Behavioural impairment and oxidative stress by acute exposure of zebrafish to a commercial formulation of tebuconazole

Tebuconazole is a systemic follicular fungicide known to cause diverse problems in non-target organisms namely associated to the pure active ingredient. As such, the objective of this work was to evaluate developmental changes induced by a tebuconazole commercial formulation to a non-target animal model. Zebrafish embryos at ± 2 h post-fertilization were exposed to tebuconazole wettable powder concentrations (0.05, 0.5 and 5 mg L^-1) for 96 h with developmental toxicity assessed throughout the exposure period and biochemical parameters evaluated at the end of the exposure. Behavioural assessment (spatial exploration and response to stimuli) was conducted 24 h after the end of the exposure. While no developmental and physiological alterations were observed, exposure to tebuconazole resulted in an increased generation of reactive oxidative species at the 0.05 and 0.5 mg L^-1 concentrations and a decreased GPx activity at the 0.5 mg L^-1 concentration suggesting a potential protection mechanism. There was also a change in the avoidance-escape behaviour supporting an anxiolytic effect suggesting possible alterations in the central nervous system development demanding further studies.     

Study on chemical constituents of Folium Artemisiae argyi Carbonisatum,toxicity evaluation on zebrafish and intestinal hemostasis

Folium Artemisiae argyi Carbonisatum (FAAC) is a traditional medicine widely used in clinic. It has the effect of hemostasis by warming meridians. In order to further explore the chemical composition and biological activity of FAAC, the methanol extract of FAAC was isolated and purified by open column and high- performance liquid chromatography. and the complete structure was characterized by nuclear magnetic resonance (NMR) and LREI-MS for the first time, namely rutin, quercetin and octacosanol respectively. Initially the toxic effect of methanol extract of FAAC on zebrafish was evaluated by observing the phenotypic characteristics, spontaneous twitch times, heart rate, hatching rate, the distance of SV-BA and cardiomyocyte apoptosis of zebrafish. The results showed that FAAC has embryonic development toxicity and cardiotoxicity when it was higher than 62.5 μg/mL. Meanwhile, the hemostatic effect of methanol extract of FAAC was compared with FAA (Folium Artemisia argyi) by zebrafish intestinal bleeding model originally. The results showed that the hemostatic effect of the medium and high concentration dose groups (3.0 and 30.0 μg/mL) was enhanced for both FAAC and FAA. This study provided an experimental basis for the clinical application of FAAC.     

DHF-BAHPC molecule exerts ameliorative antioxidant status and reduced cadmium-induced toxicity in zebrafish (Danio rerio) embryos

In this study, we report the antioxidant and antitoxic potential of chemically synthesized 4-oxo-2-phenyl-4H-chromene-7,8-diyl bis((1-amino-2-hydroxypropyl)carbamate) (DHF-BAHPC) compound using in vitro and in vivo assays. The DHF-BAHPC was synthesized by linking 7,8-Dihydroxyflavone (DHF) with two molecules of Fmoc-threonine and characterized by Ultraviolet-visible spectroscopy (UV–vis), Fourier-transform infrared spectroscopy (FT-IR), ¹H NMR, ¹³C NMR and Mass spectrometry (MS). In vitro, antioxidant assay results revealed that DHF-BAHPC has a dose-dependent radical scavenging potential towards DPPH, ABTS, FRAP and H₂O₂ radicals with an IC₅₀ range of 15.45, 66.27, 25.71, 4.375 μg/mL, respectively. Furthermore DHF-BAHPC treatment significantly altered cadmium (Cd) intoxicated zebrafish embryos by rescuing the developmental changes associated with severe histological and reduced the level of defensive antioxidant activities (SOD, CAT, GPx and GST). The overall results of the present study represented that DHF-BAHPC may be used as a potential drug in redox-based therapeutics.     

Gambogic acid causes fin developmental defect in zebrafish embryo partially via retinoic acid signaling

Gambogic acid (GA), the major active ingredient of gamboge, has been approved by the Chinese Food and Drug Administration for clinical trials in cancer patients due to its strong anticancer activity. However, our previous research showed that GA was teratogenic against zebrafish fin development. To explore the teratogenicity and the underlying mechanisms, zebrafish (Danio rerio) embryos were used. The morphological observations revealed that GA caused fin defects in zebrafish embryos in a concentration-dependent manner. The critical exposure time of GA to reveal teratogenicity was before 8 hpf (hours post fertilization). LC/MS/MS analysis revealed that a maximum bioconcentration of GA was occurred at 4 hpf. Q-PCR data showed that GA treatment resulted in significant inactivation of RA signaling which could be partially rescued by the exogenous supply of RA. These results indicate the potential teratogenicity of GA and provide evidence for a caution in its future clinic use.     

Screening drugs for myocardial disease in vivo with zebrafish: an expert update

Introduction: Our understanding of the complexity of cardiovascular disease pathophysiology remains very incomplete and has hampered cardiovascular drug development over recent decades. The prevalence of cardiovascular diseases and their increasing global burden call for novel strategies to address disease biology and drug discovery.

