Embryonic development and oxidative stress effects in the larvae and adult fish livers of zebrafish (Danio rerio) exposed to the strobilurin fungicides, kresoxim-methyl and pyraclostrobin

Toxicity potential of a pyraclostrobin-based fungicide in plant and green microalgae models

Pyraclostrobin-based fungicides play an effective role in controlling fungal diseases and are extensively used in agriculture. However, there is concern regarding the potential adverse effects attributed to exposure to these fungicides on non-target organisms and consequent influence exerted on ecosystem functioning. Thus, it is essential to conduct studies with model organisms to determine the impacts of these fungicides on different groups of living organisms. The aim of this study was to examine the ecotoxicity associated with exposure to commercial fungicides containing pyraclostrobin. The focus of the analysis involved germination and initial development of seedlings of 4 plant models (Lactuca sativa, Raphanus sativus, Pennisetum glaucum and Triticum aestivum), in addition to determining the population growth rate and total carbohydrate content in microalga Raphidocelis subcapitata. The fungicide pyraclostrobin adversely influenced growth and development of the tested plants, indicating a toxic effect. The fungicide exerted a significant impact on the initial development of seedlings of all model species examined with T. aestivum plants displaying the greatest susceptibility to pyraclostrobin. Plants of this species exhibited inhibitory effects on both aerial parts and roots when treated with a concentration of 4.75 mg/L pyraclostrobin. In addition, the green microalga R. subcapitata was also significantly affected by the fungicide, especially at relatively high concentrations as evidenced by a reduction in total carbohydrate content. This commercial fungicide demonstrated potential phytotoxicity for the tested plant models and was also considered toxic to the selected microalgae, indicating an ecotoxic effect that might affect other organisms in aquatic environments.

Ecological risks of high-ammonia environment with inhibited growth of Daphnia magna: Disturbed energy metabolism and oxidative stress

High ammonia pollution is a common problem in water bodies. However, research on the mechanisms underlying the toxic effects on organisms at different nutritional levels is still insufficient. Herein, based on the environmental concentration, the toxic effects of high ammonia pollution on Daphnia magna were investigated. Overall, the feeding and filtration rates of D. magna were significantly decreased by ammonia. Growth inhibition of D. magna by ammonia was confirmed by the decreased body length. After ammonia exposure, the metabolic status of D. magna changed, the correlation network weakened, and the correlations between metabolites were disrupted. Changes occurred in metabolites primarily involved in oxidative stress, fatty acid oxidation, tricarboxylic acid cycle, and protein digestion, absorption, and synthesis, which were validated through alterations in multiple biomarkers. In addition, mitochondrial function was evaluated and was found to inhibit mitochondrial activity, which was accompanied by a decreased marker of mitochondrial activity contents and ATPase activity. Thus, the results suggested that energy metabolism and oxidative stress were involved in ammonia-induced growth toxicity. This study provides new insights into the impact of ammonia on aquatic ecological health.

Pyraclostrobin induces developmental toxicity and cardiotoxicity through oxidative stress and inflammation in zebrafish embryos

Pyraclostrobin, a typical representative of strobilurin fungicides, is extensively used in agriculture to control fungi and is often detected in water bodies and food. However, the comprehensive toxicological molecular mechanism of pyraclostrobin requires further study. To assess the toxic effects and underlying mechanisms of pyraclostrobin on aquatic organisms, zebrafish embryos were exposed to pyraclostrobin (20, 40, and 60 μg/L) until 96 h post fertilization (hpf). These results indicated that exposure to pyraclostrobin induces morphological alterations, including spinal curvature, shortened body length, and smaller eyes. Furthermore, heart developmental malformations, such as pericardial edema and bradycardia, were observed. This indicated severe cardiotoxicity induced by pyraclostrobin in zebrafish embryos, which was confirmed by the dysregulation of genes related to heart development. Besides, our findings also demonstrated that pyraclostrobin enhanced the contents of reactive oxygen species (ROS) and malondialdehyde (MDA), up-regulated catalase (CAT) activity, but inhibited superoxide dismutase (SOD) activity. Subsequently, the NF-κb signaling pathway was further studied, and the results indicated that the up-regulation of tnf-α, tlr-4, and myd88 activated the NF-κb signaling pathway and up-regulated the relative expression level of pro-inflammatory cytokines, such as cc-chemokine, ifn-γ, and cxcl-clc. Collectively, this study revealed that pyraclostrobin exposure induces developmental toxicity and cardiotoxicity, which may result from a combination of oxidative stress and inflammatory responses. These findings provide a basis for continued evaluation of the effects and ecological risks of pyraclostrobin on the early development of aquatic organisms.

Synergistic toxic effects and mechanistic insights of beta-cypermethrin and pyraclostrobin exposure on hook snout carp (Opsariichthys bidens): A biochemical, transcriptional, and molecular approach

The extensive utilization of pesticides results in their frequent detection in aquatic environments, often as complex mixtures, posing risks to aquatic organisms. The hook snout carp (Opsariichthys bidens) serves as a valuable bioindicator for evaluating the impacts of environmental pollutants in aquatic ecosystems. However, few studies examined the toxic effects of pesticides on O.bidens, let alone the characterization of the combined effects resulting from their mixtures. This study aims to elucidate the toxic effects of beta-cypermethrin and pyraclostrobin on O.bidens, individually and in combination, focusing on biochemical, transcriptional, and molecular responses. By organizing and analyzing the toxicogenomic databases, both pesticides were identified as a contributor to processes such as apoptosis, oxidative stress, and inflammatory responses. The acute toxicity test revealed comparable acute toxicity of beta-cypermethrin and pyraclostrobin on O.bidens, with LC50 being 0.019 and 0.027 mg/L, respectively, whereas the LC50 decreased to 0.0057 and 0.0079 mg/L under the combined exposure, indicating potential synergistic effects. The activities of enzymes involved in oxidative stress and detoxification were significantly altered after exposure, with superoxide dismutase (SOD) and catalase (CAT) increasing, while malondialdehyde (MDA) levels decreased. The activity of CYP450s was significantly changed. Likewise, the expression levels of genes (mn-sod, p53, esr, il-8) associated with oxidative stress, apoptosis, endocrine and immune systems were significantly increased. Combined exposure to the pesticides significantly exacerbated the aforementioned biological processes in O.bidens. Furthermore, both pesticides can modify protein activity by binding to the surface of SOD molecules and altering protein conformation, contributing to the elevated enzyme activity. Through the investigation of the synergistic toxic effects of pesticides and molecular mechanisms in O.bidens, our findings highlight the importance of assessing the combined effects of pesticide mixtures in aquatic environments.

