Extensive divergence of transcription factor binding in Drosophila embryos with highly conserved gene expression (part 1)
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ABSTRACT: We sequenced mRNA from blastoderm embryos of Drosophila melanogaster, Drosophila yakuba, Drosophila pseudoobscura and Drosophila virilis. Two samples contain pooled mRNA from several species, and the remaining 24 samples contain mRNA from a single species. Methods: Retinal mRNA profiles of Blastoderm embryos Comparison of the evolution of gene expression and regulatory TF binding in early Drosophila embryos.
Project description:A conspicuous feature of early animal development is the lack of transcription from the embryonic genome, and it typically takes several hours to several days (depending on the species) until widespread transcription of the embryonic genome begins. Although this transition is ubiquitous, relatively little is known about how the shift from a transcriptionally quiescent to transcriptionally active genome is controlled. We describe here the genome-wide distributions and temporal dynamics of nucleosomes and post-translational histone modifications through the maternal-to-zygotic transition in embryos of the pomace fly Drosophila melanogaster. At mitotic cycle 8, when few zygotic genes are being transcribed, embryonic chromatin is in a relatively simple state: there are few nucleosome-free regions, undetectable levels of the histone methylation marks characteristic of mature chromatin, and low levels of histone acetylation at a relatively small number of loci. Histone acetylation increases by cycle 12, but it is not until cycle 14 that nucleosome-free regions and domains of histone methylation become widespread. Early histone acetylation is strongly associated with regions that we have previously shown are bound in early embryos by the maternally deposited transcription factor Zelda. Most of these Zelda-bound regions are destined to be enhancers or promoters active during mitotic cycle 14, and our data demonstrate that they are biochemically distinct long before they become active, raising the possibility that Zelda triggers a cascade of events, including the accumulation of specific histone modifications, that plays a role in the subsequent activation of these sequences. Many of these Zelda-associated active regions occur in larger domains that we find strongly enriched for histone marks characteristic of Polycomb-mediated repression, suggesting a dynamic balance between Zelda activation and Polycomb repression. Collectively, these data paint a complex picture of a genome in transition from a quiescent to an active state, and highlight the role of Zelda in mediating this transition. We performed genome-wide mapping of histone H3 and 9 types of histone modifications, including H4K5ac, H4K8ac, H3K4me1, H3K4me3, H3K27me3, H3K36me3, H3K9ac, H3K18ac, and H3K27ac by ChIP-seq, in hand-sorted wild-type Drosophila melanogaster embryos at 4 different development time points corresponding to mitotic cycle 7-9, 11-13, 14a-b, and 14c-d, respectively. We also carried out ChIP-seq experiments in zelda mutant embryos after showing that the deposition of histone marks in early embryos strongly correlated with the binding of Zelda in wild-type embryos.
Project description:This study describes the epigenetic profiling of the H3K9me2 in wt Drosophila larvae, as well as in Drosophila larvae for which the euchromatic catalytic enzyme depositing H3K9me2 (EHMT) is knocked out. ChIP-Seq profiling of H3K9me2 in wt and EHMT KO third instar Drosophila larvae
Project description:Purpose: Combination of systemic RNAi with RNAseq to identify target genes of important pathways in early development Drosophila early patterning occurs in the syncytial blastoderm where transcription factors diffuse between cells. However, in typical insect embryos, patterning occurs in a cellularized environment where signaling pathways are likely to play a more fundamental role. We use the short germ beetle Tribolium castaneum to investigate two putative Wnt and Hh signaling centers located in the anlagen of head and growth zone. These structures are known to develop in a different way in short germ insects. We find that Hh acts upstream of Wnt in the head, which is different from the Drosophila situation. In the growth zone Wnt signaling acts upstream. For the first time outside Drosophila, we comprehensively determine the Wnt and Hh target gene sets and distinguish the anterior from the posterior gene sets by genetically depleting head or growth zone. Surprisingly, there are significantly more targets in the growth zone than in the head for both pathways and we find that their growth zone gene sets are essentially non-overlapping. Furthermore, several pair rule genes, Tc-caudal, Tc-twist and hindgut patterning genes are regulated by Wnt signaling. In addition, Wnt controls growth zone metabolism and cell division. Posterior Hh signaling activates several genes potentially involved in a proteinase cascade of unknown function. Unexpectedly, we find the Wnt target Tc-senseless to be required for hindgut development. 10-11 h old whole embyro mRNA profiles of the following treatments: reference: wild type 100bp single read triplicates reference: wild type 50bp single read triplicates treatment: Tc-arrow RNAi knockdown 50 bp single read triplicates treatment: Tc-frizzled1/2 RNAi double knockdown 50 bp single read triplicates treatment: Tc-hedgehog RNAi knockdown 100bp single reads quadruplicates treatment: Tc-orthodenticle RNAi knockdown 100bp single reads triplicates treatment: Tc-torso RNAi knockdown 100bp single reads triplicates treatment: Tc-wntless RNAi knockdown 50bp single reads triplicates Total: 2 references, 6 treatments, 25 sequencing runs
Project description:We sequenced mRNA from blastoderm embryos of Drosophila melanogaster, Drosophila yakuba, Drosophila pseudoobscura and Drosophila virilis. Two samples contain pooled mRNA from several species, and the remaining 24 samples contain mRNA from a single species. Methods: Retinal mRNA profiles of Blastoderm embryos
Project description:In this study we provide evidence that Hsp90 binds chromatin at specific sites close to several TSS in Drosophila S2 cell line. In addition of finding a preference for stalled promoter regions of annotated genes, we uncover many intergenic Hsp90 binding sites coinciding with non-annotated transcription start sites. Interestingly, this set includes promoters for primary transcripts of microRNA genes, thereby expanding the scope of Hsp90 to transcriptional control of many genes. We finally conclude that Hsp90 contacts NelfE and thus regulates pol II pausing. Our Dataset comprises of 1 ChIP-seq sample using chromatin from S2 cells which was immunoprecipitated, using antibodies against Drosophila Hsp90. The two biological replicates are submitted along with the input replicates.
