maternal to zygote transition

In oocyte biology the zona pellucida has long been known to operate three extracellular functions downstream of the secretory pathway, namely, encasing the oocytes in ovarian follicles, mediating sperm-oocyte interaction and preventing premature embryo contact with oviductal epithelium. The present study uncovers a fourth function that is fundamentally distinct from the other three, being critical for embryonic cell survival in mice. Intriguingly, the three proteins of the mouse zona pellucida (ZP1, ZP2, ZP3) were found abundantly present also inside the embryo 4 days after fertilization, as shown by mass spectrometry, immunoblotting and immunofluorescence...

Mammalian oocytes are filled with poorly understood structures called cytoplasmic lattices. First discovered in the 1960s and speculated to correspond to mammalian yolk, ribosomal arrays, or intermediate filaments, their function has remained enigmatic to date. Here, we show that cytoplasmic lattices are sites where oocytes store essential proteins for early embryonic development. Using super-resolution light microscopy and cryoelectron tomography, we show that cytoplasmic lattices are composed of filaments with a high surface area, which contain PADI6 and subcortical maternal complex proteins...

Fertilization in mammals is accompanied by an intense period of chromatin remodeling and major changes in nuclear organization. How the earliest events in embryogenesis, including zygotic genome activation (ZGA) during maternal-to-zygotic transition, influence such remodeling remains unknown. Here, we have investigated the establishment of nuclear architecture, focusing on the remodeling of lamina-associated domains (LADs) during this transition. We report that LADs reorganize gradually in two-cell embryos and that blocking ZGA leads to major changes in nuclear organization, including altered chromatin and genomic features of LADs and redistribution of H3K4me3 toward the nuclear lamina...

Parental care is considered crucial for the enhanced survival of offspring and evolutionary success of many metazoan groups. Most bryozoans incubate their young in brood chambers or intracoelomically. Based on the drastic morphological differences in incubation chambers across members of the order Cheilostomatida (class Gymnolaemata), multiple origins of incubation were predicted in this group. This hypothesis was tested by constructing a molecular phylogeny based on mitogenome data and nuclear rRNA genes 18S and 28S with the most complete sampling of taxa with various incubation devices to date...

Chromatin accessibility plays an important role in shaping gene expression, yet little is known about the genetic and molecular mechanisms that influence the evolution of chromatin configuration. Both local (cis) and distant (trans) genetic influences can in principle influence chromatin accessibility and are based on distinct molecular mechanisms. We therefore sought to characterize the role that each of these plays in altering chromatin accessibility in two closely related sea urchin species. Using hybrids of Heliocidaris erythrogramma and Heliocidaris tuberculata, and adapting a statistical framework previously developed for the analysis of cis and trans influences on the transcriptome, we examined how these mechanisms shape the regulatory landscape at three important developmental stages, and compared our results to similar analyses of the transcriptome...

Single-cell or low-input multi-omics techniques have revolutionized the study of pre-implantation embryo development. However, the single-cell or low-input proteomic research in this field is relatively underdeveloped because of the higher threshold of the starting material for mammalian embryo samples and the lack of hypersensitive proteome technology. In this study, a comprehensive solution of ultrasensitive proteome technology (CS-UPT) was developed for single-cell or low-input mouse oocyte/embryo samples...

The translational repressor Nanos (Nos) regulates a single target, maternal hunchback ( hb) mRNA, to govern abdominal segmentation in the early Drosophila embryo. Nos is recruited specifically to sites in the 3'-UTR of hb mRNA in collaboration with the sequence-specific RNA-binding protein Pumilio (Pum); on its own, Nos has no binding specificity. Nos is expressed at other stages of development, but very few mRNA targets that might mediate its action at these stages have been described. Nor has it been clear whether Nos is targeted to other mRNAs in concert with Pum or via other mechanisms...

Bisphenol A (BPA) and diethyl phthalate (DEP) are estrogenic endocrine disrupting chemicals (EEDCs). The present study reconfirmed that the angle of the ceratohyal cartilage (CH) in embryos were larger from maternal BPA and E2, but smaller from DEP compared to the control. However, it is still unknown whether both the BPA and DEP chemicals disrupted the action of E2 and thereby influence the estrogen signaling pathways. Additionally, it remains unclear whether they also disrupted certain related genes in the migratory pathways of neural crest cells (NCCs) in their offspring...

Meiotically competent oocytes in mammals undergo cyclic development during folliculogenesis. Oocytes within ovarian follicles are transcriptionally active, producing and storing transcripts required for oocyte growth, somatic cell communication and early embryogenesis. Transcription ceases as oocytes transition from growth to maturation and does not resume until zygotic genome activation. Although SUMOylation, a post-translational modification, plays multifaceted roles in transcriptional regulation, its involvement during oocyte development remains poorly understood...

