Region-specific gene expression in the epididymis of Yak

Melatonin modulated GPX5 and PTGDS expression in Bactrian camel epididymis mainly via receptor MT1†

Melatonin (Mel), an important mediator of photoperiodic annual rhythm regulation and seasonal reproduction in animals, directly modulates the expression of specific genes in the epididymis and protects sperm from oxidative damage. Bactrian camel is a dominant species in desert and semi-desert areas, exhibiting the unique reproductive regulation patterns. However, the underlying regulation mechanism of Mel on Bactrian camel is still unclear. This study isolated the epididymal caput epithelial cells of Bactrian camels and investigated the expression of specific genes involving sperm protection after Mel treatment and overexpression/knockdown of Mel receptor MT1/MT2 using real-time quantitative PCR assay (qPCR), ELISA, and western blotting assay. The results showed that MT1, MT2, clock genes cryptochrome 1/2 (Cry1/Cry2) were all positively expressed in the epididymal lumen epithelial cells, peritubular myoid cells, and luminal spermatozoa. Intriguingly, Mel treatment activated receptor MT1 in epididymal caput epithelial cells, indicating that Mel treatment regulated genes expression mainly via MT1-dependent manner. Mel treatment or overexpression of MT1 both increased secretion of glutathione peroxidase 5 (GPX5) and prostaglandin D2 synthase (PTGDS), and MT1 silencing induced downregulation of GPX5 and PTGDS expression, indicating that the expression of GPX5 and PTGDS were regulated by Mel-MT1. Overexpression of MT1 or MT2 promoted Cry2 expression, and overexpression of Cry2 also activated the MT1/MT2 expression by feedback regulation. Finally, the double luciferase reports assay showed that the activation of MT1 by Cry2 occurred during transcription. These results help to understand the regulatory effect of Mel on the epididymis in Bactrian camels.

Yak DEFB123 alleviates lung injury caused by Klebsiella pneumoniae through MAPKs signaling pathway

Beta-defensins, such as β-defensin 123 (DEFB123), are vital components of the immune system's defense against infections due to their strong antimicrobial properties and capacity for modulating the body's immunological responses. In this study, we successfully cloned and analyzed the yak DEFB123 gene sequence. Subsequently, we obtained recombinant protein DEFB123 (rDEFB123) through prokaryotic expression. Our results demonstrate that rDEFB123 effectively inhibits the growth of Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus. Furthermore, rDEFB123 enhances the phagocytic activity of macrophages by regulating specific factors. In a mouse model infected with Klebsiella pneumoniae, the administration of rDEFB123 showed significantly lower levels of serum ALT and AST compared to the control group. Moreover, IFN-γ and IgG were significantly increased in the rDEFB123-treated groups, indicating an enhanced immune response. In the MAPKs signaling pathway of the infected mouse lungs, the expressions of JNK, TRAF2, TRAF6, MIF, and IL-1β genes were downregulated in the rDEFB123-treated groups. Moreover, the levels of p-JNK protein were significantly decreased in these groups as well. Klebsiella pneumoniae caused systemic infection with organ damage in mice. However, the administration of rDEFB123 suppressed the expressions of inflammatory factors, thereby mitigating organ injury and regulating the activity of apoptosis-related factors to enhance immunity. These findings provide valuable theoretical data for future exploration of the functionality and potential applications of DEFB123 in yak.

Analysis of histomorphology and SERNINA5 gene expression in different regions of epididymis of cattleyak

The molecular mechanism of sterility in cattleyak is still unresolved. The related factors of infertility in cattleyak were studied by tissue section, SERPINA5 gene cloning and bioinformatics technology. Tissue sections of the epididymis showed poorly structured and disorganized epithelial cells in the corpus of the epididymis compared to the caput of the epididymis, while in the cauda part of the epididymis, the extra basal smooth muscle was thinner, the surface of the epithelial lumen was discontinuous and the epithelium was markedly degenerated. The results of gene cloning showed that the coding sequence (CDS) region of the SERPINA5 gene in cattleyak was 1215 bp in length, encoding a total of 404 amino acids, of which the isoleucine content was the highest, accounting for a total of 49 amino acids (12.1%). The results of real-time fluorescence quantitative PCR (qPCR) showed that the expression of the SERPINA5 gene in the epididymis caput in cattleyak was significantly higher than that in the corpus and cauda (P < 0.05), but there were no significant differences between the corpus and cauda. In the current study, histological and bioinformatics analysis, physicochemical properties, and the expression analysis of the SERPINA5 gene in different regions of the epididymis in cattleyak were carried out to explore the biological complications of cattleyak infertility.

