Name: the complete and updated "rotifer polyculture method" for rearing first feeding zebrafish
Uploaded: 2016-01-17T15:00:00
Description: Watch this Scientific Journal Video about The Complete and Updated "Rotifer Polyculture Method" for Rearing First Feeding Zebrafish at JoVE.com

The care and usage of fish generated for representative results described in this protocol was performed in full accordance with the guidelines set forth by the Institutional Animal Care and Use Committee at Boston Children&#39;s Hospital, protocol # 14-05-2673R.

1. Rotifer Culture
<ol>
	<li>Basic Components of a Culture System using a 100 L Culture Vessel
	<ol>
		<li>Gather all the components for the rotifer culture setup . The rotifer culture setup consists of a culture vessel (CV) to grow the rotifers; a similar vessel to maintain feedout rotifers (feedout culture vessel, FCV); a round-bottomed hatching jar (Feed Reservoir, FR) for storage of the algae feed mixture (AFM); an air supply (AS) to aerate the CV, FCV and the FR; a peristaltic pump with a metering...

<ol>
	<li>Ribas, L., Piferrer, F. <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+(Danio+rerio)+as+a+model+organism,+with+emphasis+on+applications+for+finfish+aquaculture+research.">The zebrafish (Danio rerio) as a model organism, with emphasis on applications for finfish aquaculture research.</a> Reviews in Aquaculture. 6, 209-240 (2014).</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=Advances+in+understanding+tissue+regenerative+capacity+and+mechanisms+in+animals.">Advances in understanding tissue regenerative capacity and mechanisms in animals.</a> Nature reviews. Genetics. 11, 710-722 (2010).</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 in genetics TIG. 29, 611-620 (2013).</li><li>Santoriello, C., Zon, L. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hooked!+modeling+human+disease+in+zebrafish.">Hooked! modeling human disease in zebrafish.</a> Journal of Clinical Investigation. 122, 2337-2343 (2012).</li><li>Selderslaghs, I. W. T., Blust, R., Witters, H. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feasibility+study+of+the+zebrafish+assay+as+an+alternative+method+to+screen+for+developmental+toxicity+and+embryotoxicity+using+a+training+set+of+27+compounds.">Feasibility study of the zebrafish assay as an alternative method to screen for developmental toxicity and embryotoxicity using a training set of 27 compounds.</a> Reproductive Toxicology. 33 (2), 142-154 (2012).</li><li>Lawrence, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+husbandry+of+zebrafish+(Danio+rerio):+A+review.">The husbandry of zebrafish (Danio rerio): A review.</a> Aquaculture. 269, 1-20 (2007).</li><li>Harper, C., Lawrence, 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> The Laboratory Zebrafish (Laboratory Animal Pocket Reference). , (2010).</li><li>Nusslein-Volhard, C., Dahm, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Zebrafish, A Practical Approach. , (2002).</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. , (2007).</li><li>Carvalho, P., Arau, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rearing+zebrafish+(Danio+rerio)+larvae+without+live+food:+evaluation+of+a+commercial,+a+practical+and+a+purified+starter+diet+on+larval+performance.">Rearing zebrafish (Danio rerio) larvae without live food: evaluation of a commercial, a practical and a purified starter diet on larval performance.</a> Aquaculture Research. 37, 1107-1111 (2006).</li><li>Spence, R., Gerlach, G., Lawrence, C., Smith, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+behaviour+and+ecology+of+the+zebrafish,+Danio+rerio.">The behaviour and ecology of the zebrafish, Danio rerio.</a> Biol Rev Camb Philos Soc. 83 (1), 13-34 (2008).</li><li>Best, J., Adatto, I., Cockington, J., James, A., Lawrence, 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+novel+method+for+rearing+first-feeding+larval+zebrafish:+polyculture+with+Type+L+saltwater+rotifers+(Brachionus+plicatilis).">A novel method for rearing first-feeding larval zebrafish: polyculture with Type L saltwater rotifers (Brachionus plicatilis).</a> Zebrafish. 7 (3), 289-295 (2010).</li><li>Lawrence, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+zebrafish+husbandry+and+management.">Advances in zebrafish husbandry and management.</a> Methods in Cell Biology. 104, 429-451 (2011).</li><li>Lawrence, C., Sanders, E., Henry, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+culturing+saltwater+rotifers+(Brachionus+plicatilis)+for+rearing+larval+zebrafish.">Methods for culturing saltwater rotifers (Brachionus plicatilis) for rearing larval zebrafish.</a> Zebrafish. 9, 140-146 (2012).</li><li>Tucker, C. S., Hargreaves, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Biology and Culture of Channel Catfish. 34, 634-657 (2004).</li></ol>

