Industrialization releases significant amounts of various air pollutants such as F, Cd, Pb, particulate matter, etc., which can in turn have a deleterious effect on a variety of biochemical and physiological processes as well as the structural organization within the cells. Responses from plants species to air pollutants is varied with certain species being very sensitive to such pollutants, ending up with well visible and measurable symptoms. Morphological damage is generally visible through lesions on the aerial parts, while biochemical and physiological changes which are invisible can be measured and quantified. This study has been designed to investigate the biochemical and physiological biomarkers of apricot (Prunus armeniaca L.) exposed to air pollution. It has been observed that, in comparison to unpolluted sites, lipid peroxidation level has increased in the leaves of apricot trees, grown in polluted areas, whereas photosynthetic capacity (Net photosynthesis, stomatal conductance, transpiration rate, total chlorophyll, and carotenoids) along with osmotic regulator (proline and soluble sugars) levels have declined. In P. armeniaca leaves, these symptoms can be used as indicators of air pollution stress for its early diagnosis, making them a reliable marker for a particular physiological disorder.

Understanding of aquaporins (AQPs) facilitating the transport of water and many other small solutes including metalloids like silicon (Si) and arsenic (As) is important to develop stress tolerant cultivars. In the present study, 40 AQPs were identified in the genome of pigeonpea (Cajanus cajan), a pulse crop widely grown in semi-arid region and areas known to affected with heavy metals like As. Conserved domains, variation at NPA motifs, aromatic/arginine (ar/R) selectivity filters, and pore morphology defined here will be crucial in predicting solute specificity of pigeonpea AQPs. The study identified CcNIP2-1 as an AQP predicted to transporter Si (beneficial element) as well as As (hazardous element). Further Si quantification in different tissues showed about 1.66% Si in leaves which confirmed the predictions. Furthermore, scanning electron microscopy showed a higher level of Si accumulation in trichomes on the leaf surface. A significant alleviation in level of As, Sb and Ge stress was also observed when these heavy metals were supplemented with Si. Estimation of relative water content, H₂O₂, lipid peroxidation, proline, total chlorophyll content and other physiological parameters suggested Si derived stress tolerance. Extensive transcriptome profiling under different developmental stages from germination to senescence was performed to understand the tissue-specific regulation of different AQPs. For instance, high expression of TIP3s was observed only in reproductive tissues. Co-expression network developed using transcriptome data from 30 different conditions and tissues, showed interdependency of AQPs. Expression profiling of pigeonpea performed using real time PCR showed differential expression of AQPs after Si supplementation. The information generated about the phylogeny, distribution, molecular evolution, solute specificity, and gene expression dynamics in article will be helpful to better understand the AQP transport system in pigeonpea and other legumes.

Arsenic (As) contamination and bioaccumulation are a serious threat to agricultural plants. To address this issue, we checked the efficacy of As tolerant plant growth promoting bacteria (PGPB), zinc oxide nanoparticles (ZnO NPs) and oxalic acid (OA) in Luffa acutangula grown on As rich soil. The selected most As tolerant PGPB i.e Providencia vermicola exhibited plant growth promoting features i.e solubilzation of phosphate, potassium and siderophores production. Innovatively, we observed the synergistic effects of P. vermicola, ZnO NPs (10 ppm) and OA (100 ppm) in L. acutangula grown on As enriched soil (150 ppm). Our treatments both as alone and in combination alleviated As toxicity exhibited by better plant growth and metabolism. Results revealed significantly enhanced photosynthetic pigments, proline, relative water content, total sugars, proteins and indole acetic acid along with As amelioration in L. acutangula. Furthermore, upregulated plant resistance was manifested with marked reduction in the lipid peroxidation and electrolyte leakage and pronounced antagonism of As and zinc content in leaves under toxic conditions. These treatments also improved level of nutrients, abscisic acid and antioxidants to mitigate As toxicity. This marked improvement in plants’ defense mechanism of treated plants under As stress is confirmed by less damaged leaves cell structures observed through the scanning electron micrographs. We also found substantial decrease in the As bioaccumulation in the L. acutangula shoots and roots by 40 and 58% respectively under the co-application of P. vermicola, ZnO NPs and OA in comparison with control. Moreover, the better activity of soil phosphatase and invertase was assessed under the effect of our application. These results cast a new light on the application of P. vermicola, ZnO NPs and OA in both separate and combined form as a feasible and ecofriendly tool to alleviate As stress in L. acutangula.

