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Telomeres in evolution and evolution of telomeres
Jirí Fajkus1, Eva Sýkorová, Andrew R Leitch
1Laboratory of Functional Genomics and Proteomics, Faculty of Science, Masaryk University Brno, Královopolská 135, CZ-61265 Brno, Czech Republic. fajkus@ibp.cz
Summary
Telomeres evolve, with plants showing unique sequence changes and loss of typical structures. Alternative lengthening of telomeres (ALT) may involve recombination, replication, or retrotransposition, impacting chromosome evolution.
Area of Science:
- Evolutionary biology
- Molecular genetics
- Genomics
Background:
- Telomeres protect chromosome ends but vary across species.
- The monocot order Asparagales exhibits two key telomere sequence evolutionary switch-points.
- Telomere loss is observed in various plant and arthropod groups.
Purpose of the Study:
- To examine telomere evolution from an evolutionary perspective.
- To investigate alternative telomere maintenance mechanisms beyond telomerase.
- To discuss the impact of telomere dysfunction on chromosome evolution and speciation.
Main Methods:
- Comparative analysis of telomere sequences across different taxa.
- Review of existing literature on telomere synthesis and maintenance.
- Hypothesizing evolutionary pathways for telomere elongation and maintenance.
Main Results:
- Identified two major telomere sequence evolutionary switch-points in Asparagales.
- Observed replacement of typical telomeres with vertebrate-like motifs and unknown mechanisms.
- Documented telomere loss in diverse plant and arthropod lineages.
- Proposed alternative telomere maintenance mechanisms including t-loops, t-circles, and recombination.
Conclusions:
- Telomerase may not be the original end-maintenance system.
- Alternative lengthening of telomeres (ALT) likely involves recombination and replication processes.
- Changes in telomere sequences and maintenance impact chromosome evolution and potentially speciation.