Successful implementation of the rotifer polyculture method for feeding early larval zebrafish requires effective protocols for two tasks: the establishment and maintenance of a continuous rotifer culture system to feed the fish, and culturing first-feeding zebrafish larvae along with rotifers in the same tank.
The setup for a continuous saltwater rotifer production system for zebrafish laboratories first described by Lawrence and co-authors14 has been modified and enhanced in a num...

The zebrafish (Danio rerio) is a pre-eminent laboratory animal utilized in a growing number of scientific disciplines, including but not limited to developmental genetics, toxicology, behavior, aquaculture, regenerative biology, and the modeling of many human disorders1-5. Although the species is relatively easy to maintain in the laboratory, there are a number of management challenges associated with their culture6. The most prominent of these is larval rearing, particularly when the fish first begin to feed subsequent to gas bladder inflation7. Under normal, controlled conditions, this developmental event occurs at ~5 days post-fertilization (dpf), with the following 3 - 5 days of growth being particularly critical7. The central technical difficulty during this stage is to adequately meet the nutritional demands of the first feeding larvae - feed items must be appropriately sized, digestible, attractive, and available on a nearly continuous basis, without creating excessive waste in culturing tanks. Historically this has been achieved typically by delivering numerous small amounts of feed to the fish in tanks, along with routine water exchange8,9. While these methods are to some degree successful, they are inefficient, require high labor inputs, and return only variable and limited rates of growth and survival10.
In nature, zebrafish larvae presumably feed on abundant small zooplankton present in the water column11. For this reason, larviculture protocols that incorporate live feeds such as Paramecium, rotifers, and Artemia are typically most efficient7. In 2010, Best and co-authors demonstrated that it was possible to grow larval zebrafish in static, brackish water along with saltwater rotifers for the first 5 days of exogenous feeding12. This approach, which harnesses the natural high productivity of rotifer cultures to provide ample, highly nutritious prey without polluting the water, yields very high rates of larval growth and survival with low labor input12,13. In recent years, an increasing number of laboratories around the world have adopted variations of this protocol, and many are now culturing rotifers in a continuous fashion to support nursery systems14.
Over the past several years, methods for both rotifer/zebrafish polyculture and rotifer production have been refined and improved to become more standardized and readily scalable. This article provides step-by-step instructions for 1) continuous and robust rotifer production and 2) the establishment of the rotifer/zebrafish polyculture system used to support robust growth of fish for the first 5 days of exogenous feeding.

