Department of Entomology, The Ohio State University, Ohio Agricultural and Research Development Center, Wooster, OH 44691, USA.
BMC Genomics. 2012 Jan 6;13:6. doi: 10.1186/1471-2164-13-6.
Bed bugs (Cimex lectularius) are hematophagous nocturnal parasites of humans that have attained high impact status due to their worldwide resurgence. The sudden and rampant resurgence of C. lectularius has been attributed to numerous factors including frequent international travel, narrower pest management practices, and insecticide resistance.
We performed a next-generation RNA sequencing (RNA-Seq) experiment to find differentially expressed genes between pesticide-resistant (PR) and pesticide-susceptible (PS) strains of C. lectularius. A reference transcriptome database of 51,492 expressed sequence tags (ESTs) was created by combining the databases derived from de novo assembled mRNA-Seq tags (30,404 ESTs) and our previous 454 pyrosequenced database (21,088 ESTs). The two-way GLMseq analysis revealed ~15,000 highly significant differentially expressed ESTs between the PR and PS strains. Among the top 5,000 differentially expressed ESTs, 109 putative defense genes (cuticular proteins, cytochrome P450s, antioxidant genes, ABC transporters, glutathione S-transferases, carboxylesterases and acetyl cholinesterase) involved in penetration resistance and metabolic resistance were identified. Tissue and development-specific expression of P450 CYP3 clan members showed high mRNA levels in the cuticle, Malpighian tubules, and midgut; and in early instar nymphs, respectively. Lastly, molecular modeling and docking of a candidate cytochrome P450 (CYP397A1V2) revealed the flexibility of the deduced protein to metabolize a broad range of insecticide substrates including DDT, deltamethrin, permethrin, and imidacloprid.
We developed significant molecular resources for C. lectularius putatively involved in metabolic resistance as well as those participating in other modes of insecticide resistance. RNA-Seq profiles of PR strains combined with tissue-specific profiles and molecular docking revealed multi-level insecticide resistance in C. lectularius. Future research that is targeted towards RNA interference (RNAi) on the identified metabolic targets such as cytochrome P450s and cuticular proteins could lay the foundation for a better understanding of the genetic basis of insecticide resistance in C. lectularius.
臭虫（Cimex lectularius）是一种嗜血性的夜间寄生虫，对人类有很高的影响，由于它们在全球范围内的复苏，臭虫已经成为了一种高影响力的寄生虫。臭虫的突然和猖獗的复苏归因于许多因素，包括频繁的国际旅行、更严格的害虫管理实践和杀虫剂抗性。
我们进行了下一代 RNA 测序（RNA-Seq）实验，以发现抗药性（PR）和敏感性（PS）品系之间的差异表达基因。通过将从头组装的 mRNA-Seq 标签（30,404 ESTs）和我们之前的 454 焦磷酸测序数据库（21,088 ESTs）的数据库结合起来，创建了一个 51,492 个表达序列标签（ESTs）的参考转录组数据库。双向 GLMseq 分析显示，PR 和 PS 品系之间有~15,000 个高度显著差异表达的 ESTs。在 top 5,000 个差异表达的 ESTs 中，鉴定出 109 个可能与穿透抗性和代谢抗性有关的防御基因（角质蛋白、细胞色素 P450s、抗氧化基因、ABC 转运蛋白、谷胱甘肽 S-转移酶、羧酸酯酶和乙酰胆碱酯酶）。细胞色素 P450 CYP3 家族成员的组织和发育特异性表达显示，mRNA 水平在角质层、马氏管和中肠中较高；在早期若虫中分别较高。最后，候选细胞色素 P450（CYP397A1V2）的分子建模和对接表明，推导蛋白具有代谢广泛杀虫剂底物的灵活性，包括滴滴涕、溴氰菊酯、氯菊酯和吡虫啉。
我们为 C. lectularius 开发了重要的分子资源，这些资源可能与代谢抗性以及其他形式的杀虫剂抗性有关。PR 品系的 RNA-Seq 图谱与组织特异性图谱和分子对接相结合，揭示了 C. lectularius 中的多层次杀虫剂抗性。针对细胞色素 P450 和角质蛋白等已识别代谢靶标的 RNA 干扰（RNAi）的未来研究，可能为更好地了解 C. lectularius 中杀虫剂抗性的遗传基础奠定基础。
