scholarly journals A Compass To Boost Navigation: Cell Biology of Bacterial Magnetotaxis

2020 ◽  
Vol 202 (21) ◽  
Author(s):  
Frank D. Müller ◽  
Dirk Schüler ◽  
Daniel Pfeiffer
Keyword(s):  
Magnetic Field ◽  
Cell Biology ◽  
Molecular Mechanisms ◽  
Magnetotactic Bacteria ◽  
Genetically Engineered ◽  
Model Organisms ◽  
Complex Cell ◽  
Magnetite Biomineralization ◽  
Directed Motility ◽  
The Impact

ABSTRACT Magnetotactic bacteria are aquatic or sediment-dwelling microorganisms able to take advantage of the Earth’s magnetic field for directed motility. The source of this amazing trait is magnetosomes, unique organelles used to synthesize single nanometer-sized crystals of magnetic iron minerals that are queued up to build an intracellular compass. Most of these microorganisms cannot be cultivated under controlled conditions, much less genetically engineered, with only few exceptions. However, two of the genetically amenable Magnetospirillum species have emerged as tractable model organisms to study magnetosome formation and magnetotaxis. Recently, much has been revealed about the process of magnetosome biogenesis and dedicated structures for magnetosome dynamics and positioning, which suggest an unexpected cellular intricacy of these organisms. In this minireview, we summarize new insights and place the molecular mechanisms of magnetosome formation in the context of the complex cell biology of Magnetospirillum spp. First, we provide an overview on magnetosome vesicle synthesis and magnetite biomineralization, followed by a discussion of the perceptions of dynamic organelle positioning and its biological implications, which highlight that magnetotactic bacteria have evolved sophisticated mechanisms to construct, incorporate, and inherit a unique navigational device. Finally, we discuss the impact of magnetotaxis on motility and its interconnection with chemotaxis, showing that magnetotactic bacteria are outstandingly adapted to lifestyle and habitat.

scholarly journals Molecular Mechanisms of Topography Sensing by Osteoblasts: An Update

2021 ◽  
Vol 11 (4) ◽  
pp. 1791
Author(s):  
Pablo Rougerie ◽  
Rafaela Silva dos Santos ◽  
Marcos Farina ◽  
Karine Anselme
Keyword(s):  
Cell Biology ◽  
Bone Repair ◽  
Molecular Mechanisms ◽  
Cell Types ◽  
Flat Surfaces ◽  
Total Potential ◽  
Gene Expression Matrix ◽  
Specialized Tissue ◽  
The Impact

Bone is a specialized tissue formed by different cell types and a multiscale, complex mineralized matrix. The architecture and the surface chemistry of this microenvironment can be factors of considerable influence on cell biology, and can affect cell proliferation, commitment to differentiation, gene expression, matrix production and/or composition. It has been shown that osteoblasts encounter natural motifs in vivo, with various topographies (shapes, sizes, organization), and that cell cultures on flat surfaces do not reflect the total potential of the tissue. Therefore, studies investigating the role of topographies on cell behavior are important in order to better understand the interaction between cells and surfaces, to improve osseointegration processes in vivo between tissues and biomaterials, and to find a better topographic surface to enhance bone repair. In this review, we evaluate the main available data about surface topographies, techniques for topographies’ production, mechanical signal transduction from surfaces to cells and the impact of cell–surface interactions on osteoblasts or preosteoblasts’ behavior.

scholarly journals Alternate histories of cytokinesis: lessons from the trypanosomatids

2020 ◽  
Vol 31 (24) ◽  
pp. 2631-2639
Author(s):  
Paul C. Campbell ◽  
Christopher L. de Graffenried
Keyword(s):  
Cell Biology ◽  
Molecular Mechanisms ◽  
Sparse Sampling ◽  
Model Organisms ◽  
Great Success ◽  
Eukaryotic Diversity ◽  
Daughter Cells ◽  
Evolutionary Trajectories ◽  
Unicellular Organisms ◽  
Cellular Organelles

Popular culture has recently produced several “alternate histories” that describe worlds where key historical events had different outcomes. Beyond entertainment, asking “could this have happened a different way?” and “what would the consequences be?” are valuable approaches for exploring molecular mechanisms in many areas of research, including cell biology. Analogous to alternate histories, studying how the evolutionary trajectories of related organisms have been selected to provide a range of outcomes can tell us about the plasticity and potential contained within the genome of the ancestral cell. Among eukaryotes, a group of model organisms has been employed with great success to identify a core, conserved framework of proteins that segregate the duplicated cellular organelles into two daughter cells during cell division, a process known as cytokinesis. However, these organisms provide relatively sparse sampling across the broad evolutionary distances that exist, which has limited our understanding of the true potential of the ancestral eukaryotic toolkit. Recent work on the trypanosomatids, a group of eukaryotic parasites, exemplifies alternate historical routes for cytokinesis that illustrate the range of eukaryotic diversity, especially among unicellular organisms.

