scholarly journals The response of the Golgi complex to microtubule alterations: the roles of metabolic energy and membrane traffic in Golgi complex organization.

1989 ◽  
Vol 109 (5) ◽  
pp. 2081-2088 ◽  
Author(s):  
J R Turner ◽  
A M Tartakoff
Keyword(s):  
Golgi Complex ◽  
Membrane Traffic ◽  
Metabolic Energy ◽  
Microtubule Assembly ◽  
Metabolic Inhibitors ◽  
Microtubule Depolymerization ◽  
Immunofluorescent Localization ◽  
Complex Organization ◽  
The Individual ◽  
Energy Dependent

A striking example of the interrelation between the Golgi complex (GC) and microtubules is the reversible fragmentation and dispersal of the GC which occurs upon microtubule depolymerization. We have characterized dispersal of the GC after nocodazole treatment as well as its recovery from the dispersed state by immunofluorescent localization of beta 1, 4-galactosyltransferase in Madin-Darby bovine kidney cells. Immunofluorescent anti-tubulin staining allowed simultaneous examination of the microtubule array. Based on our results, dispersal can be divided into a three-step process: microtubule depolymerization, GC fragmentation, and fragment dispersal. In cells treated with metabolic inhibitors after microtubule depolymerization, neither fragmentation nor dispersal occur, despite the absence of assembled microtubules. Thus, fragmentation is energy dependent and not tightly linked to microtubule depolymerization. The slowing of fragmentation and dispersal by monensin or ammonium chloride, as well as progressive inhibition at less than 34 degrees C, suggest that ongoing membrane traffic is required for these processes. Similarly, recovery may be separated into four steps: microtubule depolymerization, GC fragment centralization, fragment coalescence, and polarization of the reticular GC network. Fragment centralization and coalescence were arrested by metabolic inhibitors, despite the presence of microtubules. Neither monensin nor ammonium choride inhibited GC recovery. Partial inhibition of recovery at reduced temperatures paralleled the extent of microtubule assembly. These data demonstrate that dispersal and recovery are multi-step operations, and that the individual steps differ in temperature dependence, energy dependence, and sensitivity to ionic perturbation. GC distribution and microtubule status have also been clearly dissociate, thereby proving that organization of the GC is an active process that is not simply determined by microtubule binding. Furthermore, the results indicate that ongoing intra-GC membrane traffic may participate in fragmentation and dispersal.

Metabolic energy dependent exocytosis of mouse mast cells by lectin of Dioclea grandiflora (Mart.)

1985 ◽  
Vol 34 (23) ◽  
pp. 4169-4170 ◽  
Author(s):  
Maria Silva Lima ◽  
Manuel Cid Oliveira ◽  
Renato Azevedo Moreira ◽  
Annie Prouvost-Danon
Keyword(s):  
Mast Cells ◽  
Metabolic Energy ◽  
Dioclea Grandiflora ◽  
Energy Dependent

Regulation of cell shape in Euglena gracilis. III. Involvement of stable microtubules

1985 ◽  
Vol 74 (1) ◽  
pp. 219-237
Author(s):  
C.L. Lachney ◽  
T.A. Lonergan
Keyword(s):  
Euglena Gracilis ◽  
Cell Shape ◽  
Microtubule Assembly ◽  
Live Cells ◽  
Microtubule Depolymerization ◽  
Cytoplasmic Microtubule ◽  
Intact Cells ◽  
Calmodulin Antagonist ◽  
Cell Shapes ◽  
In Cells

The role of cytoplasmic microtubules in a recently reported biological clock-controlled rhythm in cell shape of the alga Euglena gracilis (strain Z) was examined using indirect immunofluorescence microscopy. The resulting fluorescent patterns indicated that, unlike many other cell systems, Euglena cells apparently change from round to long to round cell shape without associated cytoplasmic microtubule assembly and disassembly. Instead, the different cell shapes were correlated with microtubule patterns, which suggested that movement of stable microtubules to accomplish cell shape changes. In live intact cells, these microtubules were demonstrated by immunofluorescence to be stable to lowered temperature and elevated intracellular Ca2+ levels, treatments that are commonly used to depolymerize microtubules. In cells extracted in detergent at low temperature or in the presence of elevated Ca2+ levels, the fluorescent image of the microtubules was disrupted. Transmission electron microscopy confirmed the loss of one subset of pellicle microtubules. The difference in microtubule stability to these agents between live intact cells and cells extracted in detergent suggested the presence of a microtubule-stabilizing factor in live cells, which is released from the cell by extraction with detergent, thereby permitting microtubule depolymerization by Ca2+ or lowered temperature. The calmodulin antagonist trifluoperazine prevented the Ca2+-induced disruption of the fluorescent microtubule pattern in cells extracted in detergent. These results implied the involvement of calmodulin in the sensitivity to Ca2+ of the microtubules of cells extracted in detergent.

