Mitochondrial dysfunction, apoptosis and transcriptomic alterations induced by four strobilurins in zebrafish (Danio rerio) early life stages

Network analysis of toxic endpoints of fungicides in zebrafish

Zebrafish being the best animal model to study, every attempt has been made to decipher the toxic mechanism of every fungicide of usage and interest. It is important to understand the multiple targets of a toxicant to estimate the toxic potential in its totality. A total of 22 fungicides of different classes like amisulbrom, azoxystrobin, carbendazim, carboxin, chlorothalonil, difenoconazole, etridiazole, flusilazole, fluxapyroxad, hexaconazole, kresoxim methyl, mancozeb, myclobutanil, prochloraz, propiconazole, propineb, pyraclostrobin, tebuconazole, thiophanate-methyl, thiram, trifloxystrobin and ziram were reviewed and analyzed for their multiple explored targets in zebrafish. Toxic end points in zebrafish are highly informative when it comes to network analysis. They provide a window into the molecular and cellular pathways that are affected by a certain toxin. This can then be used to gain insights into the underlying mechanisms of toxicity and to draw conclusions on the potential of a particular compound to induce toxicity. This knowledge can then be used to inform decisions about drug development, environmental regulation, and other areas of research. In addition, the use of zebrafish toxic end points can also be used to better understand the effects of environmental pollutants on ecosystems. By understanding the pathways affected by a given toxin, researchers can determine how pollutants may interact with the environment and how this could lead to health or environmental impacts.

Effect of short-term exposure to the strobilurin fungicide dimoxystrobin: Morphofunctional, behavioural and mitochondrial alterations in Danio rerio embryos and larvae

Strobilurins, among the most used fungicides worldwide, are considered non-toxic to mammals and birds, but there is growing evidence that these compounds are highly toxic to aquatic species. Dimoxystrobin has been included in the 3rd Watch List of the European Commission, and it has been classified as very toxic to aquatic life. However, previous studies focused on acute toxicity and only two reports are available on its impact on fish, and none on its effects during the early life stages. Here, we evaluated for the first time the effects induced on zebrafish embryos and larvae by two dimoxystrobin sublethal concentrations (6.56 and 13.13 μg/L) falling in the range of predicted environmental concentrations. We demonstrated that short-term exposure to dimoxystrobin may exert adverse effects on multiple targets, inducing severe morphological alterations. Moreover, we showed enhanced mRNA levels of genes related to the mitochondrial respiratory chain and ATP production. Impairment of the swim bladder inflation has also been recorded, which may be related to the observed swimming performance alterations.

Efficient and practical in-jar silicone rubber based passive sampling for simultaneous monitoring of emerging fungicides in water and soils

The occurrence and ecological impacts of emerging fungicides in the environment has gained increasing attention. This study applied an in-jar passive sampling device based on silicone rubber (SR) film to measuring the freely dissolved concentration (Cfree) of 6 current-use fungicides as a critical index of bioavailability in water and soils. The kinetics parameters including SR-water, soil-water, and organic carbon-water partition coefficients and sampling rates of the target fungicides were first attained and characterized well with their physicochemical properties. The in situ and ex situ field deployment in Hefei City provided the assessment of contaminated levels for these fungicides in rivers and soils. The Cfree of triadimefon and azoxystrobin was estimated at 0.54 ± 0.07-17.4 ± 2.5 ng L-1 in Nanfei River and Chao Lake, while triadimefon was only found in Dongpu Reservoir water with Cfree below 0.66 ± 0.04 ng L-1. The results exhibited that the equilibrium duration of 7 d was suitable for water application but a longer interval of 14 d was recommended for soil sampling. This work demonstrated the advantages of the proposed strategy in terms of fast monitoring within 2 weeks and high sensitivity down to detection limits in 0.5-5 ng L-1. The in-jar passive sampling device can be extrapolated to the evaluation for a wide coverage of organic pollutants in water and soils.

Biodegradation of the strobilurin fungicide pyraclostrobin by Burkholderia sp. Pyr-1: Characteristics, degradation pathway, water remediation, and toxicity assessment

Pyraclostrobin, a widely used fungicide, poses significant risks to both the environment and human health. However, research on the microbial degradation process of pyraclostrobin was scarce. Here, a pyraclostrobin-degrading strain, identified as Burkholderia sp. Pyr-1, was isolated from activated sludge. Pyraclostrobin was efficiently degraded by strain Pyr-1, and completely eliminated within 6 d in the presence of glucose. Additionally, pyraclostrobin degradation was significantly enhanced by the addition of divalent metal cations (Mn2+ and Cu2+). The degradation pathway involving ether bond and N-O bond cleavage was proposed by metabolite identification. The sodium alginate-immobilized strain Pyr-1 had a higher pyraclostrobin removal rate from contaminated lake water than the free cells. Moreover, the toxicity evaluation demonstrated that the metabolite 1-(4-chlorophenyl)-1H-pyrazol-3-ol significantly more effectively inhibited Chlorella ellipsoidea than pyraclostrobin, while its degradation products by strain Pyr-1 alleviated the growth inhibition of C. ellipsoidea, which confirmed that the low-toxic metabolites were generated from pyraclostrobin by strain Pyr-1. The study provides a potential strain Pyr-1 for the bioremediation in pyraclostrobin-contaminated aquatic environments.

Roxithromycin exposure induces motoneuron malformation and behavioral deficits of zebrafish by interfering with the differentiation of motor neuron progenitor cells

Roxithromycin (ROX), a commonly used macrolide antibiotic, is extensively employed in human medicine and livestock industries. Due to its structural stability and resistance to biological degradation, ROX persists as a resilient environmental contaminant, detectable in aquatic ecosystems and food products. However, our understanding of the potential health risks to humans from continuous ROX exposure remains limited. In this study, we used the zebrafish as a vertebrate model to explore the potential developmental toxicity of early ROX exposure, particularly focusing on its effects on locomotor functionality and CaP motoneuron development. Early exposure to ROX induces marked developmental toxicity in zebrafish embryos, significantly reducing hatching rates (n=100), body lengths (n=100), and increased malformation rates (n=100). The zebrafish embryos treated with a corresponding volume of DMSO (0.1%, v/v) served as vehicle controls (veh). Moreover, ROX exposure adversely affected the locomotive capacity of zebrafish embryos, and observations in transgenic zebrafish Tg(hb9:eGFP) revealed axonal loss in motor neurons, evident through reduced or irregular axonal lengths (n=80). Concurrently, abnormal apoptosis in ROX-exposed zebrafish embryos intensified alongside the upregulation of apoptosis-related genes (bax, bcl2, caspase-3a). Single-cell sequencing further disclosed substantial effects of ROX on genes involved in the differentiation of motor neuron progenitor cells (ngn1, olig2), axon development (cd82a, mbpa, plp1b, sema5a), and neuroimmunity (aplnrb, aplnra) in zebrafish larvae (n=30). Furthermore, the CaP motor neuron defects and behavioral deficits induced by ROX can be rescued by administering ngn1 agonist (n=80). In summary, ROX exposure leads to early-life abnormalities in zebrafish motor neurons and locomotor behavior by hindering the differentiation of motor neuron progenitor cells and inducing abnormal apoptosis.

Oxidative stress and DNA alteration on the earthworm Eisenia fetida exposed to four commercial pesticides

Modern agriculture is mainly based on the use of pesticides to protect crops but their efficiency is very low, in fact, most of them reach water or soil ecosystems causing pollution and health hazards to non-target organisms. Fungicide triazoles and strobilurins based are the most widely used and require a specific effort to investigate toxicological effects on non-target species. This study evaluates the toxic effects of four commercial fungicides Prosaro® (tebuconazole and prothioconazole), Amistar®Xtra (azoxystrobin and cyproconazole), Mirador® (azoxystrobin) and Icarus® (Tebuconazole) on Eisenia fetida using several biomarkers: lipid peroxidation (LPO), catalase activity (CAT), glutathione S-transferase (GST), total glutathione (GSHt), DNA fragmentation (comet assay) and lysozyme activity tested for the first time in E. fetida. The exposure to Mirador® and AmistarXtra® caused an imbalance of ROS species, leading to the inhibition of the immune system. AmistarXtra® and Prosaro®, composed of two active ingredients, induced significant DNA alteration, indicating genotoxic effects. This study broadened our knowledge of the effects of pesticide product formulations on earthworms and showed the need for improvement in the evaluation of toxicological risk deriving from the changing of physicochemical and toxicological properties that occur when a commercial formulation contains more than one active ingredient and several unknown co-formulants.

