THE RELATION BETWEEN FROST RESISTANCE AND THE PHYSICAL STATE OF PROTOPLASM: II. THE PROTOPLASMIC SURFACE

1941 ◽  
Vol 19c (1) ◽  
pp. 9-20 ◽  
Author(s):  
D. Siminovitch ◽  
J. Levitt
Keyword(s):  
Refractive Index ◽  
Frost Resistance ◽  
Physical State ◽  
Surface Membrane ◽  
Protoplasmic Surface

Deplasmolysis injury, ductility of cytoplasmic strands, and the shape assumed by injected oil drops on deplasmolysis were investigated. The surface membrane of the protoplast of non-hardy cells stiffened when dehydrated osmotically. As a result, it ruptured readily when subjected to tension. The stiffening either failed to occur in hardy cells, or it arose only as a result of a much greater dehydration (depending on the degree of hardiness). The refractive index of the protoplasmic surface increased more on dehydration in the case of non-hardy than of hardy cells. Plasmolysis, if maintained for some time, induced a clumping of plastids and granules (systrophy) in non-hardy but not in hardy cells. All these facts indicate a greater hydrophily in hardy than in non-hardy cells—both of the surface membrane of the protoplasm and, as shown in Part I, of the protoplasm as a whole, although it is probably less marked in the latter.

THE RELATION BETWEEN FROST RESISTANCE AND THE PHYSICAL STATE OF PROTOPLASM: I. THE PROTOPLASM AS A WHOLE

1940 ◽  
Vol 18c (11) ◽  
pp. 550-561 ◽  
Author(s):  
J. Levitt ◽  
D. Siminovitch
Keyword(s):  
Frost Resistance ◽  
Physical State ◽  
Injury Rate ◽  
Mechanical Injury ◽  
Brownian Movement

The protoplasm of hardy and non-hardy cells was compared with regard to displacement by centrifuging, rounding-up time on plasmolysis, deplasmolysis injury, rate of Brownian movement, resistance to and recovery from distortion by micromanipulation. The conclusions are: (i) When the cells are in the normally hydrated (i.e., turgid) condition there is either no difference in the consistency of hardy and non-hardy protoplasm, or else it is slightly less m the latter; (ii) when the cells are plasmolysed to the same degree (i.e., with a weaker plasmolyte in the case of the non-hardy) there is no difference in consistency; (iii) when the cells are in equilibrium with one and the same concentration of plasmolyte, the protoplasmal consistency of the non-hardy is greater than that of the hardy; (iv) the non-hardy are more susceptible to mechanical injury.

II. Electrostatic capacity of glass

1878 ◽  
Vol 169 ◽  
pp. 17-23 ◽  
Keyword(s):  
Refractive Index ◽  
Magnetic Permeability ◽  
Wave Motion ◽  
Physical State ◽  
Refractive Indices ◽  
Guard Ring ◽  
Electricity And Magnetism ◽  
The Difference ◽  
Electric Quantity ◽  
Limits Of Error

1. In his work on Electricity and Magnetism Professor Maxwell developes a theory in which electric and magnetic phenomena are explained by changes of position of the medium, the wave motion of which constitutes Light. He deduces with the aid of this theory that that velocity, which is the ratio of the electrostatic and electro­magnetic units of electric quantity, is identical with the velocity of light. This deduction may be said to be verified within the limits of error of our knowledge of these quantities. He further finds that the product of the electrostatic capacity and the magnetic permeability of a transparent substance is equal to the square of the refractive index for long waves. The only available experiments for testing this result when Professor Maxwell’s book was published were the “Determinations of Electrostatic Capacity of Solid Paraffin,” by Messrs. Gibson and Barclay (Phil. Trans., 1871), and the ‘Determinations of Refractive Indices of Melted Paraffin,’ by Dr. Gladstone. Considering the difference in physical state in the two experiments the result verifies the theory fairly well. The various kinds of optical flint glass are suitable for the purpose of making a comparison of refractive indices and specific inductive capacity, since each is an article pretty constant in its composition and physical properties, and has small conductivity and return charge. 2. The only convenient form in which glass can be examined is a plate with plane parallel sides; this plate must form the dielectric of a guard ring condenser. Four instruments are thus required, the guard ring condenser, an adjustable condenser which can be made equal to the first, a battery for giving equal and opposite charges to the two condensers, and an electroscope to show when the added charges of the condensers are nil.

