Rutin hydrate relieves neuroinflammation in zebrafish models: Involvement of NF-κB pathway as a central network.

Neuroinflammation is prevalent in multiple brain diseases and may also lead to dementia, cognitive impairment, and impaired spatial memory function associated with neurodegenerative diseases. A neuroprotective and antioxidant flavonoid, rutin hydrate (RH), was evaluated for the anti-neuroinflammatory activity mediated by copper sulfate (CuSO4) solution and lipopolysaccharide (LPS) in zebrafish. The results showed that 100 mg/L RH significantly reduced the ratio of neutrophil mobility in caudal hematopoietic tissue (CHT) region caused by CuSO4 and the number of neutrophils co-localized with facial peripheral nerves. In the LPS model, RH co-injection significantly diminished neutrophil and macrophage migration. Therefore, RH exhibited a significant rescue effect on both models. In addition, RH treatment remarkably reduced the effects of neuroinflammation on the locomotor ability, expression levels of genes associated with behavioral disorders, and acetylcholinesterase (AChE) activity. Furthermore, network pharmacology techniques were employed to investigate the potential mechanisms, and the associated genes and enzyme activities were validated in order to elucidate the underlying mechanisms. Network pharmacological analysis and zebrafish model indicated that RH regulated the expressions of NF-κB pathway-related targets (Toll-like receptor 9 (tlr9), nuclear factor kappa B subunit 1 (nfkb1), RELA proto-oncogene (RelA), nitric oxide synthase 2a, inducible (nos2a), tumour necrosis factor alpha-like (tnfα), interleukin 6 (il6), interleukin 1ß (il1ß), chemokine 8 (cxcl8), and macrophage migration inhibitory factor (mif)) as well as six key factors (arachidonic acid 4 alpha-lipoxygenase (alox4a), arachidonate 5-lipoxygenase a (alox5), prion protein a (prnpa), integrin, beta 2 (itgb2), catalase (CAT), and alkaline phosphatase (ALP) enzymes). Through this study, a thorough understanding of the mechanism underlying the therapeutic effects of RH in neuroinflammation has been achieved, thereby establishing a solid foundation for further research on the potential therapeutic applications of RH in neuroinflammatory disorders.

Oxidative stress contributes to flumioxazin-induced cardiotoxicity in zebrafish embryos.

Flumioxazin is a widely applied herbicide for the control of broadleaf weeds, including aquatic plants. Current evidence suggests that flumioxazin could induce cardiac defects (ventricular septal defects) in vertebrates, but the underlining mechanisms remain unclear. Because of the inhibitory effect of flumioxazin on polyphenol oxidase, the assumption is made that flumioxazin-induced cardiotoxicity is caused by oxidative stress. To verify whether oxidative stress plays an important role in flumioxazin-induced cardiotoxicity, we compared the differences in heart phenotype, oxidative stress level, apoptosis, and gene expression between flumioxazin exposure and a normal environment, and we also tested whether cardiotoxicity could be rescued with astaxanthin. The results showed that flumioxazin induced both cardiac malformations and the abnormal gene expression associated with cardiac development. Cardiac malformations included pericardial edema, cardiac linearization, elongated heart, cardiomegaly, cardiac wall hypocellularity, myocardial cell atrophy with a granular appearance, and a significant gap between the myocardial intima and the adventitia. An increase in oxidative stress and apoptosis was observed in the cardiac region of zebrafish after exposure to flumioxazin. The antioxidant astaxanthin reversed the cardiac malformations, excessive production of reactive oxygen species (ROS), and expression of genes for cardiac developmental and apoptosis regulation induced by flumioxazin. In addition, flumioxazin also activated aryl hydrocarbon receptor (AhR) signaling pathway genes (aryl hydrocarbon receptor 2 [ahr2], cytochrome p450 family subfamily a [cyp1a1], and b [cyp1b1]) and increased the concentration of porphyrins. The results suggest that excessive ROS production, which could be mediated through AhR, led to apoptosis, contributing to the cardiotoxicity of flumioxazin in zebrafish embryos. Environ Toxicol Chem 2023;42:2737-2746. © 2023 SETAC.

Immunotoxicity and transcriptome analysis of zebrafish embryos exposure to Nitazoxanide.

