Publications (7)4.86 Total impact
Article: Temporal and spatial variability of cyanobacterial toxins microcystins in three interconnected freshwater reservoirs[show abstract] [hide abstract]
ABSTRACT: In spite of substantial research on health and ecological risks associated with cyanobacterial toxins in past decades, our understanding to natural dynamics and variability of toxic cyanobacterial blooms is still limited. Here we report results of the long term monitoring 1998-1999 / 2001-2008 of three reservoirs (Vír, Brno, Nové Mlýny) where toxic blooms develop annually. These three reservoirs provide a unique model, because they are interconnected by a river Svratka, which allows possible transfer of phytoplankton as well as toxins from one reservoir to another. Frequency of occurrence and dominance of the major cyanobacterial taxa Microcystis aeruginosa did not change during the investigated period but substantial variability was observed in the composition of other phytoplankton. Although absolute concentrations of studied toxins (microcystins) differed among reservoirs, there were apparent parallel trends. For example, during certain years, microcystin concentrations were systematically elevated in all three studied reservoirs. Further, concentration profiles in three sites were also correlated (parallel trends) within individual seasons based on monthly samplings. Microcystin-LR, a variant for which World Health Organization recommended a guideline value, formed only about 30-50% of total microcystins. This is of importance especially in the Vír reservoir, which serves as a drinking water supply. Maxima in the cell-bound microcystins (intracellular; expressed per dry weight biomass) generally preceded the maxima of total microcystins (expressed per volume of water sample). Overall maximum concentration in biomass (all three reservoirs, period 1993-2005) was 6.1 mg/g dry weight; median values ranged 0.065 - 2.3 mg/g dry weight. These are generally high concentrations in comparison with both Czech Republic and worldwide reported data. Our data reveal substantial variability of both toxic cyanobacteria and their peptide toxins that should be reflected by detailed monitoring programs.01/2010; 75:1303-1312.
Article: Effects of co-exposure to cyanobacterial biomass, lead and immunological challenge in Japanese quails01/2008; 180:S197-S197.
Article: Detoxification and oxidative stress responses along with microcystins accumulation in Japanese quail exposed to cyanobacterial biomass[show abstract] [hide abstract]
ABSTRACT: The cyanobacterial. exposure has been implicated in mass mortalities of wild birds, but information on the actual effects of cyanobacteria on birds in controlled studies is missing. Effects on detoxification and antioxidant parameters as well as bioaccumulation of microcystins (MCs) were studied in birds after sub-lethal exposure to natural cyanobacterial biomass. Four treatment groups of model species Japanese quail (Coturnix coturnix japonica) were exposed to controlled doses of cyanobacterial bloom during acute (10 days) and subchronic (30 days) experiment. The daily doses of cyanobacterial biomass corresponded to 0.2-224.6 ng MCs/g body weight. Significant accumulation of MCs was observed in the liver for both test durations and slight accumulation also in the muscles of the highest treatment group from acute test. The greatest accumulation was observed in the liver of the highest treatment group in the acute test reaching average concentration of 43.7 ng MCs/g fresh weight. The parameters of detoxification metabolism and oxidative stress were studied in the liver, heart and brain. The cyanobacterial exposure caused an increase of activity of cytochrome P-450-dependent 7-ethoxyresorufin O-deethylase representing the activation phase of detoxification metabolism. Also the conjugation phase of detoxification, namely the activity of glutathione-S-transferase, was altered. Cyanobacterial exposure also modulated oxidative stress responses including the level of glutathione and activities of glutathione- related enzymes and caused increase in lipid peroxidation. The overall pattern of detoxification parameters and oxidative stress responses clearly separated the control and the lowest exposure group from all the higher exposed groups. This is the first controlled study documenting the induction of oxidative stress along with MCs accumulation in birds exposed to natural cyanobacterial biomass. The data also suggest that increased activities of detoxification enzymes could lead to greater biotransformation and elimination of the MCs at the longer exposure time. (C) 2008 Elsevier B.V. All rights reserved.01/2008; 398:34-47.
