The Zygorhynchus zygosporangium and zygospore

1978 ◽  
Vol 56 (8) ◽  
pp. 1061-1073 ◽  
Author(s):  
K. L. O'donnell ◽  
S. L. Flegler ◽  
J. J. Ellis ◽  
C. W. Hesseltine
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Wall Layer ◽  
Primary Wall ◽  
Wall Deposition ◽  
Transmission Electron ◽  
Inner Surface

Zygosporangium and zygospore formation in Zygorhynchus was followed by scanning and transmission electron microscopy. One or more slender, lateral zygophoric filaments proliferate from the subterminal portion of a septate, erect hypha. These lateral zygophoric branches recurve and conjugate with the stout, terminal zygophoric hypha. Heteromorphic gametangia are delimited asynchronously on either side of the fusion wall. Deposition of wart material on and within the inner primary wall layer is concomitant with fusion septum dissolution. The mature zygosporangial wall is composed of electron-opaque stellate, confluent warts with an elaborate ornamented inner surface. The potential taxonomic value of mature zygosporangium and zygospore topography in Zygorhynchus is examined.

Ultrastructural aspects of coated vesicles in tobacco protoplasts

1981 ◽  
Vol 59 (7) ◽  
pp. 1307-1313 ◽  
Author(s):  
P. van der Valk ◽  
L. C. Fowke
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plasma Membrane ◽  
Coated Vesicles ◽  
Thin Sections ◽  
Tobacco Protoplasts ◽  
Vesicle Membranes ◽  
Transmission Electron ◽  
Large Numbers ◽  
Inner Surface

The ultrastructure and distribution of coated vesicles in isolated tobacco protoplasts were investigated using transmission electron microscopy of thin sections of whole protoplasts and stained plasma membrane preparations obtained by osmotic bursting of protoplasts attached to coated microscope grids. Large numbers of coated vesicles were associated with both the plasma membrane and the maturing face of dictyosomes. Dictyosome associated coated vesicles were smaller and had less distinct coats and vesicle membranes than those associated with the plasma membrane. Honeycomb structures believed to be aggregations of coats were also associated with the inner surface of the plasma membrane. Our data suggest that coated vesicles are produced by the Golgi apparatus, fuse with the plasma membrane, their coats remaining attached, at least temporarily, to the plasma membrane inner surface.

Zygosporangium and zygospore formation in Phycomyces nitens

1978 ◽  
Vol 56 (1) ◽  
pp. 91-100 ◽  
Author(s):  
K. L. O'Donnell ◽  
S. L. Flegler ◽  
G. R. Hooper
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Secondary Wall ◽  
Wall Layer ◽  
Central Vacuole ◽  
Transmission Electron ◽  
Large Central Vacuole ◽  
Outer Primary

Zygosporangium and zygospore formation in Phycomyces nitens was followed by correlative light microscopy and scanning and transmission electron microscopy. Compatible multibranched zygophores became interlocked by the interdigitation of their lobes. Progametangia grew up from the substratum in pairs and then differentiated into gametangia and tongs-shaped suspensors. Plasmogamy was deferred until the gametangia were delimited. Development of rings of hyaline appendages on the suspensors was concomitant with plasmogamy. The appendages originated from the tertiary suspensor wall layer and ruptured the outer primary and secondary wall layers prior to development of their terminal thornlike processes.Developing zygosporangia contained a large central vacuole and some organelle zonation; however, these features were not discernible in more mature zygosporangia. A reticulum of electron-opaque fluted warts developed within the secondary zygosporangial wall layer. Cryofractured zygosporangia revealed a smooth hyaline zygospore with truncate ends. Wall layer relations of mature zygosporangia and zygospores were presented. Information obtained was correlated with existing ultrastructural observations on zygosporangiogenesis in the Mucorales.

Wound Tyloses in Robinia Pseudoacacia L.

