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A model for physiological transmembrane transport derived from thermodynamical principles

A generic formulation for both passive and active transmembrane transport is derived from basic thermodynamical principles. The derivation takes into account the energy required for the motion of molecules across membranes, and includes the possibility of modeling asymmetric flow. Transmembrane currents can then be described by the generic model in the case of electrogenic flow. As it is desirable in new models, it is possible to derive other well known expressions for transmembrane currents as particular cases of the generic formulation. For instance, the conductance-based formulation for current turns out to be a linear approximation of the generic current. Also, under suitable assumptions, other formulas for current based on electrodiffusion, like the constant field approximation by Goldman, can also be recovered from the generic formulation. The applicability of the generic formulations is illustrated first with fits to existing data, and after, with models of transmembrane potential dynamics for pacemaking cardiocytes and neurons. The generic formulations presented here provide a common ground for the biophysical study of physiological phenomena that depend on transmembrane transport.

physiology↗

Temporal gating of SIRT1 functions by O-GlcNAcylation prevents hyperglycemia and enables physiological transitions in liver

Inefficient fasted-to-refed transitions are known to cause metabolic diseases. Thus, identifying mechanisms that may constitute molecular switches during such physiological transitions become crucial. Specifically, whether nutrients program a relay of interactions in master regulators, such as SIRT1, and affect their stability is underexplored. Here, we elucidate nutrient-dependent O-GlcNAcylation of SIRT1, within its N-terminal domain, as a key determinant of hepatic glucose- and fat-metabolism, and insulin signaling. SIRT1 glycosylation dictates interactions with PPAR/FOXO1/PGC1/SREBP1, to exert a temporal control over transcription of genes during fasted-to-refed transitions. Interestingly, glycosylation-dependent cytosolic export of SIRT1 promotes a transient interaction with AKT and subsequent proteasomal degradation. Loss of glycosylation discomposes these interactions and enhances stability of SIRT1 even upon refeeding, which causes insulin resistance, hyperglycemia and hepatic-inflammation. Aberrant glycosylation of SIRT1 is associated with aging and/or metabolic diseases. Thus, nutrient-dependent glycosylation constrains spatio-temporal dynamics of SIRT1 and gates its functions to maintain metabolic homeostasis.

physiology↗

The physiological response in the mammary gland to Escherichia coli infection reflects a conflict between glucose need for milk production and immune response

Upon entry into the mammary gland, mammary pathogenic strains of Escherichia coli rapidly grow using milk as a nutrient source, in a manner highly dependent on the expression of the ferric-dicitrate system by these bacteria. Intra-mammary challenge with distinct mammary pathogenic E. coli (MPEC) strains result in development of clinical acute mastitis, with peak bacterial counts in milk at 16-24 h post-challenged and profound immune changes found in the milk. The main biochemical changes measured in milk were partially in accord with lipopolysaccharide-induced mastitis, with increased glucose-6-phosphate and lactate dehydrogenase activity or prolonged lactate dehydrogenase, and Glu6P/Glu alterations. Changes also reflect physiological responses to inflammation in the mammary gland, as in the balance between aerobic and anaerobic metabolism (citrate to lactate ratios). Some alterations measured in milk resolved with days after challenge but other remained for above one month, regardless of bacterial clearance. The results suggest that E. coli mastitits can be divided into two stages: an acute, clinical phase, as an immediate response to bacterial infection in the mammary gland and a chronic phase, independent of bacteria clearance, and in response to the tissue damage caused in the first phase.

physiology↗

Age-dependent effects of reduced mTor signalling on life expectancy through distinct physiology

Research on the mechanisms of ageing has identified ways via which lifespan can be extended in model organisms, increasing the potential for translation of these findings to our own species. However, the large majority of research on animal models involves dietary, genetic or pharmacological treatments throughout life - limiting translational potential and ignoring age-dependent effects. Previously, we have suggested using demographic meta-analysis that reduced mTor signalling has the potential to instantly rejuvenate. We have now tested this prediction experimentally using large-scale demographic data (N > 10,000) combined with conditional knockdown of mTor in Drosophila melanogaster. Indeed, reduced mTor decreased mortality rate when applied during old age. Interestingly, we found that transient treatment during early adult life had long-lasting benefits. Age-dependent deep-RNAseq indicated that these effects arose from distinct physiology and implicate alternative splicing as a potential mechanism for the long-lasting benefits of transient mTor reduction. These findings suggest that reducing mTor short term or during old age could be used to combat ageing. In addition, our findings suggest that the results from experimental research on mTor signalling, and potentially other mechanisms of ageing, that employ life-long interventions are likely to be a complex composite of age-dependent effects that counteract or enhance each other.

