Intermolecular interactions with/within cell membranes and the trinity of membrane potentials: kinetics and imaging

2003 ◽  
Vol 31 (5) ◽  
pp. 990-996 ◽  
Author(s):  
P. O'Shea
Keyword(s):  
Intermolecular Interactions ◽  
Cell Biology ◽  
Membrane Surface ◽  
Membrane Potentials ◽  
Membrane Microdomains ◽  
Membrane Dipole Potential ◽  
Additional Level ◽  
The Trinity ◽  
Detection Technologies

The interactions of (macro-)molecules with biological membranes underlies much of cell biology. This paper outlines many of the factors that must be taken into account in order to understand fully the nature of these interactions. These include some roles of the membrane potentials including features of the surface and dipole potentials. Several fluorescence detection technologies directed towards these are outlined that offer high-resolution experimental determination of the intermolecular interactions by measuring small changes of these potentials resulting from specific interactions of many kinds of molecular species. The possibilities for making single-cell spatial imaging measurements of such interactions is also described. Examples are used to indicate the feasibility of identifying and tracking localized interactions on the membrane surface in real-time. Some of this work points to the possibility that the membrane dipole potential spatially varies about the cell surface, particularly within membrane microdomains such as ‘rafts’. Such variation is suggested to underlie the altered behaviour of signalling systems within rafts and offer the means of an additional level of biological control.

Physical landscapes in biological membranes: physico–chemical terrains for spatio–temporal control of biomolecular interactions and behaviour

2005 ◽  
Vol 363 (1827) ◽  
pp. 575-588 ◽  
Author(s):  
Paul O'Shea
Keyword(s):  
Biological Membranes ◽  
Point Of View ◽  
Membrane Rafts ◽  
Biomolecular Interactions ◽  
Membrane Dipole Potential ◽  
Physico Chemical ◽  
Spatio Temporal ◽  
Influential Parameters ◽  
Detection Technologies

The evolving complexities of biological membranes are discussed from the point of view of potential roles of the physical constitution of the membrane. These include features of the surface and dipole potentials and membrane ‘rafts’. These properties are outlined; they emphasize that protein–lipid and specific lipid environments are influential parameters in how biomolecular interactions may take place with and within membranes. Several fluorescence detection technologies directed towards measurement of these properties are also outlined that permit high–resolution experimental determination of intermolecular interactions with membranes by measuring small changes of these potentials. These point to the possibility that the membrane dipole potential in particular is enormously influential in determining the behaviour of receptor and signalling systems within membrane rafts, and offers the means of a novel mechanism for biological control.

scholarly journals Determination of transmembrane pH gradients and membrane potentials in liposomes

1992 ◽  
Vol 63 (5) ◽  
pp. 1336-1345 ◽  
Author(s):  
P.R. Harrigan ◽  
M.J. Hope ◽  
T.E. Redelmeier ◽  
P.R. Cullis
Keyword(s):  
Membrane Potentials ◽  
Ph Gradients

scholarly journals Determination of platelet antigens and glycoproteins in the human fetus

Blood ◽  
1986 ◽  
Vol 68 (2) ◽  
pp. 488-492 ◽  
Author(s):  
Y Gruel ◽  
B Boizard ◽  
F Daffos ◽  
F Forestier ◽  
J Caen ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Human Fetus ◽  
Antenatal Diagnosis ◽  
Polyclonal Antibodies ◽  
Umbilical Vein ◽  
Membrane Surface ◽  
Platelet Suspension ◽  
Direct Puncture ◽  
Normal Human

Abstract The autosomal recessive transmission of Glanzmann's thrombasthenia (GT) and Bernard-Soulier syndrome (BSS), together with requests of families who already had children with these diseases, prompted us to investigate the feasibility of their antenatal diagnosis. The preliminary step leading to the early detection of GT or BSS was to characterize, in the normal human fetus, the platelet antigens and glycoproteins (GPs) and to define their normal amounts on the membrane surface. Blood samples from 32 fetuses between 18 to 26 weeks of gestation were collected by direct puncture of the umbilical vein using an ultrasound-guided needle. Polyclonal antibodies from human origin directed against PLA1, Leka antigens, and the GPIIb IIIa complex (IgGL), or murine monoclonal antibodies specific for GPIb (AN51, 6D1), GPIIIa (AP-3), or GPIIb IIIa (AP-2) were studied using platelet suspension immunofluorescence tests. The binding of each antibody was quantified using a cytofluorograph (Ortho 50H). PLA1 and Leka antigens were expressed in normal amounts on fetal platelets as early as 16 weeks of intrauterine life. The GPIIb IIIa complex quantified by polyclonal or monoclonal antibodies was in the same range in fetuses (IgGL = 427 +/- 23 AUF, AP-2 = 459.5 +/- 8.5; AP-3 = 536 +/- 14) and in adults (IgGL = 420 +/- 30; AP-2 = 498 +/- 11; AP-3 = 515 +/- 13). The platelet binding of antibodies that recognized GPIb was higher in fetuses (AN51 = 491.5 +/- 14; 6D1 = 479 +/- 15) than in adults (AN51 = 426.5 +/- 9; 6D1 = 449 +/- 8.7). These results suggest that immunological techniques can be applied as early as 18 weeks of gestation for the antenatal diagnosis of GT and BSS.

