The authors would like to thank Drs. Stephen Wilson and Lisa Wilsbacher for helpful discussions. This work was supported in part by NIH HL054737.

NOTE: Procedures using zebrafish were approved by UCSF&#39;s Institutional Animal Care and Use Committee.
1. Preparation of Tools
<ol>
	<li>Insert minutia pin into a pin holder and clamp the pin.</li>
	<li>Using fine tip forceps, carefully bend the tip of the pin to create a slight hook.</li>
	<li>For manipulation and stabilization of the embryo during injury, bend the end of a 28 guage &#189; inch needle mounted on an insulin syringe using needle-nose pliers.</li>
</ol>
2. Preparation of Zebrafish Embryos for Injury
<ol>
	<li>Set up zebrafish breeding pairs and collect eggs in egg water (60ug/mL aquarium salts) as shown previously22.</li>
	<li>Add 0.003% N-Phenylthiourea (PTU) to the egg water when the embryos are approximately 8 hr post fertilization (hpf) to prevent melanization.</li>
	<li>Dechorionate two day post fertilization (dpf) embryos prior to the experiment using fine tip forceps. 
	NOTE: Embryos can be injured anytime after circulation begins. The data presented here is for 2 dpf embryos, but the technique has been successfully applied in embryos up to 5 dpf.</li>
	<li>Anesthetize the embryos with 0.02% buffered 3-aminobenzoic acid (Tricaine) approximately 10 min prior to manipulations.</li>
</ol>
3. Mechanical Vessel Injury of Embryos
<ol>
	<li>Transfer anesthetized embryos to a depression slide on a dissecting stereomicroscope using a transfer pipet.</li>
	<li>Using the short flat side of the syringe needle to manipulate the embryo with the dominant hand, position the embryo on its side with the ventral surface facing away from the needle.</li>
	<li>Position the minutia pin with the tip pointed directly against the ventral surface of the fish posterior to the urogenital opening. Position the minutia pin at a slight angle such that the curved tip is able to pierce through the periderm directly into the caudal vein (Figure 1).</li>
	<li>Using the syringe needle to manipulate the embryo, pierce the caudal vein with the minutia pin by tapping the embryo into the pin to slightly hook the pin into the vein.</li>
	<li>Using the syringe needle, pull the embryo away from the minutia pin to create a small tear in the vessel. 
	NOTE: A successful injury will result in immediate bleeding from the vein.</li>
</ol>
4. Analysis of Hemostasis
<ol>
	<li>Choose only embryos with visibly circulating blood cells for this procedure.</li>
	<li>Prepare to begin the timer as soon as the minutia pin is pulled from the vessel.</li>
	<li>Start the timer as soon as blood loss can be visualized from the wound. When blood loss from the wound ceases, stop the timer and record total time as Bleeding Time. If coagulation is inhibited, record the time to when there are no longer visibly circulating blood cells.</li>
</ol>
5. Analysis of Wound Healing
<ol>
	<li>Transfer post-injury animals onto glass-bottom imaging dishes for microscopy.</li>
	<li>Remove the majority of the egg water.</li>
	<li>Cover the embryos in 0.3-1.2% low melting agarose dissolved in egg water, heated to between 42 and 45 &#186;C and supplemented with 0.02% Tricaine.</li>
	<li>Position embryos on their sides using forceps.</li>
	<li>After the agarose cools, fill the dish with 0.02% Tricaine in egg water.</li>
	<li>Acquire images using brightfield, epifluorescence, or confocal microscopy.</li>
	<li>Remove embryo from the agarose using forceps and transfer back to egg water.</li>
</ol>

