Name: protocol for acute and chronic ecotoxicity testing of the turquoise killifish nothobranchius furzeri
Uploaded: 2018-04-24T14:30:00
Description: Watch this Scientific Journal Video about Protocol for Acute and Chronic Ecotoxicity Testing of the Turquoise Killifish Nothobranchius furzeri at JoVE.com

We are grateful to the SPHERE group of the UAntwerpen and the Department of crop protection of the Ugent for analysis of water samples. Support during this project was provided by the Excellence Center &#39;Eco and socio-evolutionary dynamics (PF/10/007) of the KU Leuven Research Fund. AFG (11Q0516N) and ESJT (FWO-SB151323) were funded as doctoral and TP (12F0716N) as post-doctoral fellow by FWO Flanders (Fonds Wetenschappelijk Onderzoek).

All methods described here have been approved by the Ethical committee of KULeuven.
1. Hatching and General Maintenance of N. furzeri 
<ol>
	<li>Prepare fish medium (pH 7) at a temperature of 14 &#176;C and add purified Type II water, with added standardized salts, to a conductivity of 600 &#181;S/cm (24 &#176;C).</li>
	<li>Select eggs from the GRZ (Gona-Rhe-Zhou) laboratory line that have been stored under standardized conditions13. Select eggs in the DIII s...

<ol>
	<li>European-Chemicals-Bureau. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> TAPIR Three point three-A Project for the Information Requirements of REACH. Final Report-2 August 2005. Scoping study on the development of a Technical Guidance Document on information requirements on intrinsic properties of substances (RIP 3.3-1). , (2005).</li><li>Philippe, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+and+chronic+sensitivity+to+copper+of+a+promising+ecotoxicological+model+species,+the+annual+killifish+Nothobranchius+furzeri.">Acute and chronic sensitivity to copper of a promising ecotoxicological model species, the annual killifish Nothobranchius furzeri.</a> Ecotoxicol Environ Saf. , 26-35 (2017).</li><li>Noyes, P. D., Lema, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Forecasting+the+impacts+of+chemical+pollution+and+climate+change+interactions+on+the+health+of+wildlife.">Forecasting the impacts of chemical pollution and climate change interactions on the health of wildlife.</a> Current Zoology. 61 (4), 669-689 (2015).</li><li>Consommateurs, S. S. d. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Health &amp; Consumer Protection Directorate-General European Commission. 4, (2002).</li><li>Commission, E. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guidance+document+on+aquatic+ecotoxicology.+Under+Council+directive+91/414/EEC.">Guidance document on aquatic ecotoxicology. Under Council directive 91/414/EEC.</a> SANCO/3268/2001 Rev 4. 2002b. , (2002).</li><li>. Ecological Effects Test Guidelines, OPPTS 850.1500 Fish life cycle toxicity Available from: <a target="_blank" href="https://www.epa.gov/sites/production/files/2015-07/documents/850-1500.pdf">https://www.epa.gov/sites/production/files/2015-07/documents/850-1500.pdf</a> (1996)</li><li>Philippe, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+and+chronic+sensitivity+to+copper+of+a+promising+ecotoxicological+model+species,+the+annual+killifish+Nothobranchius+furzeri.">Acute and chronic sensitivity to copper of a promising ecotoxicological model species, the annual killifish Nothobranchius furzeri.</a> Ecotoxicol Environ Saf. , (2017).</li><li>Ankley, G. T., Villeneuve, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+fathead+minnow+in+aquatic+toxicology:+past,+present+and+future.">The fathead minnow in aquatic toxicology: past, present and future.</a> Aquatic Toxicology. 78 (1), 91-102 (2006).</li><li>Pola&#269;ik, M., Bla&#382;ek, R., Reichard, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laboratory+breeding+of+the+short-lived+annual+killifish+Nothobranchius+furzeri.">Laboratory breeding of the short-lived annual killifish Nothobranchius furzeri.</a> Nature Protocols. 11 (8), 1396-1413 (2016).</li><li>Reichwald, K., 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=Insights+into+Sex+Chromosome+Evolution+and+Aging+from+the+Genome+of+a+Short-Lived+Fish.">Insights into Sex Chromosome Evolution and Aging from the Genome of a Short-Lived Fish.</a> Cell. 163 (6), 1527-1538 (2015).</li><li>Valenzano, D. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+African+Turquoise+Killifish+Genome+Provides+Insights+into+Evolution+and+Genetic+Architecture+of+Lifespan.">The African Turquoise Killifish Genome Provides Insights into Evolution and Genetic Architecture of Lifespan.</a> Cell. 163 (6), 1539-1554 (2015).</li><li>Shedd, T. R., Widder, M. W., Toussaint, M. W., Sunkel, M. C., Hull, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+the+annual+killifish+Nothobranchius+guentheri+as+a+tool+for+rapid+acute+toxicity+screening.">Evaluation of the annual killifish Nothobranchius guentheri as a tool for rapid acute toxicity screening.</a> Environ. Toxicol. Chem. 18 (10), 2258-2261 (1999).</li><li>Platzer, M., Englert, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nothobranchius+furzeri:+a+model+for+aging+research+and+more.">Nothobranchius furzeri: a model for aging research and more.</a> Trends Genet. 32 (9), 543-552 (2016).</li><li>Watters, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ecology+and+distribution+of+Nothobranchius+fishes.">The ecology and distribution of Nothobranchius fishes.</a> J Am Killifish Assoc. 42, 58-61 (2009).</li><li>Op de Beeck, L., Verheyen, J., Stoks, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Competition+magnifies+the+impact+of+a+pesticide+in+a+warming+world+by+reducing+heat+tolerance+and+increasing+autotomy.">Competition magnifies the impact of a pesticide in a warming world by reducing heat tolerance and increasing autotomy.</a> Environ Pollut. 233, 226-234 (2018).</li><li>Patra, R. W., Chapman, J. C., Lim, R. P., Gehrke, P. 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+effects+of+three+organic+chemicals+on+the+upper+thermal+tolerances+of+four+freshwater+fishes.">The effects of three organic chemicals on the upper thermal tolerances of four freshwater fishes.</a> Environ. Toxicol. Chem. 26 (7), 1454-1459 (2007).</li><li>Beitinger, T. L., Bennett, W. A., McCauley, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temperature+tolerances+of+North+American+freshwater+fishes+exposed+to+dynamic+changes+in+temperature.">Temperature tolerances of North American freshwater fishes exposed to dynamic changes in temperature.</a> Environ Biol Fishes. 58 (3), 237-275 (2000).</li><li>Cellerino, A., Valenzano, D. R., Reichard, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+the+bush+to+the+bench:+the+annual+Nothobranchius+fishes+as+a+new+model+system+in+biology.">From the bush to the bench: the annual Nothobranchius fishes as a new model system in biology.</a> Biological Reviews. , (2015).</li></ol>

