The authors thank Dr Anne Gibbon, Dr Christine Mackay and all the staff at Monash Animal Services and Physiology animal house. The authors thank Jeremy Weinstein and the Mcube team for video and animation production.a

<ol>
 <li>The sheep is fasted for 24 hours but allowed water ad libitum</li>
 <li>The sheep is weighed.</li>
 <li>Anaestheisa is induced by intravenous injection of thiopentone (20mg/kg).</li>
 <li>Prophylactic intravenous antibiotics may be given.</li>
 <li>Endotracheal intubation is performed using a sized 7 to 9 cuffed endotracheal tube. </li>
 <li>Anaesthesia is maintainted with isoflurane, 1&#x2013;3%, in 100% oxygen at a flow rate of 2L per minute.</li>
 <li>Observations are made and the level of anaesthesia monitored continuously. </li>
 <li>The surgical tools needed for this operation include: Toothed forceps, non toothed forceps, Metzenbaum scissors, Mayo scissors, needle holders, scalpel handle (long and short), Kerrison rongeurs, pituitary rongeurs, pneumatic surgical drill, drill bits and guards, nerve hooks (blunt and micro hook), elevator (ie, Watson Cheyne), insulated mono polar and bipolar electrosurgical forceps, vertebral body distractor (ie 16mm Caspar pins), distraction pin drill and drill sleeve, 2-0, and 3-0 angled curettes, Size 7 and 10 French sucker and suction tubing, Langenback retractors and self-retaining cervical retractors.</li>
 <li>The neck region is shaved and washed with a betadine detergent solution.</li>
 <li>The animal is then placed in the supine position onto the operating table and the neck gently extended.</li>
 <li>The skin is marked with a needle and an x-ray is taken to confirm the C3/4 level. </li>
 <li>The neck is then prepped using alcoholic chlorhexidine, alcoholic iodine and 70% ethanol in water.</li>
 <li>A fenestrated square drape is used for the surgical site and a large square drape for the overhead table.</li>
 <li>An operating microscope, or Loupe magnification and headlight, are used for the surgical procedure.</li>
 <li>The incision is made using a scalpel at the site previously identified using the x-ray</li>
 <li>Next, dissection through the investing layers is performed using scissors and a plane developed medial to the carotid sheath and lateral to the trachea and oesophagus.</li>
 <li>Haemostasis is maintained through the procedure using diathermy</li>
 <li>Once the vertebral column is located, the midline should be palpated and care should be taken to ensure that retraction is medial to the carotid artery and lateral to trachea and oesophagus.</li>
 <li>A bayoneted needle is then inserted into the disc (this prevents inadvertent advancement which could risk damaging the spinal cord). A square drape is used to cover the surgical site. Before an intraoperative xray is taken to confirm the C3/4 disc level.</li>
 <li>Casper distraction pins are then inserted in C3 and C4 respectively.</li>
 <li>The disc is incised with a 15-scalpel blade.</li>
 <li>The distractor is then inserted and the disc space gently distracted apart.</li>
 <li>A discectomy is then performed using rongeurs and Kerrison rongeurs. A drill and curettes may also be of assistance.</li>
 <li>The endplates are then prepared using the drill and curettes until bleeding bone visualized.</li>
 <li>The posterior longitudinal ligament may be opened at this point, depending on experimental design. A blunt hook and 1mm Kerrison are best used for this procedure.</li>
 <li>The wound is then irrigated with normal saline, prior to insertion of the interbody cage or test material.</li>
 <li>The distraction is relaxed ad the device checked to ensure that it is securely in place.</li>
 <li>The distraction pins are then removed and bone wax may be inserted to achieve haemostasis in the bone holes.</li>
 <li>The longus coli muscle is closed with Vicryl. Layered closure is then performed, preferably with a subcuticular suture to avoid the need for suture removal.</li>
 <li>Xylocaine is infiltrated around the surgical site</li>
 <li>The anaestheitc gas is switched off and, when spontaneous breathing occurs and signs of swallowing are evident, the endotracheal tube is removed.</li>
 <li>The animal is then allowed to recover in a metabolic cage under constant observation.</li>
 <li>It is important that the animal is positioned upright with legs tucked under it, to prevent regurgitation.</li>
 <li>Once the animal is standing (usually within 1 hour) food and water may be reintroduced.</li>
 <li>Close monitored is performed for 24 hours and continued for 1 week.</li>
 <li>Analgesia is maintained with a Fentanyl patch for 3 days following the operation.</li>
</ol>