The expression spectrum of yak epididymal epithelial cells reveals the functional diversity of caput, corpus and cauda regions

Sperm undergo a series of changes in the epididymis region before acquiring the ability to move and fertilize, and the identification of genes expressed in a region-specific manner in the epididymis provides a valuable insight into functional differences between regions. We collected epididymal tissue from three yaks and cultured epithelial cells from the caput, corpus and cauda regions of the yak epididymis using the tissue block method. RNA sequencing analysis (RNA-seq) technology was used to detect gene expression in yak epididymal caput, corpus and cauda epithelial cells. The results showed that the DEGs were highest in the caput vs. corpus comparison, and lowest in the corpus vs. cauda comparison. Six DEGs were verified by real-time fluorescence quantitative PCR (qRT-PCR), consistent with transcriptome sequencing results. The significantly enriched DNA replication pathway in the caput vs. corpus was coordinated with cell proliferation, while upregulated DEGs such as POLD1 and MCM4 were found in the DNA replication pathway. The AMPK signaling pathway was found significantly enriched in the caput vs cauda, suggesting its involvement in sperm maturation and capacitation. The TGF beta signaling pathway was screened in the corpus vs cauda and is crucial for mammalian reproductive regulation. Upregulated DEGs (TGFB3, INHBA, INHBB) are involved in the TGF beta signaling pathway. This study provides a reference for culturing yak epididymal epithelial cells in vitro, and elucidates the transcriptional profiles of epithelial cells in different segments of the epididymis, revealing the regulatory and functional differences between different segments, providing basic data for exploring the molecular mechanism of yak sperm maturation and improving the reproductive capacity of high-altitude mammals.

Knockdown of EIF2AK2-OAS1 axis reduces ATP production inducing AMPK phosphorylation to inhibit the malignant behavior of gastric cancer cells

Energy metabolism has always been a hot topic in cancer progression and targeted therapy, and exploring the role of genes in energy metabolic pathways in cancer cells has become key to address this issue. Eukaryotic translation initiation factor 2α kinase 2 (EIF2AK2) plays regulatory roles in cancer and disorders of energy metabolism. Indeed, the role of EIF2AK2 in energy metabolism has been underestimated. The aim of this study is to reveal the expression specificity of EIF2AK2 in gastric cancer (GC) progression and metastasis, and to demonstrate the role of EIF2AK2 in energy metabolism, cytoskeleton, proliferation, death and metastasis pathways in GC cells. Mechanistically, EIF2AK2 overexpression promoted cytoskeleton remodeling and ATP production, mediated cell proliferation and metastasis, upregulated OAS1 expression, decreases p-AMPK expression and inhibited apoptosis in GC cells. Conversely, knockdown of EIF2AK2 resulted in the opposite effect. However, overexpression of OAS1 mediated the upregulation of mitochondrial membrane potential and promoted ATP production and NAD+/NADH ratio, but knockdown of OAS1 inhibited the above effects. In addition, knockdown of OAS1 had no effect on EIF2AK2 expression, but inhibited AMPK and upregulated p-AMPK expression. In conclusion, our study identified EIF2AK2 and OAS1 as previously undescribed regulators of energy metabolism in GC cells. We hypothesized that EIF2AK2-OAS1 axis may regulate energy metabolism and inhibit cellular malignant behavior in cancer cells by affecting ATP production to induce AMPK phosphorylation, suggesting EIF2AK2 as a potential therapeutic target for cancer cell progression.

Effects of microbiota-testis interactions on the reproductive health of male ruminants: A review

Ruminants are one of the world's economically important species, and their reproductive health is critical to the economic development of the livestock industry. In recent years, research on the relationship between microbiota and reproductive health has received much attention. Microbiota disruption affects the developmental health of the testes and epididymis, the male reproductive organs of the host, which in turn is related to sperm quality. Maintaining a stable microbiota protects the host from pathogens and increases breeding performance, which in turn promotes the economic development of animal husbandry. In addition, the effects and mechanisms of microbiota on reproduction were further explored. These findings support new approaches to improving and managing reproductive health in ruminants through the microbiota and facilitate further systematic exploration of microbiota-mediated reproductive impacts.