physiology↗

Physiological synchrony promotes cooperative success in real-life interactions

Cooperation is pivotal for society to flourish and prosper. To ease cooperation, humans express and read emotions and intentions via explicit signals or subtle reflections of arousal visible in the face. Evidence is accumulating that humans synchronize these nonverbal expressions, as well as the physiological mechanisms underlying them, potentially promoting cooperative behavior. The current study is designed to verify the existence of this putative linkage between synchrony and cooperation. To that extent, 152 participants played multiple rounds of the Prisoners Dilemma game in a naturalistic dyadic interaction setting. During one round of games they could see each other, and during a second round they could not. The results showed that when peoples heart rate and skin conductance level aligned, they cooperated more successfully. Interestingly, for skin conductance level synchrony to boost cooperation, face to face contact was essential. The effect of heart rate synchrony on cooperation was context independent. Skin conductance level, but not heart rate, tended to closely correlate with changes in pupil size and we discuss how the pupil might provide a window to partners sympathetic arousal. These findings show how unconscious mechanisms guide social behavior and emphasize the importance of studying social processes between rather than within individuals in real-life interactions. Significance StatementHuman cooperation is remarkable in its scale, complexity, and efficiency. However, whereas people think of themselves as rational agents, they actually partly base their decision to cooperate with someone on gut feelings. These feelings are informed by non-verbal expressions that are picked up implicitly and that synchronize across interaction partners. For the first time, we show that the alignment of peoples arousal over multiple rounds of the Prisoners dilemma game predicts cooperative success. Through synchrony, partners converge emotionally, fostering understanding and bonding, which are key ingredients when it comes to successful cooperation. This suggests that successfully cooperating does not depend on individuals, but on the connection between individuals, emphasizing the importance of studying social decision-making processes in real-life settings.

physiology↗

State Change Probability: A Measure of the Complexity of Cardiac RR Interval Time Series Using Physiological State Change with Statistical Hypothesis Testing

The complexity of biological signals has been proposed to reflect the adaptability of a given biological system to different environments. Two measures of complexity--multiscale entropy (MSE) and entropy of entropy (EoE)--have been proposed, to evaluate the complexity of heart rate signals from different perspectives. The MSE evaluates the information content of a long time series across multiple temporal scales, while the EoE characterizes variation in amount of information, which is interpreted as the \"state changing,\" of segments in a time series. However, both are problematic when analyzing white noise and are sensitive to data size. Therefore, based on the concept of \"state changing,\" we propose state change probability (SCP) as a measure of complexity. SCP utilizes a statistical hypothesis test to determine the physiological state changes between two consecutive segments in heart rate signals. The SCP value is defined as the ratio of the number of state changes to total number of consecutive segment pairs. Two common statistical tests, the t-test and Wilcoxon rank-sum test, were separately used in the SCP algorithm for comparison, yielding similar results. The SCP method is capable of reasonably evaluating the complexity of white noise and other signals, including 1/f noise, periodic signals, and heart rate signals, from healthy subjects, as well as subjects with congestive heart failure or atrial fibrillation. The SCP method is also insensitive to data size. A universal SCP threshold value can be applied, to differentiate between healthy and pathological subjects for data sizes ranging from 100 to 10,000 points. The SCP algorithm is slightly better than the EoE method when differentiating between subjects, and is superior to the MSE method.

physiology↗

Regimen-dependent glucocorticoid effects improve muscle performance without altering CNS physiology in mdx mice

