Propiconazole induces abnormal behavior and oxidative stress in zebrafish

A novel framework for industrial pesticide effluent assessment: Integrating chemical screening, multi-endpoint responses and literature-based validation

Industrial pesticide effluents pose substantial risks to aquatic ecosystems, yet comprehensive understanding of their toxicological impacts remains limited. This study presents an integrated approach to evaluate the ecological risks of pesticide manufacturing effluents through chemical screening and multi-endpoints biological responses. Using zebrafish embryos as a model organism, we demonstrated that effluent discharge point (EDP) sample induced 100 % mortality, while diluted samples exhibited significant developmental toxicity, cardiovascular injury, immunosuppression, and behavioral alterations. Non-targeted metabolomics analysis revealed the molecular mechanisms underlying these toxic responses. Through chemical screening and targeted quantification, we identified three predominant azole fungicides - propiconazole (2.11 μg/L), hexaconazole (13.3 μg/L), and tebuconazole (18.66 μg/L) - that exhibited synergistic toxicity. Notably, our innovative meta-analysis framework based on literature data validated the toxicological profiles of detected compounds, providing an efficient alternative to conventional bioassays. This study establishes a comprehensive framework for assessing industrial effluent toxicity and demonstrates the value of integrating chemical analysis with biological responses for environmental risk assessment.

Bioavailability assessment of propiconazole to Limnobium laevigatum and zebrafish (Danio rerio) in aquatic microcosms

Residues of the triazole fungicide propiconazole (PCZ) in the environment can easily enter aquatic ecosystems through various pathways and accumulate in sediments, thus threatening ecosystem stability. The method of using passive sampling techniques to measure the freely dissolved concentration (Cfree) of pollutants in aquatic environments for assessing their bioavailability has been widely utilized in environmental risk assessments. This study employs oleic acid-embedded cellulose acetate membrane (OECAM) as a tool to determine the Cfree of PCZ in water. By establishing sediment spiking concentrations of 0.1 and 0.5 mg/kg in an aquatic microcosm, the distribution and bioaccumulation of PCZ in zebrafish (Danio rerio) and the aquatic plant Limnobium laevigatum (L. laevigatum) were examined over a 7-day period. During the experimental period, the concentrations of PCZ in the water for the 0.1 mg/kg and 0.5 mg/kg treatment groups remained approximately 0.9 μg/L and 10.0 μg/L, respectively. After 7 days, the PCZ content in the sediments decreased by 22.74% and 14.94%, respectively. In both zebrafish and L. laevigatum, the concentration of PCZ initially increased and then gradually stabilized, with both species exhibiting moderate accumulation ability for PCZ. The bioconcentration factor (BCF) for zebrafish in the 0.1 mg/kg and 0.5 mg/kg treatment groups ranged from 9.25 to 13.96 and 7.84-16.05, respectively, while those for L. laevigatum ranged from 28.17 to 31.40 and 23.01-36.11, respectively. By the end of the 7-day experiment, the total PCZ content in both treatment groups decreased by an average of 17.51%. Among them, L. laevigatum contributed significantly, highlighting its potential in accelerating the removal of PCZ from aquatic ecosystems.

Sub-chronic exposure of hexaconazole may induce metabolic and neuropathic diseases: The evidence from gut microbiota

The high-frequency detection and long persistence of hexaconazole (Hex) in agricultural products and environment poses potential risk to non-targeted organisms which should pay special attention to. Intestinal flora plays an important role in host health by prevention the occurrence of various diseases. Therefore, in this study, the disturbance of Hex on intestinal function and flora in rats had been studied at environmental related concentrations to evaluate the potential risk of Hex. Our results showed that Hex exposure induced serious oxidative stress and inflammation in intestinal tract. Meanwhile, it notably decreased the tight connectivity in colonic cell leading to the dysfunction of intestinal barrier. Moreover, 16sRNA gene sequencing showed that Hex exposure significantly disturbed the composition and structures of gut microbiota by decrease beneficial bacteria and increase pathogenic bacteria. Further, the metabolites and SCFAs that related to neuropathic and metabolic diseases in colonic contents were also significantly affected by Hex exposure. The pathways of membrane transport, replication and repair, lipid metabolism, and neurodegenerative diseases had been seriously interfered. The obtained results referred that Hex exposure may pose potential risk to metabolic system causing obesity, metabolic syndrome, and cardiovascular as well as nervous system inducing Parkinson's diseases, Alzheimer's diseases, and depression. Our study provided a new sight to study the mechanisms of Hex induced toxicity effects from the aspect of gut microbiota which could help for prevention the risk induced by Hex.

Ecotoxicological impact of succinate dehydrogenase inhibitor (SDHI) fungicides on non-targeted organisms: a review

As the global population continues to grow, the use of pesticides to increase food production is projected to escalate. Pesticides are critical in plant protection, offering a powerful defense against fungal diseases such as apple scab, leaf spot, sclerotinia rot, damping off, sheath blight, and root rot, which threaten crops like cereals, corn, cotton, soybean, sugarcane, tuberous vegetables, and ornamentals. Succinate Dehydrogenase Inhibitor (SDHI) fungicides represent a novel class essential for controlling fungal pathogens and bolstering food security. However, the impact of SDHIs on non-target organisms, including freshwater and terrestrial invertebrates, crustaceans, and oligochaetes, remains insufficiently understood. Empirical studies indicate that SDHIs can induce mortality, mitochondrial dysfunction, oxidative stress, and developmental delays in non-target organims. Additionally, the environmental persistence of these compounds raises concerns about their potential for ecological disruption. The effects of SDHIs on pollinating species and the possible transgenerational transmission of harmful effects warrant further investigation. Comprehensive transcriptomic analyses are necessary to elucidate the molecular disturbances and adverse outcome pathways triggered by SDHIs. Furthermore, there are emerging concerns about the endocrine-disrupting potential of SDHIs in aquatic organisms. For the first time, this review aims to synthesize existing knowledge on the ecotoxicological impacts of SDHIs on non-target organisms and identify critical research directions to address the ecological challenges posed by their use.

