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Davidson Lab Gene Regulatory Networks |
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ENDOMESODERM GENE NETWORK |
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Endomesoderm Network Views Back to Top |
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The increasing complexity of the network model means that a single overview network is no longer being provided. However, the view below of the endomesoderm territories after 21 hours is the closest to the traditional single overview network diagram, and the two network diagrams following it present more complete information for earlier time periods. All three "View from All Nuclei" (VfA) diagrams purport to illustrate the sum of linkages that are functional in the different places and the different stages of the endomesodermal specification process, including the Endomesoderm Specification 21 to 30 Hours, PMC Specification 6 to 30 Hours, and Endomesoderm Specification 6 to 18 Hours.i |
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Endomesoderm Specification 21 to 30 Hours: View From All Nuclei Back to Top ![]() |
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The architecture of the network is based on perturbation and expression data, on data from cis-regulatory analyses for several genes, and on other experiments discussed in text. See the endomesoderm network perturbation QPCR data for quantitative results of perturbation experiments and temporal details. Each short horizontal line from which a bent arrow extends to indicate transcription represents the cis-regulatory element that is responsible for expression of the gene named in the domain shown. Embryonic gene expression was perturbed in specific ways by use of antisense morpholino-substituted oligonucleotides by introduction of mRNA encoding Engrailed repressor domain fusions or mRNA encoding the normal protein product of the gene; by introduction of genetic expression constructs; by interference with the β-catenin/Tcf signal transduction system using overexpression of mRNA encoding an intracellular domain of cadherin; or by interference with the Notch (N) signaling system by overexpression of mRNA encoding the extracellular domain of the N receptor. RNA was extracted from embryos grown from eggs injected with the respective perturbation reagents and converted to cDNA. This was utilized in multiplexed quantitative PCR (QPCR) experiments to assess effects of each perturbation on the other genes indicated in the Figure. The arrows and barred lines indicate the normal function of the gene (activation or repression) as deduced from changes in transcript levels due to the perturbations. Minimum significance levels for inclusion in the model are three-fold increases or decreases in amount of transcript as a result of the perturbation; effects range up to several hundred fold. The relationships shown may in some cases be indirect, though all known or suspected indirect relationships have been excluded from the model. For linkages that are direct each input arrow constitutes a prediction of specific transcription factor target site sequence(s) in the relevant cis-regulatory control element. Experimental cis-regulatory results provide additional direct evidence; green diamonds indicate reported experimental evidence validates expected target site. Many genes are initially expressed over broader ranges, and their expression later resolves to the definitive domains indicated by their backgrounds. The rectangles in the lower tier of the diagram (with the exception of Small Mic/CP) show downstream differentiation genes. Dashed lines indicate inferred or possibly indirect relationships. Arrows inserted in arrow tails indicate intercellular signaling interactions. Large open ovals represent cytoplasmic biochemical interactions at the protein level, e.g., those responsible for nuclearization of β-catenin, the effect of Delta on Notch (Jacobsen et al., 1998) or of Neuralized on Delta (Yeh et al., 2000, 2001). Much data from experimental embryology and molecular biology are included in this model; for references see Davidson et al., Dev. Biol. 246, 162-190, 2002. |
PMC Specification 6 to 30 Hours: View From All Nuclei Back to Top ![]() |
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Endomesoderm Specification 6 to 18 Hours: View From All Nuclei Back to Top ![]() |
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Endomesoderm QPCR Data Tables Back to Top |
ECTODERM GENE NETWORK |
BioTapestry Interactive Network Viewer for Ectoderm Back to Top
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Ectoderm Network Views Back to Top |
The following four network diagrams illustrate portions regulatory gene network for ectoderm specification. These four "View from All Nuclei" (VfA) diagrams include the Mesomere Lineages Network 6 to 17 Hours, Oral Animal Ectoderm 18 to 30 Hours, Lateral and Aboral Animal Ectoderm 18 to 30 Hours, and Veg1 Ectoderm 21 to 30 Hours. These network views are supported by the following sources of information: (1) MASO perturbation experiments, the raw data for which are in the process of being added to the accompanying table below; (2) time course and in situ hybridization data for the regulatory genes in the network, some of which is published in the Genome Issue of Developmental Biology (v.300(1), 2006) and in the following references. Relevant additional data are from Gross et al, Development 130, 1989-1999, 2003; Duboc et al, Developmental Cell 6, 397-410, 2004; Duboc et al, ibid, 9, 147-158, 2005; Angerer et al, Development 128, 4393-4404, 2001; Bradham and McClay, ibid, 133, 21-33, 2006; Otim et al, Developmental Biology, 273, 226-243, 2004; Amore et al, ibid, 261, 55-81, 2003; Nam et al, ibid, 306, 860-869, 2007; Ben-Tabou de-Leon, S., Su, Y.-H., Lin, K.-T., Li, E., and Davidson, E. H. Developmental Biology 374, 245-254, 2013; Li, E., Cui, M., Peter, I.S., and Davidson, E. H. PNAS Online Feb 20, 2014, E906-913.
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Mesomere Lineages Network 6 to 17 Hours: View From All Nuclei Back to Top ![]() |
Oral Animal Ectoderm 18 to 30 Hours: View From All Nuclei Back to Top ![]() |
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Lateral and Aboral Animal Ectoderm 18 to 30 Hours: View From All Nuclei Back to Top ![]() |
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Veg1 Ectoderm 21 to 30 Hours: View From All Nuclei Back to Top ![]() |
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Ectoderm QPCR and Nanostring Data Tables Back to Top |
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HIGH DENSITY TIMECOURSE DATA |
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High Density Timecourse Data
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We measured the prevalence of 172 genes - transcription factors, signaling molecules and some markers - in early sea urchin development. Most of these genes are locally restricted in their spatial expression, and contribute to the divergent regulatory states of cells in the developing embryo. Many genes in this data set are already part of the gene regulatory networks covering endomesoderm or ectoderm, others have yet to be integrated.
In order to obtain high-resolution expression profiles samples were collected at hourly intervals from fertilization to late gastrulation. Rather than rely on housekeeping genes to quantify expression level we used external standards. For this we carefully transcribed GFP RNA and RFP RNA in vitro and accurately determined its concentration. We then added a fixed number of RNA molecules to lysates of a known number of embryos. Abundance of sea urchin transcripts and standards was determined with the
NanoString nCounter, an RNA counting device, and the resulting data were converted to molecules per embryo. The measured time courses agree well with, and substantially extend, prior relative abundance measurements obtained by quantitative PCR. The data are available via an
interactive plotting tool for quick plotting of selected time courses. For a detailed discussion of the data please consult the paper (Materna et al., 2010).
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References Back to Top
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