<table border="0" cellpadding="0" cellspacing="0" width="823">
	<tbody>
		<tr height="22">
			<td height="22" style="height:22px;width:305px;">Rotifer Culture Infrastructure</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">100 Liter Culture Vessel</td>
			<td style="width:135px;">Aquaneering</td>
			<td style="width:119px;">Custom</td>
			<td style="width:264px;">Polycarbonate culture vessel, conical bottomed, with drain valve</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">5 Gallon Culture Bucket Kit</td>
			<td style="width:135px;">Reed Mariculture</td>
			<td style="width:119px;">CCS Starter Kit</td>
			<td style="width:264px;">Small volume culture vessel for small facilities</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Rigid Clear Tubing 1/2&#34; O.D., 36&#8221;</td>
			<td style="width:135px;">Pentair Aquatic Ecosystems</td>
			<td style="width:119px;">16025</td>
			<td style="width:264px;">Rigid clear tubing for air delivery</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Mesh tube</td>
			<td style="width:135px;">Pentair Aquatic Ecosystems</td>
			<td style="width:119px;">RT444X</td>
			<td style="width:264px;">Mesh tube support for floss filter</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Rotifer Floss</td>
			<td style="width:135px;">Reed Mariculture</td>
			<td style="width:119px;">Rotifer floss 12&#8221; x 42&#8221;</td>
			<td style="width:264px;">Particulate waste trap</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Peristaltic Metering Timer Pump, 5 GPD</td>
			<td style="width:135px;">Grainger</td>
			<td style="width:119px;">38M003&#160;</td>
			<td style="width:264px;">Metering pump with timer for dosing feed to rotifers</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Peristaltic Metering Timer Pump, 1-100 mL/h (for smaller-scale culture)</td>
			<td style="width:135px;">Coral Vue</td>
			<td style="width:119px;">SKU: IC-LQD-DSR</td>
			<td style="width:264px;">Metering pump with timer for dosing feed to rotifers</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Silicone Tubing&#160;</td>
			<td style="width:135px;">Cole Parmer</td>
			<td style="width:119px;"></td>
			<td style="width:264px;">Tubing for algae delivery to rotifer vessel</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Rigid Clear Tubing &#34; O.D.,36&#8221;</td>
			<td style="width:135px;">Pentair Aquatic Ecosystems</td>
			<td style="width:119px;">16025</td>
			<td style="width:264px;">Rigid clear tubing for air delivery to algae paste</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Rigid Clear Tubing O.D., 36&#8221;</td>
			<td style="width:135px;">Pentair Aquatic Ecosystems</td>
			<td style="width:119px;">16025</td>
			<td style="width:264px;">Rigid clear tubing for algae delivery</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:305px;">Rotifers</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Live Rotifers Brachionus plicatilis Type L</td>
			<td style="width:135px;">Reed Mariculture</td>
			<td style="width:119px;">Type L 5 million</td>
			<td style="width:264px;">Rotifer stock culture for system startup</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:305px;">Rotifer Feed</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="45">
			<td height="45" style="height:45px;width:305px;">Sodium hydroxymethylsulfonate</td>
			<td style="width:135px;">Reed Mariculture</td>
			<td style="width:119px;">ClorAm-X&#174; 1lb tub</td>
			<td style="width:264px;">Ammonia reducer for algae feed mix</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:305px;">Sodium Bicarbonate</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:119px;">S25533B</td>
			<td style="width:264px;">pH buffer for algae feed mix</td>
		</tr>
		<tr height="45">
			<td height="45" style="height:45px;width:305px;">Microalgae concentrate</td>
			<td style="width:135px;">Reed Mariculture</td>
			<td style="width:119px;">Rotigrow Plus&#174; 1 liter bag</td>
			<td style="width:264px;">Nutritionally optimized rotifer feed</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:305px;">Water Preparation</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="96">
			<td height="96" style="height:96px;width:305px;">&#160;Reef Crystals Reef Salt</td>
			<td style="width:135px;">That Fish Place</td>
			<td style="width:119px;">198210</td>
			<td style="width:264px;">Salt for making culture water (NOTE: this item is an example only; any contaminant free salt formulations may be used).&#160;</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Refractometer</td>
			<td style="width:135px;">Pentair Aquatic Ecosystems</td>
			<td style="width:119px;">SR6</td>
			<td style="width:264px;">measuring salinity</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:305px;">Rotifer Culture Equipment</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Plankton Collectors 12&#34; Dia, 53 microns</td>
			<td style="width:135px;">Pentair Aquatic Ecosystems</td>
			<td style="width:119px;">BBPC20</td>
			<td style="width:264px;">Mesh screen for collecting rotifers</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Scrub Pads</td>
			<td style="width:135px;">Pentair Aquatic Ecosystems</td>
			<td style="width:119px;">SCR-58</td>
			<td style="width:264px;">Scrub pad for cleaning inside of culturing vessels</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:305px;">Scrub Brush</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td style="width:264px;"></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Bucket</td>
			<td style="width:135px;">Grainger Supply&#160;</td>
			<td style="width:119px;">43Y530</td>
			<td style="width:264px;">Graduated bucket for mixing culture water</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Hatching Jar</td>
			<td style="width:135px;">Pentair Aquatic Ecosystems</td>
			<td style="width:119px;">J30</td>
			<td style="width:264px;">Storage of algae feed mix</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Lugol&#8217;s Solution, Dilute</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:119px;">S99481</td>
			<td style="width:264px;">Agent used to immobilize live rotifers for counting</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Sedgewick-Rafter plankton counting slide with grid&#160;</td>
			<td style="width:135px;">Pentair Aquatic Eco-Systems</td>
			<td style="width:119px;">M415</td>
			<td style="width:264px;">Counting rotifers</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:305px;">Miscelleneous</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="41">
			<td height="41" style="height:41px;width:305px;">Tea Strainer</td>
			<td style="width:135px;">Kitchenworks</td>
			<td style="width:119px;">971972</td>
			<td style="width:264px;">Used for collecting zebrafish embryos after spawning</td>
		</tr>
	</tbody>
</table>

the complete and updated "rotifer polyculture method" for rearing first feeding zebrafish