<ol>
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Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zebrafish+in+the+study+of+early+cardiac+development.">Zebrafish in the study of early cardiac development.</a> Circ Res. 110 (6), 870-874 (2012).</li><li>Traver, D., 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=The+zebrafish+as+a+model+organism+to+study+development+of+the+immune+system.">The zebrafish as a model organism to study development of the immune system.</a> Adv Immunol. 81, 253-330 (2003).</li><li>Lieschke, G. J., Trede, N. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fish+immunology.">Fish immunology.</a> Curr Biol. 19 (16), R678-R682 (2009).</li><li>Lesley, R., Ramakrishnan, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insights+into+early+mycobacterial+pathogenesis+from+the+zebrafish.">Insights into early mycobacterial pathogenesis from the zebrafish.</a> Curr Opin Microbiol. 11 (3), 277-283 (2008).</li><li>Oehlers, S. H., 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=A+chemical+enterocolitis+model+in+zebrafish+larvae+that+is+dependent+on+microbiota+and+responsive+to+pharmacological+agents.">A chemical enterocolitis model in zebrafish larvae that is dependent on microbiota and responsive to pharmacological agents.</a> Dev Dyn. 240 (1), 288-298 (2011).</li><li>Gemberling, M., Bailey, T. J., Hyde, D. R., 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=The+zebrafish+as+a+model+for+complex+tissue+regeneration.">The zebrafish as a model for complex tissue regeneration.</a> Trends Genet. 29 (11), 611-620 (2013).</li><li>LeBert, D. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loss+of+fibrinogen+in+zebrafish+results+in+symptoms+consistent+with+human+hypofibrinogenemia.">Loss of fibrinogen in zebrafish results in symptoms consistent with human hypofibrinogenemia.</a> PLoS One. 8 (9), e74682 (2013).</li><li>Liu, 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=Targeted+mutagenesis+of+zebrafish+antithrombin+III+triggers+disseminated+intravascular+coagulation+and+thrombosis,+revealing+insight+into+function.">Targeted mutagenesis of zebrafish antithrombin III triggers disseminated intravascular coagulation and thrombosis, revealing insight into function.</a> Blood. , (2014).</li><li>Jagadeeswaran, P., Liu, Y. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+hemophilia+model+in+zebrafish:+analysis+of+hemostasis.">A hemophilia model in zebrafish: analysis of hemostasis.</a> Blood Cells Mol Dis. 23 (1), 52-57 (1997).</li><li>Jagadeeswaran, P., Gregory, M., Day, K., Cykowski, M., Thattaliyath, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zebrafish:+a+genetic+model+for+hemostasis+and+thrombosis.">Zebrafish: a genetic model for hemostasis and thrombosis.</a> J Thromb Haemost. 3 (1), 46-53 (2005).</li><li>Lin, H. F., 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=Analysis+of+thrombocyte+development+in+CD41-GFP+transgenic+zebrafish.">Analysis of thrombocyte development in CD41-GFP transgenic zebrafish.</a> Blood. 106 (12), 3803-3810 (2005).</li><li>Rosen, J. N., Sweeney, M. F., Mably, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microinjection+of+zebrafish+embryos+to+analyze+gene+function.">Microinjection of zebrafish embryos to analyze gene function.</a> J Vis Exp. (25), (2009).</li><li>Benard, E. L., 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=Infection+of+zebrafish+embryos+with+intracellular+bacterial+pathogens.">Infection of zebrafish embryos with intracellular bacterial pathogens.</a> J Vis Exp. (61), (2012).</li><li>Jagadeeswaran, P., Sheehan, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+blood+coagulation+in+the+zebrafish.">Analysis of blood coagulation in the zebrafish.</a> Blood Cells Mol Dis. 25 (3-4), 3-4 (1999).</li><li>Jin, S. W., Beis, D., Mitchell, T., Chen, J. N., Stainier, D. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+and+molecular+analyses+of+vascular+tube+and+lumen+formation+in+zebrafish.">Cellular and molecular analyses of vascular tube and lumen formation in zebrafish.</a> Development. 132 (23), 5199-5209 (2005).</li><li>Traver, D., 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=Transplantation+and+in+vivo+imaging+of+multilineage+engraftment+in+zebrafish+bloodless+mutants.">Transplantation and in vivo imaging of multilineage engraftment in zebrafish bloodless mutants.</a> Nat Immunol. 4 (12), 1238-1246 (2003).</li><li>Lawson, N. D., Weinstein, B. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+imaging+of+embryonic+vascular+development+using+transgenic+zebrafish.">In vivo imaging of embryonic vascular development using transgenic zebrafish.</a> Dev Biol. 248 (2), 307-318 (2002).</li><li>Renshaw, S. A., 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=A+transgenic+zebrafish+model+of+neutrophilic+inflammation.">A transgenic zebrafish model of neutrophilic inflammation.</a> Blood. 108 (13), 3976-3978 (2006).</li><li>Hall, C., Flores, M. 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The authors declare that they have no competing financial interests.

Zebrafish have been used successfully as a model for different types of wounds including laser injury13-15, laser-induced thrombosis16, and epithelial wounding10. We report a method of mechanical wounding that is simple to execute and produces a controlled injury in an in vivo model that is highly amenable to real-time microscopy. Injury results in a rapid and measurable hemostatic response and a reproducible wound repair program that can be monitored using video and timelapse mi...

