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Trubitsyn, Denis. "Magnetosome formation in marine vibrio MV-1." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/7589.
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Marine vibrio MV-1 is a magnetotactic bacterium capable of aligning its cell in response to the Earth’s magnetic field. This ability is due to the presence of chainlike structures comprising magnetosomes, magnetite particles enclosed in a lipid membrane with associated proteins. Strain MV-1 differs from other, bettercharacterized strains of magnetotactic bacteria as the cells produce higher amounts of biomagnetite per litre of culture and its magnetosomes are unique in shape. This study investigates the presence and organisation of a gene cluster termed a “magnetosome island” within the genome of MV-1. In other magnetotactic bacteria this genomic region has been shown to contain many of the genes associated with magnetosome formation but has not been previously investigated for MV-1. One of the conserved fragments of this region was amplified using degenerate primers followed by extension of the known sequence using inverse PCR based technique and constructing plasmid libraries. Sequencing of the genome of strain MV-1 was accomplished as a part of this study. Significant work was done on comparison of the sequence quality obtained from SOLEXA, 454 and Sanger sequencing technologies. A number of obtained contigs were joined manually and the resulting sequence was automatically annotated using RAST. The obtained genome sequence of 3.6 Mb with a G+C content of 54.3 % was preliminarily analysed and used to search for magnetosome related genes. This study also analysed proteins associated with the magnetosomes of strain MV-1 using MALDI-TOF, LC-MS and Orbitrap mass spectrometry. These approaches allowed the identification of a number of proteins in the isolated magnetosome membrane fraction. Some of these proteins have very low similarity with other characterized proteins (either in magnetotactic bacteria or in other organisms). Another significant point is that genes that code for proteins such as MamR, MamK and MmsF were found to be present in several homologous copies within the “magnetosome island” of MV-1. Interestingly, this study shows that all homologous copies of these proteins were identified in the magnetosome membrane fraction. Generation of knock-out mutants of several specific genes from the “magnetosome island” of strain MV-1 was attempted; constructs were made based on suicide plasmids carrying the cre-lox or I-SceI systems. Despite altering numerous experimental conditions it was not possible to obtain conclusive evidence of the isolation of MV-1 transconjugants containing the integrated constructs. In order to investigate the cell localization of the magnetosome associated protein CAV30779.1, an enhanced green fluorescent protein (EGFP) fusion based construct was generated and transferred into MV-1 cells. The EGFP fluorescent protein fusions within the cells were detected by microscopy. This study reveals novel information about magnetosome formation in marine vibrio MV-1. The obtained results provide an important foundation for further investigation of this organism and contribute towards broadening the knowledge of the complex process of magnetosome formation in bacteria.
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Liu, Shuk Yi. "Encapsulation of magnetosomes in lipid vesicles." HKBU Institutional Repository, 2004. http://repository.hkbu.edu.hk/etd_ra/615.
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Lohsse, Anna. "Genome engineering of the magnetosome island in Magnetospirillum gryphiswaldense." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-181516.
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Bain, Jennifer. "Biomimetic synthesis of magnetosomes for biomedical application." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/12312/.
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Li, Yingjie. "Oxygen regulation and redox control of magnetosome biomineralization in Magnetospirillum gryphiswaldense." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-174813.
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Kiani, Alibagheri Bahareh [Verfasser], and Stefan [Akademischer Betreuer] Klumpp. "On structural properties of magnetosome chains / Bahareh Kiani Alibagheri ; Betreuer: Stefan Klumpp." Potsdam : Universität Potsdam, 2017. http://d-nb.info/1218402628/34.
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Mumper, Eric Keith. "Mixotrophic Magnetosome-Dependent Magnetoautotrophic Metabolism of Model Magnetototactic Bacterium Magnetospirillum magneticum AMB-1." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1551880645784717.
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Lohße, Anna [Verfasser], and Dirk [Akademischer Betreuer] Schüler. "Genome engineering of the magnetosome island in Magnetospirillum gryphiswaldense / Anna Lohße. Betreuer: Dirk Schüler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1069743704/34.
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Juodeikis, Rokas. "Engineering membranes in Escherichia coli : the magnetosome, LemA protein family and outer membrane vesicles." Thesis, University of Kent, 2016. https://kar.kent.ac.uk/61062/.
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Magnetosomes are membranous organelles found in magnetotactic bacteria (MTB). The organelle consist of ferromagnetic crystals housed within a lipid bilayer chained together by an actin-like filament and allows MTB to orient within magnetic fields. The genetic information required to produce these organelles has been linked to four different operons, encoding for 30 genes. These membranous organelles and the magnetic minerals housed within have various biotechnological applications, therefore enhanced recombinant production of such structures in a model organism holds significant potential. The research described in this thesis is focuses on the production of recombinant magnetosomes in the model organism Escherichia coli. Cloning the genes involved in the generation of the organelle individually or in various combinations resulted in the construction of over 100 different plasmids, compatible with the model organism. SDS-PAGE and electron microscopy analysis was used to characterise E. coli cells harbouring these constructs. The observation of electron dense particles, arranged in a chain structure, show that magnetosome generation in the model organism is possible, but is highly dependent on the growth conditions used. The need for specific growth conditions is later backed up by the analysis of the maturation of the cytochrome c proteins involved in magnetosome biomineralisation, which can only be correctly processed under certain conditions. Individual production of two different magnetosome proteins, MamQ or MamY, allowed the generation of various membranous structures in E. coli observed in 48.9% and 56.2% of the whole population of cells respectively. Combinations of these with MamI, MamL or MamB in a variety of combinations led to a variation in the phenotype observed. Bioinformatics analysis of MamQ led to the discovery of a novel membrane restructuring protein family, the LemA protein family, present in a broad range of bacteria. Four different LemA proteins from Bacillus megaterium, Clostridium kluyveri, Brucella melitensis or Pseudomonas aeruginosa were then produced in E. coli and the analysis of the resulting strains revealed the presence of novel intracellular membranous structures which vary in size, form and localisation. Furthermore, when attempts were made to target these proteins for the modification of the outer membrane, a mechanism for increased outer membrane vesicle generation was serendipitously discovered and different effects of these proteins were once again observed. Together, the results described shows good evidence for recombinant magnetosome production in E. coli and opens a new avenue of membrane engineering in this commonly used organism. Such membranous structures have various biotechnological applications, such as enhanced metabolic engineering potential or specialised lipid vesicle production.
