Review: Molecular mechanisms of sex differentiation in sturgeons

Abstract

Sex determination is a complex process, especially in fish where multiple models of sex determination can be identified. The fate of differentiating gonads may depend on species genetics, environmental or behavioural factors. In the case of the sturgeon, sex determination is most likely of genetic origin and is characterized by a ZW female heterogametic system. However, molecular mechanisms of sex development and differentiation in sturgeons are poorly understood. Due to the lack of sexual dimorphism and a long period of maturation combined with invaluable caviar obtained from sturgeons, plenty of research revolving around discovering master sex‐determining gene has been done. Yet, despite numerous studies utilizing multiple approaches and techniques to find key genes involved in sex differentiation, no master sex‐determining genes were identified in sturgeons. Nevertheless, the latest research provided a great deal of data regarding the expression of genes commonly related with sex development and differentiation in vertebrates. Several of these genes were found to be connected with the same processes in sturgeons. This review attempts to summarize research into the expression of genes involved in sex differentiation and development in sturgeons.

A 180 Myr-old female-specific genome region in sturgeon reveals the oldest known vertebrate sex determining system with undifferentiated sex chromosomes

“…We have discovered a female-specific (W) region, consistent with a potential ZZ/ZW system in sturgeon. This finding is in accordance with previous assumptions or indirect evidence that sturgeons exhibit a female-heterogametic sex determination system [ 36 , 48 , 49 ]. This genomic region is conserved in at least six sturgeon species, spanning the entire phylogenetic tree, represented by the most divergent species A. sturio, A. oxyrinchus , A. ruthenus and H. huso , all of which are formally ancient tetraploid (approx.…”

“…The search for a sex chromosome or sex-linked markers in sturgeons has been unsuccessful for a long time [ 36 , 48 , 49 ]. We discuss four major challenges, why this has been the case.…”

A 180 My-old female-specific genome region in sturgeon reveals the oldest known vertebrate sex determining system with undifferentiated sex chromosomes

“…We have discovered a female-specific (W) region, consistent with a potential ZZ/ZW system in sturgeon. This finding is in accordance with previous assumptions or indirect evidence that sturgeons exhibit a female-heterogametic sex determination system [37,49–50]. This genomic region is conserved in at least six sturgeon species, spanning the entire phylogenetic tree from the basal branches ( A. sturio, A. oxyrinchus ) to the tips ( A. ruthenus, H. huso ), all of which are formally ancient tetraploid (~120 chromosomes) [33].…”

“…The search for a sex chromosome or sex-linked markers in sturgeons has not been successful for a long time [37,49–50]. We discuss four major challenges, why this has been the case.…”

Histological Evaluation of Gonad Impairments in Russian Sturgeon (Acipenser gueldenstaedtii) Reared in Recirculating Aquatic System (RAS)

“…The abovementioned potential causes of the observed gonadal pathologies in the analyzed sturgeon do not exhaust the topic, as there is a wide spectrum of genetic and environmental factors that can affect gonadal development, leading to the observed gonadal impairments. The identification of the potential ones is a particularly difficult task, especially due to the fact that sex determination mechanisms in sturgeons are still insufficiently recognized [ 75 ]. Sturgeon RAS farming has many advantages; however, particular emphasis should be placed on proper sturgeon gonadal development under RAS conditions, as disturbed gonadal development or differentiation can lead to a decline in fish reproduction capacity.…”