scholarly journals Hydrodynamics and direction change of tumbling bacteria

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254551
Author(s):  
Mariia Dvoriashyna ◽  
Eric Lauga
Keyword(s):  
Kinematic Model ◽  
E Coli ◽  
Change Of Direction ◽  
Helical Bundle ◽  
Rotation Direction ◽  
Direction Change ◽  
Imaging Results ◽  
Erratic Motion ◽  
Good Agreement ◽  
Main Change

The bacterium Escherichia coli (E. coli) swims in viscous fluids by rotating several helical flagellar filaments, which are gathered in a bundle behind the cell during ‘runs’ wherein the cell moves steadily forward. In between runs, the cell undergoes quick ‘tumble’ events, during which at least one flagellum reverses its rotation direction and separates from the bundle, resulting in erratic motion in place and a random reorientation of the cell. Alternating between runs and tumbles allows cells to sample space by stochastically changing their propulsion direction after each tumble. The change of direction during a tumble is not uniformly distributed but is skewed towards smaller angles with an average of about 62°–68°, as first measured by Berg and Brown (1972). Here we develop a theoretical approach to model the angular distribution of swimming E. coli cells during tumbles. We first use past experimental imaging results to construct a kinematic description of the dynamics of the flagellar filaments during a tumble. We then employ low-Reynolds number hydrodynamics to compute the consequences of the kinematic model on the force and torque balance of the cell and to deduce the overall change in orientation. The results of our model are in good agreement with experimental observations. We find that the main change of direction occurs during the ‘bundling’ part of the process wherein, at the end of a tumble, the dispersed flagellar filaments are brought back together in the helical bundle, which we confirm using a simplified forced-sphere model.

Constraints on kinematic model from Pantheon SNIa, OHD and CMB shift parameter measurements

2021 ◽  
Vol 36 (08) ◽  
pp. 2150049
Author(s):  
Abdulla Al Mamon
Keyword(s):  
Confidence Region ◽  
Kinematic Model ◽  
Hubble Constant ◽  
Cosmic Acceleration ◽  
Late Time ◽  
Shift Parameter ◽  
Redshift Range ◽  
Data Points ◽  
Text Model ◽  
Good Agreement

In this paper, we reconstruct the late-time cosmological dynamics using a purely kinematic approach. In particular, considering a divergence-free parametrization for deceleration parameter [Formula: see text], we first derive the jerk parameter [Formula: see text] and then confront it with combination of various cosmological datasets. We use the most recent observational datasets consisting of the 1048 Pantheon Supernovae Ia data points in the redshift range [Formula: see text], the 51 data points of observational Hubble parameter (OHD) measurements in the redshift range [Formula: see text], the Hubble constant [Formula: see text] (R19) and the CMB shift parameter measurements. We study the evolution of different cosmological quantities for the present model and compare it with the concordance [Formula: see text]CDM model. We find that only the combined Pantheon+OHD+R19 data shows good agreement with the [Formula: see text]CDM [Formula: see text] model within [Formula: see text] confidence region. We also find that our model successfully generates late time cosmic acceleration along with a decelerated expansion in the past.

Mischkolonien auxotropher und Wildtypzellen nach Behandlung von Esdierichia coli-Zellen mit salpetriger Säure

1963 ◽  
Vol 18 (3) ◽  
pp. 245-252 ◽  
Author(s):  
F. Kaudewitz ◽  
K. Moebus ◽  
H. Kneser
Keyword(s):  
Experimental Evidence ◽  
Nitrous Acid ◽  
Single Cells ◽  
The Other ◽  
Mathematical Treatment ◽  
E Coli ◽  
Type 3 ◽  
Good Agreement ◽  
Hybrid Dna ◽  
In Cells

Cells of E. coli incubated in nitrous acid give rise 1. to unchanged wildtype colonies, 2. to colonies composed of wildtype and auxotrophic cells and 3. to colonies consisting of auxotrophic cells only. The mixed colonies are considered to originate from single cells each of them harbouring hybrid DNA with one subunit, probably a sisterstrand, changed by deamination of a cytosine or adenine, the other one with unchanged wildtype composition. In cells producing type 3 colonies this wildtype strand is mutated lethally by a separate deamination of a cytosine or adenine. A mathematical treatment of this hypothesis leads to predictions which are in good agreement with experimental evidence. The data obtained are used for an estimation of the number of gene-loci of E. coli.

