This work was funded by the National Natural Science Foundation of China (21777145, 22076170), and the Program for Changjiang Scholars and Innovative Research Team in University (IRT_17R97).

Adult zebrafish are originated from the China Zebrafish Resource Center (Wuhan, China). The experiments were conducted in compliance with the national guide &#34;Laboratory Animal Guideline for Ethical Review of Animal Welfare (GB/T35892-2018).
1. Embryo collection
<ol>
	<li>Maintain fish in 20 L glass tanks with recirculating charcoal-filtered tap water system (pH 7.0 &#177; 0.2) at a constant temperature (28 &#177; 0.5 &#176;C) on a photoperiod of 14:10 h light: dark.</li>
	<li>Feed fish twice daily with Artemia nauplii. It is recommended that the food is given at max. 3% fish weight per day and should be eaten within 5 min every time14.</li>
	<li>Transfer well-developed adult zebrafish (with body length of 3-4 cm) into the spawning tank at a ratio of one male to two females the night before the breeding. 
	NOTE: The following morning, the fish start to spawn after the onset of the light cycle.</li>
	<li>Collect eggs using a Pasteur pipette. Rinse with 10% Hank&#39;s solution several times, and then check for fertilization using a microscope. Fertilized eggs undergo the cleavage period after approximately 2 h post fertilization (hpf) and can be clearly identified15.</li>
	<li>Incubate the fertilized embryos in a 500 mL beaker containing 200 mL of 10% Hank&#39;s solution with 1% methylene blue for disinfection at 28 &#176;C. Do not exceed a loading rate of 1 embryo/2 mL solution. 
	NOTE: 10% Hank&#39;s solution is made up of 137 mM NaCl, 5.4 mM KCl, 0.25 mM Na2HPO4, 0.44 mM KH2PO4, 1.3 mM CaCl2, 1.0 mM MgSO4 and 4.2 mM NaHCO3.</li>
</ol>
2. Preparation of microplastic suspensions
<ol>
	<li>Sonicate the stock solution of green fluorescently labeled polystyrene beads (10 mg/mL) with nominal diameter of 500 nm (excitation/emission: 460/500 nm) for 10 minutes.</li>
	<li>Dilute the stock solution with 10% Hank&#39;s solution to produce the desired exposure solutions (0.1, 1, and 10 mg/L).</li>
	<li>Always prepare the exposure solutions of microplastics before exposure. 
	&#8203;NOTE: Caution should be taken when assessing the toxic effects of microplastics, because the presence of preservatives, such as sodium azide, in the commercial particle formulations, can be toxic to different organisms 16. Therefore, these additives should be removed or accounted for in the controls before conducting toxicity experiment.</li>
</ol>
3. Microplastic exposure
<ol>
	<li>Randomly select 6 newly fertilized embryos (4 hpf), and then transfer into each well of 6-well plate containing 5 mL of microplastic solutions with different concentrations. Include the control groups containing 10% Hank&#39;s solution.
	<ol>
		<li>Use triplicate wells (with a total of 18 embryos) for each treatment.</li>
	</ol>
	</li>
	<li>Incubate the embryos under the same light: dark cycle and temperature as adults (see 1.2) and observe every 12 hours. Remove the dead immediately.</li>
	<li>Renew the microplastic solutions 90% every 24 h. During the exposure period, the fish are not fed. 
	NOTE: Generally, the hatching of embryo begins at 48 hpf and completes at about 72 hpf.</li>
</ol>
4. Assessment of microplastic distribution
<ol>
	<li>At 24, 48, 72, 96, and 120 h post fertilization, randomly select the embryos/larvae (one from each of the three replicates) and rinse with 10% Hank&#39;s solution.</li>
	<li>Transfer the larvae into a Petri dish and expose to 0.016% tricaine for anesthesia.
	<ol>
		<li>Prepare the stock solution of tricaine: 4 mg of tricaine powder is dissolved in 100 mL of double distilled water, and adjust the pH to 7.0 with Tris-HCl (pH 9.0). Store the stock solution in the freezer.</li>
		<li>Prepare the working solution. Dilute the stock solution to the desired concentration (0.016%) with 10% Hank&#39;s solution at room temperature14.</li>
	</ol>
	</li>
	<li>Arrange the embryos/larvae and prepare for observation.</li>
	<li>Observe the fish with a fluorescence microscope and image with imaging software.</li>
	<li>Quantify the fluorescence intensity in fish with ImageJ.</li>
</ol>

