Project description:The sea-ice dwelling diatom Fragilariopsis Cylindrus was cultured for 4 months under dark or light exposed conditions to mimic the effects of Antarctic winter growth conditions. Cells were harvested periodically and LFQ proteomics used to investigate the molecular mechanisms of dark survival.
Project description:We performed RNA-sequencing experiments to examine the differential regulation of genes in the genome of the Southern Ocean diatom Fragilariopsis cylindrus including diverged alleles. RNA-seq was performed on three replicate samples for each experimental condition. Phytoplankton cells were grown under six different experimental conditions including (1) optimal growth, (2) freezing temperatures, (3) elevated temperature, (4) elevated carbon dioxide concentrations, (5) low iron concentrations and (6) prolonged darkness. Total RNA was extracted using a guanidinium thiocyanate-phenol-chloroform extraction protocol, followed by DNase I treatment and RNA purification (Quiagen). First strand cDNA synthesis was performed using random hexamers. Library preparation was performed using the RNA-seq Sample Prep Kit (Illumina) and sequencing was conducted according to the TruSeq RNA sequencing protocol (Illumina) All samples were sequenced together in one flowcell on one lane.
Project description:Diatoms, the major eukaryotic phytoplankton in polar regions, are essential to sustain food webs. As such, it is fundamental to understand the physiological mechanisms and associated molecular basis of resilience to polar night of diatoms. Here, we report an integrative approach that reveals that in prolonged darkness, the cell enters a state of hypometabolism associated with reduced transcriptional activity during which no cell division occurs. Minimal energy is provided by respiration via alternative oxidase and progressive degradation of protein, carbohydrate and lipid stores. We also report internal structural changes that manifest the morphological acclimation of cells to darkness. Our results further indicate that immediately after returning to light, the majority of cells were able to use photoprotective mechanisms and resume photosynthesis. Divisions of surviving cells resumed at rates similar to those before darkness. Our study demonstrates the robustness of this species to prolonged darkness at low temperatures.
Project description:The Southern Ocean diatom Fragilariopsis cylindrus was grown under half-saturating concentrations of silicate (0.3 uM) and in the blue (480 - 540 nm) and red (550 - 700 nm) light spectrum to investigate gene expression responses using RNA-seq relative to optimal growth conditions (deposited under accession E-MTAB-5024). RNA-seq was performed on three replicate samples for each experimental condition. Total RNA was extracted using a guanidinium thiocyanate-phenol-chloroform extraction protocol, followed by DNase I treatment and RNA purification (Quiagen). First strand cDNA synthesis was performed using random hexamers. Library preparation was performed using the RNA-seq Sample Prep Kit (Illumina) and sequencing was conducted according to the TruSeq RNA sequencing protocol (Illumina) All samples were sequenced together in one flowcell on one lane.
