Effect of methyl parathion and chlorpyrifos on certain biomarkers in various tissues of guppy fish, Poecilia reticulata

Tests of acute toxicity were performed on the most common species of aquarium fish, Poecilia reticulata. Guppies (P. reticulata) were exposed to progressive concentrations of methyl parathion (MP) and chlorpyrifos (CPF); a semi-static method according to guidelines of OECD was used. Tests of acute toxicity were conducted using 10 fish for each separate concentration and for the control group. The results were subjected to probit analysis to determine the 96 h LC₅₀ values. The 96 h LC₅₀ values of MP and CPF to P. reticulata were 8.48 ppm/L (5.98–10.89) and 0.176 ppm/L (0.313–0.224) respectively. In addition, behavioral changes at each concentration were observed for the individual fish. Fish were exposed for 96 h to different sublethal concentrations of MP and CPF (¼ LC₅₀, 1/8 LC₅₀ and 1/10 LC₅₀) and their oxidative stress-induction potential was estimated in brain, liver and gills of fish. MDA content is induced in all tissues but maximum rise was observed in gills (161% and 153% for MP and CPF respectively). With regard to antioxidant defense system (ADS), GSH level decreased in the brain, liver and gills of tissues of MP treated fishes (22%, 6% and 13% respectively) and showed increase in brain and gills CPF treated (23% and 21% respectively). CAT, GST, GR and SOD levels fluctuated in all treatment groups relative to the control. Brain AChE showed dose-dependent inhibition in fish exposed to the higher concentrations reached 45% and 66% for MP and CPF respectively. Collective findings demonstrated that pesticide exposure of fish induced an increase in MDA and fluctuated ADS along with inhibited AChE. These findings may be used as valuable biomarkers for evaluation of water pollution.     

Hemolytic assay for goat (caprine) and swine (porcine) complement

Optimal conditions for assaying hemolytic complement of goat (caprine) and swine (porcine) sera were determined. Effects of the following were tested: pH, ionic strength, calcium and magnesium ion concentrations, time and temperature of incubation, and ethylenediamine tetracetate concentration. Guinea pig erythrocytes sensitized with goat or cattle antibodies were the most sensitive target cells for goat complement. Sheep and cattle erythrocytes sensitized with rabbit hemolysin were the best target cells for swine complement. Barbital buffer, pH 7.3, ionic strength of 90 nmM relative salt concentration, containing 0.5 mM CaCl2 and 1 mM MgCl2 was the best for swine complement assay. Goat complement lysed best in a barbital buffer, pH 8, ionic strength of 90 to 120 mM of relative salt concentration, in presence of 0.5 mM CaCl2 and 1 mM MgCl2. The optimal incubation temperature was 37 degrees C for both complements. The complement dependent lysis required 75 minutes to reach its maximum. Ethylenediamine tetracetate in 4 mM concentration completely inhibited lysis by both species complements. The CH50 for goat sera varied between 18 and 75 per ml, in swine sera between 75 and 210 per ml.