Comparative effects of different metals on the Japanese medaka embryos and larvae

Rapid evaluation of the toxicity of metals using fish embryo acute toxicity is facilitative to ecological risk assessment of aquatic organisms. However, this approach has seldom been utilized for the comparative study on the effects of different metals to fish. In this study, acute and sub-chronic tests were used to compare the toxicity of Se(IV) and Cd in the embryos and larvae of Japanese medaka (Oryzias latipes). The embryos with different levels of dechorionation and/or pre-exposure were also exposed to Se(IV) and Cd at various concentrations. The results showed that the LC50-144 h of Cd was 1.3-5.2 folds higher than that of Se(IV) for the embryos. In contrast, LC50-96 h of Se(IV) were 200-400 folds higher than that of Cd for the larvae. Meanwhile, dechorionated embryos were more sensitive to both Se and Cd than the intact embryos. At elevated concentrations, both Se and Cd caused mortality and deformity in the embryos and larvae. In addition, pre-exposure to Cd at the embryonic stages enhanced the resistance to Cd in the larvae. However, pre-exposure to Se(IV) at the embryonic stages did not affect the toxicity of Se(IV) to the larvae. This study has distinguished the nuance differences in effects between Se(IV) and Cd after acute and sub-chronic exposures with/without chorion. The approach might have a potential in the comparative toxicology of metals (or other pollutants) and in the assessment of their risks to aquatic ecosystems.

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.

Petanin Potentiated JNK Phosphorylation to Negatively Regulate the ERK/CREB/MITF Signaling Pathway for Anti-Melanogenesis in Zebrafish

Petanin, an acylated anthocyanin from the Solanaceae family, shows potential in tyrosinase inhibitory activity and anti-melanogenic effects; however, its mechanism remains unclear. Therefore, to investigate the underlying mechanism of petanin's anti-melanogenic effects, the enzyme activity, protein expression and mRNA transcription of melanogenic and related signaling pathways in zebrafish using network pharmacology, molecular docking and molecular dynamics simulation were combined for analysis. The results showed that petanin could inhibit tyrosinase activity and melanogenesis, change the distribution and arrangement of melanocytes and the structure of melanosomes, reduce the activities of catalase (CAT) and peroxidase (POD) and enhance the activity of glutathione reductase (GR). It also up-regulated JNK phosphorylation, inhibited ERK/RSK phosphorylation and down-regulated CREB/MITF-related protein expression and mRNA transcription. These results were consistent with the predictions provided through network pharmacology and molecular docking. Thus, petanin could inhibit the activity of tyrosinase and the expression of tyrosinase by inhibiting and negatively regulating the tyrosinase-related signaling pathway ERK/CREB/MITF through p-JNK. In conclusion, petanin is a good tyrosinase inhibitor and anti-melanin natural compound with significant market prospects in melanogenesis-related diseases and skin whitening cosmetics.

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.

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.

The research progress on the impact of antibiotics on the male reproductive system

Antibiotics are extensively utilized in the livestock and poultry industry and can accumulate in animals and the environment, leading to potential health risks for humans via food and water consumption. Research on antibiotic toxicity, particularly their impact as endocrine disruptors on the male reproductive system, is still in its nascent stages. This review highlights the toxic effect of antibiotics on the male reproductive system, detailing the common routes of exposure and the detrimental impact and mechanisms of various antibiotic classes. Additionally, it discusses the protective role of food-derived active substances against the reproductive toxicity induced by antibiotics. This review aims to raise awareness about the reproductive toxicity of antibiotics in males and to outline the challenges that must be addressed in future research.

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.

Adsorption of azoxystrobin and pyraclostrobin onto degradable and non-degradable microplastics: Performance and mechanism

Microplastics (MPs) exist after agricultural operations and thus present potential hazards to the environment and human health. However, the ecological risks posed by MPs carrying pesticides remain unclear. In this study, the adsorption and desorption behaviors of two pesticides, azoxystrobin and pyraclostrobin, on degradable and non-degradable MPs of poly(butylene adipate-co-terephthalate) (PBAT) and polyethylene (PE) were compared before and after UV aging. Additionally, the bioaccessibility of MPs carrying pesticides within a condition simulating gastrointestinal fluids was evaluated. The results showed that, after UV aging, the adsorption capacity of PBAT for pesticides decreased, while that of PE increased. Moreover, PBAT possessed higher adsorption ability towards both the pesticides due to its higher specific surface area, pore volume, contact angle, and lower crystallinity, as well as stronger van der Waals forces, electrostatic interactions, and hydrogen bonding indicated by theoretical calculation. Bioaccessibility experiments showed that azoxystrobin and pyraclostrobin had a higher risk of desorption from PBAT than PE, which is mainly dependent on the LogKow of pesticides according to the random forest analysis. In brief, the study highlights the potential risks of degradable MPs carrying pesticides to human health and the ecosystem, especially when compared to their non-degradable counterparts, manifesting that the ecological risk posed by degradable MPs should not be ignored.

Toxicological impact of strobilurin fungicides on human and environmental health: a literature review

Fungicides are specifically used for controlling fungal infections. Strobilurins, a class of fungicides originating from the mushroom Strobilurus tenacellus, act on the fungal mitochondrial respiratory chain, interrupting the ATP cycle and causing oxidative stress. Although strobilurins are little soluble in water, they have been detected in water samples (such as rainwater and drinking water), indoor dust, and sediments, and they can bioaccumulate in aquatic organisms. Strobilurins are usually absorbed orally and are mainly eliminated via the bile/fecal route and urine, but information about their metabolites is lacking. Strobilurins have low mammalian toxicity; however, they exert severe toxic effects on aquatic organisms. Mitochondrial dysfunction and oxidative stress are the main mechanisms related to the genotoxic damage elicited by toxic compounds, such as strobilurins. These mechanisms alter genes and cause other dysfunctions, including hormonal, cardiac, neurological, and immunological impairment. Despite limitations, we have been able to compile literature information about strobilurins. Many studies have dealt with their toxic effects, but further investigations are needed to clarify their cellular and underlying mechanisms, which will help to find ways to minimize the harmful effects of these compounds.

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.

