Life Sciences Commons^™

Cytology Of Pollutant Metals In Marine Invertebrates: A Review Of Microanalytical Applications, J. A. Nott

Scanning Microscopy

X-ray microanalysis (XRMA) is customized for investigations of the metabolic and detoxification strategies of heavy metals taken by marine organisms from polluted environments. Sites of uptake, intracellular accumulation, transport and excretion are visualized, analysed and quantified . Cryopreparation techniques are required to prevent the translocation or loss from specimens of soluble metal species.

In marine invertebrates, metals are detoxified by systems of chemical binding and intracellular compartmentalization. XRMA investigations have concentrated on marine molluscs and crustaceans and even within these restricted groups there are marked inter-species differences in the biochemical and cytological processes which reduce metal bioavailability. Some detoxification systems …

Development And Use Of A Pneumoconiosis Database Of Human Pulmonary Inorganic Particulate Burden In Over 400 Lungs, Jerrold L. Abraham, Bryan R. Burnett, Andrew Hunt

Scanning Microscopy

Over 400 cases with data from in situ electron microprobe quantitation of non-fibrous inorganic particles (e.g., silica, alumino-silicates, talc, metals) in pulmonary tissue sections, and data from quantitative digestion analyses for fiber content (e.g., asbestos, silica, alumino-silicates, man-made fibers, talc) comprise an extensive microcomputer data set of lung particle burden. When allied with demographic and histopathologic information the result is a comprehensive database of occupational pulmonary pathology. Examples of the kinds of information which can be extracted from the database include: 1) summary information on the types sizes and associations of particles in lungs with a variety of exposures, 2) …

Diapause In The Earthworm, Aporrectodea Longa: Morphological And Quantitative X-Ray Microanalysis Of Cryosectioned Chloragogenous Tissue, A. J. Morgan, C. Winters

Scanning Microscopy

The earthworm, Aporrectodea longa, which experiences an apparent obligatory physiological resting state (“diapause”) in the temperate Summer, was collected monthly from February through to October. Morphological examination of the chloragocytes, and quantitative electron probe X-ray microanalysis of their constituent chloragosome granules prepared by cryoultramicrotomy and air-dried/smearing, were undertaken over this period. Worms entered diapause in May, and emerged from it between August and September. The long-term energy stores in the form of lipid, in addition to the more usual polysaccharide (glycogen) reserves, were accumulated by early diapause; the lipid was gradually consumed during diapause. In addition, the structure and composition …

Changes In Sodium Concentration In Cardiac Myocytes From Diabetic Rats, Alice Warley

Scanning Microscopy

The effects of streptozotocin induced diabetes on rats were studied. The animals showed an increase in blood glucose concentration and a loss of weight from both the body and the heart. Loss of weight from the heart was less severe leading to an increased heart to body weight ratio. Study of element concentrations by X-ray microanalysis showed that there was an increase in intracellular Na concentration in cardiac myocytes from the diabetic animals, but no change in Mg. These results agree with studies which show changes in Na/K ATPase after the onset of diabetes.

X-Ray Microanalytical Studies Of Freshwater Biota: Changes In The Elemental Composition Of Anabaena Spiroides During Blooms Of 1988 And 1989, S. Clay, D. C. Sigee, E. Bellinger

Scanning Microscopy

Samples of Anabaena spiroides were collected from a eutrophic freshwater lake (Rostherne Mere, Cheshire) during the bloom periods of 1988 and 1989, and analysed by SEM electron probe X-ray microanalysis. Vegetative cells, akinetes and heterocysts consistently had clear peaks of Mg, Si, P, S, Cl, Kand Ca.

In comparison to vegetative cells, akinetes had generally higher elemental mass fractions (particularly K and P) while heterocysts had significantly lower levels of Mg, P, and Ca.

