Embryonic toxicity of epoxiconazole exposure to the early life stage of zebrafish

Mechanistic insights into the parental co-exposure of T-2 toxin and epoxiconazole on the F1 generation of zebrafish (Danio rerio)

Mycotoxins and pesticides frequently coexist in agricultural commodities on a global scale. The potential transgenerational consequences induced by these substances pose a significant threat to human health. However, there is a lack of data concerning the effects of co-contamination by these chemicals in the F1 generation following parental exposure. This investigation delved into the mixture effects of T-2 toxin (T-2) and epoxiconazole (EPO) on the offspring of zebrafish (Danio rerio). The findings revealed that exposure across generations to a combination of T-2 and EPO resulted in toxicity in the larvae of the F1 generation. This was demonstrated by a significant increase in the levels or activities of malondialdehyde (MDA), thyroxine (T4), Caspase3, and cas9, along with a decrease in the levels of cyp19a, ERα, and ERβ. These outcomes suggested that cross-generational exposure to T-2 and EPO in D. rerio disrupted oxidative balance, induced cell apoptosis, and affected the endocrine system. Moreover, these effects were magnified when the F1 generation was continuously exposed to these compounds. Notably, these adverse effects could persist in subsequent generations without additional exposure. This study underscored the potential dangers associated with the simultaneous presence of T-2 and EPO on the development of fish offspring and the resulting environmental hazards to aquatic ecosystems. These findings emphasized the significant health risks posed by cross-generational exposure and highlighted the need for additional legislative measures to address these concerns.

Epoxiconazole disturbed metabolic balance and gut microbiota homeostasis in juvenile zebrafish

Epoxiconazole (EPX) is a broad-spectrum fungicide extensively used in agricultural pest control. Emerging evidence suggests that EPX can adversely affect different endpoints in non-target organisms. Here, the toxicity of EPX was assessed using earlier developmental stage of zebrafish as a model to investigate its effects on metabolism and intestinal microbiota after 21 days of exposure. Our findings indicated that EPX exposure resulted in physiological alterations in juvenile zebrafish, including increase in triglycerides (TG), total cholesterol (TC), low-density lipoprotein (LDL), and glycose (Glu). Nile red staining demonstrated enhanced lipid accumulation in juvenile, accompanied by a marked upregulation in the expression of genes associated with TG synthesis. Moreover, EPX led to alterations in amino acids and carnitines levels in 21 dpf (days post fertilization) zebrafish. We also observed that EPX disrupted intestinal barrier function in juvenile zebrafish, manifested by decreasing mucus secretion and changing in genes related to tight junctions. Moreover, for a more comprehensive analysis of the intestinal microbiota in 21 dpf zebrafish, the intestine tissues were dissected under a microscope for 16S rRNA sequencing analysis. The results revealed that EPX altered the structure and abundance of intestinal microflora in zebrafish, including decreased alpha diversity indices and shifted in bacteria at phylum and genus levels. Notably, the correlation analysis demonstrated strong associations between alterations in various pathogenic bacterial genera and levels of amino acids and carnitines. Overall, these findings confirm that the fungicide EPX promotes metabolic disorders and alterations in the intestinal micro-environment in 21 dpf zebrafish, shedding light on the toxicologic effects of chemicals to aquatic organisms during the development stage.

Absorption, distribution, metabolism, and elimination of epoxiconazole enantiomers in lizards (Eremias argus)

Epoxiconazole (EPX) is a world widely used chiral triazole fungicide in the agriculture field. The excessive application of this triazole may cause damage to lizards. However, limited information is known about the toxicokinetics of EPX on lizards. Our study aimed to investigate the enantioselective absorption, distribution, metabolism, and elimination (ADME) of EPX in lizards following low and high dose exposure (10 and 100 mg kg-1 bodyweitht (bw)). The results demonstrated that (+)-EPX was easier absorbed than (-)-EPX in lizard plasma. Both (+)-EPX and (-)-EPX were detected in the liver, gonad, kidney, skin, brain, and intestine, with (+)-EPX preferentially distributed in these tissues. The elimination of (-)-EPX was faster than that of (+)-EPX in lizard liver and kidney in the high dose groups. Chiral conversion was found between EPX enantiomers in lizard skin. Simultaneously, five metabolites including M2, M4, M10, M18 and M19 were detected in lizard liver and kidney after EPX enantiomers exposure. The relative concentrations of M2, M4, and M10 were higher in the liver and kidney of (-)-EPX groups than those produced from (+)-EPX groups. The metabolic enzymes CYP3A4 and SULT1A1 primarily mediated enantioselective metabolism of EPX. The conclusions drawn from this study significantly enhance our understanding of the enantioselective behaviors of chiral triazole fungicides in reptiles, offering essential guidance for assessing the risks associated with different enantiomers of triazole fungicides.

