Publications by authors named "Xiaoshan Zhu"

78 Publications

Ecotoxicological effects of DBPs on freshwater phytoplankton communities in co-culture systems.

J Hazard Mater 2021 Jul 17;421:126679. Epub 2021 Jul 17.

State Key Laboratory of Urban Water Resource and Environment of Harbin Institute of Technology, Shenzhen 518055, PR China. Electronic address:

Intensive disinfection of wastewater during the COVID-19 pandemic might elevate the generation of toxic disinfection byproducts (DBPs), which has triggered global concerns about their ecological risks to natural aquatic ecosystems. In this study, the toxicity of 17 DBPs typically present in wastewater effluents on three representative microalgae, including Scenedesmus sp. (Chlorophyta), Microcystis aeruginosa (Cyanophyta), and Cyclotella sp. (Bacillariophyta) was investigated. The sensitivities of the three microalgae to DBPs varied greatly from species to species, indicating that DBPs may change the structure of phytoplankton communities. Later, co-cultures of these phytoplankton groups as a proxy of ecological freshwater scenario were conducted to explore the impacts of DBPs on phytoplankton community succession. M. aeruginosa became surprisingly dominant in co-cultures, representing over 50% after dosing with monochloroacetic acid (MCAA, 0.1-10 mg/L). The highest proportion of M. aeruginosa was 70.3% when exposed to 2 mg/L MCAA. Although Scenedesmus sp. dominated in monochloroacetonitrile (MCAN) exposure, M. aeruginosa accounted for no less than 30% even at 40 mg/L MCAN. In this study, DBPs disrupted the original inter-algal relationship in favor of M. aeruginosa, suggesting that DBPs may contribute to the outbreak of cyanobacterial blooms in aquatic ecosystems.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126679DOI Listing
July 2021

Toxicity of 17 Disinfection By-products to Different Trophic Levels of Aquatic Organisms: Ecological Risks and Mechanisms.

Environ Sci Technol 2021 08 16;55(15):10534-10541. Epub 2021 Jun 16.

Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, P. R. China.

Intensified disinfection of wastewater during the COVID-19 pandemic increased the release of toxic disinfection by-products (DBPs). However, studies relating to the ecological impacts of DBPs on the aquatic environment remain insufficient. In this study, we comparatively investigated the toxicities and ecological risks of 17 typical, halogenated DBPs to three trophic levels of organisms in the freshwater ecosystem, including phytoplankton ( sp.), zooplankton (), and fish (). Toxicity of DBPs was found to be species-specific: sp. was the most sensitive to haloacetic acids, while was the most sensitive to haloacetonitriles and trihalomethanes. Specific to each DBP, toxicities were also related to their classes and substituted halogen atoms. Damage to photosystems and oxidative stress served as the potential mechanisms for DBPs toxicity to microalgae. The different sensitivities to DBPs indicate that a battery of bioassays with organisms at different trophic levels is necessary to determine the ecotoxicity of DBPs. Furthermore, the ecological risks of DBPs were assessed by calculating the risk quotients (RQs) based on toxicity data from multiple bioassays. The cumulative RQs of DBPs to all the organisms were greater than 1.0, indicating high ecological risks of DBPs in wastewater effluents.
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http://dx.doi.org/10.1021/acs.est.0c08796DOI Listing
August 2021

Combined toxicity of nano-TiO and Cd to Scenedesmus obliquus: Effects at different concentration ratios.

J Hazard Mater 2021 Sep 9;418:126354. Epub 2021 Jun 9.

Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.

The continuous release of manufactured nanomaterials (MNMs) to environments raised concerns on their combined toxicological risks with co-existing contaminants, since MNMs might severely alter the environmental behavior and fate of the contaminants. In this study, the combined toxicity of nano-sized titanium dioxide (nTiO) and cadmium (Cd) to the green alga Scenedesmus obliquus and the underlying physicochemical mechanisms were investigated for the first time at different concentration ratios of Cd to nTiO to closely mimic the realistic environment scenarios where the concentration ratios of nTiO to other contaminants are constantly changing. Our results suggested that under the co-exposure to different concentration ratios of Cd to nTiO, the co-exposure contaminants exhibited three different combined toxicity modes (antagonistic, partially additive, and synergistic). Specifically, antagonistic combined toxicity was observed under co-exposure to a low concentration ratio of nTiO to Cd as the absorption by nTiO decreased the bioavailability of Cd. However, the partially additive and synergistic combined toxicity occurred when the proportion of nTiO in the co-exposure system was relatively high, which would mechanically and/or oxidatively damage the alga cell structures. Even worse, as a carrier of Cd, nTiO enhanced the amount of Cd entering cells, which significantly enhanced the toxicity of Cd to algae. Overall, we demonstrated that concentration ratios of nTiO to Cd play an important role in determining the combined toxicity mode, which would provide a novel reference to environmental and health risk assessment of co-exposure to conventional pollutants and MNMs.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126354DOI Listing
September 2021

A Highly Sensitive Time-Gated Fluorescence Immunoassay Platform Using Mn-Doped AgZnInS/ZnS Nanocrystals as Signal Transducers.

Front Phys 2021 Jan 27;8. Epub 2021 Jan 27.

Department of Electrical and Biomedical Engineering, University of Nevada, Reno, NV, United States.

In this work, a time-gated immunoassay platform using low-energy excitable and fluorescence long-lived Mn:AgZnInS/ZnS nanocrystals as signal transducers was developed and applied to the detection of the capsular polysaccharide (CPS) of , a Gram-negative bacterium that is the causative agent of melioidosis. CPS is a high molecular weight antigen displayed and is shed from the outer membrane of . The immunoassay using the time-gated platform presents a limit of detection at around 23 pg/ml when CPS is spiked in human serum.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8009851PMC
January 2021

Relationships between above- and below-ground carbon stocks in mangrove forests facilitate better estimation of total mangrove blue carbon.

Carbon Balance Manag 2021 Mar 17;16(1). Epub 2021 Mar 17.

Key Laboratory for Earth System Modeling, Ministry of Education, Department of Earth System Science, Tsinghua University, Beijing, 100084,, China.