IAWA Journal ◽  
1994 ◽  
Vol 15 (2) ◽  
pp. 157-160 ◽  
Author(s):  
Uwe Schmitt ◽  
Walter Liese
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Division ◽  
Robinia Pseudoacacia ◽  
Wall Thickening ◽  
Primary Wall ◽  
Transmission Electron ◽  
Mother And Daughter ◽  
Robinia Pseudoacacia L ◽  
Earlywood Vessels

The formation of tyloses in vessels of Robinia pseudoacacia L. after wounding was investigated by transmission electron microscopy. Some tyloses in earlywood vessels exhibit cell division. The young walls between mother and daughter tyloses with primary wall-like appearance evince plasmodesmata; pits develop simultaneously with wall thickening.

Mycoparasitism of teliospores of Ustilago bullata by an oomycete

1990 ◽  
Vol 68 (11) ◽  
pp. 2415-2421 ◽  
Author(s):  
Robert W. Roberson ◽  
E. S. Luttrell ◽  
Melvin S. Fuller
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Key Words ◽  
Enzymatic Degradation ◽  
Spore Wall ◽  
Wall Layer ◽  
Smut Fungus ◽  
Pythium Vexans ◽  
Transmission Electron ◽  
Host Parasite

The mycoparasitism of teliospores of the smut fungus Ustilago bullata was discovered by transmission electron microscopy (TEM). Large, multinucleate chlamydospores germinated, producing hyphae that directly penetrated the walls of mature teliospores after forming an appressorium-like structure. Invagination of the exosporium at the point of penetration suggested mechanical penetration of this outer spore wall layer. The inner endosporium layer was fibrillar in appearance, with irregular electron-transparent regions suggesting enzymatic degradation. The cytoplasm and endosporium of parasitized teliospores were completely disintegrated, leaving only the spiny exosporium layer distributed throughout the sorus. Hyphae of the mycoparasite emerged from the teliospore shell, and their tips penetrated surrounding teliospores. TEM characteristics of the parasite confirmed oomycetous affinities. Pythium vexans was isolated from smutted tissue collected at the same time as tissue used for TEM observations. Pythium vexans was able to parasitize U. bullata teliospores in culture. Key words: hyperparasitism, ultrastructure, smut, Pythium, host–parasite relationships, infection.

Ultrastructure of the dormant and germinating sporangiospore of Phascolomyces articulosus (Mucorales)

1978 ◽  
Vol 56 (7) ◽  
pp. 747-753 ◽  
Author(s):  
P. Jeffries ◽  
T. W. K. Young
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Freeze Fracture ◽  
Spore Wall ◽  
Wall Layer ◽  
Thin Sections ◽  
Transmission Electron ◽  
Sporangial Wall ◽  
Scanning Electron

Using results obtained with light and scanning electron microscopy of critical-point-dried material and transmission electron microscopy of carbon replicas and freeze-fracture and ultra-thin sections, the structure and germination of the sporangiospore of Phascolomyces articulosus Boedijn is described. The sporangial wall is trilaminate and the ornamented spore wall is two layered. During germination, a new wall layer develops between the plasmalemma and the original spore wall. Sporangial structure is related to that of other members of the Thamnidiaceae and the use of germinating spores of P. articulosus for infection studies of the mycoparasite Piptocephalis unispora is indicated.

Transmission electron microscopy of annellides and conidiogenesis in the synnematal hyphomycete Trichurus spiralis

1977 ◽  
Vol 55 (3) ◽  
pp. 233-244 ◽  
Author(s):  
Terrence M. Hammill
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Wall Layer ◽  
Nuclear Behavior ◽  
Transmission Electron ◽  
Formed Part

This study was done to compare events of conidiogenesis with previous studies done on the closely related genera Doratomyces and Scopulariopsis. Formation of the first conidium by a T. spiralis annellide was not observed. Conidial initials blew out through the annellide apex, increased in size, and were eventually delimited by centripetally developing septa. Each conidial-delimiting septum subsequently split; the distal layer formed part of the conidial base, and the proximal layer became a portion of the wall of the next conidial initial. A circumscissile rupture of the wall layer continuous between conidium and annellide produced the characteristic annellations and conidial basal frills. Annellations on T. spiralis were more conspicuous than on the two species of Doratomyces and the two species of Scopulariopsis previously studied with electron microscopy. Differences in nuclear behavior and other differences and similarities among the five species were discussed. The term holoblastic to describe conidiogenesis in annellides was questioned.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

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