Study of Mid-Blastula Transition of zebrafish embryos
Ontology highlight
ABSTRACT:
ORGANISM(S): Danio rerio
PROVIDER: GSE32914 | GEO | 2011/10/13
SECONDARY ACCESSION(S): PRJNA146543
REPOSITORIES: GEO
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Project description:Sox31 is a member of the zebrafish SoxB1 subfamily, and its expression can be detected both pre- and post-MBT. To distinguish the function of its maternal and zygotic transcripts, a splice blocking morpholino (Sb MO) was designed to interfere with the processing of new, zygotically synthesised mRNAs without interfering with mRNAs of maternal origin. Developmental arrest was observed in Sb MO which could not bypass MBT. Mid-Blastula Transition (MBT) functions as a time window for zygotic genome activation and maternal mRNA degradation. To uncover whether the “zygotic up” and “maternal down” event during MBT is retarded in Sb morphants, we performed microarray experiment at the end of MBT (about 4.3 hours post fertilication/4.3 hpf) to compare mRNAs from Sb morphants and control embryos. In one experiment, three flocks of zebrafish eggs were injected with the Sox19b morpholino immediately after fertilization, while another three control populations were injected with placebo. At 4.3 hpf, these six flocks of embryos were sent for gene expression profiling with six Affymetrix Zebrafish Genome Arrays. In another experiment, we compared two wildtype embryo samples at 4h (post-MBT) against two wildtype samples at 2.5 h (pre-MBT).
2011-10-12 | E-GEOD-32914 | biostudies-arrayexpress
Project description:The Xenopus mid-blastula transition (MBT) marks the onset of large-scale zygotic transcription, as well as an increase in cell cycle length and a loss of synchronous cell divisions. Little is known about what triggers the activation of transcription or how newly expressed genes interact with each other. Here we use high-resolution expression profiling to identify three waves of gene activity: a post-fertilization wave involving polyadenylation of maternal transcripts; a broad wave of zygotic transcription detectable as early as the 7th cleavage and extending beyond the MBT at the 12th cleavage; and a shorter post-MBT wave of transcription that becomes apparent as development proceeds. Our studies have also allowed us to define a set of maternal genes whose mRNAs are deadenylated shortly after fertilization, and are likely to be degraded thereafter. Experimental analysis indicates that the polyadenylation of maternal transcripts is necessary for the establishment of proper levels of zygotic transcription at the MBT, and that genes activated in the second wave of expression, including Brachyury and Mixer, contribute to the regulation of genes expressed in the third. Together, our high-resolution time series and experimental studies have yielded a deeper understanding of the temporal organization of gene regulatory networks in the early Time series polyA+ and RiboZero RNA sequencing of Xenopus Embryos covering 0-9.5 hours post fertilization
2014-03-27 | E-GEOD-56242 | biostudies-arrayexpress
Project description:The Xenopus mid-blastula transition (MBT) marks the onset of large-scale zygotic transcription, as well as an increase in cell cycle length and a loss of synchronous cell divisions. Little is known about what triggers the activation of transcription or how newly expressed genes interact with each other. Here we use high-resolution expression profiling to identify three waves of gene activity: a post-fertilization wave involving polyadenylation of maternal transcripts; a broad wave of zygotic transcription detectable as early as the 7th cleavage and extending beyond the MBT at the 12th cleavage; and a shorter post-MBT wave of transcription that becomes apparent as development proceeds. Our studies have also allowed us to define a set of maternal genes whose mRNAs are deadenylated shortly after fertilization, and are likely to be degraded thereafter. Experimental analysis indicates that the polyadenylation of maternal transcripts is necessary for the establishment of proper levels of zygotic transcription at the MBT, and that genes activated in the second wave of expression, including Brachyury and Mixer, contribute to the regulation of genes expressed in the third. Together, our high-resolution time series and experimental studies have yielded a deeper understanding of the temporal organization of gene regulatory networks in the early
2014-03-27 | GSE56242 | GEO
Project description:Upon fertilization, maternal factors direct development in a transcriptionally silent embryo. At the maternal-to-zygotic transition (MZT), a universal step in animal development, unknown maternal factors trigger zygotic genome activation (ZGA). In zebrafish, ZGA is required for gastrulation and clearance of maternal mRNAs, which is achieved in part by the conserved microRNA miR-430. However, the precise factors that activate the zygotic program remain largely unknown. Here we show that Nanog, Pou5f1 and SoxB1 are required for genome activation in zebrafish. We identified several hundred genes directly activated by maternal factors, thus constituting the first wave of zygotic transcription in zebrafish. Ribosome profiling in the pre-MZT embryo revealed that nanog, sox19b and pou5f1 are the most highly translated transcription factor mRNAs. Combined loss of function for Nanog, SoxB1 and Pou5f1 resulted in developmental arrest prior to gastrulation, and a failure to activate >75% of zygotic genes. Furthermore, we found that Nanog binds the miR-430 locus and together with Pou5f1 and SoxB1 initiate miR-430 expression and activity. Our results demonstrate that maternal Nanog, Pou5f1 and SoxB1 are required to initiate the zygotic developmental program and in turn trigger the clearance of the maternal program by activating miR-430 expression. Wild type and loss-of-function total mRNA sequencing of embryonic transcriptomes pre- and post-MZT; ribosome profiling pre-MZT
2013-09-22 | E-GEOD-47558 | biostudies-arrayexpress
Project description:Upon fertilization, maternal factors direct development in a transcriptionally silent embryo. At the maternal-to-zygotic transition (MZT), a universal step in animal development, unknown maternal factors trigger zygotic genome activation (ZGA). In zebrafish, ZGA is required for gastrulation and clearance of maternal mRNAs, which is achieved in part by the conserved microRNA miR-430. However, the precise factors that activate the zygotic program remain largely unknown. Here we show that Nanog, Pou5f1 and SoxB1 are required for genome activation in zebrafish. We identified several hundred genes directly activated by maternal factors, thus constituting the first wave of zygotic transcription in zebrafish. Ribosome profiling in the pre-MZT embryo revealed that nanog, sox19b and pou5f1 are the most highly translated transcription factor mRNAs. Combined loss of function for Nanog, SoxB1 and Pou5f1 resulted in developmental arrest prior to gastrulation, and a failure to activate >75% of zygotic genes. Furthermore, we found that Nanog binds the miR-430 locus and together with Pou5f1 and SoxB1 initiate miR-430 expression and activity. Our results demonstrate that maternal Nanog, Pou5f1 and SoxB1 are required to initiate the zygotic developmental program and in turn trigger the clearance of the maternal program by activating miR-430 expression.
