Electron microscopic observations of the envelopes of isolated algal packets of Azolla

1991 ◽  
Vol 69 (7) ◽  
pp. 1418-1419 ◽  
Author(s):  
Eiji Uheda ◽  
Shunji Kitoh
Keyword(s):  
Electron Microscope ◽  
Nitric Acid ◽  
Sodium Hydroxide ◽  
Key Words ◽  
Layer Structure ◽  
Sodium Dodecylsulfate ◽  
Electron Microscopic ◽  
Microscopic Studies ◽  
20 Nm

The envelopes of isolated algal packets from cyanobiont-containing and cyanobiont-free Azolla were examined with the electron microscope. Both types of envelope were 10–20 nm thick and composed of three layers. The three-layer structure was also observed when algal packets were treated with cellulase, pectinase, lipase, protease, sodium hydroxide, nitric acid, or sodium dodecylsulfate. Thus, the envelopes do not appear to be membrane-like in nature and the presence and ultrastructure of the envelopes are not affected by cyanobiont filaments. Key words: algal packet, cyanobiont-free Azolla, Azolla, electron microscopic studies, envelope.

scholarly journals An Electron Microscope Study of Snow Crystal Nuclei

1953 ◽  
Vol 2 (13) ◽  
pp. 176-180
Author(s):  
Ukichiro Nakaya
Keyword(s):  
Electron Microscope ◽  
Electron Microscope Study ◽  
Condensation Nuclei ◽  
Electron Microscopic ◽  
Carbon Particles ◽  
Snow Crystal ◽  
Microscopic Studies ◽  
Snow Crystals ◽  
Micro Organisms ◽  
Collodion Film

AbstractSnow crystals were received on the collodion film of the holder of an electron microscope, and made to sublimate without melting. These specimens were investigated under an electron microscope. One solid nucleus was always observed in the central portion of a snow crystal. These centre nuclei were of sizes between 0.5 and 8μ. Most of them were presumed to be kaolin, clay or carbon particles; some were considered to be micro-organisms. In the other parts of snow crystals numerous smaller nuclei were observed, whose dimensions were of the order of those of condensation nuclei. These condensation nuclei were found to be of two kinds, the larger ones most frequently having a diameter of about 0.15μ, the smaller ones of about 0.05μ. A new theory was proposed from the data of the electron microscopic studies and those of the conditions of formation of snow crystals. In this theory it is proposed that minute water droplets of 1μor so play an important rôls in the process of snow crystal growth.

Electron Microscopic Studies of Fillers in Rubber. III. Effect of Milling on the Dispersion of Fillers

1956 ◽  
Vol 29 (3) ◽  
pp. 1003-1010 ◽  
Author(s):  
Eiji Suito ◽  
Masafumi Arakawa ◽  
Hiroshi Hasegawa ◽  
Yonemasa Furusawa
Keyword(s):  
Electron Microscope ◽  
Marked Effect ◽  
The State ◽  
Replica Method ◽  
Interesting Problem ◽  
Electron Microscopic ◽  
Vulcanized Rubber ◽  
Microscopic Studies ◽  
Filler Particles ◽  
The Relationship

Abstract In the study of types of fillers which have a marked effect on the properties of rubber, information as to how the filler particles are dispersed in rubber is a prerequisite. The authors have already reported on the state of dispersion of various fillers in vulcanized rubber, observed under an electron microscope by the replica method. How the dispersion of these fillers affects the properties of rubber is an interesting problem. Since, in the earlier work, filler particles were observed to orient themselves in certain directions, in this report the relationship between the state of dispersion observed under an electron microscope of filler particles in rubber milled in different ways and the resulting characteristics of the mixtures were examined.

Electron microscope study on the glial filaments of astrocytes in the rat brain

1978 ◽  
Vol 36 (2) ◽  
pp. 618-619
Author(s):  
S. Mori ◽  
K. Furukawa ◽  
H. Abe
Keyword(s):  
Body Weight ◽  
Electron Microscope ◽  
Glial Cells ◽  
Microscope Study ◽  
Phosphate Buffer ◽  
Electron Microscope Study ◽  
Gold Chloride ◽  
Electron Microscopic ◽  
New Knowledge ◽  
Microscopic Studies

With the electron microscope, it was demonstrated that the glial filaments existed in astrocytes and could be impregnated by Cajal's gold chloride sublimate solution. By this conspicuous structure of glial filaments, thus, the astrocytes have long been differentiated from other glial cells from the classical light microscopic studies till the recent electron microscopic observations. Further investigations could add the new knowledge on this important component of glial cells in this laboratory that the actin- like filaments might be contained among the glial filaments. It will be shown in this report that glial filaments of astrocytes are consisted of the heterogenous groups of filaments, and some of them can bind with the heavy meromyosins (HMM).Normal rats (about 120 g body weight) were anesthetized with Nembutal and fixed by perfusion through the heart for 30 minutes with the fixative. This fluid was consisted of 3 % glutaraldehyde, 2 % paraformaldehyde, 4 % sucrose and 0. 5 mM CaCl2 in 0. 1 M phosphate buffer at PH 7. 4.