Background: Although great efforts have been made to quantify mangrove carbon stocks, accurate estimations of below-ground carbon stocks remain unreliable. In this study, we examined the distribution patterns of mangrove carbon stocks in China and other countries using our own field survey data and datasets from published literature. Based on these data, we investigated the possible relationships between above-ground carbon stock (AGC) and below-ground carbon stock (BGC) for mangrove forests, aiming to provide a scientific basis for estimation of total mangrove carbon stocks.

Results: The average above-ground carbon stock in each region was sizeable (ranging from 12.0 to 150.2 Mg/ha), but average below-ground carbon stock was dominant (ranging from 46.6 to 388.6 Mg/ha), accounting for 69-91% of total carbon stock at the sites studied in China. Significant positive relationships were found between above-ground and below-ground mangrove carbon stocks, with the best fitting equation as BGC = 1.58 * AGC + 81.06 (Mg/ha, R = 0.62, p < 0.01, n = 122) for China. Such linear relationships vary for mangrove forests of different types and locations, from different geographical regions in China to other countries worldwide.

Conclusion: The positive relationship we found between above- and below-ground carbon stocks of mangrove forests in China and worldwide can facilitate more accurate assessments of mangrove blue carbon stocks at regional or global scales using modern techniques including remote sensing.
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http://dx.doi.org/10.1186/s13021-021-00172-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7972349PMC
March 2021

Subanesthetic isoflurane abates ROS-activated MAPK/NF-κB signaling to repress ischemia-induced microglia inflammation and brain injury.

Aging (Albany NY) 2020 12 28;12(24):26121-26139. Epub 2020 Dec 28.

Centre of Inflammation and Cancer Research, 150th Central Hospital of PLA, Luoyang 471031, Henan, China.

Isoflurane (ISO) elicits protective effects on ischemia-induced brain injury. We investigated whether sub-anesthetic (0.7%) ISO post-conditioning attenuates the inflammation and apoptosis in oxygen-glucose deprivation (OGD)-insulted co-cultures (microglia and neurons) and the brain injury of the middle cerebral arterial occlusion (MCAO) rat. We demonstrated that ISO augmented the viability of OGD-treated microglia and neurons. ISO reduced the expression and activation of COX2 and iNOS in OGD-challenged microglia. ISO repressed the production of tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-8, and monocyte chemoattractant protein-1 in OGD-exposed microglia. ISO also decreased nucleosomal fragmentation and caspase-3 activity but increased mitochondrial membrane potential in OGD-stimulated microglia and neurons. Mechanistically, ISO suppressed OGD-induced microglial inflammation by blocking ROS-regulated p38 MAPK/NF-κB signaling pathway and hampered OGD-triggered microglial apoptosis in a ROS- or NO-dependent fashion. results with MCAO rats were partly consistent with the observation. These findings indicate that sub-anesthetic ISO post-conditioning abates the inflammation and apoptosis in OGD-stimulated rat microglia and the apoptosis of OGD-exposed neurons and the brain injuries of MCAO rats, suggesting it as a potentially effective therapeutic approach for ischemic brain damages.
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http://dx.doi.org/10.18632/aging.202349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7803578PMC
December 2020

TiO nanoparticles enhanced bioaccumulation and toxic performance of PAHs via trophic transfer.

J Hazard Mater 2021 04 15;407:124834. Epub 2020 Dec 15.

Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, PR China.

Engineering nanoparticles (NPs) could act as accumulator and carrier of co-contaminants, affecting their fate and toxicity in environments. However, the effects of NPs on the bioaccumulation and trophic transfer of co-contaminants through the food chain and the ensuing effects on higher predators are unclear. In the present study, we investigated the effects of titanium dioxide nanoparticles (nTiO) on the trophic transfer of phenanthrene (Phe) from prey Artemia salina to predator Scophthalmus maximus. We also evaluated the ensuing toxic performance of Phe in S. maximus after been transferred from A. salina in the presence and absence of nTiO. The presence of nTiO significantly (p < 0.05) increased Phe accumulation in A. salina with higher bioconcentration factor (BCF) up to 90.9 than that of 38.6 in Phe exposure along. After trophic transfer, nTiO (1 mg/L) also promoted the bioaccumulation of Phe (1 μg/L) in predator S. maximus from 4.17 mg/kg to 7.85 mg/kg (dry weight). However, nTiO did not enhance the trophic transfer of Phe from A. salina to S. maximus since the biological magnification factor (BMF) decreased from 0.13 to 0.08. Nevertheless, the nTiO-enhanced bioaccumulation of Phe did enhance Phe toxicity performance in predator S. maximus after trophic transfer, showing significant (p < 0.05) growth inhibition and changes of nutrient status in the predator, compared to those of the control. Further physio-biochemical investigations suggested that oxidative stress and inhibition of digestive functions might explain the growth inhibition in treatment with nTiO + Phe. This study demonstrates the first evidence that NP-enhanced bioaccumulation and toxic performance of co-existing pollutants across trophic transfer, which poses potential risks to marine ecosystems, and ultimately human health by seafood consumption.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124834DOI Listing
April 2021

Bovine surfactant in the treatment of pneumonia-induced-neonatal acute respiratory distress syndrome (NARDS) in neonates beyond 34 weeks of gestation: a multicentre, randomized, assessor-blinded, placebo-controlled trial.

Eur J Pediatr 2021 Apr 21;180(4):1107-1115. Epub 2020 Oct 21.

Department of Neonatology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.

