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Search indexed bioRxiv preprints in genomics, neuroscience, cell biology and bioinformatics. Read source abstracts and check manuscript versions; preprints are not peer reviewed.

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bioRxiv2017

The promiscuous estrogen receptor: evolution of physiological estrogens and response to phytochemicals and endocrine disruptors

Many actions of estradiol (E2), the principal physiological estrogen in vertebrates, are mediated by estrogen receptor- (ER) and ER{beta}. An important physiological feature of vertebrate ERs is their promiscuous response to several physiological steroids, including estradiol (E2), {Delta}5-androstenediol, 5-androstanediol, and 27-hydroxycholesterol. A novel structural characteristic of {Delta}5-androstenediol, 5-androstanediol, and 27-hydroxycholesterol is the presence of a C19 methyl group, which precludes the presence of an aromatic A ring with a C3 phenolic group that is a defining property of E2. The structural diversity of these estrogens can explain the response of the ER to synthetic chemicals such as bisphenol A and DDT, which disrupt estrogen physiology in vertebrates, and the estrogenic activity of a variety of plant-derived chemicals such as genistein, coumestrol, and resveratrol. Diversity in the A ring of physiological estrogens also expands potential structures of industrial chemicals that can act as endocrine disruptors. Compared to E2, synthesis of 27-hydroxycholesterol and {Delta}5-androstenediol is simpler, leading us, based on parsimony, to propose that one or both of these steroids or a related metabolite was a physiological estrogen early in the evolution of the ER, with E2 assuming this role later as the canonical estrogen. In addition to the well-studied role of the ER in reproductive physiology, the ER also is an important transcription factor in non-reproductive tissues such as the cardiovascular system, kidney, bone, and brain. Some of these ER actions in non-reproductive tissues appeared early in vertebrate evolution, long before mammals evolved.

physiology↗

bioRxiv2019

Resting-state \"Physiological Networks\"

Slow changes in systemic brain physiology can elicit large fluctuations in fMRI time series, which may manifest as structured spatial patterns of temporal correlations between distant brain regions. These correlations can appear similar to large-scale networks typically attributed to coupled neuronal activity. However, little effort has been devoted to a systematic investigation of such \"physiological networks\"--sets of segregated brain regions that exhibit similar physiological responses--and their potential influence on estimates of resting-state brain networks. Here, by analyzing a large group of subjects from the 3T Human Connectome Project database, we demonstrate brain-wide and noticeably heterogenous dynamics attributable to either respiratory variation or heart rate changes. We show that these physiologic dynamics can give rise to apparent \"connectivity\" patterns that resemble previously reported resting-state networks derived from fMRI data. Further, we show that this apparent \"physiological connectivity\" cannot be removed by the use of a single nuisance regressor for the entire brain (such as global signal regression) due to the clear regional heterogeneity of the physiological responses. Possible mechanisms causing these apparent \"physiological networks\", and their broad implications for interpreting functional connectivity studies are discussed.

physiology↗

bioRxiv2026

A Physiologically Constrained Calibration Framework for Cardiovascular Models applied in Paediatric Sepsis

Calibration of mechanistic cardiovascular models is a central barrier to their use in population analysis and patient-specific simulation, particularly in settings where key physiological variables are unobservable and multiple parameter combinations can reproduce the same haemodynamic targets. In this work, we present Embedded Gradient Descent (EGD), a calibration framework for ODE-based lumped-parameter cardiovascular models in which selected physiological parameters are promoted to dynamic states and driven toward prescribed targets through embedded controller equations. By exploiting the qualitative structure of the governing equations, EGD enforces physiologically consistent parameter-variable relationships, yielding unique calibrated solutions that are robust to initial conditions and scale efficiently with model complexity. The framework is demonstrated using a mechanistic cardiovascular model to generate virtual paediatric populations spanning normal physiology and two septic shock phenotypes (warm and cold shock), achieving low residual error across pressures, flows, and compartmental volumes. The resulting parameter distributions are consistent with known haemodynamic adaptations in paediatric sepsis, including alterations in vascular resistance, compliance, cardiac elastance, and effective blood volume. Importantly, persistent calibration residuals arise only when target combinations are structurally incompatible with the model, providing an explicit and interpretable diagnostic of feasibility limits rather than an optimisation failure. These results establish EGD as a general, scalable calibration strategy for mechanistic cardiovascular models and a practical foundation for virtual population generation and future patient-specific digital twin applications in critical care. NEW & NOTEWORTHYThis study introduces a novel, embedded gradient descent calibration framework that enables scalable generation of mechanistically interpretable virtual populations of patients from ODE-based cardiovascular models. By treating parameter inference as a dynamical extension of the governing equations and calibrating directly against cycle-derived physiological targets, the method preserves physiologically meaningful parameter-variable relationships. Applied to paediatric sepsis, the framework reproduces warm and cold shock phenotypes while exposing infeasible target combinations, while providing efficient calibration and physiological insight.

