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  • 1
    Online Resource
    Online Resource
    Loss of Fshr prevents testicular maturation in Atlantic salmon ( Salmo salar L.)
    The Endocrine Society ; 2024
    In:  Endocrinology
    Details
    In: Endocrinology, The Endocrine Society
    Abstract: Early puberty poses a significant challenge for male Atlantic salmon in aquaculture due to its negative impact on growth and welfare. The regulation of puberty in vertebrates involves two key reproductive hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and their gonadal receptors. In male mice lacking FSH receptor, testes size is reduced, but fertility is maintained, while medaka and zebrafish with a disrupted fshr gene exhibit near normal testis size and fertility. In these fishes both Fsh and Lh are present during puberty and Lh may rescue fertility, while in salmonid fish only Fsh is present in the circulation during puberty. Using CRISPR-Cas9, we produced crispants with a high prevalence of fshr mutations at the target site, which remained fertile, although more than half showed a testis development deviating from wild-type (wt) males. Crossing out these F0 crispants to each other produced a viable F1 generation showing frameshift (fshr-/-) or in-frame mutations (fshrif/if). Nearly all wt males matured while all fshr-/- males remained immature with small testes containing A spermatogonia as the furthest developed germ cell type and prepubertal plasma androgen levels. Also, the pituitary transcript levels of gnrhr2bba and lhb, but not for fshb, were reduced in the fshr-/- males compared to maturing males. More than half of the fshrif/if mutant males showed no, or a delayed maturation. In conclusion, Atlantic salmon show the unique characteristic that loss of Fshr function alone results in male infertility, offering new opportunities to control precocious puberty or fertility in salmon.
    Type of Medium: Online Resource
    ISSN: 1945-7170
    URL: Article
    DOI: 10.1210/endocr/bqae013
    Language: English
    Publisher: The Endocrine Society
    Publication Date: 2024
    detail.hit.zdb_id: 2011695-0
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  • 2
    Online Resource
    Online Resource
    Sex steroid production associated with puberty is absent in germ cell-free salmon
    Springer Science and Business Media LLC ; 2017
    In:  Scientific Reports Vol. 7, No. 1 ( 2017-10-03)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 7, No. 1 ( 2017-10-03)
    Abstract: In all vertebrates studied so far, germ cells are not required for pubertal maturation of the gonadal steroidogenic system, subsequent development of secondary sex characteristics and reproductive behavior. To explore if the absence of germ cells affects puberty or growth in Atlantic salmon, germ cell-free (GCF), dnd knockout and wild type (WT) postsmolts were stimulated to enter puberty. No GCF fish entered puberty, whereas 66.7% (males) and 30% (females) WT fish completed or entered puberty, respectively. Expression of genes related to steroidogenesis ( star , cyp17a1 , cyp11β , cyp19a1a) , gonadal somatic cells ( insl 3, amh , igf 3), oocytes ( bmp15) , gonadotropin receptors ( fshr , lhcgr) , and pituitary gonadotropic cells ( fshb , lhb , gnrhr4 ) showed an immature status and failure to up-regulate gonadal sex steroid production in male and female GCF fish was also reflected in low or undetectable plasma sex steroids (11-ketotestosterone, estradiol-17β and testosterone). A gender difference (high in females, low in males) was found in the expression of star and cyp17a1 in GCF fish. No clear difference in growth was detected between GCF and immature WT fish, while growth was compromised in maturing WT males. We demonstrate for the first time in a vertebrate that germ cells are required for pubertal activation of the somatic steroidogenic cells.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-017-12936-w
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2017
    detail.hit.zdb_id: 2615211-3
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  • 3
    Online Resource
    Online Resource
    Vgll3 and the Hippo pathway are regulated in Sertoli cells upon entry and during puberty in Atlantic salmon testis
    Springer Science and Business Media LLC ; 2018
    In:  Scientific Reports Vol. 8, No. 1 ( 2018-01-30)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 8, No. 1 ( 2018-01-30)
