Effects of sublethal concentrations of tobacco (Nicotiana tobaccum) leaf dust on some biochemical parameters of Hybrid catfish (Clarias gariepinus and Heterobranchus bidorsalis)

The aim of this work was to study the effect of tobacco (Nicotiana tobaccum) leaf dust at sublethal concentrations (375.6, 187.8, 93.9 0.0mg/L) on biochemical parameters of Hybrid catfish in a static semi-renewable bioassay system with the aim to ascertain its effect on the test fish after 14 days exposure period. The effects of the plant dust on the test fish was dose-dependent, revealing significant difference in albumin, glucose, triglyceride, cholesterol, urea, and uric acid of the serum, liver and kidney; total protein and globulin of serum and kidney and creatinine and calcium of the serum while insignificant difference were observed for calcium and creatinine in liver and kidney and total protein and globulin in liver compared to the control. The effect of the plant dust was most pronounced in the serum, less in the kidney and least in the liver. However, the monitored water quality parameters revealed that the plant dust had effects on primary productivity, thus the biodiversity of organisms.

Gene expression of acetylcholinesterase in hybrid catfish (Clarias gariepinus X Clarias macrocephalus) exposed to chlorpyrifos and carbaryl.

After serving as a neurotransmitter, acetylcholine is hydrolyzed by acetylcholinesterase (AChE). Inhibition of AChE is considered to be a specific biomarker for exposure to organophosphate and carbamate insecticides. In this study, the AChE gene was isolated from hybrid catfish brain by RT-PCR methods using degenerate primers. The amplified fragment of 966 nucleotides generated by PCR was cloned, and sequence analysis showed 82% nucleotide identity with AChE of the Electrophorus electricus. Specific primers of the hybrid catfish AChE gene were then synthesized and used in the examination of AChE gene expression in brain tissue of hybrid catfish exposed to sublethal concentrations of chlorpyrifos (0.43, 4.3 and 43 2M) and carbaryl (1.19, 11.9 and 119 2M) for 24 hr. Real-time PCR was used to compare with the amplified 28S rRNA gene. AChE gene expression was significantly elevated 12.4 times in catfish exposed to 43 2M chlorpyrifos in comparison to the control group (p<0.05). Carbaryl did not produce any significant change. These results indicate that AChE is more sensitive to administration of chlorpyrifos than carbaryl. The induction of the AChE gene indicates the possibility of using this gene as biomarker for detecting effects of organophosphate insecticides in hybrid catfish.