Kleppe Lene

#acquacoltura

PhD, Institute of Marine Research – Bergen-Borway

Sessione: L’ACQUACOLTURA COME STRATEGIA DI SVILUPPO PER ECONOMIA E AMBIENTE

Editing genetico con CRISPR/Cas9: un punto di svolta per l’acquacoltura?

Norway is the world’s biggest producer of Atlantic salmon, with a yearly production of more than 1,2 million tons. However, sustainability concerns are currently hampering further expansion of the industry. One of the concerns is that farmed escapees may reproduce with wild salmon, and consequently affect the genetic integrity of wild strains. A second and more acute challenge is the high prevalence of salmon lice due to high densities of salmon in sea cages, which causes infections and lethality in both farmed and wild salmon. There are also concerns regarding the increasing replacement of marine ingredients with plant-based material in the production of feed, which leads to a reduced concentration of omega-3 fatty acids in the farmed salmon. Finally, future changes in sea temperature and production systems may require a more robust salmon to avoid phenotypes associated with stress (diseases, deformities) and precocious sexual maturation.

In the recent years, the field of gene editing has made substantial advances due to the introduction of CRISPR/Cas9, a highly efficient and potent methodology. CRISPR/Cas9 allows editing of specific DNA sequences in any organism, including fish, which opens for new possibilities to edit key genetic traits in aquaculture. The CRISPR/Cas9 methodology allows gene editing at different levels, and does not necessarily involve transgenesis (where genetic material from unrelated species are added to alter or create new traits), which has been the major focus for the criticism towards genetically modified organisms. With CRISPR/Cas9 it is possible to perform cisgenetic gene editing, which does not introduce any “foreign” DNA to the organism, but instead induces changes in its existing genome sequence, which is different from traditional technologies used to edit genomes.

We have established a protocol for gene knockout by CRISPR/Cas9 in Atlantic salmon, which allows us to perform functional studies with the aim to identify the genetic signature behind specific phenotypes, such as early/late sexual maturation and resistance to diseases. This will reveal key genes that may be targeted in the future to solve the major environmental challenges, and therefore ensure a more sustainable production of salmon. Since traditional breeding techniques are extremely time consuming, other methods should be elucidated. Future studies should investigate if and how gene editing can be applied in aquaculture.

A first prerequisite for the introduction of gene edited fish to sea cage farming is sterility, to avoid any chances of genetic introgression of escapees with wild salmon populations. Therefore, we have explored the possibility to produce salmon devoid of germ cells, and thus is 100% sterile. This has been successful using CRISPR/Cas9 to knock out one single gene, dead end (dnd). Furthermore, our germ cell-free salmon shows no signs of entering puberty, which is different from the sterile triploid salmon that is currently being tested for large scale production in some salmon farms. Nevertheless, since germ cell-free broodstock cannot reproduce, we do not yet have an efficient way to produce these fishes. We are currently working on ideas on how to solve this. We also have ongoing projects investigating if we can affect other phenotypic traits in salmon, such as the age at puberty onset and omega 3 metabolism. The main aims of these projects are to gain more knowledge on the factors underlying phenotypes of interest in farmed salmon, however, such knowledge could potentially also be used in the future by the farmers with the aim to obtain a more sustainable production.

Curriculum Vitae

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