Areas covered: This review describes the recent history of cardiovascular drug discovery using in vivo phenotype-based screening in zebrafish. The rationale for the use of this model is highlighted and the initial efforts in the fields of disease modeling and high-throughput screening are illustrated. Finally, the advantages and limitations of in vivo zebrafish screening are discussed, highlighting newer approaches, such as genome editing technologies, to accelerate our understanding of disease biology and the development of precise disease models.

Expert opinion: Full understanding and faithful modeling of specific cardiovascular disease is a rate-limiting step for cardiovascular drug discovery. The resurgence of in vivo phenotype screening together with the advancement of systems biology approaches allows for the identification of lead compounds which show efficacy on integrative disease biology in the absence of validated targets. This strategy bypasses current gaps in knowledge of disease biology and paves the way for successful drug discovery and downstream molecular target identification.     

马兜铃酸对斑马鱼的耳毒性及肾毒性研究

目的探讨马兜铃酸对斑马鱼的耳毒性及肾毒性。方法①使用不同浓度的马兜铃酸处理受精后5天(5 dpf)的AB系斑马鱼,探索马兜铃酸对斑马鱼的最大非致死浓度(maximum non-lethal concentration,MNLC)。②依据MNLC选取4个浓度(MNLC、1/2MNLC、1/4MNLC及1/8MNLC)为实验组,2.5μg/ml庆大霉素为阳性对照组,溶剂组[1.0%二甲基亚砜(DMSO)]为阴性对照组,每组分别处理30尾斑马鱼。24 h后,每组取10尾斑马鱼用DASPEI染料对斑马鱼身体侧线毛细胞进行荧光染色,分析马兜铃酸对毛细胞的影响。每组剩余的20尾斑马鱼继续饲养至72 h,观察肾包膜的情况。结果①实验所用马兜铃酸浓度无法得出其MNLC,取其中未出现斑马鱼死亡的最大浓度(3.4μg/ml)为MNLC。②庆大霉素组毛细胞的损伤率为88.5%,与阴性对照组比较,差异有统计学意义(P<0.01);马兜铃酸MNLC组、1/2MNLC组、1/4MNLC组及1/8MNLC组毛细胞损伤率分别为-7.2%、6.9%、-0.4%、12.4%,与阴性对照组比较,差异均无统计学意义(P>0.05)。③继续处理斑马鱼至72 h后,马兜铃酸MNLC组斑马鱼全部死亡;1/2MNLC组10%的斑马鱼死亡,余下11.1%的斑马鱼出现严重的肾包膜水肿;1/4MNLC组、1/8MNLC组未观察到肾包膜水肿。结论本实验所用浓度的马兜铃酸对斑马鱼有肾毒性,无耳毒性。     

Perturbation of metabonome of embryo/larvae zebrafish after exposure to fipronil

The escalating demand for fipronil by the increasing insects’ resistance to synthetic pyrethroids placed a burden on aquatic vertebrates. Although awareness regarding the toxicity of fipronil to fish is arising, the integral alteration caused by fipronil remains unexplored. Here, we investigated on the development toxicity of fipronil and the metabolic physiology perturbation at 120 h post fertilization through GC–MS metabolomics on zebrafish embryo. We observed that fipronil dose-dependently induced malformations including uninflated swim bladder and bent spine. Further, the “omic” technique hit 26 differential metabolites after exposure to fipronil and five significant signaling pathways. We speculated that changes in primary bile acid synthesis pathway and the content of saturated fatty acid in the chemical-related group indicated the liver toxicity. Pathway of Aminoacyl-tRNA biosynthesis changed by fipronil may relate to the macromolecular synthesis. Concurrently, methane metabolism pathway was also identified while the role in zebrafish needs further determination. Overall, this study revealed several new signaling pathways in fipronil-treated zebrafish embryo/larval.     

Zebrafish as a novel model for non-typhoidal Salmonella pathogenesis,transmission and vaccine efficacy

Salmonella-induced gastroenteritis causes massive morbidity and mortality in both adults and children of developing countries. However, it is difficult to study the mode of infection and vaccine efficacy due to inadequacies of current animal models. For this reason, we have explored using zebrafish as an improved model for non-typhoidal Salmonella (NTS) infection, including Salmonella enterica Typhimurium, Salmonella enterica Enteritidis and Salmonella enterica Weltevreden. In this study, we found that after infection of zebrafish with NTS, severe diarrhea like symptoms were observed and NTS significantly colonized the zebrafish intestine without any manipulation of the normal intestinal microbiota of the fish. Furthermore, these strains can colonize for longer than 72 h and induce severe inflammation in the intestine, which may induce fish death. We also found that infected fish can transmit the pathogen into naïve fish. Moreover, we have established that zebrafish is an excellent model for vaccine study. Successive triple bath vaccination with heat-killed single serotype S. Typhimurium and S. Enteritidis immunogen induced protective efficacy against a high dose (10⁸ CFU/ml) of infection with these pathogens. This study provides a natural infection model for the study of NTS infection, transmission and vaccine efficacy.