Dinitroaniline herbicide pendimethalin affects development and induces biochemical and histological alterations in zebrafish early-life stages.

Pendimethalin (PND) is a dinitroaniline preemergent herbicide widely used to control grasses and weeds. The present study aimed to evaluate the PND potential effects on the development of zebrafish early-life stages. The research focuses first on acute toxicity, followed by the integration of toxicity results through histopathology, oxidative status, and neurotoxicity evaluation of sublethal and environmentally relevant concentrations. Zebrafish larvae exposed to PND showed mortality and developed sublethal alterations including impaired fin development, lordosis, scoliosis, blood congestion, impaired blood flow, and reduced heartbeat. PND exposure (0.5 mg/L) affects musculoskeletal development leading to delayed and reduced ossification of the vertebral centra in the developing vertebral column and disruption of muscle morphology. Herbicide exposure (0.5 mg/L and 0.05 mg/L) led also to biochemical changes of antioxidant enzymes, increasing the activity of CAT, GR, and GPx, while no effects were observed on the activity of SOD and GST in zebrafish larvae. Lastly, AChE activity, a biochemical marker of neurotoxicity, was also increased in zebrafish larvae exposed to 0.5 mg/L of PND. These results confirm the developmental toxicity of PND in zebrafish early-life stages, pointing out the potential role of oxidative stress in the onset of sublethal alterations.

Oxysterols Profile in Zebrafish Embryos Exposed to Triclocarban and Propylparaben-A Preliminary Study.

Oxysterols have long been considered as simple by-products of cholesterol metabolism, but they are now fully designed as bioactive lipids that exert their multiple effects through their binding to several receptors, representing endogenous mediators potentially involved in several metabolic diseases. There is also a growing concern that metabolic disorders may be linked with exposure to endocrine-disrupting chemicals (EDCs). To date, there are no studies aimed to link EDCs exposure to oxysterols perturbation-neither in vivo nor in vitro studies. The present research aimed to evaluate the differences in oxysterols levels following exposure to two metabolism disrupting chemicals (propylparaben (PP) and triclocarban (TCC)) in the zebrafish model using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Following exposure to PP and TCC, there were no significant changes in total and individual oxysterols compared with the control group; however, some interesting differences were noticed: 24-OH was detected only in treated zebrafish embryos, as well as the concentrations of 27-OH, which followed a different distribution, with an increase in TCC treated embryos and a reduction in zebrafish embryos exposed to PP at 24 h post-fertilization (hpf). The results of the present study prompt the hypothesis that EDCs can modulate the oxysterol profile in the zebrafish model and that these variations could be potentially involved in the toxicity mechanism of these emerging contaminants.

Developmental toxicity induced by triclosan exposure in zebrafish embryos.

OBJECTIVES: The present study aimed to investigate the acute toxicity and the developmental alterations induced by triclosan (TCS) exposure in zebrafish early-life stages using fish embryo acute toxicity tests as a methodological approach. MATERIAL AND METHODS: Zebrafish embryos were exposed to five concentrations of TCS and the four lethal alterations were daily recorded to determine the toxicological endpoints of acute toxicity. Furthermore, sublethal alterations were recorded to assess the effect of exposure concentrations on zebrafish embryo's development. RESULTS: The TCS toxicity was determined at 96 h of exposure as lethal concentration 10, lethal concentration 20, lethal concentration 50, lowest observed effects concentration, and no observed effects concentration, reported the following values: 168, 197.2, 267.8, 300, and 200 µg/L. Exposed larvae showed a delay in hatching rate and developed sublethal alterations including reduced blood flow, pericardial oedemata, reduced heartbeat, blood congestion, and craniofacial malformations. The number of zebrafish larvae developing cardiovascular alterations changed according to the tested concentrations and time of evaluation. CONCLUSION: The data confirmed the developmental toxicity of TCS on aquatic organisms and the sublethal alterations developed by zebrafish larvae, indicated its cardiotoxicity and neurotoxicity. Moreover, the developmental toxicity was strongly influenced by the concentration tested and the number of survived zebrafish developing this alteration varying according to the time of exposure.