physiology↗

bioRxiv2019

Physiological Adaptability and Parametric Versatility in a Simple Genetic Circuit

The intimate relationship between the environment and cellular growth rate has remained a major topic of inquiry in bacterial physiology for over a century. Now, as it becomes possible to understand how the growth rate dictates the wholesale reorganization of the intracellular molecular composition, we can interrogate the biophysical principles underlying this adaptive response. Regulation of gene expression drives this adaptation, with changes in growth rate tied to the activation or repression of genes covering enormous swaths of the genome. Here, we dissect how physiological perturbations alter the expression of a circuit which has been extensively characterized in a single physiological state. Given a complete thermodynamic model, we map changes in physiology directly to the biophysical parameters which define the expression. Controlling the growth rate via modulating the available carbon source or growth temperature, we measure the level of gene expression from a LacI-regulated promoter where the LacI copy number is directly measured in each condition, permitting parameter-free prediction of the expression level. The transcriptional output of this circuit is remarkably robust, with expression of the repressor being largely insensitive to the growth rate. The predicted gene expression quantitatively captures the observations under different carbon conditions, indicating that the bio-physical parameters are indifferent to the physiology. Interestingly, temperature controls the expression level in ways that are inconsistent with the prediction, revealing temperature-dependent effects that challenge current models. This work exposes the strengths and weaknesses of thermodynamic models in fluctuating environments, posing novel challenges and utility in studying physiological adaptation. SignificanceCells adapt to changing environmental conditions by repressing or activating gene expression from enormous fractions of their genome, drastically changing the molecular composition of the cell. This requires the concerted adaptation of transcription factors to the environmental signals, leading to binding or releasing of their cognate sequences. Here, we dissect a well characterized genetic circuit in a number of physiological states, make predictions of the response, and measure how the copy number of a regulator and its gene target are affected. We find the parameters defining the regulators behavior are remarkably robust to changes in the nutrient availability, but are susceptible to temperature changes. We quantitatively explore these two effects and discuss how they challenge current models of transcriptional regulation.

biophysics↗

bioRxiv2020

A High Throughput Gravimetric Phenotyping Platform for Real Time Physiological Screening of Plant Environment Dynamic Responses

Food security for the growing global population is a major concern. The data provided by genomic tools far exceeds the supply of phenotypic data, creating a knowledge gap. To meet the challenge of improving crops to feed the growing global population, this gap must be bridged. Physiological traits are considered key functional traits in the context of responsiveness or sensitivity to environmental conditions. Many recently introduced high-throughput phenotyping techniques are based on remote sensing or imaging and are capable of directly measuring morphological traits, but measure physiological parameters only indirectly. This paper describes a method for direct physiological phenotyping that has several advantages for the functional phenotyping of plant-environment interactions. It aims to help users overcome the many challenges encountered in the use of load-cell gravimetric systems and pot experiments. The suggested techniques will enable users to distinguish between soil weight, plant weight and soil water content, providing a method for continuous and simultaneous measurement of dynamic soil, plant and atmosphere conditions, alongside key physiological traits. This method allows researchers to closely mimic field stress scenarios while taking into consideration the environments effect on the plants physiology. This method also minimizes pot effects, which are one of the major problems in pre-field phenotyping. It includes a feedback fertigation system that enables a truly randomized experimental design with a field-like plant density. This system detects the soil-water content limiting threshold ({theta}) and allows for the translation of data into knowledge through the use of a real-time analytic tool and an online statistical resource. This method for the rapid and direct measurement of the physiological responses of multiple plants to a dynamic environment has great potential for use in screening for beneficial traits associated with responses to abiotic stress, in the context of pre-field breeding and crop improvement. SUMMARYThis high-throughput, whole-plant water relations gravimetric phenotyping method enables direct and simultaneous real-time measurements and analysis of multiple yield-related physiological traits involved in dynamic plant-environment interactions.

