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The genome sequence of Atlantic cod reveals a unique immune system
Bastiaan Star1, Alexander J Nederbragt, Sissel Jentoft
1Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, PO Box 1066, Blindern, N-0316 Oslo, Norway.
Nature
|August 12, 2011
Summary
The Atlantic cod genome reveals unique immune system adaptations, including the loss of major histocompatibility complex (MHC) II genes, compensated by expanded MHC I and altered Toll-like receptors (TLRs). This provides insights into vertebrate immune evolution.
Area of Science:
- Genomics
- Immunology
- Evolutionary Biology
Background:
- Atlantic cod (Gadus morhua) is commercially important and cold-adapted.
- Understanding its genome is crucial for fisheries and aquaculture.
- Previous knowledge of its immune system's complexity was limited.
Purpose of the Study:
- To present the genome sequence of Atlantic cod.
- To investigate its thermal adaptations and immune architecture.
- To understand the evolution of its immune system.
Main Methods:
- Genome sequencing using 454 technology (shotgun and paired-end libraries).
- Automated gene annotation to identify protein-coding genes.
- Comparative analysis of immune system components, including MHC and TLRs.
Main Results:
- A genome assembly with 22,154 identified genes.
- Evidence of complex thermal adaptations in the haemoglobin gene cluster.
- Loss of major histocompatibility complex (MHC) II pathway genes (MHC II, CD4, invariant chain).
- Expansion of MHC I genes and a unique composition of Toll-like receptor (TLR) families.
- Atlantic cod exhibits compensatory immune mechanisms despite MHC II absence.
Conclusions:
- The Atlantic cod genome provides a resource for understanding cold-adaptation and aquaculture.
- The fish possesses an unusual immune system architecture, lacking key adaptive immune genes.
- Compensatory mechanisms in innate and adaptive immunity suggest novel evolutionary pathways for vertebrate immune systems.
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