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The SEM‐2 (Space Environment Monitor‐2) instrument embedded on the NOAA‐15 Low Earth Orbit satellite provides measurements of trapped protons in the Van Allen inner belt from 1998 to nowadays. This continuous set of measurements enables us to study the dynamics of the South Atlantic Anomaly (SAA) over more than two solar cycles, particularly, its temporal evolution. We observe that the area of the SAA is anti‐correlated with the solar activity. Two physical processes explain this anticorrelation. First, the more the Sun is active the more it disables the cosmic rays to reach the Earth's magnetosphere and fill in the inner radiation belt with protons. Then, when the Sun is more active, the upper atmosphere is warmer and therefore absorbs more protons from the radiation belt. Then, we investigate the protons flux centroid of the SAA. The temporal evolution of its position, latitude and, longitude is studied over the same time interval (1998–2022). We notice that the latitude of the centroid is also anti‐correlated with the solar activity whereas the longitude seems absolutely independent. The temporal evolution of the position of the centroid shows a drift of the SAA. Indeed from 1998 to 2022 the SAA drifted of about 7° West. The SEM‐2 instrument measures flux for protons of different energies (16, 36, 70, and, 140 MeV). For each energy, the SAA dynamic has a similar trend but with different values. These differences are investigated and the results are discussed. Key Points: The SAA is studied from proton flux measurements values in the inner radiation belt collected during the 1998–2022 period by the SEM‐2 instrument embedded on the NOAA‐15 satelliteThe SAA drifts globally Northward with an anticorrelation of its latitude with the solar activity and 7° Westward over a 24‐years periodThe higher the energy of the protons, the farther north and west the SAA shifts [ABSTRACT FROM AUTHOR]

Elevated ethanol concentrations in yeast affect the plasma membrane. The plasma membrane in yeast has many lipid-protein complexes, such as Pma1 (MCP), Can1 (MCC), and the eisosome complex. We investigated the response of eisosomes, MCPs, and membraneless structures to ethanol stress. We found a correlation between ethanol stress and proton flux with quick acidification of the medium. Moreover, ethanol stress influences the symporter expression in stressed cells. We also suggest that acute stress from ethanol leads to increases in eisosome size and SG number: we hypothesized that eisosomes may protect APC symporters and accumulate an mRNA decay protein in ethanol-stressed cells. Our findings suggest that the joint action of these factors may provide a protective effect on cells under ethanol stress.

SUMMARY: In natural and agricultural situations, ammonium (NH4+) is a preferred nitrogen (N) source for plants, but excessive amounts can be hazardous to them, known as NH4+ toxicity. Nitrate (NO3−) has long been recognized to reduce NH4+ toxicity. However, little is known about Brassica napus, a major oil crop that is sensitive to high NH4+. Here, we found that NO3− can mitigate NH4+ toxicity by balancing rhizosphere and intracellular pH and accelerating ammonium assimilation in B. napus. NO3− increased the uptake of NO3− and NH4+ under high NH4+ circumstances by triggering the expression of NO3− and NH4+ transporters, while NO3− and H+ efflux from the cytoplasm to the apoplast was enhanced by promoting the expression of NO3− efflux transporters and genes encoding plasma membrane H+‐ATPase. In addition, NO3− increased pH in the cytosol, vacuole, and rhizosphere, and down‐regulated genes induced by acid stress. Root glutamine synthetase (GS) activity was elevated by NO3− under high NH4+ conditions to enhance the assimilation of NH4+ into amino acids, thereby reducing NH4+ accumulation and translocation to shoot in rapeseed. In addition, root GS activity was highly dependent on the environmental pH. NO3− might induce metabolites involved in amino acid biosynthesis and malate metabolism in the tricarboxylic acid cycle, and inhibit phenylpropanoid metabolism to mitigate NH4+ toxicity. Collectively, our results indicate that NO3− balances both rhizosphere and intracellular pH via effective NO3− transmembrane cycling, accelerates NH4+ assimilation, and up‐regulates malate metabolism to mitigate NH4+ toxicity in oilseed rape. [ABSTRACT FROM AUTHOR]