The zebrafish (Danio rerio) is a model organism of increasing importance in many fields of science. One of the most demanding technical aspects of culture of this species in the laboratory is rearing first-feeding larvae to the juvenile stage with high rates of growth and survival. The central management challenge of this developmental period revolves around delivering highly nutritious feed items to the fish on a nearly continuous basis without compromising water quality. Because larval zebrafish are well-adapted to feed on small zooplankton in the water column, live prey items such as brachionid rotifers, Artemia, and Paramecium are widely recognized as the feeds of choice, at least until the fish reach the juvenile stage and are able to efficiently feed on processed diets. This protocol describes a method whereby newly hatched zebrafish larvae are cultured together with live saltwater rotifers (Brachionus plicatilis) in the same system. This polyculture approach provides fish with an "on-demand", nutrient-rich live food source without producing chemical waste at levels that would otherwise limit performance. Importantly, because the system harnesses both the natural high productivity of the rotifers and the behavioral preferences of the fish, the labor involved with maintenance is low. The following protocol details an updated, step-by-step procedure that incorporates rotifer production (scalable to any desired level) for use in a polyculture of zebrafish larvae and rotifers that promotes maximal performance during the first 5 days of exogenous feeding.

The continuous rotifer culture system described here is dynamic, and it is normal for rotifer numbers to fluctuate to a small extent over time if there are variations in daily feeding and harvest rates. The population of the rotifers in one of the active cultures in the aquaculture facilities at Boston Children&#39;s Hospital, maintained in the manner described above, was monitored for 30 days (Figure 3). The mean culture density during this period was 932 rotifers/mL, wi...

Watch this Scientific Journal Video about The Complete and Updated "Rotifer Polyculture Method" for Rearing First Feeding Zebrafish at JoVE.com

The Complete and Updated &quot;Rotifer Polyculture Method&quot; for Rearing First Feeding Zebrafish

Larval zebrafish are adapted to feed on zooplankton. It is possible to capitalize on this natural feature in the laboratory by growing first feeding fish together in the same system with live saltwater rotifers. This "polyculture" strategy promotes high growth and survival with minimal labor and disturbance to the larvae.

The Complete and Updated "Rotifer Polyculture Method" for Rearing First Feeding Zebrafish

The zebrafish (Danio rerio) is a model organism of increasing importance in many fields of science.  One of the most demanding technical aspects of ...