<ol>
	<li>SAPEA (Science Advice for Policy by European Academies). <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> A Scientific Perspective on Microplastics in Nature and Society. , (2019).</li><li>Plastics Europe. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Plastics-the facts 2019. , (2019).</li><li>Andrady, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microplastics+in+the+marine+environment.">Microplastics in the marine environment.</a> Marine Pollution Bulletin. 62, 1596-1605 (2011).</li><li>Arthur, C., Baker, J., Bamford, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proceedings+of+the+International+Research+Workshop+on+the+Occurrence,+Effects+and+Fate+of+Microplastic+Marine+Debris.">Proceedings of the International Research Workshop on the Occurrence, Effects and Fate of Microplastic Marine Debris.</a> National Oceanic and Atmospheric Administration Technical Memorandum. , (2009).</li><li>Ivleva, N. P., Wiesheu, A. C., Niessner, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microplastic+in+aquatic+ecosystems.">Microplastic in aquatic ecosystems.</a> Angewandte Chemie International Edition. 56, 1720-1739 (2017).</li><li>Lu, T., 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=Pollutant+toxicology+with+respect+to+microalgae+and+cyanobacteria.">Pollutant toxicology with respect to microalgae and cyanobacteria.</a> Journal of Environmental Sciences. 99, 175-186 (2021).</li><li>Huang, J. N., 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=Exposure+to+microplastics+impairs+digestive+performance,+stimulates+immune+response+and+induces+microbiota+dysbiosis+in+the+gut+of+juvenile+guppy+(Poecilia+reticulata).">Exposure to microplastics impairs digestive performance, stimulates immune response and induces microbiota dysbiosis in the gut of juvenile guppy (Poecilia reticulata).</a> Science of the Total Environment. 733, 138929 (2020).</li><li>Pr&#252;st, M., Meijer, J., Westerink, R. H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+plastic+brain:+neurotoxicity+of+micro-+and+nanoplastics.">The plastic brain: neurotoxicity of micro- and nanoplastics.</a> Particle and Fibre Toxicology. 17, 24 (2020).</li><li>Jakubowska, 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=Effects+of+chronic+exposure+to+microplastics+of+different+polymer+types+on+early+life+stages+of+sea+trout+Salmo+trutta.">Effects of chronic exposure to microplastics of different polymer types on early life stages of sea trout Salmo trutta.</a> Science of the Total Environment. 740, 139922 (2020).</li><li>Qiang, L., Cheng, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exposure+to+polystyrene+microplastics+impairs+gonads+of+zebrafish+(Danio+rerio).">Exposure to polystyrene microplastics impairs gonads of zebrafish (Danio rerio).</a> Chemosphere. 263, 128161 (2021).</li><li>Hamed, M., Soliman, H. A. M., Osman, A. G. M., Sayed, A. E. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antioxidants+and+molecular+damage+in+Nile+Tilapia+(Oreochromis+niloticus)+after+exposure+to+microplastics.">Antioxidants and molecular damage in Nile Tilapia (Oreochromis niloticus) after exposure to microplastics.</a> Environmental Science and Pollution Research. 27, 14581-14588 (2020).</li><li>Burns, E. E., Boxall, A. B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microplastics+in+the+aquatic+environment:+Evidence+for+or+against+adverse+impacts+and+major+knowledge+gaps.">Microplastics in the aquatic environment: Evidence for or against adverse impacts and major knowledge gaps.</a> Environmental Toxicology and Chemistry. 37, 2776-2796 (2018).</li><li>Ma, H., Pu, S., Liu, S., Bai, Y., Mandal, S., Xing, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microplastics+in+aquatic+environments:+Toxicity+to+trigger+ecological+consequences.">Microplastics in aquatic environments: Toxicity to trigger ecological consequences.</a> Environmental Pollution. 261, 114089 (2020).</li><li>Westerfield, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Zebrafish Book: A Guide for the Laboratory Use of Zebrafish (Danio reio). 4th ed. , (2000).</li><li>Kimmel, C. B., Ballard, W. W., Kimmel, S. R., Ullmann, B., Schilling, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stages+of+embryonic+development+of+the+zebrafish.">Stages of embryonic development of the zebrafish.</a> Developmental Dynamics. 203, 253-310 (1995).</li><li>Pikuda, O., Xu, E. G., Berk, D., Tufenkji, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxicity+assessments+of+micro-+and+nanoplastics+can+be+confounded+by+preservatives+in+commercial+formulations.">Toxicity assessments of micro- and nanoplastics can be confounded by preservatives in commercial formulations.</a> Environmental Science &amp; Technology Letters. 6, 21-25 (2019).</li><li>Lidster, K., Readman, G. D., Prescott, M. J., Owen, S. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=International+survey+on+the+use+and+welfare+of+zebrafish+Danio+rerio+in+research.">International survey on the use and welfare of zebrafish Danio rerio in research.</a> Journal of Fish Biology. 90, 1891-1905 (2017).</li><li>Pitt, J. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uptake,+tissue+distribution,+and+toxicity+of+polystyrene+nanoparticles+in+developing+zebrafish+(Danio+rerio).">Uptake, tissue distribution, and toxicity of polystyrene nanoparticles in developing zebrafish (Danio rerio).</a> Aquatic Toxicology. 194, 185-194 (2018).</li><li>Lin, S. J., Zhao, Y., Nel, A. 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The author declares no competing or financial interests.

