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Michael R Moore - One of the best experts on this subject based on the ideXlab platform.
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Comparative toxicity of the cyanobacterial toxin, Cylindrospermopsin between mice and cattle: Human implications
2020Co-Authors: Glendon Reginald Shaw, Geoff Eaglesham, Ross A. Mckenzie, W. A. Wickramasinghe, Alan A. Seawright, Michael R MooreAbstract:The cyanobacterial toxin Cylindrospermopsin is produced by Cylindrospermopsis raciborskii and Aphanizomenon ovalisporum in many parts of the world. A human poisoning incident occurring at Palm Island, Queensland, Australia in 1979 was subsequently ascribed to Cylindrospermopsin. The structure of Cylindrospermopsin, a tricyclic guanidinium moiety bridged to hydroxymethyluracil, was deduced in 1992. A number of studies have investigated the acute toxicity of Cylindrospermopsin in mice. It is primarily a hepatotoxin with a 24-hour acute intraperitoneal (IP) LD50 of 2 mg/kg, a 5-day acute i.p. LD50 of 0.2 mg/kg and a 5-day acute oral LD50 of approximately 6 mg/kg. A human health risk assessment using data from longer-term oral dosing studies suggests a guideline value for Cylindrospermopsin in drinking water of approximately 10 μg/L.We have recently studied cattle poisonings by Cylindrospermopsin and detected the toxin in a number of tissues after necropsy. Concentrations of 1 mg/L or above in drinking water (dose is approximately 50 μg/kg/day) were shown to result in cattle death after short-term exposure (less than 10 days). Oral dosing of mice at levels up to 5 mg/L with Cylindrospermopsin in drinking water for 90 days did not produce any significant toxicity. Human health risk assessment based on cattle however, which are much more sensitive to Cylindrospermopsin than rodents, would produce a guideline for human drinking water of approximately 0.05 μg/L. A consideration of reported human poisoning incidents that implicate Cylindrospermopsin suggests that humans may also be more sensitive than rodents to this toxin.
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Hepatic xenobiotic metabolism of Cylindrospermopsin in vivo in the mouse
Toxicon, 2002Co-Authors: Ross Norris, P. Senogles, Glendon Reginald Shaw, M.j. Smith, Robyn K. Chiswell, Geoff Eaglesham, A A Seawright, Michael R MooreAbstract:Cylindrospermopsin (CYN) is a hepatotoxin isolated from the blue-green alga Cylindrospermopsis raciborskii. The role of both glutathione (GSH) and the cytochrome P450 enzyme system (P450) in the mechanism of toxicity of CYN has been previously investigated in in vitro systems. We have investigated the role of GSH and P450 in vivo in mice. Mice pre-treated with buthionine sulphoximine and diethyl maleate to deplete hepatic GSH prior to dosing with 0.2 mg/kg CYN showed a seven-day survival rate of 5/13 while the control group rate was 9/14. Dosing mice with 0.2 mg/kg CYN produced a small decrease in hepatic GSH with a characteristic rebound effect at 24 h, The magnitude of this effect is however small and combined with the non-significant difference in survival rates after GSH depletion suggest depletion of GSH by CYN could not be a primary mechanism for CYN toxicity, Conversely, pro-treatment with piperonyl butoxide, a P450 inhibitor, protected mice against CYN toxicity giving a survival rate of 10/10 compared with 4/10 in the control group (p < 0.05 Chi squared) and was protective at doses up to 0.8 mg/kg, suggesting activation of CYN by P450 is of primary importance in the mechanism of action. (C) 2002 Elsevier Science Ltd. All rights reserved.
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Cylindrospermopsin a cyanobacterial alkaloid evaluation of its toxicologic activity
Therapeutic Drug Monitoring, 2000Co-Authors: Glen R Shaw, A A Seawright, Michael R MooreAbstract:This paper describes the natural occurrence of the toxin, Cylindrospermopsin, in two species of cyanobacteria found in Australia. The structure and chemical properties of this compound are described along with a nontoxic analog of Cylindrospermopsin. The results of both intraperitoneal (IP) and oral dosing of mice show that hepatotoxicity is the main effect of Cylindrospermopsin in vivo, but that a thrombo-hemorrhagic phenomenon is observed in a proportion of dosed animals. It has been shown that the toxin can be metabolized in vivo and that a bound metabolite occurs in the liver. Cytotoxicity experiments using cell cultures show that Cylindrospermopsin is more cytotoxic to isolated rat liver hepatocytes than to other cell types. Risk assessment calculations show that guideline values for Cylindrospermopsin in drinking water should lie in the low microgram per liter range.