Effective adaptation of flight muscles to tebuconazole-induced oxidative stress in honey bees

The widespread and excessive agricultural use of azole fungicide tebuconazole poses a major threat to pollinator species including honey bee colonies as highlighted by recent studies. This issue is of growing importance, due to the intensification of modern agriculture and the increasing amount of the applied chemicals, serving as a major and recent problem from both an ecotoxicological and an agricultural point of view. The present study aims to detect the effects of acute sublethal tebuconazole exposure focusing on the redox homeostasis of honey bee flight muscles. The results show that the redox homeostasis, especially the glutathione system, of the exposed animals is severely impaired by the treatment, but flight muscles are able to successfully counteract the detrimental effects by the effective activation of protective processes. This efficient adaptation may have led to overcompensation processes eventually resulting in lower hydrogen peroxide and malondialdehyde concentrations after exposure. It could also be assumed that tebuconazole has a non-monotonic dose-response curve similarly to many other substances with endocrine-disrupting activity concerning parameters such as superoxide dismutase activity or total antioxidant capacity. These findings shed light on the detrimental impact of tebuconazole on the redox balance of honey bee flight muscles, also highlighting, that unlike other organs such as the brain, they may effectively adapt to acute tebuconazole exposure.

Toxicological risk assessment of triadimenol for human exposure, broiler health, and food safety

Triadimenol, a widely used triazole fungicide, leaves residues that pose risks to broiler health, food safety, and human health. Current studies focus on lab animals, leaving limited data regarding its impact on non-target organisms in agricultural ecosystems. Moreover, the doses in current studies often exceed typical agricultural pollution levels of triadimenol. Therefore, this study evaluates the toxic effects of triadimenol by exposing broilers to different concentrations (0.05-20 mg/kg) in their feed for 42 days, assessing growth performance, organ index, hematological parameters, histopathology, jejunum morphology, and tissue residues. The results show that triadimenol contamination at 0.05-20 mg/kg in feed does not significantly affect broiler growth performance. However, the significant changes in hematological parameters suggest the potential hematological toxicity of triadimenol in broilers. Triadimenol at 1 mg/kg or higher induces hepatotoxic and nephrotoxic effects, and significantly alters kidney organ index and histopathology in broilers. Additionally, when the triadimenol contamination level in feed exceeds 1 mg/kg, the residues in edible tissues of broilers exceed the limits set by the EU and China. Overall, our study indicates that even low-dose exposure to triadimenol poses potential risks, highlighting the need for strict regulation of its use in agriculture to protect food safety and human health.

Pyridaben inhibits cell cycle progression and delays early embryonic development in zebrafish (Danio rerio)

Pyridaben is a broad-spectrum, contact-killing acaricide that can be used to control a variety of harmful food and plant mites. Pyridaben displays cardiotoxicity and liver toxicity toward fish, but the effects on fish embryonic development have not been characterized. We exposed early zebrafish embryos to 20, 30, and 40 μg/L concentrations of pyridaben. The exposure caused developmental abnormalities, including delayed embryonic shield formation, yolk sac resorption, decreases in body length, reduced pigmentation, and delays in hatching. Pyridaben caused a significant increase in the transcription level of the endoderm marker foxa2, but the transcription levels of the ectoderm development marker foxb1a and the mesoderm development marker snaila were not significantly altered. The transcription levels of the genes SOX17 in early embryos were significantly reduced. After exposure to pyridaben, catalase (CAT) activity and glutathione (GSH) content were increased, and cyclin D1, that is involved in early embryonic development, was abnormally expressed. This study shows that pyridaben causes anomalous development in zebrafish embryos by interfering with the cell cycle order of early embryonic development and inducing excessive oxidative stress. Colivelin, an agonist of the STAT3 signaling pathway, acted as a salvage drug to restore the cell cycle order during embryonic development following exposure to pyridaben. Thus, the toxic effects may be caused by pyridaben's regulation of the STAT3 signaling pathway.

The Fungicide Ipconazole Can Activate Mediators of Cellular Damage in Rat Brain Regions

This study aimed to investigate the toxicity of the fungicide ipconazole on oxidative status, cell death and inflammasome complex activation in the hypothalamus, cerebral cortex, striatum and hippocampus of rats. Female albino rats were randomly divided into a control group and four groups treated with ipconazole at doses of 1, 5, 10 and 20 mg/kg b.w., administered for six days. Ipconazole significantly increased MDA and ROS levels in all brain regions studied, while reducing catalase enzyme activity. The molecular expression of cell death-related genes (AKT1, APAF1, BNIP3, CASP3 and BAX) and the inflammasome complex (CASP1, IL1β, IL6, NLRP3, NFĸB and TNFα) was also assessed, showing increased expression in at least one brain region. The findings demonstrate that ipconazole induces central nervous system toxicity in mammals, highlighting its potential role as a risk factor in the development of neurodegenerative disorders in individuals exposed to this contaminant.

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.

Enzymatic and transcriptional level changes induced by the co-presence of lead and procymidone in hook snout carp (Opsariichthys bidens)

Understanding the interactions between different environmental pollutants is necessary in ecotoxicology since environmental contaminants never appear as single components but rather in combination with other substances. Heavy metals and pesticides are commonly detected in the environment, but the characterization of their mixture toxicity has been inadequately explored. This research aimed to elucidate the mixture impacts of the heavy metal lead (Pb) and the pesticide procymidone (PCM) on the hook snout carp (Opsariichthys bidens) using an array of biomarkers. The data showed that Pb and PCM possessed almost equivalent acute toxicity to the animals, with 4-days LC50 values of 120.9 and 85.15 mg L-1, respectively. Combinations of Pb and PCM generated acute synergistic effects on O. bidens. The contents of malondialdehyde (MDA), antioxidative (SOD), apoptotic (caspase-9), and detoxifying enzymes glutathione S-transferase (GST) and cytochrome P450 (CYP450) significantly changed after most of the mixture exposures compared with the baseline level and the corresponding individual exposures. This suggests the induction of oxidative stress, cell damage, and detoxification dysfunction. The expressions of eight genes (mn-sod, cu-sod, p53, cas3, erβ1, esr, ap, and klf2α) associated with oxidative stress, cell apoptosis, immune response, and hormonal functions exhibited pronounced changes when challenged with the mixture compared to the individual treatments. This indicates the occurrence of immune dysregulation and endocrine disorder. These findings provide an overall understanding of fish upon the challenge of sublethal toxicity between Pb and PCM and can be adopted to evaluate the complicated toxic mechanisms in aquatic vertebrates when exposed to heavy metal and pesticide mixtures. Additionally, these results might guide environmental regulation tactics to protect the population of aquatic vertebrates in natural ecosystems.

