This work uses a time series in order to decipher gene relationships and consequently to build core regulatory networks involved in Arabidopsis root adaptation to NO3- provision. The experimental approach has been to monitor genome response to NO3- at 3, 6, 9, 12, 15 and 20 min, using ATH1 chips. This high-resolution time course analysis demonstrated that the previously known primary nitrate response is actually preceded by very fast (within 3 min) gene expression modulation, involving genes/functions needed to prepare plants to use/reduce NO3-. State-space modeling (a machine learning approach) has been used to successfully predict gene behavior in unlearnt conditions.
Predictive network modeling of the high-resolution dynamic plant transcriptome in response to nitrate.
Specimen part, Treatment
View SamplesNitrogen and light are two major regulators of plant metabolism and development. While genes involved in the control of each of these signals have begun to be identified, regulators that integrate gene responses to nitrogen and light signals have yet to be determined.
Modeling the global effect of the basic-leucine zipper transcription factor 1 (bZIP1) on nitrogen and light regulation in Arabidopsis.
Specimen part
View SamplesWe investigated the morphological roots decisions of Arabidopsis in a NO3- heterogeneous medium. To do so, we used the Split-Root System which is an experimental set up to assess root decisions in nutrient heterogeneous medium. Split-root plants have been subjected to three different treatments. Control KNO3 plants received KNO3 on both sides of the root system (C.NO3) and Control KCl plants received KCl on both sides (C.KCl) as a nitrogen deprivation treatment. 'Split' plants received KNO3 on one side (Sp.NO3) and KCl on the other side (Sp.KCl) of the root system to assess the root decision-making in a heterogeneous environment.
Nitrogen economics of root foraging: transitive closure of the nitrate-cytokinin relay and distinct systemic signaling for N supply vs. demand.
Specimen part, Treatment
View SamplesThis work studies the impact of AtNIGT1/HRS1-GR entrance in the nucleus upon DEX treatment in protoplasts.
AtNIGT1/HRS1 integrates nitrate and phosphate signals at the Arabidopsis root tip.
No sample metadata fields
View SamplesWe performed an analysis of transcriptomic responses to auxin within four distinct tissues of the Arabidopsis thaliana root. This high-resolution dataset shows how different cell types are predisposed to react to auxin with discrete transcriptional responses. The sensitivity provided by the analysis lies in the ability to detect cell-type specific responses diluted in organ-level analyses. This dataset provides a novel resource to examine how auxin, a widespread signal in plant development, influences differentiation and patterning in the plant through tissue-specific transcriptional regulation.
A map of cell type-specific auxin responses.
Specimen part, Treatment
View SamplesLiving organisms have to cope with multiple and combined fluctuations in their environment. According to their sessile mode of life, plants are even more subjected to such fluctuations impacting their physiology and development. In particular, nutrient availability is known to tune plant development through modulating hormonal signaling, and conversely, hormonal signals are key to control nutrient related signaling pathways (Krouk et al., 2011a). However, very few is known about molecular mechanisms leading to plant adaptation to such combined signals. Here we deployed an unprecedented combinatorial treatment matrix to reveal plant adaptation in response to nitrate (NO3-), ammonium (NH4+), auxin (IAA), cytokinins (CK) and abscisic acid (ABA) and their exhaustive binary combinations.
Combinatorial interaction network of transcriptomic and phenotypic responses to nitrogen and hormones in the Arabidopsis thaliana root.
Specimen part, Time
View SamplesTo identify potential transient interactions between a TF and its targets, we developed an approach that can identify primary targets based either on TF-induced regulation or TF-binding, assayed in the same samples. Our studies focused on the TF bZIP1 (BASIC LEUCINE ZIPPER 1), a central integrator of cellular and metabolic signaling.
Hit-and-run transcriptional control by bZIP1 mediates rapid nutrient signaling in Arabidopsis.
No sample metadata fields
View SamplesCD4+ T helper lymphocytes that express interleukin-17 (Th17 cells) have critical roles in mouse models of autoimmunity, and there is mounting evidence that they also influence inflammatory processes in humans. Genome-wide association studies in humans have linked genes involved in Th17 cell differentiation and function with susceptibility to Crohns disease, rheumatoid arthritis, and psoriasis1-3. Thus, the pathway towards differentiation of Th17 cells and, perhaps, of related innate lymphoid cells with similar effector functions4, 5, is an attractive target for therapeutic applications. Mouse and human Th17 cells are distinguished by expression of the retinoic acid receptor-related orphan nuclear receptor RORt, which is required for induction of IL-17 transcription and for the manifestation of Th17-dependent autoimmune disease in mice6. By performing a chemical screen with an insect cell-based reporter system, we identified the cardiac glycoside digoxin as a specific inhibitor of RORt transcriptional activity. Digoxin inhibited murine Th17 cell differentiation without affecting differentiation of other T cell lineages and was effective in delaying the onset and reducing the severity of autoimmune disease in mice. At high concentrations, digoxin is toxic for human cells, but non-toxic synthetic derivatives, 20,22-dihydrodigoxin-21,23-diol (Dig(dhd)) and digoxin-21-salicylidene (Dig(sal)), specifically inhibited induction of IL-17 in human CD4+ T cells. Using these small molecule compounds, we demonstrated that RORt is imporant for the maintenance of IL-17 expression in mouse and human effector T cells. These data suggest that derivatives of digoxin can be used as chemical probes for development of RORt-targeted therapeutic agents that attenuate inflammatory lymphocyte function and autoimmune disease.
