Ultrastructural changes in host leaf cells caused by host-selective toxin of Alternaria alternata from rough lemon

1984 ◽  
Vol 62 (12) ◽  
pp. 2485-2492 ◽  
Author(s):  
K. Kohmoto ◽  
Y. Kondoh ◽  
T. Kohguchi ◽  
H. Otani ◽  
S. Nishimura ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Alternaria Alternata ◽  
Bundle Sheath ◽  
Ultrastructural Changes ◽  
Selective Toxicity ◽  
Mesophyll Cells ◽  
Veinal Necrosis ◽  
Rough Lemon ◽  
The Matrix ◽  
In Cells

A pathotype of A. alternata with selective pathogenicity to rough lemon produces two or more substances with selective toxicity to the host. The major toxin was extracted from culture fluids with ethyl acetate and purified by several different chromatographic procedures. Toxin (10 ng/mL, 25 μL) was applied to leaves; within 24 h, water congestion and veinal necrosis were evident. The first toxin-induced change detected by electron microscopy was in the mitochondria; toxin at 1 μg/mL caused swelling, reduction in numbers and vesiculation of cristae, and decreases in electron density of the matrix. At 1 h after toxin treatment, the percentages of affected mitochondria in cells of several tissues were 18 in bundle sheaths, 9 in mesophyll cells adjacent to bundle sheath, and 9% in mesophyll cells remote from sheath. The number of affected mitochondria increased with time, until nearly 100% were affected at 6 h. No effects on other organelles were evident at 6 h. No ultrastructural changes were evident in cells of resistant leaves. The same changes in mitochondria were observed in pathogen-inoculated susceptible but not in resistant leaves by 24 h after incubation. The data indicate that the initial site of toxin action may be in the mitochondria.

Phenolic Deposits and Kranz Syndrome in Leaf Tissues of Spotted (Euphorbia maculata) and Prostrate (Euphorbia supina) Spurge

Weed Science ◽  
1983 ◽  
Vol 31 (1) ◽  
pp. 131-136 ◽  
Author(s):  
C. Dennis Elmore ◽  
Rex N. Paul
Keyword(s):  
Electron Microscopy ◽  
Phenolic Compounds ◽  
Light And Electron Microscopy ◽  
Bundle Sheath ◽  
Fixation Technique ◽  
Mesophyll Cells ◽  
Kranz Anatomy ◽  
Bundle Sheath Cells ◽  
Leaf Tissues ◽  
Sheath Cells

Spotted spurge (Euphorbia maculataL.) and prostrate spurge (E. supinaRaf.), both in subgenusChamesyce,were examined by light and electron microscopy using a caffeine - fixation technique to sequester the phenolic pools intercellularly. Both species have typical dicotyledon-type Kranz anatomy. Sequestered phenolic pools were located in vacuoles in epidermal and mesophyll cells. Only in spotted spurge, however, were additional phenolic pools formed in bundle - sheath cells. This study was undertaken because allelopathy has been demonstrated in prostrate spurge and because phenolic compounds have been implicated in allelopathy. These results would indicate that spotted spurge should also be allelopathic.

Étude ultrastructurale des modifications induites par Exserohilum turcicum chez le limbe de Zea mays – Effet du gène de résistance Ht-1

1987 ◽  
Vol 65 (10) ◽  
pp. 2061-2066
Author(s):  
B. Gélie ◽  
M. Petitprez ◽  
A. Souvre ◽  
L. Albertini
Keyword(s):  
Zea Mays ◽  
Comparative Study ◽  
Inbred Lines ◽  
Bundle Sheath ◽  
Ultrastructural Changes ◽  
Exserohilum Turcicum ◽  
Mesophyll Cells ◽  
Isogenic Lines ◽  
Bundle Sheath Cells ◽  
Cellular Components

Ultrastructural changes induced by Exserohilum turcicum (Pass.) Leonard et Suggs in maize leaf cells are observed 24 to 72 h after inoculation, in a comparative study between two isogenic lines with or without the Ht-1 gene. In the susceptible plants (without Ht-1), the plasmalemma and the tonoplast of the mesophyll cells are the first cellular components altered, followed by disorganisation and alteration of organelles, which become scattered throughout the cell. Chloroplasts in particular seem to be very sensitive to the toxic action of the pathogen, which causes disruption of their envelope and grana. Bundle sheath cells are altered later and to a lesser extent than the mesophyll cells. In Ht-1 monogenic resistant inbred lines, cytoplasmic residues of prematurely dead cells surround healthy mesophyll cells protecting them and stimulating their activity and resulting in stabilization of the pathotoxic process 36 to 48 h after inoculation.