The overall goal of the Rotifer Polyculture Method is to harness the natural productivity and biological characteristics of salt water rotifers to create an environment that promotes rapid growth, and the maximum survival of first-feeding larval zebrafish. The primary advantage of this technique is that it dramatically decreases the amount of time and space required to successfully rear large numbers of zebrafish larvae for use in research experiments. Begin rotifer culture maintenance by filling the feed-out culture vessel, or FCV, to 90 percent capacity with clean, dechlorinated fresh water dosed with 10 grams per liter of aquarium salts.Ensure that the water is thoroughly mixed and that all of the salt is fully dissolved. Then, set the airflow into the vessel so that it maintains a rolling boil. Measure the salinity of the liquid with a refractometer.Next, sample the rotifers in the culture vessel, or CV.Make sure that the culture is well mixed. Then, collect three two-to-three milliliter samples using a transfer pipette from different parts of the culture and combine the samples in a tube. Transfer one-to-two milliliters of the combined sample onto a petri dish.Visualize the sample under a dissecting microscope, and check the quality of the culture. Add 100 microliters of 50 percent Lugol's iodine solution to the sample to immobilize the rotifers and count them. Immediately take a two milliliter sub-sample with a plastic pipette and dispense one milliliter into a Sedgewick Rafter counting slide.Using the dissecting microscope, count as much of the slide area as necessary to count up to 100 intact rotifers and the total number of eggs attached to the rotifers. Then, calculate the number of rotifers per milliliter for later use. Initiate harvest by removing the air supply and floss filter.Slowly open the valve at the bottom of the CV and allow the water to flow gently into a plankton collector with a 53 micron mesh screen. Collect the water flowing out of the bottom of the collector after filtering into a bucket or draining. Next, fill a bottle with 10 to 15 grams per liter of clean salt water.Invert the screen over the FCV and wash the rotifers into the FCV with a gentle stream of salt water. Start the programmable metering timer or PMT to deliver feed to the FCV. Then, scrub the entire inside of the CV with a clean scrub pad.Create a new 15 grams per liter mix in a five gallon bucket to replace the volume of water lost to harvest. Stir the solution vigorously until the mixture is completely dissolved. Then, add the solution to the CV.Next, rinse the floss filter with a high-pressure spray.When the floss filter is free of debris, return it to the CV.Adjust the feed rates of algae delivered to the CV by changing the duration of each dosing event. After 24 hours, repeat the process, starting the harvest of the rotifers remaining in the FCV. Concentrate the rotifers in two liters of fresh, clean, dechlorinated water with five grams per liter of salt.These can be stored at four degrees Celsius as a back-up supply, or used to feed later stages of fish beyond what is described in this protocol. Collect zebrafish embryos from a spawning event by pouring spawned embryos through a tea strainer. And then, gently rinsing with sterile fish water from a wash bottle into petri dishes.Once all the embryos are collected, incubate them. Begin the polyculture phase when more than 90 percent of the hatched larvae are actively swimming up in the water column. Add 500 milliliters of the rotifer culture directly from the FCV to a 3.5 liter nursery tank.Next, gently pour the larvae from one petri dish into the nursery tank. Ensure that no larvae remain in the dish. Add 500 milliliters of clean, conditioned fish water from a dedicated water source to the tank to a final volume of one liter, and 5 grams per liter final salinity.Observe the polyculture tank at least once per day to ensure that the rotifers and fish are present and growing. Check that the rotifers are visible throughout the water column. Ensure that the fish are also visible within the water column and that they are swimming among the rotifers.It's critical to asses the status of each tank on a daily basis to make sure that they're alive and swimming with rotifers available for all fish larvae. Upon insurance that the rotifers and fish are growing, start normal water flow through the tank. Finally, place a screen over the drain port to ensure that the larvae are not flushed out of the tank.The typical performance of a rotifer culture was monitored over a 30 day period, and yielded a mean culture density of 932 rotifers per milliliter. And a maximum of 1, 330 rotifers per milliliter. The rotifer population in a polyculture tank with zebrafish has a mean rotifer density of 589.4 rotifers per milliliter.The minimum value of 481 rotifers per milliliter is 10 times better than previously published work. Zebrafish showed steady growth each day over the five day period from a mean total length of 3.9 millimeters to 5.4 millimeters. After watching this video, you should have a good understanding of how to culture rotifers for use in a polyculture system that's devised to meet the nutritional demands of first-feeding zebrafish.

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Research

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Developmental Biology

Live Imaging of Innate Immune and Preneoplastic Cell Interactions Using an Inducible Gal4/UAS Expression System in Larval Zebrafish Skin

Here we describe a method to conditionally induce epithelial cell transformation by the use of the 4-Hydroxytamoxifen (4-OHT) inducible KalTA4-ERT2/UAS expression system1 in zebrafish larvae, and the subsequent live imaging of innate immune cell interaction with HRASG12V expressing skin cells. The KalTA4-ERT2/UAS system is both inducible and reversible which allows us to induce cell transformation with precise temporal/spatial resolution in vivo. This provides us with a unique opportunity to live image how individual preneoplastic cells interact with host tissues as soon as they emerge, then follow their progression as well as regression. Recent studies in zebrafish larvae have shown a trophic function of innate immunity in the earliest stages of tumorigenesis2,3. Our inducible system would allow us to live image the onset of cellular transformation and the subsequent host response, which may lead to important insights on the underlying mechanisms for the regulation of oncogenic trophic inflammatory responses. We also discuss how one might adapt our protocol to achieve temporal and spatial control of ectopic gene expression in any tissue of interest.

