of+two+using+structured+illumination+microscopy.">Surpassing the lateral resolution limit by a factor of two using structured illumination microscopy.</a> J Microscopy. 198 (2), 82-87 (2000).</li><li>Ashdown, G. W., Cope, A., Wiseman, P. W., Owen, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+flow+quantified+beyond+the+diffraction+limit+by+spatiotemporal+image+correlation+of+structured+illumination+microscopy+data.">Molecular flow quantified beyond the diffraction limit by spatiotemporal image correlation of structured illumination microscopy data.</a> Biophys J. 107 (9), L21-L23 (2014).</li><li>Zhang, W., Yan, Z., Jan, L. Y., Jan, Y. 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Here a protocol is described for manual removal of muscle tissue from Drosophila larval fillets. This protocol modifies previously described larval dissection techniques10,11. After the larva is dissected in a silicone elastomer dish, the dorsal midline is located. A single forceps prong, in its flattest possible orientation, is carefully inserted between the muscle tissue and the epidermis, near the dorsal midline. The forceps are gently pulled upwards to separate muscle tissue from one anchor point ...

Drosophila larval dendritic arborization (da) neurons provide a valuable model for studying neuronal development due to their amenability to genetic manipulation and the ease with which they can be imaged. These sensory neurons have been instrumental in the identification of numerous pathways that control dendrite morphogenesis1-3.
Four classes of da neurons (class I - IV) innervate the larval epidermis. These neurons lie between the basement membrane and the epidermis, with their dendrites forming largely two-dimensional arrays4,5. Of the four classes, class IV da neurons have the most highly branched arbors and, like sensory neurons of other animals, the elaboration of these arbors requires intrinsic factors as well as cues from neighboring tissues, particularly the epidermis, for their development6-9.
Studies to determine how such neuronal and extra-neuronal factors control dendrite morphogenesis benefit from the ability to detect protein expression in situ by immunofluorescence. The outer cuticle of the larva is impenetrable to antibodies, but this impediment is easily overcome by the preparation of larval fillets through well-established dissection methods10,11. However, the body wall muscle tissue that lies just interior to the basement membrane presents several challenges towards visualization of da neurons and epidermal cells. First, the muscle tissue, which lines most of the body wall, greatly obscures fluorescent signals emanating from neuronal or epidermal tissue. This substantially reduces the signal to noise ratio in the sample. Second, many relevant proteins may be expressed in the muscle tissue as well as in the neurons or epidermis. This muscle-derived fluorescence signal is likely to further obscure detection of a fluorescence signal from the neuron or epidermis. Finally, advances in microscopy technologies now permit imaging of samples at sub-diffraction resolution and may be especially helpful in discerning the localization of proteins that are expressed in neurons and surrounding epidermal cells12,13. However, imaging via super-resolution microscopy benefits from a strong signal to noise ratio and close proximity of the sample to the coverslip. In addition to reducing the signal to noise ratio, the larval body wall muscle distances da neurons from the coverslip, thereby limiting the improved image resolution that can be achieved with super-resolution microscopy methods. Besides challenges for immunofluorescence analysis, muscle tissue presents a barrier to electrophysiological recording from sensory neurons in the larval body wall. Its removal therefore benefits neurophysiological manipulation of sensory neurons14.
Here a method for manual removal of Drosophila larval muscle tissue is described. We demonstrate that our protocol permits immunofluorescence imaging of proteins that are otherwise obscured by muscle tissue, improves the signal to noise ratio for visualization of class IV da neurons, and enables the use of super-resolution microscopy to better discriminate spatial relationships of proteins and cellular structures in da neurons and the epidermis.