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stability of Cylindrospermopsin the toxin from the cyanobacterium cylindrospermopsis raciborskii effect of ph temperature and sunlight on decomposition
Environmental Toxicology, 1999Co-Authors: Robyn K. Chiswell, M.j. Smith, Ross Norris, Glen R Shaw, G Eaglesham, A A Seawright, Michael R MooreAbstract:Cylindrospermopsin is a powerful hepatotoxin produced by the cyanobacterium Cylindrospermopsis raciborskii. It is considered a potential threat to livestock, wildlife, and humans, and is the suspected cause of an outbreak of hepatoenteritis on Palm Island, Queensland, Australia, and various stock poisoning incidents around Australia. In this study, the stability of Cylindrospermopsin was investigated using different parameters, including visible and UV light, sunlight, temperature and pH. Cylindrospermopsin decomposes rapidly (half-life of 1.5 h) when exposed to sunlight in an algal extract solution; however, no decomposition was recorded in pure Cylindrospermopsin and Milli-Q water solutions. Cylindrospermopsin decomposes slowly in temperatures ranging from 4 to 50 degrees C at pH 7. After 10 weeks at 50 degrees C, Cylindrospermopsin had degraded to 57% of the original concentration. This degradation was accompanied by an increase in another compound which is believed to be structurally related to Cylindrospermopsin. Boiling does not cause a significant degradation of Cylindrospermopsin within 15 min. Initial investigations indicate that Cylindrospermopsin is degraded slowly under artificial light ranging from 42, 29, and 9 mu E m(-1) S-1 and in darkness. Degradation of Cylindrospermopsin was not affected by changes in pH. Experiments were performed in sterile conditions. (C) 1999 by John Wiley gr Sons, Inc.
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deoxyCylindrospermopsin an analog of Cylindrospermopsin from cylindrospermopsis raciborskii
Environmental Toxicology, 1999Co-Authors: Ross Norris, Geoffrey K. Eaglesham, M.j. Smith, Robyn K. Chiswell, Glen R Shaw, A A Seawright, Greg Pierens, Michael R MooreAbstract:Cylindrospermopsin (CYN) is a hepatotoxic alkaloid found in the blue-green alga Cylindrospermopsis raciborskii (C. raciborskii). Data indicating CYN alone does not account for the toxicity of freeze dried cultures of C. raciborskii have been presented recently. In an attempt to explain these data, we have purified and characterized the structure of an analog of CYN, deoxyCylindrospermopsin (deoxy-CYN). Three mice dosed intraperitoneally (IP) with 0.8 mg/kg of deoxy-CYN showed no toxicity after 5 days. Comparison with the toxicity of CYN (5 day median lethal dose approximately 0.2 mg/kg IF) and its relative abundance in C. raciborskii suggest deoxy-CYN does not contribute significantly to the toxicity of C. raciborskii. The additional toxicity of freeze dried C. raciborskii over pure CYN, therefore, remains unexplained. (C) 1999 by John Wiley & Sons, Inc.
Assaf Sukenik - One of the best experts on this subject based on the ideXlab platform.
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Oral toxicity of the cyanobacterial toxin Cylindrospermopsin in mice: Long‐term exposure to low doses
Environmental Toxicology, 2020Co-Authors: Assaf Sukenik, Shmuel Carmeli, M. Reisner, M. WermanAbstract:The hepatotoxin Cylindrospermopsin, a sulfated-guanidinium alkaloid with substituted dioxypyrimidine (uracil) moiety, was isolated from several cyanobacteria species. The acute toxicity of Cylindrospermopsin was well established based on intraperitoneal and oral exposure; however, only a few long-term subacute exposure studies were performed to permit a reliable guideline value for Cylindrospermopsin in drinking water. In the study reported herein, female and male mice were exposed to Cylindrospermopsin in their drinking water. Cylindrospermopsin-containing, Aphanizomenon ovalisporum (cyanobacterium)-free medium was provided as the only source of drinking water, whereas a control group was given a fresh medium for cyanobacteria as drinking water. Over a period of 42 weeks, experiment groups were exposed to Cylindrospermopsin concentration, gradually increased from 100 to 550 μg L−1 (daily exposure ranged between 10 and 55 μg kg−1 day−1). Body and organ weights were recorded, and serum and hematology analyses were performed 20 and 42 weeks after the beginning of the experiment. The most pronounced effect of Cylindrospermopsin was elevated hematocrit levels in both male and female mice after 16 weeks of exposure to Cylindrospermopsin. The observed changes in the hematocrit level were accompanied by deformation of red blood cells, which were changed into acanthocyte. Based on these results, a daily Cylindrospermopsin dose of 20 μg kg−1 day−1 (equivalent to 200 μg L−1) is proposed as the lowest-observed-adverse-effect level for both male and female mice. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 575–582, 2006.
