scholarly journals Understanding the Biomineralization Role of Magnetite-Interacting Components (MICs) From Magnetotactic Bacteria

2018 ◽  
Vol 9 ◽  
Author(s):  
Hila Nudelman ◽  
Yi-Zong Lee ◽  
Yi-Lin Hung ◽  
Sofiya Kolusheva ◽  
Alexander Upcher ◽  
...  
Keyword(s):  
Magnetotactic Bacteria ◽  
Interacting Components

scholarly journals Spatiotemporal Distribution of Marine Magnetotactic Bacteria in a Seasonally Stratified Coastal Salt Pond

2004 ◽  
Vol 70 (10) ◽  
pp. 6230-6239 ◽  
Author(s):  
S. L. Simmons ◽  
S. M. Sievert ◽  
R. B. Frankel ◽  
D. A. Bazylinski ◽  
K. J. Edwards
Keyword(s):  
Alternative Model ◽  
Physiological Role ◽  
Magnetotactic Bacteria ◽  
Respiratory Metabolism ◽  
Population Abundance ◽  
Seasonal Fluctuations ◽  
Salt Pond ◽  
Chemical Conditions ◽  
Physical And Chemical

ABSTRACT The occurrence and distribution of magnetotactic bacteria (MB) were studied as a function of the physical and chemical conditions in meromictic Salt Pond, Falmouth, Mass., throughout summer 2002. Three dominant MB morphotypes were observed to occur within the chemocline. Small microaerophilic magnetite-producing cocci were present at the top of the chemocline, while a greigite-producing packet-forming bacterium occurred at the base of the chemocline. The distributions of these groups displayed sharp changes in abundance over small length scales within the water column as well as strong seasonal fluctuations in population abundance. We identified a novel, greigite-producing rod in the sulfidic hypolimnion that was present in relatively constant abundance over the course of the season. This rod is the first MB that appears to belong to the γ-Proteobacteria, which may suggest an iron- rather than sulfur-based respiratory metabolism. Its distribution and phylogenetic identity suggest that an alternative model for the ecological and physiological role of magnetotaxis is needed for greigite-producing MB.

Thermal decomposition rate of MgCO3as an inorganic astrobiological matrix in meteorites

2016 ◽  
Vol 16 (2) ◽  
pp. 130-136 ◽  
Author(s):  
E. Bisceglia ◽  
G. Micca Longo ◽  
S. Longo
Keyword(s):  
Decomposition Rate ◽  
Thermal Protection ◽  
Magnetotactic Bacteria ◽  
Planetary Atmosphere ◽  
Carbonate Minerals ◽  
Biological Matter ◽  
Gaseous Carbon Dioxide ◽  
Carbonate Matrix ◽  
Better Than

AbstractCarbonate minerals, likely of hydrothermal origins and included into orthopyroxenite, have been extensively studied in the ALH84001 meteorite. In this meteorite, nanocrystals comparable with those produced by magnetotactic bacteria have been found into a carbonate matrix. This leads naturally to a discussion of the role of such carbonates in panspermia theories. In this context, the present work sets the basis of a criterion to evaluate whether a carbonate matrix in a meteor entering a planetary atmosphere would be able to reach the surface. As a preliminary step, the composition of carbonate minerals in the ALH84001 meteorite is reviewed; in view of the predominance of Mg in these carbonates, pure magnesite (MgCO3) is proposed as a mineral model. This mineral is much more sensitive to high temperatures reached during an entry process, compared with silicates, due to facile decomposition into MgO and gaseous carbon dioxide (CO2). A most important quantity for further studies is therefore the decomposition rate expressed as CO2evaporation rateJ(molecules/m2s). An analytical expression forJ(T) is given using the Langmuir law, based on CO2pressure in equilibrium with MgCO3and MgO at the surface temperatureT. Results suggest that carbonate minerals rich in magnesium may offer much better thermal protection to embedded biological matter than silicates and significantly better than limestone, which was considered in previous studies, in view of the heat absorbed by their decomposition even at moderate temperatures. This first study can be extended in the future to account for more complex compositions, including Fe and Ca.

scholarly journals Magnetosomes could be protective shields against metal stress in magnetotactic bacteria

