杂色鲍血细胞中一氧化氮合酶活性的鉴别

一氧化氮合酶(Nitric oxide synthase,NOS)是催化L-精氨酸与O_2产生一氧化氮(Nitric ox- ide,NO)的一种合成酶,它广泛存在于生物体的各个器官和组织中,其活力大小可通过测定NO合成量的多少来决定。NO作为一种新型生物信使分子、效应分子和免疫调节分子,参与机体多种重要的生理病理活动,可以通过非特异性地杀伤细菌、真菌、寄生虫及病毒等。增强机体的非特异性免疫。本文采用生物化学法,以副溶血弧菌和脂多糖为刺激因子.并采用硝酸盐还原酶法测定了NO的水平,对杂色鲍血细胞中的NOS活性进行了初步鉴别。结果表明,加入副溶血弧菌组或LPS组NO水平显著高于对照组(P<0.05),孵育4h后分别为对照组的1.84和1.92倍,孵育8h后分别为对照组的2.38和3.05倍,而且这一反应能被NOS抑制剂L-NAME所阻断,说明杂色鲍血细胞中存在NOS活性。

Identification of NOS activity in Haliotis diversicolor haemocytes

Nitric oxide synthase(NOS)is ubiquitous in organs and tissues of all living or- ganisms,where it catalyzes the conversion of L-arginine to L-citrulline and produces nitric oxide (NO).Its activity can be determined by measuring the quantity of NO.NO is involved in multi- ple physiological functions as a new biological messenger molecule,effective molecule and im- munology regulation molecule.It takes part in many important physiological and pathological reactions,and kills bacteria,fungi,parasite or virus through improving the non-specific immune function.In this study,the NOS activity in Haliotis diversicolor haemocytes was identified as induced by Vibrio parahaemolyticus and Lipopolysaccharide(LPS).The NO concentration was determined by measuring the quantity of nitrite and nitrate.The treatments for which V.para- haemolyticus or LPS was added showed much higher NO concentrations than the control(P<0.05);and they were 84% and 92% higher than the control,respectively,after 4 h of incuba- tion,and 138% and 205% higher,respectively,after 8h of incubation.This reaction could be inhibited by analog of L-arginine(L-NAME),which was the inhibitor of mammalian NOS. Therefore,it could be concluded that NOS activity exists in haemocytes of H.diversicolor.