Bouzid Wafa, Verdenaud Marion, Klopp Christophe, Ducancel Frédéric, Noirot Céline, Vétillard Angélique
Venoms and Biological Activities Laboratory, EA 4357, PRES-University of Toulouse, Jean-François Champollion University Center, Albi, France.
BMC Genomics. 2014 Nov 18;15(1):987. doi: 10.1186/1471-2164-15-987.
Arthropod venoms are invaluable sources of bioactive substances with biotechnological application. The limited availability of some venoms, such as those from ants, has restricted the knowledge about the composition and the potential that these biomolecules could represent. In order to provide a global insight on the transcripts expressed in the venom gland of the Brazilian ant species Tetramorium bicarinatum and to unveil the potential of its products, high-throughput approach using Illumina technology has been applied to analyze the genes expressed in active venom glands of this ant species.
A total of 212,371,758 pairs of quality-filtered, 100-base-pair Illumina reads were obtained. The de novo assemblies yielded 36,042 contigs for which 27,873 have at least one predicted ORF among which 59.77% produce significant hits in the available databases. The investigation of the reads mapping toxin class revealed a high diversification with the major part consistent with the classical hymenopteran venom protein signature represented by venom allergen (33.3%), followed by a diverse toxin-expression profile including several distinct isoforms of phospholipase A1 and A2, venom serine protease, hyaluronidase, protease inhibitor and secapin. Moreover, our results revealed for the first time the presence of toxin-like peptides that have been previously identified from unrelated venomous animals such as waprin-like (snakes) and agatoxins (spiders and conus).The non-toxin transcripts were mainly represented by contigs involved in protein folding and translation, consistent with the protein-secretory function of the venom gland tissue. Finally, about 40% of the generated contigs have no hits in the databases with 25% of the predicted peptides bearing signal peptide emphasizing the potential of the investigation of these sequences as source of new molecules. Among these contigs, six putative novel peptides that show homologies with previously identified antimicrobial peptides were identified.
To the best of our knowledge, this work reports the first large-scale analysis of genes transcribed by the venomous gland of the ant species T. bicarinatum and helps with the identification of Hymenoptera toxin arsenal. In addition, results from this study demonstrate that de novo transcriptome assembly allows useful venom gene expression analysis in a species lacking a genome sequence database.
节肢动物毒液是具有生物技术应用价值的生物活性物质的宝贵来源。某些毒液（如蚂蚁毒液）的有限可得性限制了我们对其组成以及这些生物分子潜在价值的了解。为了全面了解巴西蚂蚁物种双隆骨铺道蚁（Tetramorium bicarinatum）毒腺中表达的转录本，并揭示其产物的潜力，已采用基于Illumina技术的高通量方法来分析该蚂蚁物种活性毒腺中表达的基因。
共获得212,371,758对经过质量过滤的100碱基对Illumina读数。从头组装产生了36,042个重叠群，其中27,873个至少有一个预测的开放阅读框，其中59.77%在现有数据库中产生了显著匹配。对映射到毒素类别的读数进行的研究显示出高度的多样性，主要部分与由毒液变应原代表的经典膜翅目毒液蛋白特征一致（33.3%），其次是多样的毒素表达谱，包括磷脂酶A1和A2、毒液丝氨酸蛋白酶、透明质酸酶、蛋白酶抑制剂和secapin的几种不同同工型。此外，我们的结果首次揭示了以前在不相关的有毒动物（如类蛙皮素样蛋白（蛇）和蜘蛛毒素（蜘蛛和芋螺））中鉴定出的毒素样肽的存在。非毒素转录本主要由参与蛋白质折叠和翻译的重叠群代表，这与毒腺组织的蛋白质分泌功能一致。最后，约40%的生成重叠群在数据库中无匹配，25%的预测肽带有信号肽，这突出了将这些序列作为新分子来源进行研究的潜力。在这些重叠群中，鉴定出了六种与先前鉴定的抗菌肽具有同源性的假定新型肽。
据我们所知，这项工作首次报道了对双隆骨铺道蚁毒腺转录基因的大规模分析，并有助于鉴定膜翅目毒素库。此外，本研究结果表明，从头转录组组装可在缺乏基因组序列数据库的物种中进行有用的毒液基因表达分析。