Numerous applications exist for graphene-based materials, such as graphene oxide (GO) nanosheets. Increased concentrations of GO nanosheets in the environment have the potential to have a large negative effect on the aquatic environment, with consequences for benthic organisms, such as polychaetes. The polychaete Hediste diversicolor mobilises the sediments, hence altering the availability of contaminants and the nutrients biogeochemical cycle. As such, this study proposes to assess the effects of different GO nanosheet concentrations on the behaviour, feeding activity, mucus production, regenerative capacity, antioxidant status, biochemical damage and metabolism of H. diversicolor. This study evidenced that H. diversicolor exposed to GO nanosheets had a significantly lower ability to regenerate their bodies, took longer to feed and burrow into the sediment and produced more mucus. Membrane oxidative damage (lipid peroxidation) increased in exposed specimens. The increased metabolic rate (ETS) evidenced a higher energy expenditure in exposed organisms (high use of ready energy sources – soluble sugars) to fight the toxicity induced by GO nanosheets, such as SOD activity. The increase in SOD activity was enough to reduce reactive oxygen species (ROS) induced by GO on cytosol at the lowest concentrations, avoiding the damage on proteins (lower PC levels), but not on membranes (LPO increase). This study revealed that the presence of GO nanosheets, even at the lower levels tested, impaired behavioural, physiological, and biochemical traits in polychaetes, suggesting that the increase of this engineered nanomaterial in the environment can disturb these benthic organisms, affecting the H. diversicolor population. Moreover, given the important role of this group of organisms in coastal and estuarine food webs, the biogeochemical cycle of nutrients, and sediment oxygenation, there is a real possibility for repercussions into the estuarine community.

In the current investigation, we presented the success of the modified hydrothermal method for synthesizing the iron-oxide nanoparticles (Fe₂O₃-NPs) efficiently. These NPs were further characterized by using different techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM) micrographs, energy-dispersive X-ray spectroscopy (EDAX)/Mapping pattern, Raman Spectroscopy Pattern, ultra violet (UV) and Photoluminescence (PL). All these analyses revealed highly pure nature of Fe₂O₃-NPs with no internal defects, and suggested its application for plant growth improvement. Therefore, we further investigated the separate as well as combined effects of the Fe₂O₃-NPs and citric acid (CA) in the alleviation of arsenic (As) toxicity in the soybean (Glycine max L.), by evaluating the different plant growth and metabolic attributes. Results of our study revealed that As-induced growth inhibition, reduction of photosynthesis, water use efficiency (WUE), and reactive oxygen species (ROS) accumulation whereas application of the Fe₂O₃-NPs and CA significantly reversed all these adverse effects in soybean plants. Moreover, the As-stress induced malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) production were partially reversed by the Fe₂O₃-NPs and CA in the As-stressed plants by 16% and 10% (MDA) and 29% and 12% (H₂O₂). This might have resulted due to the Fe₂O₃-NPs and CA induced activities of the antioxidant defense in plants. Overall, the Fe₂O₃-NPs and CA supplementation separately and in combination positively regulated the As tolerance in soybean; however, the effect of the combined application on the As tolerance was more profound relative to the individual application. These results suggested the synergetic effect of the Fe₂O₃-NPs and CA on the As-tolerance in soybean. However, in-depth mechanism underlying the defense crosstalk between the Fe₂O₃-NPs and CA needs to be further explored.

