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Jun Shi, Huiping Deng, Huichao Pan, Yinjie Xu, Min Zhang
Epigallocatechin-3-gallate (EGCG) has been shown to possess anti-inflammatory effects. Microcystin-LR (MC-LR) is a potent toxin and our past research suggested that it also mediated human umbilical vein endothelial cell (HUVEC) injury. The aim of this study was to investigate the effects of EGCG on MC-LR-induced oxidative stress and inflammatory responses in HUVECs. HUVECs were stimulated with MC-LR in the presence or absence of EGCG. MC-LR (40 μM) significantly increased cell death and decreased cell viability, migration, and tube formation, whereas EGCG (50 μM) inhibited these effects...
October 21, 2016: Chemosphere
Xueting Wang, Jie Ding, Zou Xiang, Peipei Jiang, Jing Du, Xiaodong Han
Microcystin-LR (MC-LR), which generates strong reproductive toxicity, reduces serum testosterone level without directly damaging Leydig cells. The purpose of this study was to identify the target cells of MC-LR in the rat hypothalamic-pituitary axis and to investigate the underlying mechanisms. We found that the gonadotropin-releasing hormone (GnRH) neurons were the direct target of MC-LR. In vivo results showed that upon exposure to rats, cells around the third ventricle of hypothalamus underwent apoptosis...
October 20, 2016: Toxicon: Official Journal of the International Society on Toxinology
Quan Zhang, Hang Zhou, Zhe Li, Jianqiang Zhu, Cong Zhou, Meirong Zhao
The use of glyphosate, which is a well-known sterilant herbicide, has been growing rapidly because the area under the cultivation of genetically modified crops that are tolerant to this herbicide has increased. Glyphosate can enter into aquatic systems through many different ways. However, information on the potential risks of glyphosate at environmentally relevant levels to aquatic systems is still limited. In this study, we selected the cyanobacterium Microcystis aeruginosa FACHB-905 (M. aeruginosa) as a model organism to evaluate the effects of glyphosate at environmentally relevant concentrations on the former's growth and microcystin (MC) production...
November 2016: Environmental Monitoring and Assessment
Maciej Woźny, Bogdan Lewczuk, Natalia Ziółkowska, Piotr Gomułka, Stefan Dobosz, Alicja Łakomiak, Maciej Florczyk, Paweł Brzuzan
To date, there has been no systematic approach comprehensively describing the sequence of pathological changes in fish during prolonged exposure to microcystin-LR (MC-LR). Towards this aim, juvenile whitefish individuals received an intraperitoneal injection with pure MC-LR, and the injection was repeated every week to maintain continuous exposure for 28days. During the exposure period, growth and condition of the fish were assessed based on biometric measurements. Additionally, selected biochemical markers were analysed in the fishes' blood, and their livers were carefully examined for morphological, ultrastructural, and molecular changes...
October 17, 2016: Toxicology and Applied Pharmacology
Yuan Zhou, Xiaoping Xu, Beibei Yu, Guang Yu
The intestinal epithelium is a single-cell layer that provides an important barrier against natural toxins. Microcystin-LR (MC-LR), a cyclic heptapeptide, is one of the best known toxins able to alter the functions of intestine. This study evaluated the toxic effects and the possible mechanisms of MC-LR on barrier function of the intestinal epithelial cells. Intestinal epithelial cells (IEC-6) were exposed to 0, 6.25, 12.5, 25 and 50 μM MC-LR. Cell viability significantly decreased, while the ratio of apoptotic cells increased after exposure to 12...
October 19, 2016: Environmental Toxicology
Akira Umehara, Tohru Takahashi, Tomohiro Komorita, Ryo Orita, Jin-Woo Choi, Risa Takenaka, Rie Mabuchi, Ho-Dong Park, Hiroaki Tsutsumi
Freshwater cyanobacteria produce toxic microcystins (MCs), which travel from freshwater areas into the sea. The MCs produced by cyanobacteria in a freshwater reservoir were discharged frequently into the adjacent Isahaya Bay, remained in the surface sediments, and then accumulated in various macrobenthic animals on the seafloor. The MCs were transported further outside of Isahaya Bay (Ariake Bay), and the median values of the MC contents in the sediments were in the same levels in both bays, while their temporal variations were also similar during the study period...
October 15, 2016: Chemosphere
Diane M Orihel, David W Schindler, Nathaniel C Ballard, Lindsey R Wilson, Rolf D Vinebrooke
The effects of reducing nutrient inputs to lakes and reservoirs are often delayed by hysteresis resulting from internal phosphorus (P) loading from sediments. Consequently, controlling harmful algal blooms (HABs) in many eutrophic ecosystems requires additional management to improve water quality. We manipulated iron (Fe) concentrations in a hypereutrophic lake to determine if Fe amendment would suppress HABs by inhibiting P release from sediments. Our experiment consisted of 15 in situ mesocosms, 12 of which each received a different dose of Fe (ranging from 2 to 225 g/m(2) ); the remaining three were unmanipulated to serve as controls...
