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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Ultramicroscopy 19 (1986), S. 80 
    ISSN: 0304-3991
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Natural Sciences in General , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0248-4900
    Keywords: freeze-fracturing ; high pressure freezing ; membrane-associated structures ; rust fungi ; secretion processes
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 105 (1975), S. 193-199 
    ISSN: 1432-072X
    Keywords: Bean ; Rust ; Haustorium ; Sheath ; Autoradiography ; Infection ; Electron microscopy ; Phaseolus vulgaris ; Uromyces phaseoli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tritium labeled uredospores of Uromyces phaseoli were produced be feeding the host, Phaseolus vulgaris, with 3H-orotic acid. These spores were allowed to germinate on and to penetrate into a bean leaf. 24 hrs after inoculation, the bean rust had formed the first haustorium. All fungal structures, including the fungus walls, were heavily labeled. No label could be detected in the cells that had come into contact with the hyphae. In the infected host cell, the haustorium was labeled heavily, but the sheath around the haustorium and the host cell remained free of label. These results indicate that no detectable amounts of label leach from the bean rust into the host at this stage of infection although it is known that the rust takes up many metabolites. Since the sheath remains free of label and all fungal structures are evenly labeled, it is concluded that the sheath is formed by the host.
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  • 4
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Bei der Wirt-Parasit-Kombination Phaseolus vulgaris (cv. Favorit) und Uromyces phaseoli typica wird die Aktivität peroxydatischer Enzyme am dritten Tag nach Infektion elektronenmikroskopisch dargestellt. Die Aktivität in den Mitochondrien (möglicherweise eine Cytochromoxydase oder Cytochromperoxydase) ist in der infizierten Zelle erhöht. Die Peroxisomen (sie enthalten eine Katalase) bleiben in der infizierten Zelle unverändert. Im Pilz wird keine Katalaseaktivität gefunden. Die Schicht mit peroxydatischer Aktivität auf der Außenseite der Zellwand (Zellwandperoxydase) ist an der Berührungsstelle Hyphe—Wirtswand oft verdickt. An der Eintrittsstelle des Haustoriums in die Zelle wird Aktivität auf der Wand des Haustoriumhalses und auf den Cisternen des benachbarten ribosomenbesetzten endoplasmatischen Reticulums beobachtet. Manchmal findet man auch eine Schicht mit peroxydatischer Aktivität zwischen Scheide und Wand des Haustoriums.
    Notes: Summary Peroxidase activity in Phaseolus vulgaris (cultivar Favorit), infected with Uromyces phaseoli typica, was studied with the help of an electronmicroscope. The plant material was prefixed three days after inoculation and 3,3-diaminobenzidine was used as a substrate to detect the enzyme activity. The mitochondrial membranes showed an enhanced enzyme activity (due to a cytochrome oxidase or possibly due to a cytochrome peroxidase) in the infected cell. There was no change in the structure and catalase activity of peroxisomes of the host. No catalase activity was detected in the fungus. A layer with evident peroxidase activity is seen outside the cell wall. This layer is sometimes thickened especially when it is in touch with intercellular hyphae. The penetration site of the haustorium has been intensively studied. Activity was observed in the neck region (from the penetration site of the haustorium to the neckband) in the zone between the host plasmalemma and the plasmalemma of the fungus. Some activity was also seen on the cisternae of the endoplasmic reticulum surrounding the neck. In a few preparations, activity was also found between sheath and wall of the haustorium.
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  • 5
    ISSN: 1432-072X
    Keywords: Infection structure differentiation ; Protein metabolism ; Rust fungi ; Thigmo-differentiation ; Two-dimensional polyacrylamide gel electrophoresis ; Uromyces vicae-fabae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract On artificial polyethylene membranes providing a thigmotropic signal, uredospores of the broad bean rust fungus Uromyces viciae-fabae differentiated a series of infection structures which in nature are necessary to invade the host tissue through the stomata. Within 24 h germ tubes, appressoria, substomatal vesicles, infection hyphae and haustorial mother cells were developed successively. Alterations in protein metabolism during infection structure differentiation of this obligate plant pathogen were analyzed in the absence of the host plant by high resolution two-dimensional polyacrylamide gel electrophoresis (2-DE) and silver staining. The norm pattern representing the 2-DE protein patterns of the whole developmental sequence of infection structures of U. viciae-fabae showed 733 spots. During infection structure differentiation 55 proteins were newly formed, altered in quantity, or disappeared. Major alterations in the protein pattern occurred during uredospore germination and when infection hyphae were formed. Uredospore germination was characterized by a decrease of acidic proteins and an increase mainly of proteins with isoelectric points ranging from weakly acidic to basic.
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  • 6
    ISSN: 1615-6102
    Keywords: Filipin-sterol complexes ; freeze-etch ; Uromyces appendiculatus ; Phaseolus vulgaris ; Puccinia coronata ; Avena sativa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Treatment with the polyene antibiotic filipin resulted in the formation of granular protuberances of the plasmamembranes of the mesophyll cells of bean (Phaseolus vulgaris) and oat (Avena sativa) plants, and of intercellular hyphal cells of the rust fungiUromyces appendiculatus var.appendiculatus andPuccinia coronata var.avenae, as seen by freeze-etch electron microscopy. The granules were also occasionally seen in intracellular vesicles ofU. appendiculatus. None were found in any intracellular organelles of plant or fungal tissue. The granules ranged in size from about 20–25 nm in the plant tissue and 21–27 nm in the fungal tissue. They were concluded to be filipin-sterol (FS) complexes. The extrahaustorial membranes of either bean or oat rustinfected tissue were generally devoid of FS complexes. The extrahaustorial membrane is continuous with the host plasmamembrane but appeared to have a lower sterol content as compared to the non-invaginated plasmamembrane. The results are discussed in relation to membrane associations at the host-parasite interface.
