by Karin Pittman 1,2,
Sjur Øyen S1, Mette Sørensen3, Kjetil Korsnes 3,4, Dalia Dahle3, Nimalan
Nadanasabesan 3, Mearge Okubamichael2, Grigory Merkin G2, Ole Jacob Myre2
1. Dept of Biosciences, Univ of Bergen, Thormøhlensgate 53, 5006 Bergen, Norway
2. Quantidoc AS, Thormøhlensgate 41, 5006 Bergen Norway
3. Nord University, P.O. Box 1490, 8049 Bodø, Norway
4. BioVivo Technologies AS, Storbjørnen 17, 8029 Bodø, Norway
Fish wear their immune system on the outside and the answer to many industry
conundrums is likely hiding in plain sight. This statement refers to the
mucosal immune system, or rather all the slimy barriers in skin, gills and
intestines (the outside of the inside), (See Figures 1A and 1B).
Why does this matter? We can think of this protection like a detective’s tools
to find out where a production challenge lies: the skin is the shield and able
to tolerate some handling and damage, the gills are the sentinel guarding 50
percent of the surface area of the fish, while the guts are the foundation,
reliant on incoming nutrition upon which almost all else in the fish is built.
The structure of skin, gill and gut mucosal barriers at the cell-level is
almost identical. These tissues can regenerate, and they can learn: this innate
mucosal (mucus) immune system is more important for fish than the typical
acquired immune system is for mammals. Fish are hatched with this protective
system, optimised quite free-of-charge by nature through about 500 million
years of evolution. It knows a thing or two about protecting fish health,
survival and tolerance.
If we can read these immune responses, so what? Feeds give different signals to
the guts and the skin, and sometimes to the gills. Everyone knows about the
anti-nutrients that come from terrestrial plantstuffs, and everyone knows that
fishmeal is generally more expensive than plant ingredients.
Fish gut microbiomes are clearly different from mammalian gut microbiomes and
fish genes even more diverse than mammalian genes. This makes functional
interpretation a challenge, but we have to start somewhere. To summarise the
effects of genes, fatty acids, proteins, lipids and treatments we can look at
the tissue which contains the cells we are interested in, the mucus or goblet
cells.
This is a much higher level of biological organisation than genes and it is
much less variable. The fish intestine reacts to the entirety of a recipe, not
just the fashionable silver bullet ingredient.
Read more, HERE.
The Aquaculturists