2013-09-22 | GSE47558 | GEO
Project description:To validate that EU-RNA imaging provides a direct readout of wide-spread zygotic transcription, we sought to identify the nascent transcriptome using RNA-seq. We micoinjected 5-ethynyl uridine (EU) into 1-cell Xenopus embryos, isolated total RNA from embryos at mid-blastula transition (MBT), biotinylated EU-RNA and purified it to generate cDNA libraries for sequencing. Total RNA from normal embyros were used as control. We found over 25,000 nascent genes in this EU-RNA dataset at mid-ZGA. The nascent transcriptome dataset captures nearly 90% of the transcripts present in the whole-embryo dataset and with similar or better read-depth, indicating that our EU-RNA imaging is truly representative of wide-spread zygotic transcription. Furthermore, of the known zygotic genes that are most highly induced at MBT, we detected all of them and at much higher levels than in the whole-embryo dataset. These results show that our labeling captures the nascent zygotic transcriptome. We found ~ 4-fold higher sensitivity for nascent transcripts in the EU-RNA dataset compared to the whole embryo dataset, and as excepted we did not detect thousands of maternal-only transcripts in the nascent dataset. Together, these results suggest that EU-labeling provides a visual readout of bona fide nascent zygotic transcripts.
2019-05-31 | GSE131962 | GEO
Project description:In most embryos, the mid-blastula transition is a complex process featuring maternal RNA degradation, cell cycle pause, zygotic transcriptional activation and morphological changes. The nucleocytoplasmic (N/C) ratio has been proposed to control the multiple events at MBT. To understand the global transcriptional response to the changes of the N/C ratio, we profiled wild type and haploid embryos using cDNA microarrays at three developmental stages. Keywords: time course and different genotype
2009-06-02 | GSE14287 | GEO
Project description:Externally deposited eggs begin development with an immense cytoplasm and a single overwhelmed nucleus. Rapid mitotic cycles restore normality as the ratio of nuclei to cytoplasm (N/C) increases. A threshold N/C has been widely proposed to activate zygotic genome transcription and onset of morphogenesis at the mid-blastula transition (MBT). To test whether a threshold N/C is required for these events, we blocked N/C-increase by downregulating cyclin/Cdk1 to arrest early cell cycles in Drosophila. Embryos that were arrested two cell cycles prior to the normal MBT activated widespread transcription of the zygotic genome including genes previously described as N/C-dependent. Zygotic transcription of these genes largely retained features of their regulation in space and time. Furthermore, zygotically regulated post-MBT events such as cellularization and gastrulation movements occurred in these cell-cycle-arrested embryos. These results are not compatible with models suggesting that these MBT events are directly coupled to N/C. Cyclin/Cdk1 activity normally declines in tight association with increasing N/C and is regulated by N/C. By experimentally promoting the decrease in cyclin/Cdk1, we uncoupled MBT from N/C increase, arguing that N/C guided down-regulation of cyclin/Cdk1 is sufficient for genome activation and MBT.
2020-08-15 | GSE154502 | GEO
Project description:We followed the polysomal association of maternal and early zygotic transcriptome over the first few hours of embryonic development, prior to and after MBT. We isolated polysome-associated (bound) and non-polysome-associated (unbound) mRNAs using sucrose gradient centrifugation followed by size fractionation. Using next generation sequencing (RNA-seq), we profiled the transcriptome in polysome-bound and unbound fractions. Our analysis revealed distinct dynamics of polysome association of cytoplasmically polyadenylated maternal mRNAs.
2017-10-14 | GSE88776 | GEO
Project description:Zygotic genome activation (ZGA), which is according to the midblastula transition in zebrafish, is an important event during the maternal-zygotic transition in animals. Our preliminary study and other groupâs works indicate that epigenetic regulations play an essential role in ZGA. Morpholino was employed to knockdown PRMT6. We used microarrays to analyze the global gene expression in prmt6 morphants. prmt6 MO (0.3mM) was injected into the one-two cell zebrafish, prmt6 cMO (0.3mM) injection as a control. At 6 hpf, embryos were classified into three subtypes (normal, mild and severe) and prepared for global gene expression analysis with Affymetrix Zebrafish Genome Arrays. The severe subtype and the control were repeated three times.
2015-11-25 | E-GEOD-63735 | biostudies-arrayexpress