We thank Ms. Fan Shen for her support to the zebrafish rearing. This is supported by fundings to Dr. Bing Hu (Chinese Academy of Sciences, "Bai Ren Ji Hua", NSFC 30870833 and National Basic Science Program of China, 2009CB941302).
All animal experiments were conducted in accordance with the guidelines and regulations set forth by the University of Science and Technology of China (USTC) Animal Resources Center and University Animal Care and Use Committee.

Part I: Construct the OKR apparatus
Details are shown in video demonstration.
Part II: OKR of Adult Zebrafish
If your lab has constructed an OKR apparatus, the key of adult zebrafish OKR is to hold the fish. In this part, we will show you step by step.
Our apparatus composes following parts similar to others mentioned. The circular fish chamber is 7.0 cm in outer diameter, 6.5 cm in inner diameter and 7.0 cm in high. The drum around fish chamber is 8.5 cm in out diameter, 7.5 cm in inner diameter and 7.0 cm in high. It could rotate clockwise and counter-clockwise with the speed from 20~70 rotations per min (rpm). Eleven cycles of black and white stripes are drawn on a tracing paper which adhered on the outside of the drum. The light system is composed of two circle light tubes in 21 cm diameter.
<img src="/files/ftp_upload/1742/1742fig1.jpg" alt="Figure 1" /> Figure 1. The model of sponge. The cliff made in this middle is to make sure that the visual field was not being sheltered.
<ol>
<li>A sponge as shown in Fig.1 composed by two parts. The left part is length 3 cm x width 3 cm x high 2 cm. The right part is length 3 cm x width 3 cm x high 3 cm.</li>
<li>Put this sponge in the bottom of fish chamber and pour rearing water in about 2 cm depth. Air bubble which hide in the sponge should be driven out.</li>
<li>Insert a pin in the front of right part of sponge, about 2 mm behind the cliff.</li>
<li>Anesthetize an adult zebrafish in MS-222.</li>
<li>Put the zebrafish on the sponge with dorsal up and allow one side of its pectoral fin before the first pin. </li>
<li>The second pin is inserted behind the other pectoral fin. It could avoid zebrafish shrinking body by cooperating with the first pin (also see in Fig. 2). </li>
<li>Clamp its tail with an artery clamp and fix the artery clamp in a piece of rubber (modeling clay) which is adhered on the fish chamber.</li>
<li>The third and fourth pin is planted in the site near cloacal pore of fish body. It could prevent zebrafish to wave its tail intensely. </li>
<li>The fifth pin is sited between the first and the third pin and then the sixth pin is on the other side of it. They could prevent zebrafish from shaking its body.</li>
<li>The seventh and eighth pin is inserted in the sites near the gill to keep the head orientation. </li>
<li>Pour rearing water in the fish chamber.</li>
<li>After the zebrafish wakes up, let it adapt for 5~10 minutes.</li>
<li>Switch on the light of this apparatus and let zebrafish adapt this lighting for 2 minutes.</li>
<li>Switch on the motor to drive the grating and allow zebrafish to adapt for 1 minute.</li>
<li>Turn on the camera and record the movement of eyes.</li>
<li>Analyze the eye angles6 and saccade numbers on your personal computer (A representative example of the eye angles analysis is shown in Fig.2).</li>
</ol>
<img src="/files/ftp_upload/1742/1742fig2.jpg" alt="Figure 2" /> Figure 2. The angle between eye axis and body axis. 
a)When the direction of grating is nasal-to-temporal, we defined the angle at the ahead of fish body is a negative angle and the angle at the fish body is a positive angle, vice versa (for brief review also see Ref. 6). Numbers in this figure represent the sequence of pins. 
b)OKR analysis example from one fish in normal group. An one-second film was transferred to a series frames and the eye angles of each frame was measured with Image-pro Plus software. Each point in this figure represents each frame we measured.
Notes:
<ol class="lalpha">
<li>All the pins are just used to prevent zebrafish from shaking its body, too tight will be harmful to fish.</li>
<li>Artery clamp could damage the tail as its contact area is small. Once the tail is free, it s very difficult to fix this fish. Wrap a bandage around the tail is recommended in some condition.</li>
<li>The seventh and eighth pin which are planted in the site near gill should not be shelter from their sight of grating.</li>
</ol>

