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Assessment of DNA Contamination in RNA Samples Based on Ribosomal DNA
Published on: January 22, 2018
Analysis of ribosomal protein gene structures: implications for intron evolution
Maki Yoshihama1, Akihiro Nakao, Hung D Nguyen
1Frontier Science Research Center, University of Miyazaki, Kiyotake, Miyazaki, Japan.
Plos Genetics
|March 7, 2006
Summary
Investigating intron evolution, this study found that shared intron positions in cytoplasmic and mitochondrial ribosomal protein genes arose from parallel gains, not conserved ancestry. This suggests spliceosomal introns were acquired later in eukaryotic evolution.
Area of Science:
- Genomics
- Evolutionary Biology
- Molecular Biology
Background:
- The evolution of spliceosomal introns in eukaryotic genomes is a long-standing question.
- Cytoplasmic ribosomal proteins (CRPs) and mitochondrial ribosomal proteins (MRPs) have distinct evolutionary origins (archaeal and bacterial, respectively).
Purpose of the Study:
- To investigate intron evolution by comparing gene structures of CRPs and MRPs.
- To determine if shared intron positions represent conserved ancestry or independent gains.
Main Methods:
- Comparative analysis of 25 homologous CRP and MRP gene pairs.
- Identification and analysis of 527 intron positions.
- Examination of proto-splice sites at shared intron locations.
Main Results:
- None of the 12 shared intron positions between CRP and MRP genes were conserved; all resulted from parallel intron gains.
- High frequency of proto-splice sites at shared positions supports the intron insertion hypothesis.
- Mitochondrial ribosomal protein genes were likely intronless at the time of endosymbiosis.
Conclusions:
- Results support the hypothesis that spliceosomal introns were gained later in eukaryotic evolution, rather than being ancient.
- Parallel intron gains are a significant factor in intron distribution, accounting for an estimated 2.3% of total intron positions.
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