Scientific article
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Sequence variations in the large-subunit ribosomal RNA gene of Ammonia (foraminifera, protozoa) and their evolutionary implications

Published inJournal of molecular evolution, vol. 43, no. 2, p. 145-151
Publication date1996-08

An unusually high divergence was observed in the ribosomal RNA genes of a free-living population of foraminifera belonging to the genus Ammonia. The sequences of a large-subunit (LSU) rDNA expansion segment D1 and flanking regions were obtained from 20 specimens named Ammonia sp. 1 and Ammonia sp. 2. The sequence divergence between the two species averages 14%. Within each species it ranges from 0.2% to 7.1% in Ammonia sp. 1 and from 0.7% to 2.3% in Ammonia sp. 2. We did not find two specimens having identical sequences. Moreover, in opposition to the generally acaepted view, rDNA sequence variations were also found within a single individual. The variations among several rDNA copies in a single specimen of Ammonia may reach up to 4.9%. Most of the observed variations result from multiplication of CA or TA serial repeats occurring in two particularly variable regions. For single base changes, C-T transitions are most frequently observed. We discuss the evolution of expansion segments and their use for phylogenetic studies.

  • Foraminifera
  • Sequence dissimilarity
  • LSU rRNA gene
  • Phylogeny
Citation (ISO format)
HOLZMANN, Maria, PILLER, Werner, PAWLOWSKI, Jan Wojciech. Sequence variations in the large-subunit ribosomal RNA gene of <i>Ammonia</i> (foraminifera, protozoa) and their evolutionary implications. In: Journal of molecular evolution, 1996, vol. 43, n° 2, p. 145–151. doi: 10.1007/BF02337359
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Article (Published version)
ISSN of the journal0022-2844

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