A new class of biological ion-driven rotary molecular motors with 5:2 symmetry.

Frontiers in microbiology 13 (2022) 948383

Authors:

Martin Rieu, Roscislaw Krutyholowa, Nicholas MI Taylor, Richard M Berry

Abstract:

Several new structures of three types of protein complexes, obtained by cryo-electron microscopy (cryo-EM) and published between 2019 and 2021, identify a new family of natural molecular wheels, the "5:2 rotary motors." These span the cytoplasmic membranes of bacteria, and their rotation is driven by ion flow into the cell. They consist of a pentameric wheel encircling a dimeric axle within the cytoplasmic membrane of both Gram-positive and gram-negative bacteria. The axles extend into the periplasm, and the wheels extend into the cytoplasm. Rotation of these wheels has never been observed directly; it is inferred from the symmetry of the complexes and from the roles they play within the larger systems that they are known to power. In particular, the new structure of the stator complex of the Bacterial Flagellar Motor, MotA5B2, is consistent with a "wheels within wheels" model of the motor. Other 5:2 rotary motors are believed to share the core rotary function and mechanism, driven by ion-motive force at the cytoplasmic membrane. Their structures diverge in their periplasmic and cytoplasmic parts, reflecting the variety of roles that they perform. This review focuses on the structures of 5:2 rotary motors and their proposed mechanisms and functions. We also discuss molecular rotation in general and its relation to the rotational symmetry of molecular complexes.

Accurate Baryon Acoustic Oscillations reconstruction via semi-discrete optimal transport

(2021)

Authors:

Sebastian VON HAUSEGGER, Bruno Lévy, Roya Mohayaee

Quantifying vascularity in the frontoparietal dome of Stegoceras validum (Dinosauria: Pachycephalosauridae) from high resolution CT scans

Journal of Vertebrate Paleontology Taylor & Francis 41:5 (2021) e2036991

Authors:

Jasmine A Nirody, Mark B Goodwin, John R Horner, Tony L Huynh, Matthew W Colbert, David K Smith, David C Evans

Tardigrades exhibit robust interlimb coordination across walking speeds and terrains

Proceedings of the National Academy of Sciences National Academy of Sciences 118:35 (2021) e2107289118

Authors:

Jasmine A Nirody, Lisset A Duran, Deborah Johnston, Daniel J Cohen

Abstract:

Tardigrades must negotiate heterogeneous, fluctuating environments and accordingly utilize locomotive strategies capable of dealing with variable terrain. We analyze the kinematics and interleg coordination of freely walking tardigrades (species: Hypsibius exemplaris). We find that tardigrade walking replicates several key features of walking in insects despite disparities in size, skeleton, and habitat. To test the effect of environmental changes on tardigrade locomotor control circuits we measure kinematics and interleg coordination during walking on two substrates of different stiffnesses. We find that the phase offset between contralateral leg pairs is flexible, while ipsilateral coordination is preserved across environmental conditions. This mirrors similar results in insects and crustaceans. We propose that these functional similarities in walking coordination between tardigrades and arthropods is either due to a generalized locomotor control circuit common to panarthropods or to independent convergence onto an optimal strategy for robust multilegged control in small animals with simple circuitry. Our results highlight the value of tardigrades as a comparative system toward understanding the mechanisms—neural and/or mechanical—underlying coordination in panarthropod locomotion.

A fast semidiscrete optimal transport algorithm for a unique reconstruction of the early Universe

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 506:1 (2021) 1165-1185

Authors:

Bruno Levy, Roya Mohayaee, Sebastian von Hausegger