According to the guideline on the protection of animals used for scientific purposes, such as EU Directive 2010/63/EU, animal ethics permission is not mandatory for an experiment with early life-stages of zebrafish until the stage of being capable of independent feeding (5 days post fertilization)17. However, best welfare practice is important for optimizing the use of zebrafish, and, for example, the humane methods of anesthesia and euthanasia should be of concern. Ethyl 3-aminobenzoate methanesulphate (MS-222, or tricaine), the routinely used agent in the most laboratories, is employed here for anesthesia and euthanasia.
Before observation under the microscope, the embryos and larvae should be rinsed since the microplastics adsorbed on the external surface might interfere with the results. In addition, the autofluorescence in the embryos/larvae, especially around the yolk sac, which has been reported occasionally, might be problematic. The presence of many biomacromolecules, such as flavins, nicotinamide-adenine dinucleotide (NAD), aromatic amino acids, lipofuscins, advanced glycation end products, and collage, will emit light when excited at the appropriate wavelength. 
It is important to note that, as the particulate pollutant, the size of microplastic is considered as one of the determining factors of bioavailability, and toxicity18. The nominal diameter of microplastic used here is 500 nm, which is comparative to the pore size of the embryo chorion (within the range of 300 nm to 1 &#181;m)19. Therefore, these microplastics are not expected to easily pass through the zebrafish chorion. Consistently, there is little fluorescence visible in the embryos before hatching (Figure 1). Since the chorion will act as an effective barrier against the particles with large size, the dechorionation process before exposure may be needed. Chorion can be removed easily using the forceps, but enzymatic dechorionation with pronase is preferred when the embryos are handled in bulk. However, although dechorionation will increase the bioavailability and facilitate the high-throughput screening for the toxicity of substances, the embryo with chorion intact is more recommended to assess the ecotoxicity of pollutants when considering the condition of exposure in the "real" world. 
Although considerable efforts have been devoted to investigating the adverse effects of microplastics on fish, the current knowledge, including that of bioaccumulation, remain limited or even conflicting. These across-study inconsistencies are mainly attributed to the differences of properties of particles, including size, density, and surface characteristics (for example, surface charge). The behavior of microplastics in the solution is critical to the bioavailability as well. The physicochemical characteristics of microplastics should be tracked over the exposure duration, and the aggregation phenomenon that may occur should be recorded. In fact, for the exposures that require the microplastics to be suspended for an extended period, sonication or stirring with a magnetic bar is recommended.

Since first synthesized in the 1900s, plastics are widely used in various fields, resulting in rapid growth of global production1. In 2018, approximately 360 million tons of plastics were produced worldwide2. The plastics in the natural environment will degrade to fine particles due to chemical, physical or biological processes3. Generally, fine plastic particles &lt;5 mm in size are defined as microplastics4. Microplastics are also engineered for specific applications, such as microbeads from cosmetic products5. As near-permanent contaminants, microplastics are accumulated in the environment, and have attracted increasing attention from scientists, policymakers and the public1,6. Previous studies documented that microplastics could cause adverse effects in fish, such as gastrointestinal damage7, neurotoxicity8, endocrine disruption9, oxidative stress10 and DNA damage11. However, the toxicity of microplastics has not been fully revealed so far12,13.
Zebrafish embryos offer a lot of experimental advantages, including small size, external fertilization, optical transparency and large clutches, and is considered as an ideal model organism for in vivo studying the effects of pollutants on fish at early life stages. In addition, only limited amounts of test substances are needed for the evaluation of biological responses. Here, zebrafish embryos are exposed to different concentrations of microplastics (0.1, 1, 10 mg/L) for 5 days, and the bioaccumulation and distribution of microplastics in zebrafish embryos/larvae are evaluated. This result will advance our understanding about the toxicity of microplastics to fish, and the method described here can potentially be generalized to determine the accumulation and distribution of other types of fluorescent materials in the early life stages of zebrafish.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Fluorescent microscope</td>
			<td>Nikon, Japan</td>
			<td>Eclipse Ti-S</td>
			<td></td>
		</tr>
		<tr>
			<td>Green fluorescently labeled polystyrene beads</td>
			<td>Phosphorex, USA</td>
			<td>2103A</td>
			<td></td>
		</tr>
		<tr>
			<td>Tricaine</td>
			<td>Sigma-Aldrich, USA</td>
			<td>A5040</td>
			<td></td>
		</tr>
	</tbody>
</table>

