Redox Reactions in Lipid Membranes as a Model for Primordial Energy-Conserving Systems

1997 ◽  
Vol 161 ◽  
pp. 437-442
Author(s):  
Salvatore Di Bernardo ◽  
Romana Fato ◽  
Giorgio Lenaz
Keyword(s):  
Experimental Evidence ◽  
Lipid Membranes ◽  
Energy Supply ◽  
Redox Reactions ◽  
Living Systems ◽  
Asymmetric Distribution ◽  
Conservation Of Energy ◽  
Asymmetrical Distribution ◽  
Energy Conserving ◽  
Living Organisms

AbstractOne of the peculiar aspects of living systems is the production and conservation of energy. This aspect is provided by specialized organelles, such as the mitochondria and chloroplasts, in developed living organisms. In primordial systems lacking specialized enzymatic complexes the energy supply was probably bound to the generation and maintenance of an asymmetric distribution of charged molecules in compartmentalized systems. On the basis of experimental evidence, we suggest that lipophilic quinones were involved in the generation of this asymmetrical distribution of charges through vectorial redox reactions across lipid membranes.

Phosphorus mobilization in lake sediments: Experimental evidence of strong control by iron and negligible influences of manganese redox reactions

2019 ◽  
Vol 246 ◽  
pp. 472-481 ◽  
Author(s):  
Musong Chen ◽  
Shiming Ding ◽  
Yuexia Wu ◽  
Xianfang Fan ◽  
Zengfeng Jin ◽  
...  
Keyword(s):  
Experimental Evidence ◽  
Lake Sediments ◽  
Redox Reactions ◽  
Strong Control

scholarly journals Numerical Development and Evaluation of an Energy Conserving Conceptual Stochastic Climate Model

2019 ◽  
Vol 5 (1) ◽  
pp. 45-64 ◽  
Author(s):  
Federica Gugole ◽  
Christian L. E. Franzke
Keyword(s):  
Energy Conservation ◽  
Total Energy ◽  
Prediction Models ◽  
Climate Model ◽  
Empirical Orthogonal Functions ◽  
Correlated Noise ◽  
Spatial Covariance ◽  
Conservation Of Energy ◽  
Stochastic Climate Model ◽  
Energy Conserving

AbstractIn this study we aim to present the successful development of an energy conserving conceptual stochastic climate model based on the inviscid 2-layer Quasi-Geostrophic (QG) equations. The stochastic terms have been systematically derived and introduced in such away that the total energy is conserved. In this proof of concept studywe give particular emphasis to the numerical aspects of energy conservation in a highdimensional complex stochastic system andwe analyzewhat kind of assumptions regarding the noise should be considered in order to obtain physical meaningful results. Our results show that the stochastic model conserves energy to an accuracy of about 0.5% of the total energy; this level of accuracy is not affected by the introduction of the noise, but is mainly due to the level of accuracy of the deterministic discretization of the QG model. Furthermore, our results demonstrate that spatially correlated noise is necessary for the conservation of energy and the preservation of important statistical properties, while using spatially uncorrelated noise violates energy conservation and gives unphysical results. A dynamically consistent spatial covariance structure is determined through Empirical Orthogonal Functions (EOFs). We find that only a small number of EOFs is needed to get good results with respect to energy conservation, autocorrelation functions, PDFs and eddy length scale when comparing a deterministic control simulation on a 512 × 512 grid to a stochastic simulation on a 128 × 128 grid. Our stochastic approach has the potential to seamlessly be implemented in comprehensive weather and climate prediction models.

scholarly journals D-Serine in Neurobiology: CNS Neurotransmission and Neuromodulation

2014 ◽  
Vol 41 (2) ◽  
pp. 164-176 ◽  
Author(s):  
Sanaa K. Bardaweel ◽  
Muhammed Alzweiri ◽  
Aman A. Ishaqat
Keyword(s):  
Amino Acids ◽  
Central Nervous System ◽  
Human Physiology ◽  
Nervous System ◽  
Living Systems ◽  
Cns Development ◽  
Human Central Nervous System ◽  
High Affinity ◽  
Aspartate Receptor ◽  
Living Organisms