Energy dependence of RNA degradation in rabbit reticulocytes

1984 ◽  
Vol 247 (5) ◽  
pp. C390-C395 ◽  
Author(s):  
E. A. Park ◽  
H. E. Morgan
Keyword(s):  
Protein Synthesis ◽  
Ribosomal Rna ◽  
Rna Degradation ◽  
Atp Depletion ◽  
Metabolic Inhibitors ◽  
Atp Content ◽  
Bicarbonate Buffer ◽  
Ribosomal Subunits ◽  
Energy Dependent ◽  
Rabbit Reticulocytes

RNA degradation in rabbit reticulocytes was partially energy dependent. Reticulocytes were incubated for 10 h in Krebs-Henseleit bicarbonate buffer that was gassed with 95% O2-5% CO2 and contained glucose (30 mM) or 2-deoxyglucose (20 mM) and 2,4-dinitrophenol (0.2 mM). The rate of RNA degradation was reduced 41% in the presence of the metabolic inhibitors. When the buffer was gassed with 95% N2-5% CO2 and no substrate was added, the disappearance of RNA was decreased 55%. The cellular ATP content was depleted either by addition of the metabolic inhibitors or by incubation under anoxic conditions. ATP depletion did not modify the ratio of ribosomal subunits + monomers to polysomes. Puromycin and cycloheximide, which increased or decreased, respectively, the proportion of ribosomal RNA in subunits + monomers, blocked protein synthesis but did not alter the rate of RNA degradation. These experiments indicated that energy depletion inhibited RNA degradation by a mechanism that did not depend on the inhibition of protein synthesis. No evidence was obtained to indicate that the ratio of subunits + monomers to polysomes affected RNA degradation.

Energy-dependent cell volume maintenance in UC-11MG human astrocytomas

1989 ◽  
Vol 257 (4) ◽  
pp. C817-C824 ◽  
Author(s):  
R. Lomneth ◽  
E. I. Gruenstein
Keyword(s):  
Cell Volume ◽  
Glucose Deprivation ◽  
Atp Depletion ◽  
Metabolic Inhibitors ◽  
Rapid Phase ◽  
Atp Levels ◽  
Time Period ◽  
Astrocytoma Cell ◽  
Dependent Cell ◽  
Energy Dependent

Swelling of astrocytes in the brain is a major cause of the morbidity and mortality associated with stroke and head trauma. Using a human astrocytoma cell line (UC-11MG) as a model system, we studied cell volume changes caused by ATP depletion under conditions mimicking hypoxia. ATP levels were reduced to less than 10% of control using the metabolic inhibitors KCN or antimycin in combination with glucose deprivation. This was sufficient to eliminate ouabain-sensitive 86Rb+ uptake, indicating the Na+-K+-adenosinetriphosphatase was not operating. Furosemide-sensitive 86Rb+ uptake was reduced by approximately 60%, indicating Na+-K+-2Cl- cotransport was also sensitive to ATP loss. ATP depletion resulted in a 30-40% reduction of cell volume within 60 min. ATP depletion also resulted in a net loss of intracellular K+. This loss of K+ could be blocked by Ba2+, indicating the K+ loss was through a conductive channel. When the net K+ loss was blocked by Ba2+, the volume decrease was also prevented. The cells remained viable throughout the time period as judged by exclusion of ethidium bromide by 99% of the cells and recovery of ATP levels to 75% of control within 60 min. We conclude that ATP depletion, following inhibition of glycolysis and oxidative phosphorylation, causes astrocytes to shrink because of a more rapid loss of K+ than uptake of Na+. Thus it appears that ATP depletion alone is not sufficient to account for the rapid phase of astrocytic swelling observed during cerebral ischemia.

Role of Metabolic Inhibitors on the Adhesion of Rabbit Gel Filtered Platelets to Collagen - Sepharose

1979 ◽  
Author(s):  
J.O. Capobianco ◽  
W.H. Holleman
Keyword(s):  
Metabolic Inhibitors ◽  
Antimycin A ◽  
Inhibitory Effects ◽  
Energy Dependent

The adhesion of rabbit gel filtered platelets (GFP) to collagen-Sepharose was found to be largely energy independent, since metabolic inhibitors only partially suppressed this process. 51Cr and 14C-serotonin labeled GFP were incubated at 37°C/10 min. with anti-metabolites prior to passage over collagen-Sepharose columns. Adhesion and release responses were determined by 51Cr content of columns and 14C content of the supernatant from column eluents. Antimycin-A (AA, 2μg/ml), or AA plus 2-deoxy-D-glucose (2DG, 32mM) or Rotenone (R, 2μg/ml) produced small reductions in adhesion. All three compounds inhibited release, their effects being additive. 2DG or glucono-§-lactone (GLAC, 10mM) alone had little or no effect on adhesion. 2DG reduced release response by 40%, while GLAC had no effect. AA or R reduced adhesion by 35% and 31%, and release by 51% and 47%, respectively. The combination of 2DG, GLAC, AA and R did not reduce adhesion more than 45%. The Inhibitory effects of AA were time and dose related, and the addition c glucose (0.1%) circumvented these effects. These experiments suggest that adhesion includes energy dependent and independent phases. In addition, spherical platelets (GFP at 4°c/24 hrs.) also adhered to collagen-Sepharose; however, in contrast to disc-platelets (GFP at 37°c/10 min.), the adhering platelets demonstrated a depressed release response (-79%),

