栉孔扇贝鳃和唇瓣过氧化物酶活性

Peroxidase activity in gill and labial palps of scallop Chlamys farreri

采用组织化学、电镜细胞化学和分光光度技术对栉孔扇贝(Chlamys farreri)鳃和唇瓣内的过氧化物酶(EC1.11.1.7;POD)进行研究,以探讨扇贝的鳃和唇瓣在免疫防御中的作用。组织化学显示,鳃轴、鳃丝和唇瓣上皮细胞均呈POD强阳性,结缔组织呈弱阳性;病毒感染后酶活力逐步增强。电镜细胞化学定位表明,鳃和唇瓣上皮细胞内有数量和大小不等的POD强阳性颗粒,阳性颗粒多为圆形,直径为150-220 nm;次级溶酶体也呈POD强阳性;内质网和空泡膜等细胞内膜系统以及细胞表面的微绒毛和纤毛呈POD弱阳性。结缔组织中部分血细胞呈POD强阳性。鳃轴上皮细胞内POD高电子密度阳性颗粒较少,而低电子密度阳性颗粒较多;主鳃丝上皮细胞内POD阳性颗粒较少,普通鳃丝上皮细胞内POD高电子致密阳性颗粒和呈POD强阳性的次级溶酶体均较多;唇瓣上皮细胞内POD阳性颗粒较鳃的略少。生化测定显示,鳃轴的POD酶活力最高,鳃丝次之,唇瓣最低;病毒感染24 h后,各部分的酶活力均显著增强。栉孔扇贝鳃和唇瓣内大量的POD可在抵抗病原微生物感染方面发挥重要的作用。

The peroxidase (EC1. 11. 1.7, POD) in gill and labial palps of scallop Chlamys farreri were studied with histochemical, cytochemical and spectrophotometric method. The aim of this study was to probe into the role of gill and labial palps in immunological defense of scallop. The results of histochemical localization showed that all of the epithelial cells of branchial axis, branchial filaments and labial palps pre-sented strong POD positivity; the connective tissue of branchial axis, branchial filaments and labial palps pre-sented weakly positive to POD. The results of cytochemical localization under electron microscope were as follows:POD-strong positive granules were found in cytoplasm of epithelial cells in the gill and the labial palps; the number and the size of POD-strong positive granules in the epithelial cells were not alike;most granules were round with 150- 220 nm in diameter. Secondary lysosomes presented strong POD positivity too. Endomembrane system such as endoplasmic reticulum, vavuole membrane presented weakly positive of POD. Cilia and microvilli on the surface of the epithelial cells in the gill and the labial palps presented weak-ly positive of POD. Part of blood cells in connective tissue presented strong POD positivity. The number of POD positive granules with high electron density was fewer than the number of POD positive granules with low electron density in the epithelial cells of branchial axis. POD positive granules in the epithelial cells of main gill filaments were not rich. POD positive granules with high electron density in the epithelial cells of ordinary gill filaments were rich. Secondary lysosomes which present strong POD positivity in the epithelial cells of ordinary gill filaments were rich too. The number of POD positive granules in the epithelial cells of labial palps was fewer than in the gill. The enzyme activity of POD in the tissue of branchial axis, branchial filaments and the labial palps were assayed by biochemical test. The POD activities in the tissue of branchial axis, branchial filaments and labial palps were respectively 111.98 U,74.40 U and 41.38 U(pH 6.8, 37 ℃) . The Ievels of POD activity was the highest in branchial axis and was the lowest in the labial palps. After injection with the viruses,the POD activities of experimental groups in gill andlabial palps at 24 h were higher than that of control groups. The results of POD determinations suggest that POD in the gill and the labial palps may play an important role in protection from pathogens in Chlamys farreri.