<ol>
	<li>Angevine, P. D., Arons, R. R., McCormick, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=National+and+regional+rates+and+variation+of+cervical+discectomy+with+and+without+anterior+fusion,+1990-1999.">National and regional rates and variation of cervical discectomy with and without anterior fusion, 1990-1999.</a> Spine. 28, 931-940 (2003).</li><li>Cloward, 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=The+anterior+approach+for+removal+of+ruptured+cervical+disks.">The anterior approach for removal of ruptured cervical disks.</a> J Neurosurg. 15, 602-617 (1958).</li><li>Jacobs, W. C., Anderson, P. G., Limbeek, J., Willems, P. C., Pavlov, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+or+double-level+anterior+interbody+fusion+techniques+for+cervical+degenerative+disc+disease.">Single or double-level anterior interbody fusion techniques for cervical degenerative disc disease.</a> Cochrane Database Syst Rev. , CD004958-CD004958 (2004).</li><li>Kandziora, F., Pflugmacher, R., Scholz, M., Schnake, K., Lucke, M., Schr&#246;der, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+between+sheep+and+human+cervical+spines:+an+anatomic,+radiographic,+bone+mineral+density,+and+biomechanical+study.">Comparison between sheep and human cervical spines: an anatomic, radiographic, bone mineral density, and biomechanical study.</a> Spine. 26, 1028-1037 (2001).</li><li>Patil, P. G., Turner, D. A., 	Pietrobon, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=National+trends+in+surgical+procedures+for+degenerative+cervical+spine+disease:+1990-2000.">National trends in surgical procedures for degenerative cervical spine disease: 1990-2000.</a> Neurosurgery. 57, 753-758 (2005).</li><li>Smith, G. W., Robinson, R. 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+treatment+of+certain+cervical-spine+disorders+by+anterior+removal+of+the+intervertebral+disc+and+interbody+fusion.">The treatment of certain cervical-spine disorders by anterior removal of the intervertebral disc and interbody fusion.</a> J Bone Joint Surg Am. 40-A, 607-624 (1958).</li></ol>

There are some sources of variability to consider while planning and performing anterior cervical discectomy and fusion. Therefore, for consistency of the model, the animals should be of the same age and breed. We prefer two year old, crossbred Leicester Merino sheep. If performed correctly, there will be minimal complications such as bleeding, infection, or mortality. Bleeding should be controlled throughout the procedure and haemosatsis checked before closing. Prophylactic antiobiotics are given at induction to minimse infection risk. Advice and help from the Clinical Veterinarians is invaluable and should be sought early. The procedure is generally well tolerated. 
Monitoring of progression of fusion can be performed with regular x-rays.
Conclusion
In conclusion, we have demonstrated techniques and hardware and a simple and reproducible method for studying novel therapies for anterior cervical discectomy and fusion.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">	
		
		<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>Marcain</td>
<td>&nbsp;</td>
<td>AstraZeneca</td>
<td>&nbsp;</td>
<td>0/5% Bupivicaine hydrochloride solution for injection 100mg in 20 mls</td>
</tr>
<tr>
<td>Thiopentone</td>
<td>&nbsp;</td>
<td>Illium</td>
<td>&nbsp;</td>
<td>Thiopentone sodium (sterile powder for injection) 5g</td>
</tr>
<tr>
<td>Issoranne</td>
<td>&nbsp;</td>
<td>Baxter</td>
<td>&nbsp;</td>
<td>Isoflurane BP 100%</td>
</tr>
<tr>
<td>Chlorehxidine</td>
<td>&nbsp;</td>
<td>Jurox</td>
<td>&nbsp;</td>
<td>40mg/ml Chlorhexidine glucoronate</td>
</tr>
<tr>
<td>PVD Iodine Solution</td>
<td>&nbsp;</td>
<td>Apex</td>
<td>&nbsp;</td>
<td>Povidine Iodine 100mg/ml</td>
</tr>		</tbody>
		</table>
		</div>

anterior cervical discectomy and fusion in the ovine model

Anterior cervical discectomy and fusion (ACDF) is the most common surgical operation for cervical radiculopathy and/or myelopathy in patients who have failed conservative treatment1,5. Since the operation was first described by Cloward2 and Smith and Robinson6 in 1958, a variety refinements in technique, graft material and implants have been made3. In particular, there is a need for safe osteoinductive agents that could benefit selected patients. The ovine model has been shown to have anatomical, biomechanical, bone density and radiological properties that are similar to the human counterpart, the most similar level being C3/44. It is therefore an ideal model in which preclinical studies can be performed. In particular this methodology may be useful to researchers interested in evaluating different devices and biologics, including stem cells, for potential application in human spinal surgery.

