The evolutionary analysis on complement genes reveals that fishes C3 and C9 experience different evolutionary...

Area of Science:

• Immunology
• Evolutionary Biology
• Genetics

Background:

• Complement system is crucial for innate immunity, pathogen clearance, and bridging innate and acquired immunity.
• Complement component 3 (C3) is central to complement activation pathways.
• Complement component 9 (C9) forms the membrane attack complex (MAC) to lyse microorganisms.

Purpose of the Study:

• To investigate the evolutionary patterns of complement component 9 (C9) genes.
• To compare the evolutionary trajectories of C3 and C9 genes.
• To determine if C3 and C9 exhibit different evolutionary patterns across species.

Main Methods:

• Employed the sliding window method to calculate evolutionary rates (ω) in C3 and C9 codons.
• Utilized the maximum likelihood (ML) method to identify positive selection sites.
• Analyzed C3 and C9 gene evolution in both fish and mammalian species.

Main Results:

• Positive selection sites were identified in mammalian C9 genes but not in fish C9 genes.
• Conversely, positive selection sites were found in fish C3 genes, but not in mammalian C3 genes.
• Demonstrated that C3 and C9 exhibit divergent evolutionary patterns between mammals and fishes.

Conclusions:

• The study concludes that C3 and C9 genes display different evolutionary patterns in mammals and fishes.
• Environmental factors likely drive these distinct evolutionary trajectories.
• Suggests that different complement components may evolve uniquely across diverse species and environments.