Cytopathology and ultrastructure of mild and severe strains of maize chlorotic dwarf virus in maize and johnsongrass

1993 ◽  
Vol 71 (5) ◽  
pp. 718-724 ◽  
Author(s):  
E. D. Ammar ◽  
R. E. Gingery ◽  
L. R. Nault
Keyword(s):  
Electron Microscopy ◽  
Uranyl Acetate ◽  
Dwarf Virus ◽  
Mesophyll Cells ◽  
White Stripe ◽  
Cytoplasmic Inclusions ◽  
Maize Leaves ◽  
Maize Chlorotic Dwarf Virus ◽  
In Cells

In maize leaves experimentally infected with various isolates or strains of maize chlorotic dwarf virus, including a newly characterized strain (M1), and in naturally infected johnsongrass, only two types of cytoplasmic inclusions were consistently observed: (i) quasi-spherical electron-dense granular inclusions, and (ii) curved or straight bundles of fibrous inclusions. Both types were detected by light and (or) electron microscopy in vascular parenchyma and phloem cells, and less frequently in bundle-sheath and adjacent mesophyll cells. The dense granular inclusions usually contained numerous isometric virus-like particles, some of which may have been released into the surrounding cytoplasm. However, a high proportion of these inclusions in cells infected with the mild type strain and a type-like isolate (M8) were either devoid of or contained very few viruslike particles. In maize leaves infected with the white stripe (WS) isolate, the chloroplasts were markedly deformed; in leaves of stunted plants doubly infected with M8 and the serologically distinct M1 strain, some phloem cells appeared degenerated. Electron microscopy of preparations of purified M1 stained with uranyl acetate revealed both stain-impenetrable full particles and stain-penetrable empty or partially empty particles. Both full and apparently empty particles were also found in cells of maize leaves infected with M1, whereas with other strains and isolates, mainly full particles were found both in situ and in vitro. Key words: maize chlorotic dwarf virus, cytopathology, ultrastructure, maize, johnsongrass.

Changes in the plastid ultrastructure during greening in cultured soybean cells

1989 ◽  
Vol 47 ◽  
pp. 1010-1011
Author(s):  
M.A. Gillott ◽  
G. Erdös ◽  
D. E. Buetow
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gene Regulation ◽  
Uranyl Acetate ◽  
Total Darkness ◽  
Ultrastructural Changes ◽  
Ethanol Dehydration ◽  
Mesophyll Cells ◽  
Plastid Ultrastructure ◽  
Transmission Electron

Mesophyll cells isolated from soybeans (Glycine max, L. Merr. var. Corsoy) can be grown photoautotrophically in suspension culture. The SB-P cell line can be bleached by maintaining them in total darkness in sucrose supplemented media for several weeks, and will regain photosynthetic competency when returned to the light. This system is ideally suited for the study of gene regulation and the biochemical and ultrastructural changes which occur during the greening process.Cells were fixed for electron microscopy after 8 weeks of growth in total darkness and at intervals of 1 h to 12 d after transfer to the light. Chlorophyll measurements were determined for each sample. For transmission electron microscopy, the cells were fixed for 1-2 h in 4% glutaraldehyde in 0.1M Pipes buffer, pH 7.4, washed in the same buffer, then postfixed for 1 h in 1% OsO4 in Pipes, pH 6.8. Following a graded ethanol dehydration series the cells were transferred into propylene oxide and embedded in Epon. Sections were stained with uranyl acetate and observed on a JEOL 100C TEM operated at 80 kV.

Cytological Effects of Ultra-High Temperatures on Corn

Weed Science ◽  
1973 ◽  
Vol 21 (4) ◽  
pp. 299-303 ◽  
Author(s):  
T. C. Ellwanger ◽  
S. W. Bingham ◽  
W. E. Chappell ◽  
S. A. Tolin
Keyword(s):  
Electron Microscopy ◽  
Zea Mays ◽  
High Temperatures ◽  
Light Microscope ◽  
Osmium Tetroxide ◽  
Bundle Sheath ◽  
Membrane Systems ◽  
Mesophyll Cells ◽  
Bundle Sheath Cells ◽  
Sheath Cells

Corn (Zea mays L. ‘Funk's G-83’) seedling leaves exposed to flame-generated ultra-high temperatures produced in flame cultivation were fixed in glutaraldehyde, post fixed in osmium tetroxide, and embedded in Araldite. In the light microscope, bundle sheath cells of flamed tissue were more heavily stained with Azure II and less vacuolated than were nonflamed cells. Heated mesophyll cells contained swollen, disrupted, and granular chloroplasts. Examination of flamed tissue by electron microscopy revealed granular, dispersed cytaplasm and altered membrane systems. Chloroplast lamellar systems and envelopes, tonoplasts, and plasmalemmas were disintegrated in both bundle sheath and mesophyll cells.

