RESUMEN
A PCR assay for the amplification of small subunit ribosomal DNA (SSU rDNA) of Euryarchaea was developed and used to detect archaeal rDNA in 37 (77%) out of 48 pooled subgingival plaque samples from 48 patients suffering from periodontal disease. One major group of cloned periodontal sequences was identical to Methanobrevibacter oralis and a second minor group to Methanobrevibacter smithii. These two groups and a third novel group were found to be more than 98% similar to each other over an 0.65-kb segment of the 16S rRNA gene sequenced. M. oralis was found to be the predominant archaeon in the subgingival dental plaque. Phylogenetic analysis of partial SSU rDNA sequences revealed evidence for a distinct cluster for human and animal Methanobrevibacter sp. within the Methanobacteriaceae family.
Asunto(s)
Archaea/aislamiento & purificación , ADN de Archaea/aislamiento & purificación , Placa Dental/microbiología , Encía/microbiología , Adolescente , Adulto , Anciano , Archaea/genética , ADN de Archaea/genética , ADN Ribosómico/genética , Escherichia coli , Euryarchaeota/genética , Femenino , Humanos , Masculino , Persona de Mediana Edad , Filogenia , Reacción en Cadena de la Polimerasa , Análisis de Secuencia de ADNRESUMEN
In 1992 we started assembling an ordered library of cosmid clones from chromosome XIV of the yeast Saccharomyces cerevisiae. At that time, only 49 genes were known to be located on this chromosome and we estimated that 80% to 90% of its genes were yet to be discovered. In 1993, a team of 20 European laboratories began the systematic sequence analysis of chromosome XIV. The completed and intensively checked final sequence of 784,328 base pairs was released in April, 1996. Substantial parts had been published before or had previously been made available on request. The sequence contained 419 known or presumptive protein-coding genes, including two pseudogenes and three retrotransposons, 14 tRNA genes, and three small nuclear RNA genes. For 116 (30%) protein-coding sequences, one or more structural homologues were identified elsewhere in the yeast genome. Half of them belong to duplicated groups of 6-14 loosely linked genes, in most cases with conserved gene order and orientation (relaxed interchromosomal synteny). We have considered the possible evolutionary origins of this unexpected feature of yeast genome organization.