Single and joint toxicity of azoxystrobin and cyproconazole to Prochilodus lineatus: Bioconcentration and biochemical responses

Fungicides are widely used across the world to protect crops and their presence in freshwater systems is increasing. However, the evaluation of their potential impacts on non-target organisms is in the minority of studies related to pesticides. In the current research, the single and joint toxicity of azoxystrobin (AZX) and cyproconazole (CYP) was investigated in juvenile fish Prochilodus lineatus. In particular, we evaluated bioconcentration and biochemical responses following a short-term exposure to environmentally relevant concentrations of the fungicides (alone and in mixture). We also determined interactions between the biological responses when the two compounds were used in mixture. Our results demonstrate that AZX and CYP pose a risk to native freshwater fish by causing deleterious effects. Both compounds, alone and in mixture, bioaccumulated in P. lineatus and triggered neurotoxicity and changes in oxidative stress biomarkers in several organs. Moreover, muscle was a target tissue for these fungicides and a synergistic interaction was observed for the mixture. Due to the lack of studies in fish assessing the effects following exposure to AZX-CYP mixtures and considering a realistic exposure situation in agriculture-impacted water bodies, these findings provide new and relevant information for future studies.

Experimental investigation of the effect of tebuconazole on three biomarkers of innate immunity in the house sparrow (Passer domesticus)

Triazoles are among the most widely used fungicides in the world due to their efficacy against fungal crop diseases and their broad spectrum of action. Intensive use of triazoles has resulted in residual contamination in different compartments of agroecosystems and exposes non-target species to potential sublethal effects. Triazoles are known to be immunomodulators in medicine and therapeutic treatments, but very little data is available on their potential effect on immune parameters of non-target vertebrate species living in agroecosystems. In this study, we experimentally examined the impact of tebuconazole on three immune biomarkers (haemagglutination titre (HA), haemolysis titre (HL), and haptoglobin concentration (Hp)), as well as on the body condition of house sparrows (Passer domesticus). Our results suggest that tebuconazole had very little, if any, effect on the studied immune parameters. However, further studies are needed to better assess the effect of tebuconazole on bird immunity because (1) experimental individuals were kept under optimal conditions and the impact of tebuconazole on immunity may occur under suboptimal conditions, (2) only one concentration of tebuconazole was tested and its effect could be dose-dependent and (3) other complementary immunological biomarkers should be studied, given the complexity of the vertebrate immune system. Current knowledge on the potential effects of triazoles on the immunity of wild farmland vertebrates is still largely insufficient. Further physiological and immune studies should be conducted to better understand the effect of triazole fungicides on farmland birds.

Neurobehavioral effects of fungicides in zebrafish: a systematic review and meta-analysis

Pesticides are widely used in global agriculture to achieve high productivity levels. Among them, fungicides are specifically designed to inhibit fungal growth in crops and seeds. However, their application often results in environmental contamination, as these chemicals can persistently be detected in surface waters. This poses a potential threat to non-target organisms, including humans, that inhabit the affected ecosystems. In toxicologic research, the zebrafish (Danio rerio) is the most commonly used fish species to assess the potential effects of fungicide exposure, and numerous and sometimes conflicting findings have been reported. To address this, we conducted a systematic review and meta-analysis focusing on the neurobehavioral effects of fungicides in zebrafish. Our search encompassed three databases (PubMed, Scopus, and Web of Science), and the screening process followed predefined inclusion/exclusion criteria. We extracted qualitative and quantitative data, as well as assessed reporting quality, from 60 included studies. Meta-analyses were performed for the outcomes of distance traveled in larvae and adults and spontaneous movements in embryos. The results revealed a significant overall effect of fungicide exposure on distance, with a lower distance traveled in the exposed versus control group. No significant effect was observed for spontaneous movements. The overall heterogeneity was high for distance and moderate for spontaneous movements. The poor reporting practices in the field hindered a critical evaluation of the studies. Nevertheless, a sensitivity analysis did not identify any studies skewing the meta-analyses. This review underscores the necessity for better-designed and reported experiments in this field.

Triazoles as a Potential Threat to the Nutritional Quality of Tomato Fruits

Triazole fungicides can threaten plants as abiotic stressors but can also positively affect plant defense by inducing priming. Thus, plant yield is also both protected and endangered by triazoles that may influence several metabolic pathways during maturation processes, such as the biosynthesis of saccharides or secondary metabolites. Here, Solanum lycopersicum L. plants were exposed to foliar and soil applications of penconazole, tebuconazole, or their combination, and their resulting effect on tomato fruits was followed. The exposure to the equimolar mixture of both triazoles influenced the representation of free proteinogenic amino acids, especially Gln, Glu, Gly, Ile, Lys, Ser and Pro, saccharide content, and led to a significant increase in the contents of total phenolics and flavonoids as well as positive stimulation of the non-enzymatic antioxidant system. Among the identified secondary metabolites, the most abundant was naringenin, followed by chlorogenic acid in tomato peel. In turn, all triazole-treated groups showed a significantly lower content of rosmarinic acid in comparison with the control. Foliar application of penconazole affected the fruit more than other single triazole applications, showing a significant decrease in antioxidant capacity, the total content of secondary metabolites, and the activities of total membrane-bound peroxidases and ascorbate peroxidase.

Detrimental consequences of tebuconazole on redox homeostasis and fatty acid profile of honeybee brain

Excessive use of azole fungicides in agriculture poses a potential threat to honeybees and other pollinator insects; however, the detailed effects of these molecules remain largely unclear. Hence, in the present study it was aimed to investigate the acute sublethal effects of tebuconazole on the redox homeostasis and fatty acid composition in the brain of honeybees. Our findings demonstrate that tebuconazole decreased total antioxidant capacity, the ratio of reduced to oxidized glutathione and disturbed the function of key antioxidant defense enzymes along with the induction of lipid peroxidation indicated by increased malondialdehyde levels, while it also altered the fatty acid profile of the brain. The present study highlights the negative impact of tebuconazole on honeybees and contributes to the understanding of potential consequences related to azole exposure on pollinator insects' health, such as the occurrence of colony collapse disorder.

