Plants have evolved shoot elongation mechanisms to escape from diverse environmental stresses such as flooding and vegetative shade. The apparent similarity in growth responses suggests possible convergence of the signalling pathways. Shoot elongation is mediated by passive ethylene accumulating in flooded plant organs and by changes in light quality and quantity under vegetation shade. Here we study hypocotyl elongation as a proxy for shoot elongation and delineated Arabidopsis hypocotyl length kinetics in response to ethylene and shade. Based on these kinetics, we further investigated ethylene and shade-induced genome-wide gene expression changes in hypocotyls and cotyledons separately. Both treatments induced a more extensive transcriptome reconfiguration in the hypocotyls compared to the cotyledons. Bioinformatics analyses suggested contrasting regulation of growth promotion- and photosynthesis-related genes. These analyses also suggested an induction of auxin, brassinosteroid and gibberellin signatures and the involvement of several candidate regulators in the elongating hypocotyls. Pharmacological and mutant analyses confirmed the functional involvement of several of these candidate genes and physiological control points in regulating stress-escape responses to different environmental stimuli. We discuss how these signaling networks might be integrated and conclude that plants, when facing different stresses, utilise a conserved set of transcriptionally regulated genes to modulate and fine tune growth.
Ethylene- and Shade-Induced Hypocotyl Elongation Share Transcriptome Patterns and Functional Regulators.
Specimen part, Treatment, Time
View SamplesStudies of adult human hematopoiesis have until now relied on the expression of CD10 to define lymphoid commitment. We report a novel lymphoid-primed population in human bone marrow that is generated from hematopoietic stem cells (HSC) prior to the onset of CD10 expression and B cell commitment, and is identified by high levels of the homing molecule L-selectin (CD62L). CD10-CD62Lhi progenitors have full lymphoid (B/T/NK) potential, and show reduced myeloid and absent erythroid potential. Genome-wide gene expression analysis demonstrates that the CD10-CD62Lhi population represents an intermediate stage of differentiation between CD34+CD38- HSC and CD34+lin-CD10+ progenitors marked by down-regulation of TAL1 and MPL, upregulation of E2A, CD3E and IL2RG expression, and absent B cell commitment or RAG1/2 expression. Immature CD34+CD1a- thymocytes are also CD62Lhi and L-selectin ligands are expressed at the cortico-medullary junction, suggesting a possible role for L-selectin in human thymic homing. These studies identify the earliest stage of lymphoid priming in human bone marrow.
Lymphoid priming in human bone marrow begins before expression of CD10 with upregulation of L-selectin.
Specimen part
View SamplesThis study profiles transcriptomic changes of Arabidopsis thaliana Col-0 in response to submergence. This dataset includes CEL files, RMA signal values and MAS5 P/M/A calls from total mRNA populations of plants at 9 to 10 leaf rosette stage. Biological replicates of root and shoot tissues were harvested after 7 h and 24 h of submergence in darkness along with corresponding non-submerged dark controls. To characterize the dark response, non-submerged light controls plants were harvested at the 0 h time point. Quantitative profiling of cellular mRNAs was accomplished with the Affymetrix ATH1 platform. Changes in the transcriptome in response to submergence and early darkness were evaluated, and the data led to identification of genes co-regulated at the conditional and organ-specific level.
Molecular characterization of the submergence response of the Arabidopsis thaliana ecotype Columbia.
Specimen part, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
GPI-80 defines self-renewal ability in hematopoietic stem cells during human development.