scholarly journals Optimization of Fenton Technology for Recalcitrant Compounds and Bacteria Inactivation

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1483
Author(s):  
Pablo Salgado ◽  
José Luis Frontela ◽  
Gladys Vidal
Keyword(s):  
Regression Coefficient ◽  
Interactive Effects ◽  
Molar Ratio ◽  
Main Process ◽  
Optimum Conditions ◽  
Box Behnken Design ◽  
E Coli ◽  
Bacteria Inactivation ◽  
The Individual ◽  
Good Agreement

In this work, the Fenton technology was applied to decolorize methylene blue (MB) and to inactivate Escherichia coli K12, used as recalcitrant compound and bacteria models respectively, in order to provide an approach into single and combinative effects of the main process variables influencing the Fenton technology. First, Box–Behnken design (BBD) was applied to evaluate and optimize the individual and interactive effects of three process parameters, namely Fe2+ concentration (6.0 × 10−4, 8.0 × 10−4 and 1.0 × 10−3 mol/L), molar ratio between H2O2 and Fe2+ (1:1, 2:1 and 3:1) and pH (3.0, 4.0 and 5.0) for Fenton technology. The responses studied in these models were the degree of MB decolorization (D%MB), rate constant of MB decolorization (kappMB) and E. coli K12 inactivation in uLog units (IuLogEC). According to the results of analysis of variances all of the proposed models were adequate with a high regression coefficient (R2 from 0.9911 to 0.9994). BBD results suggest that [H2O2]/[Fe2+] values had a significant effect only on D%MB response, [Fe2+] had a significant effect on all the responses, whereas pH had a significant effect on D%MB and IuLogEC. The optimum conditions obtained from response surface methodology for D%MB ([H2O2]/[Fe2+] = 2.9, [Fe2+] = 1.0 × 10−3 mol/L and pH = 3.2), kappMB ([H2O2]/[Fe2+] = 1.7, [Fe2+] = 1.0 × 10−3 mol/L and PH = 3.7) and IuLogEC ([H2O2]/[Fe2+] = 2.9, [Fe2+] = 7.6 × 10−4 mol/L and pH= 3.2) were in good agreement with the values predicted by the model.

scholarly journals Characterization of cytochrome bo3 activity in a native-like surface-tethered membrane

2008 ◽  
Vol 417 (2) ◽  
pp. 555-560 ◽  
Author(s):  
Sophie A. Weiss ◽  
Richard J. Bushby ◽  
Stephen D. Evans ◽  
Peter J. F. Henderson ◽  
Lars J. C. Jeuken
Keyword(s):  
Self Assembly ◽  
Membrane System ◽  
Terminal Oxidase ◽  
E Coli ◽  
Cytochrome Bo3 ◽  
Substrate Analogues ◽  
Long Chain ◽  
Good Agreement ◽  
Tethered Membranes

We have developed a simple native-like surface-tethered membrane system to investigate the activity of cbo3 (cytochrome bo3), a terminal oxidase in Escherichia coli. The tethered membranes consist of E. coli inner-membrane extracts mixed with additional E. coli lipids containing various amounts of the cbo3 substrate UQ-10 (ubiquinol-10). Tethered membranes are formed by self-assembly from vesicles on to gold electrodes functionalized with cholesterol derivatives. cbo3 activity was monitored using CV (cyclic voltammetry) with electron transfer to cbo3 mediated by UQ-10. The apparent Km for oxygen with this system is 1.1±0.4 μM, in good agreement with values reported in the literature for whole-cell experiments and for purified cbo3. Increasing the concentration of lipophilic UQ-10 in the membrane leads to an increase in cbo3 activity. The activity of cbo3 with long-chain ubiquinones appears to be different from previous reports using short-chain substrate analogues such as UQ-1 in that typical Michaelis–Menten kinetics are not observed using UQ-10. This native-like membrane model thus provides new insights into the interaction of transmembrane enzymes with hydrophobic substrates which contrasts with studies using hydrophilic UQ analogues.