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Mannoubi, Soumaya. "Caractérisation de MamK et Mamk-like les "actins-like" responsables de l'alignement des magnétosomes chez Magnetsirillum magneticum AMB-1." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4004.
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Les bactéries magnétotactiques (MTB) ont la capacité de s'orienter dans un champ magnétique grâce à un organite procaryote constitué d'un nanocristal magnétique biominéralisé et entouré d'une membrane biologique : le magnétosome. La synthèse de cet organite est un processus complexe contrôlé génétiquement par une série de gènes spécifiques aux MTB (les gènes mam) qui sont regroupés sur le chromosome bactérien. Chez la souche modèle Magnetospirillum magneticum AMB-1 cet ensemble de gènes forme un îlot génomique (MAI) auquel s'ajoute un second groupe distinct de 7 gènes homologues aux gènes mam (gènes mam-like) récemment identifié dont le rôle physiologique est très peu caractérisé. Parmi les produits des gènes mam, MamK est impliqué dans l'alignement des magnétosomes. Cette « actin-like » prokaryote qui forme des filaments selon un processus ATP-dépendant a été caractérisée ces dernières années. Dans le MIS de AMB-1, un gène homologue mamK-like a été identifié. Ainsi différentes approches pluridisciplinaires ont été mises en place pour comprendre le rôle de MamK et MamK-like. L'expression des gènes du MIS a été quantifiée. Les souches dépourvues des gènes mamK et mamK-like ainsi que le double mutant ont été obtenues puis phénotypées par différentes techniques d'imagerie. Les interactions entre les deux protéines ont été également testées. Enfin, les deux protéines ont été et leurs propriétés biochimiques caractérisées. L'ensemble de ces données nous permet de proposer un modèle selon lequel MamK et MamK-like participeraient tous deux à l'alignement des magnétosomes bactériens, vraisemblablement par la formation de filaments hybridesMagnetotactic bacteria (MTB) have the ability to orient in a magnetic field through a prokaryotic organelle composed of a magnetic nanocrystal surrounded by a biological membrane: the magnetosome. The synthesis of this organelle is a genetically complex process controlled by a series of specific genes (mam genes) grouped together on the bacterial chromosome. In the strain model Magnetospirillum magneticum AMB-1 this set of genes form a genomic island (MAI) and a second distinct group of seven genes homologous to mam genes (mam-like genes) recently identified. The physiological role of this islet magnetosome (MIS) is very little characterized to date.Among the products of mam genes, MamK is involved in the alignment of the magnetosomes. This « actin-like » which forms prokaryote filaments according an ATP - dependent process has been characterized in recent years. In the MIS of AMB-1, a homologous gene mamK-like was identified. And various multidisciplinary approaches have been developed to understand the role of MamK and MamK-like. The MIS gene expression was quantified. The strains lacking genes of mamK, mamK-like and the obtained of double mutant were then phenotyped by different imaging techniques. The interactions between the two proteins were also tested. Finally, the two proteins were overexpressed and their biochemical properties characterized. All of these data allows us to propose a model whereby MamK and MamK-like participate in both the alignment of bacterial magnetosomes, presumably by the formation of hybrid filaments
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Kolinko, Isabel [Verfasser], and Dirk [Akademischer Betreuer] Schüler. "Homologous and heterologous expression of magnetosome operons from Magnetospirillum gryphiswaldense / Isabel Kolinko ; Betreuer: Dirk Schüler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/111907391X/34.
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Nevondo, Walter. "Engineering bacterial magnetic nanoparticles." Thesis, University of the Western Cape, 2013. http://hdl.handle.net/11394/4432.
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>Magister Scientiae - MScMagnetosomes, produced by magnetotactic bacteria (MTB), are the most attractive alternative source of non-toxic biocompatible magnetic nanoparticles (MNPs). A magnetosome contains Fe2O4 magnetite with properties superior to MNPs synthesized by the traditional chemical route. However, synthesis of magnetosomes on large scale has not been achieved yet because magnetotactic bacteria are fastidious to grow. In addition, magnetosomes are generally “soft” magnetic materials which can only be used for some applications, while other applications require “hard” magnetic materials. Here at the Institute of Microbial Biotechnology and Metagenomic (IMBM), a study is being conducted on cloning and expression of the magnetosome gene island (MIA), the genetic machinery for magnetosome formation, in an easy to culture E. coli strain. The magnetic properties of the magnetosome can be manipulated by doping with divalent metals such as Ni2+ or Co2+ for a variety of applications. The specific objective of this study was to genetically engineer E. coli strains which accumulate intracellular Ni2+ or Co2+ in order to manipulate the magnetic properties of the magnetosomes. Three E. coli mutants and a wild type strain were transformed with high affinity Ni2+ or Co2+ uptake genes and evaluated for intracellular accumulation at different medium concentrations of NiCl2 or CoCl2. Cellular iron and magnesium were also evaluated because iron is the major component of the magnetosome and magnesium is important for cell growth. The wild type strain, EPI 300 habouring Ni2+ uptake permease the hoxN gene or Co2+ uptake ABC type transporter cbiKMQO operon was found to accumulate the most intracellular Ni2+ or Co2+ in medium conditions most likely to induce magnetosome formation and magnetite manipulation. This strain can be used to co-express the MIA and Ni2+ or Co2+ uptake gene for mass production of magnetosome with altered magnetic properties.
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Uebe, René. "Mechanism and regulation of magnetosomal iron uptake and biomineralization in magnetospirillum gryphiswaldense." Diss., Ludwig-Maximilians-Universität München, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-153441.
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Lang, Claus. "Magnetosome-specific expression of chimeric proteins in Magnetospirillum gryphiswaldense for applications in cell biology and biotechnology." Diss., lmu, 2009. http://nbn-resolving.de/urn:nbn:de:bvb:19-105376.
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Li, Yingjie [Verfasser], and Dirk [Akademischer Betreuer] Schüler. "Oxygen regulation and redox control of magnetosome biomineralization in Magnetospirillum gryphiswaldense / Yingjie Li. Betreuer: Dirk Schüler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1059069822/34.
