Structural organization of cholera toxin gene and its expression in an environmental non-pathogenic strain of Vibrio cholerae

Non-pathogenic, environmental strain ofVibrio cholerae, ELTOR Ogawa EW6 carries a copy of the cholera toxin gene in its chromosome. Restriction enzyme digestion followed by Southern blot analysis revealed that the structure of the cholera toxin gene in this organism is different from that found in the virulent strains. The xbaI site which has been found to be conserved in the cholera toxin of the virulent strains examined so far, is absent here. Results of the RNA dot blot analysis indicated that the cholera toxin gene in EW6 is transcribed much less efficiently compared to the cholera toxin gene present in the virulent strainVibrio cholerae classical Inaba 569B

Repression of the alkaline phosphatase of Vibrio cholerae

The synthesis of alkaline phosphatase by two strains of Vibrio cholerae belonging to the Inaba and Ogawa serotypes has been examined in relation to the phosphate concentration of the culture medium. The synthesis of the enzyme in both strains was repressed in cells grown in the presence of a high concentration of inorganic phosphate. Lowering the phosphate content of the growth medium led to a derepression of enzyme activity. The presence of glucose in low phosphate medium stimulated the degree of derepression. The synthesis of the enzyme by strain Inaba 569B was more sensitive to inorganic phosphate than that of strain Ogawa 154. The enzyme was presumably located in the periplasmic space since it was released when the organisms were converted to spheroplasts

Fast response and low temperature sensing of acetone and ethanol using Al-doped ZnO microrods

We report low temperature acetone and ethanol sensing properties of Al-doped ZnO microrods synthesized using hydrothermal technique. We observe the acetone detection at room temperature as well as ethanol and acetone detection at low temperature of 150 °C using Al-doped ZnO microrods. 3 wt% Al-doped ZnO microrods sensor exhibits the highest response of 231 toward 8100 parts per million (ppm) of ethanol at 150 °C. The response & recovery time are found to be ultrafast of 60 ms & 870 ms for ethanol and 110 ms & 330 ms for acetone of the Al-doped ZnO microrods at an operating temperature of 150 °C, respectively. In addition, sensing mechanism has explained to illuminate the improved sensing performances of Al-doped ZnO microrods. Thus it is revealed that Al-doped ZnO microrods are promising as an ultrafast gas sensor

Enterotoxin production, DNA repair and alkaline phosphatase of Vibrio cholerae before and after animal passage

Summary: Three strains of Vibrio cholerae differing in biotype, serotype and/or toxinogenicity were studied. The capability for dark repair of DNA and stability of alkaline phosphatase decreased concomitantly with toxinogenicity on laboratory passage of highly enterotoxinogenic strain 569B. These properties could be restored by passaging strain 569B once through a guinea-pig

Deregulation of LIMD1-VHL-HIF-1α-VEGF pathway is associated with different stages of cervical cancer.

To understand the mechanism of cellular stress in basal-parabasal layers of normal cervical epithelium and during different stages of cervical carcinoma, we analyzed the alterations (expression/methylation/copy number variation/mutation) of HIF-1α and its associated genes LIMD1, VHL and VEGF in disease-free normal cervix (n = 9), adjacent normal cervix of tumors (n = 70), cervical intraepithelial neoplasia (CIN; n = 32), cancer of uterine cervix (CACX; n = 174) samples and two CACX cell lines. In basal-parabasal layers of normal cervical epithelium, LIMD1 showed high protein expression, while low protein expression of VHL was concordant with high expression of HIF-1α and VEGF irrespective of HPV-16 (human papillomavirus 16) infection. This was in concordance with the low promoter methylation of LIMD1 and high in VHL in the basal-parabasal layers of normal cervix. LIMD1 expression was significantly reduced while VHL expression was unchanged during different stages of cervical carcinoma. This was in concordance with their frequent methylation during different stages of this tumor. In different stages of cervical carcinoma, the expression pattern of HIF-1α and VEGF was high as seen in basal-parabasal layers and inversely correlated with the expression of LIMD1 and VHL. This was validated by demethylation experiments using 5-aza-2'-deoxycytidine in CACX cell lines. Additional deletion of LIMD1 and VHL in CIN/CACX provided an additional growth advantage during cervical carcinogenesis through reduced expression of genes and associated with poor prognosis of patients. Our data showed that overexpression of HIF-1α and its target gene VEGF in the basal-parabasal layers of normal cervix was due to frequent inactivation of VHL by its promoter methylation. This profile was maintained during different stages of cervical carcinoma with additional methylation/deletion of VHL and LIMD1.This work was supported by CSIR (Council of Scientific and Industrial Research, Government of India)-JRF/NET grant [File No.09/030(0059)/2010-EMR-I] to Mr. C.Chakraborty, grant [Sr. No. 2121130723] from UGC (University Grants Commission, Government of India) to Mr. Sudip Samadder, grant [SR/SO/HS-116/2007] from DST (Department of Science and Technology, Government of India) to Dr. C. K. Panda and grant [ No. 60(0111)/14/EMR-II of dt.03/11/2014] from CSIR (Council of Scientific and Industrial Research, Government of India) to Dr. C. K. Pand

