Toxicity assessment of combined fluoroquinolone and tetracycline exposure in zebrafish (Danio rerio)

Abstract

Fluoroquinolones (FQs) and tetracyclines (TCs), the two b-diketone antibiotics (DKAs), are two frequently detected pollutants in the environment; however, little data are available on their combined toxicity to zebrafish (Danio rerio). This study reports that toxicologic effects of combined DKA (FQs-TCs) exposure on zebrafish were comparable with or slightly less than those of TCs alone, showing that TCs played a major toxicologic role in the mixtures. The effects of FQs, TCs, and DKAs on malformation rates of zebrafish were dose dependent, with EC 50 values of 481.3, 16.4, and 135.1 mg/L, respectively. According to the combined effects of DKAs on zebrafish hatching, mortality, and malformation rates, the interaction between FQs and TCs was shown to be antagonistic based on three assessment methods: Toxic Unit, Additional Index, and Mixture Toxic Index. The 1.56 mg/L TC and 9.38 mg/L DKA treatments resulted in higher zebrafish basal swimming rate compared with the control group at 120 hours postfertilization (hpf). in both light and light-to-dark photoperiod experiments. Under conditions of no obvious abnormality in cardiac development, the heart beats were decreased significantly because of DKA exposure, such as decreasing by 20% at 150 mg/L DKAs. Transmission electron microscopy observation of myocytes from DKA-exposed hearts displayed prominent interruptions and myofibrillar disorganization of the normal parallel alignment of thick and thin filaments, and partial edematous and dissolved membranes of cell nuclear tissues. At 90 mg/L DKAs, the transcriptional levels of the acta1a, myl7, and gle1b genes, related to heart development and skeletal muscle formation, were significantly changed. This is consistent with the swimming behavior and histopathologic results obtained by transmission electron microscopy. In summary, the toxicity of the combined DKAs to zebrafish was comparable with or less than that of TCs

Joint toxicity of fluoroquinolone and tetracycline antibiotics to zebrafish (<i>Danio rerio</i>) based on biochemical biomarkers and histopathological observation

“…2). The previously behavioral study by our group revealed that DKAs reduced the swimming activity and induced equilibrium loss in larvae (Zhang et al, 2016). Another sensitive endpoint was the abnormal yolk sac resorption in conjunction with prominent oedemas.…”

Immunotoxicity of β-Diketone Antibiotic Mixtures to Zebrafish (Danio rerio) by Transcriptome Analysis

“…Water was dechlorinated and filtered by reverse osmosis (pH 6.5–7.5), and Instant Ocean band of salt was added to raise the specific conductivity to 450–1000 μS/cm. Zebrafish were fed twice daily with live Artemia (Jiahong Feed Co., Tianjin, China) and dry flake diet (Zeigler, Aquatic Habitats, Apopka FL, USA) [ 10 ]. The fertilized and normal embryos were inspected and staged for subsequent experiments under a stereomicroscope according to Kimmel and coworker’s method [ 16 ].…”

“…Previous studies have primarily focused on the toxicity of single DKA species to explore the relevant toxicological mechanisms. However, in real-world aquatic environments, mixtures of several different DKA species may have entirely different toxicological mechanisms, which can lead to complex, combined toxicity actions by DKAs mixtures [ 9 – 10 ]. For in vivo experiments, changes in metabolic transformation and distribution of DKAs make the toxicological research more complicated [ 11 – 12 ].…”

Melanogenic Inhibition and Toxicity Assessment of Flavokawain A and B on B16/F10 Melanoma Cells and Zebrafish (Danio rerio)

“…The number of zebrafish embryo's tail coiling was counted within 1 min period. Cardiac toxicity was evaluated by measuring heart rates of zebrafish embryos in natural lateral recumbent position within 1 min period without anesthesia to avoid bias heartbeat scoring [73,74]. Zebrafish larvae were not fed during the experiment.…”