A research group led by Hiyori Sakaguchi, a first-year master's student at Utsunomiya University, and Project Associate Professor Reimasa Iwanami was the first in the world to succeed in raising young medaka fish under sterile conditions.We have demonstrated that intestinal bacteria are necessary for the development of the intestinal tract and the normal functioning of the immune system.
The balance of intestinal bacteria is important for maintaining human health, and a decline in immune function affects the balance of intestinal bacteria.This is said to be the same in fish, but until now there has been little experimental proof.Therefore, the research group investigated the interaction between the immune system and the intestinal microbiota using the medaka fish, which is a small fish model that is easy to genetically manipulate.
The research group created germfree medaka by hatching medaka eggs under sterile conditions and feeding them sterilized food.As a result of comparing normal medaka fish with intestinal bacteria and germ-free medaka fish, the function (expression) of a group of genes involved in biological defense responses was reduced in germ-free medaka fish, and abnormal development of intestinal epithelial cells was observed.It has been found that medaka fish that grow in too clean an environment do not mature in their immune function.
Next, they conducted an experiment using immunodeficient medaka fish, which do not have lymphocytes that can deal with microorganisms in the water, including intestinal bacteria.As a result, in immunodeficient medaka fish, only certain bacteria increased significantly, and the balance of intestinal bacteria was gradually lost.The immune system of medaka fish was found to be necessary for maintaining a normal intestinal bacterial balance.
These results revealed that the immune function and intestinal bacteria of medaka fish interact with each other.This research result, which shows the relationship between intestinal bacteria and the immune function of medaka fish, has academic significance in helping to understand symbiotic evolution, and is expected to be applied to maintaining the health of fish in the fisheries and aquaculture industries. .
Paper information:[Frontiers in Immunology] Maturation of the medaka immune system depends on reciprocal interactions between the microbiota and the intestinal tract