accumulation and distribution of fluorescent microplastics in the early life stages of zebrafish

As a new type of environmental pollutant, microplastic has been widely found in the aquatic environment and poses a high threat to aquatic organisms. The bioaccumulation of microplastics plays a key role in their toxic effects; however, as a particulate, their bioaccumulations are different from many other pollutants. Described here is a feasible method to visually determine the accumulation and distribution of microplastics in zebrafish embryos or larvae using fluorescent microplastics. Embryos are exposed to different concentrations (0.1, 1, and 10 mg/L) of fluorescent microplastics with a diameter of 500 nm for 120 h. It is shown in the results that microplastics can bioaccumulate in zebrafish embryos/larvae in a concentration-dependent manner. Before hatching, strong fluorescence is found around the embryonic chorion; while in zebrafish larvae, the yolk sac, pericardium, and gastrointestinal tract are the main accumulated sites of microplastics. The results demonstrate the uptake and internalization of microplastics in zebrafish at early life stages, which will provide basis for better understanding the impact of microplastics on aquatic animals.

The distribution and accumulation of fluorescent microplastics are shown in Figure 1 and Table 1. No visible fluorescence is observed in the unexposed group (control). However, an accumulation of fluorescence is found surrounding the chorion after exposure to different concentrations of microplastics (24 hpf). Green fluorescence is also detected in larvae, and the fluorescence levels appear to increase in a concentration- and time-dependent manner. The yolk sac, pericardium, and gastrointestinal tract are the main accumulated sites of microplastics (Figure 2).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/62117/62117fig01.jpg" /> 
Figure 1:&#160;Distribution of fluorescent polystyrene microplastics in embryos/larvae of zebrafish (40&#215;). The fish are sampled from the control group, or the groups exposed to 500-nm microplastics at 0.1, 1 and 10 mg/L.&#160;Scale bar 100 &#181;m <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62117/62117fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/62117/62117fig02.jpg" /> 
Figure 2:&#160;The sites of microplastic accumulation in zebrafish larvae (40&#215;). This larva is sampled from the group exposed to 500-nm microplastics at 10 mg/L for 120 hours. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/62117/62117fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Concentration</td>
			<td>Embryo</td>
			<td></td>
			<td>Larva</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>(mg/L)</td>
			<td>24 hpf</td>
			<td>48 hpf&#160;a</td>
			<td>48 hpf b</td>
			<td>72 hpf</td>
			<td>96 hpf</td>
			<td>120 hpf</td>
		</tr>
		<tr>
			<td>Cont.</td>
			<td>1.2&#177;0.1</td>
			<td>2.6&#177;0.3</td>
			<td>2.2</td>
			<td>3.0&#177;0.2</td>
			<td>2.6&#177;0.7</td>
			<td>3.3&#177;0.3</td>
		</tr>
		<tr>
			<td>1</td>
			<td>1.2&#177;0.2</td>
			<td>5.0&#177;0.1</td>
			<td>5.3</td>
			<td>7.5&#177;0.5</td>
			<td>8.7&#177;0.5</td>
			<td>10.0&#177;1.9</td>
		</tr>
		<tr>
			<td>0.1</td>
			<td>7.0&#177;0.9</td>
			<td>26.1&#177;2.9</td>
			<td>8.9</td>
			<td>18.4&#177;0.7</td>
			<td>16.3&#177;2.8</td>
			<td>25.7&#177;2.7</td>
		</tr>
		<tr>
			<td>10</td>
			<td>9.1&#177;1.1</td>
			<td>82.3&#177;5.3</td>
			<td>30.4</td>
			<td>32.7&#177;3.2</td>
			<td>41.6&#177;0.4</td>
			<td>44.1&#177;0.9</td>
		</tr>
		<tr>
			<td colspan="7">a: only two embryos were assessed; b: only one larva was assessed.</td>
		</tr>
	</tbody>
</table>
Table 1: The change of fluorescence level in zebrafish following exposure to fluorescent microplastics (n=3). Due to the influence of chorion on the absorption of fluorescent microplastics, the data are divided into two parts, that of the embryos (before hatching) and larvae (after hatching).