Ultrastructural changes associated with induced systemic resistance of cucumber to disease: host response and development of Colletotrichum lagenarium in systemically protected leaves

1988 ◽  
Vol 66 (6) ◽  
pp. 1028-1038 ◽  
Author(s):  
X. L. Xuei ◽  
U. Järlfors ◽  
J. Kuć
Keyword(s):  
Electron Microscopy ◽  
Host Cell ◽  
Host Response ◽  
Structural Changes ◽  
Induced Systemic Resistance ◽  
Light And Electron Microscopy ◽  
Systemic Resistance ◽  
Ultrastructural Changes ◽  
Mesophyll Cells ◽  
Before And After

Systemic resistance to anthracnose caused by Colletotricum lagenarium was induced in cucumber by inoculation with fungal conidia. Control and immunized leaves were examined by both light and electron microscopy before and after subsequent challenge with the fungus. Penetration through the epidermal wall was evident 36 h after challenge and was followed by hyphal proliferation and host-cell destruction in control tissues. Penetration was rarely seen in immunized tissues before 72 h, but at 24 h, invaginations of the appressorial wall were observed, as well as highly electron opaque epidermal walls beneath the appressoria. At 72 h, thin penetration pegs were seen within the dense host wall, and at 96 h, the peg was embedded within the underlying papilla and aggregates of callose-like material. Penetration through the epidermis was rare in immunized tissue, but when it was observed, development appeared to be similar to that in control leaves. Evidence is presented to show that ultra-structural changes in immunized tissues as well as in the fungus occur within 24 h after challenge of the host. There appears to be a correlation between the comparatively few lesions observed macroscopically in immunized leaves and the sparsity of successful penetrations into host mesophyll cells.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Ultrastructural Changes of Canine Kidneys During 24-Hour Perfusion on a LI-400 Preservation System

1971 ◽  
Vol 29 ◽  
pp. 316-317
Author(s):  
M. O. Magnusson ◽  
D. G. Osborne ◽  
T. Shimoji ◽  
W. S. Kiser ◽  
W. A. Hawk
Keyword(s):  
Electron Microscopy ◽  
Electrolyte Solution ◽  
Ultrastructural Changes ◽  
Midline Incision ◽  
Short Term ◽  
Pentobarbital Anesthesia ◽  
Pulsatile Perfusion

Short term experimental and clinical preservation of kidneys is presently best accomplished by hypothermic continuous pulsatile perfusion with cryoprecipitated and millipore filtered plasma. This study was undertaken to observe ultrastructural changes occurring during 24-hour preservation using the above mentioned method.A kidney was removed through a midline incision from healthy mongrel dogs under pentobarbital anesthesia. The kidneys were flushed immediately after removal with chilled electrolyte solution and placed on a LI-400 preservation system and perfused at 8-10°C. Serial kidney biopsies were obtained at 0-½-1-2-4-8-16 and 24 hours of preservation. All biopsies were prepared for electron microscopy. At the end of the preservation period the kidneys were autografted.

The Structure and Development of Microbodies in the Fat Body and other Tissues of an Insect (Calpodes Ethlius)

1970 ◽  
Vol 28 ◽  
pp. 148-149
Author(s):  
M. Locke ◽  
J. T. McMahon
Keyword(s):  
Electron Microscopy ◽  
Liquid Crystals ◽  
Fat Body ◽  
Competitive Inhibitor ◽  
Dense Core ◽  
Urate Oxidase ◽  
Blood Proteins ◽  
Free Base ◽  
The Core ◽  
The Matrix

The fat body of insects has always been compared functionally to the liver of vertebrates. Both synthesize and store glycogen and lipid and are concerned with the formation of blood proteins. The comparison becomes even more apt with the discovery of microbodies and the localization of urate oxidase and catalase in insect fat body.The microbodies are oval to spherical bodies about 1μ across with a depression and dense core on one side. The core is made of coiled tubules together with dense material close to the depressed membrane. The tubules may appear loose or densely packed but always intertwined like liquid crystals, never straight as in solid crystals (Fig. 1). When fat body is reacted with diaminobenzidine free base and H2O2 at pH 9.0 to determine the distribution of catalase, electron microscopy shows the enzyme in the matrix of the microbodies (Fig. 2). The reaction is abolished by 3-amino-1, 2, 4-triazole, a competitive inhibitor of catalase. The fat body is the only tissue which consistantly reacts positively for urate oxidase. The reaction product is sharply localized in granules of about the same size and distribution as the microbodies. The reaction is inhibited by 2, 6, 8-trichloropurine, a competitive inhibitor of urate oxidase.

Effect of Acetone and Kerosene on Skin Ultrastructure

1972 ◽  
Vol 30 ◽  
pp. 92-93
Author(s):  
A. P. Lupulescu ◽  
H. Pinkus ◽  
D. J. Birmingham
Keyword(s):  
Electron Microscopy ◽  
Human Skin ◽  
Osmium Tetroxide ◽  
Human Epidermis ◽  
Ultrastructural Changes ◽  
Chemical Agents ◽  
Skin Ultrastructure ◽  
Volar Surface

Our laboratory is engaged in the study of the effect of different chemical agents on human skin, using electron microscopy. Previous investigations revealed that topical use of a strong alkali (NaOH 1N) or acid (HCl 1N), induces ultrastructural changes in the upper layers of human epidermis. In the current experiments, acetone and kerosene, which are primarily lipid solvents, were topically used on the volar surface of the forearm of Caucasian and Negro volunteers. Skin specimens were bioptically removed after 90 min. exposure and 72. hours later, fixed in 3% buffered glutaraldehyde, postfixed in 1% phosphate osmium tetroxide, then flat embedded in Epon.

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