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R F BEERS

Publications and source records attributed to R F BEERS.

At least 19 recordsLinked to original sources
PubMed1965

NONPHOTOREACTIVATING REPAIR OF ULTRAVIOLET LIGHT-DAMAGED MICROCOCCUS LYSODEIKTICUS CELLS.

Elder, Robert L. (Johns Hopkins University, Baltimore, Md.), and Roland F. Beers, Jr. Nonphotoreactivating repair of ultraviolet light-damaged Micrococcus lysodeikticus cells. J. Bacteriol. 89:1225-1230. 1965.-Micrococcus lysodeikticus cells are highly resistant to ultraviolet radiation. The shape of the dose-survival curve is consistent with the presence of a repair mechanism. The presence of nontoxic doses of dinitrophenol (0.1 mm) or iodoacetate (1 mm) before or after radiation decreases the survival number and the initial lag in the dose-kill curve. The extent of decrease in survival after postradiation treatment with these compounds is dependent upon both time and temperature. Organisms that survive radiation show a prolonged lag phase before multiplying. No photoreactivation of the radiated cells can be demonstrated. Ultraviolet-radiated phage show a higher inactivation when plated on host cells of M. lysodeikticus treated with dinitrophenol at concentrations which do not affect the infectivity of nonradiated phage. The resistance of these cells to ultraviolet radiation is the result of a very efficient dark-cell repair mechanism that can be blocked by iodoacetate or dinitrophenol.

Bacteriophages↗
PubMed1964

ACRIDINE ORANGE BINDING BY MICROCOCCUS LYSODEIKTICUS.

Beers, Roland F., Jr. (Johns Hopkins University, Baltimore, Md). Acridine orange binding by Micrococcus lysodeikticus. J. Bacteriol. 88:1249-1256. 1964.-Micrococcus lysodeikticus cells bind acridine orange (AO) reversibly. The adsorption isotherm is consistent with a highly cooperative-type binding similar to that observed with polyadenylic acid. The cells exhibit a strong buffering action on the concentration of free AO which remains constant (1 mug/ml) over a range from 5 to 95% saturation of the cells by AO. The cells stain either fluorescent orange or green. The fraction stained orange is directly proportional to the quantity of dye adsorbed, indicating that these cells bind a fixed amount of AO (10% of dry weight). The green-stained cells contain less than 1% of the AO bound to orange-stained cells. The results suggest that the abrupt increase in amount of AO bound by the orange-stained cells occurs when the concentration of free AO reaches a threshold concentration. Similar results were obtained with Bacillus cereus. Mg increases the free AO concentration and the extent of binding capacity of the cells.

Acridine Orange↗