Project description:Nitrogen fixation is an important metabolic process carried out by microorganisms, which converts molecular nitrogen into inorganic nitrogenous compounds such as ammonia (NH3). These nitrogenous compounds are crucial for biogeochemical cycles and for the synthesis of essential biomolecules, i.e. nucleic acids, amino acids and proteins. Azotobacter vinelandii is a bacterial non-photosynthetic model organism to study aerobic nitrogen fixation (diazotrophy) and hydrogen production. Moreover, the diazotroph can produce biopolymers like alginate and polyhydroxybutyrate (PHB) that have important industrial applications. However, many metabolic processes such as partitioning of carbon and nitrogen metabolism in A. vinelandii remain unknown to date.
Genome-scale metabolic models (M-models) represent reliable tools to unravel and optimize metabolic functions at genome-scale. M-models are mathematical representations that contain information about genes, reactions, metabolites and their associations. M-models can simulate optimal reaction fluxes under a wide variety of conditions using experimentally determined constraints. Here we report on the development of a M-model of the wild type bacterium A. vinelandii DJ (iDT1278) which consists of 2,003 metabolites, 2,469 reactions, and 1,278 genes. We validated the model using high-throughput phenotypic and physiological data, testing 180 carbon sources and 95 nitrogen sources. iDT1278 was able to achieve an accuracy of 89% and 91% for growth with carbon sources and nitrogen source, respectively. This comprehensive M-model will help to comprehend metabolic processes associated with nitrogen fixation, ammonium assimilation, and production of organic nitrogen in an environmentally important microorganism.
Project description:The aim of this study was to extend our analysis to the obligate human pathogen M. tuberculosis, which has to deal with a more restricted set of environmental variables in terms of nitrogen sources, and to delineate the GlnR regulon, by peforming global analysis of GlnR-DNA interactions by Chromatin Immunoprecipitation and high-throughput sequencing (ChIP-seq) over nitrogen run-out.
Project description:We developed a general approach to small molecule library screening called GE-HTS (Gene Expression-Based High Throughput Screening) in which a gene expression signature is used as a surrogate for cellular states and applied it to the identification of compounds inducing the differentiation of acute myeloid leukemia cells. In screening 1,739 compounds, we identified 8 that reliably induced the differentiation signature, and furthermore yielded functional evidence of bona fide differentiation. This SuperSeries is composed of the following subset Series:; GSE976: Gene Expression-Based High Throughput Screening: APL Treatment with Candidate Compounds; GSE982: Gene Expression-Based High Throughput Screening: HL-60 Cell Treatment with Candidate Compounds; GSE983: Gene Expression-Based High Throughput Screening: Primary Patient AML Blasts, Normal Neutrophils, and Normal Monocytes; GSE985: Gene Expression-Based High Throughput Screening: HL-60 Cells Treated with ATRA and PMA Experiment Overall Design: Refer to individual Series
Project description:High-temperature fermentation of the Bacillus subtilis isolated from the black part of maotai Daqu. Studying on the gene expression profile using microarray for analyzing the connection between metabolites and the maotai flavor substances. 84 differential expressed genes were obtained, including 40 up-regulated genes and 44 down-regulated genes.The differentially expressed genes involved in the metabolic pathways were just only KBL (glycine C - acetyltransferase) and ripA (bifunctional 3, 4 - dihydroxy - 4-2 - butanone phosphate synthase), up-regulated 2.9 and 2.9 times respectively, and their catalytic reaction prodction of aminobutyric acid and dihydroxy ethyl ketone phosphate, respectively. They may be further derived into alcohol and ketone flavoring substances. However, a large number of differential expressed genes was related to sporulation, such as ybaN (polysaccharide deacetylase) and rapA (aspartic acid phosphatase), they were up-regulated 17.5 times and down-regulated 112.5 times. YbaN is closely related to the formation of spore cortex and high temperature group spore cortex obvious thickening by TEM. RapA is signaling molecules to restrain spore formation, its lower expression can promote the sporulation in group A. Formation and release of peptidoglycan and the DPA (2, 6 - Pyridinedicarboxylic acid) of spore cortex during theseveral rounds of low temperature to high temperature circulation fermentation may be the main source of furan and pyranand nitrogen heterocyclic compounds in maotai flavor substances . In this paper, the formation of high-temperature fermentation Bacillus subtilis spores is closely related to the generation of maotai flavor substances. There are total of eight samples. It divided two groups, set as group A (High temperature fermentation) and B (normal temperature fermentation, continuous 37C). There are four replicates for each group.