Stress testing at the cellular and molecular level to unravel cellular dysfunction and growth factor signal transduction defects: What Molecular Cell Biology can learn from Cardiology

2007 ◽  
Vol 98 (11) ◽  
pp. 975-979 ◽  
Author(s):  
Johannes Waltenberger
Keyword(s):  
Cell Biology ◽  
Stress Testing ◽  
Molecular Mechanisms ◽  
Cellular Stress ◽  
Cellular Models ◽  
Collateral Arteries ◽  
Monocyte Chemotaxis ◽  
Molecular Cell Biology ◽  
Cellular Dysfunction ◽  
The Impact

SummaryClinical medicine has been revolutionized by the impact of cellular and molecular biology in the past 30 years. This article focuses on a novel approach, whereby the clinically proven and important concept of patient or organ stress testing is being applied to cellular models, thereby developing and validating novel quantitative molecular and cellular stress tests. One example is monocyte chemotaxis analysis, whereby circulating monocytes freshly isolated from peripheral blood are being tested for their migratory responsiveness towards relevant biological stimuli such as growth factors or chemokines. These stimuli are relevant for recruiting monocytes to sites of local inflammation such as during wound healing or arteriogenesis, i.e. growth of collateral arteries. Initial clinical studies to validate “ligand-induced monocyte chemotaxis” indicate that this parameter is impaired in the presence of various cardiovascular risk factors including diabetes mellitus, hypercholesterolemia or smoking. In addition, there is proof of concept that impaired monocyte chemotaxis is reversible as shown for anti-oxidants in smokers. Moreover, the parameter “ligand-induced monocyte chemotaxis” is of great relevance for basic science (including Molecular Cell Biology) as unravelling the underlying molecular mechanisms of cellular dysfunction will certainly stimulate our understanding of the molecular basis of cellular function. This article highlights the concept of stress testing in modern medicine. Cellular stress testing is introduced as a novel and intriguing approach, which was developed as bedside-to-bench. Future prospective clinical trials will have to validate the predictive value of cellular stress testing.

scholarly journals The Effects of Environmental Adversities on Human Neocortical Neurogenesis Modeled in Brain Organoids

2021 ◽  
Vol 8 ◽  
Author(s):  
Kseniia Sarieva ◽  
Simone Mayer
Keyword(s):  
Brain Development ◽  
Molecular Mechanisms ◽  
Time Windows ◽  
Fetal Brain ◽  
Model Organisms ◽  
The Past ◽  
Nicotine Consumption ◽  
Simplex Virus ◽  
The Impact

Over the past decades, a growing body of evidence has demonstrated the impact of prenatal environmental adversity on the development of the human embryonic and fetal brain. Prenatal environmental adversity includes infectious agents, medication, and substances of use as well as inherently maternal factors, such as diabetes and stress. These adversities may cause long-lasting effects if occurring in sensitive time windows and, therefore, have high clinical relevance. However, our knowledge of their influence on specific cellular and molecular processes of in utero brain development remains scarce. This gap of knowledge can be partially explained by the restricted experimental access to the human embryonic and fetal brain and limited recapitulation of human-specific neurodevelopmental events in model organisms. In the past years, novel 3D human stem cell-based in vitro modeling systems, so-called brain organoids, have proven their applicability for modeling early events of human brain development in health and disease. Since their emergence, brain organoids have been successfully employed to study molecular mechanisms of Zika and Herpes simplex virus-associated microcephaly, as well as more subtle events happening upon maternal alcohol and nicotine consumption. These studies converge on pathological mechanisms targeting neural stem cells. In this review, we discuss how brain organoids have recently revealed commonalities and differences in the effects of environmental adversities on human neurogenesis. We highlight both the breakthroughs in understanding the molecular consequences of environmental exposures achieved using organoids as well as the on-going challenges in the field related to variability in protocols and a lack of benchmarking, which make cross-study comparisons difficult.

Aneuploidy: From a Physiological Mechanism of Variance to Down Syndrome

2009 ◽  
Vol 89 (3) ◽  
pp. 887-920 ◽  
Author(s):  
Mara Dierssen ◽  
Yann Herault ◽  
Xavier Estivill
Keyword(s):  
Gene Expression ◽  
Down Syndrome ◽  
Phenotypic Diversity ◽  
Physiological Mechanism ◽  
Brain Regions ◽  
Learning Disorders ◽  
Genetically Engineered ◽  
Model Organisms ◽  
Genomic Disorder ◽  
The Impact

Quantitative differences in gene expression emerge as a significant source of variation in natural populations, representing an important substrate for evolution and accounting for a considerable fraction of phenotypic diversity. However, perturbation of gene expression is also the main factor in determining the molecular pathogenesis of numerous aneuploid disorders. In this review, we focus on Down syndrome (DS) as the prototype of “genomic disorder” induced by copy number change. The understanding of the pathogenicity of the extra genomic material in trisomy 21 has accelerated in the last years due to the recent advances in genome sequencing, comparative genome analysis, functional genome exploration, and the use of model organisms. We present recent data on the role of genome-altering processes in the generation of diversity in DS neural phenotypes focusing on the impact of trisomy on brain structure and mental retardation and on biological pathways and cell types in target brain regions (including prefrontal cortex, hippocampus, cerebellum, and basal ganglia). We also review the potential that genetically engineered mouse models of DS bring into the understanding of the molecular biology of human learning disorders.