This work describes a new bioassay using Nothobranchius furzeri, an emerging model organism, to study the individual and combined long-term effects of toxicants and other stressors. The presented protocols were successfully applied to measure the sensitivity of the species to an array of toxicants (copper, cadmium, 3,4-dichloroaniline, and chlorpyrifos). Due to its fast life-cycle, this vertebrate model allows for assessment of sublethal and transgenerational effects within four months. Another major advantage o...

Sensitivity profiles of an array of species to strategically selected toxicants have been described1 for the European REACH legislation (Registration, Evaluation, Authorization, and Restriction of Chemicals). Acute or short-term toxicity tests were mostly used for this purpose as they give a quick indication of a species&#39; sensitivity. However, in their natural environment, organisms are exposed over much longer periods and full life-cycles or even several generations could be affected2. Moreover, organisms in polluted environments are typically exposed to more than one stressor at a time, which may interact with each other, possibly resulting in synergistic effects3. Hence, safe concentrations calculated based on acute, single stressor toxicity tests may underestimate the actual risks imposed by toxicants in natural environments. It is, therefore, advisable to also study the chronic and multigenerational effects of sublethal concentrations of toxicants in an environmentally relevant context as advocated by the European Commission4,5 and the USEPA (United States Environmental Protection Agency)6,7. Especially in vertebrate research, the costs in terms of labor, money, and time are high when performing chronic and multigenerational exposure studies because of the relatively long lifespan of vertebrates compared to invertebrate model organisms. Therefore, it is advisable to choose the most appropriate fish model organism, depending on the research question. Furthermore, a wide array of vertebrate species should be available in order to test the generality of responses across species to be able to adapt regulations based on the most sensitive species. For now, there is a need to develop new, efficient protocols with vertebrate model species characterized by short life-cycles to lower the costs of performing chronic and multigenerational exposures on vertebrates7,8.
The turquoise killifish Nothobranchius furzeri is an interesting fish model to use in such long-term exposure experiments because of its short maturation time and life-cycle (generation time less than 4 weeks9). This means that ecologically relevant endpoints such as maturation time and fecundity can be studied within a short time frame compared to other fish models7. Furthermore, these fish produce drought-resistant, dormant eggs that remain viable for several years when stored under standard conditions, thereby eliminating the need for a continuous culture9. In ecotoxicological studies, this also implies that replicate fish can all be hatched at the exact same moment, resulting in time synchrony for all animals, even among batches of eggs produced at different times. We advise using the laboratory GRZ strain to perform exposure experiments. This strain performs well under laboratory conditions, is homozygous (except for sex chromosomes) and the genome is well characterized10,11.
In ecotoxicological studies, it is important to select the appropriate range of test concentrations. Several complementary methods can be used to this end. The nominal concentration range can be based on the sensitivity of a related species, such as Nothobranchius guentheri12. Alternatively, the range can be based on the sensitivity of standard fish models, such as zebrafish (Danio rerio)2 that have a comparable sensitivity to most toxicants (Philippe et al. (in review)). In combination, with both of these options, a range finding experiment should be conducted to select the nominal concentration range. For acute testing, researchers should aim for concentration treatments with 100% mortality, intermediate mortality and 0% mortality after 24 h of exposure to the toxicant. For chronic testing, it is advisable to run the range finding experiment for two weeks to verify if larval mortality in the condition with the highest test concentrations does not exceed 10% during this reference period.
The protocol can serve as a baseline to perform acute and chronic exposure to waterborne pollutants on N. furzeri, examining potential effects of stressors both at the individual and cellular level. It can also be used to perform multi-stressor research to accommodate a higher ecological relevance, mixing different toxic compounds or studying interactive effects between pollution and other natural stressors (e.g. predation) or anthropogenic stressors (e.g. warming due to climate change).

