Manger I D, Hehl A, Parmley S, Sibley L D, Marra M, Hillier L, Waterston R, Boothroyd J C
Department of Microbiology and Immunology, Stanford University, California 94305-5124, USA.
Infect Immun. 1998 Apr;66(4):1632-7. doi: 10.1128/IAI.66.4.1632-1637.1998.
Toxoplasma gondii is a protozoan parasite responsible for widespread infections in humans and animals. Two major asexual forms are produced during the life cycle of this parasite: the rapidly dividing tachyzoite and the more slowly dividing, encysted bradyzoite. To further study the differentiation between these two forms, we have generated a large number of expressed sequence tags (ESTs) from both asexual stages. Previously, we obtained data on approximately 7,400 ESTs from tachyzoites (J. Ajioka et al., Genome Res. 8:18-28, 1998). Here, we report the results from analysis of approximately 2,500 ESTs from bradyzoites purified from the cysts of infected mice. We also report the results from analysis of 760 ESTs from parasites induced to differentiate from tachyzoites to bradyzoites in vitro. Comparison of the data sets from bradyzoites and tachyzoites reveals many previously uncharacterized sequence clusters which are largely or completely specific to one or other developmental stage. This class includes a bradyzoite-specific form of enolase. Combined with the previously identified bradyzoite-specific form of lactate dehydrogenase, this finding suggests significant differences in flux through the lower end of the glycolytic pathway in this stage. Thus, the generation of this data set provides valuable insights into the metabolism and growth of the parasite in the encysted form and represents a substantial body of information for further study of development in Toxoplasma.
刚地弓形虫是一种原生动物寄生虫，可导致人类和动物广泛感染。在这种寄生虫的生命周期中会产生两种主要的无性形态：快速分裂的速殖子和分裂较慢、形成包囊的缓殖子。为了进一步研究这两种形态之间的差异，我们从两个无性阶段生成了大量表达序列标签（EST）。此前，我们从速殖子中获得了约7400个EST的数据（J. Ajioka等人，《基因组研究》8：18 - 28，1998年）。在此，我们报告对从感染小鼠囊肿中纯化的缓殖子的约2500个EST分析的结果。我们还报告了对体外诱导从速殖子分化为缓殖子的寄生虫的760个EST分析的结果。缓殖子和速殖子数据集的比较揭示了许多以前未表征的序列簇，这些序列簇在很大程度上或完全特定于一个或另一个发育阶段。这一类包括一种缓殖子特异性形式的烯醇化酶。结合先前鉴定的缓殖子特异性形式的乳酸脱氢酶，这一发现表明在该阶段糖酵解途径下游通量存在显著差异。因此，该数据集的生成提供了对寄生虫包囊形式下代谢和生长的宝贵见解，并代表了用于进一步研究弓形虫发育的大量信息。
