Calcofluor disrupts the midgut defense system in insects

The insect midgut is generally lined with a unique protective chitin/protein structure, the peritrophic membrane (PM). We demonstrated that in Trichoplusia ni larvae, the majority of PM proteins were assembled with chitin as a consequence of their chitin binding properties. These proteins could be dissociated from the PM in vitro by Calcofluor, a well-known chemical with chitin binding properties. The chitin binding characteristics of FM proteins were confirmed by their high affinity binding in vitro to regenerated chitin. In vivo assays demonstrated that Calcofluor could inhibit PM formation in five lepidopteran insects tested. The inhibition of T. ni PM formation by Calcofluor, was accompanied by increased larval susceptibility to baculovirus infection. Continuous inhibition of PM formation by Calcofluor resulted in retarded larval development and mortality. The destructive effect of Calcofluor on PM formation was demonstrated to be transient and reversible depending on the presence of Calcofluor within the midgut. In addition, degradation of the insect intestinal mucin was observed concurrently with the inhibition of PM formation by Calcofluor. our studies revealed a potential novel approach to develop strategies for insect control by utilizing chitin binding molecules to specifically target PM formation in a broad range of insect pest species. (C) 2000 Elsevier Science Ltd. All rights reserved.

昆虫中肠通常衬有一层独特的几丁质/蛋白质保护结构，即围食膜（PM）。我们证明在粉纹夜蛾幼虫中，由于其几丁质结合特性，大多数围食膜蛋白质与几丁质结合在一起。这些蛋白质在体外可被钙荧光素（一种具有几丁质结合特性的知名化学物质）从围食膜上解离下来。围食膜蛋白质的几丁质结合特性通过它们在体外与再生几丁质的高亲和力结合得到了证实。体内实验表明，钙荧光素可抑制所测试的五种鳞翅目昆虫的围食膜形成。钙荧光素对粉纹夜蛾围食膜形成的抑制伴随着幼虫对杆状病毒感染敏感性的增加。钙荧光素对围食膜形成的持续抑制导致幼虫发育迟缓并死亡。钙荧光素对围食膜形成的破坏作用被证明是暂时的且可逆的，这取决于中肠内钙荧光素的存在情况。此外，在钙荧光素抑制围食膜形成的同时，观察到昆虫肠道粘蛋白的降解。我们的研究揭示了一种潜在的新方法，即通过利用几丁质结合分子特异性地针对多种害虫物种的围食膜形成来制定昆虫防治策略。（C）2000爱思唯尔科学有限公司。保留所有权利。