Part III. OKR of Larval Zebrafish
1. Methylcellulose
Larval zebrafish can be immobilized in 6% methylcellulose solution while keep alive for a long time. Prepare methylcellulose solution as follows.
<ol>
<li>Boil 200 ml ddH2O in microwave oven about 3 minutes at high level.</li>
<li>Transfer the hot water to a stirring hotplate and stir it vigorously.</li>
<li>Add 12 g methylcellulose into the hot water gradually.</li>
<li>Keep stirring for 3 minutes after methylcellulose is well-dispersed.</li>
<li>Cool the solutions with ice water until it becomes clear, and then place it at 4&deg;C.</li>
</ol>
2. Larval Zebrafish
<ol>
<li>Pairs two male and a female of adult zebrafish in a mating tank at 17:00 after feeding. Next morning transfer them to a fresh mating tank and collect embryos after 1 hour.</li>
<li>The eggs are maintained in embryo medium in a 28.5&plusmn;0.5&deg;C incubator with the light: dark cycle of 14:10.</li>
<li>Eggs will be hatched out at 48 hours post fertilization (hpf) and the OKR will be tested at 72 hpf or later on. In this video, the larvaes are at 5 dpf.</li>
</ol>
3. Procedure of OKR
<ol>
<li>Put the apparatus under the stereoscope equipped with CCD camera and switch on the light of this apparatus.</li>
<li>Add 20 ml 6%methycellulose in a 55-mm petri dish.</li>
<li>Place several larvaes in a row at centre of this dish. </li>
<li>Put an air bubble about a volume of 1 &mu;l in the camera field, it could be as a mirror to reflect the direction of the grating.</li>
<li>Switch on the motor and record the movement of their eyes.</li>
</ol>

Part IV. OMR of Adult Zebrafish
Adult zebrafish OMR could also be conducted with this apparatus, just place a column in the fish chamber for preventing fish swimming across centre (showed in Fig.3a, rotating velocity is 36 rpm, black-white cycles are 11).
<ol>
<li>Put a fish in this fish chamber.</li>
<li>Stand a column of 2 cm diameter in the centre of this fish chamber.</li>
<li>Adapt for one minute both in still grating and rotation grating.</li>
<li>Record the movement of zebrafish.</li>
<li>Analyze the coincidence rate of time on your personal computer (an example is shown in Fig.3b, rotating velocity is 36 rpm, black-white cycle is 11)</li>
</ol>
<img src="/files/ftp_upload/1742/1742fig3.jpg" alt="Figure 3" /> Figure 3. OMR of Adult Zebrafish. (a) A white plastics column was placed at the centre of fish chamber for preventing fish swimming across it. (b) The coincidence rate of adult zebrafish following the grating. The coincidence rate was defined as the proportion of the following grating time to the total recording time. The value of 50% indicates that the fish is swimming randomly while 100% indicates the fish following grating very well. Both optic nerves were crushed with a jewelry forceps about 10 seconds. The behavior of OMR appeared as a random swimming after crush.

