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Although pesticides commonly exist as combinations in real-life situations of the aquatic ecosystem, the impact of the toxicity of their mixtures has remained largely unclear. In this study, we investigated the combined effects of two neurotoxic pesticides, including one organophosphate insecticide phoxim (PHO) and one pyrethroid insecticide lambda -cyhalothrin (LCY), on the embryos of the small yellow croaker (Larimichthys polyactis), and their potential pathways. LCY exhibited higher toxicity relative to PHO, with a 72-h LC 50 value of 0.0074 mg a.i. L−1, while the corresponding value for PHO was 0.12 mg a.i. L−1. The mixture of PHO and LCY exerted a synergistic effect on the embryos of L. polyactis. The activities of antioxidant enzyme CAT and apoptotic enzyme caspase 3 were substantially changed in most single and combined exposure groups relative to the baseline value. Under both single and combined exposures, more significant changes were found in the mRNA expression of five genes, including the immunosuppression gene ngln2 , the apoptosis gene P53 , the endocrine system gene cyp19a1b , as well as neurodevelopment genes of ap and acp2 , relative to the baseline value. Furthermore, the non-target metabolomic analysis demonstrated that hundreds of differential metabolites, including two bile acids (taurodeoxycholic acid and tauroursodeoxycholic acid), were significantly increased in the exposure groups. The bile acids were closely associated with the gut microbiota, and 16S rRNA sequencing results demonstrated dysfunction of the gut microbiota after exposure, especially in the combined exposure group. Our findings indicated that there might be a potential risk connected to the co-occurrence of these two pesticides in aquatic vertebrates. Consequently, future ecological risk assessments should incorporate synergistic mixtures because the current risk assessments do not consider them. [Display omitted] • Lambda -cyhalothrin in combination with phoxim presented synergistic acute toxicity. • Expression levels of 5 genes in mixtures elicited greater changes than individuals. • More metabolites were discovered after mixture exposure than individual exposures. • Co-exposure caused most significantly varied microbiota at phylum and genus levels. • Synergistic effects should be incorporated into risk assessment of pesticide. [ABSTRACT FROM AUTHOR]

Pesticides commonly occur as mixtures in an aqueous environment, causing deleterious effects on human health and the environment. However, the mechanism underlying the combined effects on aqueous organisms remains largely unknown, especially at low concentrations. In the current study, we inspected the interactive toxicity of tebuconazole (TEB), a triazole fungicide, and bifenthrin (BIF), a pyrethroid insecticide, to zebrafish (Danio rerio) using various toxicological assays. Our data revealed that the 96 h-LC 50 (lethal concentration 50) values of BIF to fish at different life periods (embryonic, larval, juvenile, and adult periods) ranged from 0.013 (0.011–0.016) to 0.41 (0.35–0.48) mg a.i. L−1, which were lower than that of TEB ranging from 1.1 (0.88–1.3) to 4.8 (4.1–5.7) mg a.i. L−1. Combination of TEB and BIF induced synergetic acute toxicity to embryonic fish. Activities of T-SOD, POD, and GST were distinctly altered in most individual and joint administrations. Expressions of 16 genes associated with oxidative stress, cellular apoptosis, immune system, and endocrine system at the mRNA level were evaluated, and the information revealed that embryonic zebrafish were impacted by both individual compounds and their combinations. Six genes (cas9 , P53 , gr , TRα, IL-8, and cxcl-clc) exhibited greater changes when exposed to pesticide mixtures. Therefore, the joint effects induced by the pesticides at low concentrations should be considered in the risk assessment of mixtures and regulated as priorities for mixture risk management in the aqueous ecosystem. More research is needed to identify the threshold concentrations of the realistic pesticide mixtures above which synergistic interactions occur. [Display omitted] • Bifenthrin exhibited higher acute toxic effects than tebuconazole on the zebrafish. • Co-exposure of tebuconazole and bifenthrin elicited synergistic acute responses. • Synergistic oxidative stress, apoptosis and endocrine disrupting effects were observed. • Immune gene expressions (IL-8 and cxcl-clc) were significantly altered in mixtures. • Identification of single pesticides involved in synergism can benefit risk precautions. [ABSTRACT FROM AUTHOR]

