Sex Determination and Differentiation in Aquatic Animals

A special issue of Animals (ISSN 2076-2615). This special issue belongs to the section "Aquatic Animals".

Deadline for manuscript submissions: 15 December 2025 | Viewed by 3180

Special Issue Editors

Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
Interests: aquatic animal; sex change; molecular mechanism; application
Special Issues, Collections and Topics in MDPI journals
College of Fisheries, Southwest University, No. 2, Tiansheng Road, Chongqing 400715, China
Interests: genetics and breeding of aquatic organisms; reproduction and development of aquatic organisms; fundamentals of aquatic sciences

Special Issue Information

Dear Colleagues,

Sex determination and differentiation are important developmental events in the life cycle of all sexually reproducing animals. Sex determination is complicated and very flexible. For instance, according to the role of temperature in sex determination, the sex-determining mechanisms in fish can be broadly classified as genotypic (GSD), temperature (TSD) or genotypic plus temperature effects (GSD + TE). Additionally, the sexual phenotype exhibits various types, including gonochorism and hermaphrodites. Research on the genetic basis and potential mechanisms of sex determination and differentiation is necessary for application in aquaculture and species conservation. In recent decades, remarkable progress has been obtained in research on sex determination and differentiation in aquatic animals. In this Special Issue, we will present state-of-the-art work relating to sex determination and differentiation in aquatic animals, assembling the most recent advances in our field in one place.

Dr. Qiaomu Hu
Dr. Ke Feng
Guest Editors

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Keywords

  • aquatic animals
  • genetics
  • genomics
  • epigenetics
  • sequencing
  • sex determination
  • sex differentiation
  • gene
  • expression

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Published Papers (3 papers)

