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Microcystin Concentration (microcystin + concentration)
Selected AbstractsCharacteristics of microcystin production in the cell cycle of Microcystis viridisENVIRONMENTAL TOXICOLOGY, Issue 1 2004Keishi Kameyama Abstract The correlation between the content of three microcystins (types LR, RR and YR) and the cell cycle of an axenic strain of Microcystis viridis, NIES-102, was investigated under conditions of high (16 mg L,1) and low (1.0 mg L,1) nitrate (NO3 -N) concentrations. Each phase of the cell cycle was identified using a flow cytometer equipped with a 488-nm argon laser using SYTOX Green dye, which binds specifically to nucleic acids and can be exited by the wavelength (Ex/Em: 504/523 nm on DNA). Microcystin concentration showed a positive linear correlation with DNA concentration. The microcystin content of the cells changed remarkably as the cell cycle process proceeded, with maximum content in the G2/M phase and minimum content in the G0/G1 phase. Under a condition of high NO3 -N concentration, the ratio of the total content in the G0/G1 phase to that in the G2/M phase was about 6:1. In contrast, for the two batch cultures the total content was 1.3-fold greater in the G2/M phase. The compositions of the three microcystins also changed along with the cell cycle process, although there was little difference in composition that was related to NO3 -N concentration. Therefore, there were distinctive compositions specific to each phase of the cycle, and the cell cycle of the M. viridis strain was more strongly responsible for both the quantity and the types of microcystin production than was the effect of NO3 -N concentration. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 20,25, 2004. [source] Contrasting microcystin production and cyanobacterial population dynamics in two Planktothrix -dominated freshwater lakesENVIRONMENTAL MICROBIOLOGY, Issue 10 2005Ingmar Janse Summary Microcystin concentrations in two Dutch lakes with an important Planktothrix component were related to the dynamics of cyanobacterial genotypes and biovolumes. Genotype composition was analysed by using denaturing gradient gel electrophoresis (DGGE) profiling of the intergenic transcribed spacer region of the rrn operon (rRNA-ITS), and biovolumes were measured by using microscopy. In Lake Tjeukemeer, microcystins were present throughout summer (maximum concentration 30 µg l,1) while cyanobacterial diversity was low and very constant. The dominant phototroph was Planktothrix agardhii. In contrast, Lake Klinckenberg showed a high microcystin peak (up to 140 µg l,1) of short duration. In this lake, cyanobacterial diversity was higher and very dynamic with apparent genotype successions. Several genotypes derived from DGGE field profiles matched with genotypes from cultures isolated from field samples. The microcystin peak measured in Lake Klinckenberg could be confidently linked to a bloom of Planktothrix rubescens, as microscopic and genotypic analysis showed identity of bloom samples and a toxin-producing P. rubescens culture. Toxin-producing genotypes were detected in the microbial community before they reached densities at which they were detected by using microscopy. Cyanobacterial biovolumes provided additional insights in bloom dynamics. In both lakes, the microcystin content per cell was highest at the onset of the blooms. Our results suggest that while genotypic characterization of a lake can be valuable for detection of toxic organisms, for some lakes a monitoring of algal biomass has sufficient predictive value for an assessment of toxin production. [source] POPULATION DYNAMICS AND THE TOXICITY OF BLUE-GREEN ALGAE IN THE NAKTONG RIVER, KOREAJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Lee, J. A.1, Choi, A. R.1, Park, J. H.1 & Chung, I. K2 1Department of Environmental Science, Inje University, Kimhae 621-749, Korea; 2Departement of Marine Science, Pusan National University, Pusan 609-735, Korea Seasonal and spatial variations of phytoplankton community were monitored at 16 sites along the Naktong River. Blue-green algae appeared from May through November with dominant genera of Microcystis, Anabaena, Oscillatoria and Gomphosphaeria. Frequency and biomass of the genera became greater at lower reaches. The Microcystis were observed from May to October up to 85,750cells/ml. Six species of Microcystis were identified with morphological characteristics and M. aeruginosa was most dominant. There were significant relationships between