Evidence of strobilurin fungicides and their metabolites in Dongjiang River ecosystem, southern China: Bioaccumulation and ecological risks

Despite the widespread application of strobilurin fungicides (SFs) in agriculture, little is known about their distribution and bioaccumulation in aquatic ecosystems. In this study, the concentrations of 12 SFs and two of their metabolites were determined in abiotic (water and sediment; n = 83) and biotic (plant, algae, zooplankton, and fish; n = 123) samples collected from a subtropical freshwater ecosystem, namely, Dongjiang River wetland, in southern China. Among the 12 SFs measured, azoxystrobin (AZ) was the major fungicide found in surface water (median: 2.20 ng/L) and sediment (0.064 ng/g dry wt.). Azoxystrobin acid (AZ-acid), a metabolite of AZ, was the major analyte in the plant samples and had a median concentration at 0.36 ng/g dry wt. In algae and zooplankton, (Z)-metominostrobin was the predominant fungicide and had median concentrations of 3.52 and 5.55 ng/g dry wt., respectively. In fish muscle, dimoxystrobin (DIMO) was the major SF and had a median concentration of 0.47 ng/g dry wt. The bioconcentration factor (BCF) values of AZ-acid, trifloxystrobin (TFS), and pyraclostrobin (PYR) in algae and zooplankton and AZ-acid, PYR, TFS, TFS-acid, picoxystrobin, and DIMO in fish muscle exceeded 1000 L/kg (algae, zooplankton, and fish concentrations were expressed on a dry weight basis), suggesting that these fungicides can accumulate in biota. A positive association between log BCFs of SFs in fish and logKow of SFs and a negative correlation between log BCFs and the log solubility index were observed. Additionally, the risk quotient (RQ) was calculated to evaluate the potential ecotoxicological risk of SFs to different aquatic organisms (algae, zooplankton, and fish). The PYR and DIMO concentrations at 19 sampling sites had RQ values >0.1, indicating moderate ecotoxicological risks to aquatic organisms. This study is the first to document the widespread occurrence of SFs and their metabolites in aquatic ecosystems and to elucidate the bioaccumulation potential of SFs in aquatic organisms.

The benefit of using in vitro bioassays to screen agricultural samples for oxidative stress: South Africa's case

Applied pesticides end up in non-target environments as complex mixtures. When bioavailable, these chemicals pose a threat to living organisms and can induce oxidative stress (OS). In this article, attention is paid to OS and the physiological role of the antioxidant defense system. South African and international literature was reviewed to provide extensive evidence of pesticide-induced OS in non-target organisms, in vivo and in vitro. Although in vitro approaches are used internationally, South African studies have only used in vivo methods. Considering ethical implications, the authors support the use of in vitro bioassays to screen environmental matrices for their OS potential. Since OS responses are initiated and measurable at lower cellular concentrations compared to other toxicity endpoints, in vitro OS bioassays could be used as an early warning sign for the presence of chemical mixtures in non-target environments. Areas of concern in the country could be identified and prioritized without using animal models. The authors conclude that it will be worthwhile for South Africa to include in vitro OS bioassays as part of a battery of tests to screen environmental matrices for biological effects. This will facilitate the development and implementation of biomonitoring programs to safeguard the South African environment.

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.

Captivating Colors, Crucial Roles: Astaxanthin's Antioxidant Impact on Fish Oxidative Stress and Reproductive Performance

Fish, constantly exposed to environmental stressors due to their aquatic habitat and high metabolic rates, are susceptible to oxidative stress. This review examines the interplay between oxidative stress and fish reproduction, emphasizing the potent antioxidant properties of astaxanthin. Our primary objective is to highlight astaxanthin's role in mitigating oxidative stress during critical reproductive stages, leading to improved gamete quality, ovary development, and hormone levels. We also explore its practical applications in aquaculture, including enhanced pigmentation and overall fish health. We conducted a comprehensive literature review, analyzing studies on astaxanthin's antioxidant properties and its impact on fish reproduction. Astaxanthin, a carotenoid pigment, effectively combats reactive oxygen species, inhibiting lipid peroxidation and maintaining membrane integrity. It significantly enhances reproductive success in fish and improves overall fish health in aquaculture settings. This review reveals astaxanthin's multifaceted benefits in fish health and reproduction, offering economic advantages in aquaculture. Future research should delve into species-specific responses, optimal dosages, and the long-term effects of astaxanthin supplementation to inform sustainable aquaculture strategies.

An integrated approach for evaluating the interactive effects between azoxystrobin and ochratoxin A: Pathway-based in vivo analyses

Azoxystrobin (AZO) is a broad-spectrum strobilurin fungicide widely used in agriculture. However, its use increases the possibility of co-occurrence with mycotoxins such as ochratoxin A (OTA), which poses a significant risk to human health. Therefore, it is imperative to prioritize the evaluation of the combined toxicity of these two compounds. To assess the combined effects of AZO and OTA, the response genes and phenotypes for AZO or OTA exposure were obtained by utilizing Comparative Toxicogenomics Database, and Database for Annotation, Visualization and Integrated Discovery was used for GO and KEGG pathway enrichment analysis. In addition, we provided in-vivo evidence that AZO and OTA, in isolation and combination, could disrupt a variety of biological processes, such as oxidative stress, inflammatory response, apoptosis and thyroid hormone regulation under environmentally relevant concentrations. Notably, our findings suggest that the combined exposure group exhibited greater toxicity, as evidenced by the expression of various markers associated with the aforementioned biological processes, compared to the individual exposure group, which presents potential targets for the underlying mechanisms of induced toxicity. This study provides a novel methodological approach for exploring the mechanism of combined toxicity of a fungicide and a mycotoxin, which can shed light for conducting risk assessment of foodborne toxins.

Evaluation of single and combined effects of mancozeb and metalaxyl on the transcriptional and biochemical response of zebrafish (Danio rerio)

Mancozeb and metalaxyl are fungicidal agents frequently used in combination to control fungi in crops that may affect non-target organisms when entering ecosystems. This study aims to evaluate the environmental effects of Mancozeb (MAN) and Metalaxyl (MET), alone and in combination, on zebrafish (Danio rerio) as an experimental model. The oxidative stress biomarkers and the transcription of genes involved in detoxification in zebrafish (Danio rerio) were assessed after co-exposure to MAN (0, 5.5, and 11 μg L^-1) and MET (0, 6.5, and 13 mg L^-1) for 21 days. Exposure to MAN and MET induced a significant increase in the expression of genes related to detoxification mechanisms (Ces2, Cyp1a, and Mt2). Although Mt1 gene expression increased in fish exposed to 11 μg L^-1 of MAN combined with 13 mg L^-1 of MET, Mt1 expression was down-regulated significantly in other experimental groups (p < 0.05). The combined exposure to both fungicides showed synergistic effects in the expression levels that are manifested mainly at the highest concentration. Although a significant (p < 0.05) increase in alkaline phosphatase (ALP) and transaminases (AST and ALT), catalase activities, the total antioxidant capacity, and malondialdehyde (MDA) contents in the hepatocytes of fish exposed to MAN and MET alone and in combination was detected, lactate dehydrogenase (LDH), gamma-glutamyl transferase (GGT) activities, and hepatic glycogen content decreased significantly (p < 0.05). Overall, these results emphasize that combined exposure to MET and MAN can synergistically affect the transcription of genes involved in detoxification (except Mt1 and Mt2) and biochemical indicators in zebrafish.

