Studies on the Protein Synthesis by Toxoplasma Gondii in Cell Free System.

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The main reason for studying Toxoplasma is to learn more about its behavior in hopes of subsequently discovering a method for controlling or eradicating the disease it causes. Despite intensive study by experimental infection of various animals and tissue cultures, relatively little is known about this parasite's requirements for infection, survival and growth in a host cell. Nutritional studies of this parasite are complicate by its obligate parasitic nature. They are hidden from view of most of their life cycle. The extra-host cellular stage of the parasite, namely tachyzoite, which is easily obtainable in quantity seemed to be inactive or depressed, if any, in its metabolic activity. We examined influences of extracellular ions on several cellular events of this parasite including regulation of internal pH, motility and infectivity. We also studied possible occurrence of incorporation of ^<35>S-methionine by the tachyzoites in cell-free medium with varying external ionic conditions. In the present report, external ionic conditions, mainly K^+ and C1^-, are discussed in terms of electrochemical H^+ gradients across the parasite's membrane for cellular events of the tachyzoite in cell-free medium. A successful application of metabolic radiolabelling of toxoplasma proteins by ^<35>S-methionine let us possible tracer experiments of this parasitic protozoon. This method may also useful for screening anti-toxoplasma agints.