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Science Advances Feb 2022Translational regulation plays an important role in gene expression and function. Although the transcriptional dynamics of mouse preimplantation embryos have been well...
Translational regulation plays an important role in gene expression and function. Although the transcriptional dynamics of mouse preimplantation embryos have been well characterized, the global mRNA translation landscape and the master regulators of zygotic genome activation (ZGA) remain unknown. Here, by developing and applying a low-input ribosome profiling (LiRibo-seq) technique, we profiled the mRNA translation landscape in mouse preimplantation embryos and revealed the translational dynamics during mouse preimplantation development. We identified a marked translational transition from MII oocytes to zygotes and demonstrated that active translation of maternal mRNAs is essential for maternal-to-zygotic transition (MZT). We further showed that two maternal factors, Smarcd2 and Cyclin T2, whose translation is activated in zygotes, are required for chromatin reprogramming and ZGA, respectively. Our study thus not only filled in a knowledge gap on translational regulation during mammalian preimplantation development but also revealed insights into the critical function of maternal mRNA translation in MZT.
Topics: Animals; Embryonic Development; Gene Expression Regulation, Developmental; Mammals; Mice; Protein Biosynthesis; RNA, Messenger, Stored; Zygote
PubMed: 35108058
DOI: 10.1126/sciadv.abj3967 -
Current Biology : CB Jun 2024Rapid cleavage divisions and the transition from maternal to zygotic control of gene expression are the hallmarks of early embryonic development in most species. Early... (Review)
Review
Rapid cleavage divisions and the transition from maternal to zygotic control of gene expression are the hallmarks of early embryonic development in most species. Early development in insects, fish and amphibians is characterized by several short cell cycles with no gap phases, necessary for the rapid production of cells prior to patterning and morphogenesis. Maternal mRNAs and proteins loaded into the egg during oogenesis are essential to drive these rapid early divisions. Once the function of these maternal inputs is complete, the maternal-to-zygotic transition (MZT) marks the handover of developmental control to the gene products synthesized from the zygotic genome. The MZT requires three major events: the removal of a subset of maternal mRNAs, the initiation of zygotic transcription, and the remodeling of the cell cycle. In each species, the MZT occurs at a highly reproducible time during development due to a series of feedback mechanisms that tightly couple these three processes. Dissecting these feedback mechanisms and their spatiotemporal control will be essential to understanding the control of the MZT. In this primer, we outline the mechanisms that govern the major events of the MZT across species and highlight the role of feedback mechanisms that ensure the MZT is precisely timed and orchestrated.
Topics: Zygote; Animals; Gene Expression Regulation, Developmental; Embryonic Development; Female; RNA, Messenger, Stored
PubMed: 38834020
DOI: 10.1016/j.cub.2024.04.044 -
Cellular and Molecular Life Sciences :... Jan 2020Zygosis is the generation of new biological individuals by the sexual fusion of gamete cells. Our current understanding of eukaryotic phylogeny indicates that sex is... (Review)
Review
Zygosis is the generation of new biological individuals by the sexual fusion of gamete cells. Our current understanding of eukaryotic phylogeny indicates that sex is ancestral to all extant eukaryotes. Although sexual development is extremely diverse, common molecular elements have been retained. HAP2-GCS1, a protein that promotes the fusion of gamete cell membranes that is related in structure to certain viral fusogens, is conserved in many eukaryotic lineages, even though gametes vary considerably in form and behaviour between species. Similarly, although zygotes have dramatically different forms and fates in different organisms, diverse eukaryotes share a common developmental programme in which homeodomain-containing transcription factors play a central role. These common mechanistic elements suggest possible common evolutionary histories that, if correct, would have profound implications for our understanding of eukaryogenesis.
Topics: Animals; Biological Evolution; Cell Membrane; Eukaryota; Germ Cells; Phylogeny; Transcription Factors; Zygote
PubMed: 31203379
DOI: 10.1007/s00018-019-03187-1 -
Methods in Molecular Biology (Clifton,... 2019Direct modification of the genome of the zygotes (i.e., one-cell embryos) by the CRISPR/Cas9-editing reagents, followed by embryo transfer to pseudopregnant females for...