Studying the earliest events of preneoplastic cell progression and innate immune cell interaction is pivotal to understand and treat cancer. Here we describe a method to conditionally induce epithelial cell transformations and the subsequent live imaging of innate immune cell interaction with HRASG12V expressing skin cells in zebrafish larvae.

Here we describe a method to conditionally induce epithelial cell transformation by the use of the 4-Hydroxytamoxifen (4-OHT) inducible KalTA4-ERT2/UAS ...

Use of the TetON System to Study Molecular Mechanisms of Zebrafish Regeneration

The zebrafish has become a very important model organism for studying vertebrate development, physiology, disease, and tissue regeneration. A thorough understanding of the molecular and cellular mechanisms involved requires experimental tools that allow for inducible, tissue-specific manipulation of gene expression or signaling pathways. Therefore, we and others have recently adapted the TetON system for use in zebrafish. The TetON system facilitates temporally and spatially-controlled gene expression and we have recently used this tool to probe for tissue-specific functions of Wnt/beta&#8211;catenin signaling during zebrafish tail fin regeneration. Here we describe the workflow for using the TetON system to achieve inducible, tissue-specific gene expression in the adult regenerating zebrafish tail fin. This includes the generation of stable transgenic TetActivator and TetResponder lines, transgene induction and techniques for verification of tissue-specific gene expression in the fin regenerate. Thus, this protocol serves as blueprint for setting up a functional TetON system in zebrafish and its subsequent use, in particular for studying fin regeneration.

Here we outline the workflow for using the TetON system to achieve tissue-specific gene expression in the adult regenerating zebrafish tail fin.

The zebrafish has become a very important model organism for studying vertebrate development, physiology, disease, and tissue regeneration. A thorough ...

Analysis of Zebrafish Larvae Skeletal Muscle Integrity with Evans Blue Dye

The zebrafish model is an emerging system for the study of neuromuscular disorders. In the study of neuromuscular diseases, the integrity of the muscle membrane is a critical disease determinant. To date, numerous neuromuscular conditions display degenerating muscle fibers with abnormal membrane integrity; this is most commonly observed in muscular dystrophies. Evans Blue Dye (EBD) is a vital, cell permeable dye that is rapidly taken into degenerating, damaged, or apoptotic cells; in contrast, it is not taken up by cells with an intact membrane. EBD injection is commonly employed to ascertain muscle integrity in mouse models of neuromuscular diseases. However, such EBD experiments require muscle dissection and/or sectioning prior to analysis. In contrast, EBD uptake in zebrafish is visualized in live, intact preparations. Here, we demonstrate a simple and straightforward methodology for performing EBD injections and analysis in live zebrafish. In addition, we demonstrate a co-injection strategy to increase efficacy of EBD analysis. Overall, this video article provides an outline to perform EBD injection and characterization in zebrafish models of neuromuscular disease.

In this study, we describe a straightforward method to perform Evans Blue Dye (EBD) analysis on zebrafish larvae. This technique is a powerful tool for the characterization of skeletal muscle integrity and delineation of zebrafish models of muscular dystrophy, and is a valuable method for the development of novel therapeutics.

The zebrafish model is an emerging system for the study of neuromuscular disorders.  In the study of neuromuscular diseases, the integrity of the muscle ...

Imaging Subcellular Structures in the Living Zebrafish Embryo

In vivo imaging provides unprecedented access to the dynamic behavior of cellular and subcellular structures in their natural context. Performing such imaging experiments in higher vertebrates such as mammals generally requires surgical access to the system under study. The optical accessibility of embryonic and larval zebrafish allows such invasive procedures to be circumvented and permits imaging in the intact organism. Indeed the zebrafish is now a well-established model to visualize dynamic cellular behaviors using in vivo microscopy in a wide range of developmental contexts from proliferation to migration and differentiation. A more recent development is the increasing use of zebrafish to study subcellular events including mitochondrial trafficking and centrosome dynamics. The relative ease with which these subcellular structures can be genetically labeled by fluorescent proteins and the use of light microscopy techniques to image them is transforming the zebrafish into an in vivo model of cell biology. Here we describe methods to generate genetic constructs that fluorescently label organelles, highlighting mitochondria and centrosomes as specific examples. We use the bipartite Gal4-UAS system in multiple configurations to restrict expression to specific cell-types and provide protocols to generate transiently expressing and stable transgenic fish. Finally, we provide guidelines for choosing light microscopy methods that are most suitable for imaging subcellular dynamics.

