Correspondence/Rebuttal pubs.acs.org/est
Response to Comment on “Uptake and Accumulation of Polystyrene Microplastics in Zebrafish (Danio rerio) and Toxic Effects in Liver”
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e thank Baumann et al. for their interest in the article “Uptake and accumulation of polystyrene microplastics in zebrafish (Danio rerio)”1 and for their careful comments on our paper. Their main concerns regard the designation of tissue type, acquirement of images of fluorescent-labeled MPs in tissues, and histopathologic findings. • In Figure 1, the slides of gut were transverse section, and the structure of intestinal villus is evident. Many studies documented MPs primarily accumulated in gut and excreted through intestinal tract.2 Therefore, the observed MPs accumulated in intestinal epithelium and villus surface is reasonable. In the process of preparing tissue sections and microscope observation, strict quality control procedures were performed to avoid sample contamination. In this study, fluorescent-labeled MPs was used to investigate the distribution and accumulation of MPs in fish tissues. But formalin used for tissue fixation can dissolve the dyes in the MPs, is not conductive to fluorescence detection of MPs. To reduce this adverse effect, shortening the time of tissue fixation is the last resort, which may influence the fixed tissues. In such situation, it is difficult to balance. • In order to observe the presence of fluorescent-labeled polystyrene microplastic particles in tissues, one brightfield image was acquired by microscopy first and then a dark-field image of the same slide was acquired by epifluorescence microscopy. Finally, the two sets of images were stacked together by using AxioVision Rel. 4.7. The results were shown as Figure 1. Actually, this is a very common method for many detections of fluorescent particles.3 • According to published images of hepatocellular necrosis,4−6 we believe necrosis is evident in the MPs exposed livers (Figure 3, red arrows indicate). All the histopathological changes were evaluated by a board certified pathologist blinded to the sample identity. A total of seven tissue samples for each group and five slices for each tissue were analyzed. The percentages of adverse histological changes were 78 ± 10% and 77 ± 11% in 5 μm MPs and 70 nm MPs treatment groups, respectively. We still stand by our main conclusion that MPs exposure induced inflammatory responses in fish liver. In addition, lipid metabolites of triglycerides, fatty acids, choline, phosphorylcholine were significantly changed due to MPs exposure, which indicated that lipid metabolism were disturbed in liver. Lipid droplets observed in fish liver, which was used an important complementary certificate. For energy metabolism, many related metabolites were significantly altered. It has been demonstrated that MPs ingestion could deplete energy reserves in aquatic organisms.7,8 In this situation, ingestion of MPs with no nutritional value influenced the normal absorption of food is a reasonable © XXXX American Chemical Society
explanation. And abnormal food absorption could disturb the metabolism of lipid and energy. In summary, the primary results of this paper remain the same. First, fluorescent-labeled MPs accumulated in zebrafish tissues (gill, liver and gut). Second, MPs exposure induced inflammatory responses in fish liver. Finally, MPs exposure disturbed the metabolism of lipid and energy in zebrafish.
Yifeng Lu† Yan Zhang*,† Yongfeng Deng† Wei Jiang† Yanping Zhao‡ Jinju Geng† Lili Ding† Hongqiang Ren*,† †
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State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, China ‡ Jiangsu Key Lab Environmental Change & Ecological Construct, School of Geography Science, Nanjing Normal University, Nanjing, Jiangsu 210023, China
AUTHOR INFORMATION
Corresponding Authors
*(Y.Z.) Phone: +86 25 89680160; e-mail:
[email protected]. cn. *(H.R.) E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Yifeng, L.; Yan, Z.; Yongfeng, D.; Wei, J.; Yanping, Z.; Jinju, G.; Lili, D.; Hongqiang, R. Uptake and accumulation of polystyrene microplastics in zebrafish (Danio rerio) and toxic effects in liver. Environ. Sci. Technol. 2016, 50 (7), 4054−4060. (2) Lusher, A. L.; McHugh, M.; Thompson, R. C. Occurrence of microplastics in the gastrointestinal tract of pelagic and demersal fish from the English Channel. Mar. Pollut. Bull. 2013, 67 (1−2), 94−99. (3) Hu, M.; Novo, C.; Funston, A.; Wang, H. N.; Staleva, H.; Zou, S. L.; Mulvaney, P.; Xia, Y. N.; Hartland, G. V. Dark-field microscopy studies of single metal nanoparticles: understanding the factors that influence the linewidth of the localized surface plasmon resonance. J. Mater. Chem. 2008, 18 (17), 1949−1960. (4) Wolf, J. C.; Wolfe, M. J. A brief overview of nonneoplastic hepatic toxicity in fish. Toxicol. Pathol. 2005, 33 (1), 75−85. (5) Al-Zaidan, A. S.; Al-Sarawi, H. A.; Massoud, M. S.; Al-Enezi, M.; Smith, A. J.; Bignell, J. P.; Green, M. J.; Askem, C.; Bolam, T. P. C.; Barber, J. L.; Bersuder, P.; Lyons, B. P. Histopathology and contaminant concentrations in fish from Kuwait’s marine environment. Mar. Pollut. Bull. 2015, 100 (2), 637−645. (6) Riley, A. K.; Chernick, M.; Brown, D. R.; Hinton, D. E.; Di Giulio, R. T. Hepatic Responses of Juvenile Fundulus heteroclitus
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DOI: 10.1021/acs.est.6b04379 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
Environmental Science & Technology
Correspondence/Rebuttal
from Pollution-adapted and Nonadapted Populations Exposed to Elizabeth River Sediment Extract. Toxicol. Pathol. 2016, 44 (5), 738− 748. (7) Wright, S. L.; Rowe, D.; Thompson, R. C.; Galloway, T. S. Microplastic ingestion decreases energy reserves in marine worms. Curr. Biol. 2013, 23 (23), R1031−R1033. (8) Cole, M.; Lindeque, P.; Fileman, E.; Halsband, C.; Galloway, T. S. The Impact of Polystyrene Microplastics on Feeding, Function and Fecundity in the Marine Copepod Calanus helgolandicus. Environ. Sci. Technol. 2015, 49 (2), 1130−1137.
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DOI: 10.1021/acs.est.6b04379 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