Bioenergetic profiles of psychrophiles across domains of life are unusual in that intracellular ATP levels increase with declining temperature. Whole-transcriptome sequencing of the glacier ice worm Mesenchytraeus solifugus revealed a unique C-terminal extension on the ATP6 protein, which forms part of the proton pore of mitochondrial ATP synthase (Complex V). This extension, positioned near the proton exit pore, comprises alternating histidine residues thought to increase proton flux through Complex V leading to elevated ATP synthesis. To test this hypothesis, we fused the M. solifugus C-terminal extension to Escherichia coli AtpB (the ATP6 orthologue) and observed a ~ 5-fold increase in ATP synthesis. This enhancement was unidirectional as we observed no change to ATP hydrolysis rates. These findings offer an avenue for identifying critical factors associated with ice worm adaptation., (© 2025 The Author(s). FEBS Letters published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

We present multi‐spacecraft observations of the proton fluxes spanning from 1.5 to 433 MeV for the largest solar proton event of solar cycle 24, i.e., September 7 and 10, 2017. In September 2017, M5.5 flare on September 4, X9.3 flare on September 6 and X8.2 flare on September 10 gave rise to solar proton event when observed by near‐Earth spacecrafts. On September 7 and September 10, 2017, a strong enhancement in the proton intensities was observed by Advanced Composition Explorer (ACE) and WIND at L1 and Van Allen Probes, GOES‐15 and POES‐19 in the Earth's inner magnetosphere. Below geosynchronous orbit, Van Allen Probes and POES‐19 show that no significant proton flux was observed with energies ≤25 MeV on September 4, while the fluxes peaked 3 to 7‐times during September 7 and by ∼25 times during the third proton flux event on September 10, 2017. Van Allen Probe‐A observation shows that the closest distance that solar proton fluxes could approach the Earth is L∼4.4 for 102.6 MeV energies on 10th September 2017, while lower energy protons i.e., 25 MeV are observed deep up to L∼3.4 on 11th September 2017. POES‐19 observations show that there is no particular magnetic local time (MLT) dependence of the solar proton flux and is symmetric everywhere at high and low latitudes. The measurements from multiple spacecrafts located in the different regions of the Earth's magnetosphere show that the increased level of solar proton flux population persisted for ∼2 days. Thus, we quantify the temporal flux variability in terms of L‐value, energy and MLT. Plain Language Summary: During a solar energetic particle (SEP) event, energetic electrons and ions flood the heliosphere causing severe damage to satellites, radio communication and humans in space. The Earth's magnetic field controls the dynamics of these particles to near‐Earth space. One such unique event was observed in September 2017 for which the energy spectra and quantification of the proton fluxes spanning from 1.5 to 433 MeV using multi‐satellite observations is studied. This was the largest proton event of the solar cycle 24 with three M‐class and four X‐class flares were observed by near‐Earth spacecrafts. Proton fluxes were quantified at different locations like L1 point, geostationary orbit, inner magnetosphere, and low altitudes. The extent of flux enhancements, its access into the Earth's magnetosphere, MLT dependence and time to reach maximum fluxes are computed and compared before and after the SEPs arrived. We show that the multiple spacecraft observations are the key tool to quantify the temporal flux variability in terms of L‐value, energy and MLT. Key Points: Peak proton fluxes with energies >20 MeV at L = 6.6 on 10th September were >2 order higher than the ones observed on September 7, 2017Solar proton fluxes were observed as close as L∼3.4Solar proton fluxes show no particular magnetic local time dependence [ABSTRACT FROM AUTHOR]

A test particle simulation code was developed to simulate the inner proton belt response during the intense geomagnetic storm of 15 May 2005. The guiding center model was implemented to compute the proton trajectories with an energy range of 70–180 MeV. The time-varying magnetic field model implemented in the simulations was computed by the Tsyganenko model TS05 with the associated inductive electric field. One of the most important features of the low-earth orbit (LEO) environment is the South Atlantic Anomaly, which imposes a dangerous radiation load on most LEO missions. This research aims to investigate the proton flux variations in the anomaly region with respect to space weather conditions. The results showed that during the main phase of the geomagnetic storm, the proton flux in the SAA decreased, whereas, throughout the initial and recovery phases, the proton flux was increased at most of the altitudes. Satellite measurements confirmed numerical results. [ABSTRACT FROM AUTHOR]