    Abstract: Vgll3 is linked to age at maturity in Atlantic salmon ( Salmo salar ). However, the molecular mechanisms involving Vgll3 in controlling timing of puberty as well as relevant tissue and cell types are currently unknown. Vgll3 and the associated Hippo pathway has been linked to reduced proliferation activity in different tissues. Analysis of gene expression reveals for the first time that vgll3 and several members of the Hippo pathway were down-regulated in salmon testis during onset of puberty and remained repressed in maturing testis. In the gonads, we found expression in Sertoli and granulosa cells in males and females, respectively. We hypothesize that vgll3 negatively regulates Sertoli cell proliferation in testis and therefore acts as an inhibitor of pubertal testis growth. Gonadal expression of vgll3 is located to somatic cells that are in direct contact with germ cells in both sexes, however our results indicate sex-biased regulation of vgll3 during puberty.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-018-20308-1
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2018
    detail.hit.zdb_id: 2615211-3
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  • 4
    Online Resource
    Online Resource
    Author Correction: Rescue of germ cells in dnd crispant embryos opens the possibility to produce inherited sterility in Atlantic salmon
    Springer Science and Business Media LLC ; 2021
    In:  Scientific Reports Vol. 11, No. 1 ( 2021-03-22)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 11, No. 1 ( 2021-03-22)
    Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-021-86045-0
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2615211-3
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  • 5
    Online Resource
    Online Resource
    Dnd knockout ablates germ cells and demonstrates germ cell independent sex differentiation in Atlantic salmon
    Springer Science and Business Media LLC ; 2016
    In:  Scientific Reports Vol. 6, No. 1 ( 2016-02-18)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 6, No. 1 ( 2016-02-18)
    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.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/srep21284
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2016
    detail.hit.zdb_id: 2615211-3
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  • 6
    Online Resource
    Online Resource
    Table_2.DOCX
    Frontiers Media SA ; 2021
    In:  Frontiers in Cell and Developmental Biology Vol. 9 ( 2021-4-16)
    Details
    In: Frontiers in Cell and Developmental Biology, Frontiers Media SA, Vol. 9 ( 2021-4-16)
    Abstract: Entering meiosis strictly depends on stimulated by retinoic acid 8 ( Stra8 ) gene function in mammals. This gene is missing in a number of fish species, including medaka and zebrafish, but is present in the majority of fishes, including Atlantic salmon. Here, we have examined the effects of removing stra8 on male fertility in Atlantic salmon. As in mammals, stra8 expression was restricted to germ cells in the testis, transcript levels increased during the start of puberty, and decreased when blocking the production of retinoic acid. We targeted the salmon stra8 gene with two gRNAs one of these were highly effective and produced numerous mutations in stra8 , which led to a loss of wild-type (WT) stra8 expression in F0 salmon testis. In maturing stra8 crispants, the spermatogenetic tubuli were partially disorganized and displayed a sevenfold increase in germ cell apoptosis, in particular among type B spermatogonia and spermatocytes. The production of spermatogenic cysts, on the other hand, increased in maturing stra8 crispants. Gene expression analysis revealed unchanged ( lin28a, ret ) or reduced levels ( egr1, dusp4 ) of transcripts associated with undifferentiated spermatogonia. Decreased expression was recorded for some genes expressed in differentiating spermatogonia including dmrt1 and ccnd2 or in spermatocytes, such as ccna1 . Different from Stra8 -deficient mammals, a large number of germ cells completed spermatogenesis, sperm was produced and fertilization rates were similar in WT and crispant males. While loss of stra8 increased germ cell apoptosis during salmon spermatogenesis, crispants compensated this cell loss by an elevated production of spermatogenic cysts, and were able to produce functional sperm. It appears that also in a fish species with a stra8 gene in the genome, the critical relevance this gene has attained for mammalian spermatogenesis is not yet given, although detrimental effects of the loss of stra8 were clearly visible during maturation.