<table border="0" cellpadding="0" cellspacing="0" width="1299">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:413px;">Dumont #5 tweezers</td>
			<td style="width:304px;">Electron Microscopy Sciences</td>
			<td style="width:151px;">72701-D</td>
			<td style="width:432px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Micro Scissors, 8 cm, straight, 5 mm blades, 0.1 mm tips</td>
			<td>World Precision Instruments</td>
			<td>14003</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sylgard 184 silicone elastomer kit</td>
			<td>Dow Corning</td>
			<td>3097358-1004</td>
			<td>for dissecting plates</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Austerlitz insect pins, 0.1 mm</td>
			<td>Fine Science Tools</td>
			<td>26002-10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fostec 8375 light source</td>
			<td>Artisan Technology Group</td>
			<td>62792-4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Zeiss Stemi 2000</td>
			<td>Carl Zeiss Microscopy</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vectashield antifade mounting medium</td>
			<td>Vector Laboratories</td>
			<td>H-1000</td>
			<td>for confocal microscopy</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Prolong Diamond antifade mountant</td>
			<td>Life Technologies</td>
			<td>P36970</td>
			<td>for structured illumination microscopy</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Micro cover glass, 22x22 mm, No. 1.5</td>
			<td>VWR</td>
			<td>48366-227</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Superfrost Plus microscope slides, 25 x 75 x 1.0 mm</td>
			<td>Fisherbrand</td>
			<td>12-550-15</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse anti-Coracle antibody</td>
			<td>Developmental Studies Hybridoma Bank</td>
			<td>C615.16</td>
			<td>supernatant, dilute 1:50</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse anti-Discs large antibody</td>
			<td>Developmental Studies Hybridoma Bank</td>
			<td>4F3</td>
			<td>supernatant, dilute 1:50</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Rabbit anti-dsRed antibody</td>
			<td>Clontech</td>
			<td>632496</td>
			<td>dilute 1:1000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Goat anti-rabbit antibody, Alexa Fluor 568 conjugated</td>
			<td>ThermoFisher Scientific</td>
			<td>A-11011</td>
			<td>dilute 1:1000</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Goat anti-mouse antibody, Alexa Fluor 488 conjugated</td>
			<td>ThermoFisher Scientific</td>
			<td>A-11001</td>
			<td>dilute 1:500</td>
		</tr>
	</tbody>
</table>

removal of drosophila muscle tissue from larval fillets for immunofluorescence analysis of sensory neurons and epidermal cells

Drosophila larval dendritic arborization (da) neurons are a popular model for investigating mechanisms of neuronal morphogenesis. Da neurons develop in communication with the epidermal cells they innervate and thus their analysis benefits from in situ visualization of both neuronally and epidermally expressed proteins by immunofluorescence. Traditional methods of preparing larval fillets for immunofluorescence experiments leave intact the muscle tissue that covers most of the body wall, presenting several challenges to imaging neuronal and epidermal proteins. Here we describe a method for removing muscle tissue from Drosophila larval fillets. This protocol enables imaging of proteins that are otherwise obscured by muscle tissue, improves signal to noise ratio, and facilitates the use of super-resolution microscopy to study da neuron development.

We demonstrate the utility of the muscle removal procedure for improving signal to noise ratio in immunofluorescence experiments to co-visualize the septate junction proteins Coracle (Cora) and Discs-large (Dlg) together with class IV da neurons labeled with the membrane marker CD4-tdTomato.
Cora has been previously used to identify tracts where da neuron dendrites are enclosed by epidermal cells and is one of many identified epidermal factors that have been st...

Watch this Scientific Journal Video about Removal of Drosophila Muscle Tissue from Larval Fillets for Immunofluorescence Analysis of Sensory Neurons and Epidermal Cells at JoVE.com

Removal of Drosophila Muscle Tissue from Larval Fillets for Immunofluorescence Analysis of Sensory Neurons and Epidermal Cells

Studies of neuronal morphogenesis using Drosophila larval dendritic arborization (da) neurons benefit from in situ visualization of neuronal and epidermal proteins by immunofluorescence. We describe a procedure that improves immunofluorescence analysis of da neurons and surrounding epidermal cells by removing muscle tissue from the larval body wall.

Removal of Drosophila Muscle Tissue from Larval Fillets for Immunofluorescence Analysis of Sensory Neurons and Epidermal Cells

Drosophila larval dendritic arborization (da) neurons are a popular model for investigating mechanisms of neuronal morphogenesis. Da neurons develop in ...