Sanguinarine exposure induces immunotoxicity and abnormal locomotor behavior in zebrafish

Sanguinarine (C20H14NO4+), a plant alkaloid and pesticide, works well a fungicidal and insecticidal applications. The prospect that sanguinarine may have potentially toxic effects on aquatic organisms has been brought to light by its use in agriculture. The first evaluation of the immunotoxic and behavioral effects of sanguinarine exposure on larval zebrafish was done in this work. Firstly, zebrafish embryos exposed to sanguinarine had shorter body length, larger yolk sacs, and slower heart rates. Secondly, the number of innate immune cells was significantly reduced. Thirdly, alterations in locomotor behavior were observed as exposure concentrations increased. Total distance travelled, travel time, and mean speed were all reduced. We also found significant changes in oxidative stress-related indicators and a significant increase in apoptosis in the embryos. Further studies revealed aberrant expression of some key genes in the TLR immune signaling pathway including CXCL-c1c, IL8, MYD88, and TLR4. At the same time, the expression of the pro-inflammatory cytokine IFN-γ was upregulated. To sum up, our results suggest that sanguinarine exposure may cause immunotoxicity and aberrant behavior in larval zebrafish.

Multicompartmental monitoring of legacy and currently used pesticides in a subtropical lake used as a drinking water source (Laguna del Cisne, Uruguay)

A pilot annual monitoring survey (April 2018-March 2019) was conducted to investigate the presence of pesticides in superficial water and fish in Laguna del Cisne, one of the most critical drinking water sources in Uruguay. A total of 25 pesticide residues were detected in superficial water (89.3 % of the samples). Pesticide's temporal distribution was associated with crops and livestock practices, with higher occurrences in spring and summer than in autumn and winter. The most frequent compounds in superficial water were the insecticide chlorantraniliprole, and the herbicides glyphosate (including its metabolite AMPA) and metolachlor. The levels of Organochlorine pesticide, p,p'-DDT, was in some cases two order of magnitude above the international water quality guidelines for Ambient Water Criteria. In fishes, eight different pesticides were detected, at concentrations from 1000 to 453,000 ng·kg^-1. The most frequent pesticides found were propiconazole, chlorpyrifos, and p,p'-DDE. The widespread occurrence of pesticides in fish suggests potential exposure effects on fish populations and the aquatic ecosystem. The sampling approach of this work allowed monitoring the continuous concentrations of several pesticides in surface waters and fishes to establish the influence from past and current agriculture practices in Laguna del Cisne basin. For safety measures, continuous monitoring programs must be performed in this system to prevent toxicity impacts on aquatic organisms and human health.

Ochratoxin A induces locomotor impairment and oxidative imbalance in adult zebrafish

Ochratoxin A (OTA) is a mycotoxin produced by species of filamentous fungi widely found as a contaminant in food and with high toxic potential. Studies have shown that this toxin causes kidney and liver damage; however, data on the central nervous system effects of exposure to OTA are still scarce. Thus, this study aimed to investigate the effects of exposure to OTA on behavioral and neurochemical parameters in adult zebrafish. The animals were treated with different doses of OTA (1.38, 2.77, and 5.53 mg/kg) with intraperitoneal injections and submitted to behavioral evaluations in the open tank and social interaction tests. Subsequently, they were euthanized, and the brains were used to assess markers associated with oxidative status. In the open tank test, OTA altered distance traveled, absolute turn angle, mean speed, and freezing time. However, no significant effects were observed in the social interaction test. Moreover, OTA also increased glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione reductase (GR) levels and decreased non-protein thiols (NPSH) levels in the zebrafish brain. This study showed that OTA can affect behavior and neurochemical levels in zebrafish.

Azole pesticide products and their hepatic metabolites cause endocrine disrupting potential by suppressing the homo-dimerization of human estrogen receptor alpha

We selected azole pesticides products that are managed by setting maximum residue limits (MRLs) in the Republic of Korea and describe the estrogen receptor (ER) α-related negative effect to endocrine system using in vitro Organization for Economic Cooperation and Development performance-based test guideline. No azoles were found to be an ERα agonist. Conversely, three azoles (bitertanol, cafenstrole, and tebufenpyrad) were determined to be ERα antagonists. In addition, the ERα antagonistic activities of bitertanol, cafenstrole, and tebufenpyrad were not significantly perturbed in the existence of phase I (hydroxylation, dealkylation, oxidation or reduction) and phase II (conjugation). Regarding the mechanism underlying their ERα-mediated endocrine disrupting potentials, ERα proteins cannot be translocated to the nucleus by suppressing the dimerization of ERα in the cytoplasm by bitertanol, cafenstrole, and tebufenpyrad. These data indicated that azole pesticide products show the capability to interfere the ERα-related human endocrine system. Furthermore, we identified the mechanism of ERα-mediated endocrine disrupting by azole insecticide products through this study.

Toxicological effects caused by environmental relevant concentrations of ketoconazole in Chironomus sancticaroli (Diptera, Chironomidae) larvae evaluated by oxidative stress biomarkers

Ketoconazole (KTZ), a broad-spectrum fungicidal drug, has been a significant problem in recent decades due to its toxic action on non-target aquatic organisms. Thus, the present study aimed to evaluate determine the effects that environmental relevant concentration of the commercial formulation of KTZ can exert on benthic macroinvertebrates, more specifically on larvae of the insect Chironomus sancticaroli. Acute toxicity tests with KTZ indicated lethal concentration (LC₅₀) of 9.9 μg/L. Analyses of prolonged exposure to KTZ (chronic toxicity) indicated an increase in the rate of mentum deformity by approximately 3 times at concentrations of 0.6 and 2.4 μg/L. All biomarkers analyzed showed an increase after exposure to KTZ (0.6 and 2.4 μg/L), with average values of 115 % for superoxide dismutase (SOD), 63 % for catalase (CAT), 111 % for glutathione S-transferase (GST) and 59 % for malonaldehyde (MDA) in C. sancticaroli larvae. Thus, the toxic effects on survival, development (length and weight), mentum and redox responses caused by commercial KTZ in low concentrations were observed on C. sancticaroli larvae. In addition, the results suggest that biochemical biomarkers can be used for studies involving environmental disturbances.

