Allelopathic influence of Vigna mungo (black gram) seeds on germination and radical growth of some crop plants

Intercropping of Vigna mungo (black gram) isprevalent for varied crop regimes in subtropical northern plains of India. Insugarcane, the negative impacts of a black gram intercrop on crop yields,rhizosphere soil properties and benefit: cost ratio have been reported. Thepossible allelopathic potential of black gram seeds on the germination,seedlingemergence and root elongation of other commercial crops is reported here. Theeffects of imbibed seeds of black gram, their aqueous leachate and seedextractson the germination and root elongation of seeds of four test crops viz. wheat,maize, gram and lentil, both under aseptic and soil conditions, wereinvestigated. Inhibitory effects were evident in all the bioassays of seeds ofthese crops. The black gram seeds directly and leachates were highly inhibitorybut the aqueous seed extract was less so. The observations indicate a releaseofinhibitory substances from black gram seeds leading to the observed inhibitoryeffects.     

Nitrotyrosinylation,remodeling and endothelial‐myocyte uncoupling in iNOS,cystathionine beta synthase (CBS) knockouts and iNOS/CBS double knockout mice

Increased levels of homocysteine (Hcy), recognized as hyperhomocysteinemia (HHcy), were associated with cardiovascular diseases. There was controversy regarding the detrimental versus cardio protective role of inducible nitric oxide synthase (iNOS) in ischemic heart disease. The aim of this study was to test the hypothesis that the Hcy generated nitrotyrosine by inducing the endothelial nitric oxide synthase, causing endothelial‐myocyte (E‐M) coupling. To differentiate the role of iNOS versus constitutive nitric oxide synthase (eNOS and nNOS) in Hcy‐mediated nitrotyrosine generation and matrix remodeling in cardiac dysfunction, left ventricular (LV) tissue was analyzed from cystathionine beta synthase (CBS) heterozygote knockout, iNOS homozygote knockout, CBS?/+/iNOS?/? double knockout, and wild‐type (WT) mice. The levels of nitrotyrosine, MMP‐2 and ‐9 (zymographic analysis), and fibrosis (by trichrome stain) were measured. The endothelial‐myocyte function was determined in cardiac rings. In CBS?/+ mice, homocysteine was elevated and in iNOS?/? mice, nitric oxide was significantly reduced. The nitrotyrosine and matrix metalloproteinase‐9 (MMP‐9) levels were elevated in double knockout and CBS?/+ as compared to WT mice. Although MMP‐2 levels were similar in CBS?/+, iNOS?/?, and CBS?/+/iNOS?/?, the levels were three‐ to fourfold higher than WT. The levels of collagen were similar in CBS?/+ and iNOS?/?, but they were threefold higher than WT. Interesting, the levels of collagen increased sixfold in double knockouts, compared to WT, suggesting synergism between high Hcy and lack of iNOS. Left ventricular hypertrophy was exaggerated in the iNOS?/? and double knockout, and mildly increased in the CBS?/+, compared to WT mice. The endothelial‐dependent relaxation was attenuated to the same extent in the CBS?/+ and iNOS?/?, compared to WT, but it was robustly blunted in double knockouts. The results concluded that homocysteine generated nitrotyrosine in the vicinity of endothelium, caused MMP activation and endothelium‐myocyte uncoupling. The generation of nitrotyrosine was independent of iNOS. J. Cell. Biochem. 106: 119–126, 2009. © 2008 Wiley‐Liss, Inc.     

Modeling of Graphene Coplanar Waveguide and its Discontinuities for THz Integrated Circuits Applications

Plasmonics - Graphene, having extraordinary electronic and optical properties at THz frequencies, can be used in the design and development of miniaturized components, devices, and integrated...     

Clonal Variability and Its Relevance in Generation of New Pathotypes in the Spot Blotch Pathogen, <Emphasis Type="Italic">Bipolaris sorokiniana</Emphasis>

Spot blotch pathogen Bipolaris sorokiniana of wheat was investigated with threefold objectives: to establish a relationship between morphological and pathological variability of isolates, identify clonal genotype(s) acting as a source for the generation of new variability, and to determine the mechanism of generation of such variability in the pathogen. Isolates were collected from the leaves and seeds of field-grown wheat crop at four different sites in eastern Gangetic plains of India. Eighty-six clonal isolates derived from a single isolate (gray with white patches, Group III), which segregated in an equal proportion of parental and nonparental types, were studied. Morphological characters—i.e., colony morphology, growth rate, and sporulation—were studied along with disease-causing ability of the isolate clones. Clonal isolates were grouped into three categories. Microscopic analysis of nuclei was done to determine the causes of such variability. Morphological variability appeared to be related to the pathological variability. The isolate having epidemic potential appeared different than that acting as the reservoir for variability. The cause of such variability could be attributed either to hyphal fusion and heterokaryosis, nuclear migration and occurrence of multinucleate state, or a combination of these factors. Random Amplified Polymorphic DNA (RAPD) assay suggested that the unique fragments for different groups could be utilized as molecular markers to identify the isolates of specific groups.     