The overall goal of this procedure is to remove muscle tissue from a drosophila larva in preparation for immunofluorescence analysis of larval dendritic arborization or da neurons and epidermal tissue. Today, we are going to demonstrate a method that improves visualization of neuronal and extra neuronal factors involved in dendrite morphogenesis. The main advantage of this technique is that it permits immunofluorescence imaging of proteins, that are otherwise obscured by muscle tissue, improve signal to noise ratio, and enables the use of super resolution microscopy.To begin, add enough cold saline to a silicone elastomer dish to cover the bottom surface. Add the subject larva to the dish and place it under the stereo microscope. Ensuring proper placement of light.Position the larva with the ventral side up, which can be identified by the abdominal denticle belts. Stretch the larva in the anterior posterior direction, and using insect pins, pin the head and tail to the bottom of the dish. With a pair of fine dissecting scissors, cut along the ventral midline of the larva from one end to the other.Spread the larva open and pin the cuticle tissue at the four corners so that it lies flat. Using forceps, remove the internal organs, including the CNS, gut, and trachea. Adjust the insect pins so that the filet is taught but not maximally stretched.Locate the dorsal midline of the larva, where muscle tissue is absent, and then position a forceps prong at the interior of this boundary. Slide the prong between the muscle and epidermis, taking care to minimize contact with the epidermis To minimize damage to the epidermis, dissect with the flattest possible prongs, and try dissecting in calcium containing saline. That could help create space between the muscle and the epidermis.Next, pull the forceps upwards to break the attachment of the muscle to the body wall at one anchor point. Repeat this process for the remaining muscle segments of interest. Readjust the insect pins to maximally stretch the larval fillets in all directions.To fix the filet, first remove the saline solution, and then add cold freshly prepared 4%formaldehyde in PBS, to cover the bottom of the dish. Incubate at room temperature for 25 minutes. Rinse the filet five times in PBS to remove excess formaldehyde.Next, use forceps to carefully pull away the muscle tissue from the remaining anchor points. Again, minimizing contact with the epidermis. Finally, unpin the filet and remove it from the dissecting dish.Place it into a clean 1.5 milliliter microcentrifuge tube. Further washing, blocking and immunostaining should be carried out in this tube. To mount the filet for imaging, remove the sample from the microcentrifuge tube and orient it inner surface down onto a cover slip in a drop of PBS.Cut off the head and tail. And then remove the PBS by absorbing it with a laboratory wipe. Add one drop of Antifade Mountant.Place a microscope slide onto the cover slip, and then press gently using a laboratory wipe to disperse the mounting medium. Flip the side over and apply clear nail polish at each edge to seal the cover slip. These confocal images show immunofluorescence experiments to visualize the septate junction protein, Coracle, or Cora, and da neurons.Here, images of muscle removed and muscle intact tissues were taken under the same laser power conditions. In muscle intact tissue, laser power was increased to compensate for muscle interference, and produce a comparable image. In images obtained from muscle removed fillets, cora could be clearly detected at epidermal cell boundaries in intermittent tracks along class four da neuron dendrites.And outlining the neuron, soma. In contrast, cora localization at these domains was barely detectable in muscle on samples. Here, cora was largely visualized in the muscle, trachea, and neuromuscular junctions, and fluorescence from these tissues obscured most epidermal cora.Samples were also imaged using 3D structured illumination microscopy to determine whether muscle removal improved visualization at higher resolution. Again, the muscle intact samples needed visualization with increased power and exposure time to compensate for muscle interference. Image resolution appeared sharper in muscle off samples, fewer artifacts were observed, and cora staining of dendrite tracks was more readily resolved.Dendrite membranes could also be measured at 114 nanometers in the muscle off condition. Whereas they appear to be 272 nanometers wide in muscle on filets. While performing this procedure, it's important to limit the number of larva dissected prior to fixation, so that the elapsed time is no more than 25 minutes.After watching this video, you should have a good understanding of how to remove muscle tissue from a drosophila larva. This protocol will assist with immunofluorescence analysis of larval sensory neurons and the epidermal cells they innovate. Thanks for watching and good luck with your experiments.

