Search

Oocytes and embryos are highly sensitive to environmental stress in vivo and in vitro. During in vitro culture, many stressful conditions can affect embryo quality and viability, leading to adverse clinical outcomes such as abortion and congenital abnormalities. In this study, we found that valeric acid (VA) increased the mitochondrial membrane potential and ATP content, decreased the level of reactive oxygen species that the mitochondria generate, and thus improved mitochondrial function during early embryonic development in pigs. VA decreased expression of the autophagy-related factors LC3B and BECLIN1. Interestingly, VA inhibited expression of autophagy-associated phosphorylation-adenosine monophosphate-activated protein kinase (p-AMPK), phosphorylation-UNC-51-like autophagy-activated kinase 1 (p-ULK1, Ser555), and ATG13, which reduced apoptosis. Short-chain fatty acids (SCFAs) can signal through G-protein-coupled receptors on the cell membrane or enter the cell directly through transporters. We further show that the monocarboxylate transporter 1 (MCT1) was necessary for the effects of VA on embryo quality, which provides a new molecular perspective of the pathway by which SCFAs affect embryos. Importantly, VA significantly inhibited the AMPK-ULK1 autophagic signaling pathway through MCT1, decreased apoptosis, increased expression of embryonic pluripotency genes, and improved embryo quality. • VA significantly increased blastocyst formation rate, mitochondrial activity, while decreasing reactive oxygen species accumulation. • MCT1-mediated VA uptake could promote ATP production and inhibited p-AMPK in the embryo. • VA regulates the AMPK-ULK1 pathway to reduce autophagy and apoptosis and improve early embryo quality. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) is a gaseous signaling molecule produced in the body by three enzymes: cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST). H2S is crucial in various physiological processes associated with female mammalian reproduction. These include estrus cycle, oocyte maturation, oocyte aging, ovulation, embryo transport and early embryo development, the development of the placenta and fetal membranes, pregnancy, and the initiation of labor. Despite the confirmed presence of H2S-producing enzymes in all female reproductive tissues, as described in this review, the exact mechanisms of H2S action in these tissues remain in most cases unclear. Therefore, this review aims to summarize the knowledge about the presence and effects of H2S in these tissues and outline possible signaling pathways that mediate these effects. Understanding these pathways may lead to the development of new therapeutic strategies in the field of women’s health and perinatal medicine. [ABSTRACT FROM AUTHOR]

STUDY QUESTION How do transcriptomics vary in haploid human androgenote embryos at single cell level in the first four cell cycles of embryo development? SUMMARY ANSWER Gene expression peaks at the fourth cell cycle, however some androcytes exhibit unique transcriptional behaviors. WHAT IS KNOWN ALREADY The developmental potential of an embryo is determined by the competence of the oocyte and the sperm. However, studies of the contribution of the paternal genome using pure haploid androgenotes are very scarce. STUDY DESIGN, SIZE, DURATION This study was performed analyzing the single-cell transcriptomic sequencing of 38 androcytes obtained from 10 androgenote bioconstructs previously produced in vitro (de Castro et al. , 2023). These results were analyzed through different bioinformatics software such as g: Profiler, GSEA, Cytoscape, and Reactome. PARTICIPANTS/MATERIALS, SETTING, METHODS Single cell sequencing was used to obtain the transcriptomic profiles of the different androcytes. The results obtained were compared between the different cycles studied using the DESeq2 program and functional enrichment pathways using g: Profiler, Cytoscape, and Reactome. MAIN RESULTS AND THE ROLE OF CHANCE A wave of paternally driven transcriptomic activation was found during the third-cell cycle, with 1128 upregulated and 225 downregulated genes and the fourth-cell cycle, with 1373 upregulated and 286 downregulated genes, compared to first-cell cycle androcytes. Differentially expressed routes related to cell differentiation, DNA-binding transcription, RNA biosynthesis and RNA polymerase II transcription regulatory complex, and cell death were found in the third and fourth with respect to the first-cell cycle. Conversely, in the fourth cell cycle, 153 downregulated and 332 upregulated genes were found compared with third cell cycle, associated with differentially expressed processes related to E-box binding and zinc finger protein 652 (ZNF652) transcription factor. Further, significant overexpression of LEUTX, PRAMEF1, DUXA, RFPL4A, TRIM43, and ZNF675 found in androgenotes, compared to biparental embryos, highlights the paternal contributions to zygote genome activation. LARGE SCALE DATA All raw sequencing data are available through the Gene Expression Omnibus (GEO) under accessions number: GSE216501. LIMITATIONS, REASONS FOR CAUTION Extrapolation of biological events from uniparental constructs to biparental embryos should be done with caution. Maternal and paternal genomes do not act independently of each other in a natural condition. The absence of one genome may affect gene transcription of the other. In this sense, the haploid condition of the bioconstructs could mask the transcriptomic patterns of the single cells. WIDER IMPLICATIONS OF THE FINDINGS The results obtained demonstrated the level of involvement of the human paternal haploid genome in the early stages of embryo development as well as its evolution at the transcriptomic level, laying the groundwork for the use of these bioconstructs as reliable models to dispel doubts about the genetic role played by the paternal genome in the early cycles of embryo development. STUDY FUNDING/COMPETING INTEREST(S) This study was funded by Instituto de Salud Carlos III (ISCIII) through the project 'PI22/00924', co-funded by European Regional Development Fund (ERDF); 'A way to make Europe'. F.D. was supported by the Spanish Ministry of Economy and Competitiveness through the Miguel Servet program (CPII018/00002). M.J.E. was supported by Instituto de Salud Carlos III (PI19/00577 [M.J.E.]) and FI20/00086. P.dC. was supported by a predoctoral grant for training in research into health (PFIS PI19/00577) from the Instituto de Salud Carlos III. All authors declare having no conflict of interest with regard to this trial. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) is a gaseous signaling molecule produced in the body by three enzymes: cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST). H2S is crucial in various physiological processes associated with female mammalian reproduction. These include estrus cycle, oocyte maturation, oocyte aging, ovulation, embryo transport and early embryo development, the development of the placenta and fetal membranes, pregnancy, and the initiation of labor. Despite the confirmed presence of H2S-producing enzymes in all female reproductive tissues, as described in this review, the exact mechanisms of H2S action in these tissues remain in most cases unclear. Therefore, this review aims to summarize the knowledge about the presence and effects of H2S in these tissues and outline possible signaling pathways that mediate these effects. Understanding these pathways may lead to the development of new therapeutic strategies in the field of women’s health and perinatal medicine.