July 2016: Ecological Applications: a Publication of the Ecological Society of America
Nian Wei, Lili Hu, Lirong Song, Nanqin Gan
Micocystin (MC) exists in Microcystis cells in two different forms, free and protein-bound. We examined the dynamic change in extracellular free MCs, intracellular free MCs and protein-bound MCs in both batch cultures and semi-continuous cultures, using high performance liquid chromatography and Western blot. The results showed that the free MC per cell remained constant, while the quantity of protein-bound MCs increased with the growth of Microcystis cells in both kinds of culture. Significant changes in the dominant MC-bound proteins occurred in the late exponential growth phase of batch cultures, while the dominant MC-bound proteins in semi-continuous cultures remained the same...
October 12, 2016: Toxins
J Machado, J Azevedo, M Freitas, E Pinto, A Almeida, V Vasconcelos, A Campos
Toxic cyanobacterial blooms are often observed in freshwaters and may reflect the increased eutrophication of these environments and alterations in climate. Cyanotoxins, such as microcystins (MCs), are an effective threat to many life forms, ranging from plants to humans. Despite the research conducted to date on cyanotoxins, the risks associated to the use of contaminated water in agriculture require further elucidation. To tackle this aim, a research was conducted with the root-vegetable Daucus carota. The specific aims of this work were the following: (i) to evaluate the effects of MC-LR on the plant growth and photosynthesis; (ii) to evaluate the nutritional quality of carrot roots; and (iii) to measure bioaccumulation...
October 18, 2016: Environmental Science and Pollution Research International
Yuanyuan Chen, Jian Li, Jin Wei, Atufa Kawan, Li Wang, Xuezhen Zhang
Cyanobacterial blooms and their associated toxins pose a great threat to human beings. The situation is even worse for those whose drinking water source is a cyanotoxin-polluted water body. Therefore, efficient and safe treatments urgently need to be developed. The present study verified the application of vitamin C on the inhibition of toxic Microcystis aeruginosa. Our results showed that vitamin C drove the Fenton reaction and significantly sterilized cultures of M. aeruginosa. The algicidal activity of vitamin C was dependent on its involvement in iron (Fe) metabolism...
October 6, 2016: Journal of Hazardous Materials
Miriam Fontanillo, Ivan Zemskov, Maximilian Häfner, Ulrike Uhrig, Francesca Salvi, Bernd Simon, Valentin Wittmann, Maja Köhn
Research and therapeutic targeting of the phosphoserine/threonine phosphatases PP1 and PP2A is hindered by the lack of selective inhibitors. The microcystin (MC) natural toxins target both phosphatases with equal potency, and their complex synthesis has complicated structure-activity relationship studies in the past. We report herein the synthesis and biochemical evaluation of 11 MC analogues, which was accomplished through an efficient strategy combining solid- and solution-phase approaches. Our approach led to the first MC analogue with submicromolar inhibitory potency that is strongly selective for PP2A over PP1 and does not require the complex lipophilic Adda group...
October 10, 2016: Angewandte Chemie
Hong Li, Hainan Ai, Li Kang, Xingfu Sun, Qiang He
Measures for removal of toxic harmful algal blooms often cause lysis of algal cells and release of microcystins (MCs). In this study, Acinetobacter sp. CMDB-2 that exhibiting distinct algal lysing activity and MCs degradation capability was isolated. The physiological response and morphological characteristics of toxin-producing Microcystis aeruginosa, the dynamics of intra- and extracellular MC-LR concentration were studied in an algal/bacterial co-cultured system. The results demonstrated that Acinetobacter sp...
October 6, 2016: Environmental Science & Technology
Ehsan Maghsoudi, Nathalie Fortin, Charles Greer, Christine Maynard, Antoine Pagé, Sung Vo Duy, Sébastien Sauvé, Michèle Prévost, Sarah Dorner
A bacterium capable of degrading five microcystin (MC) variants, microcystin-LR, YR, LY, LW and LF at an initial total concentration of 50 μg l(-1) in less than 16 hours was isolated from Missisquoi Bay, in the south of Quebec, Canada. Phylogenetic analysis of the 16S rRNA gene sequence identified the bacterium as Sphingopyxis sp., designated strain MB-E. It was shown that microcystin biodegradation activity was reduced at acidic and basic pH values. Even though no biodegradation occurred at pH values of 5...