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Neuroscience

Live-imaging of PKC Translocation in Sf9 Cells and in Aplysia Sensory Neurons

Protein kinase Cs (PKCs) are serine threonine kinases that play a central role in regulating a wide variety of cellular processes such as cell growth and learning and memory. There are four known families of PKC isoforms in vertebrates: classical PKCs (&alpha;, &beta;I, &beta;II and &gamma;), novel type I PKCs (&#949; and &eta;), novel type II PKCs (&delta; and &theta;), and atypical PKCs (&zeta; and &iota;). The classical PKCs are activated by Ca2+ and diacylclycerol (DAG), while the novel PKCs are activated by DAG, but are Ca2+-independent. The atypical PKCs are activated by neither Ca2+ nor DAG. In Aplysia californica, our model system to study memory formation, there are three nervous system specific PKC isoforms one from each major class, namely the conventional PKC Apl I, the novel type I PKC Apl II and the atypical PKC Apl III. PKCs are lipid-activated kinases and thus activation of classical and novel PKCs in response to extracellular signals has been frequently correlated with PKC translocation from the cytoplasm to the plasma membrane. Therefore, visualizing PKC translocation in real time in live cells has become an invaluable tool for elucidating the signal transduction pathways that lead to PKC activation. For instance, this technique has allowed for us to establish that different isoforms of PKC translocate under different conditions to mediate distinct types of synaptic plasticity and that serotonin (5HT) activation of PKC Apl II requires production of both DAG and phosphatidic acid (PA) for translocation 1-2. Importantly, the ability to visualize the same neuron repeatedly has allowed us, for example, to measure desensitization of the PKC response in exquisite detail 3. In this video, we demonstrate each step of preparing Sf9 cell cultures, cultures of Aplysia sensory neurons have been described in another video article 4, expressing fluorescently tagged PKCs in Sf9 cells and in Aplysia sensory neurons and live-imaging of PKC translocation in response to different activators using laser-scanning microscopy.

In this video, we demonstrate visualization of PKC translocation in living cells using fluorescently tagged PKCs.

Protein kinase Cs (PKCs) are serine threonine kinases that play a central role in regulating a wide variety of cellular processes such as cell growth and ...

Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae

Since the discovery of Green Fluorescent Protein (GFP), there has been a revolutionary change in the use of live-cell imaging as a tool for understanding fundamental biological mechanisms. Striking progress has been particularly evident in Drosophila, whose extensive toolkit of mutants and transgenic lines provides a convenient model to study evolutionarily-conserved developmental and cell biological mechanisms. We are interested in understanding the mechanisms that control cell fate specification in the adult peripheral nervous system (PNS) in Drosophila. Bristles that cover the head, thorax, abdomen, legs and wings of the adult fly are individual mechanosensory organs, and have been studied as a model system for understanding mechanisms of Notch-dependent cell fate decisions. Sensory organ precursor (SOP) cells of the microchaetes (or small bristles), are distributed throughout the epithelium of the pupal thorax, and are specified during the first 12 hours after the onset of pupariation. After specification, the SOP cells begin to divide, segregating the cell fate determinant Numb to one daughter cell during mitosis. Numb functions as a cell-autonomous inhibitor of the Notch signaling pathway.
Here, we show a method to follow protein dynamics in SOP cell and its progeny within the intact pupal thorax using a combination of tissue-specific Gal4 drivers and GFP-tagged fusion proteins 1,2.This technique has the advantage over fixed tissue or cultured explants because it allows us to follow the entire development of an organ from specification of the neural precursor to growth and terminal differentiation of the organ. We can therefore directly correlate changes in cell behavior to changes in terminal differentiation. Moreover, we can combine the live imaging technique with mosaic analysis with a repressible cell marker (MARCM) system to assess the dynamics of tagged proteins in mitotic SOPs under mutant or wildtype conditions. Using this technique, we and others have revealed novel insights into regulation of asymmetric cell division and the control of Notch signaling activation in SOP cells (examples include references 1-6,7 ,8).

Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae

In this video, we describe a method for live cell imaging of asymmetrically dividing sensory organ progenitor cells and epidermal cells in intact Drosophila pupae

Since the discovery of Green Fluorescent Protein (GFP), there has been a revolutionary change in the use of live-cell imaging as a tool for understanding ...

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 ...