A Single-Cell Landscape of Spermioteleosis in Mice and Pigs

(1) Background: Spermatozoa acquired motility and matured in epididymis after production in the testis. However, there is still limited understanding of the specific characteristics of sperm development across different species. In this study, we employed a comprehensive approach to analyze cell compositions in both testicular and epididymal tissues, providing valuable insights into the changes occurring during meiosis and spermiogenesis in mouse and pig models. Additionally, we identified distinct gene expression signatures associated with various spermatogenic cell types. (2) Methods: To investigate the differences in spermatogenesis between mice and pigs, we constructed a single-cell RNA dataset. (3) Results: Our findings revealed notable differences in testicular cell clusters between these two species. Furthermore, distinct gene expression patterns were observed among epithelial cells from different regions of the epididymis. Interestingly, regional gene expression patterns were also identified within principal cell clusters of the mouse epididymis. Moreover, through analysing differentially expressed genes related to the epididymis in both mouse and pig models, we successfully identified potential marker genes associated with sperm development and maturation for each species studied. (4) Conclusions: This research presented a comprehensive single-cell landscape analysis of both testicular and epididymal tissues, shedding light on the intricate processes involved in spermatogenesis and sperm maturation, specifically within mouse and pig models.

Sulforaphane reduces adipose tissue fibrosis via promoting M2 macrophages polarization in HFD fed-mice

Adipose tissue fibrosis has been identified as a novel contributor to the pathomechanism of obesity associated metabolic disorders. Sulforaphane (SFN) has been shown to have an anti-obesity effect. However, the impact of SFN on adipose tissue fibrosis is still not well understood. In this study, obese mice induced by high-fat diets (HFD) were used to examine the effects of SFN on adipose tissue fibrosis. According to the current findings, SFN dramatically enhanced glucose tolerance and decreased body weight in diet-induced-obesity (DIO) mice. Additionally, SFN therapy significantly reduced extracellular matrix (ECM) deposition and altered the expression of genes related to fibrosis. Furthermore, SFN also reduced inflammation and promoted macrophages polarization towards to M2 phenotype in adipose tissue, which protected adipose tissue from fibrosis. Notably, SFN-mediated nuclear factor E2-related factor 2 (Nrf2) activation was crucial in decreasing adipose tissue fibrosis. These results implied that SFN had favorable benefits in adipose tissue fibrosis, which consequently ameliorates obesity-related metabolic problems. Our research provides new treatment strategies for obesity and associated metabolic disorders.

Expression and role of melatonin membrane receptors in the hypothalamic-pituitary-testicular axis of Tibetan sheep in a plateau pastoral area

MTNR1A and MTNR1B, two high-affinity MT membrane receptors found in mammals, mediate the activity of MT on the HPGA to regulate animal reproduction. Nevertheless, the expression patterns and function of the MTNR1A and MTNR1B genes in the HPTA of seasonal estrus sheep and perennial estrus sheep have not been elucidated. We studied the expression of MTNR1A and MTNR1B in the hypothalamic-pituitary-testicular axis (HPTA) of Tibetan sheep at different reproductive stages using histochemistry, enzyme linked immunosorbent assay (ELSIA), scanning electron microscopy, transmission electron microscopy, quantitative Real-time PCR (qRT-PCR), and Western blot (WB), and analyzed the relationship between their expression and reproductive hormone receptors. We also compared relevant characteristics between seasonal Tibetan sheep and non-seasonal Small Tail Han sheep in the same pastoral area. The results showed that MTNR1A and MTNR1B were expressed in all tissues of the Tibetan sheep HPTA, and both were co-expressed in the cytoplasm of epididymis basal and halo cells located at common sites of the epididymis basement membrane, forming an immune barrier. The qRT-PCR analysis showed that not only MTNR1A but also N-acetyltransferase (AANAT), hydroxyindole-oxygen- methyltransferase (HIOMT), androgen receptor (AR), and estrogen receptor α (ERα) mRNA expression was significantly upregulated in the testis and epididymis of Tibetan sheep during the breeding season, whereas no clear upregulation of these genes was observed in the tissues of Small Tail Han sheep. MTNR1A and MTNR1B are important regulators of the HPTA in sheep. MTNR1A mediates seasonal estrus regulation in Tibetan sheep. Both MTNR1A and MTNR1B may play important roles in formation of the blood-epididymal barrier. The results of this study should help advance research on the mechanism of reproductive regulation of the HPTA in male animals and provide reference data for improving the reproductive rate of seasonal breeding animals.

Polymorphisms Analysis of BMP15, GDF9 and BMPR1B in Tibetan Cashmere Goat (Capra hircus)