Specimen part
View SamplesAdvances in pluripotent stem cell and reprogramming technologies have given hope of generating hematopoietic stem cells (HSC) in culture. To succeed, greater understanding of the self-renewing HSC during human development is required. We discovered that glycophosphatidylinositol-anchored surface protein GPI-80 (Vanin 2) defines a distinct subpopulation of human fetal hematopoietic stem/progenitor cells (HSPC) with self-renewal ability. CD34+CD90+CD38-GPI-80+ HSPC were the sole population that maintained proliferative potential and undifferentiated state in bone marrow stroma co-culture, and engrafted in immunodeficient mice. GPI-80 expression also enabled tracking of HSC migration between human fetal hematopoietic niches. The most highly enriched surface protein in GPI-80+ HSPC as compared to their progeny was Integrin alpha-M (ITGAM), which in leukocytes cooperates with GPI-80 to support migration. Knockdown of either GPI-80 or ITGAM was sufficient to perturb undifferentiated HSPC in stroma co-culture. These findings indicate that human fetal HSC utilize common mechanisms with leukocytes for cell-cell interactions governing HSC self-renewal.
GPI-80 defines self-renewal ability in hematopoietic stem cells during human development.
Specimen part
View SamplesAdvances in pluripotent stem cell and reprogramming technologies have given hope of generating hematopoietic stem cells (HSC) in culture. To succeed, greater understanding of the self-renewing HSC during human development is required. We discovered that glycophosphatidylinositol-anchored surface protein GPI-80 (Vanin 2) defines a distinct subpopulation of human fetal hematopoietic stem/progenitor cells (HSPC) with self-renewal ability. CD34+CD90+CD38-GPI-80+ HSPC were the sole population that maintained proliferative potential and undifferentiated state in bone marrow stroma co-culture, and engrafted in immunodeficient mice. GPI-80 expression also enabled tracking of HSC migration between human fetal hematopoietic niches. The most highly enriched surface protein in GPI-80+ HSPC as compared to their progeny was Integrin alpha-M (ITGAM), which in leukocytes cooperates with GPI-80 to support migration. Knockdown of either GPI-80 or ITGAM was sufficient to perturb undifferentiated HSPC in stroma co-culture. These findings indicate that human fetal HSC utilize common mechanisms with leukocytes for cell-cell interactions governing HSC self-renewal.
GPI-80 defines self-renewal ability in hematopoietic stem cells during human development.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Expansion on stromal cells preserves the undifferentiated state of human hematopoietic stem cells despite compromised reconstitution ability.
Specimen part, Cell line
View SamplesOne of the long-standing goals in the field has been to establish a culture system that would allow maintenance of HSC properties ex vivo. In the absence of such system, the ability to model human hematopoiesis in vitro has been limited, and there has been little progress in the expansion of human HSCs for clinical application. To that end, we defined a mesenchyml stem cell co-culture system for expansion of clonally multipotent human HSPCs that are protected from apoptosis and immediate differentiation, and retain the HSPC phenotype. By performing a genome-wide gene expression analysis of purified HSPCs isolated at different stages of co-culture, we asked at the molecular level, to what degree hematopetic stem cell properties can be preserved during culture. This temporal gene expression data from in vivo derived- and ex vivo expanded human HSPCs will serve as a resource to identify novel regulatory pathways that control HSC properties, and to develop clinically applicable protocols for HSC expansion.
Expansion on stromal cells preserves the undifferentiated state of human hematopoietic stem cells despite compromised reconstitution ability.
Specimen part
View SamplesOne of the long-standing goals in the field has been to establish a culture system that would allow maintenance of HSC properties ex vivo. In the absence of such system, the ability to model human hematopoiesis in vitro has been limited, and there has been little progress in the expansion of human HSCs for clinical application. To that end, we defined a mesenchymal stem cell co-culture system based on a monoclonal OP9 stromal cell line (OP9M2), for expansion of clonally multipotent human HSPCs that were protected from apoptosis and immediate differentiation, and retained the HSPC phenotype. To identify the supportive mechanisms, we performed a genome-wide gene expression analysis of OP9M2 stromal cells and compared the expression to a non-supportive stomal line (BFC012). This co-culture system provides a new, well-defined platform for studying mechanisms involved in HSC-niche interactions and protection of critical HSC properties ex vivo.
Expansion on stromal cells preserves the undifferentiated state of human hematopoietic stem cells despite compromised reconstitution ability.
Specimen part, Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Medial HOXA genes demarcate haematopoietic stem cell fate during human development.
Specimen part
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