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genetic and morphologic characterization of four putative Cylindrospermopsin producing species of the cyanobacterial genera anabaena and aphanizomenon
Journal of Plankton Research, 2009Co-Authors: Rebecca Campbell, Anke Stuken, Antonio Quesada, Assaf Sukenik, Pawan K Dadheech, Claudia WiednerAbstract:Cylindrospermopsin (CYN) is a potent hepatotoxic alkaloid that has been detected in freshwater samples worldwide and is produced by a number of cyanobacterial species, mainly of the genera Cylindrospermopsis, Aphanizomenon and Anabaena. Cylindrospermopsis raciborskii is a morphologically distinctive species which forms a genetically well-defined cluster. In contrast, some species within Aphanizomenon and Anabaena are morphologically not clearly assignable to either genera and both genera are polyphyletic. In the Cylindrospermopsis cluster CYN producing and non-producing strains co-occur, but it is not known if GYM producing and non-producing strains are closely related in Anabaena and Aphanizomenon. Here we attempt to disentangle the phylogenetic relationships of four taxa of the genera Anabaena and Aphanizomenon, some of which are known as CYN producers. We have sequenced and phylogenetically analysed partial sequences of the 16S rRNA gene, cpcBA-IGS and rpoCI from 31 cyanobacteria isolates of the genera Aphanizomenon and Anabaena and have documented morphotypic characteristics of new and recently isolated strains. Our results do not corroborate the separation of Aph. gracile and Aph. flos-aquae into separate species. In contrast, they support the distinction of Ana. bergii and Aph. ovalisporum into distinct taxa. Further, Ana. bergii is most likely not a CYN producing species.
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an abrb like protein might be involved in the regulation of Cylindrospermopsin production by aphanizomenon ovalisporum
Environmental Microbiology, 2008Co-Authors: Gali Shalevmalul, Assaf Sukenik, Judy Liemanhurwitz, Yehudith Vinermozzini, Ariel Gaathon, Mario Lebendiker, Aaron KaplanAbstract:Certain filamentous cyanobacteria, including Aphanizomenon ovalisporum, are potentially toxic owing to the formation of the hepatotoxin Cylindrospermopsin. We previously identified a gene cluster in A. ovalisporum likely to be involved in Cylindrospermopsin biosynthesis, including amidinotransferase (aoaA) and polyketide-synthase (aoaC), transcribed on the reverse strands. Analysis of the genomic region between aoaA and aoaC identified two transcription start points for each of these genes, differentially expressed under nitrogen and light stress conditions. The transcript abundances of these genes and the Cylindrospermopsin level were both affected by nitrogen availability and light intensity. Gel shift assays and DNA affinity columns isolated a protein that specifically binds to a 150 bp DNA fragment from the region between aoaA and aoaC, and MS/MS analyses identified similarity to AbrB in other cyanobacteria and in Bacillus sp. Comparison of the native AbrB isolated from A. ovalisporum with that obtained after cloning and overexpression of abrB in Escherichia coli identified specific post-translational modifications in the native cyanobacterial protein. These modifications, which are missing in the protein expressed in E. coli, include N-acetylation and methylation of specific residues. We discuss the possible role of these modifications in the regulation of Cylindrospermopsin production in Aphanizomenon.
