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Kess T, Lehnert SJ, Bentzen P, Duffy S, Messmer A, Dempson JB, Newport J, Whidden C, Robertson MJ, Chaput G, Breau C, April J, Gillis C, Kent M, Nugent CM, Bradbury IR. Variable parallelism in the genomic basis of age at maturity across spatial scales in Atlantic Salmon. Ecol Evol 2024; 14:e11068. [PMID: 38584771 PMCID: PMC10995719 DOI: 10.1002/ece3.11068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Accepted: 01/31/2024] [Indexed: 04/09/2024] Open
Abstract
Complex traits often exhibit complex underlying genetic architectures resulting from a combination of evolution from standing variation, hard and soft sweeps, and alleles of varying effect size. Increasingly, studies implicate both large-effect loci and polygenic patterns underpinning adaptation, but the extent that common genetic architectures are utilized during repeated adaptation is not well understood. Sea age or age at maturation represents a significant life history trait in Atlantic Salmon (Salmo salar), the genetic basis of which has been studied extensively in European Atlantic populations, with repeated identification of large-effect loci. However, the genetic basis of sea age within North American Atlantic Salmon populations remains unclear, as does the potential for a parallel trans-Atlantic genomic basis to sea age. Here, we used a large single-nucleotide polymorphism (SNP) array and low-coverage whole-genome resequencing to explore the genomic basis of sea age variation in North American Atlantic Salmon. We found significant associations at the gene and SNP level with a large-effect locus (vgll3) previously identified in European populations, indicating genetic parallelism, but found that this pattern varied based on both sex and geographic region. We also identified nonrepeated sets of highly predictive loci associated with sea age among populations and sexes within North America, indicating polygenicity and low rates of genomic parallelism. Despite low genome-wide parallelism, we uncovered a set of conserved molecular pathways associated with sea age that were consistently enriched among comparisons, including calcium signaling, MapK signaling, focal adhesion, and phosphatidylinositol signaling. Together, our results indicate parallelism of the molecular basis of sea age in North American Atlantic Salmon across large-effect genes and molecular pathways despite population-specific patterns of polygenicity. These findings reveal roles for both contingency and repeated adaptation at the molecular level in the evolution of life history variation.
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Affiliation(s)
- Tony Kess
- Northwest Atlantic Fisheries CentreFisheries and Oceans CanadaSt. John'sNewfoundland and LabradorCanada
| | - Sarah J. Lehnert
- Northwest Atlantic Fisheries CentreFisheries and Oceans CanadaSt. John'sNewfoundland and LabradorCanada
| | - Paul Bentzen
- Department of BiologyDalhousie UniversityHalifaxNova ScotiaCanada
| | - Steven Duffy
- Northwest Atlantic Fisheries CentreFisheries and Oceans CanadaSt. John'sNewfoundland and LabradorCanada
| | - Amber Messmer
- Northwest Atlantic Fisheries CentreFisheries and Oceans CanadaSt. John'sNewfoundland and LabradorCanada
| | - J. Brian Dempson
- Northwest Atlantic Fisheries CentreFisheries and Oceans CanadaSt. John'sNewfoundland and LabradorCanada
| | - Jason Newport
- Marine Environmental Research Infrastructure for Data Integration and Application NetworkHalifaxNova ScotiaCanada
| | | | - Martha J. Robertson
- Northwest Atlantic Fisheries CentreFisheries and Oceans CanadaSt. John'sNewfoundland and LabradorCanada
| | - Gerald Chaput
- Fisheries and Oceans CanadaGulf Fisheries CentreMonctonNew BrunswickCanada
| | - Cindy Breau
- Fisheries and Oceans CanadaGulf Fisheries CentreMonctonNew BrunswickCanada
| | - Julien April
- Ministère des Forêts de la Faune et des ParcsQuebecQuebecCanada
| | - Carole‐Anne Gillis
- Gespe'gewa'gi, Mi'gma'qi, ListugujGespe'gewa'gi Institute of Natural UnderstandingQuebecQuebecCanada
| | - Matthew Kent
- Centre for Integrative GeneticsNorwegian University of Life SciencesÅsNorway
| | - Cameron M. Nugent
- Northwest Atlantic Fisheries CentreFisheries and Oceans CanadaSt. John'sNewfoundland and LabradorCanada
| | - Ian R. Bradbury
- Northwest Atlantic Fisheries CentreFisheries and Oceans CanadaSt. John'sNewfoundland and LabradorCanada
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Andersson E, Schulz RW, Almeida F, Kleppe L, Skaftnesmo KO, Kjærner-Semb E, Crespo D, Fjelldal PG, Hansen TJ, Norberg B, Edvardsen RB, Wargelius A. Loss of Fshr Prevents Testicular Maturation in Atlantic Salmon (Salmo salar L.). Endocrinology 2024; 165:bqae013. [PMID: 38298132 PMCID: PMC10878062 DOI: 10.1210/endocr/bqae013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Revised: 01/26/2024] [Accepted: 01/29/2024] [Indexed: 02/02/2024]
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 2 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 with 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.
