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W tym Artykule

  • Podsumowanie
  • Streszczenie
  • Wprowadzenie
  • Protokół
  • Wyniki
  • Dyskusje
  • Ujawnienia
  • Podziękowania
  • Materiały
  • Odniesienia
  • Przedruki i uprawnienia

Podsumowanie

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

Streszczenie

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.

Wprowadzenie

The production of plastic waste was about 6300 Mt in 2015, one-tenth of which was recycled, and the rest was burned or buried underground. It is estimated that about 12,000 Mt of plastic waste would be buried underground by 20501. With the international community's attention to plastic waste, Thompson first proposed the concept of microplastics in 20042. Microplastics (MPs) refer to small particle plastics with a particle diameter less than 5 mm. At present, researchers have detected the ubiquitous presence of MPs in the coastline of various continents, the Atlantic Islands, inland lakes, the Arctic, and deep-sea habitats3,4,5,6,7. Therefore, more researchers have begun to study the environmental hazards of MPs.

Organisms could ingest MPs in the environment. MPs were found in the digestive tract of 233 marine organisms worldwide (including 100% turtle species, 36% seal species, 59% whale species, 59% seabird species, 92 kinds of sea fish, and 6 kinds of invertebrates)8. Moreover, MPs may block the organisms' digestive system, accumulate, and migrate in their bobies9. It has been found that MPs can be transferred via the food chain, and their intake differs with the changes of habitat, growth stage, feeding habits, and food sources10. Some researchers reported the existence of MPs in the droppings of seabirds11, which means that seabirds act as the carrier of MPs. In addition, ingestion of MPs can affect health of some organisms. For example, MPs can be entangled in the gastrointestinal tract, thus increasing the mortality of cetaceans12.

MPs alone have toxic effects on organisms as well as joint toxic effects on organisms with other pollutants. Ingestion of environmental-related concentrations of plastic debris may disturb the endocrine system function of adult fish13. The size of microplastics is one of the important factors that affect their uptake and accumulation by organisms14,15. The small-size plastics, especially the nanosize plastics, are prone to interaction with cells and organisms with high toxicity16,17,18,19. Although the harmful effects of nano-particle size microplastics on organisms exceed the current research level, the detection and quantification of microplastics with sizes less than several micrometers, especially the submicron/nano-plastics in the environment, is still a great challenge. In addition, nano-plastics also have some effects on embryos. Polystyrene can damage the development of sea urchin embryos by regulating protein and gene profiles20.

To explore the potential impact of MPs on organisms, we conducted this study. Due to the similarity between bird embryos and human embryos, they are usually used in developmental biology research21 including angiogenesis and antiangiogenesis, tissue engineering, biomaterial implant, and brain tumors22,23,24. Bird embryos have the advantages of low cost, a short culture cycle and easy operation25,26. Therefore, we chose quail embryos with a short growth cycle as the experimental animal in this study. Simultaneously, we can directly observe the morphological changes of quail embryos exposed to MPs during the embryonic development stage using an eggshell-free hatching technology. The experimental materials used were polypropylene (PP) and polystyrene (PS). Because PP and PS27 account for the largest proportion of polymer types obtained in sediments and water bodies worldwide, the most common polymer types extracted from captured marine organisms are ethylene and propylene28. This experimental protocol describes the whole process for visual evaluation of toxicological effects of MPs on quail embryos exposed to MPs. We can easily extend this method to examine other pollutants' toxicity to embryo development of other oviparous animals.

Protokół

1. Preparation before exposure

  1. Select fertilized quail eggs born on the same day for the exposure test.
  2. Select quail eggs with similar weights. Each fertilized quail egg is about 10-12 g.
  3. Fully clean all fertilized quail eggs from external feces and other debris.
  4. Sterilize each pre-hatched fertilized quail egg and the eggs to be used (Choose eggs with similar shell shape, especially the tip of the egg) with an antibiotic solution (penicillin and streptomycin, 1:1000, room temperature). Sterilize the incubator with 75% ethanol.
  5. Open the eggs with the blunt end of a dental drill, leaving the eggshell at the tip for further use. Before transferring the fertilized eggs, the contents of the eggs are poured out. This is to keep the moisture of the eggshell. The opening diameter of the egg was about 3 cm.
    NOTE: To reduce the damage to the quail embryo, use a dental drill to open the blunt end of the egg and make the crack as smooth as possible.
  6. After sterilization, place the fertilized quail eggs in a 38 °C incubator with 60% humidity for 24-48 h. Ensure that the blunt end of the quail egg faces up.
  7. During the incubation of fertilized quail eggs, sterilize the tools needed in the subsequent experiments in a sterilization pot. These tools include plastic wrap, a beaker, sterile water, pipette tips, surgical straight scissors, tweezers, and a spoon.
    NOTE: Use a film with a temperature tolerance high enough to avoid problems with the high-temperature sterilization.

