Reproductive toxicity of long-term exposure to environmental relevant concentrations of cyprodinil in female zebrafish (Danio rerio)

The effect of abamectin exposure on gametogenesis in zebrafish

Today, pesticides are widely used to enhance agricultural yield mixed with soil and water, creating significant environmental pollution. The extensive use of insecticides for pest control has made this issue more pronounced. Abamectin, a key member of the avermectin family, is used as an insecticide and an antihelminthic agent in agriculture. It is an active and effective agricultural pesticide, particularly preferred for combating pests such as aphids and red spider mites. The dosage and frequency of its use vary depending on the target plant species and pest organism. For example, abamectin-based products with an 18 g/L EC formulation in apple orchards are typically recommended at 10 ml/100 L of water to control red spider mites. Although significantly below agricultural application levels, the low dose of 0.75 µg L⁻1 used in our study has demonstrated effects that cannot be overlooked. However, it can contaminate aquatic environments, posing harmful effects on organisms. Studies indicate that abamectin exposure may lead to serious health issues, showing toxic and reproductive toxicity effects in aquatic species. Examining abamectin's effects on testicular tissue revealed hypertrophy of Sertoli cells in the group exposed to 0.75 µg L⁻1 of abamectin. Apoptotic cells were observed in the groups exposed to 0.75 µg L⁻1 and 1.5 µg L⁻1. At the same time, pyknotic structures, disruption of seminiferous tubules, interstitial fibrosis, and atrophic appearance were identified across all dose groups, with severity increasing dose-dependently. Analysis of ovarian tissue demonstrated distortion of the zona radiata in groups exposed to 0.75 µg L⁻1 and 1.5 µg L⁻1 of abamectin. Moreover, in all dose groups, thickening of the zona radiata, vacuolization, formation of degenerated follicles, and nuclear disruption were observed, with these pathological alterations exacerbating in a dose-dependent manner. Like many studies involving zebrafish, this research is crucial for assessing potential toxic effects that may pose risks to human health. This study examined the histopathological effects of varying doses of abamectin (0.75 µg L⁻1, 1.5 µg L⁻1, and 3 µg L⁻1) on zebrafish gonads after 96 h of exposure. Using standard histological techniques, the samples prepared were stained with H&E and observed under a light microscope. Statistical analyses were conducted using SPSS 23. The normality of the data was assessed with the Shapiro-Wilk test. One-way ANOVA and Tukey post-hoc tests were used for normally distributed groups, while the Kruskal-Wallis and Dunnett's T3 tests were applied for non-normally distributed groups. All analyses were performed with a 95% confidence interval and a significance level of p > 0.05.

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.

Leveraging zebrafish models for advancing radiobiology: Mechanisms, applications, and future prospects in radiation exposure research

Ionizing radiation (IR) represents a significant risk to human health and societal stability. To effectively analyze the mechanisms of IR and enhance protective strategies, the development of more sophisticated animal models is imperative. The zebrafish, with its high degree of genomic homology to humans and the capacity for whole-body optical visualization and high-throughput screening, represents an invaluable model for the study of IR. This review examines the benefits of utilizing zebrafish as a model organism for research on IR, emphasizing recent advancements and applications. It presents a comprehensive overview of the methodologies for establishing IR models in zebrafish, addresses current challenges, and discusses future development trends. This paper provide theoretical support for elucidating the mechanisms of IR injury and developing effective treatment strategies.

Pesticide contamination and associated ecological risks in estuarine waters of Brazil's Legal Amazon

