scholarly journals Membrane flow during nematode spermiogenesis.

1982 ◽  
Vol 92 (1) ◽  
pp. 113-120 ◽  
Author(s):  
T M Roberts ◽  
S Ward
Keyword(s):  
Caenorhabditis Elegans ◽  
Diffusion Coefficients ◽  
Surface Membrane ◽  
Lateral Diffusion ◽  
Bulk Flow ◽  
Membrane Glycoproteins ◽  
Membrane Flow ◽  
Latex Beads ◽  
Membrane Components

Two distinct types of surface membrane rearrangement occur during the differentiation of Caenorhabditis elegans spermatids into amoeboid spermatozoa. The first, detected by the behavior of latex beads attached to the surface, is a nondirected, intermittent movement of discrete portions of the membrane. This movement starts when spermatids are stimulated to differentiate and stops when a pseudopod is formed. The second type of movement is a directed, continual flow of membrane components from the tip of the pseudopod to its base. Both membrane glycoproteins and fluorescent phospholipids inserted in the membrane flow backward at the same rate, approximately 4 micrometers/min, although their lateral diffusion coefficients in the membrane differ by at least a factor of 5. These observations suggest that pseudopodial membrane movement is due to bulk flow of membrane components away from the tip of the pseudopod.

scholarly journals Comparative behavior of membrane protein-antibody complexes on motile fibroblasts: implications for a mechanism of capping.

1990 ◽  
Vol 111 (6) ◽  
pp. 2499-2512 ◽  
Author(s):  
B F Holifield ◽  
A Ishihara ◽  
K Jacobson
Keyword(s):  
Membrane Proteins ◽  
Diffusion Coefficients ◽  
Lateral Diffusion ◽  
Locomotory Activity ◽  
Similar Time ◽  
Membrane Flow ◽  
Current Form ◽  
Materials Used ◽  
Membrane Components ◽  
Time Frames

A characteristic feature of fibroblast locomotory activity is the rearward transport across the leading lamella of various materials used to mark the cell surface. The two processes most frequently invoked as explanations for this transport phenomenon, called capping, are (a) retrograde membrane flow arising from directed membrane insertion and (b) rearward cortical cytoskeletal flow arising from cytoskeletal assembly and contraction. The retrograde lipid flow hypothesis, the most current form of the membrane flow scheme, makes explicit predictions about the movement of membrane proteins subjected to the postulated rearward lipid flow. Several of these predictions were tested by comparing the behavior of four membrane proteins, Pgp-1, Thy-1, H-2, and influenza HA0, identified by fluorescent antibodies. With the exception of Pgp-1, these proteins were uniformly distributed under nonaggregated conditions but were capped when aggregated into patches. In contrast, Pgp-1 was capped in similar time frames in both nonaggregated and aggregated states where the lateral diffusion coefficients were very different. Furthermore, the capping behavior of two tagged membrane proteins was markedly different yet both had similar diffusion coefficients. The results from these tests disprove the bulk membrane flow hypothesis and are at odds with explicit predictions of the retrograde lipid flow hypothesis for the mechanism of capping. This work, therefore, supports the alternative cytoskeletal-based mechanism for driving capping. Requirements for coupling cytoskeletal movement to membrane components are discussed.

scholarly journals Centripetal flow of pseudopodial surface components could propel the amoeboid movement of Caenorhabditis elegans spermatozoa.

1982 ◽  
Vol 92 (1) ◽  
pp. 132-138 ◽  
Author(s):  
T M Roberts ◽  
S Ward
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Body ◽  
Wheat Germ ◽  
Amoeboid Movement ◽  
Directed Movement ◽  
Membrane Flow ◽  
Lectin Receptors ◽  
Latex Beads ◽  
Bulk Membrane ◽  
Membrane Components

Latex beads and wheat germ agglutinin (WGA) were used to examine the movement of membrane components on amoeboid spermatozoa of Caenorhabditis elegans. The behavior of beads attached to the cell revealed continuous, directed movement from the tip of the pseudopod to its base, but no movement on the cell body. Lectin receptors are also cleared from the pseudopod (4). Blocking preexisting lectin receptors with unlabeled WGA followed by pulse-labeling wih fluorescent WGA showed that new lectin receptors are continuously inserted at the tip of the pseudopod. Like latex beads, these new lectin receptors move continuously over the pseudopod surface to the cell body-pseudopod junction where they are probably internalized. Mutants altering the rate of membrane flow, and eliminating its topographical asymmetry, have been identified. Together with the observation that fluorescent phospholipids are cleared from the pseudopod of developing spermatozoa at the same rate as lectin receptors (25), these results show that there is bulk membrane flow over the pseudopod with assembly at the tip and apparent disassembly at the base. There are no vesicles visible at either the pseudopodial tip or base, so these spermatozoa must have a novel mechanism for insertion and uptake of membrane components. This membrane flow could provide the forward propulsion of spermatozoa attached to a substrate by their pseudopods.

