烟夜蛾幼虫血淋巴凝集素的理化特性研究

Study on physico-chemical properties of hemolymph lectins in Helicoverpa assulta larvae

为了明确烟夜蛾Helicoverpa assulta幼虫血淋巴凝集素的理化性质,采用糖抑制试验和血凝法检测,分别测定了凝集素与不同糖类的结合特性和不同因素对其凝集活性的影响.糖抑制试验结果表明,在选用13种糖类中,不同糖类对凝集素凝集活性的抑制作用不同,其中乳糖、D-半乳糖和L-鼠李糖具有完全抑制作用,说明烟夜蛾幼虫血淋巴凝集素与这3种糖类有专一结合特性.血凝法检测结果表明,不同因素对凝集活性的影响不同,其中烟夜蛾血淋巴凝集素凝集活性依赖于Ca2+,属C型凝集素;反复冻融对凝集素的活性没有影响;但随处理温度的升高或持续时间的延长,其凝集活性下降,在60℃处理15 min后凝集活性完全丧失;凝集素在p H 7.17时活性最高;凝集素对经胰蛋白酶修饰后的鸭血红细胞的凝集活性明显增强;血淋巴中酚氧化酶引起的黑化未对其凝集活性产生影响,说明同为体液免疫因子的凝集素与酶氧化酶在昆虫免疫防御中的协同性.

The physico-chemical properties of Helicoverpa assulta larval lectins were investigated by comparing the inhibitory activity of thirteen sugars on the hemagglutination of the duck erythrocytes and hemagglutination reaction. The results indicated that H. assulta leetins could bind galaetose, lactose, and rhamnose. The effects of different factors The effectson the hemagglutinating activity of H. assulta lectins were different. The H. assulta lectins were found to belong to the C-type （calcium-dependent） lectin family. The hemagglutinating activity was not influenced after repeated cycles of freezing and thawing, but it declined with increasing temperature and duration. All activity was lost at 60 ℃ for 15 min. The lectins had high hemagglutinating activity at pH 7.17. The agglutinin ability increased when duck erythrocytes were treated with trypsin. The hemagglutinating activity of lectins was not affected by the phenoloxidase-induced melanization reaction in the hemolymph, This suggested that leetins and phenoloxidase played synergistic effects in the humoral immune mechanisms of insects.