The authors would like to thank Dr. Shaun Coughlin for hosting the filming of this procedure in his laboratory, and for general support. R.A. was supported by the NIH (F32HL110489) and the Sarnoff Cardiovascular Research Foundation. S.R. was supported by a Research Fellowship of the Deutsche Forschungsgemeinschaft (DFG) and the American Heart Association (AHA). D.Y.R.S was supported by the NIH (RO1HL54737), the Packard Foundation, and the Max Planck Society.

NOTE: Always be sure that IACUC or ethics committee approval is in place before beginning any experimental procedure using zebrafish.
1. Prepare reagents and setup
<ol>
	<li>Prepare the following solutions. Find the recipes for all of these solutions in standard zebrafish manuals10.
	<ul>
		<li>500 ml of Egg Water</li>
		<li>200 ml of 0.03% Tricaine in Egg Water</li>
		<li>100 ml of 1x Phosphate-Buffered Saline (PBS)</li>
		<li>RBC Lysis Buffer (optional)</li>
		<li>Destination buffer of choice (fixative, Trizol, PBS, etc.) in a 1.5 ml microfuge tube on ice 
		NOTE: Fixative and Trizol are toxic if they come into contact with skin. Wear gloves when handling these substances.</li>
	</ul>
	</li>
	<li>Prepare dissection setup:
	<ol>
		<li>Position the gooseneck light source over the dissecting microscope. Place the lid of a 9 cm Petri dish on the dissecting microscope stage, and pour a thin layer of 1x PBS into it (the lid is used because the dish itself is too deep for an easy dissection).</li>
		<li>Place the Petri dish itself (not the lid) on the countertop near the dissecting scope and pour approximately 15 ml of 1x PBS in it. Use this to wash the heart after dissection. Alternatively, use RBC Lysis Buffer.</li>
		<li>Place razor blade, two pairs of forceps, microscissors (optional), and a transfer pipette beside the microscope. Obtain a container of ice if euthanasia by rapid cooling is chosen.</li>
		<li>Pour 200 ml of 0.03% Tricaine in Egg Water into a 250 ml glass beaker if euthanasia by Tricaine is chosen. Prepare a small biohazard bag for disposal of zebrafish carcasses.</li>
	</ol>
	</li>
</ol>
2. Prepare Zebrafish
<ol>
	<li>For fixed fish, bring fixed fish, rinsed in PBS, to the microscope setup.
	<ol>
		<li>Euthanize the whole adult zebrafish by rapid cooling with ice for &#62;10 min.</li>
		<li>Use forceps to make a hole in the skin over the peritoneum (away from the heart) to aid penetration of fixative, and then put them in 4% paraformaldehyde in Fix Buffer10 for 2 hr at RT or O/N at 4 &#176;C.</li>
	</ol>
	</li>
	<li>Alternatively, for fresh fish, place fish to be euthanized in a small holding tank and bring to the microscope setup. Depending on the individual facility&#8217;s fish protocol and the downstream uses for the dissected fish hearts, anesthetize fish with Tricaine or euthanize by rapid cooling before decapitation.
	<ol>
		<li>To use ice, pick up one fish with the fish net and place in ice water until the fish stops moving, approximately 5 min.</li>
		<li>Alternatively, to use Tricaine, pick up one fish with the fish net and place in the beaker of the solution until gill movements stop.</li>
	</ol>
	</li>
	<li>Quickly pick up the euthanized fish by its tail fin and lay it on its side in the Petri dish cover that was filled with 1x PBS. Use the forceps to lift a pectoral fin with one hand, while using the razor blade to decapitate the fish with the other hand, just posterior to the attachment of the pectoral fin (Figure 1A). Perform this step either by looking through the microscope or by just directly visualizing the fish on the microscope stage. 
	NOTE: Freshly euthanized fish will still bleed after decapitation.</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/52248/52248fig1highres.jpg" /> 
