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https://www.readbyqxmd.com/read/28634756/a-high-throughput-targeted-and-non-targeted-method-for-the-analysis-of-microcystins-and-anatoxin-a-using-on-line-solid-phase-extraction-coupled-to-liquid-chromatography-quadrupole-time-of-flight-high-resolution-mass-spectrometry
#1
Xavier Ortiz, Eva Korenkova, Karl J Jobst, Karen A MacPherson, Eric J Reiner
Microcystins are cyclic heptapeptide hepatotoxins produced by cyanobacteria in freshwater. Sample preparation for the analysis of these cyanotoxins in water from algal blooms can take up to several days due to the matrix complexity and the low detection limits required to comply with current legislation. Moreover, there is a large number of unknown microcystins that could potentially exist in the environment resulting from different amino acid substitutions into the microcystin skeletal structure. To tackle these problems, the present study involved the development of a high throughput method based on on-line solid phase extraction coupled to liquid chromatography that could provide quantitative results for 12 microcystin variants (LR, YR, RR, HtyR, HilR, WR, LW, LA, LF, LY, Dha(7)-LR, and Dha(7)-RR) and anatoxin-A in less than 3 h with detection limits between 0...
June 20, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28634476/changes-in-n-p-supply-ratios-affect-the-ecological-stoichiometry-of-a-toxic-cyanobacterium-and-its-fungal-parasite
#2
Thijs Frenken, Joren Wierenga, Alena S Gsell, Ellen van Donk, Thomas Rohrlack, Dedmer B Van de Waal
Human activities have dramatically altered nutrient fluxes from the landscape into receiving waters. As a result, not only the concentration of nutrients in surface waters has increased, but also their elemental ratios have changed. Such shifts in resource supply ratios will alter autotroph stoichiometry, which may in turn have consequences for higher trophic levels, including parasites. Here, we hypothesize that parasite elemental composition will follow changes in the stoichiometry of its host, and that its reproductive success will decrease with host nutrient limitation...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28623299/integrated-optical-waveguide-based-fluorescent-immunosensor-for-fast-and-sensitive-detection-of-microcystin-lr-in-lakes-optimization-and-analysis
#3
Lanhua Liu, Xiaohong Zhou, James S Wilkinson, Ping Hua, Baodong Song, Hanchang Shi
Nowadays, biosensor technologies which can detect various contaminants in water quickly and cost-effectively are in great demand. Herein, we report an integrated channel waveguide-based fluorescent immunosensor with the ability to detect a maximum of 32 contaminants rapidly and simultaneously. In particular, we use waveguide tapers to improve the efficiency of excitation and collection of fluorescent signals in the presence of fluorophore photobleaching in a solid surface bioassay. Under the optimized waveguide geometry, this is the first demonstration of using such a type of waveguide immunosensor for the detection of microcystin-LR (MC-LR) in lake water...
June 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28606991/caspase-digestion-resistant-homozygous-keratin-18-mutation-protects-mouse-liver-from-apoptosis-and-injury
#4
Han-Na Yoon, Sung Yeon Yoon, Jin Hyuck Hong, Nam-On Ku
Cytoskeletal keratin 18 (K18) undergoes caspase-mediated digestion during apoptosis, which leads to dramatic keratin filament disassembly. We studied the significance of K18 caspase digestion in a mouse model. We generated transgenic mice expressing human K18 caspase digestion-resistant double-mutant, K18-D238/397E, in mouse (m) K18-null background, and compared their response to Fas-mediated injury. Notably, K18-D238/397E;mK18-null mice were significantly more resistant to Fas-induced injury as compared with K18-WT;mK18-null mice (23% vs 57% lethality, respectively; p<0...
June 12, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28605328/characterization-of-microcystin-induced-dualistic-toxic-effects-on-primary-rat-hepatocytes
#5
Yi Shuai, Dan Lou, Jianxun Yin, Xiaolan Qian, Yanqin Wang, Xinyu Hong, Ping Xiao, Weijian Zhong
Microcystins (MCs) comprise a group of widely characterized cyclic heptapeptides able to induce a series of liver injuries, including acute liver failure and primary liver cancer. Although the dualistic effects of MCs have been postulated, the specific action mode according to the exposure dosage of MCs remains unknown. In the present study, primarily cultured rat hepatocytes were used to systematically investigate hepatotoxic characteristics of MC-LR (one of the most abundant and toxic MCs variants). Results showed that the dualistic toxicity of MC-LR on hepatocytes is dose dependent...
