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Grazing of the copepod Cyclops vicinus on toxic Microcystis aeruginosa : potential for controlling cyanobacterial blooms and transfer of toxins

Mohamed Z. A., Bakr A. A., Ghramh H. A.

Oceanological and Hydrobiological Studies

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2018

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Vol. 47, No. 3

296--302

EN

Grazing of zooplankton on phytoplankton may contribute to a reduction of harmful cyanobacteria in eutrophic waters. However, the feeding capacity and interaction between zooplankton and toxic cyanobacteria vary among grazer species. In this study, laboratory feeding experiments were designed to measure the grazing rate of the copepod Cyclops vicinus on Microcystis aeruginosa and the potential microcystin (MC) accumulation in the grazer. Copepods were fed a mixed diet of the edible green alga Ankistrodesmus falcatus and toxic M. aeruginosa for 10 days. The results showed that C. vicinus efficiently ingested toxic Microcystis cells with high grazing rates, varying during the feeding period (68.9–606.3 Microcystis cells animal-1 d-1) along with Microcystis cell density. Microcystis cells exhibited a remarkable induction in MC production under grazing conditions with concentrations 1.67–12.5 times higher than those in control cultures. Furthermore, C. vicinus was found to accumulate MCs in its body with concentrations increasing during the experiment (0.05–3.21 μg MC animal-1). Further in situ studies are needed to investigate the ability of Cyclops and other copepods to assimilate and detoxify MCs at environmentally relevant concentrations before deciding on the biocontrol of Microcystis blooms by copepods.

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Functional investigation of MiR92b-3p for diagnosis and miRNA-based cure in chemically induced liver injury in fish: a project description

Brzuzan P., Woźny M., Florczyk M.

Environmental Biotechnology

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2016

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Vol. 12, No. 2

40--42

EN

The continued lack of knowledge concerning the molecular background of adverse effects caused by microcystin-LR (MC-LR) is surprising. This toxin requires additional attention, not only for its ability to cause acute poisoning, but also for its ability to initiate cancer in acute doses, and potentially, to promote cancer via chronic exposure to low concentrations in drinking water. Our recent studies on whitefish (Coregonus lavaretus) revealed that long-term exposure to MC-LR resulted in severe liver injury, followed by regeneration of the liver and its unexpected resilience to further toxin uptake. These effects were accompanied by perturbations of hepatic microRNAs (miRNAs) that have target genes involved in cytoskeletal remodeling, cell metabolism, cell cycle regulation, and apoptosis. Among the most pronounced individual alterations, the reduction of MiR92b-3p expression was the most remarkable, and we suggest roles for the miRNA in the aberrant processes of liver cells. This project addresses potential involvement of MiR92b-3p in the as yet unknown regulatory network of MC-induced hepatotoxicity in fish. After a suite of biochemical, physiological, anatomical, and transcriptomic analyses in vitro and in vivo, we will show how MiR92b-3p works in a damaged liver and which processes it targets. Finally, the research will confirm if and how MiR92b-3p can be targeted therapeutically. We expect it to be shown effective enough to pave a way for its use as a tool for treatment of liver damage in fish. What is more, the RNA-based silencing technique that will be used should yield exciting data for our understanding of the system-level biology of vertebrates.

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Neurotoxicity of cyanobacterial toxins

Florczyk M., Łakomiak A., Woźny M., Brzuzan P.

Environmental Biotechnology

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2014

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Vol. 10, No. 1

26--43

EN

Eutrophication of marine and fresh waters can lead to excessive development of cyanobacterial blooms, which may contain strains that produce toxins. These toxins are secondary metabolites which can accumulate in the food chain and contaminate drinking water, thus posing a potential threat to the health of humans and aquatic organisms. These toxins include a variety of compounds with different mechanisms; this review focuses on the neurotoxicity of microcystin and other cyanotoxins. Although the hepatotoxic action of microcystins is commonly known, its neurotoxic effects have also been described, e.g. oxidative stress, cytoskeletal changes and changes in protein phosphatase activity. These effects have been partially explained by the discovery in the blood brain barrier of the same membrane transporters involved in microcystins hepatotoxic mechanisms. Additionally, this paper reviews other cyanotoxins that are known or suspected to target cholinergic synapses and voltage gated channels, including anatoxin a, anatoxin a(s), antillatoxins, cylindrospermopsin, homoanatoxin a, jamaicamide, kalkitoxin and saxitoxins. The neurotoxic and cytotoxic effects of the cyanotoxins discussed here are of particular interest because of their pharmacological potential. This review also discusses the potential of these compounds to serve as drugs for cancer and central nervous system failure.

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Relationship between Cyanobacterial bloom composition and anatoxin-a and microcystin occurrence in the eutrophic dam reservoir (SE Poland)

Pawlik-Skowrońska B., Skowroński T., Pirszel J., Adamczyk A.

Polish Journal of Ecology

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2004

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Vol. 52, nr 4

479-490

EN

Long-lasting cyanobacterial blooms were observed over summer periods 2001-2003 in the highly eutrophic dam reservoir (Zemborzycki Reservoir near Lublin, SE Poland) loaded with nitrogen and phosphorus by the river Bystrzyca. Chloriphyll a content and water transparence reached in summer periods 2002-2003 average values 115-129 [mi]g l^-1 and 0.5 m, respectively. The blooms consisted of eight taxa of Cyanobacteria occurring in different proportions: Aphanizomenon flos-aquae, Anabaena circinalis, Anabaena spiroides, Anabaena flos-aquae, Planktothrix agardhii, Microcystis aeruginosa, Microcystis viridis, Microcystis wesenbergii. At decreased average water temperature and increased concentration of dissolved ammonium-nitrogen in summer 2003, compared with two earlier years, a replacement of dominant Aph. flos-aquae to P. agardhii was observed. The total abundance of potential microcystin producers was positively correlated with the content of these hepatotoxins in the reservoir water. First time in Poland, mass occurrence of Anabaena strains producing anatoxin-a was observed. Anatoxin-a concentration in the reservoir water was positively correlated with total abundance of 3 taxa of Anabaena. It was no such correlation with Aph. flos-aquae.

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Badanie efektywności usuwania toksyn sinicowych w procesie uzdatniania wody na przykładzie systemu produkcyjno-przesyłowego Sulejów-Łódź

Kabziński A. K. M., Grabowska H.

Gospodarka Wodna

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2003

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Nr 3

109-118

PL

W artykule przedstawiono wyniki pracy badawczej dotyczącej zastosowania ozonu do rozkładu mikrocystyny. Prace były prowadzone w systemie produkcyjno-przesyłowym zaopatrującym Łódź w wodę z zalewu sulejowskiego.

EN

The paper presents results of research work concerning application of ozone to decomposition of microcystin. The work has been carried out in the productivetransferring system supplying the town Łódź with water from the Sulejow reservoir.