Molecular imaging by Raman microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1512-1513
Author(s):  
D.N. Batchelder ◽  
B.J.E. Smith ◽  
S. Webster ◽  
C. Cheng
Keyword(s):  
Refractive Index ◽  
Raman Spectrum ◽  
Physical State ◽  
Raman Band ◽  
Optical Microscope ◽  
Optical Quality ◽  
Pass Band ◽  
Positive Identification ◽  
Multilayer Dielectric

The optical microscope relies on spatial variations of refractive index, absorption and reflectivity in a specimen in order to produce the modulation in light intensity necessary to form the magnified image. The ability to identify the materials which comprise the specimen is very limited as these properties are generally not material specific. By contrast the Raman spectrum of a material is usually not only sufficient to give positive identification, but detail in the spectrum can often be used to assess the physical state of the material. Thus images recorded in light scattered in a particular Raman band should be very informative about the distribution of different molecular species.We have developed a Raman microscope which uses multilayer dielectric filters to select the Raman band with which the image is formed. The optical quality of the filters is sufficiently high so as not to degrade the image forming capabilities of the microscope. The filters typically have a pass band of 20 cm-1 and are wavelength tuned by rotation.

Influence of Calcium Ions on the Plant Cell Surface: Membrane Fusions and Conformational Changes

1974 ◽  
Vol 32 ◽  
pp. 154-155
Author(s):  
D. James Morré ◽  
Charles E. Bracker ◽  
William J. VanDerWoude
Keyword(s):  
Cell Wall ◽  
Cell Surface ◽  
Conformational Changes ◽  
Calcium Ions ◽  
Surface Membrane ◽  
Carboxyl Groups ◽  
Cross Linking ◽  
Ultrastructural Evidence ◽  
Glycine Max L ◽  
Wall Extensibility

Calcium ions in the concentration range 5-100 mM inhibit auxin-induced cell elongation and wall extensibility of plant stems. Inhibition of wall extensibility requires that the tissue be living; growth inhibition cannot be explained on the basis of cross-linking of carboxyl groups of cell wall uronides by calcium ions. In this study, ultrastructural evidence was sought for an interaction of calcium ions with some component other than the wall at the cell surface of soybean (Glycine max (L.) Merr.) hypocotyls.

Oncornavirus assembly at the cell surface revealed in replicas of freeze-dried cells

1978 ◽  
Vol 36 (2) ◽  
pp. 354-355
Author(s):  
Anthony Demsey ◽  
Christopher W. Stackpole
Keyword(s):  
Cell Surface ◽  
Surface Membrane ◽  
Viral Origin ◽  
Intact Cells ◽  
Structural Formation ◽  
Virus Core ◽  
Freeze Dried ◽  
Cacodylate Buffer ◽  
Surface Replica ◽  
Leukemia Viruses

The murine leukemia viruses are type-C oncornaviruses, and their release from the host cell involves a “budding” process in which the newly-forming, RNA-containing virus core becomes enveloped by modified cell surface membrane. Previous studies revealed that the released virions possess a dense array of 10 nm globular projections (“knobs”) on this envelope surface, and that these knobs contain a 70, 000 MW glycoprotein (gp70) of viral origin. Taking advantage of this distinctive structural formation, we have developed a procedure for freeze-drying and replication of intact cells which reveals surface detail superior to other surface replica techniques, and sufficient to detect even early stages of virus budding by localized aggregation of these knobs on the cell surface.Briefly, cells growing in monolayer are seeded onto round glass coverslips 10-12 mm in diameter. After a period of growth, cells are fixed in situ for one hour, usually with 1% OsO4 in 0. 1 M cacodylate buffer, and rinsed in distilled water.

TEM characterization of proton-exchanged LiNbO3 optical waveguides

1986 ◽  
Vol 44 ◽  
pp. 480-481
Author(s):  
W. E. Lee
Keyword(s):  
Refractive Index ◽  
Benzoic Acid ◽  
Optical Waveguides ◽  
Total Internal Reflection ◽  
Index Of Refraction ◽  
Optical Measurements ◽  
Lithium Ions ◽  
Wide Channel ◽  
Tem Characterization

An optical waveguide consists of a several-micron wide channel with a slightly different index of refraction than the host substrate; light can be trapped in the channel by total internal reflection.Optical waveguides can be formed from single-crystal LiNbO3 using the proton exhange technique. In this technique, polished specimens are masked with polycrystal1ine chromium in such a way as to leave 3-13 μm wide channels. These are held in benzoic acid at 249°C for 5 minutes allowing protons to exchange for lithium ions within the channels causing an increase in the refractive index of the channel and creating the waveguide. Unfortunately, optical measurements often reveal a loss in waveguiding ability up to several weeks after exchange.

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.