Figure 1. Zebrafish adult heart dissection utilizes zebrafish anatomical landmarks. (A) To decapitate the fish, lift the pectoral fin with a forceps and use a sharp clean razor blade along the red dotted line as shown. (B) To steady the fish head, place one tine of the forceps in the fish mouth while the other tine lies across the eye, and then turn the fish head so that the ventral surface is up and both tines of the forceps are stable against the bottom of the Petri dish. (C) Use the free forceps to cut the attachment of the operculum (arrow). (D) Lifting this, the dorsal aorta is visible as a white structure with a pink stripe denoting luminal blood (arrow). <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52248/52248fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
3. Dissect the Heart
<ol>
	<li>Visualize the fish head under the microscope. With one forceps, steady the fish head by placing one tine of the forceps in the fish mouth, through the brain, while the other tine is outside the head, across the eye (Figure 1B). Ensure both tines of the forceps are steady against the bottom of the petri dish. Holding the fish head this way, its ventral surface should be facing upwards.</li>
	<li>With the other hand, use the second forceps to cut the ventral attachment of the operculum to the body (arrow, Figure 1C). Lifting this slightly with the forceps, the dorsal aorta will appear underneath as a white structure with a red stripe of blood in the aortic lumen (arrow, Figure 1D). Cut the dorsal aorta with the forceps by pinching the aorta and pulling upwards; alternatively, use microscissors to cut the dorsal aorta.</li>
	<li>Now, use the second forceps to grasp the pectoral fin from its base, including the body cartilage at the base of the fin, and lift this off. Repeat with the other pectoral fin. Occasionally, the heart comes out with the pectoral fins, so examine these pieces to make sure the heart is not attached before discarding them. 
	NOTE: At this point, the heart should be visible, still intact and connected to the remaining fish head (although occasionally it comes off with the pectoral fins). The heart can be identified by its shape, its pink color, and its being surrounded by pigmented pericardium. Because euthanasia of the fish is performed quickly, freshly euthanized fish hearts may still be beating slowly.</li>
	<li>Let go of the fish head with the first forceps, so that both hands hold forceps and are free. Use both forceps to tease the heart away from the pericardium. Grasp the heart by the remainder of the dorsal aorta while the remaining pericardium is pulled away. 
	NOTE: Whether fixed or fresh, the heart is robust to gentle pulling while the surrounding connective tissue is more friable. Therefore, any surrounding pericardial tissue can be dissected away with the heart remaining intact.</li>
	<li>Discard the leftover fish carcass in the biohazard bag.</li>
</ol>
4. Prepare the Heart for Downstream Applications
<ol>
	<li>Using forceps, grasp the heart by the edge of the dorsal aorta/bulbus arteriosus and place the heart in the fresh dish of 1x PBS. Alternatively, use a transfer pipette. Move the heart back and forth in the PBS about 10x to wash away as much blood as possible.</li>
	<li>For applications in which it is important to remove all possible blood cells, wash in a 9 cm Petri dish with 15 ml RBC Lysis Buffer instead of PBS, using the same back-and-forth motion. If preserving the structure of the heart is not important for the downstream application (e.g., making RNA), use the forceps or microscissors to open the heart cavity and facilitate rinsing away of blood cells.</li>
	<li>For applications in which separate heart chambers are desired, use forceps or microscissors to dissect the bulbus arteriosus, atrium, and ventricle apart from each other.</li>
	<li>Transfer the heart, or separate chambers, to the destination buffer on ice. 
	NOTE: Common destinations include buffers for cell dissociation, 4% paraformaldehyde, or Trizol.</li>
</ol>