<table>
	<tbody>
		<tr>
			<td>purified water Type 1 (milli Q)</td>
			<td>Millipore</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sea Salt</td>
			<td>Instant Ocean</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2L plastic tank</td>
			<td>SAVIC</td>
			<td></td>
			<td>Always separate material for control and toxicity treatments</td>
		</tr>
		<tr>
			<td>1L plastic tank (spawning)</td>
			<td>Avamoplast</td>
			<td></td>
			<td>Always separate material for control and toxicity treatments</td>
		</tr>
		<tr>
			<td>nets</td>
			<td>Aqua bilzen</td>
			<td></td>
			<td>Always separate material for control and toxicity treatments</td>
		</tr>
		<tr>
			<td>2L glass jars</td>
			<td>Sepac-Flacover</td>
			<td></td>
			<td>Always separate material for control and toxicity treatments</td>
		</tr>
		<tr>
			<td>0,5L glass jars</td>
			<td>Sepac-Flacover</td>
			<td></td>
			<td>Always separate material for control and toxicity treatments</td>
		</tr>
		<tr>
			<td>Artemia eggs</td>
			<td>Ocean Nutrition</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>chironomus</td>
			<td>Ocean Nutrition</td>
			<td></td>
			<td>frozen</td>
		</tr>
		<tr>
			<td>tricaine</td>
			<td>Sigma aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>petri dishes</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Parafilm</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>pipettes</td>
			<td>MLS</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>tweezers</td>
			<td>FST</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>500 &#181;m mesh sieve</td>
			<td>/</td>
			<td></td>
			<td>self-made</td>
		</tr>
		<tr>
			<td>microcentrifuge tube (2ml)</td>
			<td>BRAND</td>
			<td></td>
			<td>To store fish in freezer</td>
		</tr>
		<tr>
			<td>glass vials</td>
			<td>Sigma aldrich</td>
			<td></td>
			<td>For water analysis</td>
		</tr>
		<tr>
			<td>weighing boat</td>
			<td>MLS</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Jiffy 7c pellets</td>
			<td>Jiffy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>water bath</td>
			<td>Gilac</td>
			<td></td>
			<td>for Ctmax</td>
		</tr>
		<tr>
			<td>liquid nitrogen</td>
			<td>Air liquide</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>digital thermometer</td>
			<td>Testo AG</td>
			<td>testo 926</td>
			<td></td>
		</tr>
		<tr>
			<td>HETO therm heater</td>
			<td>Anker Schmitt</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>calibrated balance</td>
			<td>Mettler-Toledo AG</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>camera</td>
			<td>/</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>platform for camera</td>
			<td>/</td>
			<td></td>
			<td>self-made</td>
		</tr>
		<tr>
			<td>Multiparameter kit</td>
			<td>HACH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Freezer (-80&#176;C)</td>
			<td>Panasonic Ultra low temperature freezer</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Fysio</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>homogenisation buffer</td>
			<td>VWR</td>
			<td></td>
			<td>0.1&#160;M TRIS&#8211;HCl, pH 8.5, 15&#160;% polyvinyl pyrrolidone, 153&#160;&#181;M MgSO4&#160;and 0.2&#160;% Triton X-100</td>
		</tr>
		<tr>
			<td>chloroform:methanol</td>
			<td>Sigma Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>glyceryl tripalmitate</td>
			<td>Sigma Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>amyloglucosidase</td>
			<td>Sigma Aldrich</td>
			<td>A7420</td>
			<td></td>
		</tr>
		<tr>
			<td>glucose assay reagent</td>
			<td>Sigma Aldrich</td>
			<td>G3293</td>
			<td></td>
		</tr>
		<tr>
			<td>Biorad protein dye</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>96-well microtiter plate</td>
			<td>Greiner Bio-one</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>384 microtiter plates</td>
			<td>Greiner Bio-one</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2 ml glass tubes</td>
			<td>Fiers</td>
			<td></td>
			<td>For fat analysis</td>
		</tr>
		<tr>
			<td>2,5ml eppendorf tubes</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>homogeniser</td>
			<td>Ultra-turrax TP 18/10</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>photospectrometer</td>
			<td>Infinite M200 TECAN</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>heater for glass tubes</td>
			<td>Hach COD REACTOR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>centrifuge</td>
			<td>Eppendorf Centrifuge 5415 R</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Bumako</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

protocol for acute and chronic ecotoxicity testing of the turquoise killifish nothobranchius furzeri

