M. Koivusalo, Christopher M. Welch, H. Hayashi
et al.
Inhibitors of Na+/H+ exchange proteins block macropinocytosis by lowering the pH near the plasma membrane, which in turn inhibits actin remodeling by Rho family GTPases.
BackgroundOxidation-reduction and acid–base reactions are essential for the maintenance of all living organisms. However, redox potential (Eh) has received little attention in agronomy, unlike pH, which is regarded as a master variable. Agronomists are probably depriving themselves of a key factor in crop and soil science which could be a useful integrative tool.ScopeThis paper reviews the existing literature on Eh in various disciplines connected to agronomy, whether associated or not with pH, and then integrates this knowledge within a composite framework.ConclusionsThis transdisciplinary review offers evidence that Eh and pH are respectively and jointly major drivers of soil/plant/microorganism systems. Information on the roles of Eh and pH in plant and microorganism physiology and in soil genesis converges to form an operational framework for further studies of soil/plant/microorganism functioning. This framework is based on the hypothesis that plants physiologically function within a specific internal Eh-pH range and that, along with microorganisms, they alter Eh and pH in the rhizosphere to ensure homeostasis at the cell level. This new perspective could help in bridging several disciplines related to agronomy, and across micro and macro-scales. It should help to improve cropping systems design and management, in conventional, organic, and conservation agriculture.
Mitochondria have a central role in ageing. They are considered to be both a target of the ageing process and a contributor to it. Alterations in mitochondrial structure and function are evident during ageing in most eukaryotes, but how this occurs is poorly understood. Here we identify a functional link between the lysosome-like vacuole and mitochondria in Saccharomyces cerevisiae, and show that mitochondrial dysfunction in replicatively aged yeast arises from altered vacuolar pH. We found that vacuolar acidity declines during the early asymmetric divisions of a mother cell, and that preventing this decline suppresses mitochondrial dysfunction and extends lifespan. Surprisingly, changes in vacuolar pH do not limit mitochondrial function by disrupting vacuolar protein degradation, but rather by reducing pH-dependent amino acid storage in the vacuolar lumen. We also found that calorie restriction promotes lifespan extension at least in part by increasing vacuolar acidity via conserved nutrient-sensing pathways. Interestingly, although vacuolar acidity is reduced in aged mother cells, acidic vacuoles are regenerated in newborn daughters, coinciding with daughter cells having a renewed lifespan potential. Overall, our results identify vacuolar pH as a critical regulator of ageing and mitochondrial function, and outline a potentially conserved mechanism by which calorie restriction delays the ageing process. Because the functions of the vacuole are highly conserved throughout evolution, we propose that lysosomal pH may modulate mitochondrial function and lifespan in other eukaryotic cells.
Meen-Wah Gui, Hsin-An Chu, Ming-Chien Chung
et al.
After a series of rainfall-related slope incidents that threatened immediately protected entities, the Taipei City government initiated a slope deformation monitoring and investigation program for potential landslides in its administrative districts and a review of its current rainfall thresholds for landslide occurrences, which is the aim of this study, in 2021 for better preparedness in facing the extreme weather- and climate-related natural hazards. Due to the limited availability of historical data, this study employed a physically based method to derive rainfall thresholds for landslide occurrences by integrating different rainfall distribution patterns into infiltration and slope stability analyses. The study examined four rainfall patterns—uniform, intermediate, advanced, and delayed—to assess their impact on slope failure mechanisms. Results indicate that advanced rainfall patterns (where peak rainfall occurs early) trigger the fastest failures, while delayed rainfall patterns lead to gradual groundwater accumulation, causing slope destabilization over longer durations. The study also found that short-duration rainfall (24 h) mainly triggers shallow landslides, whereas prolonged rainfall (72 h) leads to deep landslides. The study’s findings are crucial for early landslide warning systems, which provide different mitigation strategies based on the expected rainfall duration and provide a scientific basis for authorities to revise and integrate new rainfall thresholds into their real-time landslide warning systems.
We develop a discrete-event modeling framework that captures the progression of geophysical systems toward catastrophic failure through sequences of distinct damage events. By representing system evolution as a succession of temporally accelerating and amplitude-varying events, the framework reveals how finite-time singularities, both logarithmic and power law types, naturally emerge from the interplay between shrinking interevent intervals and growing event magnitudes. This event-based perspective provides an intuitive physical understanding of rupture processes, highlighting how precursory signals such as accelerating strain rate, event frequency, and energy release can be traced back to simple underlying mechanisms. A mean-field formulation further links the observed power law exponents to the evolving stiffness of the system under constant or time-varying stress. Incorporating stochastic fluctuations, the model captures the inherent randomness of natural systems leading to the emergence of stochastic finite-time singular behavior. Altogether, this unified approach offers a simple conceptual and quantitative tool for interpreting the lead-up to failure in a wide range of geophysical settings.
In this brief paper, we analyze space weather events that occurred on May 11 and 12, 2024, from the perspective of an operational space weather center that provides advisories for civil aviation. One of the key metrics monitored by the center is the radiation dose rate at operational flight altitudes. A model implemented by the center provides the dose rate in real time. The model showed that dangerous levels were momentarily exceeded just above the usual 30,000 feet level during the events. This paper highlights differences in models used by various space weather centers, emphasizing the need for harmonization.
This paper delivers a software -- libEMM -- for 3D controlled-source electromagnetics (CSEM) modelling in fictitious wave domain, based on the newly developed high-order finite-difference time-domain (FDTD) method on non-uniform grid. The numerical simulation can be carried out over a number of parallel processors using MPI-based high performance computing architecture. The FDTD kernel coded in C has been parallelized with OpenMP for speedup using local shared memory. In addition, the software features a GPU implementation of the same algorithm based on CUDA programming language, which can be cross-validated and compared in terms of efficiency. A perspective of libEMM on the horizon is its application to 3D CSEM inversion in land and marine environment.