Arsenic-induced root growth inhibition in mung bean (<Emphasis Type="Italic">Phaseolus aureus</Emphasis> Roxb.) is due to oxidative stress resulting from enhanced lipid peroxidation

Arsenic (As) toxicity and its biochemical effects have been mostly evaluated in ferns and a few higher plants. In this study, we investigated the effect of As (10.0 and 50.0 μM) on seedling growth, root anatomy, lipid peroxidation (malondialdehyde and conjugated dienes), electrolyte leakage, H₂O₂ content, root oxidizability and the activities of antioxidant enzymes in mung bean (Phaseolus aureus Roxb.). Arsenic significantly enhanced lipid peroxidation (by 52% at 50.0 μM As), electrolyte leakage and oxidizability in roots. However, there was no significant change in H₂O₂ content. Arsenic toxicity was associated with an increase in the activities of superoxide dismutase (SOD), guaiacol peroxidase (GPX) and glutathione reductase (GR). In response to 50.0 μM As, the activities of SOD and GR increased by over 60% and 90%, respectively. At 10.0 μM As, the activity of ascorbate peroxidase (APX) increased by 83%, whereas at 50.0 μM it declined significantly. The catalase (CAT) activity, on the other hand, decreased in response to As exposure, and it corresponded to the observed decrease in H₂O₂ content. We conclude that As causes a reduction in root elongation by inducing an oxidative stress that is related to enhanced lipid peroxidation, but not to H₂O₂ accumulation.     

Axial stretch: A novel mechanism of the lower esophageal sphincter relaxation

Swallow and esophageal distension-induced relaxations of the lower esophageal sphincter (LES) are associated with an orad movement of the LES because of a concurrent esophageal longitudinal muscle contraction. We hypothesized that the esophageal longitudinal muscle contraction induces a cranially directed mechanical stretch on the LES and therefore studied the effects of a mechanical stretch on the LES pressure. In adult opossums, a silicon tube was placed via mouth into the esophagus and laparotomy was performed. Two needles with silk sutures were passed, 90 degrees apart, through the esophageal walls and silicon tube, 2 cm above the LES. The tube was withdrawn, and one end of each of the four sutures was anchored to the esophageal wall and the other end exited through the mouth to exert graded cranially directed stretch on the LES by using pulley and weights. A cranially directed stretch caused LES relaxation, and with the cessation of stretch there was recovery of the LES pressure. The degree an d duration of LES relaxation increased with the weight and the duration of stretch, respectively. The mean LES relaxation in all animals was 77.7 +/- 4.7%. The required weight to induce maximal LES relaxation differed in animals (714 +/- 348 g). N(G)-nitro-L-arginine, a nitric oxide inhibitor, blocked the axial stretch-induced LES relaxation almost completely (from 78 to 19%). Our data support the presence of an axial stretch-activated inhibitory mechanism in the LES. The role of axial stretch in the LES relaxation induced by swallow and esophageal distension requires further investigation.     

Assessment of phytotoxicity of parthenin

Phytotoxicity of parthenin, a sesquiterpene lactone, was evaluated against four weedy species (Amaranthus viridis, Cassia occidentalis, Echinochloa crus-galli, and Phalaris minor) through a series of experiments conducted under laboratory or greenhouse conditions to assess its herbicidal potential. Under laboratory conditions, parthenin (0.5-2 mM) severely reduced seedling growth (root and shoot) and dry weight of test weeds. However, the effect was greater on root growth. Parthenin (1 mM) suppressed the mitotic activity in the onion root tip cells that could possibly be responsible for the reduction in seedling growth. Both pre- and post-emergent application of parthenin caused a significant loss of chlorophyll pigments and affected photosynthesis. Parthenin ( > or =1 mM) caused an excessive electrolyte leakage in the plant tissues which was light-dependent. The root inhibition was associated with swelling and blackening of the root tip, shriveling and damage to the epidermal tissue and non-formation of root hairs. The study concludes that parthenin possesses weed-suppressing potential (both pre- and post-).     

Biologically active human GM-CSF produced in the seeds of transgenic rice plants

Rice flour is a well-known and characterized source of pharmaceutical ingredients, which are gluten-free and incorporated in many drug delivery applications such as excipient starch. To further exploit this uniqueness, the synthetic capacity of rice endosperm tissue, the basis of rice flour, was extended by genetic transformation. Recombinant human GM-CSF, a cytokine used in treating neutropenia and with other potential clinical applications, has been expressed in transgenic rice seeds using a rice glutelin promoter. Rice seeds accumulated human GM-CSF to a level of 1.3% of total soluble protein. The rice seed-produced human GM-CSF was found to be biologically active when tested using a human cell line TF-1. Use of rice as a host plant offers not only attractive features of safe production in seeds but also self-containment of foreign genes, as rice is primarily a self-pollinated crop plant. Ravinder Sardana and Anil K. Dudani contributed equally to this work.     

