Leaf development has been monitored chiefly by following anatomical markers. Analysis of transcriptome dynamics during leaf maturation revealed multiple expression patterns that rise or fall with age or that display age specific peaks. These were used to formulate a digital differentiation index (DDI), based on a set of selected markers with informative expression during leaf ontogeny. The leaf-based DDI reliably predicted the developmental state of leaf samples from diverse sources and was independent of mitotic cell division transcripts or propensity of the specific cell type. When calibrated by informative root markers, the same algorithm accurately diagnosed dissected root samples. We used the DDI to characterize plants with reduced activities of multiple CINCINNATA (CIN)-TCP growth regulators. These plants had giant curled leaves made up of small cells with abnormal shape, low DDI scores and low expression of mitosis markers, depicting the primary role of CIN-TCPs as promoters of differentiation. Delayed activity of several CIN-TCPs resulted in abnormally large but flat leaves with regular cells. The application of DDI has therefore portrayed the CIN-TCPs as heterochronic regulators that permit the development of a flexible and robust leaf form through an ordered and protracted maturation schedule.
A protracted and dynamic maturation schedule underlies Arabidopsis leaf development.
No sample metadata fields
View SamplesLeaf development has been monitored chiefly by following anatomical markers. Analysis of transcriptome dynamics during leaf maturation revealed multiple expression patterns that rise or fall with age or that display age specific peaks. These were used to formulate a digital differentiation index (DDI), based on a set of selected markers with informative expression during leaf ontogeny. The leaf-based DDI reliably predicted the developmental state of leaf samples from diverse sources and was independent of mitotic cell division transcripts or propensity of the specific cell type. To calibrate and test the DDI a series of Arabidopsis shoot development was used (Efroni et al, 2008)
A protracted and dynamic maturation schedule underlies Arabidopsis leaf development.
No sample metadata fields
View SamplesFloral organ identities are specified by few transcription factors which act as master regulators. Subsequently, specification of organ axes programs the distribution of distinct tissue types within the organs that themselves develop unique identities. The C-class, AGAMOUS-clade MADS box genes are primary promoters of the gynoecium which is divided into a distal style and a subtending ovary along the apical-basal axis. We show that members of a clade of B3-domain transcription factors, NGATHA1 to NGA4 (NGA1-4), are expressed distally in all lateral organs, and all four have a redundant and essential role in style development. Loss of all four genes results in gynoecia where style is replaced by valve-like projections and a reduction in style-specific SHATTERPROOF1 (SHP1) expression. In agreement, floral misexpression of NGA1 promotes ectopic style and SHP1 expression. STYLISH1, an auxin biosynthesis inducer, conditionally activated NGA genes, which in turn, promoted distal expression of other STY genes in a putative positive feed back loop. Inhibited auxin transport or lack of YABBY1 gene activities resulted in a basally expanded style domain and broader expression of NGA genes. We speculate that early gynoecium factors delimit NGA gene response to an auxin-based signal, elicited by STY gene activity, to restrict the activation of style program to a late and distal carpel domain.
The NGATHA distal organ development genes are essential for style specification in Arabidopsis.
Age
View SamplesA prevalent hypothesis for the cell-to-cell coordination of the phenomena of early development is that a defined mixture of different mRNA species at specific abundances in each cell determines fate and behavior. With this dataset we explore this hypothesis by quantifying the abundance of every mRNA species in every individual cell of the early C. elegans embryo, for which the exact life history and fate is precisely documented. Overall design: Embryos of the 1-, 2-, 4-, 8- and 16-cell stage were dissected into complete sets of single cells, and each cell from each set was sequenced individually using SMARTer technology. 5-9 replicates were generated for each stage. Most cell identities were unknown upon sequencing, but were deduced from by their transcriptomes post hoc.
A Transcriptional Lineage of the Early C. elegans Embryo.
Specimen part, Subject
View SamplesIn seed plants, leaves are born on radial shoots but unlike shoots they are determinate dorsiventral organs made of flat lamina. YABBY genes are found only in seed plants and in all cases studied, are expressed primarily in lateral organs and in a polar manner. Despite their simple expression, Arabidopsis plants lacking all YABBY gene activities have a wide range of morphological defects in all lateral organs as well as the shoot apical meristem. Here we show that leaves lacking all YABBY activities are initiated as dorsiventral appendages but fail to properly activate lamina programs. In particular, the activation of most CIN-TCPs does not commence, SAM-specific programs are reactivated, and a marginal leaf domain is not established. Altered distribution of auxin signalling and the auxin efflux carrier PIN1, highly reduced venation, initiation of multiple cotyledons, and gradual loss of the SAM accompany these defects. We suggest that YABBY functions were recruited to mould modified shoot systems into flat plant appendages by translating organ polarity into lamina specific programs that include marginal auxin flow and activation a maturation schedule directing determinate growth.
Differentiating Arabidopsis shoots from leaves by combined YABBY activities.
Specimen part
View SamplesIn order to obtain a global picture regarding regulation of p53 in liver cells we used HepG2 hepatoma cells.We created two isogenic sub-cultures of HepG2 cells with altered expression of p53.
