Papilla response of barley epidermal cells caused by Erysiphe graminis: rate and method of deposition determined by microcinematography and transmission electron microscopy

1979 ◽  
Vol 57 (8) ◽  
pp. 898-913 ◽  
Author(s):  
Richard J. Zeyen ◽  
W. R. Bushnel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amorphous Material ◽  
Time Lapse ◽  
Epidermal Cells ◽  
Erysiphe Graminis ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Wall Appositions ◽  
Entire Sequence

Papillae were deposited in barley epidermal cells directly beneath appressoria of Erysiphe graminis f. sp. hordei and appeared as hemispherical, internal wall appositions. The papilla response began shortly after the formation of a rapidly moving cytoplasmic aggregate beneath the appressorium. As documented in coleoptile tissue by time-lapse light microcinematography, the papillae grew rapidly for 20–30 min after becoming visible, their radii increasing by 0.1 μm/min. For small papillae, deposition continued for about 30 min; for larger papillae, deposition continued for 120–180 min. Results with transmission electron microscopy on leaf epidermal cells suggested that papilla deposition by host cytoplasmic aggregates can be divided into four sequential stages: (i) the deposition of osmiophilic (lipidic) materials, (ii) the deposition and partial compaction of nonosmiophilic, amorphous material (probably insoluble polysaccharides), (iii) compaction of nonosmiophilic, amorphous material, and (iv) the incorporation of osmiophilic material into the host wall and into the compacted nonosmiophilic, amorphous material. At maturity, the papillae are hardened, electron-opaque wall appositions that may be effective in preventing fungal penetration and development. Failure of papillae to prevent fungal penetration and development may be related to the inability of the epidermal cells to complete the entire sequence of events in papilla deposition before attempted fungal penetration.

Structural Investigation of Photoluminescent Porous Si by Transmission Electron Microscopy

1992 ◽  
Vol 281 ◽  
Author(s):  
S. Shih ◽  
K. H. Jung ◽  
D. L. Kwong
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sample Preparation ◽  
Structural Investigation ◽  
Amorphous Material ◽  
Porous Si ◽  
Plan View ◽  
Mesh Structure ◽  
Transmission Electron ◽  
Minimal Damage

ABSTRACTWe have developed a new, minimal damage approach for examination of luminescent porous Si layers (PSLs) by transmission electron microscopy (TEM). In this approach, chemically etched PSLs are fabricated after conventional plan-view TEM sample preparation. A diffraction pattern consisting of a diffuse center spot, characteristic of amorphous material, is primarily observed. However, crystalline, microcrystalline, and amorphous regions could all be observed in selected areas. A crystalline mesh structure could be observed in some of the thin areas near the pinhole. The microcrystallite sizes were 15–150 Å and decreased in size when located further from the pinhole.

Dipetalonema viteae: ultrastructural study on the in vitro interaction between rat macrophages and microfilariae in the presence of IgE antibody

Parasitology ◽  
1981 ◽  
Vol 82 (1) ◽  
pp. 55-62 ◽  
Author(s):  
M. A. Ouaissi ◽  
A. Haque ◽  
A. Capron
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ultrastructural Study ◽  
Peritoneal Macrophages ◽  
Immune Serum ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Dipetalonema Viteae ◽  
In Vitro Interaction

SUMMARYThe in vitro interaction between rat peritoneal macrophages and Dipetalonema viteae microfilariae in the presence of amicrofilaraemic rat immune serum was studied by transmission electron microscopy. The probable sequence of events leading to the killing of D. viteae microfilaria by macrophages is as follows. (a) Rat peritoneal macrophages in the presence of amicrofilaraemic rat immune serum adhere to the parasite surface, (b) the macrophages extend their pseudopodia around the parasite, (c) the ‘lysosome-like’ granules discharge their contents on to the parasite surface, (d) the lytic activity of these products begins at the parasite surface and (e) subsequent breaking of the microfilarial cuticle occurs, exposing the parasite intracellular material.

A temperature-jump technique for time-resolved cryo-transmission Electron Microscopy

1989 ◽  
Vol 47 ◽  
pp. 742-743
Author(s):  
H. Chestnut ◽  
D. P. Siegel ◽  
J. L. Burns ◽  
Y. Talmon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Liquid Crystalline ◽  
Temperature Jump ◽  
Specimen Preparation ◽  
Thin Specimen ◽  
Time Resolved ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Focused Beam