Watch this Scientific Journal Video about Accumulation and Distribution of Fluorescent Microplastics in the Early Life Stages of Zebrafish at JoVE.com

Accumulation and Distribution of Fluorescent Microplastics in the Early Life Stages of Zebrafish

Zebrafish embryos/larvae develop externally and are optically transparent. The bioaccumulation of microplastics in fish at early life stages is readily assessed with fluorescently labeled microbeads.

As a new type of environmental pollutant, microplastic has been widely found in the aquatic environment and poses a high threat to aquatic organisms. The ...

accumulation-distribution-fluorescent-microplastics-early-life-stages

Nanyang Technological University

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JoVE Journal

Environment

4.6K Views.  Zhejiang University of Technology. Zebrafish embryos/larvae develop externally and are optically transparent. The bioaccumulation of microplastics in fish at early life stages is readily assessed with fluorescently labeled microbeads.

Video: Accumulation and Distribution of Fluorescent Microplastics in the Early Life Stages of Zebrafish

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 ...

Controlled-release of Chlorine Dioxide in a Perforated Packaging System to Extend the Storage Life and Improve the Safety of Grape Tomatoes

A controlled-release chlorine dioxide (ClO2) pouch was developed by sealing a slurry form of ClO2 into semipermeable polymer film; the release properties of the pouch were monitored in containers with or without fruit. The pouch was affixed to the inside of a perforated clamshell containing grape tomatoes, and the effect on microbial population, firmness, and weight loss was evaluated during a 14 day storage period at 20 &#176;C. Within 3 days, the ClO2 concentration in the clamshells reached 3.5 ppm and remained constant until day 10. Thereafter, it decreased to 2 ppm by day 14. The ClO2 pouch exhibited strong antimicrobial activity, reducing Escherichia coli populations by 3.08 log CFU/g and Alternaria alternata populations by 2.85 log CFU/g after 14 days of storage. The ClO2 treatment also reduced softening and weight loss and extended the overall shelf life of the tomatoes. Our results suggest that ClO2 treatment is useful for extending the shelf life and improving the microbial safety of tomatoes during storage without impairing their quality.

Here, we describe a protocol for the application of a novel, slow-release ClO2 product that reduces spoilage and extends the shelf life of fresh fruit. The slow-release ClO2 product was added to standard commercial grape tomato packaging and tested against Escherichia coli and Alternaria alternata.

A controlled-release chlorine dioxide (ClO2) pouch was developed by sealing a slurry form of ClO2 into semipermeable polymer film; the release properties ...

Methodology for Developing Life Tables for Sessile Insects in the Field Using the Whitefly, Bemisia tabaci, in Cotton As a Model System

Life tables provide a means of measuring the schedules of birth and death from populations over time. They also can be used to quantify the sources and rates of mortality in populations, which has a variety of applications in ecology, including agricultural ecosystems. Horizontal, or cohort-based, life tables provide for the most direct and accurate method of quantifying vital population rates because they follow a group of individuals in a population from birth to death. Here, protocols are presented for conducting and analyzing cohort-based life tables in the field that takes advantage of the sessile nature of the immature life stages of a global insect pest, Bemisia tabaci. Individual insects are located on the underside of cotton leaves and are marked by drawing a small circle around the insect with a non-toxic pen. This insect can then be observed repeatedly over time with the aid of hand lenses to measure development from one stage to the next and to identify stage-specific causes of death associated with natural and introduced mortality forces. Analyses explain how to correctly measure multiple mortality forces that act contemporaneously within each stage and how to use such data to provide meaningful population dynamic metrics. The method does not directly account for adult survival and reproduction, which limits inference to dynamics of immature stages. An example is presented that focused on measuring the impact of bottom-up (plant quality) and top-down (natural enemies) effects on the mortality dynamics of B. tabaci in the cotton system.

Methodology for Developing Life Tables for Sessile Insects in the Field Using the Whitefly, Bemisia tabaci, in Cotton As a Model System

Life tables allow quantification of the sources and rates of mortality in insect populations and contribute to understanding, predicting and manipulating population dynamics in agroecosystems. Methods for conducting and analyzing cohort-based life tables in the field for an insect with sessile immature life stages are presented.

Life tables provide a means of measuring the schedules of birth and death from populations over time. They also can be used to quantify the sources and ...

