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Acute toxicity, bioconcentration, elimination and antioxidant effects of fluralaner in zebrafish, Danio rerio
- Jia, Zhong-Qiang, Liu, Di, Sheng, Cheng-Wang, Casida, John E., Wang, Chen, Song, Ping-Ping, Chen, Yu-Ming, Han, Zhao-Jun, Zhao, Chun-Qing
- Environmental pollution 2017
- Danio rerio, acute toxicity, antioxidant activity, bioaccumulation, biomarkers, catalase, gene expression, glutathione peroxidase, insecticidal properties, insecticides, lethal concentration 50, messenger RNA, metabolism, nontarget organisms, pests, superoxide dismutase, transcription (genetics)
- Fluralaner is a novel isoxazoline insecticide which shows high insecticidal activity against parasitic, sanitary and agricultural pests, but there is little information about the effect of fluralaner on non-target organisms. This study reports the acute toxicity, bioconcentration, elimination and antioxidant response of fluralaner in zebrafish. All LC50 values of fluralaner to zebrafish were higher than 10 mg L−1 at 24, 48, 72 and 96 h. To study the bioconcentration and elimination, the zebrafish were exposed to sub-lethal concentrations of fluralaner (2.00 and 0.20 mg L−1) for 15 d and then held 6 d in clean water. The results showed medium BCF of fluralaner with values of 12.06 (48 h) and 21.34 (144 h) after exposure to 2.00 and 0.20 mg L−1 fluralaner, respectively. In the elimination process, a concentration of only 0.113 mg kg−1 was found in zebrafish on the 6th day after removal to clean water. After exposure in 2.00 mg L−1 fluralaner, the enzyme activities of SOD, CAT, and GST, GSH-PX, CarE and content of MDA were measured. Only CAT and CarE activities were significantly regulated and the others stayed at a stable level compared to the control group. Meanwhile, transcriptional expression of CYP1C2, CYP1D1, CYP11A were significantly down-regulated at 12 h exposed to 2.00 mg L−1 of fluralaner. Except CYP1D1, others CYPs were up-regulated at different time during exposure periods.Fluralaner and its formulated product (BRAVECTO®) are of low toxicity to zebrafish and are rapidly concentrated in zebrafish and eliminated after exposure in clean water. Antioxidant defense and metabolic systems were involved in the fluralaner-induced toxicity. Among them, the activities of CAT and CarE, and most mRNA expression level of CYPs showed fast response to the sub-lethal concentration of fluralaner, which could be used as a biomarker relevant to the toxicity.