plant biology↗

bioRxiv2021

Global change differentially modulates coral physiology and suggests future shifts in Caribbean reef assemblages

Global change driven by anthropogenic carbon emissions is altering ecosystems at unprecedented rates, especially coral reefs, whose symbiosis with algal endosymbionts ise particularly vulnerable to increasing ocean temperatures and altered carbonate chemistry. Here, we assess the physiological responses of the coral holobiont (animal host + algal symbiont) of three Caribbean coral species from two reef environments after exposure to simulated ocean warming (28, 31 {degrees}C), acidification (300 - 3290 atm), and the combination of stressors for 93 days. We used multidimensional analyses to assess how multiple coral holobiont physiological parameters respond to ocean acidification and warming. Our results demonstrate significantly diminishing holobiont physiology in S. siderea and P. astreoides in response to projected ocean acidification, while future warming elicited severe declines in P. strigosa. Offshore S. siderea fragments exhibited higher physiological plasticity than inshore counterparts, suggesting that this offshore population has the capacity to modulate their physiology in response to changing conditions, but at a cost to the holobiont. Plasticity of P. strigosa and P. astreoides was not clearly different between natal reef environments, however, temperature evoked a greater plastic response in both species. Interestingly, while these species exhibit unique physiological responses to ocean acidification and warming, when data from all three species are modeled together, convergent stress responses to these conditions are observed, highlighting the overall sensitivities of tropical corals to these stressors. Our results demonstrate that while ocean warming is a severe acute stressor that will have dire consequences for coral reefs globally, chronic exposure to acidification may also impact coral physiology to a greater extent than previously assumed. The variety of responses to global change we observe across species will likely manifest in altered Caribbean reef assemblages in the future.

ecology↗

bioRxiv2021

Performance of temporal and spatial ICA in identifying and removing low-frequency physiological and motion effects in resting-state fMRI

Effective separation of signal from noise (including physiological processes and head motion) is one of the chief challenges for improving the sensitivity and specificity of resting-state fMRI (rs-fMRI) measurements and has a profound impact when these noise sources vary between populations. Independent component analysis (ICA) is an approach for addressing these challenges. Conventionally, due to the lower amount of temporal than spatial information in rs-fMRI data, spatial ICA (sICA) is the method of choice. However, with recent developments in accelerated fMRI acquisitions, the temporal information is becoming enriched to the point that the temporal ICA (tICA) has become more feasible. This is particularly relevant as physiological processes and motion exhibit very different spatial and temporal characteristics when it comes to rs-fMRI applications, leading us to conduct a comparison of the performance of sICA and tICA in addressing these types of noise. In this study, we embrace the novel practice of using theory (simulations) to guide our interpretation of empirical data. We find empirically that sICA can identify more noise-related signal components than tICA. However, on the merit of functional-connectivity results, we find that while sICA is more adept at reducing whole-brain motion effects, tICA performs better in dealing with physiological effects. These interpretations are corroborated by our simulation results. The overall message of this study is that if ICA denoising is to be used for rs-fMRI, there is merit in considering a hybrid approach in which physiological and motion-related noise are each corrected for using their respective best-suited ICA approach. Impact StatementResting-state fMRI is influenced by low-frequency physiological noise and head motion. Independent component analysis (ICA) is becoming increasingly relied on for reducing these influences, but the utility of spatial and temporal ICA remains unclear. We conducted a comparison of the performance of these two ICA types, using physiological-noise and motion time courses as reference. We found that spatial ICA is more adept at reducing motion effects, while temporal ICA performs better in dealing with physiological effects. We believe these findings provide much-needed clarity on the role of ICA, and recommend using a hybrid of tICA and sICA as a paradigm shift in resting-state fMRI.

