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Polymorphic insertions and deletions in parabasalian enolase genes
1Canadian Institute for Advanced Research, Department of Botany, University of British Columbia, 3529-6270 University Blvd., Vancouver, British Columbia V6T 1Z4, Canada. pkeeling@interchange.ubc.ca
Journal of Molecular Evolution
|June 1, 2004
Summary
Polymorphic deletions in parabasalian enolase genes challenge their use as evidence for early eukaryotic origins. This gene sequence data indicates these deletions are not a reliable primitive marker.
Area of Science:
- Evolutionary biology
- Molecular evolution
- Genomics
Background:
- Insertions and deletions (indels) in gene sequences are valuable for phylogenetic inference.
- Conserved indels in enolase genes of parabasalian protists were previously interpreted as evidence for their early origin in eukaryotic evolution.
Purpose of the Study:
- To investigate the conservation of specific deletions in enolase genes within parabasalian protists.
- To re-evaluate the phylogenetic utility of these deletions as a marker for early eukaryotic divergence.
Main Methods:
- Semi-environmental 3'-RACE was employed to sample enolase genes from parabasalia.
- Phylogenetic analysis was conducted on the obtained enolase sequences to assess gene relationships and indel distribution.
Main Results:
- Parabasalian enolase genes exhibited polymorphism for the deletions in question.
- Phylogenetic analysis revealed that deletion-possessing genes clustered within deletion-lacking genes, not forming distinct clades.
- Phylogenetic incongruence was observed in the carboxy-terminal region near the deletions, without clear evidence of recombination.
Conclusions:
- The observed polymorphism of these deletions undermines their reliability as strong evidence for the early origin of parabasalia.
- The complex distribution of these indels makes it difficult to ascertain the ancestral state of parabasalian enolases relative to other eukaryotes.
- This study highlights the critical need for robust corroborating evidence when utilizing indel data in phylogenetic analyses and points to variable conservation of deletions across eukaryotic groups.