Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1000072 | ENA |
REPOSITORIES: ENA
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Project description:Desulfotomaculum reducens is the first Gram-positive sulfate- and metal- reducing bacterium for which the transcriptomic response to uranium exposure has been evaluated. The genes upregulated during fermentative growth in the presence of U(VI) as compared to its absence included those encoding for proteins involved in respiration such as NADH quinone oxidoreductase and heterodisulfide reductase. This finding suggested that electrons were shuttled to the electron transport chain during fermentation which points to the reduction of U(VI) as a metabolic process. While U(IV) is typically insoluble and readily removable by filtration, U(IV) produced during active growth was not retained by a 0.2 µm pore size filter and filtration was not sufficient to differentiate between U(VI) and U(IV). In addition, genes involved in iron homeostasis were upregulated in the presence of uranium, which was consistent with the upregulation of genes involved in c-type cytochrome biogenesis. Despite the upregulation of cytochrome biosynthesis genes, the sole c-type cytochrome encoded in the genome was not differentially expressed. Finally, genes encoding metal efflux pumps were also upregulated indicating the toxic nature of uranium. Analysis of the time-dependent gene expression showed that sporulation was the dominant process at the early stationary phase and that the presence of U at that stage did not impact expression. This data set is a time course comparing sulfate and uranium reduction with fermentative growth.
2010-07-15 | E-GEOD-22944 | biostudies-arrayexpress
Project description:Human cells require pH regulation to maintain physiological function, yet the molecular consequences of acidic environments remain incompletely understood. Here, we employ a gas-only bioreactor to control pH, oxygen, and temperature. Integrated Omics analyses reveal that acidic pH induces a glycolytic metabolic shift, suppresses proliferation, and promotes accumulation of lactate and oncometabolites alongside mitochondrial dysfunction. Acidic conditions increase reactive oxygen species (ROS) and activate inflammatory and immune pathways, leading to heteroplasmic enrichment of a pathogenic mitochondrial mutation. Acidic pH depletes intracellular NAD⁺, partly driven by PARP1 activation. Restoring NAD⁺ through nicotinamide mononucleotide (NMN) supplementation partially rescues proliferation and stress-associated transcription, while elevating NAD+ levels by NMN or PARP1 inhibition reverses heteroplasmic enrichment of mutant mitochondrial DNA. These findings underscore the role of pH homeostasis in coordinating metabolism, redox balance, and immune signaling, and identify NAD⁺ metabolism as a mechanistic link between acidic microenvironments, mitochondrial genome instability, and immune–metabolic remodeling.
2026-03-11 | GSE254130 | GEO
Project description:Acidification of groundwater co-occurring with nitrate pollution is a common, global environmental health hazard. Denitrifying bacteria have been leveraged for the in-situ removal of nitrate in groundwater. However, co-existing stressors—like low pH—reduce the efficacy of these biological removal processes. Castellaniella sp. str. MT123 is a complete denitrifier that was isolated from acidic, nitrate-contaminated groundwater. The strain grows robustly by nitrate respiration at pH < 6.0 while completely reducing nitrate to dinitrogen gas. Genomic analyses of MT123 revealed few previously characterized acid tolerance genes. Thus, we utilized a combination of proteomics, metabolomics, and competitive mutant fitness to characterize the genetic mechanisms of MT123 acclimation to growth under mildly acidic conditions. We found that glutamate accumulation is critical in the acid acclimation of MT123, likely through its decarboxylation to GABA. This is despite the fact that MT123 lacks the canonical glutamate decarboxylase-glutamate/GABA antiporter system implicated in acid tolerance in other bacteria. Additionally, branched chain amino acid (BCAA) appears to be detrimental to cell growth at lower pHs. Genetic analysis previously linked MT123 to a population of Castellaniella that bloomed—concurrent to nitrate removal—during a biostimulation effort to reduce groundwater nitrate concentrations at MT123’s location of origin. Thus, our analyses provide novel insight into mechanisms of acclimation to acidic conditions in a strain with significant potential for nitrate bioremediation.
2026-01-02 | PXD064015 | Pride
Project description:Mesophilic elemental sulfur reduction at neutral to acidic pH
| PRJEB50572 | ENA
Project description:As a successful commensal and pathogen of humans, Candida albicans encounters a wide range of environmental changes. Among them, ambient pH is an important factor, which changes frequently and affects many biological processes in this species. The ability to adapt to pH changes is tightly linked with pathogenesis and morphogenesis. In this study, we report that pH has a profound effect on white-opaque switching and sexual mating in C. albicans. Acidic pHs promote white-to-opaque switching but repress sexual mating of opaque cells. The cAMP signaling and Rim101-mediated pH sensing pathways are involved in the regulation of pH-regulated white-opaque switching. Interestingly, white and opaque cells of the cyr1/cyr1 mutant, which is defective in producing cAMP, show distinct growth defects under acidic and alkaline conditions. Phr2 could play a major role in acidic pHs-induced opaque cell formation. We further discover that acidic pH conditions repress sexual mating due to the failure of activation of the Ste2-mediated a-pheromone response pathway. The effects of pH changes on phenotypic switching and sexual mating could be a balance behavior between host adaptation and sexual reproduction.
2015-12-30 | GSE67101 | GEO
Project description:Abstract:
Despite intensive treatments including temozolomide (TMZ) administration, glioblastoma patient prognosis remains dismal and innovative therapeutic strategies are urgently needed. A systems pharmacology approach was undertaken to investigate TMZ pharmacokinetics‐pharmacodynamics (PK‐PD) incorporating the effect of local pH, tumor spatial configuration and micro‐environment. A hybrid mathematical framework was designed coupling ordinary differential equations describing the intracellular reactions, with a spatial cellular automaton to individualize the cells. A differential drug impact on tumor and healthy cells at constant extracellular pH was computationally demonstrated as TMZ‐induced DNA damage was larger in tumor cells as compared to normal cells due to less acidic intracellular pH in cancer cells. Optimality of TMZ efficacy defined as maximum difference between damage in tumor and healthy cells was reached for extracellular pH between 6.8 and 7.5. Next, TMZ PK‐PD in a solid tumor was demonstrated to highly depend on its spatial configuration as spread cancer cells or fragmented tumors presented higher TMZ‐induced damage as compared to compact tumor spheroid. Simulations highlighted that smaller tumors were less acidic than bigger ones allowing for faster TMZ activation and their closer distance to blood capillaries allowed for better drug penetration. For model parameters corresponding to U87 glioma cells, inter‐cell variability in TMZ uptake play no role regarding the mean drug‐induced damage in the whole cell population whereas this quantity was increased by inter‐cell variability in TMZ efflux which was thus a disadvantage in terms of drug resistance. Overall, this study revealed pH as a new potential target to significantly improve TMZ antitumor efficacy.
Change the value of pH for different cases.
2019-09-30 | MODEL1909300003 | BioModels
Project description:Since VirS was shown to be upregulated in acidic conditions and MtbΔvirS displayed defect in growth at pH4.5, we performed microarray at pH 6.6 and pH 4.5 to study the role of VirS in regulating gene expression at acidic pH.
2019-05-23 | GSE118508 | GEO