Watch this Scientific Journal Video about Anterior Cervical Discectomy and Fusion in the Ovine Model at JoVE.com

Anterior Cervical Discectomy and Fusion in the Ovine Model

This video demonstrates the technique of anterior cervical discectomy and fusion in the ovine model.

Anterior cervical discectomy and fusion (ACDF) is the most common surgical operation for cervical radiculopathy and/or myelopathy in patients who have ...

anterior-cervical-discectomy-and-fusion-in-the-ovine-model

Nanyang Technological University

Research

JoVE Journal

Biology

12.8K Views.  Monash University. This video demonstrates the technique of anterior cervical discectomy and fusion in the ovine model.

Video: Anterior Cervical Discectomy and Fusion in the Ovine Model

Method for Measurement of Viral Fusion Kinetics at the Single Particle Level

Membrane fusion is an essential step during entry of enveloped viruses into cells. Conventional fusion assays typically report on a large number of fusion events, making it difficult to quantitatively analyze the sequence of the molecular steps involved. We have developed an in vitro, two-color fluorescence assay to monitor kinetics of single virus particles fusing with a target bilayer on an essentially fluid support.
Influenza viral particles are incubated with a green lipophilic fluorophore to stain the membrane and a red hydrophilic fluorophore to stain the viral interior. We deposit a ganglioside-containing lipid bilayer on the dextran-functionilized glass surface of a flow cell, incubate the viral particles on the planar bilayer and image the fluorescence of a 100 x 100 &mu;m2 area, containing several hundreds of particles, on a CCD camera. By imaging both the red and green fluorescence, we can simultaneously monitor the behavior of the membrane dye (green) and the aqueous content (red) of the particles.
Upon lowering the pH to a value below the fusion pH, the particles will fuse with the membrane. Hemifusion, the merging of the outer leaflet of the viral membrane with the outer leaflet of the target membrane, will be visible as a sudden change in the green fluorescence of a particle. Upon the subsequent fusion of the two remaining distal leaflets a pore will be formed and the red-emitting fluorophore in the viral particle will be released under the target membrane. This event will give rise to a decrease of the red fluorescence of individual particles. Finally, the integrated fluorescence from a pH-sensitive fluorophore that is embedded in the target membrane reports on the exact time of the pH drop.
From the three fluorescence-time traces, all the important events (pH drop, lipid mixing upon hemifusion, content mixing upon pore formation) can now be extracted in a straightforward manner and for every particle individually. By collecting the elapsed times for the various transitions for many individual particles in histograms, we can determine the lifetimes of the corresponding intermediates. Even hidden intermediates that do not have a direct fluorescent observable can be visualized directly from these histograms.

We present an in vitro, two-color fluorescence assay to visualize the fusion of single virus particles with a fluid target bilayer. By labeling viral particles with fluorophores that differentially stain the viral membrane and its interior, we are able to monitor the kinetics of hemifusion and pore formation.

Membrane fusion is an essential step during entry of enveloped viruses into cells. Conventional fusion assays typically report on a large number of fusion ...