Epoxiconazole altered hepatic metabolism in adult zebrafish based on transcriptomic analysis

Epoxiconazole (EPX) is a triazole fungicide, which has been widely used in pest control of cereal crops. However, its extensive use has led to concerning levels of residue in water bodies, posing substantial risks to aquatic life. In this study, we characterized the toxicological effects of EPX on 6-month-old male and female zebrafish at 70 and 700 μg/L, respectively. The results revealed that EPX exposure markedly increased both body length and weight in zebrafish of both sexes, consequently elevating their condition factor. Besides, EPX exposure resulted in notable alterations in hepatic histopathology. These changes included loosened hepatocyte structure, ballooning degeneration, nucleolysis, and disappearance of cell line, with male zebrafish exhibiting more severe damage. High concentration of EPX also significantly increased hepatic lipid accumulation in male zebrafish, as well as increased hepatic triglyceride (TG) levels. Correspondingly, there was a notable alteration in the transcription of genes including cyp51, hmgcr, and PPAR-γ, which associated with cholesterol and lipid metabolism. Interestingly, with the hepatic transcriptomic analysis, high concentration of EPX produced 195 upregulated and 107 downregulated differential expression genes. Both KEGG and GO analyses identified significant enrichment of these genes in lipid and amino acid metabolism pathways. Notably, some key genes involved in the steroid synthesis pathway were marked upregulated. In addition, molecular docking study confirmed that EPX could bind CYP51 protein well (△G = -7.7 kcal/mol). Taken together, these findings demonstrated the multiple toxic effects of EPX on adult zebrafish.

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.

Multi-omics and gut microbiome: Unveiling the pathogenic mechanisms of early-life pesticide exposure

The extensive application of pesticides in agricultural production has raised significant concerns about its impact on human health. Different pesticides, including fungicides, insecticides, and herbicides, cause environmental pollution and health problems for non-target organisms. Infants and young children are so vulnerable to the harmful effects of pesticide exposure that early-life exposure to pesticides deserves focused attention. Recent research lays emphasis on understanding the mechanism between negative health impacts and early-life exposure to various pesticides. Studies have explored the impacts of exposure to these pesticides on model organisms (zebrafish, rats, and mice), as well as the mechanism of negative health effects, based on advanced methodologies like gut microbiota and multi-omics. These methodologies help comprehend the pathogenic mechanisms associated with early-life pesticide exposure. In addition to presenting health problems stemming from early-life exposure to pesticides and their pathogenic mechanisms, this review proposes expectations for future research. These proposals include focusing on identifying biomarkers that indicate early-life pesticide exposure, investigating transgenerational effects, and seeking effective treatments for diseases arising from such exposure. This review emphasizes how to understand the pathogenic mechanisms of early-life pesticide exposure through gut microbiota and multi-omics, as well as the adverse health effects of such exposure.

The occurrence of typical psychotropic drugs in the aquatic environments and their potential toxicity to aquatic organisms - A review

Psychotropic drugs (PDs) and their bioactive metabolites often persist in aquatic environments due to their typical physical properties, which made them resistant to removal by traditional wastewater treatment plants (WWTPs). Consequently, such drugs and/or their metabolites are frequently detected in both aquatic environments and organisms. Even at low concentrations, these drugs can exhibit toxic effects on non-target organisms including bony fish (zebrafish (Danio rerio) and fathead minnows) and bivalves (freshwater mussels and clams). This narrative review focuses on the quintessential representatives of three different categories of PDs-antiepileptics, antidepressants, and antipsychotics. The data regarding their concentrations occurring in the environment, patterns of distribution, the degree of enrichment in various tissues of aquatic organisms, and the toxicological effects on them are summarized. The toxicological assessments of these drugs included the evaluation of their effects on the reproductive, embryonic development, oxidative stress-related, neurobehavioral, and genetic functions in various experimental models. However, the mechanisms underlying the toxicity of PDs to aquatic organisms and their potential health risks to humans remain unclear. Most studies have focused on the effects caused by acute short-term exposure due to limitations in the experimental conditions, thus making it necessary to investigate the chronic toxic effects at concentrations that are in coherence with those occurring in the environment. Additionally, this review aims to raise awareness and stimulate further research efforts by highlighting the gaps in the understanding of the mechanisms behind PD-induced toxicity and potential health risks. Ultimately, the study underscores the importance of developing advanced remediation methods for the removal of PDs in WWTPs and encourages a broader discussion on mitigating their environmental impacts.

