Arsenic Toxicity Research Articles

Mitigation of heavy metal toxicity in pigeon pea by plant growth promoting Pseudomonas alcaliphila strain PAS1 isolated from contaminated environment.

The risk of arsenic contamination is rising globally, and it has negative impacts on the physiological processes and growth of plants. Metal removal from contaminated soils can be accomplished affordably and effectively with plant growth promoting rhizobacteria (PGPR)-based microbial management. From this angle, this research evaluated the mitigation of arsenic toxicity using the bacteria isolated from contaminated site, Mettur, Salem district, South India. The newly isolated bacterial strain was screened for plant growth promotion potential and arsenic tolerance such as (100ppm, 250ppm, 500ppm, 800ppm and 1200ppm). The metal tolerant rhizobacteria was identified using 16S rRNA gene sequence analysis as Pseudomonas alcaliphila strain PAS1 (GenBank accession number: OQ804624). Pigeon pea (Cajanus cajan) plants were used in pot culture experiments with varying concentrations of arsenic, (5ppm, 10ppm and 25ppm) both with and without bacterial culture, for a period of 45days. At the concentration of 25ppm after the application of PAS1 enhanced the plant growth, protein and carbohydrate by 35.69%, 18.31% respectively. Interestingly, P. alcaliphila strain PAS1 significantly reduced the stress-induced elevated levels of proline, flavonoid, phenol and antioxidant enzyme in pigeon pea plants was 40%, 31.11%, 27.80% and 20.12%, respectively. Consequently, PAS1 may significantly reduce the adverse effects that arsenic causes to plant development in acidic soils, improve plant uptake of nutrients, and increase plant production. The findings of this study reveal that P. alcaliphila PAS1 is intrinsic for phytoremediation by reducing arsenic accumulation in the root and shoot.

Delphi method investigation and research on the revision of Diagnosis of Occupational Arsenic Poisoning (GBZ 83-2013)

Objective: To explore the expert opinions on the revision of the Diagnosis of Occupational Arsenic Poisoning (GBZ 83-2013) . Methods: In March 2023, the improved Delphi expert consultation method was adopted, in the first round of consultation, a pre-survey was conducted on 20 experts, and the questionnaire was improved according to the experts' opinions. Then, a second round of expert consultation questionnaire was formed to conduct a questionnaire survey and consultation of 50 experts engaged in occupational disease diagnosis and related work. The feedback of experts was collected and analyzed. Results: The average score for the scientificity and progressiveness of the main technical content of the original standard was 3.33, and the average score for the rationality and operability of the main technical content of the original standard was 3.25. The importance of individual indicators with specific connotations were ranged from 4.20 to 4.45, with coefficients of variation <0.25, and the experts' opinions were relatively concentrated. The experts have provided feedback indicating that the original standard had issues such as lack of continuity in diagnostic gradation, the need to integrate biomarkers with urinary and hair arsenic levels, a scarcity of objective diagnostic indicators, the removal of exposure response from the main text, and a low level of consistency in standard usage. These issues need to be revised urgently. Conclusion: The Diagnosis of Occupational Arsenic Poisoning (GBZ 83-2013) should be revised based on experts' feedback and suggestions to meet the current real demand for occupational arsenic poisoning diagnosis.

High arsenic contamination in the breast milk of mothers inhabiting the Gangetic plains of Bihar: a major health risk to infants

