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1	Iron biology of schistosomes: molecular characterisation and vaccine potential of iron homeostasis proteins Amber Glanfield Unknown Date (has links) Iron is a trace element required for a range of metabolic reactions in virtually all living organisms. Studies of prokaryotes, plants, yeast, and vertebrates have established detailed information on iron uptake and the role iron plays in metabolic processes. Iron is an essential growth requirement of schistosomes in vitro and schistosomes also express the highly conserved iron storage protein ferritin. However, studies into how this iron is taken up by the parasite have been neglected. This study aims to identify molecules involved in iron uptake and homeostasis in the human parasite Schistosoma japonicum. I have characterised two isoforms of a divalent metal transporter (DMT), a membrane bound protein of schistosomes. These DMTs have significant homology to the mammalian DMT1, the primary ferrous iron uptake protein of the intestinal brush border. Both schistosome isoforms displayed functional iron uptake by rescuing growth in a yeast strain deficient in iron uptake (fet3fet4). Interestingly schistosome DMT1 was localised to the tegument and not the gastrodermis of adult parasites, suggesting surface mediated iron uptake across the tegument. In physiological conditions, iron is abundant as largely insoluble ferric iron and hence ferric reductases are an essential component of iron uptake, reducing iron to the soluble ferrous form. Cytochromes b561 (Cyts-b561) are a family of ascorbate reducing transmembrane proteins found in most eukaryotic cells. Recent observations that Cyts-b561 may be involved in iron metabolism have opened new perspectives for their physiological function. Here, I have identified a new member of the cytochrome b561 family in Schistosoma japonicum that localises to the tegument of this trematode. Expression of the SjCytb561 in a Saccharomyces cerevisiae mutant that lacks plasma membrane ferrireductase activity (fre1fre2) was able to rescue the growth defect in iron deficient conditions, suggesting involvement in iron metabolism. Plasma membrane ferrireductase activities were also quantified using intact transformed yeast cells. These data further support the hypothesised tegumental uptake of host iron. Further, I have identified a putative schistosome transferrin. In mammals, transferrin is a glycoprotein responsible for binding and transporting iron in the bloodstream and delivering iron into cells via a specific transferrin receptor. Preliminary characterisation of the schistosome transferrin sequence has revealed it does not contain all the conserved amino acid residues associated with iron binding, with conservation seen only in the C-terminal lobe, not in both the N and C-lobes observed in mammalian transferrins. This difference makes it unclear whether the schistosome transferrin shares functional homology with its mammalian counterpart. In addition, no transferrin receptor has been identified to support an iron trafficking and uptake function, nor would this function be expected in an acoelomate organism. Further characterisation and localisation of this protein is required to elucidate its biological significance and function. The tegumental location of both the SjDMT1 and the SjCytb561 for the uptake of host iron make it possible to consider these proteins as potential vaccine candidates. A preliminary vaccination study with these proteins elicited only low to moderate protection from infection, and further studies are required to fully assess their potential. The data presented in this thesis provide evidence for surface-mediated uptake of iron by adult schistosomes, and represent the first characterisation of iron uptake proteins in any helminths. These studies show a novel method of iron uptake in schistosomes, and contribute to our understanding of how these parasites are able to survive and thrive by scavenging nutrients, in this case iron, from the host organism. Schistosomiasis Iron Uptake Transferrin Vaccine ferric reductase
2	Development of new formulations of EDDHA/Fe³+ chelates and methodologies for their analysis based on NMR Alcañiz Lucas, Sara 11 December 2015 (has links) No description available. EDDHA o,o-EDDHA/Fe³+ o,p-EDDHA/Fe³+ Isomers Meso d,l-racemic NMR Ferric reductase oxidase (FRO) Edafología y Química Agrícola