Ferroptosis suppressor protein 1 (FSP1) is a glutathione-independent ferroptosis inhibitory factor. FSP1 has been found to play a crucial role in the regulation of mitochondrial function and ferroptosis. However, its function in porcine early embryonic development remains unknown. In the present research, we found that FSP1 was expressed at different stages during porcine early embryo development. Compared with the control condition, inhibition of FSP1 reduced the cleavage rate at 24 h and 48 h and the blastocyst rate at 144 h. In addition, inhibiting FSP1 reduced the blastocyst diameter, total cell number, and proliferation capacity. Further analysis showed that inhibition of FSP1 significantly increased the levels of ferrous ions (Fe2+) and MDA but not GPX4. We also found that inhibition of FSP1 significantly decreased mitochondrial membrane potential and ATP levels, which in turn caused excessive accumulation of ROS and decreased the levels of GSH and the activity of the intracellular antioxidant enzymes SOD and CAT in embryos. In conclusion, FSP1, an important regulator, participates in regulating the development and quality of porcine early embryos. Inhibition of FSP1 impairs blastocyst formation, induces glutathione-independent ferroptosis, and further leads to oxidative stress due to mitochondrial dysfunction, ultimately affecting the developmental competence and impairing the quality of porcine early embryos. • FSP1 is required for porcine early embryo development. • Inhibition of FSP1 leads to ferrous ions and MDA levels increasing in porcine early embryos. • Inhibition of FSP1 leads to oxidative stress and mitochondrial dysfunction in porcine early embryos. [ABSTRACT FROM AUTHOR]

Phthalates are a class of environmental endocrine disrupting chemicals which can cause reproductive system damages. However, data about reproductive toxicity spectrum of phthalate metabolites among Chinese women undergoing in vitro fertilization (IVF) treatments are scarce yet. Previous studies regarding underlying embryo toxicities focused on oxidative stress and apoptosis, while energy metabolism abnormality might be another key cause for embryo developmental disruptions. Here, we found that among the measured eight phthalate metabolites, monomethyl phthalate (MMP) had the second highest urinary concentration in women receiving IVF. Compare to the lowest exposure level group, MMP in tertile 3 was associated with fewer counts of oocyte retrieved and good-quality embryos, and MMP in tertile 2 was correlated with reduced good-quality embryo rate. The direct embryo toxicities of MMP were studied using mouse 2-cell embryos. Consistent to results found in human populations, exposure to MMP induced mouse early embryo developmental delay. Furthermore, MMP exposure led to excessive reactive oxygen species production in early embryos, and antioxidant can partially rescue the early embryo development slow down. Embryo apoptosis could also be caused by oxidative stress. To be noted, elevated apoptosis level was not found in live "slow" embryos but dead embryos, which suggested that apoptosis was not related to early embryo developmental delay. Additionally, MMP exposure depleted adenosine triphosphate (ATP) synthesis of early embryos, which could be reversed by antioxidant. In conclusion, MMP, as the newly found embryonic toxicant in Chinese women, resulted in early embryo development delay, apoptosis, and energy metabolism disruptions via inducing redox imbalance. [ABSTRACT FROM AUTHOR]

Abstract Background The oocyte-to-embryo transition (OET) converts terminally differentiated gametes into a totipotent embryo and is critically controlled by maternal mRNAs and proteins, while the genome is silent until zygotic genome activation. How the transcriptome, translatome, and proteome are coordinated during this critical developmental window remains poorly understood. Results Utilizing a highly sensitive and quantitative mass spectrometry approach, we obtain high-quality proteome data spanning seven mouse stages, from full-grown oocyte (FGO) to blastocyst, using 100 oocytes/embryos at each stage. Integrative analyses reveal distinct proteome reprogramming compared to that of the transcriptome or translatome. FGO to 8-cell proteomes are dominated by FGO-stockpiled proteins, while the transcriptome and translatome are more dynamic. FGO-originated proteins frequently persist to blastocyst while corresponding transcripts are already downregulated or decayed. Improved concordance between protein and translation or transcription is observed for genes starting translation upon meiotic resumption, as well as those transcribed and translated only in embryos. Concordance between protein and transcription/translation is also observed for proteins with short half-lives. We built a kinetic model that predicts protein dynamics by incorporating both initial protein abundance in FGOs and translation kinetics across developmental stages. Conclusions Through integrative analyses of datasets generated by ultrasensitive methods, our study reveals that the proteome shows distinct dynamics compared to the translatome and transcriptome during mouse OET. We propose that the remarkably stable oocyte-originated proteome may help save resources to accommodate the demanding needs of growing embryos. This study will advance our understanding of mammalian OET and the fundamental principles governing gene expression.

Peptidyl arginine deiminase 6 (PADI6) is a maternal factor that is vital for early embryonic development. Deletion and mutations of its encoding gene in female mice or women lead to early embryonic developmental arrest, female infertility, maternal imprinting defects and hyperproliferation of the trophoblast. PADI6 is the fifth and least well-characterized member of the peptidyl arginine deiminases (PADIs), which catalyse the post-translational conversion of arginine to citrulline. It is less conserved than the other PADIs, and currently has no reported catalytic activity. While there are many suggested functions of PADI6 in the early mouse embryo, including in embryonic genome activation, cytoplasmic lattice formation, maternal mRNA and ribosome regulation, and organelle distribution, the molecular mechanisms of its function remain unknown. In this review, we discuss what is known about the function of PADI6 and highlight key outstanding questions that must be answered if we are to understand the crucial role it plays in early embryo development and female fertility. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'. [ABSTRACT FROM AUTHOR]

BACKGROUND It has long been thought that the factors affecting embryo and foetal development were exclusively maternally derived; hence, if issues regarding fertility and embryo development were to arise, the blame has traditionally been placed solely on the mother. An escalating interest in how paternal factors influence embryo development, however, has begun to prove otherwise. Evidence suggests that both seminal plasma (SP) and sperm contribute multiple factors that shape embryogenesis. This review thus focuses on the role that semen has in driving early embryonic development, and describes how paternal factors, such as SP, sperm centriole, sperm proteins, sperm RNA, sperm DNA, and its integrity, together with epigenetics, may influence the female reproductive tract and post-fertilization events. The important contributions of paternal factors to embryo development highlight the imperative need for further research in this area, which is sure to bring forth breakthroughs leading to improvements in infertility diagnosis and ART as well as reducing the risk of miscarriage. OBJECTIVE AND RATIONALE This review provides a comprehensive overview of the role of human semen in development of the early embryo, with the aim of providing a better understanding of the influence of SP and sperm on early embryonic divisions, gene and protein expression, miscarriage, and congenital diseases. SEARCH METHODS PubMed searches were performed using the terms 'sperm structure', 'capacitation', 'acrosome reaction', 'fertilization', 'oocyte activation', 'PLCζ', 'PAWP', 'sperm-borne oocyte activation factor', 'oocyte activation deficiency', 'sperm centriole', 'sperm transport', 'sperm mitochondria', 'seminal plasma', 'sperm epigenetics', 'sperm histone modifications', 'sperm DNA methylation', 'sperm-derived transcripts', 'sperm-derived proteins', 'sperm DNA fragmentation', 'sperm mRNA', 'sperm miRNAs', 'sperm piRNAs', and 'sperm-derived aneuploidy'. The reviewed articles were restricted to those published in English between 1980 and 2022. OUTCOMES The data suggest that male-derived factors contribute much more than just the male haploid genome to the early embryo. Evidence indicates that semen contributes multiple factors that help shape the fate of embryogenesis. These male-derived factors include contributions from SP, the paternal centriole, RNA and proteins, and DNA integrity. In addition, epigenetic changes have an impact on the female reproductive tract, fertilization, and early stages of embryo development. For example, recent proteomic and transcriptomic studies have identified several sperm-borne markers that play important roles in oocyte fertilization and embryogenesis. WIDER IMPLICATIONS This review highlights that several male-derived factors are required to work in tandem with female counterparts to allow for correct fertilization and development of the early embryo. A deeper understanding of the contributions of paternal factors that are shuttled over from the sperm cell to the embryo can shed light on how to improve ART from an andrological perspective. Further studies may aid in preventing the passing on of genetic and epigenetic abnormalities of paternal origin, thus decreasing the incidence of male factor infertility. In addition, understanding the exact mechanisms of paternal contribution may assist reproductive scientists and IVF clinicians in determining new causes of recurrent early miscarriage or fertilization failure. [ABSTRACT FROM AUTHOR]

Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2/B1) is an N6-methyladenosine (m6A) RNA modification regulator and a key determinant of pre- mRNA processing, mRNA metabolism and transportation in cells. Currently, m6A reader proteins such as hnRNPA2/B1 and YTHDF2 has functional roles in mice embryo. However, the role of hnRNPA2/B1 in porcine embryogenic development are unclear. Here, we investigated the developmental competence and mRNA expression levels in porcine parthenogenetic embryos after hnRNPA2/B1 knock-down. HhnRNPA2/B1 was localized in the nucleus during subsequent embryonic development since zygote stage. After hnRNPA2/B1 knock-down using double stranded RNA injection, blastocyst formation rate decreased than that in the control group. Moreover, hnRNPA2/B1 knock-down embryos show developmental delay after compaction. In blastocyste stage, total cell number was decreased. Interestingly, gene expression patterns revealed that transcription of Pou5f1, Sox2, TRFP2C, Cdx2 and PARD6B decreased without changing the junction protein, ZO1, OCLN, and CDH1. Thus, hnRNPA2/B1 is necessary for porcine early embryo development by regulating gene expression through epigenetic RNA modification.