Developmental toxicity of the emerging contaminant cyclophosphamide and the integrated biomarker response (IBRv2) in zebrafish

The safety of cyclophosphamide (CP) in the early developmental stages is not studied yet; it is important to study the responses at these stages because they might have relevance to CP-administered humans. We studied the developmental toxicity of CP by analysing physiological, morphological, and oxidative stress, neurotransmission enzymes, gene expression and histological endpoints in zebrafish embryos/larvae. The study lasted for 120 hpf at environmentally relevant concentrations of CP. No visible alterations were noticed in the control group. Delayed hatching, slow heart rate, yolk sac oedema, pericardial oedema, morphological deformities, the incompetence of oxidative stress biomarkers, excessive generation of ROS, apoptosis, inhibition of neurotransmitters and histopathological anomalies were observed in CP-treated groups. These alterations were found to be concentration- and duration-dependent effects for physiological and morphological endpoints, whereas concentration-dependent effects were antioxidants, ROS, apoptosis and histological endpoints. Biomarkers and gene expression were standardised using the integrated biomarker response-IBRv2 index. The IBRv2 index showed a concentration-dependent behaviour. A non-lethal developmental and teratogenic effect was observed in CP-treated zebrafish embryos/larvae at the studied concentrations. The studied biomarkers are sensitive, and the responses are interrelated; thus, their responses are useful to assess veiled and unseen hazards of pharmaceuticals.

Characterization of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD)-induced cardiotoxicity in larval zebrafish (Danio rerio)

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) is a type of p-phenylenediamine (PPD), which is widely used in the manufacture of rubber tires owing to its excellent antiozonant properties. In this study, the developmental cardiotoxicity of 6PPD was evaluated in zebrafish larvae, and the LC50 was approximately 737 μg/L for the larvae at 96 h post fertilization (hpf). In the 6PPD treatment of 100 μg/L, the accumulation concentrations of 6PPD were up to 2658 ng/g in zebrafish larvae, and 6PPD induced significant oxidative stress and cell apoptosis in the early developmental stages of zebrafish. Transcriptome analysis showed that 6PPD exposure could potentially cause cardiotoxicity in larval zebrafish by affecting the transcription of the genes related to the calcium signal pathway and cardiac muscle contraction. The genes related to calcium signaling pathway (slc8a2b, cacna1ab, cacna1da, and pln) were verified by qRT-PCR, which were significantly downregulated in larval zebrafish after exposing to 100 μg/L of 6PPD. Simultaneously, the mRNA levels of the genes related to cardiac functions (myl7, sox9, bmp10, and myh71) also respond accordingly. H&E staining and heart morphology investigation indicated that cardiac malformation occurred in zebrafish larvae exposed to 100 μg/L of 6PPD. Furthermore, the phenotypic observation of transgenic Tg (myl7: EGFP) zebrafish also confirmed that 100 μg/L of 6PPD exposure could change the distance of atria and ventricles of the heart and inhibit some key genes (cacnb3a, ATP2a1l, ryr1b) related to cardiac function in larval zebrafish. These results revealed the toxic effects of 6PPD on the cardiac system of zebrafish larvae.

Systematic evaluation of the toxicological effects of deltamethrin exposure in zebrafish larvae

Deltamethrin (DM) is a widely used pesticide and has been generally detected in aquatic systems. To systematically investigate the toxic effects, zebrafish embryos were treated with various concentrations of DM for 120h. The LC₅₀ was determined to be 102 μg L^-1. Lethal concentrations of DM induced severe morphological defects in the surviving individuals. Under non-lethal concentrations, DM suppressed the development of neurons in the larvae, which was associated with the reduction in locomotor activity. DM exposure induced cardiovascular toxicity, including suppressed growth of blood vessels and enhanced heart rates. DM also disrupted the development of bones in the larvae. Moreover, liver degeneration, apoptosis and oxidative stress were observed in the larvae treated with DM. Correspondingly, the transcriptional levels of the genes related to the toxic effects were altered by DM. In conclusion, the results obtained in this study provided evidence that DM showed multiple toxic effects on aquatic organisms.