2017: Journal of Environmental Pathology, Toxicology and Oncology
https://www.readbyqxmd.com/read/28602256/rise-and-fall-of-toxic-benthic-freshwater-cyanobacteria-anabaena-spp-in-the-eel-river-buoyancy-and-dispersal
#6
Keith Bouma-Gregson, Mary E Power, Myriam Bormans
Benthic cyanobacteria in rivers produce cyanotoxins and affect aquatic food webs, but knowledge of their ecology lags behind planktonic cyanobacteria. The buoyancy of benthic Anabaena spp. mats was studied to understand implications for Anabaena dispersal in the Eel River, California. Field experiments were used to investigate the effects of oxygen bubble production and dissolution on the buoyancy of Anabaena dominated benthic mats in response to light exposure. Samples of Anabaena dominated mats were harvested from the South Fork Eel River and placed in settling columns to measure floating and sinking velocities, or deployed into in situ ambient and low light treatments to measure the effect of light on flotation...
June 2017: Harmful Algae
https://www.readbyqxmd.com/read/28602249/ten-year-survey-of-cyanobacterial-blooms-in-ohio-s-waterbodies-using-satellite-remote-sensing
#7
Tyler Gorham, Yuanyuan Jia, C K Shum, Jiyoung Lee
Cyanobacterial blooms are on the rise globally and are capable of adversely impacting human, animal, and ecosystem health. Blooms dominated by cyanobacteria species capable of toxin-production are commonly observed in eutrophic freshwater. The presence of cyanobacterial blooms in selected Ohio lakes, such as Lake Erie and Grand Lake St. Marys, has been well studied, but much less is known about the geographic distribution of these blooms across all of Ohio's waterbodies. We examined the geographic distribution of cyanobacterial blooms in Ohio's waterbodies from 2002 to 2011, using a nested semi-empirical algorithm and remotely sensed data from the Medium Resolution Imaging Spectrometer (MERIS) onboard the European Space Agency's Envisat...
June 2017: Harmful Algae
https://www.readbyqxmd.com/read/28602183/analysis-of-trace-microcystins-in-vegetables-using-matrix-solid-phase-dispersion-followed-by-high-performance-liquid-chromatography-triple-quadrupole-mass-spectrometry-detection
#8
Zong-Yao Qian, Zhi-Gang Li, Jian Ma, Ting-Ting Gong, Qi-Ming Xian
A selective and sensitive method for the simultaneous determination of five common microcystins (MC-LR, -RR, -YR, -LW, -LF) in various vegetables was established using Matrix Solid-Phase Dispersion (MSPD) followed by high performance liquid chromatography-mass spectrometry detection. To optimize the pretreatment procedure for extracting the microcystins from three vegetable matrices (tomato, cucumber and spinacia, which represented different colors), Box-Behnken design was employed to optimize the main factors affecting the extraction efficiency, including sample/dispersant mass ratio, as well as the proportion mixture dispersant and the volumes of solvent...
October 1, 2017: Talanta
https://www.readbyqxmd.com/read/28599070/serum-microcystins-level-positively-linked-with-risk-of-hepatocellular-carcinoma-a-case-control-study-in-southwest-china
#9
Chuanfen Zheng, Hui Zeng, Hui Lin, Jia Wang, Xiaobin Feng, Zhiqun Qiu, Ji-An Chen, Jiaohua Luo, Yang Luo, Yujing Huang, Lingqiao Wang, Wenyi Liu, Yao Tan, Anwei Xu, Yuan Yao, Weiqun Shu
Microcystins have been reported carcinogenic by animal and cell experimentation, but there were no data on the linkage between serum microcystins and hepatocellular carcinoma (HCC) risk in human. We conducted a clinical case-control study to investigate the association between serum microcystins and HCC risk after controlling several known risk factors, such as hepatitis B virus (HBV), alcohol, and aflatoxin. From December 2013 to May 2016, 214 patients newly diagnosed with HCC, along with 214 controls (frequency-matched by age and sex) were recruited from three hospitals in Chongqing, Southwest China...
June 9, 2017: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
https://www.readbyqxmd.com/read/28597371/uptake-and-biotransformation-of-pure-commercial-microcystin-lr-versus-microcystin-lr-from-a-natural-cyanobacterial-bloom-extract-in-the-aquatic-fungus-mucor-hiemalis
#10
Maranda Esterhuizen-Londt, Stefanie Hertel, Stephan Pflugmacher
OBJECTIVES: To evaluate the remediation efficiency of Mucor hiemalis by comparing media elimination, uptake, and biotransformation of microcystin-LR with exposure to pure toxin versus a crude bloom extract. RESULTS: With exposure to the extract, the elimination rate of microcystin-LR from the media, which was 0.28 ng MC-LR l(-1) h(-1), was significantly higher compared to that achieved with exposure to the pure toxin (0.16 ng MC-LR l(-1) h(-1)) after 24 h...