Homochirality is fundamental for life. L-Amino acids are exclusively used as substrates for the polymerization and formation of peptides and proteins in living systems. However, D- amino acids were recently detected in various living organisms, including mammals. Of these D-amino acids, D-serine has been most extensively studied. D-Serine was found to play an important role as a neurotransmitter in the human central nervous system (CNS) by binding to the N-methyl- D-aspartate receptor (NMDAr). D-Serine binds with high affinity to a co-agonist site at the NMDAr and, along with glutamate, mediates several vital physiological and pathological processes, including NMDAr transmission, synaptic plasticity and neurotoxicity. Therefore, a key role for D-serine as a determinant of NMDAr mediated neurotransmission in mammalian CNS has been suggested. In this context, we review the known functions of D-serine in human physiology, such as CNS development, and pathology, such as neuro-psychiatric and neurodegenerative diseases related to NMDAr dysfunction.

scholarly journals Equations of Atmospheric Motion in Non-Eulerian Vertical Coordinates: Vector-Invariant Form and Quasi-Hamiltonian Formulation

2014 ◽  
Vol 142 (10) ◽  
pp. 3860-3880 ◽  
Author(s):  
Thomas Dubos ◽  
Marine Tort
Keyword(s):  
Hamiltonian Formulation ◽  
Point Of View ◽  
Momentum Balance ◽  
Hamiltonian Form ◽  
Conservation Of Energy ◽  
Vertical Coordinate ◽  
Vertical Displacements ◽  
Energy Conserving ◽  
Atmospheric Motion ◽  
Hydrostatic Balance

Abstract The curl form of equations of inviscid atmospheric motion in general non-Eulerian coordinates is obtained. Narrowing down to a general vertical coordinate, a quasi-Hamiltonian form is then obtained in a Lagrangian, isentropic, mass-based or z-based vertical coordinate. In non-Lagrangian vertical coordinates, the conservation of energy by the vertical transport terms results from the invariance of energy under the vertical relabeling of fluid parcels. A complete or partial separation between the horizontal and vertical dynamics is achieved, except in the Eulerian case. The horizontal–vertical separation is especially helpful for (quasi-)hydrostatic systems characterized by vanishing vertical momentum. Indeed for such systems vertical momentum balance reduces to a simple statement: total energy is stationary with respect to adiabatic vertical displacements of fluid parcels. From this point of view the purpose of (quasi-)hydrostatic balance is to determine the vertical positions of fluid parcels, for which no evolution equation is readily available. This physically appealing formulation significantly extends previous work. The general formalism is exemplified for the fully compressible Euler equations in a Lagrangian vertical coordinate and a Cartesian (x, z) slice geometry, and the deep-atmosphere quasi-hydrostatic equations in latitude–longitude horizontal coordinates. The latter case, in particular, illuminates how the apparent intricacy of the time-dependent metric terms and of the additional forces can be absorbed into a proper choice of prognostic variables. In both cases it is shown how the quasi-Hamiltonian form leads straightforwardly to the conservation of energy using only integration by parts. Relationships with previous work and implications for stability analysis and the derivation of approximate sets of equations and energy-conserving numerical schemes are discussed.

scholarly journals Poetic Objectivity

2018 ◽  
Vol 37 (3-4) ◽  
pp. 55-70
Author(s):  
Andreas Weber
Keyword(s):  
The Other ◽  
Living Systems ◽  
Self Healing ◽  
Ecological Ethics ◽  
Ethical Thinking ◽  
Living Organisms ◽  
Meaningful Relationships

In this essay I will explore the possibility of an objective ecological ethics. To do this, I follow the embodied ethos of relationships: meaningful expression and mutual sharing occuring in living organisms and systems. Living beings on various levels of identity (cellular selves, individuals, and ecosystems) strive toward increased aliveness. They are self-healing, and generate meaningful relationships, all without the need or interference of human ethical thinking. Ecosystems tend toward complexity and organisms tend to avoid their own destruction. Both tendencies create “natural values” – values not extractable into abstraction, yet nonetheless fundamentally embodied in the actions of living beings and living systems. An ethics based on these principles (or insights) is inclusive in that it can be conceived as a sort of “poetic objectivity”. Here the ethically good is the increase in “aliveness”, which can be shared by other beings, and which is only possible as “being through the other”. Aliveness is ineffable and cannot be extracted analytically. Hence it is objective only in a poetic sense that can be shared through participation. An ethics of poetic objectivity leaves room to negotiate individual relationships and narratives while providing goodness as an encompassing context tuning into the degree of sharing and mutual inspiration to be more alive. The natural values generated by sharing transformative relationships produce the whole of nature as an “ethical commons”. Its principles can be instructive in reorganising human exchange on ethical and economical levels.

