Cu2+胁迫对克氏原螯虾(Procambarus clarkii)酚氧化酶原激活系统活性的影响

重金属铜是养殖水体的主要污染物,严重影响甲壳动物的免疫机能。以淡水克氏原螯虾(Procambarus clarkii)为实验对象,以亚致死浓度(1.0、3.0、5.0、10.0 mg·L~(-1),96-h LC50=22.14 mg·L~(-1))的Cu~(2+)为胁迫因子,采用静态水质接触染毒法,通过分析血细胞内酚氧化酶原(pro PO)、丝氨酸蛋白酶(SP)以及血淋巴中酚氧化酶(PO)、血蓝蛋白(Hc)和血细胞数(THC)的水平,探讨了Cu~(2+)胁迫对酚氧化酶原激活系统(pro PO-AS)活性的影响。结果表明,与未染毒的对照组相比,Cu~(2+)显著抑制proPO、PO的活性以及THC、Hc的含量(P0.05);但仅在10.0 mg·L~(-1)Cu~(2+)浓度下,SP的活性显著降低(P0.05)。研究结果提示,水体Cu~(2+)对螯虾具有免疫毒性效应,氧化应激导致的血细胞数、血蓝蛋白含量、丝氨酸蛋白酶活性抑制可能是影响pro PO-AS活性的主要机制之一。

Effect of Cu2+ stress on activity of prophenoloxidase activating system in Procambarus clarkii

Copper(Cu) is one of ubiquitous contaminants in the aquatic environment, causing potential immunotoxicity to crustacean. In the present study, the effect of Cu²⁺ stress on prophenoloxidase activating system(proPO-AS), the most important component of innate defense, was evaluated in freshwater crayfish Procambarus clarkii. After 96 h exposure to sub-lethal concentrations(0, 1.0, 3.0, 5.0 mg·L^-1 and 10.0 mg·L^-1) of Cu²⁺, the activities of prophenoloxidase(proPO) and serine protease(SP) in hemocyte lysate supernatant(HLS) and the levels of total haemocyte count(THC), phenoloxidase(PO), and hemocyanin(Hc) in haemolymph were determined. Results indicated that there was a significant reduction(P<0.05) in crayfish immunocompetence, including proPO, PO, THC, and Hc, at higher Cu²⁺ concentrations. The SP activity was obviously inhibited only at 10.0 mg·L^-1 Cu²⁺. The aqueous Cu²⁺ may play an important role in regulating proPO-AS by inhibiting THC, Hc, and SP. The immune factors, such as THC, proPO, and PO, could be considered as sensitive biomarkers of immunotoxicity in crayfish species.