The authors thank S.I. Bernstein (San Diego State University) for critical reading and helpful suggestions regarding the preparation of this manuscript. This work was supported by NIH grants to S.I. Bernstein, SDSU, and to R. Bodmer, BIMR; and by a post-doctoral fellowship from the Western States Affiliate of the American Heart Association to G. Vogler and to A. Cammarato.

Before you start
<ol>
 <li>Prepare the following solutions: 
 <ol class="lalpha">
 <li>relaxing buffer (artificial Drosophila hemolymph (ADH) (see &#x201C;Visualizing the beating heart in Drosophila&#x201D;) that contains 10 mM EGTA) </li>
 <li>fixative (4% formaldehyde in 1x PBS)</li>
 <li>PBSTx (PBS containing 0.1% Triton-X-100)</li>
 <li>Appropriately diluted primary and species-specific fluorescently labeled secondary antibodies in PBSTx</li>
 </ol></li>
 <li>Dissect Drosophila to expose the cardiac tubes (of adult flies and/or larvae) following
 <ol class="lalpha">
 <li>the semi-intact Drosophila heart preparation protocol in "Visualizing the beating heart in Drosophila", or </li>
 <li>Drosophila Larval NMJ Dissection protocol1 with the following modifications: Use oxygenated ADH during larval dissection and displace the posterior pin slightly from the ventral midline. Larvae are cut along the ventral midline. Do not remove any tissue prior to fixation.</li>
 </ol>
 </li>
</ol>
Fluorescent Staining
<ol>
 <li>Check that all hearts are rhythmically beating in oxygenated ADH. Quickly replace ADH with relaxing buffer. Examine each cardiac tube to ensure contractions are inhibited. </li>
 <li>Fix the hearts by replacing the relaxing buffer with fixative. Incubate at room temperature for 20 minutes with gentle shaking. (For larval preparation shaking is not necessary at any step, and may be considered detrimental to cardiac tissue integrity).</li>
 <li>Wash specimens three times for ten minutes with PBSTx at room temperature with continual shaking. </li>
 <li>For adults, carefully trim back the ventral edges of the abdominal cuticle such that what remains is more elliptical and less rounded. Additionally, with a single cut between the abdomen and thorax, carefully and cleanly separate both body segments and ensure minimal damage to the anterior region of the heart. For larval hearts, carefully remove the fat body using fine forceps. The fat removal must be executed with extreme caution, since the larval heart is especially fragile and has very little support from other muscles or connective tissue. Do not remove the tracheal branches as this may damage the heart. </li>
 <li>Transfer the trimmed dorsal region of the abdominal cuticle by the edges, avoiding contact with the centrally located cardiac tube, into a 96 well plate with wells that contain 50-100 &mu;l of primary antibody diluted in PBSTx. Place no more than 12 specimens per well. Incubate at room temperature for 2 hours with continual agitation. Incubation may also be done overnight at 4&deg; C. </li>
 <li>Remove primary antibody solution. Wash the hearts three times for ten minutes with 100 &mu;l PBSTx at room temperature with continual shaking. </li>
 <li>Following removal of final wash buffer, add 100 &mu;l of secondary antibody in PBSTx, supplemented with Alexa594-phalloidin (1:1000). Incubate for one hour with continual shaking at room temperature. Keep samples covered to prevent fluorophore bleaching. </li>
 <li>Following secondary incubation, wash the hearts three times for ten minutes with 100 &mu;l of PBSTx at room temperature with continual shaking. Keep the samples covered throughout the washing steps. </li>
 <li>For removal of Triton-X-100, rinse the hearts a final time in 100 &mu;l of PBS for 10 minutes. The specimens can be stored in the dark at 4&deg;C for several days before mounting. </li>
</ol>
Mounting for Adult Hearts
<ol>
 <li>Adhere two 18 x 18 mm cover slips to a microscope slide with 10 &mu;l of Vectashield mounting medium. The coverslips should be spaced ~10-15 mm apart. Place a small third drop of mounting medium in-between the two coverslips.</li>
 <li>Place 20 &mu;l of Vectashield in the center of a third coverslip. </li>
 <li>Carefully remove each of the hearts from the PBS wash solution by the extreme edges of the cuticle, and gently place them heart-side down onto the drop of mounting medium on the third coverslip. Place no more than five hearts per drop on the coverslip. </li>
 <li>Check under a microscope to ensure all hearts are facing down. </li>
