Loss of bmp15 gene function does not abolish fertility in male Atlantic salmon

@article{crespo2026loss,
  title = {{Loss of bmp15 gene function does not abolish fertility in male Atlantic salmon}},
  author = {Diego Crespo and Per Gunnar Fjelldal and Tom J. Hansen and Erik Kjærner-Semb and Fernando Ayllon and Kai Ove Skaftnesmo and Anders Thorsen and Birgitta Norberg and Rolf B. Edvardsen and Eva Andersson and Rüdiger W. Schulz and Rüdiger W. Schulz and Anna Wargelius and Lene Kleppe},
  journal = {Frontiers in Genetics},
  year = {2026},
  month = nov,
  doi = {10.3389/fgene.2026.1945517},
  url = {https://doi.org/10.3389/fgene.2026.1945517},
  note = {CC BY},
}

TY  - JOUR
TI  - Loss of bmp15 gene function does not abolish fertility in male Atlantic salmon
AU  - Diego Crespo
AU  - Per Gunnar Fjelldal
AU  - Tom J. Hansen
AU  - Erik Kjærner-Semb
AU  - Fernando Ayllon
AU  - Kai Ove Skaftnesmo
AU  - Anders Thorsen
AU  - Birgitta Norberg
AU  - Rolf B. Edvardsen
AU  - Eva Andersson
AU  - Rüdiger W. Schulz
AU  - Rüdiger W. Schulz
AU  - Anna Wargelius
AU  - Lene Kleppe
PY  - 2026
DA  - 2026/11/04
JO  - Frontiers in Genetics
DO  - 10.3389/fgene.2026.1945517
UR  - https://doi.org/10.3389/fgene.2026.1945517
AB  - IntroductionBone morphogenetic protein 15 (BMP15), a transforming growth factor β (TGF-β) superfamily member, is well known for its crucial involvement in regulating female reproduction in mammals, and recently also in fishes. However, the biological function(s) of Bmp15 in male reproduction are largely unknown in vertebrates in general. MethodsIn this study, we used CRISPR/Cas9 technology to generate Atlantic salmon bmp15 mutants to investigate its potential role in testis development, spermiation rates and sperm motility.ResultsNo apparent phenotypic differences were observed at either of the two sampling points (18 and 22 months of age) carried out prior to the spawning season, in any of the mutant groups. However, at 22 months of age, mutant males showed a higher frequency of individuals in the rapid testicular growth phase than wild-type (WT) controls (63.6% versus 33.3%). Then, males that remained sexually immature and homozygous for the frameshift mutations (bmp15 fs/fs) were significantly shorter and lighter than WT controls from 26 months of age (at spawning) onwards; they also exhibited a higher incidence of deformed vertebrae and significantly lower testicular transcript levels for two growth factors (amh, gsdf) when examined at the age of 26 months. Regarding testis maturation, 26 month-old fs/fs mutant males showed a higher frequency of spermiating fish than WTs. However, further analyses revealed variation in vgll3a genotype - linked to age at maturity - among the fish investigated, as well as a vgll3a genotype-dependent association with spermiation probability. No significant differences were found regarding the plasma levels of 11-ketotestosterone, the main androgen in fish, irrespective of the maturation stage. Also regarding sperm motility and trajectory, no significant differences were detected between mutants and WTs in the two following reproductive seasons, under the conditions of this study.ConclusionThis is the first mutant model in fish investigating Bmp15-mediated action in the male gonad and, similarly to the only other genetic model available in vertebrates to date–the pig –, no remarkable testicular phenotypes were revealed. Future studies will be required to determine whether these effects are evolutionary conserved across vertebrates, or whether distinct or additional phenotipic consequences emerge in other fishes or tetrapods.
SN  - 1664-8021
ER  -