Name: incremental temperature changes for maximal breeding and spawning in astyanax mexicanus
Uploaded: 2021-02-14T12:30:00
Description: Watch this Scientific Journal Video about Incremental Temperature Changes for Maximal Breeding and Spawning in Astyanax mexicanus at JoVE.com

We thank David Martasian, Diedre Heyser, Amy Parkhurst, Craig Foote, and Mandy Ng for valuable contributions to the Jeffery laboratory A. mexicanus culture facility. The research in the Jeffery laboratory is currently supported by NIH grant EY024941.

This procedure has been approved by Institutional Animal Care guidelines of the University of Maryland, College Park (Currently IACUC 469 #R-NOV-18-59; Project 1241065-1).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/61708/61708fig1.jpg" /> 
Figure 1. Calendars during a breeding week and a non-breeding week. <a href="https://www.jove.com/files/ftp_upload/61708/61708fig1large.jpg" target="_blank">Please click here to view a la...

<ol>
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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+and+development+in+the+cavefish+Astyanax.">Evolution and development in the cavefish Astyanax.</a> Current Topics in Developmental Biology. 86, 191-221 (2009).</li><li>Protas, M. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+analysis+of+cavefish+reveals+molecular+convergence+in+the+evolution+of+albinism.">Genetic analysis of cavefish reveals molecular convergence in the evolution of albinism.</a> Nature Genetics. 38, 107-111 (2006).</li><li>Protas, M., Conrad, M., Gross, J. B., Tabin, C. J., Borowsky, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regressive+evolution+in+the+Mexican+cave+tetra,+Astyanax+mexicanus.">Regressive evolution in the Mexican cave tetra, Astyanax mexicanus.</a> Current Biology. 17, 452-454 (2007).</li><li>O'Quin, K. E., Yoshizawa, M., Doshi, P., Jeffery, W. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+genetic+analysis+of+retinal+degeneration+in+the+blind+cavefish.">Quantitative genetic analysis of retinal degeneration in the blind cavefish.</a> PLoS ONE. 8 (2), 57281 (2013).</li><li>Yoshizawa, M., 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=Distinct+genetic+architecture+underlies+the+emergence+of+sleep+loss+and+prey-seeking+behavior+in+the+Mexican+cavefish.">Distinct genetic architecture underlies the emergence of sleep loss and prey-seeking behavior in the Mexican cavefish.</a> BMC Biology. 13, 15 (2015).</li><li>Elliot, W. 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C., Tort, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Netting+the+stress+responses+in+fish.">Netting the stress responses in fish.</a> Frontiers in Endocrinology. 10, 62 (2019).</li><li>Borowsky, 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> Determining the sex of adult Astyanax mexicanus. , (2008).</li><li>Paschos, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circadian+clocks,+feeding+time,+and+metabolic+homeostasis.">Circadian clocks, feeding time, and metabolic homeostasis.</a> Frontiers in Pharmacology. 6, 112 (2015).</li><li>Scheiermann, C., Kunisaki, Y., Frenette, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circadian+control+of+the+immune+system.">Circadian control of the immune system.</a> Nature Reviews Immunology. 13, 190-198 (2013).</li><li>Williams, M. B., Watts, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+basis+and+future+directions+of+zebrafish+nutrigenomics.">Current basis and future directions of zebrafish nutrigenomics.</a> Genes &amp; Nutrition. 14, 34 (2009).</li><li>Harper, C., Wolf, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphologic+effects+of+the+stress+response+in+fish.">Morphologic effects of the stress response in fish.</a> ILAR Journal. 50, 387-396 (2009).</li><li>Neubauer, P., Andersen, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+performance+in+fish+is+explained+by+an+interplay+between+physiology,+behavior+and+ecology.">Thermal performance in fish is explained by an interplay between physiology, behavior and ecology.</a> Conservation Physiology. 7 (1), 025 (2019).</li><li>Hinaux, 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=Developmental+staging+table+for+Astyanax+mexicanus.">Developmental staging table for Astyanax mexicanus.</a> Zebrafish. 8 (4), (2011).</li><li>Borowsky, 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> In vitro fertilization of Astyanax mexicanus. , (2008).</li><li>Simon, V., Hyacinthe, C., R&#233;taux, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breeding+behavior+in+the+blind+Mexican+cavefish+and+its+river-dwelling+conspecific.">Breeding behavior in the blind Mexican cavefish and its river-dwelling conspecific.</a> PLoS One. 14 (2), 0212591 (2019).</li><li>Harvey, B. J., Carolsfield, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induced+Breeding+in+Tropical+Fish+Culture.">Induced Breeding in Tropical Fish Culture.</a> International Development Research Centre. , (1993).</li><li>Ma, L., Parkhurst, A., Jeffery, W. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+a+lens+survival+pathway+including+sox2+and+aA-crystallin+in+the+evolution+of+cavefish+eye+degeneration.">The role of a lens survival pathway including sox2 and aA-crystallin in the evolution of cavefish eye degeneration.</a> EvoDevo. 5, 28 (2014).</li><li>Krishnan, J., Rohner, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cavefish+and+the+basis+for+eye+loss.">Cavefish and the basis for eye loss.</a> Philosophical Transactions of the Royal Society B: Biological Sciences. 5 (372), 20150487 (2017).</li><li>Biland&#382;ija, H., Abraham, L., Ma, L., Renner, K., Jeffery, W. 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Astyanax mexicanus is a novel biological model that spawns frequently and can be bred easily in the laboratory1,2. Because we are interested in the developmental mechanisms that underlie evolutionary changes in A. mexicanus cave fish, the production and use of embryos is vital to our research goals. The primary purpose of maintaining an adult stock of fish is the production of embryos and young fry for use in developmental experiments and for re...