Digoxin and its derivatives suppress TH17 cell differentiation by antagonizing RORγt activity.
Treatment
View SamplesThe Caenorhabditis elegans somatic gonad was the first organ to have its cell lineage determined, and the gonadal lineages of the two sexes differ greatly in their pattern of cell divisions, cell migration and cell types. Despite much study, the genetic pathways that direct early gonadal development and establish its sexual dimorphism remain largely unknown, with just a handful of regulatory genes identified from genetic screens. To help define the genetic networks that regulate gonadal development, we employed cell-specific RNA-seq. We identified transcripts present in Z1/Z4 or Z1/Z4 daughter cells in each sex at the onset of somatic gonadal sexual differentiation. For comparison, transcripts were identified in whole animals at both time points. Pairwise comparisons of samples identified several hundred gonad-enriched transcripts, including most known Z1/Z4-enriched mRNAs, and reporter analysis confirmed the effectiveness of this approach. Prior to the Z1/Z4 division few sex-biased Z1/Z4 transcripts were detectable, but less than six hours later, we identified more than 250 sex-biased transcripts in the Z1/Z4 daughters, of which about a third were enriched in the somatic gonad cells compared to cells from whole animals. This indicates that a robust sex-biased developmental program, some of it gonad-specific, initiates in these cells around the time of the first Z1/Z4 division. Cell-specific analysis also identified approximately 70 previously unannotated mRNA isoforms that are enriched in Z1/Z4 or their daughters. Our data suggest that early sex differentiation in the gonad is controlled by a relatively small suite of differentially expressed genes, even after dimorphism has become apparent. Overall design: 20 total sample: two time points, two sexes, and gonadal cells or whole animals. The earlier time point was collected in triplicate and was harvested 9.5 hours after starved, hatched L1s were fed. The later time point was collected in duplicate and was harvested 15 hour after starved, hatched L1 were fed. Replicates of either dissociated whole animals or gonadal cells (Z1/Z4 or Z1/Z4 daughter) from both male and hermaphrodites were harvested for each time point.
Cell-Specific mRNA Profiling of the Caenorhabditis elegans Somatic Gonadal Precursor Cells Identifies Suites of Sex-Biased and Gonad-Enriched Transcripts.
Sex, Specimen part, Subject, Time
View SamplesPost-hybridization washing is an essential part of microarray experiments. Both, the quality of the experimental washing protocol and the adequate consideration of washing in intensity calibration ultimately affect the quality of the expression estimates extracted from the microarray intensities. We conducted experiments on GeneChip microarrays with altered protocols for washing, scanning and staining to study the probe-level intensity changes as a function of washing cycles. Particularly, three Affymetrix GeneChip HGU133plus2 arrays were hybridized and equilibrated for 16 hours in the hybridization oven. For one of the three arrays washing and staining was performed according to the manufacturers instructions. For another array the first scan was done immediately after low stringent wash and staining without intermitting stringent washing. Then, the array was stringently washed and scanned in alternating order three more times where each washing step consists of a definite number of washing cycles. The third array was low stringently washed followed by two stringent washing cycles and staining before the first scan. Subsequently it was analogously processed as array A. All three chips are repeatedly processed in a second series of alternating wash/scan-cycles which was performed using the same protocol for each chip as in the first series as described above. As in the first series the arrays were also stained a second time to compensate for any loss of bleached fluorescent dye. Analysis of the washing kinetics shows that the signal-to-noise ratio doubles roughly every ten stringent washing cycles. Washing can be characterized by time-dependent rate constants which reflect the heterogeneous character of target binding to microarray probes. We propose an empirical washing function which estimates the survival of probe bound targets. The washing function allows calibrating probe intensities for the effect of washing. On a relative scale, proper calibration for washing markedly increases expression measures especially in the limit of small and large values.
Washing scaling of GeneChip microarray expression.
Cell line
View Samples