Project description:AtGenExpress: A multinational coordinated effort to uncover the transcriptome of the multicellular model organism Arabidopsis thaliana. The activity of genes and their encoded products can be regulated in several ways, but transcription is the primary level, since all other modes of regulation (RNA splicing, RNA and protein stability, etc.) are dependent on a gene being transcribed in the first place. The importance of transcriptional regulation has been underscored by the recent flood of global expression analyses, which have confirmed that transcriptional co-regulation of genes that act together is the norm, not the exception. Moreover, many studies suggest that evolutionary change is driven in large part by modifications of transcriptional programs. An essential first step toward deciphering the transcriptional code is to determine the expression pattern of all genes. With this goal in mind, an international effort to develop a gene expression atlas of Arabidopsis has been underway since fall 2003. This project, dubbed AtGenExpress, is funded by the DFG, and will provide the Arabidopsis community with access to a large set of Affymetrix microarray data. As part of this collaboration, we have generated expression data from 80 biologicaly different samples in triplicate. Seeds of Arabidopsis thaliana Wild Type (col-0) were sown on rafts in Magenta boxes containing MS-Agar-media. After 2 days in the cold room (4°C, dark) the boxes were transferred to the long day chamber. Long day conditions were 16/8 hrs light/dark, 24°C, 50% humidity and 150 µEinstein/cm2 sec light intensity. At day 11 the rafts were transferred in Magenta boxes containing MS-liquid-media. At day 16 stress treatment started at 3 hrs of light period; samples taken at 0.5, 1, 3, 6, 12, 24 h after treatment (in selected indicated cases 0.25h and 4.0h too), control samples include 0h; roots and shoots were prepared separately; all treatments and preparations were done on the same batch of seedlings in one place (Lab J.Kudla/Ulm, Germany) by coworkers from the indicated groups. Experimenter name = Jakub Horak , Klaus Harter; Experimenter institute = AtGenExpress Experiment Overall Design: 28 samples were used in this experiment
Project description:UV-B (280-320 nm) exposure causes serious damage in plants, limiting their growth and survival, effects that are partly counteracted by repair mechanisms active in plants receiving accompanying visible radiation. Though no particular UV-B receptor has been identified to date, there is strong evidence to indicate that certain aspects of UV-B perception are receptor-mediated. Investigations of down-stream signalling events have thus far indicated broad similarities to pathogen-induced defence responses in plants. In order to identify genes in Arabidopsis that may be up- or down- regulated specifically in response to UV-B exposure and compare them to genes whose expression is altered in plants challenged by an avirulent isolate of Peronospora parasitica (downy mildew), we propose to analyse the transcriptional profiles for the following treatments:; 1. UV-B Responses; "A-1" Columbia (Col-0) exposed to supplementary UV-B/UV-A* with a background of low photosynthetically active radiation (PAR of 20 micromol m-2 s-1) for 1.5 photoperiods (photoperiod = 12h). [UV-B treatment]; "A-2" Col-0 exposed to supplementary UV-A and low PAR for 1.5 photoperiods [control for UV-B treatment]; "A-3" Col-0 exposed to visible light only (low PAR) (no UV) for 1.5 photoperiods [control for UV effects in general].* There are no pure sources of UV-B light available. 2. Pathogen Responses; "A-4" Col-0 spray-inoculated with P. parasitica isolate HIKS-1 (recognised by the R-gene RPP7). After spraying, plants were kept covered in plant propagators and transferred to an 18 degreeC growth chamber. !Samples for RNA extraction were taken 72h after inoculation. "A-5" The viability of spores was also checked by parallel spraying of the susceptible mutant, Col-rpp7. [pathogen treatment]; "A-6" Col-0 mock treated with water, covered and transferred to an 18 degree C growth chamber, 72h prior to sampling. [control for pathogen treatment]; In all experiments, we are using RNA from leaves taken at the same time of day (6 h into the 12 h photoperiod) from 4.5-week old plants grown under 12h photoperiod. All treatments were normalised against PR-1 expression levels to ensure comparability between UV-B and pathogen treatments. Due to the difficulty in distinguishing between local and systemic induced responses in UV-B treated plants, we are using RNA from whole rosettes for both the UV-B and pathogen treatment for better comparability among treatments. The degree of similarity between these two sets of transcriptional changes will complement and help interpret our experimental data on changes in resistance to pathogens in plants pre-treated with UV-B. Moreover, the data set obtained would allow for identification of UV-B specific changes in gene expression including cis-acting UV-B-responsive promoter elements. Experimenter name = Julia Brueggemann; Experimenter phone = 01789 470 382; Experimenter fax = 01789 470 552; Experimenter address = Horticulture Research International; Experimenter address = Wellesbourne; Experimenter address = Warwickshire; Experimenter zip/postal_code = CV35 9EF; Experimenter country = UK Experiment Overall Design: 6 samples were used in this experiment
Project description:UV radiation is a ubiquitous component of solar radiation that affects plant growth and development. Analysis of natural variation in response to UV radiation revealed significant differences among natural accessions of Arabidopsis thaliana. However, the genetic basis of this is to a large extent unknown. Here, we analyzed the response of Arabidopsis accessions to UV radiation stress by performing RNA-sequencing of three UV sensitive and three UV resistant accessions. The genome-wide transcriptional analysis revealed a large number of genes significantly up- or down-regulated only in sensitive or only in resistant accessions, respectively. Mutant analysis of few selected candidate genes suggested by the RNA-sequencing results indicate a connection between UV radiation stress and plant-pathogen-like defense responses. Examination of transcriptional changes in response to UV treatment in Arabidopsis natural accessions
