Confocal scanning light microscopy of the Escherichia coli nucleoid: comparison with phase-contrast and electron microscope images.

The nucleoid of living and OsO4- or glutaraldehyde-fixed cells of Escherichia coli strains was studied with a phase-contrast microscope, a confocal scanning light microscope, and an electron microscope. The trustworthiness of the images obtained with the confocal scanning light microscope was investigated by comparison with phase-contrast micrographs and reconstructions based on serially sectioned material of DNA-containing and DNA-less cells. This comparison showed higher resolution of the confocal scanning light microscope as compared with the phase-contrast microscope, and agreement with results obtained with the electron microscope. The effects of fixation on the structure of the nucleoid were studied in E. coli B/r H266. Confocal scanning light micrographs and electron microscopic reconstructions showed that the shape of the nucleoid remained similar after OsO4 or glutaraldehyde fixation; however, the OsO4 nucleoid appeared to be somewhat smaller and more centralized within the cell.     

Electron microscopy of basophilic structures of some invertebrate oocytes. II. Fine structure of the yolk nuclei

RNA containing yolk nuclei from the surf clam Spisula solidissima have been studied with the light microscope and with the electron microscope. A variety of structures can be seen with both and a correlation can be made between bodies studied with the electron microscope and those studied with the light microscope. The electron microscope shows many of these structures to be composed of double walled lamellae arranged in space, in various ways. The variety of patterns seen with the electron microscope can be satisfactorily explained on the basis of a hypothetical model. The presence of yolk platelets within the yolk nuclei lends support to classical observations on the synthesis of yolk within yolk nuclei or yolk nuclei derivatives. Small granules (about 100 A) are included within the double walled lamellae and their presence probably accounts for the basophilic nature of the entire body. The presence of small granules attached to electron-dense layers relates the yolk nuclei described here to ergastoplasm discussed by others.     

A Quantitative Estimation of the Uptake of Two New Electron Stains by the Cytoplasmic Membrane of Ram Sperm

From microdensitometer measurements on electron micrographs of sectioned sperm heads it has been found that the electron stains, triiodobenzoyl chloride, and triiodophenylisocyanate, increase the image contrast of the cell membrane above its immediate background by about 40 per cent and 70 per cent respectively, while the nucleus remains unstained. Assumptions based on current electron scattering theory have been used to deduce the uptake by weight of the stains in terms of the density of the nucleus, which was estimated from complementary measurements made with the interference microscope and electron microscope. The uptake of the stains was found to be about 7 per cent and 12 per cent by weight respectively. It is suggested that the method used in this work could be applied generally for the density measurement of cell structures unresolved by the light microscope.     

A cytological study of the albuminsecreting cells of the hen oviduct

1. The electron and light microscope have been employed in a cytological study of the albumin-secreting cells of the hen oviduct and of fractions of this tissue obtained after homogenization and differential centrifugation. 2. These studies confirm the observation that in this tissue material corresponding to liver "microsomes" in amino acid-incorporating ability and ribonucleic acid content sediments in relatively low centrifugal fields. 3. The electron microscope studies suggest that the protein secretion of the gland is formed in intimate association with the ergastoplasm.     

Structure and secretion of the carapace in some living ostracodes

The carapaces of some living freshwater and brackish-water ostracode species have been studied by means of light microscope, scanning electron microscope. transmission electron microscope, electron probe analyzer and X-ray diffractometer, with emphasis placed on the 'pigment' granules. The granules were found to consist of calcite and apatitic calcium orthophosphate. They are located within the epidermis, as a layer which is attached to the internal side of the calcite layer. It is suggested that the main function of the granules is the construction of the new calcareous valve in the moulting process. The layer of granules probably recrystallizes to form the calcite crystals of the valves.     

Fine Structural Studies on the Pycnidiospores of Botryodiplodia theobromae Pat.

The structure of the pycnidiospores of B. theobromae was investigatedby a combination of light microscope, a scanning electron microscopeand a transmission electron microscope observations. As observedwith the light microscope the hyaline non-septate pycnidiosporeis highly vesiculated while the pigmented septate one exhibitslongitudinal hyaline striations. Investigations with the scanningelectron microscope showed the hyaline non-septate pycnidiosporeto be smooth-walled without any form of ornamentation. The pigmentedseptate pycnidiospore on the other hand had a rough outer surfacewith a transverse groove, which probably indicated the positionof the septum. The longitudinal striations seen on such pycnidiosporeswith the light microscope were not observed under these conditions.Observations with the transmission electron microscope showedthat the outermost layer of the hyaline pycnidiospore was smootherthan that of the pigmented one. The pigment was on the outerlayer of the double-layered wall of the pigmented pycnidiospore.The inner non-pigmented wall layer was continuous with the septum.The septum tapered gradually to a thin layer in the centre whereit was perforated by a simple pore. The observations indicatedthat the pigmented spore was multinucleate while the hyalineone was uninucleate.     

