Search Results (93)

The scallops of the genus Argopecten hold a significant position in the international shellfish aquaculture industry. However, due to their hermaphroditic nature, selfing reproduction has led to an increasingly severe phenomenon of germplasm degradation. The development of interspecific hybridization can effectively address this issue, but the fertility of interspecific hybrid offspring is greatly affected. Backcrossing appears to be a more practical and feasible solution, yet current research in this regard remains extremely scarce. In this study, the F1 generation of bay–Peruvian hybrid scallops (Aip derived from Ai ♀ × Ap ♂) and Peruvian–bay hybrid scallops (Api derived from Ap ♀ × Ai ♂) were successfully backcrossed with Peruvian scallops (Argopecten purpuratus, Ap) and bay scallops (Argopecten irradians, Ai) to produce F2 backcrossed population (Aipi derived from Aip ♀ × Ai ♂; Aipp derived from Aip ♀ × Ap ♂; Apii derived from Api ♀ × Ai ♂ and Apip derived from Api ♀ × Ap ♂). These F2 populations were comprehensively analyzed in terms of heterozygosity, gonadal development and differentiation, fertility, genetic diversity, and offspring identification. The results revealed that the fertilization and hatching rates of the F2 generation were significantly lower than those of the parental generations. However, they exhibited normal development through larval, juvenile, and adult stages, albeit with prolonged larval development periods. Notably, the juvenile and adult stages demonstrated significant hybrid vigor. The F2 generation retained hermaphroditic characteristics but also included individuals with exclusively female gonads. Cloning of Dmrt1 and Foxl2 genes in these scallops showed high similarity with the bay scallop’s corresponding genes, and Dmrt1 is specifically expressed in the testis, while Foxl2 is specifically expressed in the ovary, as is the case in the bay scallop. Eleven pairs of polymorphic loci were selected from developed microsatellite markers for bay scallops, and the analysis revealed that the polymorphism levels in the F2 backcrossed population were higher than those in purebred parental self-crosses. Additionally, the reliability of parental genetic information in the backcrossed population has also been corroborated according to the scallop descent identification experiments. The findings of this study enhance the understanding of Aipi, Aipp, Apii, and Apip, providing a theoretical foundation for the selection and breeding of scallop species with superior traits and addressing inbreeding decline in scallop culture. Full article

Background and Clinical Significance: Steroid cell tumours of the ovary, not otherwise specified (SCT-NOSs), are rare sex cord–stromal neoplasms with a poorly characterised molecular landscape, in which only exceptional CTNNB1 mutations have so far been reported and no recurrent driver alteration is firmly established. A better characterisation of their molecular spectrum has clinical significance for accurate diagnostic categorisation of ovarian sex cord–stromal tumours and for the identification of potentially targetable pathway alterations in this rare entity. Case Presentation: We report two consecutive SCT-NOSs of the right ovary, retrieved from the archives of the Department of Pathology of the Hôpital Universitaire de Bruxelles and of Curepath. Both underwent comprehensive sex cord–stromal and differential immunohistochemistry and targeted next-generation sequencing on a 168-gene panel with a mean coverage of 2690× (Case 1) and a 17-gene panel (Case 2) (MGI DNBSEQ-T7 for Case 1; Ion GeneStudio S5 for Case 2). A 56-year-old post-menopausal woman (Case 1) and a 50-year-old immunosuppressed woman with a history of renal transplantation and lymphoma (Case 2) both presented with rapidly progressive virilisation. The two right ovarian tumours (20 to 25 mm, no Reinke crystals) displayed an unambiguous sex cord–stromal immunophenotype (α-inhibin, calretinin, SF-1 and Melan-A positive; CD10, WT1, EMA, AE1/AE3 and PAX8 negative), with aberrant nuclear and cytoplasmic β-catenin staining. Sequencing identified a pathogenic CTNNB1 c.133T>C p.(Ser45Pro) variant in Case 1 and a pathogenic CTNNB1 c.95A>T p.(Asp32Val) variant in Case 2, with wild-type FOXL2 in both. Conclusions: Three of the four molecularly characterised CTNNB1-mutated SCT-NOSs converge on the two principal GSK-3β phosphorylation residues of β-catenin, identifying Wnt/β-catenin-pathway dysregulation as a potentially recurrent event and providing additional evidence for the involvement of the Wnt/β-catenin pathway in an emerging molecular subset of SCT-NOS. In a tumour with the canonical sex cord–stromal immunophenotype, an exon 3 CTNNB1 hotspot mutation should not be regarded as evidence against the diagnosis of SCT-NOS and may help define a distinct molecular subset. Full article

