Toxoplasma gondii asexual development:: Identification of developmentally regulated genes and distinct patterns of gene expression
Toxoplasma gondii asexual development:: Identification of developmentally regulated genes and distinct patterns of gene expression
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DOI：
10.1128/ec.1.3.329-340.2002
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发表时间：
2002-06-01
期刊：
影响因子：
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通讯作者：
Boothroyd, JC
中科院分区：
文献类型：
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作者：
Cleary, MD;Singh, U;Boothroyd, JC
弓形虫的无性发育是寄生虫生命周期的一个重要方面，可以传播和避免宿主的免疫反应。快速分裂的速殖子分化为缓慢生长的成囊缓殖子涉及生理和形态的显著变化。我们制作了4,400个弓形虫cDNA的微阵列，代表了至少600个基因的相似性（基于部分测序），并使用这些微阵列研究了速殖子向缓殖子分化过程中转录水平的变化。这种方法使我们能够（i）确定先前描述的发育调控基因的表达谱，（ii）鉴定新的发育调控基因，以及（iii）根据转录水平变化的时间和幅度鉴定不同类别的基因。而微阵列分析通常涉及在不同时间点的mRNA水平的比较，我们已经开发了一种方法来测量在给定的时间点基因之间的相对转录丰度。该方法用于确定分化前寄生虫的转录水平，并进一步对缓殖子虫诱导的基因进行分类，从而比标准表达谱更全面地了解基因表达的变化。新鉴定的发育调控基因包括推定的表面蛋白（SAG 1相关蛋白、SRS 9和含粘蛋白结构域的蛋白）、调控和代谢酶（甲硫氨酸氨基肽酶、寡肽酶、氨基转移酶和葡萄糖-6-磷酸脱氢酶同系物）以及编码分泌细胞器蛋白的基因子集（MIC 1、ROP 1、ROP 2、ROP 4、GRA 1、GRA 5和GRA 8）。这种分析允许第一次深入研究这种复杂的原生动物寄生虫发育过程中基因表达的变化。
Asexual development in Toxoplasma gondii is a vital aspect of the parasite's life cycle, allowing transmission and avoidance of the host immune response. Differentiation of rapidly dividing tachyzoites into slowly growing, encysted bradyzoites involves significant changes in both physiology and morphology. We generated microarrays of similar to4,400 Toxoplasma cDNAs, representing a minimum of similar to600 genes (based on partial sequencing), and used these microarrays to study changes in transcript levels during tachyzoite-to-bradyzoite differentiation. This approach has allowed us to (i) determine expression profiles of previously described developmentally regulated genes, (ii) identify novel developmentally regulated genes, and (iii) identify distinct classes of genes based on the timing and magnitude of changes in transcript levels. Whereas microarray analysis typically involves comparisons of mRNA levels at different time points, we have developed a method to measure relative transcript abundance between genes at a given time point. This method was used to determine transcript levels in parasites prior to differentiation and to further classify bradyzoite-induced genes, thus allowing a more comprehensive view of changes in gene expression than is provided by standard expression profiles. Newly identified developmentally regulated genes include putative surface proteins (a SAG1-related protein, SRS9, and a mucin-domain containing protein), regulatory and metabolic enzymes (methionine aminopeptidase, oligopeptidase, aminotransferase, and glucose-6-phosphate dehydrogenase homologues), and a subset of genes encoding secretory organelle proteins (MIC1, ROP1, ROP2, ROP4, GRA1, GRA5, and GRA8). This analysis permits the first in-depth look at changes in gene expression during development of this complex protozoan parasite.