The toxicity of 4-tert-butylphenol in early development of zebrafish: morphological abnormality, cardiotoxicity, and hypopigmentation

Endocrine disrupting effects of 4-tert-butylphenol (4-t-BP) are well described in literature. However, the evidence regarding developmental toxic effect of 4-t-BP is still vague. The present study used zebrafish as a model organism to investigate the toxic effect of 4-t-BP. The results showed that 4-t-BP exposure at 3, 6, and 12 μM induced developmental toxicity in zebrafish, such as reduced embryo hatchability and abnormality morphological. Flow cytometry analysis showed that 4-t-BP also induced intracellular ROS production. 4-t-BP induced changes in the expression of genes related to cardiac development and melanin synthesis, resulting in cardiotoxicity and hypopigmentation. 4-t-BP also caused oxidative stress, and initiated apoptosis through p53-bcl-2/bax-capase3 pathway. Integrative biomarker response analysis showed time- and dose-dependent effects of 4-t-BP on oxidative damage and developmental toxicity in zebrafish embryos. Overall, this study contributed to a comprehensive evaluation of the toxicity of 4-t-BP, and the findings provided new evidence for early warning of residues in aquatic environments.

Environmental Hormone Effects and Bioaccumulation of Propiconazole and Difenoconazole in Procypris merus

Studying the bioaccumulation behavior and toxicity of triazole fungicides is a crucial part of comprehensively evaluating the environmental fate and aquatic toxicity.The current research aimed to reveal the toxic effects of propiconazole and difenoconazole on fish through acute toxicity test, bioaccumulation test and oxidase system activity determination. Here, the propiconazole and difenoconazole concentrations were 11.3 mg/L and 31.2 mg/L for LC₅₀-96 h, both having low toxicity. LC-MS/MS was used to determine the propiconazole and difenoconazole concentrations in five organs (muscle, gill, liver, intestine, and kidney) of Procypris meru. The findings indicate that the bioconcentration coefficients of propiconazole and difenoconazole in grass flower carp were 0.66-27.08 and 2.43-22.72, which belonged to medium enrichment pesticides. The bioconcentration coefficients decreased with the increase of exposure concentration. The two fungicides could induce oxidative stress in fish liver, and the activities of three antioxidant enzymes were inhibited in varying degrees (p < 0.05). The results showed that the content of T3 increased, and T4 decreased when exposed to one-tenth LC₅₀ for 7 days. This study shows that triazole pesticides have bioaccumulation risks on aquatic organisms and clear environmental hormonal effects.

Pesticides and Their Impairing Effects on Epithelial Barrier Integrity, Dysbiosis, Disruption of the AhR Signaling Pathway and Development of Immune-Mediated Inflammatory Diseases

The environmental and occupational risk we confront from agricultural chemicals increases as their presence in natural habitats rises to hazardous levels, building a major part of the exposome. This is of particular concern in low- and middle-income countries, such as Brazil, known as a leading producer of agricultural commodities and consumer of pesticides. As long as public policies continue to encourage the indiscriminate use of pesticides and governments continue to support this strategy instead of endorsing sustainable agricultural alternatives, the environmental burden that damages epithelial barriers will continue to grow. Chronic exposure to environmental contaminants in early life can affect crucial barrier tissue, such as skin epithelium, airways, and intestine, causing increased permeability, leaking, dysbiosis, and inflammation, with serious implications for metabolism and homeostasis. This vicious cycle of exposure to environmental factors and the consequent damage to the epithelial barrier has been associated with an increase in immune-mediated chronic inflammatory diseases. Understanding how the harmful effects of pesticides on the epithelial barrier impact cellular interactions mediated by endogenous sensors that coordinate a successful immune system represents a crucial challenge. In line with the epithelial barrier hypothesis, this narrative review reports the available evidence on the effects of pesticides on epithelial barrier integrity, dysbiosis, AhR signaling, and the consequent development of immune-mediated inflammatory diseases.

Effect of propiconazole on neutrophil extracellular traps formation: Assessing the role of autophagy

Propiconazole (Pcz) is a kind of triazole fungicide which has an important impact on the environment. With the extensive use of Pcz in agricultural production activities, the pesticides are left in soil, water, crops and food, and will enter the organisms in the form of residues. Neutrophils play a key role in the body's innate immunity against pathogens, and the formation of neutrophil extracellular traps (NETs) is an important way for neutrophils to exert their immune function. In the present study, we focused on the effect of Pcz on the NETs of Sprague-Dawley (SD) rats for the first time. Our data demonstrated that Pcz could hinder NETs formation via inhibiting the Phosphoinositide 3-kinase (PI3K)/rapidly accelerated fibrosarcoma (Raf)/extracellular signal-regulated kinase (ERK) signaling. In the meanwhile, we assessed the role of autophagy played in this process and revealed that Pcz may inhibit the respiratory burst in neutrophils. This study provided new insights into the immunotoxic hazards of Pcz and additional laboratory evidence for assessing the impact of Pcz on terrestrial organisms.

Brain injury, genotoxic damage and oxidative stress induced by Bromuconazole in male Wistar rats and in SH-SY5Y cell line

BACKGROUND

Bromuconazole is a widely used triazole against various fungi disease. It's employment provokes harmful effects on the environment and human health. In the present study, we explored bromuconazole toxic effects in both rat brain tissue and SH-SY5Y cell line.

METHODS

Male Wistar rats were administrated orally with Bromuconazole (NOEL/4, NOEL o and NOEL ×2) daily for consecutive 28 days. In addition, neuronal SH-SY5Y cell line was used. The rat brains and SH-SY5Y cells were collected and analysed for AChE activity, oxidative stress biomarkers, genotoxicity and histopathological alterations.

RESULTS

Our results showed that rat exposure to bromuconazole at doses corresponding to NOEL/4, NOEL and NOEL ×2 caused brain histopathological alteration and decrease in acetylcholine esterase (AChE) activity. In SH-SY5Y cell line, bromuconazole strongly induced cell mortality with an IC50 about 250 µM. Bromuconazole induced also DNA damage as assessed by comet assay in both rat brain tissue and SH-SY5Y cell. Moreover, bromuconazole increased ROS production, malondialdehyde (MDA) and protein carbonyl (PC) levels and enhanced the enzymatic activities of catalase (CAT), superoxide dismutase (SOD), Glutathione-S-transferase (GST) and peroxidase (GPx) in the two studied systems.

