Biology of Reproduction最新文献

Small extracellular vesicles (sEVs) exert crucial biological functions in a wide range of organisms, whereas the existence characteristics and biological roles of egg yolk-derived sEVs (YsEVs) in oviparous vertebrates remain largely uncharacterized and unexplored to date. Here, YsEVs were respectively isolated from 13 Aves and Reptilia species via differential centrifugation, and characterized using TEM, NTA, and WB. All YsEVs exhibited typical sEV features with sEVs marker protein patterns across species. Interestingly, nearly all characteristic parameters (diameter, volume) of YsEVs derived from Aves exhibited relative similarity. In contrast, within Reptilia, the diameter of YsEVs derived from Squamata (snakes) was significantly larger than that of other reptilian samples. Proteomic analysis of YsEVs isolated from fertilized (F-YsEVs) and unfertilized (uF-YsEVs) chicken eggs identified 694 proteins in total. Compared with uF-YsEVs, F-YsEVs exhibited 106 up-regulated and 144 down-regulated proteins (|FC| > 1.2 and P < 0.05). Bioinformatics analysis revealed that these differentially expressed proteins mediate critical embryotrophic functions: nutrient/energy supply, developmental regulation, antimicrobial protection, antioxidant activity, and metabolic signaling. Collectively, sEVs are widely present in the egg yolks of oviparous vertebrates. Among the protein cargo of YsEVs, the differentially expressed proteins between F-YsEVs and uF-YsEVs are of particular interest, given that they elucidate the potential Biological Function for early embryo (stage X) in these organisms.

Epigenetic modifications regulate chromatin conformation and transcription factor accessibility to regulatory regions of the genome, controlling gene expression without altering the DNA sequence itself, and being stably transmitted throughout cell divisions. One of the most well studied epigenetic marks is DNA methylation, which controls the monoallelic, parental-origin dependent expression of imprinted genes. Paternal imprinting marks are established in the male germ line, so that mature gametes - the spermatozoa - transmit correct imprints to the future embryo. Anomalies in the establishment and/or maintenance of imprinting marks can interfere with embryonic and placental development and/or result in the birth of children affected by imprinting syndromes, such as Silver-Russell (SRS) and Beckwith-Wiedemann (BWS). Here, we review the literature on the observations of imprinting errors in the male gamete, in the context of disturbances in spermatogenesis resulting in male infertility, focusing on the observations described by our group and others. We provide a clinical perspective on the implementation of sperm methylation analysis as a tool to improve diagnostic and therapeutic strategies in Assisted Reproduction Technologies (ART) and highlight the importance of understanding the molecular mechanisms underlying spermatogenic defects and male infertility.

In the mouse testis, spermatogonial stem cells (SSCs) are sparsely distributed and migrate along the basement membrane of seminiferous tubules. Although the basement membrane is generally thought to be formed by surrounding somatic cells, whether SSCs also produce basement membrane proteins and, if so, whether SSC-produced laminin affects SSC behavior remains unknown. In this study, we found that mouse GFRα1+ spermatogonia, which include SSCs, expressed several laminin subunit genes, including Lamc1, whose expression declined upon differentiation. To test whether GFRα1+ spermatogonia-derived laminin regulates their behavior, we used two conditional knockout mouse models. In the Vasa-Cre model, which induces recombination in all germ cells, heterozygous deletion of Lamc1 increased both cell death and proliferation of GFRα1+ spermatogonia, while maintaining an apparent steady state of GFRα1+ cell density and spermatogenesis. In the tamoxifen-inducible GFRα1-CreER model carrying Lamc1flox/flox, tamoxifen-induced Lamc1 deletion in GFRα1+ spermatogonia caused a rapid reduction in their cell density within a few days, followed by increased proliferation and an imbalance between proliferation and differentiation of GFRα1+ spermatogonia that led to the restoration of GFRα1+ spermatogonial density. Collectively, these genetic findings suggest that GFRα1+ spermatogonia modulate their survival and behavior through laminin expression, likely by influencing the basement membrane around GFRα1+ spermatogonia. Such cell-autonomous regulation allows GFRα1+ spermatogonia, including SSCs, to form an appropriate local microenvironment wherever they reside within the testicular open niche, supporting stable behavior of spermatogonia during spermatogenesis.

