Autosomal sdY Pseudogenes Explain Discordances Between Phenotypic Sex and DNA Marker for Sex Identification in Atlantic Salmon

Ayllón, Fernando; Solberg, Monica Favnebøe; Besnier, François; Fjelldal, Per Gunnar; Hansen, Tom; Wargelius, Anna; Edvardsen, Rolf B.; Glover, Kevin A.

doi:10.3389/fgene.2020.544207

Cited by 18 publications

(26 citation statements)

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“…Similar to our findings, selffertilization of mature hermaphrodites has been recorded in estrogen treated rainbow trout, with 76.6% male offspring, suggesting viability of the YY genotype [24]. The YY genotype was confirmed among the offspring of the Golden Fish using a recently developed qPCR method [32], which confirmed 25% YY, 50% XY and 25% XX genotype distribution among the offspring from the selffertilization. Thus, the Golden Fish had a 1:1 ratio of X and Y eggs and sperm.…”

Section: Neo-female and Supermale Productionsupporting

confidence: 90%

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Development of supermale and all-male Atlantic salmon to research the vgll3 allele - puberty link

et al. 2020

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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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Section: Neo-female and Supermale Productionsupporting

confidence: 90%

“…PCR products were visualized in 3% agarose gels. For distinguishing between XY and YY males we used the method recently described by [32].…”

Section: Genotypinggenetic Background/variation Sex and Vgll3mentioning

confidence: 99%

Development of supermale and all-male Atlantic salmon to research the vgll3 allele - puberty link

et al. 2020

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“…2012, 2013; Ayllon et al. 2020). Our results support this suggestion, as we found that the Rainbow Trout primer did not produce polymorphic bands in Brook Trout.…”

Section: Discussionmentioning

confidence: 99%

A Nonlethal Genetic Assay for Discriminating Sex in Brook Trout

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et al. 2021

N American J Fish Manag

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Identifying sex in salmonids using nonlethal methods is valuable for controlled breeding in aquaculture and understanding behavior and dispersal for conservation. Although salmonids are male heterogametic, genetic sex identification has been problematic because a specific sex determination locus has been elusive. We implemented a blind analysis to identify sex in Brook Trout Salvelinus fontinalis using genetic primers (sdY) developed for Brown Trout Salmo trutta along with cytochrome c oxidase subunit I (COI_BT1) as an internal control. Fin clips were taken from 35 Brook Trout and analyzed via PCR and gel electrophoresis, and fish were simultaneously sacrificed and dissected to identify sex via gonads. The genetic and phenotypic analysis matched in 97% of the Brook Trout that were sampled, suggesting that this primer combination is successful in genetic sex determination. The ability to sex Brook Trout genetically will allow scientists to observe the difference in male and female Brook Trout behavior in the lab and natural stream ecosystems without using lethal methods.

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“…The third multiplex included the sex-specific markers, Exon 2 and Exon 4 [ 55 ] from the sdY sequence, a male-specific-Y-chromosome gene that is highly conserved in salmonids [ 56 ]. Although not always 100% accurate, due to the occasional occurrence of autosomal pseudocopies of sdY , at least in brown trout´s closest relative, Atlantic salmon [ 57 ], this provides more accurate sexing than phenotypic sex as morphological dimorphism can be difficult to ascertain in the field [ 58 ]. PCR was conducted using a Verity 96 well thermal cycler and GeneAmp PCR system 9700 (Applied Biosystems).…”

Section: Methodsmentioning

confidence: 99%

Long-term monitoring of a brown trout (Salmo trutta) population reveals kin-associated migration patterns and contributions by resident trout to the anadromous run

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Background In species showing partial migration, as is the case for many salmonid fishes, it is important to assess how anthropogenic pressure experienced by migrating individuals affects the total population. We focused on brown trout (Salmo trutta) from the Guddal River in the Norwegian Hardanger Fjord system, which encompasses both resident and anadromous individuals. Aquaculture has led to increased anthropogenic pressure on brown trout during the marine phase in this region. Fish traps in the Guddal River allow for sampling all ascending anadromous spawners and descending smolts. We analyzed microsatellite DNA markers from all individuals ascending in 2006–2016, along with all emigrating smolts in 2017. We investigated (1) if there was evidence for declines in census numbers and effective population size during that period, (2) if there was association between kinship and migration timing in smolts and anadromous adults, and (3) to what extent resident trout were parents of outmigrating smolts. Results Census counts of anadromous spawners showed no evidence for a decline from 2006 to 2016, but were lower than in 2000–2005. Estimates of effective population size also showed no trends of declines during the study period. Sibship reconstruction of the 2017 smolt run showed significant association between kinship and migration timing, and a similar association was indicated in anadromous spawners. Parentage assignment of 2017 smolts with ascending anadromous trout as candidate parents, and assuming that unknown parents represented resident trout, showed that 70% of smolts had at least one resident parent and 24% had two resident parents. Conclusions The results bear evidence of a population that after an initial decline has stabilized at a lower number of anadromous spawners. The significant association between kinship and migration timing in smolts suggests that specific episodes of elevated mortality in the sea could disproportionally affect some families and reduce overall effective population size. Finally, the results based on parentage assignment demonstrate a strong buffering effect of resident trout in case of elevated marine mortality affecting anadromous trout, but also highlight that increased mortality of anadromous trout, most of which are females, may lower overall production in the system.

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Autosomal sdY Pseudogenes Explain Discordances Between Phenotypic Sex and DNA Marker for Sex Identification in Atlantic Salmon

Cited by 18 publications

References 50 publications

Development of supermale and all-male Atlantic salmon to research the vgll3 allele - puberty link

Development of supermale and all-male Atlantic salmon to research the vgll3 allele - puberty link

A Nonlethal Genetic Assay for Discriminating Sex in Brook Trout

Long-term monitoring of a brown trout (Salmo trutta) population reveals kin-associated migration patterns and contributions by resident trout to the anadromous run

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