Expressed Sequence Tags from the Ciliate Protozoan Parasite Ichthyophthirius Multifiliis

Researchers sequenced 10,368 expressed sequence tags (EST) clones using a normalized cDNA library made from pooled samples of the trophont, tomont, and theront life-cycle stages, and generated 9,769 sequences (94.2% success rate). Post-sequencing processing led to 8,432 high quality sequences. Clustering analysis of these ESTs allowed identification of 4,706 unique sequences containing 976 contigs and 3,730 singletons.
The ciliate protozoan Ichthyophthirius multifiliis (Ich) is an important parasite of freshwater fish that causes 'white spot disease' leading to significant losses. A genomic resource for large-scale studies of this parasite has been lacking. To study gene expression involved in Ich pathogenesis and virulence, our goal was to generate ESTs for the development of a powerful microarray platform for the analysis of global gene expression in this species. Here, we initiated a project to sequence and analyze over 10,000 ESTs.

研究人员以涵盖多子小瓜虫（Ichthyophthirius multifiliis, Ich）滋养体、包囊体与幼虫体三个生活周期阶段的混合样本构建的标准化cDNA文库（normalized cDNA library）为材料，对10368个表达序列标签（expressed sequence tags, EST）克隆进行测序，最终获得9769条序列，测序成功率达94.2%。测序后经质控处理，共得到8432条高质量序列。对上述EST开展聚类分析后，鉴定出4706条唯一序列，其中包含976个重叠群（contig）与3730个单拷贝序列（singleton）。
纤毛门原生动物多子小瓜虫（Ichthyophthirius multifiliis, 简称Ich）是淡水鱼类的重要致病性寄生虫，其引发的“白点病”会造成水产养殖的显著经济损失。此前该研究领域一直缺乏可供该寄生虫开展大规模研究的基因组学资源。为探究参与多子小瓜虫致病机制与毒力过程的基因表达模式，本研究旨在通过构建EST文库开发高效的基因芯片平台，以实现该物种全基因组范围的基因表达分析。为此我们启动了一项针对万余条EST的测序与分析项目。