CONCLUSION

Therefore, we can deduce that bromuconazole-caused neurotoxicity may be related to oxidative statue disturbance.HIGHLIGHTSBromuconzole causes oxidative stress in the brain tissue of male Wistar rats.Bromuconazole enhances MDA, PC levels and induces DNA damage in rat brain.Bromuconazole provokes disturbance of the neuronal antioxidant system.Bromuconazole induces histopathological alterations in rat brain.Bromuconazole exposure induced cytotoxic effects and DNA damage in SH-SY5Y cells.Bromuconazole exposure induced oxidative stress in SH-SY5Ycells.

A comprehensive review of 1,2,4-triazole fungicide toxicity in zebrafish (Danio rerio): A mitochondrial and metabolic perspective

In this critical review, we synthesize data from peer-reviewed literature reporting on triazole fungicide exposures in the zebrafish model. Based on their mode of action in plants (potent inhibitors of ergosterol synthesis), we focused attention on mechanisms related to cellular, lipid, and steroid metabolism. Evidence from several studies reveals that zebrafish exposed to triazoles present with impaired mitochondrial oxidative phosphorylation and oxidative stress, as well as dysregulation of lipid metabolism. Such metabolic disruptions are expected to underscore developmental delays, deformity, and aberrant locomotor activity and behaviors often observed following exposure. We begin by summarizing physiological and behavioral effects observed with triazole fungicide exposure in zebrafish. We then discuss mechanisms that may underlie adverse apical effects, focusing on mitochondrial bioenergetics and metabolism. Using computational approaches, we also identify novel biomarkers of triazole fungicide exposure. Extracting and analyzing data contained in the Comparative Toxicogenomics Database (CTD) revealed that transcriptional signatures responsive to different triazoles are related to metabolism of lipids and lipoproteins, biological oxidations, and fatty acid, triacylglycerol, and ketone body metabolism among other processes. Pathway and sub-network analysis identified several transcripts that are responsive in organisms exposed to triazole fungicides, several of which include lipid-related genes. Knowledge gaps and recommendations for future investigations include; (1) targeted metabolomics for metabolites in glycolysis, Krebs cycle, and the electron transport chain; (2) additional studies conducted at environmentally relevant concentrations to characterize the potential for endocrine disruption, given that studies point to altered cholesterol (precursor for steroid hormones), as well as altered estrogen receptor alpha and thyroid hormone expression; (3) studies into the potential role for lipid peroxidation and oxidation of lipid biomolecules as a mechanism of triazole-induced toxicity, given the strong evidence for oxidative damage in zebrafish following exposure to triazole fungicides.

Epoxiconazole profoundly alters rat brain and properties of neural stem cells

Epoxiconazole (EPX), a widely used fungicide for domestic, medical, and industrial applications, could cause neurodegenerative diseases. However, the underling mechanism of neurotoxicity is not well understood. This study aimed to investigate the possible toxic outcomes of Epoxiconzole, a triazole fungicide, on the brain of adult rats in vivo, and in vitro on neural stem cells derived from the subventricular zone of newborn Wistar rats. Our results revealed that oral exposure to EPX at these concentrations (8, 24, 40, 56 mg/kg bw representing respectively NOEL (no observed effect level), NOEL × 3, NOEL × 5, and NOEL × 7) for 28 days caused a considerable generation of oxidative stress in adult rat brain tissue. Furthermore, a significant augmentation in lipid peroxidation and protein oxidation has been found. Moreover, it induced an elevation of DNA fragmentation as assessed by the Comet assay. Indeed, EPX administration impaired activities of antioxidant enzymes and inhibited AChE activity. Concomitantly, this pesticide produced histological alterations in the brain of adult rats. Regarding the embryonic neural stem cells, we demonstrated that the treatment by EPX reduced the viability of cells with an IC50 of 10 μM. It also provoked the reduction of cell proliferation, and EPX triggered arrest in G1/S phase. The neurosphere formation and self-renewal capacity was reduced and associated with decreased differentiation. Moreover, EPX induced cytoskeleton disruption as evidenced by immunocytochemical analysis. Our findings also showed that EPX induced apoptosis as evidenced by a loss of mitochondrial transmembrane potential (ΔΨm) and an activation of caspase-3. In addition, EPX promoted ROS production in neural stem cells. Interestingly, the pretreatment of neural stem cells with the N-acetylcysteine (ROS scavenger) attenuated EPX-induced cell death, disruption of neural stem cells properties, ROS generation and apoptosis. Thus, the use of this hazardous material should be restricted and carefully regulated.

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

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

Anti-stress effects of the glucagon-like peptide-1 receptor agonist liraglutide in zebrafish

Stress-related disorders are extremely harmful and cause significant impacts on the individual and society. Despite the limited evidence regarding glucagon-like peptide-1 receptor (GLP-1R) and mental disorders, a few clinical and preclinical studies suggest that modulating this system could improve symptoms of stress-related disorders. This study aimed to investigate the effects of liraglutide, a GLP-1R agonist, on neurobehavioral phenotypes and brain oxidative status in adult zebrafish. Acute liraglutide promoted anxiolytic-like effects in the light/dark test, while chronic treatment blocked the impact of unpredictable chronic stress on behavioral and physiological parameters. Taken together, our study demonstrates that liraglutide is active on the zebrafish brain and may counteract some of the effects induced by stress. More studies are warranted to further elucidate the potential of GLP-1R agonists for the management of brain disorders.

Effects of nanoplastic on toxicity of azole fungicides (ketoconazole and fluconazole) in zebrafish embryos

The ubiquity of nanoplastics (NPs) raises concerns about their interactions and combined toxicity with other common contaminants. Although azoles are present throughout the natural environment, their interactions with NP are not well known. We investigated the effects of polystyrene (PS) NP on the toxicity of ketoconazole (KCZ) and fluconazole (FCZ) in zebrafish embryos using the developmental toxicity, oxidative-stress-related biochemical parameters, and expression of genes related to neurotoxicity (ache), cardiotoxicity (gata4, bmp4), inflammation (il1b), oxidative stress (sod1, sod2, cyp1a), and apoptosis (bax, bcl2). Co-exposure to NP (1 mg/L) and KCZ/FCZ (1 mg/L) for 96 h reduced the hatching rate, survival rate, and heart rate and increased the malformation rate and catalase activity. The bax/bcl2 ratio, an apoptosis indicator, was higher after NP, KCZ, or FCZ treatment. However, the bax/bcl2 ratio after exposure to NP + KCZ or NP + FCZ was much higher than that after single exposure. Overall, the results indicated that NP aggravated the toxicity of azole by significantly increasing the reactive oxygen species, lipid peroxidation and altering the expression of oxidative-stress- and apoptosis-related genes. The interactive toxicity of PS NP with KCZ/FCZ reported in this study emphasises the need for caution in the release of azole fungicides in the environment.