June 8, 2017: Biotechnology Letters
https://www.readbyqxmd.com/read/28595008/rapid-and-convenient-oxidative-release-of-thiol-conjugated-forms-of-microcystins-for-chemical-analysis
#11
Christopher O Miles
Microcystins are potent cyclic heptapeptide toxins found in some cyanobacteria, and usually contain an α,β-unsaturated carbonyl group that is readily conjugated to thiol-containing amino acids, peptides and proteins in vivo and in vitro. Methods for deconjugating these types of adducts have recently been reported, but the reactions are slow or result in derivatized microcystins. Mercaptoethanol derivatives of a range of microcystins were therefore used as model compounds to develop deconjugation procedures in which the dialkyl sulfide linkage was oxidized to a sulfoxide or sulfone that, when treated with base, rapidly eliminated the adducted thiol as its sulfenate or sulfinate via β-elimination to afford free microcystins with the α,β-unsaturated carbonyl group intact...
June 8, 2017: Chemical Research in Toxicology
https://www.readbyqxmd.com/read/28586656/heterologous-expression-of-mlra-gene-originated-from-novosphingobium-sp-thn1-to-degrade-microcystin-rr-and-identify-the-first-step-involved-in-degradation-pathway
#12
Ruiping Wang, Jieming Li, Yongguang Jiang, Zhijiang Lu, Renhui Li, Ji Li
Information on the catalytic role of mlrA gene-encoded enzyme (MlrA) in microcystin-RR (MC-RR) biodegradation was limited. This study succeeded in expressing mlrA homolog of Novosphingobium sp. THN1 in heterologous host for the first time, by constructing a recombinant bacterium. Mass spectrometric analysis showed that the recombinant MlrA hydrolyzed MC-RR into linear intermediate product by cleaving the peptide bond between Adda and arginine residue, greatly detoxifying MC-RR. This finding clearly manifested that the MlrA homolog of THN1 strain possesses its original catalytic function, and ring-opening constituted the first step in MC-RR biodegradation pathway of THN1 strain...
May 17, 2017: Chemosphere
https://www.readbyqxmd.com/read/28570054/directing-the-heterologous-production-of-specific-cyanobacterial-toxin-variants
#13
Tianzhe Liu, Rabia Mazmouz, Sarah E Ongley, Rocky Chau, Russell Pickford, Jason N Woodhouse, Brett A Neilan
Microcystins are globally the most commonly occurring freshwater cyanotoxins, causing acute poisoning and chronically inducing hepatocellular carcinoma. However, the detection and toxicological study of microcystins is hampered by the limited availability and high cost of pure toxin standards. Biosynthesis of microcystin variants in a fast-growing heterologous host offers a promising method of achieving reliable and economically viable alternative to isolating toxin from slow-growing cyanobacterial cultures...
June 7, 2017: ACS Chemical Biology
https://www.readbyqxmd.com/read/28561562/using-national-scale-data-to-develop-nutrient-microcystin-relationships-that-guide-management-decisions
#14
Lester L Yuan, Amina I Pollard
Quantitative models that predict cyanotoxin concentrations in lakes and reservoirs from nutrient concentrations would facilitate management of these resources for recreation and as sources of drinking water. Development of these models from field data has been hampered by the high proportion of samples in which cyanotoxin concentrations are below detection limits and by the high variability of cyanotoxin concentrations within individual lakes. Here, we describe a national-scale hierarchical Bayesian model that addresses these issues and that predicts microcystin concentrations from summer mean total nitrogen and total phosphorus concentrations...
June 12, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28551208/dualistic-immunomodulation-of-sub-chronic-microcystin-lr-exposure-on-the-innate-immune-defense-system-in-male-zebrafish
#15
Wang Lin, Jie Hou, Honghui Guo, Yuming Qiu, Li Li, Dapeng Li, Rong Tang
Microcystins (MCs), produced by toxic cyanobacterial blooms that appeared world wildly in eutrophication waters, have often caused fish illness and even massive death cases. Among at least 90 structural variants, microcystin-LR (MC-LR) is the most common and toxic variant. In order to better understand innate immune responses in fish disrupted by environmental concentrations of MC-LR, male zebrafish (Danio rerio) were exposed to 0, 0.3, 1, 3, 10 and 30 μg/L MC-LR for 30 d, and the changes in splenic pathology and immunological gene expression as well as serum immune parameters were studied...