The teleost Astyanax mexicanus has an eyed surface-dwelling (surface fish) form and many different blind cave-dwelling (cave fish) forms1,2. Cave fish have evolved in perpetual darkness and under food limitations, resulting in the appearance of novel constructive and regressive traits3. The constructive traits include increases in taste buds and jaw size, sensory organs of the lateral line, and fat reserves. The regressive traits include the loss or reduction of melanin pigmentation, eyes, and behaviors, such as sleep, schooling, and aggression. An attribute of the Astyanax system is complete fertility between the two forms, allowing the use of quantitative trait loci (QTL) mapping to determine the genomic region(s) associated with constructive and regressive evolution4,5,6,7. A. mexicanus offers an advantageous system to study development because it can be induced to spawn frequently in the laboratory. The embryos of A. mexicanus are translucent, slightly larger than those of zebrafish, produced in large quantities, and develop into sexually mature adults in approximately 8-12 months. Their period of maximal spawning capacity is about 5 years. This protocol describes the workflow needed in an A. mexicanus culture facility during a typical breeding week and includes the details of fish system maintenance and the temperature control regime for maximal spawning.
A. mexicanus is a tropical fish that lives in rivers originating in limestone plateaus (surface fish) and in pools in limestone caves (cave fish)8. Limestone dissolves to produce hard water, and A. mexicanus thrives in hard water. Fish adapted to hard water conditions can tolerate a range of salty conditions, but generally breed in specific ones9. Induction of spawning behavior is accomplished by a combination of factors. Because fish are cold-blooded and rely on their environment to maintain homeostasis, their metabolism is sensitive to environmental changes and they react more quickly to stressors10. A. mexicanus should be cultured in aquatic systems under carefully regulated conditions of water flow, pH, conductivity, osmotic pressure, lighting, and water temperatures.
In the Jeffery laboratory, fish are maintained in two running water systems: (1) a &#8220;baby system&#8221; for young adult fish prior to sexual maturity and (2) an adult (or main) system for sexually mature, breeding adults. The &#8220;baby system&#8221; consists of 8 L and 15 L tanks supplied with running water. The &#8220;baby system&#8221; is seeded by fry and young metamorphosized juveniles grown from larvae in smaller (1-10 L) tanks, in which water is exchanged weekly. Larvae, fry, and juveniles are extremely food dependent and must be fed live food (brine shrimp) once a day to ensure a high rate of survival. Young juveniles from the &#8220;baby system&#8221; are placed into the adult system after about 1-1.5 years. At first, they are fed pulverized tetra flakes, and after further growth they are transferred to the regular adult feeding regime. Sexual maturity can be assessed by abdominal volume in females, and methods for determining sex have been described11. In the adult system, water is exchanged automatically in 42 L tanks 3 times per 24-hour period. The adult system is monitored daily by visual inspection and automatic temperature, pH, and conductivity readings from probes. The optimal pH is around 7.4 and can range between 6.8-7.5, the base temperature of the system is 72/73 &#176;F, and the ideal conductivity ranges between 600-800 mS. Automatic readings are displayed on a controller screen, and visual checks of water pressure are read at flow meters distributed throughout the system. Independent checks on water quality are made weekly by testing temperature and measuring water quality parameters for pH, ammonia, and nitrate using a colorimetric test. Ammonia and nitrate levels are kept at or close to zero by adding beneficial bacteria (e.g., Nutafin Cycle) to the system. Room lighting is controlled by a timer adjusted to 14-hour light and 10-hour dark periods. In addition to the overall water quality parameters mentioned above, the following considerations need special attention during a breeding week.
The first consideration is photoperiod, as fish (even cave fish in the laboratory) depend on light cycles to set their circadian clock. Circadian rhythms can affect everything from breeding and feeding to immune system health12,13 and must be consistent for maximum health benefits. Fish are maintained in a running-water system on a 14-hour light and 10-hour dark photoperiod. The surface fish generally begin spawning an hour after the system has been darkened, and light introduced during this period can interfere with and terminate spawning. The spawning of blind cave fish is less disturbed by light. Compared to surface fish spawning, cave fish spawning is delayed, usually beginning four to five hours after the system has been darkened.
