INSECTICIDAL TOXIN OF BACILLUS SPHAERICUS

球形芽孢杆菌是一种产芽孢细菌， 作为媒介蚊子的微生物控制剂的潜力。 这种微生物通过蛋白质毒素杀死宿主。 的 毒素对许多昆虫的幼虫和培养细胞有很强的杀虫作用， 对某些蚊子的毒性要小得多 埃及伊蚊等物种，对其他昆虫无毒 比蚊子和哺乳动物都多。 该提案描述了 试图检测这种毒素与 培养的蚊幼细胞，并探讨 在体外和体内的作用。 抗性蚊子物种将 与敏感物种进行比较，以确定减少的原因 灵敏度 标记的毒素将用于研究结合和 毒素的内化。 细胞膜的组成部分 负责敏感物种的结合将被检查， 分离，并将使用针对该受体产生的抗血清， 检测抗性物种的蛋白质。 单克隆抗体将 将被提升到毒素和受体，并将被用于 研究毒素的结合和作用方式。 可能 作用方式，包括膜孔的形成和变化 在cyclic-AMP中将被探索。 一项超微结构研究将寻求 培养的和幼虫中肠细胞的细胞膜变化 与B中毒有关。球形菌毒素和微量 金标记毒素在培养细胞和 幼虫

Bacillus sphaericus is a sporeforming bacterium with a high degree of potential as a microbial control agent for vector mosquitoes. This organism kills the host by means of a protein toxin. The toxin is highly insecticidal to larvae and cultured cells from many species of mosquitoes, but is much less toxic to certain mosquito species such as Aedes aegypti and is not toxic to insects other than mosquitoes nor to mammals. This proposal describes experiments that seek to examine the binding of this toxin to cultured and mosquito larval cells and to explore the mode of action both in vitro and in vivo. Resistant mosquito species will be compared to sensitive species, to determine the cause of reduced sensitivity. Labelled toxin will be used to study binding and internalization of the toxin. The component of the cell membrane responsible for binding in sensitive species will be examined, isolated, and antiserum raised to this receptor will be used to examine proteins of resistant species. Monoclonal antibodies will be raised to the toxin and the receptor, and will be used to investigate binding and mode of action of the toxin. Possible modes of action including development of membrane pores and changes in cyclic-AMP will be explored. An ultrastructural study will seek changes in the cell membrane of cultured and larval midgut cells associated with intoxication by the B. sphaericus toxin, and trace movement of gold-labelled toxin in cultured cells and in the larvae.