May 16, 2017: Chemosphere
https://www.readbyqxmd.com/read/28550806/lettuce-facing-microcystins-rich-irrigation-water-at-different-developmental-stages-effects-on-plant-performance-and-microcystins-bioaccumulation
#16
Efi Levizou, George Statiris, Theodoti Papadimitriou, Chrysi S Laspidou, Konstantinos Ar Kormas
This study investigated the microcystins (MCs)-rich irrigation water effect on lettuce of different developmental stages, i.e. during a two months period, covering the whole period from seed germination to harvest at marketable size of the plant. We followed four lettuce plant groups receiving MCs-rich water (1.81μgl(-1) of dissolved MCs), originating from the Karla Reservoir, central Greece: 1) from seeds, 2) the cotyledon, 3) two true leaves and 4) four true leaves stages, all of which were compared to control plants that received tap water...
May 24, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28549370/assessment-of-the-influence-of-key-abiotic-factors-on-the-alternative-microcystin-degradation-pathway-s-mlr-a-detailed-comparison-with-the-mlr-route-mlr
#17
Jesús Morón-López, Lucía Nieto-Reyes, Rehab El-Shehawy
Cyanobacterial proliferation and toxin production in water bodies around the world have led to global concern about the control of these issues. Indigenous bacteria have been shown to degrade the cyanotoxin microcystin (MC) in natural environments. The mlr cluster has been widely used as a marker for microcystin biodegradation; however, recent studies have shown that alternative pathway(s) also contribute to the natural removal of MCs in the ecosystem. The main objective of this study is to provide initial insights concerning how key abiotic factors affect the rate of MC biodegradation via alternative pathway(s) and to provide a detailed comparison with the mlr(+) pathway...
December 1, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28545227/potential-use-of-chemoprotectants-against-the-toxic-effects-of-cyanotoxins-a-review
#18
REVIEW
Remedios Guzmán-Guillén, María Puerto, Daniel Gutiérrez-Praena, Ana I Prieto, Silvia Pichardo, Ángeles Jos, Alexandre Campos, Vitor Vasconcelos, Ana M Cameán
Cyanobacterial toxins, particularly microcystins (MCs) and cylindrospermopsin (CYN), are responsible for toxic effects in humans and wildlife. In order to counteract or prevent their toxicity, various strategies have been followed, such as the potential application of chemoprotectants. A review of the main substances evaluated for this aim, as well as the doses and their influence on cyanotoxin-induced toxicity, has been performed. A search of the literature shows that research on MCs is much more abundant than research on CYN...
May 23, 2017: Toxins
https://www.readbyqxmd.com/read/28545210/response-of-microcystis-aeruginosa-bccusp-232-to-barley-hordeum-vulgare-l-straw-degradation-extract-and-fractions
#19
Gustavo Franciscatti Mecina, Anne Lígia Dokkedal, Luiz Leonardo Saldanha, Mathias Ahii Chia, Micheline Kézia Cordeiro-Araújo, Maria do Carmo Bittencourt-Oliveira, Regildo Márcio Gonçalves da Silva
The eutrophication of aquatic ecosystems is a serious environmental problem that leads to increased frequency of cyanobacterial blooms and concentrations of cyanotoxins. These changes in aquatic chemistry can negatively affect animal and human health. Environment-friendly methods are needed to control bloom forming cyanobacteria. We investigated the effect of Hordeum vulgare L. (barley) straw degradation extract and its fractions on the growth, oxidative stress, antioxidant enzyme activities, and microcystins content of Microcystis aeruginosa (Kützing) Kützing BCCUSP232...
December 1, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28535436/microcystin-lr-induces-changes-in-the-gaba-neurotransmitter-system-of-zebrafish
#20
Wei Yan, Li Li, Guangyu Li, Sujuan Zhao
It has been reported that exposure to microcystins altered adult zebrafish swimming performance parameters, but the possible mechanisms of action remain unknown. Neuronal activity depends on the balance between the number of excitatory and inhibitory processes which are associated with neurotransmitters. In the present study, zebrafish embryos (5 d post-fertilization) were exposed to 0, 0.3, 3 and 30μg/L (microcystin-LR) MCLR for 90day until reaching sexual maturity. To investigate the effects of MCLR on the neurotransmitter system, mRNA levels involved in amino acid g-aminobutyric acid (GABA) and glutamate metabolic pathways were tested using quantitative real-time PCR...
May 15, 2017: Aquatic Toxicology
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