<ol>
	<li>Beck, J., Gilland, E., Tank, D., Baker, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantifying+the+Ontogeny+of+Optokinetic+and+Vestibuloocular+Behaviors+in+Zebrafish+Medaka,+and+Goldfish.">Quantifying the Ontogeny of Optokinetic and Vestibuloocular Behaviors in Zebrafish Medaka, and Goldfish.</a> J Neurophysiol. 92, 3546-3561 (2004).</li><li>Brockerhoff, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+the+optokinetic+response+of+zebrafish+larvae.">Measuring the optokinetic response of zebrafish larvae.</a> Nature Protocols. 1, 2448-2451 (2006).</li><li>Emran, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=OFF+ganglion+cells+cannot+drive+the+optokinetic+reflex+in+zebrafish.">OFF ganglion cells cannot drive the optokinetic reflex in zebrafish.</a> Proc Natl Acad Sci U S A. 104, 19126-19131 (2007).</li><li>Rinner, O., Rick, J., Neuhauss, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contrast+Sensitivity,+Spatial+and+Temporal+Tuning+of+the+Larval+Zebrafish+Optokinetic+Response.">Contrast Sensitivity, Spatial and Temporal Tuning of the Larval Zebrafish Optokinetic Response.</a> Investigative Ophthalmology and Visual Science. 46, 137-142 (2005).</li><li>Roeser, T., Baier, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visuomotor+Behaviors+in+Larval+Zebrafish+after+GFP-Guided+Laser+Ablation+of+the+Optic+Tectum.">Visuomotor Behaviors in Larval Zebrafish after GFP-Guided Laser Ablation of the Optic Tectum.</a> The Journal of Neuroscience. 23, 3726-3734 (2003).</li><li>Easter, S., Nicola, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Development+of+Vision+in+the+Zebrafish+(Danio+rerio).">The Development of Vision in the Zebrafish (Danio rerio).</a> Developmental Biology. 180, 646-663 (1996).</li><li>Maaswinkel, H., Li, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spatio-temporal+frequency+characteristics+of+the+optomotor+response+in+zebrafish.">Spatio-temporal frequency characteristics of the optomotor response in zebrafish.</a> Vision Research. 43, 21-30 (2003).</li></ol>

According to the definition of OKR, it is a phenomenon that animals move their eyes to pursue a rotating grating spontaneously. If this behavior has been conducted for a long time (e.g. above 6 hours), the eye muscles may be tired and the OKR will be attenuated.
Adult zebrafish OMR has been described completely by others7. In this video, we just show you this behavior with our apparatus. Once the optic nerves are crushed, they could not follow this grating very well.
<p class=...

<table><tbody><tr><td>Methylcellulose</td><td>Sigma-Aldrich</td><td>M6385</td><td>Viscosity 25 cP</td></tr></tbody></table>

using the optokinetic response to study visual function of zebrafish

Optokinetic response (OKR) is a behavior that an animal vibrates its eyes to follow a rotating grating around it. It has been widely used to assess the visual functions of larval zebrafish1-5. Nevertheless, the standard protocol for larval fish is not yet readily applicable in adult zabrafish. Here, we introduce how to measure the OKR of adult zebrafish with our simple custom-built apparatus using a new protocol which is established in our lab. Both our apparatus and step-by-step procedure of OKR in adult zebrafish are illustrated in this video. In addition, the measurements of the larval OKR, as well as the optomotor response (OMR) test of adult zebrafish, are also demonstrated in this video. This OKR assay of adult zebrafish in our experiment may last for up to 4 hours. Such OKR test applied in adult fish will benefit to visual function investigation more efficiently when the adult fish vision system is manipulated.
Su-Qi Zou and Wu Yin contributed equally to this paper.

Watch this Scientific Journal Video about Using the optokinetic response to study visual function of zebrafish at JoVE.com

Using the optokinetic response to study visual function of zebrafish

Optokinetic response has been widely used to assess the visual functions of larval zebrafish. Nevertheless, the standard protocol for larval fish is not yet readily applicable in adults1-5. Here, we introduce how to measure the OKR of adult zebrafish using a new protocol which is established in our lab.

Optokinetic response (OKR) is a behavior that an animal vibrates its eyes to follow a rotating grating around it. It has been widely used to assess the ...

using-the-optokinetic-response-to-study-visual-function-of-zebrafish

Research

JoVE Journal

Biology

18.3K Views.  University of Science and Technology of China (USTC). Optokinetische reactie is op grote schaal gebruikt om de visuele functies van larvale zebravis te beoordelen. Toch is het standaard protocol voor larvale vis is nog niet goed toepasbaar bij volwassenen 1-5. Hier introduceren we hoe de OKR van volwassen zebravissen met behulp van een nieuw protocol dat is gevestigd in ons lab te meten.

