Recent developments in the use of autoradiographic techniques with electron microscopy

1971 ◽  
Vol 261 (837) ◽  
pp. 159-171 ◽  
Keyword(s):  
Electron Microscopy ◽  
Osmium Tetroxide ◽  
New World ◽  
Tracer Experiment ◽  
Electron Microscope Level ◽  
Starting Point ◽  
Recent Developments ◽  
Cell Organization ◽  
The One ◽  
Radio Isotopes

The development of techniques for observing tissues by electron microscopy has opened a whole new world of structure to the biologist. As the descriptive detail of cell organization has built up, the pressure for methods that would link these new structures to the biochemistry of the cell has also increased. It was inevitable that an attempt to apply the radio-isotopic tracer experiment at the electron microscope level should be made: it was equally certain that this attempt would involve autoradiography, since the nuclear emulsion is the only detector for radio-isotopes with powers of resolution anywhere near sufficient for the size of organelle under study. In attempting to marry the two approaches of electron microscopy and autoradiography, the logical starting-point has been to take the established product of the one technique—the conventional thin section of tissue—and attempt to adapt the methods and materials of autoradiography to it. To this day, the majority of publications in this field deal with material fixed in aldehydes, postfixed in osmium tetroxide, embedded in epon or araldite, and sectioned at 50 to 100 nm. Most of the information available deals with this type of specimen as the source of radioactivity.

A Resorcinol-Formaldehyde Resin as an Embedding Material for Electron Microscopy of Membranes

1969 ◽  
Vol 27 ◽  
pp. 328-329 ◽  
Author(s):  
J. G. Robertson ◽  
D. F. Parsons
Keyword(s):  
Electron Microscopy ◽  
Osmium Tetroxide ◽  
Neutral Lipids ◽  
Lipid Extraction ◽  
Water Soluble ◽  
Formaldehyde Resin ◽  
Electron Microscope Autoradiography ◽  
Resorcinol Formaldehyde ◽  
Major Disadvantage ◽  
Cell Organization

The extraction of lipids from tissues during fixation and embedding for electron microscopy is widely recognized as a source of possible artifact, especially at the membrane level of cell organization. Lipid extraction is also a major disadvantage in electron microscope autoradiography of radioactive lipids, as in studies of the uptake of radioactive fatty acids by intestinal slices. Retention of lipids by fixation with osmium tetroxide is generally limited to glycolipids, phospholipids and highly unsaturated neutral lipids. Saturated neutral lipids and sterols tend to be easily extracted by organic dehydrating reagents prior to embedding. Retention of the more saturated lipids in embedded tissue might be achieved by developing new cross-linking reagents, by the use of highly water soluble embedding materials or by working at very low temperatures.

Recent Developments in Elt – Part II

1982 ◽  
Vol 15 (3) ◽  
pp. 174-194 ◽  
Author(s):  
J. T. Roberts
Keyword(s):  
Psychological Approach ◽  
Danger Signs ◽  
Classroom Techniques ◽  
Starting Point ◽  
Recent Developments ◽  
Communicative Approach ◽  
To Come ◽  
The One ◽  
Descriptive Knowledge ◽  
Communicative Teaching

What the foregoing should have brought out is that ‘communication’ and ‘communicative’ are still very much the watchwords of current ELT, and that interest in research into what constitutes ‘communication’ persists strongly. It is, of course, true that over the last ten or so years a vast corpus of new knowledge has been accumulated and has led to many new applications; yet it is also evident that there is as yet little feeling of self-satisfaction and that efforts continue to be directed towards improvement of all aspects of ELT. However, there are some danger signs, perceived notably by Brumfit, that where the ‘communicative approach’ is concerned, stasis could well come about unless the obsession with syllabuses is leavened with a more immediate and sensitive concern for classroom techniques and events. The ‘humanistic/psychological approach’ is, on the other hand, principally methodologically orientated, but its own weakness is that it seems to underestimate the value of the syllabus as a device for assisting efficiency and, being in a sense ‘anti-linguistics’, may fail to see the value of descriptive knowledge of language. No doubt the debate as to how ‘explicitly’ one should actually teach learners will continue for many years to come – indeed, it has always been a perennial issue – but the one safe prediction at the present time seems to be that some sort of synthesis, as foreseen by Stern and Brumfit, will take place between the ‘communicative approach’ and the ‘humanistic/psychological approach’, such that ‘communicative teaching’ may come to have a more similar meaning for everybody. But for more detailed predictions of directions for the 1980s, Alatis et al. (eds.) (1981) should serve as a good starting-point.

