Project description:The diatoms Thalassiosira hyalina and Nitzschia frigida are important members of Arctic pelagic (open-water) and sympagic (ice-associated) microalgal communities. We investigated here the molecular mechanisms these algae apply to cope with abrupt high light exposure (Shift from 20 to 380 µmol photons m-2 s-1, resembling upwelling or ice break-up). Experiments were done under contemporary as well as future pCO2 (400 vs. 1000 µatm) to investigate whether [CO2] or pH modulate the reactions to high light intensities. After proper acclimation to the low-light regime, cells were sampled (= 0 hours), then exposed to the high-light treatment expression patterns were followed over 120h. Transcriptomic data were discussed also in the light of an accompanying physiological dataset from the same experiment (Ane Kvernvik et al. in prep).
Project description:Analyses of new genomic, transcriptomic or proteomic data commonly result in trashing many unidentified data escaping the ‘canonical’ DNA-RNA-protein scheme. Testing systematic exchanges of nucleotides over long stretches produces inversed RNA pieces (here named “swinger” RNA) differing from their template DNA. These may explain some trashed data. Here analyses of genomic, transcriptomic and proteomic data of the pathogenic Tropheryma whipplei according to canonical genomic, transcriptomic and translational 'rules' resulted in trashing 58.9% of DNA, 37.7% RNA and about 85% of mass spectra (corresponding to peptides). In the trash, we found numerous DNA/RNA fragments compatible with “swinger” polymerization. Genomic sequences covered by «swinger» DNA and RNA are 3X more frequent than expected by chance and explained 12.4 and 20.8% of the rejected DNA and RNA sequences, respectively. As for peptides, several match with “swinger” RNAs, including some chimera, translated from both regular, and «swinger» transcripts, notably for ribosomal RNAs. Congruence of DNA, RNA and peptides resulting from the same swinging process suggest that systematic nucleotide exchanges increase coding potential, and may add to evolutionary diversification of bacterial populations.