Nitazoxanide (NTZ) is a broad-spectrum immunomodulatory drug, and little information is about the immunotoxicity of aquatic organisms induced by NTZ. In the present study, reduced body length and decreased yolk sac absorption in the NTZ-treated group were observed. Meanwhile, the number of innate immune cells and adaptive immune cells was substantially reduced upon NTZ exposure, and the migration and retention of macrophages and neutrophils in the injured area were inhibited. Following NTZ stimulation, oxidative stress levels in the zebrafish increased obviously. Mechanistically, RNA-seq, a high-throughput method, was performed to analyze the global expression of differentially expressed genes (DEGs) in zebrafish embryos treated with NTZ. 531 DEGs were identified by comparative transcriptome analysis, including 121 up-regulated and 420 down-regulated genes in zebrafish embryos after NTZ exposure. The transcriptome sequences were further subjected to the Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene ontology (GO) and analysis, showing phototransduction and metabolic pathway, respectively, and were most enriched. In addition, some immune-related genes were inhibited after NTZ exposure. RNA-seq results confirmed by qRT-PCR were used to verify the expression of the 6 selected genes. The other immune-related genes such as two pro-inflammatory cytokines (IL-1ß, tnfα) and two chemokines (CXCL8b.3, CXCL-c1c) were further confirmed and were differentially regulated after NTZ exposure. In summary, NTZ exposure could lead to immunotoxicity and increased ROS in zebrafish embryos, this study provides valuable information for future elucidating the molecular mechanism of exogenous stimuli-induced immunotoxicity in aquatic ecosystems.

Enhancing electro-reduction of nitrite to ammonia by loading Co3O4 on CuO to construct elecrocatalytic dual-sites.

Improving the performance of CuO in electrocatalytic nitrite reduction to ammonia (NIRA) is the priority for designing efficient NIRA electrocatalysts. The electrocatalytic activity of CuO was enhanced by growing Co3O4 nanospheres on it. By comparing Co3O4@CuO with the mechanically mixed CuO and Co3O4 on a rotating ring-disk electrode, we discovered that the enhancement was attributed to a dual-site catalytic pathway.

Effects of haloxyfop-p-methyl on the developmental toxicity, neurotoxicity, and immunotoxicity in zebrafish.

Pesticides are extensively used in agricultural production, and their residues in soil, water, and agricultural products have become a threat to aquatic ecosystem. In this study, the toxicity of haloxyfop-p-methyl, an aryloxyphenoxypropionate herbicide was studied using the model animal zebrafish. The development of zebrafish larvae was affected by haloxyfop-p-methyl including spinal deformities, decreased body length, slow heart rate, and large yolk sac area. Behavior analysis revealed that behavior activity of larvae was weakened significantly including shortened displacement distance, reduced swimming speed, increased angular speed winding degrees, in accordance with higher AChE activity. Besides, exposure to haloxyfop-p-methyl could induce oxidative stress companied by the increased intents of ROS, MDA and increased activities of CAT and SOD. In immunotoxicity, haloxyfop-p-methyl not only reduced the innate immune cells such as neutrophils and macrophages, but also affected T cells mature in thymus. Furthermore, haloxyfop-p-methyl could induce neutrophils apoptosis, accompanied with the upregulation of the expression of proapoptotic protein such as Bax and P53 and the downregulation of the expression of antiapoptotic protein Bcl-2. In addition, haloxyfop-p-methyl could induce the expression of Jak, STAT and proinflammatory cytokine genes (IFN-γ, TNF-α, and IL-8). These results indicate that haloxyfop-p-methyl induces developmental toxicity, neurotoxicity, and immunotoxicity in zebrafish, providing a perspective on the toxicological mechanism of haloxyfop-p-methyl in teleosts.

Thiophanate-methyl induces notochord toxicity by activating the PI3K-mTOR pathway in zebrafish (Danio rerio) embryos.