UNLABELLED: OVO is required for karyotypically female germ cell viability but has no known function in the male germline in Drosophila. ovo is autoregulated by two antagonistic isoforms, OVO-A and OVO-B. All ovo - alleles were created as partial revertants of the antimorphic ovo D1 allele. Creation of new targeted alleles in an ovo + background indicated that disrupting the germline-specific exon extension of ovo-B leads to an arrested egg chamber phenotype, rather than germ cell death...

The zygote has a daunting task ahead of itself; it must develop from a single cell (fertilized egg) into a fully functioning adult with a multitude of different cell types. In the beginning, the zygote has help from its mother, in the form of gene products deposited into the egg, but eventually, it must rely on its own resources to proceed through development. The transfer of developmental control from the mother to the embryo is called the maternal-to-zygotic transition (MZT). All animals undergo this transition, which is defined by two main processes-the degradation of maternal RNAs and the synthesis of new RNAs from the zygote's own genome...

After fertilization, sperm and oocyte fused and gave rise to a zygote which is the beginning of a new life. Then the embryonic development is monitored and regulated precisely from the transition of oocyte to the embryo at the early stage of embryogenesis, and this process is termed maternal-to-zygotic transition (MZT). MZT involves two major events that are maternal components degradation and zygotic genome activation. The epigenetic reprogramming plays crucial roles in regulating the process of MZT and supervising the normal development of early development of embryos...

Drosophila Smaug and its orthologs comprise a family of mRNA repressor proteins that exhibit various functions during animal development. Smaug proteins contain a characteristic RNA-binding sterile-α motif (SAM) domain and a conserved but uncharacterized N-terminal domain (NTD). Here, we resolved the crystal structure of the NTD of the human SAM domain-containing protein 4A (SAMD4A, a.k.a. Smaug1) to 1.6 Å resolution, which revealed its composition of a homodimerization D subdomain and a subdomain with similarity to a pseudo-HEAT-repeat analogous topology (PHAT) domain...

The early development of zebrafish ( Danio rerio ) is a complex and dynamic physiological process involving cell division, differentiation, and movement. Currently, the genome and transcriptome techniques have been widely used to study the embryonic development of zebrafish. However, the research of proteomics based on proteins that directly execute functions is relatively vacant. In this work, we apply label-free quantitative proteomics to explore protein profiling during zebrafish's embryogenesis, and a total of 5961 proteins were identified at 10 stages of zebrafish's early development...

The eukaryotic genome is organized to enable the precise regulation of gene expression. This organization is established as the embryo transitions from a fertilized gamete to a totipotent zygote. To understand the factors and processes that drive genomic organization, we focused on the pioneer factor GAGA factor (GAF) that is required for early development in Drosophila. GAF transcriptionally activates the zygotic genome and is localized to subnuclear foci. This non-uniform distribution is driven by binding to highly abundant GA repeats...

Zygotic genome activation (ZGA) is essential for early embryonic development. However, the regulation of ZGA remains elusive in mammals. Here we report that a maternal factor TDP-43, a nuclear transactive response DNA-binding protein, regulates ZGA through RNA Pol II and is essential for mouse early embryogenesis. Maternal TDP-43 translocates from the cytoplasm into the nucleus at the early two-cell stage when minor to major ZGA transition occurs. Genetic deletion of maternal TDP-43 results in mouse early embryos arrested at the two-cell stage...

Zygotic genome activation (ZGA) activates the quiescent genome to enable the maternal-to-zygotic transition1,2 . However, the identity of transcription factors that underlie mammalian ZGA in vivo remains elusive. Here we show that OBOX, a PRD-like homeobox domain transcription factor family (OBOX1-OBOX8)3-5 , are key regulators of mouse ZGA. Mice deficient for maternally transcribed Obox1/2/5/7 and zygotically expressed Obox3/4 had a two-cell to four-cell arrest, accompanied by impaired ZGA...

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...

Embryogenesis requires coordinated gene regulatory activities early on that establish the trajectory of subsequent development, during a period called the maternal-to-zygotic transition (MZT). The MZT comprises transcriptional activation of the embryonic genome and post-transcriptional regulation of egg-inherited maternal mRNA. Investigation into the MZT in animals has focused almost exclusively on bilaterians, which include all classical models such as flies, worms, sea urchin, and vertebrates, thus limiting our capacity to understand the gene regulatory paradigms uniting the MZT across all animals...

BACKGROUND: During mammalian pre-implantation embryonic development (PED), the process of maternal-to-zygote transition (MZT) is well orchestrated by epigenetic modification and gene sequential expression, and it is related to the embryonic genome activation (EGA). During MZT, the embryos are sensitive to the environment and easy to arrest at this stage in vitro. However, the timing and regulation mechanism of EGA in buffaloes remain obscure. RESULTS: Buffalo pre-implantation embryos were subjected to trace cell based RNA-seq and whole-genome bisulfite sequencing (WGBS) to draw landscapes of transcription and DNA-methylation...