 <li>Carefully invert the coverslip containing the hearts and quickly place it on the slide containing the pair of coverslips such that the droplet with cardiac tubes fuses with the Vectashield droplet between the coverslip pair. A &#x201C;bridge&#x201D; should be formed by the coverslips. The hearts will be suspended between a coverslip and the microscope slide. </li>
 <li>Check under a microscope to ensure that hearts are now facing upward. </li>
 <li>Fix coverslips at their edges with nail polish. </li>
 <li>The hearts are now ready to be imaged via fluorescent or confocal microscopy. </li>
</ol>
Mounting for Larval Hearts
<ol>
 <li>Place a drop (~20 &mu;l) Vectashield on a microscope slide.</li>
 <li>Carefully transfer up to two larval specimens into the Vectashield and orient them dorsal side down using tungsten needles. </li>
 <li>Individually drag the specimens out of the mounting medium and align each in parallel.</li>
 <li>Place a coverslip on opposing sides of the specimen. Using forceps, place a third coverslip on top, first by laying one side on the posterior coverslip and lowering it down to the anterior coverslip thus forming a bridge. Capillary forces will cause a flow of Vectashield from posterior to anterior which helps proper alignment of the larval heart.</li>
 <li>Fix all coverslips in place, at their edges, with nail polish and carefully fill the space between the coverslips with 20-30 &mu;l Vectashield. </li>
 <li>Seal with nail polish and store at 4&deg;C, or for long-term storage at -20&deg;C.</li>
</ol>
Representative Results
When executed correctly, all components and associated tissues of the dorsal vessel should remain intact and be readily visualized. The background fluorescence should be minimal. For adults, the ventral longitudinal muscle layer stains very well and produces a substantial signal (Figure 1 and Figure 2). The underlying circular cardiomyocytes however, tend not to produce as intense a signal as that of the overlying ventral layer. The myocytes of the anterior &#x201C;conical chamber&#x201D; of the adult heart contain a substantial amount of contractile material and, consequently, this region appears as the most robust relative to the remainder of the cardiac tube. The larval heart shows a spiraling myofibrillar arrangement similar to that of the adult contractile cardiomyocytes (Figure 3).
<img src="/files/ftp_upload/1423/1423fig1atmb.jpg" alt="Figure 1a" border="0" /> <img src="/files/ftp_upload/1423/1423fig1btmb.jpg" border="0" alt="Figure 1b" /> Figure 1: Top. A fluorescent micrograph showing the entire cardiac tube of an adult Drosophila melanogaster that expresses myosin-GFP. The image was taken with a Zeiss Imager Z1 fluorescent microscope equipped with an Apotome sliding module. Myosin-GFP is shown in green, actin is stained with AlexaFluor&reg; 594 phalloidin (red) and &alpha;-actinin is labeled with anti-&alpha;-actinin antibody (blue). Note the preparative procedure permits recovery of heart samples with well-preserved structures. CC = conical chamber; AM = alary muscle; V = internal valve; VLL = ventral longitudinal muscle layer. Bottom. A region of the adult cardiac tube from the CC through the 3rd abdominal segment of the heart just beneath the ventral longitudinal layer showing the spiraling myofibril arrangement of the contractile cardiomyocytes. Please <a href="https://www.jove.com/files/ftp_upload/1423/1423fig1a.jpg">click here</a> for a larger version of Figure 1a, and <a href="https://www.jove.com/files/ftp_upload/1423/1423fig1b.jpg">here</a> for a larger version of figure 1b
<img border="0" src="/files/ftp_upload/1423/1423fig2tmb.jpg" alt="Figure 2" /> Figure 2: Representative confocal stacks of an anterior portion of the adult heart stained with AlexaFluor&reg; 594 phalloidin (red) and an anti-Pericardin (collagen type IV) (green) antibody. Pericardin is associated with the heart along the ventral surface, likely originating from the longitudinally oriented myofibrils of the ventral muscle layer. Please <a href="https://www.jove.com/files/ftp_upload/1423/1423fig2.jpg">click here</a> for a larger version of figure 2.
<img border="0" src="/files/ftp_upload/1423/1423fig3tmb.jpg" alt="Figure 3" /> Figure 3: A fluorescent micrograph of segment A7 of the heart proper of a stage three Drosophila larva. The image was taken with a Zeiss Imager Z1 fluorescent microscope equipped with an Apotome sliding module. Actin is labeled with AlexaFluor&reg; 594 phalloidin (green) and &alpha;-actinin is stained with anti-&alpha;-actinin antibody (red). Please <a href="https://www.jove.com/files/ftp_upload/1423/1423fig3.jpg">click here</a> for a larger version of figure 3.

