The authors have nothing to disclose.

All procedures are performed following the guidelines described in "Principles of Laboratory Animal Care" (National Institutes of Health publication no. 85-23, revised 1985) and the approved Rosalind Franklin University Institutional Animal Care and Use Committee animal protocol 08-19.
1. Gentamicin-induction of Hair Cell Necrosis
<ol>
	<li>Prepare gentamicin sulfate in normal saline at a final concentration of 0.004% (4.32 mM).</li>
	<li>Place adult fish (D. rerio, 4-6 months of age) in a container containing the 0.004% (4.32 mM) gentamicin solution. Any container can be used, but we use a fish container from a Pharmacal Aquatic System which is 7 in wide, 6 in high, and 7 in long. Place the container with fish in an incubator set at 28 &#176;C for 24 hr. Set the total volume of fluid in the tank at a sufficient level to maintain fish in a viable state for the 24 hr period. Note: Aeration of the gentamicin fluid is not necessary if sufficient volume is used for the number of fish being treated.</li>
</ol>
2. Vital Staining of Hair Cells
<ol>
	<li>Prepare a 0.08% concentration (in normal saline) of the fluorescent vital dye [4-4-diethylaminostyryl)-N-methylpyridinium iodide (485 nm excitation &#955; and 603 nm emission &#955; in methanol) from a working stock solution of 15 mg/ml in ethanol.</li>
	<li>To determine if gentamicin treatment was effective a subset of control and gentamicin treated fish are stained immediately by placing fish in the well of a 6 well culture plate containing the vital dye. Use a sufficient number of fish (and culture plates as required for statistical significance to be achieved. Based on the examiner's speed of neuromast counting, place the fish in the plates in a staggered manner over time so that fish are not stained for over 75 min as described in step 2.3.</li>
	<li>Place the plates from step 2.2 in a bench drawer by the fluorescent microscope to be used for examination of stained neuromasts. Turn off the room lights to prevent quenching of the vital dye over the 1 hr staining period at room temperature.</li>
	<li>Prepare both dye wash-out and anesthetic water tanks. Dye wash-out water is normal fish water and for anesthetic water, add sufficient 2-phenoxyethanol so that a 1:1,000 dilution in normal fish water is achieved.</li>
	<li>Place fish in excess normal fish water to rinse excess vital dye and proceed to step 3.1 for observation of vital dye stained fish.</li>
	<li>To examine regeneration of neuromasts, transfer gentamicin-treated fish that were washed in normal fish water to an incubator for between 8-16 hr at 28 &#176;C.</li>
	<li>At various times between 8-16 hr, fish are removed from the incubator, washed and stained as indicated in steps 2.1-2.4. Proceed to step 3.1 for observation of vital dye stained fish.</li>
</ol>
3. Anesthetizing Fish and Fluorescent Counting of Neuromasts
<ol>
	<li>Blot each fish on a paper towel to remove excess fluid and then place it on a dampened piece of filter paper that is centered on the lid of a plastic Petri dish.</li>
	<li>Place the lid on the stage of a fluorescent stereo microscope to obtain a digital image of the vital dye stained neuromasts of the mid body stitches.</li>
	<li>Use a digital camera placed on the fluorescent stereo microscope set a magnification of 2X to capture images for subsequent quantitative analysis. Note: The magnification setting of the stereo microscope may depend on the brand of microscope used, but the setting should allow easy viewing and counting of individual neuromasts within the mid body stitches.</li>
	<li>Determine the amount of regeneration by counting the number of visible neuromasts within the four designated stitches on the bottom-most ventral side of the fish just proximal to the right pectoral fin (see Figure 1). For statistical analysis use an appropriate test such as ANOVA or the Student's T-test. Experiments should utilize a minimum of 5 fish per time point and all experiments should be repeated a minimum of 3x.</li>
	<li>Based on the neuromast regeneration time curve (see Figure 3), count neuromasts between 8-16 hr post gentamicin wash-out to be within the linear phase of the regeneration curve. Note: Use of the linear time phase allows for proper quantitative analysis between the control and experimental groups.</li>
</ol>
4. Fluorescent Counting of Individual Hair Cells for Obtaining Higher Resolution of the Quantitative Analysis if the Neuromast Analysis is Not Statistically Significant
<ol>
	<li>If the quantitative analysis at the level of neuromasts is not significant, analysis at the level of the individual hair cell can also be utilized to obtain a higher degree of resolution. Select fish at a particular time point post gentamicin wash-out (time point based on the earlier neuromast studies), vital dye stain the fish as described in Protocol 2, and then euthanize the fish using 2-phenoxyethanol at a 1:500 dilution for 1-5 min.</li>
	<li>In subdued light to prevent quenching, make four incisions so that a square skin flap preparation is made as follows. Make an incision along the upper ribs of the fish until it is aligned with the anal fins, then make an incision across the belly, and finally, make two vertical incisions on each side of these incisions so the square skin flap is created. Note: This skin preparation will incorporate the mid body stitches used in the neuromast experiments.</li>
	<li>Place the skin specimen on a glass slide and then place a circular glass cover slip over the excised skin specimen to help anchor and flatten the tissue for subsequent digital imaging.</li>
	<li>Using the skin specimens from step 4.3, obtain digital images of the hair cells within each neuromast of the mid body stitches. Take images at a magnification of at least 60X and then count the hair cells within individual neuromasts for comparative quantitative analysis of the control and experimental groups (see Figure 4).</li>
</ol>

