Potential adverse outcome pathway (AOP) of emamectin benzoate mediated cardiovascular toxicity in zebrafish larvae (Danio rerio)

Investigation of the mechanisms of liver injury induced by emamectin benzoate exposure at environmental concentrations in zebrafish: A multi-omics approach to explore the role of the gut-liver axis

Emamectin benzoate (EMB) is a lipophilic pesticide that enters aquatic systems and adversely affects non-target organisms. This study investigated the long-term effects of EMB on zebrafish, exposing them to concentrations of 0, 0.1, 1, and 10 μg/L from the 4-hour post-fertilization (hpf) embryo stage to the 120-day post-fertilisation (dpf) adult stage. We found that exposure to 1 μg/L EMB induced liver damage, manifested as impaired liver function (elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT)), histopathological damage (lipid accumulation), as well as inflammatory and oxidative damage, with a dose - dependent effect. Non-targeted metabolomic analysis revealed an increase in lipid molecules in the liver, affecting the pathways related to glycerophospholipid metabolism. In addition, EMB exposure resulted in damage to the intestinal barrier and inflammatory responses in zebrafish. 16S rRNA sequencing demonstrated that EMB exposure resulted in notable alterations in the gut microbiota composition. Notably, the abundance of Plesiomonas and Cetobacterium increased in the EMB exposure group and exhibited a positive correlation with the majority of liver lipid metabolites. In contrast, reductions in Muribaculaceae and Alloprevotella were negatively correlated. The results of this study indicate that long-term exposure to EMB disrupts the gut microbiota, leading to the dysregulation of hepatic phospholipid metabolism. These findings provide new insights into the health risks associated with EMB and highlight its potential threats to higher organisms, including mammals.

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.

Neomycin affects cardiovascular and hematopoietic system via the PI3K/Akt pathway in zebrafish larvae

Neomycin, a widely used aminoglycoside antibiotic, poses potential risks to organism and the environment that remain incompletely evaluated. This study systematically evaluates its toxic effects on zebrafish embryos across physiological, cellular, molecular, and behavioral dimensions. At the physiological level, neomycin exposure induces severe developmental abnormalities, including yolk sac edema, reduced body length, and craniofacial malformations. Developmental disorders of the cardiovascular and hematopoietic systems are confirmed in exposed larvae. In addition, zebrafish larvae exposed to neomycin exhibit significant locomotor deficits, including reduced swimming speed, distance traveled, and impaired responsiveness to light-dark stimulation, indicating reduced activity. Mechanically, neomycin triggers oxidative stress through a dose-dependent elevation of reactive oxygen species (ROS) levels and induces cellular apoptosis through the PI3K/Akt signaling pathway. Collectively, our findings demonstrate that neomycin exerts toxic effects on zebrafish embryonic development, highlighting concerns regarding neomycin exposure risks during early pregnancy and providing critical insights into its potential environmental hazards.

Long-term exposure to Emamectin benzoate impairs reproductive health in adult zebrafish and alters neurodevelopment in their offspring

Emamectin benzoate (EMB) is a widely used insecticide that can accumulate in aquatic environments under specific conditions of high application intensity or improper management, posing potential risks to aquatic organisms and human health. This study aimed to evaluate the reproductive toxicity of long-term EMB exposure in zebrafish (Danio rerio) and neurodevelopmental toxicity in their offspring. Zebrafish embryos were exposed to various concentrations of EMB (0, 0.1, 1, and 10 μg/L) for up to 120 days. The results revealed a significant decrease in reproductive capacity and gonadal tissue damage in the F0 generation zebrafish. Additionally, the increased oxidative stress levels induced by EMB exposure further exacerbated reproductive toxicity. The F1 generation of zebrafish exhibited a high rate of deformities, reduced body length, decreased swim bladder area, and abnormal swimming behavior. Compared to the control group, zebrafish larvae in the 1 and 10 μg/L EMB exposure groups showed a significant reduction in distance travelled of 18.3 % and 36.9 % and a significant increase in dwell time of 6.1 % and 17.1 %. Analysis of neurodevelopment and gene expression in the F1 generation revealed that EMB exposure diminished the development of the central nervous system and further aggravated developmental toxicity through pathways such as oxidative stress, inflammatory response, apoptosis. Notably, maternal exposure to EMB exerted a more significant impact on developmental and neurotoxic effects in the offspring. This study demonstrated that long-term EMB exposure causes significant parental reproductive and offspring neurodevelopmental toxicity in aquatic organisms, thus highlighting the importance of environmental risk assessment and pollution control.

