Sequence variations in the large-subunit ribosomal RNA gene of Ammonia (Foraminifera, Protozoa) and their evolutionary implications

J Mol Evol. 1996 Aug;43(2):145-51. doi: 10.1007/BF02337359.

Abstract

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 accepted 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Biological Evolution*
  • DNA, Protozoan / chemistry
  • DNA, Protozoan / genetics*
  • DNA, Ribosomal / chemistry
  • DNA, Ribosomal / genetics*
  • Eukaryota / genetics*
  • Genes, Protozoan*
  • Genetic Variation
  • Molecular Sequence Data
  • Phylogeny
  • RNA, Protozoan / chemistry
  • RNA, Protozoan / genetics
  • RNA, Ribosomal / genetics
  • Sequence Homology, Nucleic Acid

Substances

  • DNA, Protozoan
  • DNA, Ribosomal
  • RNA, Protozoan
  • RNA, Ribosomal

Associated data

  • GENBANK/X93094
  • GENBANK/X93095
  • GENBANK/X93096
  • GENBANK/X93097
  • GENBANK/X93098
  • GENBANK/X93099
  • GENBANK/X93100
  • GENBANK/X93101
  • GENBANK/X93102
  • GENBANK/X93103
  • GENBANK/X93104
  • GENBANK/X93105
  • GENBANK/X93106
  • GENBANK/X93107
  • GENBANK/X93108
  • GENBANK/X93109
  • GENBANK/X93110
  • GENBANK/X93111
  • GENBANK/X93112
  • GENBANK/X93113
  • GENBANK/X93114
  • GENBANK/X93115
  • GENBANK/X93116
  • GENBANK/X93117
  • GENBANK/X93118
  • GENBANK/X93119
  • GENBANK/X93120
  • GENBANK/X93121
  • GENBANK/X93122
  • GENBANK/X93123