biomass of Microcystis and NO -3, TP and pH in water column. However, NH4+, PO4 -3 and N/P were not critical in successions to the Microcystis dominated community. Microcystis blooms were notable at water temperature higher than 25°C. Microcystis density in sediment was 3 orders of magnitude higher than water column. Anabaena density ranged up to 11,220cells/ml. Four species of Anabaena were identified and A. flos-aquae was most dominant. Anabaena biomass was not related to temperature, NO3 - , TN, PO4 -3, TP and N/P of water column and the frequency of trichome with akinete and/or heterocyte were not related to these parameters. Microcystins were detected from May to November with yearly fluctuations. Microcystin-RR was most dominant. Total 84.2% of algal materials with Microcystis exhibited toxicity of microcystin with maximum of 3,292,g/g dry wt. Total 12.5% of water column with Microcystis exhibited dissolved microcystin up to 3.3,g/l. Microcystin concentrations were positively related to Microcystis biomass and pH of water column. Anatoxin-a was determined by FD-HPLC analysis with NBD-F and all concentrations were below the detection limit of 0.1,g/l. [source] Summer changes in cyanobacterial bloom composition and microcystin concentration in eutrophic Czech reservoirsENVIRONMENTAL TOXICOLOGY, Issue 3 2006Petr Znachor Abstract In mid-July and August 2003 and 2004, 18 reservoirs in the Czech Republic were sampled for phytoplankton species composition and concentration of intracellular microcystins (MCs). As a consequence of high nutrient loading, most of the reservoirs experienced cyanobacterial blooms of various intensities, with the prevalence of cyanobacteria increasing markedly in August, along with a conspicuous shift in species composition toward dominance of Microcystis spp. Microcystins were detected in 90% of the samples, and their amount also increased considerably in August, reflecting the cyanobacterial biomass. In Microcystis -dominated samples, a significantly higher amount of MCs (p < 0.001) occurred than in samples in which other taxa prevailed. Microcystins were positively correlated with chlorophyll a and cyanobacterial biovolume (p < 0.05, R2 = 0.61 and 0.66, respectively), with the strongest correlation found for Microcystis spp. biovolume (p < 0.001, R2 = 0.87). This taxon was the most important producer of MCs in Czech reservoirs. The main structural variants of MCs were MC-LR, MC-RR, and MC-YR. This study's data also indicate that the relative share of MC variants (MC-LR and MC-RR) varies considerably with time, most likely as a consequence of different species and strain compositions during the summer. This study clearly demonstrates a high prevalence of MC-producing cyanobacteria in Czech reservoirs. Therefore, regular monitoring of these reservoirs is highly desirable in an effort to minimize potential health risks to the human population. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 236,243, 2006. [source] Hepatotoxic cyanobacterial blooms in the lakes of northern PolandENVIRONMENTAL TOXICOLOGY, Issue 5 2005Joanna Mankiewicz Abstract The lakes of northern Poland are among the recreational sites most valued by Polish and German holiday makers. Given the socioeconomic importance of these lakes, water quality should be maintained at high levels for such intensive recreational purposes. In 2002 studies of species composition, biomass, and toxin production by phytoplankton and the attendant physicochemical variables were performed in order to assess the risk of cyanobacterial blooms in selected northern lakes: Lakes Jeziorak, Jagodne, Szymoneckie, Szymon, Taltowisko, Siecino, and Trzesiecko. The research showed that total phosphorus (0.1 mg P/L) and total nitrogen (1.5 mg N/L) in the studied lakes almost exceeded the permissible limits for eutrophication of water bodies. Most phytoplankton samples were taken in late summer, when cyanobacteria were expected to reach their highest biomass. At the time of sampling most of the lakes were dominated by oscillatorialean and nostocalean species. Average chlorophyll-a concentration was higher than 10 ,g/L in almost all the lakes studied, which corresponded with an average microcystin concentration in the range of 4,5 ,g/L. The main microcystins in the analyzed samples were dmMC-RR, MC-RR, MC-YR, and MC-LR. The results demonstrated a potential for intensive cyanobacterial blooms to appear during the summer in northern Polish lakes. The levels of cyanobacteria found in the lakes investigated indicated that toxicity had reached the first-alert level according to World Health Organization recommendations. If microcystin-producing cyanobacteria dominate, with a microcystin concentration of 2,4 ,g/L, symptoms of toxicity can appear in the swimmers most sensitive to exposure. Analysis of cyanobacterial assemblages in northern Polish lakes also indicated a significant presence of Aphanizomenon species including a Scandinavian species, A. skujae (Skuja) Kom.