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The Cyanobacterial Toxin Cylindrospermopsin Inhibits Pyrimidine Nucleotide Synthesis and Alters Cholesterol Distribution in Mice
Toxicological Sciences, 2004Co-Authors: M. Reisner, Shmuel Carmeli, M. Werman, Assaf SukenikAbstract:The hepatotoxin Cylindrospermopsin, a sulfated-guanidinium alkaloid with substituted dioxypyrimidine (uracil) moiety, was isolated from several cyanobacteria species. Our previous studies on the toxicity of Cylindrospermopsin and its derivatives suggested that the uracil moiety is crucial for the toxicity and that such toxicity could partly stem from competitive binding of the toxin to a catalytic site(s) involved in the synthesis of pyrimidine nucleotides (i.e., uridine). In the present study we demonstrated that Cylindrospermopsin inhibited in a noncompetitive manner the in vitro activity of uridine monophosphate (UMP) synthase complex (responsible for the conversion of orotic acid to UMP) in a cell free liver extract from mice, with an inhibition constant, K I , of 10 μM. Exposure of mice to Cylindrospermopsin at subacute concentrations, via drinking water, only slightly affected the in vitro activity of UMP synthase. The typical metabolic disorder associated with the inhibition of UMP synthase activity, known as "orotic aciduria," was not observed under these conditions, but other anomalous metabolic responses related to cholesterol metabolism were developed.
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A novel gene encoding amidinotransferase in the Cylindrospermopsin producing cyanobacterium Aphanizomenon ovalisporum
Fems Microbiology Letters, 2002Co-Authors: Gali Shalev-alon, Assaf Sukenik, Oded Livnah, Rakefet Schwarz, Aaron KaplanAbstract:The hepatotoxin Cylindrospermopsin is produced by several cyanobacteria species, which may flourish in tropical and sub-tropical lakes. Biosynthesis of Cylindrospermopsin is poorly understood but its chemical nature, and feeding experiments with stable isotopes, suggested that guanidinoacetic acid is the starter unit and indicated involvement of a polyketide synthase. We have identified a gene encoding an amidinotransferase from the Cylindrospermopsin producing cyanobacterium Aphanizomenon ovalisporum. This is the first report on an amidinotransferase gene in cyanobacteria. It is likely to be involved in the formation of guanidinoacetic acid. The aoaA is located in a genomic region bearing genes encoding a polyketide synthase and a peptide synthetase, further supporting its putative role in Cylindrospermopsin biosynthesis.
Christopher P Saint - One of the best experts on this subject based on the ideXlab platform.
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An examination of the antibiotic effects of Cylindrospermopsin on common gram-positive and gram-negative bacteria and the protozoan Naegleria lovaniensis
Environmental Toxicology, 2020Co-Authors: J. Paul Rasmussen, Michael Cursaro, Suzanne M. Froscio, Christopher P SaintAbstract:The importance of the toxin Cylindrospermopsin to the function and fitness of the cyanobacteria that produce it remains a matter of conjecture. Given that the structure of Cylindrospermopsin has commonalities with other antibacterial protein synthesis inhibitors, such as streptomycin, authors tested the possibility that the toxin might act as an antibacterial compound that can kill competing microbes. Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa were tested by the minimal inhibitory concentration method and significant antibacterial activity was only observed at a Cylindrospermopsin concentration of 300 μg mL−1 after exposure for 5 days. No effect on log phase growth of E. coli was observed for this same toxin concentration. Protein synthesis was inhibited by Cylindrospermopsin in E. coli 70S extracts, reduced by 25% compared with controls when treated with 41.5 μg mL−1 of the toxin; however, a much greater reduction of 97% was observed for chloramphenicol in the same experiment. Naegleria lovaniensis, a phagotrophic protozoan, was more susceptible to Cylindrospermopsin, with a decrease in the number of N. lovaniensis plaques after 24-h treatment with 5–50 μg mL−1 of toxin and an LC50 of ∼60 μg mL−1. Given these results, Cylindrospermopsin is clearly not antibacterial at concentrations found in environmental waters, nor will it adversely affect N. lovaniensis at these concentrations. For organisms that are able to ingest Cylindrospermopsin-producing cells, the response of N. lovaniensis to the toxin suggests that only a few ingested cells would be enough to kill predatory organisms with similar susceptibility. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008.
