scholarly journals Actuators Displaying Unidirectional Movement

2020 ◽  
pp. 2000214
Author(s):  
Mridula Nandi ◽  
Binoy Maiti ◽  
David Díaz Díaz
Keyword(s):  
Unidirectional Movement

A Mass Unidirectional Movement of Natrix sipedon pictiventris

Copeia ◽  
1961 ◽  
Vol 1961 (4) ◽  
pp. 498 ◽  
Author(s):  
J. Alan Holman ◽  
William Holmes Hill
Keyword(s):  
Unidirectional Movement

scholarly journals Coupled myosin VI motors facilitate unidirectional movement on an F-actin network

2009 ◽  
Vol 187 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Sivaraj Sivaramakrishnan ◽  
James A. Spudich
Keyword(s):  
Single Molecule ◽  
Membrane Trafficking ◽  
Cell Periphery ◽  
Myosin Vi ◽  
Actin Network ◽  
Cortical Actin ◽  
Actin Cortex ◽  
Unidirectional Movement ◽  
Transport Vesicle ◽  
Pointed End

Unconventional myosins interact with the dense cortical actin network during processes such as membrane trafficking, cell migration, and mechanotransduction. Our understanding of unconventional myosin function is derived largely from assays that examine the interaction of a single myosin with a single actin filament. In this study, we have developed a model system to study the interaction between multiple tethered unconventional myosins and a model F-actin cortex, namely the lamellipodium of a migrating fish epidermal keratocyte. Using myosin VI, which moves toward the pointed end of actin filaments, we directly determine the polarity of the extracted keratocyte lamellipodium from the cell periphery to the cell nucleus. We use a combination of experimentation and simulation to demonstrate that multiple myosin VI molecules can coordinate to efficiently transport vesicle-size cargo over 10 µm of the dense interlaced actin network. Furthermore, several molecules of monomeric myosin VI, which are nonprocessive in single molecule assays, can coordinate to transport cargo with similar speeds as dimers.

Unidirectional movement of fluorescent microtubules on rows of dynein arms of disintegrated axonemes

1998 ◽  
Vol 111 (1) ◽  
pp. 93-98 ◽  
Author(s):  
A. Yamada ◽  
T. Yamaga ◽  
H. Sakakibara ◽  
H. Nakayama ◽  
K. Oiwa
Keyword(s):  
Sea Urchin ◽  
Sperm Head ◽  
Microtubule Binding ◽  
Unidirectional Movement ◽  
Dynein Arms ◽  
Sea Urchin Sperm

Tetramethylrhodamine-labelled microtubules were observed to move on rows of dynein arms of sea urchin sperm axonemes exposed by elastase-induced sliding disintegration. The microtubules moved towards the flagellar tip at a velocity of 3.1+/−2.1 microm second-1 (mean +/− s.d., n=53) in the presence of 0.1 mM ATP at 22 degrees C, but none moved towards the sperm head. We also examined the polarity of microtubule binding to axonemal doublet microtubules in the absence of ATP by using microtubules brightly labelled at their minus-ends. In 140 of 210 microtubules studied, they bound to axonemal microtubules with a parallel polarity. These results suggest that tightly packed dynein arms on the outer doublet microtubules of sperm axoneme preferentially bind microtubules to themselves with the same polarity as that of the axoneme and that they generate a force to move only these microtubules in the direction away from the sperm head.

scholarly journals Helicase Mechanisms During Homologous Recombination inSaccharomyces cerevisiae

2019 ◽  
Vol 48 (1) ◽  
pp. 255-273 ◽  
Author(s):  
J. Brooks Crickard ◽  
Eric C. Greene
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nucleic Acid ◽  
Homologous Recombination ◽  
Nucleic Acids ◽  
Acid Metabolism ◽  
Model Organism ◽  
Nucleic Acid Metabolism ◽  
Repair Pathway ◽  
Unidirectional Movement ◽  
Nucleoprotein Complexes

Helicases are enzymes that move, manage, and manipulate nucleic acids. They can be subdivided into six super families and are required for all aspects of nucleic acid metabolism. In general, all helicases function by converting the chemical energy stored in the bond between the gamma and beta phosphates of adenosine triphosphate into mechanical work, which results in the unidirectional movement of the helicase protein along one strand of a nucleic acid. The results of this translocation activity can range from separation of strands within duplex nucleic acids to the physical remodeling or removal of nucleoprotein complexes. In this review, we focus on describing key helicases from the model organism Saccharomyces cerevisiae that contribute to the regulation of homologous recombination, which is an essential DNA repair pathway for fixing damaged chromosomes.

