7,095 research outputs found
Fast removal of cyanobacterial toxin microcystin-LR by a low-cytotoxic microgel-Fe(III) complex
No full textEutrophication has become a serious environmental threat throughout the world. In particular, the presence of cyanobacteria toxins, especially microcystins (MCs), has become a severe problem. Inhibition of Microcystis growth in water resources is the most effective way to reduce MCs, but it is a long-term investment. In the present study, a microgel-Fe(III) complex was developed for the fast removal of MC-LR. The microgel-Fe(III) characteristics and the MC-LR removal dynamics in Milli-Q water and natural water were evaluated. The removal efficiency negatively correlated to the initial MC-LR concentration and pH value (2.0-11.5), but the kinetics was not significantly influenced. The presence of natural organic matter (NOM) in water slightly reduced MC-LR removal using microgel-Fe(III). In addition, microgel-Fe(III) removed 98.99% of MC-LR in 12 min, while for activated carbon, it took 15-24 h to reach equilibrium. Furthermore, methanol was found to regenerate the microgel-Fe(III) after MC-LR removal for at least five regeneration cycles. Finally, the microgel-Fe(III) material was made into a membrane so that MCs could be removed by filtration. Therefore, microgel-Fe(III) is an effective technology and has a great potential in removing MC-LR from drinking water resources. (C) 2011 Elsevier Ltd. All rights reserved.Eutrophication has become a serious environmental threat throughout the world. In particular, the presence of cyanobacteria toxins, especially microcystins (MCs), has become a severe problem. Inhibition of Microcystis growth in water resources is the most effective way to reduce MCs, but it is a long-term investment. In the present study, a microgel-Fe(III) complex was developed for the fast removal of MC-LR. The microgel-Fe(III) characteristics and the MC-LR removal dynamics in Milli-Q water and natural water were evaluated. The removal efficiency negatively correlated to the initial MC-LR concentration and pH value (2.0-11.5), but the kinetics was not significantly influenced. The presence of natural organic matter (NOM) in water slightly reduced MC-LR removal using microgel-Fe(III). In addition, microgel-Fe(III) removed 98.99% of MC-LR in 12 min, while for activated carbon, it took 15-24 h to reach equilibrium. Furthermore, methanol was found to regenerate the microgel-Fe(III) after MC-LR removal for at least five regeneration cycles. Finally, the microgel-Fe(III) material was made into a membrane so that MCs could be removed by filtration. Therefore, microgel-Fe(III) is an effective technology and has a great potential in removing MC-LR from drinking water resources. (C) 2011 Elsevier Ltd. All rights reserved
Sulforaphane prevents microcystin-LR-induced oxidative damage and apoptosis in BALB/c mice
No full textMicrocystins (MCs), the products of blooming algae Microcystis, are waterborne environmental toxins that have been implicated in the development of liver cancer, necrosis, and even fatal intrahepatic bleeding. Alternative protective approaches in addition to complete removal of MCs in drinking water are urgently needed. In our previous work, we found that sulforaphane (SFN) protects against microcystin-LR (MC-LR)-induced cytotoxicity by activating the NF-E2-related factor 2 (Nrf2)-mediated defensive response in human hepatoma (HepG2) and NIH 3T3 cells. The purpose of this study was to investigate and confirm efficacy the SFN-induced multi-mechanistic defense system against MC-induced hepatotoxicity in an animal model. We report that SFN protected against MC-LR-induced liver damage and animal death at a nontoxic and physiologically relevant dose in BALB/c mice. The protection by SFN included activities of anti-cytochrome P450 induction, anti-oxidation, anti-inflammation, and anti-apoptosis. Our results suggest that SFN may protect mice against MC-induced hepatotoxicity. This raises the possibility of a similar protective effect in human populations, particularly in developing countries where freshwaters are polluted by blooming algae. (C) 2011 Elsevier Inc. All rights reserved
The role of Ruditapes philippinarum glutathione transferases in the metabolism of microcystin-LR
No full textNo abstracts are to be cited without prior reference to the author. Glutathione transferases (GSTs) are phase II enzymes involved in the microcystin (MC) induced detoxication processes. In this study we analyze and compare the metabolism of MC-LR by the cytosolic GSTs from gills and hepatopancreas of Ruditapes philippinarum. Cytosolic GSTs were purified by glutathione (GSH)–agarose affinity chromatography from exposed and non-exposed bivalves to MC-LR (100 µg/L) representing the inducible and constitutive (Basal) GST fractions, respectively. For each mixture, we examined the in vitro cytosolic GST inhibition efficiency of the conjugation of CDNB to GSH by MC-LR and characterize the inhibition mechanism. Results support the important role of GST enzymes in detoxification of MCs in bivalve mollusk
Gap-Tethered Au@AgAu Raman Tags for the Ratiometric Detection of MC-LR
No full textEstablishing a simple
and accurate assay for detecting Microcystin-LR
(MC-LR) is of significant important for the environment and human
health. Herein, we develop a ratiometric surface-enhanced Raman scattering
(SERS) aptasensor based on internal standard (IS) methods for the
sensitive and reproducible quantitative detection of MC-LR. Gap-tethered
SERS-active Au@AgAu nanoparticles (NPs) are successfully prepared
and the gap sizes are adjustable by simply adjusting the acidity.
