Reinvent Aliphatic Arsenicals as Reversible Covalent Warheads toward Targeted Kinase Inhibition and Non-acute Promyelocytic Leukemia Cancer Treatment

The success of arsenic in acute promyelocytic leukemia (APL) treatment is hardly transferred to non-APL cancers, mainly due to the low selectivity and weak binding affinity of traditional arsenicals to oncoproteins critical for cancer survival. We present herein the reinvention of aliphatic trivalent arsenicals (As) as reversible covalent warheads of As-based targeting inhibitors toward Bruton's tyrosine kinase (BTK). The effects of As warheads' valency, thiol protection, methylation, spacer length, and size on inhibitors' activity were studied. We found that, in contrast to the bulky and rigid aromatic As warhead, the flexible aliphatic As warheads were well compatible with the well-optimized guiding group to achieve nanomolar inhibition against BTK. The optimized As inhibitors effectively blocked the BTK-mediated oncogenic signaling pathway, leading to elevated antiproliferative activities toward lymphoma cells and xenograft tumor. Our study provides a promising strategy enabling rational design of new aliphatic arsenic-based reversible covalent inhibitors toward non-APL cancer treatment.

Iron oxide nanoparticles improving multimetal phytoextraction in Helianthus annuus

This study assessed the phytotoxicity of a mixture of five different trace elements (TEs) frequently found as pollutants in soils: arsenic, cadmium, copper, lead and zinc. On the other hand, the plant response to a magnetite (Fe3O4) nanoparticle amendment on this mixture as well as nanomagnetite remediation potential has been tested. Sunflower (Helianthus annuus) plants were grown for 90 days in soil contaminated with the five mentioned TEs at the limit levels of TEs in soils likely to receive sludge established by French legislation. Depending on the conditions, experimental set-ups were amended or not with 1% dry weight nanomagnetite (NPsMagn), citric acid-coated nanomagnetite (NPsMagn@CA) or micro-sized magnetite (μPs) in order to assess the behavior of nanomagnetites in a TEs-contaminated water-soil-plant system under repeated water-deficiency stress. The mixture of TEs did not induce phytotoxicity as estimated by plant growth, pigment content, maximum quantum yield of photosynthesis, oxidative impact and antioxidant response. Furthermore, both nanomagnetites treatments in a TEs-contaminated soil significantly increased biomass production by 64 % compared to control and antioxidant enzyme activities compared to control and TEs-treated plants. NPsMagn and NPsMagn@CA particularly enhance phytoextraction of Cd and Cu, increasing the amounts of TEs in aerial parts from 1.5 to 4.5 times compared to set-ups without nanomagnetites. Based on Cd, Cu, Pb and Zn contents in soil solutions, both nanomagnetites treatments improved TEs phytoextraction without increasing groundwater contamination. On the contrary, nanomagnetites significantly reduce arsenic uptake by plants and solubilization in dissolved phase. Our results show that modifying surface physicochemical properties of NPsMagn with citric acid coating does not improve their effects compared to bare NPsMagn. NPsMagn and NPsMagn@CA also appear to mitigate the effects of drought stress. This work highlights several positive environmental aspects related to the use of nanomagnetites in phytoremediation.

Novel insights into the co-selection of metal-driven antibiotic resistance in bacteria: a study of arsenic and antibiotic co-exposure

The simultaneous development of antibiotic resistance in bacteria due to metal exposure poses a significant threat to the environment and human health. This study explored how exposure to both arsenic and antibiotics affects the ability of an arsenite oxidizer, Achromobacter xylosoxidans CAW4, to transform arsenite and its antibiotic resistance patterns. The bacterium was isolated from arsenic-contaminated groundwater in the Chandpur district of Bangladesh. We determined the minimum inhibitory concentration (MIC) of arsenite, cefotaxime, and tetracycline for A. xylosoxidans CAW4, demonstrating a multidrug resistance (MDR) trait. Following this determination, we aimed to mimic an environment where A. xylosoxidans CAW4 was exposed to both arsenite and antibiotics. We enabled the strain to grow in sub-MIC concentrations of 1 mM arsenite, 40 µg/mL cefotaxime, and 20 µg/mL tetracycline. The expression dynamics of the arsenite oxidase (aioA) gene in the presence or absence of antibiotics were analyzed. The findings indicated that simultaneous exposure to arsenite and antibiotics adversely affected the bacteria's capacity to metabolize arsenic. However, when arsenite was present in antibiotics-containing media, it promoted bacterial growth. The study observed a global downregulation of the aioA gene in arsenic-antibiotic conditions, indicating the possibility of increased susceptibility through co-resistance across the entire bacterial population of the environment. This study interprets that bacterial arsenic-metabolizing ability can rescue the bacteria from antibiotic stress, further disseminating environmental cross-resistance. Therefore, the co-selection of metal-driven antibiotic resistance in bacteria highlights the need for effective measures to address this emerging threat to human health and the environment.

Hesperidin and chlorogenic acid mitigate arsenic-induced oxidative stress via redox regulation, photosystems-related gene expression, and antioxidant efficiency in the chloroplasts of Zea mays

The ubiquitous metalloid arsenic (As), which is not essential, can be found extensively in the soil and subterranean water of numerous nations, raising substantial apprehensions due to its impact on both agricultural productivity and sustainability. Plants exposed to As often display morphological, physiological, and growth-related abnormalities, collectively leading to reduced productivity. Polyphenols, operating as secondary messengers within the intricate signaling networks of plants, assume integral functions in the acquisition of resistance to diverse environmental stressors, including but not limited to drought, salinity, and exposure to heavy metals. The pivotal roles played by polyphenols in these adaptive processes underscore their profound significance in plant biology. This study aims to elucidate the impact of hesperidin (HP) and chlorogenic acid (CA), recognized as potent bioactive compounds, on maize plants exposed to As. To achieve this objective, the study examined the physiological and biochemical impacts, including growth parameters, photosynthesis, and chloroplastic antioxidants, of HP (100 μM) and CA (50 μM) on Zea mays plants exposed to arsenate stress (AsV, 100 μM - Na2HAsO4⋅7H2O). As toxicity led to reductions in fresh weight (FW) and dry weight (DW) by 33% and 26%, respectively. However, the application of As+HP and As + CA increased FW by 22% and 40% and DW by 14% and 17%, respectively, alleviating the effects of As stress. As toxicity resulted in the up-regulation of PSII genes (psbA and psbD) and PSI genes (psaA and psaB), indicating a potential response to the re-formation of degraded regions, likely driven by the heightened demand for photosynthesis. Exogenous HP or/and CA treatments effectively counteracted the adverse effects of As toxicity on the photochemical quantum efficiency of PSII (Fv/Fm). H2O2 content showed a 23% increase under As stress, and this increase was evident in guard cells when examining confocal microscopy images. In the presence of As toxicity, the chloroplastic antioxidant capacity can exhibit varying trends, with either a decrease or increase observed. After the application of CA and/or HP, a significant increase was observed in the activity of GR, APX, GST, and GPX enzymes, resulting in decreased levels of H2O2 and MDA. Additionally, the enhanced functions of MDHAR and DHAR have modulated the redox status of ascorbic acid (AsA) and glutathione (GSH). The HP or CA-mediated elevated levels of AsA and GSH content further contributed to the preservation of redox homeostasis in chloroplasts facing stress induced by As. In summary, the inclusion of HP and CA in the growth medium sustained plant performance in the presence of As toxicity by regulating physiological and biochemical characteristics, chloroplastic antioxidant enzymes, the AsA-GSH cycle and photosynthesis processes, thereby demonstrating their significant potential to confer resistance to maize through the mitigation of As-induced oxidative damage and the safeguarding of photosynthetic mechanisms.

Strigolactone and nitric oxide collaborate synergistically to boost tomato seedling resilience to arsenic toxicity via modulating physiology and antioxidant system

Arsenic (As) poses a significant environmental threat as a metalloid toxin, adversely affecting the health of both plants and animals. Strigolactones (SL) and nitric oxide (NO) are known to play crucial roles in plant physiology. Therefore, the present experiment was designed to investigate the potential cumulative role of SL (GR24-0.20 μM) and NO (100 μM) in mitigating the adverse effect of AsV (53 μM) by modulating physiological mechanisms in two genotypes of tomato (Riogrand and Super Strain 8). A sample randomized design with four replicates was used to arrange the experimental pots in the growth chamber. 45-d old both tomato cultivars under AsV toxicity exhibited reduced morphological attributes (root and shoot length, root and shoot fresh weight, and root and shoot dry weight) and physiological and biochemical characteristics [chlorophyll (Chl) a and b content, activity of δ-aminolevulinic acid dehydratase activity (an enzyme responsible for Chl biosynthesis), and carbonic anhydrase activity (an enzyme responsible for photosynthesis), and enhanced Chl degradation, overproduction of reactive oxygen species (ROS) and lipid peroxidation due to enhanced malondialdehyde (MDA) content. However, the combined application of SL and NO was more effective in enhancing the tolerance of both varieties to AsV toxicity compared to individual application. The combined application of SL and NO improved growth parameters, biosynthesis of Chls, NO and proline. However, the combined application significantly suppressed cellular damage by inhibiting MDA and overproduction of ROS in leaves and roots, as confirmed by the fluorescent microscopy study and markedly upregulated the antioxidant enzymes (catalase, peroxidase, superoxide dismutase, ascorbate dismutase and glutathione reductase) activity. This study provides clear evidence that the combined application of SL and NO supplementation significantly improves the resilience of tomato seedlings against AsV toxicity. The synergistic effect of SL and NO was confirmed by the application of cPTIO (an NO scavenger) with SL and NO. However, further molecular studies could be imperative to conclusively validate the simultaneous role of SL and NO in enhancing plant tolerance to abiotic stress.