Thiophanate-methyl (TM), a typical pesticide widely used worldwide, was detected in rivers, soil, fruits, and vegetables. Thus, it is urgent to identify the potential harm of TM residual to non-target organisms and its molecular mechanisms. We used zebrafish (Danio rerio) in this study to evaluate TM toxicity. TM exposure induced developmental toxicity, including inhibited hatchability, reduced heart rates, restrained spontaneous locomotion, and decreased body length. Furthermore, we observed obvious toxicity in the notochord and detected increased expression levels of notochord-related genes (shha, col2a, and tbxta) by in situ hybridization in zebrafish larvae. In addition, calcein staining, alkaline phosphatase (ALP) activity analysis, and anatomic analysis indicated that TM induced notochord toxicity. We used rescue experiments to verify whether the PI3K-mTOR pathway involved in the notochord development was the cause of notochord abnormalities. Rapamycin and LY294002 (an inhibitor of PI3K) relieve notochord toxicity caused by TM, including morphological abnormalities. In summary, TM might induce notochord toxicity by activating the PI3K-mTOR pathway in zebrafish.

Molecular manipulations of miR398 increase rice grain yield under different conditions.

Rice miR398 targets two stress-tolerant genes, CSD1-2 (Cu/Zn Superoxide Dismutases1-2) and CCS (copper chaperone of CSD), which usually boost plants' tolerance by inhibiting growth. So, how to accurately regulate the activities of miR398 targets and thus make rice better able to adapt to different conditions has great significances in producing rice yields under the current circumstances of shrinking arable lands resulting from global urbanization and increasing salty soil caused by irrigation. Through controlling the expressions of miR398 in different levels, we found down-regulated expression of miR398 targets can promote growth under good growth conditions while up-regulated expressions of the targets can help rice tolerate salt. In this study, we over-expressed miR398 highly, moderately, and lowly, then three concomitantly inverse levels of its targets' expression were obtained. Under normal growth conditions, the transgenic lines with low and moderate levels of over-expressions of miR398 could increase grain yields 14.5% and 7.3%, respectively, although no transgenic lines could survive well under salty conditions simulating real saline-alkali soil. Using short tandem target mimic (STTM) technology to silence miR398 highly, moderately, and lowly respectively, also three inverse levels of its targets' expression were obtained. All three transgenic lines exhibited good agronomic performances under salt stress in inverse to their degrees of STTM, but their growth was inhibited differently under normal conditions. Altogether, we suggest that flexibly manipulating the expression of miR398 is an ideal strategy to help rice survive better and achieve optimized yields under specific conditions.

Exploring Quercetin Anti-Osteoporosis Pharmacological Mechanisms with In Silico and In Vivo Models.

Since osteoporosis critically influences the lives of patients with a high incidence, effective therapeutic treatments are important. Quercetin has been well recognized as a bone-sparing agent and thus the underlying mechanisms warrant further investigation. In the current study, the network pharmacology strategy and zebrafish model were utilized to explain the potential pharmacological effects of quercetin on osteoporosis. The potential targets and related signaling pathways were explored through overlapping target prediction, protein-protein interaction network construction, and functional enrichment analysis. Furthermore, we performed docking studies to verify the specific interactions between quercetin and crucial targets. Consequently, 55 targets were related to osteoporosis disease among the 159 targets of quercetin obtained by three database sources. Thirty hub targets were filtered through the cytoNCA plugin. Additionally, the Gene Ontology functions in the top 10 respective biological processes, molecular functions, and cell components as well as the top 20 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were depicted. The most significance difference in the KEGG pathways was the TNF signaling pathway, consisting of the Nuclear Factor Kappa B Subunit (NF-κB), Extracellular Regulated Protein Kinases (ERK) 1/2, Activator Protein 1 (AP-1), Interleukin 6 (IL6), Transcription factor AP-1 (Jun), and Phosphatidylinositol 3 Kinase (PI3K), which were probably involved in the pharmacological effects. Moreover, molecular docking studies revealed that the top three entries were Interleukin 1 Beta (IL1B), the Nuclear Factor NF-Kappa-B p65 Subunit (RelA), and the Nuclear Factor Kappa B Subunit 1 (NFKB1), respectively. Finally, these results were verified by alizarin red-stained mineralized bone in zebrafish and related qPCR experiments. The findings probably facilitate the mechanism elucidation related to quercetin anti-osteoporosis action.

Effects of chlorobromoisocyanuric acid on embryonic development and immunotoxicity of zebrafish.

