scholarly journals Non-uniform membrane diffusion enables steady-state cell polarization via vesicular trafficking

2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Brian D. Slaughter ◽  
Jay R. Unruh ◽  
Arupratan Das ◽  
Sarah E. Smith ◽  
Boris Rubinstein ◽  
...  
Keyword(s):  
Steady State ◽  
Cell Polarization ◽  
Vesicular Trafficking ◽  
Membrane Diffusion ◽  
Uniform Membrane

scholarly journals Constitutive recycling of the store-operated Ca2+ channel Orai1 and its internalization during meiosis

2010 ◽  
Vol 191 (3) ◽  
pp. 523-535 ◽  
Author(s):  
Fang Yu ◽  
Lu Sun ◽  
Khaled Machaca
Keyword(s):  
Steady State ◽  
Cell Membrane ◽  
Subcellular Localization ◽  
Oocyte Maturation ◽  
Vesicular Trafficking ◽  
Endocytic Pathway ◽  
Consensus Binding Site ◽  
Significant Percentage ◽  
Store Depletion ◽  
N Terminus

The egg’s competency to activate at fertilization and transition to embryogenesis is dependent on its ability to generate a fertilization-specific Ca2+ transient. To endow the egg with this capacity, Ca2+ signals remodel during oocyte maturation, including inactivation of the primary Ca2+ influx pathway store-operated Ca2+ entry (SOCE). SOCE inactivation is coupled to internalization of the SOCE channel, Orai1. In this study, we show that Orai1 internalizes during meiosis through a caveolin (Cav)- and dynamin-dependent endocytic pathway. Cav binds to Orai1, and we map a Cav consensus–binding site in the Orai1 N terminus, which is required for Orai1 internalization. Furthermore, at rest, Orai1 actively recycles between an endosomal compartment and the cell membrane through a Rho-dependent endocytic pathway. A significant percentage of total Orai1 is intracellular at steady state. Store depletion completely shifts endosomal Orai1 to the cell membrane. These results define vesicular trafficking mechanisms in the oocyte that control Orai1 subcellular localization at steady state, during meiosis, and after store depletion.

Pulmonary diffusing capacity of athletes

1963 ◽  
Vol 18 (4) ◽  
pp. 687-695 ◽  
Author(s):  
E. M. Mostyn ◽  
S. Helle ◽  
J. B. L. Gee ◽  
L. G. Bentivoglio ◽  
D. V. Bates
Keyword(s):  
Steady State ◽  
Normal Subjects ◽  
Membrane Diffusion ◽  
Distance Runners ◽  
Long Distance ◽  
Pulmonary Capillary ◽  
Capillary Blood Volume ◽  
Pulmonary Capillary Blood ◽  
Pulmonary Capillary Blood Volume ◽  
Predicted Values

Champion swimmers have been found to have significantly higher steady-state pulmonary diffusing capacities than those measured in normal subjects of comparable age at the same exercise level. Nonactive and moderately active normal subjects, swimmers of average ability, long distance runners, and older ex-athletes were found to show no significant deviation from predicted values of DlCO, either in absolute terms or in relation to body surface area or lung midcapacity. The high DlCO in champion swimmers results from a larger than normal pulmonary capillary blood volume (Vc). It has been observed that normal subjects can increase the measured steady-state Dl during exercise by a “held inspiration“ maneuver, but this increase is caused by an increased membrane diffusion component (Dm) per liter midcapacity and not by an increased Vc. Champion swimmers have a particular need of a high Dl since they must be able to transfer large volumes of oxygen across the lung when the alveolar pO2 has fallen to low levels. Submitted on August 20, 1962

scholarly journals Paxillin regulates cell polarization and anterograde vesicle trafficking during cell migration

2017 ◽  
Vol 28 (26) ◽  
pp. 3815-3831 ◽  
Author(s):  
Fatemeh Dubois ◽  
Kyle Alpha ◽  
Christopher E. Turner
Keyword(s):  
Plasma Membrane ◽  
Focal Adhesion ◽  
Leading Edge ◽  
Cell Polarization ◽  
Vesicular Trafficking ◽  
Two Dimensional ◽  
One Dimensional ◽  
Directed Migration ◽  
Key Aspects ◽  
Golgi Organization