From Single Screen to YouTube: Tracking the Regional Blockbuster

2018 ◽  
Vol 9 (2) ◽  
pp. 233-250
Author(s):  
S. V. Srinivas ◽  
V. H. C. V. Megha Shyam ◽  
Raghav Nanduri ◽  
Vasundhara Singhal ◽  
Vishnu Dath R.
Keyword(s):  
Andhra Pradesh ◽  
Necessary Conditions ◽  
Primary Objective ◽  
Current Phase ◽  
Research Projects ◽  
Starting Point ◽  
Production Distribution ◽  
Recent Developments ◽  
The One ◽  
Ongoing Project

Recent developments related to production, distribution and viewing of movies point to the need for research projects that examine multiples sites and formats simultaneously. This article outlines an ongoing project whose primary objective is to track the migration of movies across geographical spaces as well as screens. Our starting point—the pretext rather—is the ‘regional blockbuster’ that is the name we have given to big budget productions made by Chennai- and Hyderabad-based film industries. The regional blockbuster, being an all-India form that circulates in multiple language versions, offers opportunities for comparisons across regions in India and also between theatrical and other spaces of movie consumption. In the current phase, the focus of our project is the transformation of single screen cinema halls on the one hand and dubbing on the other. These, we suggest are among the necessary conditions for the emergence of the blockbuster. We present here the initial findings of fieldwork carried out by us simultaneously in Kerala, Andhra Pradesh, Telangana and Delhi.

Recent Developments in German Economic History

1958 ◽  
Vol 18 (4) ◽  
pp. 516-530 ◽  
Author(s):  
Fritz Redlich
Keyword(s):  
Cultural History ◽  
Social History ◽  
Economic History ◽  
Lecture Hall ◽  
Constitutional History ◽  
The Road ◽  
Starting Point ◽  
Classical Studies ◽  
Recent Developments ◽  
The One

In 1928 Hans Proesler, whom we shall meet in the course of this study, assumed the presidency, that is, became the Rector, of what can 1928 Hans Proesler, whom we shall meet in the course of thisbe described as the Niirnberg school of economics (Hochschule für Wirtschafts- und Sozialwissenschaften). The address he delivered on that occasion can properly serve as the starting point for my own presentation, for it dealt with German economic history, its development and problems. In his talk Proesler pointed out that it was the eighteenth-century enlightenment that opened the road to economic history by assigning to studies pointing in this direction a niche in the lecture hall of general cultural history. In Germany such men as Justus Möser, Gottfried Herder, and some members of the then-famous Göttingen school of historians, Schlözer, Gatterer, Heeren, von Anton, and Fischer, are considered by the historian of economic and social history as having stood at the cradle. Although German Romanticism had done much for historiography in general, its role for economic history was very limited. Romanticist historians were not primarily interested in things economic, although in the frame of legal and constitutional history on the one hand, and in connection with classical studies on the other, scholars of that period and the decades following made contributions to this field of knowledge. I might mention Savigny, Eich-horn, Waitz, Böckh, Otfried Müller, Mommsen; and a few minor figures, such as Hüllmann and Hannssen, even devoted themselves to special problems in the area, that is, financial and agrarian history, respectively. Georg von Below, the renowned German historian, treating Proesler's topic a few years before the latter, emphasized the contribution of the Prussian archivist, Georg Wilhelm von Raumer (1806-1856). Not only did the latter take an interest in matters economic but his ideas even tended toward what we would today call a materialistic interpretation of history.