Analysis of SNARE-mediated Membrane Fusion Using an Enzymatic Cell Fusion Assay

The interactions of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins on vesicles (v-SNAREs) and on target membranes (t-SNAREs) catalyze intracellular vesicle fusion1-4. Reconstitution assays are essential for dissecting the mechanism and regulation of SNARE-mediated membrane fusion5. In a cell fusion assay6,7, SNARE proteins are expressed ectopically at the cell surface. These "flipped" SNARE proteins drive cell-cell fusion, demonstrating that SNAREs are sufficient to fuse cellular membranes. Because the cell fusion assay is based on microscopic analysis, it is less efficient when used to analyze multiple v- and t-SNARE interactions quantitatively.
Here we describe a new assay8 that quantifies SNARE-mediated cell fusion events by activated expression of &beta;-galactosidase. Two components of the Tet-Off gene expression system9 are used as a readout system: the tetracycline-controlled transactivator (tTA) and a reporter plasmid that encodes the LacZ gene under control of the tetracycline-response element (TRE-LacZ). We transfect tTA into COS-7 cells that express flipped v-SNARE proteins at the cell surface (v-cells) and transfect TRE-LacZ into COS-7 cells that express flipped t-SNARE proteins at the cell surface (t-cells). SNARE-dependent fusion of the v- and t-cells results in the binding of tTA to TRE, the transcriptional activation of LacZ and expression of &beta;-galactosidase. The activity of &beta;-galactosidase is quantified using a colorimetric method by absorbance at 420 nm.
The vesicle-associated membrane proteins (VAMPs) are v-SNAREs that reside in various post-Golgi vesicular compartments10-15. By expressing VAMPs 1, 3, 4, 5, 7 and 8 at the same level, we compare their membrane fusion activities using the enzymatic cell fusion assay. Based on spectrometric measurement, this assay offers a quantitative approach for analyzing SNARE-mediated membrane fusion and for high-throughput studies.

We have developed a cell fusion assay that quantifies SNARE-mediated membrane fusion events by activated expression of &beta;-galactosidase.

The interactions of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor)  proteins on vesicles (v-SNAREs) and on target membranes ...

Evaluation of Muscle Function of the Extensor Digitorum Longus Muscle Ex vivo and Tibialis Anterior Muscle In situ in Mice

Body movements are mainly provided by mechanical function of skeletal muscle. Skeletal muscle is composed of numerous bundles of myofibers that are sheathed by intramuscular connective tissues. Each myofiber contains many myofibrils that run longitudinally along the length of the myofiber. Myofibrils are the contractile apparatus of muscle and they are composed of repeated contractile units known as sarcomeres. A sarcomere unit contains actin and myosin filaments that are spaced by the Z discs and titin protein. Mechanical function of skeletal muscle is defined by the contractile and passive properties of muscle. The contractile properties are used to characterize the amount of force generated during muscle contraction, time of force generation and time of muscle relaxation. Any factor that affects muscle contraction (such as interaction between actin and myosin filaments, homeostasis of calcium, ATP/ADP ratio, etc.) influences the contractile properties. The passive properties refer to the elastic and viscous properties (stiffness and viscosity) of the muscle in the absence of contraction. These properties are determined by the extracellular and the intracellular structural components (such as titin) and connective tissues (mainly collagen) 1-2. The contractile and passive properties are two inseparable aspects of muscle function. For example, elbow flexion is accomplished by contraction of muscles in the anterior compartment of the upper arm and passive stretch of muscles in the posterior compartment of the upper arm. To truly understand muscle function, both contractile and passive properties should be studied.
The contractile and/or passive mechanical properties of muscle are often compromised in muscle diseases. A good example is Duchenne muscular dystrophy (DMD), a severe muscle wasting disease caused by dystrophin deficiency 3. Dystrophin is a cytoskeletal protein that stabilizes the muscle cell membrane (sarcolemma) during muscle contraction 4. In the absence of dystrophin, the sarcolemma is damaged by the shearing force generated during force transmission. This membrane tearing initiates a chain reaction which leads to muscle cell death and loss of contractile machinery. As a consequence, muscle force is reduced and dead myofibers are replaced by fibrotic tissues 5. This later change increases muscle stiffness 6. Accurate measurement of these changes provides important guide to evaluate disease progression and to determine therapeutic efficacy of novel gene/cell/pharmacological interventions. Here, we present two methods to evaluate both contractile and passive mechanical properties of the extensor digitorum longus (EDL) muscle and the contractile properties of the tibialis anterior (TA) muscle.

Evaluation of Muscle Function of the Extensor Digitorum Longus Muscle Ex vivo and Tibialis Anterior Muscle In situ in Mice

Changes in limb muscle contractile and passive mechanical properties are important biomarkers for muscle diseases. This manuscript describes physiological assays to measure these properties in the murine extensor digitorum longus and tibialis anterior muscles.

Body  movements are mainly provided by mechanical function of skeletal muscle. Skeletal  muscle is composed of numerous bundles of myofibers that are ...