scholarly journals A subcellular proteome atlas of the yeast Komagataella phaffii

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Minoska Valli ◽  
Karlheinz Grillitsch ◽  
Clemens Grünwald-Gruber ◽  
Nadine E Tatto ◽  
Bernhard Hrobath ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Ionization Mass ◽  
Heterologous Proteins ◽  
Regulatory Pathways ◽  
Komagataella Phaffii ◽  
Tandem Mass Tag ◽  
Interactive Map ◽  
Living Organisms ◽  
Cellular Compartments

ABSTRACT The compartmentalization of metabolic and regulatory pathways is a common pattern of living organisms. Eukaryotic cells are subdivided into several organelles enclosed by lipid membranes. Organelle proteomes define their functions. Yeasts, as simple eukaryotic single cell organisms, are valuable models for higher eukaryotes and frequently used for biotechnological applications. While the subcellular distribution of proteins is well studied in Saccharomyces cerevisiae, this is not the case for other yeasts like Komagataella phaffii (syn. Pichia pastoris). Different to most well-studied yeasts, K. phaffii can grow on methanol, which provides specific features for production of heterologous proteins and as a model for peroxisome biology. We isolated microsomes, very early Golgi, early Golgi, plasma membrane, vacuole, cytosol, peroxisomes and mitochondria of K. phaffii from glucose- and methanol-grown cultures, quantified their proteomes by liquid chromatography-electrospray ionization-mass spectrometry of either unlabeled or tandem mass tag-labeled samples. Classification of the proteins by their relative enrichment, allowed the separation of enriched proteins from potential contaminants in all cellular compartments except the peroxisomes. We discuss differences to S. cerevisiae, outline organelle specific findings and the major metabolic pathways and provide an interactive map of the subcellular localization of proteins in K. phaffii.

Mechanisms of Action of Nanoparticles in Living Systems

2018 ◽  
pp. 220-236 ◽  
Author(s):  
Madhu Rawat ◽  
Yadukrishnan P. ◽  
Nitin Kumar
Keyword(s):  
Antimicrobial Activity ◽  
Plant Growth ◽  
Mechanism Of Action ◽  
Plant Growth Promotion ◽  
Mode Of Action ◽  
Growth Promotion ◽  
Mechanisms Of Action ◽  
Living Systems ◽  
Research Application ◽  
Living Organisms

Nanoparticles are being formed continuously in processes like mineralization, natural calamities, and geological recycling of matter and present naturally in the environment. In the recent past, nanoparticles and their applications have become an extensive topic of research. Application of nanomaterials in different industries will surely enhance the chances of discharge of nanoparticles into the environment. So, a number of studies have been performed to explore the mode of action of nanoparticles on living organisms and their surroundings. The most reported modes of action of nanoparticles are antimicrobial activity, ROS-induced cytotoxicity, genotoxicity, plant growth promotion, etc. It has been successfully demonstrated that actions of nanoparticles are governed by their size, shape, dose, and concentration. However, a complete mechanism of action of nanoparticles has not been known. The present chapter focuses on the highlights of the mechanisms behind the mode of action of nanoparticles in plants and microorganisms.

Random searchers cope with cognitive errors and uncertainty better than path planners

2020 ◽  
Author(s):  
Daniel Campos ◽  
Vicenç Méndez ◽  
John Palmer ◽  
Javier Cristín ◽  
Frederic Bartumeus
Keyword(s):  
Living Systems ◽  
Search Efficiency ◽  
Cognitive Errors ◽  
External Effects ◽  
Computer Screen ◽  
Random Walkers ◽  
Widespread Belief ◽  
Living Organisms ◽  
Better Than ◽  
Soccer Field

AbstractThere is a widespread belief in ecology that the capacity of animals to orchestrate systematic and planned paths should represent a significant benefit for efficient search and exploration. Within this view, stochasticity observed in real animal trajectories is mostly understood as undesirable noise caused by internal or external effects. Far less is known, however, about the case when cognitive errors and limitations inherent to living systems are explicitly put into play. Here we compare within this context the search efficiency of (i) walkers driven by Bayesian rules generating deterministic paths, (ii) standard random walkers, and (iii) human trajectories obtained from search experiments in a soccer field and on the computer screen. Our results clearly challenge the view that deterministic paths are generally better for exploration than random strategies, as the latter are more resilient to cognitive errors. Instead, we provide numerical and experimental evidence that stochasticity would provide living organisms with a sufficient and cognitively simple exploration solution to the problem of uncertainty.

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