Groundwater arsenic poisoning has posed serious health hazards in the exposed population. The objective of the study is to evaluate the arsenic ingestion from breastmilk among pediatric population in Bihar. In the present study, the total women selected were n = 513. Out of which n = 378 women after consent provided their breastmilk for the study, n = 58 subjects were non-lactating but had some type of disease in them and n = 77 subjects denied for the breastmilk sample. Hence, they were selected for the women health study. In addition, urine samples from n = 184 infants’ urine were collected for human arsenic exposure study. The study reveals that the arsenic content in the exposed women (in 55%) was significantly high in the breast milk against the WHO permissible limit 0.64 µg/L followed by their urine and blood samples as biological marker. Moreover, the child’s urine also had arsenic content greater than the permissible limit (< 50 µg/L) in 67% of the studied children from the arsenic exposed regions. Concerningly, the rate at which arsenic is eliminated from an infant’s body via urine in real time was only 50%. This arsenic exposure to young infants has caused potential risks and future health implications. Moreover, the arsenic content was also very high in the analyzed staple food samples such as rice, wheat and potato which is the major cause for arsenic contamination in breastmilk. The study advocates for prompt action to address the issue and implement stringent legislative measures in order to mitigate and eradicate this pressing problem that has implications for future generations.

Removal of Arsenic from Contaminated Water by Polypyrrole-Based Adsorbents

Worldwide, there is growing concern over the toxicity of arsenic in drinking water. The US Environmental Protection Agency and Central Pollution Control Board (India) have set a safe limit of 50 parts per billion for arsenic in drinking water. Millions of people are at immediate risk due to high concentrations of arsenic in drinking water, particularly in developing nations where arsenic poisoning symptoms have been observed. One of the essential techniques described in this article is the absorption of arsenic from contaminated water by sustainable cellulosic materials like jute and wood sawdust after suitable modification. Jute and sawdust are cheap and abundantly available in South Asia. They are functionalized with polypyrrole coating by in situ chemical polymerization of pyrrole in aqueous medium in the presence of ferric chloride. Polypyrrole-coated jute fabric (with 11.28% polypyrrole add-on) and polypyrrole-coated sawdust (with 5.28% polypyrrole add-on) are found to be excellent adsorbers of arsenic ion (As3+) from water. The effect of dosage of polypyrrole-coated adsorbents, treatment time and pyrrole concentration on the As removal efficiency have been investigated in this work. The arsenic concentration in water is determined using a microwave plasma atomic emission spectrometer with the highest level of accuracy. Maximum As removal efficiency by the polypyrrole-coated sawdust and polypyrrole-coated jute fabric is found to be 80.90% and 97.3%, respectively, from a 50 mL, 7.5 parts per million As solution with a dosage of 1 g at neutral pH. The polypyrrole-coated jute and sawdust are characterized by Fourier-transform infrared spectroscopy to understand the chemical interaction between cellulose and polypyrrole molecules. The scanning electron microscope studies reveal a uniform coating of polypyrrole around the surface of jute fibre and sawdust particles. Thermo-gravimetric analysis shows good thermal stability of jute and sawdust after polypyrrole coating.

Arsenic speciation in rice grain grown in microwave and biochar treated soil

Since the toxicity of arsenic (As) depends on its forms, it is necessary to determine the As species to evaluate the associated risk. Therefore, in this study, the As speciation of rice grain samples was performed. Arsenic contaminated (0, 20, 40, 60, and 80 mg kg–1) soils were treated with microwave (MW) and biochar (BC) with MW irradiation for 0, 3 and 6 minutes and BC application of 0, 10, 20 t ha–1 as As alleviation techniques where soil could remain contaminated but result in less accumulation in the grain. Atomic Fluorescence Spectrometry (AFS) and High-Performance Liquid Chromatography coupled with Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS) techniques were used for the determination of total As and As species identification respectively. With increasing soil As concentration both the inorganic As [as arsenite; As(III)] and organic As (as dimethylarsinic acid; DMA) concentration in rice grains increased significantly. However, rice grain As(III) and DMA concentrations were up to 73.74 % lower in MW treatments (MW-3 and MW-6) compared to the untreated control (MW-0). In rice grain samples, As was present mainly as DMA (70.6 %) and the remainder was As(III), accounting for 29.4 % of the total As. In the case of BC treatments, compared to the untreated control (BC-0), rice grain As(III) rose in the BC treatments (BC-10 and BC-20). While, DMA concentration decreased in the BC-10 treatment, compared with the control (BC-0), it increased again at BC-20. Thus, MW could be a novel technique for plant As toxicity alleviation however, more detail investigation needed considering MW and BC effect on the different soil’s rhizosphere system in different variety of rice.