Predatory stink bug, Eocanthecona furcellata (Wolff) responses to oral exposure route of λ-cyhalothrin via sex-specific modulation manner

The toxic effects of insecticides on predatory arthropods have closely related to their exposure routes. However, little is known about the effects of insecticide on reproductive parameters when the route of exposure occurs at a trophic level via prey intake. We therefore conducted current studies assessing whether Eocanthecona furcellata adults would be affected by feeding with λ-cyhalothrin-contaminated prey. Reproductive parameters, i.e. prolonged premating and preoviposition durations, reduced number of egg batches and egg amount, disturbed ovarian development, and suppressed expression of reproductive related genes were observed in E. furcellata females by feeding with treated prey. Moreover, reduced survival rate and altered carbohydrate metabolism parameters were detected in male bugs. Biochemical parameters, including MDA content, the activities of three antioxidant enzymes and three detoxification enzymes exhibited sex-specific responses after oral-exposure to λ-cyhalothrin in E. furcellata. The results indicate that the insecticide affects the fitness and leads to impairing reproductive potential via sex-specific modulation manner in predator insects. Taken together, our results provide a comprehensive assessment about detrimental impacts of λ-cyhalothrin-exposure on predators via prey intake, as well as a solid basis for further research to protect the predators from hazardous impacts of insecticides.

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.

Abiotic transformation of kresoxim-methyl in aquatic environments: Structure elucidation of transformation products by LC-HRMS and toxicity assessment

In this study, abiotic transformation of an important strobilurin fungicide, kresoxim-methyl, was investigated under controlled laboratory conditions for the first time by studying its kinetics of hydrolysis and photolysis, degradation pathways and toxicity of possibly formed transformation products (TPs). The results indicated that kresoxim-methyl showed a fast degradation in pH9 solutions with DT₅₀ of 0.5 d but relatively stable under neutral or acidic environments in the dark. It was prone to photochemical reactions under simulated sunlight, and the photolysis behavior was easily affected by different natural substances such as humic acid (HA), Fe³⁺and NO₃^-which are ubiquitous in natural water, showing the complexity of degradation mechanisms and pathways of this chemical compound. The potential multiple photo-transformation pathways via photoisomerization, hydrolyzation of methyl ester, hydroxylation, cleavage of oxime ether and cleavage of benzyl ether were observed. 18 TPs generated from these transformations were structurally elucidated based on an integrated workflow combining suspect and nontarget screening by high resolution mass spectrum (HRMS), and two of them were confirmed with reference standards. Most of TPs, as far as we know, have never been described before. The in-silico toxicity assessment showed that some of TPs were still toxic or very toxic to aquatic organisms, although they exhibit lower aquatic toxicity compared to the parent compound. Therefore, the potential hazards of the TPs of kresoxim-methyl merits further evaluation.

Effect of florasulam on oxidative damage and apoptosis in larvae and adult zebrafish (Danio rerio)

Florasulam is widely used for weed control in wheat fields due to its high activity and low dosage. Previous studies on florasulam have focused on soil microbial and residue determination, however, its ecotoxicity to aquatic organisms is unclear. The toxicity of florasulam was evaluated in larvae (120 h) and adult (14 and 28 d) zebrafish. After florasulam (0.1 and 1 μg L^-1) exposure, reactive oxygen species levels in larvae and adult zebrafish significantly increased and antioxidant system was activated. Florasulam induced lipid peroxidation in larvae and adult zebrafish. Florasulam did not cause DNA damage to larvae but caused DNA damage to adult zebrafish. Changes in caspase 3/8/9 genes indicated that apoptosis was induced in larvae but inhibited in adult zebrafish. By calculating integrated biomarker response, caspase 3 and malondialdehyde could be used as early warning indicators of florasulam effect on larvae and adult zebrafish, respectively. The higher the exposure concentration, the greater the toxicity of florasulam to larvae and adult zebrafish. Increasing exposure time resulted in higher toxicity to adult zebrafish. Florasulam has different toxicity at larvae and adult zebrafish. In future studies to investigate florasulam toxicity to zebrafish, different zebrafish life stages (larvae and adult) need to be studied.

Mixture toxicity of pyraclostrobine and metiram to the zebrafish (Danio rerio) and its potential mechanism

The interplay between pesticides plays a critical role in ecotoxicology since these chemicals rarely emerge as single substances but rather in mixtures with other chemicals. In the present work, we purposed to clarify the combined toxic impacts of pyraclostrobine (PYR) and metiram (MET) on the zebrafish by using numerous indicators. Results exhibited that the 4-day LC₅₀ value of MET to fish embryos was 0.0025 mg a.i. L^-1, which was lower compared with PYR (0.019 mg a.i. L^-1). Combinations of PYR and MET presented a synergetic impact on fish embryos. Contents of POD, CYP450, and VTG were drastically increased in the plurality of the single and joint treatments relative to the baseline value. Three genes, including vtg1, crh, and il-8, related to the endocrine and immune systems, were also surprisingly up-regulated when fish were challenged by the individual and mixture pesticides compared with the baseline value. These results afforded valuable information on the latent toxicity mechanisms of co-exposure for PYR and MET in the early growth stage of fish. Moreover, our data also revealed that frequent application of these two pesticides might exert a potentially ecotoxicological hazard on aquatic ecosystems. Collectively, the present study provided valuable guidance for the risk evaluation of chemical combinations.

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.

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.

Comprehensive study of the effects of strobilurin-based fungicide formulations on Enchytraeus albidus

Excessive application of fungicides in crop fields can cause adverse effects on soil organisms and consequently affect soil properties. Existing knowledge on the effects of strobilurin fungicides has been primarily based on toxicity tests with active ingredients, while the effects of fungicide formulations remain unclear. Therefore, this work aims to provide new data on the effects of three commercial formulations of strobilurin fungicides on the soil organism Enchytraeus albidus. The tested fungicide formulations were Retengo® (pyraclostrobin-PYR), Zato WG 50® (trifloxystrobin-TRI) and Stroby WG® (kresoxim-methyl-KM). In laboratory experiments, multiple endpoints were considered at different time points. The results showed that PYR had the greatest impact on survival and reproduction (LC₅₀ = 7.57 mg_a.i.kg_soil^-1, EC₅₀ = 0.98 mg_a.i.kg_soil^-1), followed by TRI (LC₅₀ = 72.98 mg_a.i.kg_soil^-1, EC₅₀ = 16.93 mg_a.i.kg_soil^-1) and KM (LC₅₀ = 73.12 mg_a.i.kg_soil^-1, EC₅₀ ≥ 30 mg_a.i.kg_soil^-1). After 7 days of exposure, MXR activity was inhibited at the highest concentration of all fungicides tested (6 mg_PYRkg_soil^-1, 15 mg_TRIkg_soil^-1 and 30 mg_KMkg_soil^-1). Furthermore, oxidative stress (induction of SOD, CAT and GST) and lipid peroxidation (increase in MDA) were also observed. In addition, there was a decrease in total available energy after exposure to PYR and KM. Exposure to fungicides resulted in a shift in the proportions of carbohydrates, lipids, and proteins affecting the amount of available energy. In addition to the initial findings on the effects of strobilurin formulations on enchytraeids, the observed results suggest that multiple and long-term exposure to strobilurin formulations in the field could have negative consequences on enchytraeid populations.