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the function and regulation of protein folding was studied in vitro, in isolated tissue culture cells and in unicellular organisms. Recent studies have uncovered links between protein homeostasis (proteostasis), metabolism, development, aging, and temperature-sensing. These findings have led to the development of new tools for monitoring protein folding in the model metazoan organism Caenorhabditis elegans. In our laboratory, we combine behavioral assays, imaging and biochemical approaches using temperature-sensitive or naturally occurring metastable proteins as sensors of the folding environment to monitor protein misfolding. Behavioral assays that are associated with the misfolding of a specific protein provide a simple and powerful readout for protein folding, allowing for the fast screening of genes and conditions that modulate folding. Likewise, such misfolding can be associated with protein mislocalization in the cell. Monitoring protein localization can, therefore, highlight changes in cellular folding capacity occurring in different tissues, at various stages of development and in the face of changing conditions. Finally, using biochemical tools ex vivo, we can directly monitor protein stability and conformation. Thus, by combining behavioral assays, imaging and biochemical techniques, we are able to monitor protein misfolding at the resolution of the organism, the cell, and the protein, respectively.

Using Caenorhabditis elegans as a Model System to Study Protein Homeostasis in a Multicellular Organism

To study the relationship between protein homeostasis, stress and aging, we monitored changes in protein folding by following protein dysfunction, protein localization in the cell and protein stability at the organismal, cellular and protein levels, using the genetically tractable metazoan Caenorhabditis elegans as a model system.

The folding and assembly of proteins is essential for protein function, the long-term health of the cell, and longevity of the organism. Historically, the ...

The Assembly and Application of 'Shear Rings': A Novel Endothelial Model for Orbital, Unidirectional and Periodic Fluid Flow and Shear Stress

Deviations from normal levels and patterns of vascular fluid shear play important roles in vascular physiology and pathophysiology by inducing adaptive as well as pathological changes in endothelial phenotype and gene expression. In particular, maladaptive effects of periodic, unidirectional flow induced shear stress can trigger a variety of effects on several vascular cell types, particularly endothelial cells. While by now endothelial cells from diverse anatomic origins have been cultured, in-depth analyses of their responses to fluid shear have been hampered by the relative complexity of shear models (e.g., parallel plate flow chamber, cone and plate flow model). While these all represent excellent approaches, such models are technically complicated and suffer from drawbacks including relatively lengthy and complex setup time, low surface areas, requirements for pumps and pressurization often requiring sealants and gaskets, creating challenges to both maintenance of sterility and an inability to run multiple experiments. However, if higher throughput models of flow and shear were available, greater progress on vascular endothelial shear responses, particularly periodic shear research at the molecular level, might be more rapidly advanced. Here, we describe the construction and use of shear rings: a novel, simple-to-assemble, and inexpensive tissue culture model with a relatively large surface area that easily allows for a high number of experimental replicates in unidirectional, periodic shear stress studies on endothelial cells.

Different levels and patterns of fluid shear are known to modulate endothelial gene expression, phenotype and susceptibility to disease. We discuss the assembly and use of 'shear rings': a model that produces unidirectional, periodic shear stress patterns. Shear rings are simple to assemble, economical and can produce high cell yields.

Deviations from normal levels and patterns of vascular fluid shear play important roles in vascular physiology and pathophysiology by inducing adaptive as ...

Expression of Fluorescent Fusion Proteins in Murine Bone Marrow-derived Dendritic Cells and Macrophages

Dendritic cells and macrophages are crucial cells that form the first line of defense against pathogens. They also play important roles in the initiation of an adaptive immune response. Experimental work with these cells is rather challenging. Their abundance in organs and tissues is relatively low. As a result, they cannot be isolated in large numbers. They are also difficult to transfect with cDNA constructs. In the murine model, these problems can be partially overcome by in vitro differentiation from bone marrow progenitors in the presence of M-CSF for macrophages or GM-CSF for dendritic cells. In this way, it is possible to obtain large amounts of these cells from very few animals. Moreover, bone marrow progenitors can be transduced with retroviral vectors carrying cDNA constructs during early stages of cultivation prior to their differentiation into bone marrow derived dendritic cells and macrophages. Thus, retroviral transduction followed by differentiation in vitro can be used to express various cDNA constructs in these cells. The ability to express ectopic proteins substantially extends the range of experiments that can be performed on these cells, including live cell imaging of fluorescent proteins, tandem purifications for interactome analyses, structure-function analyses, monitoring of cellular functions with biosensors and many others. In this article, we describe a detailed protocol for retroviral transduction of murine bone marrow derived dendritic cells and macrophages with vectors coding for fluorescently-tagged proteins. On the example of two adaptor proteins, OPAL1 and PSTPIP2, we demonstrate its practical application in flow cytometry and microscopy. We also discuss the advantages and limitations of this approach.

