Protistology 4 (4) 311-317 (2006/7)
Genomic dactyloscopy of Chlorella sp., symbionts of Paramecium bursaria
Irina N. Gaponova,1 Eugeny E. Andronov,2 Aleksandra V. Migunova,2
Konstantin P. Vorobyev,1 Elena P. Chizhevskaja 2 and
Konstantin V. Kvitko 2
1
Department of Genetics, All Russia Research Institute for Agricultural Microbiology, Pushkin-8,
St.-Petersburg, Russia
Summary
The exon nucleotide sequences of the last part of the 18S rRNA gene in the northern and the southern ecotypes of
zoochlorella strains (in the interval from 1315 to 1766 sites in accordance with sequence X56105 of Chlorella
kessleri strain SAG-211-11g) were compared with the exon sequence of this gene in different Chlorella
strains. These two ecotypes were shown to be the closest neighbours of Ch. vulgaris, Ch. sorokinianŠ°, Ch.
lobophora. All strains of northern and southern ecotypes were different from free-living Chlorella
vulgaris in having introns in the first part of the 18S rRNA gene. The southern zoochlorellae had at least one
more intron in middle part of the gene. We assume that in the course of evolution the ancestors of the northern
zoochlorellae (Ch. vulgaris) got an intron (of the size about 330 nucleotides in the interval of 106-1315 b.p.
of the 18S RNA gene), and southern zoochlorellae have got several introns, one similar to that of the northern
ecotype in size and position and the others in the part of the gene, 1276-1766 (the size 647 nucleotides) and 495 b.p
(according to the data of Hoshira et al., 2004, 2005) at the end of the gene.
Key words: Chlorella, PCR, 18S rRNA, phylogeny, introns, ecotypes of zoochlorella
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