Effects of BPZ, BPC, BPF, and BPS Exposure on Adult Zebrafish (Danio rerio): Accumulation, Oxidative Stress, and Gene Expression

As substitutes for bisphenol A (BPA), bisphenol analogs (BPs) have been found to cause endocrine disorders and induce toxic effects. The objective of this study was to evaluate the bioaccumulation and subacute toxicity of bisphenol Z (BPZ), bisphenol C (BPC), bisphenol F (BPF), and bisphenol S (BPS) to zebrafish. Five-month-old zebrafish were exposed to 1/100 LC₅₀, 1/50 LC₅₀, and 1/10 LC₅₀ of BPZ, BPC, BPF, and BPS for 13 days, respectively. Bioaccumulation, oxidative stress, and related mRNA expression in zebrafish tissues were measured on days 1, 7, and 13. After exposure, the four kinds of BPs all resulted in the accumulation of concentration and lipid peroxidation in zebrafish tissues to varying degrees. BPZ and BPC had the highest bioaccumulation level and had the greatest influence on malonic dialdehyde (MDA). In addition, the enzyme activities of superoxide dismutase (SOD), peroxidase (POD), glutathione peroxidase (GSH-PX), and the content of glutathione (GSH) in zebrafish tissues were also affected at different levels. However, the enzyme activities of SOD and POD were inactivated in zebrafish exposed to a high concentration of BPC. Further studies showed that BPs exposure down-regulated the transcription level of sod but up-regulated the relative expression levels of cat and gpx. The mRNA relative expression level of erα was not significantly changed, while the mRNA relative expression level of erβ₁ was significantly down-regulated except under BPS exposure. These results indicate that BPZ, BPC, and BPF significantly affect the expression level of the estrogen receptor (ER) in zebrafish tissues. Overall, the results suggest that exposure to waterborne BPs can cause severe oxidative stress and tissue damage in adult zebrafish that is not sufficient to kill them after 13 days of waterborne exposure. The toxicity of BPs to organisms, therefore, should be further analyzed and evaluated.

Toxicological differences of trifloxystrobin and kresoxim-methyl on zebrafish in various levels of exposure routes, organs, cells and biochemical indicators

Trifloxystrobin (TRI) and kresoxim-methyl (KRE), as quinone outside inhibitor fungicides (QoIs), have broad applications due to their effective activity against fungi. Excessive usages of agrochemicals trigger environmental risks, such as aquatic organisms (fish). Research performed in recent years has focused on the ecotoxicology of TRI and KRE in fish containing histologic morphology, enzyme activity, protein and gene expression under chronic toxicity conditions, whereas less is known about the underlying mechanisms of toxicity and differences between TRI and KRE in fish under acute toxicity conditions. In the present study, in comparison to different exposure routes [whole-body exposure (WBE), head exposure (HE), trunk exposure (TE), and Oral administration (OA)], the external substances TRI and KRE entered the fish body mainly via gill organs and led to fish toxicity. Furthermore, gill organs and gill cells were vulnerable to TRI and KRE exposure, which indicated that the gill is a vital impaired organ. The 96 h-LC₅₀ (sublethal concentration) value of KRE was 289.8 μg L^-1 (R² = 0.9855) with an approximate 10-fold difference in TRI toxicity. The cytotoxicity exposed to TRI was higher than that in KRE at the same concentration. The potential mechanisms of toxic differences could be various toxic effects in terms of MCIII (mitochondrial complex III) activity, ATP (Adenosine triphosphate) content, MA (mitochondrial activity), ROS (reactive oxygen species) levels, and cellular respiration. Furthermore, the disorder in MCIII activity was probably the main potential mechanisms of toxic differences. To some extent, this research provides not only new insight into the underlying toxic mechanism of TRI and KRE in fish but also a basis for the guidance of agrochemicals considering aquatic risks.

Joint toxic effects of phoxim and lambda-cyhalothrin on the small yellow croaker (Larimichthys polyactis)

Although pesticides commonly exist as combinations in real-life situations of the aquatic ecosystem, the impact of the toxicity of their mixtures has remained largely unclear. In this study, we investigated the combined effects of two neurotoxic pesticides, including one organophosphate insecticide phoxim (PHO) and one pyrethroid insecticide lambda-cyhalothrin (LCY), on the embryos of the small yellow croaker (Larimichthys polyactis), and their potential pathways. LCY exhibited higher toxicity relative to PHO, with a 72-h LC₅₀ value of 0.0074 mg a.i. L^-1, while the corresponding value for PHO was 0.12 mg a.i. L^-1. The mixture of PHO and LCY exerted a synergistic effect on the embryos of L. polyactis. The activities of antioxidant enzyme CAT and apoptotic enzyme caspase 3 were substantially changed in most single and combined exposure groups relative to the baseline value. Under both single and combined exposures, more significant changes were found in the mRNA expression of five genes, including the immunosuppression gene ngln2, the apoptosis gene P53, the endocrine system gene cyp19a1b, as well as neurodevelopment genes of ap and acp2, relative to the baseline value. Furthermore, the non-target metabolomic analysis demonstrated that hundreds of differential metabolites, including two bile acids (taurodeoxycholic acid and tauroursodeoxycholic acid), were significantly increased in the exposure groups. The bile acids were closely associated with the gut microbiota, and 16S rRNA sequencing results demonstrated dysfunction of the gut microbiota after exposure, especially in the combined exposure group. Our findings indicated that there might be a potential risk connected to the co-occurrence of these two pesticides in aquatic vertebrates. Consequently, future ecological risk assessments should incorporate synergistic mixtures because the current risk assessments do not consider them.