Myosin VI (MYO6) is the only actin-based motor protein that moves toward the minus end of actin filaments. It participates in multiple cellular processes, including endocytosis, secretion, autophagy, and the formation of apical stereocilia and microvilli in highly specialized epithelia. These diverse functions are mediated by specific cargo-adaptor proteins that recruit MYO6 to distinct cellular compartments. We have previously demonstrated that loss of MYO6 function in Snell's waltzer mice leads to several defects during spermatogenesis, resulting in reduced male fertility. Here, we show for the first time that MYO6 and selected binding partners are differentially expressed in mouse epididymal epithelium, a highly specialized mammalian epithelia developing apical microvilli. Using immunocytochemistry, confocal microscopy, and biochemical approaches we found that: (i) MYO6 is present in the epithelium of the common efferent duct and all segments of the epididymis, (ii) MYO6 and Dab2 colocalize predominantly at the apical surface of epithelial cells in the efferent duct and caput, (iii) MYO6 and GIPC1 are mainly detected in epithelial cells in the caput and corpus, with the lowest level observed in the cauda. Moreover, depletion of MYO6 results in altered distribution of clathrin and APPL1 in epididymal epithelial cells and causes ultrastructural abnormalities. Altogether, our findings indicate that MYO6 contributes to the endocytic pathway in the mouse epididymal epithelium, a process essential for generating the microenvironment required for sperm maturation. In addition, MYO6 supports the structural organization of apical microvilli, thereby facilitating sperm transport through the epididymal duct.

Oocyte differentiation occurs within germline cysts in many metazoans, where only a small number of cyst cells differentiate into oocytes, while the majority undergo apoptosis. In zebrafish, the transition of primordial germ cells (PGCs) to germline cysts has been well studied. However, the exact process by which cyst cells develop into oocytes remains unclear. Here, we analyzed the temporal and spatial characteristics of germline cysts and traced the process of oocyte differentiation in the early zebrafish gonad, by transmission electron microscopy and laser confocal microscopy. The experiments showed that germline cysts were first found at the gonadal periphery at 15 days post-fertilization (dpf) in zebrafish. No oocytes with a Balbiani body were observed within these cysts until 21 dpf. Instead, PGC daughter cells within the gonad lumen fused to form a syncytium-like structure between 15 and 16 dpf, where oocytes were formed after mitochondria and nuage aggregated into the Balbiani body since 16 dpf and were released beginning at 19 dpf. On the other hand, strong EdU-positive signals were detected in some cyst cells between 15 and 17 dpf, but not in the germ cells within the syncytium-like structure. By 21 dpf, EdU-positive cyst cells appeared in the syncytium-like structure and finally developed into individual oocytes at 25 dpf. No massive apoptosis was observed in germ cells within the syncytium-like structure. Our findings provide new insights into oocyte differentiation in zebrafish and advance our understanding of early oogenesis in vertebrates.

Obesity and metabolic dysfunction induced by high-fat and Western-style diets are key contributors to reproductive aging. However, the specific contributions of diet-induced obesity and liver damage to ovarian aging and follicle depletion remain unclear. This study investigated the impact of a high-fat diet (HFD) and a choline-deficient Western diet (CDWD) on ovarian aging in two mouse strains. Three-month-old female mice (C57BL/6 and Swiss) were assigned to a control standard diet (CSD), choline-deficient control diet (CDC), HFD, or CDWD for ten weeks. C57BL/6 mice fed an HFD exhibited significant body mass gain, intra-abdominal fat accumulation, and insulin resistance, whereas Swiss mice did not develop obesity. Both strains developed hepatomegaly and steatohepatitis under CDWD in the absence of obesity, as expected for this choline-deficient diet. HFD and CDWD increased serum cholesterol and high-density lipoprotein levels in both strains. The ovarian follicle reserve was unaffected by diet or strain, despite a modest increase in follicular atresia in HFD-fed C57BL/6 mice. However, both HFD and CDWD promoted macrophage infiltration, lipofuscin accumulation, stromal fibrosis, and increased stromal proliferative activity. These findings demonstrate that metabolic stress from HFD and CDWD remodels the ovarian microenvironment and induces early hallmarks of ovarian aging independent of follicle depletion. Metabolic responses were strain-dependent; however, both obesity-driven metabolic dysfunction and obesity-independent liver injury led to similar ovarian microenvironment remodeling. This highlights a previously underappreciated pathway linking metabolic diseases to reproductive decline and suggests that ovarian microenvironmental remodeling is an early sign of ovarian aging in response to diet-induced metabolic stress.

The seminal microbiome, which is composed of different types of bacteria in semen and seminal plasma, has a significant impact on male reproductive health by changing the quality of semen and fertility. Previously regarded as sterile, the male reproductive tract contains microbes originating from the gastrointestinal tract, reproductive organs, and external sources such as sexual partners. Dysbiosis alters sperm parameters, triggers inflammation and oxidative stress, and is associated with conditions such as infertility, HPV infection, prostatitis, prostate cancer, and azoospermia. This systematic review adhered to the PRISMA 2020 guidelines (with 2025 extensions for reproducibility) and examined studies from PubMed, Scopus, and Science Direct (2015-2025, with prior context), concentrating on human, in vitro, and rodent models. Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes are among the most important phyla. Beneficial genera, such as Lactobacillus, improve sperm motility, concentration, and DNA integrity, whereas dysbiotic taxa, such as Prevotella, Pseudomonas, and Ureaplasma, are associated with declines. Sexual activity facilitates bidirectional microbial transfer, modifying diversity and fostering the dysbiosis. Inflammatory cytokines, reactive oxygen species, and metabolic disruptions are all involved in this process. Changes that are specific to a disease, such as higher levels of Fusobacterium in HPV-positive samples, worsen the situation. This review highlights how the microbiome alters sperm function and causes infertility. Standardized methods and long-term studies are needed to prove causality. Probiotics and other therapeutic interventions show promise in restoring balance and boosting fertility.