Chemotherapeutic agents induce the expression and activity of their clearing enzyme CYP3A4 by activating p53.
Specimen part, Cell line
View SamplesEffect of the overexpression of the oncogenic form of the Vav2 protein in the NIH3T3 cell line under serum deprivation conditions. oncovav2-transformed NIH3T3 cells grown in serum-deprived medium (Vav2SD) are compared to the parental NIH3T3 controls under the same growth conditions (ContSD). Vav2SD cells are also compared to the oncovav2-transformed NIH3T3 cells growing exponentially and the NIH3T3 growing exponentially.
Microarray analysis of gene expression with age in individual nematodes.
Cell line
View SamplesRecently, a frequent chromosomal aberration fusing Androgen regulated TMPRSS2 promoter and the ERG gene (T/ERG) was discovered in prostate cancer. Several studies demonstrated cooperation between the T/ERG and other defective pathways in cancer progression however, the biological mechanism by which the T/ERG operates is yet to be determined. Using immortalized prostate epithelial cells (EP) model we were able to show that EP with the combination of androgen receptor(AR) and T/ERG(EP-AR T/ERG cell line) demonstrate an Epithelial to Mesenchymal Transition (EMT) manifested by a mesenchyme-like morphological appearance and behavior.
TMPRSS2/ERG promotes epithelial to mesenchymal transition through the ZEB1/ZEB2 axis in a prostate cancer model.
Specimen part, Cell line
View SamplesThe effect of drugs, disease and other perturbations on mRNA levels are studied using gene expression microarrays or RNA-seq, with the goal of understanding molecular effects arising from the perturbation. Previous comparisons of reproducibility across laboratories have been limited in scale and focused on a single model. The use of model systems, such as cultured primary cells or cancer cell lines, assumes that mechanistic insights derived with would have been observed via in vivo studies. We examined the concordance of compound-induced transcriptional changes using data from several sources: rat liver and rat primary hepatocytes (RPH) from Drug Matrix (DM) and open TG-GATEs (TG), primary human hepatocytes (HPH) from TG, and mouse liver / HepG2 results from the Gene Expression Omnibus (GEO) repository. Gene expression changes for treatments were normalized to controls and analyzed with three methods: 1) gene level for 9071 high expression genes in rat liver, 2) gene set analysis (GSA) using canonical pathways and gene ontology sets, 3) weighted gene co-expression network analysis (WGCNA). Co-expression networks performed better than genes or GSA on a quantitative metric when comparing treatment effects within rat liver and rat vs. mouse liver. Genes and modules performed similarly at Connectivity Map-style analyses, where success at identifying similar treatments among a collection of reference profiles is the goal. Comparisons between rat liver and RPH, and those between RPH, HPH and HepG2 cells reveal low concordance for all methods. We investigate differences in the baseline state of cultured cells in the context of drug-induced perturbations in rat liver and highlight the striking similarity between toxicant-exposed cells in vivo and untreated cells in vitro.
Assessing Concordance of Drug-Induced Transcriptional Response in Rodent Liver and Cultured Hepatocytes.
Sex, Specimen part
View SamplesMdr1a-, Bcrp-, and Mrp2-knockout rats are a more practical species for ADME studies than murine models and previously demonstrated expected alterations in pharmacokinetics of various probe substrates. At present, gene expression and pathology changes were systematically studied in small intestine, liver, kidney, and brain tissue from male SAGE Mdr1a-, Bcrp-, and Mrp2-knockout rats versus wild-type Sprague Dawley controls. Gene expression data supported the relevant knockout genotype. As expected, Mrp2-knockout rats were hyperbilirubinemic and exhibited upregulation of hepatic Mrp3. Overall, few alterations were observed within 137 ADME-relevant genes. The two most consequential changes were upregulation of intestinal carboxylesterase in Mdr1a-knockouts and catechol-O-methyltransferase in all tissues of Bcrp-knockout rats. Previously reported upregulation of hepatic Mdr1b P-glycoprotein in proprietary Wistar Mdr1a-knockout rats was not observed in the SAGE counterpart investigated herein. Relative liver and kidney weights were 22-53% higher in all three knockouts, with microscopic increases in hepatocyte size in Mdr1a- and Mrp2-knockout rats, and glomerular size in Bcrp- and Mrp2-knockouts. Increased relative weight of clearing organs is quantitatively consistent with reported increases in clearance of drugs that are not substrates of the knocked-out transporter. Overall, SAGE knockout rats demonstrated modest compensatory changes, which do not preclude their general application to study transporter-mediated pharmacokinetics. However until future studies elucidate the magnitude of functional change, caution is warranted in rare instances of extensive metabolism by catechol-O-methyltransferase in Bcrp-knockouts and intestinal carboxylesterase in Mdr1a-knockout rats, specifically for molecules with free catechol groups and esters subject to gut wall hydrolysis.
Minor compensatory changes in SAGE Mdr1a (P-gp), Bcrp, and Mrp2 knockout rats do not detract from their utility in the study of transporter-mediated pharmacokinetics.
Sex, Specimen part
View Samples