Environmentally relevant lead alters nuclear integrity in erythrocytes and generates oxidative stress in liver of Anabas testudineus: Involvement of Nrf2-Keap1 regulation and expression of biomarker genes.

Genotoxic and hepatotoxic effects of lead (Pb) on a freshwater fish, climbing perch (Anabas testudineus) were studied at an environmentally relevant concentration (43.3 ppm). The genotoxic potential of Pb was confirmed by micronucleus study, with increased frequencies of erythrocytic nuclear alterations like lobed, blebbed, notched, fragmented, and micronuclei were observed in erythrocytes in treated groups as compared to control. Inorganic Pb induces oxidative stress which is a consequence of elevated level of Reactive Oxygen Species. Hepatotoxicity was assessed both by the oxidative stress and cellular responses that emerged due to the toxic assault of Pb in the liver, the most important detoxifying organ. Upregulation of xenobiotic metabolizing enzyme like catalase was evident after 15, 30, and 90 days of exposure, and a profound effect was observed on 30th days. The level of lipid peroxidation and reduced glutathione was increased after Pb exposure. Histoarchitectural damages of liver were distinctly evident in treated fish. Western blot analysis confirmed the expressional alterations of stress-responsive marker proteins like Nrf2, Keap1, Hsp70, and Nqo1. Pb exposure resulted in increased expression of Hsp70, Nrf2, and Nqo1, whereas Keap1 was downregulated, suggesting the involvement of Nrf2-Keap1 regulation as a cytoprotective mechanism against Pb toxicity.

Arsenic and chromium induced hepatotoxicity in zebrafish (Danio rerio) at environmentally relevant concentrations: Mixture effects and involvement of Nrf2-Keap1-ARE pathway.

Arsenic (As) and chromium (Cr), two well-known cytotoxic and carcinogenic metals are reported to coexist in industrial effluents and groundwater. Their individual toxicities have been thoroughly studied but the combined effects, especially the mechanism of toxicity and cellular stress response remain unclear. Considering co-exposure as a more realistic scenario, current study compared the individual and mixture effects of As and Cr in the liver of zebrafish (Danio rerio). Fish were exposed to environmentally relevant concentrations of As and Cr for 15, 30 and 60 days. ROS generation, biochemical stress parameters like lipid peroxidation, reduced glutathione content, catalase activity and histological alterations were studied. Results showed increase in ROS production, MDA content and GSH level; and vicissitude in catalase activity as well as altered histoarchitecture, indicating oxidative stress conditions after individual and combined exposure of As and Cr which were additive in nature. This study also included the expression of Nrf2, the key regulator of antioxidant stress responses and its nuclear translocation. Related antioxidant and xenobiotic metabolizing enzyme genes like keap1, nqo1, ho1, mnsod and cyp1a were also studied. Overall results indicated increased nrf2, nqo1, ho1, mnsod expression at all time points and increased cyp1a expression after 60 days exposure. Emphasizing on the Nrf2-Keap1 pathway, this study exhibited additive or sometimes synergistic effects of As and Cr in zebrafish liver.

Lead induced genotoxicity and hepatotoxicity in zebrafish (Danio rerio) at environmentally relevant concentration: Nrf2-Keap1 regulated stress response and expression of biomarker genes.

Genotoxic and hepatotoxic potentials of Pb at an environmentally relevant concentration (5 ppm) in zebrafish were investigated in the present study. Erythrocytic nuclear abnormality tests revealed the increased frequencies of abnormal erythrocytes after Pb exposure, indicating a strong genotoxic potential of Pb. Multiple stress-related parameters were further evaluated in liver, the major detoxifying organ. Pb caused increased production of ROS, which in turn caused severe oxidative stress. As a result, lipid peroxidation was increased, whereas reduced glutathione level and catalase activity was decreased. Alterations in liver histoarchitecture also served as evidence of Pb-induced hepatotoxicity. Pb-induced ROS stress triggered upregulation of Nrf2, Nqo1, Ho1; downregulation of Keap1, and altered mRNA expressions of Mn-sod, Cu/Zn-sod, gpx1, cyp1a, ucp2 suggesting involvement of Nrf2-Keap1-ARE signaling in cellular defence. Nrf2-keap1 is a sensitive biomarker of Pb-induced ROS stress. Overexpression of Hsp70 and other genes in hepatocytes might help cell survival under oxidative stress generation.