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ABSTRACT: Mortality of wild aquatic birds has recently been attributed to cyanobacterial toxins. Despite this, no experimental studies on the effects of defined doses of microcystins administered orally to birds exist. In this experiment, four groups of male Japanese quails daily ingesting 10ml of Microcystis biomass containing 0.045, 0.459, 4.605 or 46.044mug of microcystins, respectively, for 10 and 30 days, showed no mortality. Histopathological hepatic changes in birds after the biomass exposure included cloudy swelling of hepatocytes, vacuolar dystrophy, steatosis and hyperplasia of lymphatic centres. On subcellular level, shrunken nuclei of hepatocytes containing ring-like nucleoli, cristolysis within mitochondria and vacuoles with pseudomyelin structures were present. Vacuolar degeneration of the testicular germinative epithelium was found in two exposed males. Statistically significant differences in biochemical parameters were on day 10 of exposure only. They comprised increased activities of lactate dehydrogenase and a drop in blood glucose in birds receiving the highest dose of the biomass. Principal component analysis revealed a pattern of responses in biochemical parameters on day 10 that clearly separated the two greatest exposure groups from the controls and lower exposures. The results indicate that diagnosis of microcystin intoxication solely based on clinical biochemical and haematological parameters is hardly possible in birds.Toxicon 06/2007; 49(6):793-803. · 2.51 Impact Factor
Article: Microcystin kinetics (bioaccumulation, elimination) and biochemical responses in common carp and silver carp exposed to toxic cyanobacterial blooms01/2007; 26:2687-2693.
Article: Web portal for management of bioindication methods and ecotoxicological tests in ecological risk assessment.[show abstract] [hide abstract]
ABSTRACT: The objective of this article is to inform about efforts to design and implement a data model that can parametrically describe and store information about a wide range of ecotoxicological tests and bioindication methods used in Ecological Risk Assessment (EcoRA). At the same time it describes comprehensive web-based portal built on this model that can be used to quickly find relevant biological assays (ecotoxicological biotests) for given situation and therefore support the decision-making process in EcoRA. The model structure, features of the corresponding website and its current content is described in detail and proposed development and possible collaboration is outlined. The portal (DATEST) is located at http://projects.cba.muni.cz/datest. The aim of this work is to complement existing EcoRA decision-support tools with a web-based engine for storing and searching biological tests and methods used in EcoRA as there is currently no similar informational source available on the Internet.Ecotoxicology 12/2006; 15(8):623-7. · 2.36 Impact Factor
Article: Evaluation of extraction approaches linked to ELISA and HPLC for analyses of microcystin-LR, -RR and -YR in freshwater sediments with different organic material contents[show abstract] [hide abstract]
ABSTRACT: The efficiencies of conventional extraction techniques and analytical methods (HPLC-DAD and ELISA) were investigated for analyses of microcystins (MCs) in sediments. Our results showed several limitations. First, the extraction efficiency strongly depends on the extraction solvent, and extraction with 5% acetic acid in 0.2% trifluoroacetic acid (TFA)-methanol was confirmed as being the most appropriate for three different sediments (recovery: 33.1-44.9% of total MCs according to HPLC analyses). Second, the recovery of MCs was affected by the type of sediment but did not clearly correlate with the content of organic carbon. These results suggest that the sorption of MCs onto inorganic materials such as clay minerals is probably a more important process than interactions of the MCs with organic sediment matter. Third, the structure of the MCs is another crucial factor that affects the sorption of MCs and their recovery from sediments. Hydrophilic MC-RR gave much lower recoveries (20.0-38.8%) than MC-YR (44.1-59.5%) or MC-LR (55.3-77.8%) from three different types of spiked sediments. Recovery results analysed with HPLC-DAD correlated well with ELISA analyses. Further, extraction with 5% acetic acid in 0.2% TFA-methanol was used for analyses of MCs in 34 natural sediment samples collected from Brno reservoir (Czech Republic) from April to October 2005. Concentrations of MCs in sediments ranged from 0.003 to 0.380 mu g/g sediment d.m. (ELISA results) or 0.016-0.474 mu g/g d.m. (HPLC results). These values are equivalent to 0.63-96.47 mu g/L of sediment (ELISA) or 4.67-108.68 mu g/L (HPLC), respectively. Concentrations of sediment MCs showed both temporal and spatial variability, with the highest MC contents observed in the spring (April and May) and the lowest concentrations in July and August. Our results demonstrate the suitability of the methods described here for studying the occurrence, fate and ecological role of MCs in the aquatic environment.01/2006; 385:1545-1551.