Search Results (67)

Background/Objectives: Fish eggs activated with UV-irradiated spermatozoa and exposed to the High Hydrostatic Pressure (HHP) shock to inhibit first cell cleavage develop as gynogenetic Doubled Haploids (DHs) that are fully homozygous individuals. Due to the expression of the recessive genes and side effects of the gamete treatment, survival of fish DHs is rather low, and most of the mitotic gynogenotes die before hatching. Nevertheless, as maternal gene products provided during oogenesis control the initial steps of embryonic development in fish, a maternal effect on the survival of gynogenotes needs to be also considered to affect efficiency of gynogenesis. Thus, the objective of this research was to apply an RNA-seq approach to discriminate transcriptional differences between rainbow trout (Oncorhynchus mykiss) eggs with varied abilities to develop after gynogenetic activation. Methods: Gynogenetic development of rainbow trout was induced in eggs originated from eight females. Maternal RNA was isolated and sequenced using RNA-Seq approach. Survival rates of gynogenotes and transcriptome profiles of eggs from different females were compared. Results: RNA-seq analysis revealed substantial transcriptional differences between eggs originated from different females, and a significant correlation between the ability of the eggs for gynogenesis and their transcriptomic profiles was observed. Genes whose expression was altered in eggs with the increased survival of DHs were mostly associated (GO BP) with the following biological processes: development, cell differentiation, cell migration and protein transport. Some of the genes are involved in the oocyte maturation (RASL11b), apoptosis (CASPASE 6, PGAM5) and early embryogenesis, including maternal to zygotic transition (GATA2). Conclusions: Inter-individual variation of the transcription of maternal genes correlated with the competence of eggs for gynogenesis suggest that at least part of the mortality of the rainbow trout DHs appear before activation of zygotic genome and expression of the lethal recessive traits. Full article

Epigenetics and genome science have become central to current molecular biology research. Among the key mechanisms ensuring genomic integrity is the silencing of transposable elements in germline cells, a process essential for fertility in both sexes. A pivotal component of this silencing machinery involves PIWI-interacting RNAs (piRNAs), a distinct class of small non-coding RNAs that regulate gene expression and suppress transposable elements at both the transcriptional and post-transcriptional levels. piRNAs function in concert with PIWI proteins, whose expression is critical for proper oogenesis, spermatogenesis, and early zygote development. Disruptions in piRNA or PIWI protein pathways not only impair germline function but also contribute to genome instability, unchecked cell proliferation, and aberrant epigenetic modifications, hallmarks of tumorigenesis. Emerging evidence links the dysregulation of the piRNA/PIWI axis to the development and progression of various cancers, including lung and colorectal carcinomas. This review highlights the fundamental roles of piRNAs and PIWI proteins in reproductive biology and their increasingly recognized relevance in cancer biology. Full article

Zygotic genome activation (ZGA) marks the critical transition from reliance on maternal transcripts to the initiation of embryonic transcription early in development. Despite extensive characterization in model species, the regulatory framework of ZGA in sheep remains poorly defined. Here, we applied single-cell RNA sequencing (Smart-seq2) to in vivo- and in vitro-derived sheep embryos at the 8-, 16-, and 32-cell stages. Differential expression analysis revealed 114, 1628, and 1465 genes altered in the 8- vs. 16-, 16- vs. 32-, and 8- vs. 32-cell transitions, respectively, with the core pluripotency factors SOX2, NANOG, POU5F1, and KLF4 upregulated during major ZGA. To uncover coordinated regulatory modules, we constructed a weighted gene co-expression network using WGCNA, identifying the MEred module as most tightly correlated with developmental progression (r = 0.48, p = 8.6 × 10⁻¹⁴). The integration of MERed genes into the STRING v11 protein–protein interaction network furnished a high-confidence scaffold for community detection. Louvain partitioning delineated two discrete communities: Community 0 was enriched in ER–Golgi vesicle-mediated transport, transmembrane transport, and cytoskeletal dynamics, suggesting roles in membrane protein processing, secretion, and early signaling; Community 1 was enriched in G2/M cell-cycle transition and RNA splicing/processing, indicating a coordinated network for accurate post-ZGA cell division and transcript maturation. Together, these integrated analyses reveal a modular regulatory architecture underlying sheep ZGA and provide a framework for dissecting early embryonic development in this species. Full article