Synthesis of Some New Hydroxytriazenes and their Antimicrobial and Anti-inflammatory Activities

2020 ◽  
Vol 19 (1) ◽  
pp. 50-60
Author(s):  
Shilpa Jain ◽  
Varsha Dayma ◽  
Poonam Sharma ◽  
Amit Bhargava ◽  
Prabhat K. Baroliya ◽  
...  
Keyword(s):  
Antibacterial Activities ◽  
Antimicrobial Activities ◽  
Antiinflammatory Effect ◽  
Zone Of Inhibition ◽  
Mass Spectral Analysis ◽  
Mass Spectral ◽  
E Coli ◽  
The Past ◽  
Anti Inflammatory ◽  
Good Agreement

Background: Hydroxytriazenes and their derivatives have been studied for the biological and pharmacological applications in the past few years. These compounds possess antibacterial, antifungal, anti-inflammatory, analgesic and wound healing activities. In this study, we report the synthesis of ten hydroxytriazenes in two series derived from disubstituted aniline and studied for antimicrobial and anti-inflammatory activities. Methods: For this purpose, 2-methyl-5-chloroaniline and 2-trifluoromethyl-5-chloroaniline were used to synthesize compounds A1-5 and B1-5 series, respectively. All compounds were synthesized by the reported method which involves three steps of the method (i) Reduction, (ii) Diazotization, (iii) Coupling. All synthesized compounds were characterized by various techniques CHN elemental analysis, FTIR, 1H NMR, and MASS spectral analysis. The antibacterial activities of the compounds were screened against S. aureus, S. pyogenes, E. coli, P. aeruginosa, and antifungal activities were against C. albicans, A. clavatus by the zone of inhibition method. In addition, anti-inflammatory activity was also evaluated by carrageenan-induced paw edema method and results were reported as % inhibition. Results: All the synthesized compounds were obtained in pure form and their spectral data are in good agreement with their structure. The synthesized compounds have shown good antimicrobial activity and zone of inhibition was ranging 21 to 24 mm. Further antiinflammatory effect of the compounds was 96.58 to 98.71 % inhibition. Conclusion: The results of the present study indicate that chloro and trifluoromethyl substitution at hydroxytriazenes skeleton could improve anti-inflammatory and antimicrobial activities.

scholarly journals Genome-Wide Analysis of Lipoprotein Expression in Escherichia coli MG1655

2004 ◽  
Vol 186 (10) ◽  
pp. 3254-3258 ◽  
Author(s):  
Stephen J. Brokx ◽  
Michael Ellison ◽  
Troy Locke ◽  
Drell Bottorff ◽  
Laura Frost ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Envelope ◽  
Global Gene Expression ◽  
Growth Conditions ◽  
Rt Pcr ◽  
E Coli ◽  
Genome Wide ◽  
Aerobic And Anaerobic ◽  
Insight Into ◽  
Good Agreement

ABSTRACT To gain insight into the cell envelope of Escherichia coli grown under aerobic and anaerobic conditions, lipoproteins were examined by using functional genomics. The mRNA expression levels of each of these genes under three growth conditions—aerobic, anaerobic, and anaerobic with nitrate—were examined by using both Affymetrix GeneChip E. coli antisense genome arrays and real-time PCR (RT-PCR). Many genes showed significant changes in expression level. The RT-PCR results were in very good agreement with the microarray data. The results of this study represent the first insights into the possible roles of unknown lipoprotein genes and broaden our understanding of the composition of the cell envelope under different environmental conditions. Additionally, these data serve as a test set for the refinement of high-throughput bioinformatic and global gene expression methods.

Development and Validation of a Model for Flat Belt Tracking in Pulley Drive Systems

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Dilip Prasad ◽  
Brice N. Cassenti
Keyword(s):  
Motion Tracking ◽  
Kinematic Model ◽  
Design Procedure ◽  
Physical Models ◽  
Similarity Parameter ◽  
Physical Effects ◽  
Drive Systems ◽  
Tracking Behavior ◽  
Development And Validation ◽  
Good Agreement

