Publications (32) View all
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Article: Molecular aspects of microcystin-induced hepatotoxicity and hepatocarcinogenesis.
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ABSTRACT: It is known that microcystin (MC) is a cyanotoxin that is a potent environmental inhibitor of eucariotic protein serine/threonine phosphatase 1 and 2A, both in vitro and in vivo. Consequently, these cyanobacterial toxins (MC-IARC group 2B carcinogen, MC extracts-group 3) are potent tumor promoters and there is an indication that they may also act as tumor initiators. The ability of microcystin-LR (MC-LR) to act as a tumor initiator is based on fact that it can induce DNA damage either by direct interaction with DNA or by indirect mechanisms through formation of reactive oxygen species (ROS). Both acute and chronic exposures, to either low or high doses of MC-LR, can activate apoptotic pathways. Chronic exposure to low concentrations of MC-LR contributes to increased risk for cancer development. Epidemiological studies, in certain areas of China, have suggested that MC is one of the risk factors for the high incidence of primary liver cancer (PLC). Recently, we have reported a correlation between PLC and cyanobacterial "blooms" in reservoirs used as a source for drinking water supply in central Serbia. It appears that the combination of acute and chronic exposures to both high and low doses of MC can lead to PLC initiation and promotion. Based on this, we propose that the requirement for the co-factors such as aflatoxin B1 and other mycotoxins, HBV, HCV, alcohol, etc. is not needed for initiation and promotion of PLC by MC-LR as was suggested earlier. The possible mechanisms of the genotoxicity of MC and its role as a hepatocarcinogen are outlined in this review. Furthermore, we show that the exposure of hepatocytes to MC can lead either to malignant proliferation or apoptosis.Journal of Environmental Science and Health Part C Environmental Carcinogenesis & Ecotoxicology Reviews 01/2010; 28(1):39-59. · 3.23 Impact Factor -
Article: Cyanobacterial toxins as allelochemicals with potential applications as algaecides, herbicides and insecticides.
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ABSTRACT: Cyanobacteria ("blue-green algae") from marine and freshwater habitats are known to produce a diverse array of toxic or otherwise bioactive metabolites. However, the functional role of the vast majority of these compounds, particularly in terms of the physiology and ecology of the cyanobacteria that produce them, remains largely unknown. A limited number of studies have suggested that some of the compounds may have ecological roles as allelochemicals, specifically including compounds that may inhibit competing sympatric macrophytes, algae and microbes. These allelochemicals may also play a role in defense against potential predators and grazers, particularly aquatic invertebrates and their larvae. This review will discuss the existing evidence for the allelochemical roles of cyanobacterial toxins, as well as the potential for development and application of these compounds as algaecides, herbicides and insecticides, and specifically present relevant results from investigations into toxins of cyanobacteria from the Florida Everglades and associated waterways.Marine Drugs 02/2008; 6(2):117-46. · 3.85 Impact Factor -
Article: Colonization of wheat Triticum vulgare L.) by N2‐fixing cyanobacteria: I. A survey of soil cyanobacterial isolates forming associations with roots
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ABSTRACT: summaryA variety of heterocystous, N2-fixing cyanobacteria, isolated from soils, were identified as members of the genera Nostoc, Anabaena and Cylindrospermum. These isolates were tested for their ability to form associations with the roots of wheat seedlings grown in liquid culture. Two types of associations were recognized: loose associations with cyanobacterial filaments growing between root hairs, which were typical of the Anabaena isolates, and tight associations of microcolonies in intimate association with the root surface, which were restricted to certain Nostoc isolates. Differences in nitrogenase activities of the free-living and associated cyanobacteria, together with the effects of added nitrate, indicate that nitrogenase activity may be influenced by the plant and/or its products.New Phytologist 04/2006; 118(3):477 - 483. · 6.64 Impact Factor -
Article: A new technique for examining the physical structure of Everglades floating periphyton mat
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ABSTRACT: The embedding and thin sectioning technique we describe allows for the routine examination of the distribution and numerical abundance of algae, cyanobacteria, bacteria, and calcareous deposits within intact Everglades floating periphyton mats (FPM's) using fluorescent microscopy of cryosections. The dominant species in FPM's was a calcareous filamentous cyanobacterium, Phormidium sp., that was found throughout the whole mat but which, together with Scytonema hofmannii, had a higher abundance in the bottom layer. Small coccoid cyanobacteria, characterized the upper surface and interior regions of the mat, which was also inhabited by diatoms. Of all diatoms, Mastagloia smithii var. smithii was the most abundant. Floating periphyton mat structure is characterized by high porosity and numerous void spaces.Nova Hedwigia 12/2003; 78(1-2):107-119. · 0.62 Impact Factor -
Article: Phycocyanin Induces Apoptosis and Enhances the Effect of Topotecan on Prostate Cell Line LNCaP.
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ABSTRACT: Abstract C-phycocyanin (C-PC) from Spirulina has been previously shown to have anticancer properties. Here, we report on anticancer activity of C-PC that was isolated from the novel cyanobacterium Limnothrix sp. 37-2-1. C-PC from this organism exhibited anticancer properties in our in vitro systems; however, the required doses were well above the range of anticancer drugs normally used. Therefore, we conducted several experiments to test whether lower-than-usual doses of the anticancer drug topotecan (TPT) can offer the same level of cytotoxic effects as normal doses when combined with C-PC. For this purpose, cytotoxicities of C-PC and TPT were tested using the LNCaP (prostate cancer) cells. We found that when only 10% of a typical dose of TPT was combined with C-PC, the cancer cells were killed at a higher rate than when TPT was used alone at full dose. Similarly, we were also able to detect an increased level of radical oxygen species (ROS) generation as well as an increase in activities of caspase-9 and caspase-3 when these two compounds were used in combination. Taken together, our findings suggest that combining C-PC from Limnothrix sp. with the lower dose of TPT can induce apoptosis through generation of ROS and activation of caspases. In that respect, we suggest that C-PC can potentially improve the efficacy of the currently available anticancer drug, and therefore diminish its harsh side effects in the patient.Journal of medicinal food 11/2012; · 1.39 Impact Factor