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This work was supported by a research grant from the Iacocca Family Foundation, National Institutes of Health Grant DK092721 (to R.V.I.), and Rosalind Franklin University start-up funds. No potential conflicts of interest relevant to this article were reported. G.C.P., S.M.M, and N.D. researched data. M.P.S. Jr. and RI oversaw the project, contributed to the discussion of the data, and oversaw the writing and editing of the manuscript.

Based on the extensive body of literature that has been established for analysis of lateral line (LL) regeneration in embryonic and larval zebrafish8,24,25, the goal of our study was to develop a quantitative assay for lateral line regeneration in zebrafish that could be applied to disease models that are best studied in the adult fish. We found that certain critical points are important when applying procedures developed for embryonic/larval fish to the adult fish. The most important of these points regarded:...

The lateral line (LL) system is a mechanosensory organ found in both fish and amphibians that is responsible for hearing, balance, rheotaxis and mediating behaviors such as schooling and predator avoidance1-5. It is composed of clusters of hair cells surrounded by supporting cells, both of which are positioned in structures called neuromasts6. These neuromasts are typically organized into vertical lines (called stitches) along the longitudinal axis of the body and tail with some horizontal stitches observed in the head of the fish. In the adult, neuromasts are significantly greater in number within the stitches as compared to embryonic or larval fish6. Biomedical studies in zebrafish have focused on the effect of antibiotic treatment, noise-induced trauma, chronic infection, etc. on hair cells7,8 in an attempt to better understand their effects in humans.
Unlike most vertebrates, teleosts, such as the zebrafish (Danio rerio), have the ability to regenerate lost hair cells. Zebrafish are particularly useful because of their rapid development time and high regenerative capacity. To date, however; zebrafish studies on lateral line development and/or regeneration have mainly utilized the embryonic and larval stage fish due to the reduced number of lateral line neuromasts which allows for easier counting and analysis6,9,10.
However, as many zebrafish models of neurological and non-neurological diseases11-16 are studied in the adult fish and not the larvae, we focused on developing a lateral line regenerative assay in adult zebrafish using gentamicin (an aminoglycoside previously used in zebrafish larvae and more recently used with adult fish17)&#160;so that an assay was available that could be applied to current adult zebrafish disease models. While previously published procedures by Van Trump et al.17 established the conditions for hair cell ablation in the adult fish, they did not establish a standard curve for neuromast regeneration which is required for quantitative comparison between control and experimental groups such as when using transgenic zebrafish lines or pharmacologically-induced disease states in zebrafish18. We therefore followed the procedures of Van Trump et al.17 for hair cell ablation, but built on their work to establish a standard curve of neuromast regeneration to enable investigators to use our data when comparing control and experimental groups such as with adult zebrafish disease models. The assay was also designed to allow extension of the analysis to the individual hair cell when a higher level of resolution is required.