Spontaneous Cataract in Nude Athymic Mice

1977 ◽  
Vol 35 ◽  
pp. 512-513
Author(s):  
Ronald H. Bradley ◽  
R. S. Berk ◽  
L. D. Hazlett
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Nude Mouse ◽  
Cellular Immunity ◽  
Phosphate Buffer ◽  
Osmium Tetroxide ◽  
Athymic Mice ◽  
Transmission Microscopy ◽  
Mouse Lens ◽  
Scanning Electron

The nude mouse is a hairless mutant (homozygous for the mutation nude, nu/nu), which is born lacking a thymus and possesses a severe defect in cellular immunity. Spontaneous unilateral cataractous lesions were noted (during ocular examination using a stereomicroscope at 40X) in 14 of a series of 60 animals (20%). This transmission and scanning microscopic study characterizes the morphology of this cataract and contrasts these data with normal nude mouse lens.All animals were sacrificed by an ether overdose. Eyes were enucleated and immersed in a mixed fixative (1% osmium tetroxide and 6% glutaraldehyde in Sorenson's phosphate buffer pH 7.4 at 0-4°C) for 3 hours, dehydrated in graded ethanols and embedded in Epon-Araldite for transmission microscopy. Specimens for scanning electron microscopy were fixed similarly, dehydrated in graded ethanols, then to graded changes of Freon 113 and ethanol to 100% Freon 113 and critically point dried in a Bomar critical point dryer using Freon 13 as the transition fluid.

Scanning and Transmission Microscopy of Nematocyst Batteries in Epitheliomuscular Cells of Hydra

1971 ◽  
Vol 29 ◽  
pp. 410-411 ◽  
Author(s):  
Jane A. Westfall ◽  
S. Yamataka ◽  
Paul D. Enos
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Osmium Tetroxide ◽  
External Surface ◽  
Three Dimensional ◽  
Surface Structures ◽  
Transmission Microscopy ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Scanning Electron

Scanning electron microscopy (SEM) provides three dimensional details of external surface structures and supplements ultrastructural information provided by transmission electron microscopy (TEM). Animals composed of watery jellylike tissues such as hydras and other coelenterates have not been considered suitable for SEM studies because of the difficulty in preserving such organisms in a normal state. This study demonstrates 1) the successful use of SEM on such tissue, and 2) the unique arrangement of batteries of nematocysts within large epitheliomuscular cells on tentacles of Hydra littoralis.Whole specimens of Hydra were prepared for SEM (Figs. 1 and 2) by the fix, freeze-dry, coat technique of Small and Màrszalek. The specimens were fixed in osmium tetroxide and mercuric chloride, freeze-dried in vacuo on a prechilled 1 Kg brass block, and coated with gold-palladium. Tissues for TEM (Figs. 3 and 4) were fixed in glutaraldehyde followed by osmium tetroxide. Scanning micrographs were taken on a Cambridge Stereoscan Mark II A microscope at 10 KV and transmission micrographs were taken on an RCA EMU 3G microscope (Fig. 3) or on a Hitachi HU 11B microscope (Fig. 4).

