Motility

  • Article |

    Mechanical load-sharing enables the long-range cooperative uptake of apoptotic cells by multiple epithelial cells; and clearance of these apoptotic cells facilitates error correction, which is necessary for developmental robustness and survival of the embryo.

    • Esteban Hoijman
    • , Hanna-Maria Häkkinen
    •  & Verena Ruprecht
  • Article |

    High-resolution cryo-electron microscopy structure of smooth muscle myosin II in the inhibited state enables increased understanding of the functions of the head and tail regions in regulation of myosin activity and the pathological mechanisms of disease mutations.

    • Shixin Yang
    • , Prince Tiwari
    •  & Roger Craig
  • Article |

    A theoretical framework describing the hydrodynamic interactions between a passive particle and an active medium in out-of-equilibrium systems predicts long-range Lévy flights for the diffusing particle driven by the density of the active component.

    • Kiyoshi Kanazawa
    • , Tomohiko G. Sano
    •  & Adrian Baule
  • Article |

    In mixed bacterial populations that colonize nutrient patches, a growth–migration trade-off can lead to spatial exclusion that provides an advantage to populations that become rare, thereby stabilizing the community.

    • Sebastian Gude
    • , Erçağ Pinçe
    •  & Sander J. Tans
  • Letter |

    Ultra-fast hydrodynamic communication between cells emerges in colonies of Spirostomum ambiguum through the generation of long-ranged vortex flows that are sensed by neighbouring cells, leading to propagating trigger waves that coordinate the release of toxins.

    • Arnold J. T. M. Mathijssen
    • , Joshua Culver
    •  & Manu Prakash
  • Letter |

    It is widely accepted that contraction of skeletal muscle and the heart involves structural changes in actin-containing thin filaments to allow binding of myosin motors from neighbouring thick filaments, thus driving filament sliding; here, X-ray diffraction of single skeletal muscle cells reveals that this thin-filament mechanism can regulate muscle contraction against low load, but high-load contraction requires a second permissive step involving a structural change in the thick filament.

    • Marco Linari
    • , Elisabetta Brunello
    •  & Malcolm Irving
  • Letter |

    Droplets of mixed water and propylene glycol deposited on clean glass exhibit a contact angle but do not suffer from contact line pinning; their motion can be controlled by the vapour emitted from neighbouring droplets to create a variety of autonomous fluidic machines with integrated sensing and motility capabilities.

    • N. J. Cira
    • , A. Benusiglio
    •  & M. Prakash
  • Letter |

    An optogenetic strategy allowing light-mediated recruitment of distinct cytoskeletal motor proteins to specific organelles is established; this technique enabled rapid and reversible activation or inhibition of the transport of organelles such as peroxisomes, recycling endosomes and mitochondria with high spatiotemporal accuracy, and the approach was also applied to primary neurons to demonstrate optical control of axonal growth by recycling endosome repositioning.

    • Petra van Bergeijk
    • , Max Adrian
    •  & Lukas C. Kapitein
  • Letter |

    Growth of a flagellum outside the bacterial cell proceeds by successive subunit acquisition from the cell export machinery to form a chain that is pulled to the flagellum tip, where subunit crystallization provides the entropic force to drive the process.

    • Lewis D. B. Evans
    • , Simon Poulter
    •  & Gillian M. Fraser
  • Letter |

    Populations of millions of colloidal rolling particles are shown to self-organize to achieve coherent motion; comparison between experiment and theory based on the microscopic interactions between these ‘rollers’ suggests that hydrodynamic interactions promote the emergence of the collective motion.

    • Antoine Bricard
    • , Jean-Baptiste Caussin
    •  & Denis Bartolo
  • Letter |

    In his study of Brownian motion, Einstein realized that the same random molecular movements characterizing a substance at rest should affect, for example, the drag it opposes to a particle pushed through it. This was later generalized as the fluctuation–response theorem (FRT), but whether and how it may apply to biological systems, which operate far from equilibrium, has remained an open question. Based on the unmatched fine-scale measurements possible in the study of bacterial chemotaxis, it is now revealed that the FRT does apply in this case, and ways to dissect which features in the biochemical network couple its internal states with its responses to external stimuli are suggested.

    • Heungwon Park
    • , William Pontius
    •  & Philippe Cluzel
  • Article |

    High-speed atomic force microscopy can be used to record the structure and dynamics of biomolecules simultaneously. These authors use this method to directly observe the dynamics of the motor protein myosin V moving along actin filaments, with unprecedented time resolution. The high-resolution movies provide evidence supporting the 'swinging lever-arm' model of myosin motility, and provide important insights into the mechanism of motor movement.

    • Noriyuki Kodera
    • , Daisuke Yamamoto
    •  & Toshio Ando
  • Letter |

    Collective motion is a ubiquitous self-organization phenomenon that can be observed in systems ranging from flocks of animals to the cytoskeleton. Similarities between these systems suggest that there are universal underlying principles. This idea can be tested with 'active' or 'driven' fluids, but so far such systems have offered limited parameter control. Here, an active fluid is studied that contains only a few components — actin filaments and molecular motors — allowing the control of all relevant system parameters.

    • Volker Schaller
    • , Christoph Weber
    •  & Andreas R. Bausch
  • Letter |

    The bacterial flagellar motor drives the rotation of flagellar filaments, propelling bacteria through viscous media. The rotation can switch from an anticlockwise to a clockwise direction, determining a smooth or tumbling motion. A protein called FliG forms a ring in the motor's rotor, and has been proposed to adopt distinct conformations that induce switching. Here, the full-length structure of FliG is presented, and conformational changes are identified that are involved in switching between clockwise and anticlockwise rotations.

    • Lawrence K. Lee
    • , Michael A. Ginsburg
    •  & Daniela Stock
  • Letter |

    Most animal embryos grow through cell accumulation in a posterior growth zone, but the underlying forces are unknown. It is now proposed that posterior elongation in chicken embryos is an emergent property that arises from graded cell motility in random directions (as opposed to directed movement). This occurs in response to signalling through the fibroblast growth factor.

    • Bertrand Bénazéraf
    • , Paul Francois
    •  & Olivier Pourquié
  • Letter |

    Eukaryotic cells crawl through a process in which the front of the cell is propelled forwards by the force provided by polymerization of actin filaments. These must be disassembled at the rear of the cell to allow sustained motility. It is now shown that non-muscle myosin II protein is needed for the disassembly of actin networks at the rear of crawling cells.

    • Cyrus A. Wilson
    • , Mark A. Tsuchida
    •  & Julie A. Theriot