臭氧对灵芝菌丝杀灭作用的研究

以灵芝菌丝为研究对象,测定了臭氧发生器放电时间、臭氧浓度、灵芝菌丝致死率之间的曲线关系。结果表明,随着放电时问延长,臭氧浓度变大,致死率明显上升,到一定时间后趋缓,在生物显微镜下认真观察了正常菌丝和被破坏菌丝形态上的差别,在透射电子显微镜下观察了菌丝的外观结构,用激光共聚焦扫描显微镜观察了菌丝破坏前后及吖啶橙染色与不染色的形态结构,经低真空扫描电镜、原子力显微镜观察了臭氧处理前后灵芝菌丝细胞的变化情况。     

Thirty years of the electron microscope investigation in zoology and parasitology in the Zoological Institute of the Russian Academy of Sciences

The history of the electron microscope investigations in zoology and parasitology in the Zoological Institute of the Russian Academy of Sciences and progress in scanning and transmission electron microscope investigations in this field of biology to the moment are briefly accounted.     

Improvement of the morphometry method and its use in electron microscopic studies

The paper describes morphometric device for electron microscope. Using this gauge one can get morphometric data from the screen of the electron microscope. Perspectives of morphometric analysis of ultra-structures in the electron microscope are discussed.     

Identification of a potential artifact in the use of electron microscope autoradiography to localize saturated phospholipids in cells

The suitability of electron microscope autoradiography for sutdying the uptake and intracellular localization of lipid vesicles (liposomes) containing radiolabeled saturated phospholipids has been examined. Data are presented showing that preparation of specimens for electron microscope autoradiography by conventional methods is accompanied by significant translocation and intercellular redistribution of radiolabeled saturated lipids, causing spurious labeling patterns. Intercellular redistribution of radiolabeled lipid was demonstrated by mixing glutaraldehyde-fixed mous L1210 cells that had been incubated with sonicated lipid vesicles containing [H] dipalmitoyl phosphatidylcholine with an indicator cell population (fixed avian erythrocytes) which had not been exposed to vesicles and showing that after electron microscope processing radiolabeled grains were present in both cell types. The same redistribution artifact also probably affects the intracellular localization of radiolabeled lipids. This artifact is discussed in relation to previous work in which autoradiographic methods have been used for ultrastructural localization saturated phospholipids in cells and tissues.     

Combined light and electron microscope immunocytochemical localization of scattered peptidergic neurons in the central nervous system

A pre-embedding immunocytochemical technique is described for combined light and electron microscope study of peptidergic neurons in the central nervous system. The protocol is especially designed to overcome the sampling problems inherent in electron microscope study of structures, such as luteinizing hormone-releasing hormone (LHRH) neurons, that are scattered individually across large brain regions. The fixation methods outlined for several mammalian species include immersion and vascular perfusion with acrolein. Fine-structural preservation and LHRH immunoreactivity obtained with this fixative are compared to results with more conventional fixatives. Vibratome sectioning and a "pretreatment" regime, which prepare the tissues for immunocytochemistry, are described. Immunocytochemical labeling is done with free-floating sections and the peroxidase-antiperoxidase unlabeled antibody enzyme technique. Techniques are also described for the subsequent processing of immunoreacted sections for electron microscopy. These methods ensure that the processed sections are readily scanned by light microscopy, so that regions containing immunoreactive structures can be specifically chosen for electron microscope analysis. Sample electron micrographs are shown that illustrate some fine structural features of LHRH neurons in rats, bats, ferrets, and monkeys, as revealed with the techniques described.     

Atomic force microscopy study of the collagen fibre structure

Observations of intact reconstituted and native collagen fibres were performed with the atomic force microscope. The results are compared between the two types of fibres and with those obtained previously with the electron microscope on freeze-etched or negative stained samples. Some of the findings presented here indicate that the specimens observed in air with the atomic force microscope were still in a hydrated state.     

黑龙江产十种蕨类植物孢子囊和叶表皮的扫描电镜观察

用扫描电镜对黑龙江产十种不同科属、不同生境的蕨类植物的孢子囊和叶表皮进行了详细观察,结果显示:蕨类植物的孢子囊和叶表皮在扫描电镜下,显示出更为丰富的形态特征,并表现出细致而稳定的异同点,可作为蕨类系统分类的现代手段,能更好的应用于疑难科属的分类研究;十种蕨类植物也都表现出其形态结构与生态生理的高度一致性.     