Neonatal acute respiratory distress syndrome (NARDS) reflects pulmonary surfactant dysfunction, and the usage of bovine surfactant (Calsurf) supplement may therefore be beneficial. To determine whether bovine surfactant given in NARDS can improve oxygenation and survival rate, we conducted a multicenter, randomized trial between January 2018 and June 2019, and we compared Calsurf treatment to controls in neonates with pneumonia accompanied by NARDS. Neonates who met the Montreux criteria definition of NARDS were included, and those with congenital heart and lung malformations were excluded. Primary outcomes were oxygenation index (OI) after Calsurf administration, and secondary outcomes were mortality, and duration of ventilator and oxygen between the two groups, and also other morbidities. Cumulatively, 328 neonates were recruited and analyzed, 162 in the control group, and 166 in the Calsurf group. The results shows that OI in the Calsurf group were significantly lower than that in the control group at 4 h (7.2 ± 2.7 and 11.4 ± 9.1, P = 0.001); similarly, OI in the Calsurf group were significantly lower than in the control group at 12 h ( 7.5 ± 3.1 and 11.2 ± 9.2, P = 0.001). Mortality and duration of ventilator support or oxygen use between the two groups were not significantly different.Conclusion: Calsurf acutely improved OI immediately after administration in pneumonia-induced NARDS; although, we observed no significant decrease in mortality, duration of ventilator or oxygen, or major morbidity. What is known: • The definition proposed as the Monteux criteria for neonatal acute respiratory distress syndrome (NARDS). • Surfactant acutely improved oxygenation and significantly decreased mortality in children and adolescents with acute lung injury. What is new: • This is the first large randomized controlled trail to study on surfactant treatment of neonates with acute respiratory distress syndromes. • Surfactant acutely improved oxygenation immediately after administration in pneumonia-induced NARDS at a gestational age beyond 34 weeks.
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http://dx.doi.org/10.1007/s00431-020-03821-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7575859PMC
April 2021

TiO Nanoparticles in the Marine Environment: Enhancing Bioconcentration, While Limiting Biotransformation of Arsenic in the Mussel .

Environ Sci Technol 2020 10 9;54(19):12254-12261. Epub 2020 Sep 9.

Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, P. R. China.

The increasing use of nanoscale TiO particles (nTiO) and their subsequent leakage into aquatic environments poses a threat to the ecosystem. One major concern is that nTiO may alter the environmental behaviors of arsenic (As) and disrupt the equilibrium of As accumulation and speciation in organisms. In this study, we investigated the effects of nTiO on the bioaccumulation and biotransformation of As(V) in the mussel . Exposure to nTiO significantly increased As accumulation in mussels. Our As speciation analysis demonstrated that nTiO treatment increased the proportion of inorganic As and reduced that of organic As, displaying inhibitory effects on the methylation and detoxification of inorganic As in mussels. Analysis of enzyme systems related to As metabolism in mussels demonstrated that nTiO might limit the methylation of inorganic As by suppressing the GST activity and GSH content. The strong adsorption capacity and weak desorption rate of As by nTiO, which could result in the disruption of As distribution and decrease of the amount of As involved in biotransformation, might serve as another mechanism to the limition on As methylation in mussels. Moreover, exposure to nTiO disturbed the osmotic adjustment system in mussels by reducing arsenobetaine and Na-K-ATPase activity, resulting in enhanced toxicity of As after coexposure. The findings indicate, for the first time, that nTiO can block the transformation and detoxification of As in mussels, which would increase the risk of As to marine animals and even humans via the food chain, and may disrupt the biogeochemical cycle of As in natural environments.
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http://dx.doi.org/10.1021/acs.est.0c01620DOI Listing
October 2020

In vitro oxidative stress, mitochondrial impairment and G1 phase cell cycle arrest induced by alkyl-phosphorus-containing flame retardants.

Chemosphere 2020 Jun 24;248:126026. Epub 2020 Jan 24.

State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.

Phosphorus-containing flame retardants (PFRs) have been frequently detected in various environmental samples at relatively high concentrations and are considered emerging environmental pollutants. However, their biological effects and the underlying mechanism remain unclear, especially alkyl-PFRs. In this study, a battery of in vitro bioassays was conducted to analyze the cytotoxicity, oxidative stress, mitochondrial impairment, DNA damage and the involved molecular mechanisms of several selected alkyl-PFRs. Results showed that alkyl-PFRs induced structural related toxicity, where alkyl-PFRs with higher logKow values induced higher cytotoxicity. Long-chain alkyl-PFRs caused mitochondrial and DNA damage, resulting from intracellular reactive oxygen species (ROS) and mitochondrial superoxide overproduction; while short-chain alkyl-PFRs displayed adverse outcomes by significantly impairing mitochondria without obvious ROS generation. In addition, alkyl-PFRs caused DNA damage-induced cell cycle arrest, as determined by flow cytometry, and transcriptionally upregulated key transcription factors in p53/p21-mediated cell cycle pathways. Moreover, compared to the control condition, triisobutyl phosphate and trimethyl phosphate exposure increased the sub-G1 apoptotic peak and upregulated the p53/bax apoptosis pathway, indicating potential cell apoptosis at the cellular and molecular levels. These results provide insight into PFR toxicity and the involved mode of action and indicate the mitochondria is an important target for some alkyl-PFRs.
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http://dx.doi.org/10.1016/j.chemosphere.2020.126026DOI Listing
June 2020

Mitigation effects of CO-driven ocean acidification on Cd toxicity to the marine diatom Skeletonema costatum.

Environ Pollut 2020 Apr 19;259:113850. Epub 2019 Dec 19.

College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, PR China.

Ocean acidification (OA) is a global problem to marine ecosystems. Cadmium (Cd) is a typical metal pollutant, which is non-essential but extremely toxic to marine organisms. The combined effects of marine pollution and climate-driven ocean changes should be considered for the effective marine ecosystem management of coastal areas. Previous reports have separately investigated the influences of OA and Cd pollution on marine organisms. However, little is known of the potential combined effects of OA and Cd pollution on marine diatoms. We investigated the sole and combined influences of OA (1500 ppm CO) and Cd exposure (0.4 and 1.2 mg/L) on the coastal diatom Skeletonema costatum. Our results clearly showed that OA significantly alleviated the toxicity of Cd to S. costatum growth and mitigated the oxidant stress, although the intercellular Cd accumulation still increased. OA partially rescued S. costatum from the inhibition of photosynthesis and pyruvate metabolism caused by Cd exposure. It also upregulated genes involved in gluconeogenesis, glycolysis, the citrate cycle (TCA), Ribonucleic acid (RNA) metabolism, and especially the biosynthesis of non-protein thiol compounds. These changes might contribute to algal growth and Cd resistance. Overall, this study demonstrates that OA can alleviate Cd toxicity to S. costatum and explores the potential underlying mechanisms at both the cellular and molecular levels. These results will ultimately help us understand the impacts of combined stresses of climate change and metal pollution on marine organisms and expand the knowledge of the ecological risks of OA.
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http://dx.doi.org/10.1016/j.envpol.2019.113850DOI Listing
April 2020

Prognostic Significance and Diagnostic Value of Overexpressed lncRNA PVT1 in Colorectal Cancer.