Zebrafish have been used extensively to study a variety of topics in vascular biology, including vascular development, angiogenesis, and hematopoietic development and pathology1-3. Embryos develop a functional circulation as well as leukocytes and other components of the innate immune system by 1 day post fertilization (dpf) 1,4,5. The conservation of the inflammatory and leukocyte response to injury has made the zebrafish embryo an informative model for such diverse inflammatory processes as tuberculous infection, enterocolitis, and tissue regeneration6-9. Zebrafish embryos have been used to study injury-related inflammation particularly in the context of epithelial wounding and the neutrophil response10,11. Injury to the embryo results in a highly conserved cellular response from cells at the injury site and the innate immune cells recruited to respond to the injury and regulate its resolution11,12. Other injury models have used focused laser pulses to spatially localize injury to specific cell types including neurons, muscle cells, and cardiomyocytes13-15. 
Zebrafish embryos have been used as a model to study hemostasis and thrombosis in conditions of pharmacological and genetic manipulation, using both mechanical and laser-induced thrombus formation16-19. Components of the coagulation cascade appear to be well-conserved and transgenics have allowed for detailed studies of thrombocyte and fibrin deposition at the site of coagulation17,20,21. The procedure presented in this paper complements these methods by providing a system for studying mechanical vessel injury resulting in vessel breach, thrombus formation and resolution, and vessel repair.

<table><tbody><tr><td>Minutia Pins</td><td>Fine Science Tools</td><td>26002-10</td><td>Tip diameter 0.0125 mm, rod diameter 0.1 mm</td></tr><tr><td>Pin Holder</td><td>Fine Science Tools</td><td>26016-12</td><td></td></tr><tr><td>Dumont #5 Fine Tip Forceps</td><td>Fine Science Tools</td><td>11254-20</td><td></td></tr><tr><td>Glass Depression Slide</td><td>Aquatic Eco-Systems</td><td>M30</td><td></td></tr><tr><td>Low Melting Agarose</td><td>Lonza&amp;nbsp;</td><td>50081</td><td>Preheated to 42 &amp;ordm; C</td></tr><tr><td>N-Phenylthiourea (PTU)</td><td>Sigma Aldrich</td><td>P7629</td><td></td></tr><tr><td>3-aminobenzoic acid (Tricaine)</td><td>Sigma Aldrich</td><td>E10521</td><td></td></tr><tr><td>Hirudin</td><td>Sigma Aldrich</td><td>H7016</td><td></td></tr><tr><td>Glass bottom imaging dishes</td><td>Mattek</td><td>P35G-1.5-14-C</td><td></td></tr><tr><td>Dissecting microscope</td><td>Olympus</td><td>SZH10</td><td></td></tr><tr><td>Fluorescence microscope</td><td>Zeiss</td><td>Axio Observer</td><td></td></tr><tr><td>Aquarium salts</td><td>Instant Ocean</td><td></td><td></td></tr><tr><td>Insulin syringe with 28.5 G needle</td><td>Becton Dickinson&amp;nbsp;</td><td>329461</td><td></td></tr></tbody></table>

mechanical vessel injury in zebrafish embryos

Zebrafish (Danio rerio) embryos have proven to be a powerful model for studying a variety of developmental and disease processes. External development and optical transparency make these embryos especially amenable to microscopy, and numerous transgenic lines that label specific cell types with fluorescent proteins are available, making the zebrafish embryo an ideal system for visualizing the interaction of vascular, hematopoietic, and other cell types during injury and repair in vivo. Forward and reverse genetics in zebrafish are well developed, and pharmacological manipulation is possible. We describe a mechanical vascular injury model using micromanipulation techniques that exploits several of these features to study responses to vascular injury including hemostasis and blood vessel repair. Using a combination of video and timelapse microscopy, we demonstrate that this method of vascular injury results in measurable and reproducible responses during hemostasis and wound repair. This method provides a system for studying vascular injury and repair in detail in a whole animal model.

Mechanical vessel injury was performed on 2 dpf embryos (Figure 2A-C). Injury results in a rapid and reliable coagulation response as measured by time to cessation of bleeding (Figure 2D). To determine whether or not differences in the coagulation response could be measured, the anticoagulant hirudin was administered to the embryos by injection into the Duct of Cuvier immediately prior to wounding (5-10 nl of 1 unit per &#181;l hirudin dissolved in water)(for demonstrati...

