Crash landing of Vibrio cholerae by MSHA pili-assisted braking and anchoring in a viscous environment

AbstractMannose-sensitive hemagglutinin (MSHA) pili and flagellum are critical for the surface attachment of Vibrio cholerae. However, the cell landing mechanism remains largely unknown. Here, combining the cysteine-substitution-based labelling method with single-cell tracking techniques, we quantitatively characterized the landing of V. cholerae by directly observing both pili and flagellum of cells in viscous solutions. MSHA pili are evenly distributed along the cell length and can stick to surfaces at any point along the filament. With such properties, MSHA pili are observed to act as a brake and anchor during cell landing which include three phases: running, lingering, and attaching. Resistive-force-theory based models are proposed to describe near-surface motion. Importantly, the role of MSHA pili during cell landing is more apparent in viscous solutions. Our work provides a detailed picture of the landing dynamics of V. cholerae under viscous conditions, which can provide insights into ways to better control V. cholerae infections.

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Vibrio cholerae Type VI Activity Alters Motility Behavior in Mucin

Journal of Bacteriology ◽

10.1128/jb.00261-20 ◽

2020 ◽

Vol 202 (24) ◽

Author(s):

Abby Frederick ◽

Yuhsun Huang ◽

Meng Pu ◽

Dean A. Rowe-Magnus

Keyword(s):

Small Intestine ◽

Vibrio Cholerae ◽

Swimming Speed ◽

Cell Tracking ◽

Structural Genes ◽

Wild Type ◽

Epithelial Surface ◽

Near Surface ◽

Content Type ◽

Distal Small Intestine

ABSTRACT Motility is required for many bacterial pathogens to reach and colonize target sites. Vibrio cholerae traverses a thick mucus barrier coating the small intestine to reach the underlying epithelium. We screened a transposon library in motility medium containing mucin to identify factors that influence mucus transit. Lesions in structural genes of the type VI secretion system (T6SS) were among those recovered. Two-dimensional (2D) and 3D single-cell tracking was used to compare the motility behaviors of wild-type cells and a mutant that collectively lacked three essential T6SS structural genes (T6SS−). In the absence of mucin, wild-type and T6SS− cells exhibited similar speeds and run-reverse-flick (RRF) swimming patterns, in which forward-moving cells briefly backtrack before stochastically reorienting (flicking) in a new direction upon resuming forward movement. We show that mucin induced T6SS expression and activity in wild-type bacteria but significantly decreased their swimming speed and flicking, yielding curvilinear or near-surface circular traces for many cells. Conversely, mucin slowed T6SS− cells to a lesser extent, and many continued to flick and produce RRF-like traces. ΔcheY3 cells, which exclusively swim in the forward direction and thus cannot flick, also produced curvilinear traces with or without mucin present and, on occasion, near-surface circular traces in the presence of mucin. The dependence of flicking on swimming speed suggested that mucin-induced T6SS activity further decreased V. cholerae motility and thereby reduced flicking probability during reverse-to-forward transitions. We propose that this encourages cells to continue on their current trajectory rather than reorienting, which may benefit those tracking toward the epithelial surface. IMPORTANCE V. cholerae deploys an arsenal of virulence factors as it attempts to traverse a protective mucus layer and reach the epithelial surface of the distal small intestine. The T6SS used to cull bacterial competition during infection is induced by mucus. We show that this activity may serve an additional purpose by further decreasing motility in the presence of mucin, thereby reducing the probability of speed-dependent, near-perpendicular directional changes. We posit that this encourages cells to maintain course rather than change direction, which may aid those attempting to reach and colonize the epithelial surface.

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Applications of Energy Beams in Material and Device Processing

MRS Proceedings ◽

10.1557/proc-23-25 ◽

1983 ◽

Vol 23 ◽

Author(s):

G.J. Galvin ◽

L.S. Hung ◽

J.W. Mayer ◽

M. Nastasi

Keyword(s):

Ion Beam ◽

High Energy ◽

Ion Beams ◽

Traditional Role ◽

Near Surface ◽

Device Processing ◽

Composition Modification ◽

Directed Energy ◽

Transistor Fabrication

ABSTRACTEnergetic ion beams used outside the traditional role of ion implantation are considered for semiconductor applications involving interface modification for self-aligned silicide contacts, composition modification for formation of buried oxide layers in Si on insulator structures and reduced disorder in high energy ion beam annealing for buried collectors in transistor fabrication. In metals, aside from their use in modification of the composition of near surface regions, energetic ion beams are being investigated for structural modification in crystalline to amorphous transitions. Pulsed beams of photons and electrons are used as directed energy sources in rapid solidification. Here, we consider the role of temperature gradients and impurities in epitaxial growth of silicon.