Effects of 2-ethylhexyl diphenyl phosphate exposure on the glucolipid metabolism and cardiac developmental toxicity in larval zebrafish based on transcriptomic analysis

2-Ethylhexyl diphenyl phosphate (EHDPP) is an organophosphorus type of flame retardant. It is mainly used as a flame-retardant plasticizer in the production of flexible polyvinyl chloride. EHDPP is widely present in environment, particularly in aquatic environment. In this study, we reported that EHDPP exposure significantly affected glucose and lipid metabolism in zebrafish larvae, which was reflected by changes in the transcription of relevant genes and decreased levels of glucose, pyruvate, and triglycerides. In addition, the transcriptomic analysis revealed that the differentially expressed genes could enrich various endpoints in zebrafish larvae. Interestingly, EHDPP exposure could not only change the transcription of genes related to glucolipid metabolism but also cause cardiotoxicity by affecting the transcription of genes related to calcium signaling pathways in zebrafish larvae. To support these findings, we confirmed that these genes involved in cardiac morphology and development were significantly upregulated in zebrafish larvae after EHDPP exposure. More importantly, the distance and overlapping area of the atrium and ventricle were also changed in the EHDPP-exposed zebrafish larvae of transgenic Tg (myl7: EGFP). Overall, our study revealed that EHDPP exposure could affect various endpoints related to glucolipid metabolism and cardiac development in the early developmental stages of zebrafish.

Impacts of co-exposure to zearalenone and trifloxystrobin on the enzymatic activity and gene expression in zebrafish

Although humans and animals are usually exposed to combinations of toxic substances, little is known about the interactive toxicity of mycotoxins and farm chemicals. Therefore, we can not precisely evaluate the health risks of combined exposure. In the present work, using different approaches, we examined the toxic impacts of zearalenone and trifloxystrobin on zebrafish (Danio rerio). Our findings showed that the lethal toxicity of zearalenone to embryonic fish with a 10-day LC₅₀ of 0.59 mg L^-1 was lower than trifloxystrobin (0.037 mg L^-1). Besides, the mixture of zearalenone and trifloxystrobin triggered acute synergetic toxicity to embryonic fish. Moreover, the contents of CAT, CYP450, and VTG were distinctly altered in most single and combined exposures. Transcriptional levels of 23 genes involved in the oxidative response, apoptosis, immune, and endocrine systems were determined. Our results implied that eight genes (cas9, apaf-1, bcl-2, il-8, trb, vtg1, erβ1, and tg) displayed greater changes when exposed to the mixture of zearalenone and trifloxystrobin compared with the corresponding individual chemicals. Our findings indicated that performing the risk assessment based on the combined impact rather than the individual dosage response of these chemicals was more accurate. Nevertheless, further investigations are still necessary to reveal the modes of action of mycotoxin and pesticide combinations and alleviate their effects on human health.

An Exploratory Study of the Metabolite Profiling from Pesticides Exposed Workers

Pesticides constitute a category of chemical products intended specifically for the control and mitigation of pests. With their constant increase in use, the risk to human health and the environment has increased proportionally due to occupational and environmental exposure to these compounds. The use of these chemicals is associated with several toxic effects related to acute and chronic toxicity, such as infertility, hormonal disorders and cancer. The present work aimed to study the metabolic profile of individuals occupationally exposed to pesticides, using a metabolomics tool to identify potential new biomarkers. Metabolomics analysis was carried out on plasma and urine samples from individuals exposed and non-exposed occupationally, using liquid chromatography coupled with mass spectrometry (UPLC-MS). Non-targeted metabolomics analysis, using principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) or partial least squares discriminant orthogonal analysis (OPLS-DA), demonstrated good separation of the samples and identified 21 discriminating metabolites in plasma and 17 in urine. The analysis of the ROC curve indicated the compounds with the greatest potential for biomarkers. Comprehensive analysis of the metabolic pathways influenced by exposure to pesticides revealed alterations, mainly in lipid and amino acid metabolism. This study indicates that the use of metabolomics provides important information about complex biological responses.

Oral Exposure to Epoxiconazole Disturbed the Gut Micro-Environment and Metabolic Profiling in Male Mice

Epoxiconazole (EPX), a triazole fungicide, is widely used in agriculture to control pests and diseases. High residual and occupational exposure to EPX increases health risks, and evidence of potential harm to mammals remains to be added. In the present study, 6-week-old male mice were exposed to 10 and 50 mg/kg bw EPX for 28 days. The results showed that EPX significantly increased the liver weights. EPX also decreased the mucus secretion of the colon and altered intestinal barrier function in mice including a reduced expression of some genes (Muc2, meprinβ, tjp1). Moreover, EPX altered the composition and abundance of gut microbiota in the colon of mice. The alpha diversity indices (Shannon, Simpson) in the gut microbiota increased after exposure to EPX for 28 days. Interestingly, EPX increased the ratio of Firmicutes to Bacteroides and the abundance of other harmful bacteria including Helicobacter and Alistipes. Based on the untargeted metabolomic analysis, it was found that EPX altered the metabolic profiles of the liver in mice. KEGG analysis of differential metabolites revealed that EPX disrupted the pathway related to glycolipid metabolism, and the mRNA levels of related genes were also confirmed. In addition, the correlation analysis showed that the most altered harmful bacteria were associated with some significantly altered metabolites. The findings highlight that EPX exposure changed the micro-environment and lipid metabolism disturbance. These results also suggest that the potential toxicity of triazole fungicides to mammals cannot be ignored.

