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Roger Duarte de Melo, Daniel Acosta-Avalos
'Candidatus Magnetoglobus multicellularis' is the most studied multicellular magnetotactic prokaryote. It presents a light-dependent photokinesis: green light decreases the translation velocity whereas red light increases it, in comparison to blue and white light. The present article shows that radio-frequency electromagnetic fields cancel the light effect on photokinesis. The frequency to cancel the light effect corresponds to the Zeeman resonance frequency (DC magnetic field of 4 Oe and radio-frequency of 11...
October 20, 2016: Antonie Van Leeuwenhoek
Bahareh Kherzi, Martin Pumera
Self-propelled autonomous nano/micromotors are in the forefront of current materials science and technology research. These small machines convert chemical energy from the environment into propulsion, and they can move autonomously in the environment and are capable of chemotaxis or magnetotaxis. They can be used for drug delivery, microsurgeries or environmental remediation. It is of immense interest from a future biomedical application point of view to understand the motion of the nano/micromotors in microfluidic channels...
October 14, 2016: Nanoscale
Pedro Leão, Lia C R S Teixeira, Jefferson Cypriano, Marcos Farina, Fernanda Abreu, Dennis A Bazylinski, Ulysses Lins
UNLABELLED: Magnetotactic bacteria (MTB) comprise a phylogenetically diverse group of prokaryotes capable of orienting and navigating along magnetic field lines. Under oxic conditions, MTB in natural environments in the Northern Hemisphere generally display north-seeking (NS) polarity, swimming parallel to the Earth's magnetic field lines, while those in the Southern Hemisphere generally swim antiparallel to magnetic field lines (south-seeking [SS] polarity). Here, we report a population of an uncultured, monotrichously flagellated, and vibrioid MTB collected from a brackish lagoon in Brazil in the Southern Hemisphere that consistently exhibits NS polarity...
September 15, 2016: Applied and Environmental Microbiology
Natalie Zeytuni, Samuel Cronin, Christopher T Lefèvre, Pascal Arnoux, Dror Baran, Zvi Shtein, Geula Davidov, Raz Zarivach
MamA is a highly conserved protein found in magnetotactic bacteria (MTB), a diverse group of prokaryotes capable of navigating according to magnetic fields - an ability known as magnetotaxis. Questions surround the acquisition of this magnetic navigation ability; namely, whether it arose through horizontal or vertical gene transfer. Though its exact function is unknown, MamA surrounds the magnetosome, the magnetic organelle embedding a biomineralised nanoparticle and responsible for magnetotaxis. Several structures for MamA from a variety of species have been determined and show a high degree of structural similarity...
2015: PloS One
Geula Davidov, Frank D Müller, Jens Baumgartner, Ronit Bitton, Damien Faivre, Dirk Schüler, Raz Zarivach
Magnetotactic bacteria (MTB) are a diverse group of aquatic bacteria that have the magnetotaxis ability to align themselves along the geomagnetic field lines and to navigate to a microoxic zone at the bottom of chemically stratified natural water. This special navigation is the result of a unique linear assembly of a specialized organelle, the magnetosome, which contains a biomineralized magnetic nanocrystal enveloped by a cytoplasmic membrane. The Magnetospirillum gryphiswaldense MtxA protein (MGR_0208) was suggested to play a role in bacterial magnetotaxis due to its gene location in an operon together with putative signal transduction genes...
2015: Frontiers in Molecular Biosciences
Michalis Chariaou, Lilah Rahn-Lee, Jessica Kind, Inés García-Rubio, Arash Komeili, Andreas U Gehring
Magnetotactic bacteria (MTB) build magnetic nanoparticles in chain configuration to generate a permanent dipole in their cells as a tool to sense the Earth's magnetic field for navigation toward favorable habitats. The majority of known MTB align their nanoparticles along the magnetic easy axes so that the directions of the uniaxial symmetry and of the magnetocrystalline anisotropy coincide. Desulfovibrio magneticus sp. strain RS-1 forms bullet-shaped magnetite nanoparticles aligned along their (100) magnetocrystalline hard axis, a configuration energetically unfavorable for formation of strong dipoles...
March 10, 2015: Biophysical Journal
Isaac Macwan, Zihe Zhao, Omar Sobh, Prabir Patra
Magnetospirillum magneticum (AMB-1), which belong to alpha-protobacterium are gram-negative, single-celled prokaryotic organisms consisting of a lash-like cellular appendage called flagella. These filamentous structures are made up of a protein called flagellin that in turn consist of four sub-domains, two inner domains (D0, D1) made up of alpha-helices and two outer domains (D2, D3) made up of beta sheets. It is wrapped in a helical fashion around the longitudinal filament with the outermost sub-domain (D3) exposed to the surrounding environment...
