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Histological analysis of characteristic gonadal stages in tilapia ovary (XX) and testsis (XY). Panels indicate gonads sampled from fish at different days after hatch (dah) as follows: a and b at 5 dah, c and d at 20 dah, e and f at 30 dah, g and h at 40 dah, i and j at 90 dah, and k and l at 180 dah. OG, oogonia; SG, spermatogonia; OC, oocytes; CV, ovarian cavity; ST, spermatids; SC, spermatocytes
Source publication
Background:
The factors determining sex in teleosts are diverse. Great efforts have been made to characterize the underlying genetic network in various species. However, only seven master sex-determining genes have been identified in teleosts. While the function of a few genes involved in sex determination and differentiation has been studied, we...
Citations
... Traditionally, the study of genes involved in sex determination and differentiation utilize hybridization-based microarrays, sequencing-based EST libraries and chemical tag-based serial analysis of gene expression (SAGE). With the advent of Next Generation Sequencing (NGS), RNA sequencing (RNA-Seq) has become the efficient and dominant approach for comparative transcriptome studies between gonadal types (Tao et al., 2018;Sun et al., 2013;Poon et al., 2023). In the present study, RNA-Seq was performed on testes and ovaries of adult Malabar red snapper, and we report the first gonad transcriptome for each sex of the species. ...
Malabar red snapper (Lutjanus malabaricus) is an important and high-value aquaculture species in Singapore that is attracting substantial interest and new industry investment. The consistent production of good quality eggs is an important step for establishing a selective breeding program for the species in Singapore. To achieve improved spawning outcomes, reproductive studies are needed to address the challenges in Malabar red snapper seed production, such as limited spawning success in closed culture systems. However, despite its rising profile as an aquaculture candidate and the need to improve broodstock husbandry, currently there are scarce genomic resources for the species, particularly related to genes involved in sex determination and differentiation. Herein, we report the first gonadal transcriptomes of adult L. malabaricus generated using RNA-Seq of testes (n = 6) and ovaries (n = 6). A total of 14,421 significant differentially expressed genes (DEGs) were found by comparing the gene expression profiles of ovaries and testes, including 6499 upregulated female-biased and 7922 downregulated male-biased DEGs. These DEGs included genes known to be involved in reproductive processes such as male-biased dmrt1, spat4, odf3b and sox9, and female-biased cyp19a1, zp4, sox3, bmp15 and esr1. The expression level of 16 selected DEGs were validated by RT-qPCR. This study lays the basis for further research in genes involved in sex determination and differentiation, sex control and breeding in Malabar red snapper.
... By using gonad transcriptome analysis of male and female channel catfish gonads during the critical period of sex differentiation, a few candidate genes and potential pathways underlying male-preferential cell development were revealed in catfish (Zeng et al., 2016). To uncover the genetic framework underlying sex differentiation of tilapia, a dynamic co-expression network analysis with RNA-Seq was carried out to detect differently expressed genes that were involved in sex differentiation (Tao et al., 2018). A high-quality gonadal transcriptome analysis of Siberian sturgeon was used to search for sex-differentiation genes at undifferentiated stages, and multiple genes related to the stem-cell niche and sex-specific nerve development were screened out (Vizziano-Cantonnet et al., 2018). ...
Introduction: Plectropomus leopardus, a commercially significant marine fish, is primarily found in the Western Pacific regions and along the coast of Southeast Asia. A thorough analysis of the molecular mechanisms involved in sex differentiation is crucial for gaining a comprehensive understanding of gonadal development and improving sex control breeding. However, the relevant fundamental studies of P. leopardus are relatively lacking.
Methods: In this study, a genome-wide association study (GWAS) was conducted to investigate the genetic basis mechanism of sex differentiation and gonadal developmental traits in P. leopardus utilizing about 6,850,000 high-quality single-nucleotide polymorphisms (SNPs) derived from 168 individuals (including 126 females and 42 males) by the genome-wide efficient mixed-model association (GEMMA) algorithm.