Transmission electron microscopy of rapidly-frozen, hydrated specimens (cryo-TEM) is a powerful way of examining labile microstructures. This technique avoids some artifacts associated with conventional preparative methods. Use of a controlled environment vitrification system (CEVS) for specimen preparation reduces the risk of unwanted sample changes due to evaporation, and permits the examination of specimens vitrified from a defined temperature. Studies of dynamic processes with time resolution on the order of seconds, in which the process was initiated by changes in sample pH, have been conducted. We now report the development of an optical method for increasing specimen temperature immediately before vitrification. Using our method, processes that are regulated by temperature can be initiated in less than 500 msec on the specimen grid. The ensuing events can then be captured by plunge-freezing within an additional 200 msec.Dimyristoylphosphatidylcholine (DMPC) liposomes, produced by extrusion, were used as test specimens. DMPC undergoes a gel/liquid crystalline transition at 24°C, inducing a change in liposome morphology from polyhedral to spherical. Five-μl aliquots of DMPC dispersions were placed on holey-carbon-filmed copper grids mounted in the CEVS environmental chamber, and maintained at 6-8°C and 80% relative humidity. Immediately before the temperature jump most of the sample was blotted away with filter paper, leaving a thin specimen film on the grid. Upon pressing the trigger, an electronic control circuit generated this timed sequence of events. First, a solenoid-activated shutter was opened to heat the specimen by exposing it for a variable time to the focused beam of a 75W Xenon arc lamp. Simultaneously, a solenoid-activated cryogen shutter in the bottom of the CEVS was opened. Next, the lamp shutter was closed after the desired heating interval. Finally, a solenoid-activated cable release was used to trigger a spring-loaded plunger in the CEVS, propelling the sample into a reservoir of liquid ethane. Vitrified samples were subsequently transferred to a Zeiss EM902 TEM, operated in zero-loss brightfield mode, for examination at −163°C.

Egg morphology and hatching in Mormidea pictiventris (Hemiptera: Pentatomidae)

2001 ◽  
Vol 79 (4) ◽  
pp. 726-736 ◽  
Author(s):  
Klaus W Wolf ◽  
Walton Reid
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amorphous Material ◽  
Follicle Cells ◽  
Epifluorescence Microscopy ◽  
Stink Bug ◽  
Anterior Plate ◽  
Hexagonal Pattern ◽  
Transmission Electron ◽  
Egg Morphology

Egg morphology and hatching in the stink bug Mormidea pictiventris (Hemiptera: Pentatomidae) are described with the aid of scanning electron microscopy. In addition, the eggshell is analyzed using transmission electron microscopy and the distribution of follicle cells at the surface of ovarian eggs is studied by epifluorescence microscopy using a DNA-specific fluorescent dye. The surface of the barrel-shaped eggs carries numerous slender processes. Binucleate follicle cells, in most cases arranged in a hexagonal pattern, are responsible for the synthesis of this portion of the eggshell. The rim at the anterior pole of the egg is studded at irregular intervals with short columnar processes, the aero-micropylar processes. Hatching occurs at this pole. The prolarva is wrapped in an embryonic cuticle. Its head portion carries a Y-shaped element, the egg-burster. The major features of the inner face of the eggshell are subtle, radially oriented grooves at the anterior plate and a hexagonal pattern to the surface ornamentation throughout the remainder of the eggshell. Transmission electron microscopy revealed that the processes extending from the surface of the eggshell have a coarse texture, while the eggshell proper is composed of amorphous material. The innermost layer, however, has a trabecular organization. The findings in M. pictiventris are compared with morphological observations on the eggshell in other families of Hemiptera and suggestions are made concerning the meaning of the diverse structures.

Ciliary band formation in the doliolaria larva of Florometra

Development ◽  
1986 ◽  
Vol 96 (1) ◽  
pp. 303-323
Author(s):  
T. C. Lacalli ◽  
J. E. West
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Band Pattern ◽  
Ciliated Epithelium ◽  
Ciliary Band ◽  
Band Formation ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Direct Formation ◽  
Initial Pattern

The development of ciliary band pattern in the doliolaria larva of Florometra serratissima is described based on scanning and transmission electron microscopy. The uniformly ciliated epithelium of the post-hatching larva develops four regularly spaced bands over a period of approx. 20 h generating an epithelial pattern that is, essentially, a series of stripes. The first visible events of pattern formation progress over the larval surface in a posterior-to-anterior and dorsal-to-ventral sequence, but the initial pattern is not, in fact, striped. It instead consists of a close-packed array of oval interband domains separated and surrounded by belts of band cells. Secondarily the interband domains expand laterally and coalesce to form continuous, broad stripes, while the bands remain as narrow stripes between them. Two possible explanations for this unusual sequence of events are discussed: (1) that it can be understood in evolutionary terms with reference to band pattern in other echinoderm larvae, and (2) that it is a morphogenetic necessity because limitations inherent in the patterning mechanism prevent the direct formation of regular stripes.