(1) Background: WOX (WUSCHEL-related homologous box) is a plant-specific transcription factor involved in plant development and stress response. It has been reported to be involved in processes such as growth and development, stem cell division and differentiation, and organ development; (2) Methods: In this study, bioinformatics was used to identify and analyze the WOX gene family of Korean pine. The gene characteristics were identified and analyzed through yeast transcriptional activation assays as well as subcellular localization experiments; (3) Results: A total of 21 members of the WOX gene family of Korean pine were identified in this study. The phylogenetic tree divides the PkWOX genes into three sub-branches. 21 PkWOX genes are unevenly distributed on 7 of the 12 chromosomes. PkWOX16 was expressed in all tissues. PkWOX2, 3 had higher expression in the embryonic callus, non-embryonic callus, somatic embryo, and zygotic embryo. PkWOX2, 3 and 16 were located in the nucleus and in the cell membrane. The PkWOX2 and 3 proteins exhibited transcriptional self-activation activity, while PkWOX16 did not; (4) Conclusions: In this study, the members of the WOX transcription factor family in Korean pine were identified and systematically analyzed, laying a foundation for their subsequent functional research. Full article

The nuclear factor Y (NF-Y) transcription factor is widely involved in various plant biological processes, such as embryogenesis, abscisic acid signaling, and abiotic stress responses. This study presents a comprehensive genome-wide identification and expression profile of transcription factors NF-YB and NF-YC in Pinus koraiensis. Eight NF-YB and seven NF-YC transcription factors were identified through bioinformatics analysis, including sequence alignment, phylogenetic tree construction, and conserved motif analysis. We evaluate the expression patterns of NF-YB/C genes in various tissues and somatic embryo maturation processes through the transcriptomics of ABA-treated tissues from multiple nutritional tissues, reproductive tissues, and somatic embryo maturation processes. The Leafy cotyledon1 (LEC1) gene belongs to the LEC1-type gene in the NF-YB family, numbered PkNF-YB7. In this study, we characterized the function of PkLEC1 during somatic embryonic development using genetic transformation techniques. The results indicate that PkNF-YB/C transcription factors are involved in the growth and development of nutritional tissues and reproductive organs, with specific high expression in PkNF-YB7 embryogenic callus, somatic embryos, zygotic embryos, and macropores. Most PkNF YB/C genes do not respond to ABA treatment during the maturation culture process. Compared with the absence of ABA, PkNF-YB8 was up-regulated in ABA treatment for one week (4.1 times) and two weeks (11.6 times). However, PkNF-YC5 was down-regulated in both one week (0.6 times) and two weeks (0.36 times) of culture, but the down-regulation trend was weakened in tissues treated with ABA (0.72–0.83 times). In addition, the promoter of PkNF YB/Cs was rich in elements that respond to various plant hormones, indicating their critical role in hormone pathways. The overexpression of PkLEC1 stimulated the generation of early somatic embryos from callus tissue with no potential for embryogenesis, enhancing the somatic embryogenesis ability of P. koraiensis callus tissue. Full article

Early embryonic development relies on intricately regulated gene expression, and miRNAs influence zygotic genome activation (ZGA), cleavage, and cell fate determination through post-transcriptional regulatory mechanisms. miR-192 is expressed in early pig embryos and participates in various reproductive processes. However, its role in pre-implantation pig embryo development remains poorly understood. In this study, we microinjected the miR-192 agonist (miR-192 agomir) into parthenogenetically activated pig embryos to evaluate its effects on early pig embryo development. Our findings indicate that compared to the control group (agomir NC), miR-192 agomir impairs the developmental capacity of parthenogenetic pig embryos to reach the 2-cell, 4-cell, and blastocyst stages. This impairment leads to imbalances in the oxidative–reductive system and abnormalities in mitochondrial function during the 4-cell stage, resulting in the significant accumulation of ROS, notable decreases in the expression of antioxidant enzymes CAT and SOD1 mRNA, reduction in mitochondrial membrane potential, and induction of apoptosis in pig blastocysts. Additionally, the overexpression of miR-192 inhibits the expression of its target genes YY1 and the pluripotency factor NANOG mRNA. In conclusion, this study reveals that the overexpression of miR-192 adversely affects early pig embryo development, providing new evidence for understanding the role miR-192 plays in reproduction. Full article