Ecological assessment of stream water polluted by phosphorus chemical plant: Physiological, biochemical, and molecular effects on zebrafish (Danio rerio) embryos

The rapid development of the phosphorus chemical industry has caused serious pollution problems in the regional eco-environment. However, understanding of their ecotoxic effects remains limited. This study aimed to investigate the developmental toxicity of a stream polluted by a phosphorus chemical plant (PCP) on zebrafish embryos. For this, zebrafish embryos were exposed to stream water (0, 25, 50, and 100% v/v) for 96 h, and developmental toxicity, oxidative stress, apoptosis, and DNA damage were assessed. Stream water-treated embryos exhibited decreased hatching rates, heart rates, and body lengths, as well as increased mortality and malformation rates. The general morphology score system indicated that the swim bladder and pigmentation were the main abnormal morphological endpoints. Stream water promoted antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD), and glutathione peroxidase (GPx)), lipid peroxidation, and DNA damage. It also triggered apoptosis in the embryos' heads, hearts, and spines by activating apoptotic enzymes (Caspase-3 and Caspase-9). Additionally, stream water influenced growth, oxidative stress, and apoptosis-related 19 gene expression. Notably, tyr, sod (Mn), and caspase9 were the most sensitive indicators of growth, oxidative stress, and apoptosis, respectively. The current trial concluded that PCP-polluted stream water exhibited significant developmental toxicity to zebrafish embryos, which was regulated by the oxidative stress-mediated activation of endogenous apoptotic signaling pathways.

Border cell population size and oxidative stress in the root apex of Triticum aestivum seedlings exposed to fungicides

Fungicides reduce the risk of mycopathologies and reduce the content of mycotoxins in commercial grain. The effect of fungicides on the structural and functional status of the root system of grain crops has not been studied enough. In this regard, we studied the phytocytotoxic effects tebuconazole (TEB) and epoxiconazole (EPO) and azoxystrobin (AZO) in the roots of Triticum aestivum seedlings in hydroponic culture. In the presence of EPO and AZO (but not TEB) inhibition of the root growth was accompanied by a dose-dependent increase in the content of malondialdehyde, carbonylated proteins, and proline in roots. TEB was characterized by a dose-dependent decrease in the total amount of border cells (BCs) and the protein content in root extracellular trap (RET). For EPO and AZO, the dose curves of changes in the total number of BCs were bell-shaped. AZO did not affect the protein content in RET. The protein content in RET significantly decreased by 3 times for an EPO concentration of 1 µg/mL. The obtained results reveal that the BC-RET system is one of the functional targets of fungicides in the root system of wheat seedlings. Studied fungicides induce oxidative stress and structural and functional alterations in the BC-RET system that can affect their toxicity to the root system of crops.

In Vitro, In Vivo, and In Silico Analysis of Pyraclostrobin and Cyprodinil and Their Mixture Reveal New Targets and Signaling Mechanisms

Pyraclostrobin and cyprodinil are broad-spectrum fungicides that are used in crops to control diseases. However, they are excessively used and, as a result, end up in the environment and threaten human health and ecosystems. Hence, knowledge of their mechanisms of action is critical to revealing their environmental fate and negative effects and regulating their use. In the present study, we conducted a comprehensive study to show the adverse effects of pyraclostrobin, cyprodinil, and their mixture using zebrafish larvae and different cell lines. Several end points were investigated, including mortality, development, gene expression, reporter assays, and molecular docking simulations. We found that both compounds and their mixture caused developmental delays and mortality in zebrafish, with a higher effect displayed by pyraclostrobin. Both compounds altered the expression of genes involved in several signaling pathways, including oxidative stress and mitochondrial function, lipid and drug metabolisms, the cell cycle, DNA damage, apoptosis, and inflammation. A noteworthy result of this study is that cyprodinil and the mixture group acted as NFκB activators, while pyraclostrobin demonstrated antagonist activity. The AHR activity was also upregulated by cyprodinil and the mixture group; however, pyraclostrobin did not show any effect. For the first time, we also demonstrated that pyraclostrobin had androgen receptor antagonist activity.

Impacts of pyraclostrobin on intestinal health and the intestinal microbiota in common carp (Cyprinus carpio L.)

Pyraclostrobin (PYR) is a strobilurin fungicide that is commonly used in agriculture, and its use in agriculture may lead to an increase in its residue in the aquatic environment and may have a deleterious influence on the intestinal health of aquatic creatures. Here, common carp were chronically exposed to PYR (0, 0.5, or 5.0 μg/L) for 30 d to determine its effect on the physical and immunological barrier and intestinal microbiota in the intestine. PYR exposure caused significant histological changes; altered the mRNA expression levels of occludin, claudin-2, and zonula occludens-1 (ZO-1); induced oxidative stress in the common carp intestine; and increased the serum D-lactate and diamine oxidase (DAO) levels. Moreover, PYR significantly increased the protein expression levels of tumour necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and IL-6 while decreasing the level of transforming growth factor beta (TGF-β). Further studies revealed that PYR significantly reduced lysozyme (LZM) and acid phosphatase (ACP) activities as well as complement 3 (C3) and immunoglobulin M (IgM) levels. Furthermore, PYR decreased gut microbial diversity while increasing the abundance of pathogenic bacteria such as Aeromonas and Shewanella, causing an intestinal microbial disturbances in common carp. These results imply that PYR has a negative impact on fish intestinal health and may pose serious health risks to fish by disrupting the intestinal microbiota, physical barrier, and immunological barrier in common carp.

Trifloxystrobin induced developmental toxicity by disturbing the ABC transporters, carbohydrate and lipid metabolism in adult zebrafish

The environmental risks of trifloxystrobin (TR) have drawn attention because of its multiplex toxicity on aquatic organisms, but few studies have paid close attention to its chronic toxicity at environmental concentrations. In present study, histopathology, metabolomics and transcriptomics were comprehensively performed to investigate the toxic effects and biological responses on adult zebrafish after exposure to 0.1, 1 and 10 μg/L TR for 21 d. Results demonstrated long-term exposure of TR affected zebrafish liver, ovary and heart development. Metabolomics revealed 0.1, 1 and 10 μg/L TR simultaneously decreased the carbohydrates enriched in glucose metabolism and ABC transporters pathways, such as glycogen, lactose, lactulose, maltose, maltotriose, d-trehalose, while 1 μg/L and 10 μg/L TR significantly increased many metabolites related to glycerophospholipid and sphingolipid metabolism in zebrafish liver. Transcriptomics showed TR activated the transcription of the Abcb4, Abcb5 and Abcb11 involved in ABC transporters, Pck1, Pfk, Hk, Gyg1a and Pygma related to glucose metabolism, as well as the Lpcat1, Lpcat4, Gpat2, Cers and Sgms in glycerophospholipid and sphingolipid metabolism. Results further demonstrated high concentration of TR strongly affected the DNA repair system, while low dose of TR caused pronounced effects on cardiomyocytes and oocyte regulation pathways at transcriptional levels. The results indicated the abnormal liver, gonad and heart development caused by TR might be ascribed to the disturbance of carbohydrates and lipid metabolism mediating by the Abcb4, Abcb5 and Abcb11 ABC transporters, and long-term exposure of environmental concentration of TR was sufficient to affect zebrafish normal metabolism and development.

A multidimensional optimization strategy of pyraclostrobin-loaded microcapsules to improve the selectivity between toxicological risk in zebrafish and efficacy in controlling rice blast

Developing microcapsules (MCs) delivery systems can effectively mitigate toxicological risk of highly active/toxic pesticides; whereas the controlled release functions also limiting their practical effectiveness. Therefore, designing a precise regulating strategy to balance the toxicity and bioactivity of MCs is urgently needed. Here, we prepared a series of pyraclostrobin-loaded MCs with different wall materials, particle sizes, core density and shell compactness using interfacial polymerization. The results showed that the MCs released more slowly in water with increasing particle sizes and capsule compactness, and they sunk more quickly with the increasing particle sizes and core density. Additionally, MCs with slower release speed was always accompanied with lower acute toxicity levels to zebrafish. When the release dynamics slowed down to the threshold dose on demand for disease control, facilitating settlement of MCs can further reduce toxicity within spatial and temporal dimensions. The poor accumulation of MCs with larger particle sizes or dense shell in gills was closely related to their efficient detoxification. Importantly, seven of the MCs samples possessed superior selectivity between bio-performance in controlling rice blast and toxicological hazard to fish compared to commercial formulations. The results provide a comprehensive guidance for developing an efficient and safe pesticide delivery system.

Uptake, Translocation, and Subcellular Distribution of Strobilurin Fungicides in Cucumber (Cucumis sativa L.)

The absorption, transport, and subcellular distribution of strobilurin fungicides (azoxystrobin, pyraclostrobin, and trifloxystrobin) have been studied in cucumbers. Under hydroponic laboratory conditions, pyraclostrobin and trifloxystrobin mainly accumulated in cucumber roots whereas azoxystrobin accumulated in cucumber leaves. In the subcellular distribution experiment, azoxystrobin mainly accumulated as a soluble component. Pyraclostrobin and trifloxystrobin accumulated more in the organelles and cell walls. Azoxystrobin and pyraclostrobin enter the root primarily through the apoplast pathway, whereas trifloxystrobin enters the root through the symplastic pathway. Azoxystrobin can be transported in cucumber through anion and cation channels, whereas pyraclostrobin and trifloxystrobin can be transported only through anion channels. This study has great significance in evaluating environmental risks and food safety.