The second consideration is nutrition. Adult fish are normally fed a diet of tetra flakes once a day. Prior to spawning, fish are fed a protein-rich diet supplemented with extra amounts of tetra flakes and other food: egg yolk flakes and occasionally living California blackworms (Lumbriculus variegatus) to compensate for protein loss due to egg production during the previous spawning cycle. During the breeding week, fish are fed twice per day, once in the morning and again in the afternoon/evening. Fish feeding only once a day but with a single very large portion of food should be avoided, as this can cause malnutrition14.
The third consideration is space. The space requirements are based on the average body mass of an adult as well as behavioral considerations, such as whether the fish have schooling behavior or aggressive behavior. Over or under-crowding tanks can lead to heightened aggression and constant stress, making fish vulnerable to injury from their tank mates and reluctant to participate in spawning15. We typically house 10-20 fish per 42 L tank.
The fourth consideration is temperature. As mentioned above, fish are cold-blooded animals and rely on the environment to maintain body temperature. Because temperature has a direct effect on metabolic processes, changes in temperature can trigger behavioral alterations in fish16. This breeding program consists of two-week cycles in temperature: the first week introduces a temperature spike to 78 &#176;F, and the next week maintains a static temperature of 72 &#176;F. During the first (breeding) week, plastic-edged breeding nets are placed at the bottom of the tanks each evening. The breeding nets serve as a barrier between the fish in the tanks and the spawned eggs, which would otherwise be consumed. The temperature is raised by 2 &#176;F per day to a maximum of 78 &#176;F by mid-week, and spawning is induced according to the light cycle in the first 2-3 evenings of this week. The temperature is then lowered by 2 &#176;F increments to 72 &#176;F during the remaining days of the week, and base temperature is maintained until the beginning of the next breeding week. Breeding is usually stimulated no more than twice a month to allow the fish time to recover.
Overall, this method allows for the spawning of large&#160;quantities of the highest quality embryos over a longer period of time.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Blackworms</td>
			<td style="width:299px;">Eastern Aquatics, Lancaster, PA</td>
			<td style="width:161px;">None</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Breeding Nets</td>
			<td style="width:299px;">Custom made</td>
			<td style="width:161px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Brine shrimp eggs</td>
			<td style="width:299px;">AquaCave Lake Forest, IL.</td>
			<td style="width:161px;">None</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Colorimetric test kit</td>
			<td style="width:299px;">Petco</td>
			<td style="width:161px;">SKU:11916</td>
			<td>API Freshwater pH Test Kit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Egg yolk flakes</td>
			<td style="width:299px;">Pentair, Minneapolis, MN</td>
			<td style="width:161px;">None</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Fingerbowls</td>
			<td style="width:299px;">Carolina Biological Supply</td>
			<td align="right" style="width:161px;">741004</td>
			<td>Culture dishes, 4.5 in, 250 mL</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Hand held nets</td>
			<td style="width:299px;">Any Pet Store</td>
			<td style="width:161px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Incubator for embryos</td>
			<td style="width:299px;">Fisher Scientific</td>
			<td style="width:161px;">51-029-321HPM</td>
			<td>405 L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Instant Ocean sea salts</td>
			<td style="width:299px;">Spectrum Brands, Blacksburg, VA</td>
			<td style="width:161px;">None</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Methylene Blue</td>
			<td style="width:299px;">Sigma-Aldrich, St. Louis, MO</td>
			<td style="width:161px;">M9140</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Pasteur Pipettes</td>
			<td style="width:299px;">Fisher Scientific</td>
			<td style="width:161px;">13-678-20</td>
			<td>5.75 in.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Net soaking solution</td>
			<td style="width:299px;">Any Pet Store</td>
			<td style="width:161px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Nutrafin Cycle</td>
			<td style="width:299px;">Amazon</td>
			<td style="width:161px;">None</td>
			<td>Bacterial boost</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Refrigerator for live feed</td>
			<td style="width:299px;">Any source</td>
			<td style="width:161px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Stereomicroscope</td>
			<td style="width:299px;">Any source</td>
			<td style="width:161px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Thermometer</td>
			<td style="width:299px;">Any source</td>
			<td style="width:161px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:248px;">Tetra Tropical Crisps</td>
			<td style="width:299px;">Spectrum Brands, Blacksburg, VA</td>
			<td style="width:161px;">None</td>
			<td></td>
		</tr>
	</tbody>
</table>

