Subfertile bulls may cause huge economic losses in dairy production since their semen could be used to inseminate thousands of cows by artificial insemination. This study adopted whole-genome enzymatic methyl sequencing and aimed to identify candidate DNA methylation markers in bovine sperm that correlate with bull fertility. Twelve bulls were selected (High Bull Fertility = 6; Low Bull Fertility = 6) based on the industry’s internally used Bull Fertility Index (BFI). After sequencing, a total of 450 CpG had a DNA methylation difference higher than 20% (q<0.01) had been screened. The sixteen most significant differentially methylated regions(DMRs) were identified using a 10% methylation difference cut-off (q<5.88x10-16). Interestingly, most of the differentially methylated cytosines (DMCs) and DMRs were distributed on the X and Y chromosomes, demonstrating that the sex chromosomes play essential roles in bull fertility. Additionally, the functional classification showed that the beta-defensin family, zinc finger protein family, and olfactory and taste receptors could be clustered. Moreover, the enriched G protein-coupled receptors such as neurotransmitter receptors, taste receptors, the olfactory receptor family, and ion channels indicated that the acrosome reaction and capacitation processes are pivotal for bull fertility. In conclusion, this study identified the sperm-derived bull fertility-associated DMRs and DMCs at the whole genome level, which could complement and integrate into the existing genetic evaluation methods, increasing our decisive capacity to select good bulls and explain bull fertility better in the future.
Ying Zhang, Camila Bruna de Lima, Rémi Labrecque, and Marc-Andre Sirard
Yan Feng, Zhaowei Zhong, Haifu Wan, Ziping Zhang, Pengfei Zou, Peng Lin, Yonghua Jiang, and Yilei Wang
In brief
dmrtb1 performs critical functions in sex determination/differentiation and gonadal development in many organisms, but its role in teleost is rarely studied. Through gene cloning, in situ hybridization, and RNA interference technology, the function of dmrtb1 in testicular development of large yellow croaker (Larimichthys crocea) was studied; our study will be helpful in understanding further the molecular regulation mechanism of Lcdmrtb1/Lcdmrt6 in testicular development in L. crocea, and our results enrich the theory of fish dmrts involved in reproductive regulation and provide a new idea for sex control breeding of L. crocea by manipulating reproductive pathway.
Abstract
Doublesex- and mab-3-related transcription factor B1 (dmrtb1/dmrt6) belongs to one of the members of DMRT family, which performs critical functions in sex determination and differentiation, gonadal development, and functional maintenance. However, knowledge of its exact mechanism remains unclear in teleost. Very little is known about the role of dmrtb1 in the gonad development of Larimichthys crocea. In this study, a dmrtb1 homolog in L. crocea named as Lcdmrtb1 with the full-length cDNA was isolated and characterized. Except for the conserved DM domain, the other regions had low homology. Of the tissues sampled, Lcdmrtb1 was only found to be highly expressed in the testis. In situ hybridization of testis revealed Lcdmrtb1 in both spermatogonia and spermatocytes. After Lcdmrtb1 interference in the testis cells (LYCT) of L. crocea, the expression levels of Lcdmrtb1 and Lcdmrt1 were significantly decreased; subsequently, testicular cell morphology changed from fibrous to round and their growth rate slowed. Similarly, the expression levels of Lcdmrtb1, Lcdmrt1, sox9a/b, and amh were significantly decreased after RNAi in the testis. Furthermore, it was discovered that the spermatogonia had disappeared, and the Sertoli cells had been reduced. The results of immunohistochemistry showed that the expression of Sox9 protein in the testis was not detected after dmrtb1 was knocked down. These results indicated that the absence of Lcdmrtb1 not only greatly inhibited cell growth and destroyed the morphology of testis cells but also down-regulated Lcdmrt1 expression in the testis. This study will be helpful in understanding further the molecular regulation mechanism of Lcdmrtb1/Lcdmrt6 in testicular development in L. crocea.