Functional Analysis of the Larval Feeding Circuit in Drosophila

The serotonergic feeding circuit in Drosophila melanogaster larvae can be used to investigate neuronal substrates of critical importance during the development of the circuit. Using the functional output of the circuit, feeding, changes in the neuronal architecture of the stomatogastric system can be visualized. Feeding behavior can be recorded by observing the rate of retraction of the mouth hooks, which receive innervation from the brain. Locomotor behavior is used as a physiological control for feeding, since larvae use their mouth hooks to traverse across an agar substrate. Changes in feeding behavior can be correlated with the axonal architecture of the neurites innervating the gut. Using immunohistochemistry it is possible to visualize and quantitate these changes. Improper handling of the larvae during behavior paradigms can alter data as they are very sensitive to manipulations. Proper imaging of the neurite architecture innervating the gut is critical for precise quantitation of number and size of varicosities as well as the extent of branch nodes. Analysis of most circuits allow only for visualization of neurite architecture or behavioral effects; however, this model allows one to correlate the functional output of the circuit with the impairments in neuronal architecture.

Functional Analysis of the Larval Feeding Circuit in Drosophila

The feeding circuit in Drosophila melanogaster larvae serves a simple yet powerful model that allows changes in feeding rate to be correlated with alterations in the stomatogastric neural circuitry. This circuit is composed of central serotonergic neurons that send projections to the mouth hooks as well as the foregut.

The serotonergic  feeding circuit in Drosophila  melanogaster larvae can be used to investigate neuronal substrates of  critical importance during the ...

Whole Mount Immunolabeling of Olfactory Receptor Neurons in the Drosophila Antenna

Odorant molecules bind to their target receptors in a precise and coordinated manner. Each receptor recognizes a specific signal and relays this information to the brain. As such, determining how olfactory information is transferred to the brain, modifying both perception and behavior, merits investigation. Interestingly, there is emerging evidence that cellular transduction and transcriptional factors are involved in the diversification of olfactory receptor neuron. Here we provide a robust whole mount immunological labeling method to assay in vivo olfactory receptor neuron organization. Using this method, we identified all olfactory receptor neurons with anti-ELAV antibody, a known pan-neural marker and Or49a-mCD8::GFP, an olfactory receptor neuron specifically expressed in Nba neuron using anti-GFP antibody.

Whole Mount Immunolabeling of Olfactory Receptor Neurons in the Drosophila Antenna

Herein we describe the process of whole mount immunostaining of Drosophila antennae, which enables us to better understand the molecular mechanisms involved in the diversification of olfactory receptor neurons (ORN)s.

Odorant molecules bind to their target receptors in a precise and coordinated manner. Each receptor recognizes a specific signal and relays this ...

Production and Isolation of Axons from Sensory Neurons for Biochemical Analysis Using Porous Filters

Neuronal axons use specific mechanisms to mediate extension, maintain integrity, and induce degeneration. An appropriate balance of these events is required to shape functional neuronal circuits. The protocol described here explains how to use cell culture inserts bearing a porous membrane (filter) to obtain large amounts of pure axonal preparations suitable for examination by conventional biochemical or immunocytochemical techniques. The functionality of these filter inserts will be demonstrated with models of developmental pruning and Wallerian degeneration, using explants of embryonic dorsal root ganglion. Axonal integrity and function is compromised in a wide variety of neurodegenerative pathologies. Indeed, it is now clear that axonal dysfunction appears much earlier in the course of the disease than neuronal soma loss in several neurodegenerative diseases, indicating that axonal-specific processes are primarily targeted in these disorders. By obtaining pure axonal samples for analysis by molecular and biochemical techniques, this technique has the potential to shed new light into mechanisms regulating the physiology and pathophysiology of axons. This in turn will have an impact in our understanding of the processes that drive degenerative diseases of the nervous system.

This article describes a neuronal culture system that can be used to obtain large quantities of pure axonal samples for biochemical and immunocytochemical analyses. This technique will allow an improved understanding of normal axonal physiology and signaling pathways leading to neurodegeneration.

Neuronal axons use specific mechanisms to mediate extension, maintain integrity, and induce degeneration. An appropriate balance of these events is ...