Characterization of hepatotoxic effects induced by pyraclostrobin in human HepG2 cells and zebrafish larvae

Pyraclostrobin is a highly effective and broad-spectrum strobilurin fungicide. With the widespread use of pyraclostrobin to prevent and control crop diseases, its environmental pressure and potential safety risks to humans have attracted much attention. Herein, the toxicological risks of pyraclostrobin toward HepG2 cells and the mechanisms of intoxication in vitro were investigated. The liver toxicity of pyraclostrobin in zebrafish larvae was also evaluated. It was found that pyraclostrobin induced DNA damage and reactive oxygen species generation in HepG2 cells, indicating the potential genotoxicity of pyraclostrobin. The results of fluorescent staining experiments and the expression of cytochrome c, Bcl-2 and Bax demonstrated that pyraclostrobin induced mitochondrial dysfunction, resulting in cell apoptosis. Monodansylcadaverine staining and autophagy marker-related proteins LC3, p62, Beclin-1 protein expression showed that pyraclostrobin promoted cell autophagy. Furthermore, immunoblotting analysis suggested that pyraclostrobin induced autophagy accompanied with activation of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK)/mTOR signaling pathway. Visualization of zebrafish liver and oil red staining indicated that pyraclostrobin could induce liver degeneration and liver steatosis in zebrafish. Collectively, these results help to better understand the hepatotoxicity of pyraclostrobin and provide a scientific basis for its safe applications and risk control.

Mitochondrial Dysfunction Was Involved in Decabromodiphenyl Ethane-Induced Glucolipid Metabolism Disorders and Neurotoxicity in Zebrafish Larvae

Decabromodiphenyl ethane (DBDPE), a novel brominated flame retardant, is becoming increasingly prevalent in environmental and biota samples. While DBDPE has been shown to cause various biological adverse effects, the molecular mechanism behind these effects is still unclear. In this research, zebrafish embryos were exposed to DBDPE (50-400 μg/L) until 120 h post fertilization (hpf). The results confirmed the neurotoxicity by increased average swimming speed, interfered neurotransmitter contents, and transcription of neurodevelopment-related genes in zebrafish larvae. Metabolomics analysis revealed changes of metabolites primarily involved in glycolipid metabolism, oxidative phosphorylation, and oxidative stress, which were validated through the alterations of multiple biomarkers at various levels. We further evaluated the mitochondrial performance upon DBDPE exposure and found inhibited mitochondrial oxidative respiration accompanied by decreased mitochondrial respiratory chain complex activities, mitochondrial membrane potential, and ATP contents. However, addition of nicotinamide riboside could effectively restore DBDPE-induced mitochondrial impairments and resultant neurotoxicity, oxidative stress as well as glycolipid metabolism in zebrafish larvae. Taken together, our data suggest that mitochondrial dysfunction was involved in DBDPE-induced toxicity, providing novel insight into the toxic mechanisms of DBDPE as well as other emerging pollutants.

Enantioselective effect of trifloxystrobin in early-stage zebrafish (Danio rerio) embryos: Cardiac abnormalities impacted by E,E-trifloxystrobin enantiomer

Trifloxystrobin (TFS) is one of the extensively used strobilurin fungicides, which is composed of four enantiomers and its active form is E,E-TFS. In this study, we assess the acute toxicity of four enantiomers, E,E-, E,Z-, Z,E-, and Z,Z-TFS in zebrafish (Danio rerio) embryos. Among the four enantiomers, only E,E-TFS was found to be acutely toxic, with an estimated LC₅₀ value of 0.68 mg/L. Treatment with E,E-TFS resulted in various phenotypic changes in the embryos, including pericardial and yolk-sac edema, spine curvature, and blood pooling. And it shortened the whole body length in the treated embryos by increasing the total intersegmental vessel numbers using a Tg(fli1a:EGFP) zebrafish line. Further study using Tg(cmlc2:EGFP) zebrafish line revealed that E,E-TFS treatment was associated with cardiac malformations, a failure of heart function, and a lowered heartbeat rate at the concentration of 0.25 mg/L. Also, the differential gene expression analysis identified significant down-regulation of vmhc and cacna1c genes encoding ventricular myosin heavy chain and calcium voltage-gated channel subunit alpha 1C, which are crucial for heart development. These results suggest the need for regular monitoring of E,E-TFS enantiomers after field application and further research into their potential chronic effects on environmental organisms.

Transcriptomic and physiological properties reveal the tolerance mechanism to difenoconazole toxicity in wheat (Triticum aestivum L.)

Difenoconazole (DFZ) is a broad-spectrum fungicide widely applied in wheat production. However, excessive accumulation is linked to phytotoxicity. The effects of DFZ on plants and the response mechanisms to DFZ toxicity are poorly understood. Herein, the uptake, accumulation, and translocation of DFZ and induced changes in the morphology, physiology, and gene expression were investigated under hydroculture of roots treated with 50, 100, and 200 mg/L DFZ concentrations. Compared with the control, DEZ treatment upregulated the expression of genes encoding 4-coumarate-CoA ligase (4CL) and peroxidase (POD) involved in the lignin biosynthesis pathway and enhanced lignin biosynthesis. DFZ accumulated more in older leaves (cotyledons and lower true leaves), with 0.49-5.71 and 0.09-2.14 folds higher than levels in new upper leaves and roots, respectively. The excessive accumulation of DFZ in tissues was rapidly degraded, with a 15.7-69.3% reduction of DFZ content in roots and leaves from 3 DAT to 6 DAT. The genes expression and activity of glutathione S-transferase (GST) were increased. Furthermore, DFZ treatments upregulated genes encoding chalcone synthase (CHS), chalcone isomerase (CHI), and anthocyanidin synthase (ANS) involved in the flavonoid biosynthesis pathway and increased the amount of flavonoid and anthocyanins in leaves. This study provides new insights into the self-protective behaviors exhibited by wheat plants under DFZ stress. The mechanisms included hindering DFZ penetration from roots by enhancing lignin biosynthesis, accumulating more in old leaves, degrading by GST, and alleviating oxidative damage by increasing the content of flavonoids and anthocyanins in leaves.

Effects of the fungicide trifloxystrobin on the structure and function of soil bacterial community

Trifloxystrobin has been widely applied to prevent fungal diseases because of its high efficiency and desirable safety characteristics. In the present study, the effects of trifloxystrobin on soil microorganisms were integrally investigated. The results showed that trifloxystrobin inhibited urease activity, promoted dehydrogenase activity. Downregulated expressions of the nitrifying gene (amoA), denitrifying genes (nirK and nirS), and carbon fixation gene (cbbL) were also observed. Soil bacterial community structure analysis showed that trifloxystrobin changed the abundance of bacteria genera related to nitrogen and carbon cycle in soil. Through the comprehensive analysis of soil enzymes, functional gene abundance, and soil bacterial community structure, we concluded that trifloxystrobin inhibited both nitrification and denitrification of soil microorganisms, and also diminished the carbon-sequestration ability. Integrated biomarker response analysis showed that dehydrogenase and nifH were the most sensitive indicators of trifloxystrobin exposure. It provides new insights about trifloxystrobin environmental pollution and its influence on soil ecosystem.

Unravelling joint cytotoxicity of ibuprofen and oxytetracycline on Chlamydomonas reinhardtii using a programmed cell death-related biomarkers panel

Pharmaceutical active compounds (PhACs) are emerging contaminants that pose a growing concern due to their ubiquitous presence and harmful impact on aquatic ecosystems. Among PhACs, the anti-inflammatory ibuprofen (IBU) and the antibiotic oxytetracycline (OTC) are two of the most used compounds whose presence has been reported in different aquatic environments worldwide. However, there is still scarce information about the cellular and molecular alterations provoked by IBU and OTC on aquatic photosynthetic microorganisms as microalgae, even more if we refer to their potential combined toxicity. To test the cyto- and genotoxicity provoked by IBU, OTC and their binary combination on Chlamydomonas reinhardtii, a flow cytometric panel was performed after 24 h of single and co-exposure to both contaminants. Assayed parameters were cell vitality, metabolic activity, intracellular ROS levels, and other programmed cell death (PCD)-related biomarkers as cytoplasmic and mitochondrial membrane potentials and caspase-like and endonuclease activities. In addition, a nuclear DNA fragmentation analysis by comet assay was carried out. For most of the parameters analysed (vitality, metabolic activity, cytoplasmic and mitochondrial membrane potentials, and DNA fragmentation) the most severe damages were observed in the cultures exposed to the binary mixture (IBU+OTC), showing a joint cyto- and genotoxicity effect. Both PhACs and their mixture caused a remarkable decrease in cell proliferation and metabolic activity and markedly increased intracellular ROS levels, parallel to a noticeable depolarization of cytoplasmic and mitochondrial membranes. Moreover, a strong increase in both caspase and endonuclease activities as well as a PCD-related loss of nuclear DNA integrity was observed in all treatments. Results analysis showed that the PhACs caused cell death on this non-target organism, involving mitochondrial membrane depolarization, enhanced ROS production and activation of PCD process. Thus, PCD should be an applicable toxicological target for unraveling the harmful effects of co-exposure to PhACs in aquatic organisms as microalgae.