Pseudochrobactrum asaccharolyticum mitigates arsenic induced oxidative stress of maize plant by enhancing water status and antioxidant defense system

BackgroundOxidative stress mediated by reactive oxygen species (ROS) is a common denominator in arsenic toxicity. Arsenic stress in soil affects the water absorption, decrease stomatal conductance, reduction in osmotic, and leaf water potential, which restrict water uptake and osmotic stress in plants. Arsenic-induced osmotic stress triggers the overproduction of ROS, which causes a number of germination, physiological, biochemical, and antioxidant alterations. Antioxidants with potential to reduce ROS levels ameliorate the arsenic-induced lesions. Plant growth promoting rhizobacteria (PGPR) increase the total soluble sugars and proline, which scavenging OH radicals thereby prevent the oxidative damages cause by ROS. The main objective of this study was to evaluate the potential role of Arsenic resistant PGPR in growth of maize by mitigating arsenic stress.MethodologyArsenic tolerant PGPR strain MD3 (Pseudochrobactrum asaccharolyticum) was used to dismiss the ‘As’ induced oxidative stress in maize grown at concentrations of 50 and 100 mg/kg. Previously isolated arsenic tolerant bacterial strain MD3 “Pseudochrobactrum asaccharolyticum was used for this experiment. Further, growth promoting potential of MD3 was done by germination and physio-biochemical analysis of maize seeds. Experimental units were arranged in Completely Randomized Design (CRD). A total of 6 sets of treatments viz., control, arsenic treated (50 & 100 mg/kg), bacterial inoculated (MD3), and arsenic stress plus bacterial inoculated with three replicates were used for Petri plates and pot experiments. After treating with this MD3 strain, seeds of corn were grown in pots filled with or without 50 mg/kg and 100 mg/kg sodium arsenate.ResultsThe plants under arsenic stress (100 mg/kg) decreased the osmotic potential (0.8 MPa) as compared to control indicated the osmotic stress, which caused the reduction in growth, physiological parameters, proline accumulation, alteration in antioxidant enzymes (Superoxide dismutase-SOD, catalase-CAT, peroxidase-POD), increased MDA content, and H2O2 in maize plants. As-tolerant Pseudochrobactrum asaccharolyticum improved the plant growth by reducing the oxidation stress and antioxidant enzymes by proline accumulation. PCA analysis revealed that all six treatments scattered differently across the PC1 and PC2, having 85.51% and 9.72% data variance, respectively. This indicating the efficiency of As-tolerant strains. The heatmap supported the As-tolerant strains were positively correlated with growth parameters and physiological activities of the maize plants.ConclusionThis study concluded that Pseudochrobactrum asaccharolyticum reduced the ‘As’ toxicity in maize plant through the augmentation of the antioxidant defense system. Thus, MD3 (Pseudochrobactrum asaccharolyticum) strain can be considered as bio-fertilizer.

Occupational exposure to arsenic and leukopenia risk: Toxicological alert.

Arsenic and its inorganic compounds affect numerous organs and systemic functions, such as the nervous and hematopoietic systems, liver, kidneys, and skin. Despite a large number of studies on arsenic toxicity, rare reports have investigated the leukopenia incidence in workers exposed to arsenic. In workplaces, the main source of workers' exposure is the contaminated air by the inorganic arsenic in mines, arsenic or copper smelter industries, and chemical factories. Erythropoiesis inhibition is one of the arsenic effects and it is related to regulatory factor GATA-1. This factor is necessary for the normal differentiation of early erythroid progenitors. JAK-STAT is an important intracellular signal transduction pathway responsible for the mediating normal functions of several cytokines related to cell proliferation and hematopoietic systems development and regulation. Arsenic inactivates JAK-STAT by inhibiting JAK tyrosine kinase and using the IFNγ pathway. The intravascular hemolysis starts after the absorption phase when arsenic binds to the globin of hemoglobin in erythrocytes and is transported into the body, which increases the oxidation of sulfhydryl groups in hemoglobin. So, this article intends to highlight the potential leukopenia risk via inhalation for workers exposed to arsenic and suggests a possible mechanism for this leukopenia through the JAK-signal transducer and activator of transcription (STAT) pathway inhibition.