<table border="0" cellpadding="0" cellspacing="0" width="431">
	<tbody>
		<tr>
			<td>Gentamicin sulfate solution (50mg/ml)</td>
			<td>Sigma Aldrich</td>
			<td>G1397</td>
			<td></td>
		</tr>
		<tr>
			<td>2 Phenoxyethanol</td>
			<td>Sigma Aldrich</td>
			<td>P1126</td>
			<td></td>
		</tr>
		<tr>
			<td>4-4-diethylaminostryryl-N-methylpyridinium iodide (4-Di-2-Asp)</td>
			<td>Aldrich</td>
			<td>D-3418</td>
			<td>485 nm excitation &#955; and 603 nm emission &#955;</td>
		</tr>
		<tr>
			<td>in methanol</td>
		</tr>
		<tr>
			<td>6 well plates</td>
			<td>Mid Sci</td>
			<td>TP92006</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri Dishes</td>
			<td>Fisher Scientific</td>
			<td>08-757-13</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass Bottom Microwell Dishes</td>
			<td>Matek Corporation</td>
			<td>P35G-1.5-14-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Sigma Aldrich</td>
			<td>S3014</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting&#160; Microscope</td>
			<td>Nikon</td>
			<td>TMZ-1500</td>
			<td>Any dissecting microscope is fine.</td>
		</tr>
		<tr>
			<td>Camera for Imaging</td>
			<td>Nikon</td>
			<td>Q imaging</td>
			<td>Any camera is suitable.</td>
		</tr>
		<tr>
			<td>Image J software</td>
			<td>National Institutes of Health</td>
			<td>NIH Image</td>
			<td></td>
		</tr>
		<tr>
			<td>NIS Elements</td>
			<td>Nikon</td>
			<td></td>
			<td>Any imaging software is suitable.</td>
		</tr>
		<tr>
			<td>Confocal microscope</td>
			<td>Olympus</td>
			<td>FV10i</td>
			<td>Any high resolution fluorescent microscope is suitable</td>
		</tr>
		<tr>
			<td>Aquatic System</td>
			<td>&#160;KG Aquatics ZFS Rack System.</td>
			<td></td>
			<td>Any aquatic system can be used</td>
		</tr>
	</tbody>
</table>

an assay for lateral line regeneration in adult zebrafish

Due to the clinical importance of hearing and balance disorders in man, model organisms such as the zebrafish have been used to study lateral line development and regeneration. The zebrafish is particularly attractive for such studies because of its rapid development time and its high regenerative capacity. To date, zebrafish studies of lateral line regeneration have mainly utilized fish of the embryonic and larval stages because of the lower number of neuromasts at these stages. This has made quantitative analysis of lateral line regeneration/and or development easier in the earlier developmental stages. Because many zebrafish models of neurological and non-neurological diseases are studied in the adult fish and not in the embryo/larvae, we focused on developing a quantitative lateral line regenerative assay in adult zebrafish so that an assay was available that could be applied to current adult zebrafish disease models. Building on previous studies by Van Trump et al.17&#160;that described procedures for ablation of hair cells in adult Mexican blind cave fish and zebrafish (Danio rerio), our assay was designed to allow quantitative comparison between control and experimental groups. This was accomplished by developing a regenerative neuromast standard curve based on the percent of neuromast reappearance over a 24 hr time period following gentamicin-induced necrosis of hair cells in a defined region of the lateral line. The assay was also designed to allow extension of the analysis to the individual hair cell level when a higher level of resolution is required.

Optimization of the procedures for quantifying neuromast regeneration of the lateral line in adult zebrafish.
The neuromasts of larval zebrafish are readily quantifiable; however, the lateral line of the adult zebrafish has a much greater number of neuromasts per stitch making quantitative analyses more difficult6,17,19,20. As seen in Figure 1A, the head has a significantly higher number of neuromasts compared to either the mid-section or tail; with...

