Project description:An experiment was performed to determine the similarities on the RNA level between different conditions where cell division stops in the diatom Phaeodactylum tricornutum. Many of these conditions also increase the accumulation of lipids within the cell or impair photosynthesis. The different metabolic responses were evaluated and the dataset was mined for potential transcriptional regulators of these changes. The experimental setup was as follows: Cells from the pennate diatom Phaeodactylum tricornutum were grown in ESAW medium under continous fluorescent light at 21C in baffled shakeflasks. Exponentially growing cells were harvested by centrifugation and washed twice in 21gr/L NaCL to remove nutrients. Cells were subsequently resuspended in the five different media/conditions (control, darkness, no nitrate, no phosphate, nocodazole).
Project description:Diatoms, which are responsible for up to 40% of the 45 to 50 billion metric tons of organic carbon production each year in the sea, are particularly sensitive to Fe stress. Here we describe the transcriptional response of the pennate diatom Phaeodactylum tricornutum to Fe limitation using a partial genome microarray based on EST and genome sequence data. Processes carried out by components rich in Fe, such as photosynthesis, mitochondrial electron transport and nitrate assimilation are down-regulated to cope with the reduced cellular iron quota. This retrenchment is compensated by nitrogen (N) and carbon (C) reallocation from protein and storage carbohydrate degradation, adaptations to chlorophyll biosynthesis and pigment metabolism, removal of excess electron s by mitochondrial alternative oxidase (AOX), augmented Fe-independent oxidative stress responses, and sensitized iron capture mechanisms. Keywords: Marine phytoplankton, pinnate diatom Wild-type Phaeodactylum tricornutum was grown under Fe replete (10,000 nM) and Fe limiting (5nM) conditions. Partial genome gene expression analysis of iron-inducible genes was conducted using a two-color competitive hybridization microarray.
Project description:We have done next generation sequencing of optically thin, exponentialy growing WT Phaeodactylum tricornutum and our ~50% nitrate reductase knock-down cultures. Culture were grown with and without nitrogen source to improve our undestanding of the pathways regulation under conditions that promote lipid accumulation (N-starvation).
Project description:Phaeodactylum tricornutum transcriptome respionses to shifts in niitrate availability in wild type and nitrate reductase knock out cell lines (data set 2)
Project description:The photosynthetic model marine diatom Phaeodactylum tricornutum was cultured with varying nitrogen sources and availability to elicit shifts in the proteome. Cells were grown to mid-exponential phase on ammonium (880 uM), collected by centrifugation and resuspended in N-free media for 2 hrs, and spiked with nitrate (150 uM) for 90 min. Cells were again collected by centrifugation, washed in N-free media, and resuspended in experimental treatments with no nitrogen (N-) and a nitrogen source (300 uM) provided as ammonium, nitrite, or nitrate. Each experimental treatment was sampled after 15 min, 45 min, and 18 hr.