Mixture toxicity of cadmium and acetamiprid to the early life stages of zebrafish (Danio rerio)

Aquatic organisms are often exposed to contaminants that occur in the natural environment. Nevertheless, the toxic effects of chemical combinations on aquatic animals and their underlying toxic mechanisms for dealing with such exposures are still not fully understood. In this study, we investigated the combined effects of cadmium (Cd) and acetamiprid (ACE) on zebrafish (Danio rerio) using various endpoints. Cd exhibited a 96-h LC₅₀ value of 4.77 mg a.i. L^-1 against zebrafish embryos, which was lower than that of ACE (152.6 mg a.i. L^-1). In contrast, the 96-h LC₅₀ value of the mixture of Cd and ACE was 157.4 mg a.i. L^-1. The mixture of Cd and ACE had a synergetic effect on the organisms. The activities of T-SOD, POD, and CarE were significantly changed in most exposures compared with the control group. In addition, five genes (TRα, crh, Tnf, IL, and P53) involved in oxidative stress, cellular apoptosis, the immune system, and the endocrine system exhibited more remarkable changes when exposed to chemical mixtures relative to their individual counterparts, demonstrating variations in the cellular and mRNA expression levels induced by the mixture exposure of ACE and Cd during the embryonic development of zebrafish. Therefore, these results indicated that the combined pollution of ACE and Cd could be a potentially hazardous factor, and further investigation is necessary for the safety evaluation and application of ACE. Moreover, further investigation on the combined toxicities of various chemicals must be performed to determine the chemical mixtures with synergistic responses.

Improving survival, growth, feed utilization, antioxidant status, and fatty acids profile of European seabass, Dicentrarchus labrax, larvae fed silymarin, Silybum marianum, supplemented weaning diet

To sustain normal development, high survival, and rapid growth, marine fish larvae require a diet rich in polyunsaturated fatty acids, which could decrease the risk of reactive oxygen species accumulations. Consequently, a 60-day feeding experiment was conducted to determine the effect of silymarin (SM) supplementation in weaning diets on the growth performance, survival, antioxidant enzyme activities, and fatty acids profile of European seabass (Dicentrarchus labrax) larvae. Four isonitrogenous and isolipidic diets were investigated using SM at levels of 0, 200, 400, and 600 mg kg−1 (SM0.00, SM200, SM400, and SM600, respectively). The findings showed that, in a dose-dependent manner, increasing dietary levels of SM enhanced survival, growth, and feed utilization. In the SM600 group, the weight gain, survival, and feed conversion ratio (FCR) improved by 123.21, 11.66, and 38.72%, respectively, compared to the control group. The dose-response analysis demonstrated a strong positive correlation (R2=0.96) between SM levels and weight increase, and a strong negative correlation (R2=0.88) between SM levels and FCR. The antioxidant enzyme activities of larvae given SM-enriched diets were significantly greater than those of the control group. Compared to the control group, the CAT and SOD improved by 81.77 and 5.08 % in the SM600 group. In addition, the saturated fatty acid content reduced while the unsaturated fatty acid content increased, particularly in the SM600 group. The results indicate that supplementing the micro diet of European seabass larvae during weaning with SM at a dose of 600 mg kg-1 increases growth, survival, antioxidant status, and fatty acid profiles.

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.

Use of Zebrafish as a Model Organism to Study Oxidative Stress: A Review

Dioxygen is an integral part of every living organism, but its concentration varies from organ to organ. Production of metabolites from dioxygen may result in oxidative stress. Since oxidative stress has the potential to damage various biomolecules in the cell, therefore, it has presently become an active field of research. Oxidative stress has been studied in a wide range of model organisms from vertebrates to invertebrates, from rodents to piscine organisms, and from in vivo to in vitro models. But zebrafish (adults, larvae, or embryonic stage) emerged out to be the most promising vertebrate model organism to study oxidative stress because of its vast advantages (transparent embryo, cost-effectiveness, similarity to human genome, easy developmental processes, numerous offspring per spawning, and many more). This is evidenced by voluminous number of researches on oxidative stress in zebrafish exposed to chemicals, radiations, nanoparticles, pesticides, heavy metals, etc. On these backgrounds, this review attempts to highlight the potentiality of zebrafish as model of oxidative stress compared with other companion models. Several areas, from biomedical to environmental research, have been covered to explain it as a more convenient and reliable animal model for experimental research on oxidative mechanisms.

Sub-chronic ecotoxicity of triphenyl phosphate to earthworms (Eisenia fetida) in artificial soil: Oxidative stress and DNA damage

As a flame retardant, triphenyl phosphate (TPHP) is commonly added to various daily products. Due to its easy diffusion, TPHP pollution has become a global concern. Despite the wide focus on environmental risk, the sub-chronic ecotoxicity of TPHP in soil organisms remains unclear. In this study, the artificial soil exposure method was used to analyze the oxidative stress and DNA damage in earthworms with 0, 20, 40, 60 and 80 mg/kg TPHP treatments through the response of reactive oxygen species (ROS), antioxidant and detoxifying enzymes, malondialdehyde (MDA) and olive tail moment (OTM) at 7, 14, 21 and 28 days. Throughout the experimental period, the results showed that the ROS content in earthworms treated with 20, 40, 60 and 80 mg/kg TPHP treatments increased by 9.43-18.37 %, 6.07-25.73 %, 7.71-42.61 % and 8.22-46.70 %, respectively, compared to the control treatment. Meanwhile, the activities of antioxidant and detoxification enzymes in earthworms with all TPHP treatments were significantly activated after exposure for 7 and 14 days, and then inhibited at 21 and 28 days. Despite the protection of antioxidant enzymes and detoxification enzymes, MDA content in earthworms with the 20 mg/kg treatment still significantly increased at 7 and 14 days of exposure, as well as in the other three treatments. Compared to the control treatment, the obviously higher OTM values in earthworms with TPHP treatments possibly indicated a genotoxicity of TPHP in earthworms. Furthermore, the integrated biomarker response index (IBRv2) revealed that earthworms showed an obvious biochemical response TPHP-contaminated soil, which was strongly correlated with TPHP concentrations and exposure time. This study provides insights into the TPHP hazard in the soil environment and offers a reference to assess its environmental risk to soil ecosystems.

Toxicity Mitigation of Textile Dye Reactive Blue 4 by Hairy Roots of Helianthus annuus and Testing Its Effect in In Vivo Model Systems

An anthraquinone textile dye, Reactive Blue 4 (RB4), poses environmental health hazards. In this study, remediation of RB4 (30-110 ppm) was carried out by hairy roots (HRs). UV-visible spectroscopy and FTIR analysis showed that the dye undergoes decolourization followed by degradation. In addition, toxicity and safety analyses of the bioremediated dye were performed on Allium cepa and zebrafish embryos, which revealed lesser toxicity of the bioremediated dye as compared to untreated dye. For Allium cepa, the highest concentration, i.e., 110 ppm of the treated dye, showed less chromosomal aberrations with a mitotic index of 8.5 ± 0.5, closer to control. Two-fold decrease in mortality of zebrafish embryos was observed at the highest treated dye concentration indicating toxicity mitigation. A higher level of lipid peroxidation (LPO) was recorded in the zebrafish embryo when exposed to untreated dye, suggesting a possible role of oxidative stress-inducing mortality of embryos. Further, the level of LPO was significantly normalized along with the other antioxidant enzymes in embryos after dye bioremediation. At lower concentrations, mitigated samples displayed similar antioxidant activity comparable to control underlining the fact that the dye at lesser concentration can be more easily degraded than the dye at higher concentration.