Unidirectional Movement Of Fascin-induced Actin Bundle On Heavy Meromyosin In An In Vitro Motility Assay

2008 ◽  
Vol 40 (Supplement) ◽  
pp. S297
Author(s):  
Hideyo Takatsuki ◽  
Kevin M. Rice ◽  
Shinichi Asano ◽  
Devashish Desai ◽  
Madhukar Kolli ◽  
...  
Keyword(s):  
Motility Assay ◽  
Heavy Meromyosin ◽  
In Vitro Motility Assay ◽  
Actin Bundle ◽  
In Vitro Motility ◽  
Unidirectional Movement

scholarly journals POLARIZED INTERCELLULAR BRIDGES IN OVARIAN FOLLICLES OF THE CECROPIA MOTH

1973 ◽  
Vol 58 (1) ◽  
pp. 172-188 ◽  
Author(s):  
Richard I. Woodruff ◽  
William H. Telfer
Keyword(s):  
Nurse Cell ◽  
Electrical Potential ◽  
The Other ◽  
Rabbit Serum ◽  
Nurse Cells ◽  
Recording Electrode ◽  
Serum Globulin ◽  
Intercellular Bridges ◽  
Apical Cytoplasm ◽  
Unidirectional Movement

Fluorescein-labeled rabbit serum globulin was injected into vitellogenic oocytes of the cecropia moth. Though the label spread throughout the ooplasm in less than 30 min, it was unable even after 2 h to cross the complex of intercellular bridges connecting the oocyte to its seven nurse cells. After injection into a single nurse cell, fluorescence was detected in the oocyte adjacent to the bridge complex within 3 min and had spread throughout the ooplasm in 30 min. Here also, the cell bodies of the six uninjected nurse cells remained nonfluorescent. Four of the nurse cells are not bridged directly to the oocyte but only through the apical ends of their siblings. Unidirectional movement must therefore occur in the apical cytoplasm of the nurse cells, as well as in the intercellular bridges. The nurse cells of healthy follicles had an intracellular electrical potential -40 mV relative to blood or dissecting solution, while oocytes measured -30 mV. A mV difference was also detected by direct comparison between a ground electrode in one cell and a recording electrode in the other. Three conditions were found in which the 10 mV difference was reduced or reversed in polarity. In all three cases fluorescent globulin was able in some degree to cross the bridges from the oocyte to the nurse cells.

scholarly journals Mechanical and signaling mechanisms that guide pre-implantation embryo movement

2020 ◽  
Author(s):  
Diana Flores ◽  
Manoj Madhavan ◽  
Savannah Wright ◽  
Ripla Arora
Keyword(s):  
Physical Object ◽  
Reproductive Technologies ◽  
Mechanical Stimulus ◽  
Muscle Contractions ◽  
Confocal Imaging ◽  
Mammalian Embryo ◽  
Unique Challenge ◽  
Equal Distribution ◽  
3D Image Reconstruction ◽  
Unidirectional Movement

ABSTRACTHow a mammalian embryo determines and arrives at its site of attachment is a mystery that has puzzled researchers for decades. Additionally, in multiparous species, embryos face a unique challenge of achieving adequate spacing to avoid competition for maternal resources. Using our enhanced confocal imaging and 3D image reconstruction technology, we evaluate murine embryo location in the uterus along the longitudinal oviductal-cervical axis. Our analysis reveals three distinct pre-implantation stages: a) Embryo entry; b) Unidirectional movement of embryo clusters; and c) Bidirectional scattering and spacing of embryos. We show that unidirectional movement of embryo clusters is facilitated by a mechanical stimulus of the embryo as a physical object and is regulated by adrenergic uterine smooth muscle contractions. Embryo scattering, on the other hand, relies on embryo-uterine communication reliant on the LPAR3 signaling pathway and is independent of adrenergic muscle contractions. We propose that the presence of embryo clusters in the uterine horn provides an opportunity for the uterus to sense and count the embryos, followed by scattering and spacing these embryos along the given length of the horn. Thus, uterine implantation sites in mice are neither random nor predetermined but are guided by the number of embryos entering the uterine lumen. These studies have implications for understanding how embryo-uterine communication is key to determining an optimal implantation site, which is necessary for the success of a pregnancy.Significance StatementIn mammals that carry multiple offspring in one gestation, embryos seemingly acquire even embryo spacing. Such even distribution would imply a guided interaction between the mother and the fetus very early on in pregnancy to allow favorable pregnancy outcomes. Thus, it is essential to understand quantitatively if and when such a uniform distribution of embryos is established. Further, uncovering the physical and biological mechanisms that allow for such equal distribution of embryos, will improve our understanding of early pregnancy events and provide for novel targets for improving pregnancy success in case of infertility and artificial reproductive technologies as well as to develop non-hormonal therapies for contraception.

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