Shang Wang and Irina V Larina
In brief
In vivo imaging of gametes and embryos in the oviduct enables new studies of the native processes that lead to fertilization and pregnancy. This review article discusses recent advancements in the in vivo imaging methods and insights which contribute to understanding the oviductal function.
Abstract
Understanding the physiological dynamics of gametes and embryos in the fallopian tube (oviduct) has significant implications for managing reproductive disorders and improving assisted reproductive technologies. Recent advancements in imaging of the mouse oviduct in vivo uncovered fascinating dynamics of gametes and embryos in their native states. These new imaging approaches and observations are bringing exciting momentum to uncover the otherwise-hidden processes orchestrating fertilization and pregnancy. For mechanistic investigations, in vivo imaging in genetic mouse models enables dynamic phenotyping of gene functions in the reproductive process. Here, we review these imaging methods, discuss insights recently revealed by in vivo imaging, and comment on emerging directions, aiming to stimulate new in vivo studies of reproductive dynamics.
Meng Bao, Qiwen Feng, Liping Zou, Jin Huang, Changhong Zhu, and Wei Xia
In brief
Intrauterine adhesion (IUA) is one of the main causes of female infertility. This study reveals that endoplasmic reticulum stress activation upregulates the TGF-β/SMAD pathway to induce epithelial–mesenchymal transition and promote endometrial fibrosis in an IUA model.
Abstract
IUA is a common gynecological disease and is a leading cause of female infertility. Mechanical or infectious damage to the endometrial basal layer can lead to endometrial fibrosis, which is the most common cause of IUA. Endoplasmic reticulum stress (ERS), the transforming growth factor beta signaling pathway (TGF-β/SMAD) and epithelial–mesenchymal transition (EMT) are important factors promoting endometrial fibrosis. The purpose of this study was to determine the up- and downstream regulatory relationships of the above three in the process of endometrial fibrosis. The rat IUA model was induced by double injury method and prophylactic injection of the ERS inhibitor 4-phenylbutyric acid (4-PBA) was given in vivo. The ERS activator tunicamycin and the TGF-β/SMAD pathway inhibitor A 83-01 were used in human endometrial epithelial cells (HEECs) in vitro. Masson’s trichrome, Sirius red staining, immunohistochemistry, immunofluorescence and Western blot analyses were used to determine ERS, TGF-β/SMAD pathway, EMT and fibrosis markers in the uterine tissue and HEECs of the different treatment groups. In animal experiments, ERS and the TGF-β/SMAD pathway had been activated and EMT occurred in an in vivo model of IUA but was suppressed in animals treated with prophylactic 4-PBA. In in vitro experiments, tunicamycin-treated HEECs had increased the activation of ERS, the abundance of TGF-β/SMAD pathway and fibrosis markers while EMT occurred, but the TGF-β/SMAD pathway and EMT were significantly inhibited in the tunicamycin+A 83-01 group. Our data suggest that increased ERS can induce EMT and promote endometrial fibrosis through the TGF-β/SMAD pathway.
Xue-Yun Qin, Hui-Hui Shen, Xin-Yan Zhang, Xing Zhang, Feng Xie, Wen-Jun Wang, Yu Xiong, Jie Mei, and Ming-Qing Li
Infiltration and residence of decidual macrophage (dM) are of great significance to pregnancy maintenance for its role in angiogenesis, placental development and inducing immune tolerance. Besides, hypoxia has now been acknowledged as an important biological event at maternal-fetal interface in the first trimester. However, whether and how hypoxia regulates biofunctions of dM remains elusive. Herein, we observed increased expression of C-C motif chemokine ligand 2 (CCL2) and residence of macrophages in decidua when comparing to secretory-phase endometrium. Moreover, hypoxia treatment on stromal cells improved migration and adhesion of dM. Mechanistically, these effects might be mediated by upregulated CCL2 and adhesion molecules (especially ICAM2 and ICAM5) on stromal cells in the presence of endogenous vascular endothelial growth factor-A (VEGFA) in hypoxia. These findings were also verified by recombinant VEGFA and indirect coculture, indicating the interaction between stromal cells and dM in hypoxia condition may facilitate dM recruitment and residence. In conclusion, VEGFA derived from hypoxic environment may manipulate CCL2/CCR2 and adhesion molecules to enhance the interactions between dM and stromal cells and thus contribute to the enrichment of macrophages in decidua during early normal pregnancy.