Arsenic (As) toxicity is a problem that needs to be solved in terms of both human health and agricultural production in the vast majority of the world. The presence of As causes biomass loss by disrupting the balance of biochemical processes in plants and preventing growth/water absorption in the roots and accumulating in the edible parts of the plant and entering the food chain. A critical method of combating As toxicity is the use of biosafe, natural, bioactive compounds such as hesperidin (HP) or chlorogenic acid (CA). To this end, in this study, the physiological and biochemical effects of HP (100 μM) and CA (50 μM) were investigated in Zea mays under arsenate stress (100 μM). Relative water content, osmotic potential, photosynthesis-related parameters were suppressed under stress. It was determined that stress decreased the activities of the antioxidant system and increased the level of saturated fatty acids and, gene expression of PHT transporters involved in the uptake and translocation of arsenate. After being exposed to stress, HP and CA improved the capacity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), glutathione S-transferase (GST) and glutathione peroxidase (GPX) and then ROS accumulation (H₂O₂) and lipid peroxidation (TBARS) were effectively removed. These phenolic compounds contributed to maintaining the cellular redox status by regulating enzyme/non-enzyme activity/contents involved in the AsA-GSH cycle. HP and CA reversed the adverse effects of excessive metal ion accumulation by re-regulated expression of the PHT1.1 and PHT1.3 genes in response to stress. Exogenously applied HP and CA effectively maintained membrane integrity by regulating saturated/unsaturated fatty acid content. However, the combined application of HP and CA did not show a synergistic protective activity against As stress and had a negative effect on the antioxidant capacity of maize leaves. As a result, HP and CA have great potentials to provide tolerance to maize under As stress by reducing oxidative injury and preserving the biochemical reactions of photosynthesis.

Silver nanoparticles (AgNPs) of both biologically and chemically origins trigger various physiological and metabolic processes through interaction with plant cells, exerting positive, negative and inconsequential effects. However, their impacts on plant systems must be critically investigated to guarantee their safe application in food chain. In this study, the effects of chemically synthesized (synthetic) AgNPs (sAgNPs) and biologically synthesized (biogenic) AgNPs (bAgNPs) on physiological and biochemical features of Eschscholzia californica Cham were evaluated at different concentrations (0, 10, 25, 50 and 100 mg L⁻¹). Plants exposed to bAgNPs (at 10 and 25 mg L⁻¹) and sAgNPs (at 10 mg L⁻¹) displayed relatively uniform deposition of AgNPs on leaf surface, however, the higher concentration (100 mg L⁻¹) was accompanied by aggregation of AgNPs, resulting in anatomical and physiological disorders. Foliar application of both AgNPs at lower concentrations resulted in significant (P < 0.01) improve in the content of photosynthetic pigments (chlorophylls a, b, a+b, and carotenoids) and total phenolics over the control in a dose-related manner. Leaf relative water content decreased steadily with increasing both sAgNPs and bAgNPs concentrations-with sAgNPs being more inhibitive. Both types of AgNPs at 100 mg L⁻¹ significantly (P < 0.05) increased electrolyte leakage index, level of lipid peroxidation product (malondialdehyde), and leaf soluble sugar content when compared to controls. No significant difference was found on cell membrane stability index among the plants exposed to bAgNPs and sAgNPs at the lowest concentration over the control. Californidine content was significantly (P < 0.01, by 45.1%) increased upon all the bAgNPs treatments (with a peak at 25 mg L⁻¹) relative to control. The obtained extracts from plants treated with bAgNPs at lower concentrations revealed a significant induction of antioxidant capacity (based on DPPH˙ free radical scavenging and ferrous ions-chelating activities) with lower IC₅₀ values compared to the other treatments. Conclusively, bAgNPs at lower concentrations are potent elicitors of pharmaceutically active compounds biosynthesis, which enhance physiological efficiency of E. californica, but at higher concentrations bAgNPs are equally toxic as sAgNPs.