Ecological risk assessment of environmentally relevant concentrations of propofol on zebrafish (Danio rerio) at early life stage: Insight into physiological, biochemical, and molecular aspects

Propofol is an intravenous anesthetic injection extensively used in clinic, which has been proved to be neurotoxic in humans. Improper use and disposal of propofol may lead to its release into the aquatic environment, but the potential ecological risk of propofol to aquatic organisms remains poorly understood. For this study, we comprehensively explored the ecotoxicological effects and potential mechanisms of propofol (0.04, 0.2 and 2 mg L^-1) on 120 hpf zebrafish (Danio rerio) embryos from physiological, biochemical, and molecular perspectives. The results showed that propofol has moderate toxicity on zebrafish embryos (96 h LC₅₀ = 4.260 mg L^-1), which could significantly reduce the hatchability and delay the development. Propofol can trigger reactive oxygen species (ROS) generation, lipid peroxidation (Malondialdehyde, MDA) and DNA damage (8-hydroxy-2-deoxyguanosine, 8-OHdG). The glutathione peroxidase (GPX) activity of zebrafish embryos in 0.04 and 0.2 mg L^-1 propofol treatment group was activated in response to oxidative damage, while activities of superoxide dismutase (SOD), catalase (CAT) and GPX in zebrafish treated with 2 mg L^-1 was significant inhibited compared with the control group (p＜0.05). Moreover, the expression of antioxidant genes and related pathways was inhibited. Apoptosis was investigated at genes level and histochemistry. Molecular docking confirmed that propofol could change in the secondary structure of acetylcholinesterase (AChE) and competitively inhibited acetylcholine (ACh) binding to AChE, which may disturb the nervous system. These results described toxic response and molecular mechanism in zebrafish embryos, providing multiple aspects about ecological risk assessment of propofol in water environment.

Monitoring residues of pesticides in food in Brazil: A multiscale analysis of the main contaminants, dietary cancer risk estimative and mechanisms associated

Introduction

Pesticides pose a risk for cancer development and progression. People are continuously exposed to such substances by several routes, including daily intake of contaminated food and water, especially in countries that are highly pesticide consumers and have very permissive legislation about pesticide contamination as Brazil. This work investigated the relationship among pesticides, food contamination, and dietary cancer risk.

Methods

Analyzed two social reports from the Brazilian Government: the Program for Analysis of Residues of Pesticides in Food (PARA) and The National Program for Control of Waste and Contaminants (PNCRC).

Results and discussion

First, we characterized the main pesticide residues detected over the maximum limits allowed by legislation or those prohibited for use in food samples analyzed across the country. Based on this list, we estimated the dietary cancer risks for some of the selected pesticides. Finally, we searched for data about dietary cancer risks and carcinogenic mechanisms of each pesticide. We also provided a critical analysis concerning the pesticide scenario in Brazil, aiming to discuss the food contamination levels observed from a geographical, political, and public health perspective. Exposures to pesticides in Brazil violate a range of human rights when food and water for human consumption are contaminated.

Resveratrol alleviates pyraclostrobin-induced lipid peroxidation, oxidative stress, and DNA damage in rats

Pyraclostrobin (Pyra) is a fungicide in the strobilurin class and has proven to be very toxic to organisms primarily aquatic species. Resveratrol (Res) is a phytoalexin that exhibits multiple bioactivities as anti-oxidative, anti-inflammatory, cardiovascular protective, and anti-aging and is found in plant species such as mulberry, peanut, and grape. This study aimed to determine the protective effect of Res against Pyra-induced lipid peroxidation, oxidative stress, and DNA damage in rats. For this purpose, a total of 48 male rats divided into 6 groups - 8 in each group - were exposed to 30 mg/kg Pyra by oral gavage once a day for 30 days and to three different concentrations of Res (5, 10, and 20 mg/kg) together with Pyra. Pyra administration increased liver enzyme parameters and malondialdehyde (MDA) levels whereas decreased glutathione (GSH) levels and activities of superoxide dismutase (SOD) and catalase (CAT). Also, Pyra treatment increased pro-apoptotic (Bax), apoptotic (Caspase-3, Caspase-8, and Caspase-9), pro-inflammatory (NFκB), cancer (CYP2E1), and cell regulatory (p53) gene expressions and decreased anti-apoptotic (Bcl-2) gene expression in the liver. Furthermore, DNA damage in blood and histopathological changes in the liver and kidney were observed with Pyra administration. In contrast, Res administrations in a dose-dependent manner improved Pyra-induced lipid peroxidation, oxidative and DNA damages, expression levels of these genes in the liver, and histopathological changes in the liver and kidney. Consequently, the treatment of Res, known for its anti-oxidant and protective properties, exhibited a protective effect on Pyra-induced lipid peroxidation, oxidant/anti-oxidant status, gene expressions, and DNA damage in rats.

Residual analysis of QoI fungicides in multiple (six) types of aquatic organisms by UPLC-MS/MS under acutely toxic conditions

In view of the significance of food safety and the possible relationship between residual enrichment and acute toxicity for pesticides in different aquatic organisms, it is essential to establish a sensitive and reliable determination method for pesticides in different aquatic organisms to analyze the enrichment levels. Quinone outside inhibitor fungicides (QoIs) are lipophilic fungicides that pose environmental threats to aquatic organisms. Previous research has mainly focused on QoI residues in aquatic organisms under chronic toxicity, whereas less is known about how pesticide residues differ among aquatic organism under acutely toxic conditions. In the present study, the residues of QoIs in aquatic organisms (Danio rerio, Rana pipiens, Cherax quadricarinatus, Misgurnus anguillicaudatus, Corbicula fluminea, and Ampullaria gigas) were analyzed by ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) coupled with a proposed QuEChERS method. The proposed method was validated in terms of linearity (coefficients of determination of 0.9980-0.9999), the limits of quantification (0.01 μg·kg^-1), the relative standard deviation (0.6-4.4%), and recovery (70.12-118.15%). The results demonstrated that the proposed method fulfilled the requirements for pesticide analysis in all tested aquatic organisms. The residues of QoIs in the same aquatic organism exposed to QoI concentrations of 5 and 500 μg L^-1 decreased in the order pyraoxystrobin > pyraclostrobin > triclopyricarb > picoxystrobin > azoxystrobin > fluoxastrobin. Furthermore, the acute toxicity was strongly correlated with the enrichment level of the QoIs in aquatic organisms. This study provides the first documentation of a correlation between the enrichment level of QoIs and acute toxicity in aquatic organisms, which provides a basis for the management of agrochemicals considering aquatic ecological risks.

Analyzing toxicological effects of AsIII and AsV to Chlamys farreri by integrating transcriptomic and metabolomic approaches

Inorganic arsenic (iAs) is a widespread contaminant in marine environments, which is present in two different oxidation states (arsenate (AsV) and arsenite (AsIII)) that have complex toxic effects on marine organisms. The scallop Chlamys farreri (C. farreri) accumulates high levels of As and is a suitable bioindicator of As. In this report, we integrated transcriptomics and metabolomics to investigate genetic and metabolite changes and functional physiological disturbances in C. farreri exposured to inorganic arsenic. Physiological indicators antioxidant factors and cell apoptosis analysis macroscopically corroborated the toxic effects of inorganic arsenic revealed by omics results. Toxic effects of inorganic arsenic on C. farreri were signaling-mediated, causing interference with a variety of cell growth and small molecule metabolism. The results provide evidence that inorganic arsenic disrupts the physiological functions of bivalves, highlighting the correlations between different metabolic pathways and providing new insights into the toxic effects of environmental pollutants on marine organisms.

Degradation of Kresoxim-Methyl in Different Soils: Kinetics, Identification of Transformation Products, and Pathways Using High-Resolution-Mass-Spectrometry-Based Suspect and Non-Target Screening Approaches

This study investigated the degradation of strobilurin fungicide kresoxim-methyl (KM) in three typical agricultural soils from China by aerobic and anaerobic degradation experiments, focusing on degradation kinetics of KM, identification of transformation products (TPs), and prediction of toxicity end points via in silico approaches. KM showed a pronounced biphasic degradation in different soils and could rapidly degrade, with DT₅₀ of <3 days. Four TPs were identified by high-resolution mass spectrometry (HRMS), and three of them have never been reported before. Possible degradation pathways of KM in soil were proposed, including hydrolysis, oxidation, and reduction, and the main mechanism involved in the biodegradation of KM was the hydrolysis of methyl ester regardless of aerobic or anaerobic conditions. The results of toxicity evaluation indicated that some TPs are more toxic than KM and may have a developmental toxicity and mutagenicity, and further risk assessment should be carried out.