Application of high-resolution field-emission LVSEM, backscatter imaging, immunogold staining to definition of the spatial distributions of two human neutrophil adherence receptors

1993 ◽  
Vol 51 ◽  
pp. 36-37
Author(s):  
Robert D. Nelson ◽  
Sharon R. Hasslen ◽  
Stanley L. Erlandsen
Keyword(s):  
Cell Surface ◽  
Surface Membrane ◽  
Three Dimensional ◽  
Human Neutrophils ◽  
Spatial Distributions ◽  
Immunogold Staining ◽  
Functional Control ◽  
Neutrophil Adherence ◽  
Definition Of ◽  
Mode Of Attachment

Receptors are commonly defined in terms of number per cell, affinity for ligand, chemical structure, mode of attachment to the cell surface, and mechanism of signal transduction. We propose to show that knowledge of spatial distribution of receptors on the cell surface can provide additional clues to their function and components of functional control.L-selectin and Mac-1 denote two receptor populations on the neutrophil surface that mediate neutrophil-endothelial cell adherence interactions and provide for targeting of neutrophil recruitment to sites of inflammation. We have studied the spatial distributions of these receptors using LVSEM and backscatter imaging of isolated human neutrophils stained with mouse anti-receptor (primary) antibody and goat anti-mouse (secondary) antibody conjugated to 12 nm colloidal gold. This combination of techniques provides for three-dimensional analysis of the expression of these receptors on different surface membrane domains of the neutrophil: the ruffles and microvilli that project from the cell surface, and the cell body between these projecting structures.

Light microscopy of ceramics

1993 ◽  
Vol 51 ◽  
pp. 908-909
Author(s):  
Walter C. McCrone
Keyword(s):  
Refractive Index ◽  
Light Microscopy ◽  
Light Microscope ◽  
Polarized Light ◽  
Refractive Indices ◽  
Complete Coverage ◽  
The Subject ◽  
Lower Refractive Index

An excellent chapter on this subject by V.D. Fréchette appeared in a book edited by L.L. Hench and R.W. Gould in 1971 (1). That chapter with the references cited there provides a very complete coverage of the subject. I will add a more complete coverage of an important polarized light microscope (PLM) technique developed more recently (2). Dispersion staining is based on refractive index and its variation with wavelength (dispersion of index). A particle of, say almandite, a garnet, has refractive indices of nF = 1.789 nm, nD = 1.780 nm and nC = 1.775 nm. A Cargille refractive index liquid having nD = 1.780 nm will have nF = 1.810 and nC = 1.768 nm. Almandite grains will disappear in that liquid when observed with a beam of 589 nm light (D-line), but it will have a lower refractive index than that liquid with 486 nm light (F-line), and a higher index than that liquid with 656 nm light (C-line).

Role of the Cilia Membrane in Control of Microtubule Sliding

1980 ◽  
Vol 38 ◽  
pp. 612-615
Author(s):  
Edna S. Kaneshiro
Keyword(s):  
Control Mechanism ◽  
Beat Frequency ◽  
Surface Membrane ◽  
Ciliary Membrane ◽  
Ciliary Beating ◽  
Ciliary Reversal ◽  
Voltage Dependent ◽  
Reversal Mechanism ◽  
And Function

It is currently believed that ciliary beating results from microtubule sliding which is restricted in regions to cause bending. Cilia beat can be modified to bring about changes in beat frequency, cessation of beat and reversal in beat direction. In ciliated protozoans these modifications which determine swimming behavior have been shown to be related to intracellular (intraciliary) Ca2+ concentrations. The Ca2+ levels are in turn governed by the surface ciliary membrane which exhibits increased Ca2+ conductance (permeability) in response to depolarization. Mutants with altered behaviors have been isolated. Pawn mutants fail to exhibit reversal of the effective stroke of ciliary beat and therefore cannot swim backward. They lack the increased inward Ca2+ current in response to depolarizing stimuli. Both normal and pawn Paramecium made leaky to Ca2+ by Triton extrac¬tion of the surface membrane exhibit backward swimming only in reactivating solutions containing greater than IO-6 M Ca2+ Thus in pawns the ciliary reversal mechanism itself is left operational and only the control mechanism at the membrane is affected. The topographic location of voltage-dependent Ca2+ channels has been identified as a component of the ciliary mem¬brane since the inward Ca2+ conductance response is eliminated by deciliation and the return of the response occurs during cilia regeneration. Since the ciliary membrane has been impli¬cated in the control of Ca2+ levels in the cilium and therefore is the site of at least one kind of control of microtubule sliding, we have focused our attention on understanding the structure and function of the membrane.

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