Epicatechin attenuates emamectin benzoate-induced liver injury in grass carp by activating Nrf2/GPX4 signaling pathway

Emamectin benzoate (EMB) is an antibiotic insecticide pesticide modified from avermectin. In the current study, we performed an in-depth investigation of the protective effects of epicatechin on EMB-induced liver injury in common carps. The carps were cultured in an aquatic environment containing 2.4 μg/L of EMB for 30 days to establish the model. The results provide direct evidence that epicatechin could attenuate EMB-induced liver injury, as confirmed by the inhibition of epicatechin on EMB-induced liver pathological injury, serum glucose (GLU), cortisol (COR), aspartate aminotransferase (AST), alanine aminotransferase (ALT), adenosine deaminase (ADA), and alkaline phosphatase (ALP) levels. Epicatechin also inhibited EMB-induced inflammation, as confirmed by the inhibition of epicatechin on tumor necrosis factor (TNF-α) and Interleukin-1β (IL-1β) production, and nuclear factor kappa-B (NF-κB) activation induced by EMB. Moreover, epicatechin could attenuate EMB-induced ferroptosis, as confirmed by the inhibition of epicatechin on malondialdehyde (MDA) and Fe2+ production, and up-regulation of Adenosine Triphosphate (ATP), Glutathione (GSH) production, and Glutathione Peroxidase 4 (Gpx4) and xCT expression. In addition, epicatechin increased the expression of nuclear factor erythroid-2 related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1). We therefore conclude that epicatechin protected EMB-induced liver injury by preventing ferroptosis through activating Nrf2.

Investigate the binding of pesticides with the TLR4 receptor protein found in mammals and zebrafish using molecular docking and molecular dynamics simulations

The widespread use of pesticides poses significant threats to both environmental and human health, primarily due to their potential toxic effects. The study investigated the cardiovascular toxicity of selected pesticides, focusing on their interactions with Toll-like receptor 4 (TLR4), an important part of the innate immune system. Using computational tools such as molecular docking, molecular dynamics (MD) simulations, principal component analysis (PCA), density functional theory (DFT) calculations, and ADME analysis, this study identified C160 as having the lowest binding affinity (-8.2 kcal/mol), followed by C107 and C165 (-8.0 kcal/mol). RMSD, RMSF, Rg, and hydrogen bond metrics indicated the formation of stable complexes between specific pesticides and TLR4. PCA revealed significant structural changes upon ligand binding, affecting stability and flexibility, while DFT calculations provided information about the stability, reactivity, and polarity of the compounds. ADME studies highlighted the solubility, permeability, and metabolic stability of C107, C160, and C165, suggesting their potential for bioavailability and impact on cardiovascular toxicity. C107 and C165 exhibit higher bioactivity scores, indicating favourable absorption, metabolism, and distribution properties. C165 also violated rule where molecular weight is greater than 500 g/mol. Further, DFT and NCI analysis of post MD conformations confirmed the binding of ligands at the binding pocket. The analysis shed light on the molecular mechanisms of pesticide-induced cardiovascular toxicity, aiding in the development of strategies to mitigate their harmful effects on human health.