Long-term exposure to azoxystrobin induces immunodeficiency in fish that are vulnerable to subsequent rhabdovirus infection

Azoxystrobin (AZ) is one of the most widely used strobilurin fungicides in the world, and its residue has seriously endangered aquatic ecological security. Our previous data showed that AZ exposure may reduce the resistance of fish to rhabdovirus infection in aquatic environment. Here, we further reported a potential long-term adverse effect of AZ exposure on the antiviral and immunosuppressive recovery in fish, and observed that mitochondrial dynamic balance was disturbed by AZ in which excessive mitochondrial fission occurred in response to decreased ATP levels. When a recovery operation was performed in AZ-exposed cells and fish, infectivity of our model virus, spring viraemia of carp virus (SVCV), was significantly decreased in vitro (using the epithelioma papulosum cyprini [EPC] fish cell line) and in vivo (using zebrafish) in a time-dependent manner. Also, the expression of eight innate antiviral immune genes (IFNs, ISG15, MX1, RIG-I, IRF3, Nrf2 and HO-1) showed a similar change to SVCV replication between the longer exposure period and the expression recovery. Additionally, AZ facilitated horizontal transmission of SVCV in a static cohabitation challenge model, predicting the increase of the potential for the viral outbreak. Therefore, our data suggest that long-term effect of AZ on irreparable impairment in fish made AZ residue potentially greater for ecological risks.

Hepatopancreas toxicity and immunotoxicity of a fungicide, pyraclostrobin, on common carp

Pyraclostrobin (PYR), a strobilurin fungicide, has been widely used to control fungal diseases, posing potential risk to aquatic organisms. However, the toxic effects of PYR to fish remained largely unknown. In this study, common carp (Cyprinus carpio L.) was exposed to environmentally relevant levels of PYR (0, 0.5 and 5.0 μg/L) for 30 days to assess its chronic toxicity and potential toxicity mechanism. The results showed that long-term exposure to PYR induced hepatopancreas damage as evident by increased in serum transaminase activities (AST and ALT). Moreover, PYR exposure remarkably enhanced the expressions of hsp70 and hsp90, decreased the levels of antioxidant enzymes and biomarkers and promoted the reactive oxygen species (H₂O₂ and O₂^-) and MDA contents in carp hepatopancreas. PYR exposure also upregulated apoptosis-related genes (bax, apaf-1, caspase-3 and caspase-9) and reduced anti-apoptosis gene bcl-2 in fish hepatopancreas. Moreover, PYR exposure altered the expressions of inflammatory cytokines (IL-1β, IL-6, TNF-α and TGF-β) in the serum and hepatopancreas and the level of NF-κB p65 in the hepatopancreas. Further research indicated that PYR exposure markedly changed the levels of immune parameters (LYZ, C3, IgM, ACP and AKP) in the serum and/or hepatopancreas, indicating that chronic PYR exposure also has immunotoxicity on fish. Additionally, we found that PYR exposure upregulated p38 and jnk MAPK transcription levels, suggesting that MAPK may be play important role in PYR-induced apoptosis and inflammatory response in the hepatopancreas of common carp. In summary, PYR exposure induced oxidative stress, triggered apoptosis, inflammatory and immune response in common carp, which can help to elucidate the possible toxicity mechanism of PYR in fish.

Histology and metabonomics reveal the toxic effects of kresoxim-methyl on adult zebrafish

Studies have shown that kresoxim-methyl (KM) and other strobilurin fungicides have toxic effects on aquatic organisms. However, the potential deleterious effects of kresoxim-methyl (KM) on adult zebrafish regarding the ecological risk of environmental concentration remain unclear. Here, the histology and untargeted metabonomics was used to investigate the adverse effect on female zebrafish after exposure to KM at environmental concentration, aquatic life benchmark and one-half LC₅₀ of adult zebrafish. Results demonstrated KM affected zebrafish liver, ovary and intestine development, blurred the boundary between hepatocytes or caused hepatic vacuoles, increased the percentage of perinucleolar oocyte and cortical alveolus oocyte, decreased intestinal goblet cells and disturbed villus and wall integrity after 21 d exposure. Metabonomics showed different concentrations of KM simultaneously influenced the metabolites annotated to vitamin digestion and absorption, serotonergic synapse, retinol metabolism, ovarian steroidogenesis and arachidonic acid (AA) metabolism in zebrafish liver. Results showed the decreased triglyceride and cholesterol levels, as well as the metabolic alterations in amino acid, lipid, vitamin and retinol metabolism caused by KM, might disturb the energy supply for normal liver development and oocyte maturation. In addition, KM altered the transcription of Tdo2a, Tdo2b, Ido1, Cxcl8b, Cyp7a, Cyp11a, Cyp11b, Cyp17a, Cyp19a, Hsd3β, Hsd17β, Pla2, Ptgs2a and Ptgs2b, the level of TG, TC, MDA, IFN, IL6 and Ca²⁺, and the activity of CAT, SOD Ca²⁺-ATPase in zebrafish liver. Moreover, cytoscape analysis suggested the disturbed AA metabolism caused by KM, might interconnect multiple metabolic pathways to share implicated function in the regulation of oocyte maturation and immune response. Current study brought us closer to an incremental understanding of the toxic mechanism of KM on adult zebrafish, indicated there was crosstalk among different regulatory pathways to regulate the metabolic disorders and biologically hazardous effects induced by KM.

Toxicological risks of SDHIs and QoIs to zebrafish (Danio rerio) and the corresponding poisoning mechanism

Quinone outside inhibitor fungicides (QoIs) and succinate dehydrogenase inhibitor fungicides (SDHIs) were classified as highly or moderately toxic to nontarget aquatic organisms, which deterred their application in paddy scenario. Currently, the mechanism of toxicity regarding which factors govern their risk ranking in fish species are not fully explored. In this study, adult zebrafish were exposed to four QoIs (pyraclostrobin, trifloxystrobin, kresoxim-methyl, and azoxystrobin) and three SDHIs (isopyrazam, thifluzamide, and boscalid) to assess its acute toxicity and effects on tissue accumulation and gill injury. The results showed that the overall toxicity level was in the order of QoIs > SDHIs, whereas the order of accumulation capacity was SDHIs > QoIs. Seven mitochondrial respiratory inhibitors exposure induced serious histological damage in the gills, including aneurism, curling, telangiectasia and swelling, and caused mitochondrial dysfunction and weaker complex II and III activities. The correlation between their acute toxicities and in vitro gill cytotoxicity was significant (R = 0.868), whereas the bioaccumulation level was not markedly associated with their 96h-LC₅₀ values in zebrafish (R = -0.686), indicating the degree of target organ (gill) injury may be the decisive factor that governs the risk grade of respiratory inhibitors in fish. Additionally, the docking positions and binding energies of fungicides with the target proteins may be responsible for their differential branchial damage. These results offer a point of reference and theoretical support for the design of fungicides and appropriate formulations with improved environmental safety that could broaden their application scenario.

Adverse effects of SYP-3343 on zebrafish development via ROS-mediated mitochondrial dysfunction

As a newly-invented and highly-efficiency strobilurin fungicide, pyraoxystrobin (SYP-3343) has been recognized as a highly poisonous toxin for a variety of aquatic organisms. Nevertheless, the developmental toxicity and potential mechanism of SYP-3343 have not been well-documented. The results showed that SYP-3343 was relatively stable and maintained within the range of 20 % in 24 h, and the LC₅₀ value to embryos at 72 hpf was 17.13 μg/L. The zebrafish embryotoxicity induced by 1, 2, 4, and 8 μg/L SYP-3343 is demonstrated by repressive embryo incubation, enhancive mortality rate, abnormal heart rate, malformed morphological characteristic, and impaired spontaneous coiling, indicating SYP-3343 mostly exerted its toxicity in a dose- and time-dependent manner. Besides SYP-3343 was critically involved in regulating cell cycle, mitochondrial membrane potential, and reactive oxygen species production as well as zebrafish primary cells apoptosis, which can be mitigated using antioxidant N-acetyl-L-cysteine. A significant change occurred in total protein content, the biochemical indices, and antioxidant capacities owing to SYP-3343 exposure. Additionally, SYP-3343 altered the mRNA levels of heart development-, mitochondrial function-, and apoptosis-related genes in zebrafish embryos. These results indicated that SYP-3343 induced apoptosis accompanying reactive oxygen species-initiated mitochondrial dysfunction in zebrafish embryos.

