Morphology and zoospore ultrastructure of Lacustromyces hiemalis gen. et sp.nov. (Chytridiales)

1993 ◽  
Vol 71 (3) ◽  
pp. 414-425 ◽  
Author(s):  
Joyce E. Longcore
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Key Words ◽  
Microtubule Organizing Center ◽  
Baseline Study ◽  
Zoosporic Fungus ◽  
Lipid Globule ◽  
Transmission Electron ◽  
Organizing Center ◽  
Thin Walled

As part of a baseline study of chytridiomycete fungi in two Maine lakes, a polycentric, chitinophilic, and heretofore undescribed zoosporic fungus was found. The tubular thallus of Lacustromyces hiemalis gen. et sp.nov. has intercalary thin-walled zoosporangia, has thick-walled resistant sporangia, and does not grow at temperatures greater than 23 °C. Transmission electron microscopy revealed that its zoospores are a variant of the chytridialean type. The microbody – lipid globule complex is of a previously undescribed type, lacking a rumposome or other membrane cisterna and consisting of multiple lipid globules enclosed in a microbody that extends towards the kinetosome. Three kinds of microtubule roots arise near the kinetosome, a root leading to the microbody, a ribosomal root, and a microtubule organizing center that gives rise to microtubules that extend singly into the cytoplasm. Key words: Chytridiales, fungus, Lacustromyces, lake, ultrastructure, zoospore.

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.

Microsporogenesis in Amelanchier alnifolia: sporogenous cells, microsporocytes, and tetrads

2005 ◽  
Vol 83 (9) ◽  
pp. 1106-1116 ◽  
Author(s):  
Michael J. Sumner ◽  
William R. Remphrey
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Walls ◽  
Developmental Changes ◽  
Bright Field ◽  
Peripheral Cell ◽  
Amelanchier Alnifolia ◽  
Transmission Electron ◽  
Wall Materials ◽  
Thin Walled

As part of an overall program aimed at increasing our knowledge of the male reproductive system of Amelanchier alnifolia Nutt., this study documents structural and developmental changes that occur in the sporogenous cells, microsporocytes, and tetrads of microspores during microsporogenesis using general cytochemical techniques in conjunction with bright field, fluorescence, and transmission electron microscopy. The sporogenous cells are thin walled and stain positively for β-1,4-glucans, pectic acids, and cellulose, but not callose. At the microsporocyte and tetrad stages of microsporogenesis, thick walls develop and stain positively for β-1,4-glucans (hemicelluloses but not cellulose), pectic acids, and callose. Thus, the eventual release of maturing microspores from the tetrads requires the digestion of all three of these carbohydrate wall materials. Postmeiotic cytokinesis is of the simultaneous type and is initiated when Golgi vesicles aggregate simultaneously into a network of cylindrical tubules in both central and peripheral cell locations of the coenocytic tetrad. Eventually, this network fuses to form the new cell walls within the microspore tetrad.

Ultrastructural diagnosis of renal oncocytoma

1992 ◽  
Vol 50 (1) ◽  
pp. 626-627
Author(s):  
Shirley Siew ◽  
Mehboob Fatteh
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Blood Vessels ◽  
Renal Tumors ◽  
Renal Oncocytoma ◽  
Luminal Surface ◽  
Transmission Electron ◽  
Granular Cytoplasm ◽  
Retrograde Pyelogram ◽  
Thin Walled

