Eliáš Sara, Hurychová Jana, Toubarro Duarte, Frias Jorge, Kunc Martin, Dobeš Pavel, Simões Nelson, Hyršl Pavel
Department of Experimental Biology, Faculty of Science, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic.
CBA and Faculty of Sciences and Technology, University of Azores, Rua Mãe de Deus n° 13, 9500-321 Ponta Delgada, Portugal.
Insects. 2020 Jun 5;11(6):353. doi: 10.3390/insects11060353.
Entomopathogenic nematodes (EPNs) are efficient insect parasites, that are known for their mutualistic relationship with entomopathogenic bacteria and their use in biocontrol. EPNs produce bioactive molecules referred to as excreted/secreted products (ESPs), which have come to the forefront in recent years because of their role in the process of host invasion and the modulation of its immune response. In the present study, we confirmed the production of ESPs in the EPN , and investigated their role in the modulation of the phenoloxidase cascade, one of the key components of the insect immune system. ESPs were isolated from 14- and 21-day-old infective juveniles of , which were found to be more virulent than newly emerged nematodes, as was confirmed by mortality assays using larvae. The isolated ESPs were further purified and screened for the phenoloxidase-inhibiting activity. In these products, a 38 kDa fraction of peptides was identified as the main candidate source of phenoloxidase-inhibiting compounds. This fraction was further analyzed by mass spectrometry and the de novo sequencing approach. Six peptide sequences were identified in this active ESP fraction, including proteins involved in ubiquitination and the regulation of a Toll pathway, for which a role in the regulation of insect immune response has been proposed in previous studies.
昆虫病原线虫（EPNs）是高效的昆虫寄生虫，以其与昆虫病原细菌的共生关系及其在生物防治中的应用而闻名。EPNs产生被称为排泄/分泌产物（ESPs）的生物活性分子，近年来，由于它们在宿主入侵过程及其免疫反应调节中的作用，这些分子已成为研究的前沿热点。在本研究中，我们证实了EPNs中ESPs的产生，并研究了它们在调节酚氧化酶级联反应中的作用，酚氧化酶级联反应是昆虫免疫系统的关键组成部分之一。从14日龄和21日龄的感染性幼虫中分离出ESPs，通过使用幼虫进行的死亡率测定证实，这些幼虫比新出现的线虫更具毒性。对分离出的ESPs进一步纯化，并筛选其酚氧化酶抑制活性。在这些产物中，一个38 kDa的肽段被确定为酚氧化酶抑制化合物的主要候选来源。通过质谱和从头测序方法对该肽段进行了进一步分析。在这个活性ESPs组分中鉴定出六个肽序列，包括参与泛素化和Toll途径调节蛋白，先前的研究已提出这些蛋白在昆虫免疫反应调节中发挥作用。
