Affiner votre recherche
Résultats 251-260 de 4,937
BDE-209 induces autophagy and apoptosis via IRE1α/Akt/mTOR signaling pathway in human umbilical vein endothelial cells Texte intégral
2019
Hou, Yun | Fu, Jiarong | Sun, Shitian | Jin, Yinchuan | Wang, Xifeng | Zhang, Lianshuang
Recently, the essentiality and fatalness of cardiovascular diseases is attracting much attention. Polybrominated diphenyl ethers (PBDEs) are persistent environmental pollutants, which could induce the toxic effect and have been implicated in the occurrence and development of cardiovascular diseases. However, it is unclear how autophagy and apoptosis induced by BDE-209 in endothelial cells are regulated. The aim of the present study was to investigate the effects of BDE-209 on human umbilical vein endothelial cells (HUVECs) and elucidate the mechanisms involved. HUVECs were treated with a wide range concentration of BDE-209 for 24 h. The appearance of autophagy was tested by the testing index such as outcomes of monodansylcadaverine (MDC) staining and lysotracker staining, observation of autophagosomes and conversion between autophagy marker light chain 3 (LC3)-I and LC3-II. Besides, the apoptotic cell rate was detected with flow cytometry. In addition, BDE-209 induced endoplasmic reticulum (ER) stress was detected by transmission electron microscopy (TEM). Our data suggest that the exposure of BDE-209 could induce autophagy, which was confirmed by MDC staining, transmission electron microscopy observation, lysotracker staining and LC3-I/LC3-II conversion. Besides, the ER stress-related inositol-requiring enzyme 1α (IRE1α)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway could be activated by reactive oxygen species (ROS) to regulate autophagy. Moreover, the apoptosis of endothelial cells was alleviated when autophagy was blocked by 3-Methyladenine (3-MA). The results demonstrated that BDE-209 could induce the production of ROS and ER stress, activate autophagy through IRE1α/AKT/mTOR signaling pathway and ultimately induce apoptosis of vascular endothelial cells. These findings indicate that exposure to PBDE is possible to be a potential risk factor for cardiovascular diseases.
Afficher plus [+] Moins [-]Synergistic interaction between effects of phenanthrene and dynamic heat stress cycles in a soil arthropod Texte intégral
2019
Dai, Wencai | Slotsbo, Stine | Damgaard, Christian | Ke, Xin | Wu, Longhua | Holmstrup, Martin
Climatic stressors and chemicals should not be treated as isolated problems since they often occur simultaneously, and their combined effects must be evaluated including their possible interactive effects. In the present study we subjected springtails (Folsomia candida) to combined exposure to phenanthrene and dynamic heat cycles in a full factorial experiment. In a microcosm experiment, we studied the population growth of springtails subjected to a range of sub-lethal concentrations of phenanthrene. During the 28-day experiment we further subjected microcosms to varying numbers of repeated dynamic heat cycles (0–5 cycles) simulating repeated heat waves. We found a synergistic interaction between the effects of phenanthrene and the number of heat waves on both body mass of adults and juvenile production of F. candida showing that the negative effects of phenanthrene were intensified when animals were heat stressed, and/or vice versa. This interaction was not related to internal concentrations of phenanthrene in adult springtails, nor was it due to altered degradation of phenanthrene in soil. We argue that both phenanthrene (by its partitioning into membrane bilayers) and heat have detrimental effects on the physical conditions of cellular membranes in a dose-dependent manner, which, under extreme circumstances, can increase membrane fluidity to a level which is sub-optimal for normal membrane functioning. We discuss the possibility that the synergistic interactions subsequently reduce life-history parameters such as growth and reproduction.
Afficher plus [+] Moins [-]Organophosphorus flame retardants in a typical freshwater food web: Bioaccumulation factors, tissue distribution, and trophic transfer Texte intégral
2019
Liu, Yin-E | Luo, Xiao-Jun | Zapata Corella, Pablo | Zeng, Yan-Hong | Mai, Bi-Xian
Water, sediment, and wild aquatic species were collected from an electronic waste (e-waste) polluted pond in South China. This study aimed to investigate the bioaccumulation, tissue distribution, and trophic transfer of organophosphorus flame retardants (PFRs) in these aquatic organisms. The concentrations of PFRs detected in the analyzed organisms were between 1.7 and 47 ng/g wet weight (ww). Oriental river prawn and snakehead exhibited the highest and lowest levels, respectively. Tri-n-butyl phosphate (TnBP), tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCPP) and triphenyl phosphate (TPhP) were dominant contaminants, accounting for approximately 86% of the total sum. The mean values of bioaccumulation factors (BCFs) and logarithmic biota-sediment accumulation factors (log BSAFs) for individual PFRs varied from 6.6 to 1109 and from −2.0 to 0.41, respectively. Both log BCFs and log BSAFs of PFRs were significantly and positively correlated with their octanol-water partitioning coefficient (log KOW). The concentrations of PFRs in tissues of large mud carp and snakehead were significantly and positively correlated with the lipid content (each p < 0.05) and the liver, kidney, and gill exhibited high PFR levels. When the concentration was expressed on a lipid basis, liver exhibited the lowest level, indicating the probable effects of metabolism. Significantly positive correlation was also found between lipid content and total PFR concentration in muscle of all aquatic organisms, given the strong correlation between lipid content and the concentration of TnBP. Trophic magnification factors (TMF) of TnBP and TPhP were lower than 1 (0.57 and 0.62), indicating that these PFRs undergo trophic dilution in this aquatic food web.