incremental temperature changes for maximal breeding and spawning in astyanax mexicanus

The Mexican tetra, Astyanax mexicanus, is an emerging model system for studies in development and evolution. The existence of eyed surface (surface fish) and blind cave (cave fish) morphs in this species presents an opportunity to interrogate the mechanisms underlying morphological and behavioral evolution. Cave fish have evolved novel constructive and regressive traits. The constructive changes include increases in taste buds and jaws, lateral line sensory organs, and body fat. The regressive changes include loss or reduction of eyes. melanin pigmentation, schooling behavior, aggression, and sleep. To experimentally interrogate these changes, it is crucial to obtain large numbers of spawned embryos. Since the original A. mexicanus surface fish and cave fish were collected in Texas and Mexico in the 1990s, their descendants have been routinely stimulated to breed and spawn large numbers of embryos bimonthly in the Jeffery laboratory. Although breeding is controlled by food abundance and quality, light-dark cycles, and temperature, we have found that incremental temperature changes play a key role in stimulating maximal spawning. The gradual increase of temperature from 72 &#176;F to 78 &#176;F in the first three days of a breeding week provides two-three consecutive spawning days with maximal numbers of high-quality embryos, which is then followed by a gradual decrease of temperature from 78 &#176;F to 72 &#176;F during the last three days of the spawning week. The procedures shown in this video outline the workflow before and during a laboratory breeding week for incremental temperature stimulated spawning.

We generally breed and spawn the descendants of surface fish originally collected at Nacimiento del Rio Choy in San Luis Potosi, Mexico (Rio Choy surface fish) and San Solomon Springs in Balmorhea State Park, Texas (Texas surface fish) and cave fish derived from Cueva de El Pach&#243;n (Pach&#243;n cave fish) in Tamaulipas, Mexico, and Cueva de los Sabinos (Los Sabinos cave fish) and Sotano de la Tinaja (Tinaja cave fish) in San Luis Potosi, Mexico. &#160;
Throughout a breeding week, data is c...

Watch this Scientific Journal Video about Incremental Temperature Changes for Maximal Breeding and Spawning in Astyanax mexicanus at JoVE.com

Incremental Temperature Changes for Maximal Breeding and Spawning in Astyanax mexicanus

This article outlines the basic laboratory conditions and protocols for an incremental temperature regime to stimulate maximal spawning in the Mexican tetra Astyanax mexicanus, which is an emerging model for developmental and evolutionary studies.

Incremental Temperature Changes for Maximal Breeding and Spawning in Astyanax mexicanus

The Mexican tetra, Astyanax mexicanus, is an emerging model system for studies in development and evolution. The existence of eyed surface (surface fish) ...