Context: Heat stress has been related to reduced fertility in cattle, which may reflect damage to developing oocytes. The deleterious effects of heat stress on oocytes may involve an increased production of reactive oxygen species (ROS). The addition of antioxidants, such as melatonin, to the in vitro maturation medium of heat-stressed bovine oocytes may be advantageous for reducing ROS concentrations, thereby enhancing the subsequent fertilisation and development to the blastocyst stage. Aims: The present study evaluated the in vitro production and quality of bovine embryos derived from oocytes matured under heat-shock conditions with increasing melatonin concentrations. Methods: Cumulus–oocyte complexes from Bos taurus × Bos indicus cows were matured under heat shock (12 h at 41°C, followed by 12 h at 38.5°C) in medium without melatonin (control) or with 10−12, 10−9, 10−6 and 10−3 mol/L melatonin. Logistic regression equations were adjusted when the main effect of melatonin was observed. Key results: The cleavage rate on Day 3 of culture, the production of blastocysts on Days 7 and 8, the number and proportion of apoptotic cells in expanded blastocysts, and the proportion of apoptotic cells in the inner cell mass (ICM) were not affected by melatonin. The proportion of 8- to 16-cell-stage embryos on Day 3 and the proportion of ICM cells in expanded blastocysts were influenced by the melatonin concentration. Through logistic regression, it was estimated that the proportion of 8- to 16-cell-stage embryos increased linearly as the melatonin increased until 10−3 mol/L, and that the proportion of ICM cells in blastocysts was maximised between 10−6 and 10−4 mol/L melatonin, and decreased thereafter. Conclusions: Melatonin at 10−3 mol/L in the in vitro maturation (IVM) of heat-shocked oocytes stimulated the first embryo cleavages but reduced the ratio of ICM cells in blastocysts. The embryo quality may be improved by melatonin between 10−6 and 10−4 mol/L. Implications: The addition of melatonin to IVM medium has the potential to improve the quality of bovine embryos from heat-stressed oocytes. Among the many challenges, the increase in global temperature is a prominent interference in reproductive processes in dairy cattle, since it has deleterious effects on gametes. Therefore, strategies such as the use of substances that reduce the damage caused by thermal stress have been widely used in scientific experiments. In the present study, the use of the antioxidant melatonin in the in vitro maturation medium of heat-stressed bovine oocytes was able to improve embryo quality. [ABSTRACT FROM AUTHOR]

Pluripotent stem cells (PSCs), which can self-renew and give rise to all cell types in all three germ layers, have great potential in regenerative medicine. Recent studies have shown that PSCs can have three distinct but interrelated pluripotent states: naive, formative, and primed. The PSCs of each state are derived from different stages of the early developing embryo and can be maintained in culture by different molecular mechanisms. In this review, we summarize the current understanding on features of the three pluripotent states and review the underlying molecular mechanisms of maintaining their identities. Lastly, we discuss the interrelation and transition among these pluripotency states. We believe that comprehending the divergence of pluripotent states is essential to fully harness the great potential of stem cells in regenerative medicine. [ABSTRACT FROM AUTHOR]

To estimate the repro‐protective effect of royal jelly (RJ) on phenylhydrazine (PHZ)‐induced anemia's detrimental effects, 24 mature mice were divided into control group (0.10 mL normal saline; intra‐peritoneally), RJ group (100 mg/kg/day; orally), experimental anemia (EA) group that received only PHZ (6 mg/100 g/48 h; intra‐peritoneally), and RJ + EA (according to the previous prescription) group. After 35 days, testicular histoarchitecture, RNA damage in germinal cells, sperm characteristics, testicular total anti‐oxidant capacity and malondialdehyde as well as serum testosterone levels, pre‐implantation embryo development and cyclin D1 and c‐myc mRNA levels at two‐cell, morula and blastocyst stages were analyzed. Spermatogenesis indices were ameliorated following RJ co‐administration. Moreover, RJ co‐treatment reduced germinal cells RNA damage, improved sperm characteristics, boosted pre‐implantation embryo development and restored androgenesis, and oxidant/anti‐oxidant status. Co‐administration of RJ also decreased mRNA levels of cyclin D1 and up‐regulated those of c‐myc in two‐cell embryos, morulas and blastocysts. The findings suggest that RJ can play a repro‐protective role in PHZ‐induced anemia in mice through anti‐oxidant defense system reinforcement and androgenesis restoration as well as cyclin D1 and c‐myc expressions regulation. [ABSTRACT FROM AUTHOR]

Background: Dynamic chromatin reorganization occurs during two waves of cell lineage specification process, blastocyst formation and gastrulation, to generate distinct cell types. Epigenetic defects have been associated with severe developmental defects and diseases. How epigenetic remodeling coordinates the two lineage specification waves is becoming uncovered, benefiting from the development and application of new technologies including low-input or single-cell epigenome analysis approached in the past few years. Objective: In this review, we aim to highlight the most recent findings on epigenetic remodeling in cell lineage specification during blastocyst formation and gastrulation. Methods: First, we introduce how DNA methylation dynamically changes in blastocyst formation and gastrulation and its function in transcriptional regulation lineage-specific genes. Then, we discuss widespread remodeling of histone modification at promoters and enhancers in orchestrating the trajectory of cell lineage specification. Finally, we review dynamics of chromatin accessibility and 3D structure regulating developmental gene expression and associating with specific transcription factor binding events at stage specific manner. We also highlight the key questions that remain to be answered to fully understand chromatin regulation and reorganization in lineage specification. Conclusion: Here, we summarize the recent advances and discoveries on epigenetic reorganization and its roles in blastocyst formation and gastrulation, and how it cooperates with the lineage specification, painting from global sequencing data from mouse in vivo tissues. [ABSTRACT FROM AUTHOR]

The early stages of mammalian embryonic development involve the participation and cooperation of numerous complex processes, including nutritional, genetic, and epigenetic mechanisms. However, in embryos cultured in vitro , a developmental block occurs that affects embryo development and the efficiency of culture. Although the block period is reported to involve the transcriptional repression of maternal genes and transcriptional activation of zygotic genes, how epigenetic factors regulate developmental block is still unclear. In this study, we systematically analyzed whole-genome methylation levels during five stages of sheep oocyte and preimplantation embryo development using single-cell level whole genome bisulphite sequencing (SC-WGBS) technology. Then, we examined several million CpG sites in individual cells at each evaluated developmental stage to identify the methylation changes that take place during the development of sheep preimplantation embryos. Our results showed that two strong waves of methylation changes occurred, namely, demethylation at the 8-cell to 16-cell stage and methylation at the 16-cell to 32-cell stage. Analysis of DNA methylation patterns in different functional regions revealed a stable hypermethylation status in 3′UTRs and gene bodies; however, significant differences were observed in intergenic and promoter regions at different developmental stages. Changes in methylation at different stages of preimplantation embryo development were also compared to investigate the molecular mechanisms involved in sheep embryo development at the methylation level. In conclusion, we report a detailed analysis of the DNA methylation dynamics during the development of sheep preimplantation embryos. Our results provide an explanation for the complex regulatory mechanisms underlying the embryo developmental block based on changes in DNA methylation levels. [ABSTRACT FROM AUTHOR]