Pesticide contamination remains a significant environmental concern globally, with important implications for aquatic ecosystems. Despite being one of the world's largest pesticide consumers, monitoring and assessment of pesticide pollution are limited in Brazil, especially in sensitive regions like the Amazon. In this study, the occurrence and environmental risks of 8 pesticides of different classes, namely alachlor, atrazine, chlorfenvinphos, isoproturon, irgarol, simazine, diuron, and its transformation product DCPMU (1-(3,4-dichlorophenyl)-3-methyl urea) were analysed in surface water of the São Marcos Estuarine Complex (SMEC) in two consecutive years. The quantification of the target compounds was performed using ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS). Suspected and untargeted screening analyses with ultra-high-performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) was also conducted to identify transformation products (TPs) and additional pesticides in water samples. All target pesticides, except for alachlor, were found in at least one sampling campaign. The antifouling biocides irgarol and diuron were ubiquitous in 2018 and 2019, with detection frequencies varying between 81 and 100% and maximum concentrations of 13.6 ng L-1 and 17.1 ng L-1, respectively. In 2019, the detection frequencies of the target pesticides were considerably higher than in 2018, with atrazine, isoproturon, and DCPMU being found in 100% of the samples. In 2019, chlorfenvinphos and isoproturon were the pesticides with the highest levels, reaching 48.6 ng L-1 and 44.6 ng L-1, respectively. The UHPLC-HRMS analysis showed the presence of the pesticides DEET (N,N-diethyl-meta-toluamide), octhilinone (2-Octyl-4-isothiazolin-3-one), and cyprodinil (4-cyclopropyl-6-methyl-N-phenylpyrimidin-2-amine) in water samples. Additionally, the TPs 2-hydroxy-atrazine, didemethylisoproturon (1-(4-isopropylphenyl)urea) and M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) were found. The environmental risk assessment showed that irgarol was the primary contributor to the global risk quotient in the SMEC region. Similarly, chlorfenvinphos also showed a high risk to the local aquatic biota, especially in 2019. This research not only highlights the urgent need for improved pesticide monitoring in Brazil but also establishes a baseline for future studies and environmental management efforts in SMEC. We emphasize the importance of prioritising pollutants and implementing effective mitigation strategies to protect the fragile aquatic ecosystems of the Brazilian Amazon.

Toxicity of parental co-exposure of microplastic and bisphenol compounds on adult zebrafish: Multi-omics investigations on offspring

In recent years, the widespread use of bisphenol compounds and microplastics (MP) have attracted attention due to their harmful effects. Here, individual and combined effects of MP and bisphenol compounds, were assessed on adult zebrafish after co-exposure of bisphenol A (BPA) or bisphenol S (BPS) and 25 μm polyethylene MP. Impacts on their offspring (the F1 generation) were also investigated. The reproductive toxicity in adult zebrafish impacted exerted by bisphenol compounds were aggravated by the co-presence of MP. Transcriptomics and metabolomics further showed single or co-exposure of bisphenol compounds and MP could together regulate apoptosis, calcium signaling pathway and glycerophospholipid signaling pathways. Our results also showed the different toxicity mechanisms on transcriptional and metabolic profiles in the combination effects of bisphenol compounds and MP. The co-exposure of BPA and MP predominantly influenced neurotoxicity via the MAPK signaling pathway and voltage-dependent calcium channels, whereas the co-exposure of BPS and MP principally affected visual development through phototransduction and retinol metabolism. The co-exposure of BPA and MP, as well as BPS and MP, specifically regulate lipid metabolism and carbohydrate metabolism in zebrafish offspring, respectively. Overall, this study provided a deep understanding of the toxicity differences between co-exposure and single exposure of bisphenol compound and MP in zebrafish, as well as the transgenerational effects and potential molecular mechanisms of bisphenol compounds and MP in zebrafish offspring.

Transcriptomic analysis reveals decreased expression of detoxification genes in Caenorhabditis elegans exposed to mepanipyrim and cyprodinil: Implications for multigenerational exposure effects

The broad-spectrum fungicides mepanipyrim (Mep) and cyprodinil (Cyp) have been reported to be used worldwide to control gray mold of fruit crops. Consequently, they are often detected in the water and food items. However, the impacts and potential mechanisms of these two pesticides on environmental organisms remain unclear. Utilizing Caenorhabditis elegans (C. elegans) as the model, the toxic effects and mechanisms were analyzed after Mep and Cyp exposure over four generations (P0-F3). The results showed that Mep and Cyp at concentrations over 0.1 µg/L affected the motility behavior, while 1.0 µg/L dosage and above inhibited the growth of C. elegans. In addition, multigenerational exposure could significantly impair both locomotion and development of C. elegans even at 0.01 µg/L dosage. Notably, constant exposure resulted in the function abnormalities of cholinergic, dopaminergic and GABAergic neurons, as well as the accumulation of ROS. Further transcriptome analysis showed reduced expression of 14 genes and 26 genes in xenobiotic metabolic pathway following Mep and Cyp exposure, respectively. The buildup of Mep/Cyp and ROS might have led to nerve impairment and behavioral abnormality. These findings enhanced understanding of the toxic effects of Mep and Cyp and provided insights into their eco-toxicological evaluation.

