Chemical constituents and antibacterial activity of the leaf essential oil of <Emphasis Type="Italic">Feronia limonia</Emphasis>

Bioleaching of uranium was carried out with Turamdih ore sample procured from Uranium Corporation of India Limited, Jaduguda. The bacterial strain that was used in the leaching experiments was isolated from the Jaduguda mine water sample. Efficiency of bioleaching was studied by varying parameters like pulp density and initial ferrous concentration as source of energy. It is observed that the efficiency of bioleaching was 49% at 10% pulp density (w/v) and initial pH 2.0. Addition of external has no effect on efficiency of bioleaching showing domination of direct leaching mechanism over indirect.     

Screening of certain mangroves for photosynthetic carbon metabolic pathway

The mangroves Rhizophora lamarkii, Ceriops roxburghiana, Bruguiera gymnorrhiza, Aegiceras corniculatum, and Lumnitzera racemosa were screened for their carbon metabolic pathways by measuring net photosynthetic rate (P _N), ¹³C discrimination rate, leaf anatomy, titratable acidity, and activities of phosphoenolpyruvate carboxylase, NADH-malate dehydrogenase, alanine aminotransferase, aspartate aminotransferase, and pyruvate phosphate dikinase. The tested mangroves had a well developed succulence, opening of stomata during day time and closure in the night hours, and absence of diurnal fluctuation of organic acids in their leaves which excludes the possibility of these species being CAM plants. Moreover, the leaf anatomy had not exhibited Kranz syndrome. The high values of discrimination against ¹³C, low P _N, high CO₂ compensation concentration, and the activities of aminotransferases in the direction of alanine formation suggest that the species may follow C₃ mode of carbon metabolic pathway.     

Decoding the distribution of glycan receptors for human-adapted influenza A viruses in ferret respiratory tract

Ferrets are widely used as animal models for studying influenza A viral pathogenesis and transmissibility. Human-adapted influenza A viruses primarily target the upper respiratory tract in humans (infection of the lower respiratory tract is observed less frequently), while in ferrets, upon intranasal inoculation both upper and lower respiratory tract are targeted. Viral tropism is governed by distribution of complex sialylated glycan receptors in various cells/tissues of the host that are specifically recognized by influenza A virus hemagglutinin (HA), a glycoprotein on viral surface. It is generally known that upper respiratory tract of humans and ferrets predominantly express α2→6 sialylated glycan receptors. However much less is known about the fine structure of these glycan receptors and their distribution in different regions of the ferret respiratory tract. In this study, we characterize distribution of glycan receptors going beyond terminal sialic acid linkage in the cranial and caudal regions of the ferret trachea (upper respiratory tract) and lung hilar region (lower respiratory tract) by multiplexing use of various plant lectins and human-adapted HAs to stain these tissue sections. Our findings show that the sialylated glycan receptors recognized by human-adapted HAs are predominantly distributed in submucosal gland of lung hilar region as a part of O-linked glycans. Our study has implications in understanding influenza A viral pathogenesis in ferrets and also in employing ferrets as animal models for developing therapeutic strategies against influenza.     

HIV-1 Nef Down-Modulates C-C and C-X-C Chemokine Receptors via Ubiquitin and Ubiquitin-Independent Mechanism

