Project description:To examine the mechanisms during oil production and integrate analysis of lactylation in N. oceanica, protein expression profiles were tracked after nitrogen deprivation for three days using 4D label-free proteome method. Under nitrogen deprivation (ND) and nitrogen repletion (NR) cultivation conditions, we mapped proteome of proliferating microalgal cells.
Project description:Nitrogen starvation is an efficient environmental pressure used to increase lipid accumulation and oil droplet formation in microalgal cells. Various studies focused on metabolic changes occurring in microalgae in nitrogen starvation conditions, but the mechanisms at the basis of these changes are not completely understood. Between microalgae, green algae, with more than 7000 species growing in a variety of habitats, have been frequently studied for energy purposes, but also as source of bioactive extracts/compounds. In this study, de novo transcriptome of the green algae Tetraselmis suecica has been performed in order to (1) deeply study its response to nitrogen starvation, (2) to look for enzymes with antioxidant capacity and for polyketide synthases (PKSs), (3) if present, to evaluate if nutrient starvation can influence their expression levels.
Project description:Microarray analysis of Aspergillus niger under conditions with differing combinations of carbon source, nitrogen source, nitrogen concentration, and culture pH Fermentor cultures were grown in minimal medium (MM) at a constant temperature of 30 ± 0.5 ºC and with differing combinations of carbon source (either 277.5 mM glucose or 333.0 mM xylose), nitrogen source (NH4Cl or NaNO3) and nitrogen concentration (4x: 282.4 mM; 8x: 564.8 mM), and pH (pH4 or pH5) of the medium (M. Braaksma, A.K. Smilde, M.J. van der Werf, P.J. Punt, submitted for publication). At different time points samples were collected, quenched immediately in methanol at -45 ºC and centrifuged at -20 ºC to remove supernatant. Part of the biomass was frozen into liquid nitrogen and stored at -80 ºC for microarray analysis. For each of the 16 culture conditions one sample was selected for microarray analysis; samples were collected either around the time point carbon source depleted or a considerable time (~24 h) after carbon souce depletion. In addition some technical duplicates were included.
Project description:The Target of Rapamycin complex (TORC1) is an essential regulator of metabolism in eukaryotic cells and in the fungal pathogen C. albicans regulates morphogenesis and nitrogen acquisition. Gtr1 encodes a highly conserved GTPase which in S. cerevisiae regulates nitrogen sensing and TORC1 activation. Here, were characterize the role of C. albicans GTR1 in TORC1 activation and compare with the previously characterized GTPase Rhb1. A homozygous gtr1/gtr1 mutant exhibited impaired TORC1-mediated phosphorylation of Ribosomal Protein S6 and increased susceptibility to rapamycin. Overexpression of GTR1 impaired nitrogen starvation induced filamentous growth, MEP expression and growth in BSA as the sole nitrogen source. Both GTR1 and RHB1 were shown to regulate genes involved in ribosome biogenesis, amino acid biosynthesis and expression of biofilm-growth induced genes. The rhb1/rhb1 mutant exhibited a different pattern of expression of Sko1 regulated genes and increased susceptibility to Congo Red and Calcofluor white. The homozygous gtr1/gtr1 mutant exhibited enhanced flocculation phenotypes and similar to the rhb1/rhb1 mutant exhibited enhanced biofilm formation on plastic surfaces. In summary, Gtr1 and Rhb1 link nutrient sensing and biofilm formation and this connectivity may have evolved to enhance competitiveness of C. albicans in niches where there is intense competition with other microbes for space and nutrients.
Project description:Lysine lactylation as a type of posttranslational modifications (PTMs) is recently associated with chromatin remodeling and gene transcription, but lysine lactylation of histone and non-histone proteins has not yet been studied in Nannochloropsis oceanica. To examine the prevalence and function of lactylation in N. oceanica, protein lactylation modification profiles were tracked after nitrogen deprivation for three days using 4D label-free proteome method. Under nitrogen deprivation (ND) and nitrogen repletion (NR) cultivation conditions, we mapped lactylome of proliferating microalgal cells.
Project description:Corynebacterium glutamicum, a gram-positive soil bacterium used for the industrial production of amino acids such as L-glutamate and L-lysine, is able to use a number of different nitrogen sources, such as ammonium, urea, or creatinine. In this communication, we show that L-glutamine serves as an excellent nitrogen source for C. glutamicum and allows similar growth rates in glucose minimal medium as ammonium. A transcriptome comparison revealed a strong induction of the nitrogen starvation response when glutamine was used as nitrogen source. Subsequent growth experiments with a variety of mutants defective in nitrogen metabolism showed that glutamate synthase is crucial for glutamine utilization, while a putative glutaminase is dispensable under the experimental conditions used. The fact that the glutamate synthase encoding gltBD operon is under strict nitrogen control explains the necessity for induction of the nitrogen starvation response. The paradox situation that the nitrogen starvation response is induced although intracellular L-glutamine levels are high has implications on nitrogen sensing. In contrast to other gram-positive and gram-negative bacteria such as Bacillus subtilis, Salmonella typhimurium, and Klebsiella pneumoniae, a drop in glutamine concentration obviously does not serve as a nitrogen starvation signal in C. glutamicum.
Project description:ra05-09_urea - urea - What are the transcriptomic plant responses to urea nitrogen supply ? - Columbia Arabidopsis ecotype were grown hydroponically on 0.5 mM NH4NO3 as sole nitrogen source during 35 days under short days. Plants were then placed on 3 nutrient solutions supplemented, either with 1 mM NH4NO3, or with 0.5 mM NH4NO3 + 0.5 mM Urea, or with 1 mM Urea. Root and shoot samples were harvested separately 7 days after these different nitrogen treatments Keywords: treated vs untreated comparison