The macrophage capacity for phagocytosis

1992 ◽  
Vol 101 (4) ◽  
pp. 907-913 ◽  
Author(s):  
G.J. Cannon ◽  
J.A. Swanson
Keyword(s):  
Surface Area ◽  
Membrane Surface ◽  
Fc Receptors ◽  
Phagocytic Capacity ◽  
Membrane Surface Area ◽  
Murine Bone Marrow ◽  
Latex Beads ◽  
Endocytic Compartments ◽  
Frustrated Phagocytosis

Murine bone marrow-derived macrophages, which measure 13.8 +/− 2.3 microns diameter in suspension, can ingest IgG-opsonized latex beads greater than 20 microns diameter. A precise assay has allowed the determination of the phagocytic capacity, and of physiological parameters that limit that capacity. Ingestion of beads larger than 15 microns diameter required IgG-opsonization, and took 30 minutes to reach completion. Despite the dependence on Fc-receptors for phagocytosis of larger beads, cells reached their limit before all cell surface Fc-receptors were occupied. The maximal membrane surface area after frustrated phagocytosis of opsonized coverslips was similar to the membrane surface area required to engulf particles at the limiting diameter, indicating that the capacity was independent of particle shape. Vacuolation of the lysosomal compartment with sucrose, which expanded endocytic compartments, lowered the phagocytic capacity. This decrease was reversed when sucrose vacuoles were collapsed by incubation of cells with invertase. These experiments indicate that the phagocytic capacity is limited by the amount of available membrane, rather than by the availability of Fc-receptors. The capacity was also reduced by depolymerization of cytoplasmic microtubules with nocodazole. Nocodazole did not affect the area of maximal cell spreading during frustrated phagocytosis, but did alter the shape of the spread cells. Thus, microtubules may coordinate cytoplasm for engulfment of the largest particles.

The structure, biosynthesis and functions of glycosylphosphatidylinositol anchors, and the contributions of trypanosome research

1999 ◽  
Vol 112 (17) ◽  
pp. 2799-2809 ◽  
Author(s):  
M.A. Ferguson
Keyword(s):  
Signal Transduction ◽  
Cell Surface ◽  
Cell Biology ◽  
General Structure ◽  
Surface Glycoprotein ◽  
Variant Surface Glycoprotein ◽  
Membrane Microdomains ◽  
Surface Coat ◽  
Cell Surface Molecules ◽  
Surface Molecules

The discovery of glycosylphosphatidylinositol (GPI) membrane anchors has had a significant impact on several areas of eukaryote cell biology. Studies of the African trypanosome, which expresses a dense surface coat of GPI-anchored variant surface glycoprotein, have played important roles in establishing the general structure of GPI membrane anchors and in delineating the pathway of GPI biosynthesis. The major cell-surface molecules of related parasites are also rich in GPI-anchored glycoproteins and/or GPI-related glycophospholipids, and differences in substrate specificity between enzymes of trypanosomal and mammalian GPI biosynthesis may have potential for the development of anti-parasite therapies. Apart from providing stable membrane anchorage, GPI anchors have been implicated in the sequestration of GPI-anchored proteins into specialised membrane microdomains, known as lipid rafts, and in signal transduction events.