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A warm jet in a cold ocean

Nature Communications ◽

10.1038/s41467-021-22505-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jennifer A. MacKinnon ◽

Harper L. Simmons ◽

John Hargrove ◽

Jim Thomson ◽

Thomas Peacock ◽

...

Keyword(s):

The Arctic ◽

Bering Strait ◽

Near Surface ◽

Ice Melt ◽

Beaufort Gyre ◽

The Pacific ◽

Climate Simulations ◽

Initial Evolution ◽

Forecast Models

AbstractUnprecedented quantities of heat are entering the Pacific sector of the Arctic Ocean through Bering Strait, particularly during summer months. Though some heat is lost to the atmosphere during autumn cooling, a significant fraction of the incoming warm, salty water subducts (dives beneath) below a cooler fresher layer of near-surface water, subsequently extending hundreds of kilometers into the Beaufort Gyre. Upward turbulent mixing of these sub-surface pockets of heat is likely accelerating sea ice melt in the region. This Pacific-origin water brings both heat and unique biogeochemical properties, contributing to a changing Arctic ecosystem. However, our ability to understand or forecast the role of this incoming water mass has been hampered by lack of understanding of the physical processes controlling subduction and evolution of this this warm water. Crucially, the processes seen here occur at small horizontal scales not resolved by regional forecast models or climate simulations; new parameterizations must be developed that accurately represent the physics. Here we present novel high resolution observations showing the detailed process of subduction and initial evolution of warm Pacific-origin water in the southern Beaufort Gyre.

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Indole Acts as an Extracellular Cue Regulating Gene Expression in Vibrio cholerae

Journal of Bacteriology ◽

10.1128/jb.01240-08 ◽

2009 ◽

Vol 191 (11) ◽

pp. 3504-3516 ◽

Cited By ~ 109

Author(s):

Ryan S. Mueller ◽

Sinem Beyhan ◽

Simran G. Saini ◽

Fitnat H. Yildiz ◽

Douglas H. Bartlett

Keyword(s):

Gene Expression ◽

Vibrio Cholerae ◽

Biofilm Formation ◽

Signal Molecule ◽

Control Of Gene Expression ◽

Protozoan Grazing ◽

Extracellular Signal ◽

Grazing Resistance ◽

Indole Signaling

ABSTRACT Indole has been proposed to act as an extracellular signal molecule influencing biofilm formation in a range of bacteria. For this study, the role of indole in Vibrio cholerae biofilm formation was examined. It was shown that indole activates genes involved in vibrio polysaccharide (VPS) production, which is essential for V. cholerae biofilm formation. In addition to activating these genes, it was determined using microarrays that indole influences the expression of many other genes, including those involved in motility, protozoan grazing resistance, iron utilization, and ion transport. A transposon mutagenesis screen revealed additional components of the indole-VPS regulatory circuitry. The indole signaling cascade includes the DksA protein along with known regulators of VPS production, VpsR and CdgA. A working model is presented in which global control of gene expression by indole is coordinated through σ54 and associated transcriptional regulators.

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Extreme Surface Winds During Landfalling Atmospheric Rivers: The Modulating Role of Near-Surface Stability

Journal of Hydrometeorology ◽

10.1175/jhm-d-20-0165.1 ◽

2021 ◽

Author(s):

Terence J. Pagano ◽

Duane E. Waliser ◽

Bin Guan ◽

Hengchun Ye ◽

F. Martin Ralph ◽

...