Arsenic album 30C exhibits crystalline nano structure of arsenic trioxide and modulates innate immune markers in murine macrophage cell lines

Macrophages are associated with innate immune response and M1-polarized macrophages exhibit pro-inflammatory functions. Nanoparticles of natural or synthetic compounds are potential triggers of innate immunity. As2O3 is the major component of the homeopathic drug, Arsenic album 30C.This has been claimed to have immune-boosting activities, however, has not been validated experimentally. Here we elucidated the underlying mechanism of Ars. alb 30C-mediated immune priming in murine macrophage cell line. Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD) used for the structural analysis of the drug reveals the presence of crystalline As2O3 nanoparticles of cubic structure. Similarly, signatures of M1-macrophage polarization were observed by surface enhanced Raman scattering (SERS) in RAW 264.7 cells with concomitant over expression of M1 cell surface marker, CD80 and transcription factor, NF-κB, respectively. We also observed a significant increase in pro-inflammatory cytokines like iNOS, TNF-α, IL-6, and COX-2 expression with unaltered ROS and apoptosis in drug-treated cells. Enhanced expression of Toll-like receptors 3 and 7 were observed both in transcriptional and translational levels after the drug treatment. In sum, our findings for the first time indicated the presence of crystalline As2O3 cubic nanostructure in Ars. alb 30C which facilitates modulation of innate immunity by activating macrophage polarization.

Protective effects of macromolecular polyphenols, metals (zinc, selenium, and copper) - Polyphenol complexes, and different organs with an emphasis on arsenic poisoning: A review

For the potential health benefits and nutritional value, polyphenols are one of the secondary metabolites of plants that have received extensive research. It has anti-inflammatory and cytotoxicity-reducing properties in addition to a high antioxidant content. Macromolecular polyphenols and polysaccharides are biologically active natural polymers with antioxidant and anti-inflammatory potential. Arsenic is an ecologically toxic metalloid. Arsenic in drinking water is the most common way people come into contact with this metalloid. While arsenic is known to cause cancer, it is also used to treat acute promyelocytic leukemia (APL). The treatment's effectiveness is hampered by the adverse effects it can cause on the body. Oxidative stress, inflammation, and the inability to regulate cell death cause the most adverse effects. Polyphenols and other macromolecules like polysaccharides act as neuroprotectants by mitigating free radical damage, inhibiting nitric oxide (NO) production, lowering A42 fibril formation, boosting antioxidant levels, and controlling apoptosis and inflammation. To prevent the harmful effects of toxins, polyphenols and pectin lower oxidative stress, boost antioxidant levels, improve mitochondrial function, control apoptosis, and suppress inflammation. Therefore, it prevents damage to the heart, liver, kidneys, and reproductive system. This review aims to identify the effects of the polyphenols in conjugation with polysaccharides as an ameliorative strategy for arsenic-induced toxicity in various organs.

Macrophage-hitchhiked arsenic/AB bionic preparations for liver cancer

Macrophage-hitchhiked arsenic/AB bionic preparations were developed to improve the therapeutic effect on liver cancer by means of the tumor-targeting ability of macrophages in vivo. In vitro and in vivo cellular uptake assays demonstrated that arsenic/AB, with negatively charged particles of around 100-200 nm size, could hitchhike to macrophages. Dissolution experiments of arsenic/AB showed that arsenic/AB could delay the release of arsenic and ensure the safety of macrophages during its transport. Histological examination confirmed the safety of the preparations for major organs. In vivo distribution experiment showed that the arsenic/AB bionic preparations could rapidly accumulate in tumors, and in vivo treatment experiment showed a significant tumor inhibition of arsenic/AB. The therapeutic mechanism of liver cancer might be that the arsenic/AB bionic preparations could inhibit tumor growth by reducing inflammatory response and inhibiting CSF1 secretion to block CSF1R activation to induce more differentiation of tumor-associated macrophages (TAMs) towards the anti-tumor M1 phenotype. Therefore, we concluded that the arsenic/AB bionic preparations could improve the distribution of arsenic in vivo by hitchhiking on macrophages as well as make it have tumor targeting and deep penetration abilities, thus increasing the therapeutic effect of arsenic on liver cancer with reduced side effects.

Association of urinary arsenic with the oxidative DNA damage marker 8-hydroxy-2 deoxyguanosine: A meta-analysis

BACKGROUND

The International Agency for Research on Cancer has classified arsenic as a class I carcinogen. Oxidative DNA damage is a typical early precursor to recognized malignancies. The most sensitive early independent marker of oxidative DNA damage is believed to be 8-hydroxy-2 deoxyguanosine (8-OHdG). To date, research on the link between urinary arsenic and 8-OHdG has not been consistent.

OBJECTIVE

This study was aimed at exploring the effects of urinary arsenic on 8-OHdG in human urine.

METHODS

A literature search until January 2023 was performed on the PubMed, Cochrane Library, Web of Science, Embase, and Scopus databases through a combination of computer and manual retrieval. Stata 12.0 was used to examine the degree of heterogeneity among included studies. The percentage change and 95 % confidence interval (95 % CI) of 8-OHdG were calculated between populations exposed to different doses. We used a random effect model because the degree of heterogeneity exceeded 50 %. Sensitivity analysis and testing for publication bias were performed.

RESULTS

This meta-analysis included nine studies, most of which were performed in China. After exposure to arsenic, urinary arsenic (per 10 μg/g creatinine increase) was associated with the increased 8-OHdG (% change = 41.49 %, 95 % CI: 19.73 %, 63.25 %). Subgroup analysis indicated that the percentage change in 8-OHdG in urine was more pronounced in people exposed to arsenic <50 μg/L (% change = 24.60 %, 95 % CI: 17.35 %, 37.85 %). In studies using total urinary arsenic content as an indicator, the percentage change in 8-OHdG in urine was more significant (% change = 60.38 %, 95 % CI: 15.08 %, 105.68 %).

CONCLUSION

The 8-OHdG levels in human urine significantly increased after exposure to environmental arsenic, thus suggesting that arsenic exposure is correlated with oxidative DNA damage.

Structural Basis of PML-RARA Oncoprotein Targeting by Arsenic Unravels a Cysteine Rheostat Controlling PML Body Assembly and Function

PML nuclear bodies (NB) are disrupted in PML-RARA-driven acute promyelocytic leukemia (APL). Arsenic trioxide (ATO) cures 70% of patients with APL, driving PML-RARA degradation and NB reformation. In non-APL cells, arsenic binding onto PML also amplifies NB formation. Yet, the actual molecular mechanism(s) involved remain(s) elusive. Here, we establish that PML NBs display some features of liquid-liquid phase separation and that ATO induces a gel-like transition. PML B-box-2 structure reveals an alpha helix driving B2 trimerization and positioning a cysteine trio to form an ideal arsenic-binding pocket. Altering either of the latter impedes ATO-driven NB assembly, PML sumoylation, and PML-RARA degradation, mechanistically explaining clinical ATO resistance. This B2 trimer and the C213 trio create an oxidation-sensitive rheostat that controls PML NB assembly dynamics and downstream signaling in both basal state and during stress response. These findings identify the structural basis for arsenic targeting of PML that could pave the way to novel cancer drugs.

SIGNIFICANCE

Arsenic curative effects in APL rely on PML targeting. We report a PML B-box-2 structure that drives trimer assembly, positioning a cysteine trio to form an arsenic-binding pocket, which is disrupted in resistant patients. Identification of this ROS-sensitive triad controlling PML dynamics and functions could yield novel drugs. See related commentary by Salomoni, p. 2505. This article is featured in Selected Articles from This Issue, p. 2489.

Influence of heavy metal exposure on gut microbiota: Recent advances

Gut microbiota plays a functionally important part in retaining the homeostasis of host physiology, however, under exposure of various heavy metals, the composition of gut biota is disturbed in relation to species diversity and richness. Ever since the increase of microbiome-related studies during the last decade, many research studies have delivered an understanding of the reasons and concerns of gut microbiota-related modifications. During the past decade, it's been confirmed from various studies that heavy metals poisoning alters the microbial composition, which results in changes in gene expression, alteration in metabolism, immunity, neurological dysfunction, and causes various other disorders. The present comprehensive review is summarizing an attempt to enumerate the key findings from recent clinical or preclinical studies related to the influence of heavy metals on gut microbiota published recently. Google, PubMed, Science Direct, Scopus, and Google Scholar were employed as primary search engines using the keywords such as "heavy metals, gut microbiota, dysbiosis, and intestinal microbiota" for finding relevant research articles from the past 10 years and some old important articles. Here, we tried to provide insight into some of the key timelines and scientific findings from reported literature, like the effects of heavy metals such as arsenic, cadmium, lead, and mercury on the general body and specifically on the gut microbiota of different model organisms. So, it is important to increase awareness against heavy metal-induced toxicity and formulate guidelines for the benefit of the environment.

Nephroprotective effect of diosmin against sodium arsenite-induced renal toxicity is mediated via attenuation of oxidative stress and inflammation in mice

Arsenic compounds, which are used in different industries like pesticide manufacturing, cause severe toxic effects in almost all organs, including the kidneys. Since the primary route of exposure to arsenic is through drinking water, and millions of people worldwide are exposed to unsafe levels of arsenic that can pose a threat to their health, this research was performed to investigate the nephroprotective effects of Diosmin (Dios), a flavonoid found in citrus fruits, against nephrotoxicity induced by sodium arsenite (SA). To induce nephrotoxicity, SA (10 mg/kg, oral gavage) was administered to mice for 30 days. Dios (25, 50, and 100 mg/kg, oral gavage) was given to mice for 30 days prior to SA administration. After the study was completed, animals were euthanized and blood and kidney samples were taken for biochemical and histopathological assessments. Results showed that SA-treated mice significantly increased the blood urea nitrogen and creatinine levels in the serum. This increase was associated with significant kidney tissue damage in SA-treated mice, which was confirmed by histopathological studies. Furthermore, SA enhanced the amounts of renal thiobarbituric acid reactive substances and decreased total thiol reserves, as well as the activity of antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase. Also, in the SA-exposed group, an increase in the levels of kidney inflammatory biomarkers, including nitric oxide and tumor necrosis factor-alpha was observed. The western blot analysis indicated an elevation in the protein expression of kidney injury molecule-1 and nuclear factor-kappa B in SA-treated mice. However, pretreatment with Dios ameliorated the SA-related renal damage in mice. Our findings suggest that Dios can protect the kidneys against the nephrotoxic effects of SA by its antioxidant and anti-inflammatory characteristics.