The Tibetan cashmere goat is a prolific goat breed in China. In sheep breeds, natural mutations have demonstrated that the transforming growth factor beta (TGF-β) super family ligands, such as growth differentiation factor 9 (GDF9), bone morphogenetic protein 15 (BMP15) and their type I receptor (bone morphogenetic protein receptor (BMPR1B), are essential for ovulation and increasing litter size. In this study, 216 female Tibetan cashmere goats were sampled, and candidate genes with fecundity traits were detected via restriction fragment length polymorphism (RFLP) and sequenced. Four polymorphic loci were found in specific amplification fragments of BMP15 and GDF9. Two SNP sites of the BMP15 gene were discovered, namely G732A and C805G. The G732A mutation did not cause the change in amino acids, and the frequencies of each genotype were 0.695 for the GG type, 0.282 for the GA type and 0.023 for the AA type. The C805G mutation caused amino acids to change from glutamine to glutamate. The genotype frequencies were 0.620 for the CC type, 0.320 for the CG type and 0.320 for the CG type. For the GG type 0.060, the G3 and G4 mutations of the GDF9 gene were all homozygous mutations. Two known SNP sites, C719T and G1189A, were detected in the Tibetan cashmere goat GDF9 gene, of which the C719T mutation caused a change of alanine to valine, with a genotype frequency of 0.944 for the CC type and 0.056 for the CT type, whereas no TT type was found. The G1189A mutation caused valine to become isoleucine, and the frequencies of each genotype were 0.579 for the GG type, 0.305 for the GA type and 0.116 for the AA type; G1, B2, B3, B4, FecX^H, FecX^I, FecX^L, G2, G5, G6, G7, G8, FecG^E, FecTT and FecB mutations were not found in Tibetan cashmere goats. The results of this study provide a data basis for future studies of BMP15, GDF9 and BMPR1B gene mutations in goats.

Identification and Functional Assignment of Genes Implicated in Sperm Maturation of Tibetan Sheep

While traveling through the epididymis, immature sheep spermatozoa undergo a sequence of processes that ultimately give them the capacity to swim and fertilize an egg. Different gene expression patterns may be found in the epididymal caput, corpus, and cauda, conferring variant or unique biological roles during epididymis development and sperm maturation. To search for candidate genes associated with ovine sperm maturation and assess their possible modulating mechanisms, we characterized gene expression in each epididymal segment derived from pre- and post-pubertal Tibetan sheep by RNA sequencing. Compared with pre-puberty, 7730 (3724 upregulated and 4006 downregulated), 7516 (3909 upregulated and 3607 downregulated), and 7586 (4115 elevated and 3471 downregulated) genes were found to be differentially expressed in the post-pubertal caput, corpus, and cauda epididymis, respectively, and real-time quantitative PCR verified the validity of the gathered expression patterns. Based on their functional annotations, most differential genes were assigned to the biological processes and pathways associated with cellular proliferation, differentiation, immune response, or metabolic activities. As for the post-pubertal epididymis, 2801, 197, and 186 genes were specifically expressed in the caput, corpus, and cauda, respectively. Functional annotation revealed that they were mainly enriched to various distinct biological processes associated with reproduction (including the caput binding of sperm to the zona pellucida; fertilization in the caput and corpus; and meiosis in the caput and cauda) and development (such as cell differentiation and developmental maturation in the caput; cell proliferation and metabolism in the corpus; and regulation of tube size and cell division/cell cycle in the cauda). Additionally, we focused on the identification of genes implicated in immunity and sperm maturation, and subsequent functional enrichment analysis revealed that immune-related genes mainly participated in the biological processes or pathways associated with the immune barrier (such as JAM3 and ITGA4/6/9) and immunosuppression (such as TGFB2, TGFBR1, TGFBR2, and SMAD3), thus protecting auto-immunogenic spermatozoa. Additionally, sperm maturation was mostly controlled by genes linked with cellular processes, including cell growth, proliferation, division, migration, morphogenesis, and junction. Altogether, these results suggest that most genes were differentially expressed in developmental epididymal regions to contribute to microenvironment development and sperm maturation. These findings help us better understand the epididymal biology, including sperm maturation pathways and functional differences between the epididymal regions in Tibetan sheep and other sheep breeds.

Review: The role of male reproductive tract secretions in ruminant fertility

Male fertility largely depends on the ability to produce sperm that can transmit the paternal information onto the next generation. However, the factors that are critical for sperm function and the subsequent development of healthy offspring are still not completely understood in ruminants. Importantly, sperm function is not completely encoded by germ cell DNA, but rather, depends on sequential acquisition, loss, and modification of elements through interaction with secretions from the testes, epididymides, and accessory glands (collectively termed seminal plasma). In addition, these secretions can play a role in the inheritance of paternal environmental effects by progeny. This is likely achieved directly, by the regulation of sperm epigenetic effectors, and indirectly, by altering the female environment in which the individual develops. This review will provide an overview of the different organs that contribute to seminal plasma in ruminants, and summarise how their secretions shape sperm function and modulate the female reproductive tract. Finally, some consideration will be given to the potential of paternal factors to affect embryo development and offspring health in ruminants.

