scholarly journals Nano-particles carried by multiple dynein motors: A Self-Regulating Nano-Machine

2020 ◽  
Author(s):  
I. Fayer ◽  
G. Halbi ◽  
D. Aranovich ◽  
S. Gat ◽  
S. Bar ◽  
...  
Keyword(s):  
Active Transport ◽  
Optimal Transport ◽  
Cytoplasmic Dynein ◽  
Nano Particles ◽  
Helical Motion ◽  
Dynein Motor ◽  
Cellular Environment ◽  
Long Run ◽  
Long Time ◽  
Run Lengths

AbstractNative cargos demonstrate efficient intra-cellular active transport. Here we investigate the motion of spherical nano-particles (NPs) grafted with flexible polymers, each ending with a nuclear localization signal peptide, thereby allowing recruitment of mammalian cytoplasmic dynein. Bead-motility assays show several unique motility features, depending on the number of NP-bound motors. NPs perform angular motion, in which the plus-end directed and right-handed motions are correlated. To simulate the system, we formulate a theoretical model that builds on single mammalian dynein properties, generalized to include motor-motor elastic and excluded-volume interactions. We find that long time trajectories exhibit both left- and right-handed helical motion, consistent with the measured angular velocity. The number of participating motors is self-regulated, thus allowing the NP to benefit from alternations between single and multiple transporting motors. Native cargos could use a similar approach to achieve both obstacle bypassing and persistent motion in the crowded cellular environment.Significance StatementThe mechanism of active transport of native cargos, such as some viruses, is a long-standing conundrum. Their need for persistence motion towards the nucleus, while bypassing obstacles in the super-crowded intracellular milieu, requires sophisticated natural design. To fathom this machinery, we study a smartly designed nano-particle that recruits several dynein motor-proteins from the cytoplasm. Motility assays and model simulations reveal long run-times, long run-lengths, and helical motion around the microtubule symmetry axis. Moreover, the nano-particles self-regulate the number of dyneins participating in the motion, which optimizes its motility properties. We suggest that alternating between single motor motility, which we believe is beneficial for obstacle bypassing, and multiple motor states, which engender persistent motion towards the nucleus, the NP achieves optimal transport efficiency.

scholarly journals Nano-Particles Carried by Multiple Dynein Motors Self-Regulate Their Number of Actively Participating Motors

2021 ◽  
Vol 22 (16) ◽  
pp. 8893
Author(s):  
Gal Halbi ◽  
Itay Fayer ◽  
Dina Aranovich ◽  
Shachar Gat ◽  
Shay Bar ◽  
...  
Keyword(s):  
Active Transport ◽  
Self Regulation ◽  
Nano Particles ◽  
Universal Curve ◽  
Helical Motion ◽  
Model Simulations ◽  
System Composition ◽  
Long Time ◽  
Localization Signal ◽  
Run Lengths

Intra-cellular active transport by native cargos is ubiquitous. We investigate the motion of spherical nano-particles (NPs) grafted with flexible polymers that end with a nuclear localization signal peptide. This peptide allows the recruitment of several mammalian dynein motors from cytoplasmic extracts. To determine how motor–motor interactions influenced motility on the single microtubule level, we conducted bead-motility assays incorporating surface adsorbed microtubules and combined them with model simulations that were based on the properties of a single dynein. The experimental and simulation results revealed long time trajectories: when the number of NP-ligated motors Nm increased, run-times and run-lengths were enhanced and mean velocities were somewhat decreased. Moreover, the dependence of the velocity on run-time followed a universal curve, regardless of the system composition. Model simulations also demonstrated left- and right-handed helical motion and revealed self-regulation of the number of microtubule-bound, actively transporting dynein motors. This number was stochastic along trajectories and was distributed mainly between one, two, and three motors, regardless of Nm. We propose that this self-regulation allows our synthetic NPs to achieve persistent motion that is associated with major helicity. Such a helical motion might affect obstacle bypassing, which can influence active transport efficiency when facing the crowded environment of the cell.

The Problem of Identifying and Modeling the Relationship between Monetary Factor and Inflation in the Russian Economy

2008 ◽  
pp. 61-76
Author(s):  
A. Porshakov ◽  
A. Ponomarenko
Keyword(s):  
Money Supply ◽  
Money Demand ◽  
Russian Economy ◽  
Long Run ◽  
Complex Approach ◽  
Wide Range ◽  
Long Time ◽  
The Relationship ◽  
Supply Side Factors