Low trifloxystrobin-tebuconazole concentrations induce cardiac and developmental toxicity in zebrafish by regulating notch mediated-oxidative stress generation

Trifloxystrobin-tebuconazole (TFS-TBZ) is a novel, broad-spectrum fungicide that has been frequently detected in both the environment and agricultural products. However, its adverse effects on aquatic organisms remain unknown. In this study, the adverse effects of ecologically relevant TFS-TBZ concentrations (i.e., 75.0, 112.5, and 150.0 μg/L) on the heart and development of zebrafish were investigated. TFS-TBZ was found to substantially hinder development, inhibit growth, and cause significant abnormity at higher concentrations. Moreover, TFS-TBZ caused severe pericardial edema, heart loop failure, cardiac linearization, and ultra-slow heartbeat, implying that TFS-TBZ might induce congenital heart disease. TFS-TBZ inhibited Notch signaling and increased the intracellular generation of reactive oxygen species, resulting in decreased myocardial cell proliferation and increased apoptosis. The use of sodium valproate and Gadofullerene illustrated the relevance of the Notch signaling system and oxidative stress. Finally, TFS-TBZ exposure conveys severe developmental toxicity to the zebrafish heart. The underlying mechanism is regulation notch mediated-oxidative stress generation, implying that TFS-TBZ may be potentially hazardous to aquatic organisms in the environment.

Toxicity evaluation of pyraclostrobin exposure in farmland soils and co-exposure with nZnO to Eisenia fetida

Although the toxicity of pyraclostrobin (PYRA) to earthworms in artificial soil is well known, the toxicity of PYRA in farmland soils is yet to be explored in detail. Additionally, with more zinc oxide nanoparticles (nZnO) entering the soil environment, the risk of PYRA co-exposure with nZnO is increasing alarmingly. However, toxicity caused by this co-exposure of PYRA and nZnO is still unknown. Therefore, we assessed the biomarkers responses to reveal the toxicity of PYRA (0.1, 1, 2.5 mg/kg) on earthworms in farmland soils (black soil, fluvo-aquic soil, and red clay) and evaluated the biomarkers responses of Eisenia fetida exposed to PYRA (0.5 mg/kg)/PYRA+nZnO (10 mg/kg). Moreover, transcriptomic analysis was performed on E. fetida exposed to PYRA/PYRA+nZnO for 28 days to reveal the mechanism of genotoxicity. The Integrated Biomarker Responses (IBR) showed PYRA induced more severe oxidative stress and damage to E. fetida in farmland soils than that in artificial soil. The oxidative stress and damage induced by PYRA+nZnO were greater than that induced by PYRA. Transcriptomic analysis showed that PYRA and PYRA+nZnO significantly altered gene expression of both biological processes and molecular functions. These results provided toxicological data for PYRA exposure in three typical farmland soils and co-exposure with nZnO.

Combined effects of S-metolachlor and benoxacor on embryo development in zebrafish (Danio rerio)

It is necessary to study the combined toxicity of an herbicide and its safener because the two are often used in combination. S-metolachlor and its safener benoxacor have been detected in aquatic environments and can individually damage the oxidative stress system in zebrafish embryos (Danio rerio). However, only their separate toxicity in zebrafish (Danio rerio) embryo development has been reported. This study assessed the combined toxicity of benoxacor and S-metolachlor in zebrafish embryo development, including acute toxicity, developmental toxicity, oxidative damage, and cell apoptosis. The 96-h LC₅₀ values were higher in mixtures of benoxacor and S-metolachlor than in benoxacor alone. The treatments included S-metolachlor, Mix-1 (0.1 mg/L benoxacor + 0.1 mg/L S-metolachlor), Mix-2 (0.1 mg/L benoxacor + 0.3 mg/L S-metolachlor) and benoxacor alone. Embryos exposed to Mix-1 and Mix-2 had lower developmental toxicities, superoxide dismutase (SOD) activity, osx and cat expression levels than those exposed to benoxacor alone. Moreover, glutathione S-transferase (GST), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx) activities, and the expressions of tbx16, nrf2, bcl2, and caspase9 were higher in the mixtures than in the benoxacor group. High-throughput RNA sequencing revealed that benoxacor had a greater effect on gene regulation than Mix-1 and Mix-2. The malformation rate, different enrichment gene numbers, and gene expression levels of hatched embryos were higher in Mix-1 than in Mix-2. The results indicate that a mixture of S-metolachlor and benoxacor has antagonistic effects in the early stage of embryo development. The mixtures can break the reactive oxygen species balance, causing abnormal cell apoptosis and developmental malformation in embryos. Besides investigating the combined toxicity of benoxacor and S-metolachlor in zebrafish embryo development, this study provides a risk assessment basis for a herbicide combined with its safener.

Zebrafish larvae acute toxicity test: A promising alternative to the fish acute toxicity test

Aquatic toxicity is a mandatory component in risk assessment of chemicals. The currently recommended used acute fish toxicity (AFT) test requires a large test system, bringing onerous experimental operation and discharge of much experimental wastewater. In this study, we established a more convenient and efficient test defined as the zebrafish larvae acute toxicity (FLT) test, which employed zebrafish larvae at four days post fertilization as the test organisms and implemented a 48-hour exposure in 6-well plates. Based on validated reproducibility, we applied this test to evaluate the acute toxicity of 35 chemicals. By comparing the results with the existing acute toxicity data reported in the literature, we found that most chemicals exhibited highly positive correlated LC₅₀ in the FLT and the AFT test, with the same or similar toxicity grade. The FLT test showed more comparable sensitivity with the current AFT test than the previously recommended fish embryo acute toxicity test (FET). Moreover, the FLT test is easier to implement than the FET test which requires microscopic observation to identify the fertilization and development status of the embryos. Despite a limitation similar to the FET test in terms of detecting neurotoxicants, the FLT test could be a more promising alternative to the AFT test relative to the FET test.

What Zebrafish and Nanotechnology Can Offer for Cancer Treatments in the Age of Personalized Medicine

Cancer causes millions of deaths each year and thus urgently requires the development of new therapeutic strategies. Nanotechnology-based anticancer therapies are a promising approach, with several formulations already approved and in clinical use. The evaluation of these therapies requires efficient in vivo models to study their behavior and interaction with cancer cells, and to optimize their properties to ensure maximum efficacy and safety. In this way, zebrafish is an important candidate due to its high homology with the human genoma, its large offspring, and the ease in developing specific cancer models. The role of zebrafish as a model for anticancer therapy studies has been highly evidenced, allowing researchers not only to perform drug screenings but also to evaluate novel therapies such as immunotherapies and nanotherapies. Beyond that, zebrafish can be used as an “avatar” model for performing patient-derived xenografts for personalized medicine. These characteristics place zebrafish in an attractive position as a role model for evaluating novel therapies for cancer treatment, such as nanomedicine.

Investigation of toxicity effect of TiCN coated on 304 SS and 410 SS substrates in rat fibroblasts and B-lymphocytes

In the present study, TiCN thin films were coated on AISI 304 and AISI 410 stainless steel (SS) substrates by Cathodic Arc Physical Vapor Deposition method. TiCN-coated substrates were confirmed by the XRD analysis results. Dense morphology and fine-grained surface of TiCN film were established by SEM images. Cellular toxicity of the coated 304 SS and 410 SS substrates was investigated in the fibroblasts and B-lymphocyte. In respect to that, we have shown coated substrates cytotoxicity, oxidative stress as well as cell viability, reactive oxygen species (ROS), lipid peroxidation (MDA), protein carbonyl, glutathione oxidase (GSSG), and glutathione reductase (GSH) assessment, releasing cytochrome c (Cytc), lysosomal membrane destabilization (AO) may lead to cell death signaling. Our results showed that the coated 304 SS and 410 SS substrates induced cells dysfunction via a significant increase in ROS production, MDA (P < 0.01 and P < 0.001), protein carbonyl (P < 0.05), and GSSG (P < 0.05 and P < 0.01) that correlated to cytochrome c release (P < 0.01). In addition, increased disturbance in oxidative phosphorylation was also shown by the decrease in cell viability (P < 0.001) and GSH (P < 0.01 and P < 0.001) in the coated 304 SS and 410 SS substrates-treated fibroblast and B-lymphocytes. The coated 304 SS and 410 SS substrates contacted cells and trafficked to the lysosomes and this is followed by lysosomal damage, leading to apoptosis/Necrosis. Our results indicated that these materials cause cellular dysfunction and subsequent oxidative stress leading to cognitive impairment in the rat fibroblasts and B-lymphocytes cells.

Carboxylesterases from bacterial enrichment culture degrade strobilurin fungicides

Strobilurin fungicides are a class of persistent fungicides frequently detected in the environment. Microbes can effectively degrade strobilurins, but the mechanisms are complex and diverse. Compared with isolated strains, bacterial consortia are more robust in terms of the degradation of multiple pollutants. The enrichment culture XS19 is a group of bacterial strains enriched from soil and degrades six strobilurins at 50 mg/L within 8 d, including azoxystrobin, picoxystrobin, trifloxystrobin, kresoxim-methyl, pyraclostrobin and enestroburin. LC-Q-TOF-MS analysis confirmed that XS19 can demethylate these strobilurins via hydrolysis of the methyl ester group. Analysis of the bacterial communities suggested that Pseudomonas (69.8%), Sphingobacterium (21.2%), Delftia (6.3%), and Achromobacter (1.6%) spp. were highly associated with the removal of strobilurins in the system. Metagenomics-based comprehensive analysis of XS19 suggested that carboxylesterases in Pseudomonas and Sphingobacterium play a central role in the catabolism of strobilurins. Moreover, the carboxylesterase inhibitor bis-p-nitrophenyl phosphate inhibited the degradation activity of strobilurins in XS19. This work proved that XS19 or carboxylesterases can effectively hydrolyze strobilurins, providing a reliable bioremediation paradigm.