Drying-rewetting alters arsenic ecotoxicity: From the perspective of enzyme-based functional diversity

Drying-rewetting (DW) cycles can significantly influence soil properties and microbial community composition, leading to direct or indirect changes in arsenic (As) toxicity, which inturn affects soil ecological functions. Despite this, there has been insufficient focus on accurately evaluating As ecotoxicity and its impact on soil ecological function under DW conditions. This study seeks to address this gap by examining the effects of DW on As toxicity and the characteristics of soil ecological function, specifically from the perspective of enzyme-based functional diversity. Our results reveal that compared to constant moisture conditions, DW treatment significantly increased the toxicity of As on alkaline phosphatase and β-glucosidase, with maximum inhibition rates observed at 46.29% and 21.54%, respectively. Conversely, for other tested enzymes including invertase, fluorescein diacetate hydrolase, and dehydrogenase, DW treatment decreased As toxicity, possibly be due to the different stability of these enzymes under varying soil moisture conditions. From an enzyme functional diversity perspective, DW treatment reduced the As toxicity, as evidenced by the reduced inhibition rates and a lower coefficient of variation. In conclusion, DW appears to enhance soil functional resilience against arsenic pollution. These findings contribute to a better understanding of changes in ecological functions in heavy metal-contaminated soils under dynamic environmental conditions, offering insights for improved monitoring and mitigation strategies for metalloids toxicity in natural environments.

Ischemic stroke as a consequence of acute hemolytic anemia following arsenic poisoning.

Ischemic stroke as a consequence of acute hemolytic anemia following arsenic poisoning.

Identification of key factors and mechanism determining arsenic mobilization in paddy soil-porewater-rice system

Arsenic (As) mobilization in paddy fields poses significant health risks, necessitating a thorough understanding of the controlling factors and mechanisms to safeguard human health. We conducted a comprehensive investigation of the soil-porewater-rice system throughout the rice life cycle, focusing on monitoring arsenic distribution and porewater characteristics in typical paddy field plots. Soil pH ranged from 4.79 to 7.98, while porewater pH was weakly alkaline, varying from 7.2 to 7.47. Total arsenic content in paddy soils ranged from 6.8 to 17.2 mg/kg, with arsenic concentrations in porewater during rice growth ranging from 2.97 to 14.85 μg/L. Specifically, arsenite concentrations in porewater ranged from 0.48 to 7.91 μg/L, and arsenate concentrations ranged from 0.73 to 5.83 μg/L. Through principal component analysis (PCA) and analysis of redox factors, we identified that arsenic concentration in porewater is predominantly influenced by the interplay of reduction and desorption processes, contributing 43.5 % collectively. Specifically, the reductive dissolution of iron oxides associated with organic carbon accounted for 23.3 % of arsenic concentration dynamics in porewater. Additionally, arsenic release from the soil followed a sequence starting with nitrate reduction, followed by ferric ion reduction, and subsequently sulfate reduction. Our findings provide valuable insights into the mechanisms governing arsenic mobilization within the paddy soil-porewater-rice system. These insights could inform strategies for irrigation management aimed at mitigating arsenic toxicity and associated health risks.

