Changes in Behavior and Brain Acetylcholinesterase Activity in Mosquito Fish, Gambusia affinis in Response to the Sub-Lethal Exposure to Chlorpyrifos

Abstract

Sub-lethal studies of chlorpyrifos, O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate on mosquito fish, Gambusia affinis were carried out in vivo, for 20 days to assess the locomotor behavior in relation to bioaccumulation and interaction with a targeted enzyme, acetylcholinesterase (AChE, EC: 3.1.1.7). Fish exposed to sub-lethal concentration of 60 microg/L (1/5 of LC 50) were under stress, and reduced their locomotor behavior like distance travelled per unit time (m/min) and swimming speed (cm/sec) with respect to the length of exposure. The alteration in locomotor behavior of fish may be due to an accumulation of acetylcholine (ACh), a neurotransmitter at synaptic junctions, due to the inhibition of AChE enzyme activity (40 to 55%) in brain and also bioaccumulation of the toxicant in different parts of fish. The bioaccumulation values indicated that the accumulation of chlorpyrifos was maximum in viscera followed by head and body. The average bio-concentration values are 0.109, 0.009 and 0.004 microg/g for viscera, head and body with depuration rates of 2.24, 1.69 and 0.39 ng/h respectively. It is evident from the results that the sub-lethal concentration [1/5 of LC 50; equivalent to Lowest Observed Effect Concentration (LOEC)] of chlorpyrifos can able to alter the locomotor behavior of G. affinis in relation to the length of exposure. The findings revealed that the locomotor activity of test organism could be considered as a suitable marker to evaluate the affect of toxicant even at LOEC levels.

Acute toxicity and behavioral changes of Caspian kutum (Rutilus frisii Kutum Kamensky, 1991) and Caspian roach (Rutilus rutilus caspicus Jakowlew, 1870) exposed to the fungicide hinosan

“…At doses of 16 ppm, some fishes had curvature in vertebral column and collapsed to the bottom of the aquarium. These findings coincided with those of other authors who studied acute toxicity of other organophosphorus pesticides (Rao et al, 2005;Rao, 2006;Pandey et al, 2005). Maximum Allowable Concentration (MAC) in natural environments according to LC 50 96 h is 0.1 LC 50 level.…”

Risks to Aquatic Organisms from Use of Chlorpyrifos in the United States

“…Zebrafi sh ( Danio rerio ) exposed to 220 μg CPY L −1 for 24 h exhibited impaired swimming behavior (p <0.01) and a concentration-response relationship was observed at concentrations greater than 35 μg L −1 (Tilton et al 2011 ). Similarly, locomotory behavior of mosquito fi sh, Gambusia affi nis , was affected by exposure to 60 μg CPY L −1 for 20 d (Rao et al 2005 ). Although exposures to concentrations of CPY of 100 and 200 μg L −1 caused depression of whole-body AChE (≈60% of controls) in tadpoles of Rana sphenocephala , there were no effects on swim-speed or vulnerability to predation (Widder and Bidwell 2006 ).…”

Histopathological effects of Cyperdicot and vitamin E supplementation on selected organs of Clarias gariepinus (Burchell, 1822) reared in a tropical fish farm in Nigeria

“…The histopathological effects on the gills of freshwater fish showed necrosis, abnormalities to gill lamellae, extensive fusions of secondary lamellae, and a thick coat of mucus on the gill filaments upon exposure to Cyperdicot (Rao et al, 2005). In addition, hyperplasia of the gill filaments, edema separation of primary gill lamellae, haemorrhage in the blood vessel, clubbing, fusion of adjacent filaments, and hyperplasia in the secondary lamellae in freshwater Clarias gariepinus exposed to Cyperdicot were also observed.…”