Duchenne muscular dystrophy (DMD) is a multisystem disorder affecting striated muscle, metabolism, and the central nervous system (CNS). Although glucocorticoids remain the standard therapy, muscle-centric evaluations typically fail to capture how dosing regimen and compound selection affect CNS and metabolic phenotypes. Here, we compared daily and weekly dosing of prednisolone and vamorolone in juvenile mdx mice over six weeks to determine how these variables influence multisystem outcomes. Multiorgan efficacy and adverse effects were quantified across behavioural, endocrine, metabolic, cardiovascular, and muscle domains using behavioural assays, in vivo and functional muscle testing, haemodynamic evaluation and histopathology. Daily glucocorticoid dosing failed to improve muscle function or strength, whereas weekly vamorolone produced the most robust improvements in functional and in vivo muscle strength. Daily prednisolone reduced circulating creatine kinase levels, but this biochemical change did not translate into enhanced muscle function outcomes. Daily regimens also induced severe adrenal cortical atrophy, yet these endocrine alterations were dissociated from CNS stress and anxiety responses, which remained unchanged by treatment. In addition, daily dosing caused pronounced systemic metabolic consequences, whereas weekly regimens substantially attenuated these effects, identifying dosing frequency as a key determinant of safety. Together, these findings demonstrate that glucocorticoid regimen selection fundamentally reshapes the efficacy-adverse effect profile and underscores the value of integrated multiorgan evaluation in DMD. This work highlights the need to expand therapeutic assessments beyond muscle pathology and raises new questions about how glucocorticoid signalling differentially engages peripheral and central physiological systems.

physiology↗

Effects of hypoxia and low temperature on female physiology and reproduction of Drosophila melanogaster

Because hypoxia and low temperature independently alter metabolism and reproductive investment, their interaction provides a tractable framework for testing whether combined stressors produce non-additive physiological and reproductive effects. Here, we investigated the single and combined effects of hypoxia and low temperature in Drosophila melanogaster across multiple genetic backgrounds. We quantified metabolic rate, thermal tolerance, body mass, fertility, oogenesis progression, and oocyte apoptosis to assess organismal responses to environmental stress. Hypoxia generally increased respiratory quotient and body mass, but its effects on thermal tolerance and fertility were highly genotype dependent. Across traits, combined stressors frequently produced responses that differed from those observed under single stressors, including reduced fertility, altered oogenesis, and changes in oocyte cell death. Importantly, these effects were not uniform: some genotypes exhibited increased oocyte production or reduced cell death under combined stress, highlighting pronounced genotype-dependent differences in stress sensitivity and reproductive allocation. Together, our results demonstrate that the interaction between hypoxia and temperature can modulate metabolic and reproductive responses in ways that are not predictable from single-stressor responses alone. These findings highlight the importance of incorporating genetic background and interacting environmental stressors when evaluating organismal tolerance and adaptive potential under ongoing environmental change.

physiology↗

Physiological and Biochemical Responses of Grafted Tomato Plants to Salinity Stress: Evidence from the Syrian Coast

The research was carried out in Tartus (Syria), in a plastic greenhouse during the season 2024-2025. Two tomato hybrids "Levovil and Shannon" were grafted onto two tomato "Spirit and Maxifort" rootstocks. Four levels of salinity (0, 50, 100 and 150 mM NaCl) were applied on the hybrids and grafted plants. Salinty stress induced physiological and biochemical changes in plant. At salinity level of 150 mM, the absolute value of the osmotic pressure increased to -1.18 and -1.12 Mpa, in Levovil and Shannon hybrids, as compared to -0.80 and - 0.74 Mpa in the controls, respectively. While 150 mM salinity level led to an increase of the contents of dry matter, proline, sugars and chlorine, it caused a decrease of K: Na ratio in the two hybrids (1.99 and 1.8) as compared to the controls (5.29 and 4.68, respectively). The salinity stress at 150 mM, reduced the yield of the two hybrids (26.26 and 25.28 kg/m2) as compared to the controls (33.90 and 33.11 kg/m2, respectively). The tomato scions "Levovil and Shannon hybrids" grafted onto the "Spirit and Maxifort" rootstocks enhanced the osmotic adjustment phenomenon, especially when the two hybrids were grafted onto Spirit. While tomato grafting had a significant effect on the accumulation of some osmotic compounds such as proline and sugars, in addition to increasing K: Na ratio, it reduced the absolute value of the osmotic pressure of the plant and its sodium content. Therefore, the yield increased in grafted tomato plants compared with non-grafted plants under saline conditions. The results of PCA analysis showed that the first two principal components (PC1 and PC2) explained 89.08% of the total variation, wherease all the studied parameters were well represented. The dendrogram was obtained based on the same variables as PCA, and it led to classify "Spirit" rootstock as tolerant to salt stress, "Maxifort" rootstock as half tolerant, and the non-grafted hybrids "Levovil and Shannon" as sensitive to salt stress.

physiology↗

Colony maintenance and the behavioral and physiological characteristics of selectively bred obesity prone and obesity resistant rats.

