scholarly journals A cell-based simulation software for multi-cellular systems

2010 ◽  
Vol 26 (20) ◽  
pp. 2641-2642 ◽  
Author(s):  
Stefan Hoehme ◽  
Dirk Drasdo
2010 ◽  
Vol 192 (13) ◽  
pp. 3368-3378 ◽  
Author(s):  
Matthew T. Cabeen ◽  
Michelle A. Murolo ◽  
Ariane Briegel ◽  
N. Khai Bui ◽  
Waldemar Vollmer ◽  
...  

ABSTRACT Bacterial cell morphogenesis requires coordination among multiple cellular systems, including the bacterial cytoskeleton and the cell wall. In the vibrioid bacterium Caulobacter crescentus, the intermediate filament-like protein crescentin forms a cell envelope-associated cytoskeletal structure that controls cell wall growth to generate cell curvature. We undertook a genetic screen to find other cellular components important for cell curvature. Here we report that deletion of a gene (wbqL) involved in the lipopolysaccharide (LPS) biosynthesis pathway abolishes cell curvature. Loss of WbqL function leads to the accumulation of an aberrant O-polysaccharide species and to the release of the S layer in the culture medium. Epistasis and microscopy experiments show that neither S-layer nor O-polysaccharide production is required for curved cell morphology per se but that production of the altered O-polysaccharide species abolishes cell curvature by apparently interfering with the ability of the crescentin structure to associate with the cell envelope. Our data suggest that perturbations in a cellular pathway that is itself fully dispensable for cell curvature can cause a disruption of cell morphogenesis, highlighting the delicate harmony among unrelated cellular systems. Using the wbqL mutant, we also show that the normal assembly and growth properties of the crescentin structure are independent of its association with the cell envelope. However, this envelope association is important for facilitating the local disruption of the stable crescentin structure at the division site during cytokinesis.


2020 ◽  
Author(s):  
Archit Verma ◽  
Siddhartha G. Jena ◽  
Danielle R. Isakov ◽  
Kazuhiro Aoki ◽  
Jared E. Toettcher ◽  
...  

Multi-cellular organisms rely on spatial signaling among cells to drive their organization, development, and response to stimuli. Several models have been proposed to capture the behavior of spatial signaling in multi-cellular systems, but existing approaches fail to capture both the autonomous behavior of single cells and the interactions of a cell with its neighbors simultaneously. We propose a spatiotemporal model of dynamic cell signaling based on Hawkes processes—self-exciting point processes—that model the signaling processes within a cell and spatial couplings between cells. With this cellular point process (CPP) model, we capture both the single-cell protein bursting rate and the magnitude and duration of signaling between cells relative to spatial locations. Furthermore, our model captures tissues composed of heterogeneous cell types with different bursting rates and signaling behaviors across multiple signaling proteins. We apply our model to epithelial cell systems that exhibit a range of autonomous and spatial signaling behaviors basally and under pharmacological exposure. Our model identifies known drug-induced signaling deficits, characterizes differences in signaling across a wound front, and generalizes to multi-channel observations.


1996 ◽  
Vol 184 (6) ◽  
pp. 2361-2370 ◽  
Author(s):  
Sameer D. D'Souza ◽  
Bruno Bonetti ◽  
Vijayabalan Balasingam ◽  
Neil R. Cashman ◽  
Philip A. Barker ◽  
...  

Fas is a cell surface receptor that transduces cell death signals when cross-linked by agonist antibodies or by fas ligand. In this study, we examined the potential of fas to contribute to oligodendrocyte (OL) injury and demyelination as they occur in the human demyelinating disease multiple sclerosis (MS). Immunohistochemical study of central nervous system (CNS) tissue from MS subjects demonstrated elevated fas expression on OLs in chronic active and chronic silent MS lesions compared with OLs in control tissue from subjects with or without other neurologic diseases. In such lesions, microglia and infiltrating lymphocytes displayed intense immunoreactivity to fas ligand. In dissociated glial cell cultures prepared from human adult CNS tissue, fas expression was restricted to OLs. Fas ligation with the anti-fas monoclonal antibody M3 or with the fas–ligand induced rapid OL cell membrane lysis, assessed by LDH release and trypan blue uptake and subsequent cell death. In contrast to the activity of fas in other cellular systems, dying OLs did not exhibit evidence of apoptosis, assessed morphologically and by terminal transferase–mediated d-uridine triphosphate-biotin nick-end-labeling staining for DNA fragmentation. Other stimuli such as C2-ceramide were capable of inducing rapid apoptosis in OLs. Antibodies directed at other surface molecules expressed on OLs or the M33 nonactivating anti-fas monoclonal antibody did not induce cytolysis of OLs. Our results suggest that fas-mediated signaling might contribute in a novel cytolytic manner to immune-mediated OL injury in MS.


