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

研究弓形虫的主要原因是更多地了解它的行为，希望随后发现一种控制或根除它引起的疾病的方法。尽管对各种动物和组织培养的实验感染进行了深入的研究，但对这种寄生虫在宿主细胞中的感染、生存和生长的要求知之甚少。这种寄生虫的专性寄生性质使其营养研究变得复杂。它们在生命周期的大部分时间里都被隐藏起来。寄生虫的寄主外细胞阶段，即速殖子，很容易获得数量，但似乎在代谢活动方面不活跃或受到抑制。我们研究了胞外离子对这种寄生虫的几种细胞事件的影响，包括对体内pH、运动性和传染性的调节。我们还研究了在不同的外离子条件下，速殖子在无细胞条件下掺入^&lt；35&gt；S蛋氨酸的可能性。在本报告中，讨论了外部离子条件，主要是K^+和C l^-，用跨越寄生虫膜的电化学H^+梯度来描述速殖子在无细胞介质中的细胞事件。S蛋氨酸代谢放射性标记弓形虫蛋白的成功应用，使我们有可能进行这种寄生原虫的示踪实验。该方法也可用于弓形虫抗体的筛选。

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.