The Effect of the Application of Thyme Essential Oil on Microbial Load During Meat Drying

Meat is a high protein meal that is used in the preparation of jerky, a popular food snack, where preservation and safety are important. To assure food safety and to extend the shelf life of meat and meat products, the use of either synthetic or natural preservatives have been applied to control and eliminate foodborne bacteria. A growing interest in the application of natural food additives for meat has increased. Microorganisms, such as Escherichia coli, contaminate meat and meat products, causing foodborne illnesses. Therefore, it is necessary to improve the meat conservation process. However, the use of essential oils when the meat is being dried has not been deeply studied. In this regard, there is an opportunity to increase the value of dried meat and reduce the risk of foodborne illnesses by applying essential oils during the drying process. In this protocol, we present a novel method of applying thyme essential oil (TEO) during meat drying, specifically in vapor form directly in a drying chamber. For evaluation, we use Minimal Inhibitory Concentration (MIC) to detect the number of harmful bacteria in the treated samples compared to raw samples. The preliminary results show that this method is a viable and alternative option to synthetic preservatives and that it significantly reduces microbial load in dried meat.

Microorganisms such as Escherichia coli that contaminate meat products cause foodborne illnesses. The use of essential oils in the meat drying process has not been deeply studied. Here, we present a novel method of applying thyme essential oil to meat during drying to reduce the microbial load in dried meat.

Meat is a high protein meal that is used in the preparation of jerky, a popular food snack, where preservation and safety are important. To assure food ...

Sampling, Sorting, and Characterizing Microplastics in Aquatic Environments with High Suspended Sediment Loads and Large Floating Debris

The ubiquitous presence of plastic debris in the ocean is widely recognized by the public, scientific communities, and government agencies. However, only recently have microplastics in freshwater systems, such as rivers and lakes, been quantified. Microplastic sampling at the surface usually consists of deploying drift nets behind either a stationary or moving boat, which limits the sampling to environments with low levels of suspended sediments and floating or submerged debris. Previous studies that employed drift nets to collect microplastic debris typically used nets with &#8805;300 &#181;m mesh size, allowing plastic debris (particles and fibers) below this size to pass through the net and elude quantification. The protocol detailed here enables: 1) sample collection in environments with high suspended loads and floating or submerged debris and 2) the capture and quantification of microplastic particles and fibers &lt;300 &#181;m. Water samples were collected using a peristaltic pump in low-density polyethylene (PE) containers to be stored before filtering and analysis in the lab. Filtration was done with a custom-made microplastic filtration device containing detachable union joints that housed nylon mesh sieves and mixed cellulose ester membrane filters. Mesh sieves and membrane filters were examined with a stereomicroscope to quantify and separate microplastic particulates and fibers. These materials were then examined using a micro-attenuated total reflectance Fourier transform infrared spectrometer (micro ATR-FTIR) to determine microplastic polymer type. Recovery was measured by spiking samples using blue PE particulates and green nylon fibers; percent recovery was determined to be 100% for particulates and 92% for fibers. This protocol will guide similar studies on microplastics in high velocity rivers with high concentrations of sediment. With simple modifications to the peristaltic pump and filtration device, users can collect and analyze various sample volumes and particulate sizes.

Most microplastic research to date has occurred in marine systems where suspended solid levels are relatively low. Focus is now shifting to freshwater systems, which may feature high sediment loads and floating debris. This protocol addresses collecting and analyzing microplastic samples from aquatic environments that contain high suspended solid loads.

The ubiquitous presence of plastic debris in the ocean is widely recognized by the public, scientific communities, and government agencies. However, only ...

Composition and Distribution Analysis of Bioaerosols Under Different Environmental Conditions

Variable microorganisms in particulate matter (PM) under different environmental conditions may have significant impacts on human health. In this study, we described a protocol for multiple analyses of the biological compositions in environmental PM. Five experiments are presented: (1) PM number monitoring by using a laser particle counter; (2) PM collection by using a cyclonic aerosol sampler; (3) PM collection by using a high-volume air sampler with filters; (4) culturable microbes collection by the Andersen six-stage sampler; and (5) detection of biological composition of environmental PM by bacterial 16SrDNA and fungal ITS region sequencing. We selected hazy days and a livestock farm as two typical examples of the application in this protocol. In this study, these two sampling methods, cyclonic aerosol sampler and filter sampler, showed different sampling efficiency. The cyclonic aerosol sampler performed much better in terms of collecting bacteria, while these two methods showed the same efficiency in collecting fungi. Filter samplers can work under low temperature conditions while cyclonic aerosol samplers have a sampling limitation for temperature. A solid impacting sampler, such as an Andersen six-stage sampler, can be used to sample bioaerosols directly into the culture medium, which increases the survival rate of culturable microorganisms. However, this method mainly relies on culture while more than 99% of microbes cannot be cultured. DNA extracted from the culturable bacteria collected by the Andersen six-stage sampler and samples collected by cyclonic aerosol sampler and filter sampler were detected by bacterial 16S rDNA and fungal ITS region sequencing.All the methods above may have wide application in many fields of study, such as environmental monitoring and airborne pathogen detection. From these results, we can conclude that these methods can be used under different conditions and may help other researchers further explore the health impacts of environmental bioaerosols.

