Genomic view of the evolution of the complement system

Area of Science:

• * Evolutionary biology
• * Genomics
• * Immunology

Background:

• * The complement system is a crucial part of innate immunity.
• * Genomic data provides insights into the evolutionary history of immune genes.

Purpose of the Study:

• * To trace the evolutionary trajectory of the complement system.
• * To identify key gene duplication events in complement system evolution.
• * To determine the evolutionary origins of complement genes.

Main Methods:

• * Comparative genomics across diverse animal phyla.
• * Analysis of gene presence/absence patterns in sequenced genomes.
• * Phylogenetic reconstruction of complement gene families.

Main Results:

• * Bony fish and higher vertebrates share a conserved set of complement genes, suggesting major duplications occurred before teleost/mammalian divergence (~500 MYA).
• * Ascidians possess many complement gene families, but duplications appear to have occurred independently of vertebrate lineage.
• * Core complement genes (C3 and factor B) are found in cnidarians and some protostomes, indicating an ancient origin (>1,000 MYA).

Conclusions:

• * The mammalian complement system's architecture was largely established by the teleost/mammalian divergence.
• * Independent gene duplications occurred in ascidian and vertebrate lineages.
• * The central components of the complement system originated over a billion years ago.