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Structure of Intergenic Spacer IGS1 of Ribosomal Operon from Schistidium Mosses

I. A. Milyutina1*, E. A. Ignatova2, M. S. Ignatov3, D. V. Goryunov1, and A. V. Troitsky1

1Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; fax: +7 (495) 939-3181; E-mail: iramilyutina@yandex.ru; bobr@belozersky.msu.ru

2Lomonosov Moscow State University, Biological Faculty, 119991 Moscow, Russia; E-mail: arctoa@list.ru

3Main Botanical Garden, Russian Academy of Sciences, 127276 Moscow, Russia; E-mail: misha_ignatov@list.ru

* To whom correspondence should be addressed.

Received July 8, 2015
The structure of the intergenic spacer 1 (IGS1) of the ribosomal operon from 12 species of Schistidium mosses was studied. In the IGS1 sequences of these species, three conserved regions and two areas of GC- and A-enriched repeats were identified. All of the studied mosses have a conserved pyrimidine-enriched motif at the 5′-end of IGS1. Species-specific nucleotide substitutions and insertions were found in the conserved areas. The repeated units contain single nucleotide substitutions that make unique the majority of repeated units. The positions of such repeats in IGS1 are species-specific, but their number can vary within the species and among operons of the same specimen. The comparison of IGS1 sequences from the Schistidium species and from representatives of ten other moss genera revealed the presence of common conserved motifs with similar localization. Presumably, these motifs are elements of termination of the pre-rRNA transcription and processing of rRNA.
KEY WORDS: rDNA, IGS, intergenic spacer, conserved motifs, mosses

DOI: 10.1134/S0006297915110103