Clin Lab 2019 Dec;65(12)

Background: The aim of this study is to investigate the expression of lncRNA PVT1 in CRC tissue compared to adjacent normal tissues, and reveal the association between lncRNA PVT1 expression level and the clinicopathological characteristics of patients with CRC.

Methods: We detected the lncRNA PVT1 relative expression of cancerous tissues in 130 patients with CRC by using real-time quantitative polymerase chain reaction. At the same time, we collected the clinicopathological and prognostic information.

Results: IncRNA PVT1 was overexpressed in CRC tissues compared to paired-adjacent normal tissues and the high expression rate was 72.31%. High expression of lncRNA PVT1 predicts a later tumor stage (p = 0.001), poorer tissue differentiation (p = 0.019), and higher plasma CEA level (p = 0.043). Additionally, the lncRNA PVT1 expression was closely related to lymph node metastasis (N1/N2 vs. N0) and distant metastasis (M1 vs. M0) in CRC patients (p = 0.002; p = 0.003), but not to tumor T classification (p = 0.314). The result of prognostic analysis indicated that the 1-year and 3-year DFS of the lncRNA PVT1 low and high expression patients were 93.8% and 81.1%, 69.3% and 44.7%, respectively. The median DFS was 44 months in low expression group and 26 months in high expression group, with statistical significance (p = 0.021). COX multivariate analysis showed that TNM staging (III/IV vs. I/II: HR = 6.342, 95% CI: 2.994 - 13.433, p < 0.001) and the lncRNA PVT1 expression (high expression vs. low expression: HR = 3.744, 95% CI: 1.493 - 9.392, p = 0.005) was closely related to DFS in CRC patients. As with tumor TNM staging, lncRNA PVT1 expression was also an independent prognostic predictor of DFS. The proportion of lncRNA PVT1 high expression (fold change ≥ 1.725) was higher than that of elevated CEA ( > 5 ng/mL) in different CRC stages, especially, there was a significant difference in stage I patients (X2 = 41.717, p < 0.0001).

Conclusions: The lncRNA PVT1 was over-expressed in CRC tissues, which indicated a poor prognosis. The lncRNA PVT1 expression is far higher than the plasma CEA level in the early stage patients, which has the potential diagnostic value for early stage CRC.
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http://dx.doi.org/10.7754/Clin.Lab.2019.190412DOI Listing
December 2019

The distribution, characteristics and ecological risks of microplastics in the mangroves of Southern China.

Sci Total Environ 2020 Mar 5;708:135025. Epub 2019 Nov 5.

Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.

During the production, use and disposal of plastic products, microplastics (MPs) are dispersed into the surrounding environment and have inevitable impacts on mangrove ecosystems in estuaries and offshore areas. In the mangroves of Southern China, the systematic evaluation of the distribution, characteristics and ecological risks of MPs is lacking. In this study, surface sediments (0-5 cm depth) were collected from six representative mangroves in China to explore MP contamination and its associated ecological risk. Based on the results, MP concentrations of MPs in mangrove sediments were as follows: FT (2249 ± 747 items/kg), ZJ (736 ± 269 items/kg), DF (649 ± 443 items/kg), DZG (431 ± 170 items/kg), YX (424 ± 127 items/kg), and FCG (227 ± 173 items/kg). The higher MP concentration in the Futian mangrove was mainly related to inputs from the Pearl River, the third largest river in China. The predominant shape, colour, and size of MPs were fibrous, white-transparent, and 500-5000 μm, respectively. The main MP polymer types were polypropylene, polyethylene, and polystyrene. Degradation artefacts were present on surface of MPs as well as metallic and non-metallic elements. MPs concentration in mangrove sediments increased with increasing social-economic development of surrounding districts, which indicated the clear influence of anthropogenic activity on MP pollution in these mangroves. Furthermore, total organic carbon (TOC) and silt content were positively associated with MPs (P < 0.01), indicating a facilitatory role in deposition of MPs in mangroves. Based on a comprehensive evaluation using the potential ecological risk factor (E), potential ecological risk (RI), polymer risk index (H) and pollution load index (PLI), MPs were found to present ecological risks in these mangroves, with the highest risk occurring in the Futian mangrove.
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http://dx.doi.org/10.1016/j.scitotenv.2019.135025DOI Listing
March 2020

Combined effects of CO-driven ocean acidification and Cd stress in the marine environment: Enhanced tolerance of Phaeodactylum tricornutum to Cd exposure.

Mar Pollut Bull 2020 Jan 11;150:110594. Epub 2019 Nov 11.

College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518055, PR China. Electronic address:

Ocean acidification (OA) and heavy metals are common stress factors for marine ecosystems subject to anthropogenic impacts. OA coupled with the heavy metal is likely to affect marine species. This study investigated the single and combined effects of OA (1500 ppm) and cadmium (Cd; 0.4, 1.2 mg/L) on the marine diatom Phaeodactylum tricornutum under 7 d exposure. The results clearly indicated that either OA or Cd stress (1.2 mg/L) alone inhibited the growth of P. tricornutum. However, under the combined OA-Cd stress, the growth inhibition disappeared, and the intracellular oxidative damage was mitigated. These results indicated a significantly enhanced tolerance of P. tricornutum to Cd while under OA conditions, which could be beneficial to the survival of this diatom. This study will ultimately help us understand the responses of marine organisms to multiple stressors and have broad implications for the potential ecological risks of Cd under future OA conditions.
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http://dx.doi.org/10.1016/j.marpolbul.2019.110594DOI Listing
January 2020

Oncogenic USP22 supports gastric cancer growth and metastasis by activating c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling.

Aging (Albany NY) 2019 11 4;11(21):9643-9660. Epub 2019 Nov 4.

Centre of Inflammation and Cancer Research, 150th Central Hospital of PLA, Luoyang, Henan 471031, China.