2020 ◽  
Author(s):  
D. Muñoz ◽  
L. Marcano ◽  
R. Martín-Rodríguez ◽  
L. Simonelli ◽  
A. Serrano ◽  
...  
Keyword(s):  
Magnetotactic Bacteria ◽  
Resistance Mechanisms ◽  
Metal Stress ◽  
Bacterial Populations ◽  
Cell Compartments ◽  
Aquatic Microorganisms ◽  
Field Lines ◽  
A Chain ◽  
X Ray Absorption

AbstractMagnetotactic bacteria are aquatic microorganisms with the ability to biomineralise membrane-enclosed magnetic nanoparticles, called magnetosomes. These magnetosomes are arranged into a chain that behaves as a magnetic compass, allowing the bacteria to align in and navigate along the Earth’s magnetic field lines. According to the magneto-aerotactic hypothesis, the purpose of producing magnetosomes is to provide the bacteria with a more efficient movement within the stratified water column, in search of the optimal positions that satisfy their nutritional requirements. However, magnetosomes could have other physiological roles, as proposed in this work. Here we analyse the role of magnetosomes in the tolerance of Magnetospirillum gryphiswaldense MSR-1 to transition metals (Co, Mn, Ni, Zn, Cu). By exposing bacterial populations with and without magnetosomes to increasing concentrations of metals in the growth medium, we observe that the tolerance is significantly higher when bacteria have magnetosomes. The resistance mechanisms triggered in magnetosome-bearing bacteria under metal stress have been investigated by means of x-ray absorption near edge spectroscopy (XANES). XANES experiments were performed both on magnetosomes isolated from the bacteria and on the whole bacteria, aimed to assess whether bacteria use magnetosomes as metal storages, or whether they incorporate the excess metal in other cell compartments. Our findings reveal that the tolerance mechanisms are metal-specific: Mn, Zn and Cu are incorporated in both the magnetosomes and other cell compartments; Co is only incorporated in the magnetosomes, and Ni is incorporated in other cell compartments. In the case of Co, Zn and Mn, the metal is integrated in the magnetosome magnetite mineral core.

scholarly journals Tunable self-assembly of magnetotactic bacteria: Role of hydrodynamics and magnetism

AIP Advances ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 015335
Author(s):  
Christopher J. Pierce ◽  
Hiran Wijesinghe ◽  
Emily Osborne ◽  
Eric Mumper ◽  
Brian Lower ◽  
...  
Keyword(s):  
Self Assembly ◽  
Magnetotactic Bacteria

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor

Role of the allergist in diagnosis and management of patients with uveitis

JAMA ◽  
1966 ◽  
Vol 195 (3) ◽  
pp. 167-172 ◽  
Author(s):  
T. E. Van Metre
Keyword(s):  
Diagnosis And Management

The power of norms to sway fused group members

2018 ◽  
Vol 41 ◽  
Author(s):  
Winnifred R. Louis ◽  
Craig McGarty ◽  
Emma F. Thomas ◽  
Catherine E. Amiot ◽  
Fathali M. Moghaddam
Keyword(s):  
Evolutionary Anthropology ◽  
Normative Systems ◽  
Violent Extremism ◽  
Identity Fusion ◽  
Group Members

AbstractWhitehouse adapts insights from evolutionary anthropology to interpret extreme self-sacrifice through the concept of identity fusion. The model neglects the role of normative systems in shaping behaviors, especially in relation to violent extremism. In peaceful groups, increasing fusion will actually decrease extremism. Groups collectively appraise threats and opportunities, actively debate action options, and rarely choose violence toward self or others.

Elaborating the role of reflection and individual differences in the study of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Kevin Arceneaux
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Cognitive Processes ◽  
Evolutionary History ◽  
Behavioral Responses ◽  
History Of ◽  
Economic Beliefs

AbstractIntuitions guide decision-making, and looking to the evolutionary history of humans illuminates why some behavioral responses are more intuitive than others. Yet a place remains for cognitive processes to second-guess intuitive responses – that is, to be reflective – and individual differences abound in automatic, intuitive processing as well.

The role of affect in feelings of obligation

2020 ◽  
Vol 43 ◽  
Author(s):  
Stefen Beeler-Duden ◽  
Meltem Yucel ◽  
Amrisha Vaish
Keyword(s):  
Positive Emotions ◽  
The Creation ◽  
Sense Of Obligation

Abstract Tomasello offers a compelling account of the emergence of humans’ sense of obligation. We suggest that more needs to be said about the role of affect in the creation of obligations. We also argue that positive emotions such as gratitude evolved to encourage individuals to fulfill cooperative obligations without the negative quality that Tomasello proposes is inherent in obligations.

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