    Type of Medium: Online Resource
    ISSN: 2296-634X
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.3389/fcell.2021.657192
    DOI: 10.3389/fcell.2021.657192.s001
    DOI: 10.3389/fcell.2021.657192.s002
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
    detail.hit.zdb_id: 2737824-X
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  • 7
    Online Resource
    Online Resource
    Presentation_1.pdf
    Frontiers Media SA ; 2022
    In:  Frontiers in Endocrinology Vol. 13 ( 2022-3-15)
    Details
    In: Frontiers in Endocrinology, Frontiers Media SA, Vol. 13 ( 2022-3-15)
    Abstract: Precocious male maturation causes reduced welfare and increased production costs in Atlantic salmon ( Salmo salar ) aquaculture. The pituitary produces and releases follicle-stimulating hormone (Fsh), the gonadotropin triggering puberty in male salmonids. However, little is known about how Fsh production is regulated in Atlantic salmon. We examined, in vivo and ex vivo , transcriptional changes of gonadotropin-related genes accompanying the initial steps of testis maturation, in pituitaries of males exposed to photoperiod and temperature conditions promoting maturation (constant light and 16°C). Pituitary fshb , lhb and gnrhr2bba transcripts increased in vivo in maturing males (gonado-somatic index & gt; 0.1%). RNA sequencing (RNAseq) analysis using pituitaries from genetically similar males carrying the same genetic predisposition to mature, but differing by responding or not responding to stimulatory environmental conditions, revealed 144 differentially expressed genes, ~2/3rds being up-regulated in responders, including fshb and other pituitary hormones, steroid-related and other puberty-associated transcripts. Functional enrichment analyses confirmed gene involvement in hormone/steroid production and gonad development. In ex vivo studies, whole pituitaries were exposed to a selection of hormones and growth factors. Gonadotropin-releasing hormone (Gnrh), 17β-estradiol (E 2 ) and 11-ketotestosterone (11-KT) up-regulated gnrhr2bba and lhb , while fshb was up-regulated by Gnrh but down-regulated by 11-KT in pituitaries from immature males. Also pituitaries from maturing males responded to Gnrh and sex steroids by increased gnrhr2bba and lhb transcript levels, but fshb expression remained unchanged. Growth factors (inhibin A, activin A and insulin-like growth factor 1) did not change gnrhr2bba , lhb or fshb transcript levels in pituitaries either from immature or maturing males. Additional pituitary ex vivo studies on candidates identified by RNAseq showed that these transcripts were preferentially regulated by Gnrh and sex steroids, but not by growth factors, and that Gnrh/sex steroids were less effective when incubating pituitaries from maturing males. Our results suggest that a yet to be characterized mechanism up-regulating fshb expression in the salmon pituitary is activated in response to stimulatory environmental conditions prior to morphological signs of testis maturation, and that the transcriptional program associated with this mechanism becomes unresponsive or less responsive to most stimulators ex vivo once males had entered pubertal developmental in vivo .
    Type of Medium: Online Resource
    ISSN: 1664-2392
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.3389/fendo.2022.826920
    DOI: 10.3389/fendo.2022.826920.s001
    DOI: 10.3389/fendo.2022.826920.s002
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2592084-4
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  • 8
    Online Resource
    Online Resource
    Rescue of germ cells in dnd crispant embryos opens the possibility to produce inherited sterility in Atlantic salmon
    Springer Science and Business Media LLC ; 2020
    In:  Scientific Reports Vol. 10, No. 1 ( 2020-10-22)
    Details
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 10, No. 1 ( 2020-10-22)
    Abstract: Genetic introgression of escaped farmed Atlantic salmon ( Salmo salar ) into wild populations is a major environmental concern for the salmon aquaculture industry. Using sterile fish in commercial aquaculture operations is, therefore, a sustainable strategy for bio-containment. So far, the only commercially used methodology for producing sterile fish is triploidization. However, triploid fish are less robust. A novel approach in which to achieve sterility is to produce germ cell-free salmon, which can be accomplished by knocking out the dead-end ( dnd ) gene using CRISPR-Cas9. The lack of germ cells in the resulting dnd crispants, thus, prevents reproduction and inhibits subsequent large-scale production of sterile fish. Here, we report a rescue approach for producing germ cells in Atlantic salmon dnd crispants. To achieve this, we co-injected the wild-type (wt) variant of salmon dnd mRNA together with CRISPR-Cas9 constructs targeting dnd into 1-cell stage embryos. We found that rescued one-year-old fish contained germ cells, type A spermatogonia in males and previtellogenic primary oocytes in females. The method presented here opens a possibility for large-scale production of germ-cell free Atlantic salmon offspring through the genetically sterile broodstock which can pass the sterility trait on the next generation.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    URL: Article
    DOI: 10.1038/s41598-020-74876-2
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2615211-3
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