Development of a Diagnostic Oligonucleotide DNA Probe for the Rapid Detection of Vibrio Cholerae O139

Vibrio cholerae O139 Bengal emerged as the second etiologic agent of cholera in the Indian subcontinent in late 1992, it then spread to several neighboring countries and also some developed countries. V. cholerae O139 Bengal is closely related to V. cholerae O1 E1 Tor strains associated with the seventh pandemic, and it causes a disease which is virtually indistinguishable from cholera caused by V. cholerae O1. V. cholerae O139 Bengal and V. cholerae O1 E1 Tor share several phenotypic and genotypic properties. However, all the genes of the rfb complex which encode the O antigen in V. cholerae 01 El Tor have been found deleted in V. cholerae O139. In their place, there is a new chromosomal region detected. Based on a published sequence, six set of V. cholerae O139 primers have been designed. Primer combination Sl -AS2 (5'-AGATGCCGAAGACTATAA-3' and 5'-GAGGAATAACAACTGAGA-3') was found to be specific for detection of V. cholerae O139 in a polymerase chain reaction (peR) assay, as they produced an amplicon of 520 bp from all tested pure cultures of V. cholerae O139 strains but not from 39 pure cultures of other bacteria. The newly designed primer combination has been used to develop a, diagnotic kit for the identification of V. cholerae O139 in our laboratory

Inhibition of telomerase activity and cell growth by natural plant products in human brain cancer cells

Ph.DDOCTOR OF PHILOSOPH

Thymoquinone Induces Telomere Shortening, DNA Damage and Apoptosis in Human Glioblastoma Cells

Background: A major concern of cancer chemotherapy is the side effects caused by the non-specific targeting of both normal and cancerous cells by therapeutic drugs. Much emphasis has been placed on discovering new compounds that target tumour cells more efficiently and selectively with minimal toxic effects on normal cells. Methodology/Principal Findings: The cytotoxic effect of thymoquinone, a component derived from the plant Nigella sativa, was tested on human glioblastoma and normal cells. Our findings demonstrated that glioblastoma cells were more sensitive to thymoquinone-induced antiproliferative effects. Thymoquinone induced DNA damage, cell cycle arrest and apoptosis in the glioblastoma cells. It was also observed that thymoquinone facilitated telomere attrition by inhibiting the activity of telomerase. In addition to these, we investigated the role of DNA-PKcs on thymoquinone mediated changes in telomere length. Telomeres in glioblastoma cells with DNA-PKcs were more sensitive to thymoquinone mediated effects as compared to those cells deficient in DNA-PKcs. Conclusions/Significance: Our results indicate that thymoquinone induces DNA damage, telomere attrition by inhibiting telomerase and cell death in glioblastoma cells. Telomere shortening was found to be dependent on the status of DNA-PKcs. Collectively, these data suggest that thymoquinone could be useful as a potential chemotherapeutic agent in th

Telomere Biology—Insights into an Intriguing Phenomenon

Bacteria and viruses possess circular DNA, whereas eukaryotes with typically very large DNA molecules have had to evolve into linear chromosomes to circumvent the problem of supercoiling circular DNA of that size. Consequently, such organisms possess telomeres to cap chromosome ends. Telomeres are essentially tandem repeats of any DNA sequence that are present at the ends of chromosomes. Their biology has been an enigmatic one, involving various molecules interacting dynamically in an evolutionarily well-trimmed fashion. Telomeres range from canonical hexameric repeats in most eukaryotes to unimaginably random retrotransposons, which attach to chromosome ends and reverse-transcribe to DNA in some plants and insects. Telomeres invariably associate with specialised protein complexes that envelop it, also regulating access of the ends to legitimate enzymes involved in telomere metabolism. They also transcribe into repetitive RNA which also seems to be playing significant roles in telomere maintenance. Telomeres thus form the intersection of DNA, protein, and RNA molecules acting in concert to maintain chromosome integrity. Telomere biology is emerging to appear ever more complex than previously envisaged, with the continual discovery of more molecules and interplays at the telomeres. This review also includes a section dedicated to the history of telomere biology, and intends to target the scientific audience new to the field by rendering an understanding of the phenomenon of chromosome end protection at large, with more emphasis on the biology of human telomeres. The review provides an update on the field and mentions the questions that need to be addressed

Telomere Biology-Insights into an Intriguing Phenomenon

10.3390/cells6020015CELLS6

Lack of poly(ADP-ribose) polymerase-1 gene product enhances cellular sensitivity to arsenite

10.1158/0008-5472.CAN-05-2336Cancer Research652310977-1098

Eme1 is involved in DNA damage processing and maintenance of genomic stability in mammalian cells

Yeast and human Eme1 protein, in complex with Mus81, constitute an endonuclease that cleaves branched DNA structures, especially those arising during stalled DNA replication. We identified mouse Eme1, and show that it interacts with Mus81 to form a complex that preferentially cleaves 3′-flap structures and replication forks rather than Holliday junctions in vitro. We demonstrate that Eme1(–/–) embryonic stem (ES) cells are hypersensitive to the DNA cross-linking agents mitomycin C and cisplatin, but only mildly sensitive to ionizing radiation, UV radiation and hydroxyurea treatment. Mammalian Eme1 is not required for the resolution of DNA intermediates that arise during homologous recombination processes such as gene targeting, gene conversion and sister chromatid exchange (SCE). Unlike Blm-deficient ES cells, increased SCE was seen only following induced DNA damage in Eme1-deficient cells. Most importantly, Eme1 deficiency led to spontaneous genomic instability. These results reveal that mammalian Eme1 plays a key role in DNA repair and the maintenance of genome integrity