Gap-tethered Au@AgAu NPs exhibit gap-tunable amplified SERS activity
and are served as SERS tags. The graphene oxide (GO)/Fe3O4 NPs demonstrate a unique and stable Raman band from
the graphitic component, making them an ideal IS for quantitative
Raman analysis. In principle, Au@gap@AgAu NPs are assembled with GO/Fe3O4 NPs depending on the π–π
stacking interaction between GO and MC-LR aptamers. In the presence
of MC-LR, Au@gap@AgAu NPs are dissociated from GO/Fe3O4 NPs due to the affinity of aptamer, leading to the changes
of Raman intensity of SERS tags. Quantitatively, upon correction by
the IS Raman signals, the limit of detection (LOD) is as low as 9.82
pM for MC-LR. The developed protocol provides a simple and rapid approach
for the sensitive and quantitative detection of MC-LR and shows great
promise for applications in complex systems
Transcriptional responses of glutathione transferase genes in Ruditapes philippinarum exposed to microcystin-LR
No full textNo abstracts are to be cited without prior reference to the author. Microcystins (MCs) are potent hepatotoxins produced by bloom-forming species of toxic cyanobacteria. Among these, MC-LR is the most commonly found and toxic variant. Bivalves, due to their benthic and sedentary mode of life, are one of the most threatened organisms by these environmental stressors. Glutathione transferases (GSTs) play a major role in cellular defense against MCs toxicity. The aim of this study was to compare the relative changes of gene expression of the different GSTs isoforms in mollusc bivalves exposed to MCs. The time-dependent changes of relative transcription abundance of several GST isoforms in parallel with enzymatic activity of total GST were investigated in gills and hepatopancreas of Ruditapes philippinarum exposed to dissolved MC-LR. The relative changes of gene expression and enzyme activity were analyzed by quantitative real-time PCR and colorimetric assays respectively. We found that MC-LR could affect the transcriptional activities of these detoxification enzymes in gills and hepatopancreas of the tested bivalves. Most GST isoforms showed differential response profiles depending on the concentrations of MC-LR and exposure times for clams. These results highlight the important role of GSTs in counteracting the potential deleterious effects induced by MCs in bivalve
The toxic effects of microcystin-LR on embryo-larval and juvenile development of loach, Misguruns mizolepis Gunthe
No full textMicrocystin-LR, a specific and potent hepatotoxin, was tested for its effects oil loach embryo-larval and juvenile development, The results of this study showed that loach embryos were more sensitive when exposed to microcystin-LR at a later than at an earlier stage of development, Juveniles were far less sensitive to MC-LR than were embryos and larvae. Mortality and developmental abnormality were proven to be dose-dependent and to be stage-specific sensitive. Among the abnormal changes noted were: pericardial edema and tubular heart, bradycardia, homeostasis, poor yolk resumption. small head, curved body and tail, and abnormal hatching, Liver and heart were the main targets of microcystin-LR toxicity. Ultrastructural analysis documented a complex set of sublethal effects of microcystin-LR on loach hepatocytes, chiefly including morphological alteration in nuclear and RER of loach liver cells. fit addition, microcystin-LR was lethal to loach juvenile in the subacute (7 days) exposure (LC50) = 593.3 mug/l). (C) 2002 Elsevier Science Ltd. All rights reserved
Lr-Stream: Using latency and resource aware scheduling to improve latency and throughput for streaming applications
No full textLr-Stream: Using latency and resource aware scheduling to improve latency and throughput for streaming application
Responses of antioxidant systems in the hepatocytes of common carp (Cyprinus carpio L.) to the toxicity of microcystin-LR