Effects of tauroursodeoxycholate on arsenic-induced hepatic injury in mice: A comparative transcriptomic analysis

BackgroundProlonged exposure to excessive arsenic (As) and its compounds can cause damage to multiple systems, including respiratory, cardiovascular, immune, nervous, and endocrine systems. Manifestations include changes in skin pigmentation, excessive keratosis on palms and soles, gastrointestinal symptoms, and anemia. The liver as an important detoxification organ of the body, is a significant target organ for arsenic toxicity, and liver diseases are common. So far, the molecular mechanism has not been fully elucidated. Evidence suggests that taurodeoxycholic acid (TUDCA) has a protective role in arsenic-induced liver injury. This study aims to reveal potential target genes at the transcriptional level following TUDCA intervention, providing insights for the intervention of arsenic-induced liver injury. MethodsThe TUDCA intervention model of arsenic liver injury in C57BL/6 N mice was established. The experiment was divided into two phases and lasted for 24 weeks. The phase I trial (12 weeks) was divided into control, low, middle and high groups according to the dose of As. The phaseⅡtrial (12 weeks) was administered in combination with 10 mg/L sodium arsenite (the first stage high arsenic group) and TUDCA, so subsequent groups was named with H indicating high arsenic. Divide into four groups: control group(C), TUDCA solvent control group(H-Vehicle), TUDCA combined with As group(H-TUDCA), arsenic group (As). As was ingested through free water and TUDCA was administered to mice by gavage at a dose of 0.1 mL/10 g.b.w (100 mg/kg) once a day for 12 weeks. The differential expression gene (DEG) profile was obtained from the second batch of mouse liver tissues by RNA sequencing technology. Comparative transcriptomic analysis methods were used to identify co-varying DEGs between arsenic induction and TUDCA intervention, along with their associated pathways. QRT-PCR was utilized for validation. ResultsTranscriptome results showed that 487 DEGs were identified after arsenic induction. TUDCA intervention identified 231 DEGs (p-values < 0.05 and | log2(fold change) | > 1). The comparison of "AS vs C" and "H_TUDCA vs AS" identified 65 covariant DEGs, and further screened the TUDCA pathways and related genes among these genes，six pathways and 11 genes (Ccl21a, Ccr7, Mdm2, Slc2a4, Akr1b7, Pnpla3, Dusp8, Hspa1a, Cyp7a1, Cybrd1, Trpm6) were obtained. Next, we screened for covariant DEGs among the top 50 potential hub genes in arsenic-induced DEGS, and obtained 7 (Hbb-bs, Hspa1a, Mdm2, Slc2a4, Ptk6, Egr1, and Dusp8). Finally, the intersection of Hub gene and pathway gene was selected as the target genes Dusp8, Hspa1a, Mdm2 and Slc2a4. The sequencing results showed that the mRNA expressions of Dusp8, Hspa1a and Mdm2 were significantly increased after arsenic induction, while the expression of Slc2a4 was significantly decreased (P<0.05). Conversely, TUDCA intervention reversed these DEGs changes, consistent with QRT-PCR validation results. ConclusionThis study contributes to understanding the potential health effects of arsenic-induced liver injury, identifying new potential targets, and providing references for TUDCA intervention.

Arsenical keratosis in China: A case report and review of the literature.

Arsenical keratosis is a precancerous dermatosis which could be induced by long-term exposure to arsenic poisoning. Arsenic is often added to traditional Chinese medicine in a non-compliant manner to increase the effectiveness of psoriasis treatment, which is often the main cause of arsenic poisoning in Chinese patients with psoriasis. We performed a systemic review of arsenic keratosis during the past 32 years to better understand the sources, treatment, and prognosis of arsenic keratosis in China. We searched Medline/PubMed, Embase, CNKI, and Wanfang databases for research studies published between 1992 and 2024. A total of 64 papers with 78 individual Chinese of arsenical keratosis were included in this analysis. Of the patients included in the analysis, 92.21% of arsenic poisoning was due to iatrogenic factors: Chinese traditional medicine. Seventy-six patients (98.70%) had skin manifestation of hyperkeratotic papules and plaques, 68 patients (88.31%) had hyperpigmentation, 43 cases (55.84%) had hypopigmentation, and only 4 had a clear indication of Mees' lines in nails. A total of 52.63% of patients presented with tumors, including squamous cell carcinoma, Bowen's disease, and basal cell carcinoma. For patients with tumors, 20 opted for surgery, 6 for radiotherapy, and 3 for PDT. All patients with only cutaneous tumors are currently well-controlled. Death occurred in one patient with metastatic squamous cell carcinoma. Keratinizing papules improved significantly in 70.59% of patients treated with Acitretin Capsules. In this study, arsenic sources in Chinese patients were mainly from traditional Chinese medicine, and there were no reports of exposure to water sources or occupational sources in the past 32 years. Most of the patients showed keratinizing papules and pigmentation, and more than 1/2 of the patients showed skin tumors, mainly squamous cell carcinoma. The treatments of tumors are mainly surgical treatment, PDT and radiotherapy can also be selected. The improvement in keratinizing rash was greater than 70% with acitretin capsules. Patients with this disease should be regularly followed up for early detection and timely treatment of potential malignant tumors.