Electron microscopy of spermatocytes previously studied in life: methods and some observations on micromanipulated chromosomes

1979 ◽  
Vol 35 (1) ◽  
pp. 87-104
Author(s):  
R.B. Nicklas ◽  
B.R. Brinkley ◽  
D.A. Pepper ◽  
D.F. Kubai ◽  
G.K. Rickards
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Target Cell ◽  
Living Cell ◽  
Chromosome Movement ◽  
Electron Microscopic ◽  
Microscopic Studies ◽  
Direction Of Movement ◽  
Spindle Microtubules ◽  
Future Work

A new method is offered for combined living cell and electron-microscopic studies of spermatocytes (or other cells) which normally do not adhere to glass. The key step is micro-injection of glutaraldehyde near the target cell whenever desired during observation in life. Fixation begins and simultaneously the cell is stuck very firmly to the underlying coverslip. The method is easy and reliable: cells are almost never lost and are well preserved, except for membranes. The application of the method is illustrated by studies of micromanipulated grasshopper spermatocytes. A chromosome was detached from the spindle and placed in the cytoplasm. Before or after the beginning of chromosome movement back toward the spindle, the cell was fixed, sectioned and the manipulated chromosome observed in the electron microscope. If the detached chromosome had not moved by the time of fixation, no or only one or two microtubules were seen at its kinetochore, but if movement had occurred, a few microtubules were always present. The arrangement of these microtubules corresponded to the direction of movement, but they commonly were at an unusual angle relative to the kinetochore. The origin and role in chromosome movement of the microtubules seen near moving chromosomes far from the spindle is not yet established, but a speculation is offered. A goal for future work is the detailed analysis of the microtubules associated with individual moving chromosomes. Such an analysis is feasible because the moving chromosome is far removed from the confusing mass of spindle microtubules, and its value is enhanced because the direction of movement at the time of fixation is known.

Thrombin and Reptilase Induced Fibrin Structures in the Presence of Dextran: A Quantitative Electron Microscope Study

1975 ◽  
Author(s):  
W. H. Krause ◽  
P. Zimmermann
Keyword(s):  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Microscopic Analysis ◽  
Electron Microscopic Analysis ◽  
Segment Length ◽  
Electron Microscopic ◽  
Fibrin Network ◽  
Significant Difference ◽  
Microscopic Studies

The present study describes an electron microscopic analysis, using a quantitative morphometric method, of fibrin network obtained by thrombin and reptilase in the presence of dextran. The thickness of the thrombin induced fibrin meshwork show a significant difference compared to fibrin formed by reptilase. The segment length of reptilase fibrin are reduced to 25% and the thickness of the fibers are reduced to 75% in comparison with thrombin fibrin.The thickness of the fibrin meshwork obtained by thrombin and/or reptilase in the presence of dextran ( w 40,000) is significantly diminished compared to saline controls (p < 0.001). Segment length and thickness of fibers in the clots with dextran showed different results when thrombin or reptilase were used as enzyme.The investigation indicates that the fibrin meshwork formed by thrombin and/or reptilase in the presence or absence of dextran result in a significantly different fibrin morphylogy. The results are different to the so far descriptive electron microscopic studies.

Electron Microscope Studies on Isolated Plant Protoplasts

1966 ◽  
Vol 21 (6) ◽  
pp. 581-585b ◽  
Author(s):  
E. C. Cocking
Keyword(s):  
Electron Microscope ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Close Association ◽  
Physiological Activity ◽  
Tomato Fruit ◽  
Plant Protoplasts ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Microscopic Studies

Isolated tomato fruit protoplasts have been observed to take up both tobacco mosaic virus and ferritin by the process of pinocytosis. These studies have involved electron microscopic observations on thin sections of suitably fixed and embedded material. These electron microscopic studies have also shown that very close association exists between the nucleus and chloroplasts in these protoplasts and that occasionally there are present channels extending from the plasmalemma into the cytoplasm. The implication of these results is discussed in relation to the general physiological activity of protoplasts.

scholarly journals ELECTRON MICROSCOPIC STUDIES OF MITOSIS IN AMEBAE

1960 ◽  
Vol 8 (1) ◽  
pp. 207-220 ◽  
Author(s):  
L. E. Roth ◽  
S. W. Obetz ◽  
E. W. Daniels
Keyword(s):  
Electron Microscope ◽  
Nuclear Envelope ◽  
Osmium Tetroxide ◽  
Thin Sheet ◽  
Amoeba Proteus ◽  
Electron Microscopic ◽  
Interphase Nuclei ◽  
Nucleolar Material ◽  
Microscopic Studies ◽  
Early Reconstruction