neuroscience↗

bioRxiv2023

Physiological phenotypes differ among color morphs in introduced populations of the common wall lizard, Podarcis muralis

Many species exhibit color polymorphisms which have distinct physiological and behavioral characteristics. However, the consistency of morph trait covariation patterns across species, time, and ecological contexts remains unclear. This trait covariation is especially relevant in the context of invasion biology and urban adaptation. Specifically, physiological and behavioral traits pertaining to energy maintenance are crucial to fitness, given their immediate ties to individual reproduction, growth, and population establishment. We investigated the physiological and behavioral traits of Podarcis muralis, a versatile color polymorphic species that thrives in urban environments (including invasive populations in Ohio, USA). We measured five physiological and behavioral traits (circulating corticosterone and triglycerides, hematocrit, body condition, and field body temperature) which compose an integrated multivariate phenotype. We then tested variation among stable color polymorphisms in the context of establishment in an urban environment. We found that the traits describing physiological status and strategy shifted across the active season in a morph-dependent manner-the white and yellow morphs exhibited clearly different multivariate physiological phenotypes, characterized primarily by differences in circulating corticosterone. This suggests that morphs have different strategies in physiological regulation, the flexibility of which is crucial to urban adaptation. The white-yellow morph exhibited an intermediate phenotype, suggesting an intermediary energy maintenance strategy. Orange morphs also exhibited distinct phenotypes, but the low prevalence of this morph in our study populations precludes clear interpretation. Our work provides insight into how differences among stable polymorphisms exist across axes of the phenotype and how this variation may aid in establishment within novel environments. O_QDEpigraph: "If you are only moved by color relationships, you are missing the point." - Mark Rothko, Latvian-American abstract painter C_QD

zoology↗

bioRxiv2023

Nutritional condition drives spatial variation in physiology of Antarctic lipid-storing copepods

Lipid-rich copepods form an essential link between primary producers and higher trophic levels in high-latitude oceans. These zooplankton can take advantage of ephemeral phytoplankton blooms to fuel development and reproduction. However, we have limited understanding of how the physiological condition of these animals varies in relation to environmental factors such as food availability. Due to high advection, it is likely that physiological plasticity, rather than local adaptation, is primarily responsible for physiological differences within a region. We use transcriptomics and other physiological metrics to understand how two species of copepods (Calanoides acutus and Calanus propinquus) vary across environmental gradients along the West Antarctic Peninsula. For the primarily herbivorous C. acutus, physiological separation between sampling locations appears to be driven by feeding status, and gene expression differences indicate differential expression of genes regulating lipid metabolism, reproduction, aerobic metabolism, and protein translation. For the more omnivorous C. propinquus, physiology and gene expression did not segregate as clearly by location, showed minimal signs of food deprivation at any location, and had a weaker relationship with chlorophyll compared to C. acutus. By comparing these results with concurrent starvation experiments, we find thatspatial variation in gene expression reflects short-term differences in food availability (particularly for C. acutus,), and we identify genes whose expression indicates recent feeding status. Further examination of the relationships between food availability, copepod physiology, and population dynamics will ultimately improve our capacity to predict how copepod populations will respond to rapidly changing environmental conditions in the West Antarctic Peninsula ecosystem.

ecology↗

bioRxiv2023

Proteomic and Physiological Signatures of Altitude Adaptation in a Myrsine coriacea Population under Common Garden Conditions

Plants exhibit phenotypic plasticity in response to environmental variations, which can lead to stable genetic and physiological adaptations if exposure to specific conditions is prolonged. Myrsine coriacea demonstrates this through its ability to thrive in diverse environments. The objective of the article is to investigate the adaptive responses of M. coriacea by cultivating plants from seeds collected at four different altitudes in a common garden experiment. Through integrated physiological and proteomic analyses, we identified 170 differentially accumulated proteins and observed significant physiological differences among the populations. The high-altitude population (POP1) exhibited a unique proteomic profile with significant down-regulation of proteins involved in carbon fixation and energy metabolism, suggesting a potential reduction in photosynthetic efficiency. Physiological analyses showed lower leaf nitrogen content, net CO2 assimilation rate, specific leaf area, and relative growth rate in stem height for POP1, alongside higher leaf carbon isotopic composition ({delta}13C) and leaf carbon (C) content. These findings provide insight into the complex interplay between proteomic and physiological adaptations in M. coriacea and underscore the importance of local adaptations. This study enhances our understanding of how altitude-specific selection pressures can shape plant molecular biology and physiology, offering valuable perspectives for predicting plant responses to global environmental changes. HighlightThis study unveils proteomic and physiological adaptations in a high-altitude M. coriacea population with reduced carbon fixation and energy metabolism.

