Project description:BackgroundBiofilm formation has been studied in much detail for a variety of bacterial species, as it plays a major role in the pathogenicity of bacteria. However, only limited information is available for the development of archaeal communities that are frequently found in many natural environments.MethodologyWe have analyzed biofilm formation in three closely related hyperthermophilic crenarchaeotes: Sulfolobus acidocaldarius, S. solfataricus and S. tokodaii. We established a microtitre plate assay adapted to high temperatures to determine how pH and temperature influence biofilm formation in these organisms. Biofilm analysis by confocal laser scanning microscopy demonstrated that the three strains form very different communities ranging from simple carpet-like structures in S. solfataricus to high density tower-like structures in S. acidocaldarius in static systems. Lectin staining indicated that all three strains produced extracellular polysaccharides containing glucose, galactose, mannose and N-acetylglucosamine once biofilm formation was initiated. While flagella mutants had no phenotype in two days old static biofilms of S. solfataricus, a UV-induced pili deletion mutant showed decreased attachment of cells.ConclusionThe study gives first insights into formation and development of crenarchaeal biofilms in extreme environments.
Project description:To achieve extreme manganese stress, we used DmntP E. coli strain. We identified the pathways that are altered under manganese stress. Mainly, manganese altered the metabolism of iron in the cell. Therefore, we have shown that iron supplementation mitigates manganese toxicity. Overall, our data explains the basis of manganism in higher organisms.
Project description:To investigate acclimation mechanisms employed under extreme high light conditions, gene expression analysis was performed using the model microalgae Synechocystis sp. PCC 6803 (PCC 6803) cultured under various light intensities. From the low to the mid light conditions, the expression of genes related to light harvesting systems was repressed, whereas that of CO2 fixation and of D1 protein turnover-related genes was induced. Gene expression data also revealed that the down-regulation of genes related to flagellum synthesis (pilA2), pyridine nucleotide transhydrogenase (pntA and pntB), and sigma factor (sigA and sigF) represents acclimation mechanisms of PCC 6803 under excessive high light conditions.
Project description:Mahonia Bealei was used as a traditional Chinese medicine for its high alkaloid content. Previous research found that alkaloid and flavonoid contents in the M. bealei leaves increased under combinatory treatments of ultraviolet B and dark. In order to explore the underlying response mechanism, TiO2 material enrichment and mass-based label-free quantitative proteomics techniques were used for phosphoproteomics analysis of M. bealei leaves under ultraviolet B. ATP content, photosynthetic pigment content, and some enzymatic/non-enzymatic indicators increased in the leaves of M. bealei under UV-B radiation. Phosphoproteomics study found that under the UV-B radiation, phosphoproteins related to MAPK signal transduction and plant hormone brassinosteroid signaling pathway were varied greatly. Phosphoproteins related to photosynthesis, glycolysis, tricarboxylic acid cycle, and amino acid synthesis/metabolism pathway were also significantly changed. These results suggested that the ultraviolet B radiation activated oxidative stress system, MAPK signal transduction pathway, and photosynthetic energy metabolism pathway. These changes are important for the redox reactions in secondary metabolism and the accumulation of secondary metabolites in M. bealei leaves under UV-B radiation.
Project description:Microbial iron reduction is a widespread and ancient metabolism on Earth, and may plausibly support microbial life on Mars and beyond. Yet, the extreme limits of this metabolism are yet to be defined. To investigate this, we surveyed the recorded limits to microbial iron reduction in a wide range of characterized iron-reducing microorganisms (n = 141), with a focus on pH and temperature. We then calculated Gibbs free energy of common microbially mediated iron reduction reactions across the pH-temperature habitability space to identify thermodynamic limits. Comparing predicted and observed limits, we show that microbial iron reduction is generally reported at extremes of pH or temperature alone, but not when these extremes are combined (with the exception of a small number of acidophilic hyperthermophiles). These patterns leave thermodynamically favourable combinations of pH and temperature apparently unoccupied. The empty spaces could be explained by experimental bias, but they could also be explained by energetic and biochemical limits to iron reduction at combined extremes. Our data allow for a review of our current understanding of the limits to microbial iron reduction at extremes and provide a basis to test more general hypotheses about the extent to which biochemistry establishes the limits to life.
Project description:The molecular mechanisms by which individuals subjected to environmental heat stress either adapt or develop heat-related complications are not well understood. We analysed the changes in blood mononuclear gene expression patterns in human volunteers exposed to an extreme heat in a sauna (temperature of 78 ± 6 °C).
Project description:The molecular mechanisms by which individuals subjected to environmental heat stress either adapt or develop heat-related complications are not well understood. We analysed the changes in blood mononuclear gene expression patterns in human volunteers exposed to an extreme heat in a sauna (temperature of 78 ± 6 °C).