Transcriptome identification of genes associated with uterus-vagina junction epithelial folds formation in chicken hens

Key miRNAs of chicken seminal plasma extracellular vesicles related with sperm motility regulation

MicroRNAs (miRNAs) are bio-active elements cargoed by seminal plasma extracellular vesicles extracellular vesicles (SPEVs) which are crucial for sperm function and fertility modulation. This study aimed to isolate, characterize, and identify the miRNA expression profiles in the SPEVs from high (HSM) and low sperm motility (LSM) groups that could serve as fertility biomarkers and explain the underlying mechanisms. The isolated SPEVs were round spherical structures of approximately 50-200 nm in diameter expressing molecular markers. A total of 1006 and 1084 miRNAs were detected in HSM and LSM, respectively, with 34 being differentially expressed. Their targeted genes involved in SNARE interactions in vesicular transport, Metabolic pathways, and Apelin signaling pathway, etc. The joint analysis with mRNAs of sperm and sperm storage tubules cells highlighted the cellular communication mediated by SPEVs miRNAs, where they may rule fertility by affecting sperm maturation and amino acid metabolism. SPEVs as additives could improve fertility of fresh and frozen sperm, while the knockdown of one of the differentially expressed miRNAs, miR-24-3p, diminished this effect, indicating its crucial roles. This study expands our understanding of SPEVs miRNAs mediated sperm maturation and fertility modulation, and may help to develop new therapeutic strategies for infertility and sperm storage.

Turkey hen sperm storage tubule transcriptome response to artificial insemination and the presence of semen

Introduction: Sperm storage within the uterovaginal junction (UVJ) of avian species occurs in specialized structures termed sperm storage tubules (SSTs) and allows for prolonged storage of semen, though the molecular mechanisms involved in semen preservation are not well understood. Little work has been done examining how function of the SSTs is impacted by insemination and by semen present in the SSTs. Methods: Transcriptome analysis was performed on isolated SSTs from turkey hens receiving no insemination (control), sham-insemination, or semen-insemination at three timepoints (D1, D30, and D90 post-insemination). Bioinformatic and functional annotation analyses were performed using CLC Genomics Workbench, Database for Annotation, Visualization, and Integrated Discovery (DAVID), and Ingenuity Pathway Analysis (IPA). Pairwise comparisons and k-medoids cluster analysis were utilized to decipher differential expression profiles in the treatment groups. Results: The SST transcriptome of the semen inseminated group exhibited the greatest differences within the group, with differences detectable for up to 90 days post insemination, while control and sham-inseminated groups were more similar. In the semen-inseminated samples, upregulation of pathways relating to classical and non-classical reproductive signaling, cytoskeletal remodeling, physiological parameters of the local UVJ environment, and cellular metabolism was observed. In the sham-inseminated samples, upregulation of immune pathways and non-reproductive endocrine hormones was observed. Discussion: This work provides insights into the molecular level changes of the SST in response to insemination as well as to the presence of semen. Results from this study may have direct implications on fertility rates as well as potential strategies for avian semen cryopreservation protocols.

Gamete-exporting organs of vertebrates: dazed and confused

Mature gametes are transported externally for fertilization. In vertebrates, the gonads are located within the coelom. Consequently, each species has specific organs for export, which often vary according to sex. In most vertebrates, sperm ducts and oviducts develop from the Wolffian and Müllerian ducts, respectively. However, exceptions exist. Both sexes of cyclostomes, as well as females of basal teleosts, lack genital ducts but possess genital pores. In teleosts of both sexes, genital ducts are formed through the posterior extensions of gonads. These structures appear to be independent of both Wolffian and Müllerian ducts. Furthermore, the development of Wolffian and Müllerian ducts differs significantly among various vertebrates. Are these gamete-exporting organs homologous or not? A question extensively debated around the turn of the 20th century but now largely overlooked. Recent research has revealed the indispensable role of Wnt4a in genital duct development in both sexes of teleosts: zebrafish and medaka. wnt4a is an ortholog of mammalian Wnt4, which has functions in Müllerian duct formation. These results suggest a potential homology between the mammalian Müllerian ducts and genital ducts in teleosts. To investigate the homology of gamete-exporting organs in vertebrates, more detailed descriptions of their development across vertebrates, using modern cellular and genetic tools, are needed. Therefore, this review summarizes existing knowledge and unresolved questions on the structure and development of gamete-exporting organs in diverse vertebrate groups. This also underscores the need for comprehensive studies, particularly on cyclostomes, cartilaginous fishes, basal ray-finned fishes, and teleosts.