So as the Astyanax mexicanas is a small fish. It is indigenous to Northeastern Mexico and Southern Texas. The important thing about it is it exists in two forms.One form is a surface dwelling fish that has large eyes and pigmentation, and the other form is a cave-dwelling fish that has lost its eyes and lost its pigmentation. They're still capable of spawning, of hybridizing with each other, so they can be used in a forward genetic analysis to study genetics and development. Also have large embryos that are transparent, and they can be used to study comparative developmental biology.So they've been used for many years now as a system to understand the evolution of development. Several days before the spawning is desired, we begin to feed the fish better. We also increase the temperature incrementally such that within the time we want them to spawn, they will then undergo about two or three days of excessive spawning, producing large numbers of fertilized embryos that develop well and through the larval stages to adults.After feeding the fish at 10:00 a.m. with a pinch of Tetra flakes, check the incubator that will be used to house finger bowls of developing embryos and change the water if necessary. Check the water level in all of the reservoirs and add system water to any reservoirs that are running low.Then set the incubator to 23 degrees Celsius At least 30 minutes after the first feeding, feed the fish in the breeding tanks with a pinch of egg yolk flakes, enough black worm clusters to allow each fish in the tank to consume about five to 10 worms or both. At least one hour after the second feeding, scrub the breeding tanks as necessary and carefully set up breeding nets without interfering with the tank air supply. The next morning, remove the breeding nets from the bottoms of the adult system tanks between 9:00 and 10:00 a.m.and use the hose attached to the to gently rinse the embryos into a handheld net. Invert the net into a finger bowl of clean system water and transfer about 100 embryos per finger bowl into 200 milliliters of clean system water supplemented with 0.00003%methylene blue. Stage the embryos under a light microscope to estimate the time of fertilization according to the A-mexicanas developmental timetable.After staging, place the finger bowls into an incubator for five to seven days and feed the cultures with living brine shrimp. For every tank that dropped embryos, record the date and tank number and record the number and quality of embryos dropped. Record the average time of spawn according to staging table and record the temperature of the system at the time when the fish spawned.Monitor the finger bowls of embryos throughout the day, using a pasture pipette to remove any dead or deformed embryos and debris, such as uneaten food or feces, and changing the blue water as necessary. At 1:00 p.m. feed the fish in the breeding tanks as demonstrated and set the water temperature to 24 degrees Celsius.Then remove any excess food and debris from the tanks and scrub the tanks before resetting the nets. On Wednesday and Thursday, repeat the embryo collection and evaluation as demonstrated for Tuesday. Feed the fish and set the water to the appropriate temperature.Check the embryos in the incubator and replace the finger bowl water with fresh methylene blue treated system water. Then clean the breeding tanks as needed and reset the nets. On Friday, after feeding the fish, set the water temperature to 23 degrees Celsius and check the embryos in the incubator.On Saturday and Sunday, feed the fish. In this figure, the breeding data from July 2017 through March 2020 for the Rio Choy and Texas Surface Fish and the Los Sabinos, Tinaha, and Pachon cavefish are shown. The data were analyzed by breeding week and the average number of embryos collected per day during a single breeding week.The data indicates that breeding was continuous throughout the year in Rio Choy and Texas Surface fish and in Pachon cavefish. The quantity and quality of most Rio Choy surface fish was between low and high, while the quantity and quality of most Texas surface fish and Pachon cavefish was between low and medium. The occurrence of spawning was not continuous in Tinaja or Los Sabinos cave fish, with spawning being low or non-existent during the late summer to autumn in these fish.Although the lowest levels of spawning were recorded for Los Sabinos cave fish, the quality of embryos was the best. Overall, this surface fish exhibited a better spawning quantity and quality than cavefish. Using this system, we can spawn hundreds, actually thousands of eggs bi-monthly, and these eggs are then used, these embryos are then used for many different purposes.

incremental-temperature-changes-for-maximal-breeding-spawning

Research

JoVE Journal

Developmental Biology

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 of Cell Shape Alteration and Cell Movement in Drosophila Gastrulation Using DE-cadherin Reporter Transgenic Flies

Gastrulation is the first set of morphologically dynamic events that occur during the embryonic development of multicellular animals such as Drosophila. This morphological alteration is also recognized as epithelial to mesenchymal transition (EMT). Dysregulation of EMT is associated with fibrosis and cancer metastasis. There is emerging evidence that EMT is controlled by a number of molecular mechanisms. As such, many key genes that control apical constriction are also known to be important factors in the EMT observed in cancer metastasis. Like EMT during Drosophila gastrulation, epithelial cells can be induced to change their shape and be reprogrammed to redirect cell fate towards various other cell types. Here we provide a robust imaging method of Drosophila gastrulation to assay the initiation of morphogenetic cellular movements and cell fate identification during this stage of embryonic development. Using this method, we identify cell rearrangement at the time of gastrulation and demonstrate the importance of apical constriction during gastrulation using GFP labeled DE-cadherin.

