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Water environmental pollution caused by spent batteries is a nonignorable environmental issue. In this study, the early life stage of zebrafish was employed to assess the environmental risk of spent batteries after exposure to 0, 1%, 2%, 5% and 10% spent battery extract for 120 h. Our results clearly indicated that spent battery extract can significantly decrease the survival rate, hatching rate and body length and increase heart rate. Moreover, spent battery extract exposure-induced zebrafish larvae generate oxidative stress and inhibit the mRNA transcriptional levels of heat shock protein (HSP70) and metallothionein (MT) genes. These results showed that the spent batteries not only affected the survival and development performance of zebrafish at an early life stage but also caused oxidative stress and interfered with the detoxification of zebrafish. This study provided novel insight into spent battery induced toxicity in the early life stage of fish., (Copyright © 2021. Published by Elsevier Ltd.)

Gill, as the organ of fish to contact most directly with xenobiotics, suffered more threat. To evaluate the impact of arsenite (AsIII) on the gill of fish, we measured the antioxidative responses (superoxide dismutase (SOD) and catalase (CAT) activities) and oxidative damage (malondialdehyde (MDA) content), histological changes and mRNA transcriptional responses of zebrafish gill, after exposure to AsIII (0, 10, 50, 100, and 150 μg L -1 ) solutions for 28 days. We found that AsIII increased the activities of CAT by 46%-87%, decreased the activities of SOD and the contents of MDA by 19% and 21%-32%. Furthermore, CuZnSOD and MnSOD mRNA transcription levels were also inhibited, decreasing by 62%-82% and 70%-77%. Besides, ≥ 100 μg L -1 AsIII also caused histological changes (a loss of mucus and desquamation in the surface of the epithelial cells) on zebrafish gill. These results showed that low concentrations of AsIII influenced biochemical and physiological performances of fish gill, which probably aggravates the toxic effect of AsIII on fish., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Arsenic (As) present in water is a nonignorable environmental issue, even at low concentrations (≤150 μg L -1 ). To evaluate the toxic effect of low concentrations of As, zebrafish at early life stage were exposed to 0, 25, 50, 75, or 150 μg L -1 AsIII for 120 h. Our results indicated that low concentration of AsIII decreased zebrafish larvae's survival rate to 85%, 89% and 86% at 50, 75 and 150 μg L -1 . Furthermore, low concentrations of AsIII exposure caused oxidative stress (elevated superoxide dismutase (SOD) activity and influenced the mRNA transcriptional levels of Cu/ZnSOD and MnSOD) and damage (increased malondialdehyde levels). Meanwhile, zebrafish larvae regulated the mRNA transcription of metallothionein and heat shock protein 70 to alleviate toxicity caused by AsIII. These results revealed lower concentrations (≤150 μg L -1 ) of AsIII had a detriment effect on the survival of fish at early life stage, moreover, oxidative stress caused by AsIII posed potential risk for the zebrafish. This study provides novel insight into low concentration AsIII-induced toxicity in zebrafish., (Copyright © 2019. Published by Elsevier Ltd.)

To evaluate the impact of DCAcAm on zebrafish gill, we measure the responses of antioxidant enzyme (superoxide dismutase, SOD), lipid peroxidation (malondialdehyde, MDA), ATPase (Na + /K + -ATPase and Ca 2+ /Mg 2+ -ATP) and histopathological changes of gill in adult zebrafish, after exposed to different concentrations of DCAcAm (0, 1, 10, 100, and 1000 μg L -1 ) for 30 days. Results indicated that DCAcAm first increased and then decreased SOD activity, and DCAcAm also lowered the activities of Na + /K + -ATPase and Ca 2+ /Mg 2+ -ATPase. These results indicated that high affinity of DCAcAm probably be a main factor, which can damage the structures of enzymes, thereby inhibiting the SOD and ATPase activities. Besides, histopathological investigation results also manifested that chronic exposure to DCAcAm can damage the gill tissues, disrupting the normal function of gills. We conclude that chronic exposure to DCAcAm was harmful to organisms, not only influence gill function, but also further cause damage on the gill tissues., (© 2019 Wiley Periodicals, Inc.)