Combined toxicity of acetamiprid and cadmium to larval zebrafish (Danio rerio) based on metabolomic analysis

Emerging contaminants, such as neonicotinoid pesticide acetamiprid (Ace), are frequently detected in the water environment, which can interact with existing heavy metal cadmium (Cd) to produce unpredicted influence. Limited studies have evaluated the effects of multiple pollutant exposures on aquatic animals. Here, we characterized the joint toxicity of Ace and Cd exposure to zebrafish (Danio rerio). The results revealed that Cd and its combined exposure with Ace had an inhibitory effect on the growth of larval zebrafish and induced morphological defects. Combined exposure to high doses of Ace and Cd could significantly reduce the levels of TG, glucose, and pyruvate in larval zebrafish. Untargeted metabolomics revealed that Cd treatment (285) produced more differentially expressed metabolites (DEMs) than Ace treatment (115), and combined treatment produced the most DEMs (294). The KEGG pathway enrichment analysis showed that they could disrupt riboflavin metabolism, amino acid metabolism, and glycolipid metabolism in the larvae of D. rerio. ELISA showed that VB2, FMN, and FAD levels were significantly increased. In addition, gene expression analysis exhibited that the mRNA levels of essential genes related to glycolipid metabolism were substantially affected, such as PK, PEPckc, PPAR-α, and FABP6. Furthermore, targeted amino acid metabolomics confirmed that both single exposure to Cd and combined exposure to Ace and Cd altered the levels of amino acids in larvae, including ALA, ARG, MET, PRO, TYR, VAL, GLY, ORN, and PHE. Taken together, exposure to Ace and Cd, alone or in combination, exerted harmful effects on the individual development, riboflavin metabolism, glycolipid metabolism, and amino acid metabolism disorder of D. rerio. These findings highlighted that more attention should be paid to the compound toxicity of chemical mixtures to aquatic organisms.

Stereoselective accumulation and biotransformation of chiral fungicide epoxiconazole and oxidative stress, detoxification, and endogenous metabolic disturbance in earthworm (Eisenia foetida)

>80 % of applied pesticides in agriculture will enter the soil and be exposed to soil animals. Little is known about the stereoselective metabolic effects of epoxiconazole (EPO) on soil animals. In this study, EPO-mediated stereoselective enrichment, biotransformation, oxidative stress, detoxification, and global metabolic profiles in earthworms were investigated by exposure to EPO and its enantiomers at 1 mg/kg and 10 mg/kg doses. Preferential enrichment of (-)-EPO was observed, and the five transformation products (TPs) exhibited the chemically specific stereoselective accumulation with inconsistent configurations. Biochemical markers related to reactive oxygen species (ROS) and detoxification (·OH^- content, SOD, CAT, GST, and CYP450 enzymes) showed a significant stereoselective activation overall at the low-level exposure (p-value <0.05). Based on untargeted metabolomic analysis, the steroid biosynthesis and ROS-related biotransformation, glutathione metabolism, TCA cycle, amino acid metabolism, purine and pyrimidine metabolism of earthworms were significantly interfered with by EPO and its enantiomer exposure. More pronounced stereoselectivity was observed at the level of the global metabolic profile, while comparable levels of metabolic perturbations were identified at the individual metabolite level. This study provides novel insights into the stereoselective effects of the chiral fungicide EPO, and valuable evidence for soil environmental risk assessments.

A mechanistic investigation about hepatoxic effects of borneol using zebrafish

Except for clinical value, borneol is routinely used in food and cosmetics with seldom safety evaluation. To investigate its hepatoxicity, we exposed 3 dpf (days post fertilization) larval zebrafish to borneol at a gradient of concentrations (200-500 μM) for 3 days. Herein, our results revealed that high doses of borneol (300-500 μM) caused liver size decrease or lateral lobe absence. Borneol also seriously disturbed the hepatic protein metabolism presented with the increased activity of alanine aminotransferase (ALT) and lipid metabolism shown with the increased level of triglycerides (TG) and total cholesterol (TC). The lipid accumulation (oil red staining) was detected as well. Additionally, significant upregulation of genes was detected that related to oxidative stress, lipid anabolism, endoplasmic reticulum stress (ERS), and autophagy. Conversely, the lipid metabolism-related genes were markedly downregulated. Moreover, the changes in the superoxide dismutase activity and the level of glutathione and malondialdehyde raised the likelihood of lipid peroxidation. The outcomes indicated the involvement of oxidative stress, ERS, lipid metabolism, and autophagy in borneol-induced lipid metabolic disorder and hepatic injury. This study will provide a more comprehensive understanding of borneol hepatoxicity and the theoretical basis for the safe use of this compound.

