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Calcium and Hydrogen Ion Concentrations in the Parasitophorous Vacuoles of Epithelial Cells Infected with the Microsporidian Encephalitozoon hellem |
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| Authors: | GORDON J. LEITCH MARY SCANLON GOVINDA S. VISVESVARA SARA WALLACE |
| Affiliation: | Department of Physiology, Morehouse School of Medicine, Atlanta, Georgia 30310;Division of Parasitic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Public Health Service, U. S. Department of Health and Human Services, Atlanta, Georgia 30341 |
| Abstract: | ABSTRACT. Microsporidia of the genus Encephalitozoon undergo merogony and sporogony in a parasitophorous vacuole within the host cell. Cultured green monkey kidney cells infected with Encephalitozoon hellem were loaded with the fluorescent dyes fura-2 or BCECF in order to measure intracellular concentrations of calcium and hydrogen ions respectively. Both the parasitophorous vacuole calcium concentration and pH values resembled those of the host cell cytoplasm in infected cells. Calcein entered the parasitophorous vacuole but not other host cell vacuoles or parasite stages within the parasitophorous vacuole. The lack of a pH or calcium concentration gradient across the parasitophorous vacuole membrane and the permeability of this membrane to a large anion such as calcein suggest that the vacuole membrane surrounding E. hellem resembles that surrounding some other intracellular parasites such as Toxoplasma gondii. A potential role is discussed for the parasitophorous vacuole calcium concentration in germination in situ. |
| Keywords: | Microsporidia parasitophorous vacuole calcium parasitophorous vacuole pH spore germination vacuole membrane permeability |