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During the course of study on the detoxification of microcystins, the adsorption on sediments in the natural environment was investigated. Because it was very difficult to extract microcystins from sediments using conventional techniques, a physicochemical screening method, the MMPB (2-methyl-3-methoxy-4-phenylbutyric acid) method, including ozonolysis and mass spectrometric detection was developed...
An immunoassay based on the time-resolved fluorometry (TR-FIA) was developed for microcystins, cyanobacterial peptide hepatotoxins. The assay was performed in a competitive mode and it utilised the monoclonal antibodies raised against microcystin-LR, and a europium chelate of microcystin-LR as a competitive antigen. The sensitivity of the assay was 0.1μg/l. The detection method of TR-FIA was compared...
Chronic and subchronic toxicity from exposure to microcystins, cyclic peptide liver toxins from certain cyanobacteria, poses an important hazard, which has received little study. No in vivo information exists on accumulation and transfer of microcystin from the food chain to humans. This paper present results of a 3-year study that demonstrates bioaccumulation of microcystins by fish and potential...
The cyanobacterial toxins microcystins are known to affect a number of processes in plant tissues, and their presence in water used for irrigation may have considerable impact on the growth and development of crop plants. In this study, two plant bioassays were employed to investigate the phytotoxic effects of microcystins. A plant tissue culture assay revealed that the growth and chlorophyll content...
The occurrence of cyanobacteria in many water bodies where crayfish such as Procambarus clarkii are abundant leads to the possibility of toxin accumulation and food chain transfer. This paper describes the accumulation and depuration of microcystins from a microcystin and a non-microcystin producing strain of Microcystis aeruginosa, on the survivorship, growth and nutritional status of P. clarkii...
Microcystins (MC) are a group of amphiphatic peptide hepatotoxins and protein phosphatase inhibitors produced by certain cyanobacteria (blue-green algae). Microcystins are believed to require an active transport mechanism to penetrate the plasma membranes of animal cells. In this study the surface barostat technique showed that two more hydrophobic microcystins MC-LF, containing Leu and Phe, and MC-LW,...
Microcystins (MCYSTs) were isolated from surface water using reusable immunoaffinity columns. Individual MCYST were determined by high performance liquid chromatography equipped with a photo-diode array detector (HPLC-PDA, 200-300 nm). Subsequent analysis of the samples by liquid chromatography-electrospray ionization mass spectrometry (LC-ESMS) provided molecular weight information, which was used...
During the monitoring of toxic cyanobacteria in the Utinga Reservoir, which is the main drinking water supply for the city of Belem, PA, Brazil, a Radiocystis fernandoi strain (SPC714) was isolated. This non-axenic strain was submitted to a toxicity bioassay with mice and microcystin production analyzed by HPLC-DAD. The species was identified based on cultured and natural preserved material. Morphometric,...
Microcystins are naturally occurring hepatotoxic cyclic heptapeptides produced by some toxic freshwater cyanobacterial species. In this study, crude extract of toxic cyanobacterial blooms from Dianchi Lake in southwestern China was used to determine the effects of microcystins on rape (Brassica napus L.) and rice (Oryza sativa L.). Experiments were carried out on a range of doses of the extract (equivalent...
Microcystins (MC) produced by freshwater cyanobacteria are potent hepatotoxins. MC inhibit protein phosphatases (PP) 1 and 2A. MC and okadaic acid (OA), which is a similar PP inhibitor whereas it has a less affinity to PP1 than PP2A, behave similarly to primary culture hepatocytes, with inducements of phosphorylations of cytoskeleton, morphological changes and apoptosis. Although the distribution...
A water bloom of Planktothrix (Oscillatoria) rubescens was observed in a drinking water reservoir in central Spain in 2003. Microcystins where analysed by LC/ESI-MS in 21 samples collected from this reservoir in five different days between March and May. A demethylated variant of microcystin-RR was identified as the major microcystin in most samples. Trace levels of microcystin-LR, -RR and -YR were...
Depending on the class of microcystin the protein phosphatase inhibition assay shows different sensitivities to different classes of toxin. We have determined that the IC 50 values obtained from dose–response curves for the inhibition of the enzyme by micro-cystin LR, nodularin, YR, and RR were 2.2, 1.8, 9 and 175nM, respectively. When equimolar amounts of these toxins were determined by the...
The seasonal sampling of irrigation or drinking water reservoirs in the province of Murcia (SE Spain) in the hydrological year 2000–2001 revealed the presence of intracellular microcystins in the benthic cyanophyte communities throughout the year. The total microcystin levels, as measured by HPLC, were relatively high but lower than others published for planktonic communities of the European continent...
Experiments were conducted to investigate the degradation of microcystin-RR in order to assess the effectiveness and feasibility of the combined UV/H 2 O 2 catalytic system for purification of water polluted by microcystins. The operating parameters such as hydrogen peroxide dosage, pH value, UV light intensity, initial concentration of microcystin-RR and reaction time were evaluated,...
Toxic cyanobacteria in public water supply reservoirs represent a serious health risk as they can release potent cyanotoxins into the water. In the present study we analyzed surface water collected from the Utinga Reservoir, the main source of drinking water for the city of Belém-PA, in order to characterize the reservoir's cyanobacterial biota and to determine the toxicity of these organisms and...
Toxic cyanobacteria are contaminants of surface waters worldwide. Microcystins are some of the most commonly detected cyanotoxins. Biological evidence of human exposure may be difficult to obtain due to limitations associated with cost, laboratory capacity, analytic support, and expertise. We investigated the application of an enzyme-linked immunosorbant assay (ELISA) to detect microcystins in human...
Phytoplanktivorous bighead carp were injected i.p. with extracted microcystins (mainly MC-RR and -LR) at two doses, 200 and 500MC-LReq.μgkg −1 bw, and the changes in extractable MCs in liver and in the ultrastructure of hepatocytes were studied at 1, 3, 12, 24 and 48h after injection. Quantitative and qualitative determinations of MCs in the liver were conducted by HPLC and LC-MS, respectively...
The effects of microcystins (MCs) from cyanobacterial cells on the enzymatic activities of acid and alkaline phosphatases (ACP and ALP) from liver, kidney and gill tissues, and the histopathological changes in freshwater Tilapia fish (Oreochromis sp.) were investigated under laboratory conditions. Fish were exposed to cyanobacterial cells (60.0μg MC-LR/fish per day) through their diet at different...
The present study describes for the first time the species composition and toxicity of benthic cyanobacteria forming mats on the Nile River and irrigation canal sediments in Egypt. A total of 19 species of cyanobacteria were isolated from these mats during this study. The toxicity of the extracts of these species was investigated using Artemia salina assay, mouse bioassay and enzyme linked immunosorbent...
Microcystins (MCYSTs) are a family of related cyclic heptapeptides produced by several genera and species of blue-green algae (cyanobacteria). MCYSTs are potent and specific inhibitors of the serine threonine family of protein phosphatases, especially PP1 and PP2A. MCYSTs inhibit a liver's protein phosphatase by forming a covalent linkage between MCYSTs' Mdha residue and the phosphatase's cysteine...
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