Abstract Mammalian fertilization begins with the fusion of two specialized gametes, followed by major epigenetic remodeling leading to the formation of a totipotent embryo. During the development of the pre-implantation embryo, precise reprogramming progress is a prerequisite for avoiding developmental defects or embryonic lethality, but the underlying molecular mechanisms remain elusive. For the past few years, unprecedented breakthroughs have been made in mapping the regulatory network of dynamic epigenomes during mammalian early embryo development, taking advantage of multiple advances and innovations in low-input genome-wide chromatin analysis technologies. The aim of this review is to highlight the most recent progress in understanding the mechanisms of epigenetic remodeling during early embryogenesis in mammals, including DNA methylation, histone modifications, chromatin accessibility and 3D chromatin organization.

Posttranscriptional modification of mRNA sequences through RNA editing can increase transcriptome and proteome diversity in eukaryotes. Studies of fetal and adult tissues showed that adenosine‐to‐inosine RNA editing plays a crucial role in early human development, but there is a lack of global understanding of dynamic RNA editing during mammalian early embryonic development. Therefore, here we used RNA sequencing data from human, pig and mouse during early embryonic development to detect edited genes that may regulate stem cell pluripotency. We observed that although most of the RNA editing sites are located in intergenic, intron and UTR, a few editing sites are in coding regions and may result in nonsynonymous amino acid changes. Some editing sites are predicted to change the structure of a protein. We also report that HNF1A, TBX3, ACLY, ECI1 and ERDR1 are related to embryonic development and cell division.

The early stages of mammalian embryonic development involve the participation and cooperation of numerous complex processes, including nutritional, genetic, and epigenetic mechanisms. However, in embryos cultured in vitro, a developmental block occurs that affects embryo development and the efficiency of culture. Although the block period is reported to involve the transcriptional repression of maternal genes and transcriptional activation of zygotic genes, how epigenetic factors regulate developmental block is still unclear. In this study, we systematically analyzed whole-genome methylation levels during five stages of sheep oocyte and preimplantation embryo development using single-cell level whole genome bisulphite sequencing (SC-WGBS) technology. Then, we examined several million CpG sites in individual cells at each evaluated developmental stage to identify the methylation changes that take place during the development of sheep preimplantation embryos. Our results showed that two strong waves of methylation changes occurred, namely, demethylation at the 8-cell to 16-cell stage and methylation at the 16-cell to 32-cell stage. Analysis of DNA methylation patterns in different functional regions revealed a stable hypermethylation status in 3′UTRs and gene bodies; however, significant differences were observed in intergenic and promoter regions at different developmental stages. Changes in methylation at different stages of preimplantation embryo development were also compared to investigate the molecular mechanisms involved in sheep embryo development at the methylation level. In conclusion, we report a detailed analysis of the DNA methylation dynamics during the development of sheep preimplantation embryos. Our results provide an explanation for the complex regulatory mechanisms underlying the embryo developmental block based on changes in DNA methylation levels.

Eukaryotic translation initiation factor 4E (eIF4E) mediates capdependent translation. Genetic and inhibitor studies show that eIF4E expression is required for the successful transition from maternal to embryonic control of mouse embryo development. eIF4E was present in the oocyte and in the cytoplasm soon after fertilization and during each stage of early development. Functional knockout (Eif4e−/−) by PiggyBac [Act-RFP] transposition resulted in peri-implantation embryonic lethality because of the failure of normal epiblast formation. Maternal stores of eIF4E supported development up to the two- to four-cell stage, after which new expression occurred from both maternal and paternal inherited alleles. Inhibition of the maternally acquired stores of eIF4E (using the inhibitor 4EGI-1) resulted in a block at the two-cell stage. eIF4E activity was required for new protein synthesis in the two-cell embryo and Eif4e−/− embryos had lower translational activity compared with wild-type embryos. eIF4E-binding protein 1 (4E-BP1) is a hypophosphorylation-dependent negative regulator of eIF4E. mTOR activity was required for 4E-BP1 phosphorylation and inhibiting mTOR retarded embryo development. Thus, this study shows that eIF4E activity is regulated at key embryonic transitions in themammalian embryo and is essential for the successful transition from maternal to embryonic control of development. [ABSTRACT FROM AUTHOR]

As a major protein of the polyhedral coat of coated pits and vesicles, clathrin molecules have been shown to play a stabilization role for kinetochore fibers of the mitotic spindle by acting as inter-microtubule bridges. Clathrin heavy chain 1 (CLTC), the basic subunit of the clathrin coat, plays vital roles in both spindle assembly and chromosome congression during somatic-cell mitosis. However, its function in oocyte meiotic maturation and early embryo development in mammals, especially in domesticated animals, has not been fully investigated. In this study, the expression profiles and functional roles of CLTC in sheep oocytes were investigated. Our results showed that the expression of CLTC was maintained at a high level from the germinal vesicle (GV) stage to metaphase II stage and that CLTC was distributed diffusely in the cytoplasm of cells at interphase, from the GV stage to the blastocyst stage. After GV breakdown (GVBD), CLTC co-localized with beta-tubulin during metaphase. Oocyte treatments with taxol, nocodazole, or cold did not affect CLTC expression levels but led to disorders of its distribution. Functional impairment of CLTC by specific morpholino injections in GV-stage oocytes led to disruptions in spindle assembly and chromosomal alignment, accompanied by impaired first polar body (PB1) emissions. In addition, knockdown of CLTC before parthenogenetic activation disrupted spindle formation and impaired early embryo development. Taken together, the results demonstrate that CLTC plays a vital role in sheep oocyte maturation via the regulation of spindle dynamics and an essential role during early embryo development.

Mammalian fertilization begins with the fusion of two specialized gametes, followed by major epigenetic remodeling leading to the formation of a totipotent embryo. During the development of the pre-implantation embryo, precise reprogramming progress is a prerequisite for avoiding developmental defects or embryonic lethality, but the underlying molecular mechanisms remain elusive. For the past few years, unprecedented breakthroughs have been made in mapping the regulatory network of dynamic epigenomes during mammalian early embryo development, taking advantage of multiple advances and innovations in low-input genome-wide chromatin analysis technologies. The aim of this review is to highlight the most recent progress in understanding the mechanisms of epigenetic remodeling during early embryogenesis in mammals, including DNA methylation, histone modifications, chromatin accessibility and 3D chromatin organization. [ABSTRACT FROM AUTHOR]

The sequential change from totipotency to multipotency occurs during early mammalian embryo development. However, due to the lack of cellular models to recapitulate the distinct potency of stem cells at each stage, their molecular and cellular characteristics remain ambiguous. The establishment of isogenic naïve and primed pluripotent stem cells to represent the pluripotency in the inner cell mass of the pre-implantation blastocyst and in the epiblast from the post-implantation embryo allows the understanding of the distinctive characteristics of two different states of pluripotent stem cells. This review discusses the prominent disparities between naïve and primed pluripotency, including signaling pathways, metabolism, and epigenetic status, ultimately facilitating a comprehensive understanding of their significance during early mammalian embryonic development.