No full textThe freshwater, bloom-forming cyanobacterium (blue-green alga) Microcystis aeruginosa produces a peptide hepatotoxin, which causes the damage of animal liver. Recently, toxic Microcystis blooms frequently occur in the eutrophic Dianchi Lake (300 km(2) and located in the South-Westem of China). Microcystin-LR from Microcystis in Dianchi was isolated and purified by high performance liquid chromatography (HPLC) and its toxicity to mouse and fish liver was studied (Li et al., 2001). In this study, six biochemical parameters (reactive oxygen species, glutathione, superoxide dismutase, catalase, glutathione peroxide and glutathione S-transferase) were determined in common carp hepatocytes when the cells were exposed to 10 mug microcystin-LR per litre. The results showed that reactive oxygen species (ROS) contents increased by more than one-time compared with the control after 6 h exposure to the toxin. In contrast, glutathione (GSH) levels in the hepatocytes exposed to microcystin-LR decreased by 47% compared with the control. The activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxide (GSH-Px) increased significantly after 6 h exposure to microcystin-LR, but glutathione S-transferase (GST) activity showed no difference from the control. These results suggested that the toxicity of microcystin-LR caused the increase of ROS contents and the depletion of GSH in hepatocytes exposed to the toxin and these changes led to oxidant shock in hepatocytes. Increases of SOD, CAT and GSH-Px activities revealed that these three kinds of antioxidant enzymes might play important roles in eliminating the excessive ROS. This paper also examined the possible toxicity mechanism of microcystin-LR on the fish hepatocytes and the results were similar to those with mouse hepatocytes. (C) 2003 Elsevier Science Ltd. All rights reserved
Effects of microcystin-LR on the growth and antioxidant systems in Aphanizomenon sp DC01 cells
No full textTo investigate the toxic effects of microcystin (MC) on microalgae cells and elucidate the mechanism of cell death and responses of antioxidant systems in microalgae to oxidative stress induced by MC from the perspective of reactive oxygen species (ROS), the changes of cell growth, ROS production and antioxidant systems in the cells were determined using 50 mu g . L-1 and 500 mu g . L-1 MC-LR to treat Aphanizomenon sp. DC01 cells. Results showed that 50 mu g . L-1 MC-LR had no significant effects on the growth of Aphanizomenon sp. DCO1 while 500 mu g . L-1 MC-LR induced cell death of Aphanizomenon sp. DC01. The ROS content in 50 mu g . L-1 MC-LR treated cells was significantly higher than that in the control group after 2 days toxin exposure, but Aphanizomenon cells could rehabilitate the oxidative injury through changes of glutathione (GSH) content and superoxide dismutase(SOD), glutathione peroxidas (GPX) activities. ROS content recovered to the control level after 3 days. 500 mu g-L-1 MC-LR treat significantly decreased GSH content and SOD, GPX activities, and induced the excessive production of ROS in Aphanizomenon cells. ROS production burst after 4d toxin exposure, causing lipid peroxidation of Aphanizomenon cells, which led to cell death at last
Incremental Scannerless Generalized LR Parsing
No full textThe Scannerless Generalized LR (SGLR) parsing algorithm supports the development of composed languages seamlessly but does not support incremental parsing. The Incremental Generalized LR (IGLR) parsing algorithm, on the other hand, does not support the seamless composition of languages. This thesis presents the Incremental Scannerless Generalized LR (ISGLR) parsing algorithm and investigates the effects of combining the SGLR and IGLR parsing algorithms. While the algorithmic differences are orthogonal, the fact that scannerless parsing relies on non-deterministic parsing for disambiguation has a negative impact on incrementality. Nonetheless, we show that the ISGLR parsing algorithm performs better than the batch SGLR parsing algorithm in typical scenarios. On average, the ISGLR parser can reuse 99% of a previous parse result. When parsing from scratch, the ISGLR parser has a 24% run time overhead compared to the SGLR parser, but when parsing incrementally for changes that are smaller than 1% of the input size on average, it has a 9× speedup.Successor of https://doi.org/10.1145/3359061.3361085Computer Scienc
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