Sex Determination and Sex Control in Salmonidae

The rise and fall of the ancient northern pike master sex-determining gene

“…It was proposed that in these organisms, the turnover of sex chromosomes was facilitated by autosomes that host genes involved in sex differentiation pathways that could be readily recruited as new MSD genes, facilitating turnovers of sex chromosomes ( Vicoso, 2019 ). Alternative evolutionary pathways could also involve conserved MSD genes that translocate onto different autosomes, as demonstrated for the salmonid sdY gene ( Guiguen et al, 2018 ). Interestingly, this scenario does not seem to be the case with Esocidae.…”

“…The majority of these recently discovered MSD genes, however, were phylogenetically scattered, making it challenging to infer evolutionary patterns and conserved themes of sex chromosomes and/or MSD gene turnovers. Although comparative studies have been accomplished in medakas, poeciliids, tilapiine cichlids, salmonids, and sticklebacks ( Kikuchi and Hamaguchi, 2013 ), transitions of SD systems in relation to the fate of known MSD genes within closely related species have only been explored in medakas ( Myosho et al, 2015 ) and salmonids ( Guiguen et al, 2018 ).…”

Characteristics and Cryopreservation of Semen of Sex-Reversed Females of Salmonid Fish

“…Therefore, indirect feminisation was found to be superior and is now a commonly used in hatchery practice. Major androgens that are being used for female masculinisation include synthetic 17 α-methyltestosterone (MT) and 17 α-methyldihydrotestosterone (MDHT), which represent aromatisable and nonaromatisable androgens, respectively [ 20 , 21 ]. Another important androgen used under practical hatchery conditions is naturally occurring 17 β-hydroxyandrostenedione (OHA).…”

“…The selection of the applied method is often clearly related to the labile period for particular species; immersion is preferred when sexual differentiation occurs during the embryonic or larval stages, whereas the dietary treatment is suited for species with differentiation during and/or after the initiation of larval feeding [ 13 ]. It also needs to be considered that steroids concentrations may decrease with storage time, especially at room temperature [ 21 , 40 ]. Optimising the dose and duration of treatment with masculinising agents is of the utmost importance; too-low concentrations may be ineffective (however, it may be useful for the production of functional males [ 38 ]), whereas too high doses often have a so called “paradoxical feminisation” or a sterilising effect [ 1 , 41 , 42 ].…”

“…The problem occurs when the normal population is subjected to masculinisation and the sampling of genetic males is probable. The practical strategy in such a case is focused on the production of non-functional SRFs with easily identified phenotypes, such as hermaphrodites or males without spermatic ducts [ 21 , 45 , 46 ]. This would ensure that SRF population have the XX genotype and are not mixed with individuals presenting the XY genotype.…”