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Scanning electron microscopy was used to examine microorganisms on the skin of cows' teats which were artificially contaminated and subsequently stored for different times. From the results it seems that bacteria were not spread uniformly on the surface of the teats. No extra-cellular polymers were observed before storage of the teats, but during storage polymers, in the form of thin fibers, were produced. These fibers became thicker and finally resulted in slime. Multiplication of bacteria during storage involved formation of microcolonies of bacteria in which bacteria were not attached directly to the skin but to other bacteria. This explains the decrease in the differences between bacterial counts obtained by the blending and rinsing methods after long periods of storage.

A combination of scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXRA) was used in the study of soil materials. The investigation in situ of components in thin sections was used to estimate chemical elements with atomic numbers 11 upwards, from sodium on. EDXRA could detect chemical elements up to magnifications of X 10 000. The composition of amorphous and micro-crystalline materials cannot be estimated in thin sections by light microscopy but by this technique was clearly displayed. Composition of loose soil material can also be investigated. The material that could be studied by SEM-EDXRA did not need high polishing of the thin section, and the plastic used for impregnation of the soil material was not affected by the investigation.Identification of chemical elements in situ, high resolution of the topographic image and relatively short testing times for the elements make this combination of techniques useful for soil research. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Both transmission and scanning electron microscopy were utilised to follow fine structural changes in the pollen of pyrethrum in the last stages of sporogenesis and during pollination. The ripe pollen appears to be covered with a proteinaceous skin. The role of the skin is protective. The skin also is the first site of recognition in the pollen-stigma interaction.

Determination de la localisation et des concentrations en soufre et autres elements detectables par micro-PIXE dans les racines de Tagetes, l'accumulation locale de thiophenes etant liee a celle du soufre

A series of experiments have been performed for a number of years to obtain quantitative microchemical analysis by secondary ion microscopy of materials in thin sections of soils. The first successful quantification was obtained from an area with a diameter of 300 μm in bauxite and done with an IMS 300 at Philips Research Laboratories. Such an area, however, is frequently too large for most soil samples which are extremely heterogeneous even on a microscale. A second generation IMS 3F was tested for soils at the Cameca factory in Paris. This instrument allows the quantification of trace and major elements of soil constituents in a spot with 1.5 μm diameter, using a computer program developed by Philips Research Laboratories. Calcite and clay from a Petrocalcic Xerochrept were used for this test. Ion spectra, ion images and linear traverses were made giving information on the nature and distribution of both major and trace elements. The possibility of investigating a larger number of chemical elements simultaneously in linear traverses is of considerable help in the study of thin sections. Various submicroscopic and other techniques are discussed to give some insight into the position of ion microscopy amongst these.

Soil samples are usually non-conductive which leads to charging phenomena at their surfaces if microanalysis using electron beams is to be performed. During the last decade, however, various submicroscopic techniques have been developed which give acceptable accuracy of analysis of soil materials present on the surface of thin sections of soils. Laser analysis and electron- and ion microscopy were applied but AES (Auger electron spectroscopy) has, until recently, remained unsatisfactory due to charging phenomena. However, if a very thin section ( The use of a combination instrument allowed simultaneous AES and EDX (energy dispersive X-ray analysis) measurements on the same spot on a thin section. AES gave surface information whereas EDX gave information on the bulk (subsurface) of the soil material as well. A larger area was analysed with XPS (X-ray photoelectron spectroscopy) in the same instrument. AES measurements, also supplying information on the lighter elements, make this type of analysis interesting for studies of decomposition and impregnations of organic matter in soils and are also important for environmental research in situ.

In the hibernating (diapausing) Colorado potato beetle, Leptinotarsa decemlineata Say, the flight muscles show pronounced degeneration. The muscle fibrils are greatly reduced in diameter and the sarcosomes are virtually absent. Similar signs of degeneration could be produced by extirpation of the postcerebral complex of endocrine glands, the corpora cardiaca and corpora allata. Reimplantation of active postcerebral complexes resulted in a very rapid regeneration of the muscle fibrils and new formation of sarcosomes.

Electron micrographs show the presence of the polyhedral, the outer, and the inner membranes occurring in nuclear polyhedral bodies fromMalacosoma neustria, Barathra brassicae andAdoxophyes reticulana. The outer membranes appear to be composed of a central, bimolecular leaflet of lipids bounded on either side by carbohydrates and proteins. The polyhedral and inner membranes, however, seem to consist of protein only. The inner membranes are closely attached to the virus rods, and so are the polyhedral membranes to the polyhedral protein. De polyedermembranen vanMalacosoma neustria, Barathra brassicae enAdoxophyes reticulana, alsmede de buitenste en binnenste membranen om de deeltjes van deze kernpolyedervirussen, werden met de elektronenmicroscoop bestudeerd (fig. 1A-I, 2A-C). Om de polyeders te fixeren en ter verkrijging van bepaalde contrasten in ultra-dunne coupes werd van verschillende agentia gebruik gemaakt. Vergelijking van de verkregen foto's (fig. 2D-I, 3A-B) wijst uit, dat het buitenste membraan uit een bimoleculaire laag van lipiden bestaat, die aan beide zijden door koolhydraten en eiwitten zijn begrensd (fig. 4); de polyedermembranen (fig. 3B) bestaan evenals de binnenste membranen echter uitsluitend uit eiwitten. De virusstaafjes en de polyeders zijn respectievelijk door het binnenste membraan en door het polyedermembraan nauw omsloten.