For both years, elemental mass fractions in vegetative cells showed significant changes during the course of the bloom, but these were not consistent from one year …

The Hall Method In The Quantitative X-Ray Microanalysis Of Biological Specimens: A Review, Godfried M. Roomans

Scanning Microscopy

In the two decades since its inception by T.A. Hall, the continuum theory of quantification has become the general method for quantitative analysis of biological specimens. Although the method was originally developed for thin specimens, its use has been extended to thicker specimens, and it has also been used in quantitative determinations of local water content. The single most important difficulty in the application of the "Hall method" is the accurate calculation of the extraneous continuum, i.e., the continuum due to non-specimen sources. The different variations in methods for quantitative analysis of local water content are critically compared and a …

A Low Temperature Vacuum Embedding Procedure For X-Ray Microanalysis Of Biological Specimens At Subcellular Level, Romuald Wroblewski, Joanna Wroblewski, Sven-Olof Wikström, Matti Anniko

Scanning Microscopy

The validity of freeze-drying and low temperature embedding in Lowicryl resins has been investigated in studies of ion distribution in mouse embryological inner ear, rat rib growth plate, liver and submandibular gland. The morphological preservation of the tissues was adequate for the identification of different intracellular compartments and extracellular structures. It was also possible to analyze extracellular fluids in the vestibular part of the developing inner ear. Compared with thin cryosections, Lowicryl sections are easier to produce and are more stable during analysis. Freeze-dried embedded material can be easily reorientated during cutting and adjacent sections can be used for other …

From Hela Cell Division To Infectious Diarrhoea, J. Stephen, M. P. Osborne, A. J. Spencer, A. Warley

Scanning Microscopy

Hela 83 cells were grown in suspension both randomly and, synchronously using hydroxyurea which blocks cells at the Gl/8 interface. Cryosections were prepared, freeze-dried and analyzed by X-ray microanalysis. As cells moved into S and through M phases [Na] and [Cl] increased; both returned to normal levels upon re-entering Gl phase. The Na/K ratio was 1:1 in Gl phase. Infection of HeLa 83 cells in Gl phase with vaccinia virus resulted in no change in intracellular [Na].

Infection of neonatal mice with murine rotavirus was localized to villus tip enterocytes and gave rise to diarrhoea which was maximal at 72h …

Intracellular Penetration And Accumulation Of Radiographic Contrast Media In The Rat Kidney, A. Nordby, K. E. Tvedt, J. Halgunset, O. A. Haugen

Scanning Microscopy

Radiographic iodine-containing contrast media (meglumine calcium metrizoate, iohexol and meglumine sodium ioxaglate) were injected intravenously in rats. At various intervals after exposure, in situ cryofixation of kidneys was performed. Thin, freeze-dried cryosections were examined by electron microscopy and X-ray microanalysis. In endothelial cells, erythrocytes and tubular cells high dry weight concentrations of iodine were found. Twenty-four hours after iohexol was injected, no trace of iodine was found in the plasma, microvilli or the nuclei of the tubular cells. Small organelle-like compartments in the cytoplasm of the proximal tubular cells contained high concentrations of iodine, whereas no iodine was found in …

Studies Of Epithelial Electrolyte Transport By Marker Ions, A. Dörge, R. Rick

Scanning Microscopy

The paper reviews several recent studies in which marker ions, such as Rb and Br, were used to identify ion transport pathways and membrane properties in epithelia. In the frog skin epithelium, using Rb as a substitute for K, Cl transport mechanisms across the basolateral membranes of principal cells were studied. The data suggest that intracellular Cl is maintained above electrochemical equilibrium by an Na-K-2Cl cotransport system which, under non-stimulated conditions, is normally quiescent.

In toad and frog skins, the route of transepithelial Cl movement was investigated. A subpopulation of mitochondria-rich cells demonstrated a ready exchange of Br with the …

Identification And Characterization Of Cocoa Solids And Milk Proteins In Chocolate Using X-Ray Microanalysis, B. E. Brooker

Food Structure

X-ray microanalysis was used to compare the elemental composition of isolated cocoa solids with milk powder. Whereas mllk powder contained similar high levels of calcium and potassium, cocoa sol ids were rich in potassium but contained very small amounts of calcium.

This difference in elemental composition allowed the two populations of particles to be distinguished in digital X-ray maps of frozen and fractured samples of plain , milk and white chocolates examined by cryo-scanning electron microscopy. The size distributions of particles imaged in this way were determined using standard software and were used to distinguish between two white chocolates whose …