Protective Role of Quercetin on Polychlorinated Biphenyls (Aroclor‐1254) Induced Oxidative Stress and Apoptosis in Liver of Adult Male Rats

The present study aims to investigate the protective effect of quercetin against Aroclor‐1254–induced hepatotoxicity in rats. Male Wistar rats were grouped into Group I control received vehicle (corn oil; 1 mL/kg bwt); Group II quercetin alone (50 mg/kg bwt/day orally); Group III Aroclor‐1254 (2 mg/kg bwt/day intraperitoneally); Group IV Aroclor‐1254 + quercetin treated for 30 days. The Aroclor‐1254 treatment caused significant alteration in the biochemical parameters (hydrogen peroxide, lipid peroxidation, reduced glutathione levels, and alkaline phosphatase activity). The expressions of apoptotic and antiapoptotic proteins and the liver histology of Aroclor‐1254–exposed rats showed cytoplasmic degeneration along with infiltration of polymorphonuclear cells. Whereas simultaneous treatment with quercetin normalized all the biochemical parameters, consequently it inhibited apoptosis mediated by Aroclor‐1254 by downregulating aryl hydrocarbon receptor, p53 and apoptotic protein (Bax, caspase‐9, caspase‐3) and upregulating the antiapoptotic protein (Bcl‐2) expression patterns; thereby, quercetin reduces alteration in hepatocellular morphology. Thus quercetin exhibited hepatoprotective effect. © 2012 Wiley Periodicals, Inc. J BiochemMol Toxicol 26:522‐532, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21466     

In silico analysis of DosR regulon proteins of Mycobacterium tuberculosis

One of the challenges faced by Mycobacterium tuberculosis (M. tuberculosis) in dormancy is hypoxia. DosR/DevR of M. tuberculosis is a two component dormancy survival response regulator which induces the expression of 48 genes. In this study, we have used DosR regulon proteins of M. tuberculosis H37Rv as the query set and performed a comprehensive homology search against the non-redundant database. Homologs were found in environmental mycobacteria, environmental bacteria and archaebacteria. Analysis of genomic context of DosR regulon revealed that they are distributed as nine blocks in the genome of M. tuberculosis with many transposases and integrases in their vicinity. Further, we classified DosR regulon proteins into eight functional categories. One of the hypothetical proteins Rv1998c could probably be a methylisocitrate lyase or a phosphonomutase. Another hypothetical protein, Rv0572 was found only in mycobacteria. Insights gained in this study can potentially aid in the development of novel therapeutic interventions.     

Naked eye sensing of toxic metal ions in aqueous medium using thiophene‐based ligands and its application in living cells

Thiophene‐based diimine (R1) and monoimine (R2) were synthesized in a single step, and their cation binding affinity was tested using colorimetric and UV–vis spectral studies. R1 selectively shows a colorimetric turn‐on response for Pb²⁺, Hg²⁺ ions and colorimetric turn‐off with Sn²⁺ ions, and R2 shows visual response for Cu²⁺ and Hg²⁺ over other examined metal ions in aqueous medium. R1 forms 1:1 complex with Pb²⁺, Hg²⁺, and Sn²⁺ and exhibits fluorescence quenching, whereas R2 shows 2:1 complex with Hg²⁺, Cu²⁺ and shows fluorescence enhancement. The structural and electronic properties of the sensors and their metal complexes were also investigated using Density Functional Theory calculations. R2 was also successfully demonstrated as a fluorescent probe for detecting Cu²⁺ ions in living cells. Copyright © 2014 John Wiley & Sons, Ltd.     

A unique macrophage subpopulation signals directly to progenitor cells to promote regenerative neurogenesis in the zebrafish spinal cord

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Possible role of HIWI2 in modulating tight junction proteins in retinal pigment epithelial cells through Akt signaling pathway

PIWI subfamily of proteins is shown to be primarily expressed in germline cells. They maintain the genomic integrity by silencing the transposable elements. Although the role of PIWI proteins in germ cells has been documented, their presence and function in somatic cells remains unclear. Intriguingly, we detected all four members of PIWI-like proteins in human ocular tissues and somatic cell lines. When HIWI2 was knocked down in retinal pigment epithelial cells, the typical honeycomb morphology was affected. Further analysis showed that the expression of tight junction (TJ) proteins, CLDN1, and TJP1 were altered in HIWI2 knockdown. Moreover, confocal imaging revealed disrupted TJP1 assembly at the TJ. Previous studies report the role of GSK3β in regulating TJ proteins. Accordingly, phospho-kinase proteome profiler array indicated increased phosphorylation of Akt and GSK3α/β in HIWI2 knockdown, suggesting that HIWI2 might affect TJ proteins through Akt-GSK3α/β signaling axis. Moreover, treating the HIWI2 knockdown cells with wortmannin increased the levels of TJP1 and CLDN1. Taken together, our study demonstrates the presence of PIWI-like proteins in somatic cells and the possible role of HIWI2 in preserving the functional integrity of epithelial cells probably by modulating the phosphorylation status of Akt.