Homocysteine decreases blood flow to the brain due to vascular resistance in carotid artery

An elevated level of Homocysteine (Hcy) is a risk factor for vascular dementia and stroke. Cysthathionine β Synthase (CBS) gene is involved in the clearance of Hcy. Homozygous individuals for (CBS−/−) die early, but heterozygous for (CBS−/+) survive with high levels of Hcy. The γ-Amino Butyric Acid (GABA) presents in the central nervous system (CNS) and functions as an inhibitory neurotransmitter. Hcy competes with GABA at the GABA_A receptor and affects the CNS function. We hypothesize that Hcy causes a decrease in blood flow to the brain due to increase in vascular resistance (VR) because of arterial remodeling in the carotid artery (CA). Blood pressure and blood flow in CA of wild type (WT), CBS−/+, CBS−/+ GABA_A−/− double knockout, and GABA_A−/− were measured. CA was stained with trichrome, and the brain permeability was measured. Matrix Metalloproteinases (MMP-2 and MMP-9), tissue inhibitor of metalloproteinase (TIMP-3, TIMP-4), elastin, and collagen-III expression were measured by real-time polymerase chain reaction (RT-PCR). Results showed an increase in VR in CBS−/+/GABA_A−/−double knockout > CBS−/+/ > GABA_A−/− compared to WT mice. Increased MMP-2, MMP-9, collagen-III and TIMP-3 mRNA levels were found in GABA_A−/−, CBS−/+, CBS−/+/GABA_A double knockout compared to WT. The levels of TIMP-4 and elastin were decreased, whereas the levels of MMP-2, MMP-9 and TIMP-3 increased, which indirectly reflected the arterial resistance. These results suggested that Hcy caused arterial remodeling in part, by increase in collagen/elastin ratio thereby increasing VR leading to the decrease in CA blood flow.     

Overexpression of the putative thiol conjugate transporter TbMRPA causes melarsoprol resistance in Trypanosoma brucei

Melaminophenyl arsenical drugs are a mainstay of chemotherapy against late-stage African sleeping sickness, but drug resistance is increasingly prevalent. We describe here the characterization of two genes encoding putative metal-thiol conjugate transporters from Trypanosoma brucei. The two proteins, TbMRPA and TbMRPE, were each overexpressed in trypanosomes, with or without co-expression of two key enzymes in trypanothione biosynthesis, ornithine decarboxylase and gamma-glutamyl-cysteine synthetase. Overexpression of gamma-glutamyl-cysteine synthetase resulted in a twofold increase in cellular trypanothione, whereas overexpression of ornithine decarboxylase had no effect on the trypanothione level. The overexpression of TbMRPA resulted in a 10-fold increase in the IC50 of melarsoprol. The overexpression of the trypanothione biosynthetic enzymes alone gave two- to fourfold melarsoprol resistance, but did not enhance resistance caused by MRPA. Overexpression of TbMRPE had little effect on susceptibility to melarsoprol but did give two- to threefold resistance to suramin.     

Hgt1p, a high affinity glutathione transporter from the yeast Saccharomyces cerevisiae

A high affinity glutathione transporter has been identified, cloned, and characterized from the yeast Saccharomyces cerevisiae. This transporter, Hgt1p, represents the first high affinity glutathione transporter to be described from any system so far. The strategy for the identification involved investigating candidate glutathione transporters from the yeast genome sequence project followed by genetic and physiological investigations. This approach revealed HGT1 (open reading frame YJL212c) as encoding a high affinity glutathione transporter. Yeast strains deleted in HGT1 did not show any detectable plasma membrane glutathione transport, and hgt1Delta disruptants were non-viable in a glutathione biosynthetic mutant (gsh1Delta) background. The glutathione repressible transport activity observed in wild type cells was also absent in the hgt1Delta strains. The transporter was cloned and kinetic studies indicated that Hgt1p had a high affinity for glutathione (K(m) = 54 micrometer)) and was not sensitive to competition by amino acids, dipeptides, or other tripeptides. Significant inhibition was observed, however, with oxidized glutathione and glutathione conjugates. The transporter reveals a novel class of transporters that has homologues in other yeasts and plants but with no apparent homologues in either Escherichia coli or in higher eukaryotes other than plants.