Light and electron microscopic observations of sporangium formation in Albugo Candida (Peronosporales; Oomycetes)

1977 ◽  
Vol 55 (6) ◽  
pp. 730-739 ◽  
Author(s):  
Saeed R. Khan

The formation of sporangia in Albugo Candida was studied using light and scanning and transmission electron microscopy. Their mode of development is blastic and they are not formed by percurrent proliferation as previously suggested.

Author(s):  
Veronika Burmeister ◽  
R. Swaminathan

Porphyria cutanea tarda (PCT) is a disorder of porphyrin metabolism which occurs most often during middle age. The disease is characterized by excessive production of uroporphyrin which causes photosensitivity and skin eruptions on hands and arms, due to minor trauma and exposure to sunlight. The pathology of the blister is well known, being subepidermal with epidermodermal separation, it is not always absolutely clear, whether the basal lamina is attached to the epidermis or the dermis. The purpose of our investigation was to study the attachment of the basement membrane in the blister by comparing scanning with transmission electron microscopy.


1977 ◽  
Vol 55 (20) ◽  
pp. 2565-2573 ◽  
Author(s):  
Robert D. Slocum ◽  
Gary L. Floyd

The nature of the association between the basidiomycetous mycobiont and the blue-green phycobiont in two species of the tropical basidiolichen Dictyonema was investigated using Nomarski light optics and scanning and transmission electron microscopy. Although members of this family may exhibit either a homoiomerous or heteromerous type of thallus organization, the fungus–alga relationship at the cellular level is remarkably consistent. Scytonema filaments are intimately associated with appressorial hyphae of the mycobiont and with extensive intracellular hyphae, which appear to be unrelated to the basidiomycetous fungal symbiont. This is the first report of a lichen displaying an apparent dual fungal symbiosis with the algal host. Association with the intracellular fungus produces no discernible damage to the phycobiont and apparently does not interfere with the symbiosis involving the basidiomycetous fungus.


Clay Minerals ◽  
1985 ◽  
Vol 20 (2) ◽  
pp. 255-262 ◽  
Author(s):  
S. Mann ◽  
R. M. Cornell ◽  
U. Schwertmann

Aluminium-substituted goethites are found in many soils and can also be synthesised readily in the laboratory. In recent years, synthetic substituted goethites have been examined by various techniques including XRD, IR, TEM and dissolution kinetics (Thiel, 1963; Jonas & Solymar, 1970; Fey & Dixon, 1981; Fysh & Fredericks, 1983; Schulze & Schwertmann, 1984; Schwertmann, 1984). Transmission electron microscopy (TEM) studies have shown that as Al substitution rises above 10%, the goethite needles become shorter and also thicker in the a direction. Furthermore, crystals which at zero substitution consist of domains parallel to the c axis become less domainic with increasing Al substitution (Schulze & Schwertmann, 1984).


2004 ◽  
Vol 12 (1) ◽  
pp. 3-7
Author(s):  
Stephen W. Carmichael ◽  
Jon Charlesworth

The use of fluorescent probes is becoming more and more common in cell biology. It would be useful if we were able to correlate a fluorescent structure with an electron microscopic image. The ability to definitively identify a fluorescent organelle would be very valuable. Recently, Ying Ren, Michael Kruhlak, and David Bazett-Jones devised a clever technique to correlate a structure visualized in the light microscope, even a fluorescing cell, with transmission electron microscopy (TEM).Two keys to the technique of Ren et al are the use of grids (as used in the TEM) with widely spaced grid bars and the use of Quetol as the embedding resin. The grids allow for cells to be identified between the grid bars, and in turn the bars are used to keep the cell of interest in register throughout the processing for TEM. Quetol resin was used for embedding because of its low auto fluorescence and sectioning properties. The resin also becomes soft and can be cut and easily peeled from glass coverslips when heated to 70°C.


Author(s):  
Zhi-Peng Wu ◽  
Hui Zhang ◽  
Cailing Chen ◽  
Guanxing Li ◽  
Yu Han

Oxygen electrocatalysis involving the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays a vital role in cutting-edge energy conversion and storage technologies. In situ studies of the evolution of catalysts during oxygen electrocatalysis can provide important insights into their structure - activity relationships and stabilities under working conditions. Among the various in situ characterization tools available, in situ electron microscopy has the unique ability to perform structural and compositional analyzes with high spatial resolution. In this review, we present the latest developments in in situ and quasi-in situ electron microscopic techniques, including identical location electron microscopy, in situ liquid cell (scanning) transmission electron microscopy and in situ environmental transmission electron microscopy, and elaborate their applications in the ORR and OER. Our discussion centers on the degradation mechanism, structural evolution and structure - performance correlations of electrocatalysts. Finally, we summarize the earlier discussions and share our perspectives on the current challenges and future research directions of using in situ electron microscopy to explore oxygen electrocatalysis and related processes.


