Simplicity-correlated size growth of the nuclear 28S ribosomal RNA D3 expansion segment in the crustacean order Isopoda

The expansion segments within the eukaryote nuclear 23S-like ribosomal RNA molecule are now well characterized in many diverse organisms. A different base compositional bias, a higher propensity for size variability, and an increased evolutionary rate distinguish these regions from the universally c...

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Bibliographic Details
Published in:Journal of molecular evolution 1996-02, Vol.42 (2), p.211-223
Main Authors: Nunn, G.B. (American Museum of Natural History, New York, NY.), Theisen, B.F, Christensen, B, Arctander, P
Format: Article
Language:English
Subjects:
ADN
Animals
Armadillidium vulgare
ARN RIBOSOMAL
ARN RIBOSOMIAL
Base Composition
Base Sequence
CHIMIOTAXONOMIE
Crustacea - classification
Crustacea - genetics
DNA Primers - genetics
Environment
Evolution, Molecular
FILOGENIA
GENE
GENES
ISOPODA
LARGURA
LONGUEUR
Molecular Sequence Data
Nucleic Acid Conformation
PHYLOGENIE
Phylogeny
QUIMIOTAXONOMIA
RIBOSOMAS
RIBOSOME
RNA, Ribosomal, 28S - chemistry
RNA, Ribosomal, 28S - genetics
SECUENCIA NUCLEICA
SEQUENCE NUCLEIQUE
Species Specificity
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Description
Summary:The expansion segments within the eukaryote nuclear 23S-like ribosomal RNA molecule are now well characterized in many diverse organisms. A different base compositional bias, a higher propensity for size variability, and an increased evolutionary rate distinguish these regions from the universally conserved "core" regions of the molecule. In addition, some expansion segments of higher eukaryotes exhibit significant sequence simplicity which is hypothesized to occur by slippage-mediated mutational processes. We describe the discovery of extreme size variation of the D3 expansion segment in the crustacean order Isopoda. Among 11 species D3 varies in size from 180 to 518 nucleotides but maintains a homologous secondary structure. The D3 size is significantly positively correlated to relative simplicity factor (RSF), indicating that growth is most likely by insertion of simple sequences. D3 size and RSF correlate approximately with a morphology-based phylogeny, and within oniscideans RSF increases as more recent divergences occur. The D3 of Armadillidium vulgare, with an RSF of 1.87, is the highest value recorded for any known expansion segment. Regions of high sequence simplicity in nuclear ribosomal RNA were previously only known from the higher vertebrate lineage. Here we demonstrate that this phenomenon occurs in a more extreme condition within a monophyletic invertebrate lineage. The extreme size changes identified could indicate that expansion segments are an extraneous element in the functioning ribosomes
ISSN:0022-2844
1432-1432
DOI:10.1007/bf02198847