Keyword(s):

Water Vapor ◽

Static Stability ◽

Vapor Transport ◽

Water Vapor Transport ◽

Surface Winds ◽

Near Surface ◽

Extreme Surface ◽

Atmospheric Rivers ◽

Explained Variance

AbstractAtmospheric rivers (ARs) are long and narrow regions of strong horizontal water vapor transport. Upon landfall, ARs are typically associated with heavy precipitation and strong surface winds. A quantitative understanding of the atmospheric conditions that favor extreme surface winds during ARs has implications for anticipating and managing various impacts associated with these potentially hazardous events. Here, a global AR database (1999–2014) with relevant information from MERRA-2 reanalysis, QuikSCAT and AIRS satellite observations are used to better understand and quantify the role of near-surface static stability in modulating surface winds during landfalling ARs. The temperature difference between the surface and 1 km MSL (ΔT; used here as a proxy for near-surface static stability), and integrated water vapor transport (IVT) are analyzed to quantify their relationships to surface winds using bivariate linear regression. In four regions where AR landfalls are common, the MERRA-2-based results indicate that IVT accounts for 22-38% of the variance in surface wind speed. Combining ΔT with IVT increases the explained variance to 36-52%. Substitution of QuikSCAT surface winds and AIRS ΔT in place of the MERRA-2 data largely preserves this relationship (e.g., 44% compared to 52% explained variance for USA West Coast). Use of an alternate static stability measure–the bulk Richardson number–yields a similar explained variance (47%). Lastly, AR cases within the top and bottom 25% of near-surface static stability indicate that extreme surface winds (gale or higher) are more likely to occur in unstable conditions (5.3%/14.7% during weak/strong IVT) than in stable conditions (0.58%/6.15%).

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Decomposing the time-mean Atlantic Meridional Overturning Circulation and its variability with latitude.

10.5194/egusphere-egu21-1164 ◽

2021 ◽

Author(s):

Tomas Jonathan ◽

Mike Bell ◽

Helen Johnson ◽

David Marshall

Keyword(s):

Global Climate ◽

Dominant Role ◽

Meridional Overturning Circulation ◽

Western Boundary ◽

Relative Role ◽

Overturning Circulation ◽

Near Surface ◽

Boundary Density ◽

Meridional Overturning

The Atlantic Meridional Overturning Circulations (AMOC) is crucial to our global climate, transporting heat and nutrients around the globe. Detecting&#160; potential climate change signals first requires a careful characterisation of inherent natural AMOC variability. Using a hierarchy of global coupled model&#160; control runs (HadGEM-GC3.1, HighResMIP) we decompose the overturning circulation as the sum of (near surface) Ekman, (depth-dependent) bottom velocity, eastern and western boundary density components, as a function of latitude. This decomposition proves a useful low-dimensional characterisation of the full 3-D overturning circulation. In particular, the decomposition provides a means to investigate and quantify the constraints which boundary information imposes on the overturning, and the relative role of eastern versus western contributions on different timescales.&#160;The basin-wide time-mean contribution of each boundary component to the expected streamfunction is investigated as a function of depth, latitude and spatial resolution. Regression modelling supplemented by Correlation Adjusted coRrelation (CAR) score diagnostics provide a natural ranking of the contributions of the various components in explaining the variability of the total streamfunction. Results reveal the dominant role of the bottom component, western boundary and Ekman components at short time-scales, and of boundary density components at decadal and longer timescales.

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Evaluating the role of soil physical properties on simulated land-atmosphere interactions over South Africa using coupled atmosphere-hydrological modeling

10.5194/egusphere-egu21-9418 ◽

2021 ◽

Author(s):

Zhenyu Zhang ◽

Patrick Laux ◽

Joël Arnault ◽

Jianhui Wei ◽

Jussi Baade ◽

...

Keyword(s):

South Africa ◽

Physical Properties ◽

Land Degradation ◽

Land Surface ◽

Soil Physical Properties ◽

Near Surface ◽

Soil Database ◽

Global Soil ◽

The Impact

Land degradation with its direct impact on vegetation, surface soil layers and land surface albedo, has great relevance with the climate system. Assessing the climatic and ecological effects induced by land degradation requires a precise understanding of the interaction between the land surface and atmosphere. In coupled land-atmosphere modeling, the low boundary conditions impact the thermal and hydraulic exchanges at the land surface, therefore regulates the overlying atmosphere by land-atmosphere feedback processes. However, those land-atmosphere interactions are not convincingly represented in coupled land-atmosphere modeling applications. It is partly due to an approximate representation of hydrological processes in land surface modeling. Another source of uncertainties relates to the generalization of soil physical properties in the modeling system. This study focuses on the role of the prescribed physical properties of soil in high-resolution land surface-atmosphere simulations over South Africa. The model used here is the hydrologically-enhanced Weather Research and Forecasting (WRF-Hydro) model. Four commonly used global soil datasets obtained from UN Food and Agriculture Organization (FAO) soil database, Harmonized World Soil Database (HWSD), Global Soil Dataset for Earth System Model (GSDE), and SoilGrids dataset, are incorporated within the WRF-Hydro experiments for investigating the impact of soil information on land-atmosphere interactions. The simulation results of near-surface temperature, skin temperature, and surface energy fluxes are presented and compared to observational-based reference dataset. It is found that simulated soil moisture is largely influenced by soil texture features, which affects its feedback to the atmosphere.