This investigation examines the problem of lateral belt motion (“tracking”) in belt drive systems using a mechanics-based approach. It is shown that the motion of a belt over a pulley of arbitrary shape with angular misalignment between the belt and pulley axes can be decomposed into two simpler problems: belt transport over a locally conforming cone and that over a cylindrical pulley at the specified angle of misalignment. The physical models are based on the assumptions that lateral deformations of the belt may be treated as those of a slender beam and that no slip occurs between the belt and the pulley surface. In the case of the conical pulley, a similarity parameter that incorporates the nominal pulley radius, mean normal stress in the belt and its stiffness and width is identified as the primary controlling influence on the tracking behavior. For the problem of tracking on a cylindrical pulley at a steering angle, a kinematic model is found to correctly predict the scaling of the tracking speed. In both models, it is necessary to introduce empirical constants to account for physical effects that have not been included. The tracking speed predicted by these models is nevertheless found to compare well with numerical simulations and experiments. The models are then used to determine the equilibrium position of a belt on a circular-arc crowned pulley. The predicted position was found to be in good agreement with experimental data, indicating that the present approach can be used as the basis for a systematic design procedure.

scholarly journals Structure and stability of the C-terminal helical bundle of the E. coli mechanosensitive channel of large conductance

2013 ◽  
Vol 22 (11) ◽  
pp. 1592-1601 ◽  
Author(s):  
Troy A. Walton ◽  
Douglas C. Rees
Keyword(s):  
Mechanosensitive Channel ◽  
Structure And Stability ◽  
E Coli ◽  
Helical Bundle

scholarly journals Synthesis and Electrochemical Studies of Hexamethyldibenzotetraaza N4-Macrocyclic Complexes of Ni(II) and Cu(II) Metal ions

2019 ◽  
Vol 31 (9) ◽  
pp. 2116-2120
Author(s):  
Vinod Kumar Vashistha ◽  
Neeraj Sharma ◽  
Anuj Kumar ◽  
Usha Rani Sharma
Keyword(s):  
Mass Spectra ◽  
Molar Conductance ◽  
Macrocyclic Complexes ◽  
Octahedral Structure ◽  
Standard Drug ◽  
E Coli ◽  
Distorted Octahedral ◽  
Uv Visible ◽  
Saddle Shape ◽  
Good Agreement

Hexamethyldibenzotetraaza[14]annulene type macrocyclic complexes of Ni(II) and Cu(II) have been synthesized by template method. These macrocyclic complexes were characterized by molar conductance, elemental analysis, IR, UV-visible, mass spectra and cyclic voltammetry. On the basis of electronic studies saddle shape distorted octahedral structure have been assigned to these macrocyclic complexes. The redox behaviour of Ni(II) and Cu(II) macrocyclic complexes showed reversible and quasi-irreversible redox process that supported by the ipc/ipa ratio which is in good agreement with Randles-Sevcik equation. These macrocyclic complexes were also studied for the antimicrobial activity against E. coli, P. aeruginosa, B. subtilis, S. aureus and C. albicans compared with gentamycin as standard drug.

Identification of a Kinematic Model of a 6DOF Industrial Manipulator With Angular Positioning Deviation “Error Map” of Rotary Axes

2020 ◽  
Author(s):  
Md Moktadir Alam ◽  
Soichi Ibaraki ◽  
Koki Fukuda ◽  
Sho Morita ◽  
Hiroshi Usuki
Keyword(s):  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Laser Tracker ◽  
Absolute Accuracy ◽  
Kinematic Parameters ◽  
Positioning Accuracy ◽  
Industrial Manipulator ◽  
Rotary Axes ◽  
Rotation Direction ◽  
Industrial Manipulators

Abstract To improve the overall “absolute” positioning accuracy for the industrial manipulator, it is indispensable to calibrate its kinematic parameters. In conventional studies, researchers have focused on Denavit–Hartenberg (D-H) parameters. However, until now, for industrial manipulators, the absolute accuracy is significantly poor than its repeatability. In this study, we propose a new kinematic model of a 6DOF (degrees of freedom) industrial manipulator with the angular positioning deviation “error map” of each rotary axis. The angular positioning deviation is modeled as a function of command angular positions, as well as the rotation direction to model the influence of backlash. We also propose a method to identify the angular positioning deviation of all the rotary axes by using a laser tracker.

Sign in / Sign up

Export Citation Format

Share Document