Watch this Scientific Journal Video about An Assay for Lateral Line Regeneration in Adult Zebrafish at JoVE.com

An Assay for Lateral Line Regeneration in Adult Zebrafish

Because many zebrafish models of neurological and non-neurological diseases are studied in the adult fish rather than the embryo/larvae, we developed a quantitative lateral line regenerative assay that can be applied to adult zebrafish disease models. The assay involved resolution at the 1) neuromast and 2) individual hair cell levels.

Due to the clinical importance of hearing and balance disorders in man, model organisms such as the zebrafish have been used to study lateral line ...

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12.5K Views.  Dr. William M Scholl College of Podiatric Medicine, Rosalind Franklin University of Medicine and Science. Because many zebrafish models of neurological and non-neurological diseases are studied in the adult fish rather than the embryo/larvae, we developed a quantitative lateral line regenerative assay that can be applied to adult zebrafish disease models. The assay involved resolution at the 1) neuromast and 2) individual hair cell levels.

Video: An Assay for Lateral Line Regeneration in Adult Zebrafish

Transplantation of Whole Kidney Marrow in Adult Zebrafish

Hematopoietic stem cells (HSC) are a rare population of pluripotent cells that maintain all the differentiated blood lineages throughout the life of an organism. The functional definition of a HSC is a transplanted cell that has the ability to reconstitute all the blood lineages of an irradiated recipient long term. This designation was established by decades of seminal work in mammalian systems. Using hematopoietic cell transplantation (HCT) and reverse genetic manipulations in the mouse, the underlying regulatory factors of HSC biology are beginning to be unveiled, but are still largely under-explored. Recently, the zebrafish has emerged as a powerful genetic model to study vertebrate hematopoiesis. Establishing HCT in zebrafish will allow scientists to utilize the large-scale genetic and chemical screening methodologies available in zebrafish to reveal novel mechanisms underlying HSC regulation. In this article, we demonstrate a method to perform HCT in adult zebrafish. We show the dissection and preparation of zebrafish whole kidney marrow, the site of adult hematopoiesis in the zebrafish, and the introduction of these donor cells into the circulation of irradiated recipient fish via intracardiac injection. Additionally, we describe the post-transplant care of fish in an "ICU" to increase their long-term health. In general, gentle care of the fish before, during, and after the transplant is critical to increase the number of fish that will survive more than one month following the procedure, which is essential for assessment of long term (&lt;3 month) engraftment. The experimental data used to establish this protocol will be published elsewhere. The establishment of this protocol will allow for the merger of large-scale zebrafish genetics and transplant biology.

In this article, we demonstrate a method to perform HCT in adult zebrafish.

Hematopoietic stem cells (HSC) are a rare population of pluripotent cells that maintain all the differentiated blood lineages throughout the life of an ...

Cellular Toxicity of Nanogenomedicine in MCF-7 Cell Line: MTT assay

Cytotoxicity of the futuristic nanogenomedicine (e.g., short interfering RNA and antisense) may hamper its clinical development. Of these, the gene-based medicine and/or its carrier may elicit cellular toxicity. For assessment of such cytotoxicity, a common methodology is largely dependent upon utilization of the 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assay which has been widely used as a colorimetric approach based on the activity of mitochondrial dehydrogenase enzymes in cells. In this current investigation, MCF-7 cells were inoculated in 96-well plate and at 50% confluency they were treated with different nanopolyplexes and subjected to MTT assay after 24 hours. Water soluble yellow MTT is metabolized by the metabolically active cells to the water insoluble purple formazan, which is further dissolved in dimethylsulfoxide and Sornson s buffer pH 10.5. The resultant product can be quantified by spectrophotometry using a plate reader at 570 nm.

The MTT assay is an easy and reproducible colorimetric assay for evaluation of cell viability based on reduction of yellow MTT and production of water insoluble purple formazan. Here, the viability of MCF-7 cells upon treatment of nanogenomedicine has been evaluated.