<ol>
	<li>Arnaout, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zebrafish+model+for+human+long+QT+syndrome.">Zebrafish model for human long QT syndrome.</a> Proceedings of the National Academy of Sciences of the United States of America. 104 (27), 11316-11321 (2007).</li><li>Chi, N. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+and+physiologic+dissection+of+the+vertebrate+cardiac+conduction+system.">Genetic and physiologic dissection of the vertebrate cardiac conduction system.</a> PLoS Biology. 6 (5), 109 (2008).</li><li>Poss, K. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Getting+to+the+heart+of+regeneration+in+zebrafish.">Getting to the heart of regeneration in zebrafish.</a> Seminars in Cell &amp; Developmental Biology. 18 (1), 36-45 (2007).</li><li>Fang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Translational+profiling+of+cardiomyocytes+identifies+an+early+Jak1/Stat3+injury+response+required+for+zebrafish+heart+regeneration.">Translational profiling of cardiomyocytes identifies an early Jak1/Stat3 injury response required for zebrafish heart regeneration.</a> Proceedings of the National Academy of Sciences of the United States of America. 110 (33), 13416-13421 (2013).</li><li>Manoli, M., Driever, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescence-activated+cell+sorting+(FACS)+of+fluorescently+tagged+cells+from+zebrafish+larvae+for+RNA+isolation.">Fluorescence-activated cell sorting (FACS) of fluorescently tagged cells from zebrafish larvae for RNA isolation.</a> Cold Spring Harbor Protocols. 2012 (8), (2012).</li><li>Cannon, J. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Global+analysis+of+the+haematopoietic+and+endothelial+transcriptome+during+zebrafish+development.">Global analysis of the haematopoietic and endothelial transcriptome during zebrafish development.</a> Mechanisms of Development. 130 (2-3), 122-131 (2013).</li><li>Wang, Z., Gerstein, M., Snyder, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RNA-Seq:+a+revolutionary+tool+for+transcriptomics.">RNA-Seq: a revolutionary tool for transcriptomics.</a> Nature Reviews Genetics. 10 (1), 57-63 (2009).</li><li>Gupta, T., Mullins, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissection+of+organs+from+the+adult+zebrafish.">Dissection of organs from the adult zebrafish.</a> Journal of Visualized Experiments. 37, (2010).</li><li>Singleman, C., Holtzman, N. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+dissection+in+larval,+juvenile+and+adult+zebrafish,+Danio+rerio.">Heart dissection in larval, juvenile and adult zebrafish, Danio rerio.</a> Journal of Visualized Experiments. 55, (2011).</li><li>Westerfield, M. <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 zebrafish book: a guide for the laboratory use of zebrafish (Brachydanio rerio. , (1993).</li></ol>

The authors have no disclosures.

While methods for dissecting the adult zebrafish heart have been described, these methods were time-consuming and commonly caused damage to the heart during dissection. To perform experiments where a large number of adult hearts may be needed, and/or when avoiding degradation of heart tissue is important for downstream applications, the time required using traditional dissection techniques is prohibitive. Similarly, reproducibly obtaining undamaged, intact hearts is important for study of heart structure and for immunohistochemical and microscopy methods. We found that even in the hands of beginners, 100% of hearts dissected were recovered structurally intact. Overall, the method for adult heart dissection presented here presents an advance in technique that expands the use of adult zebrafish for a variety of current and future applications, including use in heart injury and regeneration experiments.
There are several critical steps within this protocol. First, depending on the experiment for which the zebrafish hearts are required, it is important to rinse hearts as much as possible from blood cells. Examples of experiments that would benefit from removing blood cells include recovery of hearts for RNA-Seq, where presence of blood will alter gene expression profiles, or for FACS sorting, where blood cells may be difficult to sort from myocardial cells. After the fish is euthanized with Tricaine or ice, it is important to decapitate the fish quickly and allow bleeding to occur to help rid the heart of excess blood. If an intact heart is not required for the planned experiment, it can be helpful to cut the atrium and ventricle open when in PBS to further rinse out the blood. RBC lysis buffer can also be used instead of PBS.
Second, as mentioned above, occasionally the heart comes off with one of the pectoral fins rather than staying attached to the head. Therefore, pull the pectoral fins off under the microscope so that the heart can be identified. Finally, when dissecting the heart away from surrounding pericardium, try not to grasp the heart itself; instead, grasp two pieces of pericardium and pull them both away from the heart, which has more structural integrity than the friable pericardium. In this way, even minimal damage to the heart can be avoided.
The heart should be easily identifiable by its shape and contractions. As an additional aid in finding the heart, one can dissect a heart expressing a fluorescent protein under a fluorescence dissecting microscope. This is usually not needed but may be useful for beginners and/or for dissections of very small hearts.
One limitation of this technique is that dissecting hearts from small fish, i.e., younger than 3 weeks old, is difficult; other techniques have been designed for larval dissections9. Also, while it is easy to dissect the bulbus arteriosus, atrium, and ventricle from each other, it is not possible to dissect the atrioventricular valve on its own. The valve remains attached to the ventricle in most cases.

