Project description:The molecular mechanisms that control the ordered patterning of vascular tissue development in plant are not well understood. Several models propose a two component for plant vascular differentiation in which requires both an inducer of vascular tissue an also an inhibitory component that prevents the formation of vascular bundles near pre-existing bundles by a process often termed lateral inhibition. We have identified two recessive allelic mutants in Arabidopsis, designated continuous vascular (cov-1, cov-2), which display a dramatic increase in vascular tissue in the stem in place of the interfascicular region that normally separates the vascular bundles. The mutant plants exhibited normal vascular patterning in leaves and cotyledons. Analysis of the interaction of cov with known auxin signalling mutant and direct analysis of auxin concentrations suggests that cov affects vascular pattering by some mechanism that is independent of auxin. COV is expressed in all plant tissue but more highly in developing flowers and stems. The COV protein is predicted to be an integral membrane protein of unknown function, conserved in both plants and bacteria that is involved in negatively regulating the differentiation of the vascular tissue in the stem of Arabidopsis.The phenotype of COV exhibits some similarities to acl5 which is known to be a defect in the gene for spermidine synthase. Consequently, we are interested to test the idea that COV may be involved in the transport or perception of polyamines and that polyamines may be essential signals in normal vascular tissue development. Clearly, it this proves to be the case we would expect to see some differences in the transcript levels of genes associated with these pathways. Experimenter name = Simon Turner; Experimenter phone = 0161 275 5751; Experimenter fax = 0161 275 3938; Experimenter address = University of Manchester; Experimenter address = School of Biological Sciences; Experimenter address = 3.614 Stopford building; Experimenter address = Oxford Rd; Experimenter address = Manchester; Experimenter zip/postal_code = M13 9PT; Experimenter country = UK Experiment Overall Design: 8 samples were used in this experiment

Project description:The molecular mechanisms that control the ordered patterning of vascular tissue development in plant are not well understood. Several models propose a two component for plant vascular differentiation in which requires both an inducer of vascular tissue an also an inhibitory component that prevents the formation of vascular bundles near pre-existing bundles by a process often termed lateral inhibition. We have identified two recessive allelic mutants in Arabidopsis, designated continuous vascular (cov-1, cov-2), which display a dramatic increase in vascular tissue in the stem in place of the interfascicular region that normally separates the vascular bundles. The mutant plants exhibited normal vascular patterning in leaves and cotyledons. Analysis of the interaction of cov with known auxin signalling mutant and direct analysis of auxin concentrations suggests that cov affects vascular pattering by some mechanism that is independent of auxin. COV is expressed in all plant tissue but more highly in developing flowers and stems. The COV protein is predicted to be an integral membrane protein of unknown function, conserved in both plants and bacteria that is involved in negatively regulating the differentiation of the vascular tissue in the stem of Arabidopsis.The phenotype of COV exhibits some similarities to acl5 which is known to be a defect in the gene for spermidine synthase. Consequently, we are interested to test the idea that COV may be involved in the transport or perception of polyamines and that polyamines may be essential signals in normal vascular tissue development. Clearly, it this proves to be the case we would expect to see some differences in the transcript levels of genes associated with these pathways. Experimenter name = Simon Turner Experimenter phone = 0161 275 5751 Experimenter fax = 0161 275 3938 Experimenter address = University of Manchester Experimenter address = School of Biological Sciences Experimenter address = 3.614 Stopford building Experimenter address = Oxford Rd Experimenter address = Manchester Experimenter zip/postal_code = M13 9PT Experimenter country = UK Keywords: genetic_modification_design

Project description:Transcriptome analysis of adult hematopoietic stem cells (HSC) and their progeny has informed our understanding of blood differentiation and leukemogenesis, but a similarly transformative analysis of the embryonic origins of hematopoiesis is lacking. To address this issue, we acquired gene expression profiles of developing HSC purified from over 2500 dissected murine embryos and adult mice, and applied a network biology-based analysis to reconstruct the gene regulatory networks of sequential stages of HSC development. We found that embryonic hematopoietic elements clustered into three distinct transcriptional states characteristic of the definitive yolk sac, HSCs emerging from hemogenic endothelium, and definitive HSCs. We functionally validated several candidate transcriptional regulators of HSC ontogeny by morpholino-mediated knock-down in zebrafish embryos, confirming changes in the expression of HSC markers runx1 and c-myb in the aorta-gonads-mesonephros (AGM), the site of definitive HSC specification. Moreover, we found that HSCs derived from differentiating embryonic stem cells in vitro (ESC-HSC) most closely resemble definitive HSC, yet lack a signature indicative of specification by Notch signaling, which likely accounts for their deficient lymphoid development. Our analysis and accompanying web resource will accelerate the characterization of regulators of HSC ontogeny, facilitate efforts to direct hematopoietic differentiation and cell fate conversion, and serve as a model to study the origins of other adult stem cells. Hematopoietic stem cells and their precursors were isolated from mouse embryos and distinct stages and sites during development, purified by fluorescence activated cell sorting, and gene expression profiled on Affymetrix arrays. We also profiled HSCs and their precurors derived by in vitro differentitation of embryonic stem cells [expression data from GSE16925 and GSE14012 was used for mESCs, available at http://hsc.hms.harvard.edu/].

Dataset Information

Microdissection data of 3 vascular bundles stages - Brachypodium Vascular ontogeny

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