In this study, we investigated the role of ubiquitin-specific protease 22 (USP22) in the growth and progression of gastric cancer (GC). USP22 mRNA and protein levels were significantly higher in GC tissue samples and GC cell lines than in adjacent noncancerous tissue samples and a normal gastric mucosal epithelial cell line (GES1), respectively. USP22 knockdown significantly decreased survival, proliferation, migration, and invasiveness of GC cells compared with the controls. Western blot analysis of control and USP22-silenced GC cells showed that USP22 modulates the c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling pathways. Subcutanenous injection of USP22-silenced GC cells into SCID mice generated significantly smaller xenograft tumors than did control cells. Moreover, USP22-silenced GC cells showed less lung metastasis than the controls following tail vein injection in SCID mice. In addition, high USP22 expression correlated positively with tumor size, advanced stage and metastasis, and correlated negatively with tumor differentiation and prognosis in GC patients. These results show that USP22 regulates growth and progression of GC via the c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling pathways.
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http://dx.doi.org/10.18632/aging.102410DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874452PMC
November 2019

Behavioural and chronic toxicity of fullerene to Daphnia magna: Mechanisms revealed by transcriptomic analysis.

Environ Pollut 2019 Dec 7;255(Pt 1):113181. Epub 2019 Sep 7.

Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, PR China.

Extensive application of fullerene nanoparticles (nC) leads to potential environmental pollution. The acute toxic effects of nC have been largely investigated, but studies of behavioural and chronic toxicity at sublethal doses are still rare and the underlying molecular mechanisms remain unknown. The present study investigated behavioural and chronic toxicity of nC to Daphnia magna. The results showed that, in response to nC exposure, hopping, heartbeat frequencies and feeding ability of D. magna decreased significantly, displaying negative relationship with exposure time and dose. Chronic treatments with 0.1 mg/L or 1 mg/L nC for 21 days significantly reduced survival and reproduction of D. magna. These harmful effects suggested negative impacts of nC on aquatic ecosystems. Moreover, transcriptome analysis showed that the behavioural and chronic toxicity of nC to D. magna might be related to physiological functions such as cell structural repair, protein degradation, energy metabolism and reproduction. We found that nC accumulated in guts of D. magna, which should be responsible for the decrease of food ingestion and consequently inhibiting energy intake. Deficiency of energy not only affects behaviours but also declines reproduction in D. magna. Overall, this is the first study comprehensively considered the behavioral and chronic toxicity of nC to aquatic organism. The results should be helpful to better understand the ecological consequences of C released into water environments.
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http://dx.doi.org/10.1016/j.envpol.2019.113181DOI Listing
December 2019

Alleviative Effects of C on the Trophic Transfer of Cadmium along the Food Chain in Aquatic Environment.

Environ Sci Technol 2019 Jul 5;53(14):8381-8388. Epub 2019 Jul 5.

Graduate School at Shenzhen , Tsinghua University , Shenzhen 518055 , P.R. China.

C could enhance the accumulation of pollutants in organisms, but their effects on higher trophic levels remain unknown. In the present study, the transfer of C from to zebrafish () and its effects on Cd transfer were investigated. The results showed that C could be transferred from to zebrafish through dietary exposure and accumulate mainly in the intestines, but biomagnification was not observed. The presence of C promoted accumulation of Cd in . However, it decreased Cd burden in the higher trophic level (zebrafish), displaying an alleviative effect on the trophic transfer of Cd along the food chain. To explore the underlying mechanisms, the release of Cd from in digestive fluids and changes in zebrafish digestive physiology were further investigated. The results showed that C did not inhibit Cd release from , but stimulated the digestive tracts of zebrafish to excrete Cd earlier and in a greater amount, which consequently lowered assimilation efficiency of Cd in zebrafish. Overall, the present study showed the trophic transfer of C in the aquatic food chain and revealed the effects of C on trophic transfer of Cd along the food chain in aquatic environment.
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http://dx.doi.org/10.1021/acs.est.9b01636DOI Listing
July 2019

Recovery of Alexandrium tamarense under chronic exposure of TiO nanoparticles and possible mechanisms.

Aquat Toxicol 2019 Mar 9;208:98-108. Epub 2019 Jan 9.

Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, China; School of Environment, Tsinghua University, Beijing, 100084, China. Electronic address:

Harmful algal blooms (HAB), heavily influenced by human activities, pose serious hazard to aquatic ecology and human health. In this study, we monitored the physiological responses and paralytic shellfish poisoning toxins (PSTs) of the toxin-producing HAB species Alexandrium tamarense under titanium dioxide nanoparticles (TiO) exposure in the concentration range of 2-320 mg L over a period of 13 days. The results showed the acute inhibition of TiO on the algal growth, photosynthetic efficiency and esterase activity at all concentrations except 2 mg L. Nonetheless, they recovered after 13 days TiO exposure from 20 to 80 mg L. The EC value increased from 85.1 mg L in Day 4 to 140.9 mg L in Day 13. The physiological recovery after prolonged exposure may result from the elimination of excess reactive oxygen species (ROS), a combined outcome of increased TiO aggregation and algal antioxidant defense mechanisms. This observation is supported by the immediately increased antioxidant enzyme activities, including the superoxide dismutase (SOD) and catalase (CAT) activities upon TiO exposure. Moreover, the production of PSTs in A. tamarense significantly increased by 1.41-1.76 folds after chronic TiO exposure at all tested concentrations (p < 0.05), which might also be an adaptive response for the microalgae to overcome the stresses. In particular, the proportions of highly-toxic PSTs analogues GTX2/3, STX and dcSTX were significantly increased upon TiO exposure (p < 0.05). Hence, the chronic TiO exposure might aggravate the ecological impact of HABs. Furthermore investigations on different HAB species, especially those toxin-producing ones, and detail physiological responses are obviously needed.
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http://dx.doi.org/10.1016/j.aquatox.2019.01.007DOI Listing
March 2019

Effects of Carbon Quantum Dots on Aquatic Environments: Comparison of Toxicity to Organisms at Different Trophic Levels.

Environ Sci Technol 2018 12 7;52(24):14445-14451. Epub 2018 Dec 7.

Graduate School at Shenzhen , Tsinghua University , Shenzhen 518055 , P.R. China.