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Grouzdev, D. S., M. V. Dziuba, D. V. Kurek, and A. I. Ovchinnikov. "The Method for Protein Display on the Surface of Bacterial Magnetic Nanoparticles." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35488.
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In this study, we present a comprehensive approach to the design and development of magnetosomes with antibodies immobilized on their surface by integration in membrane in vitro. Designed fusion proteins Mbb and Mistbb consisted of anchor proteins and BB-domains of Staphylococcus aureus protein A as IgG-binding region were used for development of IgG-binding magnetosomes. The magnetosome membrane protein MamC and membrane protein of Bacillus subtilis Mistic were selected as anchor proteins. Using Response Surface Methodology (RSM), the high level of fusion proteins integration into bacterial nanopar-ticles membrane was achieved. IgG-binding magnetosomes obtained through this strategy could serve as multifunctional platform for displaying various types of antibodies. Such systems could be applied as theranostic agents.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35488
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Boucher, Marianne. "Magnetosomes used as biogenic MRI contrast agent for molecular imaging of glioblastoma model." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS234/document.
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Ces travaux de thèse s'inscrivent dans le contexte de l'imagerie moléculaire, qui vise à adapter les traitements de pathologies à la variabilité de chaque patient, grâce à l'imagerie de biomarqueurs cellulaires ou moléculaires. En particulier, l'imagerie par résonance magnétique (IRM) couplée a des nanoparticules d’oxyde de fer innovantes pourrait permettre de relever un tel défi.Cette thèse se concentre sur l'étude d'une nouvelle classe d'agents de contraste à base d'oxyde de fer pour l'IRM à haut champ magnétique. En effet, les magnétosomes sont des vésicules d’oxyde de fer produites naturellement par des bactéries appelées bactéries magnétotactiques. De telles bactéries synthétisent ces vésicules magnétiques et les alignent comme l'aiguille d'une boussole, ce qui facilite leur navigation dans les sédiments. Ces bactéries produisent donc des magnétosomes aux propriétés magnétiques exceptionnelles: 50 nm de diamètre, mono-cristallin, mono-domaine magnétique et avec une haute magnétisation à saturation. De plus, une grande variété de souches bactériennes existent dans la nature, et produisent, avec une grande stabilité, des magnétosomes dont la taille, la forme, et le contenu chimique, sont déterminés génétiquement. Enfin, les magnétosomes sont naturellement porteurs d'une membrane bi-lipidique dont le contenu est également déterminé génétiquement. Récemment, le contenu protéique de la membrane des magnétosomes a été mis à jour, ouvrant la voie à la fonctionnalisation de cette dernière par fusion des gènes codant pour des protéines présentes abondamment à la membrane avec ceux codant pour un peptide d’intérêt.Ainsi, l'utilisation de ces micro-organismes pour produire des agents de contraste innovants et fonctionnalisés pour l'imagerie moléculaire par IRM, et les applications qui en découlent, ont été étudiées pendant cette thèse. La production et l'ingénierie des magnétosomes a été réalisée par nos collègues du Laboratoire de Bioénergétique Cellulaire (LBC, CEA Cadarache), et sera présentée et discutée. Des magnétosomes sauvages ont d'abord été caractérisés en tant qu'agents de contraste pour l'IRM. De tel magnétosomes présentent des propriétés contrastantes très intéressantes pour l'IRM, ce qui a été validé à la fois in vitro puis in vivo. L'étude de faisabilité de la production d'un agent de contraste pour l'imagerie moléculaire par IRM en une seule étape, à l'aide des bactéries magnétotactiques, a été réalisée sur un modèle de souris porteur de glioblastome. Sachant par la littérature que les cellules tumorales sur-expriment les intégrines anb3, et que ces dernières peuvent être ciblées par le peptide RGD, il a été choisi de produire des magnétosomes exprimant le peptide RGD à leur membrane. L'affinité de tels magnétosomes pour les cellules tumorales U87 a été vérifiée in vitro, et démontré in vivo par IRM puis cross-validé par histologieThis work takes place in the context of molecular imaging, which aims at tailoring medical treatments and therapies to the individual context by revealing molecular or cellular phenomenon of medical interest in the less invasive manner. In particular, it can be acheived with MRI molecular imaging using engineered iron-oxide contrast agent.This PhD thesis focuses on the study of a new class of iron-oxide contrast agent for high field MRI. Indeed, magnetosomes are natural iron-oxide vesicles produced by magnetotactic bacteria. These bacteria synthesized such magnetic vesicles and ordered them like a nano-compass in order to facilitate their navigation in sediments. This explains why magnetosomes are awarded with tremendous magnetic properties: around 50 nm, mono-crystalline, single magnetic domain and high saturation magnetization. Furthermore, a wide variety of bacterial strains exist in nature and size and shape of magnetosomes are highly stable within strain and can be very different between strains. Finally, magnetosomes are naturally coated with a bilipidic membrane whose content is genetically determined. Lately, researchers have unravelled magnetosomes membrane protein contents, opening the way to create functionnalized magnetosomes thanks to fusion of the gene coding for a protein of interest with the gene coding for an abundant protein at magnetosomes membrane.A new alternative path using living organisms to tackle the production of engineered high effciency molecular imaging probes have been investigated with magnetotactic bacteria in this PhD. The production and engineering of magnetosomes have been carried out by our partner, the Laboratoire de Bio-energétique Cellulaire (LBC, CEA Cadarache), and will be presented and discussed. We then characterized magnetosomes as contrast agent for high field MRI. We showed they present very promising contrasting properties in vitro, and assessed this observation in vivo by establishing they can be used as effcient blood pool agent after intravenous injection. Afterward, we applied the concept of producing engineered MRI molecular imaging probes in a single step by bacteria, to a mouse model of glioblastoma. Knowing that tumor cells can be actively targeted through anb3 integrins by RGD, we produced RGD functionnalized magnetosomes. We started from showing these RGD magnetosomes have a good affnity for U87 cell in vitro, prior to demonstrate it in vivo on orthotopic U87 mouse model. This in vivo affnity being fnally cross-validated with histology
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Raschdorf, Oliver [Verfasser], and Dirk [Akademischer Betreuer] Schüler. "Genetic and ultrastructural analysis of magnetosome membrane biogenesis and biomineralization in Magnetospirillum gryphiswaldense / Oliver Raschdorf ; Betreuer: Dirk Schüler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2016. http://d-nb.info/1156533732/34.
