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The effect of plastic and methanol on the loss of microcystin-LR from solution was analysed by HPLC with photodiode array detection (HPLC-PDA). With plastic disposable pipette tips, the loss from an aqueous microcystin-LR (MC-LR) solution was 4.2% per tip operation. Using the same pipette tip, four operations were required to completely saturate a single tip with toxin. MC-LR attached to plastic pipette...
A novel and promising method of microcystin-LR (mcyst-LR) degradation is reported. The decomposition of this cyanobacterial toxin using Fenton reagent has been observed with very low initial concentrations of H 2 O 2 and Fe 2+ (Fe 3+ ) in the reaction mixture. Mcyst-LR was isolated from a laboratory culture of Microcystis aeruginosa PCC 7813. The initial concentration...
Microcystin-LR, a specific and potent hepatotoxin, was tested for its effects on loach embryo-larval and juvenile development. The results of this study showed that loach embryos were more sensitive when exposed to microcystin-LR at a later than at an earlier stage of development. Juveniles were far less sensitive to MC-LR than were embryos and larvae. Mortality and developmental abnormality were...
Two metabolites of microcystin-LR glutathione conjugate and, microcystin–cysteine conjugate, as well as microcystin-RR (MCRR) are less toxic than microcystin-LR (MCLR). In the present study, we investigated why these compounds are weakly toxic in comparison with MCLR, as the reason is still unknown and no systematic study has so far been carried out for a clarification of this issue. Although they...
The potential for the carry-over of the cyanobacterial toxin, microcystin-LR, from feed to milk was assessed using four Holstein–Friesian cows in a 4 week feeding trial. Two cows were used as control and the other two dosed daily at increasing weekly concentrations of microcystins from zero to a maximum dosage of 13μg toxin kg −1 d −1 (or 7.4mg toxin day −1 ). The absence of...
In this study, the effect of a multiple function reagent—ferrate on the removal of microcystins-LR (MCLR) from freeze-dried Planktothrix sp. was investigated. The toxin was easily decomposed by oxidation with ferrate, and the removal efficiency depended on the dosage of ferrate, pH, and contact time. Simultaneously the reduction product Fe(OH) 3 after ferrate oxidation could flocculate the...
We have demonstrated previously that microcystin-LR promoted some renal alterations using the isolated perfused rat kidney preparation. However, these effects were not proved to be direct or indirect. The aim of the current work is to examine the renal effects promoted by supernatants from rat macrophages stimulated with microcystin-LR and the role of inflammatory mediators. Peritoneal macrophages...
Toxin-producing cyanobacteria pose a worldwide health threat to humans and animals due to their increasing presence in both drinking and recreational waters. Little work has, however, been done on a preventative therapy for anyone at risk of exposure to cyanobacterial toxins. The potential benefits of dietery supplementation of selenium, an antioxidant, to protect against the mouse liver injury induced...
Toxin-producing cyanobacteria pose a worldwide health threat to humans and animals due to their increasing presence in both drinking and recreational waters. Detection of microcystins in water generally relies on specialised equipment and a delay of several days for transport and analysis. Little work has, however, been done on establishing a simple, cost-effective and sensitive plant bioassay for...
Microcystin-LR is the most frequently studied cyclic heptapeptide produced by different genera of cyanobacteria and is hepatotoxic to livestock and human populations. The adverse effects of microcystin-LR on morphology and cytoskeletal elements in different stages of early embryonal development have been studied in vitro. Embryos and whole embryo cultures have been exposed to microcystin-LR (10-100...
The freshwater, bloom-forming cyanobacterium (blue-green alga) Microcystis aeruginosa produces a peptide hepatotoxin, which causes the damage of animal liver. Recently, toxic Microcystis blooms frequently occur in the eutrophic Dianchi Lake (300 km 2 and located in the South-Western of China). Microcystin-LR from Microcystis in Dianchi was isolated and purified by high performance liquid chromatography...
The increasing presence of toxic cyanobacteria in drinking and recreational water bodies, and their potential to impact on human and animal health is cause for concern. Recent work suggests that apoptosis plays a major role in the toxic effects induced by microcystin-LR (MCLR) in the gastrointestinal tract; however, the biochemical pathway remains elusive. Exposure of CaCo2, a human colon carcinoma...
Chronic and subchronic toxicity from exposure to microcystins, cyclic hepatotoxic heptapeptides from cyanobacteria, receives increasing attention as a public human health biohazard. So far, the effects of microcystin on fish have been studied mainly in adults, rather than during early life stages. Limitations of direct ambient exposure experiments to fish egg have resulted from the difficult access...
Fed and fasted juvenile goldfish Carassius auratus (30 g body weight) were injected intraperitoneally (i.p.) with microcystin-LR (MC-LR) (125 μg/kg body weight) to determine the effect of alimentary status on the hepatic toxicity of MC-LR. The toxin accumulation pattern was similar in both fed and fasted treatments. MC-LR accumulated during the first 48 h post-injection and decreased significantly...
Microcystin-LR (MCLR) has been associated with the development of gastrointestinal complaints in people ingesting cyanobacterial bloom contaminated water. The symptoms usually present a day or two after exposure raising questions as to the toxic effects of MCLR on the gastrointestinal tract. This study investigated the apoptotic effect of ip administered MCLR over time on the duodenum, jejenum and...
This study reports a laboratory investigation of the degradation of microcystin-LR using Fenton (Fe 2+ +H 2 O 2 ) and Photo-Fenton processes. The effect of hydrogen peroxide concentration on the Fenton reaction rate was investigated at constant Fe 2+ concentrations. It was observed that at low concentrations of hydrogen peroxide (0.25-0.5 mM), the extent of...
We showed previously that exposure to microcystin-LR causes renal toxic effects in isolated perfused rat kidney, and that inflammatory mediators from supernatants of macrophages stimulated by microcystin-LR are involved in this process. The aim of this research was to examine water and electrolytes secretion in vivo, induced by microcystin-LR and supernatant of macrophages stimulated for this toxin...
The cyclic peptide toxins microcystins and nodularins are the most common and abundant cyanotoxins present in diverse water systems. They have been the cause of human and animal health hazards and even death. Development of suitable chemoprotectants against microcystin is essential considering the human health importance. In the present study, three agents cyclosporin-A (10mg/kg), rifampin (25mg/kg)...
Toxic effects of microcystin-LR were studied in hepatocytes isolated from fed and fasted juvenile goldfish Carassius auratus (30g body weight). The hepatocytes were incubated with 10μgMC-LRl −1 during 4h. MC-LR induces no effect in terms of cell number and viability. The toxin accumulation pattern was different in fed and fasted treatments. MC-LR accumulated more rapidly in ‘fasted’ cells...
The effect of acute exposure of intraperitoneal injection of microcystin-LR (MCLR) on antioxidant enzymes and lipid peroxidation has been studied in liver and kidney of rats. Rats were treated with two doses, i.e. 100 and 150μg of pure MCLR/kg body weight or saline solution. The enzyme activities of glutathione peroxidase (GSH-Px), glutathione reductase (GR), superoxide dismutase (SOD) and catalase...
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