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Secretory ribonucleases in the primitive ruminant chevrotain (Tragulus javanicus)
H J Breukelman1, P A Jekel, J Y Dubois
1Department of Biochemistry, University of Groningen, the Netherlands.
European Journal of Biochemistry
|July 17, 2001
Summary
Gene duplication events in ruminant evolution led to distinct pancreatic, seminal, and brain ribonuclease genes. These genes evolved rapidly, especially in ruminants, with chevrotain showing early divergence.
Area of Science:
- Evolutionary biology
- Molecular evolution
- Genomics
Background:
- Secretory ribonucleases (RNases) are crucial enzymes with diverse functions.
- Gene duplication is a significant driver of evolutionary innovation.
- Previous studies suggested gene duplication events in RNase 1 evolution within ruminants.
Purpose of the Study:
- To investigate the evolutionary history and diversification of secretory RNase 1 genes in ruminants.
- To analyze the phylogenetic relationships of RNase 1 genes across various artiodactyl species.
- To understand the impact of gene duplication on the evolutionary rate of RNase 1 genes.
Main Methods:
- Phylogenetic analyses of secretory RNase 1 sequences from multiple ruminant, artiodactyl, and whale species.
- Identification and characterization of paralogous RNase genes (pancreatic, seminal, brain).
- Protein isolation and N-terminal sequence analysis to confirm enzyme identity.
Main Results:
- Two gene duplication events in an ancestral ruminant gave rise to pancreatic, seminal, and brain RNase genes.
- Chevrotain (Tragulus javanicus) exhibits a higher number of RNase paralogs, with its sequences diverging earliest.
- The pancreatic RNase is highly acidic; seminal-type RNase is largely a pseudogene, except in cattle; brain-type RNase is expressed in brain tissue.
- A hybrid pancreatic-brain RNase gene was identified.
- RNase 1 genes in taxa with duplications (ruminants, camels) evolved twice as fast as in taxa with single genes.
Conclusions:
- Gene duplication played a critical role in the diversification of RNase 1 genes within ruminants.
- The evolutionary rate of RNase 1 genes accelerated significantly following duplication events.
- Phylogenetic analysis reveals distinct evolutionary trajectories for pancreatic, seminal, and brain RNase lineages.