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development and field testing of a real time pcr assay for Cylindrospermopsin producing cyanobacteria
Journal of Applied Microbiology, 2008Co-Authors: J Rasmussen, Steven Giglio, Paul Monis, Rebecca Campbell, Christopher P SaintAbstract:Aims: To develop and test a real-time PCR assay to detect and quantify genes specific to Cylindrospermopsis sp. and Cylindrospermopsin-producing cyanobacteria. Method and Results: A duplex real-time PCR assay was developed that targets a Cylindrospermopsin-specific and Cylindrospermopsis raciborskii-specific DNA sequence. The C. raciborskii-specific sequence was based on the rpoC1 DNA-dependent RNA polymerase gene, whilst the Cylindrospermopsin-specific sequence was selected by surveying an extensive number of potential Cylindrospermopsin-producing cyanobacterial strains for genes implicated in toxin production, aoaA, aoaB and aoaC. In toxic strains, sequences of each of these three genes were always present; whilst in nontoxic strains the distribution of these sequences was patchy, resulting in what are likely to be natural deletion mutants. The real-time assay was optimized on a fixed and portable device, with results indicating that the reliable limit of detection for the assay was 100 copies per reaction or 1000 cells ml−1 for both target sequences on both devices. In routine environmental samples enumerated by microscopy, the assay results were positive for all samples where C. raciborskii cells were observed at >1000 cells ml−1 and negative in 15 samples where no C. raciborskii cells were observed. In field samples, the number of copies of the rpoC1 sequence more closely approximated the number of cells enumerated by microscopy, the number of copies of the pks sequence and detection of the toxin-specific sequence matched the results of toxin testing. Conclusions: The duplex real-time PCR assay was a sensitive and rapid method for detecting potential Cylindrospermopsin-producing cyanobacteria in the laboratory or in the field. The observation of probable natural deletion mutants provides further evidence that the aoaA, aoaB and aoaC genes are involved in toxin production. Significance and Impact of the Study: This assay provides a new monitoring capability for tracking Cylindrospermopsin-producing cyanobacteria that are an emerging threat to water quality.
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multiplex pcr assay for cylindrospermopsis raciborskii and Cylindrospermopsin producing cyanobacteria
Environmental Toxicology, 2003Co-Authors: Kim M Fergusson, Christopher P SaintAbstract:Water bodies are routinely monitored for the presence of potentially toxic cyanobacteria; however, the methodology for confirming toxicity is currently complex and expensive. Here we describe the application of gene-based technology to rapidly identify Cylindrospermopsin-producing cyanobacteria, specifically, Cylindrospermopsis raciborskii. A multiplex polymerase chain reaction (PCR) test was developed that simultaneously identified polyketide synthase (pks) and peptide synthetase (ps) determinants associated with Cylindrospermopsin production and distinguished C. raciborskii from other Cylindrospermopsin-producing cyanobacteria of the species Anabaena bergii and Aphanizomenon ovalisporum, by targeting the rpoC1 gene. Twenty-one C. raciborskii, 5 A. bergii, 10 Aph. ovalisporum isolates and 3 environmental samples all yielded PCR results consistent with their toxicological status, as assessed by high-performance liquid chromatography coupled to mass spectrometry or matrix-assisted laser desorption ionization–time-of-flight mass spectrometry, and C. raciborskii was always correctly identified. The PCR test is a rapid, reliable, and economical way of assessing the toxic potential of cyanobacterial blooms formed by these organisms. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 120–125, 2003.
Geoffrey K. Eaglesham - One of the best experts on this subject based on the ideXlab platform.
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evaluation of quantitative real time pcr to characterise spatial and temporal variations in cyanobacteria cylindrospermopsis raciborskii woloszynska seenaya et subba raju and Cylindrospermopsin concentrations in three subtropical australian reservoir
Harmful Algae, 2010Co-Authors: Paul J Rasmussen, Geoffrey K. Eaglesham, Michele A Burford, Sarah M LennoxAbstract:Abstract Three drinking water storage reservoirs in subtropical southeast Queensland, Australia have regular blooms of the toxic cyanobacterium Cylindrospermopsis raciborskii that can produce Cylindrospermopsins. We tested water samples from 16 sites in 3 reservoirs on 2 sampling occasions during a bloom of C. raciborskii in the austral summer and autumn of 2007. Using a range of parameters including quantitative real-time PCR, microscope cell counts and HPLC–MS/MS we correlated the 16S ribosomal RNA gene with total cyanobacteria, the rpoC 1 gene with C. raciborskii cell concentrations, and the cyrC gene with Cylindrospermopsin concentrations to assess spatial and temporal variability within and between reservoirs. While the correlation between cyrC and Cylindrospermopsin cell quotas was good (mean r 2 = 0.61 for February samples and 0.75 for March samples), the correlation between total cyanobacteria and the 16S ribosomal RNA gene, and between C. raciborskii and the rpoC 1 gene were poor indicating that further work is needed to develop these novel molecular methods. Spatial and temporal analysis of the distribution of rpoC 1, Cylindrospermopsin cell quotas, and a range of physical and chemical water quality parameters showed the greatest variation occurred between reservoirs, and within the largest and most spatially diverse reservoir. This suggests that populations of C. raciborskii strains with inherently different Cylindrospermopsin cell quotas may be an important driver of toxicity in these reservoirs. An outcome of this study was the observation that deoxyCylindrospermopsin always exceeded the Cylindrospermopsin cell quota by up to 5-fold, and that a peak cell quota of 60 fg (Cylindrospermopsin + deoxyCylindrospermopsin) cell −1 was measured.