Video: Using the optokinetic response to study visual function of zebrafish

A Behavioral Assay to Measure Responsiveness of Zebrafish to Changes in Light Intensities 

The optokinetic reflex (OKR) is a basic visual reflex exhibited by most vertebrates and plays an important role in stabilizing the eye relative to the visual scene. However, the OKR requires that an animal detect moving stripes and it is possible that fish that fail to exhibit an OKR may not be completely blind. One zebrafish mutant, the no optokinetic response c (nrc) has no OKR under any light conditions tested and was reported to be completely blind. Previously, we have shown that OFF-ganglion cell activity can be recorded in these mutants. To determine whether mutant fish with no OKR such as the nrc mutant can detect simple light increments and decrements we developed the visual motor behavioral assay (VMR). In this assay, single zebrafish larvae are placed in each well of a 96-well plate allowing the simultaneous monitoring of larvae using an automated video-tracking system. The locomotor responses of each larva to 30 minutes light ON and 30 minutes light OFF were recorded and quantified. WT fish have a brief spike of motor activity upon lights ON, known as the startle response, followed by return to lower-than baseline activity, called a freeze. WT fish also sharply increase their locomotor activity immediately following lights OFF and only gradually (over several minutes) return to baseline locomotor activity. The nrc mutants respond similarly to light OFF as WT fish, but exhibit a slight reduction in their average activity as compared to WT fish. Motor activity in response to light ON in nrc mutants is delayed and sluggish. There is a slow rise time of the nrc mutant response to light ON as compared to WT light ON response. The results indicate that nrc fish are not completely blind. Because teleosts can detect light through non-retinal tissues, we confirmed that the immediate behavioral responses to light-intensity changes require intact eyes by using the chokh (chk) mutants, which completely lack eyes from the earliest stages of development. In our VMR assay, the chk mutants exhibit no startle response to either light ON or OFF, showing that the lateral eyes mediate this behavior. The VMR assay described here complements the well-established OKR assay, which does not test the ability of zebrafish larvae to respond to changes in light intensities. Additionally, the automation of the VMR assay lends itself to high-throughput screening for defects in light-intensity driven visual responses.

A Behavioral Assay to Measure Responsiveness of Zebrafish to Changes in Light Intensities

We developed the Visual-Motor Response to quantitate the motor output of larval zebrafish in response to light increments and decrements. We also examined zebrafish vision mutants, including the no optokinetic response (nrc) mutants, which were thought to be completely blind when tested by another vision assay, the optokinetic reflex.

The optokinetic reflex (OKR) is a basic visual reflex exhibited by most vertebrates and plays an important role in stabilizing the eye relative to the ...

VisioTracker, an Innovative Automated Approach to Oculomotor Analysis

Investigations into the visual system development and function necessitate quantifiable behavioral models of visual performance that are easy to elicit, robust, and simple to manipulate. A suitable model has been found in the optokinetic response (OKR), a reflexive behavior present in all vertebrates due to its high selection value. The OKR involves slow stimulus-following movements of eyes alternated with rapid resetting saccades. The measurement of this behavior is easily carried out in zebrafish larvae, due to its early and stable onset (fully developed after 96 hours post fertilization (hpf)), and benefitting from the thorough knowledge about zebrafish genetics, for decades one of the favored model organisms in this field. Meanwhile the analysis of similar mechanisms in adult fish has gained importance, particularly for pharmacological and toxicological applications.
Here we describe VisioTracker, a fully automated, high-throughput system for quantitative analysis of visual performance. The system is based on research carried out in the group of Prof. Stephan Neuhauss and was re-designed by TSE Systems. It consists of an immobilizing device for small fish monitored by a high-quality video camera equipped with a high-resolution zoom lens. The fish container is surrounded by a drum screen, upon which computer-generated stimulus patterns can be projected. Eye movements are recorded and automatically analyzed by the VisioTracker software package in real time.
Data analysis enables immediate recognition of parameters such as slow and fast phase duration, movement cycle frequency, slow-phase gain, visual acuity, and contrast sensitivity.
Typical results allow for example the rapid identification of visual system mutants that show no apparent alteration in wild type morphology, or the determination of quantitative effects of pharmacological or toxic and mutagenic agents on visual system performance.