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Affiliation(s)
- Eva Andersson
- Institute of Marine Research, NO-5817 Bergen, Norway
| | - Rüdiger W Schulz
- Institute of Marine Research, NO-5817 Bergen, Norway
- Science Faculty, Department Biology, Utrecht University, NL-3584 CH Utrecht, The Netherlands
| | | | - Lene Kleppe
- Institute of Marine Research, NO-5817 Bergen, Norway
| | | | | | - Diego Crespo
- Institute of Marine Research, NO-5817 Bergen, Norway
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3
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Moulistanos A, Nikolaou T, Sismanoglou S, Gkagkavouzis K, Karaiskou N, Antonopoulou E, Triantafyllidis A, Papakostas S. Investigating the role of genetic variation in vgll3 and six6 in the domestication of gilthead seabream ( Sparus aurata Linnaeus) and European seabass ( Dicentrarchus labrax Linnaeus). Ecol Evol 2023; 13:e10727. [PMID: 38020694 PMCID: PMC10654472 DOI: 10.1002/ece3.10727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 10/27/2023] [Accepted: 10/27/2023] [Indexed: 12/01/2023] Open
Abstract
Gene function conservation is crucial in molecular ecology, especially for key traits like growth and maturation in teleost fish. The vgll3 and six6 genes are known to influence age-at-maturity in Atlantic salmon, but their impact on other fish species is poorly understood. Here, we investigated the association of vgll3 and six6 in the domestication of gilthead seabream and European seabass, both undergoing selective breeding for growth-related traits in the Mediterranean. We analysed two different sets of samples using two different genotyping approaches. The first dataset comprised farmed and wild populations from Greece, genotyped for SNPs within the two genes ('gene-level genotyping'). The second dataset examined 300-600 k SNPs located in the chromosomes of the two genes, derived from a meta-analysis of a Pool-Seq experiment involving farmed and wild populations distributed widely across the Mediterranean ('chromosome-level genotyping'). The gene-level analysis revealed a statistically significant allele frequency differences between farmed and wild populations on both genes in each species. This finding was partially supported by the chromosome-level analysis, identifying highly differentiated regions may be involved in the domestication process at varying distances from the candidate genes. Noteworthy genomic features were found, such as a CpG island in gilthead seabream and novel candidate genes in European seabass, warranting further investigation. These findings support a putative role of vgll3 and six6 in the maturation and growth of gilthead seabream and European seabass, emphasizing the need for further research on their conserved function.
