EICOSANOIDS MEDIATE INSECT NODULATION RESPONSES TO BACTERIAL-INFECTIONS
EICOSANOIDS MEDIATE INSECT NODULATION RESPONSES TO BACTERIAL-INFECTIONS
复制标题
DOI：
10.1073/pnas.91.26.12418
复制
发表时间：
1994-12-20
影响因子：
11.1
通讯作者：
STANLEYSAMUELSON, DW
中科院分区：
文献类型：
--
作者：
MILLER, JS;NGUYEN, T;STANLEYSAMUELSON, DW
我们认为昆虫体内的根瘤形成是由二十烷基类化合物介导的。结瘤是昆虫和其他无脊椎动物对细菌感染的时间和数量上占优势的细胞防御反应。在粘质沙雷氏菌血腔内感染之前，抑制烟草角虫Manduca sexta幼虫二十烷类化合物的生物合成大大降低了结瘤反应。抑制二十烷基类化合物的生物合成也减少了侵染后1小时细胞聚集体的形成，这表明二十烷基类化合物参与了结瘤的早期阶段。单独使用磷脂酶A(2)、环氧合酶和脂氧合酶的特定抑制剂可以减少结瘤，这支持了结瘤是一个涉及前列腺素和脂氧合酶产物的复杂过程的观点。磷脂酶A(2)抑制剂地塞米松在感染后1小时对结瘤有明显的抑制作用，24小时后抑制作用增强。地塞米松的作用是以剂量依赖的方式表现出来的，并通过用二十烷类前体多不饱和脂肪酸处理受感染的昆虫来逆转。用不是二十烷类前体的饱和脂肪酸16：0处理，不能逆转地塞米松对结瘤的影响。这些发现有力地支持了结瘤是一种特定的昆虫细胞防御机制的鉴定，这种机制是由二十烷基类化合物介导的。
We propose that nodule formation is mediated by eicosanoids in insects. Nodulation is the temporally and quantitatively predominant cellular defense response to bacterial infection in insects and other invertebrates. Inhibition of eicosanoid biosynthesis in larvae of the tobacco hornworm Manduca sexta immediately prior to intrahemocoelic infections with the bacterium Serratia marcescens strongly reduced the nodulation response. Inhibition of eicosanoid biosynthesis also reduced formation of cellular aggregates at 1 hr postinfection, which indicates that eicosanoids mediate early stages of nodulation. Separate treatments with specific inhibitors of phospholipase A(2), cyclooxygenase, and lipoxygenase reduced nodulation, which supports the view that nodule formation is a complex process involving prostaglandins and lipoxygenase products. The inhibitory effects of the phospholipase A(2) inhibitor dexamethasone on nodulation were apparent by 1 hr after infection, and the effects increased, relative to controls, over 24 hr. The dexamethasone effects were expressed in a dose-dependent manner, and they were reversed by treating infected insects with eicosanoid-precursor polyunsaturated fatty acids. Treatments with the saturated fatty acid 16:0, which is not an eicosanoid precursor, did not reverse the dexamethasone effects on nodulation. These findings strongly support the identification of nodulation as a specific insect cellular defense mechanism that is mediated by eicosanoids.