Bromuconazole exposure induces cardiotoxicity and lipid transport disorder in larval zebrafish

Bromuconazole (BRO), as one of the typical triazole fungicides, has not been reported on its effects on aquatic organisms. In this study, zebrafish embryos were used as experimental objects to evaluate the toxicity of BRO. In the acute embryo toxicity test, it was observed that the heart rate and growing development were affected by BRO in a concentration-dependent manner, and the half-lethal concentration (LC50) of BRO at 96 h post-fertilization (hpf) was about 11.83 mg/L. Then, low concentrations of BRO (50 ng/L, 0.075 mg/L, 0.3 mg/L, 1.2 mg/L), which were set according to the LC50 and environmental related concentrations, were used to analyze the toxic effects on the different endpoints in larval zebrafish. Interestingly, the transcriptomic analysis found that most different expressed genes (DEGs) could be focused on the pathways of lipid metabolism, myocardial function, glycometabolism, indicating that heart function and lipid metabolism in larval zebrafish were disrupted by BRO. For supporting this idea, we re-exposed the transgenic zebrafish and WT zebrafish embryos, proved that BRO caused damage to heart development and lipid transport on morphological and genetic level, which was consistent with transcriptomic results. In addition, BRO exposure caused oxidative damage in the larvae. Taken together, BRO exposure could affect the myocardial contraction function and lipid transport in larval zebrafish, accompanied by disturbances in the level of oxidative stress, which was of great significance for improving the biotoxicological information of BRO.

Adsorption behavior of azole fungicides on polystyrene and polyethylene microplastics

Agricultural plastic films and triazole fungicides are widely used in agricultural production process. Exposure to natural environment, agricultural plastic films will degrade into micron plastic particles, which will adsorb pesticide molecules and may affect their toxicity, biological activity and persistence. The long-term coexistence of microplastics (MPs) and triazole fungicides will bring potential harms to the agricultural ecological environment. Therefore, two kinds of triazole fungicides flusilazole (FLU) and epoxiconazole (EPO) were selected as cases and the adsorption behaviors of them on polystyrene and polyethylene were investigated. A series of factors which could affect the adsorption behavior were evaluated. Specifically, the particle size of MPs could affect its adsorption capacity, and the smaller the particle size, the stronger the adsorption capacity. Moreover, with the increase of pH value from 6.0 to 9.0, the adsorption capacity of MPs to target compounds gradually increased. The effect of ionic strength was evaluated by NaCl, and 0.05% of NaCl was beneficial to the adsorption process, while the continuous increase of NaCl concentration inhibited the adsorption. Oxalic acid and humic acid decreased the adsorption capacity of flusilazole on PE by 15.99-32.00% and PS by 35.02-48.67%, respectively. In addition, compared with the single pesticide system, the adsorption capacity of MPs for flusilazole and epoxiconazole in the binary pesticides system decreased by 36.13-37.93% and 44.36-51.35%, respectively, indicating that competitive adsorption occurred between the two pesticides. Meanwhile, the adsorption process was evaluated by adsorption kinetics and adsorption isotherms and were consistent with pseudo-second-order kinetic model and Freundlich isotherm model, respectively. Finally, several characterization analyses were conducted to investigated the adsorption mechanism, and hydrogen, halogen bonding and hydrophobic interaction proved to play an important role. The study on the adsorption behavior and mechanism of pesticide on MPs was the basis of assessing the risk of joint exposure.

Scopoletin Induced Metabolomic Profile Disturbances in Zebrafish Embryos

Scopoletin, a typical example of a coumarin compound, exists in several Artemisia species and other plant genera. However, the systemic metabolic effects induced by scopoletin remain unclear. In the present study, we evaluated the metabolic profiles in scopoletin-exposed zebrafish embryos using UHPLC-Q-Obitrap-HRMS combined with multivariate analysis. Compared with the control group, 33 metabolites in scopoletin group were significantly upregulated, while 27 metabolites were significantly downregulated. Importantly, scopoletin exposure affected metabolites mainly involved in phosphonate and phosphinate metabolism, vitamin B6 metabolism, histidine metabolism, sphingolipid metabolism, and folate biosynthesis. These results suggested that scopoletin exposure to zebrafish embryos exhibited marked metabolic disturbance. This study provides a perspective of metabolic impacts and the underlying mechanism associated with scopoletin exposure.