Selenium improved arsenic toxicity tolerance in two bell pepper (Capsicum annuum L.) varieties by modulating growth, ion uptake, photosynthesis, and antioxidant profile

Bell pepper (Capsicum annuum L.); an important spice crop of the region is a rich source of vitamins and antioxidants having many health benefits. Many biotic and abiotic factors contribute towards growth and yield losses of this crop. Arsenic (As) toxicity is a global issue, but it is particularly critical in developing countries. The current study was designed to evaluate the efficacy of selenium (Se) in mitigating the toxic effects of As in two varieties (HSP-181 A and PS09979325) of Capsicum annuum L. Different concentrations of As (0, 50, and 100 µM) and Se (0, 5, and 10 µM) were tested using 14 days old seedlings of C. annuum L. The As stress caused a significant (P ≤ 0.001) reduction in growth, uptake of nutrients, and eco-physiological attributes in both varieties however, the response was specific. While the overproduction of osmo-protectants and antioxidants intensified the symptoms of oxidative stress. The maximum reduction in shoot length (45%), fresh weight (29%), and dry weight (36%) was observed in under 100 µM As stress. The organic acids exudation from the roots of both cultivars were significantly increased with the increase in As toxicity. The Se treatment significantly (p ≤ 0.001) improved growth, nutrient uptake, gas exchange attributes, antioxidant production, while decreased oxidative stress indicators, and As uptake in the roots and shoots of all the subjects under investigation. It is concluded from the results of this study that Se application increased photosynthetic efficiency and antioxidant activity while decreasing As levels, organic acid exudation, and oxidative stress indicators in plants. Overall, the var. PS09979325 performed better and may be a good candidate for future pepper breeding program.

Cultivating resilience in wheat: mitigating arsenic toxicity with seaweed extract and Azospirillum brasilense.

Arsenic (As) toxicity is a serious hazard to agricultural land due to growing industrialization, which has a negative effect on wheat crop yields. To address this issue, using seaweed extract and Azospirillum brasilense has emerged as an effective strategy for improving yield under stress conditions. However, the combined application of A. brasilense and seaweed extract in wheat crops under As toxicity has not been fully explored. The effectiveness of combining A. brasilense and seaweed extract in reducing As toxicity in wheat production was examined in this study through a 2-year pot experiment with nine treatments. These treatments included a control with no additives and two As concentrations (50 and 70 μM). At 50 and 70 μM, As was tested alone, with seaweed extract, with A. brasilense, and both. Significant results were achieved in reducing As toxicity in wheat crops. Arsenic at 70 μM proved more harmful than at 50 μM. The application of A. brasilense and seaweed extract was more effective in improving crop growth rates, chlorophyll levels, and stomatal conductance. The combined application notably decreased As concentration in wheat plants. It was concluded that applying A. brasilense and seaweed extract not only improves wheat growth but can also improve soil parameters under As toxicity conditions by increasing organic matter contents, boosting nutrient availability, and increasing the production of antioxidant enzymes.