Characterization of the Phage-Specific Transfer RNA Molecules Coded by Cholera Phage $149

Aminoacylation of tRNA isolated from choleraphage +149-infected cells with individual 3H-lebeled L-amino acids followed by hybridization with phage DNA revealed that the phage encodes tRNAs specific for arginine, proline, glycine, isoleucine, serine, valine, tyrosine, histidine, lysine, leucine, tryptophan, and aspartic acid. Aminoacylation of phagecoded tRNAs isolated from phage DNA-RNA hybrids also confirmed this observation except for tryptophan

Integration of the DNA of a novel filamentous bacteriophage VSK from Vibrio cholerae 0139 into the host chromosomal DNA

An unusual lilamentous bacteriophage, VSK, containing single-stranded, circular DNA as its genome was isolated from Vibuio cholerae 0139 strains PO7 and B04. Unlike other single-stranded DNA phages, VSK can integrate its genome into the chromosome of the host and enter into a lysogenic state. The double-stranded replicative form (RF) of the single-stranded phage DNA was isolated. A restriction map of the VSK RF DNA was constructed using HaeII, AvnII, ClaI and XbaI. By Southern blot analysis of the chromosomal DNA of the lysogen using labeled phage DNA as probe, the attachment site (attP) on the viral genome was also identified

Localization of transfer RNA genes on the physical map of Vibrio eltor phage e<SUB>4</SUB> genome

Transfer RNAs were isolated from uninfected and phage e<SUB>4</SUB>-infected Vibrio eltor Mak 757 cells. These tRNAs were then aminoacylated with <SUP>3</SUP>H-labeled amino acids and hybridized to DNA isolated from phage e<SUB>4</SUB>. Significant hybridization was observed only with tRNA isolated from phage e<SUB>4</SUB>-infected cells. Restriction enzyme digestion of phage e<SUB>4</SUB> DNA followed by Southern blot using [<SUP>32</SUP>P]tRNA from infected cells revealed that tRNA genes were contained in a 3.4-kb Kpnl fragment. The tRNA genes were located on the physical map of the phage genome 19 kb from one of the termini

Finish-Turning of Hardened Powder Metallurgy Steel Using Cryogenic Cooling”, www.mpif.org, 2003. VITA The author was born in Atul, India on September 3

ABSTRACT: A large fraction of automotive components made of hardened powder-metallurgy steels are subject to finish-turning before final assembly. Because of a characteristically poor machinability and high surface finish requirements, the conventional P/M turning operations usually require the use of flood-cooled polycrystalline CBN tools which leads to high machining costs, P/M component contamination, and negative impact on work environment and safety. This paper examines a new, cost-effective alternative for the P/M finish-turning which involves cryogenic fluid-cooled ceramic tools and eliminates the environmental and safety issues. Presented analysis includes comparative tool-life, cutting force, and surface integrity study for the structural steel sintered to the densities of 6.7 and 7.2 Mg/m 3 and heattreated. Experimental results show that cryogen-cooled ceramic tools live longer than CBN and offer additional work surface improvements. Technical discussion entails economic aspects of finish-turning and areas for future research