2,6-dichlorobenzoquinone (2,6-DCBQ), an emerging disinfection by-production, frequently occurs in reclaimed water and drinking water. However, limited information was available regarding its toxicity. To evaluate its impact, zebrafish at early life stage were exposed to 0, 10, 30, 60, 90, or 120 μg L -1 2,6-BDCQ for 72 h. Our results indicated that 2,6-BDCQ decreased zebrafish's survival rate to 65% and 44% at 90 and 120 μg L -1 treatments and increased its aberration rate to 11% and 26% at 90 μg L -1 and 120 μg L -1 treatments. Besides, 2,6-BDCQ had adverse effect on its oxidative stress (elevated superoxide dismutase activity), lipid peroxidation (increased malondialdehyde levels), DNA damage (increased 8-hydroxydeoxyguanosine contents) and apoptosis (increased caspase-3 activity). Although lower concentrations (≤60 μg L -1 ) of 2,6-BDCQ didn't exhibit significant effect on its survival development or lipid peroxidation of zebrafish, they induced obvious DNA damage and apoptosis occurrence. These results revealed 2,6-BDCQ caused genotoxicity and cytotoxicity to zebrafish. This study provides novel insight into 2,6-DCBQ-induced toxicity in zebrafish., (Copyright © 2018. Published by Elsevier Ltd.)

Arsenic contamination in drinking water is a worldwide issue, posing threat to human health. Arsenic is an endocrine system disruptor, however, limited information is available regarding its long-term effects on thyroid endocrine system at low exposure. In this study, we assessed the thyroid toxicity of arsenate (AsV) and arsenite (AsIII) at 10-100 μg L -1 in juvenile mice after 8-week of exposure via drinking water. After 1-2 week, AsV and AsIII had little influence on thyroxine (T4) level (56.3-64.7 μg L -1 ) in mouse blood compared to control mice at 57.3-60.7 μg L -1 . However, after 4-8 weeks, 10 μg L -1 AsIII or AsV increased T4 levels to 83.8-88.8 μg L -1 compared to control treatment at 77.2-80.0 μg L -1 , while 100 μg L -1 AsV or AsIII decreased T4 levels except for 100 μg L -1 AsIII for 8 weeks. Based on transmission electron microscopy, exposure to 100 μg L -1 AsIII or AsV for 8 weeks caused thyroid gland damage. In addition, exposure to AsV or AsIII at 10 or 100 μg L -1 impacted gene transcription of hypothalamic-pituitary-thyroid axis including thyroid stimulating hormone and iodothyronine deiodinases. Our data demonstrated that exposing to low levels of AsIII or AsV disrupted T4 homeostasis, influenced the related gene transcription and damaged the thyroid glands in juvenile mice., (Published by Elsevier Ltd.)

Rice can take up and translocate more As and Hg than other cereal crops. A hydroponic experiment was conducted to investigate their interactive effects on their uptake and toxicity in rice seedling after exposing to As(III) (0.1, 0.5 or 2.5 mg L−1) and Hg (0.05, 0.25 or 1.25 mg L−1) for 14 d. Rice was much more effective in taking up Hg than As and sequestered both in the roots. As and Hg reached 339 and 433 mg kg−1 in the roots, and 48.5 and 16.1 mg kg−1 in the shoots at As2.5 + Hg1.25. Though Hg inhibited As uptake and translocation, it enhanced As(III) toxicity to rice seedling. However, As inhibited Hg uptake at Hg0.05, but the opposite was observed at Hg0.25 and Hg1.25. Arsenite (54–100%) and inorganic Hg (100%) were the predominant form in the plant based on speciation analysis via HPLC–ICP–MS. Malondialdehyde in the roots and shoots increased with increasing As and Hg concentrations, with the highest being 54 μmol g−1 at As0.5 + Hg1.25 in the roots. Root cell structural damage and organelles number reduction with increasing As and Hg concentration were observed based on TEM. As and Hg transformation and toxicity can help to understand the metabolic mechanisms of As and Hg in rice plant when co-present.