2019 ◽  
Author(s):  
Federico Aguirre

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px 'Times New Roman'; min-height: 15.0px} p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px 'Times New Roman'} span.s1 {font: 12.0px 'Times New Roman'} <p><br></p> <p> <b>Mobility is a key aspect in current cellular networks, allowing users to access the provided services almost anywhere. When a user transitions from a base station’s coverage area to another cell being serviced by another station, a handoff process takes place, where resources are released in the first base station, and allocated in the second for the purpose of servicing the user. Predicting the future location of a cell phone user allows the handoff process to be optimized. This optimization allows for a better utilization of the available resources, regarding bot the transmitted power and the frequency allocation, resulting in less amount of wasted power in unwanted directions and the possibility of reusing frequencies in a single base station. To achieve this goal, Deep Learning techniques are proposed, which have proven to be efficient tools for predicting and detecting patterns. The purpose of this paper is to give an overview of the state of the art in Deep Learning techniques for making spatio-temporal predictions, which could be used to optimize the handoff process in cellular systems. </b></p>


1998 ◽  
Vol 76 (5) ◽  
pp. 867-873 ◽  
Author(s):  
Daniel N Hebert ◽  
Jian-Xin Zhang ◽  
Ari Helenius

Reduced cellular systems have provided important tools to study complex cellular processes. Here we describe the oxidation, oligomerization, and chaperone binding of the viral glycoprotein influenza hemagglutinin in a cell-free system. The cell-free system, comprised of rough endoplasmic reticulum derived microsomes and a reticulocyte lysate, supported the complete maturation of hemagglutinin from the earliest oxidative intermediate to the mature homo-oligomer. Hemagglutinin disulfide bond formation and oligomerization were found to occur in a time- and temperature-dependent manner. Hemagglutinin's temporal association with the molecular chaperones calnexin and calreticulin was similar to that observed for their association with elongating ribosome-attached nascent chains in live cells. Furthermore, a procedure is described that permits the translocation of protein into microsomes that are depleted of lumenal contents. This cell-free system, therefore, provided an effective means to study the biological maturation processes of a protein that traverses the secretory pathway.Key words: protein folding, endoplasmic reticulum, molecular chaperone.


2015 ◽  
Vol 26 (15) ◽  
pp. 2727-2732 ◽  
Author(s):  
Peter-G. Barr-Gillespie

The hair bundle—the sensory organelle of inner-ear hair cells of vertebrates—exemplifies the ability of a cell to assemble complex, elegant structures. Proper construction of the bundle is required for proper mechanotransduction in response to external forces and to transmit information about sound and movement. Bundles contain tightly controlled numbers of actin-filled stereocilia, which are arranged in defined rows of precise heights. Indeed, many deafness mutations that disable hair-cell cytoskeletal proteins also disrupt bundles. Bundle assembly is a tractable problem in molecular and cellular systems biology; the sequence of structural changes in stereocilia is known, and a modest number of proteins may be involved.


Author(s):  
Mohamed G. Al-Fandi ◽  
Ajay P. Malshe ◽  
Shankar Sundaram ◽  
Jerry Jenkins ◽  
Steve Tung ◽  
...  

This paper presents the results of the computational fluid dynamic (CFD) modeling of viscous fluid flow in a novel cell motor actuated micropump. A cell motor is a bacterial flagellar cell tethered to a surface by a single flagellum, this flagellum acts as a pivot around which the cell body rotates. As a test case for investigation, the micropump consisted of two Escherichia coli cell motors tethered to the bottom of a microchannel with fixed dimensions. The CFD modeling of the micropump was performed using CFD-ACE+ simulation software (CFD Research Corporation). The biological cell motor was modeled as an ellipse with constant rotational speed of 10 Hz clockwise. The results of this model demonstrated the effect of the biological cell motor placement within the microchannel, as well as the rotational phase between the two biological cell motors, on the volumetric flowrate. Pumping action was observed as the cell motor location was moved adjacent to the sidewall of the microchannel. The rates of fluid pumping were of the order of 11 pL/hr when the cell motors were rotating in phase and their placement was close to the sidewall of the microchannel.


Radiation ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 45-64
Author(s):  
Dimitris Papakonstantinou ◽  
Vaso Zanni ◽  
Zacharenia Nikitaki ◽  
Christina Vasileiou ◽  
Konstantinos Kousouris ◽  
...  

This is a study concerning the use of Machine Learning (ML) techniques to ascertain the impacts of particle ionizing radiation (IR) on cell survival and DNA damage. Current empirical models do not always take into account intrinsic complexities and stochastic effects of the interactions of IR and cell populations. Furthermore, these models often lack in biophysical interpretations of the irradiation outcomes. The linear quadratic (LQ) model is a common way to associate the biological response of a cell population with the radiation dose. The parameters of the LQ model are used to extrapolate the relation between the dosage and the survival fraction of a cell population. The goal was to create a ML-based model that predicts the α and β parameters of the well known and established LQ model, along with the key metrics of DNA damage induction. The main target of this effort was, on the one hand, the development of a computational framework that will be able to assess key radiobiophysical quantities, and on the other hand, to provide meaningful interpretations of the outputs. Based on our results, as some metrics of the adaptability and training efficiency, our ML models exhibited 0.18 median error (relative root mean squared error (RRMSE)) in the prediction of the α parameter and errors of less than 0.01 for various DNA damage quantities; the prediction for β exhibited a rather large error of 0.75. Our study is based on experimental data from a publicly available dataset of irradiation studies. All types of complex DNA damage (all clusters), and the number of double-stranded breaks (DSBs), which are widely accepted to be closely related to cell survival and the detrimental biological effects of IR, were calculated using the fast Monte Carlo Damage Simulation software (MCDS). We critically discussed the varying importance of physical parameters such as charge and linear energy transfer (LET); we also discussed the uncertainties of our predictions and future directions, and the dynamics of our approach.


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