The organization of cell surface membrane domains

1989 ◽  
Vol 47 ◽  
pp. 804-805
Author(s):  
Michael Edidin
Keyword(s):  
Cell Surface ◽  
Membrane Lipids ◽  
Surface Membrane ◽  
Lateral Diffusion ◽  
Cell Types ◽  
Membrane Domains ◽  
Membrane Biology ◽  
Morphological Polarity ◽  
Discrete Domains ◽  
Membrane Components

Cell surface membranes are based on a fluid lipid bilayer and models of the membranes' organization have emphasised the possibilities for lateral motion of membrane lipids and proteins within the bilayer. Two recent trends in cell and membrane biology make us consider ways in which membrane organization works against its inherent fluidity, localizing both lipids and proteins into discrete domains. There is evidence for such domains, even in cells without obvious morphological polarity and organization [Table 1]. Cells that are morphologically polarised, for example epithelial cells, raise the issue of membrane domains in an accute form.The technique of fluorescence photobleaching and recovery, FPR, was developed to measure lateral diffusion of membrane components. It has also proven to be a powerful tool for the analysis of constraints to lateral mobility. FPR resolves several sorts of membrane domains, all on the micrometer scale, in several different cell types.

scholarly journals Membrane flow during pinocytosis. A stereologic analysis.

1976 ◽  
Vol 68 (3) ◽  
pp. 665-687 ◽  
Author(s):  
R M Steinman ◽  
S E Brodie ◽  
Z A Cohn
Keyword(s):  
Cell Surface ◽  
Surface Area ◽  
Surface Membrane ◽  
Membrane Flow ◽  
Rapid Reduction ◽  
Secondary Lysosome ◽  
L Cells ◽  
Secondary Lysosomes ◽  
Membrane Components ◽  
Pinocytic Vesicles

HRP has been used as a cytochemical marker for a sterelogic analysis of pinocytic vesicles and secondary lysosomes in cultivated macrophages and L cells. Evidence is presented that the diaminobenzidine technique (a) detects all vaculoes containing encyme and (b) distinguishes between incoming pinocytic vesicles and those which have fused with pre-existing lysosomes to form secondary lososomes. The HRP reactive pinocytic vesicle spaces fills completely within 5 min after exposure to enzyme, while the secondary lysosome compartment is saturated in 45--60 min. The size distribution of sectioned (profile) vaculoe diameters was measured at equilibrium and converted to actual (spherical) dimensions using a technique modified from Dr. S. D. Wicksell. The most important findings in this study have to do with the rate at which pinocytosed fluid and surface membrane move into the cell and on their subsequent fate. Each minute macrophages form at least 125 pinocytic vesicles having a fractional vol of 0.43% of the cell's volume and a fractional area of 3.1% of the cell's surface area. The fractional volume and surface area flux rates for L cells were 0.05% and 0.8% per minute respectively. Macrophages and L cells thus interiorize the equivalent of their cell surface area every 33 and 125 min. During a 3-period, the size of the secondary lysosome compartment remains constant and represents 2.5% of the cell volume and 18% of the surface area. Each hour, therefore, the volume and surface area of incoming vesicles is 10 times greater than the dimensions of the secondary lysosomes in both macrophages and L cells. This implies a rapid reduction in vesicle size during the formation of the secondary lysosome and the egress of pinocytosed fluid from the vacuole and the cell. In addition, we postulate that membrane components of the vacuole are subsequently recycled back to the cell surface.