Results: The results of these single-trait GWASs showed that 46 SNP loci (-log10 p > 7) significantly associated with sex differentiation, and gonadal development traits were distributed in multiple different chromosomes, which suggested the analyzed traits were all complex traits under multi-locus control. A total of 1,838 potential candidate genes were obtained by considering a less-stringent threshold (-log10 p > 6) and ±100 kb regions surrounding the significant genomic loci. Moreover, 31 candidate genes were identified through a comprehensive analysis of significant GWAS peaks, gene ontology (GO) annotations, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, including taf7, ddx6, apoeb, sgk1, a2m, usf1, hsd3b7, dll4, xbp1, tet3, esr1, and gli3. These trait-associated genes have been shown to be involved in germline development, male sex differentiation, gonad morphogenesis, hormone receptor binding, oocyte development, male gonad development, steroidogenesis, estrogen-synthetic pathway, etc.
Discussion: In the present study, multiple genomic loci of P. leopardus associated with sex differentiation and gonadal development traits were identified for the first time by using GWAS, providing a valuable resource for further research on the molecular genetic mechanism and sex control in P. leopardus. Our results also can contribute to understanding the genetic basis of the sex differentiation mechanism and gonadal development process in grouper fish.
... Sex is determined by the interaction between genetic (genotypic sex determination, GSD) and environmental (environmental sex determination, ESD) factors that compose the heterogametic determination XX/XY system of Nile tilapia (De Alba et al., 2021b). In this species, several genes have been identified as key sex-determining genes that exhibit sexually dimorphic expression patterns before and after testis or ovary differentiation (Iriji et al., 2008;Tao et al., 2018). Tilapia ovarian differentiation is particularly encoded by factors related to cyp19a1 (P450 aromatase enzyme), which catalyzes the conversion of androgens into estrogens. ...
In nature, water temperature experiences daily variations known as thermocycles. Temperature is the main environmental factor that influences sex determination in most teleost fish. The purpose of this study was to examine the effects of rearing temperature (thermocycle (TC) vs. constant (CTE)) on development and a posterior thermal shock throughout the period of sex differentiation of Nile tilapia (Oreochromis niloticus). Embryos and larvae were kept under two temperature regimes: TC of 31 °C:25 °C day:night vs. CTE of 28 °C from 0 to 11 dpf. After this period, the larvae from each group were subjected to either heat treatment (HT, 36 °C for 12 days) or kept under the same rearing temperatures until 23 dpf (Control, C). Then all the groups remained at constant temperature until 270 dpf, when blood and gonads were collected. Larval samples were used to examine the expression of genes related to male (amh, ara, sox9a, dmrt1a) and female (cyp19a1a, foxl2, era) sexual differentiation. In juveniles, sex was characterized by histology, the gonadal expression of the genes involved in the sex steroid synthesis was analyzed by qPCR, and plasma testosterone (T) and estradiol (E2) levels were analyzed by ELISA. In larvae, daily TCs increased the survival rate against HT and up-regulated the expression of ovarian differentiation genes. In juveniles, TC + C induced a higher proportion of females and higher cyp19a1a expression compared to CTE + C. HT induced changes in the CTE group by up-regulating testicular differentiation genes and down-regulating female promoting genes, which did not occur in the TC group. Juveniles from TC + C group presented a higher proportion of females with higher E2 and cyp19a1a than CTE + HT. Fish from the CTE + HT group showed a higher percentage of males with highest T and amh. These findings indicate that daily TCs during larval development promote ovarian differentiation and diminish the masculinizing effects of HT.
... We can compare sexes using transcriptomics to determine which loci contribute to sex determination Sun et al. 2013;Lin et al. 2017). The transcriptome of reproductive tissue can also provide biological insight into sex-related differences or sex differentiation in fish Tao et al. 2018;Agarwal et al. 2020). Dmy/dmrt1Yb, DMW, DMRT1, Sox9, SDy, and Sox3 are just a few of the candidate genes associated with sex determination, gametogenesis, and gonadal differentiation and maturation in fish (Matsuda et al. 2002;Yokoi et al. 2002;Yano et al. 2012;Takehana et al. 2014). ...