Watch this Scientific Journal Video about Mechanical Vessel Injury in Zebrafish Embryos at JoVE.com

Mechanical Vessel Injury in Zebrafish Embryos

This article describes a method for creating a mechanical vessel injury in zebrafish embryos. This injury model provides a platform for studying hemostasis, injury-related inflammation, and wound healing in an organism ideally suited for real-time microscopy.

Zebrafish (Danio rerio) embryos have proven to be a powerful model for studying a variety of developmental and disease processes.  External development ...

mechanical-vessel-injury-in-zebrafish-embryos

Universidad de Cartagena UDEC

Research

JoVE Journal

Developmental Biology

7.2K Views.  University of California. This article describes a method for creating a mechanical vessel injury in zebrafish embryos. This injury model provides a platform for studying hemostasis, injury-related inflammation, and wound healing in an organism ideally suited for real-time microscopy. 

Video: Mechanical Vessel Injury in Zebrafish Embryos

Microbead Implantation in the Zebrafish Embryo

The zebrafish has emerged as a valuable genetic model system for the study of developmental biology and disease. Zebrafish share a high degree of genomic conservation, as well as similarities in cellular, molecular, and physiological processes, with other vertebrates including humans. During early ontogeny, zebrafish embryos are optically transparent, allowing researchers to visualize the dynamics of organogenesis using a simple stereomicroscope. Microbead implantation is a method that enables tissue manipulation through the alteration of factors in local environments. This allows researchers to assay the effects of any number of signaling molecules of interest, such as secreted peptides, at specific spatial and temporal points within the developing embryo. Here, we detail a protocol for how to manipulate and implant beads during early zebrafish development.

The zebrafish is an excellent model system for genetic and developmental studies. Bead implantation is a valuable tissue manipulation technique that can be used to interrogate developmental mechanisms by introducing alterations in local cellular environments. This protocol describes how to perform microbead implantation in the zebrafish embryo.

The zebrafish has emerged as a valuable genetic model system for the study of developmental biology and disease. Zebrafish share a high degree of genomic ...

Induction of Myocardial Infarction in Adult Zebrafish Using Cryoinjury

The mammalian heart is incapable of significant regeneration following an acute injury such as myocardial infarction1. By contrast, urodele amphibians and teleost fish retain a remarkable capacity for cardiac regeneration with little or no scarring throughout life2,3. It is not known why only some non-mammalian vertebrates can recreate a complete organ from remnant tissues4,5. To understand the molecular and cellular differences between regenerative responses in different species, we need to use similar approaches for inducing acute injuries.
In mammals, the most frequently used model to study cardiac repair has been acute ischemia after a ligation of the coronary artery or tissue destruction after cryoinjury6,7. The cardiac regeneration in newts and zebrafish has been predominantly studied after a partial resection of the ventricular apex2,3. Recently, several groups have established the cryoinjury technique in adult zebrafish8-10. This method has a great potential because it allows a comparative discussion of the results obtained from the mammalian and non-mammalian species.
Here, we present a method to induce a reproducible disc-shaped infarct of the zebrafish ventricle by cryoinjury. This injury model is based on rapid freezing-thawing tissue, which results in massive cell death of about 20% of cardiomyocytes of the ventricular wall. First, a small incision was made through the chest with iridectomy scissors to access the heart. The ventricular wall was directly frozen by applying for 23-25 seconds a stainless steel cryoprobe precooled in liquid nitrogen. To stop the freezing of the heart, fish water at room temperature was dropped on the tip of the cryoprobe. The procedure is well tolerated by animals, with a survival rate of 95%.
To characterize the regenerative process, the hearts were collected and fixed at different days after cryoinjury. Subsequently, the specimen were embedded for cryosectioning. The slides with sections were processed for histological analysis, in situ hybridization and immunofluorescence. This undertaking enhances our understanding of the factors that are required for the regenerative plasticity in the zebrafish, and provide new insights into the machinery of cardiac regeneration. A conceptual and molecular understanding of heart regeneration in zebrafish will impact both developmental biology and regenerative medicine.

Zebrafish represents a valuable model to study the mechanisms of heart regeneration in vertebrates. Here, we present a protocol for induction of a heart infarct in adult zebrafish using cryoinjury. This method results in massive cell death within 20% of the ventricular wall, similar to that observed in mammalian infarcts.