plant biology↗

bioRxiv2025

Host Physiology Dependent Lysis Timing Shapes Bacteriophage Competition Under Nutrient Fluctuations

When bacteriophages infect starved host bacteria, the restrictive host physiology may lead to prolonged latent periods and/or reduced burst sizes, compared to infection of a fast-growing bacterium. Using a mathematical model, we explore a system of two types of virulent phages that have distinct host physiology dependencies and are infecting a shared bacterial host population. We consider different environmental regimes to test whether they can compete and coexist under fluctuating conditions, putting emphasis on phases with limited resources for bacterial growth. We find that the fitness of a phage that can modulate lysis timing in response to changes in the host physiology is elevated in fluctuating feast-famine environments compared to more stable environments which favor rapid lysis with a reduced burst size. This effect is closely coupled to the increased mortality of free phages due to abortive adsorption to already infected host bacteria during starvation phases. We identify specific system dynamics that either support or suppress the propagation of the delayed lysis phage. This theoretical analysis highlights the competitive benefits and limitations of lysis delay as a phage propagation strategy. Our results underscore the importance of considering the bacterial physiology dependence of bacteriophage replication in order to correctly predict phage fitness and population dynamics in complex environments. IMPORTANCEBacteriophage replication depends strongly on the physiological state of the host, yet most ecological and theoretical studies treat phage life histories as fixed traits. This overlooks how nutrient limitation, starvation, and fluctuating growth conditions reshape infection outcomes. By examining competition between phages with different responses to host physiology, our work shows how environmentally driven changes in the latent period can alter which phages persist, spread, or are lost. These insights clarify when delayed lysis is a beneficial strategy and when it becomes a liability. More broadly, our results highlight the need to integrate host physiology into models of phage-host dynamics to better understand microbial ecosystems and to guide applications such as rational phage therapy design.

microbiology↗

bioRxiv2018

Motion and physiological noise effects on amygdala real-time fMRI neurofeedback learning

Real-time fMRI neurofeedback allows to learn control over activity in a localized brain region. However, with fMRI, physiological factors such as the cardiac cycle and respiration interfere with the measurement of brain activation. In conventional fMRI studies this is usually mitigated by inclusion of motion parameters and/or physiological parameters as nuisance regressors at the analysis stage, allowing to correct for and filter out such confounders. In real-time fMRI, however, such an approach is not routinely feasible due to the necessity to process all signals during the runtime of an experiment. The absence of on-line correction can therefore compromise real-time fMRI study outcomes reporting volitional self-regulation capability as BOLD signal changes. This is especially true for BOLD signal changes in subcortical regions situated close to blood vessels or air cavities, such as the amygdala. We therefore aimed to establish the effects of motion, heart rate, heart rate variability, and respiratory volume on learning effects, which means here an increase in BOLD signal change over NF training, in an amygdala neurofeedback experiment. Specifically, we investigate motion parameters from two emotion regulation studies - performed at 3T and 7T scanners - and additionally acquired physiological variance for the latter one. Our results revealed differences in these parameters between groups and especially between regulation and resting periods within each participant. However, strictly considering these parameters as nuisance regressors in data analysis revealed that the learning of volitional self-regulation of the amygdala is not driven by motion and physiological changes. As validation of our real-time findings, we compare them to the gold standard of assessment of motion and physiology from the Human Connectome Project. Based on this, we recommend to carefully report neurofeedback study results including physiological nuisance regression. To our knowledge, this is the first study investigating the effects of motion and physiological noise correction on neurofeedback BOLD effects.

neuroscience↗

bioRxiv2019

Identification of Physiological Response Functions to Correct for Fluctuations in Resting-State fMRI related to Heart Rate and Respiration