Renal oncocytoma is a comparatively rare tumor, having an incidence 1/20th that of renal cell carcinoma, from which it has to be differentiated. We report a case of a 61 year old man who was found to have albuminuria 100 mg/dL on a routine physical examination. A retrograde pyelogram showed splaying of the right upper pole infundibula. Two right renal tumors were shown on renal CT scan and there were multiple hypervascular masses on angiography. A right radical nephrectomy was performed. The kidney weighed 176 grains and measured 11 × 7.5 × 5 cm. There were several dark brown nodules in the upper pole, lower pole and midportion of the kidney. Some of the nodules protruded onto the cortical surface, stretching the overlying capsule, but, there was no evidence of capsular nor renal vein invasion. The largest nodule measured 4.5 × 4 × 4 cm. Histologic examination showed a distinct line of demarcation between the tumors and the normal kidney. Occasional thickened vessels were noted at the border. For the greater part, the tumor showed a tubular or acinar architecture, although the lumina of some of the tubules were narrow. The tubules were lined by large, polygonal eosinophilic cells with a granular cytoplasm. There was no evidence of nuclear atypicality nor mitotic activity. Thin walled blood vessels were present between the tubules. Transmission electron microscopy showed the presence of irregular tubules, surrounded by a well formed basement membrane. The tubules were separated by thin walled blood vessels (Fig. 1). The luminal surface of the cells lacked microvilli – Nuclei were comparatively small and irregular in shape. Lysosomes were concentrated towards the luminal surface. There were occasional lipid vacuoles. The cytoplasm contained large numbers of mitochondria with membranous cristae (Fig. 2) . These ultrastructural characteristics are in keeping with those of a renal oncocytoma. Comment: The term oncocyte1 is applied, at the light microscopic level, to large epithelial cells, which have a markedly eosinophilic and granular cytoplasm. Transmission electron microscopy shows the presence of an abundance of mitochondria filling the cytoplasm. Oncocytomas are tumors composed of a uniform population of such cells. Renal oncocytoma is considered to be a benign cortical adenoma. It has been postulated that it arises from proximal tubular epithelium. Features that distinguish renal oncocytoma from other adenomas are that they may reach a large size (7cm) and that they maybe multicentric in the same kidney (reported in 5% of cases). The dark brown bulging nodules present in our case are typical of the gross appearance of renal oncocytoma. Various theories have been proposed to account for the marked increase of mitochondria, including that it is due to a neoplastic proliferation of them, at the expense of other subcellular organelles. The diagnosis of oncocytoma is established by the ultrastructural demonstration of the abnormal abundance of mitochondria.

Electron microscopic study of oospore maturation and germination in an emasculate isolate of Saprolegnia ferax. 1. Gross changes

1980 ◽  
Vol 58 (2) ◽  
pp. 182-194 ◽  
Author(s):  
Gordon W. Beakes
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Microscopic Study ◽  
Electron Microscopic ◽  
Saprolegnia Ferax ◽  
Transmission Electron ◽  
Cytological Changes ◽  
Thin Walled ◽  
Germ Tubes ◽  
Peripheral Cytoplasm

The main morphological and cytological changes which accompany oospore maturation and germination in an emasculate isolate of Saprolegnia ferax have been followed by light and transmission electron microscopy. Oospore development proved similar to that described in antheridiate species except for the absence of motile granules within the central ooplast vacuole. Germination followed within a few days of maturation although it did not occur synchronously within a single oogonium. The ending of dormancy is indicated by a thinning of the oospore wall and a decrease in cytoplasmic refractivity. A new germination wall is secreted around the protoplast and the contents of the central ooplast break down and are partially dispersed into the peripheral cytoplasm as it becomes transformed into a typical somatic vacuole. Oospores swell slightly before the emergence of between one and four germ tubes. These often grow extensively within the oogonium, occasionally infesting and possibly parasitizing neighbouring germlings, before rupturing either the thin-walled pits or basal septa. After emergence most germ tubes continue to grow vegetatively in a sparsely branched fashion, although a few develop terminal sporangia. Oospore germination in this isolate is compared with that described in other oomycete species.

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

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)  

Comparison between conidial development in Sporendocladia bactrospora and Phialocephala virens

1993 ◽  
Vol 71 (7) ◽  
pp. 985-991 ◽  
Author(s):  
Marnel Mouton ◽  
Michael J. Wingfield
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fluorescence Microscopy ◽  
Key Words ◽  
Conidiogenous Cell ◽  
Secretory Vesicles ◽  
Bright Field ◽  
Transmission Electron ◽  
Building Activity ◽  
Conidial Development

Conidium development was studied and compared in Sporendocladia bactrospora (thought to resemble Chalara spp.) and in Phialocephala virens. Techniques used in the study include bright field and fluorescence microscopy, as well as scanning and transmission electron microscopy. Sporendocladia bactrospora had cylindrical conidia produced in true chains from phialidic conidiogenous cells with long cylindrical collarettes. An area of wall building activity at the base of the conidiogenous cell was characterized by secretory vesicles indicating ring wall building development. In Phialocephala virens, conidia were formed by apical wall building and distinct periclinal thickening was evident. From this study it was possible to confirm the fact that Phialocephala s.l. can clearly be divided into two distinct groups on the basis of conidium development. Key words: apical wall building, conidiogenesis, Phialocephala, ring wall building, Sporendocladia.

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.

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