The VisioTracker is an automated system for the quantitative analysis of visual performance of larval and small adult fish based on the recording of eye movements. It features full control over visual stimulus properties and real-time analysis, enabling high-throughput research in fields such as visual system development and function, pharmacology, neural circuit studies and sensorimotor integration.

Investigations into the visual system development and function necessitate quantifiable behavioral models of visual performance that are easy to elicit, ...

Neuroscience

Optogenetic Activation of Zebrafish Somatosensory Neurons using ChEF-tdTomato

Larval zebrafish are emerging as a model for describing the development and function of simple neural circuits. Due to their external fertilization, rapid development, and translucency, zebrafish are particularly well suited for optogenetic approaches to investigate neural circuit function. In this approach, light-sensitive ion channels are expressed in specific neurons, enabling the experimenter to activate or inhibit them at will and thus assess their contribution to specific behaviors. Applying these methods in larval zebrafish is conceptually simple but requires the optimization of technical details. Here we demonstrate a procedure for expressing a channelrhodopsin variant in larval zebrafish somatosensory neurons, photo-activating single cells, and recording the resulting behaviors. By introducing a few modifications to previously established methods, this approach could be used to elicit behavioral responses from single neurons activated up to at least 4 days post-fertilization (dpf). Specifically, we created a transgene using a somatosensory neuron enhancer, CREST3, to drive the expression of the tagged channelrhodopsin variant, ChEF-tdTomato. Injecting this transgene into 1-cell stage embryos results in mosaic expression in somatosensory neurons, which can be imaged with confocal microscopy. Illuminating identified cells in these animals with light from a 473 nm DPSS laser, guided through a fiber optic cable, elicits behaviors that can be recorded with a high-speed video camera and analyzed quantitatively. This technique could be adapted to study behaviors elicited by activating any zebrafish neuron. Combining this approach with genetic or pharmacological perturbations will be a powerful way to investigate circuit formation and function.

Optogenetic techniques have made it possible to study the contribution of specific neurons to behavior. We describe a method in larval zebrafish for activating single somatosensory neurons expressing a channelrhodopsin variant (ChEF) with a diode-pumped solid state (DPSS) laser and recording the elicited behaviors with a high-speed video camera.

Larval  zebrafish are emerging as a model for describing the development and function  of simple neural circuits. Due to their  external fertilization, ...

The Optokinetic Response as a Quantitative Measure of Visual Acuity in Zebrafish

Zebrafish are a proven model for vision research, however many of the earlier methods generally focused on larval fish or demonstrated a simple response. More recently adult visual behavior in zebrafish has become of interest, but methods to measure specific responses are new coming. To address this gap, we set out to develop a methodology to repeatedly and accurately utilize the optokinetic response (OKR) to measure visual acuity in adult zebrafish. Here we show that the adult zebrafish's visual acuity can be measured, including both binocular and monocular acuities. Because the fish is not harmed during the procedure, the visual acuity can be measured and compared over short or long periods of time. The visual acuity measurements described here can also be done quickly allowing for high throughput and for additional visual procedures if desired. This type of analysis is conducive to drug intervention studies or investigations of disease progression.

Zebrafish have been a valuable tool for many research areas. Here we demonstrate a method to elicit a visual response and calculate a functional visual acuity in the adult zebrafish.

Zebrafish are a proven model for vision research, however many of the  earlier methods generally focused on larval fish or demonstrated a simple  ...