The role of monetary factor in generating inflationary processes in Russia has stimulated various debates in social and scientific circles for a relatively long time. The authors show that identification of the specificity of relationship between money and inflation requires a complex approach based on statistical modeling and involving a wide range of indicators relevant for the price changes in the economy. As a result a model of inflation for Russia implying the decomposition of inflation dynamics into demand-side and supply-side factors is suggested. The main conclusion drawn is that during the recent years the volume of inflationary pressures in the Russian economy has been determined by the deviation of money supply from money demand, rather than by money supply alone. At the same time, monetary factor has a long-run spread over time impact on inflation.

scholarly journals Functional interaction between dynein light chain and intermediate chain is required for mitotic spindle positioning

2011 ◽  
Vol 22 (15) ◽  
pp. 2690-2701 ◽  
Author(s):  
Melissa D. Stuchell-Brereton ◽  
Amanda Siglin ◽  
Jun Li ◽  
Jeffrey K. Moore ◽  
Shubbir Ahmed ◽  
...  
Keyword(s):  
Light Chain ◽  
Direct Evidence ◽  
Retrograde Transport ◽  
Cytoplasmic Dynein ◽  
Dynein Light Chain ◽  
Spindle Positioning ◽  
Dynein Motor ◽  
Intermediate Chains ◽  
Activator Complex

Cytoplasmic dynein is a large multisubunit complex involved in retrograde transport and the positioning of various organelles. Dynein light chain (LC) subunits are conserved across species; however, the molecular contribution of LCs to dynein function remains controversial. One model suggests that LCs act as cargo-binding scaffolds. Alternatively, LCs are proposed to stabilize the intermediate chains (ICs) of the dynein complex. To examine the role of LCs in dynein function, we used Saccharomyces cerevisiae, in which the sole function of dynein is to position the spindle during mitosis. We report that the LC8 homologue, Dyn2, localizes with the dynein complex at microtubule ends and interacts directly with the yeast IC, Pac11. We identify two Dyn2-binding sites in Pac11 that exert differential effects on Dyn2-binding and dynein function. Mutations disrupting Dyn2 elicit a partial loss-of-dynein phenotype and impair the recruitment of the dynein activator complex, dynactin. Together these results indicate that the dynein-based function of Dyn2 is via its interaction with the dynein IC and that this interaction is important for the interaction of dynein and dynactin. In addition, these data provide the first direct evidence that LC occupancy in the dynein motor complex is important for function.

scholarly journals Stable tug-of-war between kinesin-1 and cytoplasmic dynein upon different ATP and roadblock concentrations

2020 ◽  
Author(s):  
Gina A. Monzon ◽  
Lara Scharrel ◽  
Ashwin DSouza ◽  
Ludger Santen ◽  
Stefan Diez
Keyword(s):  
Cytoplasmic Dynein ◽  
Gliding Motility ◽  
Force Balance ◽  
Stochastic Simulations ◽  
Transport Systems ◽  
Organelle Transport ◽  
Atp Concentration ◽  
Dynein Motor ◽  
Bidirectional Movement

ABSTRACTThe maintenance of intracellular processes like organelle transport and cell division depend on bidirectional movement along microtubules. These processes typically require kinesin and dynein motor proteins which move with opposite directionality. Because both types of motors are often simultaneously bound to the cargo, regulatory mechanisms are required to ensure controlled directional transport. Recently, it has been shown that parameters like mechanical motor activation, ATP concentration and roadblocks on the microtubule surface differentially influence the activity of kinesin and dynein motors in distinct manners. However, how these parameters affect bidirectional transport systems has not been studied. Here, we investigate the regulatory influence of these three parameter using in vitro gliding motility assays and stochastic simulations. We find that the number of active kinesin and dynein motors determines the transport direction and velocity, but that variations in ATP concentration and roadblock density have no significant effect. Thus, factors influencing the force balance between opposite motors appear to be important, whereas the detailed stepping kinetics and bypassing capabilities of the motors have only little effect.

scholarly journals Vannamei shrimp cultivation technology as an innovation of coastal land use in Rugemuk village Pulau Labu sub-district Deli Serdang district in 2019

2019 ◽  
Vol 4 (2) ◽  
pp. 232-236
Author(s):  
Irnawati Marsaulina ◽  
Harlem Marpaung
Keyword(s):  
Appropriate Technology ◽  
Shrimp Farming ◽  
Shrimp Culture ◽  
Long Run ◽  
Third Stage ◽  
Service Activity ◽  
Long Time ◽  
Coastal Land Use ◽  
Cultivation Technology ◽  
Shrimp Cultivation

This community service activity aims to increase the ability of fishermen and apply appropriate technology to cultivate Vannamei shrimp in a sustainable manner so that it will improve the welfare of fishermen's families. To achieve the objectives, several stages of activities are carried out, the first stage of the survey is to find out how the fish cultivator fishermen groups carry out their activities. The second stage is the socialization of activities that will be carried out to increase the ability to grow shrimp so that the results in a long time can increase the income (economy) of the fishermen. The third stage is to carry out coaching and counseling related to shrimp farming and can make decisions in the next economic field. This service program is carried out within 6 months. Program targets and outcomes (1). Increased knowledge and skills on appropriate technology in conducting Vannamei shrimp cultivation (2). Increased Vannamei shrimp yields by conducting shrimp culture training using tarpaulins. (3). In the long run, the results of aquaculture increase the economic welfare of the fishermen's family.

