Project description:Flowering of Arabidopsis thaliana is accelerated by several environmental cues, including exposure to long days. The photoperiod-dependent promotion of flowering involves the transcriptional induction of FLOWERING LOCUS T (FT) in the phloem of the leaf. FT encodes a mobile protein that is transported from the leaves to the shoot apical meristem, where it forms part of a regulatory complex that induces flowering. Whether FT also has biological functions in leaves of wild-type plants remains unclear. In order to address this issue, we first studied the leaf transcriptomic changes associated with its over expression in the companion cells of the phloem. To this end, transgenic A. thaliana plants that misexpress FT from the pGAS1 promoter in a ft-10 tsf-1 double mutant background were employed (pGAS1:FT ft-10 tsf-1). In these transgenic plants, the use of the pGAS1 promoter ensures that the FT transgene is expressed in phloem companion cells of the minor veins, recreating the spatial pattern of expression described for the native gene. In this studuy, the transcriptome of leaves of pGAS1:FT ft-10 tsf-1 transgenic plants was compared to that of ft-10 tsf-1 and Col-0 plants using Tiling Arrays.
Project description:The aim of this experiment was to investigate the regulation of gene expression by KLF3 and KLF8 in fetal erythroid cells by analyzing single and double mutant mouse models. Affymetrix microarrays were performed on RNA from TER119+ fetal liver cells from E13.5 wildtype, Klf8gt/gt, Klf3-/- and Klf3-/- Klf8gt/gt mice.
Project description:The aim of this experiment was to investigate the regulation of gene expression by KLF3 and KLF8 in fetal erythroid cells by analyzing single and double mutant mouse models. Affymetrix microarrays were performed on RNA from TER119+ fetal liver cells from E13.5 wildtype, Klf8gt/gt, Klf3-/- and Klf3-/- Klf8gt/gt mice. Four wildtype replicates, four Klf8gt/gt replicates, three Klf3-/- replicates and four Klf3-/- Klf8gt/gt replicates of E13.5 TER119+ fetal liver cell samples, litter-matched where possible.
Project description:Plants align flowering with optimal seasonal conditions to increase reproductive success. This process depends on modulating signalling pathways that respond to diverse environmental and hormonal inputs, thereby regulating the transition to flowering at the shoot apical meristem. In Arabidopsis, long-day photoperiods (LDs) stimulate the transcription of FLOWERING LOCUS T (FT), encoding the main florigenic signal. FT activation is mediated by the transcriptional regulator CONSTANS (CO), which binds to the CO responsive elements (COREs) located in the proximal FT promoter region. The phytohormone abscisic acid also (ABA) contributes to FT activation together with GIGANTEA (GI) to regulate drought escape (DE). Whether CO is a target of ABA and GI actions for the regulation of FT is, however, unknown. Here we report that ABA and its signalling components promote CO recruitment to the COREs, without causing clear effects on the diel pattern of CO protein accumulation. We also found that GI promotes CO recruitment to the COREs region, and that CO recruitment is required for the accumulation of RNAPol II at the TRANSCRIPTION START SITE of FT. Finally, we show that GI and ABA signalling pathways are largely epistatic in the control of flowering time, suggesting their involvement in the same molecular process. Taken together, these observations suggest that varying water deficit conditions modulate CO recruitment and FT expression, thus dictating DE strategies in Arabidopsis.
Project description:Background: It has been shown previously that administration of Francisella tularensis (Ft) LVS lipopolysaccharide (LPS) protects mice against subsequent challenge with Ft LVS and blunts the pro-inflammatory cytokine response. Methods: To investigate further the molecular mechanisms that underlie Ft LVS LPS-mediated protection, we profiled global hepatic gene expression following Ft LVS LPS or saline pretreatment and subsequent Ft LVS challenge using Affymetrix arrays. Results: A large number of genes (> 3000) were differentially expressed at 48 hours post-infection. The degree of modulation of inflammatory genes by infection was clearly attenuated by LPS-pretreatment in the surviving mice. However, LPS alone had a subtle but significant effect on the gene expression profile of the uninfected mice. By employing gene set enrichment analysis, we discovered significant up-regulation of peroxisome proliferator activated receptors (PPARs) and their target genes in LPS-treated liver. Conclusions: We hypothesize that the LPS-induced blunting of pro-inflammatory response in mouse is, in part, mediated by PPARs (alpha and gamma).
Project description:Background: It has been shown previously that administration of Francisella tularensis (Ft) LVS lipopolysaccharide (LPS) protects mice against subsequent challenge with Ft LVS and blunts the pro-inflammatory cytokine response. Methods: To investigate further the molecular mechanisms that underlie Ft LVS LPS-mediated protection, we profiled global hepatic gene expression following Ft LVS LPS or saline pretreatment and subsequent Ft LVS challenge using Affymetrix arrays. Results: A large number of genes (> 3000) were differentially expressed at 48 hours post-infection. The degree of modulation of inflammatory genes by infection was clearly attenuated by LPS-pretreatment in the surviving mice. However, LPS alone had a subtle but significant effect on the gene expression profile of the uninfected mice. By employing gene set enrichment analysis, we discovered significant up-regulation of peroxisome proliferator activated receptors (PPARs) and their target genes in LPS-treated liver. Conclusions: We hypothesize that the LPS-induced blunting of pro-inflammatory response in mouse is, in part, mediated by PPARs (alpha and gamma). Experiment Overall Design: Two groups of 9 mice each were used for this experiment. 48 hours prior to Ft LVS challenge, mice were injected i.p. with either 100 ng of Ft LVS LPS or an equivalent volume of saline. On the day of challenge, 3 saline- and 3 Ft LVS LPS-pretreated animals were sacrificed (uninfected controls), while all remaining mice were challenged i.p. with ~4-5 X 105 Ft LVS. Ft LVS-challenged mice were sacrificed (in groups of 3) at 24 and 48 hours post-infection.