Reconfigure

2016 ◽  
Vol 47 (6) ◽  
pp. 851-865 ◽  
Author(s):  
Nicolay Worren ◽  
Tido Eger ◽  
Thorvald Hærem
Keyword(s):  
Business School ◽  
Organization Design ◽  
System Level ◽  
Future Research ◽  
Design Concepts ◽  
Organizational Behaviour ◽  
Complex Organization ◽  
Coordination Costs ◽  
The Individual ◽  
Better Than

Background. Organization design is a subject that is covered in business school courses such as strategy implementation, organizational theory, and organizational behaviour. However, students sometimes perceive organization design concepts as abstract. Aim. To develop and pilot a simulation that may improve participants’ understanding of two key organization design concepts - work process interdependency and coordination cost. In addition, to develop an approach that may contribute to better operationalization of these concepts in future research. Method. Participants are divided into groups representing departments and are then asked to reconfigure the groups while considering both benefits (reduced coordination costs) and costs (of reconfiguration). The exercise is supported by a MicrosoftExcelTM tool, quantifying the concepts of interdependency and coordination cost. Results. The pilot application of the simulation achieved its pedagogical aims. The participants performed somewhat better than anticipated (some possible causes are discussed). Conclusions. Experiential simulations can be used to convey complex organization design principles to students and managers. They may also be used to study the capacity of individuals and groups to take into account multiple interdependencies in optimizing a design at the individual, group and system level. Recommendation. Simulations should be used to enhance the pedagogical value of organization design lectures (or seminars for employees in organizations).

scholarly journals ARL4A acts with GCC185 to modulate Golgi complex organization

2011 ◽  
Vol 124 (23) ◽  
pp. 4014-4026 ◽  
Author(s):  
Y.-C. Lin ◽  
T.-C. Chiang ◽  
Y.-T. Liu ◽  
Y.-T. Tsai ◽  
L.-T. Jang ◽  
...  
Keyword(s):  
Golgi Complex ◽  
Complex Organization

scholarly journals Nona-Arginine Facilitates Delivery of Quantum Dots into Cells via Multiple Pathways

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Yi Xu ◽  
Betty Revon Liu ◽  
Han-Jung Lee ◽  
Katie B. Shannon ◽  
Jeffrey G. Winiarz ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Cellular Uptake ◽  
Metabolic Inhibitors ◽  
Cellular Internalization ◽  
Caveolin 1 ◽  
Dependent Process ◽  
A Cell ◽  
Low Efficiency ◽  
Rnai Technique ◽  
Energy Dependent

Semiconductor quantum dots (QDs) have recently been used to deliver and monitor biomolecules, such as drugs and proteins. However, QDs alone have a low efficiency of transport across the plasma membrane. In order to increase the efficiency, we used synthetic nona-arginine (SR9), a cell-penetrating peptide, to facilitate uptake. We found that SR9 increased the cellular uptake of QDs in a noncovalent binding manner between QDs and SR9. Further, we investigated mechanisms of QD/SR9 cellular internalization. Low temperature and metabolic inhibitors markedly inhibited the uptake of QD/SR9, indicating that internalization is an energy-dependent process. Results from both the pathway inhibitors and the RNA interference (RNAi) technique suggest that cellular uptake of QD/SR9 is predominantly a lipid raft-dependent process mediated by macropinocytosis. However, involvement of clathrin and caveolin-1 proteins in transducing QD/SR9 across the membrane cannot be completely ruled out.

scholarly journals Spatial Variation of Microtubule Depolymerization in Large Asters

2021 ◽  
pp. mbc.E20-11-0723
Author(s):  
Keisuke Ishihara ◽  
Franziska Decker ◽  
Paulo Caldas ◽  
James F. Pelletier ◽  
Martin Loose ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Microtubule Assembly ◽  
Microtubule Depolymerization ◽  
Physiological Regulation ◽  
Xenopus Egg Extract ◽  
Spatial Regulation ◽  
Important Target ◽  
Egg Extract ◽  
Xenopus Egg ◽  
Difference Imaging

Microtubule plus end depolymerization rate is a potentially important target of physiological regulation, but it has been challenging to measure, so its role in spatial organization is poorly understood. Here we apply a method for tracking plus ends based on time difference imaging to measure depolymerization rates in large interphase asters growing in  Xenopus egg extract. We observed strong spatial regulation of depolymerization rates, which were higher in the aster interior compared to the periphery, and much less regulation of polymerization or catastrophe rates. We interpret these data in terms of a limiting component model, where aster growth results in lower levels of soluble tubulin and MAPs in the interior cytosol compared to that at the periphery. The steady-state polymer fraction of tubulin was ∼30%, so tubulin is not strongly depleted in the aster interior. We propose that the limiting component for microtubule assembly is a MAP that inhibits depolymerization, and that egg asters are tuned to low microtubule density. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text]

Sign in / Sign up

Export Citation Format

Share Document