Studies On Toxicity And Tissue Elimination Of Sulfamethoxazole And Trimethoprium On Fenneropenaeus Chinensis

This thesis is divided into two parts, one part firstly reports the acute toxicity and chronic toxicity of sulfamethoxazole(SMZ) and trimethoprium (TMP) (5:1) for the larvae and the juvenile of Fenneropenaeus chinensis. The other part firstly reports the residual characteristics of SMZ in muscle, blood and liver. The main results are as follows:1. The acute toxicity of SMZ and TMP(5:1) for the nauplius larvae, zoea larvae of Fenneropenaeus chinensisThe nauplius larvae, zoea larvae of Fenneropenaeus chinensis are bred in the seawater of 0, 100, 200, 300, 400, 500 mg/L respectively for 48h at water temperature 19.5²1.5℃. The mortality of the larvae of Fenneropenaeus chinensis is noted at 24h and 48h. The test shows that the 24h-LC_(50)^S (median lethal concentrations) and 48h-LC_(50)^S of nauplius larvae,zoea larvae were 300 mg/L, 355 mg/L and 232 mg/L, 172 mg /L respectively ; The safe concentration of nauplius larvae, zoea larvae were 42 mg/L, 12 mg/L respectively.2. The effects of SMZ and TMP(5:1) for the growth of juvenile of Fenneropenaeus chinensisAt water temperature 19²6℃, the juvenile of Fenneropenaeus chinensis are exposed for 35 days, the gain of the body weight and total length of shrimps exposed to SMZ and TMP(5:1) at 50 mg/L is of no significant difference to the control, but it is significantly lower(P<0.01) than the control at 100 mg/L and 200 mg/L. The MATC (maximum acceptable toxicant concentration) is 50 mg/L SMZ and TMP(5:1) based onthe growth.3. The chronic toxicity of SMZ and TMP(5:1) for the juvenile of FenneropenaeuschinensisAt water temperature 20²6.5°C, the juvenile of Fenneropenaeus chinensis are exposed for 16 days, the shrimps of the experimental groups (300 rog/L,450 mg/L and 600 mg/L)appears anorexia, lethargy and a high mortality. The haematological changes in the experimental shrimps show that the blood corpuscle concentration drop significantly (PO.05) to the control; the serum AST> ALT activity drop markedly in 300 mg/L and 450 ffig/L dosage group and rise markedly in 600 mg/L dosage group. The results of histopathology research on poisoned shrimps show that high concentration of sulfamethozazole and trimethoprium causes abnormal histological changes in the tissues of shrimp's hepatopancreas, branchia and stomach, etc. The histopathological process involves the series of changes from cellular swelling to vacuolation and at last necrosis. 4. The residue and elimination characteristics of SMZ in Fenneropenaeus chinensisThis thesis firstly reports the residual characteristics of SMZ, which is many times taken orally, in Fenneropenaeus chinensis at 20±2°C . The medicine is distilled by methylene chloride from muscle, blood and liver. The concentrations of medicament is determined by High Performance Liquid Chromatography, the average recoveries are 80 %—90 % and the limits of determination was 0.01 jig/mL. The results indicate that the medicament residue and the speed of elimination change in different tissues. The residue in the liver is more than muscle and blood, and the speed of elimination of residue in the liver is the slowest .The liver is the optimal target tissue for SMZ residue controlment. The with-holding period for Fenneropenaeus chinensis after oral administration at dose of 50 mg/kg with SMZ for 5 consecutive days should be 20 days at water temperature 20±2°C.