Exposure to tobacco smoke during pregnancy has been associated with a series of adverse reproductive outcomes; however, the underlying molecular mechanisms are not well-established. We conducted an untargeted metabolome-wide association study to identify the metabolic perturbations and molecular mechanisms underlying the association between cotinine, a widely used biomarker of tobacco exposure, and adverse birth outcomes. We collected early and late pregnancy urine samples for cotinine measurement and serum samples for high-resolution metabolomics (HRM) profiling from 105 pregnant women from the Atlanta African American Maternal-Child cohort (2014–2016). Maternal metabolome perturbations mediating prenatal tobacco smoke exposure and adverse birth outcomes were assessed by an untargeted HRM workflow using generalized linear models, followed by pathway enrichment analysis and chemical annotation, with a meet-in-the-middle approach. The median maternal urinary cotinine concentrations were 5.93 μg/g creatinine and 3.69 μg/g creatinine in early and late pregnancy, respectively. In total, 16,481 and 13,043 metabolic features were identified in serum samples at each visit from positive and negative electrospray ionization modes, respectively. Twelve metabolic pathways were found to be associated with both cotinine concentrations and adverse birth outcomes during early and late pregnancy, including tryptophan, histidine, urea cycle, arginine, and proline metabolism. We confirmed 47 metabolites associated with cotinine levels, preterm birth, and shorter gestational age, including glutamate, serine, choline, and taurine, which are closely involved in endogenous inflammation, vascular reactivity, and lipid peroxidation processes. The metabolic perturbations associated with cotinine levels were related to inflammation, oxidative stress, placental vascularization, and insulin action, which could contribute to shorter gestations. The findings will support the further understanding of potential internal responses in association with tobacco smoke exposures, especially among African American women who are disproportionately exposed to high tobacco smoke and experience higher rates of adverse birth outcomes.

Inhalation represents the most prevalent route of exposure with Thorium-232 compounds (Th-nitrate/Th-dioxide)/Th-containing dust in real occupational scenario. The present study investigated the mechanism of Th response in normal human alveolar epithelial cells (WI26), exposed to Th-nitrate or colloidal Th-dioxide (1–100 μg/ml, 24–72 h). Assessment in terms of changes in cell morphology, cell proliferation (cell count), plasma membrane integrity (lactate dehydrogenase leakage) and mitochondrial metabolic activity (MTT reduction) showed that Th-dioxide was quantitatively more deleterious than Th-nitrate to WI26 cells. TEM and immunofluorescence analysis suggested that Th-dioxide followed a clathrin/caveolin-mediated endocytosis, however, membrane perforation/non-endocytosis seemed to be the mode of Th internalization in cells exposed to Th-nitrate. Th-estimation by ICP-MS showed significantly higher uptake of Th in cells treated with Th-dioxide than with Th-nitrate at a given concentration. Both Th-dioxide and nitrate were found to increase the level of reactive oxygen species, which seemed to be responsible for lipid peroxidation, alteration in mitochondrial membrane potential and DNA-damage. Amongst HSPs, the protein levels of HSP70 and HSP90 were affected differentially by Th-nitrate/dioxide. Specific inhibitors of ATM (KU55933) or HSP90 (17AAG) were found to increase the Th- cytotoxicity suggesting prosurvival role of these signaling molecules in rescuing the cells from Th-toxicity.

Identifying risks to ecosystems from contaminants needs a diversity of bioindicators, to understand the effects of these contaminants on a range of taxa. Molluscs are an ideal bioindicator because they are one of the largest phyla with extremely high ecological and economic importance. The aim of this study was to evaluate if laboratory bred Potamopyrgus antipodarum has the potential to show the impact of contaminants from various land use activities and degree of pollution on a freshwater ecosystem. We assessed the impact of contaminants arising from runoff and direct discharges in Merri Creek by measuring organism level responses (survival, growth, and reproduction), and sub-organism level responses (glutathione S-transferase (GST) activity, lipid peroxidation (LPO) activity and catalase (CAT) activity) in snails after 28-d of deployment at nine sites in Merri Creek and one site in Cardinia Creek. In Merri Creek, the top two sites were reference sites (with low impact from human activities), while the rest were impact sites (impacted by various anthropogenic land uses). Cardinia Creek (an additional reference site) had lower human activity. High concentrations of heavy metals, nutrients, and/or synthetic pyrethroids (bifenthrin) dominated these sites, which are likely to have contributed towards the negative responses observed in the snails. There was little influence from environmental conditions and site location on the endpoints because we found a similar response at an additional reference site compared to the reference sites in Merri Creek. At the organism level, reproduction increased and/or reduced, while CAT was affected at the sub-organism level. Potamopyrgus antipodarum has the potential to be a sensitive bioindicator for Australian conditions because the snails responded to varying concentrations of contaminants across different land use activities and showed similar sensitivity to P. antipodarum found in other regions of the globe and other bioindicators.