Concept

Amphibolic

Publications associées (13)

Why do life phenomena not violate the second law of thermodynamics?

For many people, the reconciliation of Life with the Second Law of Thermodynamics remains a mystery. This law says that nothing in the universe will happen spontaneously without the generation of entropy. This function measures how many microstates are accessible to the system and may thus be interpreted in a simplified way as disorganization, or “messiness” of the system. The spontaneous increase of messiness may be easy to understand when considering avalanches thundering down mountains, or buildings coll

2026

An mTOR paradox in sarcopenia via BCAA catabolism: Skeletal muscle aging

Dietary proteins stimulate skeletal muscle growth via mTOR-mediated activation of muscle protein synthesis by amino acids. Zuo and colleagues identify impaired mitochondrial branched-chain amino acid (BCAA) catabolism during sarcopenia. Pathological BCAA accumulation in aged muscle overactivates mTOR and paradoxically contributes to loss of muscle mass and strength by inhibiting autophagy and mitochondrial function.

2025

Daily liver rhythms: Coupling morphological and molecular oscillations

Felix Naef

In mammals, a hierarchically organized circadian timing system orchestrates daily rhythms of nearly all physiology. A master pacemaker in the brain’s suprachiasmatic nucleus (SCN) synchronizes subsidiary clocks in most peripheral organs. By driving anabolic and catabolic cycles of proteins, lipids, and carbohydrates and by detoxifying endo- and xenobiotic components, the liver plays an important role in adapting the metabolic needs to rest-activity rhythms. In keeping with these functions, the liver express

Proceedings of the National Academy of Sciences2025

Self-Assembled Molecular Rafts at Liquid|Liquid Interfaces for Four-Electron Oxygen Reduction

Hubert Girault, Hirohisa Nagatani

The self-assembly of the oppositely charged watersoluble porphyrins, cobalt tetramethylpyridinium porphyrin (CoTMPyP4+) and cobalt tetrasulphonatophenyl porphyrin (CoTPPS4−), at the interface with an organic solvent to form molecular “rafts”, provides an excellent catalyst to perform the interfacial four-electron reduction of oxygen by lipophilic electron donors such as tetrathiafulvalene (TTF). The catalytic activity and selectivity of the self-assembled catalyst toward the four-electron pathway was found

2012

Influence of residual ethanol concentration on the growth of Gluconacetobacter xylinus I 2281

Urs von Stockar, Henri Kornmann

The influence of residual ethanol on metab. of food grade Gluconacetobacter xylinum I 2281 was investigated during controlled cultivations on 35 g/l glucose and 5 g/l ethanol. Bacterial growth was strongly reduced in the presence of ethanol, which is unusual for acetic acid bacteria. Biomass accumulated only after complete oxidn. of ethanol to acetate and carbon dioxide. In contrast, bacterial growth initiated without delay on 35 g/l glucose and 5 g/l acetate. It was found that acetyl CoA was activated by t

Springer-Verlag2003

Quantitative comparison of transient growth of Saccharomyces cerevisiae, Saccharomyces kluyveri, and Kluyveromyces lactis

Urs von Stockar, Christoph Herwig

A multitude of metabolic regulations occur in yeast, particularly under dynamic process conditions, such as under sudden glucose excess. However, quantification of regulations and classification of yeast strains under these conditions have yet to be elucidated, which requires high-frequency and consistent quantification of the metabolic response. The present study aimed at quantifying the dynamic regulation of the central metab. of strains Saccharomyces cerevisiae, S. kluyveri, and Kluyveromyces lactis upon

2003

Quantitative analysis of the impact of HXK2 and REG1 deletion in Saccharomyces cerevisiae on invertase expression and respiration

Urs von Stockar, Christoph Herwig

In Saccharomyces cerevisiae, the genes HXK2 and REG1 are believed to play a central role in carbon catabolite repression, acting on multiple pathways in the central metab. The present study aimed at quantifying the effect of deletion of genes HXK2 or REG1, resp., in the S. cerevisiae strain CEN.PK113-7D on the regulation of invertase and respiratory functions.Batch cultivation of the HXK2 deletion mutant on substrate mixts. of sucrose, fructose and glucose and on pure glucose showed an initial high invertas

2002

Quantitative analysis of the oxidative metabolism in HXK2- and REG1-deletion mutants of Saccharomyces cerevisiae