2014: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Lina M González, Warren C Ruder, Aaron P Mitchell, William C Messner, Philip R LeDuc
Many motile unicellular organisms have evolved specialized behaviors for detecting and responding to environmental cues such as chemical gradients (chemotaxis) and oxygen gradients (aerotaxis). Magnetotaxis is found in magnetotactic bacteria and it is defined as the passive alignment of these cells to the geomagnetic field along with active swimming. Herein we show that Magnetospirillum magneticum (AMB-1) show a unique set of responses that indicates they sense and respond not only to the direction of magnetic fields by aligning and swimming, but also to changes in the magnetic field or magnetic field gradients...
June 2015: ISME Journal
Felix Popp, Judith P Armitage, Dirk Schüler
Most motile bacteria navigate within gradients of external chemical stimuli by regulating the length of randomly oriented swimming episodes. Magnetotactic bacteria are characterized by chains of intracellular ferromagnetic nanoparticles and their ability to sense the geomagnetic field, which is believed to facilitate directed motion, but is not well understood at the behavioural and molecular level. Here, we show that cells of Magnetospirillum gryphiswaldense unexpectedly display swimming polarity that depends on aerotactic signal transduction through one of its four chemotaxis operons (cheOp1)...
2014: Nature Communications
Dennis A Bazylinski, Christopher T Lefèvre
Magnetotactic bacteria (MTB) represent a diverse collection of motile prokaryotes that biomineralize intracellular, membrane-bounded, tens-of-nanometer-sized crystals of a magnetic mineral called magnetosomes. Magnetosome minerals consist of either magnetite (Fe3O4) or greigite (Fe3S4) and cause cells to align along the Earth's geomagnetic field lines as they swim, a trait called magnetotaxis. MTB are known to mainly inhabit the oxic-anoxic interface (OAI) in water columns or sediments of aquatic habitats and it is currently thought that magnetosomes function as a means of making chemotaxis more efficient in locating and maintaining an optimal position for growth and survival at the OAI...
2013: Life
Xuegang Mao, Ramon Egli, Nikolai Petersen, Marianne Hanzlik, Xiuming Liu
Magnetotactic bacteria (MTB) use passive alignment with the Earth magnetic field as a mean to increase their navigation efficiency in horizontally stratified environments through what is known as magneto-aerotaxis (M-A). Current M-A models have been derived from MTB observations in aqueous environments, where a >80% alignment with inclined magnetic field lines produces a one-dimensional search for optimal living conditions. However, the mean magnetic alignment of MTB in their most widespread living environment, i...
2014: PloS One
Mathieu Bennet, Aongus McCarthy, Dmitri Fix, Matthew R Edwards, Felix Repp, Peter Vach, John W C Dunlop, Metin Sitti, Gerald S Buller, Stefan Klumpp, Damien Faivre
The response of cells to changes in their physico-chemical micro-environment is essential to their survival. For example, bacterial magnetotaxis uses the Earth's magnetic field together with chemical sensing to help microorganisms move towards favoured habitats. The studies of such complex responses are lacking a method that permits the simultaneous mapping of the chemical environment and the response of the organisms, and the ability to generate a controlled physiological magnetic field. We have thus developed a multi-modal microscopy platform that fulfils these requirements...
2014: PloS One
Suzanne C Dufour, Jason R Laurich, Rebecca T Batstone, Bonita McCuaig, Alexander Elliott, Kristin M Poduska
Bacteria containing magnetosomes (protein-bound nanoparticles of magnetite or greigite) are common to many sedimentary habitats, but have never been found before to live within another organism. Here, we show that octahedral inclusions in the extracellular symbionts of the marine bivalve Thyasira cf. gouldi contain iron, can exhibit magnetic contrast and are most likely magnetosomes. Based on 16S rRNA sequence analysis, T. cf. gouldi symbionts group with symbiotic and free-living sulfur-oxidizing, chemolithoautotrophic gammaproteobacteria, including the symbionts of other thyasirids...
December 2014: ISME Journal
Xuejun Zhu, Xin Ge, Ning Li, Long-Fei Wu, Chunxiong Luo, Qi Ouyang, Yuhai Tu, Guanjun Chen
The mechanism of how magnetotactic bacteria navigate along the magnetic field has been a puzzle. Two main models disagree on whether the magnetotactic behavior results from passive alignment with the magnetic field or active sensing of the magnetic force. Here, we quantitatively studied the swimming patterns of Magnetospirillum magneticum AMB-1 cells to understand the origin of their magnetotactic behaviors. Single-cell tracking and swimming pattern analysis showed that the cells follow a mixed run-reverse-tumble pattern...