Long-term exposure to aryl hydrocarbon receptor agonist neburon induces reproductive toxicity in male zebrafish (Danio rerio)

Neburon is a phenylurea herbicide that is widely used worldwide, but its toxicity is poorly studied. In our previous study, we found that neburon has strong aryl hydrocarbon receptor (AhR) agonist activity, but whether it causes reproductive toxicity is not clear. In the present study, zebrafish were conducted as a model organism to evaluate whether environmental concentrations of neburon (0.1, 1 and 10 µg/L) induce reproductive disorder in males. After exposure to neburon for 150 days from embryo to adult, that the average spawning egg number in high concentration group was 106.40, which was significantly lower than 193.00 in control group. This result was mainly due to the abnormal male reproductive behavior caused by abnormal transcription of genes associated with reproductive behavior in the brain, such as secretogranin-2a. The proportions of spermatozoa in the medium and high concentration groups were 82.40% and 83.84%, respectively, which were significantly lower than 89.45% in control group. This result was mainly caused by hormonal disturbances and an increased proportion of apoptotic cells. The hormonal disruption was due to the significant changes in the transcription levels of key genes in the hypothalamus-pituitary-gonadal axis following neburon treatment. Neburon treatment also significantly activated the AhR signaling pathway, causing oxidative stress damage and eventually leading to a significant increase in apoptosis in the exposed group. Together, these data filled the currently more vacant profile of neburon toxicity and might provide information to assess the ecotoxicity of neburon on male reproduction at environmentally relevant concentrations.

Letrozole induced a polycystic ovary syndrome model in zebrafish by interfering with the hypothalamic-pituitary-gonadal axis

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disease in women of childbearing age, with an incidence of 5-10%. This study compared the traits of zebrafish with three diagnostic criteria for human PCOS, and the diagnostic criteria for zebrafish PCOS were proposed: decreased fecundity, elevated testosterone (T) or 11-ketotestosterone (11-KT) levels and increased cortical-alveolar oocyte (CO) ratio, enhancing the zebrafish PCOS model's accuracy. According to the mammalian PCOS classification, the type of zebrafsh PCOS is divided into four phenotypes (A, B, C and D), but the four phenotypes of zebrafish PCOS are not fully covered in the existing studies (A and D). In this study, we successfully induced phenotype B zebrafish PCOS model using the aromatase inhibitor, letrozole (LET). That is, wild-type female zebrafish were exposed to 1000 μg/L LET for 30 days. Reproductive tests showed decreased fecundity in female zebrafish exposed to LET (Control: 132.63, 146.00, 173.00; LET: 29.20, 90.00, 82.71). Hormone analysis showed that female zebrafish exposed to LET had significantly lower 17β-estradiol/testosterone (E2/T) ratios, indicating elevated T levels. Meanwhile, levels of 11-KT in the ovaries exposed to LET were significantly up-regulated (Control: 0.0076 pg/μg; LET: 0.0138 pg/μg). Pathological sections of the ovary showed fewer CO in the LET-exposed group (Control: 16.27%; LET: 8.38%). In summary, the zebrafish PCOS model summarized and studied in this study provide a reliable and economical tool for the screening of therapeutic drugs, as well as for the etiology research and treatment strategies of PCOS.

Frontier of toxicology studies in zebrafish model

Based on the 87 original publications only from quartiles 1 and 2 of Journal Citation Report (JCR) collected by the major academic databases (Science Direct, Web of Science, PubMed, and Wiley) in 2022, the frontier of toxicology studies in zebrafish model is summarized. Herewith, a total of six aspects is covered such as developmental, neurological, cardiovascular, hepatic, reproductive, and immunizing toxicities. The tested samples involve chemicals, drugs, new environmental pollutants, nanomaterials, and its derivatives, along with those related mechanisms. This report may provide a frontier focus benefit to researchers engaging in a zebrafish model for environment, medicine, food, and other fields.

Association between dietary pesticide exposure profiles and body weight change in French adults: Results from the NutriNet-Santé cohort

BACKGROUND

Pesticides cause a wide range of deleterious health effects, including metabolic disorders. Little is known about the effects of dietary pesticide exposure on body weight (BW) change in the general population. We aimed to investigate the role of dietary pesticide exposure in BW change among NutriNet-Santé participants, focusing on potential sexual dimorphism.