Isolation and Culture of Dissociated Sensory Neurons From Chick Embryos

Neurons are multifaceted cells that carry information essential for a variety of functions including sensation, motor movement, learning, and memory. Studying neurons in vivo can be challenging due to their complexity, their varied and dynamic environments, and technical limitations. For these reasons, studying neurons in vitro can prove beneficial to unravel the complex mysteries of neurons. The well-defined nature of cell culture models provides detailed control over environmental conditions and variables. Here we describe how to isolate, dissociate, and culture primary neurons from chick embryos. This technique is rapid, inexpensive, and generates robustly growing sensory neurons. The procedure consistently produces cultures that are highly enriched for neurons and has very few non-neuronal cells (less than 5%). Primary neurons do not adhere well to untreated glass or tissue culture plastic, therefore detailed procedures to create two distinct, well-defined laminin-containing substrata for neuronal plating are described. Cultured neurons are highly amenable to multiple cellular and molecular techniques, including co-immunoprecipitation, live cell imagining, RNAi, and immunocytochemistry. Procedures for double immunocytochemistry on these cultured neurons have been optimized and described here.

Cell culture models provide detailed control over environmental conditions and thus provide a powerful platform to elucidate numerous aspects of neuronal cell biology. We describe a rapid, inexpensive, and reliable method to isolate, dissociate, and culture sensory neurons from chick embryos. Details of substrata preparation and immunocytochemistry are also provided.

Neurons are multifaceted cells that carry information essential for a variety of functions including sensation, motor movement, learning, and memory. ...

Physiological Preparation of Hair Cells from the Sacculus of the American Bullfrog (Rana catesbeiana)

The study of hearing and balance rests upon insights drawn from biophysical studies of model systems. One such model, the sacculus of the American bullfrog, has become a mainstay of auditory and vestibular research. Studies of this organ have revealed how sensory cells hair can actively detect signals from the environment. Because of these studies, we now better understand the mechanical gating and localization of a hair cell&#39;s transduction channels, calcium&#39;s role in mechanical adaptation, and the identity of hair cell currents. This highly accessible organ continues to provide insight into the workings of hair cells. Here we describe the preparation of the bullfrog&#39;s sacculus for biophysical studies on its hair cells. We include the complete dissection procedure and provide specific protocols for the preparation of the sacculus in specific contexts. We additionally include representative results using this preparation, including the calculation of a hair bundle&#39;s instantaneous force-displacement relation and measurement of a bundle&#39;s spontaneous oscillation.

Physiological Preparation of Hair Cells from the Sacculus of the American Bullfrog Rana catesbeiana

The American bullfrog&#39;s (Rana catesbeiana) sacculus permits direct examination of hair-cell physiology. Here the dissection and preparation of the bullfrog&#39;s sacculus for biophysical studies is described. We show representative experiments from these hair cells, including the calculation of a bundle&#39;s force-displacement relation and measurement of its unforced motion.

The study of hearing and balance rests upon insights drawn from biophysical studies of model systems. One such model, the sacculus of the American ...

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 ...

Isolation and RNA Extraction of Neurons, Macrophages and Microglia from Larval Zebrafish Brains

To gain a detailed understanding of the role of different CNS cells during development or the establishment and progression of brain pathologies, it is important to isolate these cells without changing their gene expression profile. The zebrafish model provides a large number of transgenic fish lines in which specific cell types are labelled; for example neurons in the NBT:DsRed line or macrophages/microglia in the mpeg1:eGFP line. Furthermore, antibodies have been developed to stain specific cells, such as microglia with the 4C4 antibody.
Here, we describe the isolation of neurons, macrophages and microglia from larval zebrafish brains. Central to this protocol is the avoidance of an enzymatic tissue digestion at 37 &#176;C, which could modify cellular profiles. Instead a mechanical system of tissue homogenization at 4 &#176;C is used. This protocol entails homogenization of brains into cell suspension, their immuno-staining and the isolation of neurons, macrophages and microglia by FACS. Afterwards, we extracted RNA from those cells and evaluated their quality/quantity. We managed to obtain RNA of high quality (RNA Integrity Number (RIN) &#62; 7) to perform qPCR on macrophages/microglia and neurons, and transcriptomic analysis on microglia. This approach enables a better characterization of these cells, as well as a clearer understanding about their role in development and pathologies.

We present a protocol to isolate neurons, macrophages and microglia from larval zebrafish brains under physiological and pathological conditions. Upon isolation, RNA is extracted from these cells to analyze their gene expression profile. This protocol allows for the collection of high-quality RNA for performing downstream analysis like qPCR and transcriptomics.

To gain a detailed understanding of the role of different CNS cells during development or the establishment and progression of brain pathologies, it is ...