Functional magnetic resonance imaging (fMRI) is widely viewed as the gold standard for studying brain function due to its high spatial resolution and non-invasive nature. However, it is well established that changes in breathing patterns and heart rate strongly influence the blood oxygen-level dependent (BOLD) fMRI signal and this, in turn, can have considerable effects on fMRI studies, particularly resting-state studies. The dynamic effects of physiological processes are often quantified by using convolution models along with simultaneously recorded physiological data. In this context, physiological response function (PRF) curves (cardiac and respiratory response functions), which are convolved with the corresponding physiological fluctuations, are commonly employed. While it has often been suggested that the PRF curves may be region- or subject- specific, it is still an open question whether this is the case. In the present study, we propose a novel framework for the robust estimation of PRF curves and use this framework to rigorously examine the implications of using population-, subject-, session- and scan-specific PRF curves. The proposed framework was tested on resting-state fMRI and physiological data from the Human Connectome Project. Our results suggest that PRF curves vary significantly across subjects and, to a lesser extent, across sessions from the same subject. These differences can be partly attributed to physiological variables such as the mean and variance of the heart rate during the scan. The proposed methodological framework can be used to obtain robust scan-specific PRF curves from data records with duration longer than 5 minutes, exhibiting significantly improved performance compared to previously defined canonical cardiac and respiration response functions. Besides removing physiological confounds from the BOLD signal, accurate modeling of subject- (or session-/scan-) specific PRF curves is of importance in studies that involve populations with altered vascular responses, such as aging subjects.\n\nHighlightsO_LIPhysiological response functions (PRF) vary considerably across subjects/sessions\nC_LIO_LIScan-specific PRF curves can be obtained from data records longer than 5 minutes\nC_LIO_LIThe shape of the cardiac response function is linked to the mean heart rate (HR)\nC_LIO_LIBrain regions affected by HR and breathing patterns exhibit substantial overlap\nC_LIO_LIHR and breathing patterns affect distinct regions as compared to cardiac pulsatility\nC_LI

neuroscience↗

bioRxiv2026

Physiological load via voluntary wheel running maintains Achilles tendon homeostasis by region-specific cellular responses

Physiological load is vital for maintaining tendon homeostasis, preserving the organized extracellular matrix that enables tendons to withstand extreme forces. Although tenocytes are regarded as the primary regulators of extracellular matrix production, precisely how cells facilitate the maintenance of homeostasis in response to physiological load is poorly understood. Here, we used Voluntary Wheel Running (VWR) as a model of physiological load to delineate the specific cellular contributions to mouse Achilles tendon homeostasis. Eight weeks of VWR led to a smaller cross-sectional area, increased mechanical and material properties at the midsubstance, which corresponded to a decreased proportion of small (0-60 nm) collagen fibrils and an increased proportion of larger (100-60 nm) collagen fibrils compared to sedentary controls. Using Visium HD spatial transcriptomics, we identified region-specific cell clusters (insertion vs. midsubstance). In response to physiological load, cells in the insertion and midsubstance upregulate distinct genes that reinforce the fibrocartilage interface and collagen-rich tendon matrix, respectively. Notably, Clu, Myoc, and Ccdc80 were upregulated with VWR in the midsubstance, with previously uncharacterized roles in tendon homeostasis. Together, our findings suggest that in response to physiological load, tendon cells maintain homeostasis by region-specific responses. Given that insertional and midsubstance tendinopathy is function-limiting and painful, defining the region-specific cellular responses will be key to advancing therapeutic prospects for tendon health. New and NoteworthyThis study is the first spatially rigorous characterization of the tendon response to physiological load using a Voluntary Wheel Running (VWR) model. VWR led to smaller, stronger, but not stiffer tendons at the midsubstance compared to sedentary controls. This corresponded with significant decreased proportion of small collagen fibrils and a shift toward an increased proportion of large collagen fibrils. Using Visium HD spatial transcriptomics, we identified region-specific transcriptional responses to physiological load that maintain homeostasis. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=67 SRC="FIGDIR/small/722285v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@13aa717org.highwire.dtl.DTLVardef@1afe3f1org.highwire.dtl.DTLVardef@9e1137org.highwire.dtl.DTLVardef@17c47bc_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2026