Urs von Stockar, Christoph Herwig

Deletion mutants with either deletion of HXK2 and REG1 of the wild-type strain Saccharomyces cerevisiae CEN.PK113-7D were quant. analyzed for the impact on carbon catabolite repression and the short-term effect of the oxidative metab. Therefore, continuous cultures and transient expts. were performed, which were followed by high frequency online anal. of multiple compds.It could be demonstrated that either deletion of HXK2 or REG1 alleviated repression of respiratory functions in steady state conditions. Th

2002

Thermodynamic analysis of growth of Methanobacterium thermoautotrophicum

Urs von Stockar

Growth of Methanobacterium thermoautotrophicum, an anaerobic archaebacterium using methanogenesis as the catabolic pathway, is characterized by large heat prodn. rates, up to 13 W g-1, and low biomass yields, in the order of 0.02 C-mol mol-1 H2 consumed. These values, indicating a possibly "inefficient" growth mechanism, warrant a thermodn. anal. to obtain a better understanding of the growth process. The growth-assocd. heat prodn. (DrHX0,min) and the growth-assocd. Gibbs energy dissipation per mol biomas

1999

Metabolic network analysis of a hybridoma cell line using mass balances and 14C-labeled glucose and glutamine

Urs von Stockar, Ian William Marison

Continuous cultures of a hybridoma cell line (Zac3) were performed with 2 14C-labeled substrates: glucose and glutamine. A simplified network was used to describe cell metab. This simple network gave a good idea of the main fluxes into the cell, esp. for catabolic reactions. The use of 14C-labeled glucose and glutamine enabled the metabolic routes to be described with great accuracy, esp. CO2 prodn. rate. [on SciFinder (R)]

1998

Calorimetric and stoichiometric analysis of growth of Kluyveromyces fragilis in continuous culture. Nitrogen limitation imposed upon carbon-limited growth

Urs von Stockar, Ian William Marison

The calorimetric response of the yeast Kluyveromyes fragilis was investigated for growth in continuous culture where N limitation was imposed on a C-limited culture. Calorimetric measurements were combined with off gas anal., measurements of biomass, substrate and product concns., elemental biomass compn., and heat prodn. to study the physiol. response of K. fragilis. Regions where both carbon and nitrogen limited growth, were found over a broad range of diln. rates and feed carbon-to-nitrogen ratios. The p

1996

Calorimetry and energetic efficiencies in aerobic and anaerobic microbial growth

Urs von Stockar, Ian William Marison

A simple definition of the energetic growth efficiency both in terms of enthalpy and free energy is given and discussed. In cultures growing by respiratory catabolism, these efficiencies may conveniently be obsd. online by isothermal reaction calorimetry. If the fermentative part of catabolism is important, the free energy growth efficiency must be evaluated based on biomass yield measurements. In continuous cultures of 2 yeasts growing by respiration, by pure fermn., and on a mixed catabolism, the efficien

1993

The heat generated by yeast cultures with a mixed metabolism in the transition between respiration and fermentation

Urs von Stockar

The heat generated by both batch and continuous cultures of the yeast Kluyveromycs fragilis was studied using a modified bench scale calorimeter. Batch cultures were used to measure the heat dissipation rates and the heat yields during fully aerobic and completely anaerobic growth, whereas continuous cultures also allowed a quant. study of heat dissipation rates during growth on mixed metab. The extent of fermn. vs. respiration could be specified and controlled by O2 limitation. The heat dissipated per unit

1989

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Publications associées (13)

Quantitative comparison of transient growth of Saccharomyces cerevisiae, Saccharomyces kluyveri, and Kluyveromyces lactis

Urs von Stockar, Christoph Herwig

2003

Quantitative analysis of the impact of HXK2 and REG1 deletion in Saccharomyces cerevisiae on invertase expression and respiration

Urs von Stockar, Christoph Herwig

2002

Calorimetric and stoichiometric analysis of growth of Kluyveromyces fragilis in continuous culture. Nitrogen limitation imposed upon carbon-limited growth

Urs von Stockar, Ian William Marison

1996

Calorimetry and energetic efficiencies in aerobic and anaerobic microbial growth

Urs von Stockar, Ian William Marison

1993

The heat generated by yeast cultures with a mixed metabolism in the transition between respiration and fermentation

Urs von Stockar

1989