Molecular Reproduction and Development最新文献

Embryo genome activation (EGA) is a crucial event implicated in proper embryonic development. Similarly, the DNA Damage Response (DDR) is essential for correcting or preventing occasional errors during embryonic cell division that could result in embryo development arrest or the propagation of genetic abnormalities. Although both EGA and DDR are regulated by epigenetic mechanisms, the role of microRNAs (miRNAs) in these processes has not been explored in pig embryos. Herein, we assessed the abundance of miRNAs linked to embryo development and DDR across four developmental stages: Day 2 (D2), Day 3 (D3), and Day 4 (D4), and at the blastocyst stage, as well as after DNA damage induction. mRNA levels of EGA-related genes confirmed our timepoints as representing EGA timeframe, while immunofluorescence for γH2AX validated DNA damage induction. Significant decrease in blastocyst rate and total cell number per blastocyst was detected in UV-exposed embryos. Analysis of miRNA abundance revealed increased levels of miR-200a-5p on D3, which were partially maintained on D4. Both miR-15a and miR-24-3p increased on D4, but their levels were downregulated in UV-exposed embryos at the same stage of development. In blastocysts, UV exposure upregulated miR-29a-3p and miR-344b-3p. Together, these findings provide the first characterization of miRNAs expression in porcine embryos during EGA and following DNA damage induction.

To identify the optimal in vitro maturation (IVM) duration for bovine oocytes with different nuclear maturation speeds (NMS), this study assessed how varying IVM durations (24, 28, and 32 h) affect developmental competence and embryo quality in oocytes with fast- or slow-predicted NMS classified via machine learning. Developmental competence was evaluated through cleavage rates, first cleavage timing and patterns, and blastocyst formation under individual culture. Embryo quality was assessed via differential staining of inner cell mass and trophectoderm and expression analysis of quality-related genes in formed blastocysts. For oocytes with slow-predicted NMS, extending IVM to 28 h increased cleavage rates and accelerated first cleavage timing (p < 0.01). The lower blastocyst formation rates of oocytes with slow-predicted NMS matured for 24 h improved when IVM reached 28 h, becoming comparable to fast-predicted NMS oocytes. However, extended IVM decreased expression of pluripotency-related genes (e.g., NANOG and OCT4; p < 0.01) regardless of predicted NMS. In conclusion, extending IVM duration to 28 h improved developmental competence of slow-predicted NMS oocytes, highlighting the importance of fertilization timing relative to nuclear maturation completion, though it reduced expression of key pluripotency genes. Individualized IVM protocols based on predicted NMS can enhance bovine embryo production efficiency.

Dairy cows often experience a period of negative energy balance (NEB) during the post-calving period, which can significantly impact economic outcomes due to extended calving-to-conception intervals and overall reduced fertility. This reduction is due, in part, to the impact on uterine biology by high nonesterified fatty acids (NEFA) and beta-hydroxybutyrate concentration. The uterine fluid (UF) contains small extracellular vesicles (UF-EVs) that, through their cargo, including microRNAs (miRNAs), respond to metabolic stress, affecting the uterine environment. This study aimed to assess the long-term impact of NEB intensity on the uterine environment of dairy cows. Post-partum dairy cows were classified based on NEFA concentrations in their blood during the 3 weeks post-calving as having either Low or High NEB. At 30 and 60 DPC, the synchronization protocol was started, and UF samples were collected (corresponding to ~15 days after initiation of the synchronization protocol) to isolate UF-EVs and uterine epithelial cells for miRNA and transcriptome profiling. We also investigated whether UF-EVs could modulate epithelial uterine naïve cells. Our results indicate that the uterine environment of dairy cows experiencing a High NEB post-calving is unfavorable for embryo development at 60-day post-calving. Importantly, we show that UF-EVs can reproduce this phenotype in epithelial uterine naïve cells, suggesting that UF-EVs may act as modulators of the uterine response to metabolic challenges.