Zebrafish are an excellent model for studying heart development and human disease1,2. Specific advantages include the translucent nature of zebrafish embryos, the availability of many genetic mutants and transgenic reporter lines, and the availability of genome editing technologies. In addition to their advantages for studying early heart development, zebrafish are an ideal system for studying vertebrate heart regeneration3.
More recently, adult zebrafish are playing an important part in bioinformatics approaches to studying cardiovascular development and disease, due to their relatively large clutch size and relatively quick and inexpensive breeding compared to other vertebrate models. Promising techniques include ribosome profiling, RNA-Seq, and cell dissociation and FACS sorting4-7. However, for these techniques the quality of the data can depend on obtaining a large number of samples in a rapid, efficient, and reproducible manner, before gene regulatory, metabolic, transcriptional, and other changes occur.
Dissection of adult zebrafish organs has been described in the past8,9. However, previous approaches to dissection of the heart were slow, ran the risk of damaging the heart during dissection, required special tools, and/or required fixation of the zebrafish prior to dissection; for these reasons, past approaches to zebrafish adult heart dissection were not optimized for high-throughput applications and/or applications requiring fresh tissue.
Here, we describe a method for adult zebrafish heart dissection that is simple, fast, efficient, and reproducible, while preserving cardiac morphology. This method does not include cutting into the pericardial space and therefore does not risk damaging the heart during dissection. Instead, this method relies on anatomical landmarks of the zebrafish, and therefore, it is highly reproducible. This dissection method is also versatile in that it can be used on fresh or fixed fish, and on zebrafish as young as one month old. Finally, this method results in minimal suffering to the zebrafish because after anesthesia and/or rapid cooling, the fish is additionally decapitated and pithed in the course of the dissection procedure.

<table border="0" cellpadding="0" cellspacing="0" >
	<tbody>
		<tr >
			<td >small tank for transporting fish</td>
			<td >Aquaneering</td>
			<td >ZHCT100</td>
			<td></td>
		</tr>
		<tr >
			<td >fish net</td>
			<td >Petsmart</td>
			<td >36-16731</td>
			<td></td>
		</tr>
		<tr >
			<td >250mL glass beaker</td>
			<td >Kimble</td>
			<td >14005-250</td>
			<td></td>
		</tr>
		<tr >
			<td >9cm polystyrene petri dish</td>
			<td >Nunc</td>
			<td >172958</td>
			<td></td>
		</tr>
		<tr >
			<td >razor blade</td>
			<td >Personna American Safety Razor Company</td>
			<td >94-120-71</td>
			<td></td>
		</tr>
		<tr >
			<td >two Dumont #5SF forceps</td>
			<td >Fine Science Tools</td>
			<td >11252-00</td>
			<td></td>
		</tr>
		<tr >
			<td >dissecting microscope</td>
			<td >Olympus</td>
			<td >SZX16</td>
			<td></td>
		</tr>
		<tr >
			<td >Tricaine</td>
			<td >Sigma</td>
			<td >A-5040</td>
			<td></td>
		</tr>
		<tr >
			<td >plastic transfer pipette</td>
			<td >Thermo Scientific</td>
			<td >202-20S</td>
			<td></td>
		</tr>
		<tr >
			<td >gooseneck light source</td>
			<td >Dolan-Jenner Industries, Inc</td>
			<td >Fiber-Lite 180 Illuminator, 181 Dual Gooseneck System</td>
			<td></td>
		</tr>
		<tr >
			<td >fluorescent light source</td>
			<td >Lumen Dynamics</td>
			<td >X-Cite 120Q</td>
			<td>optional</td>
		</tr>
		<tr >
			<td >micro-scissors</td>
			<td >Biomedical Research Instruments, Inc</td>
			<td >11-1000</td>
			<td>optional</td>
		</tr>
		<tr >
			<td >RBC Lysis Buffer</td>
			<td >eBioscience</td>
			<td >00-4333-57</td>
			<td>optional</td>
		</tr>
	</tbody>
</table>

