Liu C T, Hou R F, Ashida M, Chen C C
Department of Parasitology, School of Medicine, National Yangming University, Taipei, Taiwan, Republic of China.
Parasitology. 1997 Jul;115 ( Pt 1):57-68. doi: 10.1017/s0031182097001108.
The melanization of Dirofilaria immitis microfilariae in Armigeres subalbatus haemolymph in vitro is a two-step process. Firstly, the microfilariae are encased in a transparent capsule, then the capsule material is melanized later. Benzamadine HC1 and p-amidinophenylmethanesulfonyl fluoride, both serine protease inhibitors, inhibited the deposition of the transparent capsule material and melanization. Diethyldithiocarbamate, a phenoloxidase inhibitor, did not prevent the deposition of the transparent capsule material but it did inhibit melanization. m-Hydroxybenzylhydrazine, a dopa decarboxylase inhibitor, had no inhibitory action on the deposition of the transparent capsule material. However, the time for the transparent capsule to become melanized was delayed due to the presence of m-hydroxybenzylhydrazine in the test system. Immmunocytochemical localization showed that propheoloxidase and/or phenoloxidase was present in the transparent capsule material. These results suggest (1) that prophenoloxidase cascade is essential in the melanization of microfilariae in mosquitoes and its putative activation behaviour is similar to that of other insects and (2) that the deposition of transparent capsule material is the result of the activation of prophenoloxidase by serine proteases and the melanization of the transparent capsule material is due to the presence of active phenoloxidase in capsule.
体外培养时，致倦库蚊血淋巴中犬恶丝虫微丝蚴的黑化是一个两步过程。首先，微丝蚴被包裹在一个透明的囊中，随后囊物质被黑化。苯甲脒盐酸盐和对脒基苯甲磺酰氟这两种丝氨酸蛋白酶抑制剂，抑制了透明囊物质的沉积和黑化。二乙基二硫代氨基甲酸盐，一种酚氧化酶抑制剂，并未阻止透明囊物质的沉积，但它确实抑制了黑化。间羟基苄基肼，一种多巴脱羧酶抑制剂，对透明囊物质的沉积没有抑制作用。然而，由于测试系统中存在间羟基苄基肼，透明囊黑化的时间被延迟。免疫细胞化学定位显示，前酚氧化酶和/或酚氧化酶存在于透明囊物质中。这些结果表明：（1）前酚氧化酶级联反应在蚊子体内微丝蚴的黑化过程中至关重要，其假定的激活行为与其他昆虫相似；（2）透明囊物质的沉积是丝氨酸蛋白酶激活前酚氧化酶的结果，而透明囊物质的黑化是由于囊中有活性酚氧化酶的存在。
