Gene-editing tool to speed disease studies in fish

An improved gene-editing tool could improve the understanding of the genetic basis of disease resistance in valuable species of farmed fish, researchers have found.

Scientists at the Roslin Institute have developed the optimised technique to efficiently introduce changes in fish cell cultures in the lab.

They used cells of Atlantic salmon, rainbow trout, and Chinook salmon, which together are worth US$22bn a year to the aquaculture industry.

The gene-editing tool, which is fast and efficient compared with existing techniques, could be used to investigate specific genes involved in the response to pathogens, and the role of these genes in natural variation in disease resistance in fish populations.

Improved gene editing
More than 90 per cent of cells can be edited with the method and the protocol takes approximately half the time required for existing gene-editing methods.

The editing method uses a complex molecule formed of a combination of single stranded genetic material, or RNA, and a protein known as CRISPR/Cas9, responsible for cutting DNA. These molecules – called ribonucleoprotein complexes – have shown potential for gene editing in previous studies in other species.

Scientists applied an electrical field to the ribonucleoprotein complexes, which increased the permeability of the fish cell membrane and allowed DNA to be introduced into cells.

The cell cultures in the study are widely used in genetics and immunology studies of fish species.

Dr Remi Gratacap, Roslin Institute, said: “Genetically engineering fish cells in the lab is very challenging because the cells grow slowly and there is currently no efficient way to introduce DNA in them. This new method circumvents these challenges. It is simple, fast, and efficient, and we have shown that it can be used in genetic studies of important aquaculture species.”

Dr Yehwa Jin, Roslin Institute, said: “This improved editing technique has allowed us to investigate specific candidate genes involved in resistance to pathogens for Atlantic salmon and rainbow trout, leading to insight into the functional basis of disease resistance in these important aquaculture species.”

The study was jointly led by Roslin scientists Dr Remi Gratacap and Dr Yehwa Jin, with input from Master’s student Marina Mantsopoulou, who work in the research group of Professor Ross Houston. It is published in the journal Marine Biology and has been funded by Biotechnology and Biological Sciences Research Council, part of UK Research and Innovation, through the consortium project ‘AquaLeap’.