Although chlorobromoisocyanuric acid has been widely used in agriculture, its deleterious toxicity on aquatic organisms remains rare. In this study, zebrafish were exposed to chlorobromoisocyanuric acid (0, 30, 40, and 50 mg/L) from 10 to 96 h post-fertilization (hpf). We found a significant reduction in immune cell numbers (neutrophils and macrophages) and the area of thymus at 96 hpf. The expression of immune-related genes and pro-inflammatory cytokines genes were upregulated. Besides, chlorobromoisocyanuric acid triggered neutrophils cell apoptosis. The mRNA and protein levels of pro-apoptotic p53 pathway and the Bax/Bcl-2 ratio further indicated the underlying mechanism. Furthermore, the oxidative stress was observed that the accumulation of reactive oxygen species and malondialdehyde significantly increased. Subsequently, the antioxidant agent astaxanthin significantly attenuated the level of oxidative stress and the dysregulation of inflammatory response. In summary, our results showed that chlorobromoisocyanuric acid induced developmental defects and immunotoxicity of zebrafish, partly owing to oxidative stress and cell apoptosis.

Benoxacor caused developmental and cardiac toxicity in zebrafish larvae.

Benoxacor (BN) is a highly effective antidote of dichloroacetamide herbicides generally used to protect crops from herbicidal damage. As a commonly used agrochemical, this herbicide antidote is continuously discharged in watercourses thus causing toxicity to aquatic organisms, and ultimately leading to contamination of the food chain. To date, its potential toxicity to the cardiac development of aquatic organisms has not been evaluated. In the present study, we have selected the zebrafish as a model to study the impact of BN on embryonic developmental and cardiac toxicity. The zebrafish embryos were exposed in 0.5, 1.0 and 2.0 mg/L BN from 5.5 to 72 h post-fertilization (hpf). The results indicated that the exposure to BN led to increased mortality and diminished heart and hatching rates in the embryos. BN exposure also brought pericardial edema (PE) and linear stretching of heart. Besides, exposure to BN induced an excessive accumulation of reactive oxygen species (ROS) in the zebrafish embryos and abnormal activities of the antioxidant enzymes, including catalase (CAT) and malondialdehyde (MDA). Moreover, exposure to BN caused serious cardiac toxicity of the embryos, accompanied by abnormality of heart development- and apoptosis-related genes. Surprisingly, astaxanthin (ASTA), as a common antioxidant, was found to be able to partially rescue the cardiac toxicity caused by BN, which indicated that ROS are probably the major reason for the resulting cardiotoxicity in zebrafish embryos. Our results suggest the need for a comprehensive safety evaluation of the regular consumption of benoxacor, which provides scientific basis for the development of health standards and assessment of potential risk in aquatic organisms or even human.

Cardiac toxicity assessment of pendimethalin in zebrafish embryos.

Pendimethalin (PND) is one of the best sellers of selective herbicide in the world and has been frequently detected in the water. However, little is known about its effects on cardiac development. In this study, we used zebrafish to investigate the developmental and cardiac toxicity of PND. We exposed the zebrafish embryos with a serial of concentrations at 3, 4, and 5 mg/L at 5.5-72 h post-fertilization (hpf). We found that PND exposure can reduce the heart rate, survival rate, and body length of zebrafish embryos. Furthermore, we identified many malformations including pericardial and yolk sac edema, spinal deformity, and cardiac looping abnormality. In addition, PND increased the expression of reactive oxygen species and malondialdehyde and reduced the activity of superoxide dismutase (Antioxidant enzymes); We examined the expression of cardiac development-related genes and the apoptosis markers, and found changes of the following marker: vmhc, nppa, tbx5a, nkx2.5, gata4, tbx2b and FoxO1, bax, bcl-2, p53, casp-9, casp-3. Our data showed that activation of Wnt pathway can rescue the cardiac abnormalities caused by PND. Our results provided new evidence for the toxicity of PND and suggested that the PND residual should be treated as a hazard in the environment.

Toxicity of thioacetamide and protective effects of quercetin in zebrafish (Danio rerio) larvae.

