外源性一氧化氮对弓形虫速殖子凋亡的诱导作用

目的　探讨一氧化氮 (NO)是否能诱导弓形虫速殖子凋亡。方法　采用末端脱氧核苷酸转移酶(TdT)介导的原位末端标记法 (TUNEL)、透射电镜和琼脂糖凝胶电泳检测弓形虫速殖子凋亡的特征。结果　TUNEL标记法检测表明 ,NO供体亚硝基铁氰化钠 (SNP)可诱导弓形虫速殖子凋亡 ,并呈剂量和时间依赖性 ;NO清除剂 ,N 乙酰半胱氨酸能明显抑制SNP诱导的弓形虫速殖子凋亡 ;不含NO的SNP类似物 ,铁氰化钾不能诱导弓形虫速殖子凋亡。透射电镜下见SNP处理 15～ 2 0h的速殖子具有凋亡的典型形态学特征 :核染色质凝集、核固缩、核碎裂和凋亡小体形成。琼脂糖凝胶电泳显示SNP处理的弓形虫速殖子DNA片段呈现凋亡特征性的梯形条带。结论　从形态学和生化特征证明由SNP释出的NO可诱导弓形虫速殖子凋亡

Exogenous Nitric Oxide Induces Apoptosis in Tachyzoites of Toxoplasma gondii

Objective To explore whether NO is able to induce apoptosis in Toxoplasma gondii tachyzoites.Methods Apoptosis induced by NO in T.gondii tachyzoites was investigated by TUNEL (terminal-deoxynucleotidyl transferase mediated d-UTP nick end labeling ) method, electron microscopy and agarose gel electrophoresis. Results NO donor, sodium nitroprusside (SNP),was found to induce apoptosis in Toxoplasma gondii tachyzoites in a time- and dose-dependent manner by TUNEL detection. N-acetylcysteine, a NO scavenger, could inhibit SNP-induced apoptosis in the tachyzoites while potassium ferricyanide could not induce apoptosis in the tachyzoite. Electron macroscopy showed that SNP-treated tachyzoites possessed typical morphological features of apoptosis, including chromatin condensation below the nuclear membrane, nuclear pyknosis, and formation of apoptotic body.Agarose gel electrophoresis revealed that SNP-treated tachyzoite DNA fragment exhibited characteristic "DNA ladder" after 15 to 20 h. Conclusion SNP, NO donor, might induce apoptosis in T.gondii tachyzoites in terms of characteristic morphological and biochemical features.