Evolution of the complement system C3 gene in Antarctic teleosts.
Daniela Melillo1, Sonia Varriale2, Stefano Giacomelli2
1Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli (SZN), Italy.
Molecular Immunology
|April 25, 2015
Summary
Antarctic fish evolved increased flexibility in their complement C3 protein (the third component of the complement system) to function in cold waters. This adaptation involves positive selection and affects key functional domains.
Area of Science:
- Marine Biology
- Evolutionary Biology
- Immunology
Background:
- Notothenioidei are Antarctic teleosts uniquely adapted to extreme cold.
- The complement system, particularly C3, plays a crucial role in immune responses.
Purpose of the Study:
- To investigate the sequence and structure of C3 in Antarctic notothenioids.
- To identify adaptive evolutionary changes in Antarctic fish C3.
Main Methods:
- Determined nucleotide sequences of C3 isoforms in Trematomus bernacchii and Chionodraco hamatus.
- Performed sequence alignments and analyzed for diversifying selection.
- Constructed molecular models and conducted molecular dynamics simulations.
Main Results:
- Identified evidence of positive selection in Antarctic teleost C3 sequences, particularly in Chionodraco hamatus.
- Observed adaptive selection at numerous amino acid positions, including the anaphylatoxin domain.
- Antarctic C3 models exhibited increased flexibility compared to temperate relatives.
Conclusions:
- Antarctic teleost C3 molecules have positively evolved for enhanced flexibility.
- This increased flexibility is crucial for function in the low kinetic energy Antarctic marine environment.
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