几种化学因子对三种赤眼蜂离体酚氧化酶活性的影响

为比较不同赤眼蜂酚氧化酶（PO）活性的大小, 明确赤眼蜂种间免疫防御能力强弱, 本研究通过研磨、离心提取松毛虫赤眼蜂Trichogramma dendrolimi、螟黄赤眼蜂T. chilonis、玉米螟赤眼蜂T. ostriniae匀浆液, 首次测定了几种化学因子（Ca²⁺、昆布多糖、纤维素、右旋糖酐、脂多糖和丝氨酸蛋白酶抑制剂）对3种供试赤眼蜂匀浆液中酚氧化酶原激活系统（proPO-AS）的激活程度。结果表明: 玉米螟赤眼蜂匀浆液PO活性最高, 螟黄赤眼蜂次之, 松毛虫赤眼蜂最低。Ca²⁺是激活供试赤眼蜂proPO的必需因子, 且在0.03 mol/L浓度下激活作用最强; 昆布多糖和脂多糖也能有效激活proPO, 0.01及0.05 mg/mL昆布多糖能强烈激活PO活性; 纤维素和右旋糖酐对PO活性存在显著抑制作用。结果证明了赤眼蜂种间存在明显的免疫能力差异。本研究建立了小型昆虫proPO-AS研究体系, 为研究Wolbachia-小型昆虫的免疫互作体系奠定了基础。

Effects of several chemical factors on the activity of prophenoloxidase from three species of Trichogramma (Hymenoptera: Trichogrammatidae) in vitro

Prophenoloxidase-activating system (proPO-AS) is one of the most important humoral immunity systems in insects. The crude extracts of Trichogramma ostriniae, T. chilonis and T. dendrolimi were collected by grinding and centrifugation, and PO activities of three Trichogramm species induced by calcium ions, laminarin, dextran, and PMSF were compared. The results indicated that the highest PO activity was found in the crude extract from T. ostriniae, followed by T. chilonis, and then T. dendrolimi. Ca~(2+) was required for PO activation, and the maximal activation was observed at the Ca~(2+) concentration of 0.03 mol/L. Laminarin and lipopoyusaccharide could also effectively activate proPO, and 0.01 and 0.05 mg/mL laminarin caused strong activation. Cellulose and dextran were proved to be significant inhibitors to PO. A model for proPO-AS studies of small insects was established, which provides an experimental basis for studying the interaction of immune system of symbiotic bacteria-small insects.