1997 ◽  
Vol 3 (S2) ◽  
pp. 245-246
Author(s):  
A.S. Kaprelyants ◽  
A.A. Kaprelyants ◽  
A.N. Reylan ◽  
R.K. Migunova

The aim of given investigation is to study the effect of cooling upon rat hepatocyte structure using transmission electron microscopic and computer morphometric methods. Ultrastructural and morphometrical characteristics of hepatocytes under liver cooling for various levels under in vivo and in vitro conditions were investigated. Vistar rats of 180-250 g were used in the experiment. Liver cooling (in vivo) was performed by means of original cryoapplicator with different probe temperature (1,2). Liver tissue for transmission electron microscopy was fixed in glutaraldehyde fixator on cocadylate buffer and OsO4. Dehydration was completed on acetone (3). Tissue embedding was done into the mixture of Epon/Araldite epoxy rasin. Ultrathin slices were contrasted by the method of Reinolds. Cell viewing and imaging were accomplished by electron microscope at accelerating power of 75kV.Morphometrical and stereometrical analysis was performed using the “Morpho-Tools” original computer system (c) 1994-1996 A.S. Kaprelyants, A.A. Kaprelyants, A.N. Reylan .


Author(s):  
Glenn Stoner

The purpose of this paper is to demonstrate the use of a method which reduces the sample preparation time for transmission electron microscopy studies to about one minute.The relatively simple procedure is as follows: When a sample is desired, place 1 mℓ test solution in a 2-5 mℓ container, add 0.1 mℓ of a solution of 0.3 mg/mℓ fibrinogen, immediately insert a 400 mesh E.M. grid held by forceps, withdraw immediately, blot (at the tweezer tip-grid contact point) with filter paper, blow dry with a lab drier, add one drop of stain (2% urinal acetate), blot and blow dry in the above manner. Then immediately insert in the pre-pump chamber of the E.M.The above process has been used by the author in a variety of biological applications, from studies of fibrin growth from fibrinogen to identification of unknown viruses. The accompaning figures for T4, bacteriophage are given simply to demonstrate the method.


1989 ◽  
Vol 79 (12) ◽  
pp. 585-594
Author(s):  
DJ McCarthy ◽  
N Abell ◽  
T Reed

In spite of the most vigorous efforts to intervene medically and surgically when peripheral vascular disease threatens a patient, amputation of the extremity may be the only option left to arrest the progression of the disease. In a previous study, the authors assessed amputations, examined gross pathology, and identified scanning electron microscopic features associated with atherosclerotic disease. In the present study, the authors discuss this disease in terms of conventional light microscopy and transmission electron microscopy.


2011 ◽  
Vol 120 (11) ◽  
pp. 713-721 ◽  
Author(s):  
Takehisa Saito ◽  
Tetsufumi Ito ◽  
Norihiko Narita ◽  
Takechiyo Yamada ◽  
Yasuhiro Manabe

Objectives: The aim of this study was to evaluate the mean number of regenerated fungiform taste buds per papilla and perform light and electron microscopic observation of taste buds in patients with recovered taste function after severing the chorda tympani nerve during middle ear surgery. Methods: We performed a biopsy on the fungiform papillae (FP) in the midlateral region of the dorsal surface of the tongue from 5 control volunteers (33 total FP) and from 7 and 5 patients with and without taste recovery (34 and 29 FP, respectively) 3 years 6 months to 18 years after surgery. The specimens were observed by light and transmission electron microscopy. The taste function was evaluated by electrogustometry. Results: The mean number of taste buds in the FP of patients with completely recovered taste function was significantly smaller (1.9 ± 1.4 per papilla; p < 0.01) than that of the control subjects (3.8 ± 2.2 per papilla). By transmission electron microscopy, 4 distinct types of cell (type I, II, III, and basal cells) were identified in the regenerated taste buds. Nerve fibers and nerve terminals were also found in the taste buds. Conclusions: It was clarified that taste buds containing taste cells and nerve endings do regenerate in the FP of patients with recovered taste function.


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