Influence of nitrate nitrogen on immune factors in serum of Pacific white shrimp (Litopenaeus vannamei)

Four groups with different nitrate nitrogen ( NO3--N) concentrations (4.24 mgL-1 , 35 mgL-1 , 70 mgL-1 , 105 mg L-1 and 140 mgL-1) and a control group were set to study the effect of nitrate nitrogen on immune factors in serum of Pacific white shrimp ( Litopenaeus vannamei) . The activities of prophenoloxidase ( PO) , superoxide dismutase ( SOD) , alkaline phosphatase ( AKP) , acid phosphatase ( ACP) , lysozyme ( LSZ) and nitric oxide synthase ( NOS) in the serum were determined. Results show thatNO3--N concentration of no more than140 mgL-1 had effect on the activities of SOD, PO, ACP, AKP, TNOS, iNOS and LSZ in a short time, which weakened gradually along with time. At 48thhour, the activity of iNOS in other groups had no significant difference, except the 35 mgL-1 group.