W042 The Genome Sequence of Atlantic Cod: Lessons for Breeding and Aquaculture

Date: Saturday, January 14, 2012
Time: 2:35 PM
Room: Royal Palm Salons 3-4
Kjetill S. Jakobsen , University of Oslo, Oslo, Norway
Lex Nederbragt , University of Oslo
Sissel Jentoft , University of Oslo
Bastiaan Star , University of Oslo
Trine B. Rounge , University of Oslo
Martin Malmstrøm , University of Oslo
Tone F Gregers , University of Oslo
Monica H Solbakken , University of Oslo
Karin Lagesen , University of Oslo
Paul R. Berg , University of Oslo
The Atlantic cod (Gadus morhua) is a cold-adapted teleost that supports economically important fisheries and incipient aquaculture. However, the emerging cod aquaculture has experienced economic setbacks in part due to high costs associated with larval production and high susceptibility to infections.

We have sequenced and assembled the genome of the Atlantic cod by 454 pyrosequencing of shotgun and paired-end libraries. Comprehensive automated annotation, which relied on comparisons to the stickleback genome, resulted in a gene set of 22,154 genes. The completed genome revealed that Atlantic cod has lost several genes, which in vertebrates enable the adaptive immune system to respond to pathogens such as bacteria and parasites through the MHCII pathway. Specifically, the cod genome does not contain functional genes for MHCII, Invariant chain and CD4. In other teleosts, MHCII and CD 4 are present in multiple copies located on different chromosomes. Coincidently, the genome contains a highly expanded number of MHCI genes and a unique innate immune system repertoire of Toll-like receptor gene families. These observations imply that cod has evolved alternative immune mechanisms in the absence of MHCII. The hypothesis that the expanded MHCI gene family has, to some degree, compensated for the absence of MHCII in Atlantic cod is being investigated. We are also currently exploring the cod immune response to pathogens by studying gene expression patterns during infection. Our findings will allow for more targeted vaccine development and sophisticated breeding programmes – aiding disease management and the process of domestication of Atlantic cod.