Direct modification of the genome of the zygotes (i.e., one-cell embryos) by the CRISPR/Cas9-editing reagents, followed by embryo transfer to pseudopregnant females for live birth, has been the most effective method to generate laboratory rodent models for research. The method relies on proper delivery of the editing reagents into zygotes, which is commonly achieved by a standard or slightly modified pronuclear microinjection technique. In this chapter, we describe in detail an alternative delivery method, named piezo-driven cytoplasmic microinjection, which offers a superior embryo survival and birth rate. Because this method uses a much wider injection needle than that in pronuclear injection, it allows a larger volume of the editing materials to be transported into the zygotes, leading to an increase in the targeting efficiency. This also eliminates the clogging issues seen regularly in pronuclear injection. Moreover, Cytochalasin B that is used to soften zygotes during piezo-driven microinjection has been suggested a role in improving the knockin efficiency, which provides an additional benefit to use this injection method.
Topics: Animals; CRISPR-Cas Systems; Cytochalasin B; Female; Gene Editing; Male; Mice; Microinjections; Nuclear Transfer Techniques; Rats; Zygote
PubMed: 30353513
DOI: 10.1007/978-1-4939-8831-0_9 -
Genetics May 2014Centrosomes are composed of two centrioles surrounded by pericentriolar material (PCM). However, the sperm and the oocyte modify or lose their centrosomes. Consequently,...
Centrosomes are composed of two centrioles surrounded by pericentriolar material (PCM). However, the sperm and the oocyte modify or lose their centrosomes. Consequently, how the zygote establishes its first centrosome, and in particular, the origin of the second zygotic centriole, is uncertain. Drosophila melanogaster spermatids contain a single centriole called the Giant Centriole (GC) and a Proximal centriole-like (PCL) structure whose function is unknown. We found that, like the centriole, the PCL loses its protein markers at the end of spermiogenesis. After fertilization, the first two centrioles are observed via the recruitment of the zygotic PCM proteins and are seen in asterless mutant embryos that cannot form centrioles. The zygote's centriolar proteins label only the daughter centrioles of the first two centrioles. These observations demonstrate that the PCL is the origin for the second centriole in the Drosophila zygote and that a paternal centriole precursor, without centriolar proteins, is transmitted to the egg during fertilization.
Topics: Animals; Centrioles; Drosophila Proteins; Drosophila melanogaster; Female; Fertilization; Homozygote; Male; Spermatogenesis; Time Factors; Zygote
PubMed: 24532732
DOI: 10.1534/genetics.113.160523 -
Journal of Assisted Reproduction and... Jul 2014To identify an association between amino acids (AAs) metabolism and reproductive outcome.
PURPOSE
To identify an association between amino acids (AAs) metabolism and reproductive outcome.
METHODS
Prospective collection, observational study, in patients undergoing fresh, double embryo transfer (ET), in a tertiary hospital referral IVF unit. Spent day 1 and day 3 media were collected. Concentrations of taurine, aspartic acid, proline, and serine in the medium were determined using a liquid-chromatography mass-spectrometer (LCMS/MS). Data was analyzed according to excretion versus uptake, and a cut-off value was calculated based on a receiver operating curve (ROC). Pregnancy rates were also calculated after stratification into subgroups in accordance with AA metabolism.
RESULTS
Seven out of 19 patients conceived (36.8 %). The ORs for pregnancy when the zygotes secreted aspartic acid, serine and proline above the cut-off value were 2.9, 5.67 and 5.21 (p < 0.05). When both transferred embryos were above the cut-off value of serine the PR's were 62.5 %, 12.5 % when both were below, and 33.3 % when one was above and the other below (p = 0.04). Similar results were obtained for proline; PR's were 66.7, 18.7 and 28.6 % respectively, but with a borderline statistical significance (p = 0.08). The same trend was observed in the case of aspartic acid but not near statistical significance. No differences in PRs were found in association with taurine turnover during fertilization or any of the studied AAs during the cleavage stage. There was no correlation between zygote or embryo AAs metabolism and embryo morphology.
CONCLUSIONS
Serine and possibly proline decreased uptake from the fertilization medium is associated with pregnancy and might be useful for embryo selection.
Topics: Adult; Cleavage Stage, Ovum; Culture Media; Embryo Implantation; Embryo Transfer; Female; Fertilization in Vitro; Humans; Pregnancy; Proline; Serine; Zygote
PubMed: 24789167
DOI: 10.1007/s10815-014-0231-2 -
Molecular Reproduction and Development Sep 2017Genome editing in pigs has tremendous practical applications for biomedicine. The advent of genome editing technology, with its use of site-specific nucleases-including... (Review)
Review
Genome editing in pigs has tremendous practical applications for biomedicine. The advent of genome editing technology, with its use of site-specific nucleases-including ZFNs, TALENs, and the CRISPR/Cas9 system-has popularized targeted zygote genome editing via one-step microinjection in several mammalian species. Here, we review methods to optimize the developmental competence of genome-edited porcine embryos and strategies to improve the zygote genome-editing efficiency in pigs.