In this article, we provide a detailed protocol for the expression of fluorescent fusion proteins in murine bone marrow derived dendritic cells and macrophages. The method is based on the transduction of bone marrow progenitors with retroviral constructs followed by differentiation into macrophages and dendritic cells in vitro.

Dendritic cells and macrophages are crucial cells that form the first line of defense against pathogens. They also play important roles in the initiation ...

Real Time In Vivo Tracking of Thymocytes in the Anterior Chamber of the Eye by Laser Scanning Microscopy

The purpose of the method being presented is to show, for the first time, the transplant of newborn thymi into the anterior eye chamber of isogenic adult mice for in vivo longitudinal real-time monitoring of thymocytes&#180; dynamics within a vascularized thymus segment. Following the transplantation, laser scanning microscopy (LSM) through the cornea allows in vivo noninvasive repeated imaging at cellular resolution level. Importantly, the approach adds to previous intravital T-cell maturation imaging models the possibility for continuous progenitor cell recruitment and mature T-cell egress recordings in the same animal. Additional advantages of the system are the transparency of the grafted area, permitting macroscopic rapid monitoring of the implanted tissue, and the accessibility to the implant allowing for localized in addition to systemic treatments. The main limitation being the volume of the tissue that fits in the reduced space of the eye chamber which demands for lobe trimming. Organ integrity is maximized by dissecting thymus lobes in patterns previously shown to be functional for mature T-cell production. The technique is potentially suited to interrogate a milieu of medically relevant questions related to thymus function that include autoimmunity, immunodeficiency and central tolerance; processes which remain mechanistically poorly defined. The fine dissection of mechanisms guiding thymocyte migration, differentiation and selection should lead to novel therapeutic strategies targeting developing T cells.

Real Time In Vivo Tracking of Thymocytes in the Anterior Chamber of the Eye by Laser Scanning Microscopy

The goal of the protocol is to show longitudinal intravital real-time tracking of thymocytes by laser scanning microscopy in thymic implants in the anterior chamber of the mouse eye. The transparency of the cornea and vascularization of the graft allows for continuously recording progenitor cell recruitment and mature T-cell egress.

The purpose of the method being presented is to show, for the first time, the transplant of newborn thymi into the anterior eye chamber of isogenic adult ...

Effect of Fluorescent Proteins on Fusion Partners Using Polyglutamine Toxicity Assays in Yeast

For the investigation of protein localization and trafficking using live cell imaging, researchers often rely on fusing their protein of interest to a fluorescent reporter. The constantly evolving list of genetically encoded fluorescent proteins (FPs) presents users with several alternatives when it comes to fluorescent fusion design. Each FP has specific optical and biophysical properties that can affect the biochemical, cellular, and functional properties of the resulting fluorescent fusions. For instance, several FPs tend to form nonspecific oligomers that are susceptible to impede on the function of the fusion partner. Unfortunately, only a few methods exist to test the impact of FPs on the behavior of the fluorescent reporter. Here, we describe a simple method that enables the rapid assessment of the impact of FPs using polyglutamine (polyQ) toxicity assays in the budding yeast Saccharomyces cerevisiae. PolyQ-expanded huntingtin proteins are associated with the onset of Huntington&#39;s disease (HD), where the expanded huntingtin aggregates into toxic oligomers and inclusion bodies. The aggregation and toxicity of polyQ expansions in yeast are highly dependent on the sequences flanking the polyQ region, including the presence of fluorescent tags, thus providing an ideal experimental platform to study the impact of FPs on the behavior of their fusion partner.

This article describes protocols to assess the effect of fluorescent proteins on the aggregation and toxicity of misfolded polyglutamine expansion for the rapid evaluation of a newly uncharacterized fluorescent protein in the context of fluorescent reporters.