Multigenerational effects of arsenate on development and reproduction in marine copepod Tigriopus japonicus

Arsenic (As) is a persistent toxic substance, however, its toxicity to marine zooplankton remains unclear. In this study, copepods were exposed to a series of dissolved arsenate (As(V)) for four generations (F0-F3) and subsequently depurated in clean seawater for two generations (F4-F5) to assess multigenerational toxicity of As(V). As(V) exposure prolonged copepod development. The development time were 1.9, 2.4, and 3.4 days longer than the control in F0 when exposed to 50, 100, and 500 μg/L As(V), respectively, and the toxicity increased with generations. Moreover, As(V) reduced the reproductive capacity of copepods, and this effect become more severe during generation succession. The 10-day fecundities were reduced from 80 to 85 eggs per female in the control to 42 eggs per female, the lowest level, in 500 μg/L As(V) exposure group in F3. Nevertheless, the fecundity was recovered to the control level in the offspring of the 50 and 100 μg/L As(V) exposed groups (F4), suggesting it was an acclimation effect of copepods during As(V) exposure. In addition, the survival rate, development time, and reproductive parameters were significantly correlated with the As accumulation in copepods. Overall, As(V) exposure caused As bioaccumulation which negatively affected copepods' survival, development, and reproductive traits, and this toxic effect was amplified with generations and concentrations. Therefore, the multigenerational toxicity of As should be considered in the environmental risk assessments.

Attenuation of sodium arsenite mediated ovarian DNA damage, follicular atresia, and oxidative injury by combined application of vitamin E and C in post pubertal Wistar rats

Arsenic being a toxic metalloid ubiquitously persists in environment and causes several health complications including female reproductive anomalies. Epidemiological studies documented birth anomalies due to arsenic exposure. Augmented reactive oxygen species (ROS) generation and quenched antioxidant pool are foremost consequences of arsenic threat. On the contrary, Vitamin E (VE) and C (VC) are persuasive antioxidants and conventionally used in toxicity management. Present study was designed to explore the extent of efficacy of combined VE and VC (VEC) against Sodium arsenite (NaAsO2) mediated ovarian damage. Thirty-six female Wistar rats were randomly divided into three groups (Grs) and treated for consecutive 30 days; Gr I (control) was vehicle fed, Gr II (treated) was gavaged with NaAsO2 (3 mg/kg/day), Gr III (supplement) was provided with VE (400 mg/kg/day) & VC (200 mg/kg/day) along with NaAsO2. Marked histological alterations were evidenced by disorganization in oocyte, granulosa cells and zona pellucida layers in treated group. Considerable reduction of different growing follicles along with increased atretic follicles was noted in treated group. Altered activities ofΔ5 3β-Hydroxysteroid dehydrogenase and 17β-Hydroxysteroid dehydrogenase accompanied by reduced luteinizing hormone, follicle-stimulating hormone and estradiol levels were observed in treated animals. Irregular estrous cyclicity pattern was also observed due to NaAsO2 threat. Surplus ROS production affected ovarian antioxidant strata as evidenced by altered oxidative stress markers. Provoked oxidative strain further affects DNA status of ovary. However, supplementation with VEC caused notable restoration from such disparaging effects of NaAsO2 toxicities. Antioxidant and antiapoptotic attributes of those vitamins might be liable for such restoration.

Effect of phosphate on arsenic species uptake in plants under hydroponic conditions

Monothioarsenate (MTA) is a newly discovered arsenic (As) compound that can be formed under reduced sulfur conditions, mainly in paddy soil pore waters. It is structurally similar to arsenate As(V) and inorganic phosphate (Pi), which is taken up through phosphate transporters. Due to the similarity between As(V) and Pi, As(V) enters into plants instead of Pi. The important role played by phytochelatin (PC), glutathione (GSH), and the PC-vacuolar transporters ABCC1 and ABCC2 under As stress in plants is well known. However, the plant uptake and mechanisms surrounding MTA still have not been completely addressed. This investigation was divided in two stages: first, several hydroponic assays were set up to establish the sensibility-tolerance of wild-type Arabidopsis thaliana (accession Columbia-0, Col-0). Then Col-0 was used as a control plant to evaluate the effects of As(V) or MTA in (PC)-deficient mutant (cad1-3), glutathione biosynthesis mutant (cad2), and PC transport (abcc1-2). The inhibitory concentration (IC50) root length was calculated for both As species. According to the results, both arsenic species (As(V) and MTA) exhibited high toxicity for the genotypes evaluated. This could mean that these mechanisms play a constitutive role in MTA detoxification. Second, for the Pi-MTA and As(V)-Pi competition assays, a series of experiments on hydroponic seedlings of A. thaliana were carried out using Col-0 and a pht1;1. The plants were grown under increasing Pi concentrations (10 μM, 0.1 mM, or 1 mM) at 10 μM As(V) or 50 μM MTA. The total As concentration in the roots was significantly lower in plants exposed to MTA, there being less As content in the pht1;1 mutant at the lowest Pi concentrations tested compared with the As(V)/Pi treatments. In addition, a higher rate of As translocation from the roots to the shoots under MTA was observed in comparison to the As(V)-treatments.

Polyamine, 1,3-diaminopropane, regulates defence responses on growth, gas exchange, PSII photochemistry and antioxidant system in wheat under arsenic toxicity

The metalloid arsenic (As) is extremely hazardous to all living organisms, including plants. Pollution with As is very detrimental to the photosynthetic machinery, cell division, energy generation, and redox status. In order to cope with stress, the use of growth regulators such as polyamines (PA), which strengthen the antioxidant system of plants, has become widespread in recent years. PAs can modulate the plant growth through basic mechanisms common to all living organisms, such as membrane stabilization, free radical scavenging, deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and protein synthesis, enzyme activities and second messengers. However, the effect of 1,3- diaminopropane (Dap), which is a product of PA catabolism, is not clear enough in plants exposed to As toxicity. In the current study, the different concentrations of 1,3-diaminopropane (0.1, 0.5 and 1 mM Dap) were hydroponically treated to wheat (Triticum aestivum) under arsenic stress (100 μM As) and then relative growth rate (RGR), relative water content (RWC), proline content (Pro), gas exchange parameters, PSII photochemistry, chlorophyll fluorescence kinetics, antioxidant activity and lipid peroxidation were assessed. RGR, RWC, osmotic potential and Pro content decreased in As-applied plants. The inhibition of these parameters could be reversed by Dap treatments. Besides, Dap applications mitigated the As toxicity-induced suppression on chlorophyll fluorescence (Fv/Fm, Fv/Fo and Fo/Fm) and the performance of PSII photochemistry. As impaired the balance on antioxidant capacity by decreased activities of catalase (CAT), peroxidase (POX), glutathione peroxidase (GPX), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and the contents of ascorbate (AsA) and glutathione (GSH) and then lipid peroxidation (TBARS content) increased. In the presence of Dap under As stress, the plants exhibited an increase in superoxide dismutase (SOD), POX, and GPX. Dap treatments contributed to the maintenance of cellular redox state (AsA/DHA and GSH/GSSG) by regulating the activities/contents of enzyme/non-enzyme involved in the AsA-GSH cycle. After Dap applications against stress, ROS accumulation (H2O2 content) and lipid peroxidation (TBARS) were effectively reduced. The findings showed that by eliminating As-induced oxidative damage and protecting the biochemical processes of photosynthesis, Dap treatments have a substantial potential to give resistance to wheat.

Effects of preterm birth and postnatal exposure to metal mixtures on neurodevelopment in children at 24 months of age

The effects of early-life metal exposure on neurodevelopment in very low birth weight preterm (VLBMP) children (with a birth weight of <1500 g and a gestational age of <37 weeks) have not been clearly established. We aimed to investigate associations of childhood exposure to multiple metals and preterm low birth weight with neurodevelopment among children at 24 months of corrected age. VLBWP children (n = 65) and normal birth weight term (NBWT) children (n = 87) were enrolled from Mackay Memorial Hospital in Taiwan between December 2011 and April 2015. Lead (Pb), cadmium (Cd), arsenic (As), methylmercury (MeHg), and selenium (Se) concentrations in the hair and fingernails were analyzed as biomarkers for metal exposure. The Bayley Scale of Infant and Toddler Development, Third Edition, was used to determine neurodevelopment levels. VLBWP children had significantly lower scores in all development domains compared to NBWT children. We also investigated preliminary exposure levels of VLBWP children to metals as reference values for future epidemiological and clinical survey. Fingernails are a useful biomarker for metal exposure to evaluate the effects on neurological development. A multivariable regression analysis revealed that fingernail Cd concentrations were significantly negatively associated with cognition (β = -0.63, 95% confidence interval (CI): -1.17 to -0.08) and receptive language function (β = -0.43, 95% CI: -0.82 to -0.04) among VLBWP children. VLBWP children with a 10-μg/g increase in the As concentration in their nails had a 8.67-point lower composite score in cognitive ability and a 1.82-point lower score in gross-motor functions. Effects of preterm birth and postnatal exposure to Cd and As were associated with poorer cognitive, receptive language, and gross-motor abilities. VLBWP children are at risk for neurodevelopmental impairments when exposed to metals. Further large-scale studies are needed assess to the risk of neurodevelopmental impairments when vulnerable children are exposed to metal mixtures.

Zinc homeostasis may reverse the synergistic neurotoxicity of heavy metal mixtures in Caenorhabditis elegans

Heavy metal mixtures can cause nerve damage. However, the combined effects of metal mixtures are extremely complex and rarely studied. Zinc (Zn) homeostasis plays an integral role in neural function, but the role of Zn homeostasis in the toxicity of metal mixtures is not well understood. Here, we investigated the combined effects of manganese (Mn), lead (Pb) and arsenic (As) on nerves and the effect of Zn homeostasis on metal toxicity. Caenorhabditis elegans (Maupas, 1900) were exposed to single and multiple metals for 8 days, their movement, behavior, neurons and metal concentration were detected to evaluate the combined effect of metal mixtures. After nematodes were co-treated with metal mixtures and Zn, the nerve function, Zn concentration and redox balance were detected to evaluate the effect of Zn homeostasis on metal toxicity. The results showed that Mn + Pb and Pb + As mixtures induced synergistic toxicity for nematode nerves, which damaged movement, behavior and neurons, and decreased Zn concentration. While Zn supplementation recovered Zn homeostasis and promoted redox balance on nematodes, and then improved the nerve function. Our study demonstrated the combined effects of metal mixtures and the neuroprotective effect of Zn homeostasis. Therefore, assessment of metal mixtures toxicity should consider their interaction and the impacts of essential metals homeostasis.

