Project description:Genome wide rhythmic transcription under light/dark cycles is associated with sequential transcription of specific biological processes genes in Ostreococcus tauri. Transcriptional profiling of Ostreococcus tauri under light/dark cycles. In order to identify genes with a diurnal rhythm, cells entrained under 12:12 light/dark cycles were sampled every 3 hours for 27 hours with two overlapping time points at Time 9 (Light ON at Time 9; Light OFF at Time 21) in 3 independent experiments.
Project description:Although it is well established the seasonal effect of the photoperiod over the transcriptional expression patterns in plants, this effect has not been studied in microalgae. Here we fill the gap using the model microalgae Ostreococcus tauri.
Project description:Genome wide rhythmic transcription under light/dark cycles is associated with sequential transcription of specific biological processes genes in Ostreococcus tauri. Transcriptional profiling of Ostreococcus tauri under light/dark cycles. In order to identify genes with a diurnal rhythm, cells entrained under 12:12 light/dark cycles were sampled every 3 hours for 27 hours with two overlapping time points at Time 9 (Light ON at Time 9; Light OFF at Time 21) in 3 independent experiments. Two-conditions experiment, test situation (kinetic point) vs. Pool of each samples. Biological triplicates: 3 independant kinetics, 9 points per kinetics, Technical triplicates per array.
Project description:Engineered nanoparticles (ENPs) are increasingly used to generate innovative industrial and medical goods. Because of their broad applications, they form a new class of pollutants with potential eco-toxicological impacts on marine ecosystems. Attempting to evaluate the risk, we investigated the toxicity of Iron and Zinc oxide ENPs on three picophytoplanktonic strains of algae: Micromonas commoda, Ostreococcus tauri and Nannochloris sp. Microalgae responses are highly species-dependent, Micromonas commoda growth being severely impaired by both ENP types whereas Ostreococcus tauri or Nannochloris sp. are resistant. ZnO ENPs have higher toxicity than iron ENPs though growth of M. commoda was severely inhibited by Fe2O3 ENPs. Transcriptome-wide analysis after exposure of M. commoda to ENPs shows that the altered biological processes mainly take place in the cytoplasm and that the response to ENPs is largely metabolic in nature: stimulation of carbohydrate metabolism, light harvesting processes and alteration of the nitrogen pathway. In addition, a severe disruption of ribosome structure and translation processes is observed.
Project description:Casein Kinase 1 (CK1) is one of few proteins known to affect cellular timekeeping across metazoans, and the naturally occurring CK1tau mutation shortens circadian period in mammals. Functional conservation of a timekeeping function for CK1 in the green lineage was recently identified in the green marine unicell Ostreococcus tauri, in spite of the absence of CK1's transcriptional targets known from other species. The short-period phenotype of CK1tau mutant in mammals depends specifically on increased CK1 activity against PERIOD proteins. To understand how CK1 acts differently upon the algal clock, we analysed the effect of CK1tau overexpression on the phospho-preoteome of O. tauri using label-free quantification compared to the parent line. Ostreococcus tauri cells were harvested, trypsinised and phosphopeptide enrichment was performed using TiO2 columns followed by LC-MS separation (140minute gradient) on a Orbitrap XL. All those steps are described previously (Le Bihan et al J Proteomics. 2011 Sep 6;74(10):2060-70). MSMS data was searched using MASCOT Version 2.4 (Matrix Science Ltd, UK) against the Ostreococcus tauri subset of the NCBI protein database (12/01/2011; 8,726 sequences) using a maximum missed-cut value of 2., variable oxidation (M), N-terminal protein acetylation, phosphorylation (STY) and fixed carbamidomethylation (C); precursor mass tolerance was 7 ppm and MSMS tolerance 0.4 amu. The significance threshold (p) was set below 0.05 (MudPIT scoring).
Project description:The overall set of experiments consist of sampling a culture of the unicellular algae Ostreococcus tauri (wild type) every 4 hours over a period of 24h (6 time points). Each time point was performed with 5 replicate culture flasks, the cultures were collected while maintained under dark condition.