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.

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.

Transformations of Self-Regulation and New Public Regulations in the Field of Swiss Corporate Governance (1985-2002)

2007 ◽  
Vol 3 (2) ◽  
Author(s):  
Andre Mach ◽  
Gerhard Schnyder ◽  
Thomas David ◽  
Martin Lupold
Keyword(s):  
Corporate Governance ◽  
Self Regulation ◽  
Legal Framework ◽  
Stock Exchanges ◽  
Private Governance ◽  
Proxy Voting ◽  
New Public ◽  
Long Time ◽  
Accounting Rules ◽  
Takeover Bids

Switzerland was for a very long time characterised by a strong tradition of self-regulation by private actors in the economic sphere rather than by an extensive and detailed legal framework. This is particularly true in the field of corporate governance and more precisely visible in the Stock Corporation Law, the supervision of the stock exchanges and accounting rules. Due to very lax legal rules, mechanisms of "private governance" complemented the minimal legal framework in these three fields. Over the last twenty or so years, these mechanisms of self-regulation have nonetheless undergone profound change. In fact, private self-regulation has been incrementally formalised and replaced by more specific public regulations in five important fields: the transferability of shares, proxy-voting by banks, takeover bids, supervision of the stock exchanges and accounting rules. Due to changes in the international context, to the shifting preferences of important economic actors, and to the emergence of new actors (institutional investors and accountants), the legal framework of Swiss corporate governance has been reformed in a significant way.

scholarly journals The effect of the standing angle on reducing fatigue among prolonged standing workers

Work ◽  
2021 ◽  
Vol 68 (s1) ◽  
pp. S281-S287
Author(s):  
Zhihui Liu ◽  
Li Wang ◽  
Fanlei Kong ◽  
Xia Huang ◽  
Zhi Tang ◽  
...  
Keyword(s):  
Lower Limb ◽  
Self Regulation ◽  
Sampling Point ◽  
Prolonged Standing ◽  
Plantar Pressures ◽  
Lower Limb Muscles ◽  
Long Time ◽  
Foot Pad ◽  
Information Change ◽  
The Relationship

BACKGROUND: Many occupations require workers to stand for prolonged periods, which can cause discomfort, pain and even injures. Some supermarkets in life provide a foot pad for checkout staff to let them stand on it at work, thereby reducing standing fatigue caused by standing for a long time. The inclined platform is the same as the foot pad mentioned above. That is, the staff stepped on it and relieved standing fatigue to a certain extent. OBJECTIVE: The study aims to analyze how the standing angle affects fatigue among prolonged standing workers and tries to find an inclined platform with a specific angle to reduce standing fatigue. METHODS: This experiment studied fatigue of the inclined platforms with different angles on prolonged standing workers, eight participants were selected to participate in the test. The plantar pressures and sEMG (Surface Electromyography) were used to collect the physiological information change of prolonged standing participants in the lower limb and waist. The visual analogue scale was used as a subjective method to measure the psychological fatigue. RESULTS AND CONCLUSION: The study highlights the relationship between standing angle and lower limb fatigue. The inclination of the standing platform has different effects on the participants under different time conditions. When participants stand on inclined platforms at 0°, 5° and 10°, the iEMG (Integrated Electromyography) values of the gastrointestinal muscle were not significantly different until the third sampling point (40 minutes). After that self-regulation of lower limb muscles is better when standing on an inclined platform between 5° and 10°, it has a certain effect on alleviating lower limb fatigue. This knowledge is crucial for the design of the inclined working platforms fitting the needs of prolonged standing workers.

Ouabain modulation of cellular calcium stores and signaling

2007 ◽  
Vol 293 (5) ◽  
pp. F1518-F1532 ◽  
Author(s):  
Aurélie Edwards ◽  
Thomas L. Pallone
Keyword(s):  
Mathematical Model ◽  
Sarcoplasmic Reticulum ◽  
Active Transport ◽  
Intracellular Localization ◽  
Calcium Stores ◽  
Model Simulations ◽  
Store Depletion ◽  
Intracellular Ca ◽  
Atpase Inhibition ◽  
Predominant Effect