Effects of microplastics on arsenic uptake and distribution in rice seedlings

The potential of microplastics (MPs) and nanoplastics (NPs) to act as a carrier for heavy metals derived from the environment is of rising concern to the health of global ecosystems. Here, we investigated the effects of particle size of polystyrene micro/nano plastics on the uptake, accumulation, and toxicity of As in rice seedlings in a hydroponic system. Significant differences in As uptake and accumulation in different plant tissue were observed between the plants co-exposed to 82 nm NPs + As and 200 nm MPs + As. The NPs + As co-exposure led to higher As accumulation in rice leaves (12.4-36.7 %), while larger sized MPs + As(V) treatment reduced As accumulation in rice leaves. Furthermore, the co-exposure of NPs/MPs + As mitigated the rice growth inhibition caused by As toxicity. These results will provide insight into elucidating the potentially effects of nano/microplastics on As uptake and accumulation in crop plants for assessing the hazards of micro-and nanoplastics as pollutants in the food chain and environment.

Bacterial consortium (Priestia endophytica NDAS01F, Bacillus licheniformis NDSA24R, and Priestia flexa NDAS28R) and thiourea mediated amelioration of arsenic stress and growth improvement of Oryza sativa L

The present study analyzed the effects of individual microbes and their consortium (Priestia endophytica NDAS01F, Bacillus licheniformis NDSA24R, and P. flexa NDAS28R) either alone or in interaction with thiourea (TU) on growth and responses of rice plants subjected to As stress (50 mg kg^-1 in soil) in a pot experiment. The bacteria used in the experiment were isolated from As contaminated fields of Nadia, West Bengal and showed significant As removal potential in in vitro experiment. The results revealed significant growth improvement, biomass accumulation, and decline in malondialdehyde levels in rice plants in bacterial and TU treatments as compared to control As treatment. The best results were observed in a bacterial consortium (B1-2-3), which induced a profound increase of 65%, 43%, 127% and 83% in root length, shoot length, leaf width and fresh weight, respectively. Sulfur metabolism and cell wall synthesis were stimulated upon bacterial and TU amendment in plants. The maximum reduction in As concentration was observed in B2 in roots (-55%) and in B1-2-3 in shoot (-83%). The combined treatment of B1-2-3 + TU proved to be less effective as compared to that of B1-2-3 in terms of As reduction and growth improvement. Hence, the usage of bacterial consortium obtained in the present work is a sustainable approach, which might find relevance in field conditions to achieve As reduction in rice grains and to attain higher growth of plants without the need for additional TU supplementation.

Photocatalytic and oxidation mechanisms of Fe-Ag@AgCl: Effect on co-existing arsenic (III) and Escherichia coli

To address the drinking safety problems associated with high arsenic(III) (As(III)) and bacteria in underground water, core-shell Fe-Ag@AgCl nanowires were synthesized and exhibited excellent photocatalytic oxidation effects on co-existing As(III) and Escherichia coli (E. coli). With the introduction of Fe, the nanowires that were used 5 times could be easily magnetically collected, and the As(III) oxidation effect of these re-chlorinated nanowires increased from 39% to 60%. E. coli was completely inactivated within 60 min without photoreactivation after 20 min. Extracellular polymeric substances have play a protective role in the disinfection process. Quenching testing results confirmed that, except for the superoxide radical (•O₂^-), the subdominant active species were different for different objects: hole (h_VB⁺) to As(III) and hydroxyl radical (•OH) to E. coli. Therefore the system with co-existing As(III) and E. coli, the inactivation effect of Fe-Ag@AgCl on E. coli decreased remarkably with an increase in As(III) concentration, while the oxidation process of As(III) was not significantly affected by E. coli until E. coli was increased to 10⁸ cfu/mL. The photocatalytic process of co-existing As(III) and E. coli is displayed in a schematic diagram and was tested using desired results obtained from field groundwater in Xiantao City, Hubei Province. The function of Fe in band structures and density of states was analyzed using plane-wave density functional theory. These magnetic nanowires presented excellent photocatalytic ability on co-existing As(III) and E. coli, and provided new insights into drinking water safety in high-arsenic areas.

Effect of foliar and root exposure to polymethyl methacrylate microplastics on biochemistry, ultrastructure, and arsenic accumulation in Brassica campestris L

Despite the serious risk of microplastic pollution in the roots and leaves of crops, the phytotoxicity of microplastics (introduced via different exposure routes) in leafy vegetables remain insufficiently understood. Here, the effects of the root and foliar exposure of polymethyl methacrylate microplastic (PMMAMPs) on phytotoxicity, As accumulation, and subcellular distribution were investigated in rapeseed (Brassica campestris L). The relative chlorophyll content under PMMAMPs treatment decreased with time, and the 0.05 g L^-1 root exposure decreased it significantly (by 9.97-20.48%, P < 0.05). In addition, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and ascorbate peroxidase (APX) activities in rapeseed were more sensitive to PMMAMPs introduced through root exposure than through foliar exposure. There was dose-dependent ultrastructural damage, and root exposure had a greater impact than foliar exposure on root tip cells and chloroplasts. PMMAMPs entered the shoots and roots of rapeseed through root exposure. Under foliar exposure, PMMAMPs promoted As accumulation in rapeseed by up to 75.6% in shoots and 68.2% in roots compared to that under control (CK). As content in cell wall under PMMAMP treatments was 3.6-5.3 times higher than that of CK, as indicated by subcellular component results. In general, root exposure to PMMAMPs resulted in a stronger physiological impact and foliar exposure led to increased As accumulation in rapeseed.

Effects of chronic exposure to arsenic on the fecal carriage of antibiotic-resistant Escherichia coli among people in rural Bangladesh

Antibiotic resistance is a leading cause of hospitalization and death worldwide. Heavy metals such as arsenic have been shown to drive co-selection of antibiotic resistance, suggesting arsenic-contaminated drinking water is a risk factor for antibiotic resistance carriage. This study aimed to determine the prevalence and abundance of antibiotic-resistant Escherichia coli (AR-Ec) among people and drinking water in high (Hajiganj, >100 μg/L) and low arsenic-contaminated (Matlab, <20 μg/L) areas in Bangladesh. Drinking water and stool from mothers and their children (<1 year) were collected from 50 households per area. AR-Ec was detected via selective culture plating and isolates were tested for antibiotic resistance, arsenic resistance, and diarrheagenic genes by PCR. Whole-genome sequencing (WGS) analysis was done for 30 E. coli isolates from 10 households. Prevalence of AR-Ec was significantly higher in water in Hajiganj (48%) compared to water in Matlab (22%, p <0.05) and among children in Hajiganj (94%) compared to children in Matlab (76%, p <0.05), but not among mothers. A significantly higher proportion of E. coli isolates from Hajiganj were multidrug-resistant (83%) compared to isolates from Matlab (71%, p <0.05). Co-resistance to arsenic and multiple antibiotics (MAR index >0.2) was observed in a higher proportion of water (78%) and child stool (100%) isolates in Hajiganj than in water (57%) and children (89%) in Matlab (p <0.05). The odds of arsenic-resistant bacteria being resistant to third-generation cephalosporin antibiotics were higher compared to arsenic-sensitive bacteria (odds ratios, OR 1.2-7.0, p <0.01). WGS-based phylogenetic analysis of E. coli isolates did not reveal any clustering based on arsenic exposure and no significant difference in resistome was found among the isolates between the two areas. The positive association detected between arsenic exposure and antibiotic resistance carriage among children in arsenic-affected areas in Bangladesh is an important public health concern that warrants redoubling efforts to reduce arsenic exposure.

Selenite and selenate showed contrasting impacts on the fate of arsenic in rice (Oryza sativa L.) regardless of the formation of iron plaque

The different effects of selenite and selenate on the fate of As and the function of iron plaque in the interaction between Se and As are poorly understood. Rice seedlings (Oryza sativa L.) were selected as experimental plants in this study, the hydroponic experiments were conducted to investigate the possible regulatory roles of selenite and selenate on the uptake, translocation, and transformation of arsenite or arsenate accompanied by iron plaque. In arsenite- and arsenate-treated rice, the Fe30 treatments stimulated root uptake by 12.4-39.8% and 18.6-37.0%, respectively, but inhibited the movement of As from iron plaque to the roots, resulting in the absorption of a considerable amount of As on iron plaque. Regardless of the iron plaque formation, selenite (selenate) significantly increased (decreased) the root uptake of arsenite and arsenate by 28.1-53.0% and 40.0%-61.7%, respectively (45.6-56.3% and 42.5-47.7%, respectively). Interestingly, the supply of selenite significantly reduced root-to-shoot As translocation by 71.9-77.3% and 66.2-67.7%, respectively, in arsenite- and arsenate-treated rice seedlings; however, a significant increase (90.5-122.9%) was induced by selenate was found only in the arsenate-treated plants. Furthermore, the translocation of As from iron plaque to the roots was significantly increased (decreased) by selenite (selenate). As and Fe in iron plaque were significantly positively correlated in all As-treated rice plants, and this correlation was more profound than that in the shoots and roots. However, neither Fe treatments nor inorganic Se addition affected the interconversion between As(III) and As(V) obviously; and As(III) was the dominant species in both shoots (68.3-84.9%) and roots (90.7-98.2%). Our results indicate selenite and selenate are effective in reducing the As accumulation in an opposite way, and the presence of iron plaque had no obvious impact on the interaction between Se and As in rice plants.

Arsenic resistance and horizontal gene transfer are associated with carbon and nitrogen enrichment in bacteria

Coastal waters are confluences receiving large amounts of point and non-point sources of pollution. An attempt was made to explore microbial community interactions in response to carbon, nitrogen and metal pollution. Additionally, experiments were designed to analyze the influence of these factors on horizontal gene transfer (HGT). Shift in bacterial diversity dynamics by arsenic stress and nutrient addition in coastal waters was explored by metagenomics of microcosm setups. Phylogenetic analysis revealed equal distribution of Gammaproteobacteria (29%) and Betaproteobacteria (28%) in control microcosm. This proportional diversity from control switched to unique distribution of Gammaproteobacteria (44.5%)> Flavobacteria (17.7%)> Bacteriodia (11.92%)> Betaproteobacteria (11.52%) in microcosm supplemented with carbon, nitrogen and metal (C + N + M). Among metal-stressed systems, alpha diversity analysis indicated highest diversity of genera in C + N + M followed by N + M > C+M> metal alone. Arsenic and ampicillin sensitive E. coli XL1 blue and environmental strains (Vibrio tubiashii W85 and E. coli W101) were tested for efficiency of uptake of plasmid (P) pUCminusMCS (arsB^Ramp^R) under varying stress conditions. Transformation experiments revealed that combined effect of carbon, nitrogen and metal on horizontal gene transfer (HGT) was significantly higher (p < 0.01) than individual factors. The effect of carbon on HGT was proved to be superior to nitrogen under metal stressed conditions. Presence of arsenic in experimental setups (P + M, P + N + M and P + C + M) enhanced the HGT compared to non-metal counterparts supplemented with carbon or nitrogen. Arsenic resistant bacterial isolates (n = 200) were tested for the ability to utilize various carbon and nitrogen substrates and distinct positive correlation (p < 0.001) was found between arsenic resistance and utilization of urea and nitrate. However, evident positive correlation was not found between carbon sources and arsenic resistance. Our findings suggest that carbon and nitrogen pollution in aquatic habitats under arsenic stress determine the microbial community dynamics and critically influence uptake of genetic material from the surrounding environment.