Imaging the dynamic behavior of organelles and other subcellular structures in vivo can shed light on their function in physiological and disease conditions. Here, we present methods for genetically tagging two organelles, centrosomes and mitochondria, and imaging their dynamics in living zebrafish embryos using wide-field and confocal microscopy.

In vivo imaging provides unprecedented access to the dynamic behavior of cellular and subcellular structures in their natural context. Performing such ...

Rearing the Fruit Fly Drosophila melanogaster Under Axenic and Gnotobiotic Conditions

The influence of microbes on myriad animal traits and behaviors has been increasingly recognized in recent years. The fruit fly Drosophila melanogaster is a model for understanding microbial interactions with animal hosts, facilitated by approaches to rear large sample sizes of Drosophila under microorganism-free (axenic) conditions, or with defined microbial communities (gnotobiotic). This work outlines a method for collection of Drosophila embryos, hypochlorite dechorionation and sterilization, and transfer to sterile diet. Sterilized embryos are transferred to sterile diet in 50 ml centrifuge tubes, and developing larvae and adults remain free of any exogenous microbes until the vials are opened. Alternatively, flies with a defined microbiota can be reared by inoculating sterile diet and embryos with microbial species of interest. We describe the introduction of 4 bacterial species to establish a representative gnotobiotic microbiota in Drosophila. Finally, we describe approaches for confirming bacterial community composition, including testing if axenic Drosophila remain bacteria-free into adulthood.

Rearing the Fruit Fly Drosophila melanogaster Under Axenic and Gnotobiotic Conditions

A method for rearing Drosophila melanogaster under axenic and gnotobiotic conditions is presented. Fly embryos are dechorionated in sodium hypochlorite, transferred aseptically to sterile diet, and reared in closed containers. Inoculating diet and embryos with bacteria leads to gnotobiotic associations, and bacterial presence is confirmed by plating whole-body Drosophila homogenates.

The influence of microbes on myriad animal traits and behaviors has been increasingly recognized in recent years. The fruit fly Drosophila melanogaster is ...

Inducing Complete Polyp Regeneration from the Aboral Physa of the Starlet Sea Anemone Nematostella vectensis

Cnidarians, and specifically Hydra, were the first animals shown to regenerate damaged or severed structures, and indeed such studies arguably launched modern biological inquiry through the work of Trembley more than 250 years ago. Presently the study of regeneration has seen a resurgence using both &#34;classic&#34; regenerative organisms, such as the Hydra, planaria and Urodeles, as well as a widening spectrum of species spanning the range of metazoa, from sponges through mammals. Besides its intrinsic interest as a biological phenomenon, understanding how regeneration works in a variety of species will inform us about whether regenerative processes share common features and/or species or context-specific cellular and molecular mechanisms. The starlet sea anemone, Nematostella vectensis, is an emerging model organism for regeneration. Like Hydra, Nematostella is a member of the ancient phylum, cnidaria, but within the class anthozoa, a sister clade to the hydrozoa that is evolutionarily more basal. Thus aspects of regeneration in Nematostella will be interesting to compare and contrast with those of Hydra and other cnidarians. In this article, we present a method to bisect, observe and classify regeneration of the aboral end of the Nematostella adult, which is called the physa. The physa naturally undergoes fission as a means of asexual reproduction, and either natural fission or manual amputation of the physa triggers re-growth and reformation of complex morphologies. Here we have codified these simple morphological changes in a Nematostella Regeneration Staging System (the NRSS). We use the NRSS to test the effects of chloroquine, an inhibitor of lysosomal function that blocks autophagy. The results show that the regeneration of polyp structures, particularly the mesenteries, is abnormal when autophagy is inhibited.

Inducing Complete Polyp Regeneration from the Aboral Physa of the Starlet Sea Anemone Nematostella vectensis

Here we demonstrate how to induce and monitor regeneration in the Starlet Sea Anemone Nematostella vectensis, a model cnidarian anthozoan. We demonstrate how to amputate and categorize regeneration using a morphological staging system, and we use this system to reveal a requirement for autophagy in regenerating polyp structures.

Cnidarians, and specifically Hydra, were the first animals shown to regenerate damaged or severed structures, and indeed such studies arguably launched ...