In contrast to the homeokinesis of mitosis, asymmetric division of cytoplasm is the conspicuous feature of meiosis in mammalian oocytes. Protein regulator of cytokinesis 1 (PRC1) is an important regulator during mitotic spindle assembly and cytoplasmic division, but its functions in oocyte meiosis and early embryo development have not been fully elucidated. In this study, we detected PRC1 expression and localization and revealed a nuclear, spindle midzone‐related dynamic pattern throughout meiotic and mitotic progressions. Treatment of oocytes with the reagents taxol or nocodazole disturbed the distribution of PRC1 in metaphase II oocytes. Further, PRC1 depletion led to failure of first polar body (PB1) extrusion and spindle migration, aneuploidy and defective kinetochore–microtubule attachment and spindle assembly. Overexpression of PRC1 resulted in PB1 extrusion failure, aneuploidy and serious defects of spindle assembly. To investigate PRC1 function in early embryos, we injected Prc1 morpholino into zygotes and 2‐cell stage embryos. Depletion of PRC1 in zygotes impaired 4‐cell, morula and blastocyst formation. Loss of PRC1 in single or double blastomeres in 2‐cell stage embryos significantly impaired cell division, indicating its indispensable role in early embryo development. Co‐immunoprecipitation showed that PRC1 interacts with polo‐like kinase 1 (PLK1), and functional knockdown and rescue experiments demonstrated that PRC1 recruits PLK1 to the spindle midzone to regulate cytoplasmic division during meiosis. Finally, kinesin family member 4 knockdown downregulates PRC1 expression and leads to PRC1 localization failure. Taken together, our data suggest PRC1 plays an important role during oocyte maturation and early embryonic development by regulating chromosome dynamics and cytoplasmic division. [ABSTRACT FROM AUTHOR]

Objectives: Mouse embryonic stem cell (mESC) culture contains various heterogeneous populations, which serve as excellent models to study gene regulation in early embryo development. The heterogeneity is typically defined by transcriptional activities, for example, the expression of Nanog or Rex1 mRNA. Our objectives were to identify mESC heterogeneity that are caused by mechanisms other than transcriptional control. Materials and methods: Klf3 mRNA and protein were analysed by RT‐qPCR, Western blotting or immunofluorescence in mESCs, C2C12 cells, early mouse embryos and various mouse tissues. An ESC reporter line expressing KLF3‐GFP fusion protein was made to study heterogeneity of KLF3 protein expression in ESCs. GFP‐positive mESCs were sorted for further analysis including RT‐qPCR and RNA‐seq. Results: In the majority of mESCs, KLF3 protein is actively degraded due to its proline‐rich sequence and highly disordered structure. Interestingly, KLF3 protein is stabilized in a small subset of mESCs. Transcriptome analysis indicates that KLF3‐positive mESCs upregulate genes that are initially activated in 8‐cell embryos. Consistently, KLF3 protein but not mRNA is dramatically increased in 8‐cell embryos. Forced expression of KLF3 protein in mESCs promotes the expression of 8‐cell‐embryo activated genes. Conclusions: Our study identifies previously unrecognized heterogeneity due to KLF3 protein expression in mESCs. [ABSTRACT FROM AUTHOR]

Maternal mRNA degradation is a critical event of the maternal‐to‐zygotic transition (MZT) that determines the developmental potential of early embryos. Nuclear Poly(A)‐binding proteins (PABPNs) are extensively involved in mRNA post‐transcriptional regulation, but their function in the MZT has not been investigated. In this study, we find that the maternally expressed PABPN1‐like (PABPN1L), rather than its ubiquitously expressed homolog PABPN1, acts as an mRNA‐binding adapter of the mammalian MZT licensing factor BTG4, which mediates maternal mRNA clearance. Female Pabpn1l null mice produce morphologically normal oocytes but are infertile owing to early developmental arrest of the resultant embryos at the 1‐ to 2‐cell stage. Deletion of Pabpn1l impairs the deadenylation and degradation of a subset of BTG4‐targeted maternal mRNAs during the MZT. In addition to recruiting BTG4 to the mRNA 3ʹ‐poly(A) tails, PABPN1L is also required for BTG4 protein accumulation in maturing oocytes by protecting BTG4 from SCF‐βTrCP1 E3 ubiquitin ligase‐mediated polyubiquitination and degradation. This study highlights a noncanonical cytoplasmic function of nuclear poly(A)‐binding protein in mRNA turnover, as well as its physiological importance during the MZT. Synopsis: The maternal‐effect factor PABPN1‐like (PABPN1L) mediates maternal mRNA decay by acting as mRNA‐binding adapter of the mammalian MZT licensing factor BTG4 in the cytoplasm. Female Pabpn1l null mice are infertile due to impaired deadenylation and degradation of a subset of maternal mRNAs during the MZT.PABPN1L recruits BTG4 and CCR4‐NOT deadenylase to the 3ʹ‐poly(A) tail of maternal transcripts.Arg‐171 within the RNA recognition motif (RRM) is essential for the poly(A)‐binding ability of PABPN1L.PABPN1L protects BTG4 from SCF‐βTrCP1 E3 ubiquitin ligase‐mediated polyubiquitination and degradation. [ABSTRACT FROM AUTHOR]

Posttranscriptional modification of mRNA sequences through RNA editing can increase transcriptome and proteome diversity in eukaryotes. Studies of fetal and adult tissues showed that adenosine‐to‐inosine RNA editing plays a crucial role in early human development, but there is a lack of global understanding of dynamic RNA editing during mammalian early embryonic development. Therefore, here we used RNA sequencing data from human, pig and mouse during early embryonic development to detect edited genes that may regulate stem cell pluripotency. We observed that although most of the RNA editing sites are located in intergenic, intron and UTR, a few editing sites are in coding regions and may result in nonsynonymous amino acid changes. Some editing sites are predicted to change the structure of a protein. We also report that HNF1A, TBX3, ACLY, ECI1 and ERDR1 are related to embryonic development and cell division. [ABSTRACT FROM AUTHOR]

DNA methylation and histone modification are two of the most characterized epigenetic modifications. With advanced detecting techniques, particularly single-cell sequencing, we can dissect epigenomic patterns and their regulatory roles in the growth and differentiation of gametes and early embryos in animals and humans. Assisted reproductive technology (ART) procedures have been shown to influence the methylation of certain genes. Aberrant epigenetic regulation may cause several developmental disorders and clinical diseases. Here, we describe some concepts in epigenetics and review recent researches on DNA methylation and the histone modification profile and their regulatory roles during early embryo development. We also summarize the recent progress in understanding the imprinting disorders associated with ART procedures.

Embryogenesis is one of the most important processes in the life of an animal. During this dynamic process, progressive cell division and cellular differentiation are accompanied by significant changes in protein expression at the level of the proteome. However, very few studies to date have described the dynamics of the proteome during the early development of an embryo in any organism. In this dataset, we monitor changes in protein expression across a timecourse of more than 20 h of Drosophila melanogaster embryonic development. Mass-spectrometry data were produced using a SWATH acquisition mode on a Sciex Triple-TOF 6600. A spectral library built in-house was used to analyse these data and more than 1950 proteins were quantified at each embryonic timepoint. The files presented here are a permanent digital map and can be reanalysed to test against new hypotheses. The data have been deposited with the ProteomeXchange Consortium with the dataset identifier PRIDE: PXD0031078.