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Affiliation(s)
- Aristotelis Moulistanos
- Department of Genetics, Development & Molecular Biology, School of Biology, Faculty of ScienceAristotle University of ThessalonikiThessalonikiGreece
- Genomics and Epigenomics Translational Research (GENeTres)Center for Interdisciplinary Research and Innovation (CIRI‐AUTH), Balkan CenterThessalonikiGreece
| | - Theopisti Nikolaou
- Department of Genetics, Development & Molecular Biology, School of Biology, Faculty of ScienceAristotle University of ThessalonikiThessalonikiGreece
| | - Smaragda Sismanoglou
- Department of Genetics, Development & Molecular Biology, School of Biology, Faculty of ScienceAristotle University of ThessalonikiThessalonikiGreece
| | - Konstantinos Gkagkavouzis
- Department of Genetics, Development & Molecular Biology, School of Biology, Faculty of ScienceAristotle University of ThessalonikiThessalonikiGreece
- Genomics and Epigenomics Translational Research (GENeTres)Center for Interdisciplinary Research and Innovation (CIRI‐AUTH), Balkan CenterThessalonikiGreece
| | - Nikoleta Karaiskou
- Department of Genetics, Development & Molecular Biology, School of Biology, Faculty of ScienceAristotle University of ThessalonikiThessalonikiGreece
- Genomics and Epigenomics Translational Research (GENeTres)Center for Interdisciplinary Research and Innovation (CIRI‐AUTH), Balkan CenterThessalonikiGreece
| | - Efthimia Antonopoulou
- Department of Zoology, School of BiologyAristotle University of ThessalonikiThessalonikiGreece
| | - Alexandros Triantafyllidis
- Department of Genetics, Development & Molecular Biology, School of Biology, Faculty of ScienceAristotle University of ThessalonikiThessalonikiGreece
- Genomics and Epigenomics Translational Research (GENeTres)Center for Interdisciplinary Research and Innovation (CIRI‐AUTH), Balkan CenterThessalonikiGreece
| | - Spiros Papakostas
- Department of Science and TechnologyInternational Hellenic UniversityThessalonikiGreece
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F. L A, K. O S, E A, L K, R. B E, B N, P. G F, T. J H, R. W S, A W. The Piwil1 N domain is required for germ cell survival in Atlantic salmon. Front Cell Dev Biol 2022; 10:977779. [PMID: 36200047 PMCID: PMC9527287 DOI: 10.3389/fcell.2022.977779] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/22/2022] [Indexed: 11/13/2022] Open
Abstract
Genetic introgression of farmed salmon into wild populations can damage the genetic integrity of wild stocks and is therefore considered as an environmental threat. One possible solution is to induce sterility in farmed salmon. We have searched for proteins potentially essential for germline survival in Atlantic salmon. One of these is the argonaute protein Piwil1, known to be required for germ cell survival. To examine Piwil1 function in salmon, we induced indels in the N domain by CRISPR-Cas9. The encoded domain is present in all vertebrate Piwi proteins and has been linked to Tdrd1 protein interaction and PAZ lobe structure. The F0 founder generation of piwil1 crispant males and females displayed a mosaic pattern of piwil1 mutations, exhibiting highly mutated alleles (53%–97%) in their fin gDNA samples. In general, piwil1 crispants carried germ cells, went through puberty and became fertile, although a transient and partial germ cell loss and delays during the spermatogenic process were observed in many male crispants, suggesting that Piwil1 functions during salmon spermatogenesis. By crossing highly mutated F0 founders, we produced F1 fish with a mixture of: loss-of-function alleles (−); functional in frame mutated alleles (+) and wt alleles (+). In F1, all piwil1−/− fish lacked germ cells, while piwil1+/+ siblings showed normal ovaries and testes. Yet, most juvenile F1 piwil1+/−males and females displayed an intermediate phenotype with a higher somatic/germ cell ratio without an increase in germ cell apoptosis, suggestive of a gene dose effect on the number of germ cells and/or insufficient replacement of lost germ cells in heterozygous fish. Interestingly, the two longest in-frame indels in the N domain also ensured germ cell loss. Hence, the loss of 4–6 aa in this region Phe130-Ser136 may result in crucial changes of the protein structure, potentially affecting piRNA binding of the PAZ lobe, and/or affecting the binding of Piwil1 interacting proteins such as Tdrd protein, with critical consequences for the survival of primordial germ cells. In conclusion, we show that loss of piwil1 leads to loss of germ cells in salmon and that part of the N domain of Piwil1 is crucial for its function.