Cytotoxicity of the futuristic nanogenomedicine (e.g., short interfering RNA and antisense) may hamper its clinical development. Of these, the gene-based ...

Retro-orbital Injection in Adult Zebrafish

Drug treatment of whole animals is an essential tool in any model system for pharmacological and chemical genetic studies. Intravenous (IV) injection is often the most effective and noninvasive form of delivery of an agent of interest. In the zebrafish (Danio rerio), IV injection of drugs has long been a challenge because of the small vessel diameter. This has also proved a significant hurdle for the injection of cells during hematopoeitic stem cell transplantation. Historically, injections into the bloodstream were done directly through the heart. However, this intra-cardiac procedure has a very high mortality rate as the heart is often punctured during injection leaving the fish prone to infection, massive blood loss or fatal organ damage. Drawing on our experience with the mouse, we have developed a new injection procedure in the zebrafish in which the injection site is behind the eye and into the retro-orbital venous sinus. This retro-orbital (RO) injection technique has been successfully employed in both the injection of drugs in the adult fish as well as transplantation of whole kidney marrow cells. RO injection has a much lower mortality rate than traditional intra-cardiac injection. Fish that are injected retro-orbitally tend to bleed less following injection and are at a much lower risk of injury to a major organ like the heart. Further, when performed properly, injected cells and/or drugs quickly enter the bloodstream allowing compounds to exert their effect on the whole fish and kidney cells to easily home to their niche. Thus, this new injection technique minimizes mortality while allowing efficient delivery of material into the bloodstream of adult fish. Here we exemplify this technique by retro-orbital injection of Tg(globin:GFP) cells into adult casper fish as well as injection of a red fluorescent dye (dextran, Texas Red ) into adult casper fish. We then visualize successful injections by whole animal fluorescence microscopy.

Here we show how to do retro-orbital injection in adult zebrafish.

Drug treatment of whole animals is an essential tool in any model system for pharmacological and chemical genetic studies. Intravenous (IV) injection is ...

Intraperitoneal Injection into Adult Zebrafish

A convenient method for chemically treating zebrafish is to introduce the reagent into the tank water, where it will be taken up by the fish. However, this method makes it difficult to know how much reagent is absorbed or taken up per fish. Some experimental questions, particularly those related to metabolic studies, may be better addressed by delivering a defined quantity to each fish, based on weight. Here we present a method for intraperitoneal (IP) injection into adult zebrafish. Injection is into the abdominal cavity, posterior to the pelvic girdle. This procedure is adapted from veterinary methods used for larger fish. It is safe, as we have observed zero mortality. Additionally, we have seen bleeding at the injection site in only 5 out of 127 injections, and in each of those cases the bleeding was brief, lasting several seconds, and the quantity of blood lost was small. Success with this procedure requires gentle handling of the fish through several steps including fasting, weighing, anesthetizing, injection, and recovery. Precautions are required to minimize stress throughout the procedure. Our precautions include using a small injection volume and a 35G needle. We use Cortland salt solution as the vehicle, which is osmotically balanced for freshwater fish. Aeration of the gills is maintained during the injection procedure by first bringing the fish into a surgical plane of anesthesia, which allows slow operculum movements, and second, by holding the fish in a trough within a water-saturated sponge during the injection itself. We demonstrate the utility of IP injection by injecting glucose and monitoring the rise in blood glucose level and its subsequent return to normal. As stress is known to increase blood glucose in teleost fish, we compare blood glucose levels in vehicle-injected and non-injected adults and show that the procedure does not cause a significant rise in blood glucose.

We demonstrate intraperitoneal injection into adult zebrafish. We use a 10 &mu;l NanoFil microsyringe controlled by a Micro4 controller and UltraMicroPump III. This demonstration includes the use of cold water as an anesthetic.

A convenient method for chemically treating zebrafish is to introduce the reagent into the tank water, where it will be taken up by the fish. However, ...