Cholesterol Reporter Molecules

2007 ◽  
Vol 27 (6) ◽  
pp. 335-358 ◽  
Author(s):  
Gerald Gimpl ◽  
Katja Gehrig-Burger
Keyword(s):  
Cholesterol Oxidase ◽  
Phospholipid Bilayer ◽  
Major Constituent ◽  
Membrane Microdomains ◽  
Special Focus ◽  
Perfringolysin O ◽  
Cholesterol Binding

Cholesterol is a major constituent of the membranes in most eukaryotic cells where it fulfills multiple functions. Cholesterol regulates the physical state of the phospholipid bilayer, affects the activity of several membrane proteins, and is the precursor for steroid hormones and bile acids. Cholesterol plays a crucial role in the formation of membrane microdomains such as “lipid rafts” and caveolae. However, our current understanding on the membrane organization, intracellular distribution and trafficking of cholesterol is rather poor. This is mainly due to inherent difficulties to label and track this small lipid. In this review, we describe different approaches to detect cholesterol in vitro and in vivo. Cholesterol reporter molecules can be classified in two groups: cholesterol binding molecules and cholesterol analogues. The enzyme cholesterol oxidase is used for the determination of cholesterol in serum and food. Susceptibility to cholesterol oxidase can provide information about localization, transfer kinetics, or transbilayer distribution of cholesterol in membranes and cells. The polyene filipin forms a fluorescent complex with cholesterol and is commonly used to visualize the cellular distribution of free cholesterol. Perfringolysin O, a cholesterol binding cytolysin, selectively recognizes cholesterol-rich structures. Photoreactive cholesterol probes are appropriate tools to analyze or to identify cholesterol binding proteins. Among the fluorescent cholesterol analogues one can distinguish probes with intrinsic fluorescence (e.g., dehydroergosterol) from those possessing an attached fluorophore group. We summarize and critically discuss the features of the different cholesterol reporter molecules with a special focus on recent imaging approaches.

Establishment of Residue Analysis of Propanil (Dichloropropionanilide), Linuron and Diphenamide in Agricultural Commodities

1985 ◽  
Vol 48 (4) ◽  
pp. 320-324 ◽  
Author(s):  
YOSHIO ITO ◽  
HIDEYO SUZUKI ◽  
SHUNJIRO OGAWA ◽  
MASAHIRO IWAIDA
Keyword(s):  
Detection System ◽  
Residue Analysis ◽  
Brown Rice ◽  
Sodium Hydride ◽  
Gas Chromatograph ◽  
Florisil Column ◽  
Florisil Column Chromatography ◽  
Additional Level ◽  
Ppm Level

A method for simultaneous determination of residues of three herbicides containing nitrogen, propanil (3′,4′-dichloropropionanilide), linuron and diphenamide, in agricultural commodites was established. The herbicides were extracted by acetone from samples, transferred into dichloromethane, then the dichloromethane extract was dried. The residue was dissolved in n-hexane, and purified from oily contaminants by partition with acetonitrile. The acetonitrile extract was further purified by Florisil column chromatography with dichloromethane. Diphenamide was determined directly by use of gas chromatograph equipped with a flame-thermoionic detection system (FTDGC). DCPA and linuron were derivatized into their N-monomethyl derivatives by a strong methylation method by use of sodium hydride and methyl iodide in a mixture of dimethyl sulfoxide and benzene, and then subjected to determination by FTD-GC. Recoveries of the three herbicides from brown rice, barley, corn, potato, carrot and onion were not less than 80% at the additional level of 1.0 ppm, while not less than 70% at 0.1 ppm level, respectively.

Pattern Analysis Meets Cell Biology

1999 ◽  
Vol 5 (S2) ◽  
pp. 510-511
Author(s):  
Robert F. Murphy ◽  
Michael V. Boland
Keyword(s):  
Cell Biology ◽  
Fluorescent Dyes ◽  
Protein A ◽  
Chinese Hamster ◽  
Subcellular Location ◽  
Computer Applications ◽  
Double Labeling ◽  
A Cell ◽  
Widespread Availability

The widespread availability of automated fluorescence microscope systems has led to an explosion in the acquisition of digital images by biologists. This has created a need for computer applications that automate the analysis of these images and an opportunity to develop new approaches to classical problems. An example is the determination of the subcellular location of a protein from immunofluorescence images (or, more recently, images of GFP fluorescence). Current practice is to compare such images to mental images that a cell biologist has developed over time, and to reach a tentative conclusion about the structure (i.e., organelle) that a protein is found in. Since this determination is subjective, it often must be followed up by double labeling with a marker protein from the suspected structure.As an initial exploration of the feasibility of automating the determination of subcellular location, we developed a system that is able to classify the localization patterns characteristic of five cellular molecules (proteins and DNA) in Chinese Hamster Ovary (CHO) cells. Images were acquired on an epifluorescence microscope after the cells had been fixed, permeabilized, and labeled with appropriate fluorescent reagents (usually antibodies conjugated to fluorescent dyes). The labels used were directed against a Golgi protein, a lysosomal protein, a nuclear protein, a cytoskeletal protein, and DNA.

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