<ol>
	<li>Brent, J. R., Werner, K. M., McCabe, B. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drosophila+larval+NMJ+dissection.">Drosophila larval NMJ dissection.</a> J Vis Exp. , (2009).</li><li>Molina, M. R., Cripps, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ostia,+the+inflow+tracts+of+the+Drosophila+heart,+develop+from+a+genetically+distinct+subset+of+cardial+cells.">Ostia, the inflow tracts of the Drosophila heart, develop from a genetically distinct subset of cardial cells.</a> Mech Dev. 1, 51-59 (2001).</li><li>Dulcis, D., Levine, R. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glutamatergic+innervation+of+the+heart+initiates+retrograde+contractions+in+adult+Drosophila+melanogaster.">Glutamatergic innervation of the heart initiates retrograde contractions in adult Drosophila melanogaster.</a> J Neurosci. 2, 271-280 (2005).</li><li>Zeitouni, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Signalling+pathways+involved+in+adult+heart+formation+revealed+by+gene+expression+profiling+in+Drosophila.">Signalling pathways involved in adult heart formation revealed by gene expression profiling in Drosophila.</a> PLoS Genet. 10, 1907-1921 (2007).</li><li>Robertson, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+metamorphosis+of+Drosophila+melanogaster,+including+an+accurately+timed+account+of+the+principal+morphological+change.">The metamorphosis of Drosophila melanogaster, including an accurately timed account of the principal morphological change.</a> J. Morphol. 2, 351-399 (1936).</li><li>Miller, A. <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 internal anatomy and histology of the imago of Drosophila melanogaster. , (1950).</li><li>Rizki, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+circulatory+system+and+associated+cells+and+tissues.">The circulatory system and associated cells and tissues.</a> , (1978).</li><li>Cammarato, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myosin+transducer+mutations+differentially+affect+motor+function,+myofibril+structure,+and+the+performance+of+skeletal+and+cardiac+muscles.">Myosin transducer mutations differentially affect motor function, myofibril structure, and the performance of skeletal and cardiac muscles.</a> Mol Biol Cell. 2, 553-562 (2008).</li><li>Taghli-Lamallem, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dystrophin+deficiency+in+Drosophila+reduces+lifespan+and+causes+a+dilated+cardiomyopathy+phenotype.">Dystrophin deficiency in Drosophila reduces lifespan and causes a dilated cardiomyopathy phenotype.</a> Aging Cell. 2, 237-249 (2008).</li><li>Kelso, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=a+database+documenting+a+GFP+protein-trap+insertion+screen+in+Drosophila+melanogaster.">a database documenting a GFP protein-trap insertion screen in Drosophila melanogaster.</a> Nucleic Acids Res. 32, D418-D420 (2004).</li><li>Dietzl, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+genome-wide+transgenic+RNAi+library+for+conditional+gene+inactivation+in+Drosophila.">A genome-wide transgenic RNAi library for conditional gene inactivation in Drosophila.</a> Nature. 7150, 151-156 (2007).</li><li>Mery, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Drosophila+muscle+LIM+protein,+Mlp84B,+is+essential+for+cardiac+function.">The Drosophila muscle LIM protein, Mlp84B, is essential for cardiac function.</a> J Exp Biol. 211, 15-23 (2008).</li></ol>