In vivo Electroporation of Morpholinos into the Adult Zebrafish Retina

Many devastating inherited eye diseases result in progressive and irreversible blindness because humans cannot regenerate dying or diseased retinal neurons. In contrast, the adult zebrafish retina possesses the robust ability to spontaneously regenerate any neuronal class that is lost in a variety of different retinal damage models, including retinal puncture, chemical ablation, concentrated high temperature, and intense light treatment 1-8. Our lab extensively characterized regeneration of photoreceptors following constant intense light treatment and inner retinal neurons after intravitreal ouabain injection 2, 5, 9. In all cases, resident M&uuml;ller glia re-enter the cell cycle to produce neuronal progenitors, which continue to proliferate and migrate to the proper retinal layer, where they differentiate into the deficient neurons. 
	We characterized five different stages during regeneration of the light-damaged retina that were highlighted by specific cellular responses. We identified several differentially expressed genes at each stage of retinal regeneration by mRNA microarray analysis 10. Many of these genes are also critical for ocular development. To test the role of each candidate gene/protein during retinal regeneration, we needed to develop a method to conditionally limit the expression of a candidate protein only at times during regeneration of the adult retina. 
	Morpholino oligos are widely used to study loss of function of specific proteins during the development of zebrafish, Xenopus, chick, mouse, and tumors in human xenografts 11-14. These modified oligos basepair with complementary RNA sequence to either block the splicing or translation of the target RNA. Morpholinos are stable in the cell and can eliminate or "knockdown" protein expression for three to five days 12. 
	Here, we describe a method to efficiently knockdown target protein expression in the adult zebrafish retina. This method employs lissamine-tagged antisense morpholinos that are injected into the vitreous of the adult zebrafish eye. Using electrode forceps, the morpholino is then electroporated into all the cell types of the dorsal and central retina. Lissamine provides the charge on the morpholino for electroporation and can be visualized to assess the presence of the morpholino in the retinal cells. 
	Conditional knockdown in the retina can be used to examine the role of specific proteins at different times during regeneration. Additionally, this approach can be used to study the role of specific proteins in the undamaged retina, in such processes as visual transduction and visual processing in second order neurons.

In vivo Electroporation of Morpholinos into the Adult Zebrafish Retina

A method to conditionally knockdown a target protein&#x2019;s expression in the adult zebrafish retina is described, which involves intravitreally injecting antisense morpholinos and electroporating them into the retina. The resulting protein is knocked down for several days, which allows testing the protein&#x2019;s role in the regenerating or intact retina.

Many devastating inherited eye diseases result in progressive and irreversible blindness because humans cannot regenerate dying or diseased retinal ...

In vivo Electroporation of Morpholinos into the Regenerating Adult Zebrafish Tail Fin

Certain species of urodeles and teleost fish can regenerate their tissues. Zebrafish have become a widely used model to study the spontaneous regeneration of adult tissues, such as the heart1, retina2, spinal cord3, optic nerve4, sensory hair cells5, and fins6.
The zebrafish fin is a relatively simple appendage that is easily manipulated to study multiple stages in epimorphic regeneration. Classically, fin regeneration was characterized by three distinct stages: wound healing, blastema formation, and fin outgrowth. After amputating part of the fin, the surrounding epithelium proliferates and migrates over the wound. At 33 &deg;C, this process occurs within six hours post-amputation (hpa, Figure 1B)6,7. Next, underlying cells from different lineages (ex. bone, blood, glia, fibroblast) re-enter the cell cycle to form a proliferative blastema, while the overlying epidermis continues to proliferate (Figure 1D)8. Outgrowth occurs as cells proximal to the blastema re-differentiate into their respective lineages to form new tissue (Figure 1E)8. Depending on the level of the amputation, full regeneration is completed in a week to a month.
The expression of a large number of gene families, including wnt, hox, fgf, msx, retinoic acid, shh, notch, bmp, and activin-betaA genes, is up-regulated during specific stages of fin regeneration9-16. However, the roles of these genes and their encoded proteins during regeneration have been difficult to assess, unless a specific inhibitor for the protein exists13, a temperature-sensitive mutant exists or a transgenic animal (either overexpressing the wild-type protein or a dominant-negative protein) was generated7,12. We developed a reverse genetic technique to quickly and easily test the function of any gene during fin regeneration.
Morpholino oligonucleotides are widely used to study loss of specific proteins during zebrafish, Xenopus, chick, and mouse development17-19. Morpholinos basepair with a complementary RNA sequence to either block pre-mRNA splicing or mRNA translation. We describe a method to efficiently introduce fluorescein-tagged antisense morpholinos into regenerating zebrafish fins to knockdown expression of the target protein. The morpholino is micro-injected into each blastema of the regenerating zebrafish tail fin and electroporated into the surrounding cells. Fluorescein provides the charge to electroporate the morpholino and to visualize the morpholino in the fin tissue.
This protocol permits conditional protein knockdown to examine the role of specific proteins during regenerative fin outgrowth. In the Discussion, we describe how this approach can be adapted to study the role of specific proteins during wound healing or blastema formation, as well as a potential marker of cell migration during blastema formation.

