. Electron microscopy; proceedings of the Stockholm Conference, September, 1956. Electron microscopy. A Study of the Division of Saccharomyces cerevisiae Using Carbon Replicas D. E. Bradley Research Laboratory, Associated Electrical Iiuhistries Limited, Aldermaston, Berkshire, England DECAUSE bacteria and similar organisms are dense to electrons, their surfaces cannot be satisfactorily studied by direct examination in the electron micro- scope. If the surface detail of the organisms is to be revealed, a replica technique must be employed. The most suitable method found so far uses evaporated c
. Electron microscopy; proceedings of the Stockholm Conference, September, 1956. Electron microscopy. A Study of the Division of Saccharomyces cerevisiae Using Carbon Replicas D. E. Bradley Research Laboratory, Associated Electrical Iiuhistries Limited, Aldermaston, Berkshire, England DECAUSE bacteria and similar organisms are dense to electrons, their surfaces cannot be satisfactorily studied by direct examination in the electron micro- scope. If the surface detail of the organisms is to be revealed, a replica technique must be employed. The most suitable method found so far uses evaporated carbon as a replicating material, (3), and is carried out as follows: A clean aqueous suspension of yeast cells is first pre- pared. This is most satisfactorily obtained from a liquid rather than a solid nutrient medium. Cells grown in 6°o malt extract solution were found to be free from con- taminating matter. Cultures were incubated for varying periods up to 72 hours at 33"C, and fixed for 30 minutes in 4 % formalin before being finally washed prior to replication. A single-stage replica technique was used in which the cell is coated with a layer of carbon and then dissolved away. The yeast cells were first dried down onto a thick formvar film mounted on an electron microscope speci- men support grid. It was found that a good dispersion could be obtained by spraying techniques, though there was a risk of damage to the yeast cells. The cells were next coated with a layer of carbon 150 to 200 A thick. It was then necessary to wash away the formvar substrate so that the yeast cells could be dissolved from the carbon replica. This was carried out by flowing a few ml of chloroform over the grid from a burette at the rate of 1 ml per minute. After the chloroform had the grid was immersed in a solution of 3 g of a mixture of potassium permanganate and dichromate in concen- trated sulphuric acid for fifteen minutes. After removal, it was washed in water, then in con
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