Small extracellular vesicles (sEVs) function as critical regulators of ovarian follicular development. Although several pathways, including one involving neutral sphingomyelinase (nSMase), contribute to sEV production, the specific pathway active in ovarian follicles has not been clearly identified. In this study, we investigated GW4869, a specific inhibitor of nSMase activity, to determine its impact on sEV production by mouse mural granulosa cells (MGCs), the primary source of follicular sEVs. We also examined how nSMase inhibition affects the in vitro growth of oocyte‒granulosa cell complexes (OGCs) derived from secondary follicles. Transcripts encoding nSMases (Smpd2 and Smpd4) were detected in MGCs, and GW4869 treatment significantly reduced sEV production in MGC monolayer cultures. Control OGCs developed into antral follicle-like structures, with the antrum-like structure separating granulosa cells into cumulus-like and MGC-like cells. However, GW4869 treatment impaired OGC development. MGC-like cells from GW4869-treated OGCs exhibited significantly lower Cyp19a1 levels, whereas adding MGC-derived sEVs promoted Cyp19a1 expression. These results suggest that nSMase activity, likely involving Smpd2 and Smpd4, is required for sEV production by MGCs and that follicular sEVs may regulate Cyp19a1 expression in MGCs.

Among the eight types of development in sponges, the least common and least studied is direct, non-larval development during viviparity. To supplement our knowledge of this rare type of demosponge development, we present here a description of the embryonic development of four species of the genus Craniella (Demospongiae, order Tetractinellida) from the deep-sea in the Northeast Atlantic. Craniella development is asynchronous within one sponge. Mature oocytes are polylecithal and isolecithal. Embryonic development occurs in a dense double-layer follicle: layers of flattened cells and a thick layer of collagen. The cleavage is total, unequal, and asynchronous. It is characterized by collagen layers penetrating inside the embryo and surrounding blastomeres. As a result of cleavage, an oval-shaped apolar stereoblastula is formed. At the stereoblastula stage, embryonic sclerocytes secrete the first megascleres, long thin oxeas, radially positioned. Later, the embryo is divided into the peripheral, intermediate, and central zones. In the intermediate zone, choanocyte chambers, lacunes, and canals of the aquiferous system are formed. The fully formed juveniles have a subspherical to flattened shape with cone-shaped outgrowths on the surface. Unlike the adults, juveniles lack cortical microxeas and have characteristic anamonaenes spicules. The juveniles exit the mother's body through the exhalant canals of the aquiferous system.

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Aging refers to the irreversible changes in the structure and function of organisms over time. Under the influence of social and economic factors, the apparent effect of aging on female fertility has been widely recognized; however, its effect on male fertility has not received sufficient attention. Spermatogenic stem cells can differentiate and produce gametes continuously for a long time in a man's life, but more significant cumulative effects often occur over time. These age-related effects mainly manifest as increased chromosomal abnormalities and DNA damage, lower levels of sex hormones, impaired testicular function, and reduced spermatozoa count and quality. In the past, more attention has been paid to some of the macroscopic changes associated with aging. In this review, we will focus on the cellular level, discussing the effects of aging on male germ cells and the changes in the spermatogenic microenvironment, which consists mainly of Sertoli and Leydig cells.

We characterized the morphogenetic processes of larval metamorphosis and the development of the olynthus and heterocoelic aquiferous system (AS) in Sycettusa hastifera (syconoid) and Paraleucilla magna (leuconoid) (Porifera, Calcarea). Metamorphosis and development up to the olynthus were similar in both species. During metamorphosis, apparently, the juvenile's cell lineages were established by invagination of the ciliated pole into the larval cavity, while posterior pole cells covered the juvenile. Ciliated cells seemed to differentiate into an inner cell mass (ICM) (forming choanoblasts and scleroblasts), while granular cells seemed to form mainly the pinacoderm. Then, cavitation of the ICM formed the asconoid AS of the olynthus. Choanocyte chamber morphogenesis for the syconoid and leuconoid AS seemed to be epithelial, but followed different paths. In S. hastifera, the chambers were formed by folding the primordial choanoderm towards the external portion of the sponge, whereas in P. magna, invagination of the choanoderm into the spongocoel segregated groups of choanocytes into spherical chambers. The morphogenesis of the heterocoelic AS in these calcareans is likely different from that in Demospongiae (leuconoid AS is established via mesenchymal-to-epithelial morphogenesis) but similar to Homoscleromorpha (AS arises through epithelial morphogenesis). Characterizing the post-embryonic development in these species is the first step toward understanding the mechanisms that regulate the ontogeny and evolution of Porifera's primary synapomorphy: the aquiferous system.