Morphological and physiological abnormalities during development in zebrafish due to chlorpyrifos

Chlorpyrifos, a widely used organophosphate pesticide in agriculture and urban house hold has been receiving growing environmental concern due to its different biological activities. In this study we made an attempt to examine the potential developmental effects of non-lethal concentration of chlorpyrifos using zebrafish (Danio rerio) model. Fertilized eggs of the same developmental stage, 4 hours post fertilization were exposed to four different concentrations of chlorpyrifos namely 400 μg/L, 600 μg/L, 800 μg/L and 1000 μg/L. Hatching rate, morphological abnormalities were observed using Olympus microscope. Delay in hatching was noticed at higher concentrations of chlorpyrifos. Abnormalities like edema, difference in yolk sac size and decrease in pigmentation were observed in embryos before hatching, where as in larvae edema, shrinking of yolk sac and dorsal curvature of the body was noticed. From the studies carried out chlorpyrifos was shown to delay hatching and also caused different morphological abnormalities. These two could be due to slower utilization of yolk.