Inhibition of both MEK1/2 and glycogen synthase kinase-3 (GSK3; 2i system) facilitates the maintenance of naïve stemness for embryonic stem cells in various mammalian species. However, the effect of the inhibition of the 2i system on porcine early embryogenesis is unknown. We investigated the effect of the 2i system on early embryo development, expression of pluripotency-related genes, and epigenetic modifications. Inhibition of MEK1/2 (by PD0325901) and/or GSK3 (by CHIR99021) did not alter the developmental potential of porcine parthenogenetic embryos, but improved blastocyst quality, as judged by the blastocyst cell number, diameter, and reduction in the number of apoptotic cells. The expression levels of octamer-binding transcription factor 4 and SOX2, the primary transcription factors that maintain embryonic pluripotency, were significantly increased by 2i treatments. Epigenetic modification-related gene expression was altered upon 2i treatment. The collective results indicate that the 2i system in porcine embryos improved embryo developmental potential and blastocyst quality by regulating epigenetic modifications and pluripotency-related gene expression.

Purpose: Oocyte and embryo quality differs significantly among individuals. Follicular fluid (FF) is a solo environment of oocyte maturation and may flux into the oviduct. Supplementation of in vitro maturation (IVM) and culture (IVC) medium with extracellular vesicles of FFs supports oocyte maturation and embryonic development. We addressed a hypothesis that miRNA profiles in FFs are crucial background of oocyte maturation and embryonic development., Methods: FFs were collected from the ovaries of individual cows, and the FFs were classified into Good or Poor FF based on the developmental rate to the blastocyst stage of enclosed oocytes. miRNAs associated with the Good FFs were explored using small RNA sequencing. In addition, FFs were classified using the concentration of Good-FF-associated miRNAs. These classified FFs or miRNA were added to the IVM or IVC mediums., Results: Supplementation of IVM and IVC medium with Good FF improved embryonic development. Good FFs contained miR-151-3p and miR-425-5p at a high concentration compared with those in Poor FFs. FFs selected by the concentration of miR-151-3p and miR-425-5p improved oocyte maturation and embryonic development. Supplementation of IVM or IVC medium with either miR-151-3p or miR-425-5p improved embryonic development to the blastocyst stage., Conclusion: miRNAs were associated with the Good FFs determined oocyte maturation and embryonic development., Competing Interests: Authors declare that there are no conflicts of interest for this article. Hisataka IWATA is an Editorial Board member of Reproductive Medicine and Biology and a co‐author of this article. To minimize bias, they were excluded from all editorial decision‐making related to the acceptance of this article for publication., (© 2024 The Authors. Reproductive Medicine and Biology published by John Wiley & Sons Australia, Ltd on behalf of Japan Society for Reproductive Medicine.)

Aneuploidy caused by abnormal chromosome segregation during early embryo development leads to embryonic death or congenital malformation. Centromere protein F (CENPF) is a member of centromere protein family that regulates chromosome segregation during mitosis. However, its necessity in early embryo development has not been fully investigated. In this study, expression and function of CENPF was investigated in mouse early embryogenesis. Detection of CENPF expression and localization revealed a cytoplasm, spindle and nuclear membrane related dynamic pattern throughout mitotic progression. Farnesyltransferase inhibitor (FTI) was employed to inhibit CENPF farnesylation in zygotes. The results showed that CENPF degradation was inhibited and its specific localization on nuclear membranes in morula and blastocyst vanished after FTI treatment. Also, CAAX motif mutation leads to failure of CENPF-C630 localization in morula and blastocyst. These results indicate that farnesylation plays a key role during CENPF degradation and localization in early embryos. To further assess CENPF function in parthenogenetic or fertilized embryos development, morpholino (MO) and Trim-Away were used to disturb CENPF function. CENPF knockdown in Metaphase II (MII) oocytes, zygotes or embryos with MO approach resulted in failure to develop into morulae and blastocysts, revealing its indispensable role in both parthenogenetic and fertilized embryos. Disturbing of CENPF with Trim-Away approach in zygotes resulted in impaired development of 2-cell and 4-cell, but did not affect the morula and blastocyst formation because of the recovered expression of CENPF. Taken together, our data suggest CENPF plays an important role during early embryonic development in mice. Abbreviation: CENPF: centromere protein F; MO: morpholino; FTI: Farnesyltransferase inhibitor; CENPE: centromere protein E; IVF: in vitro fertilization; MII: metaphase II; SAC: spindle assembly checkpoint; Mad1: mitotic arrest deficient 1; BUB1: budding uninhibited by benzimidazole 1; BUBR1: BUB1 mitotic checkpoint serine/threonine kinase B; Cdc20: cell division cycle 20 [ABSTRACT FROM AUTHOR]

Mitochondrial DNA (mtDNA) is important for oxidative phosphorylation; dysfunctions can play a role in many mitochondrial diseases and can also affect the aging of cells and individuals. DNA methylation is an important epigenetic modification that plays a critical role in regulating gene expression. While recent studies have revealed the existence of mtDNA methylation there are still controversies about mtDNA methylation due to the special structure of mtDNA. Mitochondria and DNA methylation are both essential for regulating oocyte maturation and early embryo development, but whether mtDNA methylation changes during this process is unknown. By employing bisulfite sequencing, we found that in the process of mouse oocyte maturation, postovulatory oocyte aging, and early embryo development, all analyzed mitochondrial genes, including 16S-CpGI , DCR , ND6 , 12S , and ATP8, lacked 5'mC. Thus, mtDNA methylation does not occur in the oocyte and early embryo. [ABSTRACT FROM AUTHOR]

Embryonic lipids are crucial for the formation of cellular membranes and dynamically participate in metabolic pathways. Cells can synthesize simple fatty acids, and the elongation of fatty acids facilitates the formation of complex lipids. The aim of this work was to investigate the involvement of the elongation of very long chain fatty acid enzyme 5 (ELOVL5) in embryonic development and lipid determination. Bovine embryos were produced in vitro using a standard protocol and randomly divided to receive one of three treatments at Day 4: morpholino (Mo) gene expression knockdown assay for ELOVL5 (ELOVL5-Mo), Mo antisense oligonucleotides for the thalassemic β-globulin human mRNA (technical control Mo), and placebo (biological control). The phenotypes of embryonic development, cell number, ELOVL5 protein abundance, lipid droplet deposits, and lipid fingerprint were investigated. No detrimental effects (p > 0.05) were observed on embryo development in terms of cleavage (59.4 ± 3.5%, 63.6 ± 4.1%, and 65.4 ± 2.2%), blastocyst production (31.3 ± 4.2%, 28.1 ± 4.9%, and 36.1 ± 2.1%), and blastocyst cell number (99.6 ± 7.7, 100.2 ± 6.2, 86.8 ± 5.6), respectively, for biological control, technical control Mo, and ELOVL5-Mo. ELOVL5 protein abundance and cytoplasmic lipid droplet deposition were increased (p < 0.05) in ELOVL5-Mo–derived blastocysts compared with the controls. However, seven lipid species, including phosphatidylcholines, phosphatidylethanolamines, and triacylglycerol, were downregulated in the ELOVL5-Mo–derived blastocysts compared with the biological control. Therefore, ELOVL5 is involved in the determination of embryonic lipid content and composition. Transient translational blockage of ELOVL5 reduced the expression of specific lipid species and promoted increased cytoplasmic lipid droplet deposition, but with no apparent deleterious effect on embryonic development and blastocyst cell number.