Among the major concerns associated globally with aquaculture or fish farming, top-notch and prime one is the treatment and management of xenobiotics. Aquatic ecosystems are heavily and negatively impacted by these chemicals. Xenobiotics impact aquaculture industry in a number of ways, be it the decline in the production or remaining in the system for so long that it hampers treatment and management. Because of its presence for a large time in waterbodies, these compounds can build up in food chains via the consumption of aquaculture products. There are good reports where these chemicals build-up in human body leading to cancers. One of the main agendas of xenobiotic management is its degradation. Degradation involves bioremediation (bioattenuation, biostimulation, and bioaugmentation). Burkholderia, Bacillus, Pseudomonas, Sphingomonas, Kocuria, Chromohalobacter, and Achromobacter have been reported to play a critical role in the degradation of these compounds. Bioremediation process can be improved with advancements in molecular biological techniques like genome editing, which allows the modification of microbial strains with an increased capacity for digesting several xenobiotics simultaneously and/or at a quick rate the bioremediation process can be improved.KeywordsXenobioticDegradationBioremediationGenome editing
... We can compare sexes using transcriptomics to determine which loci contribute to sex determination (Chen et al. 2015;Sun et al. 2013;Lin et al. 2017). The transcriptome of reproductive tissue can also provide biological insight into sex-related differences or sex differentiation in fish (Zhang et al. 2019;Tao et al. 2018;Agarwal et al. 2020). Dmy/dmrt1Yb, DMW, DMRT1, Sox9, SDy, and Sox3 are just a few of the candidate genes associated with sex determination, gametogenesis, and gonadal differentiation and maturation in fish (Matsuda et al. 2002;Yokoi et al. 2002;Yano et al. 2012;Takehana et al. 2014). ...
Plasticizers, insecticides, detergents, and medications are examples of endocrine-disrupting chemicals (EDCs), which have an impact on a number of hormone-regulated physiological pathways in both people and wildlife. Many EDCs are lipophilic compounds that attach to hydrophobic spaces in steroid receptors like the oestrogen receptor and the androgen receptor, which are crucial for vertebrate development and reproduction. EDCs have been linked to a number of diseases, including early puberty, various malignancies, obesity, and reproductive dysfunction (such as decreased fertility, abnormalities of the reproductive tract, and skewed male/female sex ratios in fish). EDCs can imitate or disrupt endogenous hormone function, and they may have a substantial negative influence on an organism’s ability to survive during critical developmental and reproductive stages. In this chapter, we review the recent advanced effects of endocrine-disrupting compounds (EDCs) as emerging aquatic contaminants and special emphasis on reproduction and development.KeywordsEndocrine-disrupting chemicalsReproductionDevelopment
... From 30 dpf, the sexual differentiation begins, and it is possible to observe the first morphological changes in the gonads. From 42 dpf, the morphological changes become even more evident, due to the increased expression of 2 genes, Dmrt1 gene (testis) and Cyp19a1a gene (ovary), responsible for sex differentiation (Tao et al. 2018). In our experiment, testosterone was administered in the ideal period for sex reversal, and for this reason, we obtained ≈65, 75, and 72% in the groups of 30 T, 60 T, and 90 T values for sex reversal, respectively. ...
The objective of this work was to develop a food additive for the sex reversal of Nile tilapia (Oreochromis niloticus) based on a simple oil in water (O/W) nanoemulsion with testosterone propionate for incorporation into commercial feed. Oil screening and evaluation of the organoleptic and physicochemical characteristics were carried out to determine the best formulation. A palatability test was also performed. Sex reversal test was assayed using 5 experimental groups: negative control — macerated feed without hormone; free testosterone — macerated feed with 60 mg/kg of testosterone propionate diluted in ethanol; and macerated feed with testosterone propionate nanoemulsion at a concentration of 30, 60, and 90 mg/kg. Stable nanoemulsions (size 76–210 nm) with testosterone propionate were produced. All nanoemulsion-added feed was palatable to tilapia. We obtained sex reversal values of ≈65, 75, and 72% in the groups of 30, 60, and 90 mg/kg, respectively. We can conclude that the nanoemulsion showed promising results; it is capable of inducing sex reversal in tilapia, is suitable as a commercial product, and has the potential to promote safety for rural staff and reduce the environmental impact of hormones.
