Cytopathological Effects of Bacillus sphaericus Cry48Aa/Cry49Aa Toxin on Binary Toxin-Susceptible and -Resistant Culex quinquefasciatus Larvae
Cytopathological Effects of Bacillus sphaericus Cry48Aa/Cry49Aa Toxin on Binary Toxin-Susceptible and -Resistant Culex quinquefasciatus Larvae
复制标题
DOI：
10.1128/aem.00811-09
复制
发表时间：
2009-07-15
影响因子：
4.4
通讯作者：
Neves Lobo Silva-Filha, Maria Helena
中科院分区：
文献类型：
--
作者：
de Melo, Janaina Viana;Jones, Gareth Wyn;Neves Lobo Silva-Filha, Maria Helena
Cry48Aa/Cry49Aa双组分杀蚊毒素是最近从球形芽孢杆菌菌株IAB59中鉴定出来的，它是由一个三结构域Cry蛋白毒素（Cry48Aa）和一个二元（Bin）毒素样蛋白（Cry49Aa）独特组成的。它的作用方式尚未阐明，但该蛋白的一个显著特征是对库蚊复合体的物种具有高毒性，除了能够克服库蚊对Bin毒素的抗性外，Bin毒素是以球蚧为基础的杀幼虫剂的主要杀虫因子。本研究旨在探讨Cry48Aa/Cry49Aa对宾毒素敏感和抗性致倦库蚊幼虫中肠细胞超微结构的影响。Cry48Aa/Cry49Aa处理后观察到的主要细胞病理学影响是线粒体空泡化、内质网破裂、细胞质空泡产生和微绒毛破坏。这些作用在Bin毒素敏感和抗性的幼虫中相似，表明Cry48Aa/Cry49Aa毒素与缺乏Bin毒素受体的细胞相互作用并表现出毒性作用，而球芽孢杆菌iab59抗性幼虫在Cry48Aa/Cry49Aa毒素处理后未表现出死亡。Cry48Aa/Cry49Aa处理对Bin毒素抗性幼虫的细胞病理学改变与Bin/Cry11Aa毒素协同混合处理的结果相似。这种效果似乎是由类哭毒素和类宾毒素共同作用的结果。Cry48Aa/Cry49Aa引起的复杂效应为这些毒素作为新一代杀虫剂的活性成分的潜力提供了证据，这些杀虫剂结合具有不同作用位点的杀虫因子，以控制蚊子的抗性。
The Cry48Aa/Cry49Aa mosquitocidal two-component toxin was recently characterized from Bacillus sphaericus strain IAB59 and is uniquely composed of a three-domain Cry protein toxin (Cry48Aa) and a binary (Bin) toxin-like protein (Cry49Aa). Its mode of action has not been elucidated, but a remarkable feature of this protein is the high toxicity against species from the Culex complex, besides its capacity to overcome Culex resistance to the Bin toxin, the major insecticidal factor in B. sphaericus-based larvicides. The goal of this work was to investigate the ultrastructural effects of Cry48Aa/Cry49Aa on midgut cells of Bin-toxin-susceptible and -resistant Culex quinquefasciatus larvae. The major cytopathological effects observed after Cry48Aa/Cry49Aa treatment were intense mitochondrial vacuolation, breakdown of endoplasmic reticulum, production of cytoplasmic vacuoles, and microvillus disruption. These effects were similar in Bin-toxin-susceptible and - resistant larvae and demonstrated that Cry48Aa/Cry49Aa toxin interacts with and displays toxic effects on cells lacking receptors for the Bin toxin, while B. sphaericus IAB59-resistant larvae did not show mortality after treatment with Cry48Aa/Cry49Aa toxin. The cytopathological alterations in Bin-toxin-resistant larvae provoked by Cry48Aa/Cry49Aa treatment were similar to those observed when larvae were exposed to a synergistic mixture of Bin/Cry11Aa toxins. Such effects seemed to result from a combined action of Cry-like and Bin-like toxins. The complex effects caused by Cry48Aa/Cry49Aa provide evidence for the potential of these toxins as active ingredients of a new generation of biolarvicides that conjugate insecticidal factors with distinct sites of action, in order to manage mosquito resistance.