The killifish Nothobranchius furzeri is an emerging model organism in the field of ecotoxicology and its applicability in acute and chronic ecotoxicity testing has been demonstrated. Overall, the sensitivity of the species to toxic compounds is in the range with, or higher than, that of other model species.
This work describes protocols for acute, chronic, and multigenerational bioassays of single and combined stressor effects on N. furzeri. Due to its short maturation time and life-cycle, this vertebrate model allows the study of endpoints such as maturation time and fecundity within four months. Transgenerational full life-cycle exposure trials can be performed in as little as 8 months. Since this species produces eggs that are drought-resistant and remain viable for years, the on-site culture of the species is not needed but individuals can be recruited when required. The protocols are designed to measure life-history traits (mortality, growth, fecundity, weight) and critical thermal maximum.

The results of the acute exposure of N. furzeri to different concentrations of copper, calculated as in 2.5.2, show cleardose-response relationships (Figure 1). There is an increase in mortality with increasing toxicant concentration. LC50 values decrease over time, meaning that with decreasing concentrations, more time passes before 50% of the replicates die. For detailed results on the acute and chronic exposure of N. furzeri to...

Watch this Scientific Journal Video about Protocol for Acute and Chronic Ecotoxicity Testing of the Turquoise Killifish Nothobranchius furzeri at JoVE.com

Protocol for Acute and Chronic Ecotoxicity Testing of the Turquoise Killifish Nothobranchius furzeri

In this work, we describe an acute, chronic and multigenerational bioassay to study the effects of single and combined stressors on the Turquoise killifish Nothobranchius furzeri. This protocol is designed to study life-history traits (mortality, growth, fecundity, weight) and critical thermal maximum.

Protocol for Acute and Chronic Ecotoxicity Testing of the Turquoise Killifish Nothobranchius furzeri

The killifish Nothobranchius furzeri is an emerging model organism in the field of ecotoxicology and its applicability in acute and chronic ecotoxicity ...

The overall goal of this experiment is to study the effects of toxicants on the turquoise killifish Nothobranchius furzeri. This method can help answer key questions in the field of ecotoxicology, such as the long term effects of stressors on important life-history traits, being maturation time, growth, or fecundity. The main advantage of this experiment is that we use a vertebrate with a very fast life-cycle, resulting in time and cost-efficient experiments.These killifish are ideal models to study the impact of long-term and multi generational effects of stressors. Ultimately, they will contribute towards better understanding of environmental impact of toxicants. Though this method can provide new insights into the combined effects of toxicants and temperature, it can also be applied to other stressors such as UV radiation, food deprivation and PH alterations.Killifish are challenging to work with, because they're a new model system in ecotoxicology, and because they're sensitivity to a lot of pollutants is still unknown. We developed the idea for this experimental method when we first learned about the exceptional short life span of killifish, and their capacity to produce dormant eggs that can be stored for years on the shelf. Visual demonstration of this method is critical as the type of the experiment, as well as handling of the individuals, can alter the results.To begin, select gona ray zoo, or GRZ eggs, in the D3 stage, which are recognizable by the presence of golden eyes. And use a soft pair of tweezers to gently transfer them to a plastic two-liter tank. Add one centimeter of the hatching medium at 12 degrees celsius, and let the water temperature gradually adjust to room temperature.After 24 hours, feed the hatchlings a concentrated dose of freshly hatched artemia nauplii, and increase the water depth to five centimeters by adding fish medium. 48 hours post-hatching, transfer healthy, buoyant larvae to individual containers with exposure medium, and toxicant concentrations as described in the text protocol. Each morning and evening, check fish for mortality, stress, and sickness, and calculate LC50 values according to the text protocol.Perform a chronic exposure trial by filling individual containers with the correct exposure medium, and add an air tube to aerate the jar. Transfer fish into the jars for the remainder of the experiment. From two to 23 days post-hatching or DPH, feed the fish artemia nauplii twice per day ad libitum.Then, after supplementing with chopped chironomus larvae until 37 DPH, use frozen chironomus larvae to feed the fish ad libitum twice per day, every day, moving forward. To determine growth, measure the body size on a weekly basis, by transferring fish to a Petri dish filled with medium from the reservoir. Take four to five size-calibrated dorsal view pictures of the fish at a fixed height.And use a spatial measuring program to digitally analyze them. From 15 DPH onwards, visually inspect the male fish for coloration, to determine maturation. Check the fins for the first signs of nuptial coloration, and use the day at which fist coloration was visible as a proxy for male maturation time.From 30 DPH onwards, check fecundity by setting up a one-liter spawning tank for mature male and female couple within each treatment, using exposure medium from the male's aquarium, and supplement it with spawning substrate. Transfer both the male and female into the spawning tank. And while minimizing human activity or disturbance around the spawning containers, allow them to spawn for two hours.Afterwards, without unnecessary mixing of the water, which would whirl up the eggs in the spawning substrate, gently transfer fish back to their original housing containers. Filter out the eggs by pouring the spawning substrate over a 500 micrometer mesh. Count the eggs and use a pipette, to transfer them to damp peat moss in Petri dishes.Remove dead eggs daily. After a week, use sealing film to seal the Petri dish. And store it in a temperature-controlled incubator at 28 degrees celsius, with a 14 to 10 light to dark cycle, for immediate development to the D3 phase.For long-term conservation, store the eggs in constant darkness at 17 degrees celsius, upon which eggs enter the dormant phase, and remain viable for multiple years. To recruit fish from the dormant eggs, transfer the eggs to 28 degrees celsius, and a 14 to 10 light to dark cycle, for approximately three weeks, to allow them to develop to the D3 phase. To measure the critical thermal maximum, or CT max of adult fish, begin with a continuously circulating water bath, heated at a constant rate of 0.33 degrees celsius per minute.Add several one-liter aquaria, for each individual fish. Start the trail by adding the fish to the aquarium, when the water has reached the experimental rearing temperature of the fish. Use a digital thermometer to monitor the temperature in the one-liter aquaria of the CT max bath, every five minutes.When the fish fails to maintain a dorsal ventral upright position, or starts twitching heavily, measure the temperature in the one-liter aquarium, which is the critical maximal temperature. Then, transfer the fish back to its experimental housing for recovery. As shown in this graph, acute exposure of enfurzeri to different concentrations of copper, caused an increase in mortality with increasing toxicant concentration.LC50 values decrease over time, meaning that with decreasing concentrations, more time passes before 50%of the replicates die. In chronic exposure assay, using water-born copper, fish are shorter in length, as measured after three weeks when raised at the highest concentration tested. In this experiment using water borne chlorpyrifos or CPH, when raised at 28 degrees celsius, fish produced less eggs when exposed to the highest CPF concentration, however, at 30 degrees celsius, control fish produced more eggs than fish exposed to either concentration of CPF, indicating that the combination of CPF and an increase in temperature affected fecundity more than each stressor separately.Reported here is the mean age at which the first signs of coloration appeared in enfurzeri males, exposed to CPF at 28 and 30 degrees celsius. After exposure to four micrograms per liter of CPF, the male fish took 18%longer to mature than control fish. Measuring the CT max of fish reared at either 24 or 28 degrees celsius, and exposure to the pollutant 3, 4-DCA revealed that erratic swimming, increased opercular movement, and loss of ability to remain in dorsoventrally upright position, occurred at a lower temperature when fish were raised at 24 degrees celsius.Once mastered, this protocol, including the effects on fecundity, can be measured in two months. To measure the effects on the whole reproductive period or even a following generation, the protocol can be extended, but can still be performed in six months.

