Intraspecific Variation of Diagnostic rDNA Genes in Paramecium dodecaurelia, P. tredecaurelia and P. quadecaurelia (Ciliophora: Oligohymenophorea)

• Published in: Acta Protozoologica Vol. 45; no. 3; pp. 255 - 263
• Main Authors: Tarcz, S, Przybos, E, Prajer, M, Greczek-Stachura, M
• Format: Journal Article
• Language: English
• Published: Jagiellonian University Press 2006
• Subjects: Aurelia; Ciliophora; Marine; Paramecium; P. dodecaurelia; P. quadecaurelia; ITS1 region; ribosomal DNA; LSU rRNA gene sequences; intraspecific polymorphism; SSU rRNA gene sequences; P. tredecaurelia; sequence analyses; Paramecium aurelia species complex
• ISSN: 0065-1583

Fragments of the 3' end of SSU rRNA - ITS1 (210bp) and the 5' end of LSU rRNA (350bp) were analysed in a study of intraspecific polymorphism in species of the Pararnecium aurelia complex. These species have shown various levels of intraspecific polymorphism in previous RAPD, RFLP and ARDRA analyses, i.e. Paramecium dodecaurelia (high intraspecific polymorphism), P. quadecaurelia and P. tredecaurelia (no intraspecific polymorphism). Studies were performed on six strains of P. dodecaurelia and in two strains each (only available) of P. tredecaurelia and P. quadecaurelia, originating from geographically remote collecting sites. Alignment of both rDNA gene fragments containing 3'SSU rRNA-ITS1 and 5' LSU rRNA revealed a distinct polymorphism within P. dodecaurelia, i.e six polymorphic sites were found in a fragment of rDNA at the 3' end of SSU rRNA-ITS1, only one site differentiating strains of P. tredecaurelia, and no changes in P. quadecaurelia. Similarly, at 5' LSU several polymorphisms characteristic for the particular strains of P. dodecaurelia were observed, three polymorphic sites when two strains of P. tredecaurelia were compared, and one polymorphic site in the case of two strains of P. quadecaurelia. Neighbor-joining and maximum parsimony phylogenies showed that P. dodecaurelia strains are scattered, particular strains differ as much as different species of the P. aurelia complex. Our present study confirmed previous results (RAPD, RFLP, and ARDRA analyses) which revealed such exceptional intraspecific differentiation in P. dodecaurelia. This is the first analysis of the 5'end fragment of LSU rRNA at the intraspecific level in the P. aurelia complex, showing that the fragment seems very useful at this level.