Obesity arises from interactions between several factors including physiology, environment and genes. Studies in humans have revealed that up to 70% of overweight and obesity can be attributed to biological and genetic factors. Thus, rodent models that capture innate susceptibility or resistance to obesity have been invaluable for disentangling inherent drivers of obesity from neurobiological alterations that occur in response to consumption of obesogenic foods and/or increased adiposity. For example, studies of rats selectively bred for their propensity vs resistance to diet-induced weight gain (DIO and DR) have uncovered differences in hypothalamic circuits involved in leptin signaling and revealed relationships between susceptibility to obesity and motivational response to food cues, as well as inherent and diet-induced alterations in mesocorticolimbic systems that differ between these populations. Maintaining selectively bred lines in a closed breeding population requires the periodic introduction of new genes to avoid inbreeding. Here we describe a process for maintaining these lines, characterize key phenotypes across the selection process and verify weight gain and obesity phenotypes in the resulting colony. In addition, given the central role of the striatum in motivation for food, we examined basal striatal function and food motivation in these refreshed lines using whole-cell patch clamping and instrumental procedures. Key weight and metabolic phenotypes were maintained in the resulting colony, as was enhanced motivation for food in obesity prone rats. This provides a strong basis for examination of interactions between genes, environment and neurobehavioral plasticity that promote weight gain and obesity.

physiology↗

Towards a Physiological Scaling Law: Model Quality vs. Cohort Size for Stochastic Sequence Data

Scaling laws help determine the optimal data size for training large models but are established in domains where the target is deterministic. Physiological signals are different: heartbeat sequences are stochastic, so part of the error is irreducible even with large amounts of data. Metrics such as MAE do not account for non-deterministic behavior, and therefore assessing scaling requires evaluating distributional calibration (measuring how well predicted probability densities capture true conditional characteristics). We formulate a scaling law metric(n) = E + A n- and evaluate it with five metrics: accuracy (MAE, RMSE), distributional calibration (KS distance, goodness-of-fit), and training objective (negative log loss) using a neural temporal point process trained on a cohort of four-ECG datasets. The law fits all five metrics. While point accuracy is near saturation at n = 183, KS distance and goodness-of-fit improve by 6% and 12% respectively when extrapolated to 10,000 subjects, showing that scaling decisions in stochastic domains must be guided by distributional calibration rather than point accuracy.

physiology↗

Stressful exposure from the 2004 Indian Ocean Tsunami drives long-term changes in thyroid hormone physiology

Stressful events are associated with long-term adverse health impacts, but the causal mechanisms linking these exposures to subsequent disease remain poorly understood. One plausible mechanism is persistent changes to hormonal signaling that regulate metabolic homeostasis. Here, we examine the long-term impacts of stress associated with exposure to the 2004 Indian Ocean tsunami on levels of free triiodothyronine (FT3), a circulating measure of biologically active thyroid hormone, using data from the Study of Tsunami Aftermath and Recovery. We measure biomarkers 20 years after the tsunami in a population-representative sample age 35y+ in 2024 who, at the time of the tsunami, were living along the coast of Aceh, Indonesia, the most affected part of the Indian Ocean Basin. Because respondents were first interviewed before the tsunami and subsequently tracked regardless of migration, the sample avoids a major source of selection bias common in long-term disaster studies. We identify the causal effect of tsunami exposure using variation in community-level tsunami mortality, comparing communities within the same sub-district. We find that greater tsunami exposure reduced levels of FT3 20 years later. Exposure also altered relationships between FT3, body composition, and cortisol and increased cardiometabolic risk. These findings identify persistent alteration of thyroid hormone physiology as a potential pathway linking severe stressful exposures to long-term cardiometabolic disease risk.

