Effect of Ethanol on Cytological Changes Induced by Salt Load in Nucleus Supraopticus of Rat.

Much recent attention has been focused on vegetative survival forms of planktonic diatoms and other algae. There are several reports of extended vegetative survival of the freshwater diatom Melosira in lake sediments. In contrast to those diatoms which form a morphologically distinct resistant spore, Melosira is known to produce physiological resting cells that are indistinguishable in outward morphology from actively growing cells.We used both light and electron microscopy to document and elucidate the sequence of cytological changes during the transition from resting cells to actively growing cells in a population of Melosira granulata from Douglas Lake, Michigan sediments collected in mid-July of 1983.

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High-pressure freezing and freeze substitution of teliospores of the rust fungus Gymnosporangium clavipes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100161011 ◽

1990 ◽

Vol 48 (3) ◽

pp. 692-693

Author(s):

Robert W. Roberson

Keyword(s):

High Pressure ◽

Room Temperature ◽

Pathogenic Fungus ◽

Rust Fungus ◽

Freeze Substitution ◽

Ice Crystals ◽

High Pressure Freezing ◽

Thin Walled Structures ◽

Cytological Changes ◽

Dextran Solution

The use of cryo-techniques for the preparation of biological specimens in electron microscopy has led to superior preservation of ultrastructural detail. Although these techniques have obvious advantages, a critical limitation is that only 10-40 μm thick cells and tissue layers can be frozen without the formation of distorting ice crystals. However, thicker samples (600 μm) may be frozen well by rapid freezing under high-pressure (2,100 bar). To date, most work using cryo-techniques on fungi have been confined to examining small, thin-walled structures. High-pressure freezing and freeze substitution are used here to analysis pre-germination stages of specialized, sexual spores (teliospores) of the plant pathogenic fungus Gymnosporangium clavipes C & P.Dormant teliospores were incubated in drops of water at room temperature (25°C) to break dormancy and stimulate germination. Spores were collected at approximately 30 min intervals after hydration so that early cytological changes associated with spore germination could be monitored. Prior to high-pressure freezing, the samples were incubated for 5-10 min in a 20% dextran solution for added cryoprotection during freezing. Forty to 50 spores were placed in specimen cups and holders and immediately frozen at high pressure using the Balzers HPM 010 apparatus.

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Cytological changes induced by platinum-thymine in sarcoma-180 cells: Electron microscopy study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015900x ◽

1990 ◽

Vol 48 (3) ◽

pp. 290-291

Author(s):

Gustav Ofosu

Keyword(s):

Mammalian Cells ◽

Antitumor Agent ◽

Microscopy Study ◽

Electron Microscopy Study ◽

Limiting Factor ◽

Sarcoma 180 ◽

Electron Microscopic ◽

Cytological Changes

Platinum-thymine has been found to be a potent antitumor agent, which is quite soluble in water, and lack nephrotoxicity as the dose-limiting factor. The drug has been shown to interact with DNA and inhibits DNA, RNA and protein synthesis in mammalian cells in vitro. This investigation was undertaken to elucidate the cytotoxic effects of piatinum-thymine on sarcoma-180 cells in vitro ultrastructurally, Sarcoma-180 tumor bearing mice were treated with intraperitoneal injection of platinum-thymine 40mg/kg. A concentration of 60μg/ml dose of platinum-thymine was used in in vitro experiments. Treatments were at varying time intervals of 3, 7 and 21 days for in vivo experiments, and 30, 60 and 120 min., 6, 12, and 24th in vitro. Controls were not treated with platinum-thymine.Electron microscopic analyses of the treated cells in vivo and in vitro showed drastic cytotoxic effect.

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