AFM and Microrheology in the Zebrafish Embryo Yolk Cell

Elucidating the factors that direct the spatio-temporal organization of evolving tissues is one of the primary purposes in the study of development. Various propositions claim to have been important contributions to the understanding of the mechanical properties of cells and tissues in their spatiotemporal organization in different developmental and morphogenetic processes. However, due to the lack of reliable and accessible tools to measure material properties and tensional parameters in vivo, validating these hypotheses has been difficult. Here we present methods employing atomic force microscopy (AFM) and particle tracking with the aim of quantifying the mechanical properties of the intact zebrafish embryo yolk cell during epiboly. Epiboly is an early conserved developmental process whose study is facilitated by the transparency of the embryo. These methods are simple to implement, reliable, and widely applicable since they overcome intrusive interventions that could affect tissue mechanics. A simple strategy was applied for the mounting of specimens, AFM recording, and nanoparticle injections and tracking. This approach makes these methods easily adaptable to other developmental times or organisms.

The lack of tools to measure material properties and tensional parameters in vivo prevents validating their roles during development. We employed atomic force microscopy (AFM) and nanoparticle-tracking to quantify mechanical features on the intact zebrafish embryo yolk cell during epiboly. These methods are reliable and widely applicable avoiding intrusive interventions.

Elucidating the factors that direct the spatio-temporal organization of evolving tissues is one of the primary purposes in the study of development. ...

Visualization of Cellular Electrical Activity in Zebrafish Early Embryos and Tumors

Bioelectricity, endogenous electrical signaling mediated by ion channels and pumps located on the cell membrane, plays important roles in signaling processes of excitable neuronal and muscular cells and many other biological processes, such as embryonic developmental patterning. However, there is a need for in vivo electrical activity monitoring in vertebrate embryogenesis. The advances of genetically encoded fluorescent voltage indicators (GEVIs) have made it possible to provide a solution for this challenge. Here, we describe how to create a transgenic voltage indicator zebrafish using the established voltage indicator, ASAP1 (Accelerated Sensor of Action Potentials 1), as an example. The Tol2 kit and a ubiquitous zebrafish promoter, ubi, were chosen in this study. We also explain&#160;the processes of Gateway site-specific cloning, Tol2 transposon-based zebrafish transgenesis, and the imaging process for early-stage fish embryos and fish tumors using regular epifluorescent microscopes. Using this fish line, we found that there are cellular electric voltage changes during zebrafish embryogenesis, and fish larval movement. Furthermore, it was observed that in a few zebrafish malignant peripheral nerve sheath tumors, the tumor cells were generally polarized compared to the surrounding normal tissues.

Here, we show the process of creating a cellular electric voltage reporter zebrafish line to visualize embryonic development, movement, and fish tumor cells in vivo.

Bioelectricity, endogenous electrical signaling mediated by ion channels and pumps located on the cell membrane, plays important roles in signaling ...

Clonal Genetic Tracing using the Confetti Mouse to Study Mineralized Tissues

Labeling an individual cell in the body to monitor which cell types it can give rise to and track its migration through the organism or determine its longevity can be a powerful way to reveal mechanisms of tissue development and maintenance. One of the most important tools currently available to monitor cells in vivo is the Confetti mouse model. The Confetti model can be used to genetically label individual cells in living mice with various fluorescent proteins in a cell type-specific manner and monitor their fate, as well as the fate of their progeny over time, in a process called clonal genetic tracing or clonal lineage tracing. This model was generated almost a decade ago and has contributed to an improved understanding of many biological processes, particularly related to stem cell biology, development, and renewal of adult tissues. However, preserving the fluorescent signal until image collection and simultaneous capturing of various fluorescent signals is technically challenging, particularly for mineralized tissue. This publication describes a step-by-step protocol for using the Confetti model to analyze growth plate cartilage that can be applied to any mineralized or nonmineralized tissue.

This method describes the use of the R26R-Confetti (Confetti) mouse model to study mineralized tissues, covering all steps from the breeding strategy to the image acquirements. Included is a general protocol that can be applied to all soft tissues and a modified protocol that can be applied to mineralized tissues.

Labeling an individual cell in the body to monitor which cell types it can give rise to and track its migration through the organism or determine its ...

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 ...