Sublethal effects of diphenyl ether on zebrafish embryo: Developmental, morphological, cardiac and neurotoxic implications

In 2009, the United Nations Environment Programme classified the polybrominated diphenyl ethers (PBDEs) as an emerging class of persistent organic pollutants. In the environment, less brominated diphenyl ethers can be formed by the degradation of PBDEs. In the present study, zebrafish embryo-larvae were exposed to 1.28 mg/L (¹/₄ LC₅₀) and 2.57 mg/L (¹/₂ LC₅₀) of Diphenyl ether (DE) upto 96 h. Effects of sublethal concentrations of DE on acute developmental toxicity, morphology, body growth, heart rate, sinus venosus- bulbus arteriosus (SV-BA) distance, spontaneous movement and sensorimotor response in zebrafish larvae were studied. DE significantly decreased the survival rate and hatchability rate in a concentration dependent manner compared to control. Different types of morphological abnormalities such as pericardial edema, spinal deformity, bent tail, yolk sac edema, crooked body, distorted tail deformities were reported in zebrafish larvae after 96 h of DE exposure. Heart rate was found to be significantly decreased whereas the SV-BA distance was found to be significantly elevated in DE exposed zebrafish larvae. The neurotoxicity markers i.e., sensorimotor response and spontaneous tail coiling movement, were found to be significantly decreased in DE exposed groups when compared to control group. The present investigation will help to understand the detrimental effects of DE in the early life stage of zebrafish.