In vivo Electroporation of Morpholinos into the Regenerating Adult Zebrafish Tail Fin

We describe a method to conditionally knockdown the expression of a target protein during adult zebrafish fin regeneration. This technique involves micro-injecting and electroporating antisense oligonucleotide morpholinos into fin tissue, which allows testing the protein&#x2019;s role in various stages of fin regeneration, including wound healing, blastema formation, and regenerative outgrowth.

Certain species of urodeles and teleost fish can regenerate their tissues. Zebrafish have become a widely used model to study the spontaneous regeneration ...

Blood Collection for Biochemical Analysis in Adult Zebrafish

The zebrafish has been used as an animal model for studies of several human diseases. It can serve as a powerful preclinical platform for studies of molecular events and therapeutic strategies as well as for evaluating the physiological mechanisms of some pathologies1. 
There are relatively few publications related to adult zebrafish physiology of organs and systems2, which may lead researchers to infer that the basic techniques needed to allow the exploration of zebrafish systems are lacking3. Hematologic biochemical values of zebrafish were first reported in 2003 by Murtha and colleagues4 who employed a blood collection technique first described by Jagadeeswaran and colleagues in 1999. Briefly, blood was collected via a micropipette tip through a lateral incision, approximately 0.3 cm in length, in the region of the dorsal aorta5. Because of the minute dimensions involved, this is a high-precision technique requiring a highly skilled practitioner. The same technique was used by the same group in another publication in that same year6. In 2010, Eames and colleagues assessed whole blood glucose levels in zebrafish7. They gained access to the blood by performing decapitations with scissors and then inserting a heparinized microcapillary collection tube into the pectoral articulation. They mention difficulties with hemolysis that were solved with an appropriate storage temperature based on the work Kilpatrick et al.8. When attempting to use Jagadeeswaran's technique in our laboratory, we found that it was difficult to make the incision in precisely the right place as not to allow a significant amount of blood to be lost before collection could be started. 
Recently, Gupta et al.9 described how to dissect adult zebrafish organs, Kinkle et al.10 described how to perform intraperitoneal injections, and Pugach et al.11 described how to perform retro-orbital injections. However, more work is needed to more fully explore basic techniques for research in zebrafish.
The small size of zebrafish presents challenges for researchers using it as an experimental model. Furthermore, given this smallness of scale, it is important that simple techniques are developed to enable researchers to explore the advantages of the zebrafish model.

This paper presents a technique for collection of blood from the dorsal aorta of Zebrafish. It also provides instructions for obtaining serum for use in biochemical analyses, such as tests for determining cholesterol and triglyceride levels.

The zebrafish has been used as an animal model for studies of several human diseases. It can serve as a powerful preclinical platform for studies of ...