METHODS

Participants completed a Food Frequency Questionnaire (2014), assessing conventional and organic food consumption. Dietary exposure from plant foods of 25 commonly used pesticides was estimated using a residue database, accounting for agricultural practices (conventional and organic). Exposure profiles based on dietary patterns were computed using Non-negative Matrix Factorization (NMF). Mixed models were used to estimate the associations between BW change and exposure to pesticide mixtures, overall and after stratification by sex and menopausal status.

RESULTS

The final sample included 32,062 participants (8,211 men, 10,637 premenopausal, and 13,214 postmenopausal women). The median (IQR) follow-up was 7.0 (4.4; 8.0) years. Four pesticides profiles were inferred. Overall, men and postmenopausal women lost BW during follow-up, whereas premenopausal women gained BW. Higher exposure to NMF3, reflecting a lower exposure to synthetic pesticides, was associated with a lower BW gain, especially in premenopausal women (β(95 %CI) = -0.04 (-0.07; 0) kg/year, p = 0.04). Higher exposure to NMF2, highly positively correlated with a mixture of synthetic pesticides (azoxystrobin, boscalid, chlorpropham, cyprodinil, difenoconazole, fenhexamid, iprodione, tebuconazole, and lamda-cyhalothrin), was associated with a higher BW loss in men (β(95 %CI) = -0.05 (-0.08; -0.03) kg/year, p < 0.0001). No associations were observed for NMF1 and 4.

CONCLUSIONS

This study suggests a role of pesticide exposure, inferred from dietary patterns, on BW change, with sexually dimorphic actions, including a potential role of a lower exposure to synthetic pesticides on BW change in women. In men, exposure to a specific pesticide mixture was associated with higher BW loss. The underlying mechanisms need further elucidation.

Transgenerational effects of BDE-47 to zebrafish based on histomorphometry and toxicogenomic analyses

Exposure to 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47) has been found to have an impact on reproductive output and endocrine function in female zebrafish (Danio rerio). However, the transgenerational effects of BDE-47 have not been fully explored in previous reports. In this study, female zebrafish were exposed to BDE-47 for three consecutive weeks. The oogenesis, sex hormones, reproductive histology, and transcriptional profiles of genes along the hypothalamus-pituitary-gonad (HPG) axis were assessed in the exposed-F0 generation. After mating with unexposed males, the transgenerational effects of BDE-47 were evaluated on the basis of histopathology, morphometry and toxicogenome of the unexposed F1 generations at the larval stage. Results indicated that exposure to BDE-47 impaired reproductive capacity, disrupted endocrine system in F0 zebrafish, and compromised craniofacial skeletons and vertebrae development in F1 generations. In addition, through the use of toxicogenomics approach, immune-responsive pathways were found to be significantly enriched, and the transcript expression profiling of immune-related DEGs (IRDs) were dramatically inhibited in F1 generations following maternal BDE-47 exposure, indicating its immunotoxicity to offspring larvae. These findings advance our understanding of the transgenerational toxicity of BDE-47 and advocate for a more comprehensive assessment of other PBDE congeners through histomorphometry and toxicogenomic approaches.

Toxicity effects of pesticides based on zebrafish (Danio rerio) models: Advances and perspectives

Pesticides inevitably enter aquatic environments, posing potential risks to organisms. The common aquatic model organism, zebrafish (Danio rerio), are widely used to evaluate the toxicity of pesticides. In this review, we searched the Web of Science database for articles published between 2012 and 2022, using the keywords "pesticide", "zebrafish", and "toxicity", retrieving 618 publications. Furthermore, we described the main pathways by which pesticides enter aquatic environments and the fate of their residues in these environments. We systematically reviewed the toxicity effects of pesticides on zebrafish, including developmental toxicity, endocrine-disrupting effects, reproductive toxicity, neurotoxicity, immunotoxicity, and genotoxicity. Importantly, we summarized the latest research progress on the toxicity mechanism of pesticides to zebrafish based on omics technologies, including transcriptomics, metabolomics, and microbiomics. Finally, we discussed future research prospects, focusing on the combined exposure of multiple pollutants including pesticides, the risk of multigenerational exposure to pesticides, and the chronic toxicity of aquatic nanopesticides. This review provides essential data support for ecological risk assessments of pesticides in aquatic environments, and has implications for water management in the context of pesticide pollution.