Department of Veterinary Medicine, Rongchang Campus, Southwest University, Chongqing 402460, PR China.
Exp Parasitol. 2011 Oct;129(2):120-6. doi: 10.1016/j.exppara.2011.07.005. Epub 2011 Jul 13.
Toxocara canis is a widespread intestinal nematode parasite of dogs, which can also cause disease in humans. We employed an expressed sequence tag (EST) strategy in order to study gene-expression including development, digestion and reproduction of T. canis. ESTs provided a rapid way to identify genes, particularly in organisms for which we have very little molecular information. In this study, a cDNA library was constructed from a female adult of T. canis and 215 high-quality ESTs from 5'-ends of the cDNA clones representing 79 unigenes were obtained. The titer of the primary cDNA library was 1.83×10(6)pfu/mL with a recombination rate of 99.33%. Most of the sequences ranged from 300 to 900bp with an average length of 656bp. Cluster analysis of these ESTs allowed identification of 79 unique sequences containing 28 contigs and 51 singletons. BLASTX searches revealed that 18 unigenes (22.78% of the total) or 70 ESTs (32.56% of the total) were novel genes that had no significant matches to any protein sequences in the public databases. The rest of the 61 unigenes (77.22% of the total) or 145 ESTs (67.44% of the total) were closely matched to the known genes or sequences deposited in the public databases. These genes were classified into seven groups based on their known or putative biological functions. We also confirmed the gene expression patterns of several immune-related genes using RT-PCR examination. This work will provide a valuable resource for the further investigations in the stage-, sex- and tissue-specific gene transcription or expression.
犬弓首蛔虫是一种广泛存在的犬肠道寄生线虫，也可引起人类疾病。我们采用表达序列标签（EST）策略来研究犬弓首蛔虫的发育、消化和繁殖等基因表达。EST 为鉴定基因提供了一种快速的方法，特别是对于我们分子信息很少的生物体。在这项研究中，我们构建了一个雌性犬弓首蛔虫成虫 cDNA 文库，并获得了代表 79 个单基因的 5' - cDNA 克隆的 215 个高质量 EST，这些 EST 代表了 79 个未拼接的基因。初级 cDNA 文库的滴度为 1.83×10(6)pfu/mL，重组率为 99.33%。大多数序列长度在 300-900bp 之间，平均长度为 656bp。对这些 EST 的聚类分析确定了 79 个独特序列，其中包含 28 个重叠群和 51 个单序列。BLASTX 搜索显示，18 个单基因（占总数的 22.78%）或 70 个 EST（占总数的 32.56%）是没有与公共数据库中任何蛋白质序列有显著匹配的新基因。其余 61 个单基因（占总数的 77.22%）或 145 个 EST（占总数的 67.44%）与已知基因或已在公共数据库中保存的序列密切匹配。根据其已知或推测的生物学功能，这些基因被分为七个组。我们还通过 RT-PCR 检查证实了几种免疫相关基因的表达模式。这项工作将为进一步研究阶段、性别和组织特异性基因转录或表达提供有价值的资源。