Geneviève Genest, Shorooq Banjar, Walaa Almasri, Coralie Beauchamp, Joanne Benoit, William Buckett, Frederick Dzineku, Phil Gold, Michael H Dahan, Wael Jamal, Isaac Jacques Kadoch, Einav Kadour-Peero, Louise Lapensée, Pierre Miron, Talya Shaulov, Camille Sylvestre, Togas Tulandi, Bruce D Mazer, Carl A Laskin, and Neal Mahutte
In brief
Immune dysfunction may contribute to or cause recurrent implantation failure. This article summarizes normal and pathologic immune responses at implantation and critically appraises currently used immunomodulatory therapies.
Abstract
Recurrent implantation failure (RIF) may be defined as the absence of pregnancy despite the transfer of ≥3 good-quality blastocysts and is unexplained in up to 50% of cases. There are currently no effective treatments for patients with unexplained RIF. Since the maternal immune system is intricately involved in mediating endometrial receptivity and embryo implantation, both insufficient and excessive endometrial inflammatory responses during the window of implantation are proposed to lead to implantation failure. Recent strategies to improve conception rates in RIF patients have focused on modulating maternal immune responses at implantation, through either promoting or suppressing inflammation. Unfortunately, there are no validated, readily available diagnostic tests to confirm immune-mediated RIF. As such, immune therapies are often started empirically without robust evidence as to their efficacy. Like other chronic diseases, patient selection for immunomodulatory therapy is crucial, and personalized medicine for RIF patients is emerging. As the literature on the subject is heterogenous and rapidly evolving, we aim to summarize the potential efficacy, mechanisms of actions and side effects of select therapies for the practicing clinician.
Mathilde Daudon, Christelle Ramé, Christopher Price, and Joelle Dupont
Fibronectin type III domain-containing 5 (FNDC5) is a transmembrane protein discovered in 2012 that is cleaved to release the adipokine-myokine, irisin. Originally described as an exercise hormone that browns white adipose tissue and increases glucose metabolism, irisin secretion also increases during periods of rapid adipose mobilization, such as the post-partum period in dairy cattle when ovarian activity is suppressed. The effect of irisin on follicle function is unclear, and may be species dependent. In this study we hypothesized that irisin may compromise granulosa cell function in cattle using a well-established in vitro cell culture model. We detected FNDC5 mRNA and both FNDC5 and cleaved irisin proteins in follicle tissue and in follicular fluid. Abundance of FNDC5 mRNA was increased by treatment of cells with the adipokine visfatin but not by other adipokines tested. Addition of recombinant irisin to granulosa cells decreased basal and IGF-1- and FSH-dependent estradiol and progesterone secretion, and increased cell proliferation but had no effect on viability. Irisin decreased GLUT1, GLUT3 and GLUT4 mRNA levels in granulosa cells and increased lactate release in culture medium. The mechanism of action is in part through MAPK3/1 but not Akt, MAPK14 or PRKAA. We conclude that irisin may regulate bovine folliculogenesis by modulating granulosa cell steroidogenesis and glucose metabolism.
Qian Li, Li Yang, Feng Zhang, Jiaxi Liu, Min Jiang, Yannan Chen, and Chenchen Ren
In brief
Inflammation and abnormal immune response are the key processes in the development of endometriosis (EMs), and m6A modification can regulate the inflammatory response. This study reveals that METTL3-mediated N6-methyladenosine (m6A) modification plays an important role in EMs.