Effects of Electromagnetic Fields Exposure on the Production of Nanosized Magnetosome, Elimination of Free Radicals and Antioxidant Defense Systems in Magnetospirillum gryphiswaldense MSR-1

2019 ◽  
Vol 58 ◽  
pp. 20-31
Author(s):  
Hatami Giklou Jajan Leila ◽  
Mohsen Abolhassani ◽  
Seyed Nezamedin Hosseini ◽  
Behzad Ghareyazie ◽  
Leila Ma'mani ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Free Radicals ◽  
Magnetotactic Bacteria ◽  
Antioxidant Systems ◽  
Microaerobic Condition ◽  
Magnetospirillum Gryphiswaldense ◽  
Defense Systems ◽  
Antioxidant Defense Systems ◽  
The Impact ◽  
The Magnetic Field

Magnetotactic bacteria integrated magnetosomes, which are unique organelles that contain nanosized crystals of biogenic magnetic iron minerals with the ability to respond to the external magnetic fields. The biogenic magnetic nanoparticles (magnetosomes) show high biocompatibility in medical applications especially as scavengers to eliminate intracellular reactive oxygen species. The aim of this study was to highlight the impact of magnetosome formation and antioxidant systems in the suppression of oxidative stress on the magnetotactic bacteria cells. To assess the changes in ROS levels under different magnetic field intensity conditions, cells were cultured under the microaerobic condition in medium containing the high and low intensity of magnetic field. Treatment of magnetic field with an intensity of 500 mT during 50 hours bionormalization process of magnetotactic bacteria increased the antioxidant enzyme activity for eliminating of free radicals by 64%. We concluded that magnetosomes production plays an important role in decreasing or eliminating ROS. This is the first study to demonstrate that the magnetic field assisted magnetosome formation and antioxidants defense systems inMagnetospirillum gryphiswaldenseMSR-1.

MAGNETIC FIELD IMPACT UPON TRIBOTECHNICAL CHARACTERISTICS OF PERMANENT CONNECTIONS IN RELATION TO FRICTION SHOCK ABSORBERS

2020 ◽  
Vol 2020 (10) ◽  
pp. 4-11
Author(s):  
Victor Tikhomirov ◽  
Aleksandr Gorlenko ◽  
Stanislav Volohov ◽  
Mikhail Izmerov
Keyword(s):  
Magnetic Field ◽  
Friction Factor ◽  
Physical Contact ◽  
Active Centers ◽  
Press Fit ◽  
Electro Magnetic Field ◽  
Investigation Methods ◽  
Electro Magnetic ◽  
The Impact ◽  
The Magnetic Field

The work purpose is the investigation of magnetic field impact upon properties of friction steel surfaces at fit stripping with tightness through manifested effects and their wear visually observed. On the spots of a real contact the magnetic field increases active centers, their amount and saturation with the time of dislocation outlet, and has an influence upon tribo-mating. The external electro-magnetic field promotes the increase of the number of active centers at the expense of dislocations outlet on the contact surface, and the increase of a physical contact area results in friction tie strengthening and growth of a friction factor. By the example of friction pairs of a spentonly unit in the suspension of coach cars there is given a substantiation of actuality and possibility for the creation of technical devices with the controlled factor of friction and the stability of effects achieved is also confirmed experimentally. Investigation methods: the fulfillment of laboratory physical experiments on the laboratory plant developed and patented on bush-rod samples inserted with the fit and tightness. The results of investigations and novelty: the impact of the magnetic field upon the value of a stripping force of a press fit with the guaranteed tightness is defined. Conclusion: there is a possibility to control a friction factor through the magnetic field impact upon a friction contact.

THE IMPACT OF A MAGNETIC FIELD ON THE WEAR OF THE GRINDING BODIES, LINING, AND ORE DISINTEGRATION (IN ENGLISH)

2018 ◽  
pp. 75-82
Author(s):  
KHOPUNOV EDUARD AFANAS'EVICH ◽  
◽  
SHATAILOV IURII LEONIDOVICH ◽  
VORONCHIKHIN SERGEI LEONIDOVICH ◽  
SHATAILOV ALEKSANDR IUR'EVICH ◽  
...  
Keyword(s):  
Magnetic Field ◽  
The Impact
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