Human and Simian Immunodeficiency virus (HIV-1, HIV-2, and SIV) encode an accessory protein, Nef, which is a pathogenesis and virulence factor. Nef is a multivalent adapter that dysregulates the trafficking of many immune cell receptors, including chemokine receptors (CKRs). Physiological endocytic itinerary of agonist occupied CXCR4 involves ubiquitinylation of the phosphorylated receptor at three critical lysine residues and dynamin-dependent trafficking through the ESCRT pathway into lysosomes for degradation. Likewise, Nef induced CXCR4 degradation was critically dependent on the three lysines in the C-terminal -SSLKILSKGK- motif. Nef directly recruits the HECT domain E3 ligases AIP4 or NEDD4 to CXCR4 in the resting state. This mechanism was confirmed by ternary interactions of Nef, CXCR4 and AIP4 or NEDD4; by reversal of Nef effect by expression of catalytically inactive AIP4-C830A mutant; and siRNA knockdown of AIP4, NEDD4 or some ESCRT-0 adapters. However, ubiquitinylation dependent lysosomal degradation was not the only mechanism by which Nef downregulated CKRs. Agonist and Nef mediated CXCR2 (and CXCR1) degradation was ubiquitinylation independent. Nef also profoundly downregulated the naturally truncated CXCR4 associated with WHIM syndrome and engineered variants of CXCR4 that resist CXCL12 induced internalization via an ubiquitinylation independent mechanism.     

Use of sialylated or sulfated derivatives and acrylamide copolymers of Galβ1,3GalNAcα- and GalNAcα- to determine the specificities of blood group T- and Tn-specific lectins and the copolymers to measure anti-T and anti-Tn antibody levels in cancer patients

Sialylated or sulfated derivatives and acrylamide copolymers of blood group T-(Gal1,3GalNAc-) and Tn-(GalNAc) haptens were studied for their interaction with the lectins of peanut (PNA),Agaricus bisporus-(ABA),Helix pomatia-(HPA) andVicia villosa B₄-(VVA), using asialo Cowper's gland mucin (ACGM), which contains both T and Tn epitopes, as the coating substrate in enzyme linked lectin assay. Both T and Tn copolymers (40 haptens) showed high affinity and strict specificity; although the T-copolymer at 0.05–0.07 µm concentration caused 50% inhibition of interaction of either PNA or ABA with ACGM, there was little inhibition of the HPA and VVA interactions at over 100 times that concentration. The Tn-copolymer at 0.02–0.05 µm inhibited HPA or VVA interaction with ACGM by 50% but gave virtually no inhibition of PNA and ABA binding. Sialyl, sulfate or methyl group substitution on C-6 of GalNAc of the T-haptene did not prevent interaction with PNA but almost abolished interaction with ABA. In contrast, sialyl or sulfate group on C-6 and sulfate on C-3 of Gal in Gal1,3GalNAc- inhibited almost completely the interaction of PNA with ACGM but had only a slight effect on the interaction of ABA; C-6 substitution with either sialic acid or sulfate on GalNAc- almost abolished the interaction of both HPA and VVA with ACGM. Preliminary studies revealed a significant depression in the serum level of anti-T (two to three-fold decrease) and anti-Tn ( two-fold decrease) antibodies in breast cancer compared with normal control subjects when the acrylamide T- and Tn-copolymers were used as coating substrates in enzyme linked immunoassays.Abbreviations PNA peanut agglutinin - ABA agaricus bisporus agglutinin - HPA helix pomatia agglutinin - VVA (B4),vicia villosa agglutinin - ACGM Asialo Copwer's gland mucin - CA carcinoma - BSA bovine serum albumin - HRP Horseradish peroxidase - ABTS 2,2-azino-di (3-ethyl-benzthiazoline sulfonate) - ELISA enzyme-linked immunosorbent assay - Al allyl - Bn benzyl - AA acrylamide - CP copolymer     

Bi-transgenic Mice Reveal that K-rasVal12 Augments a p53-independent Apoptosis When Small Intestinal Villus Enterocytes Reenter the Cell Cycle