Curcumin antagonizes inflammation and autophagy induced by arsenic trioxide through immune protection in duck spleen

Arsenic is a toxic heavy metal widely found in the natural environment and has adverse effects on the health of waterfowl and human. Curcumin (CUR), a natural pigment of the golden spice turmeric, exhibits excellent anti-tumor, anti-inflammatory and anti-oxidant activities. But the effects of CUR on duck spleen exposed to arsenic remain largely unknown. In this study, 75 ducks were divided randomly into Control, L-ATO, M-ATO, H-ATO and CUR + H-ATO groups to systematically analyze the underlying role of CUR. The results showed that arsenic trioxide (ATO) led to growth retardation of ducks, hyaline degeneration and sparse cell arrangement on their spleen. And in the ATO-exposed ducks, the levels of immunoglobulins (Ig; IgA, IgG, IgM) in the serum and the expression of autophagy-related genes (Atg5, P62, LC3I, LC3II, LC3II/I, Beclin-1) were significantly upregulated compared with the control ducks. Moreover, ATO also activated NF-κB signal pathway and upregulated the expression of pro-inflammatory cytokines (TNF-α, IFN-γ, IL-1β, IL-2, IL-18). Meanwhile, application of CUR alleviated the ATO toxicity with the release of growth inhibition, and the reduced hyaline degeneration and distortion of the spleen capsule. CUR also suppressed ATO-induced NF-κB activation, pro-inflammatory cytokine addition and expression of autophagy-related genes. Overall, these results suggested that CUR might exert a protective effect against ATO-induced immunosuppression in ducks via anti-inflammation and autophagy restoring.

Can As concentration in crop be controlled by Se fertilization? A meta-analysis and outline of As sequestration mechanisms

Arsenic (As) is a pollutant with a strong toxic effect on animals, plants and human beings. Exogenous selenium (Se) has been suggested to reduce the accumulation of As in crops, but contradictory results were found in the published literature. In order to clarify the possible processes, we collected the literature that reports on the effects of Se application on As uptake and accumulation in crops, analyzed the data by meta-analysis, and tested the effects of different factors on As accumulation by meta-regression model and subgroup analysis. The results highlighted a significant dose-dependent reduction of As content in crops after Se addition. Exogenous Se can significantly reduce As concentrations in grains by 18.76%. The reduction was dose-dependent for rice grains under aerobic soil conditions but not for rice grains under anoxic soil conditions. Se-enriched soils (greater than 0.5 mg kg^-1) significantly reduced As concentrations in grains. Selenium significantly decreased the transfer factor of As from root to shoot. Moreover, selenite had a stronger inhibiting effect on the transport of As from root to shoot than selenate. The inhibition of selenium fertilization on As concentrations seems to take place in root and soil, while physiological processes in rice may be involved in restricting uptake and transport from root to shoot. These findings provide new ideas for effectively alleviating the transfer of As to the human body through the food chain.

[Effect of Modified Chitosan Loaded with Silica on Arsenic Uptake and Transport in Rice]

Chitosan loaded with silica foliar spraying material (NCSI) was prepared using natural biomass chitosan and organic silicon and was applied to Lindao 16, Nanjing 2728, Zhenghan 10, and Nongken 58 at the rice filling stage to study the effects on arsenic (As) absorption in rice. The results showed that under a 100 μmol·L^-1 pentavalent arsenic[As(Ⅴ)] hydroponic environment, foliar spraying of 30 mL NCSI on leaves promoted the accumulation of As in leaves and reduced the accumulation of As in roots and grains. Among them, the As contents of Nanjing 2728, Zhenghan 10, and Nongken 58 grains were decreased by 14.44%, 21.66%, and 10.85%, respectively, compared with those of the blank group on the 3^rd day after spraying NCSI. Meanwhile, foliar spraying of NCSI improved the activities of CAT and SOD in rice leaves and increased the GSH content, indicating that the spraying of NCSI alleviated the stress of As on rice, improved the tolerance of rice to As, and reduced the toxicity of As to rice. The main mechanism of foliar application of NCSI to reduce As accumulation in rice grains may have been that NCSI induced GSH production in leaves, reducing more As(Ⅴ) to trivalent arsenic[As(Ⅲ)], thereby promoting As chelating in leaves and inhibiting As migration to grains. Therefore, foliar spraying of NCSI can be used as a foliar control technology to solve the problem of excessive As in rice and provide a scientific basis for the safe production of rice in China.

Tocopherol Enhances the Antioxidant Defense System and Histomorphometric Parameters in The Gastrointestinal Tract of Rats Treated with Sodium Arsenite

Arsenic compromises the gastrointestinal integrity and function via the body's anti-oxidative system breakdown.  Hence, this study aimed to investigate the effects of tocopherol on redox imbalance and histoarchitectural alterations in rats' gastrointestinal tract exposed to sodium arsenite. Sodium arsenite and graded doses of tocopherol were administered orally into experimental rats assigned to different groups for four weeks concurrently. Redox status assay was done in homogenized samples by spectrophotometry. Parietal cell mass and mucous cell density (stomach), villus height and crypt depth (ileum), goblet cells count, and crypt depth (colon) were evaluated by histomorphometry. Inflammatory cells infiltration was also assessed using a semi-quantitative procedure. Sodium arsenite caused a significant increase in Malondialdehyde and Myeloperoxidase but, decreased Superoxide dismutase, Catalase, Nitric oxide, Glutathione peroxidase, Glutathione, and Glutathione-S-Transferase. Tocopherol treatment reversed the changes (p<0.05) though not largely dose-dependent. Furthermore, tocopherol annulled sodium arsenite-induced increase in parietal cell mass and decrease in mucous cell density in the stomach, decrease in villus height and villus height/crypt depth ratio in the ileum, and decrease in goblets cells and increase in crypt depth in the colon. Moreover, activated inflammatory cell infiltration by sodium arsenite was mitigated by tocopherol. Sodium arsenite provokes not only marked inflammatory cellular infiltration but a focal loss of glands, hyperplasia of crypts, atrophic villi, and hypertrophy of Peyer's patches in the intestines, which are all lessened with tocopherol treatment.  These findings underscore the anti-oxidative properties of tocopherol as a potent dietary factor against sodium arsenite toxicity in the gastrointestinal tract. Keywords: Tocopherol, arsenic, stomach, ileum, colon.

Supplementation of Ascophyllum nodosum meal and monensin: Effects on diversity and relative abundance of ruminal bacterial taxa and the metabolism of iodine and arsenic in lactating dairy cows

Previous research has shown that the brown seaweed Ascophyllum nodosum (ASCO) has antimicrobial and antioxidant properties and also increases milk I concentration. We aimed to investigate the effects of supplementing ASCO meal or monensin (MON) on ruminal fermentation, diversity and relative abundance of ruminal bacterial taxa, metabolism of I and As, and blood concentrations of thyroid hormones, antioxidant enzymes, and cortisol in lactating dairy cows. Five multiparous ruminally cannulated Jersey cows averaging (mean ± standard deviation) 102 ± 15 d in milk and 450 ± 33 kg of body weight at the beginning of the study were used in a Latin square design with 28-d periods (21 d for diet adaptation and 7 d for data and sample collection). Cows were fed ad libitum a basal diet containing (dry matter basis) 65% forage as haylage and corn silage and 35% concentrate and were randomly assigned to 1 of the following 5 dietary treatments: 0, 57, 113, or 170 g/d of ASCO meal, or 300 mg/d of MON. Supplements were placed directly into the rumen once daily after the morning feeding. Diets had no effect on ruminal pH and NH3-N concentration, which averaged 6.02 and 6.86 mg/dL, respectively. Total volatile fatty acid concentration decreased linearly in cows fed incremental amounts of ASCO meal. Supplementation with ASCO meal did not change the ruminal molar proportions of volatile fatty acids apart from butyrate, which responded quadratically with the lowest values observed at 56 and 113 g/d of ASCO supplementation. Compared with the control diet or diets containing ASCO meal, cows fed MON showed greater molar proportion of propionate. Diets did not affect the α diversity indices Shannon, Simpson, and Fisher for ruminal bacteria. However, feeding incremental levels of ASCO meal linearly decreased the relative abundance of Tenericutes in ruminal fluid. Monensin increased the relative abundance of the CAG:352 bacterial genus in ruminal fluid compared with the control diet. Linear increases in response to ASCO meal supplementation were observed for the concentrations and output of I in serum, milk, urine, and feces. Fecal excretion of As increased linearly in cows fed varying amounts of ASCO meal, but ASCO did not affect the concentration and secretion of As in milk. The plasma activities of the antioxidant enzymes and the serum concentrations of thyroid hormones did not change. In contrast, circulating cortisol decreased linearly in diets containing ASCO meal. The apparent total-tract digestibilities of dry matter, organic matter, and crude protein increased linearly with ASCO meal, but those of neutral and acid detergent fiber were not affected. In summary, feeding incremental amounts of ASCO meal decreased serum cortisol concentration, and increased I concentrations and output in serum, milk, feces, and urine.