protocol-for-acute-chronic-ecotoxicity-testing-turquoise-killifish

Research

JoVE Journal

Environment

Optimized Negative Staining: a High-throughput Protocol for Examining Small and Asymmetric Protein Structure by Electron Microscopy

Structural determination of proteins is rather challenging for proteins with molecular masses between 40 - 200 kDa. Considering that more than half of natural proteins have a molecular mass between 40 - 200 kDa1,2, a robust and high-throughput method with a nanometer resolution capability is needed. Negative staining (NS) electron microscopy (EM) is an easy, rapid, and qualitative approach which has frequently been used in research laboratories to examine protein structure and protein-protein interactions. Unfortunately, conventional NS protocols often generate structural artifacts on proteins, especially with lipoproteins that usually form presenting rouleaux artifacts. By using images of lipoproteins from cryo-electron microscopy (cryo-EM) as a standard, the key parameters in NS specimen preparation conditions were recently screened and reported as the optimized NS protocol (OpNS), a modified conventional NS protocol 3 . Artifacts like rouleaux can be greatly limited by OpNS, additionally providing high contrast along with reasonably high&#8208;resolution (near 1 nm) images of small and asymmetric proteins. These high-resolution and high contrast images are even favorable for an individual protein (a single object, no average) 3D reconstruction, such as a 160 kDa antibody, through the method of electron tomography4,5. Moreover, OpNS can be a high&#8208;throughput tool to examine hundreds of samples of small proteins. For example, the previously published mechanism of 53 kDa cholesteryl ester transfer protein (CETP) involved the screening and imaging of hundreds of samples 6. Considering cryo-EM rarely successfully images proteins less than 200 kDa has yet to publish any study involving screening over one hundred sample conditions, it is fair to call OpNS a high-throughput method for studying small proteins. Hopefully the OpNS protocol presented here can be a useful tool to push the boundaries of EM and accelerate EM studies into small protein structure, dynamics and mechanisms.

More than half of proteins are small proteins (molecular mass &#60;200 kDa) that are challenging for both electron microscope imaging and three-dimensional reconstructions. Optimized negative staining is a robust and high-throughput protocol to obtain high contrast and relatively high resolution (~1 nm) images of small asymmetric proteins or complexes under different physiological conditions.

Structural determination of proteins is rather challenging for proteins with molecular masses between 40 - 200 kDa. Considering that more than half of ...

