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Search Results: 1 - 10 of 138544 matches for " Troco K. Mihali "
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A Putative Gene Cluster from a Lyngbya wollei Bloom that Encodes Paralytic Shellfish Toxin Biosynthesis
Troco K. Mihali,Wayne W. Carmichael,Brett A. Neilan
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0014657
Abstract: Saxitoxin and its analogs cause the paralytic shellfish-poisoning syndrome, adversely affecting human health and coastal shellfish industries worldwide. Here we report the isolation, sequencing, annotation, and predicted pathway of the saxitoxin biosynthetic gene cluster in the cyanobacterium Lyngbya wollei. The gene cluster spans 36 kb and encodes enzymes for the biosynthesis and export of the toxins. The Lyngbya wollei saxitoxin gene cluster differs from previously identified saxitoxin clusters as it contains genes that are unique to this cluster, whereby the carbamoyltransferase is truncated and replaced by an acyltransferase, explaining the unique toxin profile presented by Lyngbya wollei. These findings will enable the creation of toxin probes, for water monitoring purposes, as well as proof-of-concept for the combinatorial biosynthesis of these natural occurring alkaloids for the production of novel, biologically active compounds.
Characterisation of the paralytic shellfish toxin biosynthesis gene clusters in Anabaena circinalis AWQC131C and Aphanizomenon sp. NH-5
Troco K Mihali, Ralf Kellmann, Brett A Neilan
BMC Biochemistry , 2009, DOI: 10.1186/1471-2091-10-8
Abstract: We describe the identification, annotation and bioinformatic characterisation of the putative paralytic shellfish toxin biosynthesis clusters in an Australian isolate of Anabaena circinalis and an American isolate of Aphanizomenon sp., both members of the Nostocales. These putative PST gene clusters span approximately 28 kb and contain genes coding for the biosynthesis and export of the toxin. A putative insertion/excision site in the Australian Anabaena circinalis AWQC131C was identified, and the organization and evolution of the gene clusters are discussed. A biosynthetic pathway leading to the formation of saxitoxin and its analogues in these organisms is proposed.The PST biosynthesis gene cluster presents a mosaic structure, whereby genes have apparently transposed in segments of varying size, resulting in different gene arrangements in all three sxt clusters sequenced so far. The gene cluster organizational structure and sequence similarity seems to reflect the phylogeny of the producer organisms, indicating that the gene clusters have an ancient origin, or that their lateral transfer was also an ancient event. The knowledge we gain from the characterisation of the PST biosynthesis gene clusters, including the identity and sequence of the genes involved in the biosynthesis, may also afford the identification of these gene clusters in dinoflagellates, the cause of human mortalities and significant financial loss to the tourism and shellfish industries.Paralytic shellfish poisoning (PSP) is a syndrome acquired through the consumption of contaminated shellfish or drinking water. Its symptoms include numbness and ascending paralysis followed by respiratory arrest [1]. Toxicity is mediated by a group of toxins collectively referred to as paralytic shellfish toxins (PSTs) or saxitoxins (STX).The global occurrence of PSTs coupled with their chemical stability and high toxicity, presents a formidable problem for marine and freshwater regulating bodies, while detrimenta
Neurotoxic Alkaloids: Saxitoxin and Its Analogs
Maria Wiese,Paul M. D’Agostino,Troco K. Mihali,Michelle C. Moffitt,Brett A. Neilan
Marine Drugs , 2010, DOI: 10.3390/md8072185
Abstract: Saxitoxin (STX) and its 57 analogs are a broad group of natural neurotoxic alkaloids, commonly known as the paralytic shellfish toxins (PSTs). PSTs are the causative agents of paralytic shellfish poisoning (PSP) and are mostly associated with marine dinoflagellates (eukaryotes) and freshwater cyanobacteria (prokaryotes), which form extensive blooms around the world. PST producing dinoflagellates belong to the genera Alexandrium, Gymnodinium and Pyrodinium whilst production has been identified in several cyanobacterial genera including Anabaena, Cylindrospermopsis, Aphanizomenon Planktothrix and Lyngbya. STX and its analogs can be structurally classified into several classes such as non-sulfated, mono-sulfated, di-sulfated, decarbamoylated and the recently discovered hydrophobic analogs—each with varying levels of toxicity. Biotransformation of the PSTs into other PST analogs has been identified within marine invertebrates, humans and bacteria. An improved understanding of PST transformation into less toxic analogs and degradation, both chemically or enzymatically, will be important for the development of methods for the detoxification of contaminated water supplies and of shellfish destined for consumption. Some PSTs also have demonstrated pharmaceutical potential as a long-term anesthetic in the treatment of anal fissures and for chronic tension-type headache. The recent elucidation of the saxitoxin biosynthetic gene cluster in cyanobacteria and the identification of new PST analogs will present opportunities to further explore the pharmaceutical potential of these intriguing alkaloids.