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Analysis of cyanobacterial toxins by hydrophilic interaction liquid chromatography-mass spectrometry
Journal of Chromatography A, 2004Co-Authors: Carmela Dell'aversano, Geoffrey K. Eaglesham, Michael A QuilliamAbstract:The combination of hydrophilic interaction liquid chromatography with electrospray mass spectrometry (HILIC-MS) has been investigated as a tool for the analysis of assorted toxins produced by cyanobacteria. Toxins examined included saxitoxin and its various analogues (1-18), anatoxin-a (ATX-a, 19), Cylindrospermopsin (CYN, 20), deoxyCylindrospermopsin (doCYN, 21), and microcystins-LR (22) and -RR (23). The saxitoxins could be unequivocally detected in one isocratic analysis using a TSK gel Amide-80 column eluted with 65% B, where eluent A is water and B is a 95% acetonitrile/water solution, both containing 2.0mM ammonium formate and 3.6mM formic acid. The analysis of ATX-a, CYN and doCYN required 75% B isocratic. Simultaneous determination of 1-21 was also possible by using gradient elution. HILIC proved to be suitable for the analysis of microcystins, but peak shape was not symmetric and it was concluded that these compounds are best analysed using existing reversed-phase methods. The HILIC-MS method was applied to the analysis of field and cultured samples of Anabaena circinalis and Cylindrospermopsis raciborskii. In general, the method proved quite robust with similar results obtained in two different laboratories using different instrumentation. © 2004 Elsevier B.V. All rights reserved.
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Cylindrospermopsin occurrence in two german lakes and preliminary assessment of toxicity and toxin production of cylindrospermopsis raciborskii cyanobacteria isolates
Toxicon, 2003Co-Authors: Jutta Fastner, Geoffrey K. Eaglesham, Andrew R Humpage, Rita Heinze, U Mischke, Ingrid ChorusAbstract:Abstract Cylindrospermopsis raciborskii , a freshwater cyanobacterium of tropical origin, is not only increasingly found in (sub) tropical water bodies, but also in temperate regions. Since this species may produce potent toxins such as Cylindrospermopsin (CYN) and paralytic shellfish poisons, its massive occurrence in water bodies used as drinking water sources or for recreation is of major concern. The proliferation of C. raciborskii in German water bodies has been documented for the past decade. We investigated the occurrence of CYN in field populations and isolates of C. raciborskii from two lakes, and assessed the toxicity of culture isolates using the mouse bioassay, primary rat hepatocytes and human derived cell lines. We show for the first time the occurrence of CYN in German water bodies. None of seven isolates of C. raciborskii contained CYN, however, all isolates were toxic to primary rat hepatocytes, human hepatoblastoma (HEP-G2) and human colon adenocarcinoma (CACO-2) cells. Methanolic extracts were more toxic than aqueous extracts. Three isolates tested in the mouse bioassay were toxic at a concentration of 800 mg kg −1 showing liver and spleen damage and inflammation of the intestine. These results give strong evidence that the German isolates of C. raciborskii contain currently not identified or unknown toxins.
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deoxyCylindrospermopsin an analog of Cylindrospermopsin from cylindrospermopsis raciborskii
Environmental Toxicology, 1999Co-Authors: Ross Norris, Geoffrey K. Eaglesham, M.j. Smith, Robyn K. Chiswell, Glen R Shaw, A A Seawright, Greg Pierens, Michael R MooreAbstract:Cylindrospermopsin (CYN) is a hepatotoxic alkaloid found in the blue-green alga Cylindrospermopsis raciborskii (C. raciborskii). Data indicating CYN alone does not account for the toxicity of freeze dried cultures of C. raciborskii have been presented recently. In an attempt to explain these data, we have purified and characterized the structure of an analog of CYN, deoxyCylindrospermopsin (deoxy-CYN). Three mice dosed intraperitoneally (IP) with 0.8 mg/kg of deoxy-CYN showed no toxicity after 5 days. Comparison with the toxicity of CYN (5 day median lethal dose approximately 0.2 mg/kg IF) and its relative abundance in C. raciborskii suggest deoxy-CYN does not contribute significantly to the toxicity of C. raciborskii. The additional toxicity of freeze dried C. raciborskii over pure CYN, therefore, remains unexplained. (C) 1999 by John Wiley & Sons, Inc.