The mammalian heart is incapable of significant regeneration following an acute injury such as myocardial infarction1. By contrast, urodele amphibians and ...

Medicine

Spinal Cord Transection in the Larval Zebrafish

Mammals fail in sensory and motor recovery following spinal cord injury due to lack of axonal regrowth below the level of injury as well as an inability to reinitiate spinal neurogenesis. However, some anamniotes including the zebrafish Danio rerio exhibit both sensory and functional recovery even after complete transection of the spinal cord. The adult zebrafish is an established model organism for studying regeneration following spinal cord injury, with sensory and motor recovery by 6&#160;weeks post-injury. To take advantage of in vivo analysis of the regenerative process available in the transparent larval zebrafish as well as genetic tools not accessible in the adult, we use the larval zebrafish to study regeneration after spinal cord transection. Here we demonstrate a method for reproducibly and verifiably transecting the larval spinal cord. After transection, our data shows sensory recovery beginning at 2&#160;days post-injury (dpi), with the C-bend movement detectable by 3 dpi and resumption of free swimming by 5 dpi. Thus we propose the larval zebrafish as a companion tool to the adult zebrafish for the study of recovery after spinal cord injury.

After spinal transection, adult zebrafish have functional recovery by six weeks post-injury. To take advantage of larval transparency and faster recovery, we present a method for transecting the larval spinal cord. After transection, we observe sensory recovery beginning at 2&#160;days post-injury, and C-bend movement by 3 days post-injury.

Mammals fail in sensory and motor recovery following spinal cord injury due to lack of axonal regrowth below the level of injury as well as an inability ...

Neuroscience

Displacement Analysis of Myocardial Mechanical Deformation (DIAMOND) Reveals Segmental Heterogeneity of Cardiac Function in Embryonic Zebrafish

Zebrafish are increasingly utilized as a model organism for cardiomyopathies and regeneration. Current methods evaluating cardiac function fail to reliably detect segmental mechanics and are not readily feasible in zebrafish. Here we present a semiautomated, open-source method for the quantitative assessment of four-dimensional (4D) segmental cardiac function: displacement analysis of myocardial mechanical deformation (DIAMOND). Transgenic embryonic zebrafish were imaged in vivo using a light-sheet fluorescence microscopy system with 4D cardiac motion synchronization. Acquired 3D digital hearts were reconstructed at end-systole and end-diastole, and the ventricle was manually segmented into binary datasets. Then, the heart was reoriented and isotropically resampled along the true short axis, and the ventricle was evenly divided into eight portions (I&#8211;VIII) along the short axis. Due to the different resampling planes and matrices at end-systole and end-diastole, a transformation matrix was applied for image registration to restore the original spatial relationship between the resampled systolic and diastolic image matrices. After image registration, the displacement vector of each segment from end-systole to end-diastole was calculated based on the displacement of mass centroids in three dimensions (3D). DIAMOND shows that basal myocardial segments adjacent to the atrioventricular canal undergo the highest mechanical deformation and are the most susceptible to doxorubicin-induced cardiac injury. Overall, DIAMOND provides novel insights into segmental cardiac mechanics in zebrafish embryos beyond traditional ejection fraction (EF) under both physiological and pathological conditions.

Displacement Analysis of Myocardial Mechanical Deformation DIAMOND Reveals Segmental Heterogeneity of Cardiac Function in Embryonic Zebrafish

The goal of this protocol is to detail a novel method for the assessment of segmental cardiac function in embryonic zebrafish under both physiological and pathological conditions.

Zebrafish are increasingly utilized as a model organism for cardiomyopathies and regeneration. Current methods evaluating cardiac function fail to ...

Stab Wound Injury of the Zebrafish Adult Telencephalon: A Method to Investigate Vertebrate Brain Neurogenesis and Regeneration

Adult zebrafish have an amazing capacity to regenerate their central nervous system after injury. To investigate the cellular response and the molecular mechanisms involved in zebrafish adult central nervous system (CNS) regeneration and repair, we developed a zebrafish model of adult telencephalic injury.
In this approach, we manually generate an injury by pushing an insulin syringe needle into the zebrafish adult telencephalon. At different post injury days, fish are sacrificed, their brains are dissected out and stained by immunohistochemistry and/or in situ hybridization (ISH) with appropriate markers to observe cell proliferation, gliogenesis, and neurogenesis. The contralateral unlesioned hemisphere serves as an internal control. This method combined for example with RNA deep sequencing can help to screen for new genes with a role in zebrafish adult telencephalon neurogenesis, regeneration, and repair.