Studies in cell culture systems have indicated that oncogenic forms of Ras can affect apoptosis. Activating mutations of Ras occur in ~30% of all human tumors and 50% of colorectal carcinomas. Since these mutations appear at early or intermediate stages in multistep journeys to neoplasia, an effect on apoptosis may help determine whether initiated cells progress towards a more neoplastic state. We have tested the effects of K-ras^Val12 on apoptosis in transgenic mice. A lineage-specific promoter was used to direct expression of human K-ras^Val12, with or without wild-type (wt) or mutant SV-40 T antigens (TAg), in postmitotic villus enterocytes, the principal cell type of the small intestinal epithelium. Enterocytes can be induced to reenter the cell cycle by TAg^Wt. Reentry is dependent upon the ability of TAg to bind pRB and is associated with a p53-independent apoptosis. Analyses of K-ras^Val12 × TAg^Wt bi-transgenic animals indicated that K-ras^Val12 can enhance this apoptosis threefold but only in cycling cells; increased apoptosis does not occur when K-ras^Val12 is expressed alone or with a TAg containing Glu^107,108→ Lys^107,108 substitutions that block its ability to bind pRB. Analysis of bi-transgenic K-ras^Val12 × TAg^Wt mice homozygous for wild-type or null p53 alleles established that the enhancement of apoptosis occurs through a p53-independent mechanism, is not attributable to augmented proliferation or to an increase in abortive cell cycle reentry (compared to TAg^Wt mice), and is not associated with detectable changes in the crypt–villus patterns of expression of apoptotic regulators (Bcl-2, Bcl-x_L, Bak, and Bax) or mediators of epithelial cell–matrix interactions and survival (e.g., α₅β₁ integrin and its ligand, fibronectin). Coexpression of K-ras^Val12 and TAg^Wt produces dysplasia. The K-ras^Val12-augmented apoptosis is unrelated to this dysplasia; enhanced apoptosis is also observed in cycling nondysplastic enterocytes that produce K-ras^Val12 and a TAg with a COOH-terminal truncation. The dysplastic epithelium of K-ras^Val12 × TAg^Wt mice does not develop neoplasms. Our results are consistent with this finding: (a) When expressed in initiated enterocytes with a proliferative abnormality, K-ras^Val12 facilitates progression to a dysplastic phenotype; (b) by diminishing cell survival on the villus, the oncoprotein may impede further progression; and (c) additional mutations may be needed to suppress this proapoptotic response to K-ras^Val12.     

Exploring the inhibitory activity of Withaferin-A against Pteridine reductase-1 of L. donovani

Withaferin A is an abundant withanolide present in Withania somnifera leaves and to some extent in roots. It has been known for its profound anti-cancer properties, but its role in counteracting the Leishmania donovani infection has to be explored. Pteridine reductase 1 (PTR1) is involved in pteridine salvage and an important enzyme for the parasite growth, which could be targeted for the development of an efficient antileishmanial drug. We employed molecular docking studies to identify the binding mode of withaferin A with PTR1 in silico. We further cloned, expressed, and purified PTR1 of L. donovani and performed the enzyme kinetics using the Michaelis–Menten equation and enzyme inhibition studies with withaferin A by plotting the Lineweaver–Burk graph, which followed an uncompetitive mode of inhibition. We also showed the inhibition of the enzyme in the crude lysate of treated parasites. Thus, our study contributes towards understanding the mode of action of withaferin A against L. donovani parasite.     

A re-examination of the crystal structure of A-DNA using fiber diffraction data

Classical A-DNA helices with h = 0.25 nm may represent the greatest mass per unit length attainable by polynucleotide duplexes. The X-ray diffraction pattern from polycrystalline and well-oriented fibers of calf thymus DNA in its A-form has been carefully re-examined. Indexing on the basis of a C-face-centered monoclinic unit cell of dimensions a = 2.170 nm, b = 3.990 nm, c = 2.803 nm and beta = 96.82 degrees is superior to alternatives that have been proposed. Two right-handed. Watson-Crick base-paired, helical DNA chains with 2 X 11 nucleotides per 2.803 nm pitch, each carrying C3'-endo furanose rings, pass through the unit cell. The crystallography requires the two chains in the duplex to be antiparallel and conformationally identical but the 11 nucleotides in each pitch may be distinct. However, a secondary structure with a mononucleotide asymmetric unit provides as good an X-ray agreement as one with 11 distinct nucleotides. This relative lack of variability is quite different from what is observed in fibrous B-DNAs.