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Bell, Jennifer Mary Louise. "A study of the actin-like MamK from Magnetospirillum gryphiswaldense MSR-1 and its role in magnetosome organisation." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/13862.
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Magnetospirillum gryphiswaldense MSR-1 is one of a number of species to have a genetic system enabling the biomineralisation of iron in c. 40 linearly arranged organelles within its cell. These magnetosomes are believed to be selectively advantageous to cells as a biological compass that helps to minimise the search for nutrients from a three dimensional environment to a one dimensional environment. The gene, mamK, is part of the genetic system involved in the production of magnetosomes and encodes an amino acid sequence with homology to actin and bacterial cell cycle proteins, such as MreB, ParM and FtsA. Results discussed in this thesis outline in vitro characterisation of recombinant Magnetospirillum gryphiswaldense MSR-1 MamK. MamK was expressed in Escherichia coli with and without an N-terminal His-tag and/or a C-terminal GFP domain or a C-terminal cysteine mutation. In all cases, inclusion bodies were formed. MamK was purified from inclusion bodies and resolubilised. Purified MamK was found to self-associate, as indicted by light-scattering assays, in the presence of divalent cations. In contrast to actin and some other bacterial actin-like proteins polymerisation did not appear to require the presence of NTP; however, ATP and GTP was required for purification by ion exchange column chromatography. Polymerisation did not result in a detectable change in tryptophan fluorescence. Depolymerisation was not readily induced by dilution, but slow depolymerisation occurred in the presence of EGTA, as judged by a decrease in light scattering. Microscopy studies showed that formation of large two-dimensional sheets. These results are consistent with in vivo microscopic studies of MamK where polymerisation has been observed.
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Toro-Nahuelpan, Mauricio [Verfasser], and Dirk [Akademischer Betreuer] Schüler. "Magnetoskeleton : Elucidating cytoskeletal elements involved in magnetosome chain assembly and segregation of Magnetospirillum gryphiswaldense / Mauricio Toro-Nahuelpan ; Betreuer: Dirk Schüler." Bayreuth : Universität Bayreuth, 2018. http://d-nb.info/1225397545/34.
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Katzmann, Emanuel. "Cryo-electron tomographic and genetic analysis of the actin-like MamK cytoskeleton during magnetosome chain assembly and division of Magnetospirillum gryphiswaldense." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-153319.
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Uebe, René [Verfasser], and Dirk [Akademischer Betreuer] Schüler. "Mechanism and regulation of magnetosomal iron uptake and biomineralization in magnetospirillum gryphiswaldense / René Uebe. Betreuer: Dirk Schüler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2012. http://d-nb.info/1031381155/34.
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Rioux, Jean-Baptiste. "Du génome à la protéine : caractérisation d'une nouvelle actin-like chez Magnetospirillum Magneticum AMB-1." Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22016/document.
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Les bactéries magnétotactiques synthétisent des organites spécialisés appelés magnétosomes. Ils sont composés d'un cristal magnétique entouré d'une membrane et de protéines spécifiques. Arrangés en chaîne dans la bactérie, ils orientent la bactérie dans le champ magnétique, ce qui simplifierait sa recherche d’environnements microaérophiles. Dans le génome de toutes les souches magnétotactiques séquencées, l'îlot génomique de magnétotaxie contient les gènes impliqués dans la formation des magnétosomes. Nous avons procédé à l’annotation du génome de la souche magnétotactique marine QH-2 et montré que la région du génome codant les gènes de la magnétotaxie n'est, dans ce cas, pas définie comme un îlot génomique, bien qu’elle ait été acquise par transfert latéral de gènes. Dans le génome de M. magneticum AMB-1, nous avons identifié un nouvel îlot génomique de petite taille que nous avons appelé l'îlet de magnétotaxie portant 7 gènes homologues à des gènes liés à la synthèse des magnétosomes. Pour répondre à la question de la fonction biologique de cet îlet génomique, nous avons examiné le rôle de l'un des sept gènes, mamK-like. MamK-like exprimée dans E. coli forme des filaments, comme observé pour MamK. La polymérisation in vitro des deux protéines est également comparable, mais présente des différences structurales. En outre, nous démontrons que mamK-like est transcrite dans AMB-1 de type sauvage et dans le mutant ΔmamK. Par immuno-marquage, nous montrons la présence d'un filament dans le mutant ΔmamK, probablement dû à MamK-like. Nous émettons l'hypothèse que ce filament contribue à maintenir l’organisation en chaîne des magnétosomes dans la souche mutanteMagnetotactic bacteria synthesise specialised organelles called magnetosomes. They are composed of a magnetic crystal surrounded by a lipid bilayer and specific proteins. Arranged in chains, they orient magnetotactic bacteria in the geomagnetic field, thereby simplifying their search for their microaerophilic environments. In each sequenced magnetotactic strain, the magnetotaxis genomic island contains the genes involved in magnetosomes formation. Our annotation of the newly sequenced genome of the magnetotactic strain QH-2 shows that the region coding the magnetotaxis genes is not a genomic island, though it has been acquired by lateral genes transfer. In the genome of M. magneticum AMB-1 we identified a new, small genomic island we termed the magnetotaxis islet, encoding 7 genes homologous to genes related to the magnetosomes synthesis. To assess the question of the biological function of this genomic islet, we further investigated the role of one of the seven genes, mamK-like. Filaments were observed in E. coli cells expressing MamK-like-Venus fusion by fluorescence microscopy. In vitro polymerization of both isoforms is comparable, though some differences are present at the structural level. In addition, we demonstrate that mamK-like is transcribed in AMB-1 wild-type and ΔmamK mutant cells. Immunolabelling assay using an anti-MamK antibody reveals the presence of a filament in the ΔmamK mutant. We hypothesise that this filament is due to MamK-like and that it helps maintaining a chain-like organisation of magnetosomes in the mutant strain
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Faivre, Damien. "Biological and biomimetic formation and organization of magnetic nanoparticles." Thesis, Universität Potsdam, 2014. http://opus.kobv.de/ubp/volltexte/2014/7202/.