... GATA2 is transiently expressed in the ovarian germ cell lineage during mouse gonadogenesis, and the signal location coincides with germ cell marker OCT4 [78]. Some of the important transcription factors (e.g., FOXL2, SOX9 and SOXH) we found in M. lateralis are also identified as key regulators of sex development in mouse [79], tilapia [80] and sea bass [81] by WGCNA, suggesting the drivers of gonadal development may be conserved across animal phyla. ...
... The onset of sex differentiation can be determined by the morphological or molecular method [80,82]. In this study, we found molecular sex differentiation occurs as early as 35 dpf, while morphological sex differentiation occurs at 40-45 dpf in M. lateralis. ...
Background
Gonadal development is driven by a complex genetic cascade in vertebrates. However, related information remains limited in molluscs owing to the long generation time and the difficulty in maintaining whole life cycle in the lab. The dwarf surfclam Mulinia lateralis is considered an ideal bivalve model due to the short generation time and ease to breed in the lab.
Results
To gain a comprehensive understanding of gonadal development in M. lateralis , we conducted a combined morphological and molecular analysis on the gonads of 30 to 60 dpf. Morphological analysis showed that gonad formation and sex differentiation occur at 35 and 40–45 dpf, respectively; then the gonads go through gametogenic cycle. Gene co-expression network analysis on 40 transcriptomes of 35–60 dpf gonads identifies seven gonadal development-related modules, including two gonad-forming modules (M6, M7), three sex-specific modules (M14, M12, M11), and two sexually shared modules (M15, M13). The modules participate in different biological processes, such as cell communication, glycan biosynthesis, cell cycle, and ribosome biogenesis. Several hub transcription factors including SOX2 , FOXZ , HSFY, FOXL2 and HES1 are identified. The expression of top hub genes from sex-specific modules suggests molecular sex differentiation (35 dpf) occurs earlier than morphological sex differentiation (40–45 dpf).
Conclusion
This study provides a deep insight into the molecular basis of gonad formation, sex differentiation and gametogenesis in M. lateralis , which will contribute to a comprehensive understanding of the reproductive regulation network in molluscs.
... Novel_145 regulates the expression of wt1, which has been found to have high expression in developing and adult testis of catfish and played an important role in spermatogenesis [63]. In addition, wt1 has been found to be a testis-biased gene in Silurus asotus [64], Cyprinus carpio, and tilapia [65,66]. In our study, novel_145 was also highly expressed in the testis of T. blochii, indicating that novel_145 may play an essential role in the development of testis. ...
The golden pompano (Trachinotus blochii) is a marine fish of considerable commercial importance in China. It shows notable sexual size dimorphism; the growth rate of females is faster than that of males. Therefore, sex-biased research is of great importance in T. blochii breeding. However, there have been few studies on sex differentiation and mechanisms underlying sex determination in T. blochii. MicroRNAs (miRNAs) play crucial roles in sex differentiation and determination in animals. However, limited miRNA data are available on fish. In this study, two small RNA libraries prepared from the gonads of T. blochii were constructed and sequenced. The RNA-seq analysis yielded 1366 known and 69 novel miRNAs with 289 significantly differentially expressed miRNAs (p < 0.05). Gene ontology (GO) analysis confirmed that the TFIIA transcription factor complex (GO: 0005672) was the most significantly enriched GO term. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the differentially expressed miRNAs and target genes were mainly related to sex determination and gonadal developmental signaling pathways, specifically the Wnt signaling pathway, MAPK signaling pathway, and steroid biosynthetic pathway. MiRNA-mRNA co-expression network analysis strongly suggested a role for sex-biased miRNAs in sex determination/differentiation and gonadal development. For example, gata4, foxo3, wt1, and sf1 genes were found to be regulated by bta-miR-2898; esr2 and foxo3 by novel_176, and ar by oar-let-7b. Quantitative real-time polymerase chain reaction analysis of selected mRNAs and miRNAs validated the integrated analysis. This study established a set of sex-biased miRNAs that are potential regulatory factors in gonadal development in T. blochii. These results provide new insight into the function of miRNAs in sex differentiation and determination in T. blochii and highlight some key miRNAs for future studies.