Here we present a protocol useful for preparing and staining the Drosophila melanogaster dorsal vessel and associated tissues for imaging via fluorescent or confocal microscopy. We provide a concise account of the steps refined by and commonly employed in our lab for effective staining that permits well-resolved in situ imaging of larval and adult Drosophila heart tubes. Others have described similar methods in abbreviated form2, 3, 4.
Important additiona...

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Ethylene glycol-bis (2-amino-ethylether) -N,N,N&#x2019;,N&#x2019;-tetra-acetic acid (EGTA)</td>
<td>Reagent</td>
<td>Sigma-Aldrich&reg;</td>
<td>E4378</td>
<td>&nbsp;</td>
<tr>
<td>Formaldehyde, 10%, methanol free, Ultra Pure</td>
<td>Reagent</td>
<td>Polysciences Inc.</td>
<td>50-00-0</td>
<td>&nbsp;</td>
<tr>
<td>Triton-X-100</td>
<td>Reagent</td>
<td>Sigma-Aldrich&reg;</td>
<td>9002-93-1</td>
<td>&nbsp;</td>
<tr>
<td>Alexa Fluor&reg; 594 phalloidin</td>
<td>Reagent</td>
<td>Invitrogen&trade;</td>
<td>A12381</td>
<td>&nbsp;</td>
<tr>
<td>Vectashield&reg; Mounting Medium for Fluorescence with DAPI</td>
<td>Reagent</td>
<td>Vector Laboratories, Inc.</td>
<td>H-1200</td>
<td>&nbsp;</td>
<tr>
<td>Tungsten pins</td>
<td>Reagent</td>
<td>Fine Science Tools</td>
<td>26002-10</td>
<td>&nbsp;</td>
<tr>
<td>Pin holder</td>
<td>Reagent</td>
<td>Fine Science Tools</td>
<td>26018-17</td>
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fluorescent labeling of drosophila heart structures

The Drosophila melanogaster dorsal vessel, or heart, is a tubular structure comprised of a single layer of contractile cardiomyocytes, pericardial cells that align along each side of the heart wall, supportive alary muscles and, in adults, a layer of ventral longitudinal muscle cells. The contractile fibers house conserved constituents of the muscle cytoarchitecture including densely packed bundles of myofibrils and cytoskeletal/submembranous protein complexes, which interact with homologous components of the extracellular matrix. Here we describe a protocol for the fixation and the fluorescent labeling of particular myocardial elements from the hearts of dissected larvae and semi-intact adult Drosophila. Specifically, we demonstrate the labeling of sarcomeric F-actin and of &alpha;-actinin in larval hearts. Additionally, we perform labeling of F-actin and &alpha;-actinin in myosin-GFP expressing adult flies and of &alpha;-actinin and pericardin, a type IV extracellular matrix collagen, in wild type adult hearts. Particular attention is given to a mounting strategy for semi-intact adult hearts that minimizes handling and optimizes the opportunity for maintaining the integrity of the cardiac tubes and the associated tissues. These preparations are suitable for imaging via fluorescent and confocal microscopy. Overall, this procedure allows for careful and detailed analysis of the structural characteristics of the heart from a powerful genetically tractable model system.

Watch this Scientific Journal Video about Fluorescent Labeling of Drosophila Heart Structures at JoVE.com

Fluorescent Labeling of Drosophila Heart Structures

Here we describe a basic protocol for fluorescent labeling of different elements of heart tubes from larva and adult Drosophila melanogaster. These specimens are well-suited for imaging via fluorescent or confocal microscopy. This technique permits detailed structural analysis of the features of the hearts from a powerful model organism.

