title: Molecular phylogenetic analysis of Vibrio cholerae O1 El Tor strains isolated before, during and after the O 139 outbreak based on the inter-genomic heterogeneity of the 16S-23S rRNA intergenic spacer regions.
abstract: We have cloned, sequenced and analysed all the five classes of the intergenic (16S-23S rRNA) spacer region (ISR) associated with the eight rrn operons (rrna-rrnh) of Vibrio cholerae serogroup O1 El Tor strains isolated before, during and after the O 139 outbreak. ISR classes 'a' and 'g' were found to be invariant, ISR-B (ISRb and ISRe) exhibited very little variation, whereas ISR-C (ISRc, ISRd, and ISRf) and ISRh showed the maximum variation. Phylogenetic analysis conducted with all three ISR classes (ISR-B, ISR-C and ISRh) showed that the pre-O 139 serogroup and post-O 139 serogroup O1 El Tor strains arose out of two independent clones, which was congruent with the observation made by earlier workers suggesting that analyses of ISR-C and ISR-h, instead of all five ISR classes, could be successfully used to study phylogeny in this organism.
authors.affiliation: Molecular Biology Laboratory, Indian Institute of Chemical Biology, 4, Raja SC Mullick Road, Jadavpur, Kolkata 700 032, India.
authors.forename: Atreyi
authors.initials: A
authors.lastname: Ghatak
authors.forename: Anasuya
authors.initials: A
authors.lastname: Majumdar
authors.forename: Ranajit K
authors.initials: RK
authors.lastname: Ghosh
mesh_terms: D003001:Cloning, Molecular / Q000379:methods; D021901:DNA, Intergenic / Q000235:genetics*; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D004587:Electrophoresis, Agar Gel; D018740:Genetic Heterogeneity; D016680:Genome, Bacterial / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D041241:Vibrio cholerae O1 / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D041242:Vibrio cholerae O139 / Q000145:classification / Q000235:genetics
chemical_list: D021901:DNA, Intergenic; D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S