For the investigation of protein localization and trafficking using live cell imaging, researchers often rely on fusing their protein of interest to a ...

Mass Spectrometry Analysis to Identify Ubiquitylation of EYFP-tagged CENP-A (EYFP-CENP-A)

Studying the structure and the dynamics of kinetochores and centromeres is important in understanding chromosomal instability (CIN) and cancer progression. How the chromosomal location and function of a centromere (i.e., centromere identity) are determined and participate in accurate chromosome segregation is a fundamental question. CENP-A is proposed to be the non-DNA indicator (epigenetic mark) of centromere identity, and CENP-A ubiquitylation is required for CENP-A deposition at the centromere, inherited through dimerization between cell division, and indispensable to cell viability.
Here we describe mass spectrometry analysis to identify ubiquitylation of EYFP-CENP-A K124R mutant suggesting that ubiquitylation at a different lysine is induced because of the EYFP tagging in the CENP-A K124R mutant protein. Lysine 306 (K306) ubiquitylation in EYFP-CENP-A K124R was successfully identified, which corresponds to lysine 56 (K56) in CENP-A through mass spectrometry analysis. A caveat is discussed in the use of GFP/EYFP or the tagging of high molecular weight protein as a tool to analyze the function of a protein. Current technical limit is also discussed for the detection of ubiquitylated bands, identification of site-specific ubiquitylation(s), and visualization of ubiquitylation in living cells or a specific single cell during the whole cell cycle.
The method of mass spectrometry analysis presented here can be applied to human CENP-A protein with different tags and other centromere-kinetochore proteins. These combinatory methods consisting of several assays/analyses could be recommended for researchers who are interested in identifying functional roles of ubiquitylation.

Mass Spectrometry Analysis to Identify Ubiquitylation of EYFP-tagged CENP-A EYFP-CENP-A

CENP-A ubiquitylation is an important requirement for CENP-A deposition at the centromere, inherited through dimerization between cell division, and indispensable to cell viability. Here we describe mass spectrometry analysis to identify ubiquitylation of EYFP-tagged CENP-A (EYFP-CENP-A) protein.

Studying the structure and the dynamics of kinetochores and centromeres is important in understanding chromosomal instability (CIN) and cancer ...

Production of IgG Fusion Proteins Transiently Expressed in Nicotiana benthamiana

High demand for antibodies as therapeutic interventions for various infectious, metabolic, autoimmune, neoplastic, and other diseases creates a growing need in developing efficient methods for recombinant antibody production. As of 2019, there were more than 70 FDA-approved monoclonal antibodies, and there is exponential growth potential. Despite their promise, limiting factors for widespread use are manufacturing costs and complexity. Potentially, plants offer low-cost, safe, and easily scalable protein manufacturing&#160;strategies. Plants like Nicotiana benthamiana not only can correctly fold and assemble complex mammalian proteins but also can add critical post-translational modifications similar to those offered by mammalian cell cultures. In this work, by using native GFP and an acid-stable variant of green fluorescent protein (GFP) fused to human monoclonal antibodies, we were able to visualize the entire transient antibody expression and purification process from N. benthamiana plants. Depending on the experiment&#39;s purpose, native GFP fusion can ensure easier visualization during the expression phase in the plants, while acid-stable GFP fusion allows for visualization during downstream processing. This scalable and straightforward procedure can be performed by a single researcher to produce milligram quantities of highly pure antibody or antibody fusion proteins in a matter of days using only a few small plants. Such a technique can be extended to the visualization of any type of antibody purification process and potentially many other proteins, both in plant and other expression systems. Moreover, these techniques can benefit virtual instructions and be executed in a teaching laboratory by undergraduate students possessing minimal prior experience with molecular biology techniques, providing a foundation for project-based exploration with real-world applications.

Production of IgG Fusion Proteins Transiently Expressed in Nicotiana benthamiana

We describe here a simple method for expression, extraction, and purification of recombinant human IgG fused to GFP in Nicotiana benthamiana. This protocol can be extended to purification and visualization of numerous proteins that utilize column chromatography. Moreover, the protocol is adaptable to the in-person and virtual college teaching laboratory, providing project-based exploration.

High demand for antibodies as therapeutic interventions for various infectious, metabolic, autoimmune, neoplastic, and other diseases creates a growing ...