Comparative Analysis of Epididymis Cauda of Yak before and after Sexual Maturity

Epididymis development is the basis of male reproduction and is a crucial site where sperm maturation occurs. In order to further understand the epididymal development of yak and how to regulate sperm maturation, we conducted a multi-omics analysis. We detected 2274 differential genes, 222 differential proteins and 117 co-expression genes in the cauda epididymis of yak before and after sexual maturity by RNA-seq and proteomics techniques, which included TGFBI, COL1A1, COL1A2, COL3A1, COL12A1, SULT2B1, KRT19, and NPC2. These high abundance genes are mainly related to cell growth, differentiation, adhesion and sperm maturation, and are mainly enriched via extracellular matrix receptor interaction, protein differentiation and absorption, and lysosome and estrogen signaling pathways. The abnormal expression of these genes may lead to the retardation of epididymal cauda development and abnormal sperm function in yak. In conclusion, through single and combined analysis, we provided a theoretical basis for the development of the yak epididymal cauda, sperm maturation, and screening of key genes involved in the regulation of male yak reproduction.

Morphological and histochemical identification of telocytes in adult yak epididymis

Telocytes (TCs) are a newly discovered type of mesenchymal cell that are closely related to the tissue's internal environment. The study aimed to investigate the morphological identification of TCs in the epididymis of adult yak and their role in the local microenvironment. In this study, transmission electron microscopy (TEM), scanning electron microscopy, immunofluorescence, qRT-PCR, and western blotting were used to analyze the cell morphology of TCs. The results showed that there are two types of TCs in the epididymal stroma of yak by TEM; one type is distributed around the capillaries with full cell bodies, longer TPs, and a large number of secretory vesicles; the other is distributed outside the basement membrane with irregularly long, striped, large nuclei and short telopodes (TPs). In addition, these TCs formed complex TC cell networks through TPs with epididymal interstitial capillaries and basal fibroblasts. TCs often appear near the capillaries and basement membrane by special staining. The surface markers of TCs (CD34, vimentin, and CD117) were positively expressed in the epididymal stroma and epithelium by immunohistochemistry, and immunofluorescence co-expression of vimentin + CD34 and CD117 + CD34 was observed on the surface of TCs. The trends in the mRNA and protein expression of TCs surface markers revealed expression was highest in the caput epididymis. In summary, this is first report of TCs in the epididymis of yak, and two phenotypes of TCs were observed. The existence and distribution characteristics of TCs in the epididymis of plateau yaks provide important clues for further study of the adaptation to reproductive function in the plateau.

Effect of C-Type Natriuretic Peptide (CNP) on Spermatozoa Maturation in Adult Rat Epididymis

C-type natriuretic peptide (CNP) is highly expressed in male reproductive tissues, such as the epididymis. The aim of this study is to explore the role of CNP in the maturation of rat epididymal spermatozoa. First, the expression levels of CNP and its specific natriuretic peptide receptor-B (NPR-B) were detected in various tissues of rats and epididymis at different stages after birth. Then a castrated rat model was established to analyze the relationship between testosterone and CNP/NPR-B expression in the epididymis. Finally, CNP and different inhibitors (NPR-B inhibitors, cGMP inhibitors) were used to incubate epididymal sperm in vitro to examine sperm mobility and expression of sperm maturation-related factors. The results showed CNP/NPR-B mRNAs were expressed in all tissues of rats, but were extremely highly expressed in male genital ducts (seminal vesicle, prostate and epididymis). The expression of CNP/NPR-B in epididymis was the highest at birth and the fifth week after birth. In the epididymis, CNP/NPR-B were highly expressed in the caput and located in the epididymal epithelial cells. After castration, the expression of CNP/NPR-B decreased sharply and was restored quickly after testosterone supplementation. In vitro, CNP could significantly promote the acquisition of epididymal sperm motility through the NPR-B/cGMP pathway and induce the expression of sperm maturation-related factors (such as Bin1b, Catsper 1, Dnah17, Fertilin). This study shows that CNP plays a role in epididymal sperm maturation. The mechanism of CNP is to promote the acquisition of epididymal sperm fluidity through the NPR-B/cGMP signaling pathway and also to regulate sperm maturation-related genes. Moreover, the expression of CNP/NPR-B was regulated by testosterone.