Ouabain-like factors modulate intracellular Ca2+ concentrations and Ca2+ stores. Recently, a role for Na+-K+-ATPase Na+ transport inhibition as a pivotal event in ouabain signaling was questioned (Kaunitz JD. Am J Physiol Renal Physiol 290: F995–F996, 2006). In the present study, we used a mathematical model of Ca2+ trafficking in cytoplasm and subplasmalemmal microdomains to simulate the pathways through which ouabain can affect Ca2+ signaling: inhibition of active transport by Na+-K+-ATPase α1- and α2-isoforms, activation of inositol trisphosphate (IP3) production, and increased IP3 receptor (IP3R) conductance. A fundamental prediction is that Na+-K+-ATPase inhibition favors sarcoplasmic reticulum Ca2+ store loading, whereas Src-mediated increases in IP3 production and IP3R sensitization favor store depletion. The model predicts that α2-isoform inhibition generates a peak-and-plateau pattern of cytosolic Ca2+ concentration ([Ca2+]cyt) elevation, whereas α1-isoform inhibition yields a monophasic rise. The effects of ouabain-mediated increases in IP3 production or IP3R conductance on [Ca2+]cyt depend on their relative distributions between cellular microdomains and the bulk cytoplasm. Simulations suggest that the intracellular localization of IP3 production is a pivotal determinant of the changes in compartmental Ca2+ concentrations that can be induced by ouabain. As a consequence of sequestration of the ouabain-sensitive α2-isoform into microdomains, inhibition of the α2-isoform in rodents is not predicted to significantly affect cytosolic Na+ concentration. Model simulations support the hypothesis that ouabain can enhance agonist-evoked [Ca2+]cyt transients when its predominant effect is to inhibit α2-isoform Na+ transport and, thereby, increase Ca2+ loading into sarcoplasmic reticulum stores.

scholarly journals Self-regulation of journalism in Spain

2015 ◽  
pp. 29-35
Author(s):  
A. N. Rylova
Keyword(s):  
Freedom Of Expression ◽  
Time Lag ◽  
Self Regulation ◽  
Professional Community ◽  
The State ◽  
State Control ◽  
Western Countries ◽  
Long Time ◽  
Rules And Principles ◽  
History Of

Self-regulation of journalism resides in voluntary measures taken by the professional community of journalists to guarantee the observation of certain rules and principles in the process of providing information to public, maintain independence and credibility of media. The institution of self-regulation of Spanish journalism emerged later than in other Western countries due to the history of interaction between the State and media: for a long time Spanish media were under State control and freedom of expression was constantly defied. That is why first attempts to establish bodies for self-regulation of journalism in the post-Franco Spain evoked fears of a return to censorship. However, the time lag concerning media self- regulation allowed Spain to use other countries’ experience. Nowadays, the degree of self-regulation of journalism in Spain is similar to that of the Western countries. The institution of self-regulation operates successfully and facilitates Spanish media authority.

Improved Preparation Technology of Urea Formaldehyde Microcapsules Used in Electrophoretic Display

2009 ◽  
Vol 79-82 ◽  
pp. 381-384
Author(s):  
Shu Hui Chen ◽  
Shi Rong Wang ◽  
Shu Guang Bian ◽  
Xiang Gao Li
Keyword(s):  
Electric Field ◽  
Response Time ◽  
Mechanical Strength ◽  
In Situ Polymerization ◽  
Urea Formaldehyde ◽  
Nano Particles ◽  
Preparation Technology ◽  
Electrophoretic Display ◽  
Long Time

Improved two step in-situ polymerization was applied in the preparation of urea- formaldehyde microcapsules used in microencapsulated electrophoretic display. The dispersion liquid which nano particles of titanium dioxide and carbon black dispersed in tetrachloroethylene was used as the electrophoretic liquid, and the electrophoresis microcapsules was prepared by urea-formaldehyde system. Melamine was used to modify the urea-formaldehyde microcapsules. The effect of different mole rates of urea and melamine to the surface morphology, mechanical strength, and sphericity of the microcapsules were studied. Electrophoretic performance of particles in melamine-urea-formaldehyde (MUF) microcapsules and urea-formaldehyde (UF) microcapsules were contrasted under the same condition. The results showed that as adding melamine in urea-formaldehyde, the time used to prepare microcapsules was shorter, and microcapsules were not easy aggregation during long time storage. When the mole rates of melamine and urea were from 2:8 to 5:5, the microcapsules with smoother surface (Fig.1), stronger mechanical strength and higher transmittance were obtained. Electrophoretic behaviors of particles in MUF (melamine and urea was 2:8 in mole rate) and UF microcapsules were tested under the same condition, respectively. It was shown that particles in MUF microcapsules could be seen significantly moving at the electric field of 10 V/mm, and the response time of these particles was 500 ms at the electric field of 20 V/mm，and it was shorter than 200 ms at the 50 V/mm electric field (Fig.2). On the contrast, the response time of particles in UF microcapsules was greater than 10 s at the electric field of 20 V/mm.