LC-MS Analysis of Human Platelets as a Platform for Studying Mitochondrial Metabolism

Perturbed mitochondrial metabolism has received renewed interest as playing a causative role in a range of diseases. Probing alterations to metabolic pathways requires a model in which external factors can be well controlled, allowing for reproducible and meaningful results. Many studies employ transformed cellular models for these purposes; however, metabolic reprogramming that occurs in many cancer cell lines may introduce confounding variables. For this reason primary cells are desirable, though attaining adequate biomass for metabolic studies can be challenging. Here we show that human platelets can be utilized as a platform to carry out metabolic studies in combination with liquid chromatography-tandem mass spectrometry analysis. This approach is amenable to relative quantification and isotopic labeling to probe the activity of specific metabolic pathways. Availability of platelets from individual donors or from blood banks makes this model system applicable to clinical studies and feasible to scale up. Here we utilize isolated platelets to confirm previously identified compensatory metabolic shifts in response to the complex I inhibitor rotenone. More specifically, a decrease in glycolysis is accompanied by an increase in fatty acid oxidation to maintain acetyl-CoA levels. Our results show that platelets can be used as an easily accessible and medically relevant model to probe the effects of xenobiotics on cellular metabolism.

Here we show isolated human platelets can be used as an accessible ex vivo model to study metabolic adaptations in response to the complex I inhibitor rotenone. This approach employs isotopic tracing and relative quantification by liquid chromatography-mass spectrometry and can be applied to a variety of study designs.

Perturbed mitochondrial metabolism has received renewed interest as playing a causative role in a range of diseases. Probing alterations to metabolic ...

A Protocol for Collecting and Constructing Soil Core Lysimeters

Leaching of nutrients from land applied fertilizers and manure used in agriculture can lead to accelerated eutrophication of surface water. Because the landscape has complex and varied soil morphology, an accompanying disparity in flow paths for leachate through the soil macropore and matrix structure is present. The rate of flow through these paths is further affected by antecedent soil moisture. Lysimeters are used to quantify flow rate, volume of water and concentration of nutrients leaching downward through soils. While many lysimeter designs exist, accurately determining the volume of water and mass balance of nutrients is best accomplished with bounded lysimeters that leave the natural soil structure intact. 
Here we present a detailed method for the extraction and construction of soil core lysimeters equipped with soil moisture sensors at 5 cm and 25 cm depths. Lysimeters from four different Coastal Plain soils (Bojac, Evesboro, Quindocqua and Sassafras) were collected on the Delmarva Peninsula and moved to an indoor climate controlled facility. Soils were irrigated once weekly with the equivalent of 2 cm of rainfall to draw down soil nitrate-N concentrations. At the end of the draw down period, poultry litter was applied (162 kg TN ha-1) and leaching was resumed for an additional five weeks. Total recovery of applied irrigation water varied from 71% to 85%. Nitrate-N concentration varied over the course of the study from an average of 27.1 mg L-1 before litter application to 40.3 mg L-1 following litter application. While greatest flux of nutrients was measured in soils dominated by coarse sand (Sassafras) the greatest immediate flux occurred from the finest textured soil with pronounced macropore development (Quindocqua).

A detailed method for extraction and assembly of intact soil core lysimeters and their use for study of leachate and associated loss of nutrients from surface applied poultry litter is demonstrated.

Leaching of nutrients from land applied fertilizers and manure used in agriculture can lead to accelerated eutrophication of surface water. Because the ...

Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample

Methane hydrates (MHs) are present in large amounts in the ocean floor and permafrost regions. Methane and hydrogen hydrates are being studied as future energy resources and energy storage media. To develop a method for gas production from natural MH-bearing sediments and hydrate-based technologies, it is imperative to understand the thermal properties of gas hydrates.
The thermal properties' measurements of samples comprising sand, water, methane, and MH are difficult because the melting heat of MH may affect the measurements. To solve this problem, we performed thermal properties' measurements at supercooled conditions during MH formation. The measurement protocol, calculation method of the saturation change, and tips for thermal constants' analysis of the sample using transient plane source techniques are described here.
The effect of the formation heat of MH on measurement is very small because the gas hydrate formation rate is very slow. This measurement method can be applied to the thermal properties of the gas hydrate-water-guest gas system, which contains hydrogen, CO2, and ozone hydrates, because the characteristic low formation rate of gas hydrate is not unique to MH. The key point of this method is the low rate of phase transition of the target material. Hence, this method may be applied to other materials having low phase-transition rates.

We present a protocol for measuring the thermal properties of synthetic hydrate-bearing sediment samples comprising sand, water, methane, and methane hydrate.

Methane hydrates (MHs) are present in large amounts in the ocean floor and permafrost regions. Methane and hydrogen hydrates are being studied as future ...

