Omic Study and Genes in Fish Sex Determination and Differentiation

A special issue of Genes (ISSN 2073-4425). This special issue belongs to the section "Animal Genetics and Genomics".

Deadline for manuscript submissions: closed (15 June 2024) | Viewed by 1302

Special Issue Editors

Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences (CAFS), Qingdao 266071, China
Interests: sex determination; sex differentiation; sex reversal; spermatogenesis; post-translational modification
Fisheries College, Jimei University, Xiamen 361021, China
Interests: genomics; sex determination in fish; chromosome evolution

Special Issue Information

Dear Colleagues, 

More than 30,000 species of fish have been identified, constituting the largest and most diverse group of vertebrates. Sex determination could be modulated both by genetic and external factors, and fish display the most versatile mechanisms among vertebrates. Unlike the conservation of the sex-determining gene SRY in mammals, a series of sex-determining genes have been identified in fish including dmrt1, dmy, amhy, sdY, gsdf etc. In sex differentiation, a range of the gonadal differentiation types have been described in fish, including gonochorism, sequential hermaphroditism that can initially mature either as males (protandrous) or females (protogynous), and simultaneous hermaphroditism. The diversity of sex determination and differentiation in fish provides an ideal opportunity to understand the formation and maintenance of sexes at the evolutionary level. In addition, studying sex determination and differentiation in fish is practical in aquaculture because of the potential benefits of monosex production, providing higher growth rates due to the prevailing sexual size dimorphism. Our Special Issue will mainly focus on omic and gene studies in both sex determination and differentiation in fish, including but not limited to the exploitation of gene resources through omic approaches, functional studies of genes, as well as genetic or epigenetic regulatory mechanisms. Research papers, short communications, and conceptual reviews are all welcome.

Dr. Wenteng Xu
Dr. Wanbo Li
Guest Editors

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Keywords

  • sex determination
  • sex differentiation
  • gametogenesis
  • genomics
  • chromosome evolution
  • post-translational modification

Published Papers (2 papers)

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Research

16 pages, 8437 KiB  
Article
Characteristics of the Vasa Gene in Silurus asotus and Its Expression Response to Letrozole Treatment
by Miao Yu, Fangyuan Wang, Muzi Li, Yuan Wang, Xiangzhe Gao, Hanhan Zhang, Zhenzhu Liu, Zhicheng Zhou, Daoquan Zhao, Meng Zhang, Lei Wang, Hongxia Jiang and Zhigang Qiao
Genes 2024, 15(6), 756; https://doi.org/10.3390/genes15060756 - 8 Jun 2024
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Abstract
The identification and expression of germ cells are important for studying sex-related mechanisms in fish. The vasa gene, encoding an ATP-dependent RNA helicase, is recognized as a molecular marker of germ cells and plays a crucial role in germ cell development. Silurus asotus [...] Read more.
The identification and expression of germ cells are important for studying sex-related mechanisms in fish. The vasa gene, encoding an ATP-dependent RNA helicase, is recognized as a molecular marker of germ cells and plays a crucial role in germ cell development. Silurus asotus, an important freshwater economic fish species in China, shows significant sex dimorphism with the female growing faster than the male. However, the molecular mechanisms underlying these sex differences especially involving in the vasa gene in this fish remain poorly understood. In this work, the vasa gene sequence of S. asotus (named as Savasa) was obtained through RT-PCR and rapid amplification of cDNA end (RACE), and its expression in embryos and tissues was analyzed using qRT-PCR and an in situ hybridization method. Letrozole (LT) treatment on the larvae fish was also conducted to investigate its influence on the gene. The results revealed that the open reading frame (ORF) of Savasa was 1989 bp, encoding 662 amino acids. The SaVasa protein contains 10 conserved domains unique to the DEAD-box protein family, showing the highest sequence identity of 95.92% with that of Silurus meridionalis. In embryos, Savasa is highly expressed from the two-cell stage to the blastula stage in early embryos, with a gradually decreasing trend from the gastrula stage to the heart-beating stage. Furthermore, Savasa was initially detected at the end of the cleavage furrow during the two-cell stage, later condensing into four symmetrical cell clusters with embryonic development. At the gastrula stage, Savasa-positive cells increased and began to migrate towards the dorsal side of the embryo. In tissues, Savasa is predominantly expressed in the ovaries, with almost no or lower expression in other detected tissues. Moreover, Savasa was expressed in phase I–V oocytes in the ovaries, as well as in spermatogonia and spermatocytes in the testis, implying a specific expression pattern of germ cells. In addition, LT significantly upregulated the expression of Savasa in a concentration-dependent manner during the key gonadal differentiation period of the fish. Notably, at 120 dph after LT treatment, Savasa expression was the lowest in the testis and ovary of the high concentration group. Collectively, findings from gene structure, protein sequence, phylogenetic analysis, RNA expression patterns, and response to LT suggest that Savasa is maternally inherited with conserved features, serving as a potential marker gene for germ cells in S.asotus, and might participate in LT-induced early embryonic development and gonadal development processes of the fish. This would provide a basis for further research on the application of germ cell markers and the molecular mechanisms of sex differences in S. asotus. Full article
(This article belongs to the Special Issue Omic Study and Genes in Fish Sex Determination and Differentiation)
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15 pages, 4288 KiB  
Article
Molecular and Physiological Effects of 17α-methyltestosterone on Sex Differentiation of Black Rockfish, Sebastes schlegelii
by Haijun Huang, Yuyan Liu, Qian Wang, Caichao Dong, Le Dong, Jingjing Zhang, Yu Yang, Xiancai Hao, Weijing Li, Ivana F. Rosa, Lucas B. Doretto, Xuebin Cao and Changwei Shao
Genes 2024, 15(5), 605; https://doi.org/10.3390/genes15050605 - 9 May 2024
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Abstract
It is widely known that all-female fish production holds economic value for aquaculture. Sebastes schlegelii, a preeminent economic species, exhibits a sex dimorphism, with females surpassing males in growth. In this regard, achieving all-female black rockfish production could significantly enhance breeding profitability. [...] Read more.
It is widely known that all-female fish production holds economic value for aquaculture. Sebastes schlegelii, a preeminent economic species, exhibits a sex dimorphism, with females surpassing males in growth. In this regard, achieving all-female black rockfish production could significantly enhance breeding profitability. In this study, we utilized the widely used male sex-regulating hormone, 17α-methyltestosterone (MT) at three different concentrations (20, 40, and 60 ppm), to produce pseudomales of S. schlegelii for subsequent all-female offspring breeding. Long-term MT administration severely inhibits the growth of S. schlegelii, while short term had no significant impact. Histological analysis confirmed sex reversal at all MT concentrations; however, both medium and higher MT concentrations impaired testis development. MT also influenced sex steroid hormone levels in pseudomales, suppressing E2 while increasing T and 11-KT levels. In addition, a transcriptome analysis revealed that MT down-regulated ovarian-related genes (cyp19a1a and foxl2) while up-regulating male-related genes (amh) in pseudomales. Furthermore, MT modulated the TGF-β signaling and steroid hormone biosynthesis pathways, indicating its crucial role in S. schlegelii sex differentiation. Therefore, the current study provides a method for achieving sexual reversal using MT in S. schlegelii and offers an initial insight into the underlying mechanism of sexual reversal in this species. Full article
(This article belongs to the Special Issue Omic Study and Genes in Fish Sex Determination and Differentiation)
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