2. Hatching the quail egg without a shell

  1. Transfer the pre-hatched fertilized quail eggs from the incubator to a clean bench and lay them flat on the container to stabilize them for about 1-2 min.
  2. Use scissors (12.5 cm surgical straight scissor) to poke a small hole (diameter 3 mm) in the central axis of the pre-hatched fertilized quail eggs and to cut 1-2 cm small opening. Carefully transfer the egg white and yolk of the fertilized quail eggs to the cut eggshell.
    NOTE: When cutting a small opening with scissors, avoid touching of the yolk of quail eggs.
  3. Add the control solution (without MPs) and the exposed solution of different masses (0.1, 0.2, and 0.3 mg) of microplastics with three particle sizes (100, 200, and 500 nm) to the egg contents by pipette. At the same time, add 1 drop of penicillin and 1 drop of streptomycin with a 1 mL syringe.
  4. Cover the opening of the eggshell with the sterilized film (step 1.6).
  5. According to step 2.1-2.4, treat all the fertilized quail eggs.
  6. Place the transferred quail embryos into the 38 °C incubator with 60% humidity for the necessary period. In this experiment, use an egg rotation angle of ±30°. Turn the eggs once an hour.
    ​NOTE: The transfer should be as fast as possible, which requires more practice at the early stage.

3. Sample collection

  1. After seven days of culture, remove well-developed embryos observed by the naked eye from the yolk and wash with phosphate buffered solution (PBS).
  2. Dry the surplus solution outside the cleaned embryo with absorbent paper and weigh in a clean Petri dish.
  3. Open the whole chest cavity, separate the liver and the heart from the viscera with needle-nose pliers, and place in 1.5 mL centrifuge tubes immediately after clearing.
  4. Quickly record the weight on an electronic balance and calculate the hepatosomatic index (HIS = liver weight / body weight x 100). Measure the length of the sternum and body.
  5. Based on the above indicators, evaluate the impact of MPs on embryonic development.
    ​NOTE: Embryo quality here refers to the quality of yolk removal.

4. Data analysis

  1. Report the experimental data in the form of mean ± standard error (SEM).
  2. Use single-factor analysis of variance to compare the means of multiple groups of samples. The significant difference value was α = 0.05.

Wyniki

For the analysis of experimental data, we compared wet weight, body length, sternum length and the change of hepatosomatic index between the control group and the 6 experimental groups, measuring and reflecting the quail embryos' growth and development from a macro perspective. We detected six normal quail embryos in each group. Each embryo reached the required Hamburger and Hamilton (HH) stage.

In Figure 1, we transferred the pre-hatched fertilized quail egg ...

Dyskusje

This paper provides an effective experimental scheme to evaluate quail embryo development by detecting the basic development indexes. However, there are still some limitations to this experiment.

First, the mortality of quail embryos in the later stage of hatching is higher because of the shell-less hatching. There are artificially uncontrollable factors such as the destruction of normal protein ratio in the experimental process. We limited the exposure time of embryos to ensure the accuracy ...

Ujawnienia

The authors have nothing to disclose. All authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work of this paper.

Podziękowania

This work was supported by Key Research and Development projects in Xinjiang Uygur Autonomous Region (2017B03014, 2017B03014-1, 2017B03014-2, 2017B03014-3).

Materiały

NameCompanyCatalog NumberComments
 Multi sample tissue grinderShanghai Jingxin Industrial Development Co., Ltd.Tissuelyser-24Grind large-sized plastics into small-sized ones at low temperature
Electronic balanceOHAUS corporationPR Series PrecisionUsed for weighing
Fertilized quail eggsGuangzhou Cangmu Agricultural Development Co., Ltd.Quail eggs for hatching without shell
Fluorescent polypropylene particlesFoshan Juliang Optical Material Co., Ltd.Types of plastics selected for the experiment
IncubatorShandong, Bangda Incubation Equipment Co., Ltd.264 pcProvide a place for embryo growth and development
Nanometer-scale polystyrene microspheresXi’an Ruixi Biological Technology Co., Ltd.100 nm, 200 nm, 500 nmTypes of plastics selected for the experiment
Steel rulerDeli Group20 cmUsed to measure  length
Vertical heating pressure steam sterilizerShanghai Shenan Medical Instrument FactoryLDZM-80KCS-IISterilize the experimental articles