Trace-level Gabapentin can induce cardiovascular developmental toxicity through apoptosis in zebrafish larvae

Gabapentin (GBP), an antiepileptic drug to treat epilepsy and neuropathic pain, has become an emerging pollutant in aquatic environments. Previous results suggested that GBP can cause a potential toxicity on the heart development of zebrafish but its cardiovascular effects are still not clear. In the current study, zebrafish embryos were exposed to GBP at environmental relevant concentrations (0, 0.1, 10 and 1000 μg/L) to assess its impact on cardiovascular systems during the early life stage of zebrafish. GBP exposure induced an increase in heartbeat rate and blood flow. The development of blood vessels was also affected with the vascular width significantly decreased at 10 μg/L and higher concentration of GBP. GBP exposure led to an abnormal vascular development by inhibiting the expression of relevant genes (flk1, vegfr-3, gata1, vegfα, and vegfr-2). Furthermore, GBP at 0.1 μg/L elevated the levels of reactive oxygen species and antioxidant enzyme. The vascular cell apoptosis was promoted through genes like p53, bad, and bcl2. However, these adverse effects were reversible with the antioxidant N-acetyl-L-cysteine, highlighting the crucial role of oxidative damage in GBP induced vascular toxicity. This research offers new perspectives on the adverse outcome pathways of antiepileptic drugs in non-target aquatic organisms.

Avermectin induced vascular damage in zebrafish larvae: association with mitochondria-mediated apoptosis and VEGF/Notch signaling pathway

Avermectin is a highly effective insecticide that has been widely used in agriculture since the 1990s. In recent years, the safety of avermectin for non-target organisms has received much attention. The vasculature is important organs in the body and participate in the composition of other organs. However, studies on the vascular safety of avermectin are lacking. The vasculature of zebrafish larvae is characterized by ease of observation and it is a commonly used model for vascular studies. Therefore, zebrafish larvae were used to explore the potential risk of avermectin on the vasculature. The results showed that avermectin induced vascular damage throughout the body of zebrafish larvae, including the head, eyes, intestine, somite, tail and other vasculature. The main forms of damage are reduction in vascular diameter, vascular area and vascular abundance. Meanwhile, avermectin induced a decrease in the number of endothelial cells and apoptosis within the vasculature. In addition, vascular damage may be related to impairment of mitochondrial function and mitochondria-mediated apoptosis. Finally, exploration of the molecular mechanisms revealed abnormal alterations in the expression of genes related to the VEGF/Notch signaling pathway. Therefore, the VEGF/Notch signaling pathway may be an important mechanism for avermectin-induced vascular damage in zebrafish larvae. This study demonstrates the vascular toxicity of avermectin in zebrafish larvae and reveals the possible molecular mechanism, which would hopefully draw more attention to the safety of avermectin in non-target organisms.

Emamectin benzoate exposure induced carp kidney injury by triggering mitochondrial oxidative stress to accelerate ferroptosis and autophagy

Emamectin benzoate (EMB), commonly used as an insecticide in fishery production, inevitably leaves residual chemicals in aquatic environments. High-level EMB exposure can cause severe damage to multiple systems of marine animals, potentially through mechanisms involving severe mitochondrial damage and oxidative stress. However, it is not clear yet how EMB exposure at a certain level can cause damage to fish kidney tissue. In this study, we exposed carps to an aquatic environment containing 2.4 μg/L of EMB and cultured carp kidney cells in vitro, established a cell model exposed to EMB. Our findings revealed that EMB exposure resulted in severe kidney tissue damage in carp and compromised the viability of grass carp kidney cells (CIK cells). By RNA-seq analysis, EMB exposure led to significant differences in mitochondrial homeostasis, response to ROS, ferroptosis, and autophagy signals in carp kidney tissue. Mechanistically, EMB exposure induced mitochondrial oxidative stress by promoting the generation of mitochondrial superoxide and reducing the activity of antioxidant enzymes. Additionally, EMB exposure triggered loss of mitochondrial membrane potential, an imbalance in mitochondrial fusion/division homeostasis, and dysfunction in oxidative phosphorylation, ultimately impairing ATP synthesis. Notably, EMB exposure also accelerated excessive autophagy and ferroptosis of cells by contributing to the formation of lipid peroxides and autophagosomes, and the deposition of Fe2+. However, N-acetyl-L-cysteine (NAC) treatment alleviated the damage and death of CIK cells by inhibiting oxidative stress. Overall, our study demonstrated that EMB exposure induced mitochondrial oxidative stress, impaired mitochondrial homeostasis, and function, promoted autophagy and ferroptosis of kidney cells, and ultimately led to kidney tissue damage in carp. Our research enhanced the toxicological understanding on EMB exposure and provides a model reference for comparative medicine.

