Anna Appiano

Istituto di Genomica Applicata, Udine, Friuli Venezia Giulia, Italy

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Publications (13)11.94 Total impact

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    ABSTRACT: The possible role of two types of inclusion bodies induced by tomato bushy stunt virus in Gomphrena globosa cells was investigated by electron microscope autoradiography after administration of tritiated uridine and by immunogold labeling on ultrathin sections. Our observations indicate that both multivesicular bodies (MVBs) and associated chloroplast invaginations are involved in virus replication. Since MVBs are always present in infected cells, even in those not containing chloroplasts, they appear to be the main site of virus RNA synthesis, while chloroplast invaginations are likely to provide, when present, an additional vesicular site for the same purpose. Neither of these structures contains viral protein. By contrast, the dense granules are not involved in virus RNA synthesis and consist mainly of virus coat protein, whose production is likely to occur in the cytoplasm.
    Journal of Ultrastructure and Molecular Structure Research 10/1986; 97(1-3):31-38. DOI:10.1016/S0889-1605(86)80004-0
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    ABSTRACT: Tomato bushy stunt virus induces in the cells of systemically infected Gomphrena globosa the formation of two different types of inclusions: multivesicular bodies (MVBs) and dense granules (DGs). Their origin, relationships with cell organelles, and development throughout the course of infection were investigated by selective staining, cytochemistry, and serial sectioning. Although they originated from peroxisomes, possibly with a contribution of endoplasmic reticulum for the vesicular component, the MVBs were strongly associated with chloroplasts. The chloroplasts were, in turn, highly modified, with flask-shaped invaginations opening toward the MVBs. By contrast, the DGs were not preferentially associated with particular cell components, and appeared to consist mainly of protein. The meaning of the association between MVBs and chloroplasts and the possible role of MVBs and DGs in the infection process are discussed.
    Journal of Ultrastructure and Molecular Structure Research 07/1986; 96(1-3):194-203. DOI:10.1016/0889-1605(86)90021-2
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    ABSTRACT: Summary Peculiar chloroplast alterations were found in mesophyll cells ofDatura stramonium systemically infected with tomato bushy stunt virus. These alterations lead to complete rearrangement of the thylakoids.
    Protoplasma 10/1985; 126(3):233-235. DOI:10.1007/BF01281799 · 3.17 Impact Factor
  • Anna Appiano · Giovanni D'agostino
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    ABSTRACT: Cytologisch onderzoek werd verricht aan helften van tabaksbladeren, waarin nieuwe eiwitcomponenten voorkwamen als gevolg van inoculatie van de tegenoverliggende bladhelften met tabaksmozaekvirus. Er werden geen verschillen in ultrastructuur gevonden tussen dit materiaal en dat van niet met virus genoculeerde planten. In beide gevallen werden twee soorten insluitsels waargenomen, nl. myeline-achtige en granulaire lichaampjes. Aard en mogelijke functie van deze lichaampjes worden besproken.
    European Journal of Plant Pathology 06/1985; 91(4):163-168. DOI:10.1007/BF02009677 · 1.71 Impact Factor
  • Anna Appiano · Klaus Neumann · Giovanni D'Agostino
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    ABSTRACT: The technique of cryo-ultramicrotomy was used for the detection of a plant reovirus in the tissue of its host plant. The observations made on cryosections, compared to those made on conventional sections, show that virus and related structures are well preserved, and that this technique can be usefully employed in plant virology.
    Micron and Microscopica Acta 12/1984; 15(3-15):171-176. DOI:10.1016/0739-6260(84)90048-0
  • A. Appiano · G. D'Agostino
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    ABSTRACT: The distribution of tomato bushy stunt virus in the root tips of Gomphrena globosa was studied by electron microscopy, in order to gain more information on this particular type of systemic infection. In the proximal region (1.2–5 mm from the apical initials), which contains differentiated vascular bundles, virus and related multivesicular (MV) bodies were abundant; in the median region (0.7–1.2 mm), where only the phloem is differentiated, there were progressively fewer virus particles and MV bodies; the distal region (0–0.7 mm) appeared virus free, in agreement with infectivity and immunosorbent electron microscopy tests. The possible reasons for the absence of virus from the root apex, and the relevance of the state of development of the vascular bundles, are discussed.
    Journal of Ultrastructure Research 12/1983; 85(3):239-248. DOI:10.1016/S0022-5320(83)90036-9
  • A Appiano · G D'Agostino · P Redolfi · S Pennazio
