褐飞虱和桃蚜粗提液中酚氧化酶原激活系统的激活特点

Features of the prophenoloxidase-activating system in crude extracts of Nilaparvata lugens and Myzus persicae

采用研磨法制备褐飞虱Nilaparvata lugens（Stal）和桃蚜Myzus persicae（Sulzer）粗提液，用于研究几种化学因子对粗提液中酚氧化酶原激活系统（proPO．AS）的激活特点。结果表明，在0．1—100mmol／L的Ca^2＋浓度范围内，虱液和蚜液的酚氧化酶（PO）活性随Ca^2＋浓度升高而增强，并在30mmol／L处PO活性达到最高，在此限之上PO活性反而下降。当昆布多糖浓度从10^-4mg／mL升至10mg／mL时，虱液和蚜液的PO活性也随之升高，但再提高昆布多糖浓度却未见PO活性的峰顶出现。在6种葡聚糖对PO的激活作用中，昆布多糖和酵母聚糖能显著增强PO活性，但curdlan对虱液和蚜液的PO无明显激活作用，而甘露聚糖、右旋糖苷和纤维素则降低PO活性。这些结果显示β-1，3-葡聚糖能有效激活proPO-AS。Ca^2＋和丝氨酸蛋白酶抑制剂PMSF加样顺序的不同也会影响PO活性。

The prophenoloxidase （proPO） activating system （proPO-AS） involved in crude extracts of rice planthopper Nilaparvata lugens （Stal） and green peach aphid Myzus persicae （Sulzer） was investigated in relation to potentially influential agents. The results showed that as Ca^2＋ concentration increased from 0.1 mmol/L to 100 mmol/L, the activities of phenoloxidase （PO） in the crude extracts of N. lugens and M. pers/cae were concentration dependent. The activation of the proPO peaked at 30 mmol/L of the Ca^2＋ concentration. However, a further increase of the Ca^2＋ to 100 mmol/L resulted in a decrease in proPO activation. Incubation of the extracts in conjunction with different concentrations of laminarin （from 10^-4mg/ mL to 10 mg/mL） witnessed the levels of proPO activation entirely depending on the laminarin concentrations. When different glucans were used as activating agents, laminarin and zysoman significantly enhanced the PO activities whereas the effect of curdlan was not significant compared to a blank control. In contrast, the PO activities were reduced when mannan, dextran or cellulose was added. These results indicated that the β-1,3- glucan effectively activated the proPO present in the extracts of the two insect species with the proPO-AS selectively responding to different glucans. The sequence of adding Ca^2＋ and phenylmethyl sulfonyl fluorid （a serine protease inhibitor） in the extracts also affected the PO activities.