scholarly journals Structural Breaks and Explosive Behavior in the Long-Run: The Case of Australian Real House Prices, 1870–2020

2021 ◽  
Vol 15 (1) ◽  
pp. 72-84
Author(s):  
Vicente Esteve ◽  
Maria A. Prats
Keyword(s):  
Time Series ◽  
Unit Root ◽  
Structural Breaks ◽  
House Prices ◽  
Unit Root Tests ◽  
Annual Data ◽  
Bubble Behavior ◽  
Long Period ◽  
Long Run ◽  
Long Time

Abstract In this article, we use tests of explosive behavior in real house prices with annual data for the case of Australia for the period 1870–2020. The main contribution of this paper is the use of very long time series. It is important to use longer span data because it offers more powerful econometric results. To detect episodes of potential explosive behavior in house prices over this long period, we use the recursive unit root tests for explosiveness proposed by Phillips et al. (2011), (2015a,b). According to the results, there is a clear speculative bubble behavior in real house prices between 1997 and 2020, speculative process that has not yet been adjusted.

Rab3D directs organelle transport by recruiting cytoplasmic dynein motor protein Tctex-1 to secretory membranes of osteoclast

Bone ◽  
2009 ◽  
Vol 44 ◽  
pp. S160 ◽  
Author(s):  
N.J. Pavlos ◽  
J. Xu ◽  
H. Feng ◽  
P. Ng ◽  
T. Cheng ◽  
...  
Keyword(s):  
Motor Protein ◽  
Cytoplasmic Dynein ◽  
Organelle Transport ◽  
Dynein Motor

The microtubule motor cytoplasmic dynein is required for spindle orientation during germline cell divisions and oocyte differentiation in Drosophila

Development ◽  
1997 ◽  
Vol 124 (12) ◽  
pp. 2409-2419 ◽  
Author(s):  
M. McGrail ◽  
T.S. Hays
Keyword(s):  
Asymmetric Cell Division ◽  
Fruit Fly ◽  
Cytoplasmic Dynein ◽  
Spindle Orientation ◽  
Chain Gene ◽  
Animal Development ◽  
Dynein Motor ◽  
Microtubule Motor ◽  
Two Stages ◽  
Oocyte Differentiation

During animal development cellular differentiation is often preceded by an asymmetric cell division whose polarity is determined by the orientation of the mitotic spindle. In the fruit fly, Drosophila melanogaster, the oocyte differentiates in a 16-cell syncytium that arises from a cystoblast which undergoes 4 synchronous divisions with incomplete cytokinesis. During these divisions, spindle orientation is highly ordered and is thought to impart a polarity to the cyst that is necessary for the subsequent differentiation of the oocyte. Using mutations in the Drosophila cytoplasmic dynein heavy chain gene, Dhc64C, we show that cytoplasmic dynein is required at two stages of oogenesis. Early in oogenesis, dynein mutations disrupt spindle orientation in dividing cysts and block oocyte determination. The localization of dynein in mitotic cysts suggests spindle orientation is mediated by the microtubule motor cytoplasmic dynein. Later in oogenesis, dynein function is necessary for proper differentiation, but does not appear to participate in morphogen localization within the oocyte. These results provide evidence for a novel developmental role for the cytoplasmic dynein motor in cellular determination and differentiation.

An implementation of geometric integration within Matlab

SIMULATION ◽  
2019 ◽  
Vol 95 (11) ◽  
pp. 1055-1067
Author(s):  
Guillaume Chauvon ◽  
Philippe Saucez ◽  
Alain Vande Wouwer
Keyword(s):  
Kepler Problem ◽  
Size Composition ◽  
Variable Step Size ◽  
Step Size ◽  
System Variable ◽  
Geometric Integrators ◽  
Long Run ◽  
Variable Step ◽  
Long Time ◽  
Better Than

Geometric integrators allow preservation of specific geometric properties of the exact flow of differential equation systems, such as energy, phase-space volume, and time-reversal symmetry, and are particularly reliable for long-run integration. In this study, variable step size composition methods and Gauss methods are implemented in Matlab library integrators, and are tested with several representative problems, including the Kepler problem, the outer solar system and a conservative Lotka–Volterra system. Variable step size integrators often perform better than their fixed step size counterparts and the numerical results show excellent long time preservation of the Hamiltonian in these examples.

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