Henriques Bianca Santos, Gomes Bruno, Oliveira Pedro Lagerblad, Garcia Elói de Souza, Azambuja Patrícia, Genta Fernando Ariel
Laboratory of Insect Physiology and Biochemistry, Oswaldo Cruz Institute - Oswaldo Cruz Foundation (IOC-FIOCRUZ), Rio de Janeiro, Brazil.
National Institute of Science and Technology for Molecular Entomology (INCT-EM), Cidade Universitária, Rio de Janeiro, Brazil.
Front Physiol. 2021 Jan 13;11:509310. doi: 10.3389/fphys.2020.509310. eCollection 2020.
is one important vector for the parasite in Latin America, where Chagas disease is a significant health issue. Although is a model for investigations of vector-parasite interaction and transmission, not much has been done recently to further comprehend its protein digestion. In this work, gut proteolysis was characterized using new fluorogenic substrates, including optimum pH, inhibition profiles, and tissue and temporal expression patterns. Each protease possessed a particular tissue prevalence and activity cycle after feeding. Cathepsin L had a higher activity in the posterior midgut lumen, being characterized by a plateau of high activities during several days in the intermediate phase of digestion. Cathepsin D showed high activity levels in the tissue homogenates and in the luminal content of the posterior midgut, with a single peak 5 days after blood feeding. Aminopeptidases are highly associated with the midgut wall, where the highest activity is located. Assays with proteinaceous substrates as casein, hemoglobin, and serum albumin revealed different activity profiles, with some evidence of biphasic temporal proteolytic patterns. Cathepsin D genes are preferentially expressed in the anterior midgut, while cathepsin L genes are mainly located in the posterior portion of the midgut, with specific sets of genes being differently expressed in the initial, intermediate, or late phases of blood digestion. Significance Statement This is the first description in a non-dipteran hematophagous species of a sequential protease secretion system based on midgut cathepsins instead of the most common insect digestive serine proteases (trypsins and chymotrypsins). The midgut of (Hemiptera) shows a different temporal expression of proteases in the initial, intermediate, and late stages of blood digestion. In this respect, a different timing in protease secretion may be an example of adaptative convergence in blood-sucking vectors from different orders. Expanding the knowledge about gut physiology in triatomine vectors may contribute to the development of new control strategies, aiming the blocking of parasite transmission.
在拉丁美洲，锥蝽是该寄生虫的一种重要传播媒介，恰加斯病在当地是一个严重的健康问题。尽管锥蝽是研究媒介与寄生虫相互作用及传播的模型，但最近在进一步了解其蛋白质消化方面进展甚微。在这项研究中，利用新型荧光底物对肠道蛋白水解进行了表征，包括最适pH值、抑制谱以及组织和时间表达模式。每种蛋白酶在进食后都有特定的组织分布和活性周期。组织蛋白酶L在后肠中段管腔中活性较高，其特征是在消化中期的几天内活性保持在较高水平。组织蛋白酶D在组织匀浆和后肠管腔内容物中显示出高活性水平，在吸血后5天出现单峰。氨肽酶与中肠壁高度相关，中肠壁处活性最高。用酪蛋白、血红蛋白和血清白蛋白等蛋白质底物进行的测定显示出不同的活性谱，有一些证据表明存在双相时间蛋白水解模式。组织蛋白酶D基因在前肠中段优先表达，而组织蛋白酶L基因主要位于中肠后部，在血液消化的初始、中期或后期，特定的基因集表达不同。重要性声明这是首次在非双翅目吸血物种中描述基于中肠组织蛋白酶而非最常见的昆虫消化丝氨酸蛋白酶（胰蛋白酶和胰凝乳蛋白酶）的顺序蛋白酶分泌系统。锥蝽（半翅目）的中肠在血液消化的初始、中期和后期显示出不同的蛋白酶时间表达。在这方面，蛋白酶分泌的不同时间可能是不同目吸血媒介适应性趋同的一个例子。扩展对锥蝽媒介肠道生理学的认识可能有助于开发旨在阻断寄生虫传播的新控制策略。