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blooms of the Cylindrospermopsin containing cyanobacterium aphanizomenon ovalisporum forti in newly constructed lakes queensland australia
Environmental Toxicology, 1999Co-Authors: Glen R Shaw, Geoffrey K. Eaglesham, M.j. Smith, Ross Norris, Robyn K. Chiswell, A A Seawright, Assaf Sukenik, Adi Livne, Michael R MooreAbstract:The cyanobacterium, Aphanizomenon ovalisporum (Forti) is reported herein for the first time in Australia. Its distribution appears to be restricted to an isolated subtropical region which has distinctive water quality parameters including ready availability of nutrients and relatively high chloride and hardness levels. Blooms of A. ovalisporum in Queensland, Australia, formed a thick brown surface scum from spring to autumn in newly constructed shallow lakes. During such blooms, the water and cellular material were both found to contain Cylindrospermopsin, a water soluble toxin that produced fatty livers with hepatocyte necrosis in mice similar to the toxicity produced by Cylindrospermopsis raciborskii (Wolosz.). Toxin levels in freeze-dried A. ovalisporum are approximately 25% of those present in freeze-dried C. raciborskii. However, A. ovalisporum appears to release more of the produced toxin into the water body than does C. raciborskii. Sequencing of the 16s ribosomal RNA gene of A. ovalisporum isolated from the Australian bloom showed that it was virtually identical to A. ovalisporum isolated from Lake Kinneret. Much lower homology was found between A. ovalisporum and other species of that genus (i.e., A. flos-aquae and A. gracile) or C. raciborskii, which is known to produce the toxin Cylindrospermopsin. (C) 1999 by John Wiley & Sons, Inc.
Andrew R Humpage - One of the best experts on this subject based on the ideXlab platform.
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Cylindrospermopsin occurrence in two german lakes and preliminary assessment of toxicity and toxin production of cylindrospermopsis raciborskii cyanobacteria isolates
Toxicon, 2003Co-Authors: Jutta Fastner, Geoffrey K. Eaglesham, Andrew R Humpage, Rita Heinze, U Mischke, Ingrid ChorusAbstract:Abstract Cylindrospermopsis raciborskii , a freshwater cyanobacterium of tropical origin, is not only increasingly found in (sub) tropical water bodies, but also in temperate regions. Since this species may produce potent toxins such as Cylindrospermopsin (CYN) and paralytic shellfish poisons, its massive occurrence in water bodies used as drinking water sources or for recreation is of major concern. The proliferation of C. raciborskii in German water bodies has been documented for the past decade. We investigated the occurrence of CYN in field populations and isolates of C. raciborskii from two lakes, and assessed the toxicity of culture isolates using the mouse bioassay, primary rat hepatocytes and human derived cell lines. We show for the first time the occurrence of CYN in German water bodies. None of seven isolates of C. raciborskii contained CYN, however, all isolates were toxic to primary rat hepatocytes, human hepatoblastoma (HEP-G2) and human colon adenocarcinoma (CACO-2) cells. Methanolic extracts were more toxic than aqueous extracts. Three isolates tested in the mouse bioassay were toxic at a concentration of 800 mg kg −1 showing liver and spleen damage and inflammation of the intestine. These results give strong evidence that the German isolates of C. raciborskii contain currently not identified or unknown toxins.
