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Studying Neurobehavioral Effects of Environmental Pollutants on Zebrafish Larvae

Recent years more and more environmental pollutants have been proved neurotoxic, especially at the early development stages of organisms. Zebrafish larvae ...

Tongji University

Two metabolites, OH-BDEs and MeO-BDEs, of polybrominated diphenyl ethers (PBDEs) were ubiquitously detected in animal tissues and environmental samples, drawing a widely public concern to their toxicity. The comparison of toxicity between PBDEs and their metabolites has been a focus in recent years, however, comparisons seldom involve neurobehavioral toxicity of PBDEs metabolites in published works. In this study, zebrafish larvae were exposed to 6-OH-BDE-47 and 6-MeO-BDE-47 and their neurobehavioral traits (including locomotion, path angle, and social activity) were recorded using the instrument Zebrabox; meanwhile, light illumination was used as stimuli in the test duration. The results showed larvae were more active in dark periods than light periods, and preferred turning right (+) to left (-). Effects of the two metabolites varied in different behavioral indicators. They induced different effects on path angle but did not reverse the left-right asymmetry. 6-OH-BDE-47 did not induce the effects on larval locomotion and social activity, but mainly decreased average and routine turn numbers; 6-MeO-BDE-47 promoted larvae responsive turns but inhibited social activity. This study offered new experimental means to the neurobehavioral toxicity of various PBDE metabolites. Further studies may focus on the toxic mechanisms of specific neurobehavioral traits.

Neurobehavioral effects of two metabolites of BDE-47 (6-OH-BDE-47 and 6-MeO-BDE-47) on zebrafish larvae.

Disinfection byproducts (DBPs) are inevitably generated during drinking water disinfection processes, and their hazards have not been well characterized. Because they plausibly cause toxicological and pathological damage to human kidney, we selected the human embryonic kidney (HEK293) cell, instead of the commonly used CHO cell, as a model to investigate the toxic potential and target of 10 DBPs, including 3 haloacetamides, 2 trihaloacetaldehydes and 5 iodomethanes. Based on the chronic toxicity parameter EC of the cell viability test, we obtained a toxic rank of the tested DBPs different from previous studies and calculated their risk quotients by combining their actual concentrations in drinking water systems. Then, dichloroacetamide (DCAM), trichloroacetaldehyde (TCAL), and bromochloroiodomethane (BCIM) were selected to conduct multiple mechanistic bioassays, including cellular lactate dehydrogenase (LDH) assay, ATP metabolism, ROS production, mitochondria-derived apoptosis and qRT-PCR assay. All bioassays revealed the effects of interrupting the molecular, physiological and biochemical processes relevant to mitochondrial functions, such as oxidative respiration, apoptosis, and energy metabolism. Our study improved the human risk assessment of DBPs with the help of a convenient model and parameter and revealed that mitochondrion is a potential toxic focus of DBPs exposure at the cellular level.

Xinyue Yang

Key Laboratory of Yangtze River Water Environment,
Ministry of Education,
College of Environmental Science and Engineering,
Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering

Tongji University

Studying Neurobehavioral Effects of Environmental Pollutants on Zebrafish Larvae