New insights into resveratrol attenuates hepatotoxicity in emamectin benzoate-exposed grass carp (Ctenopharyngodon idella) via NO system/NF-κB signaling pathway

Emamectin benzoate (EMB) is extensively used as a crop protection agent. Overuse of EMB poses a serious threat to the quality of water and non-target organisms in the environment. Resveratrol (RES) is a natural phytoalexin with the function of anti-oxidation and anti-inflammation. Nonetheless, it is unclear whether EMB affects the expression of cytokines and induces autophagy, apoptosis, and necroptosis of hepatocytes (L8824 cell) in grass carp (Ctenopharyngodon idella), and whether RES has an attenuate function in this process. Therefore, we established the L8824 cells model of EMB exposure and treated it with RES. The results showed that compared with the control (CON) group, EMB exposure significantly increased the nitric oxide (NO) content, inducible nitric oxide synthase (iNOS) activity, and the expression of iNOS and phosphorylated nuclear factor kappa B (p-NF-κB) (P < 0.05). In addition, compared with the CON group, the results of flow cytometry and dansylcadaverine (MDC) staining showed a significant increase in apoptosis and autophagy in the EMB-exposed group (P < 0.05) with the activation of the B-cell lymphoma-2 (Bcl-2)/Bcl-2 associated X (Bax)/cysteine-aspartic acid protease 3 (Caspase-3)/cysteine-aspartic acid protease 9 (Caspase-9) pathway and microtubule-associated protein light chain 3 (LC3)/sequestosome 1 (p62)/Beclin1 pathway. EMB exposure significantly increased the mRNA and protein expression of receptor-interacting protein 1 (RIPK1)/receptor-interacting protein 3 (RIPK3)/mixed the lineage kinase domain-like (MLKL) pathway (P < 0.05). Moreover, EMB exposure significantly increased the expression of genes related to immunity (immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin D (IgD), and antimicrobial peptide-related genes expression including β-defensin and hepcidin) (P < 0.05). The addition of RES significantly diminished autophagy, apoptosis, necroptosis, and immunity-related gene expression by inhibiting iNOS activity, NO content, and the protein expression of iNOS and p-NF-κB. In conclusion, RES attenuated autophagy, apoptosis, and necroptosis in EMB-exposed L8824 cells via suppression of the NO system/NF-κB signaling pathway.

Myclobutanil induces cardiotoxicity in developing zebrafish larvae by initiating oxidative stress and apoptosis: The protective role of curcumin

Myclobutanil (MYC) is a common triazole fungicide widely applied in agriculture. MYC extensively exists in the natural environment and can be detected in organisms. However, little is known about MYC-induced embryonic developmental damage. This study aimed to unravel the cardiotoxicity of MYC and the underlying mechanisms, as well as the cardioprotective effect of curcumin (CUR, an antioxidant polyphenol) using the zebrafish model. Here, zebrafish embryos were exposed to MYC at concentrations of 0, 0.5, 1 and 2 mg/L from 4 to 96 h post fertilization (hpf) and cardiac development was assessed. As results, MYC reduced the survival and hatching rate, body length and heart rate, but increased the malformation rate and spontaneous movement. MYC caused abnormal cardiac morphology and function in myl7:egfp transgenic zebrafish, and downregulated cardiac developmental genes. MYC promoted oxidative stress through excessive reactive oxygen species (ROS) accumulation and suppressed the activities of antioxidant enzymes, triggering cardiomyocytic apoptosis via upregulated expression of apoptosis-related genes. These adverse toxicities could be significantly ameliorated by the antioxidant properties of CUR, indicating that CUR rescued MYC-induced cardiotoxicity by inhibiting oxidative stress and apoptosis. Overall, our study revealed the potential mechanisms of oxidative stress and apoptosis in MYC-induced cardiotoxicity in zebrafish and identified the cardioprotection of CUR in this pathological process.

