Project description:Pelagic aggregates function as hotspots for microbial activity and biological carbon pumps for exporting OM fixed by photoautotrophs to sediments in lakes and oceans. In iron-rich (ferruginous) lakes, photoferrotrophic or chemolithoautotrophic bacteria appear to contribute to CO2 fixation by oxidizing reduced iron which leads to the formation of iron-rich pelagic aggregates called iron-snow. In acidic lakes, iron snow is colonized mainly by acidophilic iron-cycling microbes that can trigger interspecies aggregation mechanisms. However, the significance of iron oxidizers in carbon fixation, their general role in iron snow functioning, and the flow of carbon within iron snow is still unclear. Here, we combined a two-year metatranscriptome analysis with a 13CO2 metabolic labeling approach to determine general metabolic activities. Protein-based stable isotope probing (protein-SIP) was used to trace the 13CO2 incorporation in iron snow microcosms over time under both oxic and anoxic conditions. Analysis of our mRNA-derived metatranscriptome data identified four key players (Leptospirillum, Ferrovum, Acidithrix, Acidiphilium) with relative abundances (59.6%-85.7%) in iron snow encoding a variety of ecologically relevant pathways, including carbon fixation, polysaccharide biosynthesis, and flagellar-based motility. We did not detect transcriptional activity for carbon fixation from archaea or eukaryotes. The largest numbers of expressed genes (3008, 2991, 2936) matched to the genomes of our previously obtained iron snow isolates (Acidithrix sp. C25, Acidiphilium sp. C61, Acidocella sp. C78) separately. 13CO2 incorporation studies identified Leptospirillum and Ferrovum, as the main active chemolithoautotrophs under oxic conditions, and Ferrovum was the main active organism under anoxic conditions as well. Small amounts of labeled 13C (Relative isotope abundance: 1.0%-5.3%) were found in the heterotrophic Acidiphilium and Acidocella. Overall, our data show that iron oxidizers play an important role in the formation of iron minerals and CO2 fixation, but the majority of fixed C apparently did not reach other iron snow microbes. This finding suggests that most of the fixed C will be directly exported to the sediment without feeding heterotrophs in the water column in acidic ferruginous lakes.
Project description:Lack of resistance to pink snow mould (Microdochium nivale) is seen as a major constraint for adaptation of perennial ryegrass (Lolium perenne L.) at higher latitudes. Plants generally become more resistant to snow moulds after cold acclimation, and almost all investigations of genetic variation in resistance have been performed using cold acclimated plants. However, there may be variation in resistance mechanisms that are functioning independently of cold acclimation. In this study our aim was to identify candidate genes involved in such resistance mechanisms. We first characterized variation in resistance to M. nivale among non-acclimated plants of eight genotypes from the Norwegian cultivar Fagerlin and selected one resistant and one susceptible genotype for transcriptome analysis. Total RNA was extracted from leaf blade tissue of plants exposed to three different treatments: non-inoculated and non-incubated plants, non-inoculated plants after four days of incubation, and inoculated plants after four days of incubation. cDNA libraries were prepared and paired-end sequencing performed using Illumina Hiseq 2000. Transcriptome profiles, GO enrichment and KEGG pathway analysis indicate that defence response related genes are differentially expressed between incubated non-inoculated and incubated inoculated conditions both within resistant and susceptible genotypes. A significant up-regulation of defence related genes as well as genes involved in cell wall cellulose metabolic processes and aryl-alcohol dehydrogenase (NADP+) activity was observed in the resistant genotype. The candidate genes identified in this study might be potential molecular marker resources for breeding perennial ryegrass cultivars with improved resistance to pink snow mould.
Project description:This experiment has been annotated by TAIR (http://arabidopsis.org). We examined transcript profiles triggered by three different arabidopsis R genes that recognize distinct Peronospora parasitica isolates. Experimenter name = Thomas Eulgem Experimenter phone = 43 1 4277 54622 Experimenter fax = 43 1 4277 9546 Experimenter department = Institute of Microbiology and Genetics Experimenter address = Institute of Microbiology and Genetics Experimenter address = Dr. Bohrgasse 9 Experimenter address = Vienna Experimenter zip/postal_code = A-1030 Experimenter country = Austria Keywords: strain_or_line_design
Project description:We characterised physiological and proteomic changes between C. reinhardtii and the snow alga Chlamydomonas nivalis, to reveal insights into their contrasting responses to salinity stress
Project description:Semiconductor sequencing of alkaline degraded total RNA from Pyrococcus furiosus annotated for ”The 23S ribosomal RNA from Pyrococcus furiosus is circularly permuted” published in Frontiers in Microbiology”