Proton (H+) fluxes in plant roots play critical roles in maintaining root growth and facilitating plant responses to multiple soil stresses, including fluctuations in nutrient supply, salt infiltration, and water stress. Soil mining for nutrients and water, rates of nutrient uptake, and the modulation of cell expansion all depend on the regulation of root H+ fluxes, particularly at the root apex, mediated primarily by the activity of plasma membrane (PM) H+-ATPases. Here, we summarize recent findings on the regulatory mechanisms of H+ fluxes at the root apex under three abiotic stress conditions – phosphate deficiency, salinity stress, and water deficiency – and present an integrated physiomolecular view of the functions of H+ fluxes in maintaining root growth in the acclimation to soil stress. Modulation of proton fluxes at the root apex plays roles in nutrient and water acquisition to overcome several types of abiotic stress conditions. Enhanced plasma membrane (PM) H+-ATPase activity in different root apex zones helps to maintain cell elongation, root hair formation, lateral root development, and the secretion of organic acids under phosphate-deficient conditions. Auxin and blue-light signaling pathways are involved in the low-phosphate responses in roots that are tightly linked with regulation of the proton fluxes at the root apex. PKS5- and PIN2-regulated PM H+-ATPase activity at the root apex is essential for salt tolerance and the salt avoidance response. Several signaling components that attribute to drought resistance and hydrotropic response control the proton fluxes at the root apex via ABA- and brassinosteroid-mediated pathways. [ABSTRACT FROM AUTHOR]

The CALorimetric Electron Telescope (CALET) space experiment, developed by Japan in collaboration with Italy and the United States, is a high-energy astroparticle physics mission installed on the International Space Station (ISS). The primary goals of the CALET mission include investigating on the possible presence of nearby sources of high-energy electrons, studying the details of galactic particle propagation and searching for dark matter signatures. During a two-year mission, extendable to five years, CALET can measure the flux of cosmic-ray electrons (including positrons) to 20 TeV, gamma-rays to 10 TeV and nuclei with Z = 1 to 40 up to 1,000 TeV. The instrument consists of two layers of segmented plastic scintillators for cosmic-ray charge identification (CHD), a 3 radiation length thick tungsten-scintillating fiber imaging calorimeter (IMC) and a 27 radiation length thick lead-tungstate calorimeter (TASC). CALET has sufficient depth, imaging capabilities and excellent energy resolution to allow for a clear separation between hadrons and electrons and between charged particles and gamma rays. The instrument was launched on August 19, 2015 to the ISS with the H-II Transfer Vehicle 5 (HTV-5) and installed on the Japanese Experiment Module-Exposed Facility (JEM-EF) on August 25. Since the start of operations in mid-October, 2015, a continuous observation has been going on mainly by triggering high energy (>10 GeV) showers without any major interruption. The number of triggered events above 10 GeV is nearly 20 million per month. By using the data obtained during the first two years, we give a summary of CALET observations: (1) Electron + Positron energy spectrum, (2) Proton and Nuclei spectrum, (3) Gamma-ray observation, with results of the performance study on orbit. We also present the results of observations of the electromagnetic counterparts to LIGO-VIRGO gravitational wave events and high-energy counterparts to GRB events measured with the CALET Gamma-ray Burst Monitor (CGBM). [ABSTRACT FROM AUTHOR]

