This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Osorio, C. R. Articles by Toranzo, A. E. Search for Related Content PubMed PubMed Citation Articles by Osorio, C. R. Articles by Toranzo, A. E. Agricola Articles by Osorio, C. R. Articles by Toranzo, A. E.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, February 2005, p. 636-645, Vol. 71, No. 2
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.2.636-645.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Variation in 16S-23S rRNA Intergenic Spacer Regions in Photobacterium damselae: a Mosaic-Like Structure

Carlos R. Osorio,^1,2* Matthew D. Collins,² Jesús L. Romalde,¹ and Alicia E. Toranzo¹

Departamento de Microbioloxía e Parasitoloxía e Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain,¹ School of Food Biosciences, University of Reading, Reading, United Kingdom²

Received 27 May 2004/ Accepted 16 September 2004

Phenotypically, Photobacterium damselae subsp. piscicida and P. damselae subsp. damselae are easily distinguished. However, their 16S rRNA gene sequences are identical, and attempts to discriminate these two subspecies by molecular tools are hampered by their high level of DNA-DNA similarity. The 16S-23S rRNA internal transcribed spacers (ITS) were sequenced in two strains of Photobacterium damselae subsp. piscicida and two strains of P. damselae subsp. damselae to determine the level of molecular diversity in this DNA region. A total of 17 different ITS variants, ranging from 803 to 296 bp were found, some of which were subspecies or strain specific. The largest ITS contained four tRNA genes (tDNAs) coding for tRNA^Glu(UUC), tRNA^Lys(UUU), tRNA^Val(UAC), and tRNA^Ala(GGC). Five amplicons contained tRNA^Glu(UUC) combined with two additional tRNA genes, including tRNA^Lys(UUU), tRNA^Val(UAC), or tRNA^Ala(UGC). Five amplicons contained tRNA^Ile(GAU) and tRNA^Ala(UGC). Two amplicons contained tRNA^Glu(UUC) and tRNA^Ala(UGC). Two different isoacceptor tRNA^Ala genes (GGC and UGC anticodons) were found. The five smallest amplicons contained no tRNA genes. The tRNA-gene combinations tRNA^Glu(UUC)-tRNA^Val(UAC)-tRNA^Ala(UGC) and tRNA^Glu(UUC)-tRNA^Ala(UGC) have not been previously reported in bacterial ITS regions. The number of copies of the ribosomal operon (rrn) in the P. damselae chromosome ranged from at least 9 to 12. For ITS variants coexisting in two strains of different subspecies or in strains of the same subspecies, nucleotide substitution percentages ranged from 0 to 2%. The main source of variation between ITS variants was due to different combinations of DNA sequence blocks, constituting a mosaic-like structure.

---

* Corresponding author. Mailing address: Departamento de Microbioloxía e Parasitoloxía e Instituto de Acuicultura, Universidade de Santiago de Compostela, Campus Sur, 15782 Santiago de Compostela, Galicia, Spain. Phone: 34-981563100, ext. 16062. Fax: 34-981547165. E-mail: crosorio{at}usc.es.

---

Applied and Environmental Microbiology, February 2005, p. 636-645, Vol. 71, No. 2
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.2.636-645.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Sadeghifard, N., Gurtler, V., Beer, M., Seviour, R. J. (2006). The Mosaic Nature of Intergenic 16S-23S rRNA Spacer Regions Suggests rRNA Operon Copy Number Variation in Clostridium difficile Strains. Appl. Environ. Microbiol. 72: 7311-7323 [Abstract] [Full Text]