Ultrastructure of eastern cottonwood clones susceptible or resistant to leaf rust

1987 ◽  
Vol 65 (8) ◽  
pp. 1586-1598 ◽  
Author(s):  
L. Shain ◽  
U. Järlfors
Keyword(s):  
Electron Microscopy ◽  
Leaf Rust ◽  
Light And Electron Microscopy ◽  
Infection Process ◽  
The Other ◽  
Host Cells ◽  
Eastern Cottonwood ◽  
Melampsora Medusae ◽  
Wall Appositions ◽  
Infected Cells

The infection process in four clones of eastern cottonwood susceptible or resistant to leaf rust caused by Melampsora medusae was studied by light and electron microscopy. Infection was initiated by stomatal rather than direct entry. Typical dikaryotic haustoria were observed in all clones within 1 day of inoculation. Some healthy-appearing haustoria were observed in susceptible clones throughout the duration of the study, which was terminated during the initiation of uredial production. Incompatibility was expressed differently in the two resistant clones. In clone St 75, most haustoria and invaded host cells that were observed appeared necrotic within 2 days of inoculation. Cell wall appositions appeared during this time in cells adjoining necrotic host cells. Some infected cells disintegrated within 4 days of inoculation. Affected host cells of clone St 92, on the other hand, plasmolyzed during the first 2 to 3 days after inoculation. Necrotic host cells were not observed in this clone until the 4th day after inoculation. Hyphal ramification and host plasmolysis were extensive at 6 days after inoculation.

The illustrated life cycle of Microbotryum on the host plant Silene latifolia

Botany ◽  
2010 ◽  
Vol 88 (10) ◽  
pp. 875-885 ◽  
Author(s):  
Angela Maria Schäfer ◽  
Martin Kemler ◽  
Robert Bauer ◽  
Dominik Begerow
Keyword(s):  
Life Cycle ◽  
Light And Electron Microscopy ◽  
Laboratory Data ◽  
Infection Process ◽  
Host Cells ◽  
Silene Latifolia ◽  
Long Distance ◽  
Biological Studies ◽  
Plant Parasitic

The plant-parasitic genus Microbotryum (Pucciniomycotina) has been used as a model for various biological studies, but fundamental aspects of its life history have not been documented in detail. The smut fungus is characterized by a dimorphic life cycle with a haploid saprophytic yeast-like stage and a dikaryotic plant-parasitic stage, which bears the teliospores as dispersal agents. In this study, seedlings and flowers of Silene latifolia Poir. (Caryophyllaceae) were inoculated with teliospores or sporidial cells of Microbotryum lychnidis-dioicae (DC. ex Liro) G. Deml & Oberw. and the germination of teliospores, the infection process, and the proliferation in the host tissue were documented in vivo using light and electron microscopy. Although germination of the teliospore is crucial for the establishment of Microbotryum, basidium development is variable under natural conditions. In flowers, where the amount of nutrients is thought to be high, the fungus propagates as sporidia, and mating of compatible cells takes place only when flowers are withering and nutrients are decreasing. On cotyledons (i.e., nutrient-depleted conditions), conjugation occurs shortly after teliospore germination, often via intrapromycelial mating. After formation of an infectious hypha with an appressorium, the invasion of the host occurs by direct penetration of the epidermis. While the growth in the plant is typically intercellular, long distance proliferation seems mediated through xylem tracheary elements. At the beginning of the vegetation period, fungal cells were found between meristematic shoot host cells, indicating a dormant phase inside the plant. By using different microscopy techniques, many life stages of Microbotryum are illustrated for the first time, thereby allowing new interpretations of laboratory data.

Fine Structure of the Eye of a Nudibranch Mollusc, Hermissenda Crassicornis

1967 ◽  
Vol 2 (3) ◽  
pp. 349-358
Author(s):  
R. M. EAKIN ◽  
JANE A. WESTFALL ◽  
M. J. DENNIS
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Optic Nerve ◽  
Light And Electron Microscopy ◽  
The Other ◽  
Sensory Cells ◽  
Nerve Fibres ◽  
Supporting Cells ◽  
Small Bodies ◽  
Receptor Cells

The eye of a nudibranch, Hermissenda crassicornis, was studied by light and electron microscopy. Three kinds of cells were observed: large sensory cells, each bearing at one end an array of microvilli (rhabdomere) and at the other end an axon which leaves the eye by the optic nerve; large pigmented supporting cells; and small epithelial cells, mostly corneal. There are five sensory cells, and the same number of nerve fibres in the optic nerve. The receptor cells contain an abundance of small vesicles, 600-800 Å in diameter. The lens is a spheroidal mass of osmiophilic, finely granular material. A basal lamina and a capsule of connective tissue enclose the eye. In some animals the eye is ‘infected’ with very small bodies, 4-5 µ in diameter, thought to be symbionts.