Telocytes are stromal cells defined by extremely long, moniliform prolongations termed telopodes and have been described in most mammalian organs since their formal designation in 2010. During the past two decades, the field has expanded from ultrastructural organ-mapping to hypotheses concerning stem-cell niche regulation, extracellular-vesicle-mediated communication, fibrosis, inflammation, and cancer-associated stromal remodelling. This expansion, however, has also generated methodological heterogeneity, with frequent reliance on non-specific markers such as CD34, PDGFRα, vimentin, and c-kit, often without ultrastructural validation or functional perturbation. In this critical review, we reassess the evidential status of major claims in telocyte biology, distinguishing robustly demonstrated mechanisms from plausible but incompletely proven hypotheses. The strongest functional evidence remains the conditional ablation of Wnt secretion in intestinal Foxl1-/Gli1-expressing subepithelial telocytes, which demonstrates their necessity for stem-cell niche maintenance. By contrast, most evidence from cardiac, dermal, reproductive, and fibrotic tissues remains supplementation-based or correlative. We propose a unified Stromal Network Organiser framework, in which telocytes are interpreted as tissue-specific stromal network cells whose dysfunction may involve not only numerical loss, but also telopode fragmentation, contact uncoupling, paracrine alteration, stromal replacement, and failed niche signalling. To improve methodological clarity, we introduce a two-dimensional evaluation matrix that separates identification confidence from functional confidence. We argue that the next decade of telocyte research should prioritise loss-of-function experiments outside the intestine, independent replication of foundational single-laboratory concepts, and high-resolution multi-organ correlative ultrastructural atlases. Full article

The zig-zag eel (Mastacembelus armatus) exhibits sexual dimorphism in growth patterns. Identifying the genes involved in sex differentiation is a crucial step toward achieving single-sex breeding and serves as a vital foundation for elucidating the XY sex determination mechanism in M. armatus. This study measured the morphological characteristics of male and female M. armatus and found that males were significantly superior to females in body weight and nearly all morphological indices. Subsequently, whole-transcriptome sequencing was performed on the gonads of adult males and females, identifying 11,714 DEmRNAs, 3442 DElncRNAs, 416 DEcircRNAs, and 620 DEmiRNAs, including male sex differentiation genes such as Sox30, Tbx1, Sox9, and Gata4, and female sex differentiation genes like Sox3, Foxl2, and Wnt4a. Functional enrichment analysis identified pathways associated with sex differentiation, including the TGF-beta signaling pathway, the steroid hormone biosynthesis, the Hippo signaling pathway, and the Wnt signaling pathway, etc. A ceRNA network was constructed based on differentially expressed mRNAs and ncRNAs, revealing that the sex differentiation-related genes Sox3, Sox9, Sox30, Tbx1, and Wt1 are regulated by one or multiple pairs of lncRNA/circRNA-miRNA pairs. The study results will provide molecular targets for research on sex-controlled breeding in M. armatus and lay an important theoretical foundation for clarifying its sex differentiation mechanisms. Full article

