The Periodic Changes in Microvilli Density in Activated Xenopus Eggs That Correspond to the Cleavage Cycle. (surface structure/cleavage cycle/SCW/Xenopus egg/GV-dependency)

This paper investigates the localization within the Xenopus egg of the factors responsible for the periodic activities such as the cyclic rounding-up and flattening, related to the cleavage cycle. Denuded eggs were bisected along the boundary line between the animal and the vegetal hemispheres immediately after being rotated through 90° off the vertical axis (Early Bisection). The resulting animal halves, though prevented from cell division by colchicine, showed typical periodic rounding-up as previously observed in enucleated egg fragments, whereas the vegetal halves did not. This result indicates that the factors inducing the periodic rounding-up are not distributed uniformly throughout the egg but localized mostly in the animal hemisphere. Furthermore, the distribution of these factors between the cortex and endoplasm of the animal hemisphere was investigated. Eggs were separated into animal and vegetal halves following incubation for 30min after the 90°-off axis rotation (Late Bisection). During this incubation the endoplasmic components become relocated in the rotated egg under the force of gravity. After the rotation, the Late-Bisected vegetal halves showed typical cyclic rounding-up in contrast to those formed by Early Bisection. These results suggest that the factors inducing the periodic rounding-up (and probably also many other cyclic activities, closely linked with the rounding-up movement) are localized in endoplasmic components which can be displaced by gravity from the animal to the vegetal hemisphere of the Xenopus egg.

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Surface Structure of the Spores of Glugea Weissenbergi

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010006310x ◽

1969 ◽

Vol 27 ◽

pp. 238-239

Author(s):

Sanford H. Vernick ◽

Anastasios Tousimis ◽

Victor Sprague

Keyword(s):

Electron Microscope ◽

Surface Structure ◽

Transmission Electron Microscope ◽

Mature Spore ◽

Spore Surface ◽

Sectioned Material ◽

Transmission Electron ◽

Surface Detail

Recent electron microscope studies have greatly expanded our knowledge of the structure of the Microsporida, particularly of the developing and mature spore. Since these studies involved mainly sectioned material, they have revealed much internal detail of the spores but relatively little surface detail. This report concerns observations on the spore surface by means of the transmission electron microscope.

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Surface Structure of Nucleated Animal Cells: Carbon Replicas

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060611 ◽

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.

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High resolution surface structure of foot-and-mouth disease virus

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100082741 ◽

1978 ◽

Vol 36 (2) ◽

pp. 376-377

Author(s):

S. S. Breese ◽

H. L. Bachrach

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Surface Structure ◽

Disease Virus ◽

Potassium Phosphate ◽

Foot And Mouth Disease ◽

Mouth Disease ◽

Physical Measurements ◽

Mouth Disease Virus ◽

Foot And Mouth

Models for the structure of foot-and-mouth disease virus (FMDV) have been proposed from chemical and physical measurements (Brown, et al., 1970; Talbot and Brown, 1972; Strohmaier and Adam, 1976) and from rotational image-enhancement electron microscopy (Breese, et al., 1965). In this report we examine the surface structure of FMDV particles by high resolution electron microscopy and compare it with that of particles in which the outermost capsid protein VP3 (ca. 30, 000 daltons) has been split into smaller segments, two of which VP3a and VP3b have molecular weights of about 15, 000 daltons (Bachrach, et al., 1975).Highly purified and concentrated type A12, strain 119 FMDV (5 mg/ml) was prepared as previously described (Bachrach, et al., 1964) and stored at 4°C in 0. 2 M KC1-0. 5 M potassium phosphate buffer at pH 7. 5. For electron microscopy, 1. 0 ml samples of purified virus and trypsin-treated virus were dialyzed at 4°C against 0. 2 M NH4OAC at pH 7. 3, deposited onto carbonized formvar-coated copper screens and stained with phosphotungstic acid, pH 7. 3.

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Examination of Schistosome Cercariae and Schistosomules by Scanning Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100062154 ◽

1969 ◽

Vol 27 ◽

pp. 50-51

Author(s):

D. Johnson ◽

P. Moriearty

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

High Resolution ◽

Light Microscopy ◽

Surface Structure ◽

Extensive Study ◽

Scanning Microscopy ◽

Host Parasite ◽

Conventional Electron Microscopy ◽

Scanning Electron

Since several species of Schistosoma, or blood fluke, parasitize man, these trematodes have been subjected to extensive study. Light microscopy and conventional electron microscopy have yielded much information about the morphology of the various stages; however, scanning electron microscopy has been little utilized for this purpose. As the figures demonstrate, scanning microscopy is particularly helpful in studying at high resolution characteristics of surface structure, which are important in determining host-parasite relationships.

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Profile Imaging of Silicon Surface Reconstructions

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118229 ◽

1985 ◽

Vol 43 ◽

pp. 262-263

Author(s):

O.L. Krivanek ◽

G.J. Wood

Keyword(s):

Electron Microscopy ◽

Surface Structure ◽

Structure Determination ◽

Silicon Surface ◽

Good Resolution ◽

Surface Reconstructions ◽

Bulk Structure ◽

Point To Point ◽

The Relationship

Electron microscopy at 0.2nm point-to-point resolution, 10-10 torr specimei region vacuum and facilities for in-situ specimen cleaning presents intere; ing possibilities for surface structure determination. Three methods for examining the surfaces are available: reflection (REM), transmission (TEM) and profile imaging. Profile imaging is particularly useful because it giv good resolution perpendicular as well as parallel to the surface, and can therefore be used to determine the relationship between the surface and the bulk structure.

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