Now showing items 21-40 of 41

    • Microbubbles Reveal Chiral Fluid Flows in Bacterial Swarms 

      Wu, Yilin; Hosu, Basarab Gabriel; Berg, Howard Curtis (National Academy of Sciences, 2010)
      Flagellated bacteria can swim within a thin film of fluid that coats a solid surface, such as agar; this is a means for colony expansion known as swarming. We found that micron-sized bubbles make excellent tracers for the ...
    • A Modular Gradient-Sensing Network for Chemotaxis in Escherichia coli Revealed by Responses to Time-Varying Stimuli 

      Shimizu, Thomas S; Tu, Yuhai; Berg, Howard (Nature Publishing Group, 2010)
      The Escherichia coli chemotaxis-signaling pathway computes time derivatives of chemoeffector concentrations. This network features modules for signal reception/amplification and robust adaptation, with sensing of chemoeffector ...
    • Motile Behavior of Bacteria 

      Berg, Howard (American Institute of Physics, 2000)
    • Mutations That Stimulate flhDC Expression in Escherichia coli K-12 

      Fahrner, Karen Alicia; Berg, Howard Curtis (American Society for Microbiology, 2015)
      Motility is a beneficial attribute that enables cells to access and explore new environments and to escape detrimental ones. The organelle of motility in Escherichia coli is the flagellum, and its production is initiated ...
    • Osmotic Pressure in a Bacterial Swarm 

      Ping, Liyan; Wu, Yilin; Hosu, Basarab Gabriel; Tang, Jay Xin; Berg, Howard Curtis (Elsevier BV, 2014)
      Using Escherichia coli as a model organism, we studied how water is recruited by a bacterial swarm. A previous analysis of trajectories of small air bubbles revealed a stream of fluid flowing in a clockwise direction ahead ...
    • Perspectives on working at the physics-biology interface 

      Berg, Howard Curtis; Blagoev, Krastan (IOP Publishing, 2014)
    • Physical Responses of Bacterial Chemoreceptors 

      Vaknin, Ady; Berg, Howard (Elsevier, 2007)
      Chemoreceptors of the bacterium Escherichia coli are thought to form trimers of homodimers that undergo conformational changes upon ligand binding and thereby signal a cytoplasmic kinase. We monitored the physical responses ...
    • Physics of chemoreception 

      Berg, Howard Curtis; Purcell, E.M. (Elsevier BV, 1977)
      Statistical fluctuations limit the precision with which a microorganism can, in a given time T, determine the concentration of a chemoattractant in the surrounding medium. The best a cell can do is to monitor continually ...
    • Response thresholds in bacterial chemotaxis 

      Lele, Pushkar P.; Shrivastava, Abhishek; Roland, Thibault; Berg, Howard C. (American Association for the Advancement of Science, 2015)
      Stimulation of Escherichia coli by exponential ramps of chemoattractants generates step changes in the concentration of the response regulator, CheY-P. Because flagellar motors are ultrasensitive, this should change the ...
    • A Rotary Motor Drives Flavobacterium Gliding 

      Shrivastava, Abhishek; Lele, Pushkar Prakash; Berg, Howard Curtis (Elsevier BV, 2015)
      Cells of Flavobacterium johnsoniae, a rod-shaped bacterium devoid of pili or flagella, glide over glass at speeds of 2–4 μm/s [ 1 ]. Gliding is powered by a protonmotive force [ 2 ], but the machinery required for this ...
    • Single-File Diffusion of Flagellin in Flagellar Filaments 

      Stern, Alan S.; Berg, Howard Curtis (Elsevier BV, 2013)
      A bacterial flagellar filament is a cylindrical crystal of a protein known as flagellin. Flagellin subunits travel from the cytoplasm through a 2 nm axial pore and polymerize at the filament’s distal end. They are supplied ...
    • Spin Exchange and Surface Relaxation in the Atomic Hydrogen Maser 

      Berg, Howard (American Physical Society, 1965)
      An experiment using the atomic-hydrogen maser is described which confirms several predictions of the theory of spin exchange and which provides new information on the spin relaxation of hydrogen at solid surfaces. Atoms ...
    • Spin relaxation of atoms in molecular buffer gases 

      Berg, Howard (American Institute of Physics, 1965)
    • Storage Technique for Atomic Hydrogen 

      Berg, Howard; Kleppner, Daniel (American Institute of Physics, 1962)
    • Switching dynamics of the bacterial flagellar motor near zero load 

      Wang, Fang; Yuan, Junhua; Berg, Howard Curtis (Proceedings of the National Academy of Sciences, 2014)
      Switching dynamics of flagellar motors of Escherichia coli is commonly observed through markers attached to the flagellar filaments. To eliminate possible complications resulting from the conformational transitions of these ...
    • Switching of the Bacterial Flagellar Motor Near Zero Load 

      Yuan, Junhua; Fahrner, Karen Alicia; Berg, Howard (Elsevier, 2009)
      Flagellated bacteria, such as Escherichia coli, are able to swim up gradients of chemical attractants by modulating the direction of rotation of their flagellar motors, which spin alternately clockwise (CW) and counterclockwise ...
    • Thermal and Solvent-Isotope Effects on the Flagellar Rotary Motor near Zero Load 

      Yuan, Junhua; Berg, Howard Curtis (Biophysical Society, 2010)
      In Escherichia coli, the behavior of the flagellar rotary motor near zero load can be studied by scattering light from nanogold spheres attached to proximal hooks of cells lacking flagellar filaments. We used this method to ...
    • Ultrasensitivity of an Adaptive Bacterial Motor 

      Yuan, Junhua; Berg, Howard Curtis (Elsevier BV, 2013)
      The flagellar motor of Escherichia coli adapts to changes in the steady-state level of the chemotaxis response regulator, CheY-P, by adjusting the number of FliM molecules to which CheY-P binds. Previous measurements of ...
    • The Upper Surface of an Escherichia Coli Swarm Is Stationary 

      Zhang, Rongjing; Turner, Linda; Berg, Howard Curtis (National Academy of Sciences, 2010)
      When grown in a rich medium on agar, many bacteria elongate, produce more flagella, and swim in a thin film of fluid over the agar surface in swirling packs. Cells that spread in this way are said to swarm. The agar is a ...
    • Visualization of Flagella during Bacterial Swarming 

      Turner, Linda; Zhang, Rongjing; Darnton, Nicholas C.; Berg, Howard Curtis (American Society for Microbiology, 2010)
      When cells of Escherichia coli are grown in broth and suspended at low density in a motility medium, they swim independently, exploring a homogeneous, isotropic environment. Cell trajectories and the way in which these ...