July 24, 2014: Integrative Biology: Quantitative Biosciences From Nano to Macro
Yi-Ran Chen, Rui Zhang, Hai-Jian Du, Hong-Miao Pan, Wen-Yan Zhang, Ke Zhou, Jin-Hua Li, Tian Xiao, Long-Fei Wu
Two morphotypes of multicellular magnetotactic prokaryotes (MMPs) have been identified: spherical (several species) and ellipsoidal (previously one species). Here, we report novel ellipsoidal MMPs that are ∼ 10 × 8 μm in size, and composed of about 86 cells arranged in six to eight interlaced circles. Each MMP was composed of cells that synthesized either bullet-shaped magnetite magnetosomes alone, or both bullet-shaped magnetite and rectangular greigite magnetosomes. They showed north-seeking magnetotaxis, ping-pong motility and negative phototaxis at a velocity up to 300 μm s(-1) ...
March 2015: Environmental Microbiology
Samira Taherkhani, Mahmood Mohammadi, Jamal Daoud, Sylvain Martel, Maryam Tabrizian
The targeted and effective delivery of therapeutic agents remains an unmet goal in the field of controlled release systems. Magnetococcus marinus MC-1 magnetotactic bacteria (MTB) are investigated as potential therapeutic carriers. By combining directional magnetotaxis-microaerophilic control of these self-propelled agents, a larger amount of therapeutics can be delivered surpassing the diffusion limits of large drug molecules toward hard-to-treat hypoxic regions in solid tumors. The potential benefits of these carriers emphasize the need to develop an adequate method to attach therapeutic cargos, such as drug-loaded nanoliposomes, without substantially affecting the cell's ability to act as delivery agents...
May 27, 2014: ACS Nano
Sheng-Da Zhang, Nikolai Petersen, Wei-Jia Zhang, Sébastien Cargou, Juanfang Ruan, Dorothée Murat, Claire-Lise Santini, Tao Song, Takayuki Kato, Philippe Notareschi, Ying Li, Keiichi Namba, Anne-Marie Gué, Long-Fei Wu
Magnetotactic bacteria (MTB) have the unique capacity to align and swim along the geomagnetic field lines downward to the oxic-anoxic interface in chemically stratified water columns and sediments. They are most abundant within the first few centimetres of sediments below the water-sediment interface. It is unknown how MTB penetrate into the sediment layer and swim in the pocket water, while their movements are restricted by the alignment along the magnetic field lines. Here we characterized the swimming behaviour of the marine fast-swimming magnetotactic ovoid bacterium MO-1...
February 2014: Environmental Microbiology Reports
Mihály Pósfai, Christopher T Lefèvre, Denis Trubitsyn, Dennis A Bazylinski, Richard B Frankel
Magnetotactic bacteria (MTB) biomineralize magnetosomes, nano-scale crystals of magnetite or greigite in membrane enclosures that comprise a permanent magnetic dipole in each cell. MTB control the mineral composition, habit, size, and crystallographic orientation of the magnetosomes, as well as their arrangement within the cell. Studies involving magnetosomes that contain mineral and biological phases require multidisciplinary efforts. Here we use crystallographic, genomic and phylogenetic perspectives to review the correlations between magnetosome mineral habits and the phylogenetic affiliations of MTB, and show that these correlations have important implications for the evolution of magnetosome synthesis, and thus magnetotaxis...
2013: Frontiers in Microbiology
Fernanda Abreu, Viviana Morillo, Fabrícia F Nascimento, Clarissa Werneck, Mauricio Egidio Cantão, Luciane Prioli Ciapina, Luiz Gonzaga Paula de Almeida, Christopher T Lefèvre, Dennis A Bazylinski, Ana Tereza Ribeiro de Vasconcelos, Ulysses Lins
Candidatus Magnetoglobus multicellularis (Ca. M. multicellularis) is a member of a group of uncultured magnetotactic prokaryotes that possesses a unique multicellular morphology. To better understand this organism's physiology, we used a genomic approach through pyrosequencing. Genomic data analysis corroborates previous structural studies and reveals the proteins that are likely involved in multicellular morphogenesis of this microorganism. Interestingly, some detected protein sequences that might be involved in cell adhesion are homologues to phylogenetically unrelated filamentous multicellular bacteria proteins, suggesting their contribution in the early development of multicellular organization in Bacteria...
May 2014: ISME Journal
Christopher T Lefèvre, Dennis A Bazylinski
Magnetotactic bacteria (MTB) are widespread, motile, diverse prokaryotes that biomineralize a unique organelle called the magnetosome. Magnetosomes consist of a nano-sized crystal of a magnetic iron mineral that is enveloped by a lipid bilayer membrane. In cells of almost all MTB, magnetosomes are organized as a well-ordered chain. The magnetosome chain causes the cell to behave like a motile, miniature compass needle where the cell aligns and swims parallel to magnetic field lines. MTB are found in almost all types of aquatic environments, where they can account for an important part of the bacterial biomass...
September 2013: Microbiology and Molecular Biology Reviews: MMBR
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