Protocol for Microplastics Sampling on the Sea Surface and Sample Analysis

Microplastic pollution in the marine environment is a scientific topic that has received increasing attention over the last decade. The majority of scientific publications address microplastic pollution of the sea surface. The protocol below describes the methodology for sampling, sample preparation, separation and chemical identification of microplastic particles. A manta net fixed on an &#187;A frame&#171; attached to the side of the vessel was used for sampling. Microplastic particles caught in the cod end of the net were separated from samples by visual identification and use of stereomicroscopes. Particles were analyzed for their size using an image analysis program and for their chemical structure using ATR-FTIR and micro FTIR spectroscopy. The described protocol is in line with recommendations for microplastics monitoring published by the Marine Strategy Framework Directive (MSFD) Technical Subgroup on Marine Litter. This written protocol with video guide will support the work of researchers that deal with microplastics monitoring all over the world.

The protocol below describes the methodology for: microplastics sampling on the sea surface, separation of microplastic and chemical identification of particles. This protocol is in line with the recommendations for microplastics monitoring published by the MSFD Technical Subgroup on Marine Litter.

Microplastic pollution in the marine environment is a scientific topic that has received increasing attention over the last decade. The majority of ...

Ecotoxicological Method with Marine Bacteria Vibrio anguillarum to Evaluate the Acute Toxicity of Environmental Contaminants

Bacteria are an important component of the ecosystem, and microbial community alterations can have a significant effect on biogeochemical cycling and food webs. Toxicity testing based on microorganisms are widely used because they are relatively quick, reproducible, cheap, and are not associated with ethical issues. Here, we describe an ecotoxicological method to evaluate the biological response of the marine bacterium Vibrio anguillarum. This method assesses the acute toxicity of chemical compounds, including new contaminants such as nanoparticles, as well as environmental samples. The endpoint is the reduction of bacterial culturability (i.e., the capability to replicate and form colonies) due to exposure to a toxicant. This reduction can be generally referred to as mortality. The test allows for the determination of the LC50, the concentration that causes a 50% decrease of bacteria actively replicating and forming colonies, after a 6 h exposure. The culturable bacteria are counted in terms of colony forming units (CFU), and the &#34;mortality&#34; is evaluated and compared to the control. In this work, the toxicity of copper sulphate (CuSO4) was evaluated. A clear dose-response relationship was observed, with a mean LC50 of 1.13 mg/L, after three independent tests. This protocol, compared to existing methods with microorganisms, is applicable in a wider range of salinity and has no limitations for colored/turbid samples. It uses saline solution as the exposure medium, avoiding any possible interferences of growth medium with the investigated contaminants. The LC50 calculation facilitates comparisons with other bioassays commonly applied to ecotoxicological assessments of the marine environment.

Ecotoxicological Method with Marine Bacteria Vibrio anguillarum to Evaluate the Acute Toxicity of Environmental Contaminants

This work describes a new protocol to assess the ecotoxicity of pollutants, including emerging contaminants such as nanomaterials, using the marine bacterium Vibrio anguillarum. This method allows for the determination of the LC50, or mortality, the concentration that causes a 50% decrease in bacteria culturability, after a 6 h exposure.

Bacteria are an important component of the ecosystem, and microbial community alterations can have a significant effect on biogeochemical cycling and food ...

Protocol for Assessing the Relative Effects of Environment and Genetics on Antler and Body Growth for a Long-lived Cervid

Cervid phenotype can be placed into one of two categories: efficiency, which promotes survival over extravagant morphometric growth, and luxury, which promotes growth of large weaponry and body size. Populations of the same species display each phenotype depending on environmental conditions. Although antler and body size of male white-tailed deer (Odocoileus virginianus) varies by physiographic region in Mississippi, USA and is strongly correlated with regional variation in nutritional quality, the effects of population-level genetics from native stocks and previous re-stocking efforts cannot be disregarded. This protocol describes how we designed a controlled study, where other factors that influence phenotype, such as age and nutrition, are controlled. We brought wild-caught pregnant females and six-month-old fawns from three distinct physiographic regions in Mississippi, USA to the Mississippi State University Rusty Dawkins Memorial Deer Unit. Deer from the same region were bred to produce a second generation of offspring, allowing us to assess generational responses and maternal effects. All deer ate the same high-quality (20% crude protein deer pellet) diet ad libitum. We uniquely marked each neonate and recorded body mass, hind foot, and total body length. Each subsequent fall, we sedated individuals via remote injection and sampled the same morphometrics plus antlers of adults. We found that all morphometrics increased in size from first to second generation, with full compensation of antler size (regional variation no longer present) and partial compensation of body mass (some evidence of regional variation) evident in the second generation. Second generation males that originated from our poorest quality soil region displayed about a 40% increase in antler size and about a 25% increase in body mass when compared to their wild harvested counterparts. Our results suggest phenotypic variation of wild male white-tailed deer in Mississippi are more related to differences in nutritional quality than population-level genetics.

Phenotypic differences among cervid populations may be related to population-level genetics or nutrition; discerning which is difficult in the wild. This protocol describes how we designed a controlled study where nutritional variation was eliminated. We found that phenotypic variation of male white-tailed deer was more limited by nutrition than genetics.

Cervid phenotype can be placed into one of two categories: efficiency, which promotes survival over extravagant morphometric growth, and luxury, which ...