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Affiliation(s)
- Almeida F. L
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
- Embrapa Amazonia Ocidental, Manaus, Brazil
- *Correspondence: Almeida F. L,
| | - Skaftnesmo K. O
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Andersson E
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Kleppe L
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Edvardsen R. B
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Norberg B
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Fjelldal P. G
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Hansen T. J
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
| | - Schulz R. W
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
- Reproductive Biology Group, Department Biology, Science Faculty, Utrecht University, Utrecht, Netherlands
| | - Wargelius A
- Research Group Reproduction and Developmental Biology, Institute of Marine Research, Bergen, Norway
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5
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Debes PV, Piavchenko N, Ruokolainen A, Ovaskainen O, Moustakas-Verho JE, Parre N, Aykanat T, Erkinaro J, Primmer CR. Polygenic and major-locus contributions to sexual maturation timing in Atlantic salmon. Mol Ecol 2021; 30:4505-4519. [PMID: 34228841 DOI: 10.1111/mec.16062] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 06/16/2021] [Accepted: 07/01/2021] [Indexed: 12/13/2022]
Abstract
Sexual maturation timing is a life-history trait central to the balance between mortality and reproduction. Maturation may be triggered when an underlying compound trait, called liability, exceeds a threshold. In many different species and especially fishes, this liability is approximated by growth and body condition. However, environmental vs. genetic contributions either directly or via growth and body condition to maturation timing remain unclear. Uncertainty exists also because the maturation process can reverse this causality and itself affect growth and body condition. In addition, disentangling the contributions of polygenic and major loci can be important. In many fishes, males mature before females, enabling the study of associations between male maturation and maturation-unbiased female liability traits. Using 40 Atlantic salmon families, longitudinal common-garden experimentation, and quantitative genetic analyses, we disentangled environmental from polygenic and major locus (vgll3) effects on male maturation, and sex-specific growth and condition. We detected polygenic heritabilities for maturation, growth, and body condition, and vgll3 effects on maturation and body condition but not on growth. Longitudinal patterns for sex-specific phenotypic liability, and for genetic variances and correlations between sexes suggested that early growth and condition indeed positively affected maturation initiation. However, towards spawning time, causality appeared reversed for males whereby maturation affected growth negatively and condition positively via both the environmental and genetic effects. Altogether, the results indicate that growth and condition are useful traits to study liability for maturation initiation, but only until maturation alters their expression, and that vgll3 contributes to maturation initiation via condition.
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Affiliation(s)
- Paul V Debes
- Organismal & Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences / Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE, University of Helsinki, Helsinki, Finland
| | - Nikolai Piavchenko
- Organismal & Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences / Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE, University of Helsinki, Helsinki, Finland
| | - Annukka Ruokolainen
- Organismal & Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences / Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE, University of Helsinki, Helsinki, Finland
| | - Outi Ovaskainen
- Organismal & Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences / Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE, University of Helsinki, Helsinki, Finland
| | - Jacqueline E Moustakas-Verho
- Organismal & Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences / Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE, University of Helsinki, Helsinki, Finland
| | - Noora Parre
- Organismal & Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences / Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE, University of Helsinki, Helsinki, Finland
| | - Tutku Aykanat
- Organismal & Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences / Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE, University of Helsinki, Helsinki, Finland
| | | | - Craig R Primmer
- Organismal & Evolutionary Biology Research Program, Faculty of Biological and Environmental Sciences / Institute of Biotechnology, Helsinki Institute of Life Science (HiLIFE, University of Helsinki, Helsinki, Finland
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6
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Waters CD, Clemento A, Aykanat T, Garza JC, Naish KA, Narum S, Primmer CR. Heterogeneous genetic basis of age at maturity in salmonid fishes. Mol Ecol 2021; 30:1435-1456. [PMID: 33527498 DOI: 10.1111/mec.15822] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/07/2020] [Accepted: 01/11/2021] [Indexed: 12/12/2022]