Abstract
m6A modification is largely involved in the development of different diseases. This study intended to investigate the implication of m6A methylation transferase methyltransferase like 3 (METTL3) in EMs. EMs- and m6A-related mRNAs and long non-coding RNAs were identified through bioinformatics analysis. Next, EM mouse models established by endometrial autotransplantation and mouse endometrial stromal cell (mESC) were prepared and treated with oe-METTL3 or sh-MIR17HG for pinpointing the in vitro and in vivo effects of METTL3 on EMs in relation to MIR17HG through the determination of mESC biological processes as well as estradiol (E2) and related lipoprotein levels. We demonstrated that METTL3 and MIR17HG were downregulated in the EMs mouse model. Overexpression of METTL3 suppressed the proliferation, migration, and invasion of mESCs. In addition, METTL3 enhanced the expression of MIR17HG through m6A modification. Moreover, METTL3 could inhibit the E2 level and alter related lipoprotein levels in EMs mice through the upregulation of MIR17HG. The present study highlighted that the m6A methylation transferase METTL3 prevents EMs progression by upregulating MIR17HG expression.
Dominika Celar Sturm and Irma Virant-Klun
Bisphenol A (BPA) is an endocrine disruptor (ED), widely used as a comonomer or an additive in the plastics industry. It can be found in food and beverage plastic packaging, epoxy resins, thermal paper and other common products. To date, there have only been several experimental studies to have examined how BPA exposure affects human and mammalian follicular granulosa cells (GCs) in vitro and in vivo; the collected evidence data shows that BPA negatively affects the GCs by altering steroidogenesis and gene expression, inducing autophagy, apoptosis and cellular oxidative stress through reactive oxygen species (ROS) production. Exposure to BPA can also lead to abnormally constrained or elevated cellular proliferation and can even reduce cell viability. Therefore, research on EDs such as BPA is important as it provides some important insights into the causes and development of infertility, ovarian cancer and other conditions, related to impaired ovarian and GC function. Folic acid, a biologic form of vitamin B9, is a methyl donor that can neutralize toxic effects of the BPA exposure and is, as a common food supplement, an interesting option for researching its protective role against ubiquitous harmful EDs such as BPA.
Rodrigo Garcia Barros, Valentina Lodde, Federica Franciosi, and Alberto Maria Luciano
In brief
The proposed culture system improves the current state of in vitro culture of growing oocytes in the bovine species and allows access to the untapped gamete reserve, thus improving reproductive efficiency.
Abstract
The present study aimed to improve the in vitro culture of bovine oocytes collected from early antral follicles (EAFs) to support the progressive acquisition of meiotic and developmental competence. The rationale that drove the development of such a culture system was to maintain as much as possible the physiological conditions that support the oocyte growth and differentiation in vivo. To this extent, oocytes were cultured for 5 days, which parallels the transition from early to medium antral follicles (MAFs) in the bovine, and supports promoting a 3D-like structure were provided. Additionally, the main hormones (follicle-stimulating hormone, estradiol, progesterone, and testosterone) were added in concentrations similar to the ones previously observed in bovine EAFs. The meiotic arrest was imposed using cilostamide. The cultured cumulus–oocyte complexes (COCs) reached a mean diameter of 113.4 ± 0.75 µm and showed a progressive condensation of the chromatin enclosed in the germinal vesicle (GV), together with a gradual decrease in the global transcriptional activity, measured by 5-ethynyl uridine incorporation. The described morpho-functional changes were accompanied by an increased ability to mature and develop to the blastocyst stage in vitro, although not matching the rates obtained by MAF-retrieved oocytes. The described system improves the current state of in vitro culture of growing oocytes in the bovine species, and it can be used to increase the number of gametes usable for in vitro embryo production in animals of high genetic merit or with specific desirable traits.