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Research

20 pages, 13531 KiB  
Article
Functional Study of Four Histone Genes Involved in the Spermatogenesis of Cynoglossus semilaevis
by Xuexue Sun, Zhijie Li, Lijun Wang, Haipeng Yan, Xihong Li, Na Wang, Zhongdian Dong and Wenteng Xu
Animals 2025, 15(4), 593; https://doi.org/10.3390/ani15040593 - 18 Feb 2025
Viewed by 551
Abstract
Chinese tongue sole (Cynoglossus semilaevis) is an important mariculture fish in China, and female individuals present a growth advantage. However, genetic females (ZW) can sex reverse to phenotypic males, designated pseudomales. The pseudomale shows abnormal spermatogenesis and produces only Z sperm. [...] Read more.
Chinese tongue sole (Cynoglossus semilaevis) is an important mariculture fish in China, and female individuals present a growth advantage. However, genetic females (ZW) can sex reverse to phenotypic males, designated pseudomales. The pseudomale shows abnormal spermatogenesis and produces only Z sperm. Histone is pivotal in spermatogenesis, and post-translational modification could regulate its function. A comparison of testis phosphorylated and ubiquitinated proteins revealed 8 and 12 differentially phosphorylated and ubiquitinated histones in the testes of male and pseudomale Chinese tongue soles, respectively, but there was no difference in the translation level of these proteins. We selected four histone genes, h1.1-like, h1.2-like, h3, and h3.3-like, for further analysis. The expression levels of the h1.1-like, h3, and h3.3-like genes reached their highest levels at 2 years post-hatching (yph), and the expression level of h1.2-like reached its highest level at 1.5 years post-hatching (1.5 yph), indicating that its role began during the late stage of gonadal development. Promoter activity verification revealed that the promoters of the h1.1-like, h1.2-like, h3, and h3.3-like genes were located approximately upstream 2000 bp and six histone-related transcription factor sites were predicted. YY1A, YY1B, C-JUN, and JUNB may have negative regulatory effects on h1.1-like, h1.2-like, h3, and h3.3-like; AR and ETS-2 may have positive regulatory effects on h3 and h3.3-like. The ISH results revealed that h1.1-like, h1.2-like, h3, and h3.3-like mRNAs were located mainly in the sperm cells in the testes and the oocytes at various stages in the ovaries. After siRNA knockdown, the expression of dmrt1 in testis cell lines and the expression of tesk1 and neurl3 in males was downregulated, suggesting that the h1.1-like, h1.2-like, h3, and h3.3-like genes may have a negative regulatory role in spermatogenesis. The regulatory role in female fish remains to be explored. Mass spectrometry analysis revealed that histones have an important role in chromosome remodeling. These results provide a genetic basis for the molecular mechanism of gonadal development and spermatogenesis in Chinese tongue sole. Full article
(This article belongs to the Special Issue Sex Determination and Differentiation in Aquatic Animals)
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13 pages, 3287 KiB  
Article
Molecular Characterization and Expression of unc-13d in the Sex Reversal of Monopterus albus
by Zitong Lian, Fang Meng, Xueping Xia, Junchao Fang, Haifeng Tian and Qiaomu Hu
Animals 2025, 15(2), 122; https://doi.org/10.3390/ani15020122 - 7 Jan 2025
Viewed by 774
Abstract
Monopterus albus is a protogynous hermaphroditic fish that changes from female to male, but the underlying sex change mechanism remains as-yet unknown. In this study, we firstly cloned and characterized the sequence and protein structure of unc-13d of M. albus. We found that [...] Read more.
Monopterus albus is a protogynous hermaphroditic fish that changes from female to male, but the underlying sex change mechanism remains as-yet unknown. In this study, we firstly cloned and characterized the sequence and protein structure of unc-13d of M. albus. We found that the genomic structure of unc-13d was different from other species. Expression was detected in the developing gonad by applying qRT-PCR and in situ hybridization. We found that the expression of unc-13d in the ovotestis was higher than in the ovary and testes. A strong signal of unc-13d was detected in oocytes and granulosa cells in the ovary and spermatogonia and primary spermatocytes in the testes. We found that the promoter methylation of unc-13d was negatively correlated with gene expression in developing gonads, especially at site 114. A dual-luciferase assay was designed and revealed that dmrt1 regulates promoter activity opposite to foxl2. In summary, during sex reversal, DNA methylation affects the binding of the transcription factor dmrt1 and foxl2 in the promoter region through methylation and demethylation interactions to regulate the expression of unc-13d during gonadal development. Full article
(This article belongs to the Special Issue Sex Determination and Differentiation in Aquatic Animals)
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14 pages, 5106 KiB  
Article
Sex-Dimorphic Differential Expression Profiles in the Brain of the Adult Chinese Soft-Shelled Turtle, Pelodiscus sinensis
by Pan Liu, Yanchao Liu, Junxian Zhu, Chen Chen, Liqin Ji, Xiaoli Liu, Xiaoyou Hong, Chengqing Wei, Xinping Zhu, Qiaoqing Xu, Jiang Zhou and Wei Li
Animals 2024, 14(23), 3426; https://doi.org/10.3390/ani14233426 - 27 Nov 2024
Viewed by 996
Abstract
The Chinese soft-shelled turtle (Pelodiscus sinensis) is an economically important species in aquaculture, and its growth pattern is characterized by significant sexual dimorphism. However, the underlying molecular mechanisms of this phenomenon have mostly been investigated in the gonadal tissues of P. [...] Read more.
The Chinese soft-shelled turtle (Pelodiscus sinensis) is an economically important species in aquaculture, and its growth pattern is characterized by significant sexual dimorphism. However, the underlying molecular mechanisms of this phenomenon have mostly been investigated in the gonadal tissues of P. sinensis, and there are no articles on sex differentiation from the brain of P. sinensis. Here, we analyzed transcriptomes of the brains of adult male and female P. sinensis using high-throughput Illumina sequencing technology, establishing a set of differential genes and differential transcription factors. The data showed that there were 908 genes with significant differences in expression, of which 357 genes were up-regulated and 551 genes were down-regulated. We annotated using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG), and screened some genes and pathways related to growth. There were 282 growth-related differential genes and 181 sex-related differential genes. We screened the genes’ growth hormone receptor (GHR) and vascular endothelial growth factor A (VEGFA), which may be related to the growth of P. sinensis. The pathways related to the growth and development of P. sinensis are the growth hormone synthesis, secretion, and action pathway; the MAPK (mitogen-activated protein kinase) pathway; and the calcium signaling pathway. In addition, through gene set enrichment analysis (GSEA), we screened out two genes, LIM homeobox protein 1 (LHX1) and fibroblast growth factor 7 (FGF7), which are related to both growth and sex differentiation, and through protein interaction analysis of these genes, we screened out eight genes, including LHX1, FGF7, GHR, fibroblast growth factor 4 (FGF4), EGFR, BMP3, GLI family zinc finger 2 (GLI2), and neuronal differentiation 1 (NEUROD1), and verified the expression levels of these eight genes in the brain of the P. sinensis by real-time quantitative PCR (qRT-PCR), which supported the reliability and accuracy of our transcriptome analysis. Our study provides a solid foundation for analyzing the mechanisms of sexual-dimorphic growth of P. sinensis and even other turtles. Full article
(This article belongs to the Special Issue Sex Determination and Differentiation in Aquatic Animals)
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