Fluorescent Labeling of Drosophila Heart Structures

The Drosophila melanogaster dorsal vessel, or heart, is a tubular structure comprised of a single layer of contractile cardiomyocytes, pericardial cells ...

fluorescent-labeling-of-drosophila-heart-structures

Research

JoVE Journal

Biology

13.6K Aufrufe.  San Diego State University. Hier beschreiben wir eine grundlegende Protokoll für die Fluoreszenzmarkierung der verschiedenen Elemente des Herzens Rohre von Larven und erwachsenen Drosophila melanogaster. Diese Proben sind für die Bildgebung mittels Fluoreszenz-oder konfokalen Mikroskopie geeignet. Diese Technik ermöglicht detaillierte Strukturanalyse der Funktionen des Herzens von einem leistungsstarken Modell-Organismus.

Serie: Fluorescent Labeling of Drosophila Heart Structures

Labeling Stem Cells with Fluorescent Dyes for non-invasive Detection with Optical Imaging

Optical imaging (OI) is an easy, fast and inexpensive tool for in vivo monitoring of new stem cell based therapies. The technique is based on ex vivo labeling of stem cells with a fluorescent dye, subsequent intravenous injection of the labeled cells and visualization of their accumulation in specific target organs or pathologies. The presented technique demonstrates how we label human mesenchymal stem cells (hMSC) by simple incubation with the lipophilic fluorescent dye DiD (C67H103CIN2O3S) and how we label human embryonic stem cells (hESC) with the FDA approved fluorescent dye Indocyanine Green (ICG). The uptake mechanism is via adherence and diffusion of the lypophilic dye across the phospholipid cell membrane bilayer. The labeling efficiency is usually improved if the cells are incubated with the dye in serum-free media as opposed to incubation in serum-containing media. Furthermore, the addition of the transfection agent Protamine Sulfate significantly improves contrast agent uptake.

This video shows techniques for labeling of human embryonic stem cells and mesenchymal stem cells with fluorescent dyes. This technique can be used for an in vivo tracking of transplanted stem cells with optical imaging and for histopathological correlations with fluorescence microscopy.

Optical imaging (OI) is an easy, fast and inexpensive tool for in vivo monitoring of new stem cell based therapies. The technique is based on ex vivo ...

Visualizing the Live Drosophila Glial-neuromuscular Junction with Fluorescent Dyes

Our project identified GFP labeled glial structures at the developing larval fly neuromuscular synapse. To look at development of live glial-nerve-muscle synapses, we developed a larval tissue preparation that had features of live intact larvae, but also had good optical properties.  This new preparation also allowed for access of perfusates to the synapse.  We used fly larvae, immersed them in artificial hemolymph, and relaxed their normal rhythmic body contractions by chilling them. Next we dissected off the posterior segments of each animal and with a blunt insect pin pushed the mouth parts backward through the body cavity.  This everted the larval body wall, like turning a sock inside-out.  We completed the dissection with ultra-fine dissection scissors and thus exposed the visceral side of the body wall muscles. The glial structures at the NMJ expressed membrane targeted GFP under the control of glial specific promoters. The post-synaptic membrane, the SSR (Subsynaptic Reticula) in muscle expressed synaptically targeted dsRed. We needed to acutely label the motor neuron terminals, the third part of the synapse. To do this we applied primary antibodies to HRP, conjugated to a far-red emitting flurophore.  To test for dye diffusion properties into the perisynaptic space between the motor neuron terminals and the SSR, we applied a solution of large Dextran molecules conjugated to far-red emitting flurophore and collected images.

Visualizing the Live Drosophila Glial-neuromuscular Junction with Fluorescent Dyes

We described structural features of the Glia-neuromuscular synapses in a novel Inside-out tissue preparation of live fly larvae using fluorescent dyes with confocal microscopy. We labeled live neuron terminals with fluorescent primary antibodies to HRP, and also visualized the perisynaptic space with fluorescent Dextrans.

Our project identified GFP labeled glial structures at the developing larval fly neuromuscular synapse. To look at development of live glial-nerve-muscle ...