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Biological materials have ever been used by humans because of their remarkable properties. This is surprising since the materials are formed under physiological conditions and with commonplace constituents. Nature thus not only provides us with inspiration for designing new materials but also teaches us how to use soft molecules to tune interparticle and external forces to structure and assemble simple building blocks into functional entities. Magnetotactic bacteria and their chain of magnetosomes represent a striking example of such an accomplishment where a very simple living organism controls the properties of inorganics via organics at the nanometer-scale to form a single magnetic dipole that orients the cell in the Earth magnetic field lines.
My group has developed a biological and a bio-inspired research based on these bacteria. My research, at the interface between chemistry, materials science, physics, and biology focuses on how biological systems synthesize, organize and use minerals. We apply the design principles to sustainably form hierarchical materials with controlled properties that can be used e.g. as magnetically directed nanodevices towards applications in sensing, actuating, and transport.
In this thesis, I thus first present how magnetotactic bacteria intracellularly form magnetosomes and assemble them in chains. I developed an assay, where cells can be switched from magnetic to non-magnetic states. This enabled to study the dynamics of magnetosome and magnetosome chain formation. We found that the magnetosomes nucleate within minutes whereas chains assembles within hours. Magnetosome formation necessitates iron uptake as ferrous or ferric ions. The transport of the ions within the cell leads to the formation of a ferritin-like intermediate, which subsequently is transported and transformed within the magnetosome organelle in a ferrihydrite-like precursor. Finally, magnetite crystals nucleate and grow toward their mature dimension.
In addition, I show that the magnetosome assembly displays hierarchically ordered nano- and microstructures over several levels, enabling the coordinated alignment and motility of entire populations of cells. The magnetosomes are indeed composed of structurally pure magnetite. The organelles are partly composed of proteins, which role is crucial for the properties of the magnetosomes. As an example, we showed how the protein MmsF is involved in the control of magnetosome size and morphology. We have further shown by 2D X-ray diffraction that the magnetosome particles are aligned along the same direction in the magnetosome chain. We then show how magnetic properties of the nascent magnetosome influence the alignment of the particles, and how the proteins MamJ and MamK coordinate this assembly. We propose a theoretical approach, which suggests that biological forces are more important than physical ones for the chain formation. All these studies thus show how magnetosome formation and organization are under strict biological control, which is associated with unprecedented material properties. Finally, we show that the magnetosome chain enables the cells to find their preferred oxygen conditions if the magnetic field is present.
The synthetic part of this work shows how the understanding of the design principles of magnetosome formation enabled me to perform biomimetic synthesis of magnetite particles within the highly desired size range of 25 to 100 nm. Nucleation and growth of such particles are based on aggregation of iron colloids termed primary particles as imaged by cryo-high resolution TEM. I show how additives influence magnetite formation and properties. In particular, MamP, a so-called magnetochrome proteins involved in the magnetosome formation in vivo, enables the in vitro formation of magnetite nanoparticles exclusively from ferrous iron by controlling the redox state of the process. Negatively charged additives, such as MamJ, retard magnetite nucleation in vitro, probably by interacting with the iron ions. Other additives such as e.g. polyarginine can be used to control the colloidal stability of stable-single domain sized nanoparticles.
Finally, I show how we can “glue” magnetic nanoparticles to form propellers that can be actuated and swim with the help of external magnetic fields. We propose a simple theory to explain the observed movement. We can use the theoretical framework to design experimental conditions to sort out the propellers depending on their size and effectively confirm this prediction experimentally. Thereby, we could image propellers with size down to 290 nm in their longer dimension, much smaller than what perform so far.Biologische Materialien wie Knochen, Muscheln und Holz wurden von den Menschen seit den ältesten Zeiten verwendet. Diese biologisch gebildeten Materialien haben bemerkenswerte Eigenschaften. Dies ist besonders überraschend, da sie unter physiologischen Bedingungen und mit alltäglichen Bestandteilen gebildet sind. Die Natur liefert uns also nicht nur mit Inspiration für die Entwicklung neuer Materialien, sondern lehrt uns auch, wie biologische Additiven benutzen werden können, um einfache synthetische Bausteine in funktionale Einheiten zu strukturieren. Magnetotaktischen Bakterien und ihre Kette von Magnetosomen sind ein Beispiel, wo einfache Lebewesen die Eigenschaften von anorganischen Materialien steuern, um sich entlang den magnetischen Feldlinien der Erde zu orientieren. Die von den Bakterien gebildeten Magnetosomen sind von besonderem Interesse, da mit magnetischen Eisenoxid-Nanopartikeln in den letzten zehn Jahren einer Vielzahl von Bio-und nanotechnologischen Anwendungen entwickelt worden sind. In dieser Arbeit stelle ich eine biologische und eine bio-inspirierte Forschung auf der Grundlage der magnetotaktischen Bakterien vor. Diese Forschung verbindet die neuesten Entwicklungen von Nanotechnik in der chemischen Wissenschaft, die neuesten Fortschritte der Molekularbiologie zusammen mit modernen Messverfahren. Mein Forschungsschwerpunkt liegt somit an der Schnittstelle zwischen Chemie, Materialwissenschaften, Physik und Biologie. Ich will verstehen, wie biologische Systeme Materialien synthetisieren und organisieren, um Design-Prinzipien zu extrahieren, damit hierarchischen Materialien mit kontrollierten Eigenschaften nachhaltig gebildet werden.
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Katzmann, Emanuel [Verfasser], and Dirk [Akademischer Betreuer] Schüler. "Cryo-electron tomographic and genetic analysis of the actin-like MamK cytoskeleton during magnetosome chain assembly and division of Magnetospirillum gryphiswaldense / Emanuel Katzmann. Betreuer: Dirk Schüler." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2012. http://d-nb.info/1031381058/34.