Abstract
Understanding the genetic basis of repeated evolution of the same phenotype across taxa is a fundamental aim in evolutionary biology and has applications in conservation and management. However, the extent to which interspecific life-history trait polymorphisms share evolutionary pathways remains underexplored. Here, we address this gap by studying the genetic basis of a key life-history trait, age at maturity, in four species of Pacific salmonids (genus Oncorhynchus) that exhibit intra- and interspecific variation in this trait-Chinook Salmon, Coho Salmon, Sockeye Salmon, and Steelhead Trout. We tested for associations in all four species between age at maturity and two genome regions, six6 and vgll3, that are strongly associated with the same trait in Atlantic Salmon (Salmo salar). We also conducted a genome-wide association analysis in Steelhead to assess whether additional regions were associated with this trait. We found the genetic basis of age at maturity to be heterogeneous across salmonid species. Significant associations between six6 and age at maturity were observed in two of the four species, Sockeye and Steelhead, with the association in Steelhead being particularly strong in both sexes (p = 4.46 × 10-9 after adjusting for genomic inflation). However, no significant associations were detected between age at maturity and the vgll3 genome region in any of the species, despite its strong association with the same trait in Atlantic Salmon. We discuss possible explanations for the heterogeneous nature of the genetic architecture of this key life-history trait, as well as the implications of our findings for conservation and management.
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Affiliation(s)
- Charles D Waters
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA
| | - Anthony Clemento
- Institute of Marine Sciences, University of California, Santa Cruz, CA, USA.,Santa Cruz Laboratory, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Santa Cruz, CA, USA
| | - Tutku Aykanat
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland
| | - John Carlos Garza
- Institute of Marine Sciences, University of California, Santa Cruz, CA, USA.,Santa Cruz Laboratory, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Santa Cruz, CA, USA
| | - Kerry A Naish
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA
| | - Shawn Narum
- Hagerman Genetics Laboratory, Columbia River Inter-Tribal Fish Commission, Hagerman, ID, USA
| | - Craig R Primmer
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland.,Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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7
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Fjelldal PG, Hansen TJ, Wargelius A, Ayllon F, Glover KA, Schulz RW, Fraser TWK. Development of supermale and all-male Atlantic salmon to research the vgll3 allele - puberty link. BMC Genet 2020; 21:123. [PMID: 33183224 PMCID: PMC7664053 DOI: 10.1186/s12863-020-00927-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/27/2020] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Farmed Atlantic salmon are one of the most economically significant global aquaculture products. Early sexual maturation of farmed males represents a significant challenge to this industry and has been linked with the vgll3 genotype. However, tools to aid research of this topic, such as all-male and clonal fish, are still lacking. The present 6-year study examined if all-male production is possible in Atlantic salmon, a species with heteromorphic sex chromosomes (males being XY, females XX), and if all-male fish can be applied to further explore the vgll3 contribution on the likelihood of early maturation. RESULTS Estrogen treatment of mixed sex yolk sac larvae gave rise to one sexually mature hermaphrodite with a male genotype (XY) that was used to produce both self-fertilized offspring and androgenetic double haploid (dh) offspring following egg activation with UV treated sperm and pressure shock to block the first mitotic division. There were YY supermales among both offspring types, which were crossed with dh females. Between 1 and 8% of the putative all-male offspring from the eight crosses with self-fertilized supermales were found to have ovaries, and 95% of these phenotypic females were also genetically female. None of the offspring from the one dh supermale cross had ovaries. When assessing the general contribution of the vgll3 locus on the likelihood of early post-smolt sexual maturation (jacking) in the all-male populations we found individuals that were homozygous for the early maturing genotype (97%) were more likely to enter puberty than individuals that were homozygous for the late maturing genotype (26%). However, the likelihood of jacking within individuals with an early/late heterozygous genotype was higher when the early allele came from the dam (94%) compared to the sire (45%). CONCLUSIONS The present results show that supermale Atlantic salmon are viable and fertile and can be used as a research tool to study important aspects of sexual maturation, such as to further explore the sex dependent parental genetic contribution to age at puberty in Atlantic salmon. In addition, we report the production of viable double haploid supermale fish.
