Mechanisms involved in the photosensitized inactivation ofAcanthamoeba palestinensistrophozoites

Abstract

Aims: To advance our understanding of the mechanisms involved in the RLP068 phthalocyanine‐photosensitized inactivation of Acanthamoeba palestinensis trophozoites through a precise identification of the targets of the photoprocess in both the cytosolic and mitochondrial compartments. Methods and Results: We followed the activities of selected marker enzymes as well as we performed fluorescence and transmission electron microscopy investigations of the alterations induced by the photoprocess in the fine structure of subcellular compartments. RLP068 is preferentially located in the contractile vacuole: the fluorescence in that site is particularly evident in the unirradiated cells and becomes more diffused after irradiation. Electron microscopic analysis of photosensitized A. palestinensis cells clearly shows that the swelling of trophozoites and the appearance of vacuoles spread throughout the cytoplasm after phototreatment. The activity of a typical cytoplasmic enzyme, such as lactate dehydrogenase, underwent a 35% decrease as a consequence of the photoprocess, reflecting the photodamage induced by migrating phthalocyanine molecules in their micro‐environment. Conclusions: The presence of multiple targets for the phthalocyanine‐photosensitized process is of utmost importance because this pattern of cell damage makes it unlikely that photoresistant A. palestinensis strains are gradually selected or mutagenic phenomena are developed as a consequence of the photoinduced damage. Significance and Impact of the Study: Photosensitization via phthalocyanines appears to represent an efficient and safe approach for achieving a close control of the population of a potentially pathogenic protozoan such as A. palestinensis, opening new perspectives for the disinfection of microbiologically polluted waters.

Interaction of Talaromyces marneffei with free living soil amoeba as a model of fungal pathogenesis

“…The amoebae had more than one internalized fungal cell and individual fungal conidia in separate phagocytic vesicles indicating two independent phagocytic circumstances ( Figures 3A, B ). At 48 h infection, a swelling of amoeba cells was observed, which appear also devoid of pseudopodia indicating the impairment of osmotic balance ( Ferro et al., 2009 ). Moreover, the interaction of T. marneffei with the amoeba results in swelling of mitochondria and reduced the amoeba cytoplasmic electron density corresponding with amoeba cell injury ( Steenbergen et al., 2004 ), The extracellular yeast cell of T. marneffei was presented suggesting the A. castellanii cells lysis ( Figures 3C, D ).…”