Afficher plus [+] Moins [-]Occurrence of swampy/septic odor and possible odorants in source and finished drinking water of major cities across China Texte intégral
2019
Wang, Chunmiao | Yu, Jianwei | Guo, Qingyuan | Sun, Daolin | Su, Ming | An, Wei | Zhang, Yu | Yang, Min
Swampy/septic odors are one of the most important odor types in drinking water. However, few studies have specifically focused on it compared to the extensive reported musty/earthy odor problems, even though the former is much more offensive. In this study, an investigation covering the odor characteristics, algal distribution and possible odorants contributing to swampy/septic odor, including dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), diisopropyl sulfide (DIPS), dipropyl sulfide (DPS), dibutyl sulfide (DBS), 2-methylisoborneol (2-MIB) and geosmin (GSM), was performed in source and finished water of 56 drinking water treatment plants (DWTPs) in 31 cities across China. While the musty/earthy and swampy/septic odors were dominant odor descriptors, the river source water exhibited a higher proportion of swampy/septic odor (38.5%) compared to much higher detection rate of musty/earthy odor (50.0%) in the lake/reservoir source water. The occurrence of swampy/septic odor, which was much easier to remove by conventional drinking water treatment processes compared to musty/earthy odors, was decreased by 62.9% and 46.3% in river and lake/reservoir source water respectively. Statistical analysis showed that thioethers might be responsible for the swampy/septic odor in source water (R2 = 0.75, p < 0.05). Specifically, two thioethers, DMDS and DMTS were detected, and other thioethers were not found in all water samples. DMDS was predominant with a maximum odor activity value (OAV) of 2.0 in source water and 1.3 in finished water. The distribution of the thioethers exhibited a marked regional characteristics with higher concentrations being detected in the east and south parts of China. The high concentrations of thioethers in lake/reservoir source water samples could be partly interpreted as the bloom of the cyanobacteria. This study provides basic information for swampy/septic odor occurrence in drinking water and will be helpful for further water quality management in water industry in China.
Afficher plus [+] Moins [-]Exposure to nickel oxide nanoparticles insinuates physiological, ultrastructural and oxidative damage: A life cycle study on Eisenia fetida Texte intégral
2019
Adeel, Muhammad | Ma, Chuanxin | Ullah, Sana | Rizwan, Muhammad | Hao, Yi | Chen, Chunying | Jilani, Ghulam | Shakoor, Noman | Li, Mingshu | Wang, Lihong | Tsang, Daniel C.W. | Rinklebe, Jörg | Rui, Yukui | Xing, Baoshan
Although, health and environmental hazards of Ni are ironclad; however, that of Nickle oxide nanoparticles (NiO-NPs) are still obscure. Therefore, impact of NiO-NPs exposure (0, 5, 50, 200, 500 and 1000 mg kg⁻¹ soil) on the earthworm (Eisenia fetida) survival (at 28th day), reproduction (at 56th day), histopathology, ultrastructures, antioxidant enzymes and oxidative DNA damage was appraised in full life cycle study. Lower concentrations of NiO-NPs (5, 50 and 200) did not influence the survival, reproduction and growth rate of adult worms significantly. However, reproduction reduced by 40–50% with 500 and 1000 mg kg⁻¹ exposure, which also induced oxidative stress leading to DNA damage in earthworms. Ultrastructural observation and histology of earthworms exposed to higher NiO-NPs concentrations revealed abnormalities in epithelium layer, microvilli and mitochondria with underlying pathologies of epidermis and muscles, as well as adverse effects on the gut barrier. To the best of our knowledge, this is the first study unveiling the adverse effects of NiO-NPs on a soil invertebrate (Eisenia fetida). Our findings clue towards looking extensively into the risks of NiO-NPs on soil organisms bearing agricultural and environmental significance.