A multiplex lateral flow immunochromatography assay for the quantitative detection of pyraclostrobin, myclobutanil, and kresoxim-methyl residues in wheat

We produced three monoclonal antibodies with high specificity and sensitivity, and developed a lateral flow immunochromatography assay (LFIA) for the qualitative and quantitative detection of pyraclostrobin (PYR), myclobutanil (MYC), and kresoxim-methyl (KRE) in wheat. In the qualitative analysis, the cut-off values of LFIA were 400, 200, and 800 ng/g for PYR, MYC, and KRE in wheat, respectively. Based on the results obtained from the membrane strip reader, we generated calibration curves for the quantitative analysis. PYR, MYC, and KRE monoclonal antibodies (mAbs) had half maximal inhibitory concentrations (IC₅₀) of 25.4, 17.7, and 94.6 ng/g, respectively, and limit of detection (LOD) of 2.5, 2.0, and 8.8 ng/g, respectively. The linear detection scopes were 5.6-116.5, 4.2-74.4, 23.4-383.3 ng/g for PYR, MYC, and KRE, respectively. The intra-assay recoveries ranged from 89.2% to 101.7%, and the coefficients of variation ranged from 4.6% to 6.5%. The inter-assay recoveries ranged from 88.7% to 102.7%, with the coefficients of variation ranged from 7.2% to 9.1%. Thus, our developed LFIA is suitable for the qualitative and quantitative detection of PYR, MYC, and KRE residues in wheat.

Growth Performance, Antioxidative Capacity, and Intestinal Histomorphology of Grey Mullet (Liza ramada)-Fed Dietary Zinc Nanoparticles

Zinc is one of the essential microelements involved in vital physiological and biological functions in the fish body. The study evaluated the growth performance, antioxidative capacity, and intestinal histomorphology of Grey Mullet (Liza ramada)-fed dietary zinc nanoparticles (ZnO-NPs) at 0, 10, 20, and 40 mg/kg for the first time. The final weight and specific growth rate (SGR) of Grey Mullet-fed dietary ZnO-NPs at 20 and 40 mg/kg were meaningfully enhanced (p < 0.05). Further, the weight gain (WG) was significantly higher in fish treated with ZnO-NPs than the control, and fish fed 20-40 mg/kg had the highest WG (p < 0.05). The feed conversion ratio (FCR) was meaningfully reduced in fish fed 20-40 mg ZnO-NPs/kg (p < 0.05). The histomorphology of the intestines revealed a significant improvement in villus height, villus width, and goblet cells by ZnO-NPs. The lysozyme activity, phagocytic activity, and phagocytic index showed higher levels in Grey Mullet-fed dietary ZnO-NPs at 20 mg/kg than fish fed 0, 10, and 40 mg/kg (p < 0.05). Superoxide dismutase (SOD) and catalase (CAT) were markedly improved in Grey Mullet treated with ZnO-NPs compared with the control, and the group of fish treated with 20 mg/kg had the highest SOD and CAT (p < 0.05). Glutathione peroxidase (GPx) was significantly higher in fish fed 20-40 mg/kg ZnO-NPs than fish fed 0-10 mg/kg and fish fed 40 mg ZnO-NPs/kg showing the highest GPx value (p < 0.05). The concentration of malondialdehyde was markedly lowered in Grey Mullet fed ZnO-NPs at varying levels (p < 0.05). Based on the overall results, the regression analysis suggests that ZnO-NPs can be included at 24.61-35.5 mg/kg for the best performances of Grey Mullet.

Toxicological impact of SARS-CoV-2 on the health of the neotropical fish, Poecilia reticulata

There have been significant impacts of the current COVID-19 pandemic on society including high health and economic costs. However, little is known about the potential ecological risks of this virus despite its presence in freshwater systems. In this study, we aimed to evaluate the exposure of Poecilia reticulata juveniles to two peptides derived from Spike protein of SARS-CoV-2, which was synthesized in the laboratory (named PSPD-2002 and PSPD-2003). For this, the animals were exposed for 35 days to the peptides at a concentration of 40 µg/L and different toxicity biomarkers were assessed. Our data indicated that the peptides were able to induce anxiety-like behavior in the open field test and increased acetylcholinesterase (AChE) activity. The biometric evaluation also revealed that the animals exposed to the peptides displayed alterations in the pattern of growth/development. Furthermore, the increased activity of superoxide dismutase (SOD) and catalase (CAT) enzymes were accompanied by increased levels of malondialdehyde (MDA), reactive oxygen species (ROS) and hydrogen peroxide (H2O2), which suggests a redox imbalance induced by SARS-CoV-2 spike protein peptides. Moreover, molecular docking analysis suggested a strong interaction of the peptides with the enzymes AChE, SOD and CAT, allowing us to infer that the observed effects are related to the direct action of the peptides on the functionality of these enzymes. Consequently, our study provided evidence that the presence of SARS-CoV-2 viral particles in the freshwater ecosystems offer a health risk to fish and other aquatic organisms.

Psychoactive drugs citalopram and mirtazapine caused oxidative stress and damage of feeding behavior in Daphnia magna

As the emerging contaminants, the environmental risks of drug-derived pollutants have attracted extensive attention. Citalopram (CTP) and mirtazapine (MTP) are commonly used as modern antidepressant drugs. Previous studies had proved that CTP and MTP entered the aquatic environment, but less reported the negative effects of the drugs on aquatic organisms. Herein, the effects on the feeding rate of Daphnia magna (D. magna) induced by psychotropic drugs CTP and MTP were investigated, which the possible mechanisms were analyzed with the oxidative stress and damage. Generally, the feeding rates of exposed D. magna under all concentrations of CTP and 1.03 mg/L of MTP were significantly decreased after exposure (p < 0.05 or p < 0.01). The inhibitory effect of CTP on the feeding rate of D. magna was time- and dose-dependent. The levels of reactive oxygen species (ROS) were particularly increased in D. magna after CTP and MTP exposure (p < 0.05 or p < 0.01). The level of antioxidant molecules glutathione S-transferase (GST) and the activity of scavenging enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) of D. magna were increased (p < 0.05 or p < 0.01). In consequence, the levels of malondialdehyde (MDA), protein carbonyl, and 8-hydroxydeoxyguanosine (8-OHdG) were increased (p < 0.05 or p < 0.01), which indicated oxidative damage caused by MTP and CTP, due to the imbalance of antioxidative stress system. These findings indicated that psychoactive drugs posed a high toxic threat to the aquatic organisms, and the aquatic environmental risks caused by using psychoactive drugs deserve more attention.