Imaging of Cell Shape Alteration and Cell Movement in Drosophila Gastrulation Using DE-cadherin Reporter Transgenic Flies

Herein we describe a procedure to capture live images of Drosophila gastrulation. This has enabled us to better understand the apical constriction involved in early development and further analyze mechanisms governing cellular movements during tissue structure modification.

Gastrulation is the first set of morphologically dynamic events that occur during the embryonic development of multicellular animals such as Drosophila. ...

A Novel Mammary Fat Pad Transplantation Technique to Visualize the Vessel Generation of Vascular Endothelial Stem Cells

Endothelial cells (ECs) are the fundamental building blocks of the vascular architecture and mediate vascular growth and remodeling to ensure proper vessel development and homeostasis. However, studies on endothelial lineage hierarchy remain elusive due to the lack of tools to gain access as well as to directly evaluate their behavior in vivo. To address this shortcoming, a new tissue model to study angiogenesis using the mammary fat pad has been developed. The mammary gland develops mostly in the postnatal stages, including puberty and pregnancy, during which robust epithelium proliferation is accompanied by extensive vascular remodeling. Mammary fat pads provide space, matrix, and rich angiogenic stimuli from the growing mammary epithelium. Furthermore, mammary fat pads are located outside the peritoneal cavity, making them an easily accessible grafting site for assessing the angiogenic potential of exogenous cells. This work also describes an efficient tracing approach using fluorescent reporter mice to specifically label the targeted population of vascular endothelial stem cells (VESCs) in vivo. This lineage tracing method, coupled with subsequent tissue whole-mount microscopy, enable the direct visualization of targeted cells and their descendants, through which the proliferation capability can be quantified and the differentiation commitment can be fate-mapped. Using these methods, a population of bipotent protein C receptor (Procr) expressing VESCs has recently been identified in multiple vascular systems. Procr+ VESCs, giving rise to both new ECs and pericytes, actively contribute to angiogenesis during development, homeostasis, and injury repair. Overall, this manuscript describes a new mammary fat pad transplantation and in vivo lineage tracing techniques that can be used to evaluate the stem cell properties of VESCs.

This work demonstrates a novel approach to assess the proliferation, differentiation, and vessel-forming potential of vascular endothelial stem cells (VESCs) through mammary fat pad transplantation followed by whole-mount tissue preparation for microscopic observation. A lineage tracing strategy to investigate the behavior of VESCs in vivo is also presented.

Endothelial cells (ECs) are the fundamental building blocks of the vascular architecture and mediate vascular growth and remodeling to ensure proper ...

Dissection and Immunofluorescent Staining of Mushroom Body and Photoreceptor Neurons in Adult Drosophila melanogaster Brains

Nervous system development involves a sequential series of events that are coordinated by several signaling pathways and regulatory networks. Many of the proteins involved in these pathways are evolutionarily conserved between mammals and other eukaryotes, such as the fruit fly Drosophila melanogaster, suggesting that similar organizing principles exist during the development of these organisms. Importantly, Drosophila has been used extensively to identify cellular and molecular mechanisms regulating processes that are required in mammals including neurogenesis, differentiation, axonal guidance, and synaptogenesis. Flies have also been used successfully to model a variety of human neurodevelopmental diseases. Here we describe a protocol for the step-by-step microdissection, fixation, and immunofluorescent localization of proteins within the adult Drosophila brain. This protocol focuses on two example neuronal populations, mushroom body neurons and retinal photoreceptors, and includes optional steps to trace individual mushroom body neurons using Mosaic Analysis with a Repressible Cell Marker (MARCM) technique. Example data from both wild-type and mutant brains are shown along with a brief description of a scoring criteria for axonal guidance defects. While this protocol highlights two well-established antibodies for investigating the morphology of mushroom body and photoreceptor neurons, other Drosophila brain regions and the localization of proteins within other brain regions can also be investigated using this protocol.

Dissection and Immunofluorescent Staining of Mushroom Body and Photoreceptor Neurons in Adult Drosophila melanogaster Brains

This protocol describes the dissection and immunostaining of adult Drosophila melanogaster brain tissues. Specifically, this protocol highlights the use of Drosophila mushroom body and photoreceptor neurons as example neuronal subsets that can be accurately used to uncover general principles underlying many aspects of neuronal development.

Nervous system development involves a sequential series of events that are coordinated by several signaling pathways and regulatory networks. Many of the ...

