Transcriptome analysis of the spider Phonotimpus pennimani reveals novel toxin transcripts

Abstract Background: Phonotimpus pennimani (Araneae, Phrurolithidae) is a small-sized (3-5 mm) spider endemic to the Tacaná volcano in Chiapas, Mexico, where it is found in soil litter of cloud forests and coffee plantations. Its venom composition has so far not been investigated, partly because it is not a species of medical significance. However, it does have an important impact on the arthropod populations of its natural habitat. Methods: Specimens were collected in Southeastern Mexico (Chiapas) and identified taxonomically by morphological characteristics. A partial sequence from the mitochondrial gene coxI was amplified. Sequencing on the Illumina platform of a transcriptome library constructed from 12 adult specimens revealed 25 toxin or toxin-like genes. Transcripts were validated (RT-qPCR) by assessing the differential expression of the toxin-like PpenTox1 transcript and normalising with housekeeping genes. Results: Analysis of the coxI-gene revealed a similarity to other species of the family Phrurolithidae. Transcriptome analysis also revealed similarity with venom components of species from the families Ctenidae, Lycosidae, and Sicariidae. Expression of the toxin-like PpenTox1 gene was different for each developmental stage (juvenile or adult) and also for both sexes (female or male). Additionally, a partial sequence was obtained for the toxin-like PpenTox1 from DNA. Conclusion: Data from the amplification of the mitochondrial coxI gene confirmed that P. pennimani belongs to the family Phrurolithidae. New genes and transcripts coding for venom components were identified.

背景摘要：潘尼曼音突蛛（Phonotimpus pennimani）隶属于蜘蛛目（Araneae）、盾蛛科（Phrurolithidae），是一种体长3-5毫米的小型蜘蛛，仅分布于墨西哥恰帕斯州的塔卡纳火山，栖息于云雾林与咖啡种植园的地表枯落物中。迄今为止，其毒液组分尚未得到系统研究，部分原因在于该物种不具备医学重要性。然而，该物种对其原生栖息地的节肢动物种群具有显著的生态调控作用。
方法：研究样本采集于墨西哥东南部恰帕斯州，通过形态学特征完成分类鉴定。扩增了线粒体基因coxI的部分序列。以12只成年个体构建转录组文库，并在Illumina测序平台完成测序，共鉴定得到25个毒素或类毒素编码基因。通过实时荧光定量聚合酶链反应（RT-qPCR）对转录本进行验证：检测类毒素基因PpenTox1的差异表达水平，并以持家基因作为内参进行标准化校正。
结果：对coxI基因的序列分析显示，其与盾蛛科其他物种具有高度同源性。转录组分析还表明，该物种的毒液组分与栉蛛科（Ctenidae）、狼蛛科（Lycosidae）以及刺客蛛科（Sicariidae）物种的毒液组分存在相似性。类毒素基因PpenTox1的表达量在不同发育阶段（幼体与成体）以及不同性别（雌性与雄性）间均存在显著差异。此外，本研究还从基因组DNA中扩增得到类毒素基因PpenTox1的部分序列。
结论：线粒体coxI基因的扩增测序数据证实，潘尼曼音突蛛隶属于盾蛛科。本研究成功鉴定出一批全新的毒液编码基因及转录本。