Afficher plus [+] Moins [-]Validation and application of a modified QuEChERS method for extracting neonicotinoid residues from New Zealand maize field soil reveals their persistence at nominally hazardous concentrations Texte intégral
2019
Pook, Chris | Gritcan, Iana
The widespread use of neonicotinoid insecticides is controversial due to their persistence in the environment and concerns the long-term consequences of their use. We present a simple, low-cost method for the sensitive and efficient extraction of three important neonicotinoids from soil with a detection limit <1 ng g−1 wet soil. We have validated this method by applying it to uncontaminated soil samples spiked with thiamethoxam, clothianidin and imidacloprid at environmentally concentrations. Absolute recoveries were >80% for thiamethoxam, clothianidin and imidacloprid. We also applied the method to soil samples collected from maize fields in New Zealand's North Island and found imidacloprid in 43 out of 45 samples and clothianidin in every one. Mean imidacloprid concentrations varied from 0.5 to 9.4 ng g−1 (wet weight) and clothianidin from 2.1 to 26.7 ng g−1 (wet weight). Imidacloprid concentrations exceed the New Zealand Environmental Protection Agency's Environmental Exposure Limit of 1 ng g−1 (dry weight) at eight of the nine sites sampled. These results are also remarkable because we have detected multiple neonicotinoid residues at every site. Imidacloprid residues appear to persist at significant concentrations at five of our sites from an application at least two years previous. This is only the third study to report the presence of neonicotinoid residues in NZ's environment and the first to show that those residues are persistent in the environment at nominally hazardous concentrations.
Afficher plus [+] Moins [-]Bioaccumulation and metal-associated biomarker responses in a freshwater mussel, Dreissena polymorpha, following short-term platinum exposure Texte intégral
2019
Brand, Sarel J. | Erasmus, Johannes H. | Labuschagne, Marelize | Grabner, Daniel | Nachev, Milen | Zimmermann, Sonja | Wepener, V. | Smit, Nico | Sures, Bernd
Due to the increasing presence of platinum (Pt) in the environment, the caveat arises to identify its toxic potential in species at risk of being exposed – especially those found in aquatic environments where pollutants tend to accumulate. Comprehensive characterisation of possible adverse effects following exposure of aquatic organisms to Pt remains elusive. To address this, Zebra mussels (Dreissena polymorpha) were exposed to a range of Pt(IV) concentrations (0.1, 1, 10, 100 and 1000 μg/L) for one and four days, respectively, after which bioaccumulation was quantified and compared to alterations in biomarker profiles relevant to metal toxicity i.e. glutathione-S-transferase (GST) and catalase (CAT) activity, lipid peroxidation and metallothionein (MT) induction. Despite pre-conditioning of the tanks, Pt recovery in the exposure media was found to be 36% (0.1 μg/L), 42% (1 μg/L), 47% (10 μg/L), 68% (100 μg/L) and 111% (1000 μg/L) due to biological and non-biological processes. Pt concentrations in dried mussel soft tissue increased with exposure concentrations and were 20–153 times higher compared to quantified Pt concentrations in the exposure media. CAT activity was significantly increased in the tissue of mussels exposed to 0.1–100 μg/L Pt after Day 1 while the lowest effect concentration (LOC) for this response on both Day 1 and Day 4 was 0.1 μg/L. The effect on the GST activity was less pronounced but demonstrated a similar trend. However, enhanced lipid peroxidation was measured in the tissue of mussels exposed to ≥0.1 μg/L on Day 4. Bioaccumulation of Pt was also associated with a concentration-dependent increase in Pt-MT. Although these effects occurred at Pt levels higher than those present in the environment, it indicates that Pt has the ability to cause aberrancies in metal-associated biomarker profiles.
Afficher plus [+] Moins [-]Accumulation and spatial distribution of copper and nutrients in willow as affected by soil flooding: A synchrotron-based X-ray fluorescence study Texte intégral
2019
Cao, Yini | Ma, Chuanxin | Zhang, Jianfeng | Wang, Shufeng | White, Jason C. | Chen, Guangcai | Xing, Baoshan
Copper (Cu) induced phytotoxicity has become a serious environmental problem as a consequence of significant metal release through anthropogenic activity. Understanding the spatial distribution of Cu in plants such as willow is essential to elucidate the mechanisms of metal accumulation and transport in woody plants, particularly as affected by variable environment conditions such as soil flooding. Using synchrotron-based X-ray fluorescence (μ-XRF) techniques, the spatial distribution of Cu and other nutrient elements were investigated in roots and stems of Salix (S.) integra exposed to 450 mg kg⁻¹ Cu under non-flooded (NF)/flooding (F) conditions for 90 d. S. integra grown in the F condition exhibited significant higher tolerance index (TI, determined by the ratio of total biomass in Cu treatments to control) (p < 0.05) than that in the NF condition, indicating soil flooding alleviated Cu toxicity to willow plants. The μ-XRF revealed that Cu was preferentially located in the root cap and meristematic zone of the root tips. Under the NF condition, the Cu intensity in the root epidermis was more highly concentrated than that of the F condition, suggesting the soil flooding significantly inhibited Cu uptake by S. integra. The pattern of the Cu spatial distribution in the S. integra stem indicated that the F condition severely reduced Cu transport via the xylem vessels as a consequence of decreasing the transpiration rate of leaves. To our knowledge, this is the first study to report the in vivo Cu distribution in S. integra in a scenario of co-exposure to the Cu and the soil flooding over a long period. The finding that Cu uptake varies significantly with flooding condition is relevant to the development of strategies for plants to detoxify the metals and to maintain the nutrient homeostasis.
