Insect Immunity Against Parasitoids

9504796黑腹果蝇拟议计划的整体目标是透过研究果蝇对布氏细小蜂寄生虫的细胞毒性反应，加深对昆虫免疫系统的认识。当被感染时，免疫反应性昆虫通常会在异物周围形成深色的黑色素胶囊，但几乎对专门针对和摧毁被包裹的寄生虫的细胞毒分子一无所知。果蝇Leptopilina模型为系统分析昆虫免疫中涉及的细胞和生化过程提供了一个很好的遗传系统。Nappi博士将使用基因上定义明确的黑腹果蝇菌株，监测寄生虫诱导的潜在细胞毒性物质的产生，如黑色素前体(例如，苯二酮、半喹酮)和活性氧物种(例如，超氧阴离子、羟基自由基和过氧化氢)。对细胞毒性分子的鉴定和对它们产生机制的了解将对回答一些关于昆虫免疫识别的基本问题非常有用。寄生虫诱导的黑色素前体和抗氧化酶的变化将在已知的抗性和敏感宿主菌株中以及在抗氧化剂缺乏的菌株中进行监测，方法是使用带有电化学检测的高压液相色谱、UV/Vis光谱和荧光检测。这种研究细胞毒性分子形成的综合方法有望为某些自由基和黑色素的活性前体在昆虫免疫中的重要性提供有趣的见解。***

9504796 Nappi The overall objective of the proposed project is to gain a better understanding of the insect immune system by studying the cytotoxic responses made by the fruit fly Drosophila melanogaster against the parasitoid Leptopilina boulardi. When infected, immune reactive insects typically form darkly colored, melanotic capsules around the foreign objects, but virtually nothing is known of the cytotoxic molecules that specifically target and destroy encapsulated parasites. The Drosophila Leptopilina model provides an excellent genetic system for the systematic analysis of the cellular and biochemical processes involved in insect immunity. Using genetically well-defined strains of D. melanogaster, Dr. Nappi will monitor the parasite-induced generation of such potentially cytotoxic substances as melanin precursors (e.g., quinones, semiquinones), and reactive oxygen species (e.g., superoxide anion, hydroxyl radical and hydrogen peroxide). The identification of cytotoxic molecules and knowledge of the mechanisms by which they are produced will be extremely useful in answering some of the fundamental questions concerning immune recognition in insects. Parasite-induced changes in melanin precursors and antioxidant enzymes will be monitored in known resistant and susceptible host strains, and in antioxidant deficient strains, by using high pressure liquid chromatography with electrochemical detection, UV/vis spectroscopy, and fluorometric detection. Such a comprehensive approach for investigation the formation of cytotoxic molecules promises to provide interesting insights into the importance of certain free radicals and reactive precursors of melanin in insect immunity. ***