The Functional Competence of Animal Cells: Anal Ysis of the Secretory Pathway

2005 ◽  
pp. 71-74
Author(s):  
Daniel E. Alete ◽  
Andrew J. Racher ◽  
John R. Birch ◽  
David C. James ◽  
C. Mark Smales
Keyword(s):  
Secretory Pathway ◽  
Animal Cells ◽  
Functional Competence ◽  
Anal Ysis

Protein folding in the secretory pathway of animal cells

1995 ◽  
pp. 371-376
Author(s):  
Robert B. Freedman ◽  
Carole Greenall ◽  
Nigel Jenkins ◽  
Mick F. Tuite
Keyword(s):  
Protein Folding ◽  
Secretory Pathway ◽  
Animal Cells

Protein folding in the secretory pathway of animal cells

1995 ◽  
Vol 18 (1-2) ◽  
pp. 77-82 ◽  
Author(s):  
Robert B. Freedman ◽  
Carole Greenall ◽  
Nigel Jenkins ◽  
Mick F. Tuite
Keyword(s):  
Protein Folding ◽  
Secretory Pathway ◽  
Animal Cells

scholarly journals A Homolog of Voltage-Gated Ca2+Channels Stimulated by Depletion of Secretory Ca2+ in Yeast

2000 ◽  
Vol 20 (18) ◽  
pp. 6686-6694 ◽  
Author(s):  
Emily G. Locke ◽  
Myriam Bonilla ◽  
Linda Liang ◽  
Yoko Takita ◽  
Kyle W. Cunningham
Keyword(s):  
Mammalian Cells ◽  
Secretory Pathway ◽  
Uptake System ◽  
Wild Type ◽  
Animal Cells ◽  
Voltage Gated ◽  
High Affinity ◽  
Essential Components ◽  
Yeast Mutants ◽  
Stimulation Of

ABSTRACT In animal cells, capacitative calcium entry (CCE) mechanisms become activated specifically in response to depletion of calcium ions (Ca2+) from secretory organelles. CCE serves to replenish those organelles and to enhance signaling pathways that respond to elevated free Ca2+ concentrations in the cytoplasm. The mechanism of CCE regulation is not understood because few of its essential components have been identified. We show here for the first time that the budding yeast Saccharomyces cerevisiaeemploys a CCE-like mechanism to refill Ca2+ stores within the secretory pathway. Mutants lacking Pmr1p, a conserved Ca2+ pump in the secretory pathway, exhibit higher rates of Ca2+ influx relative to wild-type cells due to the stimulation of a high-affinity Ca2+ uptake system. Stimulation of this Ca2+ uptake system was blocked inpmr1 mutants by expression of mammalian SERCA pumps. The high-affinity Ca2+ uptake system was also stimulated in wild-type cells overexpressing vacuolar Ca2+ transporters that competed with Pmr1p for substrate. A screen for yeast mutants specifically defective in the high-affinity Ca2+ uptake system revealed two genes, CCH1 and MID1, previously implicated in Ca2+ influx in response to mating pheromones. Cch1p and Mid1p were localized to the plasma membrane, coimmunoprecipitated from solubilized membranes, and shown to function together within a single pathway that ensures that adequate levels of Ca2+ are supplied to Pmr1p to sustain secretion and growth. Expression of Cch1p and Mid1p was not affected in pmr1mutants. The evidence supports the hypothesis that yeast maintains a homeostatic mechanism related to CCE in mammalian cells. The homology between Cch1p and the catalytic subunit of voltage-gated Ca2+ channels raises the possibility that in some circumstances CCE in animal cells may involve homologs of Cch1p and a conserved regulatory mechanism.