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cell free protein synthesis inhibition assay for the cyanobacterial toxin Cylindrospermopsin
Environmental Toxicology, 2001Co-Authors: Suzanne Froscio, Andrew R Humpage, Philip Burcham, Ian R FalconerAbstract:The cyanobacterial toxin Cylindrospermopsin (CYN) is known to be a potent inhibitor of protein synthesis. This paper describes the use of a rabbit reticulocyte lysate translation system as a protein synthesis inhibition assay for CYN. A dose response curve for protein synthesis inhibition by CYN was constructed and was modeled to a sigmoidal dose response curve with variable slope (R2=0.98). In this assay, CYN has an IC50 of 120 nM [95% chemical interaction (CI)=111−130 nM] with a detection limit in the region of 50 nM in the assay solution. Application of the assay allows quantification of toxin samples within the range 0.5–3.0 μM (200–1200 μg/L) CYN. To assess the usefulness of this assay, a range of toxic and nontoxic Cylindrospermopsis raciborskii extracts, including both laboratory strains and environmental samples, were assayed by protein synthesis inhibition. These CYN quantifications were then compared to quantifications obtained by high performance liquid chromatography (HPLC) and HPLC-tandem mass spectrometry (HPLCMS–MS). The results demonstrate that the protein synthesis inhibition assay correlates well with both HPLCMS–MS (r2=0.99) and HPLC (r2=0.97) quantifications. We conclude that this is an accurate and rapid assay for the measurement of Cylindrospermopsin in cyanobacterial extracts. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 408–412, 2001
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preliminary evidence for in vivo tumour initiation by oral administration of extracts of the blue green alga cylindrospermopsis raciborskii containing the toxin Cylindrospermopsin
Environmental Toxicology, 2001Co-Authors: Ian R Falconer, Andrew R HumpageAbstract:New reports indicate that the toxic alkaloid Cylindrospermopsin occurs in cyanobacteria in Israel, Florida, South America, and Australia in drinking water sources. This toxin is now recognised as a potential threat to human health. Furthermore, we have recently demonstrated the mutagenicity of Cylindrospermopsin in vitro in a human lymphoblastoid cell-line. Therefore it is essential to determine whether Cylindrospermopsin is also carcinogenic in vivo. In this preliminary study, 53 mice were treated up to three times orally with Cylindrospermopsis raciborskii extract containing Cylindrospermopsin, while 27 control mice were treated with saline. A proportion of each group were then given O-tetradecanoylphorbol 13-acetate (10 μg/mouse, twice weekly in liquid food) for the duration of the experiment; the remainder were given a control diet. After 30 weeks, the mice were euthanased and the major organs were examined histologically. Five tumours were found in 53 Cylindrospermopsin-treated mice while none were found in the 27 controls. Although the number of animals used was too low to provide statistical significance (p=0.16), the calculated relative risk (RR=6.2; 95% CI: 0.33–117) indicates a potential biological and public health significance requiring further investigation. Estimates are given of the size of experiment required to provide statistical proof of Cylindrospermopsin carcinogenicity. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 192–195, 2001
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micronucleus induction and chromosome loss in transformed human white cells indicate clastogenic and aneugenic action of the cyanobacterial toxin Cylindrospermopsin
Mutation Research-genetic Toxicology and Environmental Mutagenesis, 2000Co-Authors: Ian R Falconer, Andrew R Humpage, Michael Fenech, Philip J ThomasAbstract:Abstract Cylindrospermopsin (CYN) is a potent inhibitor of protein synthesis produced by a number of cyanobacterial species, the most common being Cylindrospermopsis raciborskii . CYN contains a uracil moiety attached to a sulphated guanidino moiety, suggesting that it may have carcinogenic activity. This report describes the use of the WIL2-NS lymphoblastoid cell-line in the well-validated cytokinesis-block micronucleus (CBMN) assay to test this hypothesis. Centromeres (CENs) were identified in micronuclei (MNi) of binucleated cells (BNCs) by fluorescent in situ hybridisation of alpha centromeric DNA sequence repeats. The results indicate that CYN induced a significant increase in the frequency of MNi in BNCs exposed to 6 and 10 μg/ml, and a significant increase in CEN-positive MNi at all concentrations of CYN tested (1, 3, 6, and 10 μg/ml). However, despite this apparently greater sensitivity of WIL2-NS cells to induction of CEN-positive MNi at low CYN concentrations, at the higher concentrations the magnitude of the increase in CEN-positive MNi did not account for the greater increase in MNi in BNCs, indicating that both CEN-positive and CEN-negative MNi were induced. This suggests that CYN acts to induce cytogenetic damage via two mechanisms, one at the level of the DNA to induce strand breaks, the other at the level of kinetochore/spindle function to induce loss of whole chromosomes (aneuploidy). C. raciborskii occurs in a number of human drinking water sources worldwide and so these findings may have important public health implications.