Deformation under nanoindents in Si, Ge, and GaAs examined through transmission electron microscopy

2001 ◽  
Vol 16 (12) ◽  
pp. 3347-3350 ◽  
Author(s):  
S. J. Lloyd ◽  
J. M. Molina-Aldareguia ◽  
W. J. Clegg
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Amorphous Material ◽  
Face Centered Cubic ◽  
Dislocation Generation ◽  
Transmission Electron ◽  
Face Centered

Cross sections through nanoindents on Si, Ge, and GaAs {001} were examined through transmission electron microscopy. A focused ion beam workstation was used to machine electron transparent windows through the indents. In both Si and Ge there was a transformed zone immediately under the indent composed of amorphous material and a mixture of face-centered-cubic and body-centered cubic crystals. Cracking and dislocation generation were also observed around the transformed zone. In GaAs the dominant deformation mechanism was twinning on the {11} planes. The hardness of these materials is discussed in light of these observations and their macroscopic material properties such as phase transformation pressure.

Ionization-induced effects in amorphous apatite at elevated temperatures

2008 ◽  
Vol 23 (4) ◽  
pp. 962-967 ◽  
Author(s):  
In-Tae Bae ◽  
Yanwen Zhang ◽  
William J. Weber ◽  
Manabu Ishimaru ◽  
Yoshihiko Hirotsu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Elevated Temperatures ◽  
Amorphous Material ◽  
Transmission Electron ◽  
Oxygen Migration ◽  
Structural Contrast

Electron-beam-induced effects in preamorphized Sr2Nd8(SiO4)6O2 were investigated in situ using transmission electron microscopy with 200-keV electrons at temperatures ranging from 380 to 780 K. Within the electron-irradiated area, epitaxial recrystallization was observed from the amorphous/crystalline interface toward the surface, with the rate of recrystallization increasing as temperature increased from 380 to 580 K. Structural contrast features (i.e., O deficient amorphous material), as well as recrystallization, were observed outside of the irradiation area at temperatures from 680 to 780 K. Ionization-induced processes and local nonstoichiometry induced by oxygen migration and desorption are possible mechanisms for the electron-beam- induced recrystallization and for the formation of the structural contrast features, respectively.

scholarly journals Fine structure of the integument of Argas (Persicargas) persicus (Oken) (Ixodoidea: Argasidae)

2005 ◽  
Vol 16 (4) ◽  
Author(s):  
Ashraf Montasser ◽  
Amr Amin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Rough Endoplasmic Reticulum ◽  
Epidermal Cells ◽  
Argas Persicus ◽  
Dermal Glands ◽  
Transmission Electron ◽  
Surface Pores

The integument of Argas persicus was investigated using light, scanning and transmission electron microscopy. The study revealed that two layers, viz. an outer epicuticle and an inner procuticle, form the cuticle. The epicuticle includes wax, cuticulin and protein epicuticular layers. The wax layer carries numerous crater-like deposits, oval or circular discs and numerous infoldings. The procuticle contains an exo-, endo- and a subcuticle.Underlining the cuticle, flattened epidermal cells are connected via desmosomes and contain rough endoplasmic reticulum, free ribosomes and mitochondria. Scattered dermal glands are located beneath the cuticle and are continuous with the outside through dermal ducts and surface pores.

Histological observations of latent infection and tissue colonization by Diaporthe toxica in resistant and susceptible narrow-leafed lupins

1998 ◽  
Vol 76 (7) ◽  
pp. 1305-1316 ◽  
Author(s):  
M Shankar ◽  
W A Cowling ◽  
M W Sweetingham
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Frequency ◽  
Latent Infection ◽  
Epidermal Cells ◽  
Lupinus Angustifolius ◽  
Transmission Electron ◽  
Incompatible Reaction ◽  
Latent Phase

Latent infection and tissue colonization by Diaporthe toxica was examined by light, scanning, and transmission electron microscopy in stems, leaves, and petioles of resistant and susceptible narrow-leafed lupins (Lupinus angustifolius). Resistance was observed during the latent phase of the disease as an incompatible reaction between the host and pathogen that appeared to occur after penetration of the cuticle. Conidia were attached firmly to the cuticle by an extracellular substance presumably exuded from the conidia. Conidia penetrated the cuticle directly via an infection peg and formed subcuticular coralloid hyphae. The frequency of subcuticular coralloid hyphae was similar on stems, leaves, and petioles of each line. At 14 days after inoculation, resistant plants had a high frequency of small coralloid hyphae (10-80 µm length). The epidermal cells beneath these small coralloid hyphae appeared necrotic and collapsed with accumulation of polyphenolics and electron-dense substances and a loss of internal organisation in the cytoplasm. Necrosis was occasionally observed in small coralloid hyphae as well. Susceptible plants had a high frequency of large coralloid hyphae (80-400 µm length) in which intrahyphal hyphae were observed, and host epidermal cells beneath large coralloid hyphae appeared normal. Colonization of tissues below the cuticle began immediately after excision of stems from susceptible plants, but was delayed in resistant plants. At 8 days after excision, hyphae had invaded all stem tissues and initiated the formation of pycnidia in susceptible plants, but few hyphae were observed in stems of resistant plants.Key words: Diaporthe toxica, coralloid hyphae, Lupinus angustifolius, resistance.

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