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 acute ammonia exposure and recovery on the antioxidant response and expression of genes in the Nrf2-Keap1 signaling pathway in the juvenile golden pompano (Trachinotus ovatus)

Continuous exposure to high levels of ammonia can cause oxidative damage to fish tissues and organs. To date, the mechanism by which juvenile golden pompano (Trachinotus ovatus) are poisoned by ammonia exposure has not been thoroughly elucidated. although the mechanisms of ammonia toxicity are not well described for the pompano, many other studies presented these effects to other fish species. So an overview would be given. First, an acute ammonia nitrogen toxicity experiment on juvenile golden pompano obtained a 96-h half-lethal concentration (96 h LC50) of 26.9 mg/L. In the ammonia exposure experiment, fish were sampled at 0 h, 6 h, 12 h, 24 h, 48 h, 72 h and 96 h after exposure to ammonia water (26.93 mg/L). The results showed that with the prolonged ammonia nitrogen exposure, plasma cortisol (COR), total cholesterol (TC), glutamic-pyruvic transaminase (ALT), glutamic oxalacetic transaminase (AST) and malonaldehyde (MDA) levels continued to rise, while glucose (GLU) levels first increased and later gradually decreased after 12 h. The activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) in the liver and the mRNA expression levels of antioxidant genes (SOD, CAT, and GPX) first increased and subsequently decreased with increasing exposure time. Through microscopic observation, it was found that the degree of liver damage increased with increasing stress time and was most serious at 96 h. In the post-poison recovery experiment, the fish exposed to ammonia were transferred to clean water, and samples were taken at 24 h, 48 h, 72 h and 96 h after recovery. The results showed that with the increasing recovery time, each index recovered to the initial level to varying degrees, but the recovery time of 96 h was not enough for the fish to return to the normal level. We also examined the regulation of the Nrf2-Keap1 signaling pathway by the molecular mechanism of the antioxidant defense system. The results of this analysis showed that there was a positive correlation between Nrf2 and liver antioxidant gene expression levels, while there was a negative correlation between Keap1 and liver antioxidant gene expression levels, which may be observed because Nrf2 plays a key role in inducing antioxidant genes, and Keap1 may hinder the response to Nrf2. These results may provide a deeper and more comprehensive understanding of the impact of ammonia exposure on fish and help to provide a foundation for managing the healthy reproduction of juvenile 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.

Pyraclostrobin induced AMPK/mTOR pathways mediated autophagy in RAW264.7 macrophages

Pyraclostrobin(PCT) is a highly effective and broad-spectrum strobilurin fungicide. The mode action of PCT is inhibiting mitochondrial respiration. With the widespread use of PCT in preventing and controlling crop diseases, its potential safety risks to mammals have gradually attracted attention. This paper focuses on the cytotoxicity of PCT and its molecular mechanism, RAW264.7 macrophages were selected as a research model and conducted systematic toxicology studies in vitro, including MTT assay, colony formation assay, alkaline comet assay, fluorescent staining, ATP assay and Western blotting. The results revealed that PCT decreased viability and inhibited the proliferation of RAW264.7 cells in a concentration- dependent manner. Interestingly, PCT induced DNA damage, the resulting autophagosome, the accumulation of Beclin-1, the reduction of p62, the translocation and the formation of LC3-II. Furthermore, the results showed that PCT-induced the production of excessive ROS, leading to mitochondrial permeability transition pore (mPTP) opening, ATP depletion, and the elimination of mitochondria by autophagy. Furthermore, PCT treatment group significantly enhanced the phosphorylation level of AMPK, decreased the mTOR and p70s6k phosphorylation levels and activated the AMPK/mTOR signaling pathway in RAW264.7 cells. In conclusion, these results showed that PCT induced autophagy in the RAW264.7 cells might potentially have risks to mammal safety.

Molecular mechanisms of developmental toxicities of azoxystrobin and pyraclostrobin toward zebrafish (Danio rerio) embryos: Visualization of abnormal development using two transgenic lines

Azoxystrobin (AZ) and pyraclostrobin (PY) are strobilurin fungicides that inhibit fungal mitochondrial respiration. In this study, a representative model, zebrafish (Danio rerio), was used as a test species for acute and developmental toxicity. Survival and malformation rates were observed only PY-treated embryos, with an LC₅₀ value of 77.75 ppb accompanied by a dramatic decrease in hatching rate, while AZ did not show great mortality. Morphological changes were observed in PY-treated embryos with the occurrence of pericadial edema at 25 ppb. A delay in growth was observed after treatment with pyraclostrobin at 50 ppb. Use of genetically engineered Tg(cmlc:EGFP) allowed fluorescence observation during heart development. PY interfered with normal heart development via upregulation of the nppa gene responsible for the expression of natriuretic peptides. Heart function was dramatically reduced as indicated by reduced heart rates. Increased expression of the nppa gene was also seen in AZ-treated embryos. The expression level of cyp24a1 was also up-regulated, while ugt1a1 and sult1st6 were down-regulated after treatment of zebrafish embryos with AZ or PY. Overall, strobilurin fungicides might inhibit normal heart formation and function within the range of concentrations tested.

Polydatin Beneficial Effects in Zebrafish Larvae Undergoing Multiple Stress Types

Polydatin is a polyphenol, whose beneficial properties, including anti-inflammatory and antioxidant activity, have been largely demonstrated. At the same time, copper has an important role in the correct organism homeostasis and alteration of its concentration can induce oxidative stress. In this study, the efficacy of polydatin to counteract the stress induced by CuSO₄ exposure or by caudal fin amputation was investigated in zebrafish larvae. The study revealed that polydatin can reduced the stress induced by a 2 h exposure to 10 µM CuSO₄ by lowering the levels of il1b and cxcl8b.1 and reducing neutrophils migration in the head and along the lateral line. Similarly, polydatin administration reduced the number of neutrophils in the area of fin cut. In addition, polydatin upregulates the expression of sod1 mRNA and CAT activity, both involved in the antioxidant response. Most of the results obtained in this study support the working hypothesis that polydatin administration can modulate stress response and its action is more effective in mitigating the effects rather than in preventing chemical damages.