Biochemical and Behavioral Responses in Zebrafish Exposed to Imidacloprid Oxidative Damage and Antioxidant Responses

Imidacloprid (IMI) is an insecticide used worldwide, a neonicotinoid that could cause toxicity in non-target organisms. Zebrafish (Danio rerio) is a model organism widely used in different fields of research such as behavioral studies, biochemical parameters as well as neurotoxicity research. Here, we investigate whether the exposure to three concentrations (0.15, 15, and 45 μg/L) of IMI for 96 h alters responses in zebrafish. Oxidative stress parameters and acetylcholinesterase activity (AChE) as well as the behavioral responses of locomotion were measured. IMI exposure decreased distance traveled in fish exposed to the 45 μg/L. In the exploratory activity, time spent and transitions to the top area of the water column decreased in fish exposed to all concentrations of IMI. In addition, exposures to 45 and 15 μg/L of IMI decreased episodes of erratic movement in the zebrafish. Exposures to IMI at a concentration of 45 μg/L decreased the time spent in erratic movements and increased the time spent with no movement (i.e., "freezing"). Glutathione S-transferase (GST) activity was increased in the brain of zebrafish exposed for 96 h to concentrations of 0.15 and 45 μg/L. Brain AChE activity was reduced and the levels of carbonyl protein (CP) increased in brain of zebrafish at concentrations of 15 and 45 μg/L. Lipid peroxidation measured by TBARS and, also non-protein thiols (NPSH) did not show any variation in the brain of zebrafish exposed to IMI. Changes in the activity of cholinergic neurotransmitters in the brain tissues of zebrafish indicate IMI toxicity. Exposures of fish over 96 h to IMI at a nominal concentration of 45 μg/L caused more extensive sublethal responses in zebrafish, but this concentration is well above those expected in the aquatic environment. Studies are warranted to evaluate the effects on behavior and biomarker responses in fish exposed over longer periods to IMI at environmentally relevant concentrations.

Residential proximity to pesticide application as a risk factor for childhood central nervous system tumors

BACKGROUND

Pesticide exposures have been examined previously as risk factors for childhood brain cancers, but few studies were able to assess risk from specific agents.

OBJECTIVE

To evaluate risks for childhood central nervous system tumors associated with residential proximity to agricultural pesticide applications.

METHODS

Using the California Cancer Registry, we identified cancer cases less than 6 years of age and frequency matched them by year of birth to 20 cancer-free controls identified from birth certificates. We restricted analyses to mothers living in rural areas and births occurring between 1998 and 2011, resulting in 667 cases of childhood central nervous system tumors and 123,158 controls. Possible carcinogens were selected per the Environmental Protection Agency's (US. EPA) classifications, and prenatal exposure was assessed according to pesticides reported by the California Department of Pesticide Regulation's (CDPR) Pesticide Use Reporting (PUR) system as being applied within 4000m of the maternal residence at birth. We computed odds ratios for individual pesticide associations using unconditional logistic and hierarchical regression models.

RESULTS

We observed elevated risks in the hierarchical models for diffuse astrocytoma with exposure to bromacil (OR: 2.12, 95% CI: 1.13-3.97), thiophanate-methyl (OR: 1.64, 95% CI: 1.02-2.66), triforine (OR: 2.38, 95% CI: 1.44-3.92), and kresoxim methyl (OR: 2.09, 95% CI: 1.03-4.21); elevated risks for medulloblastoma with exposure to chlorothalonil (OR: 1.78, 95% CI: 1.15-2.76), propiconazole (OR: 1.60, 95% CI: 1.02, 2.53), dimethoate (OR: 1.60, 95% CI: 1.06, 2.43), and linuron (OR: 2.52, 95% CI: 1.25, 5.11); and elevated risk for ependymoma with exposure to thiophanate-methyl (OR: 1.72, 95% CI: 1.10-2.68).

CONCLUSION

Our study suggests that exposure to certain pesticides through residential proximity to agricultural applications during pregnancy may increase the risk of childhood central nervous system tumors.

Preventive efficiency of Cornelian cherry (Cornus mas L.) fruit extract in diniconazole fungicide-treated Allium cepa L. roots

Cornelian cherry (Cornus mas L.) is a medicinal plant with antioxidant-rich fruits. Diniconazole, a broad-spectrum fungicide, is employed extensively. The present study was designed to evaluate the preventive efficiency of C. mas fruit extract (CME) against the toxic effects of diniconazole on a model organism, Allium cepa L. For this aim, physiological, cytogenetic and biochemical parameters as well as the meristematic cell damages were investigated in A. cepa treated with diniconazole and C. mas extract. A. cepa bulbs were divided into six groups which were treated with tap water, 0.5 g/L CME, 1.0 g/L CME, 100 mg/L diniconazole, 0.5 g/L CME + 100 mg/L diniconazole and 1.0 g/L CME + 100 mg/L diniconazole, respectively. Diniconazole application caused a significant reduction in germination percentage, root elongation and total weight gain. Mitotic index decreased, while chromosomal aberrations increased following diniconazole application. Diniconazole caused significant rises in malondialdehyde content and the total activities of superoxide dismutase and catalase enzymes. The meristematic cell damages induced by diniconazole were indistinct transmission tissue, epidermis cell deformation, thickening of the cortex cell wall and flattened cell nucleus. Aqueous C. mas extracts induced a dose-dependent prevention and amelioration in all damages arisen from diniconazole application.

A comprehensive review on environmental toxicity of azole compounds to fish

BACKGROUND

Azoles are considered as one of the most efficient fungicides for the treatment of humans, animals, and plant fungal pathogens. They are of significant clinical importance as antifungal drugs and are widely used in personal care products, ultraviolet stabilizers, and in aircraft for its anti-corrosive properties. The prevalence of azole compounds in the natural environment and its accumulation in fish raises questions about its impact on aquatic organisms.

OBJECTIVES

The objective of this paper is to review the scientific studies on the effects of azole compounds in fish and to discuss future opportunities for the risk evaluation.

METHODS

A systematic literature search was conducted on Web of Science, PubMed, and ScienceDirect to locate peer-reviewed scientific articles on occurrence, environmental fate, and toxicological impact of azole fungicides on fish.