Visualizing the Beating Heart in Drosophila

The Drosophila heart has recently emerged as a good model system for examining the genetic, cellular, and molecular mechanisms underlying function in myogenic hearts. A key step in examining heart function in the fly is finding a way to access the heart in a manner that preserves its myogenic function while still allowing the beating heart organ to be observed and recorded. Two different methods for observing and recording the beating heart in both larva and adult Drosophila are described here. Our semi-intact preparation using adult flies allows clear visualization of the abdominal heart without interference from the pigmented cuticle and overlying fat bodies. To record larval heart beats it is necessary to immobilize the larva, which minimizes body wall movements thereby reducing heart movements that are not associated with myocardial contractions. Our methodologies produce stable adult and larval heart preparations that can beat for hours at rates of 1-3 Hz.

Visualizing the Beating Heart in Drosophila

Technique required for visualizing the beating heart in larval and adult Drosophila are presented. Each life stage requires a different methodology.

The Drosophila heart has recently emerged as a good model system for examining the genetic, cellular, and molecular mechanisms underlying function in ...

Monitoring Heart Function in Larval Drosophila melanogaster for Physiological Studies

We present various methods to record cardiac function in the larval Drosophila. The approaches allow heart rate to be measured in unrestrained and restrained whole larvae. For direct control of the environment around the heart another approach utilizes the dissected larvae and removal of the internal organs in order to bathe the heart in desired compounds. The exposed heart also allows membrane potentials to be monitored which can give insight of the ionic currents generated by the myocytes and for electrical conduction along the heart tube. These approaches have various advantages and disadvantages for future experiments that are discussed. The larval heart preparation provides an additional model besides the Drosophila skeletal NMJ to investigate the role of intracellular calcium regulation on cellular function. Learning more about the underlying ionic currents that shape the action potentials in myocytes in various species, one can hope to get a handle on the known ionic dysfunctions associated to specific genes responsible for various diseases in mammals.

Monitoring Heart Function in Larval Drosophila melanogaster for Physiological Studies

We present various ways to monitor heart function in the larva of Drosophila for assessing questions dealing with the function of gap junctions, ion channel mutations, modulation of pacemaker activity and pharmacological studies.

We present various methods to record cardiac function in the larval Drosophila. The approaches allow heart rate to be measured in unrestrained  and  ...

Preparation of embryos for Electron Microscopy of the Drosophila embryonic heart tube

The morphogenesis of the Drosophila embryonic heart tube has emerged as a valuable model system for studying cell migration, cell-cell adhesion and cell shape changes during embryonic development. One of the challenges faced in studying this structure is that the lumen of the heart tube, as well as the membrane features that are crucial to heart tube formation, are difficult to visualize in whole mount embryos, due to the small size of the heart tube and intra-lumenal space relative to the embryo. The use of transmission electron microscopy allows for higher magnification of these structures and gives the advantage of examining the embryos in cross section, which easily reveals the size and shape of the lumen. In this video, we detail the process for reliable fixation, embedding, and sectioning of late stage Drosophila embryos in order to visualize the heart tube lumen as well as important cellular structures including cell-cell junctions and the basement membrane.

Preparation of embryos for Electron Microscopy of the Drosophila embryonic heart tube

We describe a process for fixation, embedding, sectioning, and imaging of late stage Drosophila embryos for Trasmission Electron Microscopy of the embryonic heart tube. This technique allows for the visualization of the heart tube lumen as well as the basement membrane, which lines the lumen of the heart.

The morphogenesis of the Drosophila  embryonic heart tube has emerged as a valuable model system for studying cell migration, cell-cell adhesion and cell ...