Understanding the biological composition of environmental particulate matter is important for the study of its significant impacts on human health and disease spread. Here, we used three types of bioaerosol sampling methods and a biological analysis of airborne microbes to better explore airborne microbial communities under different environmental conditions.

Variable microorganisms in particulate matter (PM) under different environmental conditions may have significant impacts on human health. In this study, ...

A Telemetric, Gravimetric Platform for Real-Time Physiological Phenotyping of Plant&ndash;Environment Interactions

Food security for the growing global population is a major concern. The data provided by genomic tools far exceeds the supply of phenotypic data, creating a knowledge gap. To meet the challenge of improving crops to feed the growing global population, this gap must be bridged.
Physiological traits are considered key functional traits in the context of responsiveness or sensitivity to environmental conditions. Many recently introduced high-throughput (HTP) phenotyping techniques are based on remote sensing or imaging and are capable of directly measuring morphological traits, but measure physiological parameters mainly indirectly.
This paper describes a method for direct physiological phenotyping that has several advantages for the functional phenotyping of plant&#8211;environment interactions. It helps users overcome the many challenges encountered in the use of load-cell gravimetric systems and pot experiments. The suggested techniques will enable users to distinguish between soil weight, plant weight and soil water content, providing a method for the continuous and simultaneous measurement of dynamic soil, plant and atmosphere conditions, alongside the measurement of key physiological traits. This method allows researchers to closely mimic field stress scenarios while taking into consideration the environment&#8217;s effects on the plants&#8217; physiology. This method also minimizes pot effects, which are one of the major problems in pre-field phenotyping. It includes a feed-back fertigation system that enables a truly randomized experimental design at a field-like plant density. This system detects the soil-water-content limiting threshold (&#952;) and allows for the translation of data into knowledge through the use of a real-time analytic tool and an online statistical resource. This method for the rapid and direct measurement of the physiological responses of multiple plants to a dynamic environment has great potential for use in screening for beneficial traits associated with responses to abiotic stress, in the context of pre-field breeding and crop improvement.

A Telemetric, Gravimetric Platform for Real-Time Physiological Phenotyping of Plant&#8211;Environment Interactions

This high-throughput, telemetric, whole-plant water relations gravimetric phenotyping method enables direct and simultaneous real-time measurements, as well as the analysis of multiple yield-related physiological traits involved in dynamic plant&#8211;environment interactions.

Food security for the growing global population is a major concern. The data provided by genomic tools far exceeds the supply of phenotypic data, creating ...

Ecotoxicological Effects of Microplastics on Bird Embryo Development by Hatching without Eggshell

Microplastics are an emerging global pollutant type that poses a great health threat to animals due to their uptake and translocation in animal tissues and organs. Ecotoxicological effects of microplastics on the development of bird embryos are not known. The bird egg is a complete development and nutrition system, and the entire embryo development occurs in the eggshell. Therefore, a direct record of bird embryo development under the stress of pollutants such as microplastics is highly limited by the opaque eggshell in traditional hatching. In this study, the effects of microplastics on quail embryo development were visually monitored by hatching without an eggshell. The main steps include the cleaning and disinfection of fertilized eggs, the incubation before exposure, the short-term incubation after exposure, and the sample extraction. The results show that compared with the control group, the wet weight and body length of the microplastics-exposed group displayed a statistical difference and the liver proportion of the whole exposed group significantly increased. Additionally, we evaluated external factors that affect the incubation: temperature, humidity, egg rotation angle, and other conditions. This experimental method provides valuable information on the ecotoxicology of microplastics and a novel way to study the adverse effects of pollutants on the development of embryos.

This paper introduces a method of hatching without using an eggshell for toxicological studies of particle pollutants such as microplastics.

Microplastics are an emerging global pollutant type that poses a great health threat to animals due to their uptake and translocation in animal tissues ...