Nucleation of Disorder in Fe3Al Alloys

1967 ◽  
Vol 25 ◽  
pp. 312-313
Author(s):  
P. R. Swann ◽  
W. R. Duff ◽  
R. M. Fisher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Temperature ◽  
Antiphase Domain ◽  
Effect Of Temperature ◽  
Domain Structures ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Higher Temperature ◽  
The One

Recently we have investigated the phase equilibria and antiphase domain structures of Fe-Al alloys containing from 18 to 50 at.% Al by transmission electron microscopy and Mössbauer techniques. This study has revealed that none of the published phase diagrams are correct, although the one proposed by Rimlinger agrees most closely with our results to be published separately. In this paper observations by transmission electron microscopy relating to the nucleation of disorder in Fe-24% Al will be described. Figure 1 shows the structure after heating this alloy to 776.6°C and quenching. The white areas are B2 micro-domains corresponding to regions of disorder which form at the annealing temperature and re-order during the quench. By examining specimens heated in a temperature gradient of 2°C/cm it is possible to determine the effect of temperature on the disordering reaction very precisely. It was found that disorder begins at existing antiphase domain boundaries but that at a slightly higher temperature (1°C) it also occurs by homogeneous nucleation within the domains. A small (∼ .01°C) further increase in temperature caused these micro-domains to completely fill the specimen.

Effect of Acetone and Kerosene on Skin Ultrastructure

1972 ◽  
Vol 30 ◽  
pp. 92-93
Author(s):  
A. P. Lupulescu ◽  
H. Pinkus ◽  
D. J. Birmingham
Keyword(s):  
Electron Microscopy ◽  
Human Skin ◽  
Osmium Tetroxide ◽  
Human Epidermis ◽  
Ultrastructural Changes ◽  
Chemical Agents ◽  
Skin Ultrastructure ◽  
Volar Surface

Our laboratory is engaged in the study of the effect of different chemical agents on human skin, using electron microscopy. Previous investigations revealed that topical use of a strong alkali (NaOH 1N) or acid (HCl 1N), induces ultrastructural changes in the upper layers of human epidermis. In the current experiments, acetone and kerosene, which are primarily lipid solvents, were topically used on the volar surface of the forearm of Caucasian and Negro volunteers. Skin specimens were bioptically removed after 90 min. exposure and 72. hours later, fixed in 3% buffered glutaraldehyde, postfixed in 1% phosphate osmium tetroxide, then flat embedded in Epon.

The Current Situation in Chemical Stabilization of Biological Materials

1972 ◽  
Vol 30 ◽  
pp. 132-133
Author(s):  
John H. Luft
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Osmium Tetroxide ◽  
Molecular Level ◽  
Cross Linking ◽  
Chemical Stabilization ◽  
Specimen Preparation ◽  
Sufficient Condition ◽  
Radio Telescopes

With information processing devices such as radio telescopes, microscopes or hi-fi systems, the quality of the output often is limited by distortion or noise introduced at the input stage of the device. This analogy can be extended usefully to specimen preparation for the electron microscope; fixation, which initiates the processing sequence, is the single most important step and, unfortunately, is the least well understood. Although there is an abundance of fixation mixtures recommended in the light microscopy literature, osmium tetroxide and glutaraldehyde are favored for electron microscopy. These fixatives react vigorously with proteins at the molecular level. There is clear evidence for the cross-linking of proteins both by osmium tetroxide and glutaraldehyde and cross-linking may be a necessary if not sufficient condition to define fixatives as a class.

Application of ruthenium red/osmium tetroxide to bacteria, plant and animal tissue

1986 ◽  
Vol 44 ◽  
pp. 54-55
Author(s):  
R. L. Grayson ◽  
N. A. Rechcigl
Keyword(s):  
Electron Microscopy ◽  
Electron Density ◽  
Osmium Tetroxide ◽  
Biological Materials ◽  
Ruthenium Red ◽  
Animal Tissue

Ruthenium red (RR), an inorganic dye was found to be useful in electron microscopy where it can combine with osmium tetroxide (OsO4) to form a complex with attraction toward anionic substances. Although Martinez-Palomo et al. (1969) were one of the first investigators to use RR together with OsO4, our computor search has shown few applications of this combination in the intervening years. The purpose of this paper is to report the results of our investigations utilizing the RR/OsO4 combination to add electron density to various biological materials. The possible mechanisms by which this may come about has been well reviewed by previous investigators (1,3a,3b,4).

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