Odniesienia

  1. Geyer, R., Jambeck, J. R., Law, K. L. Production, use, and fate of all plastics ever made. Science Advances. 3 (7), 5 (2017).
  2. Thompson, R. C., et al. Lost at sea: Where is all the plastic. Science. 304 (5672), 838-838 (2004).
  3. Barletta, M., Lima, A. R. A., Costa, M. F. Distribution, sources and consequences of nutrients, persistent organic pollutants, metals and microplastics in South American estuaries. Science of the Total Environment. 651, 1199-1218 (2019).
  4. Eriksson, C., Burton, H., Fitch, S., Schulz, M., vanden Hoff, J. Daily accumulation rates of marine debris on sub-Antarctic island beaches. Marine Pollution Bulletin. 66 (1-2), 199-208 (2013).
  5. Zhang, C. F., et al. Microplastics in offshore sediment in the Yellow Sea and East China Sea, China. Environmental Pollution. 244, 827-833 (2019).
  6. Obbard, R. W., et al. Global warming releases microplastic legacy frozen in Arctic Sea ice. Earths Future. 2 (6), 315-320 (2014).
  7. Van Cauwenberghe, L., Vanreusel, A., Mees, J., Janssen, C. R. Microplastic pollution in deep-sea sediments. Environmental Pollution. 182, 495-499 (2013).
  8. Wilcox, C., Van Sebille, E., Hardesty, B. D. Threat of plastic pollution to seabirds is global, pervasive, and increasing. Proceedings of the National Academy of Sciences of the United States of America. 112 (38), 11899-11904 (2015).
  9. Wright, S. L., Thompson, R. C., Galloway, T. S. The physical impacts of microplastics on marine organisms: A review. Environmental Pollution. 178, 483-492 (2013).
  10. Ferreira, G. V. B., Barletta, M., Lima, A. R. A. Use of estuarine resources by top predator fishes. How do ecological patterns affect rates of contamination by microplastics. Science of the Total Environment. 655, 292-304 (2019).
  11. Provencher, J. F., Vermaire, J. C., Avery-Gomm, S., Braune, B. M., Mallory, M. L. Garbage in guano? Microplastic debris found in faecal precursors of seabirds known to ingest plastics. Science of the Total Environment. 644, 1477-1484 (2018).
  12. Baulch, S., Perry, C. Evaluating the impacts of marine debris on cetaceans. Marine Pollution Bulletin. 80 (1-2), 210-221 (2014).
  13. Rochman, C. M., Kurobe, T., Flores, I., Teh, S. J. Early warning signs of endocrine disruption in adult fish from the ingestion of polyethylene with and without sorbed chemical pollutants from the marine environment. Science of the Total Environment. 493, 656-661 (2014).
  14. Mattsson, K., et al. Brain damage and behavioural disorders in fish induced by plastic nanoparticles delivered through the food chain. Scientific Reports. 7, 7 (2017).
  15. Brown, D. M., Wilson, M. R., MacNee, W., Stone, V., Donaldson, K. Size-dependent proinflammatory effects of ultrafine polystyrene particles: A role for surface area and oxidative stress in the enhanced activity of ultrafines. Toxicology and Applied Pharmacology. 175 (3), 191-199 (2001).
  16. Salvati, A., et al. Experimental and theoretical comparison of intracellular import of polymeric nanoparticles and small molecules: toward models of uptake kinetics. Nanomedicine-Nanotechnology Biology and Medicine. 7 (6), 818-826 (2011).
  17. Frohlich, E., et al. Action of polystyrene nanoparticles of different sizes on lysosomal function and integrity. Particle and Fibre Toxicology. 9, 13 (2012).
  18. Bexiga, M. G., Kelly, C., Dawson, K. A., Simpson, J. C. RNAi-mediated inhibition of apoptosis fails to prevent cationic nanoparticle-induced cell death in cultured cells. Nanomedicine. 9 (11), 1651-1664 (2014).
  19. Lehner, R., Weder, C., Petri-Fink, A., Rothen-Rutishauser, B. Emergence of Nanoplastic in the Environment and Possible Impact on Human Health. Environmental Science, Technology. 53 (4), 1748-1765 (2019).
  20. Pinsino, A., et al. Amino-modified polystyrene nanoparticles affect signalling pathways of the sea urchin (Paracentrotus lividus) embryos. Nanotoxicology. 11 (2), 201-209 (2017).
  21. El-Ghali, N., Rabadi, M., Ezin, A. M., De Bellard, M. E. New Methods for Chicken Embryo Manipulations. Microscopy Research and Technique. 73 (1), 58-66 (2010).
  22. Rashidi, H., Sottile, V. The chick embryo: hatching a model for contemporary biomedical research. Bioessays. 31 (4), 459-465 (2009).
  23. Faez, T., Skachkov, I., Versluis, M., Kooiman, K., de Jong, N. In vivo characterization of ultrasound contrast agents: microbubble spectroscopy in a chicken embryo. Ultrasound in Medicine and Biology. 38 (9), 1608-1617 (2012).
  24. Yamamoto, F. Y., Neto, F. F., Freitas, P. F., Ribeiro, C. A. O., Ortolani-Machado, C. F. Cadmium effects on early development of chick embryos. Environmental Toxicology and Pharmacology. 34 (2), 548-555 (2012).
  25. Li, X. D., et al. Caffeine interferes embryonic development through over-stimulating serotonergic system in chicken embryo. Food and Chemical Toxicology. 50 (6), 1848-1853 (2012).
  26. Lokman, N. A., Elder, A. S. F., Ricciardelli, C., Oehler, M. K. Chick Chorioallantoic Membrane (CAM) Assay as an In Vivo Model to Study the Effect of Newly Identified Molecules on Ovarian Cancer Invasion and Metastasis. International Journal of Molecular Sciences. 13 (8), 9959-9970 (2012).
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Ecotoxicological EffectsMicroplasticsBird EmbryosHatching Without EggshellQuail EggsIncubation ProcessSample CollectionEnvironmental PollutantEmbryo DevelopmentFertilized EggsDisinfectionExposure TestControl GroupWeight DifferenceBody LengthLiver ProportionExternal Factors

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