Otosclerosis is a common cause of conductive hearing loss thought to result from dysregulated bone remodeling in the embryonic tissues of the globuli interossei. Both familial and sporadic cases have been reported. To date, 10 published OTSC loci and four genes (FOXL1 (OTSC11), SMARCA4 (OTSC12), MEPE, SERPINF1) have been identified in autosomal dominant families. Using a combined genetic and genomics approach in five affected siblings, we identified a nonsense mutation in Karyopherin subunit α7 (KPNA7, c.49C>T, p.R17X), the newest of the importin-α family of nuclear transporters. KPNA7 is a key maternal factor involved in the classical transport of NLS-containing cargo proteins, active during early embryonic cleavage events and zygotic genome activation. So far, 377 cargo proteins associated with KPNA7 have been identified. Recessive KPNA7 variants cause skeletal abnormalities, epilepsy, intellectual disabilities and preimplantation embryo arrest (PREMBA). A closer look at the OTSC genes reveals their involvement in endochondral ossification signaling pathways. We explore how KPNA7 haploinsufficiency in the embryonic tissues of the otic capsule may cause dysregulated bone remodeling. This study expands the phenotypic spectrum of KPNA7 and provides new insights into the pathobiology of otosclerosis. Full article

Chinese tongue sole (Cynoglossus semilaevis), an economically important mariculture species in China, exhibits pronounced sexual dimorphism in growth, underscoring the importance of elucidating sex regulatory mechanisms for aquaculture development. Heterogeneous nuclear ribonucleoprotein K (hnrnpk) critically regulates mammalian reproductive development, yet its role in fish sex regulation remains elusive. Here, we systematically investigated the underlying function and mechanisms of hnrnpk in C. semilaevis through integrated molecular cloning, expression profiling, upstream regulatory analysis, functional assays, and transcriptome sequencing. We found that hnrnpk was highly expressed in the gonad and liver, with female-biased expression during gonadal development. Promoter activity assays revealed that sox2 and c-Jun enhanced hnrnpk transcription, whereas foxl2 and ar suppressed it. Additionally, hnrnpk was directly targeted by miR-460a-5p in C. semilaevis, revealing multi-level transcriptional and post-transcriptional regulation. Functional analyses showed that hnrnpk regulated cyp19a1a in a cell type-dependent and dose-sensitive manner: the expression of cyp19a1a was both upregulated in hnrnpk-knockdown ovarian cells and hnrnpk-overexpression testicular cells. Interestingly, foxl2 was upregulated in hnrnpk-knockdown ovarian cells but suppressed in hnrnpk-overexpression testicular cells, which showed the distinct regulation mechanisms in the different sexual programs. Transcriptomic analyses further revealed that several sex-related genes (sox9a with downregulation, etc.) were significantly regulated, and cell development and cycle pathways were dramatically enriched in functional enrichment analyses. This might indicate that hnrnpk overexpression drives C. semilaevis testis (CSTE) toward feminization reprogramming through sox9 switching and multi-pathway perturbations. Overall, our findings might reveal that hnrnpk, a female-biased gene regulated by miR-460a-5p and transcription factors, influences sex-related gene expression through sox9 switching. This study will offer new insights for C. semilaevis hnrnpk into sex determination and also provide a potential target for monosex breeding in aquaculture. Full article

Genes involved in sexual development have been identified in many teleost fishes, including the turbot, a flatfish of high commercial value in aquaculture. In this species, a major sex determination (SD) Quantitative Trait Locus has been identified, and Sox2 has been proposed as the SD gene. Although RT-PCR, qPCR, and transcriptomic analyses have been performed on turbot gonads, histological studies remain limited. Here, we examined the tissue-specific expression patterns of several sex-related genes in turbot using in situ hybridization on paraffin sections (SISH) of differentiated ovaries and testes of juvenile and adult specimens. Vasa, Foxl2, Amh, Sox2 and Sox17 transcripts were detected in both male and female gonads, whereas Cyp19a1a and Sox19 expression was restricted to the ovary; these results support previous gene expression analyses and suggest a role for these genes in gonadal development and reproductive functions in this species. SISH provides complementary information to molecular analyses by identifying the specific cell types expressing the sex-related genes analyzed in gonadal tissue, thereby offering a more comprehensive understanding of gonadal differentiation in turbot. Comparison with results reported for the gonads of other teleost species revealed similar tissue-specific gene expression patterns during sexual development. Full article