recovery of adult zebrafish hearts for high-throughput applications

Use of the zebrafish model system for studying development, regeneration, and disease is expanding toward use of adult hearts for cell dissociation and purification of RNA, DNA, and proteins. All of these applications demand the rapid recovery of significant numbers of zebrafish hearts to avoid gene regulatory, metabolic, and other changes that begin after death. Adult zebrafish hearts are also required for studying heart structure for a variety of mutants and for studying heart regeneration. However, the traditional zebrafish heart dissection is slow and difficult and requires specialized tools, making large-scale dissection of adult zebrafish hearts tedious. Traditional methods also harbor the risk of damaging the heart during the dissection. Here, we describe a method for dissection of adult zebrafish hearts that is fast, reproducible, and preserves heart architecture. Furthermore, this method does not require specialized tools, is painless for the zebrafish, can be performed on fresh or fixed specimens, and can be performed on zebrafish as young as one month old. The approach described expands the use of adult zebrafish for cardiovascular research.

Using this method, an adult zebrafish heart can be dissected in less than 1 min, compared to over 5 min using traditional methods8. Hearts dissected using this method are reliably intact (Figure 2A), while traditional methods8 require cutting blindly into the pericardium and therefore commonly cause damage or loss of the atrium or bulbus arteriosus (Figure 2B). Hearts dissected maintain their structural integrity and are suitable for histology (Figure 2C), electron microscopy (Figure 2D), as well as for applications where the heart is dissociated or pulverized. In our hands, from a dissection of 50 hearts over the course of a week&#8217;s experiments, 50 hearts were obtained structurally intact. We also taught this technique to a colleague in the laboratory who had no experience with zebrafish dissection. 9 out of 9 hearts dissected by the beginner colleague were also structurally intact. This dissection method is suitable for juveniles older than 1 month old, and for adults of all ages.
<img alt="Figure 2" src="/files/ftp_upload/52248/52248fig2highres.jpg" /> 
Figure 2. Dissected hearts are intact and maintain architectural integrity. (A) In less than 1 min, an adult zebrafish heart with an intact atrium (A), ventricle (V), and bulbus arteriosus (BA) can be dissected from a euthanized fish. (B) Traditional adult zebrafish heart dissections take longer and even when care is taken, run the risk of damage. Here, only the ventricle is intact. (C) A heart dissected from a Tg(myl7dsRed) adult fish maintained its structural integrity for use in histology. The atrium (A), ventricle (V), and bulbus arteriosus (BA) are seen, and even smaller structures like the atrioventricular valve (AV, arrow) and the outflow tract (OFT, arrow) are intact. (D) Electron microscopy of a dissected wild-type adult heart shows that sarcomeres remain undamaged by the dissection process. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/52248/52248fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Recovery of Adult Zebrafish Hearts for High-throughput Applications at JoVE.com

Recovery of Adult Zebrafish Hearts for High-throughput Applications

Use of zebrafish for cardiovascular research is expanding towards research on adult hearts. For these applications, quick and simple isolation of cardiac tissues is key to avoid post-mortem changes and to obtain an adequate number of samples. Here, we describe a fast and reproducible method for dissecting adult zebrafish hearts.