Dispersion of Nanomaterials in Aqueous Media: Towards Protocol Optimization

The sonication process is commonly used for de-agglomerating and dispersing nanomaterials in aqueous based media, necessary to improve homogeneity and stability of the suspension. In this study, a systematic step-wise approach is carried out to identify optimal sonication conditions in order to achieve a stable dispersion. This approach has been adopted and shown to be suitable for several nanomaterials (cerium oxide, zinc oxide, and carbon nanotubes) dispersed in deionized (DI) water. However, with any change in either the nanomaterial type or dispersing medium, there needs to be optimization of the basic protocol by adjusting various factors such as sonication time, power, and sonicator type as well as temperature rise during the process. The approach records the dispersion process in detail. This is necessary to identify the time points as well as other above-mentioned conditions during the sonication process in which there may be undesirable changes, such as damage to the particle surface thus affecting surface properties. Our goal is to offer a harmonized approach that can control the quality of the final, produced dispersion. Such a guideline is instrumental in ensuring dispersion quality repeatability in the nanoscience community, particularly in the field of nanotoxicology.

Here, we present a step-wise protocol for the dispersion of nanomaterials in aqueous media with real-time characterization to identify the optimal sonication conditions, intensity, and duration for improved stability and uniformity of nanoparticle dispersions without impacting the sample integrity.

The sonication process is commonly used for de-agglomerating and dispersing nanomaterials in aqueous based media, necessary to improve homogeneity and ...

On the Preparation and Testing of Fuel Cell Catalysts Using the Thin Film Rotating Disk Electrode Method

We present a step-by-step tutorial to prepare proton exchange membrane fuel cell (PEMFC) catalysts, consisting of Pt nanoparticles (NPs) supported on a high surface area carbon, and to test their performance in thin film rotating disk electrode (TF-RDE) measurements. The TF-RDE methodology is widely used for catalyst screening; nevertheless, the measured performance sometimes considerably differs among research groups. These uncertainties impede the advancement of new catalyst materials and, consequently, several authors discussed possible best practice methods and the importance of benchmarking.
The visual tutorial highlights possible pitfalls in the TF-RDE testing of Pt/C catalysts. A synthesis and testing protocol to assess standard Pt/C catalysts is introduced that can be used together with polycrystalline Pt disks as benchmark catalysts. In particular, this study highlights how the properties of the catalyst film on the glassy carbon (GC) electrode influence the measured performance in TF-RDE testing. To obtain thin, homogeneous catalyst films, not only the catalyst preparation, but also the ink deposition and drying procedures are essential. It is demonstrated that an adjustment of the ink&#39;s pH might be necessary, and how simple control measurements can be used to check film quality. Once reproducible TF-RDE measurements are obtained, determining the Pt loading on the catalyst support (expressed as Pt wt%) and the electrochemical surface area is necessary to normalize the determined reaction rates to either surface area or Pt mass. For the surface area determination, so-called CO stripping, or the determination of the hydrogen underpotential deposition (Hupd) charge, are standard. For the determination of the Pt loading, a straightforward and cheap procedure using digestion in aqua regia with subsequent conversion of Pt(IV) to Pt(II) and UV-vis measurements is introduced.

Preparing and testing Pt/C fuel cell catalysts is subject to continuous discussion in the scientific community with respect to reproducibility and best practice. With the presented work, we intend to present a step-by-step tutorial to make and test Pt/C catalysts, which can serve as benchmark for novel catalyst systems.

We present a step-by-step tutorial to prepare proton exchange membrane fuel cell (PEMFC) catalysts, consisting of Pt nanoparticles (NPs) supported on a ...

The Hawaii Protocol for Scientific Monitoring of Coffee Berry Borer: a Model for Coffee Agroecosystems Worldwide

Coffee berry borer (CBB) is the most devastating insect pest for coffee crops worldwide. We developed a scientific monitoring protocol that is aimed at capturing and quantifying the dynamics and impact of this invasive insect pest as well as the development of its host plant across a heterogeneous landscape. The cornerstone of this comprehensive monitoring system is timely georeferenced data collection on CBB movement, coffee berry infestation, mortality by the fungus Beauveria bassiana, and coffee plant phenology via a mobile electronic data recording application. This electronic data collection system allows field records to be georeferenced through built-in global positioning systems, and is backed by a network of weather stations and records of farm management practices. Comprehensive monitoring of CBB and host plant dynamics is an essential part of an area-wide project in Hawaii to aggregate landscape-level data for research to improve management practices. Coffee agroecosystems in other parts of the world that experience highly variable environmental and socioeconomic factors will also benefit from implementing this protocol, in that it will drive the development of customized integrated pest management (IPM) to manage CBB populations.

Comprehensive monitoring of coffee berry borer and host plant dynamics is essential for aggregating landscape-level data to improve management of this invasive pest. Here, we present a protocol for scientific monitoring of coffee berry borer movement, infestation, mortality, coffee plant phenology, weather, and farm management via a mobile electronic data recording application.

Coffee berry borer (CBB) is the most devastating insect pest for coffee crops worldwide. We developed a scientific monitoring protocol that is aimed at ...