Atlantic Cod Survive Without ‘Vital’ Immune Genes…
Unique immune system in Atlantic cod. CEES-led team make ground-breaking discovery about the Atlantic cod immune system, published in Nature and featured in Nature News. An international team of researchers used high throughput sequencing technology to make a striking discovery that changes fundamental ideas about the evolution of the immune system in vertebrates. These results are published in this week’s issue of Nature.The team, led by researchers from the University of Oslo, found that an important component of the Atlantic cod immune system is absent. In other vertebrates, including humans, this component helps fight disease due to bacterial infections and parasites. “The overall aim of this initiative was to obtain the entire genome sequence of the Atlantic cod by utilizing new technology”, says Prof. Kjetill S. Jakobsen at the Centre for Ecological and Evolutionary Synthesis (CEES) University of Oslo, who led the team of researchers. “We had not expected to find that Atlantic cod has lost such a crucial component of its immune system.” Prof. Jakobsen explains: “All vertebrates, including humans, have a complex immune system that fights disease. This immune system, like the genetic code, originated only once in evolutionary history. Therefore, all vertebrates share similar components of this
system and we expected that Atlantic cod possessed a minimum set of genes responsible for these components. Nevertheless, despite some very hard searching, we concluded that some genes were missing.”In fact, Atlantic cod has lost the genes that are essential for the function of the major histocompatibility complex (MHC) II pathway. In humans, the malfunction of this pathway leads to severe disease or even death. Atlantic cod, however, is not exceptionally susceptible to disease under natural conditions. Interestingly, other genes in the Atlantic cod genome are far more numerous than expected. For example, large increase in the numbers of MHC I genes and Toll-like receptor (TLR) genes were found, indicating that Atlantic cod relies relatively more on these genes for its immune response and has developed unique mechanisms to deal with bacterial infections. Knowledge of such alternative mechanisms will greatly help understanding of the evolution of immune function in vertebrates and even humans, and will allow for more targeted vaccine development – aiding disease management and the process of domestication of Atlantic cod. The research team; The project is lead by Prof. Kjetill S. Jakobsen, and has been carried out by his team (CEES, Univ. of Oslo, chaired by Prof. Nils Chr. Stenseth) in collaboration with national and international research groups: Centre for Ecological and Evolutionary Synthesis (CEES), Dept. of Biology, Univ. of Oslo; group leader Kjetill S. Jakobsen – Centre for Integrative Genetics (CIGENE), Univ. of Life Sciences group leaders; Stig W. Omholt and Sigbjørn Lien – Computational Biology Unit (CBU), Univ. of Bergen; group leader Inge Jonassen – Dept of
Biology, Univ. of Bergen/Inst. For Marine Research (IMR); group leader Frank Nilsen – Nofima Marin; group leader Øivind Andersen – Univ. of Nordland; group leader Truls Moum – Dept for Molecular Biotechnology, Univ. of Tromsø; group leader Steinar Johansen – 454/ Roche (USA); group leaders Lei Du, Jim Knight – Max Planck Institute (Germany); group leader Richard Reinhardt – The Wellcome Trust Sanger Institute (GB); group leader Steve Searle. For further information please contact: Prof. Kjetill S. Jakobsen. News from: University of Oslo ~ The Atlantic cod, Gadus morhua, is a well-known demersal food fish belonging to the family Gadidae. It is also commercially known as cod, codling or haberdine.In the western Atlantic Ocean cod has a distribution north of Cape Hatteras, North Carolina, and round both coasts of Greenland; in the eastern Atlantic it is found from the Bay of Biscay north to the Arctic Ocean, including the Baltic Sea, the North Sea, areas around Iceland and the Barents Sea.It can grow to 2 meters in length and weigh up to 96 kilograms (210 lb). It can live for 25 years and sexual maturity is generally attained between ages 2 to 4, but can be as late as 8 years in the northeast Arctic.Colouring is brown to green with spots on the dorsal side, shading to silver ventrally. A lateral line is clearly visible. Its habitat ranges from the shoreline down to the continental shelf. Several cod stocks collapsed in the 1990s (declined by >95% of maximum historical biomass) and have failed to recover even with the cessation of fishing. This absence of the apex predator has led to a trophic cascade in many areas.Many other cod stocks remain at risk. The “Atlantic Cod” is labelled VU (vulnerable) on the IUCN Red List of Threatened Species. G.N.
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