Upon fertilisation, the egg must have the resources to facilitate successful fertilisation and regulate zygotic growth prior to the activation of the embryonic genome. A key biomarker of egg activation is the synchronised release of of cortical alveoli (CA) from the egg's cortex into the perivitelline space. Teleost CA are primarily associated with their highly conserved roles in polyspermy prevention. However, several CA-associated proteins with functions related to innate immunity have been isolated. While there is growing evidence that teleost CA have extended biological roles outside of polyspermy prevention, little work has been done towards developing an understanding of their general proteomic composition. Therefore, the aim of this study was to identify proteins which were proportionally over-represented in the zebrafish (Danio rerio) perivitelline fluid (PVF) directly following CA exocytosis to identify a candidate list of CA-associated proteins. This study utilised a novel technique for PVF extraction from water-activated eggs shortly following CA exocytosis which negated the use of fixatives, thereby increasing PVF sample integrity for downstream mass-spectrometry analysis. Moreover, this study provides the first comparative proteomic analysis of the PVF relative to the yolk and cytoplasm of the zebrafish egg. As a result, 44 proteins were identified which were proportionally over-represented in the PVF, relative to the yolk and cytosol, of the water-activated unfertilised egg. The resulting PVF proteome was comprised of proteins associated with functions in carbohydrate binding and peptidase regulation. Many of these proteins are compelling candidates for being CA-derived and have been previously implicated in innate immunity.

Premature ovarian insufficiency (POI) impacts ~1-3.7% of women under the age of 40 globally and is characterised by an absence or complete loss of ovarian function. POI is clinically heterogenous in nature and researchers have identified >100 causative genes harbouring variants responsible for POI thus far. Genes identified to date include those associated with cell differentiation/development, mitochondrial maintenance, hormone receptors, transcription/translation factors, DNA repair/replication, and metabolic processes. Genes encoding cell components that facilitate these processes should therefore also be considered in POI gene candidature. The RNA exosome is a critical component in RNA processing, degradation, and biogenesis in eukaryotic cells. Catalytic activity of the RNA exosome is supplied by two subunits, DIS3 and EXOSC10. Dysregulation of RNA exosome function results in conditions known as exosomopathies that have a broad spectrum of phenotypic severity. RNA transcript regulation is essential in transcriptionally inactive maturing mammalian oocytes with its disruption negatively impacting meiosis and fertilization. Notably, oocyte depletion of Exosc10 significantly impacts the fertility of female mice. Herein we identified, via whole exome sequencing, the first instance of a human POI patient with an EXOSC10 homozygous missense variant. Using Drosophila melanogaster we modelled the impact of knockdown of the EXOSC10 ortholog, Rrp6, on both somatic and germline ovarian cells. We observed that Rrp6 is required in ovarian development in Drosophila. Due to the conserved role of EXOSC10 in fertility maintenance across species we contend that variants in EXOSC10 identified in POI patients may be causative.

Semen from mature, healthy bulls contains commensal microbes. Potential internal sources of seminal microbes have not been extensively evaluated. Objectives were to 1) assess whether the testes of the bull contain commensal microbes and to compare the composition of the putative testicular microbiome to that of semen and rumen fluid and 2) determine whether other organs of the bull reproductive system contain microbial populations. Here, we demonstrate that the testes of the bull contain a low biomass, yet diverse, microbiome. Interestingly, the microbial composition of rumen fluid, semen and testicular tissue were each dissimilar from one another, indicating that each source contains a unique microbiota. Only four core amplicon sequence variants, Acinetobacter, Enterobacteriaceae (E. coli), Jeotgalicoccus, and Kiritimatiellae WCHB1-41, were shared between semen and the testes. Along with the testes, microbial populations were also present within the penile and pelvic urethra, seminal vesicles and epididymis of mature bulls. Of these anatomic niches, the microbial populations within the penile and pelvic urethra were the most diverse and shared the greatest number of core taxa (n = 72). The microbiota of the seminal vesicles, epididymis and the testes were significantly dissimilar from each other. Only one core taxa, Mycoplasma, was shared between the testes and epididymis. Collectively, our results demonstrate that semen and organs of the bull reproductive tract contain unique microbial populations. Further research is necessary to determine whether the microbial composition of organs of the bull reproductive system, such as the testes and epididymis, influence sperm viability and bull fertility.