The nuclear polyhedral bodies fromMalacosoma neustria are enclosed within a membrane. The diameter of the nuclear polyhedra varies from 0.9 to 2.8 μ with an average of 1.8 μ. In the nuclear polyhedra the rod-like virus particles occur both singly and in bundles. The single virus rods are enclosed within two membranes, namely the intimate membrane and the developmental membrane. The virus rods which occur in bundles have an intimate membrane just like the single virus rods, whereas the developmental membrane encloses the whole bundle. The virus rods are closely packed by the intimate membrane and between the intimate and the developmental membrane is a space. The diameter of the virus rods without membranes, determined from sectioned polyhedra, is about 25 mμ and the length 250 mμ.

The rostrum tip of Dysdercus spp. bears on each side 13 sensilla. They include 10 sensilla basiconica, innervated by 3-5 neurons, one small sensillum basiconicum (innervated by two dendrites), one sensillum basiconicum with a sharp tip (innervated by three neurons) and one sensillum trichodeum (innervated by two neurons). The microstructure of the sensilla basconica indicates a contact chemoreceptive function; this conclusion is supported by preliminary electrophysiological evidence.

Experiments with a LAMMA-500 instrument were performed in order to test whether or not thin sections of soils with a thickness of more than 15 Μm could be analysed with this instrument. Although the usual thickness of the specimens for this instrument lies between 0.1–1 Μm, it was possible to analyse such thick sections by application of laser milling in which the laser beam was aimed at grazing incidence onto the edge of the section. In this way a path was cleared through the section by erosion and the material that sputtered away along this path could be analysed.

Carnations were treated with a silver thiosulphate complex to prevent wilting of the flowers. The ultrastructural localization of silver and sulphur in the receptacle tissue was investigated by electron microscopy. Electron-dense deposits were present in the receptacle tissue. Coarse-grained deposts (diam. 60–100 nm) were predominantly observed at the inner side of the cell wall, whereas fine-grained deposits (diam. 20–60 nm) were predominantly present inside the cell-wall region and in the intercellular spaces. These particles were analyzed for chemical elements by X-ray analytical electron microscopy (Philips EM 400 plus Edax energy dispersive analyzer, type 711). In both types of deposits, the presence of silver and sulphur was verified. Point analysis revealed that in both precipitates the S/Ag ratio was of the same order.

Organic matter, minerals and iron-manganese nodules were studied in thin sections of soils with an electron microprobe analyzer (EMA) and a combination of a scanning electron microscope (SEM) and an energy-dispersive X-ray analyzer (EDXRA). Both instruments were used to estimate the presence and nature of chemical elements in two selected areas, one containing a combination of organic and mineral material and another inside an iron-manganese nodule. The detection of organic matter proved problematic. Of the light elements, N could not be detected with EMA and O was detected but was not specific to organic matter. EMA could not be used for C because of the C coating of the thin section. SEM-EDXRA only detected heavier elements. EMA produced somewhat better X-ray images of heavier elements, especially from an iron-manganese nodule. However, with organic material, SEM-EDXRA X-ray images were similar to or slightly better than EMA. An advantage of SEM-EDXRA over EMA is that the soil material can be analysed at various magnifications with a much higher limit, and point analysis can be made of loose material. For soil material, SEM-EDXRA was better as a routine instrument which solved most problems. EMA can be used as a complementary instrument. Other microanalytical techniques such as the ion microprobe mass analyzer (IMMA) were necessary to analyse light elements in organic material of soils. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Components from thin sections of soils developed on weathered granite were analysed with the Laser Microprobe Mass Analyzer. Fragments of thin sections were mounted on sandwich grids, and perforated with the laser from the edges inwards (laser milling), using the laser light at grazing incidence. Laser-induced mass spectra of secondary titanium compounds and other constituents in the weathered granite were obtained in this manner. Positive and negative laser desorption mass spectra were recorded with such a speed and accuracy that in spite of the relatively large volume of analysed materials, minute changes in composition could be detected over very short distances. This allowed total chemical element analysis of spots in which titanium compounds concentrated during weathering, giving information on changes in purity of amorphous and semi-crystalline materials at such sites. Characteristic analysis possibilities of the Ion Microprobe Mass Analyzer (IMMA), Laser Microspectral Analyzer (LMA) and Laser Microprobe Mass Analyzer (LAMMA 500) are compared. (Abstract retrieved from CAB Abstracts by CABI’s permission)

The fine structure and growth of two gram-negative and two gram-positive strains of sheathed bacteria, isolated from activated sludge, have been studied. Their anatomy is quite different from Sphaerotilus natans. The cells are rectangular, tightly joined together, non-motile and enclosed by a sheath which is thin in the gram-negative strains and rather electron-dense in the two larger gram positive strains. The four strains grow slowly and form pink filamentous flocs in liquid media.