Use of the zebrafish model system for studying development, regeneration, and disease is expanding toward use of adult hearts for cell dissociation and ...

recovery-of-adult-zebrafish-hearts-for-high-throughput-applications

Nanyang Technological University

Research

JoVE Journal

Biology

12.2K Views.  University of California San Francisco. Use of zebrafish for cardiovascular research is expanding towards research on adult hearts. For these applications, quick and simple isolation of cardiac tissues is key to avoid post-mortem changes and to obtain an adequate number of samples. Here, we describe a fast and reproducible method for dissecting adult zebrafish hearts.

Video: Recovery of Adult Zebrafish Hearts for High-throughput Applications

A High-Throughput Method For Zebrafish Sperm Cryopreservation and In Vitro Fertilization

This is a method for zebrafish sperm cryopreservation that is an adaptation of the Harvey method (Harvey et al., 1982).  We have introduced two changes to the original protocol that both streamline the procedure and increase sample uniformity.  First, we normalize all sperm volumes using freezing media that does not contain the cryoprotectant. Second, cryopreserved sperm are stored in cryovials instead of capillary tubes.  The rates of sperm freezing and thawing (&delta;&deg;C/time) are probably the two most critical variables to control in this procedure.  For this reason, do not substitute different tubes for those specified.  Working in teams of 2 it is possible to freeze the sperm of 100 males per team in ~2 hrs.  Sperm cryopreserved using this protocol has an average of 25% fertility (measured as the number of viable embryos generated in an in vitro fertilization divided by the total number of eggs fertilized) and this percent fertility is stable over many years.

A High-Throughput Method For Zebrafish Sperm Cryopreservation and In Vitro Fertilization

This is a high-throughput sperm cryopreservation protocol for zebrafish. Sperm cryopreserved using this protocol has an average of 25% fertility in subsequent vitro fertilization and is stable over many years.

This is a method for zebrafish sperm cryopreservation that is an adaptation of the Harvey method (Harvey et al., 1982).  We have introduced two changes to ...

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, ...

High-throughput Saccharification Assay for Lignocellulosic Materials

Polysaccharides that make up plant lignocellulosic biomass can be broken down to produce a range of sugars that subsequently can be 
used in establishing a biorefinery. These raw materials would constitute a new industrial platform, which is both sustainable and carbon neutral, to replace 
the current dependency on fossil fuel. The recalcitrance to deconstruction observed in lignocellulosic materials is produced by several intrinsic properties 
of plant cell walls. Crystalline cellulose is embedded in matrix polysaccharides such as xylans and arabinoxylans, and the whole structure is encased by the 
phenolic polymer lignin, that is also difficult to digest 1. In order to improve the digestibility of plant materials we need to discover the main bottlenecks 
for the saccharification of cell walls and also screen mutant and breeding populations to evaluate the variability in saccharification 2. These tasks require 
a high throughput approach and here we present an analytical platform that can perform saccharification analysis in a 96-well plate format. This platform has 
been developed to allow the screening of lignocellulose digestibility of large populations from varied plant species. We have scaled down the reaction volumes 
for gentle pretreatment, partial enzymatic hydrolysis and sugar determination, to allow large numbers to be assessed rapidly in an automated system.
This automated platform works with milligram amounts of biomass, performing ball milling under controlled conditions to reduce the plant 
materials to a standardised particle size in a reproducible manner. Once the samples are ground, the automated formatting robot dispenses specified and recorded 
amounts of material into the corresponding wells of 96 deep well plate (Figure 1). Normally, we dispense the same material into 4 wells to have 4 replicates for 
analysis. Once the plates are filled with the plant material in the desired layout, they are manually moved to a liquid handling station (Figure 2). In this 
station the samples are subjected to a mild pretreatment with either dilute acid or alkaline and incubated at temperatures of up to 90&deg;C. The pretreatment solution 
is subsequently removed and the samples are rinsed with buffer to return them to a suitable pH for hydrolysis. The samples are then incubated with an enzyme
mixture for a variable length of time at 50&deg;C. An aliquot is taken from the hydrolyzate and the reducing sugars are automatically determined by the MBTH 
colorimetric method.

