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  • 1
    Publication Date: 1987-03-27
    Description: The dimensions of the topographical signals for growth orientation and infection structure formation, a cell differentiation event that includes nuclear division, were determined for the stomatal penetrating rust fungus Uromyces appendiculatus. The differentiation signal was found to be a simple ridge on the substrate surface that had a markedly optimum height of 0.5 micrometer. Such ridges were microfabricated on silicon wafers by using electron-beam lithography. A similar ridge, in the form of a stomatal lip, was found associated with the stomatal guard cells of the bean (Phaseolus vulgaris) leaf. Ridge elevations greater than 1.0 micrometer or less than 0.25 micrometer did not serve as effective signals. Germ tubes of the fungus were highly oriented by ridge spacings of 0.5 to 6.7 micrometers. The data indicate that the fungus is able to distinguish uniquely minute differences in leaf surface topography in order to infect the host plant.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hoch, H C -- Staples, R C -- Whitehead, B -- Comeau, J -- Wolf, E D -- New York, N.Y. -- Science. 1987 Mar 27;235(4796):1659-62.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17795599" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Phytopathology 25 (1987), S. 231-247 
    ISSN: 0066-4286
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Biology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Current genetics 15 (1989), S. 411-414 
    ISSN: 1432-0983
    Keywords: Onion leaf blight ; Onion neck-rot ; Botrytis squamosa ; Hygromycin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The onion leaf blight fungus, Botrytis squamosa, was transformed to hygromycin B resistance using a plasmid (pDH25) containing a bacterial gene for hygromycin phosphotransferase (hph) fused to promoter elements from Aspergillus. Southern hybridization of transformants indicated that single or multiple copies of the vector were integrated into heterologous regions of the B. squamosa genome. Free plasmid was found in undigested preparations of transformant DNA, but was not detected after 3–5 passages of selective transfer. Most transformants were mitotically stable in both selective and non-selective growth; however, both genetic rearrangements and loss of integrated DNA occurred during vegetative growth.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 109 (1976), S. 75-84 
    ISSN: 1432-072X
    Keywords: Anthracnose ; Appressoria ; Nuclear division ; Spore germination ; Differentiation ; Colletotrichum truncatum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Conidia of the soybean anthracnose fungus, Colletotrichum truncatum differentiate to form appressoria required for host invasion when the germ tube touches a hard surface. This thigmotrophic stimulus appears to be translated by the fungus during the second round of nuclear division. Inhibiting the second round of DNA synthesis by fluorodeoxyuridine or hydroxyurea blocked appearance of appressoria but not emergence of the germ tube. DNA synthesis and mitosis resumed upon removal of FUdR but only mycelia formed, and infection structures did not appear. In addition, actinomycin D reversibly blocked development of appressoria and synthesis of polyadenylate, but nuclear division was not affected. The data suggest that anthracnose conidia produce appressoria in response to germ tube contact by altering the messenger program of its germ tube nucleus. This study has also shown that mitochondrial DNA had an unusual bimodal distribution in CsCl at 1.690 and 1.719 g/cm3, respectively.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of plant pathology 74 (1968), S. 25-36 
    ISSN: 1573-8469
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Uit rustende en gekiemde uredosporen van de boneroest,Uromyces appendiculatus (Pers.) Ung., (syn.U. phaseoli (Pers.) Wint.) werden ribosomen geïsoleerd met een sedimentatieconstante (S20,w) van 82.3. Incorporatie van aminozuren door de ribosomen werd gekatalyseerd door een oplossing van activerende enzymen, verkregen uit de uredosporen. Een klein deel van de ribosomen kwam voor in polysoomstructuren, die gevoelig waren voor ribonuclease. Wanneer geen boodschapper-RNA werd toegevoegd, was de aminozuur-incorporende activiteit grotendeels geassocieerd met deze polysomen, die sedimentatieconstanten hadden van tenminste 204 S. RNA, geïsoleerd uit sporen in verschillende stadia van de kieming, had boodschapperactiviteit, zoals bleek bij toetsing in een celvrij aminozuur-incorporerend systeem uitEscherichia coli. Hieruit en uit het feit, dat polysomen aanwezig waren, kan tot de aanwezigheid van boodschapper-RNA in de uredosporen geconcludeerd worden.