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Keutner, Christoph [Verfasser], Carsten [Akademischer Betreuer] Westphal, and Wolfgang [Gutachter] Rhode. "Der direkte Blick auf die Magnetosomen-Kette: PEEM- und SEM-Untersuchungen am intakten Magnetospirillum magnetotacticum / Christoph Keutner. Betreuer: Carsten Westphal. Gutachter: Wolfgang Rhode." Dortmund : Universitätsbibliothek Dortmund, 2015. http://d-nb.info/1110893485/34.
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Descamps, Elodie. "Greigite et magnétite : les déterminants environnementaux et génétiques contrôlant la biominéralisation chez les bactéries magnétotactiques." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0057/document.
Full textAbstract:
Les bactéries magnétotactiques représentent un groupe d’une grande diversité écologique et phylogénétique. Elles sont capables de biominéraliser des nanocristaux de magnétite [un oxyde de fer (Fe(II)Fe(III)2O4)] ou de greigite [un sulfure de fer (Fe(II)Fe(III)2S4)] dans leurs magnétosomes, organites alignés en chaînes permettant la navigation le long des lignes de champ magnétique terrestre. Jusqu'à récemment, seules des souches produisant de la magnétite étaient disponibles en culture pure, conduisant à des études sur les mécanismes de biominéralisation de cet oxyde de fer. En 2011, une nouvelle bactérie capable de former de la magnétite et de la greigite, Desulfamplus magnetovallimortis souche BW-1, a été cultivée avec succès en laboratoire. Dans cette thèse, nous proposons d'utiliser une approche intégrée et multidisciplinaire pour comprendre les mécanismes de biominéralisation de la greigite en utilisant comme modèle d’étude la souche BW-1. Nous avons donc cherché à déterminer les conditions environnementales et biologiques favorisant la formation de la magnétite et de la greigite. Ces travaux ont également conduit à la caractérisation physiologique et phylogénétique de BW-1. Puis, l’utilisation d’approches globales et ciblées de transcriptomique ont permis d'évaluer le taux d'expression des gènes impliqués dans la formation des magnétosomes (magnétite vs. greigite) dans diverses conditions de croissance. Une approche de protéomique a permis d’apporter des informations supplémentaires à cette étude. Ces résultats ont permis de progresser dans la compréhension fondamentale de la biominéralisation in vivo, en particulier pour des bactéries formant de la greigiteMagnetotactic bacteria represent a phylogenetically and ecologically diverse group of prokaryotes able to biomineralize magnetic nanocrystals composed of magnetite [an iron oxide (Fe(II)Fe(III)2O4)] or greigite [an iron sulfide (Fe(II)Fe(III)2S4)] in their magnetosomes, a prokaryotic organelle whose cytoplasmic alignement in chain allows the cell to navigate along the Earth’s magnetic field lines. Until recently, only magnetite-producing strains were available in pure culture. Thus, only the magnetite biomineralization has been studied. In 2011, a new bacterium able to form both magnetite and greigite, Desulfamplus magnetovallimortis strain BW-1, was isolated from Death Valley, California and cultivated in pure culture. In this work, we propose to use an integrated and multidisciplinary approach to understand the mechanisms involved in greigite biomineralization in BW-1 strain. First, we determined the environmental and biological conditions in which magnetite and greigite are formed. This first part of my thesis also contributed to the physiologic and phylogenetic characterization of this bacterium. Secondly, we used global and targeted transcriptomic approaches to evaluate the transcription levels of genes putatively involved in magnetosomes formation (magnetite vs. greigite) under various growth conditions. A proteomic approach provided additional informations to this study.Results obtained during my thesis contribute to the understanding of in vivo biomineralization, particularly for greigite production in magnetotactic bacteria
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Preveral, Sandra. "Ingénierie et utilisation des magnétosomes pour des applications médicales." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0405.
Full textAbstract:
Les magnetosomes sont des nanoparticules d’oxyde de fer produites génétiquement par les bactéries magnétotactiques. De part, la pureté de leurs cristaux, leur taille contrôlée, leur solubilité et biocompatibilité liées à la membrane les entourant ainsi que la possibilité de les fonctionnaliser par voie génétique, les magnétosomes peuvent être exploités dans un grand nombre d’applications biotechnologiques, rivalisant avec des particules magnétiques produites par voie chimique. C’est dans ce contexte que mon travail de thèse vise à explorer l’utilisation des magnétosomes comme agent théranostique. Mes travaux se sont centré sur l’utilisation de magnétosomes étiquetés génétiquement avec le peptide RGD (magnétosomes@RGD) comme outils biogéniques pour le diagnostic et le thérapie du cancer. En effet, nous démontrons que la présence du peptide RGD, se liant au récepteur ανβ3, permet le ciblage des cellules cancéreuses et augmente l'internalisation de la bioparticule de fer dans la tumeur. Après validation in cellulo, ces expériences ont été conduites chez la souris porteuse de tumeurs de la prostate, de mélanome ou de glioblastome. L'accumulation spécifique dans les tumeurs a été démontrée en imagerie par résonnance magnétique. La présence d'une grande quantité de fer dans les cellules nous a également permis d'aborder le potentiel thérapeutique des magnetosomes@RGD. Nous avons développé pour cela une approche par photothermie ainsi que par effet de radiosensibilisation aux rayons X ou protons appliquée in cellulo puis in vivo. L’ensemble de ces travaux contribue à démontrer le potentiel théranostique des magnétosomes bactériens via une fonctionnalisation adaptéeMagnetosomes are iron oxide nanoparticles produced genetically by magnetotactic bacteria. Due to the purity of their crystals, their controlled size, their solubility and biocompatibility related to the surrounding membrane and the possibility of their genetic functionalization, magnetosomes can be exploited in a large number of biotechnological applications, competing with chemically produced magnetic particles. It is in this context that my thesis work aims to explore the use of magnetosomes as theranostic agents. My work has focused on the use of magnetosomes genetically labelled with the RGD peptide (magnetosomes@RGD) as biogenic tools for cancer diagnosis and therapy. Indeed, we demonstrate that the presence of the RGD peptide, which binds to the ανβ3 receptor, allows the targeting of cancer cells and increases the internalization of the iron bioparticle in the tumor. After validation in cellulo, these experiments were conducted in mice with prostate tumours, melanoma or glioblastoma. Specific accumulation in tumours has been demonstrated in magnetic resonance imaging. The presence of a large amount of iron in the cells also allowed us to address the therapeutic potential of magnetosomes@RGD. For this purpose, we have developed an approach based on photothermia as well as on radiosensitivity to X-rays or protons applied in cellulo and then in vivo. All this work contributes to demonstrating the theranostic potential of bacterial magnetosomes through appropriate functionalization
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Fuduche, Maxime. "Croissance et synthèse de magnétosomes chez la bactérie magnétotactique marine Magnetospira sp (souche QH-2)." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0157.
