Ribeiro José M C, Genta Fernando A, Sorgine Marcos H F, Logullo Raquel, Mesquita Rafael D, Paiva-Silva Gabriela O, Majerowicz David, Medeiros Marcelo, Koerich Leonardo, Terra Walter R, Ferreira Clélia, Pimentel André C, Bisch Paulo M, Leite Daniel C, Diniz Michelle M P, da S G V Junior João Lídio, Da Silva Manuela L, Araujo Ricardo N, Gandara Ana Caroline P, Brosson Sébastien, Salmon Didier, Bousbata Sabrina, González-Caballero Natalia, Silber Ariel Mariano, Alves-Bezerra Michele, Gondim Katia C, Silva-Neto Mário Alberto C, Atella Georgia C, Araujo Helena, Dias Felipe A, Polycarpo Carla, Vionette-Amaral Raquel J, Fampa Patrícia, Melo Ana Claudia A, Tanaka Aparecida S, Balczun Carsten, Oliveira José Henrique M, Gonçalves Renata L S, Lazoski Cristiano, Rivera-Pomar Rolando, Diambra Luis, Schaub Günter A, Garcia Elói S, Azambuja Patrícia, Braz Glória R C, Oliveira Pedro L
Section of Vector Biology, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America.
Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil ; Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil.
PLoS Negl Trop Dis. 2014 Jan 9;8(1):e2594. doi: 10.1371/journal.pntd.0002594. eCollection 2014.
The bloodsucking hemipteran Rhodnius prolixus is a vector of Chagas' disease, which affects 7-8 million people today in Latin America. In contrast to other hematophagous insects, the triatomine gut is compartmentalized into three segments that perform different functions during blood digestion. Here we report analysis of transcriptomes for each of the segments using pyrosequencing technology. Comparison of transcript frequency in digestive libraries with a whole-body library was used to evaluate expression levels. All classes of digestive enzymes were highly expressed, with a predominance of cysteine and aspartic proteinases, the latter showing a significant expansion through gene duplication. Although no protein digestion is known to occur in the anterior midgut (AM), protease transcripts were found, suggesting secretion as pro-enzymes, being possibly activated in the posterior midgut (PM). As expected, genes related to cytoskeleton, protein synthesis apparatus, protein traffic, and secretion were abundantly transcribed. Despite the absence of a chitinous peritrophic membrane in hemipterans - which have instead a lipidic perimicrovillar membrane lining over midgut epithelia - several gut-specific peritrophin transcripts were found, suggesting that these proteins perform functions other than being a structural component of the peritrophic membrane. Among immunity-related transcripts, while lysozymes and lectins were the most highly expressed, several genes belonging to the Toll pathway - found at low levels in the gut of most insects - were identified, contrasting with a low abundance of transcripts from IMD and STAT pathways. Analysis of transcripts related to lipid metabolism indicates that lipids play multiple roles, being a major energy source, a substrate for perimicrovillar membrane formation, and a source for hydrocarbons possibly to produce the wax layer of the hindgut. Transcripts related to amino acid metabolism showed an unanticipated priority for degradation of tyrosine, phenylalanine, and tryptophan. Analysis of transcripts related to signaling pathways suggested a role for MAP kinases, GTPases, and LKBP1/AMP kinases related to control of cell shape and polarity, possibly in connection with regulation of cell survival, response of pathogens and nutrients. Together, our findings present a new view of the triatomine digestive apparatus and will help us understand trypanosome interaction and allow insights into hemipteran metabolic adaptations to a blood-based diet.
吸血半翅目昆虫罗得西亚锥蝽是恰加斯病的传播媒介，目前拉丁美洲有700万至800万人受该病影响。与其他吸血昆虫不同，锥蝽的肠道分为三个部分，在血液消化过程中发挥不同功能。在此，我们报告了使用焦磷酸测序技术对每个部分的转录组进行的分析。通过将消化文库中的转录频率与全身文库进行比较来评估表达水平。所有类型的消化酶均高度表达，其中半胱氨酸蛋白酶和天冬氨酸蛋白酶占主导，后者通过基因复制显著扩增。尽管已知在前肠中段（AM）不发生蛋白质消化，但仍发现了蛋白酶转录本，这表明其以前酶形式分泌，可能在后肠中段（PM）被激活。正如预期的那样，与细胞骨架、蛋白质合成装置、蛋白质运输和分泌相关的基因大量转录。尽管半翅目昆虫没有几丁质围食膜——取而代之的是中肠上皮细胞上覆盖的脂质微绒毛膜——但仍发现了几种肠道特异性围食蛋白转录本，这表明这些蛋白质除了作为围食膜的结构成分外还发挥其他功能。在与免疫相关的转录本中，虽然溶菌酶和凝集素表达最高，但还鉴定出了几个属于Toll途径的基因——在大多数昆虫的肠道中含量较低——这与IMD和STAT途径的转录本丰度较低形成对比。对与脂质代谢相关的转录本的分析表明，脂质发挥多种作用，是主要能量来源、微绒毛膜形成的底物以及可能用于产生后肠蜡层的碳氢化合物来源。与氨基酸代谢相关的转录本显示，酪氨酸、苯丙氨酸和色氨酸的降解具有意外的优先性。对与信号通路相关的转录本的分析表明，丝裂原活化蛋白激酶、GTP酶和LKBP1/AMP激酶在控制细胞形状和极性方面发挥作用，可能与细胞存活调节、病原体反应和营养物质有关。总之，我们的研究结果为锥蝽的消化器官提供了新的视角，将有助于我们理解锥虫的相互作用，并深入了解半翅目昆虫对以血液为基础的饮食的代谢适应性。