Labeling Techniques for the Analysis of Cell Surface Glycoproteins

1980 ◽  
Vol 38 ◽  
pp. 716-719
Author(s):  
R.S. Molday
Keyword(s):  
Cell Surface ◽  
Surface Membrane ◽  
Molecular Complexes ◽  
Biochemical Properties ◽  
Membrane Glycoproteins ◽  
Animal Cells ◽  
Membrane Components ◽  
Specific Membrane ◽  
Specific Label

Surface membranes of animal cells display a wide variety of glycoproteins, many of which serve as enzymes, transport components or receptors for extra-cellular molecules and molecular complexes. In recent years specific label-ing techniques have been developed to detect, quantitate and study the ultra-structural organization and biochemical properties of cell surface membrane glycoproteins. Studies utilizing these techniques have contributed to our general understanding of membrane structure and have provided some insight into the role of specific membrane components in cellular communication and regulation.

scholarly journals Lateral diffusion of wild-type and mutant Ld antigens in L cells.

1984 ◽  
Vol 99 (6) ◽  
pp. 2333-2335 ◽  
Author(s):  
M Edidin ◽  
M Zuniga
Keyword(s):  
Plasma Membrane ◽  
Diffusion Coefficients ◽  
Transmembrane Protein ◽  
Transmembrane Proteins ◽  
Lateral Diffusion ◽  
Cytoplasmic Domain ◽  
Histocompatibility Antigen ◽  
Wild Type ◽  
Major Histocompatibility Antigen ◽  
Cytoplasmic Side

We have compared the lateral diffusion of intact transmembrane proteins, wild-type H-2Ld antigens, with that of mutants truncated in the cytoplasmic domain. Diffusion coefficients and mobile fractions were similar for all molecules examined, from wild-type Ld antigens with 31 residues on the cytoplasmic side of the plasma membrane to mutants with only four residues in the cytoplasmic domain. This result limits ways in which the lateral diffusion of a major histocompatibility antigen, a transmembrane protein, can be constrained by interactions with other molecules.

Modification of fibroblast surface amines alters receptor-mediated cell spreading on protein-coated substrata but not adsorptive endocytosis

1981 ◽  
Vol 49 (1) ◽  
pp. 283-297
Author(s):  
J.D. Aplin ◽  
R.C. Hughes
Keyword(s):  
Cell Attachment ◽  
Surface Membrane ◽  
Fluorescein Isothiocyanate ◽  
Adhesive Interaction ◽  
Cultured Fibroblasts ◽  
Amine Groups ◽  
Coated Surfaces ◽  
Amine Compounds ◽  
Membrane Components ◽  
Dose Dependent

Fluorescein isothiocyanate (FITC) and other anionic reagents specific for amine groups have previously been shown to inhibit the adhesion and spreading of cultured fibroblasts to fibronectin-coated surfaces (Butters, Devalia, Aplin & Hughes, 1980). Here it is demonstrated that a population of FITC-labelled cells can be separated using flow cytometry into fractions displaying greater and lesser adhesivity at lower and higher fluorescence, respectively, demonstrating that the inhibition is dose-dependent. Glass coverslips covalently derivatized with the lectins ricin and concanavalin A are used to show that the inhibition also occurs in lectinmediated cell adhesion as well as in adhesion to collagen coated with fibronectin and plastic coated with serum or antibody, suggesting that all of these responses share a common, FITC-sensitive component. Simple primary amine compounds inhibit adhesion to fibronectin, but specific inhibitors of transglutaminases do not affect the process. Transglutaminase activity of cell surfaces has been implicated in protein endocytosis and receptor recycling (Davies et al. 1980). FITC modification of cells appears to affect specifically adhesive interaction, since ricin cytotoxicity and infection of cells with influenza and Sendai viruses (phenomena thought to proceed by means of receptor-mediated endocytosis) are unaffected. Evidently, receptor-mediated cell attachment, spreading on protein-coated surfaces and protein endocytosis are functionally separate events requiring different cell-surface membrane components, even when the same protein (ricin) is used to trigger these 2 processes.

Determination of lateral diffusion coefficients in air-water monolayers by fluorescence quenching measurements

1991 ◽  
Vol 113 (13) ◽  
pp. 4838-4843 ◽  
Author(s):  
F. Caruso ◽  
F. Grieser ◽  
A. Murphy ◽  
P. Thistlethwaite ◽  
R. Urquhart ◽  
...  
Keyword(s):  
Fluorescence Quenching ◽  
Diffusion Coefficients ◽  
Lateral Diffusion
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