Electrochemiluminescence assay for the impact of Ganoderma lucidum polysaccharides on resisting arsenic-induced apoptosis

Ganoderma lucidum (G. lucidum) is a traditional edible fungus with strong medicinal value. G. lucidum polysaccharides (GLP) encapsulate many of the key beneficial properties of this species, providing a valuable tool for the treatment of a range of diseases. The present study was developed to explore the protective benefits of GLP treatment in the context of arsenic poisoning. Through microscopy and flow cytometry experiments, NaAsO2 was found to induce rat tracheal epithelial (RTE) cell apoptosis, together with reductions in cell surface epidermal growth factor receptor (EGFR) expression. GLP treatment, however, was able to reduce apoptosis rates and elevate the expression of EGFR relative to NaAsO2-treated cells. GLP extracts (50, 100, 200 mg·mL−1) prepared from four types of G. lucidum were administered to RTE cells damaged with arsenic, revealing limited differences in position resistance among these varieties. This work provides reference for the pharmaceutical and medical research of G. lucidum.

Transformation of p-arsanilic acid by dissolved Mn(III) and enhanced arsenic removal: Mechanism, toxicity and performance in complicated water matrices

Dissolved Mn(III), as a potent one-electron transfer oxidant, is ubiquitous in natural waters and sediments and actively involved in the transformation of organics in biogeochemical processes and water treatment. However, the important role of Mn(III) has long been overlooked because of its short life. This study was the first to investigate the performance of Mn(III) in organoarsenic transformation and to highlight the environmental implications. Both homogeneous and heterogeneous Mn(III)-based systems were effective to remove p-arsanilic acid (p-ASA, 15 μM) with degradation efficiency approaching 40.4 %–98.3 %. Two degradation pathways of p-ASA were proposed, in which As-C bond and amino group were vulnerable sites to Mn(III) attack, leading to the formation of more toxic arsenate (As(V)) and nitarsone. Through transforming organoarsenic to inorganic arsenic species, the removal efficiency of total arsenic and dissolved organics were enhanced to 65.1 %–95.5 % and 16.6 %–36.6 %, respectively, by post-treatment of coagulation or adsorption, accompanied with significant reduction of cytotoxicity and environmental risks. Particularly, polymeric ferric sulfate and granular activated alumina showed superior performance in the total As removal. Moreover, oxidation efficiency of Mn(III) was hardly affected by common cations and anions (e.g., Ca2+, Mg2+, NH4+, NO3ˉ, SO4ˉ), halide ions (e.g., Clˉ, Brˉ) and natural organic matter, showing high robustness for organoarsenic removal under complicated water matrices. Overall, this study shed light on the significance of Mn(III) to the fate of organoarsenics in manganese-rich environments, and demonstrated the promising potential of Mn(III)-based strategies to achieve targeted decontamination in water/wastewater purification.

Phosphorous accumulation associated with mitochondrial PHT3-mediated enhanced arsenate tolerance in Chlamydomonas reinhardtii

Arsenate is a highly toxic element and excessive accumulation of arsenic in the aquatic environment easily triggers a problem threatening the ecological health. Phytoremediation has been widely explored as a method to alleviate As contamination. Here, the green algae, Chlamydomonas reinhardtii was investigated by profiling the accumulation of arsenate and phosphorus, which share the same uptake pathway, in response to arsenic stress. Both C. reinhardtii wild type C30 and the Crpht3 mutant were cultured under arsenic stress, and demonstrated a similar growth phenotype under limited phosphate supply. Sufficient phosphate obviously increased the uptake of polyphosphate and intercellular phosphate in the Crpht3 mutant, which increased the arsenic tolerance of the Crpht3 mutant under stress from 500 µmol L−1 As(V). Upregulation of the PHT3 gene in the Crpht3 mutant increased accumulation of phosphate in the cytoplasm under arsenate stress, which triggered a regulatory role for the differentially expressed genes that mediated improvement of the glutathione redox cycle, antioxidant activity and detoxification. While the wild type C30 showed weak arsenate tolerance because of little phosphate accumulation. These results suggest that the enhanced arsenic tolerance of the Crpht3 mutant is regulated by the PHT3 gene mediation. This study provides insight onto the responsive mechanisms of the PHT3 gene-mediated in alleviating arsenic toxicity in plants.