Pollen morphology of the alangiaceae

This paper presents a pollen-morphological study of Alangium, a genus mainly restricted to the tropics of the Old World, of which 18 of the 19 known species were studied. The pollen grains, studied with the use of a light microscope, a transmission electron microscope and a scanning electron microscope, were classified into 15 pollen types, to which a key is given. Comparison of fossil and recent grains produced some information about both the evolutionary trends in the characters of the pollen grains and the phytogeography of Alangium.     

On the structure and function of the mouthparts of the soil-inhabiting collembolan Folsomia Candida

The fine structure of the mouthparts of the collembolan Folsomia Candida is described, largely on the basis of a study with the scanning electron microscope. The structure of the maxilla and of die mandibular molar plate is clarified and its interpretation corrected. The grinding function, usually attributed to the collembolan molar plate is disputed. This possible change in function of the mouthparts may also mean that these insects play a slightly different role than hitherto believed in the breakdown of the litter and humus in the soil.
An alternative method to replace freeze-drying in the preparation of Collembola, and possibly other small arthropods for scanning electron microscope studies is described.     

A post-embedding avidin-biotin peroxidase system to demonstrate the light and electron microscopic localization of lectin binding sites in rat kidney tubules

Summary A post-embedding method for the light and electron microscopic demonstration of lectin binding sites in rat kidney tubules is described. The use of biotinylated lectins, followed by treatment with avidin peroxidase and the DAB—H₂O₂ sequence, produced intense staining of acrylic sections at the electron microscope level: brush borders and associated structures, cytoplasmic granules, basal infoldings and basement membrane—plasmalemmal interfaces of proximal tubules bound erythrophytohaemagglutinin, while distal tubules were mainly unstained. At the light microscope level, epoxy resin sections showed a similar staining pattern after etching, as did acrylic resin sections after intensification of the final reaction product. The binding of wheatgerm agglutinin to cytoplasmic granules and brush border structures in the proximal tubules was abolished, at both the light and electron microscope levels, by the competing sugar tri-N—acetylchitotriose. Epoxy resin ultrathin sections required etching before staining was achieved in the electron microscope, and results were far inferior to those obtained with acrylic resin. This method allows rapid and inexpensive screening of large numbers of lectins, if required, at both the light and electron microscope levels, using reagents that are stable for long periods of time.     

Identification of a potential artifact in the use of electron microscope autoradiography to localize saturated phospholipids in cells

The suitability of electron microscope autoradiography for studying the uptake and intracellular localization of lipid vesicles (liposomes) containing radiolabeled saturated phospholipids has been examined. Data are presented showing that preparation of specimens for electron microscope autoradiography by conventional methods is accompanied by significant translocation and intercellular redistribution of radiolabeled saturated lipids, causing spurious labeling patterns. Intercellular redistribution of radiolabeled lipid was demonstrated by mixing glutaraldehyde-fixed mouse L1210 cells that had been incubated with sonicated lipid vesicles containing [³H]dipalmitoyl phosphatidylcholine with an indicator cell population (fixed avian erythrocytes) which had not been exposed to vesicles and showing that after electron microscope processing radiolabeled grains were present in both cell types. The same redistribution artifact also probably affects the intracellular localization of radiolabeled lipids. This artifact is discussed in relation to previous work in which autoradiographic methods have been used for ultrastructural localization of saturated phospholipids in cells and tissues.     

Immunogold labeling of organelles in the bioluminescent dinoflagellate Gonyaulax polyedra with anti-luciferase antibody

A polyclonal antibody directed against the luciferase of the luminous dinoflagellate Gonyaulax polyedra labels both dense vesicles and trichocyst sheaths, as visualized in the electron microscope after treatment of antibody-reacted sections with an immunogold probe. Because of their similar size, shape and localization, the dense vesicles seen with the electron microscope are postulated to correspond to autofluorescent particles seen with the fluorescent microscope, which are known to be the origin of bioluminescent flashes in this alga. The explanation for the trichocyst sheath-specific labeling is less evident. The possibility that a second antibody of different specificity is involved has not been excluded but seems unlikely. Alternatively, it could be due to a different but antigenically cross-reacting protein. But the possibility that luciferase itself occurs in two different organelles is intriguing and consistent with previous biochemical studies of cell extracts.     

An Alternative to the Flat Substrate Method of Preparing Electron Microscope Autoradiographs

Difficulty with flat substrate methods of preparing electron microscope autoradiographs has prompted reconsideration and refinement of a technique in which an electron microscope grid is placed beneath the specimen prior to dipping. This technique avoids the problems commonly associated with the direct application of emulsions to specimen grids, and should be considered as an alternative to flat substrate techniques when difficulty with these methods is encountered.