title: Dnd knockout ablates germ cells and demonstrates germ cell independent sex differentiation in Atlantic salmon.
abstract: Introgression of farmed salmon escapees into wild stocks is a major threat to the genetic integrity of wild populations. Using germ cell-free fish in aquaculture may mitigate this problem. Our study investigated whether it is possible to produce germ cell-free salmon in F0 by using CRISPR-Cas9 to knock out dnd, a factor required for germ cell survival in vertebrates. To avoid studying mosaic animals, sgRNA targeting alb was simultaneously used as a visual tracer since the phenotype of alb KO is complete loss of pigmentation. Induced mutations for the tracer (alb) and the target (dnd) genes were highly correlated and produced germ cell-less fish lacking pigmentation, underlining the suitability of alb KO to serve as tracer for targeted double allelic mutations in F0 animals in species with prohibitively long generation times. This is also the first report describing dnd knockout in any fish species. Analyzing gene expression and histology of dnd KO fish revealed that sex differentiation of the somatic compartment does not depend on the presence of germ cells. However, the organization of the ovarian somatic compartment seems compromised in mutant fish.
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway.
authors.forename: Anna
authors.initials: A
authors.lastname: Wargelius
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway.
authors.forename: Sven
authors.initials: S
authors.lastname: Leininger
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway.
authors.forename: Kai Ove
authors.initials: KO
authors.lastname: Skaftnesmo
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway.
authors.forename: Lene
authors.initials: L
authors.lastname: Kleppe
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway.
authors.forename: Eva
authors.initials: E
authors.lastname: Andersson
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway.
authors.forename: Geir Lasse
authors.initials: GL
authors.lastname: Taranger
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway.|Utrecht University, Science Faculty, Department Biology, Padualaan 8, NL-3584 CH Utrecht, The Netherlands.
authors.forename: Rüdiger W
authors.initials: RW
authors.lastname: Schulz
authors.affiliation: Institute of Marine Research, P.O. Box 1870, Nordnes, NO-5817 Bergen, Norway.
authors.forename: Rolf B
authors.initials: RB
authors.lastname: Edvardsen
mesh_terms: D000818:Animals; D064113:CRISPR-Cas Systems; D005260:Female; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D055785:Gene Knockdown Techniques; D005854:Germ Cells / Q000378:metabolism*; D008297:Male; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D020317:Salmo salar / Q000235:genetics / Q000378:metabolism; D012733:Sex Differentiation / Q000235:genetics*
chemical_list: D029941:Fish Proteins; D016601:RNA-Binding Proteins