Individual organisms of Amoeba proteus have been fixed in buffered osmium tetroxide in either 0.9 per cent NaCl or 0.01 per cent CaCl2, sectioned, and studied in the electron microscope in interphase and in several stages of mitosis. The helices typical of interphase nuclei do not coexist with condensed chromatin and thus either represent a DNA configuration unique to interphase or are not DNA at all. The membranes of the complex nuclear envelope are present in all stages observed but are discontinuous in metaphase. The inner, thick, honeycomb layer of the nuclear envelope disappears during prophase, reappearing after telophase when nuclear reconstruction is in progress. Nucleoli decrease in size and number during prophase and re-form during telophase in association with the chromatin network. In the early reconstruction nucleus, the nucleolar material forms into thin, sheet-like configurations which are closely associated with small amounts of chromatin and are closely applied to the inner, partially formed layer of the nuclear envelope. It is proposed that nucleolar material is implicated in the formation of the inner layer of the envelope and that there is a configuration of nucleolar material peculiar to this time. The plasmalemma is partially denuded of its fringe-like material during division.

Radiation effects on minerals in the electron microscope

1983 ◽  
Vol 41 ◽  
pp. 350-353
Author(s):  
David R. Veblen ◽  
Peter R. Buseck
Keyword(s):  
Electron Microscope ◽  
Radiation Damage ◽  
Radiation Effects ◽  
Limiting Factor ◽  
Electron Microscopic ◽  
Electron Dose ◽  
Good Opportunity ◽  
Wide Range ◽  
High Resolution Tem ◽  
Microscopic Studies

Radiation damage is commonly the most important limiting factor in transmission electron microscopic studies of minerals. This is especially true for high-resolution TEM (HRTEM) investigations, which typically utilize a relatively large electron dose. Conversely, because of this requirement, HRTEM studies provide a good opportunity for observing the effects of radiation in the electron microscope on different minerals. In this contribution, we attempt to impose some chemical and structural order on observations of beam damage in minerals, mostly silicates, based on HRTEM investigations of a wide range of specimens over the past decade.Because reports of radiation damage rates in the TEM are typically anecdotal, with no fixed point of reference, we here limit our comparisons of rates to first-hand observations. These observations were made primarily at lOOkV in a JEOL JEM100B microscope, although some of the same systematics also have been noted in other instruments at voltages up to 200kV. In addition, experiments of others where part of a crystal structure damages selectively are discussed.

Electron Microscopic Studies of Gerbil Testis After Vasectomy

1976 ◽  
Vol 34 ◽  
pp. 154-155
Author(s):  
S. K. MAJUMDAR ◽  
FRED KALENSCHER
Keyword(s):  
Electron Microscope ◽  
Normal Structure ◽  
Uranyl Acetate ◽  
Meriones Unguiculatus ◽  
Mongolian Gerbils ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Acetate Lead ◽  
Microscopic Studies ◽  
Ultrathin Sections

Ultrathin sections made from bilaterally vasectomized as well as bilaterally sham-operated Mongolian gerbils (Meriones unguiculatus) were examined and compared under an electron microscope in order to determine whether vasectomy has any effect upon the fine structure of the testis. The whole testes were removed and placed in Karnovsky's fixative for one hour. After this period the testes were diced into small pieces and fixed for an additional hour in the same fixative. After rinsing in distilled water and postfixed for one hour in OsO4, the tissues were embedded in Epon 812. The sections were stained with uranyl acetate-lead citrate and examined on a Philips Model 201 transmission electron microscope. Shamoperated testis exhibited normal structure of germ cells.

Adrenal gland ultrastructural pathology in plasmodium berghei parasitized mice

1996 ◽  
Vol 54 ◽  
pp. 748-749
Author(s):  
M. Pulido-Méndez ◽  
H.J. Finol ◽  
A. Rodríguez-Acosta ◽  
A. Márquez ◽  
I. Aguilar ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Adrenal Gland ◽  
Adrenal Cortex ◽  
Plasmodium Berghei ◽  
Liver Pathology ◽  
Male Mice ◽  
Electron Microscopic ◽  
Malaria Research ◽  
Transmission Electron ◽  
Microscopic Studies

The use of animal models is widely accepted in malaria research. Plasmodium berghei has been extensively studied because it produces a mortal malaria in rodents. Electron microscopic studies on brain and liver pathology have been performed in this infection. In a previous ultrastructural work we reported the capillary alterations observed in adrenal cortex in P. berghei infected mice. In this work we describe the cell and capillary changes we found in adrenal cortex and medulla in this infection.Male mice weighing 18-22 g were inoculated intraperitoneally with P. berghei infected erythrocytes. At the ninth day animals were sacrificed when parasitemia ranged between 80-90%. Adrenal gland samples were processed by routine techniques and observed in a Hitachi H-500 transmission electron microscope.

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