We report updated measurements of the integral fluxes of energetic protons, helium ions, and heavier ions as measured by the Cosmic Ray Telescope for the Effects of Radiation (CRaTER). CRaTER is a particle telescope that has been operating aboard the Lunar Reconnaissance Orbiter since 2009. In an earlier report, we presented the methodology used to extract linear energy transfer spectra and integral fluxes for particles with sufficient energies to fully penetrate the telescope. Results were presented for the time span from late 2009 to the end of calendar year 2014, a period that encompassed the rise of solar activity from deep solar minimum to the weak maximum of Cycle 24. Here, we update the results with data obtained from that point in time through the end of 2018, in the declining phase of Cycle 24. Fluxes obtained in the most recent data are approaching the peak levels observed in late 2009 and early 2010. The results can be used as input to models of solar modulation of galactic cosmic rays and are also relevant to human exploration of deep space. Plain Language Summary: We report measurements of increasing intensities of galactic cosmic ray protons and helium ions from 2015 to the end of 2018. The overall decrease in solar activity in this period has led to an increased flux of energetic particles, to levels that are approaching those observed during the previous solar minimum in 2009/2010, which was the deepest minimum of the Space Age. The data have implications for human exploration of deep space and may provide useful benchmarks for models of cosmic ray fluxes as a function of solar modulation. Key Points: Integral fluxes of hydrogen and helium ions in the GCR are nearing 2009–2010 levelsRecently obtained linear energy transfer spectra closely resemble those from 2009 to 2010Solar modulation affects protons more than helium, as expected from rigidity considerations [ABSTRACT FROM AUTHOR]

Abstract SLC4A11 mutations are associated with Fuchs' endothelial corneal dystrophy (FECD), congenital hereditary endothelial dystrophy (CHED) and Harboyan syndrome (endothelial dystrophy with auditory deficiency). Mice with genetically ablated Slc4a11 recapitulate CHED, exhibiting significant corneal edema and altered endothelial morphology. We recently demonstrated that SLC4A11 functions as an NH 3 sensitive, electrogenic H+ transporter. Here, we investigated the properties of five clinically relevant SLC4A11 mutants: R125H, W240S, C386R, V507I and N693A, relative to wild type, expressed in a PS120 fibroblast cell line. The effect of these mutations on the NH 4 Cl-dependent transporter activity was investigated by intracellular pH and electrophysiology measurements. Relative to plasma membrane expression of Na K ATPase, there were no significant differences in plasma membrane SLC4A11 expression among each mutant and wild type. All mutants revealed a marked decrease in acidification in response to NH 4 Cl when compared to wild type, indicating a decreased H+ permeability in mutants. All mutants exhibited significantly reduced H+ currents at negative holding potentials as compared to wild type. Uniquely, the C386R and W240S mutants exhibited a different inward current profile upon NH 4 Cl challenges, suggesting an altered transport mode. Thus, our data suggest that these SLC4A11 mutants, rather than having impaired protein trafficking, show altered H+ flux properties. [ABSTRACT FROM AUTHOR]

Pentameric FocA permeates either formate or formic acid bidirectionally across the cytoplasmic membrane of anaerobically growing Escherichia coli. Each protomer of FocA has its own hydrophobic pore, but it is unclear whether formate or neutral formic acid is translocated in vivo. Here, we measured total and dicyclohexylcarbodiimide (DCCD)-inhibited proton flux out of resting, fermentatively grown, stationary-phase E. coli cells in dependence on FocA. Using a wild-type strain synthesizing native FocA, it was shown that using glucose as a source of formate, DCCD-independent proton efflux was ∼2.5 mmol min−1, while a mutant lacking FocA showed only DCCD-inhibited, F O F 1 -ATPase-dependent proton-efflux. A strain synthesizing a chromosomally-encoded FocA H209N variant that functions exclusively to translocate formic acid out of the cell, showed a further 20 % increase in FocA-dependent proton efflux relative to the parental strain. Cells synthesizing a FocA T91A variant, which is unable to translocate formic acid out of the cell, showed only DCCD-inhibited proton efflux. When exogenous formate was added, formic acid uptake was shown to be both FocA- and proton motive force-dependent. By measuring rates of H 2 production, potassium ion flux and ATPase activity, these data support a role for coupling between formate, proton and K+ ion translocation in maintaining pH and ion gradient homeostasis during fermentation. FocA thus plays a key role in maintaining this homeostatic balance in fermenting cells by bidirectionally translocating formic acid. • FocA bidirectionally translocates formate plus a proton across the membrane. • Coupling between ion translocation activities of FocA, F O F 1 -ATPase and K+ transport. • H+ co-transported with formate via FocA or coupled with F O F 1 proton translocation. • FocA contributes ion and pH homeostasis during fermentation in E. coli. [ABSTRACT FROM AUTHOR]