Asci of the Pezizales. I. The apical apparatus of iodine-positive species

1978 ◽  
Vol 56 (16) ◽  
pp. 1860-1875 ◽  
Author(s):  
Don A. Samuelson
Keyword(s):  
Electron Microscopy ◽  
Positive Reaction ◽  
Light And Electron Microscopy ◽  
The Other ◽  
Reaction Site ◽  
Lower Region

Morphological, developmental, and cytochemical studies on the apical apparatuses of five species, i.e., Peziza succosa, Ascobolus crenulatus, Saccobolus depauperatus, Thecotheus pelletieri, and Iodophanus granulipolaris, were performed with light and electron microscopy. Asci of all species, except A. crenulatus, stain blue in Melzer's reagent. The site of the iodine-positive reaction is believed to be an exogenous mucilaginous coat in P. succosa, S. depauperatus, and T. pelletieri. In I. granulipolaris, the reaction site appears to be the ascal wall. The presence of an annular indentation was found in the ascal tips of all species except I. granulipolaris. A line of dehiscence was found in the lower region of the annular indentation in T. pelletieri and S. depauperatus. The development of the apical apparatuses of all species occurs during and after late ascosporogenesis. The apical apparatus of I. granulipolaris diverged significantly in morphology and cytochemistry from the other species.

scholarly journals AutoCLEM: An Automated Workflow for Correlative Live-Cell Fluorescence Microscopy and Cryo-Electron Tomography

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xiaofeng Fu ◽  
Jiying Ning ◽  
Zhou Zhong ◽  
Zandrea Ambrose ◽  
Simon Charles Watkins ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Speed ◽  
Electron Tomography ◽  
Light And Electron Microscopy ◽  
Live Cell ◽  
Host Cells ◽  
Spatiotemporal Information ◽  
Fluorescence Light ◽  
Correlation Process ◽  
Electron Imaging

AbstractCorrelative light and electron microscopy (CLEM) combines the strengths of both light and electron imaging modalities and enables linking of biological spatiotemporal information from live-cell fluorescence light microscopy (fLM) to high-resolution cellular ultra-structures from cryo-electron microscopy and tomography (cryoEM/ET). This has been previously achieved by using fLM signals to localize the regions of interest under cryogenic conditions. The correlation process, however, is often tedious and time-consuming with low throughput and limited accuracy, because multiple correlation steps at different length scales are largely carried out manually. Here, we present an experimental workflow, AutoCLEM, which overcomes the existing limitations and improves the performance and throughput of CLEM methods, and associated software. The AutoCLEM system encompasses a high-speed confocal live-cell imaging module to acquire an automated fLM grid atlas that is linked to the cryoEM grid atlas, followed by cryofLM imaging after freezing. The fLM coordinates of the targeted areas are automatically converted to cryoEM/ET and refined using fluorescent fiducial beads. This AutoCLEM workflow significantly accelerates the correlation efficiency between live-cell fluorescence imaging and cryoEM/ET structural analysis, as demonstrated by visualizing human immunodeficiency virus type 1 (HIV-1) interacting with host cells.

Light and electron microscopy of a host–fungus interaction in the roots of some epiphytic ferns from Costa Rica

1995 ◽  
Vol 73 (7) ◽  
pp. 991-996 ◽  
Author(s):  
E. Schmid ◽  
F. Oberwinkler ◽  
L. D. Gómez
Keyword(s):  
Electron Microscopy ◽  
Costa Rica ◽  
Matrix Material ◽  
Light And Electron Microscopy ◽  
Root Hairs ◽  
Host Cells ◽  
Cortical Cells ◽  
Host Fungus ◽  
Hyphal Coils ◽  
Uniform Diameter

The roots of 11 epiphytic fern species from the genera Elaphaglossum, Peltapteris, Hymenophyllum, Grammitis, and Lellingeria were studied by means of light and electron microscopy. All species showed a similar association with an ascomycete that traversed the root hairs and formed intracellular hyphal coils within cytoplasmic epidermal and outer cortical cells. The unbranched fungal hyphae were of a uniform diameter. They were surrounded by a flocculent matrix material and by the host plasmalemma. Cytoplasmic hyphae also occurred within degenerated host cells. The host–fungus interaction showed similarities to Ericoid mycorrhizae. Key words: ferns, mycorrhiza, ascomycete, ultrastructure, Costa Rica.