Pyraclostrobin Removal in Pilot-Scale Horizontal Subsurface Flow Constructed Wetlands and in Porous Media Filters

Pyraclostrobin is a fungicide extensively used for the control of various fungal diseases and is frequently detected in environmental samples. Natural systems, such as constructed wetlands (CWs) and gravity filters, are effective and environmentally friendly treatment systems, which can reduce or eliminate pesticides from the environment. The aim of this study was to investigate the capacity of two pilot-scale CWs (porous media: cobbles and fine gravel, planted with Phragmites australis) and six gravity filters (filling material: bauxite, carbonate gravel and zeolite) to remove pyraclostrobin from polluted water originating from spraying equipment rinsing sites. For this, experiments were conducted to test the performance of the above natural systems in removing this fungicide. The results showed that the mean percent pyraclostrobin removal efficiencies for cobbles and fine gravel CW units were 56.7% and 75.2%, respectively, and the mean percent removals for HRTs of 6 and 8 days were 68.7% and 62.8%, respectively. The mean removal efficiencies for the bauxite, carbonate gravel and zeolite filter units were 32.5%, 36.7% and 61.2%, respectively, and the mean percent removals for HRTs 2, 4 and 8 days were 39.9%, 43.4% and 44.1%, respectively. Regarding the feeding strategy, the mean removal values of pyraclostrobin in gravity filter units were 43.44% and 40.80% for continuous and batch feeding, respectively. Thus, these systems can be used in rural areas for the treatment of spraying equipment rinsing water.

Photo-enhanced toxicity of crude oil on early developmental stages of Atlantic cod (Gadus morhua)

Photo-enhanced toxicity of crude oil is produced by exposure to ultraviolet (UV) radiation. Atlantic cod (Gadus morhua) embryos were exposed to crude oil with and without UV radiation (290-400 nm) from 3 days post fertilization (dpf) until 6 dpf. Embryos from the co-exposure experiment were continually exposed to UV radiation until hatching at 11 dpf. Differences in body burden levels and cyp1a expression in cod embryos were observed between the exposure regimes. High doses of crude oil produced increased mortality in cod co-exposed embryos, as well as craniofacial malformations and heart deformities in larvae from both experiments. A higher number of differentially expressed genes (DEGs) and pathways were revealed in the co-exposure experiment, indicating a photo-enhanced effect of crude oil toxicity. Our results provide mechanistic insights into crude oil and photo-enhanced crude oil toxicity, suggesting that UV radiation increases the toxicity of crude oil in early life stages of Atlantic cod.

Health risks of sulfentrazone exposure during zebrafish embryo-larvae development at environmental concentration

Knowledge about the negative effects and mechanism of sulfentrazone (SUL) on aquatic early life stages is still limited. Here we investigated the lethal and sub-lethal effects of SUL during zebrafish embryo-larvae development. Results demonstrated that the 96 h and 120 h-LC₅₀ of SUL to embryonic zebrafish was 2.02 mg/L, and the 30 d-LC₅₀ was 0.899 mg/L after embryos exposed to SUL for 30 d. High concentrations of SUL delayed yolk sac absorption, disordered the hatching and heart rate during zebrafish embryonic stage, while 0.0100-0.100 mg/L SUL had no phenotypic changes on embryonic development, but decreased the body weight of larvae after 30 d exposure. RNA-seq identified 321, 394 and 727 differentially expressed genes in larvae after embryos exposed to 0.0100 mg/L, 0.0400 mg/L and 0.400 mg/L SUL for 30 d, found that the transcriptional profiles involved in heart development and endocrine disruption were simultaneously influenced by different concentrations of SUL, such as adrenergic signaling in cardiomyocytes, cardiac muscle contraction, cell adhesion molecules and steroid biosynthesis. Biochemical analysis showed that SUL increased the levels of E₂, T₃ and TSH, induced the activities of mitochondrial complex IV, cytochrome c oxidase, Ca²⁺-ATPase, total Na⁺K⁺-ATPase and Ca²⁺Mg²⁺-ATPase, and decreased ATP formation after embryos exposed to SUL for 5 d and 30 d. Further comprehensive analysis demonstrated that SUL caused more significantly alteration on the transcript, level or activity of the key elements involved in heart development and endocrine disruption after 30 d exposure, indicated long-term SUL exposure might cause more negative effects on zebrafish at doses below the presumed no-observed-adverse-effect level during early life development. The results inferred the environmental concentration of SUL might cause potential cardiac and endocrine health risk in zebrafish later life stages, also facilitated a better understanding of the sub-lethal effects and molecular mechanism of SUL on aquatic organism.

Transcriptome Analysis of the Toxic Effects of Amisulbrom and Isoflucypram on Zebrafish (Danio rerio) Larvae

Fungicides are frequently detected in the water bodies, however, the adverse effects of these fungicides on aquatic lives remain limited. To better understand the adverse effects of amisulbrom (AML) and isoflucypram (ISO) on embryogenesis, zebrafish embryos were exposed to two different fungicides, 0.75 μM amisulbrom (AML) and 2.5 μM isoflucypram (ISO), for 72 h. Transcriptome sequencing was employed to identify differentially expressed genes (DEGs) after AML and ISO exposure. A total of 571 and 3471 DEGs were detected between the libraries of the two fungicides-treated groups and the control, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that PPAR signaling pathway, phototransduction, ribosome and p53 signaling pathway were significantly enriched in response to both AML and ISO stress. Moreover, a number of DEGs involved in tyrosine metabolism, phagosome pathway, cell cycle pathway, extracellular matrix (ECM) receptor interaction pathway, and arginine and proline metabolism were specially enriched after exposure to AML; a number of DEGs involved in notch signaling pathway, drug metabolism, alanine, aspartate and glutamate metabolism, amino-acyl−tRNA biosynthesis, and protein processing in endoplasmic reticulum were significantly enriched after exposure to ISO. These results provide novel insights into the toxicological mechanisms underlying fish’s responses to fungicides.

Decabromodiphenyl Ethane Mainly Affected the Muscle Contraction and Reproductive Endocrine System in Female Adult Zebrafish

The novel brominated flame retardant decabromodiphenyl ethane (DBDPE) has become a widespread environmental pollutant. However, the target tissue and toxicity of DBDPE are still not clear. In the current study, female zebrafish were exposed to 1 and 100 nM DBDPE for 28 days. Chemical analysis revealed that DBDPE tended to accumulate in the brain other than the liver and gonad. Subsequently, tandem mass tag-based quantitative proteomics and parallel reaction monitoring verification were performed to screen the differentially expressed proteins in the brain. Bioinformatics analysis revealed that DBDPE mainly affected the biological process related to muscle contraction and estrogenic response. Therefore, the neurotoxicity and reproductive disruptions were validated via multilevel toxicological endpoints. Specifically, locomotor behavioral changes proved the potency of neurotoxicity, which may be caused by disturbance of muscular proteins and calcium homeostasis; decreases of sex hormone levels and transcriptional changes of genes related to the hypothalamic-pituitary-gonad-liver axis confirmed reproductive disruptions upon DBDPE exposure. In summary, our results suggested that DBDPE primarily accumulated in the brain and evoked neurotoxicity and reproductive disruptions in female zebrafish. These findings can provide important clues for a further mechanism study and risk assessment of DBDPE.

Effects of Pesticides on Longevity and Bioenergetics in Invertebrates-The Impact of Polyphenolic Metabolites

Environmentally hazardous substances such as pesticides are gaining increasing interest in agricultural and nutritional research. This study aims to investigate the impact of these compounds on the healthspan and mitochondrial functions in an invertebrate in vivo model and in vitro in SH-SY5Y neuroblastoma cells, and to investigate the potential of polyphenolic metabolites to compensate for potential impacts. Wild-type nematodes (Caenorhabditis elegans, N2) were treated with pesticides such as pyraclostrobin (Pyr), glyphosate (Gly), or fluopyram (Fluo). The lifespans of the nematodes under heat stress conditions (37 °C) were determined, and the chemotaxis was assayed. Energetic metabolites, including adenosine triphosphate (ATP), lactate, and pyruvate, were analyzed in lysates of nematodes and cells. Genetic expression patterns of several genes associated with lifespan determination and mitochondrial parameters were assessed via qRT-PCR. After incubation with environmentally hazardous substances, nematodes were incubated with a pre-fermented polyphenol mixture (Rechtsregulat^®Bio, RR) or protocatechuic acid (PCA) to determine heat stress resistance. Treatment with Pyr, Glyph and Fluo leads to dose-dependently decreased heat stress resistance, which was significantly improved by RR and PCA. The chemotaxes of the nematodes were not affected by pesticides. ATP levels were not significantly altered by the pesticides, except for Pyr, which increased ATP levels after 48 h leads. The gene expression of healthspan and mitochondria-associated genes were diversely affected by the pesticides, while Pyr led to an overall decrease of mRNA levels. Over time, the treatment of nematodes leads to a recovery of the nematodes on the mitochondrial level but not on stress resistance on gene expression. Fermented extracts of fruits and vegetables and phenolic metabolites such as PCA seem to have the potential to recover the vitality of C. elegans after damage caused by pesticides.