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Les bactéries magnétotactiques (MTB) ont la particularité de s’orienter le long des lignes de champ magnétique terrestre. Ce comportement est lié à la présence d’organites intracellulaires appelés magnétosomes, constitués d’un nanocristal de fer magnétique enveloppé d’une membrane biologique. L’un des obstacles majeurs rencontrés dans l’étude des MTB microaérophiles réside dans la difficulté à les cultiver, notamment du fait de leur extrême sensibilité à l’oxygène, nécessaire pour la croissance mais qui en même temps inhibe fortement la synthèse des magnétosomes. Dans ce travail, un protocole d’incubation en bioréacteur d’une MTB marine récemment isolée, Magnetospira sp. (QH-2), a été développé. Le contrôle précis des conditions de croissance a permis de déterminer finement la gamme de sensibilité de la souche à la pression partielle d’oxygène (pO2) et de préciser son métabolisme hétérotrophe, basé sur la consommation concomitante du succinate et de l’histidine. Dans un autre volet, l’analyse par RT-qPCR du niveau d’expression des gènes impliqués dans la synthèse des magnétosomes a permis de démontrer chez QH-2 une régulation extrêmement fine de ce processus de biominéralisation, dépendante de la présence de fer et des conditions d’oxygénation. Nos résultats mettent en évidence un lien indirect entre la synthèse des magnétosomes et le métabolisme général du fer chez QH-2. La mise au point d’un nouveau dispositif de culture a permis de multiplier le taux de croissance de QH-2 par cinq comparé aux cultures traditionnelles réalisées en flacons. Cet outil pourra être utilisé à l’avenir pour isoler et cultiver d’autres microorganismes ayant des besoins en oxygène spécifiquesMagnetotactic bacteria (MTB) have the ability to orient themselves along geomagnetic field lines. This behavior is linked to the presence of intracellular organelles called magnetosomes, which are membrane-enclosed magnetic iron minerals. One of the major obstacles to the study of microaerophilic MTB is their fastidiousness with regard to their growth, due to their extreme sensitivity to oxygen that is required for cell growth but also strongly inhibits magnetosome synthesis. In this thesis, a method for the incubation in a bioreactor of a newly isolated marine MTB, Magnetospira sp. (strain QH-2), has been developed. The precise control of the growing conditions allowed us to determine the pO2 (oxygen partial pressure) range tolerated by the strain and to clarify its heterotrophic metabolism based on the concomitant consumption of succinate and histidine. In another part, the expression of the genes involved in magnetosome synthesis based on RT-qPCR analysis revealed a tight regulation of the biomineralization process, depending on the availability of iron and oxygen concentration. Our findings highlight the existence of an indirect link between magnetosome biosynthesis and the general iron metabolism in QH-2. The development of a new culture device has increased the growth rate of QH-2 by a factor of five compared to the traditional incubation using flasks. In the future, this tool could also be used to grow other microorganisms that have specific low but constant O2-requirements, and should facilitate the isolation and the development of new microaerophilic microbial models
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Abbe, Jean-Baptiste. "Ingénierie de bactéries magnétotactiques pour la bioremédiation du cobalt." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0051.
Full textAbstract:
Les bactéries magnétotactiques (MTB) sont des organismes capables de synthétiser des cristaux magnétiques au sein d’un organite particulier, le magnétosome. L’assemblage de ces magnétosomes leur confère des propriétés d’aimantation et d’orientation dans les champs magnétiques. Dans le contexte de l’essor des biotechnologies, nous avons procédé à la fonctionnalisation des MTB pour des applications de bioremédiation du cobalt.Nous avons ainsi développé des vecteurs adaptés aux MTB pour l’expression de machineries enzymatiques de Staphylococcus aureus et Pseudomonas aeruginosa permettant la production de métallophores analogues à la nicotianamine. Nous avons observé un phénotype double, d’augmentation de la résistance aux métaux et d’augmentation de l’accumulation du cobalt que ce soit chez Escherichia coli ou les MTB Magnetospirillum magneticum AMB-1 et Magnetospirillum gryphiswaldense MSR-1. Nous avons également observé que l’expression de systèmes d’import des métaux tel que la NiCoT perméase NxiA de Rhodopseudomonas palustris dans des souches exprimant les analogues de la nicotianamine permet d’accroître encore l’accumulation des métaux.De plus, nous avons montré que la production de ces analogues permet un enrichissement en cobalt des magnétosomes, mais ne conduit pas à de modification de la spéciation de ce métal chez les MTB.Nous proposons donc ici l’utilisation des MTB comme châssis cellulaire pour de nouvelles applications biotechnologiquesMagnetotactic bacteria (MTB) are organisms able to synthesize magnetic crystals within a specific organelle, the magnetosome. The assembly of these magnetosomes gives them magnetization and orientation properties in magnetic fields. In the context of the development of biotechnology, we have performed the functionalization of MTBs for cobalt bioremediation applications.We have thus developed vectors suitable for MTB for the expression of enzymatic machineries of Staphylococcus aureus and Pseudomonas aeruginosa allowing the production of metallophores analogous to nicotianamine. We observed a double phenotype, increased resistance toward metals and increased cobalt accumulation in Escherichia coli or MTBs Magnetospirillum magneticum AMB-1 and Magnetospirillum gryphiswaldense MSR-1. We have also observed that the expression of metal import systems such as Rhodopseudomonas palustris NiCoT permease NxiA in strains expressing nicotianamine analogs further increases the accumulation of metals.Moreover, we have shown that the production of these analogs allows a cobalt enrichment of the magnetosomes, but does not lead to a modification of the speciation of this metal in MTB.We introduce here the use of MTBs as cellular chassis for new biotechnological applications
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"Ring pattern formation of magnetospirillum magneticum strain AMB-1." 2012. http://library.cuhk.edu.hk/record=b5549181.