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  • 7
    ISSN: 1615-6102
    Keywords: Affinity chromatography ; Biotrophy ; Concanavalin A ; Extrahaustorial matrix ; Puccinia ; Uromyces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rust haustoria isolated from infected leaf tissue strongly bind to ConA. This property was exploited to purify them by affinity chromatography on a ConA-Sepharose macrobead column. Haustoria were obtained with more than 90% purity and yields of up to 50%. Binding of haustoria to the column was partially inhibited by a ConA-specific sugar, methyl α-D-mannopyranoside. Compared to ConA,Lens culinaris agglutinin and wheat germ agglutinin were less efficient affinity ligands. Using ConA-Sepharose, rust haustoria from a variety of sources could be isolated with equal efficiency, indicating that they have similar carbohydrate surface properties. The haustoria maintained their typical shape after the isolation procedure, which suggests a rather rigid wall structure. The morphology of haustoria was characteristic both for a given species and the nuclear condition of the rust mycelium. Electron microscopy of isolated haustoria revealed an intact haustorial wall surrounded by a fibrillar layer presumably derived from the extrahaustorial matrix. The matrix thus appears to represent a layer with gel-like properties which is rich in ConA-binding carbohydrates and connected to the haustorial wall but not to the host-derived extrahaustorial membrane.
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  • 8
    ISSN: 1615-6102
    Keywords: Uromyces appendiculatus ; High pressure freezing ; Freeze substitution ; Cryoprotection ; Fine structure preservation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The fine structure of the intercellular dikaryotic hyphae of the biotrophic fungusUromyces appendiculatus was studied. High pressure freezing and freeze substitution were used to achieve a closer approximation of the native state than with conventional fixation and dehydration techniques. In addition to organelles previously described in rust fungi, heavily decorated multivesicular bodies (star bodies) were found close to the nuclei. Two types of tubular-vesicular complexes were distributed randomly within the cytoplasm of the hyphae. Furthermore, a more or less pronounced brush-like fibrillar layer on the hyphal walls was detected. The possibility that the latter two structures are correlated with the biotrophic phase of this fungus is discussed.
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  • 9
    ISSN: 1615-6102
    Keywords: Rust fungi ; Uromyces ; Infection structures ; Lectins ; Cell wall architecture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Uredospores ofUromyces viciae-fabae differentiate to form germ tubes, appressoria, infection hyphae and haustorial mother cells on oil-containing collodion membranes. The cell walls of these infection structures were studied with the electron microscope and with FITC-labeled lectins before and after treatment with enzymes and inorganic solvents. Binding of the FITC-labeled lectins was measured with a microscope photometer. The enzymes pronase E, laminarinase, chitinase and lipase had different effects on each infection structure. Pronase treatment uncovered the chitin of germ tubes, appressoria and haustorial mother cells, but not of substomatal vesicles and infection hyphae. A mixture of α- and β-1,3-glucanase which also contained chitinase activity dissolved germ tubes and appressoria completely, but not infection pegs, substomatal vesicles, infection hyphae and haustorial mother cells. After treatment with laminarinase or lipase, an additional layer, which is especially obvious over the substomatal vesicle, infection hypha and haustorial mother cell, bound to LCA-FITC. In the wall of the haustorial mother cell, a ring, which surrounds the presumed infection peg, had strong affinity for WGA after protease and sodium hydroxide treatment. The infection structures have a fibrillar skeleton. The main constituent seems to be chitin. This skeleton is more dense or has a higher chitin content in the walls of appressoria and haustorial mother cells. The fibrils of the skeleton extend throughout the cell wall of the germ tube and appressorium. They are embedded within amorphous material of complex chemical composition (α-1,3-glucan, β-1,3-glucan, glycoprotein). The chitin of the infection peg, substomatal vesicle, infection hypha and haustorial mother cell is covered completely with this amorphous material. These results show, that each infection structure has distinct surface and wall characteristics. They may reflect the different tasks of the infection structures during host recognition and leaf penetration.
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  • 10
    ISSN: 1615-6102
    Keywords: Monokaryotic haustorium ; Encasement ; High pressure freezing ; Immunolabelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Monokaryotic haustoria (M-haustoria) ofUromyces vignae inVigna sinensis cells are surrounded by an extrahaustorial matrix (ema) and the invaginated host plasmalemma, the extrahaustorial membrane (ehrn). The ema was characterized with antibodies against components of the plant cell wall; the ema contained hydroxyproline-rich glycoproteins and arabinogalactans/arabinogalactan proteins, both at a higher concentration close to the ehm. Haustoria with large vacuoles had the ema encased by additional layers. An electron-translucent inner layer deposited on top of the ema contained arabinogalactans/arabinogalactan proteins, hydroxyproline-rich glycoproteins, and callose. The inner layer was surrounded by an electron-translucent middle layer with numerous dark inclusions, rich in pectin and fucose bound to xyloglucans. Finally, a more electron-dense outer layer containing arabinogalactans/arabinogalactan proteins and hydroxyproline-rich glycoproteins encased the whole structure. These polysaccharides, with the exception of callose and un-esterified pectin, were also found in the plant Golgi apparatus. The polysaccharides were synthesized in the trans Golgi cisternae and secreted into the host-parasite interface. The secretory events seem to be coupled to endocytosis since numerous coated pits were found on the ehm too. The pits were elongated, sometimes formed tubules and the coat reacted with an antibody against plant clathrin. Our results suggest intensive membrane recycling around haustoria, together with the secretion of cell wall material, which in the case of more or less vacuolated haustoria seems to be responsible for encasement
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