Surface Structure of Nucleated Animal Cells: Carbon Replicas

1967 ◽  
Vol 25 ◽  
pp. 120-121
Author(s):  
Robert M. Glaeser ◽  
Thea B. Scott
Keyword(s):  
Cell Surface ◽  
Surface Structure ◽  
Particle Diameter ◽  
Cellular Functions ◽  
Animal Cells ◽  
Replica Technique ◽  
Carbon Replica ◽  
Characteristic Particle ◽  
Cell Surface Structure ◽  
Carbon Replicas

The carbon-replica technique can be used to obtain information about cell-surface structure that cannot ordinarily be obtained by thin-section techniques. Mammalian erythrocytes have been studied by the replica technique and they appear to be characterized by a pebbly or “plaqued“ surface texture. The characteristic “particle” diameter is about 200 Å to 400 Å. We have now extended our observations on cell-surface structure to chicken and frog erythrocytes, which possess a broad range of cellular functions, and to normal rat lymphocytes and mouse ascites tumor cells, which are capable of cell division. In these experiments fresh cells were washed in Eagle's Minimum Essential Medium Salt Solution (for suspension cultures) and one volume of a 10% cell suspension was added to one volume of 2% OsO4 or 5% gluteraldehyde in 0.067 M phosphate buffer, pH 7.3. Carbon replicas were obtained by a technique similar to that employed by Glaeser et al. Figure 1 shows an electron micrograph of a carbon replica made from a chicken erythrocyte, and Figure 2 shows an enlarged portion of the same cell.

Nuclear Envelope Dynamics During Mitosis

1988 ◽  
Vol 46 ◽  
pp. 224-225
Author(s):  
Brian Burke
Keyword(s):  
Nuclear Envelope ◽  
Membrane Vesicles ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Animal Cells ◽  
Interphase Chromosome ◽  
Lamin B ◽  
Chromosome Architecture ◽  
Complex Membrane ◽  
Pore Complexes

The nuclear envelope is a complex membrane structure that forms the boundary of the nuclear compartment in eukaryotes. It regulates the passage of macromolecules between the two compartments and may be important for organizing interphase chromosome architecture. In interphase animal cells it forms a remarkably stable structure consisting of a double membrane ouerlying a protein meshwork or lamina and penetrated by nuclear pore complexes. The latter form the channels for nucleocytoplasmic exchange of macromolecules, At the onset of mitosis, however, it rapidly disassembles, the membranes fragment to yield small vesicles and the lamina, which is composed of predominantly three polypeptides, lamins R, B and C (MW approx. 74, 68 and 65 kDa respectiuely), breaks down. Lamins B and C are dispersed as monomers throughout the mitotic cytoplasm, while lamin B remains associated with the nuclear membrane vesicles.

Localization of Adenosine Triphosphatase Activity in the Phleom of Nicotiana Tabacum

1972 ◽  
Vol 30 ◽  
pp. 230-231
Author(s):  
James Cronshaw ◽  
Jamison E. Gilder
Keyword(s):  
Plasma Membrane ◽  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Higher Plants ◽  
High Surface ◽  
Root Tip ◽  
Animal Cells ◽  
Physiological Processes ◽  
Tip Cells ◽  
Atpase Localization

Adenosine triphosphatase (ATPase) activity has been shown to be associated with numerous physiological processes in both plants and animal cells. Biochemical studies have shown that in higher plants ATPase activity is high in cell wall preparations and is associated with the plasma membrane, nuclei, mitochondria, chloroplasts and lysosomes. However, there have been only a few ATPase localization studies of higher plants at the electron microscope level. Poux (1967) demonstrated ATPase activity associated with most cellular organelles in the protoderm cells of Cucumis roots. Hall (1971) has demonstrated ATPase activity in root tip cells of Zea mays. There was high surface activity largely associated with the plasma membrane and plasmodesmata. ATPase activity was also demonstrated in mitochondria, dictyosomes, endoplasmic reticulum and plastids.

Structural aspects of tracheary element differentiation in suspension cultures of Zinnia elegans

1989 ◽  
Vol 47 ◽  
pp. 768-769
Author(s):  
C. H. Haigler ◽  
A. W. Roberts
Keyword(s):  
Tracheary Element ◽  
Vesicle Fusion ◽  
Zinnia Elegans ◽  
Cellulose Synthesis ◽  
Tracheary Elements ◽  
Animal Cells ◽  
Mesophyll Cells ◽  
Fixation Techniques ◽  
Localized Patterns ◽  
Structural Aspects