Beta-defensins as marker for male fertility: a comprehensive review†

Bovine male fertility in animals has a direct impact on the productivity of dairy herds. The epididymal sperm maturations involve extensive sperm surface modifications to gain the fertilizing ability, especially by absorptions of the plethora of biomolecules, including glycoprotein beta-defensins (BDs), enzymes, organic ions, protein, and phospholipids. Defensins are broad-range nonspecific antimicrobial peptides that exhibit strong relations with innate and adaptive immunity, but their roles in male fertility are relatively recently identified. In the course of evolution, BD genes give rise to different clusters with specific functions, especially reproductive functions, by undergoing duplications and nonsynonymous mutations. BD polymorphisms have been reported with milk compositions, disease resistance, and antimicrobial activities. However, in recent decades, the link of BD polymorphisms with fertility has emerged as an appealing improvement of reproductive performance such as sperm motility, membrane integrity, cervical mucus penetration, evading of uterus immunosurveillance, oviduct cell attachment, and egg recognition. The reproductive-specific glycosylated BD class-A BDs (CA-BDs) have shown age- and sex-specific expressions in male reproductive organs, signifying their physiological pleiotropism, especially in the sperm maturation and sperm transport in the female reproductive tract. By considering adult male reproductive organ-specific BD expressions, importance in sperm functionalities, and bioinformatic analysis, we have selected two bovine BBD126 and BBD129 genes as novel potential biomarkers of bovine male fertility. Despite the importance of BDs, however, genomic characterization of most BD genes across most livestock and nonmodel organisms remains predictive/incomplete. The current review discusses our understanding of BD pleiotropic functions, polymorphism, and genomic structural attributes concerning the fertilizability of the male gamete in dairy animals.

Comparative iTRAQ proteomics identified proteins associated with sperm maturation between yak and cattleyak epididymis

Background

During maturation, spermatozoa acquire motility and fertilizing capacity as they transit through the epididymis. In recent years, two-dimensional gel electrophoresis has been employed in proteomics studies conducted in rat, boar and human. However, there has not been a complete information regarding the proteins associated with sperm maturation in the epididymis. In this study, we employed iTRAQ proteomics to investigate proteins associated with sperm maturation between yak and cattleyak epididymis.

Results

After a successful sampling and protein extraction, the iTRAQ coupled with LC-MS/MS mass spectrometry and bioinformatics analysis were performed. We identified 288 differentially abundant proteins (DAPs) between yak and cattleyak epididymis; 151 were up-regulated while 137 were down-regulated in cattleyak relative to yak. Gene Ontology analysis identified that down-regulated DAPs in cattleyak were mostly enriched in the acetylation of protein component, along with negative and positive regulatory activities. iTRAQ proteomics data showed that the top up-regulated DAPs were mainly enriched in cell communication, cell adhesion, cytoskeleton organization, stress response, post-translational modifications and metabolic functions while the down-regulated DAPs were predominantly associated with sperm maturation, long-term sperm storage, sperm forward motility, sperm-oocyte fusion and regulatory functions.

Conclusion

These results provide insight into the molecular mechanisms underlying male cattleyak sterility.

Study of microRNA Expression Profile in Different Regions of Ram Epididymis

The regional expression of epididymal genes provides a guarantee for sperm maturation. As a class of endogenous non-coding small RNAs, microRNAs (miRNAs) play an important role in spermatogenesis, maturation and fertilization. Currently, the regulatory role of miRNA in the epididymis is poorly understood. Here, transcriptome sequencing was used to analyse miRNA expression profiles in three regions of the epididymis of rams, including caput, corpus and cauda. The results showed that there were 13 known miRNAs between the caput and corpus controls, 29 between the caput and cauda and 22 differences between the corpus and cauda. Based on the analysis of miRNA target genes by GO and KEGG, a negative regulation network of miRNA-mRNA was constructed in which let-7, miR-541-5p, miR-133b and miR-150 may play an important regulatory role in the maturation regulation of ram epididymal sperm. This research provides a reference for studying the regulation mechanism of sperm maturation in male epididymis and improving semen quality and male reproductive performance.

Next-generation sequencing analysis reveals segmental patterns of microRNA expression in yak epididymis

MicroRNAs (miRNAs) have emerged as potent regulators of gene expression and are widely expressed in biological systems. In reproduction, they have been shown to have a significant role in the acquisition and maintenance of male fertility, whereby deletion of Dicer in mouse germ cells leads to infertility. Evidence indicates that this role of miRNAs extends from the testis into the epididymis, controlling gene expression and contributing to regional variations in gene expression. In this study, RNA sequencing technology was used to investigate miRNA expression patterns in the yak epididymis. Region-specific miRNA expression was found in the yak epididymis. In all, 683 differentially expressed known miRNAs were obtained; 190, 186 and 307 differentially expressed miRNAs were identified for caput versus corpus, corpus versus cauda and caput versus cauda region pairs respectively. Kyoto Encyclopedia of Genes and Genomes results showed endocytosis as the most enriched pathway across region pairs, followed by protein processing in the endoplasmic reticulum, phagosome, spliceosome and biosynthesis of amino acids in region pair-specific hierarchical order. Gene ontology results showed varied enrichment in terms including cell, biogenesis, localisation, binding and locomotion across region pairs. In addition, significantly higher miR-34c expression was seen in the yak caput epididymidis relative to the corpus and cauda epididymidis.