The natural co-occurrence of multiple mycotoxins has been reported in cereals and cereal products worldwide. Even though the dietary exposure to mycotoxins constitutes a serious human health, most reports are limited to the toxic effect of individual mycotoxins. The purpose of the present study was to assess the combined toxic effects of zearalenone (ZEN) and fumonisin B1 (FB1) and the potential interaction of their mixture on zebrafish (Danio rerio) embryos. Our results showed that ZEN possessed the higher toxicity to embryonic zebrafish (7-day LC 50 value of 0.78 mg a.i. L−1) compared with FB1 (7-day LC 50 value of 227.7 mg a.i. L−1). The combination of ZEN and FB1 exerted an additive effect on zebrafish embryos. Meanwhile, the activities of antioxidant CAT, caspase-3, and detoxification enzyme CYP450, as well as the expressions of six genes (Mn-sod , cas9 , bax , cc-chem , ERα , and crh) associated with oxidative stress, cellular apoptosis, immune system, and endocrine system were prominently altered in the mixture exposure compared with the corresponding single treatment group of ZEN or FB1. Taken together, the regulatory standards of mycotoxins in food and feed should be updated based on the mixture effects of mycotoxins, and there is an increased need on effective detoxification methods for controlling and reducing the toxicity of multiple mycotoxins in animal feed and throughout the food supply chain. [Display omitted] • The natural co-occurrence of multiple mycotoxins is common in worldwide cereals. • Co-exposure of zearalenone and fumonisin B1 exhibited additive acute response. • Combined effects related to biochemical index changes were observed in the mixture. • Gene expression altered for oxidative stress, apoptosis, immune and endocrine system. • Regulatory standards of mycotoxins should take the mixture effects into account. [ABSTRACT FROM AUTHOR]

Pesticides scarcely exist as individual compounds in the water ecosystem, but rather as mixtures of multiple chemicals at relatively low concentrations. In this study, we aimed to explore the mixture toxic effects of fludioxonil (FLU) and triadimefon (TRI) on zebrafish (Danio rerio) by employing different toxicological endpoints. Results revealed that the 96-h LC 50 values of FLU to D. rerio at multiple developmental stages ranged from 0.055 (0.039–0.086) to 0.61 (0.33–0.83) mg L−1, which were less than those of TRI ranging from 3.08 (1.84–5.96) to 9.75 (5.99–14.78) mg L−1. Mixtures of FLU and TRI exerted synergistic effects on embryonic zebrafish. Activities of total superoxide dismutase (T-SOD) and catalase (CAT) were markedly altered in most of the individual and pesticide mixture treatments compared with the control. The expressions of 16 genes involved in oxidative stress, cellular apoptosis, immune system and endocrine system displayed that embryonic zebrafish were affected by the individual pesticides and their mixtures, and greater variations of four genes (ERɑ , Tnf , IL and bax) were found when exposed to pesticide mixtures compared with their individual compounds. Therefore, more studies on mixture toxicities among different pesticides should be taken as a priority when evaluating their ecological risk. Image 1 • Fludioxonil elicited higher toxicity than triadimefon to zebrafish. • Mixtures of fludioxonil and triadimefon displayed synergistic response on zebrafish. • Expressions of 4 genes exerted greater changes in mixtures compared with individuals. • Mixture toxic effects should be incorporated into the risk assessment of pesticides. Mixture toxicity and potential mechanism of fludioxonil and triadimefon to the zebrafish. [ABSTRACT FROM AUTHOR]