A Short Review on Polymeric Biomaterials as Additives for Lubricants.

With increasing environmental concerns and the depletion of petroleum resources, the development of lubricant additives from bioresources has attracted much attention recently. In this review, we reported a few polymers and polymer composites that are synthesized from vegetable oils (soybean oil, sunflower oil, rice bran oil, and castor oil) and used as multifunctional additives in the formulation of eco-friendly lubricant compositions. We mentioned the preparation of vegetable oil-based homo- and copolymers and their characterization by different spectral techniques (FTIR/NMR). The average molecular weights of the polymers are determined by gel permeation chromatography (GPC). Performance evaluations of the polymeric materials mainly as a viscosity index improver (VII), pour point depressant (PPD), and most importantly antifriction additives when blended with lubricating base oils are indicated. Standard ASTM methods have been applied to evaluate their performances. The findings have shown that all the additives discussed are non-toxic, biodegradable, and showed excellent performances compared to commercial petroleum-based additives.

Polyacrylate-magnetite nanocomposite as a potential multifunctional additive for lube oil.

The application of polymer nanocomposites (PNCs) in lubricant industry has attracted considerable interest due to their much enhanced properties compared to neat polymers. In this study, magnetite (Fe3O4) nanoparticles (NPs) were synthesized. Then PNCs were prepared by reinforcing these NPs in the homopolymer of dodecyl acrylate in different percentages. The characterization of the prepared NPs and PNCs was done by different analytical techniques. Thermal stability is determined through thermogravimetric analysis (TGA). Performance evaluation of the PNCs as viscosity index improver, pour point depressant and antiwear additive was carried out by blending them with a mineral base stock at different percentage ratios. Standard ASTM methods are followed to carry out the evaluations. It is found that with increasing the percentage of nanocomposites in the base stock, the overall performance of the furnished lubricant is enhanced.

Large Magnetoelectric Coupling in the Thin Film of Multiferroic CuO.

We report observation of large magnetoelectric coupling in an epitaxial thin film of multiferroic CuO grown on the (100)MgO substrate by the pulsed laser deposition technique. The film is characterized by X-ray diffraction, transmission electron microscopy, and Raman spectrometry. The crystallographic structure of the film turns out to be monoclinic (space group C2/c) with [111]CuO||[100]MgO "out-of-plane" epitaxy and "in-plane" domain structure. The lattice misfit strain is found to vary within ±1-3%. The dc resistivity, magnetization, dielectric spectroscopy, and remanent ferroeletric polarization have been measured across 80-300 K. The dielectric constant is found to decrease by >20% under a moderate magnetic field of ∼18 kOe while the remanent ferroelectric polarization, emerging at the onset of magnetic transition (T N ∼ 175 K), decreases by nearly 50% under ∼18 kOe field. These results could assume importance as the strain-free bulk CuO does not exhibit magnetoelectric coupling within such magnetic field regime. The strain-induced large magnetoelectric coupling in the CuO thin film would generate new possibility of further strain tuning to observe room-temperature magnetoelectric multiferroicity suitable for scores of applications such as memories, sensors, energy-harvesting devices, generators, amplifiers, and so forth.

Tuning the growth pattern in 2D confinement regime of Sm2O3 and the emerging room temperature unusual superparamagnetism.

Programming the reaction chemistry for superseding the formation of Sm2O3 in a competitive process of formation and dissolution, the crystal growth patterns are varied and two different nanostructures of Sm2O3 in 2D confinement regime are designed. Among these, the regular and self-assembled square platelets nanostructures exhibit paramagnetic behavior analogous to the bulk Sm2O3. But, the other one, 2D flower like shaped nanostructure, formed by irregular crystal growth, shows superparamagnetism at room temperature which is unusual for bulk paramagnet. It has been noted that the variation in the crystal growth pattern is due to the difference in the binding ability of two organic ligands, oleylamine and oleic acid, used for the synthesis and the magnetic behavior of the nanostructures is related to the defects incorporated during the crystal growth. Herein, we inspect the formation chemistry and plausible origin of contrasting magnetism of these nanostructures of Sm2O3.