title: Intraspecific genetic variation in Paramecium revealed by mitochondrial cytochrome C oxidase I sequences.
abstract: Studies of intraspecific genetic diversity of ciliates, such as population genetics and biogeography, are particularly hampered by the lack of suitable DNA markers. For example, sequences of the non-coding ribosomal internal transcribed spacer (ITS) regions are often too conserved for intraspecific analyses. We have therefore identified primers for the mitochondrial cytochrome c oxidase I (COI) gene and applied them for intraspecific investigations in Paramecium caudatum and Paramecium multimicronucleatum. Furthermore, we obtained sequences of the ITS regions from the same strains and carried out comparative sequence analyses of both data sets. The mitochondrial sequences revealed substantially higher variation in both Paramecium species, with intraspecific divergences up to 7% in P. caudatum and 9.5% in P. multimicronucleatum. Moreover, an initial survey of the population structure discovered different mitochondrial haplotypes of P. caudatum in one pond, thereby demonstrating the potential of this genetic marker for population genetic analyses. Our primers successfully amplified the COI gene of other Paramecium. This is the first report of intraspecific variation in free-living protozoans based on mitochondrial sequence data. Our results show that the high variation in mitochondrial DNA makes it a suitable marker for intraspecific and population genetic studies.
authors.affiliation: Molecular Evolution and Animal Systematics, Institute of Biology II, University of Leipzig, 04103 Leipzig, Germany. dbarth@rz.uni-leipzig.de
authors.forename: Dana
authors.initials: D
authors.lastname: Barth
authors.forename: Sascha
authors.initials: S
authors.lastname: Krenek
authors.forename: Sergei I
authors.initials: SI
authors.lastname: Fokin
authors.forename: Thomas U
authors.initials: TU
authors.lastname: Berendonk
mesh_terms: D000818:Animals; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000032:analysis / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000032:analysis; D003576:Electron Transport Complex IV / Q000235:genetics*; D014644:Genetic Variation; D008928:Mitochondria / Q000201:enzymology*; D008969:Molecular Sequence Data; D010247:Paramecium / Q000145:classification* / Q000201:enzymology / Q000235:genetics*; D048488:Paramecium caudatum / Q000145:classification / Q000201:enzymology / Q000235:genetics; D012340:RNA, Ribosomal, 5.8S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers; D004272:DNA, Mitochondrial; D021903:DNA, Ribosomal Spacer; D012340:RNA, Ribosomal, 5.8S; D003576:Electron Transport Complex IV