Preparation of Drosophila Polytene Chromosome Squashes for Antibody Labeling

Drosophila has long been a favorite model system for studying the relationship between chromatin structure and gene regulation due to the cytological advantages provided by the giant salivary gland polytene chromosomes of third instar larvae.  In this tissue the chromosomes undergo many rounds of replication in the absence of cell division giving rise to approximately 1000 copies.  The DNA remains aligned after each replicative cycle resulting in greatly enlarged chromosomes that provide a unique opportunity to correlate chromatin morphology with the localization of specific proteins.  Consequently, there has been a high level of interest in defining the epigenetic modifications present at different genes and at different stages of the transcription process. An important tool for such studies is the labeling of polytene chromosomes with antibodies to the enzyme, transcription factor, or histone modification of interest. This video protocol illustrates the squash technique used in the Johansen laboratory to prepare Drosophila polytene chromosomes for antibody labeling.

This video protocol illustrates the squash technique used in the Johansen laboratory to prepare Drosophila polytene chromosomes for antibody labeling.

Drosophila has long been a favorite model system for studying the relationship between chromatin structure and gene regulation due to the cytological ...

Fluorescent Labeling of COS-7 Expressing SNAP-tag Fusion Proteins for Live Cell Imaging

SNAP-tag and CLIP-tag protein labeling systems enable the specific, covalent attachment of molecules, including fluorescent dyes, to a protein of interest in live cells. These systems offer a broad selection of fluorescent substrates optimized for a range of imaging instrumentation. Once cloned and expressed, the tagged protein can be used with a variety of substrates for numerous downstream applications without having to clone again. There are two steps to using this system: cloning and expression of the protein of interest as a SNAP-tag fusion, and labeling of the fusion with the SNAP-tag substrate of choice. The SNAP-tag is a small protein based on human O6-alkylguanine-DNA-alkyltransferase (hAGT), a DNA repair protein. SNAP-tag labels are dyes conjugated to guanine or chloropyrimidine leaving groups via a benzyl linker. In the labeling reaction, the substituted benzyl group of the substrate is covalently attached to the SNAP-tag. CLIP-tag is a modified version of SNAP-tag, engineered to react with benzylcytosine rather than benzylguanine derivatives. When used in conjunction with SNAP-tag, CLIP-tag enables the orthogonal and complementary labeling of two proteins simultaneously in the same cells.

SNAP-tag and CLIP-tag protein labeling systems enable the specific, covalent attachment of molecules, including fluorescent dyes, to a protein of interest in live cells. Once cloned and expressed, the tagged protein can be used with a variety of substrates for numerous downstream applications without having to clone again.

SNAP-tag and CLIP-tag protein labeling systems enable the specific, covalent attachment of molecules, including fluorescent dyes, to a protein of interest ...

Whole Mount RNA Fluorescent in situ Hybridization of Drosophila Embryos

Assessing the expression pattern of a gene, as well as the subcellular localization properties of its transcribed RNA, are key features for understanding its biological function during development. RNA in situ hybridization (RNA-ISH) is a powerful method used for visualizing RNA distribution properties, be it at the organismal, cellular or subcellular levels 1. RNA-ISH is based on the hybridization of a labeled nucleic acid probe (e.g. antisense RNA, oligonucleotides) complementary to the sequence of an mRNA or a non-coding RNA target of interest 2. As the procedure requires primary sequence information alone to generate sequence-specific probes, it can be universally applied to a broad range of organisms and tissue specimens 3. Indeed, a number of large-scale ISH studies have been implemented to document gene expression and RNA localization dynamics in various model organisms, which has led to the establishment of important community resources 4-11. While a variety of probe labeling and detection strategies have been developed over the years, the combined usage of fluorescently-labeled detection reagents and enzymatic signal amplification steps offer significant enhancements in the sensitivity and resolution of the procedure 12. Here, we describe an optimized fluorescent in situ hybridization method (FISH) employing tyramide signal amplification (TSA) to visualize RNA expression and localization dynamics in staged Drosophila embryos. The procedure is carried out in 96-well PCR plate format, which greatly facilitates the simultaneous processing of large numbers of samples.

Whole Mount RNA Fluorescent in situ Hybridization of Drosophila Embryos

Here we describe a whole-mount fluorescent in situ hybridization (FISH) protocol for determining the expression and localization properties of RNAs expressed during embryogenesis in the fruit fly, Drosophila melanogaster.

