Bojan Sedmak

Bojan Sedmak
National Institute of Biology - Nacionalni inštitut za biologijo | NIB · Genetic toxicology and cancer biology

Scientific Councillor, Professor

About

44
Publications
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1,219
Citations

Publications

Publications (44)
Article
The increasing occurrence of cyanobacterial blooms in water bodies is a serious threat to the environment. Efficient in-lake treatment methods for the control of cyanobacteria proliferation are needed, their in-vivo detection to obtain a real-time response to their presence, as well as the information about their physiological state after the appli...
Poster
Full-text available
INNOVATIVE TECHNOLOGY FOR CYANOBACTERIAL BLOOM CONTROL DEVELOPMENT OF ROBOTIC VESSEL AND DEMONSTRATION OF ITS OPERATION INTEGRATED REAL-TIME INFORMATION ON THE SPATIOTEMPORAL DISTRIBUTION OF CYANOBACTERIAL OCCURRENCE AND TARGETED CYANOBACTERIAL GROWTH CONTROL
Conference Paper
Full-text available
The effects of electrochemical oxidation of a laboratory-grown toxic cyanobacterial culture of Microcystis aeruginosa PCC 7806 were tested. In our experiment, the electrolytic cell, equipped with boron-doped diamond electrodes was used. This type of electrode is known to have the highest potential of forming hydroxyl radicals. 500ml of the sample,...
Article
Cyanobacterial blooms are global phenomena that can occur in calm and nutrient-rich (eutrophic) fresh and marine waters. Human exposure to cyanobacteria and their biologically active products is possible during water sports and various water activities, or by ingestion of contaminated water. Although the vast majority of harmful cyanobacterial prod...
Conference Paper
Full-text available
Koseze pond is an anthropogenic, shallow water body, located on the outskirts of Ljubljana and an important element in terms of the natural and cultural heritage of the city. It shows eutrophic to hypereutrophic status. Despite its biodiversity and the potential for massive development of toxic cyanobacteria, it is not included in the national moni...
Conference Paper
Full-text available
The management of fresh water bodies imposes to evaluate the presence of contaminants of both biological and anthropogenic origin and phytoplankton monitoring as the key element in the assessment of environmental water quality. Poor water quality and consequent cyanobacterial blooms represent a remarkable environmental risk with negative economic e...
Article
Full-text available
One of the unwanted consequences of water eutrophication is an excessive growth of cyanobacteria, also known as blue-green algae. The phenomenon is known as harmful cyanobacterial bloom (HCB). When episodes of HCB end the cyanobacterial toxins are released into the environment with adverse effects: fish deaths, human poisoning with water, water not...
Article
Full-text available
Due to the stratospheric ozone depletion, several organisms will become exposed to increased biologically active UVB (280-320 nm) radiation, not only at polar but also at temperate and tropical latitudes. Bloom forming cyanobacteria are exposed to UVB radiation on a mass scale, particularly during the surface bloom and scum formation that can persi...
Article
We investigated the capability of Microcystis aeruginosa to cause apoptosis by pursuing morphological, molecular and physiological characteristics after exposure to H2O2. Microcystis proliferation was only weakly affected after exposure to 150 mu M H2O2 but cell numbers decreased dramatically after exposures of 250 and 325 mu M H2O2. Cells exposed...
Article
The reasons for the apparent dominance of the toxic cyanobacterium Microcystis sp., reflected by its massive blooms in many fresh water bodies, are poorly understood. We show that in addition to a large array of secondary metabolites, some of which are toxic to eukaryotes, Microcystis sp. secretes large amounts of fibrous exopolysaccharides that fo...
Article
Full-text available
The aim of this study was to detect cyanobacterial cytoskeletal elements and the cytoskeletal framework using immunostaining with anti-bovine α-tubulin mouse monoclonal antibodies. After strong permeabilization of axenic cyanobacterial cell lines, the cytoskeleton elements become visible in all cells. A mild cell permeabilization procedure allows t...
Article
Full-text available
Toxic cyanobacterial blooms are a rich source of metabolites having a variety of biological activities. Two main groups of cyclic peptides, depsipeptides and ureido linkage-containing peptides, reportedly inhibit serine peptidases. We characterised their inhibitory properties against selected peptidases and investigated their influence on cell viab...
Article
Full-text available
The presence of planktopeptin BL1125, anabaenopeptin B and anabaenopeptin F, two types of "non-toxic" cyclic peptide produced in bloom forming cyanobacteria, can provoke lysis of different non-axenic Microcystis aeruginosa cell lines via the induction of virus-like particles. The resulting particles are also able to infect the axenic M. aeruginosa...
Article
Full-text available
Background. The information of the overall production of major cyanobacterial cyclic peptides in a water body is essential for risk assessment and for the prediction of future development of the bloom. A procedure that gives a review of both toxic and non-hepatotoxic hydrophilic cyclic peptide production is important to evaluate the ecological cond...
Article
Full-text available