Application of RNAi and Heat-shock-induced Transcription Factor Expression to Reprogram Germ Cells to Neurons in C. elegans

Studying the cell biological processes during converting the identities of specific cell types provides important insights into mechanism that maintain and protect cellular identities. The conversion of germ cells into specific neurons in the nematode Caenorhabditis elegans (C. elegans) is a powerful tool for performing genetic screens in order to dissect regulatory pathways that safeguard established cell identities. Reprogramming of germ cells to a specific type of neurons termed ASE requires transgenic animals that allow broad over-expression of the Zn-finger transcription factor (TF) CHE-1. Endogenous CHE-1 is expressed exclusively in two head neurons and is required to specify the glutamatergic ASE neurons fate, which can easily be visualized by the gcy-5prom::gfp reporter. A trans gene containing the heat-shock promoter-driven che-1 gene expression construct allows broad mis-expression of CHE-1 in the entire animal upon heat-shock treatment. The combination of RNAi against the chromatin-regulating factor LIN-53 and heat-shock-induced che-1 over-expression leads to reprogramming of germ cell into ASE neuron-like cells. We describe here the specific RNAi procedure and appropriate conditions for heat-shock treatment of transgenic animals in order to successfully induce germ cell to neuron conversion.

Application of RNAi and Heat-shock-induced Transcription Factor Expression to Reprogram Germ Cells to Neurons in C. elegans

This protocol describes how to study cellular processes during cell fate conversion in Caenorhabditis elegans in vivo. Using transgenic animals, allowing heat-shock promoter-driven overexpression of the neuron fate-inducing transcription factor CHE-1 and RNAi-mediated depletion of the chromatin-regulating factor LIN-53 germ cell to neuron reprogramming can be observed in vivo.

Studying the cell biological processes during converting the identities of specific cell types provides important insights into mechanism that maintain ...

Neurogenesis Using P19 Embryonal Carcinoma Cells

The P19 cell line derived from a mouse embryo-derived teratocarcinoma has the ability to differentiate into the three germ layers. In the presence of retinoic acid (RA), the suspension cultured P19 cell line is induced to differentiate into neurons. This phenomenon is extensively investigated as a neurogenesis model in vitro. Therefore, the P19 cell line is very useful for molecular and cellular studies associated with neurogenesis. However, protocols for neuronal differentiation of P19 cell line described in the literature are very complex. The method developed in this study are simple and will play a part in elucidating the molecular mechanisms in neurodevelopmental abnormalities and neurodegenerative diseases.

The P19 mouse embryonic carcinoma cell line (P19 cell line) is widely used for studying the molecular mechanism of neurogenesis with great simplification compared to in vivo analysis. Here, we present a protocol for retinoic acid-induced neurogenesis in the P19 cell line.

The P19 cell line derived from a mouse embryo-derived teratocarcinoma has the ability to differentiate into the three germ layers. In the presence of ...

Visualizing the Node and Notochordal Plate In Gastrulating Mouse Embryos Using Scanning Electron Microscopy and Whole Mount Immunofluorescence

The post-implantation mouse embryo undergoes major shape changes after the initiation of gastrulation and morphogenesis. A hallmark of morphogenesis is the formation of the transient organizers, the node and notochordal plate, from cells that have passed through the primitive streak. The proper formation of these signaling centers is essential for the development of the body plan and techniques to visualize them are of high interest to mouse developmental biologists. The node and notochordal plate lie on the ventral surface of gastrulating mouse embryos around embryonic day (E) 7.5 of development. The node is a cup-shaped structure whose cells possess a single slender cilium each. The proper subcellular localization and rotation of the cilia in the node pit determines left-right asymmetry. The notochordal plate cells also possess single cilia albeit shorter than those of the node cells. The notochordal plate forms the notochord which acts as an important signaling organizer for somitogenesis and neural patterning. Because the cells of the node and notochordal plate are transiently present on the surface and possess cilia, they can be visualized using scanning electron microscopy (SEM). Among other techniques used to visualize these structures at the cellular level is whole mount immunofluorescence (WMIF) using the antibodies against the proteins that are highly expressed in the node and notochordal plate. In this report, we describe our optimized protocols to perform SEM and WMIF of the node and notochordal plate in developing mouse embryos to help in the assessment of tissue shape and cellular organization in wild-type and gastrulation mutant embryos.