High-throughput sequencing reveals differential expression of miRNAs in yak and cattleyak epididymis

Cattleyaks (CY) are interspecific hybrids between cattle (Bos taurus) and yak (Bos gruniens, YK) exhibiting the same prominent adaptability and higher performances than YK. MiRNAs have played an important role in the acquisition and maintenance of male fertility in reproduction, where deletion of Dicer in mice germ cells results in infertility. According to a body of evidence, the function of miRNA in the male reproductive system extends from the testis into the epididymis and, as such, regulates gene expression and contributes to regional gene expression variations. Using RNA sequencing on biological replicates, we described differentially expressed miRNAs profiles for tissue from epididymis of YK and CY. In the present study, High-throughput sequencing analysis showed that 55 differentially expressed (DE) miRNAs were identified in the epididymis of YK and CY. Among these, 43 DE miRNAs were upregulated while the remaining 12 DE miRNAs were downregulated between epididymis of YK and CY. Our results showed that the top most important DE miRNAs, bta-miR-449c, bta-miR-539, bta-miR-136, bta-miR-504, bta-miR-31 and bta-miR-222 were found to be involved in the reproductive system of CY. In addition, some targeted genes, Clusterins (CLU), Retinoic Acid Receptor a (RARa) and Hydroxy acyl glutathione Hydrolase (HAGH) and HSPH1 targeted by bta-miR-2411-3p and bta-miR-1298 were involved in the sperm motility, sperm morphology and post-testicular sperm maturation. Furthermore, GO and KEGG analyses were performed to classify the functions of target genes for DE miRNAs. In addition, RT-qPCR validation of the DE miRNAs and its targeted genes revealed that putative miRNAs are involved in the male CY infertility by altering the gene expression. Present findings may not only increase our understanding of the molecular mechanisms regulated by the miRNAs in epididymis, but also provide a valuable information to understand the male infertility mechanism of CY.

Study on the region-specific expression of epididymis mRNA in the rams

The epididymis is divided into three regions including the caput, corpus and cauda. Gene expression profiles in different regions indicate the different functions of epididymis which are crucial for sperm maturation. In this study, three one-year-old rams was used as the experimental animal. Transcriptome sequencing technology was used to sequence mRNA in the caput, corpus and cauda of the epididymis. Based on the spatiotemporal-specific expression pattern in the epididymis, the mRNA expression profiles of the three parts of the epididymis were analysed. Region-specifically expressed genes were analysed by GO and KEGG analyses to screen the key genes involved in sheep sperm maturation. We obtained 129, 54 and 99 specifically expressed genes in the caput, corpus and cauda, respectively. And twenty specific expressed genes related to sperm maturation were used to construct functional networks. The heatmap showed that 6 genes of LCN protein family were highly expressed in the head of epididymis of sheep. We infer that sperm maturation is gradual in the epididymis and that there are significant differences in epididymal gene expression patterns between different species. This provides a data resource for analysing the regulatory mechanism of epididymis genes related to sperm maturation in rams.

Litter Size of Sheep (Ovis aries): Inbreeding Depression and Homozygous Regions

Ovine litter size (LS) is an important trait showing variability within breeds. It remains largely unknown whether inbreeding depression on LS exists based on genomic homozygous regions, and whether the homozygous regions resulted from inbreeding are significantly associated with LS in sheep. We here reanalyze a set of single nucleotide polymorphism (SNP) chip of six breeds to characterize the patterns of runs of homozygosity (ROH), to evaluate inbreeding levels and inbreeding depressions on LS, and to identify candidate homozygous regions responsible for LS. Consequently, unique ROH patterns were observed among six sheep populations. Inbreeding depression on LS was only found in Hu sheep, where a significant reduction of 0.016, 0.02, and 0.02 per 1% elevated inbreeding FROH4-8, FROH>8 and the total inbreeding measure was observed, respectively. Nine significantly homozygous regions were found for LS in Hu sheep, where some promising genes for LS possibly via regulation of the development of oocytes (NGF, AKT1, and SYCP1), fertilization (SPAG17, MORC1, TDRD9, ZFYVE21, ADGRB3, and CKB), embryo implantation (PPP1R13B, INF2, and VANGL1) and development (DPPA2, DPPA4, CDCA4, CSDE1, and ADSSL1), and reproductive health (NRG3, BAG5, CKB, and XRCC3) were identified. These results from the present study would provide insights into the genetic management and complementary understandings of LS in sheep.