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Affiliation(s)
- Per Gunnar Fjelldal
- Institute of Marine Research (IMR), Matre Aquaculture Research Station, 5984 Matredal, Norway
| | - Tom J. Hansen
- Institute of Marine Research (IMR), Matre Aquaculture Research Station, 5984 Matredal, Norway
| | - Anna Wargelius
- Institute of Marine Research (IMR), PO Box 1870, Nordnes, 5817 Bergen, Norway
| | - Fernando Ayllon
- Institute of Marine Research (IMR), PO Box 1870, Nordnes, 5817 Bergen, Norway
| | - Kevin A. Glover
- Institute of Marine Research (IMR), PO Box 1870, Nordnes, 5817 Bergen, Norway
| | - Rüdiger W. Schulz
- Reproductive Biology Group, Division Developmental Biology, Department of Biology, Faculty of Sciences, Utrecht University, Utrecht, The Netherlands
| | - Thomas W. K. Fraser
- Institute of Marine Research (IMR), Matre Aquaculture Research Station, 5984 Matredal, Norway
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8
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Güralp H, Skaftnesmo KO, Kjærner-Semb E, Straume AH, Kleppe L, Schulz RW, Edvardsen RB, Wargelius A. Rescue of germ cells in dnd crispant embryos opens the possibility to produce inherited sterility in Atlantic salmon. Sci Rep 2020; 10:18042. [PMID: 33093479 DOI: 10.1038/s41598-020-74876-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 10/07/2020] [Indexed: 11/12/2022] Open
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.
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9
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Ayllon F, Solberg MF, Besnier F, Fjelldal PG, Hansen TJ, Wargelius A, Edvardsen RB, Glover KA. Autosomal sdY Pseudogenes Explain Discordances Between Phenotypic Sex and DNA Marker for Sex Identification in Atlantic Salmon. Front Genet 2020; 11:544207. [PMID: 33173531 PMCID: PMC7591749 DOI: 10.3389/fgene.2020.544207] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 09/17/2020] [Indexed: 11/13/2022] Open
Abstract
Despite the key role that sex-determination plays in evolutionary processes, it is still poorly understood in many species. In salmonids, which are among the best studied fishes, the master sex-determining gene sexually dimorphic on the Y-chromosome (sdY) has been identified. However, sdY displays unexplained discordance to the phenotypic sex, with a variable frequency of phenotypic females being reported as genetic males. Multiple sex determining loci in Atlantic salmon have also been reported, possibly as a result of recent transposition events in this species. We hypothesized the existence of an autosomal copy of sdY, causing apparent discordance between phenotypic and genetic sex, that is transmitted in accordance with autosomal inheritance. To test this, we developed a qPCR methodology to detect the total number of sdY copies present in the genome. Based on the observed phenotype/genotype frequencies and linkage analysis among 2,025 offspring from 64 pedigree-controlled families of accurately phenotyped Atlantic salmon, we identified both males and females carrying one or two autosomal copies of sdY in addition to the Y-specific copy present in males. Patterns across families were highly consistent with autosomal inheritance. These autosomal sdY copies appear to have lost the ability to function as a sex determining gene and were only occasionally assigned to the actual sex chromosome in any of the affected families.