Project description:UV-induced DNA lesions are an important contributor to mutagenesis and cancer, but it is not fully understood how the chromosomal landscape influences UV lesion formation and repair. We have used a novel high-throughput sequencing method to precisely map UV-induced cyclobutane pyrimidine dimers (CPDs) at nucleotide resolution throughout the yeast genome. Analysis of CPD formation reveals that nucleosomal DNA having an inward rotational setting is protected from CPD lesions. In strongly positioned nucleosomes, this nucleosome 'photofootprint' overrides intrinsic dipyrimidine sequence preferences for CPD formation. CPD formation is also inhibited by DNA-bound transcription factors, in effect protecting important DNA elements from UV damage. Analysis of CPD repair revealed a clear signature of efficient transcription-coupled nucleotide excision repair. Repair was less efficient at translational positions near a nucleosome dyad and at heterochromatic regions in the yeast genome. These findings define the roles of nucleosomes and transcription factors in UV damage formation and repair. UV mapping data was analyzed for yeast cells irradiated with 125J/m2 and allowed to repair for 0hr (2 samples), 20 minutes, 1 hour, or 2 hours. Data is also included for naked DNA irradiated with UV 60 or 90 J/m2
Project description:The Rad23/Rad4 protein complex plays a major role in DNA damage recognition during nucleotide excision repair (NER) in yeast. We recently showed that two distinct pathways contribute to efficient NER in yeast. The first operates independently of de novo protein synthesis and requires a nonproteolytic function of the 19S regulatory complex of the 26S proteasome and Rad23. The second pathway requires de novo protein synthesis, and relies on the activity of a newly identified Rad7-containing E3 ubiquitin ligase that ubiquitinates Rad4 in response to UV. Surprisingly, we found that cells deleted of either Rad23 or Rad4 caused reduced Rad4 and Rad23 mRNA levels respectively. We considered the possibility of an unexpected role of Rad23 and Rad4 in regulating the expression of genes involved in the transcriptional response to DNA damage. Gene expression profiling has suggested that Rad23 and Rad4 may function as a complex to affect transcription of a small subset of genes in response to UV damage. To determine how Rad4 and Rad23 contribute to the regulation of these genes, we have examined the occupancy of Rad4/Rad23 in their promoter regions by chromatin immunoprecipitation (ChIP), both in the presence and absence of UV damage. Our preliminary ChIP data suggests that the Rad4/Rad23 complex regulates a set of genes in response to UV light. We also proposed that the transcriptional regulatory activity of the Rad4-Rad23 complex required Rad4 ubiquitination. These arrays test this theory using the psocs mutant strain, which is unable to facilitate Rad4 ubiquitination after UV irradiation. *** This Series represents the gene expression component of the study. Expression analysis was performed on the pRAD7 strain, which served as the WT control, and harboured the WT RAD7 sequence on the pRS313 plasmid, the psocs strain, which harboured the same plasmid with 2 point mutations in the RAD7 sequence that prevented post-UV Rad4 ubiquitination. Expression analysis was also conducted on a pRAD7 and psocs Strain with RAD23 deleted. Analysis was performed using untreated strains, and strains 15 minutes and 60 minutes after 100Jm-2 UV irradiation. mRNA was extracted from logaritmically growing cells.
Project description:We have found that MtFTb genes play a role in the response to LD conditions, both under vernalized and non-vernalized conditions. To explore the regulatory gene network downstream of FTb genes on a global scale, we performed RNA sequencing of the gene-edited Mtftb1/b2 vs WT plants. For this, we grew wild-type and gene-edited Mtftb1/2 plants under two different conditions: vernalised long days (VLD), where the plants were vernalized for 14 days and then grown for two weeks under LD photoperiod, with the aim of capture changes in expression profiles in the period in which the plant becomes physiologically committed to flower; the second condition was non-vernalised long days (NVLD), where non-vernalized plants were grown for 60 days, a crucial time point when wild-type plants typically undergo the transition to flowering. This approach allowed us to investigate the gene expression changes in the FTb1/2 mutant independent of vernalization effects.
Project description:Photosynthesis, the fundamental process using light energy to convert CO2 to organic matter, is vital for life on Earth. It relies on capturing light through light-harvesting complexes in photosystems I and II and converting light energy into chemical energy. Composition and organization of photosystem core complexes are well conserved across evolution, and are highly susceptible to photodamage. Consequently, a large diversity of photoprotective mechanisms have evolved in photoautotrophs, finely tuned for the specific light conditions. Light Harvesting Complex protein family (LHC and LHC-like families) have acquired a dual function during evolution. Members of the LHC antenna complexes of photosystems capture light energy whereas others dissipate excess energy that cannot be harnessed for photosynthesis. This process mainly occurs through non photochemical quenching (NPQ). In this work, we analysed the effect of UV-B on the proteome of Chlamydomonas.
Project description:We analysed global gene expression changes in Chlamydomonas reinhardtii in response to 1h UV-B, applied at the same low level that was seen to promote subsequent UV-B stress tolerance, in order to elucidate the transcriptional reprogramming that leads to UV-B acclimation. mRNA profiles generated by deep sequencing from triplicate replicate Chlamydomonas reinhardtii samples sourced from independent cultures either protected from UV-B or exposed to 1h acclimation-level UV-B.