Pesticides often occur as mixtures of complex compounds in water environments, while most of studies only focus on the toxic effects of individual pesticides with little attention to the joint toxic effects. In the present study, we aimed to the mixture toxicity of beta -cypermethrin (BCY) and thiacloprid (THI) to zebrafish (Danio rerio) employing multiple toxicological endpoints. Results displayed that the 96-h LC 50 values of BCY to D. rerio at various developmental stages ranged from 2.64 × 10 (1.97 × 10–3.37 × 10) to 6.03 × 103 (4.54 × 103–1.05 × 104) nM, which were lower than those of THI ranging from 2.97 × 104 (1.96 × 104–4.25 × 104) to 2.86 × 105 (2.19 × 105–5.87 × 105) nM. Mixtures of BCY and THI exhibited synergistic response in embryonic zebrafish. Meanwhile, the enzyme activities of antioxidants (CAT and SOD) and detoxification enzyme (CarE), endogenous T-GSH and MDA contents, as well as gene expressions (tsh , crh , cxcl and bax) involved in oxidative stress, cellular apoptosis, immune system and endocrine system were obviously changed in the mixture exposure compared with the respective BCY or THI treatment. Consequently, the increased toxicity of pesticide mixture suggested that the toxicological data acquired from individual pesticide tests might underrate the toxicity risk of pesticides that actually arise in the real environment. Taken together, our present study provided evidence that mixture exposure of BCY and THI could induce additional toxic effect compared with their respective individual pesticides on D. rerio , offering valuable insights into the toxic mechanism of pesticide mixture. Image 1 • Beta -cypermethrin exerted greater toxicity than thicloprid to zebrafish. • Mixtures of beta -cypermethrin and thicloprid had synergistic effect on zebrafish. • Expressions of 4 genes exerted greater changes in pesticide mixtures. • Mixture effects should be considered in the ecological risks of pesticide. Synergistic effects and underlying mechanism of beta -cypermethrin and thiacloprid on zebrafish. [ABSTRACT FROM AUTHOR]

Despite the current efforts to identify the mixtures of chemical pollutants, they are often "binned" into their corresponding pollutant groups. Limited studies have investigated complex mixtures of chemical pollutants co-occurring across different groups. The combined toxic impacts of several substances become a critical consideration in toxicology because chemical combinations can exert a greater deleterious effect than the single components in the mixture. In the current work, we assessed the joint impacts of ochratoxin A and tricyclazole on the zebrafish (Danio rerio) embryos and explored their underlying signaling pathways. Ochratoxin A displayed higher toxicity than tricyclazole, with a 10-day LC 50 of 0.16 mg L−1, whereas that for tricyclazole was 1.94 mg L−1. The combination of ochratoxin A and tricyclazole exhibited a synergistic impact on D. rerio. The activities of detoxification enzymes GST and CYP450, as well as apoptosis-associated enzyme caspase 3, were distinctly changed in most individual and mixture exposures comparing to the untreated group. Upon both individual and mixture exposures, more dramatic variations were detected in the expressions of nine genes, such as the apoptosis genes cas3 and bax , antioxidant gene mn-sod , immunosuppression gene il-1β , and the endocrine system genes trα , dio1 , trβ , ugtlab , and crh , compared with the untreated group. These findings suggested that the simultaneous exposure to low doses of mycotoxins and pesticides in food commodities was more toxic than predicted from the individual chemicals. Considering the frequent co-occurrence of mycotoxins and pesticides in the diet, this synergy should be considered in future assessments. [Display omitted] • Ochratoxin A had a higher toxicity to embryonic zebrafish than tricyclazole. • Ochratoxin A in combination with tricyclazole showed synergistic toxicity. • CarE had an important funcion in the synergism of ochratoxin A and tricyclazole. • Expression levels of 9 genes in mixtures showed greater changes than individuals. [ABSTRACT FROM AUTHOR]

Abstract: DNA damage caused by low dosage of avermectin was evaluated in hemocytes of silkworm (Bombyx mori) using the alkaline single-cell gel electrophoresis (SCGE). The fourth instar larvae of silkworm were exposed to avermectin by oral feeding with mulberry leaves treated on the three different concentrations. The hemocytes were collected at day 1, 3, 5, 7, 9 for assessment of DNA damage with tail DNA percent. Results showed that there was positive correlation between avermectin concentration and DNA damage in three tested treatments. The maximum value of tail DNA percent was observed at the third day, followed by a gradual non-linear decline. For better understanding the results of SCGE at transcription level, differentially expressed genes (DEGs) were explored in hemocytes of silkworm exposed to avermectin (1.0μg/l) using annealing control primer (ACP)-based PCR. 15 DEGs were screened and sequenced, among which 10 genes were up-regulated, 5 genes were down-regulated. These genes were related with DNA damage or DNA damage repair of hemocytes. [Copyright &y& Elsevier]