Afficher plus [+] Moins [-]Increase of apoplastic ascorbate induced by ozone is insufficient to remove the negative effects in tobacco, soybean and poplar Texte intégral
2019
Dai, Lulu | Feng, Zhaozhong | Pan, Xiaodong | Xu, Yansen | Li, Pin | Lefohn, Allen S. | Harmens, Harry | Kobayashi, Kazuhiko
Apoplastic ascorbate (ASCapo) is an important contributor to the detoxification of ozone (O3). The objective of the study is to explore whether ASCapo is stimulated by elevated O3 concentrations. The detoxification of O3 by ASCapo was quantified in tobacco (Nicotiana L), soybean (Glycine max (L.) Merr.) and poplar (Populus L), which were exposed to charcoal-filtered air (CF) and elevated O3 treatments (E-O3). ASCapo in the three species were significantly increased by E-O3 compared with the values in the filtered treatment. For all three species, E-O3 significantly increased the malondialdehyde (MDA) content and decreased light-saturated rate of photosynthesis (Asat), suggesting that high O3 has induced injury/damage to plants. E-O3 significantly increased redox state in the apoplast (redox stateapo) for all species, whereas no effect on the apoplastic dehydroascorbate (DHAapo) was observed. In leaf tissues, E-O3 significantly enhanced reduced-ascorbate (ASC) and total ascorbate (ASC+DHA) in soybean and poplar, but significantly reduced these in tobacco, indicating different antioxidative capacity to the high O3 levels among the three species. Total antioxidant capacity in the apoplast (TACapo) was significantly increased by E-O3 in tobacco and poplar, but leaf tissue TAC was significantly enhanced only in tobacco. Leaf tissue superoxide anion (O2•-) in poplar and hydrogen peroxide (H2O2) in tobacco and soybean were significantly increased by E-O3. The diurnal variation of ASCapo, with maximum values occurring in the late morning and lower values experienced in the afternoon, appeared to play an important role in the harmful effects of O3 on tobacco, soybean and poplar.
Afficher plus [+] Moins [-]Biosorption of Rhodamine B onto novel biosorbents from Kappaphycus alvarezii, Gracilaria salicornia and Gracilaria edulis Texte intégral
2019
Selvakumar, A. | Rangabhashiyam, S.
In the present investigation seaweeds of macroalgae like Kappaphycus alvarezii, Gracilaria salicornia and Gracilaria edulis used as novel biosorbent in native (KA, GS, GE) and ethanol modified (EKA, EGS, EGE) for Rhodamine B (RB) removal from aqueous solution in batch process. Effect of various biosorption parameters such as pH, initial concentration of RB, biosorbent dosage and contact time were studied. The maximum biosorption capacity determined as 9.84 (KA), 11.03 (GS), 8.96 (GE), 112.35 (EKA), 105.26 (EGS) and 97.08 mg/g (EGE), respectively towards the removal of RB from aqueous solutions. Better removal of RB was observed using EKA, EGS, and EGE biosorbents at 2.0 pH. The characterizations of the biosorbents were performed using Scanning Electron microscope and Fourier Transform Infrared Spectroscopy. Biosorption equilibrium data evaluated using Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Jovanovic isotherm model. The Langmuir isotherm model best suited the equilibrium data for all the biosorbents studied. The rate of RB removal subjected to kinetic analysis using pseudo-first-order, pseudo-second-order, intra-particle diffusion and Elovich models. Pseudo-second-order kinetic model better described the experimental data of the RB biosorption. Desorption studies performed using 0.1 M sodium hydroxide as eluting agents for regeneration and recycle analysis. The recyclability of the six biosorbents showed consistent biosorption capacity towards RB removal up to the entire three cycles. The studied biosorbents sourced from large volume and easily available, further biosorption performance indicated that the KA, GS, GE, EKA, EGS and EGE could be used as efficient, alternative and eco-friendly biosorbents for the removal of harmful dyes in the environment.
Afficher plus [+] Moins [-]