title: Characterization of the 23S and 5S rRNA genes and 23S-5S intergenic spacer region (ITS-2) of Photobacterium damselae.
abstract: The 23S ribosomal RNA (rRNA) gene has been sequenced in strains of the fish pathogens Photobacterium damselae subsp. damselae (ATCC 33539) and subsp. piscicida (ATCC 29690), showing that 3 nucleotide positions are clearly different between subspecies. In addition, the 5S rRNA gene plus the intergenic spacer region between the 23S and 5S rRNA genes (ITS-2) were amplified, cloned and sequenced for the 2 reference strains as well as the field isolates RG91 (subsp. damselae) and DI21 (subsp. piscicida). A 100% similarity was found for the consensus 5S rRNA gene sequence in the 2 subspecies, although some microheterogeneity was detected as inter-cistronic variability within the same chromosome. Sequence analysis of the spacer region between the 23S and 5S rRNA genes revealed 2 conserved and 3 variable nucleotide sequence blocks, and 4 different modular organizations were found. The ITS-2 spacer region exhibited both inter-subspecies and intercistronic polymorphism, with a mosaic-like structure. The EMBL accession numbers for the 23S, 5S and ITS-2 sequences are: P. damselae subsp. piscicida 5S gene (AJ274379), P. damselae subsp. damselae 23S gene (Y18520), subsp. piscicida 23S gene (Y17901), P. damselae subsp. piscicida ITS-2 (AJ250695, AJ250696), P. damselae subsp. damselae ITS-2 (AJ250697, AJ250698).
authors.affiliation: Departamento de Microbioloxía e Parasitoloxía e Instituto de Acuicultura, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain. crosorio@usc.es
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Osorio
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Collins
authors.forename: Jesús L
authors.initials: JL
authors.lastname: Romalde
authors.forename: Alicia E
authors.initials: AE
authors.lastname: Toranzo
mesh_terms: D001483:Base Sequence; D016000:Cluster Analysis; D017931:DNA Primers; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010776:Photobacterium / Q000235:genetics*; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D021903:DNA, Ribosomal Spacer