Long non-coding RNAs (lncRNAs) act as competing endogenous RNAs (ceRNAs) that play a significant role in bovine embryo development; but the influence of sperm-borne lncRNA on the preimplantation development of bovine embryos has not been reported in detail. In this study, we aimed to clarify how sperm-borne lncRNAs can act to regulate early development of bovine embryos. Utilizing high-throughput sequencing technology and quantitative real-time PCR (qPCR), we found that the lncRNA, loc100847420, was highly enriched in bovine sperm and was carried into the oocyte during fertilization. Introduction of wild-type loc100847420 had no effect on cleavage rate of parthenogenetic embryos compared with injection of mutant loc100847420 (70.58 ± 2.85% vs 70.46 ± 1.98%, p > 0.05), but significantly improved the blastocyst rate (33.67 ± 2.40% vs 28.35 ± 3.06%, p < 0.05), total numbers of cells (p < 0.05), numbers of inner cell mass (ICM) cells (p < 0.05) and numbers of trophoblast (TE) cells (p < 0.05). In summary, the sperm-borne lncRNA, loc100847420, can improve the developmental potential of early bovine embryos. [ABSTRACT FROM AUTHOR]

Some evidence shows that body mass index in humans and extreme weights in animal models, including avian species, are associated with low in vitro fertilization, bad oocyte quality, and embryo development failures. Adipokines are hormones mainly produced and released by white adipose tissue. They play a key role in the regulation of energy metabolism. However, they are also involved in many other physiological processes including reproductive functions. Indeed, leptin and adiponectin, the most studied adipokines, but also novel adipokines including visfatin and chemerin, are expressed within the reproductive tract and modulate female fertility. Much of the literature has focused on the physiological and pathological roles of these adipokines in ovary, placenta, and uterine functions. The purpose of this review is to summarize the current knowledge regarding the involvement of leptin, adiponectin, visfatin, and chemerin in the oocyte maturation, fertilization, and embryo development in both mammals and birds.

The ERA (E. coli RAS-like protein)-related GTPase (ERG) is a nuclear-encoded GTPase with two conserved domains: a GTPase domain and a K Homology (KH) domain. ERG plays a vital role in early seed development in Antirrhinum majus. However, the mechanism that regulates seed development remains unclear. Blasting the genome sequence revealed two homologies of ERG, AtERG1, and AtERG2 in Arabidopsis. In this study, we found that AtERG2 is localized in the mitochondria and binds mitochondrial 18S RNA. Promoter and transcript analyses indicated that AtERG2 was mainly expressed in the leaf vein, trichome, and ovule. The T-DNA insertion lines of AtERG2 showed silique shortage, early seed abortion, and sporophytic maternal effects (SME), in which some seeds arrested in the zygotic stage at 1.5 days after pollination (DAP) and aborted at 2.0 DAP in aterg2-1 +/−. We further showed that the ovules of these arrested seeds presented unusual tissue degradation inside the embryo sacs. Reactive oxygen species (ROS) accumulated at 1.0 and 1.5 DAP in the arrested seeds, and the transcription of several ROS-responsive genes, WRKY40, ANAC017, and AOX1a, was up-regulated in the aterg2-1 +/− arrested seeds at 1.5 and 2.0 DAP, but not in wild-type (WT) and aterg2-1 +/− developed seeds. The cell death-related gene BAG6 was also transcriptionally activated in aterg2-1 +/− seeds arrested at 2.0 DAP. Additionally, the protein level of mitochondria protein ATPase Subunit 6 was lower in 2-DAP siliques of aterg2-1 +/− than it was in those of WT. These results suggested that AtERG2 promotes early seed development by affecting the maturation of the mitochondria ribosome small subunit and mitochondrial protein translation in Arabidopsis.

Dynamic epigenetic regulation is critical for proper oogenesis and early embryo development. During oogenesis, fully grown germinal vesicle oocytes develop to mature Metaphase II oocytes which are ready for fertilization. Fertilized oocyte proliferates mitotically until blastocyst formation and the process is called early embryo development. Throughout oogenesis and early embryo development, spatio-temporal gene expression takes place, and this dynamic gene expression is controlled with the aid of epigenetics. Epigenetic means that gene expression can be altered without changing DNA itself. Epigenome is regulated through DNA methylation and histone modifications. While DNA methylation generally ends up with repression of gene expression, histone modifications can result in expression or repression depending on type of modification, type of histone protein and its specific residue. One of the modifications is histone acetylation which generally ends up with gene expression. Histone acetylation occurs through the addition of acetyl group onto amino terminal of the core histone proteins by histone acetyltransferases (HATs). Contrarily, histone deacetylation is associated with repression of gene expression, and it is catalyzed by histone deacetylases (HDACs). This review article focuses on what is known about alterations in the expression of HATs and HDACs and emphasizes importance of HATs and HDACs during oogenesis and early embryo development., (© 2023 Wiley Periodicals LLC.)

Abstract The position of the nucleus in a cell can instruct morphogenesis in some cases, conveying spatial and temporal information and abnormal nuclear positioning can lead to disease. In oocytes from worm, sea urchin, frog and some fish, nucleus position regulates embryo development, it marks the animal pole and in Drosophila it defines the future dorso-ventral axis of the embryo and of the adult body plan. However, in mammals, the oocyte nucleus is centrally located and does not instruct any future embryo axis. Yet an off-center nucleus correlates with poor outcome for mouse and human oocyte development. This is surprising since oocytes further undergo two extremely asymmetric divisions in terms of the size of the daughter cells (enabling polar body extrusion), requiring an off-centering of their chromosomes. In this review we address not only the bio-physical mechanism controlling nucleus positioning via an actin-mediated pressure gradient, but we also speculate on potential biological relevance of nuclear positioning in mammalian oocytes and early embryos. [ABSTRACT FROM AUTHOR]

Paracrine factors such as glial cell line-derived neurotrophic factor (GDNF), which was originally derived from the supernatants of a rat glioma cell line, play pivotal roles in oocyte maturation and early embryo development in mammals, such as mice, rats, pigs, sheep, and even humans. However, whether GDNF facilitates in vitro oocyte maturation or early embryo development in bovines is not yet known. We show for the first time that GDNF and its receptor, GDNF family receptor alpha-1 (GFRA1), are presented in ovarian follicles at different stages as well as during oocyte maturation and early embryo development. Immunostaining results revealed the subcellular localizations of GDNF and GFRA1 in oocytes throughout follicle development, first in germinal vesicles and during blastocyst embryo stages. The ability of exogenously applied GDNF to promote oocyte maturation and early embryo development was evaluated in culture, where we found that an optimal concentration of 50 ng/mL promotes the maturation of cumulus-oocyte complexes and the nuclei of denuded oocytes as well as the development of embryos after IVF. To further investigate the potential mechanism by which GDNF promotes oocyte maturation, bovine oocytes were treated with morpholinos targeting Gfra1 . The suppression of GFRA1 presence blocked endogenous and exogenous GDNF functions, indicating that the effects of GDNF that are essential and beneficial for bovine oocyte maturation and early embryo development occur through this receptor. Furthermore, we show that supplementation with GDNF improves the efficiency of bovine IVF embryo production. [ABSTRACT FROM AUTHOR]