Ovarian reserve and reproductive life are closely linked concepts in female reproductive biology. The ovarian reserve consists of primordial follicles and refers to the number and quality of oocytes (eggs) remaining in the ovaries at any given time. Follicular dynamics shape a woman’s reproductive lifespan, ultimately leading to menopause. Elucidating the underlying genetic and molecular pathways of follicle maturation and depletion is thus crucial for understanding menopausal onset and progression, both in normal and pathophysiological contexts, such as primary ovarian insufficiency, defined as menopause before the age of 40. A key factor in ovarian differentiation and fertility maintenance is FOXL2, a forkhead family transcription factor that plays a crucial role in follicle formation and development, ovarian maintenance, and sex determination. By employing a ChIP-Seq approach in mice, we identified a previously unreported binding of FOXL2 to a Tsc1 regulatory region. Our data, along with a thorough literature review, support the hypothesis that FOXL2-mediated activation of Tsc1 in granulosa cells can help maintain primordial follicles in a dormant state by suppressing mTORC1 signalling. Understanding the mechanisms behind ovarian reserve may lay the foundation for developing novel fertility preservation strategies, improving fertility treatment protocols and promoting in vitro activation of cryopreserved ovarian tissue to support folliculogenesis. Full article

The freshwater snail Bellamya purificata is both ecologically and economically significant, exhibiting notable sexual dimorphism in growth and nutritional traits that underscore the importance of breeding of monosex stocks. However, the genetic basis of sex determination remains unclear. Herein, genome-wide association studies (GWASs) combined with transcriptomic analysis were conducted to identify sex-linked markers and candidate genes for this species. GWAS generated 571 significantly sex-associated SNPs and 1853 InDels, corresponding to 44 candidate genes. Multiple significant SNP peaks were detected on chromosomes 1 and 2, with mrc2 and mis18bp1 as key candidate genes. A sex-linked InDel marker located within mis18bp1 can distinguish males and females cost-effectively. Genotype analysis of the sex-associated loci revealed that most females were homozygous while males were heterozygous, suggesting that B. purificata has a primarily XX/XY sex determination system. Comparative gonadal transcriptome analyses identified 2996 female-biased and 4281 male-biased genes. Among them, sry, sox8, dmrt1 and dmrt2 may be critical in male sex differentiation, while β-catenin, foxl2, esr1 and nr5a2 may be important in female sex differentiation. Integration of GWAS and transcriptomic data highlighted four pronounced sex-associated candidate genes, including mis18bp1, rnf216, tbx1 and mrc2. These results provide a valuable foundation for elucidating the genetic mechanisms underlying sex determination and for the development of monosex stocks in B. purificata. Full article

Chinese tongue sole (Cynoglossus semilaevis) is an important mariculture product in northern China, exhibiting significant sexual dimorphism: females grow 2–4 times faster than males and ultimately attain much greater body weights. As a well-known transcription factor crucial for regulating sex differentiation, foxl2 has been characterized in various mammals. Herein, we identified and characterized three foxl genes, foxl1, foxl2a and foxl2l. Three foxl genes exhibited a gonad-biased expression pattern, where foxl2a showed higher expression in ovary than in testis, while foxl1 and foxl2l exhibited higher expression in testis. All foxl genes were detected in testes and ovaries by ISH; foxl1/foxl2l were expressed in oocytes and sperm, and foxl2a in granulosa cells and sperm. Overexpression of foxl in testicular cells led to KEGG enrichment in DNA repair, MAPK, FOXO and progesterone-mediated oocyte maturation pathways. In tongue sole testicular cell line, knockdown of foxl1 and foxl2l resulted in upregulation of multiple male-related genes. In contrast, knockdown of foxl2a led to decreased expression of aromatase genes and increased expression of ctnnb1, indicating that foxl2a is more closely associated with female differentiation and maintenance. Our study investigated the functions of the foxl gene family in teleosts and offers valuable insights into their role in sex differentiation and gonadal maintenance in teleost fish. Full article

