Project description:The emerging picture of transcriptional regulation is one of unexpected complexity. It is now clear that single transcription factors control hundreds, if not thousands, of direct targets by binding their genomic loci, but it is not understood how many of these are major players and how many are supporting cast. To address this, we leverage a well-characterized developmental network in Arabidopsis and map genome-wide binding of related proteins in multiple tissues. The transcription factor APETALA2 (AP2) has numerous functions, including roles in floral organ identity, seed development and stem cell maintenance. We focus on the role of AP2 in the floral transition and map direct targets on a genome-wide scale. We show that ap2 mutants flower early in long and short days, and that AP2 binds to many loci, most prominently floral pathway integrators, microRNAs and floral organ identity genes, many of which exhibit AP2-dependent transcription. Opposing, logical effects are evident in AP2 binding to two developmental microRNA genes that control AP2 expression, with AP2 positively regulating miR156 and negatively regulating miR172, forming a complex direct feedback loop, which also included all but one of the AP2-like miR172 target clade members. We also seek conserved targets by comparing the genome-wide direct target repertoire of AP2 with that of SCHLAFMÜTZE (SMZ), another member of the AP2-like miR172 target clade that shares partial redundancy, as evidenced by a hexuple mutant for the entire clade that flowered extremely early. Clear similarities and divergence are exposed in the AP2 and SMZ direct target repertoires. Finally, using an inducible expression system, we demonstrate that AP2 has dual molecular roles. It functions both as a transcriptional activator and repressor, directly inducing the expression of the floral repressor AGAMOUS-LIKE 15 (AGL15), and directly repressing the transcription of floral activators like SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1). ChIP-Seq of two biological replicates for ATH-AP2 and respective control samples
Project description:Characterization of the activities of the transcription factor that AG encodes throughout flower development using perturbation assays and ChIP-Seq in combination with a floral induction system (FIS) that allows a stage-specific analysis of flower development. Examination of genomic regions bound by fully functional AG-GFP protein at approx floral stage 4-5 as compared to a negative control sample.
Project description:Despite great advances in sequencing capacity, generating functional information for non-model organisms remains a challenge. One solution lies in an improved ability to predict genetic circuits based on primary DNA sequence combined with the characterization of regulatory molecules from model species. Here, we focus on the LEAFY (LFY) transcription factor, a conserved master regulator of floral development. Starting with biochemical and structural information, we built a biophysical model describing LFY DNA binding specificity in vitro that accurately predicts in vivo LFY binding sites in the Arabidopsis thaliana genome. Extending the model to other species, we show that it can correctly identify functional homologs of known LFY targets from Arabidopsis thaliana in other angiosperms, even if a functional shift between orthologs and paralogs has occurred. Moreover, this model demonstrates the evolutionary fluidity of the link between LFY and one of its target genes, underlining how this regulatory interaction can be conserved despite changes in position, sequence and affinity of the LFY binding sites. Our study shows that the cis-element fluidity recently illustrated in animals also exists in plants, and that it can be detected without any experimental work in each individual species, using a biophysical transcription factor model. A. thaliana LEAFY ChIP-seq w control, 2 replicates
Project description:Characterization of the activities of the transcription factors that AP3 and PI encode throughout flower development using perturbation and ChIPSeq assays in combination with a floral induction system (FIS) that allows a stage-specific analysis of flower development. Examination of genomic regions bound by fully functional AP3-GFP and PI-GFP proteins at approx floral stage 4-5 as compared to a negative control sample
Project description:This SuperSeries is composed of the following subset Series: GSE38358: Molecular basis for the specification of floral organs by APETALA3 and PISTILLATA (ChIP-Seq) GSE38362: Molecular basis for the specification of floral organs by APETALA3 and PISTILLATA (mRNA) Refer to individual Series
Project description:The neurotoxic effects and mechanisms of low-dose and long-term sulfamethoxazole (SMZ) exposure remain unknown. This study exposed zebrafish to environmental SMZ concentrations and observed behavioral outcomes. SMZ exposure increased hyperactivity and altered the transcript levels of 17 genes associated with neurological function. It impaired intestinal function by reducing the number of intestinal goblet cells and lipid content. Metabolomic results indicated that the contents of several lipids and amino acids in the gut were altered, which might affect the expression levels of neurological function-related genes. Metagenomic results demonstrated that SMZ exposure substantially altered the composition of the gut microbiome. Zebrafish receiving a transplanted fecal microbiome from the SMZ group were also found to exhibit abnormal behavior, suggesting that the gut microbiome is an important target for SMZ exposure-induced neurobehavioral abnormalities. Multi-omics correlation analysis revealed that gut micrometabolic function was related to differential gut metabolite levels, which may affect neurological function through the gut-brain-axis. Reduced abundance of Lefsonia and Microbacterium was strongly correlated with intestinal metabolic function and may be the key bacterial genera in neurobehavioral changes. This study confirms for the first time that SMZ-induced neurotoxicity in zebrafish is closely mediated by alterations in the gut microbiome.