Physiological Oscillations of Lateral Ventricular Volume Revealed by Fast fMRI: Effects of Aging and Vigilance

Abstract Background: Cyclic ventricular deformation may contribute to CSF displacement. However, the physiological mechanisms underlying ventricular motion remain poorly understood. This study characterized physiological oscillations of lateral ventricular volume (LVV) and examined their associations with aging and vigilance. Methods: We analyzed two fast resting-state fMRI scans from 99 adults aged 35-82 years. The first scan was acquired during eyes-open wakefulness, followed by 30 min of eyes-closed rest and a second scan during eyes-closed drowsiness. LVV was estimated for each image volume using automated ventricular segmentation, yielding time-resolved volume measurements. Temporal variability was quantified using the standard deviation and coefficient of variation, and spectral power was quantified for low-frequency, respiratory, and cardiac oscillations. Age-related associations were assessed using multiple linear regression adjusted for sex. Awake-drowsy differences were assessed using paired t-tests. False discovery rate correction was applied for multiple comparisons in all analyses. Results: After quality-control exclusions, 97 participants were analyzed. LVV exhibited distinct low-frequency, respiratory, and cardiac oscillatory components. Respiratory and cardiac oscillations accounted for 37.7% and 38.4% of total physiological spectral power, respectively, compared with 23.9% for low-frequency oscillations. Mean lateral ventricular volume increased with age (FDR-adjusted p = 0.010), while respiratory and cardiac power also showed positive associations with age, although neither survived FDR correction (both FDR-adjusted p = 0.067). The transition to eyes-closed drowsiness was associated with greater LVV fluctuation magnitude, reflected by increases in standard deviation (FDR-adjusted p < 0.001) and coefficient of variation (FDR-adjusted p = 0.028) and accompanied by increased low-frequency (FDR-adjusted p < 0.001) and respiratory power (FDR-adjusted p = 0.015). Mean LVV and cardiac power did not change significantly between conditions. Conclusions: LVV exhibits prominent respiratory and cardiac oscillations in addition to low-frequency fluctuations, suggesting that ventricular dynamics reflect multiple physiological influences rather than a single dominant physiological driver. Aging was primarily associated with ventricular enlargement, whereas reduced vigilance was accompanied by increased LVV fluctuation magnitude, primarily reflected in increased low-frequency and respiratory power, without a change in mean LVV. Time-resolved LVV provides a complementary approach for investigating the physiological regulation of ventricular dynamics in health and disease. Keywords: Cerebrospinal fluid; Lateral ventricular volume; Fast fMRI; Physiological oscillations; Cardiac pulsation; Respiration; Low-frequency oscillations; Aging; Vigilance

bioengineering↗

bioRxiv2021

Associations between Infant-Mother Physiological Synchrony and 4- to 6-Month-Old Infants' Emotion Regulation

In this study we assessed whether physiological synchrony between infants and mothers contributes to infants emotion regulation following a mild social stressor. Infants between 4- to 6-months of age and their mothers were tested in the Face-to-Face-Still-Face paradigm, and were assessed for behavioral and physiological self-regulation during and following the stressor. Physiological synchrony was calculated from a continuous measure of respiratory sinus arrhythmia (RSA) enabling us to cross-correlate the infants and mothers RSA responses. Without considering physiological synchrony, the evidence suggested that infants distress followed the prototypical pattern of increasing during the Still Face episode and then decreasing during the Reunion episode. Once physiological synchrony was added to the model, we observed that infants emotion regulation improved if mother-infant synchrony was positive, but not if it was negative. This result was qualified further by whether or not infants suppressed their RSA response during the Still Face episode. In sum, these findings highlight how individual differences in infants physiological responses contribute significantly to their self-regulation abilities.

physiology↗

bioRxiv2022

The cost of sympatry: spatio-temporal patterns in leopard dietary and physiological responses to tiger competition in Rajaji Tiger Reserve, India