Cell polarization and directed migration play pivotal roles in diverse physiological and pathological processes. Herein, we identify new roles for paxillin-mediated HDAC6 inhibition in regulating key aspects of cell polarization in both two-dimensional and one-dimensional matrix environments. Paxillin, by modulating microtubule acetylation through HDAC6 regulation, was shown to control centrosome and Golgi reorientation toward the leading edge, a hallmark of cell polarization to ensure directed trafficking of promigratory factors. Paxillin was also required for pericentrosomal Golgi localization and centrosome cohesion, independent of its localization to, and role in, focal adhesion signaling. In addition, we provide evidence of an accumulation of paxillin at the centrosome that is dependent on focal adhesion kinase (FAK) and identify an important collaboration between paxillin and FAK signaling in the modulation of microtubule acetylation, as well as centrosome and Golgi organization and polarization. Finally, paxillin was also shown to be required for optimal anterograde vesicular trafficking to the plasma membrane.

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 544-545
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
Steady State ◽  
Room Temperature ◽  
Small Mass ◽  
Equilibrium Pressure ◽  
Biological Objects ◽  
Mechanical Pump ◽  
Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

The photoreceptor cytoskeleton visualized

1992 ◽  
Vol 50 (1) ◽  
pp. 480-481
Author(s):  
Beth Burnside
Keyword(s):  
Outer Segment ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Cell Polarization ◽  
Synaptic Proteins ◽  
Cell Functions ◽  
Vertebrate Photoreceptor ◽  
Numerous Cell ◽  
Turn Over

The vertebrate photoreceptor provides a drammatic example of cell polarization. Specialized to carry out phototransduction at its distal end and to synapse with retinal interneurons at its proximal end, this long slender cell has a uniquely polarized morphology which is reflected in a similarly polarized cytoskeleton. Membranes bearing photopigment are localized in the outer segment, a modified sensory cilium. Sodium pumps which maintain the dark current critical to photosensory transduction are anchored along the inner segment plasma membrane between the outer segment and the nucleus.Proximal to the nucleus is a slender axon terminating in specialized invaginating synapses with other neurons of the retina. Though photoreceptor diameter is only 3-8u, its length from the tip of the outer segment to the synapse may be as great as 200μ. This peculiar linear cell morphology poses special logistical problems and has evoked interesting solutions for numerous cell functions. For example, the outer segment membranes turn over by means of a unique mechanism in which new disks are continuously added at the proximal base of the outer segment, while effete disks are discarded at the tip and phagocytosed by the retinal pigment epithelium. Outer segment proteins are synthesized in the Golgi near the nucleus and must be transported north through the inner segment to their sites of assembly into the outer segment, while synaptic proteins must be transported south through the axon to the synapse.The role of the cytoskeleton in photoreceptor motile processes is being intensely investigated in several laboratories.

Continuous hydrogenolysis of acetal-stabilized lignin in flow

2021 ◽  
Author(s):  
Wu Lan ◽  
Yuan Peng Du ◽  
Songlan Sun ◽  
Jean Behaghel de Bueren ◽  
Florent Héroguel ◽  
...  
Keyword(s):  
Steady State ◽  
Challenges And Opportunities

We performed a steady state high-yielding depolymerization of soluble acetal-stabilized lignin in flow, which offered a window into challenges and opportunities that will be faced when continuously processing this feedstock.

Network reconstruction based on steady-state data

2008 ◽  
Vol 45 ◽  
pp. 161-176 ◽  
Author(s):  
Eduardo D. Sontag
Keyword(s):  
Steady State ◽  
Reverse Engineering ◽  
Theoretical Method ◽  
Network Reconstruction ◽  
Quasi Steady State ◽  
State Data

This paper discusses a theoretical method for the “reverse engineering” of networks based solely on steady-state (and quasi-steady-state) data.

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