Carbon quantum dots (CQDs) have high hydrophilicity, high cell permeability, and are frequently used in water-based and biorelated applications, yet studies concerning the ecological risks of CQDs in aquatic environments are largely insufficient. In the present study, the toxicity of CQDs to zebrafish ( Danio rerio), zooplankton ( Daphnia magna), and phytoplankton ( Scenedesmus obliquus) were assessed for the first time. The results indicated that CQDs (up to 200 mg/L) could be depurated by D. rerio with negligible toxicity. In comparison, CQDs induced mortality and immobility in D. magna with a 48-h EC value and LC value of 97.5 and 160.3 mg/L, respectively. In S. obliquus, CQDs inhibited photosynthesis and nutrition absorption in a dose- and time-dependent manner, and the growth of algae was also inhibited with a 96-h EC value of 74.8 mg/L, suggesting that S. obliquus, the lowest trophic level in this study, was most sensitive to CQDs exposure. Further investigations revealed that CQDs induced an increase in oxidative stress in algae cells and a decrease in pH value of an algae medium, indicating that oxidative stress and water acidification may be the mechanisms underlying the toxicity of CQDs to S. obliquus.
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http://dx.doi.org/10.1021/acs.est.8b04235DOI Listing
December 2018

Graphene oxide in the marine environment: Toxicity to Artemia salina with and without the presence of Phe and Cd.

Chemosphere 2018 Nov 24;211:390-396. Epub 2018 Jul 24.

Shenzhen Key Laboratory of Organic Pollution Prevention and Control, State Key Laboratory of Urban Water Resource and Environment of Harbin Institute of Technology (Shenzhen), 518055, China. Electronic address:

Given the increasing potential of graphene oxide entering marine environments, it is imperative to assess the risks of GO on marine ecosystem, including its direct toxicity to marine organisms and indirect toxicity brought by co-existing aquatic pollutants, as a result of the remarkable adsorption capacity of GO. In the present study, the acute toxicity of GO, Phe, Cd, GO-Phe, and GO-Cd to Artemia salina were systemically assessed and compared for the first time. Although the lethal effects of GO alone to A. salina only appeared at high GO dose (500 mg/L), its sublethal toxicity (growth inhibition) at concentrations as low as 1 mg/L was observed by microscopy, which was likely closely related to the GO-induced oxidative stress in A. salina. Compared with the toxicity of Phe alone, GO-Phe exhibited a synergistic effect to A. salina at a high GO concentration. For GO-Cd, the toxicity was positively correlated with both GO dose and Cd dose. The increased toxicity of GO-Phe or GO-Cd at high doses might be attributed to the promoted bioaccumulation of toxicants by GO, as the adhesion of GO complexes to intestinal tract of A. salina was observed during the toxicity tests, which probably resulted in further toxicological effects.
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http://dx.doi.org/10.1016/j.chemosphere.2018.07.140DOI Listing
November 2018

Mn Doped AZIS/ZnS Nanocrystals (NCs): Effects of Ag and Mn Levels on NC Optical Properties.

J Alloys Compd 2018 Oct 19;765:236-244. Epub 2018 Jun 19.

Department of Electrical and Biomedical Engineering, University of Nevada Reno, NV, USA.

In this work, Mn-doped AZIS/ZnS NCs were prepared using a nucleation doping approach with the tuning of Mn and Ag levels in their synthesis. The optical properties of Mn:AZIS/ZnS NCs are found to be significantly affected by Ag and Mn levels. Specifically, more Ag and Mn atoms in Mn:AZIS/ZnS NCs cause their fluorescence red-shift, and as the Ag or Mn level reaches a high threshold, the fluorescence lifetime of Mn:AZIS/ZnS NC has a significant drop. The reasons for the effects of Mn and Ag levels on NC optical properties were explored and discussed. Through this study, it is also found that with certain Ag and Mn levels in synthesis, some Mn:AZIS/ZnS NCs present optimal optical properties including high brightness (QY > 40%), long fluorescence lifetime (> 1.2 ms), low energy for excitation (excitable at 405 nm), and no reabsorption. The feasibility of the optimized NCs for time-gated fluorescence measurement using a portable/compact instrument was further demonstrated, which indicates the application potential of the NCs in time-gated biosensing including point-of-care testing. Notably, this study also discloses that Mn:AZIS/ZnS NCs with different lifetimes can be achieved by tuning Mn and Ag levels in synthesis, which may further broaden the applications of Mn:AZIS/ZnS NCs in multiplexing detection/measurement.
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http://dx.doi.org/10.1016/j.jallcom.2018.06.173DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6039121PMC
October 2018

Tolerance and bioaccumulation of combined copper, zinc, and cadmium in Sesuvium portulacastrum.

Mar Pollut Bull 2018 Jun 24;131(Pt A):416-421. Epub 2018 Apr 24.

School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China. Electronic address:

Sesuvium portulacastrum was treated with mixture of copper, zinc, and cadmium for 60 days, with the concentration of each metal ranging from 0 to 20 mg/L. The tolerance of plants and bioaccumulation of heavy metals were then investigated. The height of S. portulacastrum decreased significantly with increasing heavy metal concentrations from 1 to 20 mg/L. The biomass was adversely impacted when the concentration exceeded 5 mg/L. There were no significant differences in malondialdehyde (MDA) concentration among different treatment groups, while the soluble protein content and superoxide dismutase (SOD) activity decreased with increasing heavy metal concentration. However, the BCF values of the three metals were all higher than 10 and the tolerance in root was up to 1000 mg/kg without causing significant growth inhibition, suggesting that S. portulacastrum should be a potential candidate for phytostabilization for the phytoremediation of polymetallic contaminations in coastal environments.
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http://dx.doi.org/10.1016/j.marpolbul.2018.04.049DOI Listing
June 2018

Biofilm inhibition and pathogenicity attenuation in bacteria by .

R Soc Open Sci 2018 Apr 18;5(4):170702. Epub 2018 Apr 18.

Shenzhen Public Service Platforms of Marine Microbial Resource Screening and Exploitation, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, Guangdong, People's Republic of China.

