金鱼藻抗氧化酶对水体无机氮升高的响应

RESPONSES OF ANTIOXIDASES OF CERATOPHYLLUM DEMERSUM TO THE INCREASE OF INORGANIC NITROGEN IN WATER COLUMN

为了研究水体富营养化引起的无机氮升高对沉水植物的胁迫 ,本研究用 4种浓度的碳酸铵和 5种浓度的硝酸钾对金鱼藻进行急性处理 ,分别在 5— 4 8h内测定植株超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶 (APX)的活力。结果表明铵盐处理下 4种酶中CAT活性变化最大 ,在 5— 15h时其活性与处理浓度正相关。更长时间 2 4h处理则导致响应停止。硝酸盐处理下SOD、APX和CAT活性在 2 4h时才有明显升高。SOD和CAT活性在 4种酶中变化最大 ,它们对处理浓度变化的响应趋势都是在低浓度处理上升然后在较高浓度下降。在铵盐和硝酸盐处理下APX活性都是在 4种酶中最低 ,其变化规律与CAT相当一致。本研究表明CAT对铵盐胁迫响应较快 ;SOD和CAT对硝酸盐胁迫的响应速度较铵盐慢 ;

Acute responses of four antioxidant enzymes:superoxide dismutase(SOD,EC 1.15.1.1),catalase(CAT,EC 1.11. 1 6) peroxidase(POD,EC 1.11.1.7)and ascorbate peroxidase (APX,EC1.11.1.11),of Ceratophyllum demersum to inorganic nitrogen enrichment in water column were investigated after 5—24h incubations with potassium nitrate or ammonium carbonate,and thus to evaluate the stress of inorganic nitrogen enrichment in water column on submersed macrophytes.In this experiment,the concentrations of NO 3 N were ranged from 1mg/L to 20mg/L,and the concentrations NH 4 N were ranged from 1mg/L to 100mg/L. The results show that in the ammonium treatments,CAT activity was the highest among the four enzymes.In the 5h and 15h after the treatments,the activity of CAT showed a concentration dependent increase,but there were no significant differences in CAT activity among treatments as the incubation prolonged to 24h.In the treatments with nitrate,SOD,APX and CAT activities changed significantly only at 24 hr after the treatment.SOD and CAT activities were the highest in the four enzymes.The activities of both enzymes showed a peak at 5mg/L nitrate. APX activity was the lowest among the four enzymes both in ammonium and nitrate treatments.The trend of APX was similar to that of CAT.This experiment suggested that CAT show a quick response to ammonium enrichment in water,whereas SOD and CAT show delayed response of 15—24h to that of nitrate.CAT and SOD are possible indicators for submersed macrophytes under the stress of inorganic nitrogen enrichment in water.