Changes in the immune system lead to success

DNA
Credit: CC0 Public Domain

The sequencing of the Atlantic cod genome in 2011 demonstrated that this species lacks a crucial part of its immune system. In a follow-up study, Kjetill S. Jakobsen and collaborators have investigated a large number of additional fish species and found that this is a trait that Atlantic cod have in common with its close relatives, the codfishes. Further analyses show that the alternate immune system observed is associated with increased speciation rates, and a key to the success of this group of fishes. The results are now published in the world-leading journal Nature Genetics.

Altogether, 65 new fish species were genome sequenced which made a foundation for a new bony fish phylogeny and further revealed that the loss of the central immune gene MHC II occurred around 100 million years ago in the branch leading to codfishes. Intriguingly, it was shown that the codfishes have evolved an alternative strategy by substantially increasing in the copy-number of another immune gene, MHC I, found to influence another evolutionary process:

"Other researchers have suggested that the immune genes also have an effect on mate choice and speciation processes. For example, immune genes may affect in three spined stickleback, and even among humans – although the human results are thought to be controversial. Until now we have not had empirical data on MHC I and speciation. Our findings for codfishes and other groups of fishes are a breakthrough," Kjetill S. Jakobsen explains.

In addition to evolution of the immune system, an improved phylogeny and new insight into speciation these results are of interest to immunological research in general:

"Our data shows that the immune system is far more evolutionary flexible than previously believed. The prevailing view has been that the human immune system is universal and can serve as a model for all vertebrates. Now, by adding the bony fishes – the largest group of vertebrates – it turns out that we, the humans, may be the special case. This knowledge has implications for all immunological research – including us," Sissel Jentoft says.

A particular challenge for cod aquaculture has been the difficulties in developing vaccines by traditional methods. The new knowledge about the of Atlantic cod and other codfishes may catalyse more efficient methods for vaccine development.


Explore further

Sequencing of cod genome reveals unique immune system characteristic

More information: Martin Malmstrøm et al. Evolution of the immune system influences speciation rates in teleost fishes, Nature Genetics (2016). DOI: 10.1038/ng.3645
Journal information: Nature Genetics

Provided by University of Oslo
Citation: Changes in the immune system lead to success (2016, August 30) retrieved 14 May 2021 from https://phys.org/news/2016-08-immune-success.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
10 shares

Feedback to editors

User comments