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The control of inflammation via the phosphorylation and dephosphorylation of tristetraprolin: a tale of two phosphatases

Biochemical Society Transactions ◽

10.1042/bst20160166 ◽

2016 ◽

Vol 44 (5) ◽

pp. 1321-1337 ◽

Cited By ~ 39

Author(s):

Andrew R. Clark ◽

Jonathan L.E. Dean

Keyword(s):

Inflammatory Mediators ◽

Knockout Mouse ◽

Rna Binding ◽

Binding Protein ◽

Rna Binding Protein ◽

Human Orthologue ◽

And Function ◽

Detailed Picture ◽

Lines Of Evidence

Twenty years ago, the first description of a tristetraprolin (TTP) knockout mouse highlighted the fundamental role of TTP in the restraint of inflammation. Since then, work from several groups has generated a detailed picture of the expression and function of TTP. It is a sequence-specific RNA-binding protein that orchestrates the deadenylation and degradation of several mRNAs encoding inflammatory mediators. It is very extensively post-translationally modified, with more than 30 phosphorylations that are supported by at least two independent lines of evidence. The phosphorylation of two particular residues, serines 52 and 178 of mouse TTP (serines 60 and 186 of the human orthologue), has profound effects on the expression, function and localisation of TTP. Here, we discuss the control of TTP biology via its phosphorylation and dephosphorylation, with a particular focus on recent advances and on questions that remain unanswered.

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Label-Free Automated Cell Tracking: Analysis of the Role of E-cadherin Expression in Collective Electrotaxis

Cellular and Molecular Bioengineering ◽

10.1007/s12195-016-0471-6 ◽

2016 ◽

Vol 10 (1) ◽

pp. 89-101 ◽

Cited By ~ 3

Author(s):

Mark L. Lalli ◽

Brooke Wojeski ◽

Anand R. Asthagiri

Keyword(s):

Cell Tracking ◽

Label Free ◽

E Cadherin

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NMME-based Assessment of Prediction Skills of US Summertime Droughts and Pluvials: Role of Near-surface Temperature Prediction Skill

10.5194/egusphere-egu21-1957 ◽

2021 ◽

Author(s):

Jonghun Kam ◽

Sungyoon Kim ◽

Joshua Roundy

Keyword(s):

Surface Temperature ◽

Climate Extremes ◽

Prediction Skill ◽

Seasonal Forecasts ◽

Near Surface ◽

Anomaly Correlation ◽

The North ◽

Anomaly Correlation Coefficient ◽

Precipitation Anomalies

This study used the North American Multi-Model Ensemble (NMME) system to understand the role of near surface temperature in the prediction skill for US climate extremes. In this study, the forecasting skill was measured by anomaly correlation coefficient (ACC) between the observed and forecasted precipitation (PREC) or 2-meter air temperature (T2m) over the contiguous United States (CONUS) during 1982&#8211;2012. The strength of the PREC-T2m coupling was measured by ACC between observed PREC and T2m or forecasted PREC and T2m over the CONUS. This study also assessed the NMME forecasting skill for the summers of 2004 (spatial anomaly correlation between PREC and T2m: 0.05), 2011 (-0.65), and 2012 (-0.60) when the PREC-T2m coupling is weaker or stronger than the 1982&#8211;2012 climatology (ACC:-0.34). This study found that most of the NMME models show stronger (negative) PREC-T2m coupling than the observed coupling, indicating that they fail to reproduce interannual variability of the observed PREC-T2m coupling. Some NMME models with skillful prediction for T2m show the skillful prediction of the precipitation anomalies and US droughts in 2011 and 2012 via strong PREC-T2m coupling despite the fact that the forecasting skill is year-dependent and model-dependent. Lastly, we explored how the forecasting skill for SSTs over north Pacific and Atlantic Oceans affects the forecasting skill for T2m and PREC over the US. The findings of this study suggest a need for the selective use of the current NMME seasonal forecasts for US droughts and pluvials.

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