RESULTS

Studies included in this review provide ample evidence that azole compounds are not only commonly detected in the natural environment but also cause several detrimental effects on fish. Future studies with environmentally relevant concentrations of azole alone or in combination with other commonly occurring contaminants in a multigenerational study could provide a better understanding.

CONCLUSION

Based on current knowledge and studies reporting adverse biological effects of azole on fish, considerable attention is required for better management and effective ecological risk assessment of these emerging contaminants.

A comparison of behavioral and reproductive parameters between wild-type, transgenic and mutant zebrafish: Could they all be considered the same "zebrafish" for reglementary assays on endocrine disruption?

Transgenic zebrafish models are efficiently used to study the effects of endocrine disrupting chemicals (EDC); thereby informing on their mechanisms of action. However, given the reported differences between zebrafish strains at the genetical, physiological and behavioral levels; care should be taken before using these transgenic models for EDC testing. In the present study, we undertook a set of experiments in different transgenic and/or mutant zebrafish strains of interest for EDC testing: casper, cyp19a1a-eGFP, cyp19a1a-eGFP-casper, cyp11c1-eGFP, cyp11c1-eGFP-casper. Some behavioral traits, and some biochemical and reproductive physiological endpoints commonly used in EDC testing were assessed and compared to those obtained in WT AB zebrafish to ensure that transgene insertion and/or mutations do not negatively modify basal reproductive physiology or behavior of the fish. Behavioral traits considered as anxiety and sociality have been monitored. Sociality was evaluated by monitoring the time spent near congeners in a shuttle box while anxiety was evaluated using the Novel tank diving test. No critical difference was observed between strains for either sociality or anxiety level. Concerning reproduction, no significant difference in the number of eggs laid per female, in the viability of eggs or in the female circulating VTG concentrations was noted between the 5 transgenic/mutants and the WT AB zebrafish studied. In summary, the transgene insertion and the mutations had no influence on the endpoints measured in basal conditions. These results were a prerequisite to the use of these transgenic/mutant models for EDC testing. Next step will be to determine the sensitivity of these biological models to chemical exposure to accurately validate their use in existing fish assays for EDC testing.

Fluxapyroxad induces developmental delay in zebrafish (Danio rerio)

Succinate dehydrogenase inhibitor (SDHI) fungicides are extensively used in agriculture. Some SDHI fungicides show developmental toxicity, immune toxicity and hepatotoxicity to fish. Fluxapyroxad (FLU) is a broad spectrum pyrazole-carboxamide SDHI fungicide and its potential impacts on fish embryonic development are unknown. We exposed zebrafish embryos to 1, 2 and 4 μM FLU. Developmental malformations, including yolk sac absorption disorder, decreased pigmentation and hatch delay were induced after FLU exposure. FLU caused significantly increased transcription levels in the ectoderm marker foxb1a but no significant changes in endoderm and mesoderm development markers (foxa2, ntl and eve1). Transcription levels of genes in the early stage embryos (gh, crx, neuroD and nkx2.4b) decreased significantly after FLU treatments. The content of glutathione (GSH) increased after FLU exposure. This study shows that FLU is toxic to zebrafish through its developmental effects and oxidative stress. FLU may pose risks to other non-target aquatic organisms.

The effects of a short-term exposure to propiconazole in zebrafish (Danio rerio) embryos

Propiconazole (PCZ) is a widely used fungicide around the world and was frequently detected in surface waters, which would pose risk to aquatic organisms. Previous studies indicated that PCZ has high toxicity to different kinds of fish. However, most of the studies focus on the toxicity and mechanisms of PCZ to adult fish, the potential toxicity mechanism of PCZ to fish embryos is still poorly understood. The present study investigated the effects of PCZ on content of reactive oxygen species (ROS) and malondialdehyde (MDA); activities of superoxide dismutase (SOD), catalase (CAT), and Na⁺-K⁺-ATPase; and expression level of genes related to oxidative stress, cell apoptosis, and innate immune system in zebrafish embryos after 96-h exposure. The results showed that 5.0 mg/L PCZ induced oxidative damage in zebrafish embryos, as indicated by increased ROS and MDA content and alteration of antioxidative enzyme activity. The activity of Na⁺-K⁺-ATPase in zebrafish embryos was significantly inhibited after exposure to 0.5 mg/L PCZ. The expression levels of bax, p53, casp-3, casp-9, and apaf-1 were significantly increased, indicating that cell apoptosis was caused in embryos by 5.0 mg/L PCZ. The expression level of interleukin-1b (IL-1b) and IL-8 increased after exposure to 0.5 mg/L PCZ, but that of IL-1b, IL-8, and cxcl-c1c (chemokine (C-X-C motif) ligand 18b) decreased in 5.0-mg/L PCZ treatment group, indicating an immunotoxicity effect. Our results suggest that oxidative damage, cell apoptosis, and immunotoxicity would be induced in zebrafish embryos after short-term exposure to PCZ.

A mixture of fipronil and fungicides induces alterations on behavioral and oxidative stress parameters in zebrafish

Pesticide commercial mixtures, including the insecticide fipronil and the fungicides pyraclostrobin and methyl-thiophanate, have been used in concomitant pest control, facilitating agricultural management. Their widespread use can lead to soil and water contamination and potentially induce damages in the ecosystem, producing toxic effects in non-target organisms. Despite their toxicological potential, their effects on behavioral and biochemical parameters are not well understood. Here we investigated the effects of the mixture of fipronil and fungicides (MFF) pyraclostrobin and methyl- thiophanate on behavioral and biochemical parameters of oxidative stress in adult zebrafish. Animals exposed to the highest MFF tested concentration showed a decrease in the total distance traveled and in the number of crossings in the different zones of the tank. Furthermore, animals exposed to highest MFF tested concentration spent more time in water surface. In addition, our data showed that the exposure to this preparation promoted a decrease in non-protein thiol content as well as in catalase activity. Finally, pesticide exposure induced an increase in the superoxide dismutase/catalase ratio. Our results indicate that alterations in behavioral and oxidative parameters are involved in MFF toxicity in zebrafish. The antioxidant mechanisms analyzed were altered in concentrations that did not affect zebrafish behavior. Therefore, the assessment of oxidative stress parameters in zebrafish brains could be very useful to detect the early effects of environmental exposure to the MFF.