Assessing  the expression pattern of a gene, as well as the subcellular localization  properties of its transcribed RNA, are key features for ...

Intravital Microscopy for Imaging Subcellular Structures in Live Mice Expressing Fluorescent Proteins

Here we describe a procedure to image subcellular structures in live rodents that is based on the use of confocal intravital microscopy. As a model organ, we use the salivary glands of live mice since they provide several advantages. First, they can be easily exposed to enable access to the optics, and stabilized to facilitate the reduction of the motion artifacts due to heartbeat and respiration. This significantly facilitates imaging and tracking small subcellular structures. Second, most of the cell populations of the salivary glands are accessible from the surface of the organ. This permits the use of confocal microscopy that has a higher spatial resolution than other techniques that have been used for in vivo imaging, such as two-photon microscopy. Finally, salivary glands can be easily manipulated pharmacologically and genetically, thus providing a robust system to investigate biological processes at a molecular level.
In this study we focus on a protocol designed to follow the kinetics of the exocytosis of secretory granules in acinar cells and the dynamics of the apical plasma membrane where the secretory granules fuse upon stimulation of the beta-adrenergic receptors. Specifically, we used a transgenic mouse that co-expresses cytosolic GFP and a membrane-targeted peptide fused with the fluorescent protein tandem-Tomato. However, the procedures that we used to stabilize and image the salivary glands can be extended to other mouse models and coupled to other approaches to label in vivo cellular components, enabling the visualization of various subcellular structures, such as endosomes, lysosomes, mitochondria, and the actin cytoskeleton.

Intravital microscopy is a powerful tool that enables imaging various biological processes in live animals. In this article, we present a detailed method for imaging the dynamics of subcellular structures, such as the secretory granules, in the salivary glands of live mice.

Here we describe a procedure to image subcellular structures in live rodents that is based on the use of confocal intravital microscopy. As a model organ, ...

Drosophila Preparation and Longitudinal Imaging of Heart Function In Vivo Using Optical Coherence Microscopy (OCM)

Longitudinal study of the heartbeat in small animals contributes to understanding structural and functional changes during heart development. Optical coherence microscopy (OCM) has been demonstrated to be capable of imaging small animal hearts with high spatial resolution and ultrahigh imaging speed. The high image contrast and noninvasive properties make OCM ideal for performing longitudinal studies without requiring tissue dissections or staining. Drosophila has been widely used as a model organism in cardiac developmental studies due to its high number of orthologous human disease genes, its similarity of molecular mechanisms and genetic pathways with vertebrates, its short life cycle, and its low culture cost. Here, the experimental protocols are described for the preparation of Drosophila and optical imaging of the heartbeat with a custom OCM system throughout the life cycle of the specimen. By following the steps provided in this report, transverse M-mode and 3D OCM images can be acquired to conduct longitudinal studies of the Drosophila cardiac morphology and function. The en face and axial sectional OCM images and the heart rate (HR) and cardiac activity period (CAP) histograms, were also shown to analyze the heart structural changes and to quantify the heart dynamics during Drosophila metamorphosis, combined with the videos constructed with M-mode images to trace cardiac activity intuitively. Due to the genetic similarity between Drosophila and vertebrates, longitudinal study of heart morphology and dynamics in fruit flies could help reveal the origins of human heart diseases. The protocol here would provide an effective method to perform a wide range of studies to understand the mechanisms of cardiac diseases in humans.

Drosophila Preparation and Longitudinal Imaging of Heart Function In Vivo Using Optical Coherence Microscopy OCM

Here, the experimental protocols are described for preparing Drosophila at different developmental stages and performing longitudinal optical imaging of Drosophila heartbeats using a custom optical coherence microscopy (OCM) system. The cardiac morphological and dynamical changes can be quantitatively characterized by analyzing the heart structural and functional parameters from OCM images.

Longitudinal study of the heartbeat in small animals contributes to understanding structural and functional changes during heart development. Optical ...