To shed light on the cellular and molecular mechanisms of zebrafish adult neurogenesis and regeneration, we developed a protocol for invasive surgery causing mechanical injuries in the zebrafish adult telencephalon and subsequent monitoring of changes in the stabbed hemisphere by immunohistochemistry or in situ hybridization.

Adult zebrafish have an amazing capacity to regenerate their central nervous system after injury. To investigate the cellular response and the molecular ...

A Simple and Effective Transplantation Device for Zebrafish Embryos

Classical embryological manipulations, such as removing cells and transplanting cells within or between embryos, are powerful techniques to study complex developmental processes. Zebrafish embryos are ideally suited for these manipulations since they are easily accessible, relatively large in size, and transparent. However, previously developed devices for cell removal and transplantation are cumbersome to use or expensive to purchase. In contrast, the transplantation device presented here is economical, easy to assemble, and simple to use. In this protocol, we first introduce the handling of the transplantation device as well as its assembly from commercially and widely available parts. We then present three applications for its use: generation of ectopic clones to study signal dispersal from localized sources, extirpation of cells to produce size-reduced embryos, and germline transplantation to generate maternal-zygotic mutants. Finally, we show that the tool can also be used for embryological manipulations in other species such as the Japanese rice fish medaka.

Embryological manipulations such as extirpation and transplantation of cells are important tools to study early development. This protocol describes a simple and effective transplantation device to perform these manipulations in zebrafish embryos.

Classical embryological manipulations, such as removing cells and transplanting cells within or between embryos, are powerful techniques to study complex ...

In Vivo Mechanotransduction Study Using Magnetic Beads in the Zebrafish Heart

Manipulating Mechanical Forces in the Developing Zebrafish Heart Using Magnetic Beads

Mechanical forces continuously provide feedback to heart valve morphogenetic programs. In zebrafish, cardiac valve development relies on heart contraction and physical stimuli generated by the beating heart. Intracardiac hemodynamics, driven by blood flow, emerge as fundamental information shaping the development of the embryonic heart. Here, we describe an effective method to manipulate mechanical forces in vivo by grafting a 30 &#181;m to 60 &#181;m diameter magnetic bead in the cardiac lumen. The insertion of the bead is conducted through microsurgery in anesthetized larvae without perturbing heart function and enables artificial alteration of the boundary conditions, thereby modifying flow forces in the system. As a result, the presence of the bead amplifies the mechanical forces experienced by endocardial cells and can directly trigger mechanical stimulus-dependent calcium influx. This approach facilitates the investigation of mechanotransduction pathways that govern heart development and can provide insights into the role of mechanical forces in cardiac valve morphogenesis.

Author Spotlight: Understanding Mechanical Forces Involved in Shaping the Zebrafish Heart

This protocol outlines a method for grafting a magnetic bead into the developing zebrafish heart through microsurgery, enabling the manipulation of mechanical forces in vivo and triggering mechanical stimulus-dependent calcium influx in endocardial cells.

Mechanical forces continuously provide feedback to heart valve morphogenetic programs. In zebrafish, cardiac valve development relies on heart contraction ...