Dictyophora Polysaccharide Attenuates As-Mediated PINK1/Parkin Pathway-Induced Mitophagy in L-02 Cell through Scavenging ROS

Arsenic (As) is common in the human living environment and a certain amount of exposure to As can lead to liver damage; this toxic effect has been proved to be closely related to intracellular PINK1/Parkin pathway-mediated mitophagy. Dictyophora is an edible fungus that extracts polysaccharides with antioxidant and hepatoprotective effects. In the present study, we demonstrated that As induced the onset of mitophagy in hepatocytes by stimulating cellular production of ROS to activate PINK1/Parkin, and the extent of damage increased with increased As-induced toxicity. Dictyophora polysaccharide (DIP) has the ability to scavenge intracellular ROS, which can inhibit oxidative stress injury and inhibit the PINK/Parkin pathway through its receptors or efficacious proteins, thus preventing mitochondrial autophagy and alleviating the hepatotoxicity of As. In conclusion, our results indicate that DIP can reduce As-induced PINK1/Parkin pathway-mediated hepatic mitophagy through scavenging ROS and exert hepatoprotective effects, providing experimental data and theoretical basis for the development of medicinal value of Dictyophora as a dual-use food and medicinal fungus.

Effect of Telmisartan on Arsenic-Induced (Sub-chronic) Perturbations in Redox Homeostasis, Pro-inflammatory Cascade and Aortic Dysfunction in Wistar Rats

An experimental study was conducted in male Wistar rats to explore the antioxidant potential of telmisartan (an AT₁ receptor blocker) to overcome arsenic ('As')-induced perturbations in redox homeostasis pro-inflammatory cytokines, prostaglandin-E₂ levels and aortic dysfunction in Wistar rats. Wistar rats were randomly divided into four groups of six each. Group-I served as untreated control, while group-II received sodium (meta) arsenite (NaAsO₂) (10 mg/kg b.wt. p.o) for a period of 60 days. Experimental rats in group-III received treatment similar to group-II, but in addition received telmisartan (with 1% aqueous solution of Tween 80) @ 10 mg/kg b.wt. (p.o) for a similar duration, while rats in group-IV received telmisartan alone. Arsenic exposure resulted in significant (p < 0.05) elevation in the levels of superoxide anion ([Formula: see text]) radicals (control: 768.20 ± 126.77 vs group-II: 1232.75 ± 97.85 pmol of NBT reduced/min/mg protein). Telmisartan administration showed significant (p < 0.05) reduction in [Formula: see text] generation (815.34 ± 43.41 pmol of NBT reduced/min/mg protein). Sub-chronic exposure to 'As' significantly (p < 0.05) decreased the activities of SOD, CAT, GPx and GR activity and GSH levels in the aorta, thus induced lipid peroxidation (LPO) measured as measured in terms of thiobarbituric acid reactive substances (TBARS) called as malondialdehyde (MDA). However, the administration of telmisartan effectively countered the LPO (24.03 ± 1.18 nmol of MDA/g) on account of restoring the levels of aforesaid antioxidant defense system. Telmisartan administration effectively attenuated the 'As'-induced surge in pro-inflammatory cytokines (viz., IL-1β, IL-6 and TNF-α) levels, as well as countered the activity of cyclooxygenase (COX₂) as indicated by a significant (p < 0.05) decrease in PGE₂ level in the aorta. In addition to it, there was a significant (p < 0.05) decrease in plasma angiotensin II (Ang-II) levels in experimental rats receiving telmisartan. Quantitative RT-PCR studies revealed that sub-chronic exposure to 'As' upregulated the Nox₂ mRNA expression, but there was a 1.2-fold reduction in expression level upon co-administration of telmisartan. Histopathological examination revealed marked recovery from 'As'-induced disruption of tunica adventitia and loss of connective tissue in experimental rats receiving telmisartan. The study concludes that telmisartan can overcome aortic dysfunction induced by sub-chronic exposure to arsenic through drinking water in experimental rats through restoration of redox balance, attenuation of pro-inflammatory cytokines and mediators and downregulation of Nox₂ mRNA expression.

[Effects of Earthworms/Biochar on Bacterial Diversity and Community in As-contaminated Red Soil]

Cerium-manganese modified biochar (MBC) combined with earthworms (Eisenia foetida) can immobilize arsenic (As) in red soils. In this study, high-throughput sequencing technology was used to explore the combined effects of MBC and E. foetida on bacterial diversity and community structure in As-contaminated red soils. The results showed that the single earthworm treatment had the highest diversity index, whereas the diversity index decreased in the single biochar or MBC treatment, indicating that earthworms can boost the growth of bacteria in the soil, and the addition of biochar/MBC all decreased the bacterial diversity of soils. When biochar/MBC was combined with earthworms, the diversity index increased to some degree. In terms of bacterial community structure, the relative abundance of Proteobacteria and Bacteroidetes increased significantly in each treatment, especially for MBC-earthworm treated soil, in which the relative abundance was increased by 17.08% and 329.47% for Proteobacteria and Bacteroidetes, respectively, compared to that in the control (CK). Otherwise, those abundances were decreased by 19.18% and 48.76%, respectively, for Acidobacteria and Chloroflexi. Correlation analysis results showed that the soil water-soluble As (WSAs) was negatively correlated with the relative abundances of Proteobacteria and Bacteroides (P<0.05) but was positively correlated with Acidobacteria and Chloroflexi (P<0.05), which indicated that with the decrease in WSAs in soils, the bacteria of Proteobacteria and Bacteroides reproduced rapidly, whereas the Acidobacteria and Chloroflexi were inhibited. Moreover, different treatments induced selective changes in the bacterial community, in which earthworms significantly promoted the proliferation of γ-Proteobacteria, Flavobacteriales, Aeromonadales, and Variovorax and earthworms improved the immobilization effect of As by promoting the growth of these bacteria.

Alkaline extract from vermicompost reduced the stress promoted by As on maize plants and increase their phytoextraction capacity

Arsenic (As) represents an environmental risk and phytoremediation has been identified as a good technique to recover contaminated soils. Plants defense mechanisms needed to be enhanced against As stress-promoting action by biostimulants such as humic materials. This work sought to determine the effectiveness of an alkaline vermicompost extract (AEV) and in mitigating stresses promoted by As in maize plants, increasing their potential use for phytoextraction. The AEV were extracted from vermicompost and two preliminary assays in Leonard pots were carried out: the first one to define the best AEV concentration-response dose and the second to point out the toxic As concentration. The second step was to set up a 28-day long experiment with the following four treatments: control, AEV, As, As + AEV. AEV attenuated As-induced stress in maize plants. Maize dry biomass was reduced in the As treatment and rebalanced to values similar to the control in the As + HS treatment while the plants treated only with HS showed the highest biomass among the treatments. The concentrations of P, Fe, Cu, Mn and Ni, and catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) antioxidant activity increased in the As treatment and decreased in the As + AEV treatment. The rate of photosynthesis decreased, and the internal CO₂ concentration increased with stress induced by As, where both effects were attenuated by AEV. Our results show the positive effect of the AEV in alleviating As abiotic stress on maize growth, offering new options of employment of humic substances in phytoremediation process.

Aquoeus Extracts of Daucus Carota (Linn) Protected the Postnatal Developing Cerebellum of Wistar Rats Against Arsenic-Induced Oxidative Stress

The neuroprotective effects of the aqueous extract of Daucus carota (Dc) tuber against arsenic-induced oxidative damage on the developing cerebellum of Wistar rats were studied. Twenty-five pregnant rats (110-200g) were divided into five groups (n=5) - control received distilled water; Arsenic (As); Dc (200mg/kg); Dc (200mg/kg) +As; Vitamin C (Vc) (100mg/kg) +As. The pregnant rats in all the groups were treated orally from the first day of pregnancy to postnatal day 21. The Dc extract and Vc were administered one hour before the administration of As. Body weight of the pups on days 1, 7, 14, 21 and 28 were recorded, while neurobehavioural (forelimb grip strength and negative geotaxis) tests were done on day 21 pups. The rats were sacrificed and cerebellar tissues were collected for oxidative stress, histological (H and E), and immunohistochemical studies. Decreased forelimb grip strength, increased lipid peroxidation and decreased glutathione, glutathione peroxidase, catalase and superoxide dismutase was observed in the As group compared with the control and other treated groups. Histologically, the cerebellar cortex of the As pups showed persistent external granular layer (EGL) on postnatal day 21, reduced thickness of the molecular layer (ML) on postnatal day 28, pyknotic and depleted Purkinje cells compared with the control and other treated rats. Immunohistochemical evaluations of the cerebellar cortex showed astroliosis in the As-treated group on day 21 pups compared with the control and other treated groups.  Aqueous extracts of Daucus carota and Vitamin C reversed the toxicity caused by arsenic. From the results of the study, arsenic-induced oxidative stress with morphological alterations in the perinatal developing rat cerebellum. Extracts of Daucus carota exhibited antioxidant activity as such may be a potential neuroprotective agent.

Ferritin-based targeted delivery of arsenic to diverse leukaemia types confers strong anti-leukaemia therapeutic effects

Trivalent arsenic (AsIII) is an effective agent for treating patients with acute promyelocytic leukaemia, but its ionic nature leads to several major limitations like low effective concentrations in leukaemia cells and substantial off-target cytotoxicity, which limits its general application to other types of leukaemia. Here, building from our clinical discovery that cancerous cells from patients with different leukaemia forms featured stable and strong expression of CD71, we designed a ferritin-based As nanomedicine, As@Fn, that bound to leukaemia cells with very high affinity, and efficiently delivered cytotoxic AsIII into a large diversity of leukaemia cell lines and patient cells. Moreover, As@Fn exerted strong anti-leukaemia effects in diverse cell-line-derived xenograft models, as well as in a patient-derived xenograft model, in which it consistently outperformed the gold standard, showing its potential as a precision treatment for a variety of leukaemias.