Substantial removal of four pesticide residues in three fruits with ozone microbubbles

Developing a straightforward method to remove pesticide residues from fruits is essential for food safety. In this study, ozone microbubble treatment was performed on three fruits (strawberry, cherry, and apricot) to remove four pesticide residues (emamectin benzoate, azoxystrobin, boscalid, and difenoconazole) while comparing removal efficiency. The concentration of hydroxyl radicals in different washing orientations was homogeneous at a concentration ranging between 8.9 and 10.2 μmol·L-1. Under long washing time (18 min), strawberry, cherry, and apricot obtained higher removal rates of 51 %∼65 %, 51 %∼59 % and 24 %∼70 %, respectively. Moreover, scanning electron microscopy (SEM) and contact angle (CA) revealed that apricot has better hydrophobicity, leading to a higher pesticide removal of 45 ∼ 84 % with less water and more vigorous washing. Notably, vitamin C content in fruits remain largely unchanged following ozone microbubble treatment. This study demonstrated the effectiveness of ozone microbubble treatment as pollution-free method for enhancing food safety by removing pesticide residues on fruits.

Proteomic and cardiac dysregulation by representative perfluoroalkyl acids of different chemical speciation during early embryogenesis of zebrafish

Perfluoroalkyl acids (PFAAs) of different chemical speciation were previously found to cause diverse toxicity. However, the toxicological mechanisms depending on chemical speciation are still largely unknown. In this follow-up study, zebrafish embryos were acutely exposed to only one concentration at 4.67 μM of the acid and salt of representative PFAAs, including perfluorooctanoic acid (PFOA), perfluorobutane carboxylic acid (PFBA), and perfluorobutanesulfonic acid (PFBS), till 96 h post-fertilization (hpf), aiming to gain more mechanistic insights. High-throughput proteomics found that PFAA acid and salt exerted discriminative effects on protein expression pattern. Bioinformatic analyses based on differentially expressed proteins underlined the developmental cardiotoxicity of PFOA acid with regard to cardiac muscle contraction, vascular smooth muscle contraction, adrenergic signaling in cardiomyocytes, and multiple terms related to myocardial contraction. PFOA salt and PFBS acid merely disrupted the cardiac muscle contraction pathway, while cardiac muscle cell differentiation was significantly enriched in PFBA acid-exposed zebrafish larvae. Consistently, under PFAA exposure, especially PFOA and PFBS acid forms, transcriptional levels of key genes for cardiogenesis and the concentrations of troponin and epinephrine associated with myocardial contraction were significantly dysregulated. Moreover, a transgenic line Tg (my17: GFP) expressing green fluorescent protein in myocardial cells was employed to visualize the histopathology of developing heart. PFOA acid concurrently caused multiple deficits in heart morphogenesis and function, which were characterized by the significant increase in sinus venosus and bulbus arteriosus distance (SV-BA distance), the induction of pericardial edema, and the decrease in heart rate, further confirming the stronger toxicity of PFOA acid than the salt counterpart on heart development. Overall, this study highlighted the developmental cardiotoxicity of PFAAs, with potency ranking PFOA > PFBS > PFBA. The acid forms of PFAAs induced stronger cardiac toxicity than their salt counterparts, providing an additional insight into the structure-toxicity relationship.