Gavaging Adult Zebrafish

The zebrafish has become an important in vivo model in biomedical research. Effective methods must be developed and utilized to deliver compounds or agents in solutions for scientific research. Current methods for administering compounds orally to adult zebrafish are inaccurate due to variability in voluntary consumption by the fish. A gavage procedure was developed to deliver precise quantities of infectious agents to zebrafish for study in biomedical research. Adult zebrafish over 6 months of age were anesthetized with 150 mg/L of buffered MS-222 and gavaged with 5 &mu;l of solution using flexible catheter implantation tubing attached to a cut 22-G needle tip. The flexible tubing was lowered into the oral cavity of the zebrafish until the tip of the tubing extended past the gills (approximately 1 cm). The solution was then injected slowly into the intestinal tract. This method was effective 88% of the time, with fish recovering uneventfully. This procedure is also efficient as one person can gavage 20-30 fish in one hour. This method can be used to precisely administer agents for infectious diseases studies, or studies of other compounds in adult zebrafish.

The increasing use of zebrafish as an animal model requires the development of effective methods for the delivery of known quantities of compounds and solutions. The gavage procedure described below allows for the oral delivery of precise volumes of solution reliably, safely and efficiently to adult zebrafish.

The zebrafish has become an important in vivo model in biomedical research. Effective methods must be developed and utilized to deliver compounds or ...

Repeated Blood Collection for Blood Tests in Adult Zebrafish

Repeated blood collection is one of the most common techniques performed on laboratory animals. However, a non-lethal protocol for blood collection from zebrafish has not been established. The previous methods for blood collection from zebrafish are lethal, such as lateral incision, decapitation and tail ablation. Thus we have developed a novel &#8220;repeated&#8221; blood collection method, and present here a detailed protocol outlining this procedure. This method is minimally invasive and results in a very low mortality rate (2.3%) for zebrafish, thus enabling repeated blood sampling from the same individual. The maximum volume of blood sampling is dependent on body weight of the fish. The volume for repeated blood sampling at intervals should be&#160;&#8804;0.4% of body weight every week or &#8804;1% every 2 weeks, which were evaluated by measurements of blood hemoglobin. Additionally, hemoglobin, fasting blood glucose, plasma triacylglycerol (TG) and total cholesterol levels in male and female adult zebrafish were measured. We also applied this method to investigate the dysregulation of glucose metabolism in diet-induced obesity. This blood collection method will allow many applications, including glucose and lipid metabolism and hematological studies, which will increase the use of zebrafish as a human disease model organism.

Repeated blood sampling is necessary and important in animal research. We developed a novel, non-lethal and reliable method for repeated blood collection from adult zebrafish, and applied this method to the study of blood biochemistry, including glucose metabolism.

Repeated blood collection is one of the most common techniques performed on laboratory animals. However, a non-lethal protocol for blood collection from ...

In Vivo Surface Electrocardiography for Adult Zebrafish

The electrocardiogram waveforms of adult zebrafish and those of humans are remarkably similar. These electrocardiogram similarities enhance the value of zebrafish not only as a research model for human cardiac electrophysiology and myopathies but also as a surrogate model in high throughput pharmaceutical screening for potential cardiotoxicities to humans, such as QT prolongation. As such, in vivo electrocardiography for adult zebrafish is an electrical phenotyping tool that is necessary, if not indispensable, for cross-sectional or longitudinal in vivo electrophysiological characterizations. However, too often, the lack of a reliable, practical, and cost-effective recording method remains a major challenge preventing this in vivo diagnostic tool from becoming more readily accessible. Here, we describe a practical, straightforward approach to in vivo electrocardiography for adult zebrafish using a low-maintenance, cost-effective, and comprehensive system that yields consistent, reliable recordings. We illustrate our protocol using healthy adult male zebrafish of 12-18 months of age. We also introduce a rapid real-time interpretation strategy for quality validation to ensure data accuracy and robustness early in the electrocardiogram recording process.

Here, we present a reliable, minimally invasive, and cost-effective method to record and interpret electrocardiograms in live anesthetized adult zebrafish.

The electrocardiogram waveforms of adult zebrafish and those of humans are remarkably similar. These electrocardiogram similarities enhance the value of ...