Occurrence of Textile Dyes and Metals in Tunisian Textile Dyeing Effluent: Effects on Oxidative Stress Status and Histological Changes in Balb/c Mice

Although it is known that textile wastewater contains highly toxic contaminants whose effects in humans represent public health problems in several countries, studies involving mammal species are scarce. This study was aimed to evaluate the toxicity profile of 90-days oral administration of textile dyeing effluent (TDE) on oxidative stress status and histological changes of male mice. The TDE was collected from the textile plant of Monastir, Tunisia and evaluated for the metals, aromatic amines, and textile dyes using analytical approaches. Metal analysis by ICP-MS showed that the tested TDE exhibited very high levels of Cr, As, and Sr, which exceeded the wastewater emission limits prescribed by WHO and Tunisian authority. The screening of TDE through UPLC-MS/MS confirmed the presence of two textile dyes: a triphenylmethane dye (Crystal violet) and a disperse azo dye (Disperse yellow 3). Exposure to TDE significantly altered the malondialdehyde (MDA), Conjugated dienes (CDs), Sulfhydryl proteins (SHP) and catalase levels in the hepatic and renal tissues. Furthermore, histopathology observation showed that hepatocellular and renal lesions were induced by TDE exposure. The present study concluded that TDE may involve induction of oxidative stress which ensues in pathological lesions in several vital organs suggesting its high toxicity. Metals and textile dyes may be associated with the observed toxicological effects of the TDE. These pollutants, which may have seeped into surrounding rivers in Monastir city, can cause severe health malaise in wildlife and humans.

Rice seed (IR64) priming with potassium humate for improvement of seed germination, seedling growth and antioxidant defense system under arsenic stress

The intolerable levels of arsenic (As) in groundwater and its application in rice cultivation are continuously affecting the rice production in Ganga-Meghna-Brahmaputra (GMB) plain. The reduced germination and plant growth rates under excessive As stress ultimately lead to lower yield. To mitigate this concerning issue, the present study was carried out to evaluate the potential of K-humate priming on seed germination and plant growth under As stress. Seeds were primed with 100 mg/l K-humate for 12 h prior to germination. The germination percentages in unprimed seeds were 65 ± 5.0% and 58.3 ± 7.6% under stress level of 50 μM AsV and 50 μM AsIII, respectively. However, germination percentage in K-humate primed seeds were 75 ± 5.0% and 68.3 ± 2.9% under AsV and AsIII stress, respectively. The vigour index I (VG I) and vigour index II (VG II) recorded on 12 DAS (days after seeding) were also increased by 1.47 and 1.51 fold, respectively with K-humate supplementation under As stress. Detrimental effects of AsIII on seed germination, seedling growth and other physiological parameters were more suppressive than AsV. Application of K-humate not only improved seed germination, seedling growth and nutrient uptake but also decreased the oxidative stress markers and antioxidant activities by minimizing As uptake and translocation in the seedlings.

Sperm quality assessment in Ficopomatus enigmaticus (Fauvel, 1923): Effects of selected organic and inorganic chemicals across salinity levels

Contamination by organic and inorganic compounds remains one of the most complex problems in both brackish and marine environments, causing potential implications for the reproductive success and survival of several broadcast spawners. Ficopomatus enigmaticus is a tubeworm polychaete that has previously been used as a model organism for ecotoxicological analysis, due to its sensitivity and ecological relevance. In the present study, the effects of five trace elements (zinc, copper, cadmium, arsenic and lead), one surfactant (sodium dodecyl sulfate, SDS) and one polycyclic aromatic hydrocarbon (benzo(a)pyrene, B(a)P) on the sperm quality of F. enigmaticus were investigated. Sperm suspensions were exposed in vitro to different concentrations of each selected contaminant under four salinity conditions (10, 20, 30, 35). Possible adverse effects on sperm function were assessed by measuring oxidative stress, membrane integrity, viability and DNA damage. Sperm quality impairments induced by organic contaminants were more evident than those induced by inorganic compounds. SDS exerted the largest effect on sperm. In addition, F. enigmaticus sperm showed high tolerance to salinity variation, supporting the wide use of this species as a promising model organism for ecotoxicological assays. Easy and rapid methods on polychaete spermatozoids were shown to be effective as integrated sperm quality parameters or as an alternative analysis for early assessment of marine and brackish water pollution.

Application of Next Generation Sequencing (NGS) in Phage Displayed Peptide Selection to Support the Identification of Arsenic-Binding Motifs

Next generation sequencing (NGS) in combination with phage surface display (PSD) are powerful tools in the newly equipped molecular biology toolbox for the identification of specific target binding biomolecules. Application of PSD led to the discovery of manifold ligands in clinical and material research. However, limitations of traditional phage display hinder the identification process. Growth-based library biases and target-unrelated peptides often result in the dominance of parasitic sequences and the collapse of library diversity. This study describes the effective enrichment of specific peptide motifs potentially binding to arsenic as proof-of-concept using the combination of PSD and NGS. Arsenic is an environmental toxin, which is applied in various semiconductors as gallium arsenide and selective recovery of this element is crucial for recycling and remediation. The development of biomolecules as specific arsenic-binding sorbents is a new approach for its recovery. Usage of NGS for all biopanning fractions allowed for evaluation of motif enrichment, in-depth insight into the selection process and the discrimination of biopanning artefacts, e.g., the amplification-induced library-wide reduction in hydrophobic amino acid proportion. Application of bioinformatics tools led to the identification of an SxHS and a carboxy-terminal QxQ motif, which are potentially involved in the binding of arsenic. To the best of our knowledge, this is the first report of PSD combined with NGS of all relevant biopanning fractions.

Chronic arsenic exposure enhances metastatic potential via NRF2-mediated upregulation of SOX9

Chronic low dose arsenic exposure continues to be a worldwide health concern because of its prevalence and link to increased cancer risk, including non-small cell lung cancer (NSCLC). Mortality of NSCLC patients increases with the development of a metastatic lesion compared to when the tumor is localized; however, the exact mechanism for what causes NSCLC cells to metastasize in the context of environmental toxicant exposure has yet to be fully elucidated. One proposed contributor to metastasis in NSCLC is nuclear factor (erythroid-derived 2)-like 2 (NRF2), a transcription factor with known oncogenic properties that has proved to be critical for arsenic carcinogenesis. Here, we demonstrate that chronic arsenic exposure enhances the invasive and migratory capacity of immortalized lung epithelial cells via NRF2-dependent upregulation of SRY-box 9 (SOX9), another transcription factor linked with cell proliferation, epithelial-mesenchymal transition, and metastasis. We identified a functional antioxidant response element (ARE) in the promoter region of SOX9, suggesting that it is an NRF2 target gene, with mutation of the ARE preventing NRF2 binding. Pharmacological induction or inhibition of NRF2 increased or decreased SOX9 expression, respectively. Furthermore, we demonstrate that hyperactivation of NRF2 via knockout of Kelch-like ECH-associated protein 1 (KEAP1), its negative regulator, contributes to proliferation; while, inhibition of NRF2 or direct knockdown of SOX9 slowed the ability of NSCLC cells to proliferate, migrate, and invade. Overall, this study suggests that NRF2-mediated SOX9 upregulation can contribute to the metastatic potential of both environmentally and genetically driven lung tumors.

Arsenic Exposure Decreases Adiposity During High-Fat Feeding

OBJECTIVE

Arsenic is an endocrine-disrupting chemical associated with diabetes risk. Increased adiposity is a significant risk factor for diabetes and its comorbidities. Here, the impact of chronic arsenic exposure on adiposity and metabolic health was assessed in mice.

METHODS

Male C57BL/6J mice were provided ad libitum access to a normal or high-fat diet and water +/- 50 mg/L of sodium arsenite. Changes in body weight, body composition, insulin sensitivity, energy expenditure, and locomotor activity were measured. Measures of adiposity were compared with accumulated arsenic in the liver.

RESULTS

Despite uniform arsenic exposure, internal arsenic levels varied significantly among arsenic-exposed mice. Hepatic arsenic levels in exposed mice negatively correlated with overall weight gain, individual adipose depot masses, and hepatic triglyceride accumulation. No effects were observed in mice on a normal diet. For mice on a high-fat diet, arsenic exposure reduced fasting insulin levels, homeostatic model assessment of insulin resistance and β-cell function, and systemic insulin resistance. Arsenic exposure did not alter energy expenditure or activity.

CONCLUSIONS

Collectively, these data indicate that arsenic is antiobesogenic and that concentration at the source poorly predicts arsenic accumulation and phenotypic outcomes. In future studies, investigators should consider internal accumulation of arsenic rather than source concentration when assessing the outcomes of arsenic exposure.

In vivo evaluation of arsenic-associated behavioral and biochemical alterations in F0 and F1 mice

Groundwater contaminated with arsenic (As) is the biggest threat to public health in Bangladesh. The children of As-exposure parents are also exposing to As through drinking water. The effects of As on the children's health of As-exposure parents are poorly understood. An animal study was taken to evaluate the effects of As on behavioral and biochemical changes in F₁ mice. Swiss albino mice were separated into three groups: a) control, b) As-treated F₀ and c) As-treated F₁. Elevated plus maze and Morris water maze tests were used for evaluating anxiety, spatial memory and learning, respectively. We found that the effect of As on anxiety like behavior, spatial memory and learning impairment in As-treated F₁ mice was significantly higher than that of As-treated F₀ mice and control group. Additionally, we also evaluated the effects of As on biochemical parameters by measuring ALT, AST, ALP, BChE, SOD activities and the level of creatinine in As-induced mice, where we found that all of the blood parameters were significantly changed in F₁ generation. A significant portion of As accumulated in the brain, liver and kidney of F₁ mice than F₀ mice. Histological analysis revealed a significant change in tissue damage related to hepatic and renal dysfunctions that might be associated with As-induced biochemical alterations. In conclusion, arsenic plays an important role for the development of As-associated neurological disorders, hepatic toxicities, and renal dysfunctions in both F₀ and F₁ generations. Notably F₁ mice were much more vulnerable to As-exposure than F₀ mice.

Alteration of enzyme activities and functional diversity of a soil contaminated with copper and arsenic

Copper (Cu) mining has to address a critical environmental issue related to the disposal of heavy metals and metalloids (HMs). Due to their deleterious effects on living organisms, Cu and arsenic (As) have gained global attention, and thus their monitoring in the environment is an important task. The aims of this study were: 1) to evaluate the alteration of soil enzyme activities (EAs) and soil microbial functional diversity with Cu/As contamination, and 2) to select the most reliable biochemical indicators of Cu/As contamination. A twelve-week soil experiment was performed with four increasing levels of Cu, As, and Cu/As from 150/15 to 1000/100 mg Cu/As kg^-1. Soil enzyme activities and soil community-level physiological profile (CLPP) using MicroResp™ were measured during the experiment. Results showed reduced EAs over time with increasing Cu and Cu/As levels. The most Cu-sensitive EAs were dehydrogenase, acid phosphatase, and arylsulfatase, while arginine ammonification might be related to the resilience of soil microbial communities due to its increased activity in the last experimental times. There was no consistent response to As contamination with reduced individual EAs at specific sampling times, being urease the only EA negatively affected by As. MicroResp™ showed reduced carbon (C) substrate utilization with increasing Cu levels indicating a community shift in C acquisition. These results support the use of specific EAs to assess the environmental impact of specific HMs, being also the first assessment of EAs and the use of CLPP (MicroResp™) to study the environmental impact in Cu/As contaminated soils.