Quercetin is a flavonoid compound with a variety of biological properties that is widely distributed throughout the plant kingdom. Studies have found that quercetin has anti-inflammatory, antioxidant, and liver-protective effects, while thioacetamide (TAA) can cause inflammation and liver damage in zebrafish larvae. The purpose of this study was to evaluate whether quercetin can prevent TAA-induced inflammation and liver damage in zebrafish larvae and to investigate the molecular mechanisms involved. Zebrafish Tg transgenic lines were used as the experimental animals. Behavioral, oxidative stress level, proliferative antigen chromogenic antibody, and western blot analyses were carried out on zebrafish larvae in the control group and groups treated with TAA and 12 µM quercetin. The results indicated that quercetin promoted the development of zebrafish larvae damaged by TAA, exhibited antioxidant and anti-inflammatory properties, and promoted cell proliferation. Quercetin reduced the expression of p53 protein in zebrafish larvae injured by TAA, resulting in decreased levels of Bax and increased levels of Bcl-2. The findings suggested quercetin has antiapoptotic action. Quercetin reduced the expression of DKK1 and DKK2 genes related to the Wnt signaling pathway in zebrafish larvae damaged by TAA and increased the expression of Lef1 and wnt2bb. Quercetin may regulate the development of zebrafish larvae damaged by TAA through the Wnt signaling pathway. This study provides the scientific basis for the development and utilization of quercetin and the development of new related drugs.

Holography-based structured light illumination for temporal focusing microscopy.

In this Letter, we present a holography-based structured light illumination (SLI) method to enhance the resolution of widefield temporal focusing microscopy (TFM). In the system, a digital micromirror device is employed to simultaneously disperse the incoming femtosecond laser to induce temporal focusing at the focal plane and generate designed structured patterns via a Lee hologram. As the generated structured patterns do not contain the zeroth order beam, it improves the contrast and modulation frequency. Mathematical models have been derived to calculate the electric fields at the focal plane and to explain the effects of improved optical cross-sectioning capability. Imaging experiments have been devised and performed on fluorescent beads and mouse kidney sections; the results demonstrate enhanced axial confinement and improved suppression of out-of-focus fluorescence. The new SLI method realizes high-resolution TFM and can be readily applied to other microscopy platforms for biophotonics applications.

Effects of sulfometuron-methyl on zebrafish at early developmental stages.

Sulfometuron methyl (SM) is a widely used herbicide and thus leading to accumulation in the environment. The toxicity assessments of SM in model organisms are currently rare. In the present study, zebrafish were utilized for evaluating the detrimental effects of SM in aquatic vertebrates. Zebrafish embryos were exposed to 0, 10, 20, and 40 mg/L SM from 5.5 to 72 h post-fertilization (hpf), respectively. Consequently, SM exposure resulted in increasing the mortality rate and reducing hatching rate in larval zebrafish at 10, 20, and 40 mg/L SM-treated groups. The reduced numbers of immune cells (neutrophils and macrophages) were observed after SM exposure by a dose-dependent manner. The inflammatory responses (TLR4, MYD88, IL-1ß, IL-6, IL-8, IFN-γ, IL-10, and TGF-ß) were measured to estimate immune responses. Anti-inflammatory factors (IL-10 and TGF-ß) were down-regulated in all the treated groups and significantly altered at 40 mg/L exposure group. Additionally, behavioral tests suggested that SM treatment significantly increased the total distance, average speed, and maximum acceleration of larval zebrafish during light-dark transition and subsequently enzymology test displayed the same trend to locomotor behaviors. The content significantly increased in oxidative stress, as reflected in ROS level in all the treated groups. The numbers of cell apoptosis were significantly increased at 20, and 40 mg/L and the highest concentration group induced the substantial increment (P < 0.001) of apoptosis-related genes including p53, Bax/Bcl-2, caspase-9, and caspase-3. In summary, our results demonstrated that exposure to SM caused toxicity of development, immune system, locomotor behavior, oxidative stress, and cell apoptosis at the early developmental stages of zebrafish.

Effect of flupyradifurone on zebrafish embryonic development.