physiology↗

Enhancing the Clinical Utility of Renal Denervation Through Efficient Physiologic Monitoring

Introduction: The inability to measure renal sympathetic outflow clinically poses a significant problem for patient identification and intraprocedural feedback for renal denervation. Sympathetic vasomotion is a novel physiologic measure of rhythmic vascular control that reflects renal sympathetic nervous system activity, but previous measurements of sympathetic vasomotion relied on 15-minute data recordings, which may be impractical in many clinical settings. We therefore tested whether shorter data segments can provide reliable sympathetic vasomotion assessment to enhance decision making for renal denervation. Methods: Ten swine that had previously undergone unilateral surgical renal denervation underwent four rounds of catheter-based denervation of the contralateral kidney. Sympathetic vasomotion was quantified from the time-varying arterial pressure-resistive renal blood flow transfer function of recordings obtained before and after each round of ablation. Randomly placed 1- to 14-minute data segments were scored and compared with the corresponding 15-minute sympathetic vasomotion scores across 100 passes using correlation, intraclass correlation, error, and Bland-Altman agreement metrics, and by whether they reproduced the denervation decisions made from the full recordings. Results: Agreement with the 15-minute reference score improved steeply with recording length up to approximately four minutes and slowly thereafter, with the point of diminishing returns at four minutes for every group-level measure. Four-minute data segments showed an intraclass correlation coefficient of 0.94, reproduced the group-level statistical results across ablations, and preserved intraprocedural denervation decisions. Bland-Altman analysis revealed that individual-level precision continued to improve with recording length; the proportion of scores falling within a quarter of the average difference between innervated and denervated kidneys at baseline was 65 percent at four minutes and 96 percent at ten minutes. Discussion: Four-minute data segments provide a feasible minimum recording duration when the question is a group comparison or a paired, within-individual decision, such as intraprocedural confirmation that an innervated kidney has shifted toward a denervated state. When a single score must be interpreted on its own, as in preprocedural patient selection, ten-minute recordings provide greater precision. Further studies are needed to prospectively evaluate sympathetic vasomotion in clinical settings and determine whether this technology can support procedural feedback and inform patient selection.

physiology↗

Reduced physiological reserve and a blunted response to acute exercise in adults with cerebral palsy

Cerebral palsy (CP) is an early-onset neurodevelopmental condition associated with metabolic impairment and an increased risk of non-communicable diseases across the lifespan. However, the basis of these changes remains largely unknown. This study provides a comprehensive cardiometabolic and physical function profile of 23 adults with CP relative to 33 typically developing (TD) adolescents and 61 TD adults. Compared to TD individuals, adults with CP exhibited reduced cardiorespiratory fitness, smaller cardiac dimensions, and lower muscle mass. Circulating metabolomic and proteomic profiling identified a distinct molecular signature in CP, including altered tricarboxylic acid (TCA) cycle metabolites, and elevated myostatin, matrix-related proteins and pro-inflammatory cytokines. We further tested the capacity for physiological and molecular adaptation using an acute bout of endurance exercise. In response to exercise, individuals with CP exhibited an attenuated response compared to TD groups, characterized by a blunted lactate response and lower venous oxygen levels. TD participants also increased canonical exercise-responsive factors, including NADK, IL-8, ANGPTL1 and GDF15, whereas these responses were attenuated in CP. These novel findings define a distinct cardiometabolic profile in adults with CP at rest and reveal an attenuated molecular response to exercise. These data carry implications for targeted interventions and prevention strategies across the lifespan.

physiology↗

A high resolution 7-Tesla resting-state fMRI test-retest dataset with cognitive and physiological measures

Here we present a test-retest dataset of functional magnetic resonance imaging (fMRI) data acquired at rest. 22 participants were scanned during two sessions spaced one week apart. Each session includes two 1.5 mm isotropic whole-brain scans and one 0.75 mm isotropic scan of the prefrontal cortex, giving a total of six timepoints. Additionally, the dataset includes measures of mood, sustained attention, blood pressure, respiration, pulse, and the content of self-generated thoughts (mind wandering). This data enables the investigation of sources of both intra- and inter-session variability not only limited to physiological changes, but also including alterations in cognitive and affective states, at high spatial resolution. The dataset is accompanied by a detailed experimental protocol and source code of all stimuli used.

