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Comparative Genomics Identifies Epidermal Proteins Associated with the Evolution of the Turtle Shell
Karin Brigit Holthaus1, Bettina Strasser2, Wolfgang Sipos3
1Research Division of Biology and Pathobiology of the Skin, Department of Dermatology, Medical University of Vienna, Vienna, Austria Dipartimento di Scienze Biologiche, Geologiche ed Ambientali (BiGeA), University of Bologna, Bologna, Italy.
Molecular Biology and Evolution
|November 26, 2015
Summary
Turtles evolved unique skin structures, like their shells, through adaptations in Epidermal Differentiation Complex (EDC) genes. These genes, particularly beta-keratins, show specific expression patterns linked to shell development in turtles.
Area of Science:
- Evolutionary biology
- Genomics
- Molecular biology
Background:
- Reptile, bird, and mammal evolution involved unique integumentary structures.
- The Epidermal Differentiation Complex (EDC) gene cluster drives epidermal protein evolution.
- Turtles possess unique, mechanically resilient epidermal modifications for defense.
Purpose of the Study:
- Investigate molecular adaptations in turtle integument evolution.
- Analyze Epidermal Differentiation Complex (EDC) gene sequences and expression in turtles.
- Determine the role of EDC genes in the evolutionary innovation of the turtle shell.
Main Methods:
- Comparative genomics using newly available turtle genome sequences.
- Identification of the epidermal differentiation gene complement in turtles.
- Gene expression analysis in European pond turtle skin from various body sites.
Main Results:
- The turtle EDC contains over 100 genes, including at least 48 beta-keratin/corneous beta-protein genes.
- Some EDC proteins exhibit high cysteine/proline content (>50%).
- Distinct EDC gene subfamilies expanded and translocated outside the EDC in turtles.
- Differential expression of EDC genes observed across body sites, with specific beta-keratins highly expressed in the shell.
Conclusions:
- Turtle shell evolution is linked to specific molecular adaptations of epidermal differentiation.
- EDC gene evolution and expression patterns are crucial for turtle integumentary innovations.
- Beta-keratin genes, both within and outside the EDC, play a key role in shell formation.
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