Occurrence of manganese-rich inclusions in the root cortex of white clover

Walker, Graham D.

doi:10.1080/0028825x.1979.10425154

Cited by 7 publications

(2 citation statements)

References 4 publications

(5 reference statements)

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“…37 The greater concentration of iron, manganese, cadmium, aluminium and nickel in grass compared with clover (Table 1) may derive from the reduced competitiveness of clover in grass±clover mixtures, which is due primarily to its uncompetitive root morphology. 38 This has been reported previously for manganese, 35,39±41 which is present in large quantities in the root cortex of white clover, 42 from where it is unlikely to be translocated as much as in grass. Whitehead et al 40 reported a slightly greater iron content in clover than in grass, which is not supported by this experiment.…”

Section: Herbagesupporting

confidence: 51%

Effects of sodium fertiliser on the distribution of trace elements, toxic metals and water-soluble carbohydrates in grass and clover fractions

Chiy

Phillips

1999

J. Sci. Food Agric.

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Section: Herbagesupporting

confidence: 51%

Effects of sodium fertiliser on the distribution of trace elements, toxic metals and water-soluble carbohydrates in grass and clover fractions

Chiy

Phillips

1999

J. Sci. Food Agric.

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“…Studies of inclusions include those by Walker & Powell ( I 979) on the phosphorus content of mycorrhizas, and Walker (1979) on the sequestration of toxic manganese in clover roots, both using freeze-fractured bulk material. Roomans ( I 980) used freeze-dried ultrathin sections of yeast cells suspended in gelatin and quench-frozen in nitrogen slush, for a scanning transmission electron microscope study of the phosphate-rich granules.…”

Section: (4) Plant Cellsmentioning

confidence: 99%

Electron‐probe X‐ray Microanalysis: Techniques and Recent Applications in Biology

Moreton¹

1981

Biological Reviews

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Summary (1) X‐ray microanalysis is a powerful technique, allowing the quantitative measurement of many elements of physiological interest, at physiological concentrations and with a spatial resolution typically of a few micrometres in bulk specimens, and a few hundred nanometres in thin sections. (2) The basic requirements are a focussed, high‐energy electron beam, X‐ray spectrometers and a means of visualizing the specimen. These facilities are found in a number of different types of commercial microanalysers, which may be based on either the transmission electron microscope, or the scanning electron microscope. Scanning microanalysers offer a lower image resolution, but are considerably more versatile than instruments based on the transmission electron microscope. (3) Preparing the specimen in a form that will withstand electron bombardment under high vacuum, and yet in which the elements to be analysed are retained in their original locations, is clearly the most critical step. For analysing diffusible elements, especially water‐soluble electrolytes, the only reliable method is to freeze as rapidly as possible, and analyse the tissue without any chemical treatment. (4) The best results are obtained if frozen sections are cut and analysed on a cold‐stage with their water content retained as ice. Procedures have been worked out for doing this, and for quantitative interpretation of the results, so that original tissue concentrations of the common electrolytes, phosphorus, sulphur and other elements of interest can now be measured with confidence. The original water‐content of different cell and tissue compartments can also be estimated from the mass‐loss on drying. (5) A simpler alternative is to freeze‐dry the frozen sections before analysis. The distribution of diffusible elements is probably not too much disturbed, spatial resolution is improved, and the visual image becomes much clearer, but quantitation is made more difficult and less reliable. Nevertheless this technique is frequently used. (6) For precipitated materials and for fluid samples, much simpler methods of preparation can be used. (7) The technique is the subject of a large and rapidly expanding literature, and is providing new information on the sub‐cellular distribution of electrolytes and other elements in many different tissues from animals and plants. (8) Some of the earliest applications to the study of diffusible ions were in the analysis of micropuncture samples from kidney tubules, where it has been possible to analyse many very small samples, and for several elements at once. Some preliminary information has also been obtained on the intracellular ion concentrations in kidneys subjected to different physiological conditions. (9) A particularly successful field has been the study of transporting epithelia, including vertebrate and insect digestive and excretory tissues, where the distribution of ions along the intercellular spaces has been shown not to agree with that predicted from the ‘standing gradient’ theory of osmotic coupling. Th...

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