On the Chemistry, Toxicology and Genetics of the Cyanobacterial Toxins, Microcystin, Nodularin, Saxitoxin and Cylindrospermopsin
Leanne Pearson,Troco Mihali,Michelle Moffitt,Ralf Kellmann,Brett Neilan
Marine Drugs , 2010, DOI: 10.3390/md8051650
Abstract: The cyanobacteria or “blue-green algae”, as they are commonly termed, comprise a diverse group of oxygenic photosynthetic bacteria that inhabit a wide range of aquatic and terrestrial environments, and display incredible morphological diversity. Many aquatic, bloom-forming species of cyanobacteria are capable of producing biologically active secondary metabolites, which are highly toxic to humans and other animals. From a toxicological viewpoint, the cyanotoxins span four major classes: the neurotoxins, hepatotoxins, cytotoxins, and dermatoxins (irritant toxins). However, structurally they are quite diverse. Over the past decade, the biosynthesis pathways of the four major cyanotoxins: microcystin, nodularin, saxitoxin and cylindrospermopsin, have been genetically and biochemically elucidated. This review provides an overview of these biosynthesis pathways and additionally summarizes the chemistry and toxicology of these remarkable secondary metabolites.
Déconstruction, auto-immunité, précarité. De l’intraduisible politique chez Derrida
Ciprian Mihali
Meta : Research in Hermeneutics, Phenomenology and Practical Philosophy , 2011,
Abstract: In this paper we try to analyze that which in Jacques Derrida’s philosophical and political thinking is called “political untranslatable” through a triple movement described in the late texts: a deconstruction movement, which can be found in his entire works and which, in terms of political philosophy, aims to identify in politics an untranslatable remain that cannot be contained in any binary categories of philosophy; an autoimmune movement, which stretches and complicates deconstruction and which expresses the capacity of western political philosophy concepts to obliterate themselves from their inside. The political untranslatable, in terms of autoimmunity, signifies the difficulty, if not impossibility of transferring these concepts from a historical experience to another. Finally, the precariousness movement completes deconstruction and autoimmune vocabulary and refers to the necessity of considering, in any philosophical composition, the fragility of political, economic or social structures of the globalized world in which we live. The political untranslatable is another name for the rest of our individual and collective lives that resist to any recovery in totalizing ideologies.