Topics: Animals; Animals, Genetically Modified; CRISPR-Cas Systems; Gene Editing; Swine; Zygote
PubMed: 28471514
DOI: 10.1002/mrd.22829 -
Molecular Plant Sep 2021Fertilization constitutes a critical step in the plant life cycle during which the gamete genomes undergo chromatin dynamics in preparation for embryogenesis. In...
Fertilization constitutes a critical step in the plant life cycle during which the gamete genomes undergo chromatin dynamics in preparation for embryogenesis. In mammals, parental chromatin is extensively reprogrammed through the global erasure of DNA methylation. However, in flowering plants it remains unclear whether and how DNA methylation is remodeled in gametes and after fertilization in the zygote. In this study, we characterize DNA methylation patterns and investigate the function of DNA glycosylases in rice eggs, sperm, and unicellular zygotes and during embryogenesis. We found that DNA methylation is locally reconfigured after fertilization and is intensified during embryogenesis. Genetic, epigenomic, and transcriptomic analysis revealed that three rice DNA glycosylases, DNG702, DNG701, and DNG704, demethylate DNA at distinct genomic regions in the gametes and the zygote, and are required for zygotic gene expression and development. Collectively, these results indicate that active DNA demethylation takes place in the gametes and the zygote to locally remodel DNA methylation, which is critical for egg and zygote gene expression and reproduction in rice.
Topics: Arabidopsis; Chromatin; DNA Methylation; DNA, Plant; Germ Cells, Plant; Oryza; Plant Development; Zygote
PubMed: 34116223
DOI: 10.1016/j.molp.2021.06.006 -
Current Opinion in Genetics &... Oct 2020After fertilization, mouse embryos go through preimplantation development to give rise to blastocyst. Two key molecular events, zygotic genome activation (ZGA) and the... (Review)
Review
After fertilization, mouse embryos go through preimplantation development to give rise to blastocyst. Two key molecular events, zygotic genome activation (ZGA) and the first cell lineage specification, are essential for the process. Recent advances in low-input epigenomics profiling techniques allow the analysis of these events at a molecular level, which revealed a critical role of epigenetic and chromatin reprogramming in ZGA and the first cell lineage specification. Additionally, the establishment of an in vitro embryonic stem cell (ESC) to two-cell embryo-like conversion system have also contributed to the molecular understanding of preimplantation development. In this review, we summarize recent advances in epigenetic regulation of mouse preimplantation development, point out the remaining questions, and propose strategies to tackle these questions.
Topics: Animals; Blastocyst; Embryonic Development; Embryonic Stem Cells; Epigenesis, Genetic; Female; Genome; Humans; Pregnancy; Zygote
PubMed: 32563750
DOI: 10.1016/j.gde.2020.05.015 -
PLoS Biology Jan 2021To ensure genome stability, sexually reproducing organisms require that mating brings together exactly 2 haploid gametes and that meiosis occurs only in diploid zygotes....
To ensure genome stability, sexually reproducing organisms require that mating brings together exactly 2 haploid gametes and that meiosis occurs only in diploid zygotes. In the fission yeast Schizosaccharomyces pombe, fertilization triggers the Mei3-Pat1-Mei2 signaling cascade, which represses subsequent mating and initiates meiosis. Here, we establish a degron system to specifically degrade proteins postfusion and demonstrate that mating blocks not only safeguard zygote ploidy but also prevent lysis caused by aberrant fusion attempts. Using long-term imaging and flow-cytometry approaches, we identify previously unrecognized and independent roles for Mei3 and Mei2 in zygotes. We show that Mei3 promotes premeiotic S-phase independently of Mei2 and that cell cycle progression is both necessary and sufficient to reduce zygotic mating behaviors. Mei2 not only imposes the meiotic program and promotes the meiotic cycle, but also blocks mating behaviors independently of Mei3 and cell cycle progression. Thus, we find that fungi preserve zygote ploidy and survival by at least 2 mechanisms where the zygotic fate imposed by Mei2 and the cell cycle reentry triggered by Mei3 synergize to prevent zygotic mating.
Topics: Cell Cycle; Cell Cycle Proteins; Fungal Proteins; Genes, Fungal; Mating Factor; Meiosis; Organisms, Genetically Modified; Ploidies; RNA-Binding Proteins; Recombination, Genetic; Schizosaccharomyces; Schizosaccharomyces pombe Proteins; Zygote
PubMed: 33406066
DOI: 10.1371/journal.pbio.3001067