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    ABSTRACT: The ultrastructure of necrotic local lesions induced by tomato bushy stunt virus in Gomphrena globosa was studied during the first stages of development (24–64 hr postinoculation), in an attempt to define a sequence of cytological events possibly correlated with the mechanism of localization. The main cell alterations observed in the infection center were seen to appear in this order: swelling of the chloroplast thylakoids, alterations in shape of the chloroplasts and appearance of multivesicular bodies, appearance of virus particles, cell plasmolysis with callose deposits, necrosis. No deposition of lignin or suberin was observed in the infection stages examined. These results indicate that, at least in this virus—host combination, no “barrier substance” appears soon enough to be considered effective in preventing virus spread.
    Journal of Ultrastructure Research 09/1981; 76(2):173-80. DOI:10.1016/S0022-5320(81)80015-9
  • S. Pennazio · A. Appiano · P. Redolfi
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    ABSTRACT: Comphrena globosa leaves react to tomato bushy stunt virus giving, 30 h after inoculation, yellowish fluorescent spots which develop into necrotic lesions 8 h later. Thin sectioning of these spots revealed alterations of chloroplasts, mitochondria, cell walls, plasma membrane, and small groups of virus particles. Some cells showed severe degeneration presaging collapse and necrosis. The appearance of the fluorescent spots coincided with the accumulation of a flavonoid whose synthesis did not involve an increase of phenylalanine ammonia lyase activity. Significant increases in electrolyte leakage occurred starting from 5 h after inoculation. The release of electrolyte progressively increased with time and was very large from 25 h. The early electrolyte leakage, probably due to a change in permeability of the plasma membrane alone, cannot be the cause of the necrosis, and may be a consequence of an interaction between viral particles and plasma membrane.
    Physiologial Plant Pathology 09/1979; 15(2-15):177-182. DOI:10.1016/0048-4059(79)90066-3
  • A. Appiano · G. D'Agostino · S. Pennazio
  • S. Pennazio · G. D'Agostino · Anna Appiano · P. Redolfi
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    ABSTRACT: In a region of tissue (2 mm wide) surrounding local necrotic lesions of tomato bushy stunt virus (TBSV) on Gomphrena globosa leaves, and showing localized acquired resistance, the cells showed ultrastructural changes principally in the chloroplasts. The bundle sheath chloroplasts had conspicuous starch grains, abundant peripheral reticulum and well-defined grana; mesophyll chloroplasts lacked starch grains but had a prominent peripheral reticulum. The intercellular spaces of cells just encircling the lesion were incompletely filled with deposition materials consisting of lignins and suberins. The histochemical analysis of the whole resistant region revealed starch accumulation 48 h after inoculation. Callose was found only inside the lesion, at the periphery of the necrotic centre, 48 h after inoculation. Since no cell structure active in limiting viral diffusion could be observed, it is concluded that physiological changes must be involved in inducing localized resistance. Changes in chloroplast ultrastructure similar to those observed in cells of the resistant region were observed in mature, healthy G. globosa leaves, which react to TBSV like resistant tissues. It is, therefore, suggested that the induction of localized resistance can be regarded as an ageing reaction.
    Physiologial Plant Pathology 09/1978; 13(2-13):165-171. DOI:10.1016/0048-4059(78)90030-9
  • A. Appiano · S. Pennazio · P. Redolfi
    Journal of General Virology 08/1978; 40(2):277-286. DOI:10.1099/0022-1317-40-2-277 · 3.53 Impact Factor
  • Anna Appiano · S. Pennazio · G. D'Agostino · P. Redolfi
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    ABSTRACT: Local lesions, consisting of a central necrotic zone surrounded by a halo, induced on Gomphrena globosa leaves by tomato bushy stunt virus (TBSV), were studied by means of light and electron microscopy and by some histochemical techniques. In the necrotic zone, the cell contents were reduced to a dark matrix, whose electron-lucent areas were crowded with virus particles. The presence of small amounts of callose was histochemically demonstrated. The cells of the outer part of the halo showed many cytological alterations, such as: (1) the presence of an abundant cytoplasm crowded with organelles, indicating high metabolic activity; (2) a great accumulation of starch in the chloroplasts, which also showed sac-lice evaginations; (3) a massive deposition of material outside the cell walls, histochemically demonstrated to consist of lignins and suberins. Traces of callose were present as well. In the inner part of the halo, chloroplasts were devoid of starch and had conspicuous evaginations connected to “membranous bodies”. Cell walls were considerably thickened. In spite of the thickened walls, infective virus particles occurred in this part of the halo, therefore the presence of callow depositions and wall thickenings are not considered to act as a barrier responsible for TBSV localization.
    Physiologial Plant Pathology 11/1977; 11(3-11):327-332. DOI:10.1016/0048-4059(77)90075-3
  • Source
    A Appiano · S Pennazio
    Journal of General Virology 04/1972; 14(3):273-6. DOI:10.1099/0022-1317-14-3-273 · 3.53 Impact Factor