1.O_LIApex predators have critical roles in maintaining the structure of ecosystem functioning by controlling intraguild subordinate populations. Such dominant-subordinate interactions involve agonistic interactions including direct (death/displacement) or indirect (physiological and/or health implications) impacts on the subordinates. As these indirect effects are often mediated through physiological processes, it is important to quantify such responses for better understanding of population parameters. C_LIO_LIWe used a well-known sympatric large carnivore intraguild system involving tiger (Panthera tigris) and leopard (Panthera pardus) to understand the dietary and physiological responses under a spatio-temporal gradient of tiger competition pressures in Rajaji Tiger Reserve (RTR), a major source tiger population of the western Terai-Arc Landscape, India between 2015-2020. The park provided a natural experimental set-up for tiger competition with the eastern part (ERTR) having high tiger density and the western (WRTR) part with functionally no competition from tigers. C_LIO_LIWe conducted systematic faecal sampling in the winters of 2015 and 2020 from ERTR and WRTR to assess diet and physiological measures. Analyses of leopard-confirmed faeces suggest a dietary-niche separation as a consequence of tiger competition. In 2020, we found increased occurrence of large-bodied prey species without tiger competition in WRTR. Physiological measures followed the dietary responses where leopards with large-sized prey in diet showed higher fT3M and lower fGCM measures in WRTR. In contrast, ERTR leopards showed lower levels of fT3M as well as fGCM in 2020, possibly due to intense competition from tigers. Overall, these pattens strongly indicate a physiological cost of sympatry where competition with dominant tigers resulted in elevated nutritional stress. C_LIO_LIThe combination of the natural habitat providing unique experimental setup, spatio-temporal sampling strategy and multidisciplinary approaches provide critical conservation perspectives for leopards, particularly in the context of recent increase in tiger numbers across India. We recommend expansion of leopard monitoring and population estimation efforts to buffers, developing appropriate plans for human-leopard conflict mitigation and intensive efforts to understand leopard population dynamics patterns to ensure their persistence during the ongoing Anthropocene. C_LI

physiology↗

bioRxiv2023

Common types of microdebris affect the physiology of reef-building corals

Marine debris, particularly microdebris (< 1 mm) poses a potential threat to marine life, including reef-building corals. While previous research has mainly focused on the impact of single polymer microplastics, the effects of natural microdebris, composed of a mixture of materials, have not been explored. Therefore, this study aimed to assess the effects of different microdebris, originating from major sources of pollution, on reef-building corals. For this, we exposed two scleractinian coral species, Pocillopora verrucosa and Stylophora pistillata, known to frequently ingest microplastics, to four types of microdebris in an 8-week laboratory experiment: fragmented environmental plastic debris, artificial fibers from clothing, residues from the automobile sector consisting of tire wear, brake abrasion, and varnish flakes, a single polymer microplastic treatment consisting of polyethylene particles, and a microdebris-free control treatment. Specifically, we (I) compared the effects of the different microdebris on coral growth, necrosis, and photosynthesis, (II) investigated the difference between the microdebris mixtures and the exposure to the single polymer treatment, and (III) identified potential mechanisms causing species-specific effects by contrasting the feeding responses of the two coral species on microdebris and natural food. We show that the fibers and tire wear had the strongest effects on coral physiology, with P. verrucosa being more affected than S. pistillata. Both species showed increased volume growth in response to the microdebris treatments, accompanied by decreased calcification in P. verrucosa. Photosynthetic efficiency of the symbionts was enhanced in both species. The species-specific physiological responses might be attributed to feeding reactions, with P. verrucosa responding significantly more often to microdebris than S. pistillata. These findings highlight the effect of different microdebris on coral physiology and the need for future studies to use particle mixtures to better mimic naturally occurring microdebris and assess its effect on corals in more detail. HighlightsO_LIThe effects of major sources of microdebris pollution on coral physiology were compared. C_LIO_LIOverall, microdebris had only minor impacts on coral physiology. C_LIO_LIArtificial fibers and tire wear caused the strongest effect on coral physiology. C_LIO_LISingle polymer and complex microdebris caused similar, yet species-specific effects. C_LIO_LISpecies-specific effects might be due to different feeding behaviors. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/569976v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@1ba7ba8org.highwire.dtl.DTLVardef@c5795org.highwire.dtl.DTLVardef@4a10deorg.highwire.dtl.DTLVardef@9983e5_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