Loach (Misgurnus anguillicaudatus) is a small benthic fish favored by consumers in East Asia. Female loaches exhibit greater production value due to their larger size and higher meat yield. Therefore, controlling the sex of loach should be studied to implement an all-female breeding strategy. This study identified sex-related SNP markers and candidate genes in loach through GWAS. Genotyping male and female populations with WGRS revealed 84 SNPs labeled as associated with sex. Distinct SNP peaks appeared on Chr6 and Chr3, with over half of the sex-associated SNPs located on Chr6. Within these sex-associated regions, 15 key candidate genes related to sex and reproduction were identified, including hemgn and foxl2a. Among these genes, pik3cb on Chr3 and hhip, cntln, and pard3ba on Chr6 have multiple sex-associated haplotypes that can be utilized for subsequent monosex breeding. Notably, a highly male-linked SNP marker was identified on pard3ba, whose genotype is consistent with the male heterogamete (XX/XY). Through gene enrichment analysis and expression validation, signaling pathways such as TGF-β, FoxO, and mTOR were identified as being involved in sex regulation. This study provides molecular markers for sex-controlled breeding in loach, facilitating in-depth research into the mechanisms of sex regulation in loach. Full article

Spermatogenesis is a sophisticated process coordinated by germ cells and the somatic microenvironment. Circular RNAs (circRNAs), key components of competitive endogenous RNA (ceRNA) networks, form intricate post-transcriptional regulatory systems by sequestering microRNAs (miRNAs). However, the specific functions of these networks in spermatogenesis, particularly regarding the cell-intrinsic regulatory programs of germ cells, remain poorly understood. To address this, we utilized a unique foxl3 mutant model in medaka (Oryzias latipes), in which XX female germ cells spontaneously transdifferentiate into functional sperm within the ovarian somatic environment. This model enables the functional enrichment of core spermatogenic programs largely independent of male-specific somatic cues. Through whole-transcriptome sequencing and bioinformatic analysis, we identified 58 key circRNAs, 27 core miRNAs, and 2965 mRNAs, and constructed a candidate ceRNA regulatory network mediated by six circRNAs. Under genetically consistent conditions, this study elucidated a putative ceRNA network directly involved in the germ cell-dominant initiation of spermatogenesis, suggesting an essential role of these networks in germ cell fate determination. These findings provide new insights into the regulatory mechanisms of teleost spermatogenesis and offer valuable molecular targets for advancing reproductive medicine and improving breeding efficiency in aquaculture. Full article

The wnt gene family encodes a group of highly conserved secreted glycoproteins that play essential roles in vertebrate development, including tissue patterning, cell differentiation, and gonadal regulation. However, the genomic organization, evolutionary dynamics, and functional roles of Wnt signaling components in flatfish remain poorly understood. In this study, we performed a comprehensive genome-wide identification, evolutionary characterization, expression profiling, and functional analysis of wnt genes in Cynoglossus semilaevis, a flatfish species exhibiting ZW/ZZ sex determination and temperature-induced sex reversal. A total of 20 wnt genes were identified and classified into 13 subfamilies, displaying conserved structural organization and phylogenetic relationships consistent with other teleosts. Chromosomal mapping revealed lineage-specific WNT clusters, including a unique wnt3–wnt7b–wnt5b–wnt16 block, as well as syntenic associations with reproduction-related genes (e.g., adipor2, sema3a, nape-pld, erc2, lamb2), suggesting coordinated genomic regulation. Tissue transcriptome analysis demonstrated strong sex- and tissue-biased expression patterns, with wnt5a predominantly expressed in ovaries and wnt5b specifically upregulated in pseudo-male testes. Functional assays revealed that knockdown of wnt5a or wnt5b induced testis-specific genes (sox9b, tesk1) and suppressed ovarian markers (foxl2, cyp19a1a), indicating antagonistic regulatory roles in gonadal fate determination. Promoter analysis identified yy1a as a selective repressor of wnt5b, but not wnt5a, providing a mechanistic basis for paralog divergence. Furthermore, pull-down combined with LC–MS/MS analysis showed that WNT5b interacts with proteins enriched in ribosome biogenesis and ubiquitin-mediated proteolysis, suggesting a role in translational regulation and protein turnover during spermatogenesis. Together, these findings establish WNT5 signaling—particularly wnt5b—as a key driver of testicular development in C. semilaevis and provide new insights into the molecular mechanisms underlying sex differentiation and sex reversal in flatfish. Full article