Research progress on the regulatory mechanism of cell senescence in arsenic toxicity: a systematic review.

As an element with metalloid properties, arsenic is pervasively present in the environment and is recognized as a potent carcinogen. Consequently, the issue of human arsenic exposure has become a significant concern within the global public health sector. Numerous studies have indicated that arsenic induces cellular senescence through various mechanisms, including triggering epigenetic alterations, inducing the senescence-associated secretory phenotype (SASP), promoting telomere shortening, and causing mitochondrial dysfunction. This article collates and summarizes the latest research advancements on the involvement of cellular senescence in arsenic toxicity and explores the mechanisms of arsenic-induced toxicity. This study aims to provide new perspectives and directions for future research on arsenic toxicity and the development of prevention and treatment strategies.

Regulation of arsenate stress by nitric oxide and hydrogen sulfide in Oryza sativa seedlings: Implication of sulfur assimilation, glutathione biosynthesis, and the ascorbate-glutathione cycle and its genes

Seed priming by nitric oxide (NO) and hydrogen sulphide (H2S) in combating against abiotic stress in plants is well documented. However, knowledge of fundamental mechanisms of their crosstalk is scrambled. Therefore, the reported study examined the probable role of NO and H2S in the mitigation of arsenate toxicity (As(V)) in rice seedlings and whether their potential signalling routes crossover. Results report that As(V) toxicity limited shoot and root length growth with more As accumulation in roots. As(V) further caused elevated reactive oxygen species levels, inhibited ascorbate-glutathione cycle enzymes and relative gene expression of its enzymes and thus, causing lipid and protein oxidation. These results correlate with reduced nitric oxide synthase-like and L–cysteine desulfhydrase activity along with endogenous NO and H2S. While, L-NAME or PAG augmented As(V) toxicity, and addition of SNP or NaHS effectively reversed their respective effects. Furthermore, SNP under PAG or NaHS under L-NAME were able to pacify As(V) stress, implicating that endogenous NO and H2S efficiently ameliorate As(V) toxicity but without their shared signaling in rice seedlings.

Insights into the ameliorative effect of ZnONPs on arsenic toxicity in soybean mediated by hormonal regulation, transporter modulation, and stress responsive genes.

Arsenic (As) contamination of agricultural soils poses a serious threat to crop productivity and food safety. Zinc oxide nanoparticles (ZnONPs) have emerged as a potential amendment for mitigating the adverse effects of As stress in plants. Soybean crop is mostly grown on marginalized land and is known for high accumulation of As in roots than others tissue. Therefore, this study aimed to elucidate the underlying mechanisms of ZnONPs in ameliorating arsenic toxicity in soybean. Our results demonstrated that ZnOB significantly improved the growth performance of soybean plants exposed to arsenic. This improvement was accompanied by a decrease (55%) in As accumulation and an increase in photosynthetic efficiency. ZnOB also modulated hormonal balance, with a significant increase in auxin (149%), abscisic acid (118%), gibberellin (160%) and jasmonic acid content (92%) under As(V) stress assuring that ZnONPs may enhance root growth and development by regulating hormonal signaling. We then conducted a transcriptomic analysis to understand further the molecular mechanisms underlying the NPs-induced As(V) tolerance. This analysis identified genes differentially expressed in response to ZnONPs supplementation, including those involved in auxin, abscisic acid, gibberellin, and jasmonic acid biosynthesis and signaling pathways. Weighted gene co-expression network analysis identified 37 potential hub genes encoding stress responders, transporters, and signal transducers across six modules potentially facilitated the efflux of arsenic from cells, reducing its toxicity. Our study provides valuable insights into the molecular mechanisms associated with metalloid tolerance in soybean and offers new avenues for improving As tolerance in contaminated soils.