Transcriptomic and targeted metabolomic analysis revealed the toxic effects of prochloraz on larval zebrafish

Prochloraz (PCZ), an imidazole fungicide, has been extensively used in horticulture and agriculture to protect against pests and diseases. To investigate the potential toxicity of PCZ on aquatic organisms, larval zebrafish, as a model, were exposed to a series of concentrations (0, 20, 100, and 500 μg/L) of PCZ for 7 days. With transcriptomic analysis, we found that exposure to high dose PCZ could produce 76 downregulated and 345 upregulated differential expression genes (DEGs). Bioinformatics analysis revealed that most of the DEGs were characterized in the pathways of glycolipid metabolism, amino acid metabolism and oxidative stress in larval zebrafish. Targeted metabolomic analysis was conducted to verify the effects of PCZ on the levels of acyl-carnitines and some amino acids in larval zebrafish. In addition, biochemical indicators related to glycolipid metabolism were affected obviously, manifested as elevated triglyceride (TG) levels and decreased glucose (Glu) levels in whole larvae. The expression levels of genes associated with glycolipid metabolism were affected in larvae after exposure to PCZ (PK, GK, PEPckc, SREBP, ACO). Interestingly, we further confirmed that PCZ could induce oxidative stress by the changing enzyme activities (T-GSH, GSSG) and upregulating several related genes levels in larval zebrafish. Generally, our results revealed that the endpoints related to glycolipid metabolism, amino acid metabolism and oxidative stress were influenced by PCZ in larval zebrafish.

Catechin from green tea had the potential to decrease the chlorpyrifos induced oxidative stress in larval zebrafish (Danio rerio)

Catechin is a biological compound in green tea (Camellia sinesis), which has anti-oxidant, anti-cancer, anti-apoptotic, anti-inflammatory, and attenuated effects in different experimental models. Chlorpyrifos (CPF), a broad-spectrum organophosphate insecticide, has resulted in oxidative stress, mitochondrial dysfunction, and apoptosis in zebrafish. The goal of this study is to assess whether catechin can alleviate CPF-induced oxidative damage and apoptosis in the early developmental stage of zebrafish. According to the results, we observed that 200 μg/L CPF exposure could induce oxidative stress, ROS production and changing the antioxidant-related enzymes and genes in larval zebrafish. Interestingly, catechin had the potential to reduce the oxidative damage and cell apoptosis caused by CPF exposure in larval zebrafish at different endpoints. Especially, catechin could promote the contents of GSH and activity of GST in zebrafish larvae injured by CPF, suggesting that catechin could repair oxidative damage at a certain degree by regulating the activities and gene transcription of some key enzymes related to GSH pathway in zebrafish. In addition, at transcriptional levels, a high concentration of catechin exposure reduced the expression genes of Mn-SOD, Cat, gst, and GPX induced by CPF in larval zebrafish. These genes mainly reflected the degree of oxidative damage of zebrafish, which was basically consistent with the enzyme activity. Catechin also could reduce the transcription of p53 and bax, which are tightly related to the apoptosis induced by CPF in zebrafish larvae. The expression of genes was consistent with ROS production, which proved that catechin could alleviate the apoptosis induced by CPF. This study discovered that catechin had some antioxidant effects in aquatic animals to reduce the toxicity caused by pesticides and offered the scientific basis for the utilization and development of catechin.

Developmental toxicity of fenbuconazole in zebrafish: effects on mitochondrial respiration and locomotor behavior

Triazole fungicides are used to control the disease of cereal crops but may also cause adverse effects on non-target organisms. There is a lack of toxicity data for some triazoles such as fenbuconazole in aquatic organisms. This research was conducted to evaluate the toxicity of fenbuconazole at environmentally relevant concentrations with attention on the mitochondria, antioxidant system, and locomotor activity in zebrafish. Zebrafish were exposed to one concentration of 5, 50, 200 or 500ng/L fenbuconazole for 96h. There was no effect on survival nor percentage of fish hatched, but exposure to 200 and 500ng/L fenbuconazole resulted in malformation and hypoactivity in zebrafish. Oxygen consumption rates (OCR) of embryos were measured to determine if the fungicide impaired mitochondrial respiration. Exposure to 500ng/L fenbuconazole reduced basal OCR and oligomycin-induced ATP linked respiration in exposed fish. Fenbuconazole reduced mitochondrial membrane potential and reduced the activities of mitochondrial Complex II and III. Transcript levels of both sdhc and cyc1, each related to Complex II and III, were also altered in expression by fenbuconazole exposure, consistent with mitochondrial dysfunction in embryos. Fenbuconazole activated the antioxidant system, based upon both transcriptional and enzymatic data in zebrafish. Consistent with mitochondrial impairment, molecular docking confirmed a strong binding capacity of the fungicide at the Q_i site of Complex III, revealing this complex is susceptible to fenbuconazole. This study reveals potential toxicity pathways related to fenbuconazole exposure in aquatic organisms; such data can improve risk assessments for triazole fungicides.

