Studying the Atlantic cod microbiome in Oslo

As announced last year, the University of Bath has founded The Milner Centre for Evolution, after receiving a generous £5 million donation from Bath alumnus Dr Jonathon Milner. The centre is partnered with the University of Oslo's Centre for Ecological and Evolutionary Synthesis (CEES), which has been at the forefront of ecological and evolutionary research for a number of years. This partnership will enable collaborations between experts from the two universities, and also give young scientists the opportunity to travel and perform research in different environments. As such, I am very grateful to the University of Bath for awarding me funding for a five week research stay at the University of Oslo (CEES), under the Future Research Leaders Incubator Scheme.

So, why am I here? Some of you may have heard about a relatively new field of research into bacterial communities - such communities are known as a 'microbiome'. These microbiomes are generally comprised of many bacterial species, and so are shaped by the interactions between these species, their hosts, and the environment. It has recently been estimated that there are as many bacterial cells living in or on our body as human cells 1. Just think about that for a second. These bacteria are not merely passengers within our bodies, rather they play an important role in maintaining our health. There is increasing evidence that imbalances in our microbiome are linked with poorly understood diseases, such as irritable bowel syndrome, Crohn's disease, and some cancers 2. Although much of this research is uncertain, it shows great promise in helping us to understand these diseases. Despite active research into the human microbiome, there has been little focus on microbiomes from other organisms. I am spending my time in Oslo studying the cod microbiome (in particular the Atlantic cod).

Why are cod important? Atlantic cod are widely consumed, commercially important fish; as a result their numbers have repeatedly suffered from overfishing. They are long-lived (up to 25 years), large (up to 2m long, and 95 kg in weight), and wide-ranging. Populations are found off the shores of the Northeastern USA, Greenland, and most of Northwestern Europe from the Bay of Biscay to the Arctic Circle. Some populations are coastal, whilst others, such as the Northeast Arctic cod (referred to as skrei, a Norwegian name meaning the wanderer) live much further out to sea. These populations are genetically distinct, and show adaptations to their different environments 3–5. But what about their microbiomes? Do different populations vary in their microbiomes? If so, do these differences help to protect against different environmental stresses? Could we use this information to improve monitoring of the health of cod populations? These are the questions I am trying to answer during my stay. This is made possible by combining bacterial genomics expertise at the University of Bath with cod genomics expertise at the University of Oslo.

1. Sender, R., Fuchs, S. & Milo, R. Revised estimates for the number of human and bacteria cells in the body. bioRxiv 036103 (2016). doi:10.1101/036103
2. Cho, I. & Blaser, M. J. The human microbiome: at the interface of health and disease. Nat. Rev. Genet. 13, 260–270 (2012).
3. Sodeland, M. et al. 'Islands of divergence' in the Atlantic cod genome represent polymorphic chromosomal rearrangements. Genome Biol. Evol. (2016). doi:10.1093/gbe/evw057
4. Berg, P. R. et al. Adaptation to Low Salinity Promotes Genomic Divergence in Atlantic Cod (Gadus morhua L.). Genome Biol. Evol. 7, 1644–1663 (2015).
5. Karlsen, B. O. et al. Genomic divergence between the migratory and stationary ecotypes of Atlantic cod. Mol. Ecol. 22, 5098–5111 (2013).