3	Gemmata spp., pathogènes opportunistes ? / Gemmata spp., opportunistic pathogens? Aghnatios, Rita 29 September 2015 (has links) Au cours de notre travail de thèse, nous avons isolé la seconde espèce du genre Gemmata, Gemmata massiliana à partir de l'eau d'un réseau hospitalier. Nous avons étudié sa distribution dans deux réseaux hospitaliers à Marseille après avoir mis au point une PCR temps réel spécifique. Les échantillons d'eau filtrée recueillis dans l'unité de soins intensifs et des échantillons d'eau non-filtrée recueillis dans des fauteuils dentaires, des réservoirs et des points d'utilisation ont été testés. Au total, 2,2% des échantillons d'eau filtrée ont été positifs contre 11,3% des points d'eau non-filtrée, dont 14,1% des fauteuils dentaires, 5,9% des points d'utilisation et 8% des échantillons de réservoirs. Les patients hospitalisés peuvent être exposés à G. massiliana par l'intermédiaire de l'eau de l'hôpital. Le rôle des Gemmata comme pathogènes opportunistes méritait donc d'être exploré. Nous avons détecter de l'ADN de Planctomycetes dans 2 échantillons testés de sang de patients leucémiques, mais toutes les tentatives d'isolement ont échoué. Nous avons travaillé à améliorer les conditions de culture des Gemmata. Notre analyse du génome de G. obscuriglobus et de G. massiliana a indiqué l'absence de certains composants essentiels dans la voie du métabolisme du fer, les sidérophores et l'enzyme ferriréductase. La culture des Gemmata en présence du surnageant filtré d'Escherichia coli contenant les sidérophores et l'enzyme ferriréductase, améliorait significativement la croissance des Gemmata par rapport à la culture sur une gélose standard. L'amélioration des techniques de culture nous permettra par la suite de mieux aborder l'étude de pathogénicité. / During our thesis work, we isolated a second Gemmata species; Gemmata massiliana from a hospital water network in France. We studied its distribution in two hospitals water network in Marseille after developing a real-time PCR. Filtered water collected at the intensive care unit and non-filtered water collected from dental chairs, tanks and usage points were tested. In total, 2.2% filtered water samples tested positive versus 11.3% non-filtered points, including 14.1% dental chairs, 5.9% usage points and 8% tank specimens. We concluded that hospitalized patients may be exposed to G. massiliana through hospital water, especially the non-filtered water. The role of Gemmata as opportunistic pathogen deserved to be explored. Additionally, using 16S rRNA gene-based specific Planctomycetes primers, enabled us to detect DNA Planctomycetes in 2 of 100 blood samples tested of leukemic patients. In one of the positive specimens DNA of a Gemmata-related bacterium was detected, unfortunately all isolation attempts proved futile. Therefore, we worked at improving the Gemmata species culture conditions to optimize their isolation from clinical samples. Genome analysis indicated that Gemmata organisms do not encode some essential iron pathway components, siderophores and ferric reductase. On this basis, we have shown that culture of G. obscuriglobus and G. massiliana in the presence of Escherichia coli filtered supernatant containing siderophores and extracellular ferric reductase, significantly improved the two species growth compared to their culture on a standard agar. The improvement of Gemmata species culture techniques will allow us to better address the pathogenicity study. Gemmata massiliana Gemmata obscuriglobus Planctomycetes Pathogène Réseau hospitalier Patients Fer Sidérophores Ferriréductase Gemmata massiliana Gemmata obscuriglobus Planctomycetes Pathogen Hospital water network Patients Iron Siderophores Ferric reductase
4	Identifikation von Genen und Mikroorganismen, die an der dissimilatorischen Fe(III)-Reduktion beteiligt sind / Isolation of Genes and Microorganisms Involved in Dissimilatory Fe(III)-Reduction Özyurt, Baris 21 January 2009 (has links) No description available. 500 Naturwissenschaften allgemein Mathematics and Computer Science Metagenomik dissimilatorische Fe(III)-Reduktion Dissimilatory iron reduction DIR dissimilatory oxido-reduction of iron dissimilatory iron(III) reduction metal reduction ferricironreduction microbial iron respiration bacterial respiration microorganisms for energy production dissimilatory iron reducing bacteria dissimilatory metal reducing bacteria DMRB energy production electricity energy transduction microbial electricity electron donor electron acceptor electron transfer carbon source carbohydrate mannit mannitol biofilm mineral mineral formation microbial degradation ribosomal proteins cytochromes hypothetical proteins enzymes oxidation reduction ferric iron iron oxide Fe(II) Fe(III) soluble iron insoluble iron ferric reductase activity iron mineral formation mineralisation <i>E. coli</i> Escherichia coli environmental microorganisms life in extreme environments uncultivable bacteria soil microbial ecology anaerobic growth anaerobic incubation environmental sequences environmental DNA DNA extraction functional screening metagenomic metagenome meta-genome microbial ecology environmental genomics soil metagenome BACs sequencing bioinformatics microbial communities 16S rRNA phylogenetics 30 42.30 42.30 58.30 42.49 58.30 42.13 RA W

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