    Notes: Abstract Ribosomes were isolated from dormant and germinated uredospores of the bean rust fungus and found to have sedimentation constants (S20, w) of 82.3. A supernatant solution of activating enzymes prepared from uredospores catalyzed amino acid incorporation by ribosomes. A small proportion of the ribosomes was associated in ribonuclease sensitive clusters. In the absence of added messenger RNA, a large proportion of the amino acid incorporation was carried out by these polysomes, which had sedimentation coefficients at least as high as 204 S. Presence of messenger RNA in spores is inferred from the fact that polysomes are present and that RNA preparations from spores at various stages of germination have template activity in an assay system prepared fromEscherichia coli.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1615-6102
    Keywords: Uromyces ; Differentiation ; Cytoskeleton ; Actin ; Cytochalasin E ; Phalloidin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The role of F-actin in cell differentiation ofUromyces appendiculatus (bean rust fungus) germlings was examined by treating differentiating and nondifferentiating germlings with the actin-binding drugs cytochalasin E (CE) and phalloidin. Prolonged exposure of urediospores to 5×10−3–5 × 10−5 M CE induced nuclear division in up to 28–45% of the resulting germlings, whereas the rate of mitosis in established germlings exposed to these concentrations of CE was significantly lower (4–11%). Germlings treated with CE shifted from polarized apical growth to spherical expansion, cytoplasmic microfilaments were depolymerized, and nuclear inclusions became enlarged. Differentiating germlings exposed to a 10 minute pulse of 5×10−6M CE before the initiation of septum formation prevented the establishment of the F-actin septal ring and growth of the crosswall delimiting the appressorium. Although these CE treatments resulted in morphological and nuclear events similar to those occurring during normal appressorium formation, transient microfilament depolymerization was not sufficient to induce differentiation. Phalloidin stabilized cytoplasmic microfilaments, especially posteriorly-located microfilaments, but did not affect differentiation, nor did it significantly inhibit the effects of CE.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 194 (1996), S. 91-102 
    ISSN: 1615-6102
    Keywords: Appressoria ; Fungi ; Integrin ; RGD-peptides ; Rust fungi ; Uromyces appendiculatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Germlings of the plant pathogenic fungusUromyces appendiculatus sense and respond to topographical signals of various substrata by undergoing a cell differentiation process that culminates in a structure termed an appressorium. In some cell systems, recognition and mediation of extracellular signals is via transmembrane glycoproteins known as integrins that often exhibit specific affinities to the tripeptide sequence Arg-Gly-Asp (RGD) found in several extracellular matrix components. Germlings grown on substrata inductive for appressorium formation in the presence of buffered synthetic peptides containing the amino acid sequence RGD, e.g., RGD, RGDS, GRGD, and GRGDGSPK (0.5–2.0 mM), were inhibited from developing appressoria. Two non-RGD peptides (GGGG and RGES) as well as two RGD peptides (GRGDS and RGDSPASSKP) did not inhibit appressorium formation. Germling growth was not significantly affected by any of the peptides. Furthermore, 0.5 μm diameter micropipettes that are normally inductive for appressorium formation when positioned between the germling apex and the substratum did not induce appressorium formation when coated with the RGD peptide. Silanized micropipettes left uncoated or coated with RGES were inductive for appressorium formation. Those observations lead to the hypothesis that an integrin-like protein may be involved in the process of signaling for initiation of appressorium formation inUromyces. An RGDSPC-affinity column was used to isolate proteins fromUromyces germlings with affinity to the RGD sequence. Elution with RGD or EDTA, but not with RGES, yielded at least 12 proteins of which one protein (95 kDa) expressed affinity on immunoblots to two different antibodies of β1-integrin; one to the carboxyl-terminus of a synthetic peptide of integrin from chicken, and the other from the amino terminus of integrin from human placenta.
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  • 8
    ISSN: 1615-6102
    Keywords: Cytoskeleton ; Immunocytochemistry ; Microfilaments ; Microtubules ; Microtubule organizing center ; Uromyces phaseoli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The microtubule and F-actin cytoskeleton of nondifferentiated germlings ofUromyces phaseoli was studied using immunofluorescence methodologies. The microtubules were oriented mostly parallel to the longitudinal axis of the hypha. Microtubule depolymerizing agents, such as cold, demecolcine, griseofulvin and nocodazole, were effective in destroying the microtubule network, but not the F-actin system. Repolymerization of microtubules, following release from these agents, occurred first in the hyphal apices and not near the nuclei or spindle pole bodies. It was concluded that the microtubule nucleating region in such fungal cells is located in the apical regions. Enhanced microtubule arrays were visualized following incubation of the cells in taxol, an agent known to favor microtubule polymerization.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 165 (1991), S. 37-50 
    ISSN: 1615-6102
    Keywords: Bean rust fungus ; F-actin ; Laser scanning confocal microscopy ; Microtubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Formation of appressoria inUromyces appendiculatus is triggered by external physical features of host stomata as well as artifical surfaces bearing inductive topographies. Microtubule and F-actin microfilament cytoskeletons were examined for their involvement in the process of appressorium formation in this fungus, using laser scanning confocal and electron microscopy. In germlings not stimulated to form appressoria the microtubule and microfilament cytoskeletons were organized as filaments mostly oriented parallel to the longitudinal axis of the cell. Following contact of the germling apex with an inductive topographical signal, e.g., 0.5 μm high ridge, the microtubules and F-actin filaments in the cell apex nearest the substrate appeared randomly oriented. Microtubules farther from the substrate remained oriented parallel to the longitudinal axis of the cell. In later stages of appressorium development, many cytoskeletal elements became oriented parallel to the inductive ridge, especially near the substrate. In regions farther from the substrate in these same cells, the microtubules and microfilaments were arranged in a reticulate pattern. Changes in the distribution and organization of the microtubule and F-actin microfilament cytoskeletons reflect a change in cell function following signal reception for appressorium. The reorientation of the cytoskeleton likely dictates the change in cell morphology.
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  • 10
    Publication Date: 1976-01-01
    Print ISSN: 0302-8933
    Electronic ISSN: 1432-072X
    Topics: Biology
    Published by Springer
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