Title

PHOTODYNAMIC RESPONSES IN RHODOTORULA GLUTINIS IN THE ABSENCE OF ADDED SENSITIZERS

Document Type

Article

Date of Original Version

1-1-1971

Abstract

Abstract— –The lethal effect of a continuous spectrum of light at wavelengths longer than 300 nm has been examined for the yeast Rhodotorula glutinis. A survival curve consisting of a shoulder, an exponential phase of death, and a “tailing off” phase was shown to occur when cells were irradiated in the absence of a sensitizing dye. An action spectrum showed that the portion of the light used for irradiation which is lethal to the cells lies between 310 and 430 nm. It was found that carotenoid pigments were not able to provide any protection against this endogenously photosensitized oxidation. Exponentially growing cells were the most sensitive to killing and, as cells approached and entered into the stationary phase of growth, they became more resistant until a constant level of sensitivity was reached. A primary temperature effect on the length of the shoulder prior to the death of the cell has been observed. The sensitivity was greatest at low temperatures with an optimum resistance occurring at 22.5°C and an increasing sensitivity occurring at higher temperatures. Various sites have been examined for cellular damage which might lead to the death of the cell. Damage was found to impair the function of the plasma‐lemma, the glycolytic and respiratory system, the nucleus, and to be observable cytologically. Copyright © 1971, Wiley Blackwell. All rights reserved

Publication Title

Photochemistry and Photobiology

Volume

13

Issue

3

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