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The Tarsius gamma-globin gene: pseudogene or active gene?
C M Meireles1, J Czelusniak, M Goodman
1Department of Anatomy and Cell Biology, Wayne State University-School of Medicine, Detroit, Michigan 48201, USA.
Molecular Phylogenetics and Evolution
|December 22, 1999
Summary
Tarsier gamma-globin genes are active despite promoter mutations. Sequencing revealed synonymous substitutions in coding regions, indicating expression, not pseudogene status.
Area of Science:
- Genomics
- Molecular Evolution
- Primate Genetics
Background:
- The gamma-globin gene locus in Tarsius syrichta presented mutations suggesting it might be a nonexpressed pseudogene.
- Specific mutations included a lack of the distal CCAAT box and a point mutation in the proximal CCAAT box.
Purpose of the Study:
- To investigate the expression status of the gamma-globin gene locus in Tarsius bancanus.
- To compare the gamma-globin gene locus sequences between Tarsius bancanus and Tarsius syrichta.
Main Methods:
- Sequencing of the approximately 5-kb gamma-globin gene locus from Tarsius bancanus.
- Comparative sequence analysis with the published gamma-globin gene sequence from Tarsius syrichta.
Main Results:
- Both tarsier species share a point mutation in the proximal CCAAT element and lack the distal CCAAT element.
- Analysis of coding regions showed only synonymous substitutions, indicating a low divergence rate.
- Noncoding regions exhibited a significantly higher divergence rate compared to coding regions.
Conclusions:
- The gamma-globin gene locus in tarsiers is likely expressed, contrary to previous pseudogene suggestions.
- The observed pattern of synonymous substitutions suggests active gene function despite promoter mutations.
- This finding challenges expectations for silent genes under stabilizing selection.