Pfefferkorn E R, Pfefferkorn L C
J Protozool. 1977 Aug;24(3):449-53. doi: 10.1111/j.1550-7408.1977.tb04774.x.
Radioactive uracil was not significantly incorporated into the nucleic acids of human fibroblast cells. Infection of these cells with Toxoplasma gondii resulted in an exponential increase in the rate of uracil incorporation that paralleled the exponential growth of the parasite. One day after infection the rate of uracil incorporation was increased 100-fold. It was established by autoradiography that all of the [3H] uracil was incorporated into the intracellular parasites. A possible explanation for this difference in ability to use uracil is our observation that the specific activity of uridine phosphorylase was 100-fold greater in partially purified parasites than in the host cell.
放射性尿嘧啶并未显著掺入人成纤维细胞的核酸中。用刚地弓形虫感染这些细胞后，尿嘧啶掺入率呈指数增长，这与寄生虫的指数生长平行。感染后一天，尿嘧啶掺入率增加了100倍。通过放射自显影确定，所有的[3H]尿嘧啶都掺入了细胞内的寄生虫中。对于这种利用尿嘧啶能力差异的一种可能解释是，我们观察到在部分纯化的寄生虫中尿苷磷酸化酶的比活性比宿主细胞中高100倍。