Comparative rna-seq analysis of region-specific miRNA expression in the epididymis of cattleyak

The epididymis is the site of post-testicular sperm maturation, which constitutes the acquisition of sperm motility and the ability to recognize and fertilize oocytes. The role of miRNA in male reproductive system, including the control of different steps leading to proper fertilization such as gametogenesis, sperm maturation and maintenance of male fertility where the deletion of Dicer in mouse germ cells led to infertility, has been demonstrated. The identification of miRNA expression in a region-specific manner will therefore provide valuable insight into the functional differences between the regions of the epididymis. In this study, we employed RNA-seq technology to explore the expression pattern of miRNAs and establish some miRNAs of significant interest with regard to epididymal sperm maturation in the CY epididymis. We identified a total of 431 DE known miRNAs; 119, 185 and 127 DE miRNAs were detected for caput versus corpus, corpus versus cauda and caput versus cauda region pairs, respectively. Our results demonstrate region-specific miRNA expression in the CY epididymis. The GO and KEGG enrichment for the predicted target genes indicated the functional values of miRNAs. Furthermore, we observed that the expression of miR-200a was downregulated in the caput, compared with cauda. Since the family of miR-200 has previously been suggested to contribute to the distinct physiological function of sperm maturation in epididymis of adult rat, we speculate that the downregulation of miR-200a in CY caput epididymis may play an important role of sperm maturation in the epididymis of CY. Therefore, our findings may not only increase our understanding of the molecular mechanisms regulated by the miRNA functions in region-specific miRNA expression in the CY epididymis, it could provide a valuable information to understand the mechanism of male infertility of CY.

Analysis of long non-coding RNAs in epididymis of cattleyak associated with male infertility

Cattleyak (CY), is a cross breed between cattle and yak (YK), which display equal adaptability to the harsh environment as YK and much higher performances than YK. However, the CY is female fertile and male sterile. Previous studies were conducted on testes tissues to investigate the mechanism of male infertility in CY. There is no systematic research on genes, especially lncRNAs between CY and YK epididymis. In this study, Illumina Hiseq was performed to profile the epididymis transcriptome (lncRNA and mRNA) of CY and YK. In total 18859 lncRNAs were identified, from which lincRNAs 12458, antisense lncRNAs 2345, intronic lncRNAs 3101, and sense lncRNAs 955 respectively. We have identified 345 DE lncRNAs and 3008 DE mRNAs between YK and CY epididymis. Thirteen DEGs were validated by quantitative real-time PCR. Combing with DEG, 14 couples of lncRNAs and their target genes were both DE, and 6 of them including CCDC39, KCNJ16, NECTIN2, MRPL20, PSMC4, and DEFB112 show their potential infertility-related terms such as cellular motility, sperm maturation, sperm storage, cellular junction, folate metabolism, and capacitation. On the other hand, several down-regulated genes such as DEFB124, DEFB126, DEFB125, DEFB127, DEFB129, CES5A, TKDP1, CST3, RNASE9 and CD52 in CY compared to YK were involved in the immune response and sperm maturation. Therefore, comprehensive analysis for lncRNAs and their target genes may enhance our understanding of the molecular mechanisms underlying the process of sperm maturation in CY and may provide important resources for further research.

Distinct expression and localization patterns of HSP70 in developmental reproductive organs of rams

Heat shock protein 70 (HSP70) has been widely reported to play a vital role in maintaining intracellular homeostasis, mainly through cellular protection and immune regulation. The expression and function of HSP70 can vary depending upon species and age. To explore the expression signatures and regulatory functions of HSP70 in the reproductive organs of male sheep, we evaluated the expression and distribution patterns of HSP70 in the testes and epididymides (caput, corpus, and cauda) of Tibetan sheep at three developmental stages (i.e., 3 months, 1 year and 3 years after birth) by qRT-PCR, Western blot and immunofluorescence. HSP70 was found to be expressed in testes, caput, corpus, and cauda epididymides throughout the developmental stages but is mainly expressed postpuberty (1 year and 3 years old). Immunofluorescence results revealed that in the testes, a positive reaction for HSP70 protein was mainly seen in round spermatids and luminal sperms from the groups aged 1 year and 3 years. In caput epididymides, the positive signals for HSP70 protein was notably observed in sperm and principal cells of the epididymal epithelium from the groups aged 1 year and 3 years, and positive signals in the epididymal interstitium were found in all three age groups. In corpus and cauda epididymides, HSP70 protein was present in the epididymal epithelium and interstitium, and the positive signals gradually increased with age. In conclusion, these findings suggest that Tibetan sheep HSP70 may play a crucial role in further development and maturation of postmeiotic germ cells and participate in regulation of intraepididymal homeostasis maintenance in Tibetan sheep.