Morphology of infection of onion leaves by Alternaria porri

1994 ◽  
Vol 72 (8) ◽  
pp. 1164-1170 ◽  
Author(s):  
Theresa A. S. Aveling ◽  
Heidi G. Snyman ◽  
F. H. J. Rijkenberg
Keyword(s):  
Electron Microscopy ◽  
Epidermal Cell ◽  
Leaf Surface ◽  
Infection Process ◽  
Mesophyll Cells ◽  
Transmission Electron ◽  
Close Proximity ◽  
Alternaria Porri ◽  
Infected Cells ◽  
Germ Tubes

Conidial germination of Alternaria porri, formation of prepenetration structures, penetration of the onion leaf surface, and the postpenetration processes were studied using light, scanning electron, and transmission electron microscopy. Ninety-six percent of conidia germinated at 25 °C within 24 h of inoculation. Each conidium formed several germ tubes that grew in any direction across the leaf surface. Each germ tube usually terminated in a bulbous appressorium formed directly on the epidermal cell (52.4% of appressoria) or on a stoma (48.6% of appressoria). Following direct penetration of the outer epidermal cell wall or the stoma, bulbous primary hyphae developed below the appressoria. Secondary hyphae developed from the primary hyphae within 48 h after inoculation and grew within the intercellular spaces penetrating mesophyll cells. The changes in ultrastructure of cells in close proximity to hyphae and of infected cells are described. Key words: Allium cepa, electron microscopy, infection process, purple blotch.

Somatic mitosis in Erysiphe graminis hordei

1972 ◽  
Vol 18 (12) ◽  
pp. 1915-1922 ◽  
Author(s):  
W. E. McKeen
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Nuclear Membrane ◽  
Osmium Tetroxide ◽  
Central Body ◽  
Nuclear Division ◽  
Light And Electron Microscopy ◽  
Erysiphe Graminis ◽  
The Other ◽  
Erysiphe Graminis Hordei

Somatic nuclear division in Erysiphe graminis hordei was studied by light and electron microscopy after various fixation and staining procedures. Electron microscopy studies of alcohol – acetic acid fixed material aided in providing an understanding of nuclear division and showing the gross alterations which occurred. Light microscopy indicated that a central body was always present at a specific site on the nuclear membrane in the interphase nucleus and was connected to chromatic spherical bodies. Microtubules were preserved when a short glutaraldehyde – osmium tetroxide fixation was used. Some microtubules extend from plaque to plaque while others terminate in kinetochores. A microtubular spindle, oblique to the nuclear and mildew-cells axes formed within the nuclear membrane. Typical prophases, metaphases, anaphases, and telophases were observed. Then one set of daughter chromatids bypassed the nucleolus which persisted intranuclearly until the daughter nuclei reached their destination, and the other set of daughter chromatids moved to midpoint in the other daughter cell. A narrow corridor, which connected daughter nuclei for some time, was filled mainly with microtubules and probably was the filament which was observed in the nucleus by light microscopy during nuclear division. At least six chromosomes were present in each nucleus.

scholarly journals Reovirus Forms Neo-Organelles for Progeny Particle Assembly within Reorganized Cell Membranes

mBio ◽  
2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Isabel Fernández de Castro ◽  
Paula F. Zamora ◽  
Laura Ooms ◽  
José Jesús Fernández ◽  
Caroline M.-H. Lai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Viral Replication ◽  
Cell Membranes ◽  
Light And Electron Microscopy ◽  
Host Cells ◽  
Pharmacological Intervention ◽  
Genome Replication ◽  
Particle Assembly ◽  
Intermediate Compartment