Response to vanadate exposure in Ochrobactrum tritici strains

Vanadium is a transition metal that has been added recently to the EU list of Raw Critical Metals. The growing needs of vanadium primarily in the steel industry justify its increasing economic value. However, because mining of vanadium sources (i. e. ores, concentrates and vanadiferous slags) is expanding, so is vanadium environmental contamination. Bioleaching comes forth as smart strategy to deal with supply demand and environmental contamination. It requires organisms that are able to mobilize the metal and at the same time are resistant to the leachate generated. Here, we investigated the molecular mechanisms underlying vanadium resistance in Ochrobactrum tritici strains. The highly resistant strain 5bvl1 was able to grow at concentrations > 30 mM vanadate, while the O. tritici type strain only tolerated < 3 mM vanadate concentrations. Screening of O. tritici single mutants (chrA, chrC, chrF and recA) growth during vanadate exposure revealed that vanadate resistance was associated with chromate resistance mechanisms (in particular ChrA, an efflux pump and ChrC, a superoxide dismutase). We also showed that sensitivity to vanadate was correlated with increased accumulation of vanadate intracellularly, while in resistant cells this was not found. Other up-regulated proteins found during vanadate exposure were ABC transporters for methionine and iron, suggesting that cellular responses to vanadate toxicity may also induce changes in unspecific transport and chelation of vanadate.

Arsenic-induced immunomodulatory effects disorient the survival-death interface by stabilizing the Hsp90/Beclin1 interaction

Ground water arsenic contamination is a global menace. Since arsenic may affect the immune system, leading to immunesuppression, we investigated the effects of acute arsenic exposure on the thymus and spleen using Swiss albino mice, exposed to 5 ppm, 15 ppm and 300 ppm of sodium arsenite for 7 d. Effects on cytokine balance and cell survivability were subsequently analyzed. Our data showed that arsenic treatment induced debilitating alterations in the tissue architecture of thymus and spleen. A dose-dependent decrease in the ratio of CD4⁺-CD8⁺ T-cells was observed along with a pro-inflammatory response and redox imbalance. In addition, pioneering evidences established the ability of arsenic to induce an up regulation of Hsp90, eventually resulting in stabilization of its client protein Beclin-1, an important autophagy-initiating factor. This association initiated the autophagic process, confirmed by co-immunoprecipitation assay, acridine orange staining and Western blot, indicating the effort of cells trying to survive at lower doses. However, increased arsenic assault led to apoptotic cell death in the lymphoid organs, possibly by increased ROS generation. There are several instances of autophagy and apoptosis taking place either simultaneously or sequentially due to oxidative stress. Since arsenic is a potent environmental stress factor, exposure to arsenic led to a dose-dependent increase in both autophagy and apoptosis in the thymus and spleen, and cell death could therefore possibly be induced by autophagy. Therefore, exposure to arsenic leads to serious effects on the immune physiology in mice, which may further have dire consequences on the health of exposed animals.

High-Protein Diet Ameliorates Arsenic-Induced Oxidative Stress and Antagonizes Uterine Apoptosis in Rats

Arsenic toxicity purportedly threats a broad spectrum of female reproductive functions. We investigated the remedial role of a casein- and pea protein-enriched high-protein diet (HPD) in combating the arsenic insult. Cyclic female rats maintained on standard diet (n = 6) or an isocaloric HPD (n = 6) were gavaged with As₂O₃ at 3 mg/kg BW/rat/day (n = 12) for 28 days. Vehicle-fed rats (n = 6) maintained on the standard diet served as the control. We monitored the estrus cycles and performed the histomorphometric analyses of the uterus and ovary. Uterine luminal epithelial (ULE) ultrastructure was appraised by scanning electron microscopy. Uterine oxidative stress was evaluated in the forms of ROS generation and activities of the ROS scavengers. The uterine apoptotic manifestation was blueprinted by Western blot analysis of caspase-3 and Bax expression. Arsenic treatment arrested the follicular maturation and disrupted the estrus cycles with a typical increase in the diestrus index. Shrunken endometrial glands and thinned microvilli density of the ULE reflected loss of cell polarity and mislaid uterine homeostasis. Increased ROS generation and attenuated activities of the ROS scavengers marked a state of uterine oxidative imbalance and loss of redox regulation. Superfluous expression of procaspase-3, cleaved caspase-3, and Bax mirrored an inflated state of uterine apoptosis. HPD supplementation, by and large, counteracted these arsenic impacts and maintained the frameworks close to the control levels. In conclusion, arsenic mediates its reproductive toxicity, at least in part, by upsetting the uterine ROS homeostasis and redox regulation. Pea proteins and casein-supplemented HPD can counteract the arsenic effects and maintain the reproductive functions.

Impacts of Arsenic and Antimony Co-Contamination on Sedimentary Microbial Communities in Rivers with Different Pollution Gradients

Arsenic (As) and antimony (Sb) are both toxic metalloids that are of primary concern for human health. Mining activity has introduced elevated levels of arsenic and antimony into the rivers and has increased the risks of drinking water contamination in China. Due to their mobility, the majority of the metalloids originating from mining activities are deposited in the river sediments. Thus, depending on various geochemical conditions, sediment could either be a sink or source for As and Sb in the water column. Microbes are key mediators for biogeochemical transformation and can both mobilize or precipitate As and Sb. To further understand the microbial community responses to As and Sb contamination, sediment samples with different contamination levels were collected from three rivers. The result of the study suggested that the major portions of As and Sb were in strong association with the sediment matrix and considered nonbioavailable. These fractions, however, were also suggested to have profound influences on the microbial community composition. As and Sb contamination caused strong reductions in microbial diversity in the heavily contaminated river sediments. Microorganisms were more sensitive to As comparing to Sb, as revealed by the co-occurrence network and random forest predictions. Operational taxonomic units (OTUs) that were potentially involved in As and Sb metabolism, such as Anaerolinea, Sphingomonas, and Opitutus, were enriched in the heavily contaminated samples. In contrast, many keystone taxa, including members of the Hyphomicrobiaceae and Bradyrhizobiaceae families, were inhibited by metalloid contamination, which could further impair crucial environmental services provided by these members.

Role of Pigment Epithelium-Derived Factor in Arsenic-Induced Vascular Endothelial Dysfunction in a Rat Model

Water-borne arsenicosis is caused by the consumption of excess levels of inorganic arsenic from drinking water and is a worldwide public health issue. Arsenic exposure has recently attracted extensive attention due to its damage to the cardiovascular system. Vascular endothelial dysfunction (VED) is recognized as an important cause of cardiovascular diseases. Pigment epithelium-derived factor (PEDF) plays an important role in maintaining endothelial function, and our previous studies suggested that PEDF may have role in arsenic-induced damage. In the present study, we established subchronic arsenic exposure (3 months) rat model from drinking water at doses of 0, 2 mg/L, 10 mg/L, and 50 mg/L, respectively. The results showed that the endothelial cells of the aortic arch were obviously damaged, the apoptosis rate increased, the vWF and iNOS levels increased, and the NO and TNOS levels significantly decreased in the arsenic exposure groups. Regardless of serum or aortic arch endothelium, PEDF levels in the arsenic exposure groups decreased compared to the control group. The oxidative stress level and key proteins associated with apoptosis such as Fas, FasL, P53, and p-p38 were then detected to explore the detailed mechanisms. The results showed that the P53 and p-p38 levels significantly increased in the 10 mg/L and 50 mg/L groups compared to the control group. The MDA content in the arsenic exposure groups increased markedly, whereas the SOD activity decreased significantly with the increased arsenic dose. Taken together, our study is the first to find that PEDF plays a protective role in arsenic-induced endothelial dysfunction through anti-oxidation and anti-apoptosis, and p38 and P53 may be promising target proteins.

Silencing GSK3β instead of DKK1 can inhibit osteogenic differentiation caused by co-exposure to fluoride and arsenic

Chronic exposure to combined fluoride (F) and arsenic (As) continues to be a major public health problem worldwide, attracting the attention of an increasing number of researchers. While bone is the main target organ of syndrome of endemic arsenic poisoning and fluorosis (SEAF), the specific mechanism and targeted intervention remains uncertain. The first question in this study sought to determine the interaction of F and As on the Wnt signaling pathway and its role in osteogenic differentiation in the SEAF population. As can be seen from the data, with the increase in exposure to F, the content of Wnt signaling inhibitor Dickkopf-related protein 1 (DKK1) gradually decreased, but the expression of glycogen synthase kinase-3β (GSK3β), β-catenin and the osteogenic differentiation indicators pro-collagen I alpha 1 (COL1A1) and bone alkaline phosphatase (BALP) were increased. Next, we grouped the SEAF population according to urinary As and found that As can upregulate the GSK3β, β-catenin level and the bone formation bio-marker BALP in serum. But the experiments did not detect any evidence that As can change the content of DKK1 in serum. To better understand the combined effects of F and As on the Wnt signaling pathway, we performed further interaction analysis. These results suggest that the interaction of F and As can inhibit the GSK3β, β-catenin, COL1A1 and BALP. And DKK1 is mainly manifested by the independent effect of F. To further study the role of DKK1 and GSK3β in fluoride-arsenic pollution combined with osteogenic differentiation, we attempted to silence the DKK1 and GSK3β gene in hFOB 1.19 cells. The results show that F, As alone and in combination exposure can up-regulate GSK catenin transcription and protein expression levels and down-regulate DKK1, and COL1A1 and ALP are significantly increased, after silenced the DKK1. The same results did not appear after silenced the GSK3β. F and As alone and in combination exposure did not reverse the inhibition of GSK3β and β-catenin by GSK3β silencing, and COL1A1 and ALP are significantly decreased. The results indicate that silencing GSK3β instead of DKK1 can inhibit osteogenic differentiation caused by co-exposure to fluoride and arsenic. This study can provide a scientific basis for further understanding the causes of bone formation caused by F and As and the improvement of targeted intervention strategies.