The node and notochordal plate are transient signaling organizers in developing mouse embryos that can be visualized using several techniques. Here, we describe in detail how to perform two of the techniques to study their structure and morphogenesis: 1) scanning electron microscopy (SEM); and 2) whole mount immunofluorescence (WMIF).

The post-implantation mouse embryo undergoes major shape changes after the initiation of gastrulation and morphogenesis. A hallmark of morphogenesis is ...

Tissue Preparation and Immunostaining of Mouse Craniofacial Tissues and Undecalcified Bone

Tissue immunostaining provides highly specific and reliable detection of proteins of interest within a given tissue. Here we describe a complete and simple protocol to detect protein expression during craniofacial morphogenesis/pathogenesis using mouse craniofacial tissues as examples. The protocol consists of preparation and cryosectioning of tissues, indirect immunofluorescence, image acquisition, and quantification. In addition, a method for preparation and cryosectioning of undecalcified hard tissues for immunostaining is described, using craniofacial tissues and long bones as examples. Those methods are key to determine the protein expression and morphological/anatomical changes in various tissues during craniofacial morphogenesis/pathogenesis. They are also applicable to other tissues with appropriate modifications. Knowledge of the histology and high quality of sections are critical to draw scientific conclusions from experimental outcomes. Potential limitations of this methodology include but are not limited to specificity of antibodies and difficulties of quantification, which are also discussed here.

Here, we present a detailed protocol to detect and quantify protein levels during craniofacial morphogenesis/pathogenesis by immunostaining using mouse craniofacial tissues as examples. In addition, we describe a method for preparation and cryosectioning of undecalcified hard tissues from young mice for immunostaining.

Tissue immunostaining provides highly specific and reliable detection of proteins of interest within a given tissue. Here we describe a complete and ...

Wholemount In Situ Hybridization for Astyanax Embryos

In recent years, a draft genome for the blind Mexican cavefish (Astyanax mexicanus) has been released, revealing the sequence identities for thousands of genes. Prior research into this emerging model system capitalized on comprehensive genome-wide investigations that have identified numerous quantitative trait loci (QTL) associated with various cave-associated phenotypes. However, the ability to connect genes of interest to the heritable basis for phenotypic change remains a significant challenge. One technique that can facilitate deeper understanding of the role of development in troglomorphic evolution is whole-mount in situ hybridization. This technique can be implemented to directly compare gene expression between cave- and surface-dwelling forms, nominate candidate genes underlying established QTL, identify genes of interest from next-generation sequencing studies, or develop other discovery-based approaches. In this report, we present a simple protocol, supported by a flexible checklist, that can be widely adapted for use well beyond the presented study system. It is hoped that this protocol can serve as a broad resource for the Astyanax community and beyond.

Wholemount In Situ Hybridization for Astyanax Embryos

This protocol enables visualization of gene expression in embryonic Astyanax cavefish. This approach has been developed with the goal of maximizing gene expression signal, while minimizing non-specific background staining.

In recent years, a draft genome for the blind Mexican cavefish (Astyanax mexicanus) has been released, revealing the sequence identities for thousands of ...

Controlled Cortical Impact Model of Mouse Brain Injury with Therapeutic Transplantation of Human Induced Pluripotent Stem Cell-Derived Neural Cells

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide. Disease pathology due to TBI progresses from the primary mechanical insult to secondary injury processes, including apoptosis and inflammation. Animal modeling has been valuable in the search to unravel injury mechanisms and evaluate potential neuroprotective therapies. This protocol describes the controlled cortical impact (CCI) model of focal, open-head TBI. Specifically, parameters for producing a mild unilateral cortical injury are described. Behavioral consequences of CCI are analyzed using the adhesive tape removal test of bilateral sensorimotor integration. Regarding experimental therapy for TBI pathology, this protocol also illustrates a process for transplanting cultured cells into the brain. Neural cell cultures derived from human induced pluripotent stem cells (hiPSCs) were chosen for their potential to show superior functional restoration in human TBI patients. Chronic survival of hiPSCs in the host mouse brain tissue is detected using a modified DAB immunohistochemical process.

This protocol demonstrates methodologies for a mouse model of open-skull traumatic brain injury and transplantation of cultured human induced pluripotent stem cell-derived cells into the injury site. Behavioral and histologic tests of outcomes from these procedures are also described in brief.

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide. Disease pathology due to TBI progresses from the primary mechanical ...