Zygotic genome activation (ZGA) is critical for early embryo development and is meticulously regulated by epigenetic modifications. H3K4me3 is a transcription-permissive histone mark preferentially found at promoters, but its distribution across genome features remains incompletely understood. In this study, we investigated the genome-wide enrichment of H3K4me3 during early embryo development and embryonic stem cells (ESCs) in both sheep and mice. We discovered that broad H3K4me3 domains were present in MII stage oocytes and were progressively diminished, while promoter H3K4me3 enrichment was increased and correlated with gene upregulation during ZGA in sheep. Additionally, we reported the dynamic distribution of H3K4me3 at the transposable elements (TEs) during early embryo development in both sheep and mice. Specifically, the H3K4me3 distribution of LINE1 and ERVL, two subsets of TEs, was associated with their expression during early embryo development in sheep. Furthermore, H3K4me3 enrichment in TEs was greatly increased during ZGA following Kdm5b knockdown, and the distribution of RNA polymerase II (Pol2) in TEs was also markedly increased in Kdm5b knockout ESCs in mice. These findings suggest that H3K4me3 plays important roles in regulating TE expression through interaction with RNA Pol2, providing valuable insights into the regulation of ZGA initiation and cell fate determination by H3K4me3. Full article

The critical mechanism to restart zygote metabolism and prevent polyspermy during fertilization is the intracellular Ca²⁺ increase. All of the signaling molecules leading to the Ca²⁺ rise are not fully known in any species. In the sea star Patiria miniata, SFK1, SFK3, and PLCγ participate in this fertilization Ca²⁺ increase. These proteins share common regulatory features, including signaling via tyrosine phosphorylation and their SH2 domains. In this study, we explore two different bioinformatic strategies to identify transcripts in the Patiria miniata mature egg transcriptome (Accession PRJNA398668) that code for proteins possessing an SH2 domain. The first identified the longest open reading frame for each transcript and then utilized similarity searching tools to provide identities for each transcript. The second, novel, method involved a six-frame translation of the entire transcriptome to identify SH2 domain-containing proteins. The identified transcripts were aligned against the NCBI non-redundant database and the SwissProt database. Eighty-two transcripts that encoded SH2 domains were identified. Of these, 33 were only found using the novel method. This work furthers research into egg activation by providing possible target proteins for future experiments and a novel method for identifying specific proteins of interest within a de novo transcriptome. Full article

The use of C-type natriuretic peptide (CNP) in the interaction with the oocyte and in the temporary postponement of spontaneous meiosis resumption has already been well described. However, its action in pre-implantation developmental-stage embryos is yet to be understood. Thus, our study aimed to detect the presence of the canonical CNP receptor (natriuretic peptide receptor, NPR2) in germinal vesicle (GV)-, metaphase II (MII)-, presumptive zygote (PZ)-, morula (MO)-, and blastocyst (BL)-stage embryos and, later, to observe possible modulations on the embryos when co-cultured with CNP. In Experiment I, we detected and quantified NPR2 on the abovementioned embryo stages. Further, in Experiment II, we intended to test different concentrations (100, 200, or 400 nM of CNP) at different times of inclusion in the in vitro culture (IVC; inclusion from the beginning, i.e., day 1, or from day 5). In Experiment III, 400 nM of CNP was used on day 1 (D1) in the IVC, which was not demonstrated to be embryotoxic, and it showed potentially promising results in the blastocyst production rate when compared to the control. Thus, we analyzed the embryonic development rates of bovine embryos (D7) and hatching kinetics (D7, D8, and D9). Subsequently, morula and blastocyst were collected and evaluated for transcript abundance of their competence and quality (apoptosis, oxidative stress, proliferation, and differentiation) and lipid metabolism. Differences with probabilities less than p < 0.05, and/or fold change (FC) > 1.5, were considered significant. We demonstrate the presence of NPR2 until the blastocyst development stage, when there was a significant decrease in membrane receptors. There was no statistical difference in the production rate after co-culture with 400 nM CNP. However, when we evaluated the abundance of morula transcripts, there was an upregulated transcription in ADCY6 (p = 0.057) and downregulated transcripts in BMP15 (p = 0.013), ACAT1 (p = 0.040), and CASP3 (p = 0.082). In addition, there was a total of 12 transcriptions in morula that presented variation FC > 1.5. In blastocysts, the treatment with CNP induced upregulation in BID, CASP3, SOX2, and HSPA5 transcripts and downregulation in BDNF, NLRP5, ELOVL1, ELOVL4, IGFBP4, and FDX1 transcripts (FC > 1.5). Thus, our study identified and quantified the presence of NPR2 in bovine pre-implantation embryos. Furthermore, 400 nM of CNP in IVC, a concentration not previously described in the literature, modulated some transcripts related to embryonic metabolism, and this was not embryotoxic morphologically. Full article