Background. Microcystins (MCs) are cyclic heptapeptides that are considered to be liver specific toxins. They are potent tumour promoters and recent studies indicate that they are also genotoxic. In this study we measured DNA damage in lymphocytes, liver, kidney (cortex and medulla), lung, spleen and brain cells of male Fisher F344 rats that were e...
Article
Full-text available
Dissolved microcystins (MCs) are regularly present in water dominated by microcystin-producing, bloom-forming cyanobacteria. In vitro experiments with environmentally feasible concentrations (5 x 10(-7) M) of the three most common microcystins, MC-LR, MC-RR, and MC-YR, revealed that they influence the metabolism of different representative phytopla...
Article
Two novel microcystins, seco[d-Asp(3)]microcystin-RR (1) and [d-Asp(3),d-Glu(OMe)(6)]-microcystin-RR (2), along with the known [d-Asp(3)]microcystin-RR (3), were isolated from a Planktothrix rubescens toxic bloom collected in Lake Bled, Slovenia. The structures were deduced using one- and two-dimensional NMR techniques, ESIMS/CID/MS analysis, and M...
Article
Three new protease inhibitors, planktopeptin BL1125, planktopeptin BL843 and planktopeptin BL1061 were isolated, along with three known compounds, anabaenopeptin A, anabaenopeptin B and anabaenopeptin F from the hydrophilic extract of Planktothrix rubescens. The planar structure of the new compounds was determined by homonuclear and inverse-heteron...
Article
Full-text available
Acute intoxication with MC-LR induces cytoskeletal alterations, apoptosis and necrosis of hepatocytes resulting in intrahepatic hemorrhage. Preliminary results have shown that chronic treatment of rats with intraperitoneal injections of sublethal doses of microcystins MC-LR and MC-YR could induce not only liver, but also kidney injuries. We aimed t...
Article
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 c...
Article
Full-text available
Microcystins are naturally occurring hepatotoxins produced by strains of Microcystis aeruginosa. They are involved in promoting primary liver tumours and a previous study showed that they might also be tumour initiators. In this study we demonstrate that microcystin-LR (MCLR) at doses that were not cytotoxic (0.01-1 microg/ml), induced dose and tim...
Article
Full-text available
The microcystins (MCs) LR and YR are hepatotoxins produced by some species of freshwater cyanobacteria. Only a few reports on the acute nephrotoxicity of MCs have been published to date. Here we investigate the effects on rat kidneys of chronic administration of relatively low doses of MC LR and MC YR. Male Wistar rats were injected every second da...
Article
Full-text available
The subchronic effects of cyanobacterial lyophilizate (CL) containing microcystins on liver were investigated in female New Zealand rabbits. Sterilised CL containing microcystins was injected i.p. Liver toxicity was assessed by histological examination of liver samples. Non-invasive magnetic resonance imaging (MRI) of liver was also performed in or...
Article
Full-text available
The presence of high microcystin concentrations in cyanobacterial blooms additionally affects species diversity. Blooms with high toxin contents can reach higher cell densities, which is also demonstrated by microcystin cell contents. In vitro experiments show that microcystins influence phytoplankton proliferation. The action is strongly dependent...
Article
Cyanobacterial blooms are frequent in the North-Eastern region of Slovenia, where the agricultural activities are intensive, resulting in higher water eutrophication. In a two year monitoring program we identified eighteen blooms of cyanobacteria, fifteen being hepatotoxic by intraperitoneal mouse bioassay. The approximate LD100 varied from 50-1000...
Article
Background and purpose: Shellfish toxicity is frequent in the Northern Adriatic due to the presence of toxic dinoflagellates. It usually breaks out in late summer continues in autumn and can also persist in winter. The fish market offers a wide variety of organisms from different marine environments that are able to accumulate toxic phytoplankton a...
Article
The immunogenicity of a pore-forming polypeptide, equinatoxin II, from the sea anemone Actinia equina was studied after attenuation of the toxin's lethal and cytolytic activity by autologous polar lipids. In BALB/c mice, the lipid-inactivated toxin was used to raise specific antibodies and cellular immunity, resulting in in vivo protection. In vitr...
Article
The dynamics of the toxicity of the musselMytilus galloprovincialis was compared between two different shellfish farms, 5 km apart, but using the same cultivation technique. The main differences concerned the freshwater influx and the open aspect to the Gulf of Trieste. It is suggested that a deep closed bay and abundant fresh water inflow are the...
Article
The dynamics of the toxicity of the musselMytilus galloprovincialis was compared between two different shellfish farms, 5 km apart, but using the same cultivation technique. The main differences concerned the freshwater influx and the open aspect to the Gulf of Trieste. It is suggested that a deep closed bay and abundant fresh water inflow are the...
Article
The cytotoxic and cytolytic effects of equinatoxin II (EqT II) from the sea anemone Actinia equina L. were studied on exponentially growing and synchronized V-79-379 A cell line in culture. The cell viability test and the determination of the cytolytic effect by cell counting confirmed both cytotoxic and cytolytic activity of EqT II. Additionally,...

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Project (1)
Project
Demonstration of robotic floating platform for detection and control of cyanobacteria http://lifestopcyanobloom.arhel.si/