-Legn. & Cronb. Future investigations of Polish lakes also should assess neurotoxins and study the biology of their producers. This study was the first attempt to evaluate the potential danger of toxic cyanobacterial blooms in the lakes of northern Poland. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 499,506, 2005. [source] Tests for the toxicity assessment of cyanobacterial bloom samplesENVIRONMENTAL TOXICOLOGY, Issue 5 2001gorzata Tarczynska Abstract Cyanobacterial (blue,green algal) blooms are one of the common consequences of the increasing eutrophication of surface waters. The production of cyanobacterial toxins and their presence in drinking and recreational waters represents a growing danger to human and animal health. Due to a lack of toxin standards and to resource limitations on the wide-scale use of analytical methods (e.g., high-performance liquid chromatography, enzyme-linked immunosorbent assay (ELISA)) in cyanobacterial toxin monitoring, it is necessary to assess and to develop additional methods for their detection and estimation. Microbiotests using invertebrates offer a possible approach for the inexpensive and straightforward detection and assessment of cyanobacterial bloom toxicity. Three microbiotests with: Thamnocephalus platyurus, Daphnia magna, and Spirostomum ambiguum were examined with bloom samples containing hepatotoxic microcystin-LR and up to five additional microcystin variants. Two kinds of cyanobacterial bloom sample preparations were tested: crude extracts (CE) and purified extracts (PE). The highest toxicity was found when CE was used for microbiotests. The sensitivity of microorganisms decreased from S. ambiguum to T. platyurus and to D. magna. A statistically significant correlation was found between microcystin concentration and T. platyurus biotest, and between mouse bioassay and S. ambiguum results. Addition of Me2SO (1%, v/v) is a possible method to increase the sensitivity of the microorganisms for microcystin-LR. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 383,390, 2001 [source] A new morphospecies of Microcystis sp. forming bloom in the Cheffia dam (Algeria): Seasonal variation of microcystin concentrations in raw water and their removal in a full-scale treatment plantENVIRONMENTAL TOXICOLOGY, Issue 4 2007Hichèm Nasri Abstract Toxic cyanobacterial blooms are an increasing problem in Algeria. The production of cyanotoxins (microcystins) and their presence in drinking water represent growing hazards to human health. In this study, seasonal variations in the concentrations of total microcystins and physicochemical parameters (pH, temperature, dissolved oxygen, nitrate, orthophosphate, and chlorophyll- a) were analyzed in the Cheffia dam (Algeria), mainly used to supply drinking water. The removal of cyanobacterial cells and microcystins was also evaluated in full-scale plant associated with the Cheffia reservoir. The levels of microcystins (MCYSTs) in both raw and drinking water were evaluated using the protein phosphatase type 2A (PP2A) inhibition test as MCYST-LR equivalents. Identification of microcystin variants was achieved by LC/MS/MS. During the period of study (March,December 2004), microscopic observation showed the dominance in the autumn months (September,November) of a new morphospecies of Microcystis sp. The MCYST-LR equivalent concentrations in raw water varied between 50.8 and 28,886 ng L,1. The highest level of toxins was observed in October 2004 and was significantly correlated with the chlorophyll- a. Three variants of microcystins assigned as microcystin-YR (MCYST-YR), microcystin-LR (MCYST-LR), and 6Z -Adda stereoisomer of MCYST-LR were observed in the crude extract of the Microcystis sp. bloom sample. During the bloom period, total elimination of Microcystis sp. and toxins were achieved through a classical treatment plant comprised of coagulation and flocculation, powdered activated carbon at 15 mg L,1, slow sand filtration and chlorination before storage. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 347,356, 2007. [source] | ||||||||||