Monitoring of xenobiotic stress in fish by an acute phase protein

Abstract C-reactive protein (CRP) is a classic example of an acute phase plasma protein which is normally present at detectable levels (200–240 μg/ml of serum) in the fish Channa punctatus . Environmental chemicals are known to induce CRP synthesis in rat, where it is a trace component. Therefore an attempt was made to mount an acute phase response in fish by xenobiotics to assess whether CRP can be utilized as a biomonitoring tool. Channa punctatus were exposed to nonlethal levels of mercuric chloride (0.11 ppm), cadmium chloride (33.3 ppm), ammonia (36 ppm), phenol (10 ppm), metacid-50 (0.533 ppb) and carbaryl (3.73 ppm). Blood sampling was done at 12, 24, 48 and 72 h of exposure. CRP level was estimated by the Single Radial Immunodiffusion (SRID) technique using a monospecific antiserum of Channa punctatus CRP raised in white rabbit. At all time periods and with all xenobiotics, except Cd at 72 h, the CRP level was significantly elevated. Heavy metals caused the acute phase within 24 h and nonmetals and metacid-50 within 48 h of exposure. Carbaryl showed a biphasic response, elevating the CRP level at 12 h of exposure and then again at 48 h. It is concluded that the CRP level in the serum of fish may be used as a parameter of acute poisoning by xenobiotics.