Laser-inflicted Injury of Zebrafish Embryonic Skeletal Muscle

Various experimental approaches have been used in mouse to induce muscle injury with the aim to study muscle regeneration, including myotoxin injections (bupivacaine, cardiotoxin or notexin), muscle transplantations (denervation-devascularization induced regeneration), intensive exercise, but also murine muscular dystrophy models such as the mdx mouse (for a review of these approaches see 1). In zebrafish, genetic approaches include mutants that exhibit muscular dystrophy phenotypes (such as runzel2 or sapje3) and antisense oligonucleotide morpholinos that block the expression of dystrophy-associated genes4. Besides, chemical approaches are also possible, e.g. with Galanthamine, a chemical compound inhibiting acetylcholinesterase, thereby resulting in hypercontraction, which eventually leads to muscular dystrophy5. However, genetic and pharmacological approaches generally affect all muscles within an individual, whereas the extent of physically inflicted injuries are more easily controlled spatially and temporally1. Localized physical injury allows the assessment of contralateral muscle as an internal control. Indeed, we recently used laser-mediated cell ablation to study skeletal muscle regeneration in the zebrafish embryo6, while another group recently reported the use of a two-photon laser (822 nm) to damage very locally the plasma membrane of individual embryonic zebrafish muscle cells7.
Here, we report a method for using the micropoint laser (Andor Technology) for skeletal muscle cell injury in the zebrafish embryo. The micropoint laser is a high energy laser which is suitable for targeted cell ablation at a wavelength of 435 nm. The laser is connected to a microscope (in our setup, an optical microscope from Zeiss) in such a way that the microscope can be used at the same time for focusing the laser light onto the sample and for visualizing the effects of the wounding (brightfield or fluorescence). The parameters for controlling laser pulses include wavelength, intensity, and number of pulses.
Due to its transparency and external embryonic development, the zebrafish embryo is highly amenable for both laser-induced injury and for studying the subsequent recovery. Between 1 and 2 days post-fertilization, somitic skeletal muscle cells progressively undergo maturation from anterior to posterior due to the progression of somitogenesis from the trunk to the tail8, 9. At these stages, embryos spontaneously twitch and initiate swimming. The zebrafish has recently been recognized as an important vertebrate model organism for the study of tissue regeneration, as many types of tissues (cardiac, neuronal, vascular etc.) can be regenerated after injury in the adult zebrafish10, 11.

The method presented here comprises the precise injury of live zebrafish embryos with high-energy laser pulses and the subsequent analysis of these injuries and their recovery with time. We also show how genetically labeled single or groups of skeletal muscle cells can be tracked during and after laser light induced damage.

Various experimental approaches have been used in mouse to induce muscle injury with the aim to study muscle regeneration, including myotoxin injections ...

Biology

Imaging and 3D Reconstruction of Cerebrovascular Structures in Embryonic Zebrafish

Zebrafish are a powerful tool to study developmental biology and pathology in vivo. The small size and relative transparency of zebrafish embryos make them particularly useful for the visual examination of processes such as heart and vascular development. In several recent studies transgenic zebrafish that express EGFP in vascular endothelial cells were used to image and analyze complex vascular networks in the brain and retina, using confocal microscopy. Descriptions are provided to prepare, treat and image zebrafish embryos that express enhanced green fluorescent protein (EGFP), and then generate comprehensive 3D renderings of the cerebrovascular system. Protocols include the treatment of embryos, confocal imaging, and fixation protocols that preserve EGFP fluorescence. Further, useful tips on obtaining high-quality images of cerebrovascular structures, such as removal the eye without damaging nearby neural tissue are provided. Potential pitfalls with confocal imaging are discussed, along with the steps necessary to generate 3D reconstructions from confocal image stacks using freely available open source software.

Imaging of cerebrovascular development in larval zebrafish is described. Techniques to facilitate 3D imaging and modify cerebrovascular development using chemical treatments are also provided.

Zebrafish are a powerful tool to study developmental biology and pathology in vivo.  The small size and relative transparency of zebrafish embryos make ...

Optimized Intraperitoneal Injection for Compound Delivery in Adult Zebrafish

An Intraperitoneal Injection Technique in Adult Zebrafish that Minimizes Body Damage and Associated Mortality

The adult zebrafish (Danio rerio), which is genetically accessible, is being employed as a valuable vertebrate model to study human disorders such as cardiomyopathy. Intraperitoneal (IP) injection is an important method that delivers compounds to the body for either testing therapeutic effects or generating disease models such as doxorubicin-induced cardiomyopathy (DIC). Currently, there are two methods of IP injection. Both&#160;methods have limitations when handling toxic compounds such as doxorubicin, which result in side effects manifesting as severe damage to the body shape and fish death. While these shortcomings could be overcome by extensive investigator training, a new IP injection method that has minimal side effects is desirable. Here, a unique IP injection method that is able to handle toxic compounds is reported. Consistently reduced cardiac function can result without incurring significant fish death. The technique can be easily mastered by researchers who have minimal experience with adult zebrafish.

Author Spotlight: Novel Intraperitoneal Injection Method for Zebrafish Cardiotoxicity Models

A new intraperitoneal (IP) injection method in adult zebrafish is described. When handling toxic compounds such as doxorubicin, this procedure is more effective than the two previously reported IP methods. The technique is designed to be easily adopted by researchers with limited experience in the zebrafish model.

The adult zebrafish (Danio rerio), which is genetically accessible, is being employed as a valuable vertebrate model to study human disorders such as ...