The Study in the Toxic Effects of the Material Bisphenol A at Long Time Exposure

2013 ◽  
Vol 641-642 ◽  
pp. 1010-1014
Author(s):  
Zheng Hua Duan ◽  
Hua Wang ◽  
Xiao Hao Zhang ◽  
Ning Tao Li
Keyword(s):  
Bisphenol A ◽  
Self Regulation ◽  
Dose Effect ◽  
Rt Pcr ◽  
Chronic Effects ◽  
Baby Bottles ◽  
Food And Beverage ◽  
Long Time ◽  
Female Zebrafish ◽  
Zebrafish Liver

Bisphenol a (BPA), is a chemical that has been used for more than 40 years in the manufacture of many hard plastic food containers such as baby bottles and reusable cups and the lining of metal food and beverage cans, including canned liquid infant formula. Therefore, it is very necessary to study its health risk and ecological risk. In this paper, four typical estrogen acceptor genes (AHR1, ESR1, VTG1 and VTG3) in female zebrafish liver were studied to assess the low dose and chronic effects of bisphenol A (BPA), with the method of quantitative real-time RT-PCR, and the ability of self regulation and repair of these genes were also discussed. The results showed that these genes could be induced even at 15 ug/L BPA, and VTG 3 was the most sensitive gene. VTG 3 and VTG 1 had obvious self repair and adjustment ability when BPA risk was removed. No monotonic dose-effect relationships of BPA were also found at this study.

scholarly journals Polymer-Cement Composites Glazing by Concentrated Solar Energy

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 350
Author(s):  
Liana Baltes ◽  
Silvia Patachia ◽  
Ozgur Ekincioglu ◽  
Hulusi Ozkul ◽  
Catalin Croitoru ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Solar Radiation ◽  
Vertical Axis ◽  
High Water ◽  
Scratch Resistance ◽  
Nano Particles ◽  
Solar Furnace ◽  
Cement Composites ◽  
Concentrated Solar Energy ◽  
Long Time

Macro defect free (MDF) cements are polymer-cement composites characterized by high biaxial flexural strength compared to traditional concrete, having as a drawback a low water resistance. Glazing these composite materials with an inorganic enamel containing TiO2 nano-particles has led to a high water-stable material with advanced photocatalytic properties. Classic glazing by thermal treatment of samples, at 1050 °C, requires energy consumption and long-time performing. The purpose of this paper is to test the use of solar radiation as a source of energy in the glazing process. A vertical axis solar furnace has been used, from PROMES-CNRS Solar Laboratory, Font-Romeu Odeillo, France, and it has been observed that a uniform appearance of the glaze coating has been achieved; it shows high scratch resistance, meaning a good hardness and adhesion to the substrate. The obtained film was also characterized by SEM, EDS and XRD, aiming to evidence the coat morphology, the TiO2 distribution and its crystallinity alteration, when compared to the samples obtained by classic thermal treatment. The conclusion of the paper is that using solar radiation in the MDF cement glazing process is a promising approach for obtaining multifunctional materials.

scholarly journals Physical Crop Postharvest Storage and Protection Methods

Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 93
Author(s):  
Marek Kopacki ◽  
Joanna Pawłat ◽  
Barbara Skwaryło-Bednarz ◽  
Agnieszka Jamiołkowska ◽  
Patrycja Maria Stępniak ◽  
...  
Keyword(s):  
Low Temperature ◽  
Plant Protection ◽  
Self Regulation ◽  
Physical Method ◽  
Plant Production ◽  
Physical Factors ◽  
Low Temperature Plasma ◽  
Temperature Plasma ◽  
Application Techniques ◽  
Long Time

Sustainable and organic plant production uses natural products and natural self-regulation processes occurring in the ecosystem. The awareness is growing and the demands of consumers are higher and higher. One solution is to use various methods, as an alternative to pesticides. It is also very important to care for the stored crops after harvesting especially using non-chemical methods. The physical method of plant protection consists in treating the harmful organism with physical factors such as temperature, its same light and radiation, controlled atmosphere, special packaging, pressure, various sounds, ozone, and low-temperature plasma. The availability of effective application techniques opens up new possibilities for the storage of crops in order to maintain their health and quality for a long time. This review focuses on the analysis of physical methods of postharvest protection, especially the latest methods using ozone and low-temperature plasma. As a result, consumers of agricultural crops will be able to consume food free of insects, mycotoxins and pesticide residues.

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