Biofilms play an important role in the antibiotic resistance of encased bacteria, and biofilm formation is regulated by quorum sensing (QS). Inhibiting the QS system may, therefore, degrade the integrity of a biofilm and expose the bacterial pathogens within it to the deleterious effects of molecules such as antibiotics. Moreover, the use of QS inhibitors (QSIs) may provide a novel approach for treating bacterial infections of aquacultures. In the present study, the bacterium was identified as a potential producer of QSIs. Varying concentrations (0.1-1.1%) of filtrates prepared from the culture of inhibited biofilm formation by the pathogens , and by as much as 58.9%, 41.5% and 41.9%, respectively. These filtrates as well as the crude aqueous extracts prepared from them increased the sensitivities of pathogens to the inhibitory effects of kanamycin. The filtrates also showed pathogenicity attenuation potential in by decreasing the production of virulence factors. Moreover, the filtrates did not influence the planktonic growth of these pathogens. The results indicate that may act as a non-specific (or broad-spectrum) inhibitor of biofilm formation that will help control infectious diseases that adversely affect the aquaculture industry.
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http://dx.doi.org/10.1098/rsos.170702DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5936886PMC
April 2018

A mechanism study on toxicity of graphene oxide to Daphnia magna: Direct link between bioaccumulation and oxidative stress.

Environ Pollut 2018 Mar 21;234:953-959. Epub 2017 Dec 21.

Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, China.

Graphene oxide (GO) possesses versatile applicability and high hydrophilicity, thus may have frequent contact with aquatic organisms. However, the ecological risks of GO in aquatic ecosystems remain largely unexplored currently. This study evaluated the comprehensive toxicological effects of GO on Daphnia magna, a key species in fresh water ecosystem. The results revealed nonsevere acute toxicities, including immobility (72 h EC: 44.3 mg/L) and mortality (72 h LC: 45.4 mg/L), of GO on D. magna. To understand the underlying mechanism of GO exposure, changes in superoxide dismutase (SOD) and lipid peroxidation (LPO) of D. magna exposed to GO were correlated, which revealed elevated GO-mediated oxidative stress and damages, especially in the long-time and high-dose exposure groups. The observations of in vivo fluorescence labeled with 2', 7'-dichlorofluorescin further demonstrated that reactive oxygen species were concentrated in daphnia guts, which corresponded with the high bioaccumulation level (5 mg/L, 24 h body burden: 107.9 g/kg) of GO in daphnia guts. However, depuration of GO from daphnia was not difficult. Daphnia almost released all GO within 24 h after it was transferred to clean water. These results hence suggest that GO could accumulate and induce significant oxidative stress in the gut of D. magna, while D. daphnia can also relieve the acute toxicity by depurating GO.
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http://dx.doi.org/10.1016/j.envpol.2017.12.034DOI Listing
March 2018

Mn Doped AIZS/ZnS Nanocrystals: Synthesis and Optical Properties.

J Alloys Compd 2017 Nov 28;725:1077-1083. Epub 2017 Jul 28.

Department of Electrical and Biomedical Engineering, University of Nevada Reno, NV, USA.

In this work, Mn doped AIZS/ZnS (Mn:AIZS/ZnS) nanocrystals (NCs) have been synthesized in an approach using heat-up and drop-wise addition of precursors. On the basis of the characterization of these doped NCs on their optical properties and materials, it is found that: (1) as more Mn atoms are doped into NCs, the doped NCs present photoluminescence (PL) red-shift and quantum yield quenching; (2) the doped NCs possess a short PL lifetime in tens of microseconds and a long PL lifetime in hundreds of microseconds, and the short lived PL is more dominant than the long lived one; and (3) the doped NCs present a reversible PL thermal quenching in a range from room temperature to 170°C. Possible PL mechanisms of these NCs were discussed by analyzing their time-resolved PL spectra and thermal stability.
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http://dx.doi.org/10.1016/j.jallcom.2017.07.262DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5724564PMC
November 2017

TiO nanoparticles in the marine environment: Impact on the toxicity of phenanthrene and Cd to marine zooplankton Artemia salina.

Sci Total Environ 2018 Feb 4;615:375-380. Epub 2017 Oct 4.

Graduate School at Shenzhen, Tsinghua University, Shenzhen, China.

The impact of manufactured nanoparticles on the toxicity of co-existing pollutants in aquatic environments has raised increasing concerns. However, the toxicity of polycyclic aromatic hydrocarbons or metal ions in the presence of titanium dioxide nanoparticles (nTiO) to marine zooplankton has been rarely reported. In the present study, the impacts of nTiO on the toxicity of phenanthrene (Phe) and cadium (Cd) to Artemia salina, a model marine zooplankton, were investigated. Although nTiO alone exerted a limited toxicity to A. salina within 48h of exposure, nTiO strongly altered the toxicity of Phe and Cd to A. salina. Compared with the individual toxicities of pollutants to A. salina, the toxicities of Phe and Cd increased by 2.0% and 12.2%, respectively, in the presence of 5mg/L nTiO but decreased by 24.5% and 57.1%, respectively, in the presence of 400mg/L nTiO. These concentration-dependent impacts of nTiO on the toxicity of Phe or Cd might be attributed to the concurrent functions of several interrelated factors including the adsorption of pollutants on nTiO, the nTiO-faciliated bioaccumulation of pollutants, the limited gut volume in organisms, and the aggregation and sedimentation behaviors of nTiO. These results presented in the study could help understand the effects of manufactured nanomaterials in marine environments.
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http://dx.doi.org/10.1016/j.scitotenv.2017.09.292DOI Listing
February 2018

Tolerance and bioaccumulation of Cd and Cu in Sesuvium portulacastrum.

Ecotoxicol Environ Saf 2018 Jan 14;147:306-312. Epub 2017 Sep 14.