A simple, rapid method for determining the saccharification potential of large numbers of plant biomass samples is described. The automated platform for this analysis involves the preparation of the plant biomass for analysis in 96 well plates and the subsequent performance of pretreatment, hydrolysis and quantification of the sugars released.

Polysaccharides that make up plant lignocellulosic biomass can be broken down to produce a range of sugars that subsequently can be 
used in establishing ...

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 ...

A Manual Small Molecule Screen Approaching High-throughput Using Zebrafish Embryos

Zebrafish have become a widely used model organism to investigate the mechanisms that underlie developmental biology and to study human disease pathology due to their considerable degree of genetic conservation with humans. Chemical genetics entails testing the effect that small molecules have on a biological process and is becoming a popular translational research method to identify therapeutic compounds. Zebrafish are specifically appealing to use for chemical genetics because of their ability to produce large clutches of transparent embryos, which are externally fertilized. Furthermore, zebrafish embryos can be easily drug treated by the simple addition of a compound to the embryo media. Using whole-mount in situ hybridization (WISH), mRNA expression can be clearly visualized within zebrafish embryos. Together, using chemical genetics and WISH, the zebrafish becomes a potent whole organism context in which to determine the cellular and physiological effects of small molecules. Innovative advances have been made in technologies that utilize machine-based screening procedures, however for many labs such options are not accessible or remain cost-prohibitive. The protocol described here explains how to execute a manual high-throughput chemical genetic screen that requires basic resources and can be accomplished by a single individual or small team in an efficient period of time. Thus, this protocol provides a feasible strategy that can be implemented by research groups to perform chemical genetics in zebrafish, which can be useful for gaining fundamental insights into developmental processes, disease mechanisms, and to identify novel compounds and signaling pathways that have medically relevant applications.

The zebrafish is an excellent experimental organism to study vertebrate developmental processes and model human disease. Here, we describe a protocol on how to perform a manual high-throughput chemical screen in zebrafish embryos with a whole-mount in situ hybridization (WISH) read-out.

Zebrafish have become a widely used model organism to investigate the mechanisms that underlie developmental biology and to study human disease pathology ...

High-throughput Screening for Chemical Modulators of Post-transcriptionally Regulated Genes

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays focus on transcriptional regulation, being essentially aimed at the identification of promoter-targeting molecules. As a result, post-transcriptional mechanisms are largely uncovered by gene expression targeted drug development. Here we describe a cell-based assay aimed at investigating the role of the 3&#39; untranslated region (3&#8217; UTR) in the modulation of the fate of its mRNA, and at identifying compounds able to modify it. The assay is based on the use of a luciferase reporter construct containing the 3&#8217; UTR of a gene of interest stably integrated into a disease-relevant cell line. The protocol is divided into two parts, with the initial focus on the primary screening aimed at the identification of molecules affecting luciferase activity after 24 hr of treatment. The second part of the protocol describes the counter-screening necessary to discriminate compounds modulating luciferase activity specifically through the 3&#8217; UTR. In addition to the detailed protocol and representative results, we provide important considerations about the assay development and the validation of the hit(s) on the endogenous target. The described cell-based reporter gene assay will allow scientists to identify molecules modulating protein levels via post-transcriptional mechanisms dependent on a 3&#8217; UTR.

Here we describe a cell-based reporter gene assay as a valuable tool to screen chemical libraries for compounds modulating post-transcriptional control mechanisms exerted through 3&#8217; UTR.

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays ...

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 ...