Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Dm miR-309 cluster KO Expression Profiling

ABSTRACT: To investigate whether early zygotic miR-309 cluster miRNA expression might contribute to the down-regulation of maternal transcripts during the maternal to zygotic transition in Drosophila, we performed microarray analyses of control and miR-309 cluster mutant embryos at 0-1h and 2-3h of embryonic development. One-hour egg collections of w1118 and miR-309-6delta1 mutant flies at 25?C were either aged (2-3h sample) at 25?C or directly processed (0-1h sample). Six independent collections per genotype and time-point were performed. Using this approach, we found that maternal transcripts were stabilized in the miR-309 cluster mutant, indicating that the miR-309 cluster miRNAs are required for the down-regulation of these transcripts during the maternal to zygotic transition in Drosophila.

ORGANISM(S): Drosophila melanogaster

SUBMITTER: Charles Girardot

PROVIDER: E-TABM-441 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:In all animals, the initial events of embryogenesis are controlled by maternal gene products that are deposited into the developing oocyte. At some point after fertilization, control of embryogenesis is transferred to the zygotic genome in a process called the maternal to zygotic transition (MZT). During this time maternal RNAs are degraded and zygotic RNAs are transcribed1. A long standing question has been, what factors regulate these events? The recent findings that microRNAs and Smaugs mediate maternal transcript degradation brought new life to this old problem2,3, however, the transcription factors that activate zygotic gene expression remained elusive. A clue came from the finding that many early zygotic genes in Drosophila share a cis-regulatory heptamer motif, CAGGTAG and related sequences, collectively referred to as TAG-team sites4,5. We asked whether there was a dedicated transcription factor that interacts with these sites to activate early genes. Here we report the discovery of a zinc-finger protein, Zelda (Zld) that binds specifically to TAG-team sites, and is capable of activating transcription in transient transfection assays. Mutant embryos lacking zld are defective in the cellularization process, and fail to activate the transcription of many early zygotic genes involved in cellularization, sex determination, and dorsoventral patterning. Global expression profiling confirmed that Zld plays a key role in the activation of the early zygotic genome, and suggests that Zld may also play a role in maternal RNA degradation during the MZT since many RNAs are up-regulated in the absence of Zld. Experiment Overall Design: Total RNA samples were extracted from three replicate collections of 1-2 hr yw and M- zld embryos by TRIzol (invitrogen). A portion of the collected embryos was fixed and stained with DAPI; 90% were in nuclear cycles 8 to13. cDNA was prepared using the GeneChipÂ® HT One-Cycle cDNA Synthesis Kit (Manufactured by Invitrogen for Affymetrix) and labeled with the BioArrayâ¢ HighYieldâ¢ RNA Transcript Labeling Kit (Enzo). Labeled probes were hybridized to Drosophila Genome 2 Affymetrix arrays and processed by a GeneChip Fluidics Station 400. Data were acquired and normalized by the GeneChipÂ® Scanner 3000 and processed by the Affymetrix GeneChip Operating Software (GCOS). t-test analysis was performed on the data from three biological replicates.

Project description:Background: During the maternal-to-zygotic transition (MZT) vast changes in the embryonic transcriptome are produced by a combination of two processes: elimination of maternally provided mRNAs and synthesis of new transcripts from the zygotic genome. Previous genome-wide analyses of the MZT have been restricted to whole embryos. Here we report the first such analysis for primordial germ cells (PGCs), the progenitors of the germ-line stem cells. Results: We purified PGCs from Drosophila embryos, defined their proteome and transcriptome, and assessed the content, scale and dynamics of their MZT. Transcripts encoding proteins that implement particular types of biological functions group into nine distinct expression profiles, reflecting coordinate control at the transcriptional and posttranscriptional levels. mRNAs encoding germ-plasm components and cell-cell signaling molecules are rapidly degraded while new transcription produces mRNAs encoding the core transcriptional and protein synthetic machineries. The RNA-binding protein, Smaug, is essential for the PGC MZT, clearing transcripts encoding proteins that regulate stem cell behavior, transcriptional and posttranscriptional processes. Computational analyses suggest that Smaug and AU-rich element binding-proteins function independently to control transcript elimination. Conclusion: The scale of the MZT is similar in the soma and PGCs. However, the timing and content of their MZTs differ, reflecting the distinct developmental imperatives of these cell types. The PGC MZT is delayed relative to that in the soma, likely because relief of PGC-specific transcriptional silencing is required for zygotic genome activation as well as for efficient maternal transcript clearance. There are 26 samples in total, including 1-to-3 hour, 3-to-5 hour, 5-to-7 hour PGCs in wild type and smaug mutant flies and 1-to-3 hour somatic cells in wild type flies. Except for the 1-to-3 hour and 3-to-5 hour smaug mutant PGCs which have three replicates, all the other samples have four replicates.

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Dm miR-309 cluster KO Expression Profiling

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