Project description:Microarray analyses were performed on Wildtype Mycobacterium smegmatis and MSMEG_1918 gene knockout (ΔpdtaS) grown in two different carbon sources, glucose and glycerol.
Project description:The purpose of this study was to examine how Mtb integrates acidic pH and available carbon sources as environmental cues to regulate its metabolism and growth rate. RNA-seq transcriptional profiling of M. tuberculosis growing at acidic or neutral pH, in pyruvate or glycerol, was examined. These studies identified carbon source-dependent and -independent pH-dependent adaptations.
Project description:The unicellular microalga Dunaliella salina is one of the halotolerant and cell wall-less green microalgae in Dunaliella genus. The ability of halotolerance in Dunaliella is attributed to the accumulation of glycerol. Both sugar made by photosynthesis and starch serve as carbon sources for glycerol biosynthesis. Quantitative PCR-based analyses concluded no apparent transcriptional regulation of glycerol, carbon fixation, and starch metabolisms upon salinity stresses. To examine whether or not transcriptional regulation is involved at the transcriptomic level, we assembled a de novo deep sequencing transcriptome. By using a pathway-based approach, we show that low- and high-salt (i.e., 0.5M versus 2M NaCl) adapted cells share a common transcriptomic profile and that subsets of ESTs associated with energy metabolisms are less affected upon salinity stress. We find that enzymes involved in glycerol, carbon fixation, and starch metabolisms are encoded by multiple EST isoforms. We show that EST isoforms encoding dihydroacetone reductase in glycerol metabolism, phosphoglycerate kinase in carbon fixation, and beta-amylase and fructobiphosphate aldolase in starch metabolism display a correlated transcriptional level change to the alteration of glycerol and starch contents upon salinity stresses. Taken together, our results demonstrate that some enzymes involved in glycerol, carbon fixation, and starch metabolisms are regulated at the transcriptional level upon salinity stresses. Furthermore, our analyses indicate that energy metabolisms are not drastically affected upon salinity stresses, consistent with its ability to adapt to a wide range of salinities.
Project description:Transcriptome analyses using a wild-type strain of Saccharomyces cerevisiae were performed to assess the overall pattern of gene expression during the transition from glucose-based fermentative to glycerol-based respiratory growth. These experiments revealed a complex suite of metabolic and structural changes associated with the adaptation process. Alterations in gene expression leading to remodeling of various membrane transport systems and the cortical actin cytoskeleton were observed. Transition to respiratory growth was accompanied by alterations in transcript patterns demonstrating not only a general stress response, as seen in earlier studies, but also the oxidative and osmotic stress responses. In some contrast to earlier studies, these experiments identified modulation of expression for many genes specifying transcription factors during the transition to glycerol-based growth. Importantly and unexpectedly, an ordered series of changes was seen in transcript levels from genes encoding components of the TFIID, SAGA (Spt-Ada-Gcn5-Acetyltransferase), and SLIK (Saga LIKe) complexes and all three RNA polymerases, suggesting a modulation of structure for the basal transcriptional machinery during adaptation to respiratory growth. In concert with data given in earlier studies, the results presented here highlight important aspects of metabolic and other adaptations to respiratory growth in yeast that are common to utilization of multiple carbon sources. Importantly, they also identify aspects specific to adaptation of this organism to growth on glycerol as sole carbon source. A time-series illustrating the transition from fermentation using glucose (dextrose) as sole carbon source to respiration using glycerol as sole carbon source. Time points of 15 minutes, 30 minutes and 60 minutes as well as growth on dextrose, glycerol or ethanol as sole carbon source from a starter culture. Three biological replicates of the 30 minute time point and growth on glycerol from starter culture.