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Affiliation(s)
| | | | | | | | | | | | | | - Kevin Alan Glover
- Institute of Marine Research, Bergen, Norway.,Department of Biological Sciences, University of Bergen, Bergen, Norway
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Brown MS, Evans BS, Afonso LOB. Discordance for genotypic sex in phenotypic female Atlantic salmon (Salmo salar) is related to a reduced sdY copy number. Sci Rep 2020; 10:9651. [PMID: 32541863 PMCID: PMC7296011 DOI: 10.1038/s41598-020-66406-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 05/18/2020] [Indexed: 11/10/2022] Open
Abstract
The master sex determinant in rainbow trout (Oncorhynchus mykiss), sexually dimorphic on the Y chromosome (sdY), is strongly but not perfectly associated with male phenotype in several other species from the family Salmonidae. Currently, the cause and implications of discordance for sdY-predicted genotypic sex and phenotypic sex in these species is unclear. Using an established multiplex PCR test for exons 2 and 3 of sdY, we demonstrated that sdY-predicted genotypic sex was discordant with histologically evidenced phenotypic sex in 4% of 176 Tasmanian Atlantic salmon. All discordant individuals were phenotypic females presenting a male genotype. Using real-time qPCR assays that we developed and validated for exons 2, 3 and 4 of sdY, all genotype-phenotype discordant females were confirmed to possess sdY, albeit at a reduced number of copies when compared to phenotypic males. The real-time qPCR assays also demonstrated reduced levels of sdY in 30% of phenotypic females that the established multiplex PCR-based test indicated to be devoid of sdY. These findings suggest sdY may be reduced in copy number or mosaicked in the genomic DNA of sdY-positive phenotypic female Atlantic salmon and highlight the importance of understanding the effects of reduced sdY copies on the development of phenotypic sex.
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Affiliation(s)
- Morgan S Brown
- School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University Warrnambool Campus, Warrnambool, Victoria, 3280, Australia
| | - Brad S Evans
- Breeding & Research, Tassal Operations, Hobart, Tasmania, 7000, Australia
| | - Luis O B Afonso
- School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University Warrnambool Campus, Warrnambool, Victoria, 3280, Australia.
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Kurko J, Debes PV, House AH, Aykanat T, Erkinaro J, Primmer CR. Transcription Profiles of Age-at-Maturity-Associated Genes Suggest Cell Fate Commitment Regulation as a Key Factor in the Atlantic Salmon Maturation Process. G3 (Bethesda) 2020; 10:235-46. [PMID: 31740454 DOI: 10.1534/g3.119.400882] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Despite recent taxonomic diversification in studies linking genotype with phenotype, follow-up studies aimed at understanding the molecular processes of such genotype-phenotype associations remain rare. The age at which an individual reaches sexual maturity is an important fitness trait in many wild species. However, the molecular mechanisms regulating maturation timing processes remain obscure. A recent genome-wide association study in Atlantic salmon (Salmo salar) identified large-effect age-at-maturity-associated chromosomal regions including genes vgll3, akap11 and six6, which have roles in adipogenesis, spermatogenesis and the hypothalamic-pituitary-gonadal (HPG) axis, respectively. Here, we determine expression patterns of these genes during salmon development and their potential molecular partners and pathways. Using Nanostring transcription profiling technology, we show development- and tissue-specific mRNA expression patterns for vgll3, akap11 and six6. Correlated expression levels of vgll3 and akap11, which have adjacent chromosomal location, suggests they may have shared regulation. Further, vgll3 correlating with arhgap6 and yap1, and akap11 with lats1 and yap1 suggests that Vgll3 and Akap11 take part in actin cytoskeleton regulation. Tissue-specific expression results indicate that vgll3 and akap11 paralogs have sex-dependent expression patterns in gonads. Moreover, six6 correlating with slc38a6 and rtn1, and Hippo signaling genes suggests that Six6 could have a broader role in the HPG neuroendrocrine and cell fate commitment regulation, respectively. We conclude that Vgll3, Akap11 and Six6 may influence Atlantic salmon maturation timing via affecting adipogenesis and gametogenesis by regulating cell fate commitment and the HPG axis. These results may help to unravel general molecular mechanisms behind maturation.
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