Oxidative stress and DNA damage induced by trifloxystrobin on earthworms (Eisenia fetida) in two soils

Trifloxystrobin is a new type of fungicide, which is extensively used due to its excellent antifungal activity. In this study, oxidative stress and DNA damage induced by trifloxystrobin exposure was evaluated using Eisenia fetida at subchronic toxicity concentrations in artificial soil and brown soil (0.1-2.5 mg/kg). Throughout the exposure period (days 7, 28 and 56), six biochemical indicators including reactive oxygen species (ROS), antioxidant enzymes (SOD and CAT), glutathione S-transferase (GST), lipid peroxidation and DNA damage (8-hydroxydeoxyguanosine) were measured. In addition, the integrated biomarker response (IBR) index was calculated to make comparison of toxicological response between artificial and brown soils. Results indicated that trifloxystrobin can induce oxidative stress and DNA damage to earthworms with subchronic toxicity greater in brown soil compared to artificial soil as determined through integrated calculations for six biochemical indicators. Trifloxystrobin toxicological experiments in artificial soil may not accurately evaluate its toxicity in natural soil ecosystems, as the toxicity of trifloxystrobin to Eisenia fetida was underestimated.

Behavioral and developmental toxicity assessment of the strobilurin fungicide fenamidone in zebrafish embryos/larvae (Danio rerio)

Strobilurin fungicides are among the most widely used in the world and have characteristics that include high water solubility and toxicity to aquatic organisms. While several studies report on mechanisms of toxicity of strobilurins in fish, there are no data on the sub-lethal toxicity of fish to the fungicide fenamidone. To address this gap, survival and hatch rate, deformities, mitochondrial bioenergetics, expression of oxidative stress and apoptotic genes, and behavior (locomotor activity and anxiolytic-related behaviors) were assessed in zebrafish embryos and larvae following exposure to fenamidone. Fenamidone negatively affected development of zebrafish embryos, causing a delay of hatching time at concentrations of 2.5 and 5 μM. Fenamidone caused morphological deformities in zebrafish, including pericardial edema, yolk sac edema, tail deformities, and spinal curvature. Exposure to 1.5 μM fenamidone reduced surface area of swim bladder in larvae at 6 dpf. Fenamidone significantly reduced oxygen consumption rates of embryos; 5 μM fenamidone decreased basal respiration (~85%), oligomycin induced ATP-linked respiration (~70%), FCCP-induced maximal respiration (~75%) and non-mitochondrial respiration (~90%) compared to controls. Sod2 mRNA levels were decreased by fenamidone in larval fish. Locomotor activity was significantly decreased in zebrafish larvae following exposure to 2 μM fenamidone but there was no evidence for anxiolytic nor anxiety-related behaviors (exposures of 100 nM up to 1.5 µM). This study addresses a data gap for potential risks associated with fenamidone exposure in developing fish.

Effects of strobilurin fungicides (azoxystrobin, pyraclostrobin, and trifloxystrobin) on survival, reproduction and hatching success of Enchytraeus crypticus

Large quantities of strobilurin fungicides (SFs) are used worldwide, resulting in adverse effects on non-target organisms. SFs affect the reproduction and embryonic development of aquatic organisms, while the impact on soil organisms has been insufficiently researched. Therefore, we investigated the effects of three SFs (azoxystrobin (AZO), pyraclostrobin (PYR), and trifloxystrobin (TRI)) on the survival, reproduction, and hatching success of the non-target soil oligochaete Enchytraeus crypticus. The standard enchytraeid reproduction test (ERT) showed that, regarding survival, TRI (LC₅₀ = 2.34 mg/kg) was the most toxic, followed by PYR (LC₅₀ = 4.26 mg/kg) and AZO (LC₅₀ ≥150 mg/kg). Reproduction was affected in the same order (TRI EC₅₀ = 0.045 mg/kg, PYR EC₅₀ = 1.85 mg/kg, and AZO EC₅₀ = 93.10 mg/kg). Exposure to AZO and PYR showed a negative impact on hatching success with a significant increase in the number of unhatched cocoons. Prolonged hatching test was consequently carried out. As a result, a hatching delay was observed at lower AZO and PYR concentrations, while at higher concentrations hatching was completely stopped as the cocoons were no longer viable. Hence, hatching test enabled a discrimination between hatching delay and hatching impairment. Besides demonstrating the adverse effects of AZO, PYR, and TRI on the survival, reproduction, and hatching success of E. crypticus, the obtained results indicate the convenience of using several endpoints in reproduction tests. The usage of prolonged hatching tests and monitoring of hatching dynamics could fill the gap between standard reproduction tests and multigeneration tests and allow a better understanding of the adverse effects on reproduction.

Ecotoxicological effects of pyraclostrobin on tilapia (Oreochromis niloticus) via various exposure routes

Pyraclostrobin is a widely used and highly efficient fungicide that also has high toxicity to aquatic organisms, especially fish. Although some research has reported the toxic effects of pyraclostrobin on fish, the main toxic pathways of pyraclostrobin in fish remain unclear. The present study has integrated histopathological, biochemical and hematological techniques to reveal the main toxic pathways and mechanisms of pyraclostrobin under different exposure routes. Our results indicated that pyraclostrobin entered fish mainly through the gills. The highest accumulation of pyraclostrobin was observed in the gills and heart compared with accumulation in other tissues and gill tissue showed the most severe damage. Hypoxia symptoms (water jacking, tummy turning and cartwheel formation) in fish were observed throughout the experiment. Taken together, our results suggested that the gills are important target organs. The high pyraclostrobin toxicity to gills might be associated with oxidative damage to the gills, inducing alterations in ventilation frequency, oxygen-carrying substances in blood and disorders of energy metabolism. Our research facilitates a better understanding of the toxic mechanisms of pyraclostrobin in fish, which can promote the ecotoxicological research of agrochemicals on aquatic organisms.

Comparative toxicity of multiple exposure routes of pyraclostrobin in adult zebrafish (Danio rerio)

Pyraclostrobin, one of the most widely used fungicides globally, is highly toxic to aquatic organisms, which restricts its application in paddy fields. Most studies have focused on the molecular mechanism of pyraclostrobin toxicity; however, the exposure routes and target organs of pyraclostrobin in fish are poorly known. Here, we found that the lethal effects of aquatic exposure, head immersion, trunk immersion and oral exposure on the toxicity and accumulation of pyraclostrobin in adult zebrafish were different. The major pathway leading to pyraclostrobin accumulation, followed by high hazard to fish, was crossing over the gill rather than the intestine or skin. Additionally, serious histological abnormalities, mitochondrial dysfunction, energy deficiency and respiratory impairment occurred in the gills, while no overt change was observed in the heart and brain at the organic and cellular levels. This result suggested that the gill is the dominant portal and target organ of pyraclostrobin in fish, a fact that has been further verified by intravenous injection. The differences in the toxicity and translocation factor of crystalline and dissolved pyraclostrobin in fish demonstrated that reducing the concentration in the branchial environment is a vital direction for the future design of an effective toxicity regulation strategy to protect key sites from pyraclostrobin attack.

Bixafen causes cardiac toxicity in zebrafish (Danio rerio) embryos

Bixafen (BIX) is a succinate dehydrogenase inhibitor (SDHI)-class fungicide that is used to control crop diseases. However, data on the toxicity of BIX to zebrafish are limited. Here, zebrafish embryos were exposed to 0.1, 0.3, and 0.9 μM BIX. After BIX exposure, zebrafish embryos exhibited cardiac dysplasia and dysfunction, including pericardial edema, reduced heart rate, and drastically decreased erythrocytes in the cardiac area; the severity of these negative effects increased with BIX concentration and the duration of BIX exposure. In addition, the transcription levels of erythropoiesis-related genes decreased significantly in BIX-treated embryos, as compared to untreated control embryos. Similarly, compared with the control, key genes responsible for cardiac development (myh6, nkx2.5, and myh7) also exhibited dysregulated expression patterns in response to BIX treatment, suggesting that BIX might specifically affect cardiac development. Finally, cell apoptosis was induced in embryos after BIX treatment. In combination, our results suggested that exposure to BIX induced cardiac toxicity in zebrafish. These data will be valuable for future evaluations of the environmental risks of BIX.