Simulation of Early Earth Hydrothermal Chimneys in a Thermal Gradient Environment

Deep sea hydrothermal vents are self-organizing precipitates generated from geochemical disequilibria and have been proposed as a possible setting for the emergence of life. The growth of hydrothermal chimneys in a thermal gradient environment within an early Earth vent system was successfully simulated by using different hydrothermal simulants, such as sodium sulfide, which were injected into an early Earth ocean simulant containing dissolved ferrous iron. Moreover, an apparatus was developed to sufficiently cool the ocean simulant to near 0 &#176;C in a condenser vessel immersed in a cold water bath while injecting a sulfide solution at hot to room temperatures, effectively creating an artificial chimney structure in a temperature gradient environment over a period of a few hours. Such experiments with different chemistries and variable temperature&#160;gradients resulted in a variety of morphologies in the chimney structure. The use of ocean and hydrothermal fluid simulants at room temperature resulted in vertical chimneys, whereas the combination of a hot hydrothermal fluid and cold ocean simulant inhibited the formation of robust chimney structures. The customizable 3D printed condenser created for this study acts as a jacketed reaction vessel that can be easily modified and used by different researchers. It will allow the careful control of injection rate and chemical composition of vent and ocean simulants, which should help accurately simulate prebiotic reactions in chimney systems with thermal gradients similar to those of natural systems.

The goal of this protocol is to form simulated hydrothermal chimneys via chemical garden injection experiments and introduce a thermal gradient across the inorganic precipitate membrane, using a 3D printable condenser that can be reproduced for educational purposes.

Deep sea hydrothermal vents are self-organizing precipitates generated from geochemical disequilibria and have been proposed as a possible setting for the ...

Monitoring Pedogenic Inorganic Carbon Accumulation Due to Weathering of Amended Silicate Minerals in Agricultural Soils.

The present study aims to demonstrate a systematic procedure for monitoring inorganic carbon induced by enhanced weathering of comminuted rocks in agricultural soils. To this end, the core soil samples taken at different depth (including 0-15 cm, 15-30 cm, and 30-60 cm profiles) are collected from an agriculture field, the topsoil of which has already been enriched with an alkaline earth metal silicate containing mineral (such as wollastonite). After transporting to the laboratory, the soil samples are air-dried and sieved. Then, the inorganic carbon content of the samples is determined by a volumetric method called calcimetry. The representative results presented herein showed five folded increments of inorganic carbon content in the soils amended with the Ca-silicate compared to control soils. This compositional change was accompanied by more than 1 unit of pH increase in the amended soils, implying high dissolution of the silicate. Mineralogical and morphological analyses, as well as elemental composition, further corroborate the increase in the inorganic carbon content of silicate-amended soils. The sampling and analysis methods presented in this study can be adopted by researchers and professionals looking to trace pedogenic inorganic carbon changes in soils and subsoils, including those amended with other suitable silicate rocks such as basalt and olivine. These methods can also be exploited as tools for verifying soil inorganic carbon sequestration by private and governmental entities to certify and award carbon credits.

The verification method described here is adaptable for monitoring pedogenic inorganic carbon sequestration in various agricultural soils amended with alkaline earth metal silicate-containing rocks, such as wollastonite, basalt, and olivine. This type of validation is essential for carbon credit programs, which can benefit farmers that sequester carbon in their fields.

Accumulation and Distribution of Fluorescent Microplastics in the Early Life Stages of Zebrafish

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Chapters in this video

Protocol for Microplastics Sampling on the Sea Surface and Sample Analysis

Controlled-release of Chlorine Dioxide in a Perforated Packaging System to Extend the Storage Life and Improve the Safety of Grape Tomatoes

Methodology for Developing Life Tables for Sessile Insects in the Field Using the Whitefly, Bemisia tabaci, in Cotton As a Model System

The Effect of the Application of Thyme Essential Oil on Microbial Load During Meat Drying

Sampling, Sorting, and Characterizing Microplastics in Aquatic Environments with High Suspended Sediment Loads and Large Floating Debris

Composition and Distribution Analysis of Bioaerosols Under Different Environmental Conditions

A Telemetric, Gravimetric Platform for Real-Time Physiological Phenotyping of Plant–Environment Interactions

Ecotoxicological Effects of Microplastics on Bird Embryo Development by Hatching without Eggshell

Simulation of Early Earth Hydrothermal Chimneys in a Thermal Gradient Environment

Monitoring Pedogenic Inorganic Carbon Accumulation Due to Weathering of Amended Silicate Minerals in Agricultural Soils.