Stanley-Samuelson D W, Jensen E, Nickerson K W, Tiebel K, Ogg C L, Howard R W
Department of Entomology, University of Nebraska, Lincoln 68583-0816.
Proc Natl Acad Sci U S A. 1991 Feb 1;88(3):1064-8. doi: 10.1073/pnas.88.3.1064.
Inhibition of eicosanoid formation in larvae of the tobacco hornworm Manduca sexta, using specific inhibitors of phospholipase A2, cyclooxygenase, and lipoxygenase, severely weakened the ability of larvae to clear the bacterium Serratia marscescens from their hemolymph. The reduced capability to remove bacteria is associated with increased mortality due to these bacteria. There is a dose-dependent relationship between the phospholipase A2 inhibitor dexamethasone and both the reduced bacterial clearance and increased larval mortality. The dexamethasone effects on larval survival were reversed by treatment with arachidonic acid. Maleic acid, a nonspecific antioxidant, did not interfere with the insects' ability to remove bacterial cells from hemolymph. The larvae were shown to contain all of the C20 polyunsaturated fatty acids necessary for eicosanoid biosynthesis and to be capable of converting radioactive arachidonic acid into several primary prostaglandins. These results strongly suggest that eicosanoids mediate transduction of bacterial infection signals into the complex of cellular and humoral responses that comprise invertebrate immunity.
使用磷脂酶A2、环氧化酶和脂氧合酶的特异性抑制剂抑制烟草天蛾幼虫中类花生酸的形成，严重削弱了幼虫从血淋巴中清除粘质沙雷氏菌的能力。清除细菌能力的降低与这些细菌导致的死亡率增加有关。磷脂酶A2抑制剂地塞米松与细菌清除率降低和幼虫死亡率增加之间存在剂量依赖关系。用花生四烯酸处理可逆转地塞米松对幼虫存活的影响。马来酸，一种非特异性抗氧化剂，不会干扰昆虫从血淋巴中清除细菌细胞的能力。研究表明，幼虫含有类花生酸生物合成所需的所有C20多不饱和脂肪酸，并且能够将放射性花生四烯酸转化为几种主要的前列腺素。这些结果有力地表明，类花生酸介导细菌感染信号转导为构成无脊椎动物免疫的细胞和体液反应复合体。