Transforming growth factor β (TGF-β) superfamily members are critical in teleost sex determination and differentiation. Tgfb2b is an important TGF-β ligand gene exhibiting dominant expression in the ovary of Chinese tongue sole (Cynoglossus semilaevis), yet its function in sex regulation remains unclear. In the present study, the gene expression pattern, transcriptional regulation, and knockdown effect were examined. Its expression persisted and showed a gradual increase throughout ovarian development from 3 months to 1.5 years post-hatching. In situ hybridization (ISH) revealed that the gene was distributed across oocytes at stages I–III, while scarcely detectable in the testis. The transcriptional factors CCAAT/enhancer binding protein α (C/EBPα) and Jun proto-oncogene AP-1 transcription factor subunit (c-Jun) could repress the activity of tgfb2b promoter. In vitro knockdown of tgfb2b in C. semilaevis ovarian cells led to downregulation of its downstream genes (e.g., smad1 and smad2) as well as other sex-related genes (e.g., foxl2 and esr2b). Moreover, multi-omics analysis indicated that, in C. semilaevis gonads, a miRNA named novel-m0083-3p showed an opposite expression pattern with tgfb2b and might have a binding site with the gene. By dual-luciferase assay, tgfb2b was validated to be directly targeted and suppressed by the miRNA. These results demonstrate that tgfb2b plays a significant role in ovarian differentiation and development. Further functional and molecular studies on the interplay between tgfb2b and the foxl2–cyp19a–esr axis will help elucidate the regulatory network underlying sex development in teleost. Full article

FOXL2 (forkhead box protein L2) is a transcription factor, its function and regulatory mechanism have been mainly studied in mammals; related research on marine invertebrates is still insufficient. It was found that oogenesis was affected, and even a small number of cells resembling spermatogonial morphology appeared in C. farreri ovaries after the FOXL2 was knocked down through RNA interference (RNAi) technology in our laboratory previously. Based on previous research, this paper conducted transcriptome sequencing and differential expression analysis on the ovarian tissues between the experimental group (post-RNAi) and the control group (pre-RNAi) of C. farreri, and used recombinant C. farreri FOXL2 protein for antibody production in Chromatin Immunoprecipitation Sequencing (ChIP seq) experiments to comprehensively analyze the pathways and key genes regulated by FOXL2 during oogenesis. The results showed that in the RNAi experimental group, 389 genes were upregulated, and 1615 genes were downregulated. Among the differentially expressed genes (DEGs), the differential genes related to gender or gonadal development are relatively concentrated in physiological processes such as steroid hormone synthesis, spermatogenesis, gonadal development, and ovarian function maintenance, as well as the FoxO and estrogen signaling pathways. Combining transcriptome and ChIP-seq data, it was found that there were some genes related to sex gonadal development among genes which were directly regulated by FOXL2, such as Wnt4, SIRT1, HSD17B8, GABABR1, KRAS, NOTCH1, HSD11B1, cPLA2, ADCY9, IP3R1, PLCB4, and Wnt1. This study lays the foundation for a deeper understanding of the FOXL2′s specific regulatory mechanism during oogenesis in scallops as a transcription factor. Full article