Zygotic genome activation (ZGA) is a pivotal event in mammalian embryogenesis, marking the transition from maternal to zygotic control of development. During the ZGA process that is characterized by the intricate cascade of gene expression, who tipped the first domino in a meticulously arranged sequence is a subject of paramount interest. Recently, Dux, Obox and Nr5a2 were identified as pioneer transcription factors that reside at the top of transcriptional hierarchy. Through co-option of retrotransposon elements as hubs for transcriptional activation, these pioneer transcription factors rewire the gene regulatory network, thus initiating ZGA. In this review, we provide a snapshot of the mechanisms underlying the functions of these pioneer transcription factors. We propose that ZGA is the starting point where the embryo’s own genome begins to influence development trajectory, therefore in-depth dissecting the functions of pioneer transcription factors during ZGA will form a cornerstone of our understanding for early embryonic development, which will pave the way for advancing our grasp of mammalian developmental biology and optimizing in vitro production (IVP) techniques. Full article

The testis-specific double sex and mab-3-related transcription factor 1 (DMRT1) has long been recognized as a crucial player in sex determination across vertebrates, and its essential role in gonadal development and the regulation of spermatogenesis is well established. Here, we report the cloning of the key spermatogenesis-related DMRT1 cDNA, named Tc-DMRT1, from the gonads of Tridacna crocea (T. crocea), with a molecular weight of 41.93 kDa and an isoelectric point of 7.83 (pI). Our hypothesis is that DMRT1 machinery governs spermatogenesis and regulates gonadogenesis. RNAi-mediated Tc-DMRT1 knockdown revealed its critical role in hindering spermatogenesis and reducing expression levels in boring giant clams. A histological analysis showed structural changes, with normal sperm cell counts in the control group (ds-EGFP) but significantly lower concentrations of sperm cells in the experimental group (ds-DMRT1). DMRT1 transcripts during embryogenesis exhibited a significantly high expression pattern (p < 0.05) during the early zygote stage, and whole-embryo in-situ hybridization confirmed its expression pattern throughout embryogenesis. A qRT-PCR analysis of various reproductive stages revealed an abundant expression of Tc-DMRT1 in the gonads during the male reproductive stage. In-situ hybridization showed tissue-specific expression of DMRT1, with a positive signal detected in male-stage gonadal tissues comprising sperm cells, while no signal was detected in other stages. Our study findings provide an initial understanding of the DMRT1 molecular machinery controlling spermatogenesis and its specificity in male-stage gonads of the key bivalve species, Tridacna crocea, and suggest that DMRT1 predominantly functions as a key regulator of spermatogenesis in giant clams. Full article