Different biodegradation potential and the impacted soil functions of epoxiconazole in two soils

Epoxiconazole is an effective pesticide to control Fusarium head blight (FHB), and the application will increase. To investigate the ecotoxicity of epoxiconazole to soil microbiome, we carried out an indoor experiment in which soils from two main regions of wheat production in China (Nanjing and Anyang) were treated with epoxiconazole (0, 0.0625, 0.625, or 6.25 mg kg^-1) and incubated for 90 days. Under epoxiconazole stress, for bacteria and fungi, the abundance was increased and the diversity and community were impacted. In Anyang soil, the half-life of epoxiconazole was short with more increased species (linear discriminant analysis effect size biomarkers) and more increased xenobiotics biodegradation pathways in epoxiconazole treatments. The increased species mostly due to high abundance in initial state and more positive connections of the species. Co-occurrences revealed that epoxiconazole tightened bacterial connection, and increased positive correlations in Anyang soil. The N transformation was influenced with increased nifH and amoA; and the contents of NH₄⁺-N and NO₃^--N were also increased. The functions of C, S, and manganese metabolisms were also impacted by epoxiconazole. This work expands our understanding about epoxiconazole degradation and help us to properly assess the risk of epoxiconazole in soil.

Insights into the effects of difenoconazole on the livers in male mice at the biochemical and transcriptomic levels

Difenoconazole (DFZ) is a broad-spectrum triazole fungicide, that is extensively used in agriculture. Studies have shown that residues of DFZ and other fungicides have toxic effects on nontarget organisms. However, its hepatoxicity in mammals remains unclear. Here, we characterized the toxic hepatic effects in male C57BL/6 mice exposed to 30 and 100 mg/kg bw DFZ for 14 and 56 days, respectively. The results revealed that DFZ could increase the relative liver weights, however, the relative fat and spleen weights decreased. More importantly, DFZ exposure changed the hepatic morphology and induced hepatic oxidative stress. Gene expression analysis suggested that DFZ could induce a glycolipid metabolism disorder. Moreover, hepatic transcriptomic analysis revealed the effects of DFZ exposure on the transcriptional levels of various genes, and enrichment analysis of differentially expressed genes (DEGs) showed that energy metabolism and immune-associated pathways were mainly affected. We validated the results from transcriptomic analysis and found that some key genes related to energy metabolism were affected. In addition, flow cytometry showed that the CD3+/CD4+ and CD3+ /CD8+ levels declined in the spleen of mice. Taken together, these findings combined with transcriptome analysis highlighted that DFZ caused different endpoints in the liver, which could provide more evidence for investigating the toxic effects of DFZ in mammals.

Lentinan Impairs the Early Development of Zebrafish Embryos, Possibly by Disrupting Glucose and Lipid Metabolism

LNT is the major biologically active substance extracted from Lentinus edodes (L. edodes). Although functional and pharmacological studies have demonstrated that LNT has multiple benefits for animals and humans, the safety assessment is far from sufficient. To evaluate the potential safety risk, larval zebrafish were continuously exposed to varying concentrations of LNT for 120 h. The 96 h LC50 of LNT was determined to be 1228 μg/mL, and morphological defects including short body length, reduced eye and swim bladder sizes and yolk sac edema were observed. In addition, LNT exposure significantly reduced the blood flow velocity and locomotor activity of larval zebrafish. The biochemical parameters were also affected, showing reduced glucose, triglyceride and cholesterol levels in zebrafish larvae after being exposed to LNT. Correspondingly, the genes involved in glucose and lipid metabolism were disrupted. In conclusion, the present study demonstrates the adverse potential of high concentrations of LNT on the development of zebrafish larvae in the early life stage.

Revisiting pesticide pollution: The case of fluorinated pesticides

Fluorinated pesticides acquired a significant market share in the agrochemical sector due to the surge of new fluoroorganic ingredients approved in the last two decades. This growing trend has not been accompanied by a comprehensive scientific and regulatory framework entailing all their potential negative impacts for the environment, especially when considering the hazardous properties that may result from the incorporation of fluorine into organic molecules. This review aims to address the safe/hazardous dichotomy associated with fluorinated pesticides by providing an updated outlook on their relevancy in the agrochemical sector and how it leads to their role as environmental pollutants. Specifically, the environmental fate and distribution of these pesticides in the ecosystems is discussed, while also analysing their potential to act as toxic substances for non-target organisms.