School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China. Electronic address:

In order to investigate the tolerance and bioaccumulation of Cd and Cu in the halophyte Sesuvium portulacastrum, seedlings were hydroponically cultured for 30 days using the modified 1/2 Hoagland nutrient solution with different concentrations of Cd (0, 5, 10, 15, and 20mgL) and Cu (0, 2.5, 5, 7.5, and 10mgL). Afterwards, the seedling height, leaf area, biomass, and mineral element contents (Fe, Mg, Cu, and Zn) in the roots, stems and leaves were measured, and the tolerance index, bioconcentration factor (BCF), transportation index, and removal rate were calculated. The effects of salinity (0‰-30‰) on the growth and bioaccumulation ability of S. portulacastrum under combined Cu/Cd (5mgL) exposure were also determined. The results showed that, with an increasing Cd concentration, the biomass and seedling height of S. portulacastrum initially increased and then decreased. The highest leaf biomass and seedlings height was observed in the 10mgL and 5mgL Cd treatment group, respectively. Salinity did not affect the biomass of S. portulacastrum but decreased Cd concentration in roots and aboveground tissues and Cu concentration in roots of S. portulacastrum. Cu treatment significantly facilitated the absorption of Mg, Cu, and Zn in roots. With an increasing Cu concentration, the Mg and Fe contents increased in the leaves of S. portulacastrum. In comparison to the above-ground portions, the root showed a higher bioaccumulation ability of Cd and Cu, with the BCF of 341.5 and 211.9, respectively. The BCF and translocation factor (TF) values indicated that S. portulacastrum was not a hyperaccumulator for Cd and Cu, but could be used as a phytostablization plant in heavy metal contaminated coastal environments.
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http://dx.doi.org/10.1016/j.ecoenv.2017.08.056DOI Listing
January 2018

Exposure of engineered nanoparticles to Alexandrium tamarense (Dinophyceae): Healthy impacts of nanoparticles via toxin-producing dinoflagellate.

Sci Total Environ 2018 Jan 11;610-611:356-366. Epub 2017 Aug 11.

Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China; School of Environment, Tsinghua University, Beijing 100084, China. Electronic address:

Human activities can enhance the frequency, intensity and occurrence of harmful algal blooms (HABs). Engineered nanoparticles (ENPs), contained in many materials, will inevitably enter coastal waters and thus cause unpredictable impacts on aquatic organisms. However, knowledge of the influence of ENPs on HAB species is still lacking. In this study, we examined the effects of titanium dioxide nanoparticles (TiO), zinc oxide nanoparticles (ZnO) and aluminum oxide nanoparticles (AlO) on physiological changes and paralytic shellfish poisoning toxins (PSTs) production of Alexandrium tamarense. We found a dose-dependent decrease in photosynthetic activity of A. tamarense under all three ENPs and a significant growth inhibition induced by ZnO. The largest reactive oxygen species (ROS) production was induced by TiO, followed by ZnO and AlO. Moreover, the PSTs production rate increased by 3.9-fold for TiO (p<0.01) and 4.5-fold for AlO (p<0.01) at a concentration of 200mgL. The major component, C2 was transformed to its epimer C1 and the proportion of decarbamoyl toxins increased under 200mgL of ZnO and AlO. In addition, the proportion of carbamate toxins increased upon exposure to 2mgL ENPs, while decreased upon exposure to 200mgL ENPs. The changes in PSTs production and composition might be an adaptive response for A. tamarense to overcome the stress of ENPs exposure. This work brings the first evidence that ENP would affect PSTs production and profiles.
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http://dx.doi.org/10.1016/j.scitotenv.2017.05.170DOI Listing
January 2018

Mechanisms underlying the acute toxicity of fullerene to Daphnia magna: Energy acquisition restriction and oxidative stress.

Water Res 2017 10 14;123:696-703. Epub 2017 Jul 14.

Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, PR China.

The toxicity of fullerene (C) to Daphnia magna has been a subject with increasing concerns. Nevertheless, the underlying mechanisms are still poorly understood. In the present study, we evaluated various aspects of the toxicological impacts of C on daphnia. After a 72-h exposure, the 50% effective concentration of C was 14.9 mg/L for immobilization, and 16.3 mg/L for mortality. Daphnia exhibited a quick uptake of C with a body burden value of 413 μg/g in wet weight in the 1 mg/L C treatment group. Transmission electron microscopy observations revealed that C had mainly accumulated in the guts of organisms. The feeding rate, gut ultra-structural alterations, and digestive enzyme activities of daphnia in response to C treatment were evaluated. The results revealed a significant reduction in the digestion and filtration rates, as well as gut impairment and inhibition of digestive enzymes (cellulose, amylase, trypsin, and β-galactosidase) activity of C exposed daphnia. In addition, the changes in superoxide dismutase (SOD) and malondialdehyde (MDA) levels in daphnia under C exposures were also discovered. These results, for the first time, provide systematic evidence that C caused a restriction in energy acquisition and increased oxidative damage in daphnia, which might be related to the bioaccumulation of C and finally led to the immobility and mortality.
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http://dx.doi.org/10.1016/j.watres.2017.07.023DOI Listing
October 2017

Effects of short-term invasion of Spartina alterniflora and the subsequent restoration of native mangroves on the soil organic carbon, nitrogen and phosphorus stock.

Chemosphere 2017 Oct 15;184:774-783. Epub 2017 Jun 15.

Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, China; Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing, 100084, China. Electronic address:

The exotic cordgrass Spartina alterniflora has severely invaded the mangrove wetlands in southern China and ecological restoration using native mangroves was conducted in an attempt to control this invasive species. In this study, the contents and pools of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) were quantified to investigate the invasive effects of S. alterniflora and then to evaluate whether the ecological restoration of native mangrove could reverse those effects. S. alterniflora only showed significantly higher organic carbon content in the surface 0-10 cm of soil than in the uninvaded mudflat. The high δC values in the surface soil of the invaded habitat demonstrated that S. alterniflora contributed 42.6-62.2% of the organic carbon. The SOC for invasive S. alterniflora and newly restored mangroves (4 years and 14 years) was not enhanced in comparison to the unvegetated mudflat. S. alterniflora significantly increased the surface soil TN content, but decreased the available phosphorus content and TP density. The TN densities increased gradually with the mangrove restoration, while the TP densities were only slightly influenced. The results suggested that short-term invasion of S. alterniflora and subsequent mangrove restoration did not alter SOC or TN pool sizes, but S. alterniflora was shown to affect the potential carbon storage capacity produced by the mangroves in the Zhangjiang Estuary.
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http://dx.doi.org/10.1016/j.chemosphere.2017.06.060DOI Listing
October 2017
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