Haploinsufficiency of the PRR12 gene is implicated in a human neuro-ocular syndrome. Although identified as a nuclear protein highly expressed in the embryonic mouse brain, PRR12 molecular function remains elusive. This study explores the spatio-temporal expression of zebrafish PRR12 co-orthologs, prr12a and prr12b, as a first step to elucidate their function. In silico analysis reveals high evolutionary conservation in the DNA-interacting domains for both orthologs, with significant syntenic conservation observed for the prr12b locus. In situ hybridization and RT-qPCR analyses on zebrafish embryos and larvae reveal distinct expression patterns: prr12a is expressed early in zygotic development, mainly in the central nervous system, while prr12b expression initiates during gastrulation, localizing later to dopaminergic telencephalic and diencephalic cell clusters. Both transcripts are enriched in the ganglion cell and inner neural layers of the 72 hpf retina, with prr12b widely distributed in the ciliary marginal zone. In the adult brain, prr12a and prr12b are found in the cerebellum, amygdala and ventral telencephalon, which represent the main areas affected in autistic patients. Overall, this study suggests PRR12’s potential involvement in eye and brain development, laying the groundwork for further investigations into PRR12-related neurobehavioral disorders. Full article

Commencing with sperm–egg fusion, the early stages of metazoan development include the cleavage and formation of blastula and gastrula. These early embryonic events play a crucial role in ontogeny and are accompanied by a dramatic remodeling of the gene network, particularly encompassing the maternal-to-zygotic transition. Nonetheless, the gene expression dynamics governing early embryogenesis remain unclear in most metazoan lineages. We conducted transcriptomic profiling on two types of gametes (oocytes and sperms) and early embryos (ranging from the four-cell to the gastrula stage) of an economically valuable flatfish–the Chinese tongue sole Cynoglossus semilaevis (Pleuronectiformes: Cynoglossidae). Comparative transcriptome analysis revealed that large-scale zygotic genome activation (ZGA) occurs in the blastula stage, aligning with previous findings in zebrafish. Through the comparison of the most abundant transcripts identified in each sample and the functional analysis of co-expression modules, we unveiled distinct functional enrichments across different gametes/developmental stages: actin- and immune-related functions in sperms; mitosis, transcription inhibition, and mitochondrial function in oocytes and in pre-ZGA embryos (four- to 1000-cell stage); and organ development in post-ZGA embryos (blastula and gastrula). These results provide insights into the intricate transcriptional regulation of early embryonic development in Cynoglossidae fish and expand our knowledge of developmental constraints in vertebrates. Full article

The glossiphoniid leech, Helobdella austinensis, is an experimentally tractable member of the superphylum, Lophotrochozoa. Its large embryonic cells, stereotyped asymmetric cell divisions and ex vivo development capabilities makes it a favorable model for studying the molecular and cellular events of a representative spiralian. In this study, we focused on a narrow developmental time window of ~6–8 h, comprising stages just prior to and immediately following zygote deposition. Employing RNA-Seq methodology, we identified differentially expressed transcripts at this fundamental ontogenic boundary, known as the maternal-to-zygotic transition (MZT). Gene expression changes were characterized by the massive degradation of maternal RNAs (~45%) coupled with the rapid transcription of ~5000 zygotic genes (~20% of the genome) in the first mitotic cell cycle. The latter transcripts encoded a mixture of cell maintenance and regulatory proteins that predictably influence downstream developmental events. Full article

Mammalian fertilization initiates the reprogramming of oocytes and sperm, forming a totipotent zygote. During this intricate process, the zygotic genome undergoes a maternal-to-zygotic transition (MZT) and subsequent zygotic genome activation (ZGA), marking the initiation of transcriptional control and gene expression post-fertilization. Histone modifications are pivotal in shaping cellular identity and gene expression in many mammals. Recent advances in chromatin analysis have enabled detailed explorations of histone modifications during ZGA. This review delves into conserved and unique regulatory strategies, providing essential insights into the dynamic changes in histone modifications and their variants during ZGA in mammals. The objective is to explore recent advancements in leading mechanisms related to histone modifications governing this embryonic development phase in depth. These considerations will be useful for informing future therapeutic approaches that target epigenetic regulation in diverse biological contexts. It will also contribute to the extensive areas of evolutionary and developmental biology and possibly lay the foundation for future research and discussion on this seminal topic. Full article