MicroRNA-29b (miR-29b) is a member of the miR-29 family, which targets DNA methyltransferases (DNMTs) and ten eleven translocation enzymes (TETs), thereby regulating DNA methylation. However, the role of miR-29b in porcine early embryo development has not been reported. In this study, we examined the effects of miR-29b in porcine in vitro fertilization (IVF) embryos to investigate the mechanism by which miR-29b regulated DNA methylation. The interference of miR-29b by its special miRNA inhibitor significantly up-regulated Dnmt3a/b and Tet1 but down regulated Tet2/3; meanwhile it increased DNA methylation levels of the global genome and Nanog promoter region but decreased global DNA demethylation levels. The inhibition of miR-29b also resulted in a decrease in the development rate and quality of blastocysts. In addition, the pluripotency genes Nanog and Sox2 were significantly downregulated, and the apoptosis genes Bax and Casp3 were upregulated, but antiapoptosis gene Bcl-2 was downregulated in blastocysts. Our study indicated that miR-29b could regulate DNA methylation mediated by miR29b- Dnmt3a/b - Tet1/2/3 signaling during porcine early embryo development. [ABSTRACT FROM AUTHOR]

The ERA (E. coli RAS-like protein)-related GTPase (ERG) is a nuclear-encoded GTPase with two conserved domains: a GTPase domain and a K Homology (KH) domain. ERG plays a vital role in early seed development in Antirrhinum majus. However, the mechanism that regulates seed development remains unclear. Blasting the genome sequence revealed two homologies of ERG, AtERG1, and AtERG2 in Arabidopsis. In this study, we found that AtERG2 is localized in themitochondria and bindsmitochondrial 18S RNA. Promoter and transcript analyses indicated that AtERG2 was mainly expressed in the leaf vein, trichome, and ovule. The T-DNA insertion lines of AtERG2 showed silique shortage, early seed abortion, and sporophytic maternal effects (SME), in which some seeds arrested in the zygotic stage at 1.5 days after pollination (DAP) and aborted at 2.0 DAP in aterg2-1 +/-. We further showed that the ovules of these arrested seeds presented unusual tissue degradation inside the embryo sacs. Reactive oxygen species (ROS) accumulated at 1.0 and 1.5 DAP in the arrested seeds, and the transcription of several ROS-responsive genes, WRKY40, ANAC017, and AOX1a, was up-regulated in the aterg2-1 +/- arrested seeds at 1.5 and 2.0 DAP, but not in wild-type (WT) and aterg2-1 +/- developed seeds. The cell death-related gene BAG6 was also transcriptionally activated in aterg2-1 +/- seeds arrested at 2.0 DAP. Additionally, the protein level of mitochondria protein ATPase Subunit 6 was lower in 2-DAP siliques of aterg2-1 +/- than it was in those of WT. These results suggested that AtERG2 promotes early seed development by affecting the maturation of the mitochondria ribosome small subunit and mitochondrial protein translation in Arabidopsis. [ABSTRACT FROM AUTHOR]

High salinity and low temperatures can induce Artemia sinica to enter the diapause stage during embryonic development. Diapause embryos stop at the gastrula stage, allowing them to resist apoptosis and regulate cell cycle activity to guarantee normal development after diapause termination. P53 and DNA damage-regulated gene 1 (pdrg1) is involved in cellular physiological activities, such as apoptosis, DNA damage repair, cell cycle regulation, and promotion of programmed cell death. However, the role of pdrg1 in diapause and diapause termination in A. sinica remains unknown. Here, the full-length A. sinica pdrg1 cDNA (As-pdrg1) was obtained and found to contain 1119 nucleotides, including a 228 bp open reading frame (ORF), a 233 bp 5'-untranslated region (UTR), and a 658-bp 3'-UTR, which encodes a 75 amino acid protein. In situ hybridization showed no tissue specific expression of As-pdrg1. Quantitative real-time PCR and western blotting analyses of As-pdrg1 gene and protein expression showed high levels at 15-20 h of embryo development and a subsequent downward trend. Low temperatures upregulated As-pdrg1 expression. RNA interference for the pdrg1 gene in Artemia embryos caused significant developmental hysteresis. Thus, PDRG1 plays an important role in diapause termination and cell cycle regulation in early embryonic development of A. sinica. [ABSTRACT FROM AUTHOR]

A statistical mechanical mean-field approach to the temporal development of biological regulation provides a phenomenological, but basic description of the dynamical behavior of genome expression in terms of autonomous self-organization with a critical transition (Self-Organized Criticality: SOC). This approach reveals the basis of self-regulation/organization of genome expression, where the extreme complexity of living matter precludes any strict mechanistic approach. The self-organization in SOC involves two critical behaviors: scaling-divergent behavior (genome avalanche) and sandpile-type critical behavior. Genome avalanche patterns--competition between order (scaling) and disorder (divergence) reflect the opposite sequence of events characterizing the self-organization process in embryo development and helper T17 terminal cell differentiation, respectively. On the other hand, the temporal development of sandpile-type criticality (the degree of SOC control) in mouse embryo suggests the existence of an SOC control landscape with a critical transition state (i.e., the erasure of zygote-state criticality). This indicates that a phase transition of the mouse genome before and after reprogramming (immediately after the late 2-cell state) occurs through a dynamical change in a control parameter. This result provides a quantitative open-thermodynamic appreciation of the still largely qualitative notion of the epigenetic landscape. Our results suggest: (i) the existence of coherent waves of condensation/de-condensation in chromatin, which are transmitted across regions of different gene-expression levels along the genome; and (ii) essentially the same critical dynamics we observed for cell-differentiation processes exist in overall RNA expression during embryo development, which is particularly relevant because it gives further proof of SOC control of overall expression as a universal feature. [ABSTRACT FROM AUTHOR]

During the embryonic development of Artemia sinica , the diapause phenomenon can be induced by high salinity or low temperature conditions. The diapause embryo at the gastrula stage is maintained under the threat of apoptosis to guarantee the embryo's normal development. In this process, apoptosis inhibitor proteins play vital roles in protecting embryos against apoptosis. Apoptosis inhibitor5 (API5) plays a pivotal role in regulating the cell cycle and preventing programmed cell death after growth factor starvation. In the present study, we cloned the full-length cDNA representing the api5 gene from A. sinica ( As-api5 ), which encodes a 372-amino acid protein. In situ hybridization experiments revealed that As-api5 expression is not tissue or organ specific. Quantitative real-time PCR analyses of the developmental expression of As-api5 showed that it reached its highest level at 10 h, after which its expression decreased. High salinity and low temperature treatments increased the expression of As-api5 . Western blotting was used to assess the abundance of As -API5 and related proteins ( As- CyclinA , As- CyclinE, As- E2F1, As- CDK2, As- APAF1, and As- Caspase9). Downregulation of As-api5 expression using a short interfering RNA resulted in increased mortality and embryo malformation of A. sinica . Taken together, the results indicated that API5 plays a crucial role in embryonic diapause termination and early embryo development of A. sinica. [ABSTRACT FROM AUTHOR]

In this review we provide an overview of the components of the spermatozoa playing an important role in reproductive success beyond fertilization, showing the relationship between the integrity of the diverse elements and the development of a healthy offspring. The present knowledge about fish sperm chromatin organization, epigenetic modifications of DNA and histones and sperm-borne RNAs, essential in controlling embryo development, is summarized, pointing out the possibility of using specific genes or transcripts as biomarkers of sperm quality. Data about commercial species are reported when available and more detailed information about zebrafish sperm is presented. Considering the implications that the integrity of sperm genome and epigenome has on the preservation of a proper genotype and phenotype in the progeny, the methods applied for the study of chromatin damage and for the study of transcriptome are described. Moreover we discuss some injuring agents affecting paternal information, from the presence of contaminants in the aquatic environment, to the reproductive practices applied in fish farming. The consequences of fertilizing with damaged spermatozoa, as well as the zygotic ability to repair damage are also reviewed. Statement of relevance Role of the sperm on achieving high rates of healthy fries. [ABSTRACT FROM AUTHOR]