Evaluation of the toxicity of pesticide residues on non-target organisms in the ecosystem is an important part of pesticide environmental risk assessment. Flupyradifurone is a new type of butenolide insecticide produced by Bayer, who claims it to be "low toxic" to non-target organisms in the environment. However, there is little evidence in the literature to show how flupyradifurone affects aquatic organism development. In the current study, zebrafish embryos were treated with 0.1, 0.15, and 0.2 mg/mL of flupyradifurone within 6.0-72 h past fertilization (hpf). We found that the half-lethal concentration (LC50) of flupyradifurone for zebrafish embryos at 96 hpf was 0.21 mg/mL. Flupyradifurone decreases the heart rate, survival rate, and body length of zebrafish embryos. The flupyradifurone treatment also led to the failure of heart looping, and pericardial edema. Moreover, flupyradifurone increased the level of reactive oxygen species (ROS) and decreased the enzymatic catalysis of catalase (CAT) and superoxide dismutase (SOD). Alterations were induced in the transcription of apoptosis-related genes (bcl-2, bax, bax/bcl-2, p53 and caspase-9) and the heart development-related genes (gata4, myh6, nkx2.5, nppa, tbx2b, tbx5 and vmhc). In the current study, new evidences have been provided regarding the toxic effects of flupyradifurone and the risk of its residues in agricultural products and the environment.

Pyridaben induced cardiotoxicity during the looping stages of zebrafish (Danio rerio) embryos.

Pyridaben is a widely used acaricide in agriculture and reaches a high concentration (97 µg/L) in paddy water for a short time when pyridaben was applied to rice. However, its toxicity to aquatic organisms is still poorly understood. Therefore, we assessed the pyridaben cardiotoxicity to aquatic organisms using the zebrafish (Danio rerio) model. We found that pyridaben is highly toxic to aquatic organisms, and LC50 of pyridaben for zebrafish at 72 hpf was 100.6 µg/L. Pyridaben caused severe cardiac malformations and functional abnormalities. Morphologic abnormity included severe pericardial edema, cardiomegaly, decreased cardiomyocytes, thinning of the myocardial layer, linear heart, and increased the distance between sinus venous and bulbus arteriosus (SV-BA). Functional failure included arrhythmia, heart failure, and reduced pumping efficiency. The genes involved in heart development, WNT signaling, BMP signaling, ATPase, and cardiac troponin C were abnormally expressed in the pyridaben treatment group. Exposure to pyridaben increased oxidative stress and induced cell apoptosis. The above causes may lead to cardiac toxicity. The results suggest that pyridaben exposure induced elevated oxidative stress through the WNT signaling pathway, which in turn led to apoptosis in the heart and cardiotoxicity. Besides, pyridaben exposure at the critical stage of cardiac looping (24-36 hpf) resulted in the greatest cardiotoxicity. The chorion reduced the entry of pyridaben and protected zebrafish embryos, resulting in cardiotoxicity second only to the stage of cardiac looping. The study should provide valuable information that pyridaben exposure causes cardiotoxicity in zebrafish embryos and have potential health risks for other aquatic organisms and humans.

Calcineurin controls proximodistal blastema polarity in zebrafish fin regeneration.

Planarian flatworms regenerate their heads and tails from anterior or posterior wounds and this regenerative blastema polarity is controlled by Wnt/ß-catenin signaling. It is well known that a regeneration blastema of appendages of vertebrates such as fish and amphibians grows distally. However, it remains unclear whether a regeneration blastema in vertebrate appendages can grow proximally. Here, we show that a regeneration blastema in zebrafish fins can grow proximally along the proximodistal axis by calcineurin inhibition. We used fin excavation in adult zebrafish to observe unidirectional regeneration from the anterior cut edge (ACE) to the posterior cut edge (PCE) of the cavity and this unidirectional regeneration polarity occurs as the PCE fails to build blastemas. Furthermore, we found that calcineurin activities in the ACE were greater than in the PCE. Calcineurin inhibition induced PCE blastemas, and calcineurin hyperactivation suppressed fin regeneration. Collectively, these findings identify calcineurin as a molecular switch to specify the PCE blastema of the proximodistal axis and regeneration polarity in zebrafish fin.

Development toxicity and cardiotoxicity in zebrafish from exposure to iprodione.