Abstract Two Liulin type spectrometers performed measurements of the energetic particles flux outside the International Space Station (ISS) in 3 long-term periods between 2008 and 2016. The linear regression analysis is performed of 1053 averaged per day South-Atlantic anomaly (SAA) proton flux measurements from the daily Dst index. The data reveal that the SAA flux dependence from the Joule heating in the high latitudes and respectively from the neutral atmosphere density, isn't observed only in the time of the magnetic storms. This is a permanent, continues process influencing the SAA fluxes all the time. The data, obtained during the two magnetic storms in 2010 and to powerful storms of March and June 2015, were used to find and classify the following short-term magnetic storm effects: 1) The SAA proton flux maximum and area show strong decrease during the main phase of the magnetic storms. The protons losses can be caused by the collisions with the storm-enhanced neutral oxygen atoms. This hypothesis is proved by a comparison with the prediction by the NRLMSISE-00 model global neutral Oxygen density; 2) Increase of the proton flux, in the presence of solar energetic protons, is observed during the storm sudden commencements (SSC); 3) An enhanced flux of relativistic electrons is recorded in SAA during the recovery phase of the magnetic storms at L-values higher than 1.7. They migrate from the outer radiation belt. Their presence was proved by the analysis of the energy deposition spectra. Highlights • Particle flux measurements outside the International space station are presented. • Data are obtained by Bulgarian build Liulin type instruments. • South-Atlantic anomaly flux variations during magnetic storms are analyzed. [ABSTRACT FROM AUTHOR]

Phosphorus deficiency in soil is one of the major limiting factors for plant growth. Plasma membrane H+-ATPase (PM H+-ATPase) plays an important role in the plant response to low-phosphorus stress (LP). However, few details are known regarding the action of PM H+-ATPase in mediating root proton (H+) flux and root growth under LP. In this study, we investigated the involvement and function of different Arabidopsis PM H+-ATPase genes in root H+ flux in response to LP. First, we examined the expressions of all Arabidopsis PM H+-ATPase gene family members (AHA1-AHA11) under LP. Expression of AHA2 and AHA7 in roots was enhanced under this condition. When the two genes were deficient in their respective Arabidopsis mutant plants, root growth and responses of the mutants to LP were highly inhibited compared with the wild-type plant. AHA2-deficient plants exhibited reduced primary root elongation and lower H+ efflux in the root elongation zone. AHA7-deficient plants exhibited reduced root hair density and lower H+ efflux in the root hair zone. The modulation of H+ efflux by AHA2 or AHA7 was affected by the action of 14-3-3 proteins and/or auxin regulatory pathways in the context of root growth and response to LP. Our results suggest that under LP conditions, AHA2 acts mainly to modulate primary root elongation by mediating H+ efflux in the root elongation zone, whereas AHA7 plays an important role in root hair formation by mediating H+ efflux in the root hair zone. [ABSTRACT FROM AUTHOR]

Background: The purpose of this paper is a review of a number of studies considering links between life threatening cardiac arrhythmias, sudden cardiac death (SCD) and the level of environmental physical activity factors like geomagnetic activity (GMA) and opposite them cosmic ray and high energy proton flux. This is a part of studies in the field named Clinical Cosmobiology. Methods: Temporal distribution of cardiac arrhythmias and SCD daily and monthly were compared to the level of GMA, space proton flux, cosmic ray activity according to neutron activity (impulse/min) on the earth's surface. The cosmophysical data was obtained from the cosmic science institutions in the USA, Russia and Finland (cosmic ray data, partially). Results: As it follows from the results of the quoted studies there is an inverse relationship between the frequency of cardiac arrhythmic events and SCD and the level of daily GMA. Conclusions: Now studies are in progress considering the role of neutron (cosmic ray) activity in the natural history of the mentioned events. According to the various studies, we can presume that the GMA has some protective effect on cardiac arrhythmias and SCD.