... Sex determination has received significant research attention in various animals, and numerous genes involved in sex determination have been found in many model species (human, mice, goat, chicken, zebra fish, killifish and cichlid), including sox9, foxl2, wnt4 and dmrt1 [1][2][3]. Facilitated by high conservation, sex-related genes in other species have been identified through homology screening [4,5]. However, the sex-determination mechanisms in fish (especially teleost fishes) are not as well conserved as those in mammals or birds [6,7]. ...
Among vertebrates, teleost fishes exhibit the largest array of sex-determining systems, resulting in many reproductive strategies. Screening these fish for sex-related genes could enhance our understanding of sexual differentiation. The lizardfish, Saurida elongata (Temminck & Schlegel, 1846), is a commercially important marine fish in tropical and subtropical seas of the northwest Pacific. However, little genomic information on S. elongata is available. In this study, the transcriptomes of three female and three male S. elongata were sequenced. A total of 49.19 million raw read pairs were generated. After identification and assembly, a total of 59,902 nonredundant unigenes were obtained with an N50 length of 2070 bp. Then, 38,016 unigenes (63.47% of the total) were successfully annotated through multiple public databases. A comparison of the unigenes of different sexes of S. elongata revealed that 22,507 unigenes (10,419 up-regulated in a female and 12,088 up-regulated in a male) were differentially expressed between sexes. Then, numerous candidate sex-related genes were identified, including dmrt2, dmrt4, foxl2, zps and starts. Furthermore, 23,941 simple sequence repeats (SSRs) were detected in SSR-containing sequences. This informative transcriptome analysis provides valuable data to increase the genomic resources of S. elongata.
... The development of sequencing technologies provides an opportunity to study the role of specific genes and transcripts associated with the trait of interest through annotation. RNA-seq, a next-generation sequencing method, was applied to study differentially expressed genes (DEGs) in transcriptomes for various economic traits in aquaculture fish, such as temperature stress (Liang et al., 2015;Logan and Somero, 2010;Smith et al., 2013), disease resistance Robinson et al., 2020), sex determination (Tao et al., 2018), and growth traits . Since QTL mapping can dissect the genetic architecture of economic traits into several chromosomal loci, its combination with transcriptome profiling represents a practical solution to further refine the mapping results, which has been successfully applied to animals and plants (Habib et al., 2018;Lionikas et al., 2012), but it is rarely reported to be applied to fish. ...
Genetic improvement of growth traits is a major target of grouper aquaculture and breeding. As one of the largest groupers, the giant grouper (Epinephelus lanceolatus) has excellent growth performance, although the genetic basis of its growth traits has been rarely studied. In this study, we successfully constructed a high-density genetic linkage map with 2988 SNPs generated by genotype-by-sequencing of 178 individuals, which belong to an F1 full-sibling family. The length of the map was 3231.5 cM with an average interval of 1.21 cM. Then, we performed genome-wide QTL (quantitative trait locus) mapping for five growth traits including all length, body length, body height, body thickness, and body weight in the giant grouper and identified six growth-associated QTLs, which explained 4.65–12.56% of the phenotypic variance. These QTLs were distributed on five linkage groupers (LGs) of our sex-averaged linkage map with two QTLs on LG11, four QTLs on LG7, LG10, LG15, and LG23. The genes identified within the significant QTLs were validated using qPCR and the results showed six significantly upregulated genes (kalrn, ypel1, supt7l, lacs5, ccnd2, mybpc2) in tissues (muscle, fat, liver, gill, etc.) of the fast vs slow growth groups were highlighted as promising candidates. Further, RNA-seq analysis revealed 484 differentially expressed genes (DEGs) between fast/slow growth groups that play roles in the RNA transport, metabolic pathways, PPAR signaling pathway, and carbon metabolism pathways. Notably, 27 DEGs were detected in the identified growth-associated-QTL regions. Those candidate genes shared between QTL mapping and DEGs may play important roles in regulating cell growth, signal transduction, carbohydrate metabolism and skeletal development. Overall, our findings are useful for improving the genetic process for molecular marker-assisted selection and provide new insights into elucidating the molecular mechanism of growth variation in this species.