Hepatoprotective Effects of Berberis vulgaris L. Extract/β Cyclodextrin on Carbon Tetrachloride–Induced Acute Toxicity in Mice
Anca Hermenean,Cristina Popescu,Aurel Ardelean,Miruna Stan,Nicoleta Hadaruga,Ciprian-Valentin Mihali,Marieta Costache,Anca Dinischiotu
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13079014
Abstract: The present study investigated the capacity of formulated Berberis vulgaris extract/β-cyclodextrin to protect liver against CCl 4-induced hepatotoxicity in mice. Formulated and non-formulated extracts were given orally (50 mg/kg/day) to mice for 7 days and were then intra-peritoneally injected with 1.0 mL/kg CCl 4 on the 8th day. After 24 h of CCl 4 administration, an increase in the levels of apartate-amino-transferase (AST), alanine-amino-transferase (ALT) and malondialdehyde (MDA) was found and a significant decrease in superoxide-dismutase (SOD), catalase (CAT), glutathione (GSH) and glutathione-peroxidase (GPx) levels could be detected. This was accompanied by extended centrilobular necrosis, steatosis, fibrosis and an altered ultrastructure of hepatocytes. Pre-treatment with formulated or non-formulated extract suppressed the increase in ALT, AST and MDA levels and restored the level of antioxidant enzymes at normal values. Histopathological and electron-microscopic examination showed milder liver damage in both pre-treated groups and the protective effect was more pronounced after the formulated extract was administered. Internucleosomal DNA fragmentation induced by CCl 4 was reduced in the group which received non-formulated extract and absent in the group which received formulated extract. Taken together, our results suggest that Berberis vulgaris/β-cyclodextrin treatment prevents hepatic injury induced by CCl 4 and can be considered for further nutraceutical studies.
The Constrained Mean-Semivariance Portfolio Optimization Problem with the Support of a Novel Multiobjective Evolutionary Algorithm  [PDF]
K. Liagkouras, K. Metaxiotis
Journal of Software Engineering and Applications (JSEA) , 2013, DOI: 10.4236/jsea.2013.67B005

The paper addresses the constrained mean-semivariance portfolio optimization problem with the support of a novel multi-objective evolutionary algorithm (n-MOEA). The use of semivariance as the risk quantification measure and the real world constraints imposed to the model make the problem difficult to be solved with exact methods. Thanks to the exploratory mechanism, n-MOEA concentrates the search effort where is needed more and provides a well formed efficient frontier with the solutions spread across the whole frontier. We also provide evidence for the robustness of the produced non-dominated solutions by carrying out, out-of-sample testing during both bull and bear market conditions on FTSE-100.

Design of a Cantilever - Type Rotating Bending Fatigue Testing Machine  [PDF]
K. K. Alaneme
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.1011078
Abstract: This research is centered on the design of a low–cost cantilever loading rotating bending fatigue testing machine using locally sourced materials. The design principle was based on the adaptation of the technical theory of bending of elastic beams. Design drawings were produced and components/materials selections were based on functionality, durability, cost and local availability. The major parts of the machine: the machine main frame, the rotating shaft, the bearing and the bearing housing, the specimen clamping system, pulleys, speed counter, electric motor, and dead weights; were fabricated and then assembled following the design specifications. The machine performance was evaluated using test specimens which were machined in conformity with standard procedures. It was observed that the machine has the potentials of generating reliable bending stress – number of cycles data; and the cost of design (171,000 Naira) was lower in comparison to that of rotating bending machines from abroad. Also the machine has the advantages of ease of operation and maintenance, and is safe for use.
K. Метешк?н,Х. Раковський
Information Technologies and Learning Tools , 2010,
Abstract: The results of Bologna process are investigated. It is underlined that theoretical – methodological bases of the Bologna process have been poorly developed. A scheme for master’s education both on requirements of separate states, and on requirements of EU is offered. Досл джуються п дсумки Болонського процесу. П дкреслю ться, що слабко розроблен теоретико-методолог чн основи Болонського процесу. Пропону ться схема навчання маг стр в, як для потреб окремих держав, так для потреб С.
Х.В. Раковський,Н.Х. Раковська,K.О. Метешк?н
Information Technologies and Learning Tools , 2010,
Abstract: The process and phenomena connected with the initiation of new methodological paradigm of the scientific and educational management in Ukraine has been investigated. The paradigm is conditioned by global tendencies of informatization, development of communicative means and integrative processes in education and science У статт досл джен процеси та явища, пов’язан з зародженням в Укра н ново методолог чно парадигми управл ння осв тою наукою, яка обумовлена глобальними тенденц ями нформатизац , розвитком комун кац йних засоб в, а також нтеграц йними процесами в осв т та науц .
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