ABSTRACTMost viruses that replicate in the cytoplasm of host cells form neo-organelles that serve as sites of viral genome replication and particle assembly. These highly specialized structures concentrate viral replication proteins and nucleic acids, prevent the activation of cell-intrinsic defenses, and coordinate the release of progeny particles. Despite the importance of inclusion complexes in viral replication, there are key gaps in the knowledge of how these organelles form and mediate their functions. Reoviruses are nonenveloped, double-stranded RNA (dsRNA) viruses that serve as tractable experimental models for studies of dsRNA virus replication and pathogenesis. Following reovirus entry into cells, replication occurs in large cytoplasmic structures termed inclusions that fill with progeny virions. Reovirus inclusions are nucleated by viral nonstructural proteins, which in turn recruit viral structural proteins for genome replication and particle assembly. Components of reovirus inclusions are poorly understood, but these structures are generally thought to be devoid of membranes. We used transmission electron microscopy and three-dimensional image reconstructions to visualize reovirus inclusions in infected cells. These studies revealed that reovirus inclusions form within a membranous network. Viral inclusions contain filled and empty viral particles and microtubules and appose mitochondria and rough endoplasmic reticulum (RER). Immunofluorescence confocal microscopy analysis demonstrated that markers of the ER and ER-Golgi intermediate compartment (ERGIC) codistribute with inclusions during infection, as does dsRNA. dsRNA colocalizes with the viral protein σNS and an ERGIC marker inside inclusions. These findings suggest that cell membranes within reovirus inclusions form a scaffold to coordinate viral replication and assembly.IMPORTANCEViruses alter the architecture of host cells to form an intracellular environment conducive to viral replication. This step in viral infection requires the concerted action of viral and host components and is potentially vulnerable to pharmacological intervention. Reoviruses form large cytoplasmic replication sites called inclusions, which have been described as membrane-free structures. Despite the importance of inclusions in the reovirus replication cycle, little is known about their formation and composition. We used light and electron microscopy to demonstrate that reovirus inclusions are membrane-containing structures and that the endoplasmic reticulum (ER) and the ER-Golgi intermediate compartment interact closely with these viral organelles. These findings enhance our understanding of the cellular machinery usurped by viruses to form inclusion organelles and complete an infectious cycle. This information, in turn, may foster the development of antiviral drugs that impede this essential viral replication step.

Unusual macromorphology of the ductuli efferentes and epididymis of the koala (Phascolarctos cinereus)

2000 ◽  
Vol 48 (6) ◽  
pp. 681
Author(s):  
Rachel J. Gibson ◽  
Chris M. Leigh ◽  
William G. Breed
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Secretory Activity ◽  
The Other ◽  
Ciliated Cells ◽  
Phascolarctos Cinereus ◽  
Ductuli Efferentes ◽  
Sds Page ◽  
Marsupial Species ◽  
Electron Lucent

The macromorphology of the ductuli efferentes and epididymis of the koala (Phascolarctos cinereus) was investigated and found to differ from that of other marsupial species that have been described as it comprised four macroscopically distinct lobes. Light and electron microscopy of epithelium of the duct within these lobes showed that there were principal and ciliated cells lining the duct of the first lobe, indicating it to be composed of ductuli efferentes. In the other three lobes, the epithelium contained principal, basal, electron-lucent, and mitochondria-rich cells, showing that these three lobes included the epithelium of the epididymis. The height of this epithelium gradually increased along the duct (contrary to the situation in most other species that have been studied, in which a decrease occurs). Preliminary 1D-SDS PAGE observations of flushes from the caput and cauda epididymides suggested that epididymal proteins were secreted along much of the length of the duct; the greater height of the cauda epithelium may relate to the greater protein synthetic and secretory activity in this region.

scholarly journals Parvoviral nuclear import: bypassing the host nuclear-transport machinery

2006 ◽  
Vol 87 (11) ◽  
pp. 3209-3213 ◽  
Author(s):  
Sarah Cohen ◽  
Ali R. Behzad ◽  
Jeffrey B. Carroll ◽  
Nelly Panté
Keyword(s):  
Electron Microscopy ◽  
Nuclear Import ◽  
Mouse Fibroblast ◽  
Host Cells ◽  
Fibroblast Cells ◽  
Dna Virus ◽  
Minute Virus Of Mice ◽  
Nuclear Lamin ◽  
Infected Cells ◽  
Minute Virus

The parvovirus Minute virus of mice (MVM) is a small DNA virus that replicates in the nucleus of its host cells. However, very little is known about the mechanisms underlying parvovirus' nuclear import. Recently, it was found that microinjection of MVM into the cytoplasm of Xenopus oocytes causes damage to the nuclear envelope (NE), suggesting that the nuclear-import mechanism of MVM involves disruption of the NE and import through the resulting breaks. Here, fluorescence microscopy and electron microscopy were used to examine the effect of MVM on host-cell nuclear structure during infection of mouse fibroblast cells. It was found that MVM caused dramatic changes in nuclear shape and morphology, alterations of nuclear lamin immunostaining and breaks in the NE of infected cells. Thus, it seems that the unusual nuclear-import mechanism observed in Xenopus oocytes is in fact used by MVM during infection of host cells.

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