Iprodione is a highly effective broad-spectrum fungicide commonly used for early disease control in fruit trees and vegetables. Pesticides often flow into watercourses due to rainfall, causing toxicity in non-target organisms, eventually entering the food chain. However, little information is available in the current literature about the toxicity of iprodione to cardiac development. The present study aimed to investigate the effect of iprodione on early embryonic development and its cardiotoxicity in aquatic animals, using zebrafish as a model. At 6-72 h post-fertilization (hpf), zebrafish were exposed to concentrations of 15 mg/L, 20 mg/L, and 25 mg/L (72 h-LC50 = 21.15 mg/L). We found that exposure to iprodione resulted in yolk edema, increased mortality, and shortened body length in zebrafish embryos. In addition, iprodione was also found to induce edema in the pericardium of zebrafish, decrease heart rate, and cause the failure of cardiac cyclization. Exposure to iprodione significantly increased the accumulation of ROS and altered the activity of antioxidant enzymes (MDA, CAT) in zebrafish embryos. Moreover, iprodione induced changes in the transcription levels of heart developmental-related genes and apoptosis-related genes. In addition, Astaxanthin (antioxidant) can partially rescue the toxic phenotype caused by iprodione. Apoptosis-related genes and heart developmental-related genes were rescued after astaxanazin treatment. The results suggest that iprodione induces developmental and cardiac toxicity in zebrafish embryos, which provides new evidence of the toxicity of iprodione to organisms in aquatic ecosystems and assessing human health risks.

Famoxadone-cymoxanil induced cardiotoxicity in zebrafish embryos.

Famoxadone-cymoxanil is a new protective and therapeutic fungicide, but little research has been done on it or its toxicity in aquatic organisms. In this study, we used zebrafish to investigate the cardiotoxicity of famoxadone-cymoxanil and the potential mechanisms involved. Zebrafish embryos were exposed to different concentrations of famoxadone-cymoxanil until 72 h post-fertilization (hpf), then changes of heart morphology in zebrafish embryos were observed. We also detected the levels of oxidative stress, myocardial-cell proliferation and apoptosis, ATPase activity, and the expression of genes related to the cardiac development and calcium-signaling pathway. After famoxadone-cymoxanil exposure, pericardial edema, cardiac linearization, and reductions in the heart rate and cardiac output positively correlated with concentration. Although myocardial-cell apoptosis was not detected, proliferation of the cells was severely reduced and ATPase activity significantly decreased, resulting in a severe deficiency in heart function. In addition, indicators of oxidative stress changed significantly after exposure of the embryos to the fungicide. To better understand the possible molecular mechanisms of cardiovascular toxicity in zebrafish, we studied the transcriptional levels of cardiac development, calcium-signaling pathways, and genes associated with myocardial contractility. The mRNA expression levels of key genes in heart development were significantly down-regulated, while the expression of genes related to the calcium-signaling pathway (ATPase [atp2a1], cardiac troponin C [tnnc1a], and calcium channel [cacna1a]) was significantly inhibited. Expression of klf2a, a major endocardial flow-responsive gene, was also significantly inhibited. Mechanistically, famoxadone-cymoxanil toxicity might be due to the downregulation of genes associated with the calcium-signaling pathway and cardiac muscle contraction. Our results found that famoxadone-cymoxanil exposure causes cardiac developmental toxicity and severe energy deficiency in zebrafish.

Effect of fomesafen on the embryonic development of zebrafish.

Fomesafen is widely used in agriculture and can be detected in the environment and agricultural products. Research on the developmental toxicity of fomesafen in animals is currently very limited. Here, we used zebrafish as an animal model to evaluate the toxicity of fomesafen in developing aquatic vertebrates and higher animals. From 6h to 72h following fertilization, exposure of zebrafish embryos to 5, 10 and 20 mg/L of fomesafen resulted in pericardial edema, a reduction in heart rate, shortening of body length, and yolk sac edema. Fomesafen reduced the number of immune cells such as neutrophils and macrophages, increased the expression of a number of inflammatory factors, induced the up-regulation of the oxidative stress response and apoptosis, and disrupted the activity of enzymes related to nerve development, which affected the motility of the embryos. In conclusion, the results provide new evidence for the comprehensive assessment of fomesafen toxicity in aquatic vertebrates.