Electroretinogram Analysis of the Visual Response in Zebrafish Larvae

The electroretinogram (ERG) is a noninvasive electrophysiological method for determining retinal function. Through the placement of an electrode on the surface of the cornea, electrical activity generated in response to light can be measured and used to assess the activity of retinal cells in vivo. This manuscript describes the use of the ERG to measure visual function in zebrafish. Zebrafish have long been utilized as a model for vertebrate development due to the ease of gene suppression by morpholino oligonucleotides and pharmacological manipulation. At 5-10 dpf, only cones are functional in the larval retina. Therefore, the zebrafish, unlike other animals, is a powerful model system for the study of cone visual function in vivo. This protocol uses standard anesthesia, micromanipulation and stereomicroscopy protocols that are common in laboratories that perform zebrafish research. The outlined methods make use of standard electrophysiology equipment and a low light camera to guide the placement of the recording microelectrode onto the larval cornea. Finally, we demonstrate how a commercially available ERG stimulator/recorder originally designed for use with mice can easily be adapted for use with zebrafish. ERG of larval zebrafish provides an excellent method of assaying cone visual function in animals that have been modified by morpholino oligonucleotide injection as well as newer genome engineering techniques such as Zinc Finger Nucleases (ZFNs), Transcription Activator-Like Effector Nucleases (TALENs), and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9, all of which have greatly increased the efficiency and efficacy of gene targeting in zebrafish. In addition, we take advantage of the ability of pharmacological agents to penetrate zebrafish larvae to evaluate the molecular components that contribute to the photoresponse. This protocol outlines a setup that can be modified and used by researchers with various experimental goals.

We present a method for the electroretinographic (ERG) analysis of zebrafish larvae utilizing micromanipulation and electroretinography techniques. This is a simple and straightforward method for assaying visual function of zebrafish larvae in vivo.

The electroretinogram (ERG) is a noninvasive electrophysiological method for determining retinal function. Through the placement of an electrode on the ...

Eye Removal in Living Zebrafish Larvae to Examine Innervation-dependent Growth and Development of the Visual System

Zebrafish exhibit remarkable life-long growth and regenerative abilities. For example, specialized stem cell niches established during embryogenesis support continuous growth of the entire visual system, both in the eye and the brain. Coordinated growth between the retinae and the optic tectum ensures accurate retinotopic mapping as new neurons are added in the eyes and brain. To address whether retinal axons provide crucial information for regulating tectal stem and progenitor cell behaviors such as survival, proliferation, and/or differentiation, it is necessary to be able to compare innervated and denervated tectal lobes within the same animal and across animals. 
Surgical removal of one eye from living larval zebrafish followed by observation of the optic tectum achieves this goal. The accompanying video demonstrates how to anesthetize larvae, electrolytically sharpen tungsten needles, and use them to remove one eye. It next shows how to dissect brains from fixed zebrafish larvae. Finally, the video provides an overview of the protocol for immunohistochemistry and a demonstration of how to mount stained embryos in low-melting-point agarose for microscopy.

The article explains how to surgically remove eyes from living zebrafish larvae as the first step toward investigating how retinal input influences optic tectum growth and development. In addition, the article provides information about larval anesthetization, fixation, and brain dissection, followed by immunohistochemistry and confocal imaging.

Zebrafish exhibit remarkable life-long growth and regenerative abilities. For example, specialized stem cell niches established during embryogenesis ...

Developmental Biology

Investigating Development with Optogenetic Signaling Manipulation in Zebrafish

Optogenetic Signaling Activation in Zebrafish Embryos

Signaling pathways orchestrate fundamental biological processes, including development, regeneration, homeostasis, and disease. Methods to experimentally manipulate signaling are required to understand how signaling is interpreted in these wide-ranging contexts. Molecular optogenetic&#160;tools can provide reversible, tunable manipulations of signaling pathway activity with a high degree of spatiotemporal control and have been applied in vitro, ex vivo, and in vivo. These tools couple light-responsive protein domains, such as the blue light homodimerizing light-oxygen-voltage sensing (LOV) domain, with signaling effectors to confer light-dependent experimental control over signaling. This protocol provides practical guidelines for using the LOV-based bone morphogenetic protein (BMP) and Nodal signaling activators bOpto-BMP and bOpto-Nodal in the optically accessible early zebrafish embryo. It describes two control experiments: A quick phenotype assay to determine appropriate experimental conditions, and an immunofluorescence assay to directly assess signaling. Together, these control experiments can help establish a pipeline for using optogenetic tools in early zebrafish embryos. These strategies provide a powerful platform to investigate the roles of signaling in development, health, and physiology.

