Influences of cellular susceptibility to amphotericin B and of post-irradiation growth conditions on inactivation of Candida albicans by ultraviolet radiation.

Abstract

Earlier investigations have shown that inactivation of non-budding cells ofC. albicans by ultraviolet radiation is determined in part by (i) their post-irradiation incubation temperature, (ii) opportunity for exposure to long chain fatty acids or sterols and (iii) the nutri tional quality of their post-irraditation growth medium. These cultural conditions do not affect the viability of cells which are budding when irradiated nor the frequency of mutants among the survivors of irradiated, unbudded populations. Several lines of evidence have indicated that the post-irradiation growth conditions influence recoveries from non-genetic forms of uv-induced damage which are potentially lethal only for cells which are not in the process of division when irradiated. Studies reported here show that mutation to resistance to the polyene antibiotic, amphotericin B, changes the composite pattern of survival responses of uv treated unbudded cells to the three post-irradiation conditions. Acquisition of amphotericin B resistance does not alter the uv mutability of such cells nor the vulnerability of budding cells to uv inactivation. Differences in susceptibilities of cells to polyene antibiotics are known to be determined by differences in the composition and structural arrangement of their membranes. The present observations are consonant, therefore, with a previous proposal that post-irradiation temperature, nutrition and contact with lipid affect cellular recoveries from damages to processes which (i) are essential for initiation of cell division and (ii) are related to the organization of the cell membrane.