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Deep phylogenomics of a tandem-repeat galectin regulating appendicular skeletal pattern formation
Ramray Bhat1,2, Mahul Chakraborty3, Tilmann Glimm4
1Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. ramray@mrdg.iisc.ernet.in.
BMC Evolutionary Biology
|August 20, 2016
Summary
Evolutionary changes in Galectin-8 (Gal-8) genes, including non-coding motif acquisition and selection pressures, explain the diverse skeletal patterns across vertebrate fins and limbs. This network
Area of Science:
- Developmental Biology
- Evolutionary Biology
- Genomics
Background:
- Vertebrate skeletal patterning involves a network of Galectin-1 (Gal-1) and Galectin-8 (Gal-8).
- Distinct skeletal structures exist in chondrichthyan fins, actinopterygian fins, and tetrapod limbs.
- Galectin-1 structure is conserved across vertebrates, prompting investigation into Galectin-8's role in tetrapod limb evolution.
Purpose of the Study:
- To understand the evolutionary origins of the galectin-based skeletal patterning network.
- To investigate the contribution of Galectin-8 gene evolution to the emergence of the tetrapod limb pattern.
Main Methods:
- Comparative genomic analysis.
- Protein evolution studies.
- Application of a reaction-diffusion-adhesion model.
Main Results:
- Galectin-8 gene evolution varied across fish lineages (Actinopterygii vs. Sarcopterygii).
- Sarcopterygian Galectin-8 genes gained a regulatory motif and underwent purifying selection.
- Actinopterygian Galectin-8 genes lacked this motif and experienced positive selection.
Conclusions:
- Galectin-8 gene evolution, including regulatory motif acquisition and differential selection, explains distinct skeletal patterns in vertebrates.
- The reaction-diffusion-adhesion model, informed by these findings, accounts for the diversity of skeletal structures from fish fins to tetrapod limbs.
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