Full textAbstract:
我們研究趨磁螺菌 AMB-1局限在 100微米厚的空間內的運動，細菌濃度約為每立方厘米 10⁹個。整個過程以一台安裝在顯微鏡上的攝像機，以暗場摸式觀察及拍攝。在地球磁場下，我們可以觀察到細菌聚集成環紋，並開始擴大。擴大的初始速度與細菌的游泳速度接近。半小時後，環紋擴大至離液滴邊緣毫米左右，然後停止擴大。環寬約 130微米，比大腸桿菌的趨化環結構小 100倍。我們對這個現象作出了一系列的實驗，研究其特性。我們測試了不同化學成份的實驗緩衝液對環紋的影響。發現當緩衝液缺少琥珀酸時，環紋不會出現；另一方面，當使用琥珀酸作為緩衝液的唯一化學成份時，環紋能清楚地被觀測。這表明琥珀酸是環紋形成的關鍵成份。
實驗環境的氧氣含量能按不同比例混合氮和氧來控制。當環境改變為純氮時，環紋進一步擴大；當環境氧氣含量提高時，環紋縮小。實驗結果與微好氧細菌的特性相同。
在施加外加的磁場後，環紋被拉成長橢球形，證明細菌的擴散在環紋的形中有重要的作用。在更大的外加磁場下（ 0.3mT，十倍地球磁場），細胞聚集在液滴的兩端，隨後在這些位置長出環紋。該現象證明了環紋會在高細菌濃度的條件下形成， AMB-1有可能存在群體感應機制。
We study the motion of Magnetospirillum magneticum strain AMB-1 in solution of concentration around 10⁹ cells cm⁻³, which was conned between two glasses with separation 100 μm. The motion was imaged with a EMCCD camera attached to a microscope in darkeld mode and growing ring pattern was observed. Under the earth magnetic eld, the ring migrated under the velocity close to the bacteria swimming velocity. After about half an hour, the ring had expanded to around 1 mm from the edge of droplet. The ring width is about 130 μm, which is 2 orders of magnitude smaller than that of similar ring structure found in E. Coli. A series of experiments were conducted to study the properties of such ring.
In studying the chemical composition of the buffer uid, different compositions were tested. No ring was obseved when succinic acid was absent; on the other hand, ring pattern was observed when using succinic acid alone as a buffer, which suggests that succinic acid is one of the key components of ring formation.
Oxygen level was controlled by mixing nitrogen and oxygen in dierent ratios. Ring further expanded to the edge of droplet when pure nitrogen was pumped in; and shrank when oxygen level was high. The results are consistent with the property of micro-aerophilic band in all micro-aerophilic bacteria.
With an applied magnetic eld, the swarm ring elongated to ellip¬soidal shape, which suggests that the diusion of bacteria plays an important role in the formation of ring. Under even larger magnetic eld (10 times earth magnetic eld), cells aggregated at opposite ends of the droplet, and rings formed at these positions afterwards, which suggests that ring grows at high cell concentrations.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Chan, Siu Kit = 趨磁螺菌AMB-1的環紋觀測 / 陳兆傑.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2012.
Includes bibliographical references (leaves 48-50).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts also in Chinese.
Chan, Siu Kit = Qu ci luo jun AMB-1 de huan wen guan ce / Chen Zhaojie.
Abstract --- p.i
Acknowledgement --- p.iii
Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- History --- p.1
Chapter 1.2 --- General Properties of MTB --- p.1
Chapter 1.2.1 --- Microaerophilic --- p.2
Chapter 1.2.2 --- Magnetotaxis and Magnetosome --- p.2
Chapter 1.3 --- Motivation --- p.6
Chapter 1.3.1 --- Observation of Ring Pattern --- p.6
Chapter 2 --- Experimental Setup --- p.8
Chapter 2.1 --- Cell Culturing --- p.8
Chapter 2.1.1 --- Incubation --- p.9
Chapter 2.1.2 --- Culture Characterization --- p.11
Chapter 2.1.3 --- Storage --- p.11
Chapter 2.1.4 --- Strain Maintenance --- p.11
Chapter 2.2 --- Bacteria Tracking --- p.14
Chapter 2.2.1 --- Darkfield microscopy --- p.14
Chapter 2.2.2 --- Concentration Measurement --- p.17
Chapter 2.2.3 --- Darkfield image and cell density --- p.18
Chapter 2.3 --- Design of Experiment --- p.19
Chapter 2.3.1 --- Magnetic Field --- p.19
Chapter 2.3.2 --- Chemicals --- p.20
Chapter 2.3.3 --- Air Chamber --- p.20
Chapter 3 --- Experimental Result and Analysis --- p.22
Chapter 3.1 --- Ring properties --- p.22
Chapter 3.2 --- Chemotactic Property --- p.24
Chapter 3.3 --- Oxygen Concentration Control --- p.27
Chapter 3.3.1 --- Micro-aerophilic property --- p.27
Chapter 3.4 --- Response to Magnetic Field --- p.28
Chapter 3.4.1 --- Ring under constant magnetic field --- p.32
Chapter 3.4.2 --- Analysis on the change of shape --- p.35
Chapter 4 --- Conclusion and Discussion --- p.41
Chapter 4.1 --- Discussion --- p.41
Chapter 4.1.1 --- Formation of ring --- p.41
Chapter 4.1.2 --- Band Property --- p.43
Chapter 4.2 --- Suggested Focus --- p.44
Chapter A --- MSGM Content --- p.45
Chapter B --- Shrinking of Ring --- p.47
Bibliography --- p.48
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Lang, Claus [Verfasser]. "Magnetosome specific expression of chimeric proteins in Magnetospirillum gryphiswaldense for applications in cell biology and biotechnology / vorgelegt von Claus Lang." 2009. http://d-nb.info/996677003/34.
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Scheffel, André [Verfasser]. "Molekulare und strukturelle Untersuchungen zur Bildung von Magnetosomen und zur Assemblierung von Magnetosomenketten in Magnetospirillum gryphiswaldense / vorgelegt von André Scheffel." 2007. http://d-nb.info/985685085/34.
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