Formation of amyloid fibrils via longitudinal growth of oligomers

Mature amyloid fibrils are believed to be formed by the lateral association of discrete structural units designated as protofibrils, but this lateral association of protofibrils has never been directly observed. We have recently characterized a thioesterase from Alcaligenes faecalis, which was shown to exist as homomeric oligomers with an average diameter of 21.6 nm consisting of 22 kDa subunits in predominantly beta-sheet structure. In this study, we have shown that upon incubation in a 75% ethanol solution, the oligomeric particles of protein were transformed into amyloid-like fibrils. TEM pictures obtained at various stages during fibril growth helped us to understand to a certain extent the early events in the fibrillization process. When incubated in 75% ethanol, oligomeric particles of protein grew to approximately 35-40 nm in diameter before fusion. Fusion of two oligomers of 35-40 nm resulted in the formation of a fibril. Fibril formation was accompanied by a reduction in the diameter of the particle to approximately 20-25 nm along with concomitant elongation to approximately 110 nm, indicating reorganization and strengthening of the structure. The elongation process continued by sequential addition of oligomeric units to give fibers 500-1000 nm in length with a further reduction in diameter to 17-20 nm. Further elongation resulted in the formation of fibers that were more than 4000 nm in length; the diameter, however, remained constant at 17-20 nm. These data clearly show that the mature fibrils have assembled via longitudinal growth of oligomers and not via lateral association of protofibrils.     

Design,Synthesis, and Molecular Docking Studies of Some New Quinoxaline Derivatives as EGFR Targeting Agents

Russian Journal of Bioorganic Chemistry - The synthesis of some new quinoxaline derivatives (IVa–n) and their structure determination using 1H&nbsp;NMR, 13C NMR and mass spectral analysis...     

Single-Cell Transcriptomics Uncovers Glial Progenitor Diversity and Cell Fate Determinants during Development and Gliomagenesis

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Induction of non-protein thiols and phytochelatins by cadmium in Eichhornia crassipes

Abstract

Impact of root Cd concentration on production of cysteine, non-protein thiols (NP-SH), glutathione (GSH), reduced glutathione (GSSG), and phytochelatins (PCs) in Eichhornia crassipes exposed to different dilutions of brass and electroplating industry effluent (25%, 50%, and 75%), and synthetic metal solutions of Cd alone (1, 2.5, and 3.5?ppm) and with Cr (1?ppm Cd + 1?ppm Cr, 2.5?ppm Cd + 3?ppm Cr, and 3.5?ppm Cd + 4?ppm Cr) was assessed in a 45?days study. Different treatments were used to understand and compare differential antioxidant defense response of plant under practical drainage (effluent) and experimental synthetic solutions. The production of NP-SH and cysteine was maximum under 2.5?ppm Cd + 3?ppm Cr treatments i.e., 1.78?µmol/g fw and 288?nmol/g fw, respectively. The content of GSH declined whereas that of GSSG increased progressively with exposure duration in all treatments. HPLC chromatograms revealed that the concentrations of PC2, PC3, and PC4 (248, 250, and 288?nmol-SH equiv.g^?1 fw, respectively) were maximum under 1?ppm Cd, 1?ppm Cd + 1?ppm Cr, and 2.5?ppm Cd + 3?ppm Cr treatments, respectively. PC2, PC3, and PC4 concentrations increased with Cd accumulation in the range 812–1354?µg/g dry wt, 1354–2032?µg/g dry wt and 2032–3200?µg/g dry wt, respectively. Thus, the study establishes a direct proportionality relationship between concentration/length of phytochelatins and root Cd concentrations, upto threshold limits, in E. crassipes.     

HIV-1 diseases progression associated with loss of Th17 cells in subtype 'C' infection

Th17 cells play a crucial role in host immune response. We examined the role of Th17 cells in HIV-1 'subtype-C' infection and report that HIV-1 specific Th17 cells are induced in early infection and slow progressors but are significantly reduced at late stage of infection. There was a further decline in Th17 cells in late stage subjects with gastrointestinal infections. Additionally, we observed expanded population of IL-21 (needed for Th17 population expansion) producing CD4 T cells in early and slow progressors compared to subjects with late stage infection. A significant positive correlation existed between virus specific IL-17 and IL-21 producing CD4 T cells suggesting that HIV-1 infection induces a demand for Th17 cells. A significant negative correlation between virus specific Th17 cells and HIV-1 plasma viral load (pVL) was also observed, indicating a gradual loss of Th17 cells with HIV-1 disease progression.     

Magnetic resonance imaging of glutamate

Glutamate, a major neurotransmitter in the brain, shows a pH- and concentration-dependent chemical exchange saturation transfer effect (GluCEST) between its amine group and bulk water, with potential for in vivo imaging by nuclear magnetic resonance. GluCEST asymmetry is observed ～3 p.p.m. downfield from bulk water. Middle cerebral artery occlusion in the rat brain resulted in an ～100% elevation of GluCEST in the ipsilateral side compared with the contralateral side, predominantly owing to pH changes. In a rat brain tumor model with blood-brain barrier disruption, intravenous glutamate injection resulted in a clear elevation of GluCEST and a similar increase in the proton magnetic resonance spectroscopy signal of glutamate. GluCEST maps from healthy human brain were also obtained. These results demonstrate the feasibility of using GluCEST for mapping relative changes in glutamate concentration, as well as pH, in vivo. Contributions from other brain metabolites to the GluCEST effect are also discussed.