Tracheary elements, the water-conducting cells in plants, are characterized by their reinforced walls that became thickened in localized patterns during differentiation (Fig. 1). The synthesis of this localized wall involves abundant secretion of Golgi vesicles that export preformed matrix polysaccharides and putative proteins involved in cellulose synthesis. Since the cells are not growing, some kind of endocytotic process must also occur. Many researchers have commented on where exocytosis occurs in relation to the thickenings (for example, see), but they based their interpretations on chemical fixation techniques that are not likely to provide reliable information about rapid processes such as vesicle fusion. We have used rapid freezing to more accurately assess patterns of vesicle fusion in tracheary elements. We have also determined the localization of calcium, which is known to regulate vesicle fusion in plant and animal cells.Mesophyll cells were obtained from immature first leaves of Zinnia elegans var. Envy (Park Seed Co., Greenwood, S.C.) and cultured as described previously with the following exceptions: (a) concentration of benzylaminopurine in the culture medium was reduced to 0.2 mg/l and myoinositol was eliminated; and (b) 1.75ml cultures were incubated in 22 x 90mm shell vials with 112rpm rotary shaking. Cells that were actively involved in differentiation were harvested and frozen in solidifying Freon as described previously. Fractures occurred preferentially at the cell/planchet interface, which allowed us to find some excellently-preserved cells in the replicas. Other differentiating cells were incubated for 20-30 min in 10(μM CTC (Sigma), an antibiotic that fluoresces in the presence of membrane-sequestered calcium. They were observed in an Olympus BH-2 microscope equipped for epi-fluorescence (violet filter package and additional Zeiss KP560 barrier filter to block chlorophyll autofluorescence).

Three-Dimensional reconstruction of isolated centrosomes by automated electron tomography

1994 ◽  
Vol 52 ◽  
pp. 310-311
Author(s):  
M.B. Braunfeld ◽  
M. Moritz ◽  
B.M. Alberts ◽  
J.W. Sedat ◽  
D.A. Agard
Keyword(s):  
Electron Tomography ◽  
Three Dimensional ◽  
Vital Role ◽  
Complex Nature ◽  
Animal Cells ◽  
Microtubule Organizing Center ◽  
Nucleation Sites ◽  
Dimensional Reconstruction ◽  
Organizing Center ◽  
Resolution Model

In animal cells, the centrosome functions as the primary microtubule organizing center (MTOC). As such the centrosome plays a vital role in determining a cell's shape, migration, and perhaps most importantly, its division. Despite the obvious importance of this organelle little is known about centrosomal regulation, duplication, or how it nucleates microtubules. Furthermore, no high resolution model for centrosomal structure exists.We have used automated electron tomography, and reconstruction techniques in an attempt to better understand the complex nature of the centrosome. Additionally we hope to identify nucleation sites for microtubule growth.Centrosomes were isolated from early Drosophila embryos. Briefly, after large organelles and debris from homogenized embryos were pelleted, the resulting supernatant was separated on a sucrose velocity gradient. Fractions were collected and assayed for centrosome-mediated microtubule -nucleating activity by incubating with fluorescently-labeled tubulin subunits. The resulting microtubule asters were then spun onto coverslips and viewed by fluorescence microscopy.

Animal Cells as Bioreactors

1994 ◽  
Author(s):  
Terence Cartwright
Keyword(s):  
Animal Cells

SiO2 Entrapment of Animal Cells for Hybrid Bioartificial Organs

2000 ◽  
Vol 628 ◽  
Author(s):  
Giovanni Carturan ◽  
Renzo Dal Monte ◽  
Maurizio Muraca
Keyword(s):  
Gas Phase ◽  
Mechanical Stability ◽  
Porous Silica ◽  
Collagen Matrix ◽  
Homogeneous Layer ◽  
Animal Cells ◽  
Bioartificial Organs ◽  
Liver And Pancreas ◽  
Encapsulation Method ◽  
Metabolic Activities

ABSTRACTSi-alkoxides in gas phase are reactive towards the surface of animal cells, depositing a homogeneous layer of porous silica. This encapsulation method preserves cell viability and does not alter the hindrance of the biological load.In the prospective use for the design of a hybrid bioartificial liver, hepatocytes in a collagen matrix can be entrapped by the siliceous deposit which provides definite mechanical stability to the collagen matrix and molecular cutoff vs. high molecular weight proteins, including immunoglobulins. The functionality of the encapsulated cell load is maintained for the expressions of typical liver and pancreas metabolic activities.

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