Neuroscience↗

Pollen contaminated with field-relevant levels of cyhalothrin affects honey bee survival, nutritional physiology, and pollen consumption behavior

Honey bees are exposed to a variety of environmental stressors that impact their health, including nutritional stress, pathogens, and chemicals in the environment. In particular, there has been increasing evidence that sublethal exposure to pesticides can cause subtle, yet important effects on honey bee health and behavior. Here, we add to this body of knowledge by presenting data on bee-collected pollen containing sublethal levels of cyhalothrin, a pyrethroid insecticide, which, when fed to young honey bees, results in significant changes in lifespan, nutritional physiology, and behavior. For the first time, we show that when young, nest-aged bees are presented with pollen containing field-relevant levels of cyhalothrin, they reduce their consumption of contaminated pollen. This indicates that, at least for some chemicals, young bees are able to detect contamination in pollen and change their behavioral response, even if the contamination levels do not prevent foraging honey bees from collecting the contaminated pollen.

Animal Behavior and Cognition↗

Conformational dynamics of Tau in the cell quantified by an intramolecular FRET biosensor in physiological and pathological context

Impaired interactions of Tau protein with microtubules (MT) and Tau misfolding play a key role in Alzheimer disease (AD) and other neurodegenerative diseases collectively named Tauopathies. However, little is known about the molecular conformational changes that underlie Tau misfolding and aggregation in pathological conditions, due to the difficulty of studying structural aspects of this intrinsically unfolded protein, particularly in the context of living cells.\n\nHere we developed a new Conformational-Sensitive Tau sensor (CST), based on human Tau full length protein, to investigate the changes in 3D conformation and aggregation state of Tau upon modulation of its interactions with MTs in living cells, in physiological and pathological conditions. After showing that the CST fully preserves functional Tau activities in living cells, we demonstrated that MT-bound Tau displays a loop-like conformation, while soluble Tau assumes a relaxed conformation.\n\nThe imaging readout based on CST allowed to discover new conformational properties of full length Tau in living cells, when challenged with Alzheimer-relevant seeds from different sources, and to learn about different ways to induce the self-aggregation of full length Tau in cells. Furthermore, it allowed to investigate the contribution to the pathology of point mutations known to alter Tau/MTs interaction.\n\nSIGNIFICANCEThe microtubule-associated protein Tau regulates the stability of microtubules (MT) and its alteration and misfolding plays an important role in Alzheimer disease (AD) and in several other neurodegenerative diseases collectively named Tauopathies. However, little is known about the molecular mechanism that modulate the conformational changes of Tau in pathological conditions. Here, we developed a conformational sensitive Tau biosensor providing insights into the 3D conformation of Tau in living cells. This new tool showed that MT-bound Tau displays a loop-like conformation, while soluble Tau assume a relaxed conformation, which might be more prone to aggregation. Furthermore the CST was used to develop an assay to screen molecules and mutations involved in Tau self-aggregation in living cells. Remarkably, the imaging tool developed allowed to demonstrate that A{beta} oligomers induced Tau aggregation in living cells.

Neuroscience↗

Physiological and biochemical changes associated with experimental dehydration in the desert adapted cactus mouse, Peromyscus eremicus

Characterizing traits critical for adaptation to a given environment is an important first step in understanding how phenotypes evolve. How animals adapt to the extreme heat and aridity commonplace to deserts represents is an exceptionally interesting example of these processes, and has been the focus of study for decades. In contrast to those studies, where experiments are conducted on either wild animals or captive animals held in non-desert conditions, the study described here leverages a unique environmental chamber that replicates desert conditions for captive Peromyscus eremicus (cactus mouse). Here we establish baseline values for daily water intake and for serum electrolytes, as well as the response of these variables to experimental dehydration. In brief, P. eremicus daily water intake is very low. Its serum electrolytes are distinct from many previously studied animals, and its response to acute dehydration is profound, though not suggestive of renal impairment, which is atypical of mammals.\n\nSummary statementThe establishment of baseline values for serum electrolytes and water intake, as well as their response to acute dehydration is critical for characterizing the physiology necessary for desert survival.\n\nConflict of Interest StatementThe authors declare no conflict of interest.

Zoology↗