October 3, 2016: Environmental Science. Processes & Impacts
J Machado, A Campos, V Vasconcelos, M Freitas
Toxic cyanobacterial blooms are recognized as an emerging environmental threat worldwide. Although microcystin-LR is the most frequently documented cyanotoxin, studies on cylindrospermopsin have been increasing due to the invasive nature of cylindrospermopsin-producing cyanobacteria. The number of studies regarding the effects of cyanotoxins on agricultural plants has increased in recent years, and it has been suggested that the presence of microcystin-LR and cylindrospermopsin in irrigation water may cause toxic effects in edible plants...
October 1, 2016: Environmental Research
Soheila Rezaitabar, Abbas Esmaili Sari, Nader Bahramifar, Zohreh Ramezanpour
This study was conducted to determine Microcystin LR concentration in the aquatic ecosystem of the Anzali wetland in Iran. Extraction and detection of MC-LR from the water and fish samples was conducted by the SPE and HPLC-UV apparatus. Our results showed that among toxic cyanobacteria, Anabaena was the dominant genera during the study period. The results indicated that MC-LR content in water ranged from 0.18 to 3.02μg/L in dissolved fraction and undetectable level to 1.13μg/L in cellular fraction, in all three seasons...
September 30, 2016: Science of the Total Environment
Shiqing Zhou, Lingjun Bu, Yanghai Yu, Xu Zou, Yansen Zhang
This study investigated the electrochemical degradation of microcystin-LR (MC-LR) using boron-doped diamond (BDD) anode and mixed metal oxides (MMO, IrO2Ta2O5/Ti) anode in different medium. In-situ electrogenerated oxidants including hydroxyl radical, active chlorine, and persulfate were confirmed in phosphate, chloride, and sulfate medium, respectively. Different from MMO anode, hydroxyl radical was observed to play a significant role in chlorine generation at BDD anode in chloride medium. Besides, BDD anode could activate sulfate electrochemically due to its high oxygen evolution potential, and MC-LR degradation rate increased with the decrease of solution pH...
December 2016: Chemosphere
Hui Huang, Chuanrui Liu, Xiaoli Fu, Shenshen Zhang, Yongjuan Xin, Yang Li, Lijian Xue, Xuemin Cheng, Huizhen Zhang
Microcystins (MCs), the secondary metabolites of blue-green algae, are ubiquitous and major cyanotoxin contaminants. Besides the hepatopancreas/liver, the reproductive system is regarded as the most important target organ for MCs. Although reactive oxygen species (ROS) have been implicated in MCs-induced reproductive toxicity, the role of MCs in this pathway remains unclear. In the present study, Sertoli cells were employed to investigate apoptotic death involved in male reproductive toxicity of microcystin-LR (MC-LR)...
2016: Frontiers in Physiology
Kennedy Uchenna Eguzozie, Vuyo Mavumengwana, Duduzile Nkosi, Eugenie Kayitesi, Emmanuella Chioma Nnabuo-Eguzozie
A study which probed the occurrence and quantitative variations hepatotoxic microcystin in a Sub Saharan drinking freshwater reservoir was carried out between November 2014 and March 2015. Results reveal the presence of MCYST-YR, MCYST-LR, MCYST-RR, MCYST-LA and MCYST-LF variants either in cells collected directly from bloom or toxic isolates cultured under laboratory conditions. Two minor microcystin congeners (MCYST-(H4)YR) and (D-Asp(3), Dha(7)) MCYST-RR) were identified, but not quantified. Variants dominance were in the order MCYST-LR > MCYST-RR > MCYST-YR > MCYST-LA > MCYST-LF across sampling sites...
September 19, 2016: Bulletin of Environmental Contamination and Toxicology
Jie Wang, Qi Liu, Jia Feng, Jun-Ping Lv, Shu-Lian Xie
Severe eutrophication and harmful cyanobacterial blooms of freshwater ecosystems is a persistent environmental topic in recent decades. Pyrogallol (polyphenol) was confirmed to exhibit one of the most intensive inhibitory effects on the Microcystis aeruginosa. In this study, the expression of genes, release of microcystins (MCs) and antioxidant system of pyrogallol on Microcystis aeruginosa TY001 were investigated. The results revealed that the expression of stress response genes (prx, ftsH, grpE and fabZ) and DNA repair genes (recA and gyrB) were up-regulated...
September 16, 2016: Ecotoxicology and Environmental Safety
Yi Zhang, Hanyu Wei, Qing Xin, Mingang Wang, Qi Wang, Qiang Wang, Yanqing Cong
A gas-liquid hybrid discharge system was applied to microcystin-LR (MC-LR) degradation. MC-LR degradation was completed after 1 min under a pulsed high voltage of 16 kV, gas-liquid interface gap of 10 mm and oxygen flow rate of 160 L/h. The Box-Behnken Design was proposed in Response Surface Methodology to evaluate the influence of pulsed high voltage, electrode distance and oxygen flow rate on MC-LR removal efficiency. Multiple regression analysis, focused on multivariable factors, was employed and a reduced cubic model was developed...
December 1, 2016: Journal of Environmental Management
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