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Contamination of drinking water by carcinogen arsenic (As) is of worldwide concern as its exposure poses potential threat to human health. As such, it is important to understand the mechanisms associated with As-induced toxicity to humans. The Nrf2/Keap1 signal pathway is one of the most important defense mechanisms in cells to counter oxidative stress; however, limited information is available regarding its role in countering As-induced stress in model animal mouse. In this study, we assessed the responses of Nrf2/keap1 pathway in mice after chronic exposure to As at environmentally-relevant concentrations of 10-200 μg L -1 for 30 days via drinking water. Our results indicate that chronic As exposure had limited effect on mouse growth. However, As induced oxidative stress to mice as indicated by increased content of malondialdehyde (MDA; 52-90%), an index of lipid peroxidation. Further, arsenic exposure reduced the activity of superoxide dismutase (SOD; 14-18%), an indication of reduced anti-oxidative activity. Besides, arsenic exposure increased MnSOD mRNA transcription by 25-66%, and decreased the mRNA transcriptions of Cu/ZnSOD by 72-83% and metallothionein by 16-75%, a cysteine-rich protein involved in metal detoxification. To counter arsenic toxicity, the expression of transcription factor for Nrf2 and Keap1 was increased by 2.8-8.9 and 0.2-8.1 fold in mice. To effectively reduce As-induced oxidative stress, the Nrf2/Keap1 transcription factor upregulated several downstream anti-oxidative genes, including heme oxygenase-1 (0.9-2.5 fold), glutamate-cysteine ligase catalytic subunit (0.6-1.7 fold), and NADH quinone dehydrogenase 1 (2.1-4.8 fold). This study shows the importance of Nrf2/Keap1 signaling pathway and associated anti-oxidative enzymes in countering As-toxicity in mice, possibly having implication for human health., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

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.)

Low concentrations of arsenic (As) contamination in aquatic environment is a worldwide issue, which is of great concern. To evaluate the impact of low concentrations of As on zebrafish, we measured the growth, antioxidant enzymes including superoxide dismutase (SOD) and catalase (CAT), oxidative damage (malondialdehyde, MDA) and apoptosis-related genes (nrf2, p53 and c-jun) of adult zebrafish after exposing to different AsIII concentrations (0, 10, 50, 100 or 150 μg L -1 ) for 28 d. Results indicated that exposure to low AsIII concentrations decreased the zebrafish weight by 14%, increased the activities of SOD and CAT by 23-41% and 31-59%, decreased the contents of MDA by 29-54%, and modulated transcription of apoptosis related genes. Our study showed that chronic exposure to AsIII concentrations <150 μg L -1 generated oxidative stress and damage on zebrafish, and altered apoptosis-related genes in zebrafish., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

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.