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.

Ultrastructural and cytological observations of apothecial tissues of Geopyxis carbonaria (Pezizales, Ascomycetes)

1990 ◽  
Vol 68 (2) ◽  
pp. 243-257 ◽  
Author(s):  
James W. Kimbrough ◽  
Jack L. Gibson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Key Words ◽  
Mother Cell ◽  
Secondary Wall ◽  
Cell Stage ◽  
Wall Structures ◽  
Transmission Electron ◽  
Secondary Wall Formation ◽  
Characteristic Features

Cytological observations are made on apothecial tissues of Geopyxis carbonaria, using transmission electron microscopy. Characteristic features of both the medullary and ectal excipula are examined. Changes in ascus apex and wall structures are examined during ascus ontogeny, especially in relation to operculum position and structure. Ultrastructure of septum configuration is observed and compared in the excipulum, ascogenous hyphae, paraphyses, and at the base of young asci. Ascosporogenesis is observed from the ascus mother cell stage and initial spore delimitation until secondary wall formation. The cytological and ultrastructural observations on this species are discussed in relation to their possible taxonomic or phylogenetic value. Key words: ascosporogenesis, Discomycetes, ascospore ultrastructure, septal ultrastructure, cytochemistry.

Sporophytes, megaspores, and massulae of Azolla stanleyi from the Paleocene Joffre Bridge locality, Alberta

1994 ◽  
Vol 72 (3) ◽  
pp. 301-308 ◽  
Author(s):  
Georgia L. Hoffman ◽  
Ruth A. Stockey
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Key Words ◽  
Red Deer ◽  
The Other ◽  
Evolutionary Trends ◽  
Reproductive Structures ◽  
Transmission Electron ◽  
New Material

Several hundred vegetative and fertile specimens of Azolla Lam. have been recovered from the Paleocene Paskapoo Formation at the Joffre Bridge locality (Middle Tiffanian (Ti3) age) near Red Deer, Alberta. The spore complexes closely resemble those of the Paleocene A. stanleyi Jain & Hall, and the vegetative material is referred to that species. The specimens are unusually complete in that the remains of the fragile sporophyte are preserved, commonly with reproductive structures in place. Plants reaching up to 2.25 cm in length consist of alternately branched rhizomes bearing alternate, imbricate, sessile leaves. Leaves are ovate with entire margins, papillate surfaces, and a single midvein. Reproductive structures have been examined using light, scanning, and transmission electron microscopy. This new material is compared with the other Paleocene species for which sporophytes are known and discussed in terms of evolutionary trends for the genus. The specimens suggest that most of the vegetative characteristics of modern Azolla species were established by the middle Paleocene. Key words: Azolla, Salviniaceae, megaspore, massula, ultrastructure, Paleocene.

Electron microscopy study of the bacteria adherent to the rumen wall in young conventional lambs

1990 ◽  
Vol 36 (2) ◽  
pp. 140-144 ◽  
Author(s):  
Franoise Rieu ◽  
G. Fonty ◽  
Brigitte Gaillard ◽  
P. Gouet
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Epithelial Cell ◽  
Key Words ◽  
Bacterial Population ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Transmission Electron ◽  
Scanning Electron

The lamb rumen walls were rapidly colonized by an abundant bacterial population after birth. This colonization was examined by electron microscopy in neonatal conventional lambs. The sequence of establishment of the epimural species during the 3 weeks following birth, and the distribution of bacteria on the different sacs of the rumen, were examined by scanning electron microscopy. The population was very dense and consisted of a limited number of morphological types by 2 days after birth. Three types of rods were dominant at that time. The microflora was more complex 2 weeks later. Observations by transmission electron microscopy of desquamated epithelial cells revealed the presence of adherent bacteria that are surrounded by fibrous carbohydrate coats and sometimes partially enclosed by invaginations of the epithelial cell. Key words: rumen, lamb, microflora, scanning electron microscopy, adherence.

Fine structure of teliospores of the cedar-apple rust Gymnosporangium juniperi-virginianae

1975 ◽  
Vol 53 (6) ◽  
pp. 544-552 ◽  
Author(s):  
Charles W. Mims ◽  
Frank Seabury ◽  
E. L. Thurston
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Basal Cell ◽  
Spore Wall ◽  
Cellular Structures ◽  
Lipid Bodies ◽  
Germ Pore ◽  
Transmission Electron ◽  
Single Nucleus

Teliospores of the cedar-apple rust Gymnosporangium juniperi-virginianae were examined using transmission electron microscopy. Each ellipsoid spore is divided into two cells by a transverse septum. A second septum separates the basal cell of the teliospore from a long, hyaline, cylindrical pedicel. The fine structure of these septa is considered. The cytoplasm of the teliospore is very dense and contains a complement of cellular structures including ribosomes, vacuoles, mitochondria, and a large number of structures thought to be lipid bodies. Each cell of the teliospore contains a single nucleus, in which the chromatin is often considerably condensed. Two germ pore regions are present in each cell. The spore wall is thinnest in these regions and is different in structure than elsewhere around the spore.

LOCALIZATION OF RUMEN WALL-ADHERENT UREOLYTIC BACTERIA

1984 ◽  
Vol 64 (5) ◽  
pp. 60-61 ◽  
Author(s):  
R. J. C. McLEAN ◽  
J. W. COSTERTON ◽  
K.-J. CHENG
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Key Words ◽  
Histochemical Technique ◽  
Tissue Samples ◽  
Associated Bacteria ◽  
Transmission Electron ◽  
Ureolytic Bacteria

Treatment of rumen tissue samples with a newly developed histochemical technique for urease localization resulted in an electron dense reaction product deposition in several wall-associated bacteria. This represents the first instance in which ureolytic rumen wall-associated bacteria can be identified with transmission electron microscopy. Key words: Histochemical, rumen, urease, localization

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.

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.

scholarly journals Ultrastructure of sporophyte of Cladosiphon okamuranus Tokida (Ectocarpales, Phaeophyceae)

1970 ◽  
Vol 38 (2) ◽  
pp. 177-180 ◽  
Author(s):  
Qinghua Zhu ◽  
Xuecheng Zhang ◽  
KKIU Arunakumara
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Key Words ◽  
Hair Cells ◽  
Brown Algae ◽  
Lipid Bodies ◽  
Transmission Electron ◽  
Cladosiphon Okamuranus

Transmission Electron Microscopy of 35 day old culture of Cladosiphon okamuranus Tokida, revealed several chloroplasts and other organelles in each cell of assimilatory filaments. Each chloroplast possesses single pyrenoid and Lipid bodies while in hair cells, there were few chloroplasts clinging to plasma-membrane and many pathholes were seen in the cell wall. Key words: Cladosiphon okamuranus; Brown algae; Ultrastructure; Pathhole DOI: 10.3329/bjb.v38i2.5143 Bangladesh J. Bot. 38(2): 177-180, 2009 (December)  

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