Project description:Our primary objective was to characterize the amount of variation in transcript abundance among individual flies with identical genotypes. We also wanted to determine which analysis methods would be optimal for RNA-Seq data. To meet these objectives, we performed transcriptional profiling of whole adult individuals from 16 Drosophila Genetic Reference Panel (DGRP) lines. We quantified differential expression among genotypes, environments, and sexes. We randomly chose 16 DGRP lines for this experiment: DGRP-93, DGRP-229, DGRP-320, DGRP-352, DGRP-370, DGRP-563, DGRP-630, DGRP-703, DGRP-761, DGRP-787, DGRP-790, DGRP-804, DGRP-812, DGRP-822, DGRP-850, and DGRP-900. We collected 8 virgin male and 8 virgin female flies from the 16 DGRP genotypes in three replicated environments to produce RNA sequence profiles. We controlled the environmental conditions in the following ways. We seeded the fly cultures with 5 male and 5 female parents. We reared the progeny in a single incubator on standard Drosophila food (http://flystocks.bio.indiana.edu/Fly_Work/media-recipes/bloomfood.htm) at 25°C, 60% humidity, and a 12:12-hour light:dark cycle. We collected and maintained male and female virgins at 20 flies to a same-sex vial for four days prior to RNA extraction to control for social exposure. Flies were frozen for RNA extraction at the same circadian time (1:00 pm) in 96-well plates. PolyA RNA stranded libraries were prepared by modifying an existing protocol. ERCC (External RNA Controls Consortium, SRM2374, beta version, pools 78A/78B) sequences were added during the library preparation as a control. For some samples >1 library was generated to check technical variation. We performed multiplexed single-end 76 bp sequencing on an Illumina HiSeq2000. Reads were mapped to FlyBase release 5 version 57 and release 6 version 01 of the Drosophila melanogaster genome and the ERCC sequences. Mapped reads were counted at the gene level.
Project description:Poised RNA polymerase II is predominantly found at developmental control genes and is thought to allow their rapid and synchronous induction in response to extracellular signals. How the recruitment of poised RNA Pol II is regulated during development is not known. By isolating muscle tissue from Drosophila embryos at five stages of differentiation, we show that the recruitment of poised Pol II occurs at many genes de novo and this makes them permissive for future gene expression. When compared to other tissues, these changes are stage-specific and not tissue-specific. In contrast, Polycomb group repression is tissue-specific and in combination with Pol II (the balanced state) marks genes with highly dynamic expression. This suggests that poised Pol II is temporally regulated and is held in check in a tissue-specific fashion. We compare our data to mammalian embryonic stem cells and discuss a framework for predicting developmental programs based on chromatin state. mRNA-seq of Drosophila tissues during development
Project description:The goal of this experiment was to identify genomic dCAP-D3 binding sites in Drosophila S2R+ cells dCAP-D3 was immunoprecipitated in two separate experiments with antibody YZ834 which was developed in the Longworth lab. IgG immunoprecipiation was performed alongside the dCAP-D3 immunoprecipitation to serve as controls for each experiment. Input chromatin was also harvested from each of the two experiments.
Project description:It has long been appreciated that striped pair-rule transcription factor expression is necessary for convergent extension in the early Drosophila embryo, although the mechanisms that link these transcriptional regulators to planar polarity in this tissue have long been elusive. The goal of this study was to determine the transcriptional tragets of the pair-rule transcription factors Eve and Runt in Drosophila blastoderm embryos. We compared the transcriptional profiles of late blastoderm embryos injected with either water or dsRNAs against both eve and runt to identify differentially expressed genes that may directly contribute to the establishment of planar polarity during Drosophila convergent extension. Comparing the mRNA profiles from late blastoderm Drosophila embryos injected with either water (Water) or eve+runt dsRNAs (Eve), in triplicate, using Illumina HiSeq.