Author Spotlight: Manipulating Signaling in Zebrafish Embryos to Decode Cell Fate Decisions 

Optogenetic manipulation of signaling pathways can be a powerful strategy to investigate how signaling is decoded in development, regeneration, homeostasis, and disease. This protocol provides practical guidelines for using light-oxygen-voltage sensing domain-based Nodal and bone morphogenic protein (BMP) signaling activators in the early zebrafish embryo.

Signaling pathways orchestrate fundamental biological processes, including development, regeneration, homeostasis, and disease. Methods to experimentally ...

4-Dimensional Imaging of Zebrafish Optic Cup Morphogenesis

Visual system function requires the establishment of precise tissue and organ structures. In the vertebrate eye, structural defects are a common cause of visual impairment, yet mechanisms of eye morphogenesis are still poorly understood. The basic organization of the embryonic eye is conserved throughout vertebrates, thus live imaging of zebrafish embryos has become a powerful approach to directly observe eye development at real time under normal and pathological conditions. Dynamic cell processes including movements, morphologies, interactions, division, and death can be visualized in the embryo. We have developed methods for uniform labeling of subcellular structures and timelapse confocal microscopy of early eye development in zebrafish. This protocol outlines the method of generating capped mRNA for injection into the 1-cell zebrafish embryo, mounting embryos at optic vesicle stage (~12 hours post fertilization, hpf), and performing multi-dimensional timelapse imaging of optic cup morphogenesis on a laser scanning confocal microscope, such that multiple datasets are acquired sequentially in the same imaging session. Such an approach yields data that can be used for a variety of purposes, including cell tracking, volume measurements, three-dimensional (3D) rendering, and visualization. Our approaches allow us to pinpoint the cellular and molecular mechanisms driving optic cup development, in both wild type and genetic mutant conditions. These methods can be employed directly by other groups or adapted to visualize many additional aspects of zebrafish eye development.

This protocol describes an approach for in toto labeling and multidimensional imaging of zebrafish early eye development. We describe labeling, embedding, and four dimensional (4D) imaging using laser scanning confocal microscopy, and considerations for optimizing acquisition of datasets for dissecting mechanisms of optic cup morphogenesis.

Visual system function requires the establishment of precise tissue and organ structures. In the vertebrate eye, structural defects are a common cause of ...

Photomotor Response Assay: A Method to Measure the Behavioral Response of Larval Zebrafish to a Sudden Change in Lighting Condition

Source: Steele, W. B., et al. <a href="https://www.jove.com/v/57938/" target="_blank">Experimental Protocol for Examining Behavioral Response Profiles in Larval Fish: Application to the Neuro-stimulant Caffeine</a>.&#160;J. Vis. Exp.&#160;(2018).
This video describes the photomotor response assay of zebrafish and fathead minnow larvae using an automated tracking software. The protocol measures the behavioral response of the larval fish following a sudden change in lighting condition.

Source: Steele, W. B., et al. Experimental Protocol for Examining Behavioral Response Profiles in Larval Fish: Application to the Neuro-stimulant ...

JoVE Encyclopedia of Experiments

Danio rerio (zebrafish)

Larva

Optokinetic Response Assay: A Method to Measure Visual Acuity in Zebrafish

Source: Cameron, D. J., et al. <a href="https://www.jove.com/v/50832/" target="_blank">The Optokinetic Response as a Quantitative Measure of Visual Acuity in Zebrafish</a>.&#160;J. Vis. Exp.&#160;(2013)
This video describes the optokinetic response assay in zebrafish. The video measures the reflexive eye movements based on the visual moving stimulus and determines the visual acuity in zebrafish.

Source: Cameron, D. J., et al. The Optokinetic Response as a Quantitative Measure of Visual Acuity in Zebrafish.&#160;J. Vis. Exp.&#160;(2013)
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Using the optokinetic response to study visual function of zebrafish

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