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Results for “Physiology”

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 Read source abstracts and check manuscript versions; preprints are not peer reviewed.

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At least 289 records · Page 16Linked to original sources

bioRxiv2022

Associations between locus coeruleus MRI contrast and physiological responses to acute stress in younger and older adults

Acute stress activates the brains locus coeruleus (LC)-noradrenaline system. Recent studies indicate that a magnetic resonance imaging (MRI)-based measure of LC structure is associated with better cognitive outcomes in later life. Yet despite the LCs documented role in promoting physiological arousal during acute stress, no studies have examined whether MRI-assessed LC structure is related to arousal responses to acute stress. In this study, 102 younger and 51 older adults completed an acute stress induction task while we assessed multiple measures of physiological arousal (heart rate, breathing rate, systolic and diastolic blood pressure, sympathetic tone, and heart rate variability, HRV). We used turbo spin echo MRI scans to quantify LC MRI contrast as a measure of LC structure. We applied univariate and multivariate approaches to assess how LC MRI contrast was associated with arousal at rest and during acute stress reactivity and recovery. In older participants, having higher caudal LC MRI contrast was associated with greater stress-related increases in systolic blood pressure and decreases in HRV, as well as lower HRV during recovery from acute stress. These results suggest that having higher caudal LC MRI contrast in older adulthood is associated with more pronounced physiological responses to acute stress. Further work is needed to confirm these patterns in larger samples of older adults.

neuroscience↗

bioRxiv2022

Transcriptome profiling of barley and tomato shoot and root meristems unravels physiological variations underlying photoperiodic sensitivity

The average sowing date of crops in temperate climate zones has been shifted forwards by several days, resulting in a changed photoperiod regime at the emergence stage. In the present study, we performed a global transcriptome profiling of plant development genes in the seedling stage of root and shoot apical meristems of a photoperiod-sensitive species (barley) and a photoperiod insensitive species (tomato) in short-day conditions (8h). Variant expression indicated differences in physiological development under this short day-length regime between species and tissues. The barley tissue transcriptome revealed reduced differentiation compared to tomato. In addition, decreased photosynthetic activity was observed in barley, indicating a slower physiological development of shoot meristems than in tomatoes. The photomorphogenesis controlling cryptochrome gene cry1, with an effect on physiological differentiation, showed an underexpression in barley compared to tomato shoot meristems. This might lead to a cascade of suspended sink-source activities, which ultimately delay organ development and differentiation in barley shoot meristems under short photoperiods.

developmental biology↗

bioRxiv2022

Digital twins and hybrid modelling for simulation of physiological variables and stroke risk

One of the more interesting ideas for achieving personalized, preventive, and participatory medicine is the concept of a digital twin. A digital twin is a personalized computer model of a patient. So far, digital twins have been constructed using either mechanistic models, which can simulate the trajectory of physiological and biochemical processes in a person, or using machine learning models, which for example can be used to estimate the risk of having a stroke given a cross-section profile at a given timepoint. These two modelling approaches have complementary strengths which can be combined into a hybrid model. However, even though hybrid modelling combining mechanistic modelling and machine learning have been proposed, there are few, if any, real examples of hybrid digital twins available. We now present such a hybrid model for the simulation of ischemic stroke. On the mechanistic side, we develop a new model for blood pressure and integrate this with an existing multi-level and multi-timescale model for the development of type 2 diabetes. This mechanistic model can simulate the evolution of known physiological risk factors (such as weight, diabetes development, and blood pressure) through time, under different intervention scenarios, involving a change in diet, exercise, and certain medications. These forecast trajectories of the physiological risk factors are then used by a machine learning model to calculate the 5-year risk of stroke, which thus also can be calculated for each timepoint in the simulated scenarios. We discuss and illustrate practical issues with clinical implementation, such as data gathering and harmonization. By improving patients understanding of their body and health, the digital twin can serve as a valuable tool for patient education and as a conversation aid during the clinical encounter. As such, it can facilitate shared decision-making, promote behavior change towards a healthy lifestyle, and improve adherence to prescribed medications.

systems biology↗

bioRxiv2022

A coupled atrioventricular-aortic setup for in-vitro hemodynamic study of the systemic circulation: Design, Fabrication, and Physiological relevancy

In-vitro models of the systemic circulation have gained a lot of interest for fundamental understanding of cardiovascular dynamics and for applied hemodynamic research. In this study, we introduce a physiologically accurate in-vitro hydraulic setup that models the hemodynamics of the coupled atrioventricular-aortic system. This unique experimental simulator has three major components: 1) an arterial system consisting of a human-scale artificial aorta along with the main branches, 2) an artificial left ventricle (LV) sac connected to a programmable piston-in-cylinder pump for simulating cardiac contraction and relaxation, and 3) an artificial left atrium (LA). The setup is designed in such a way that the basal LV is directly connected to the aortic root via an aortic valve, and to the LA via an artificial mitral valve. As a result, two-way hemodynamic couplings can be achieved for studying the effects that the LV, aorta, and LA have on each other. The collected pressure and flow measurements from this setup demonstrate a remarkable correspondence to clinical hemodynamics. We also investigate the physiological relevancies of isolated effects on cardiovascular hemodynamics of various major global parameters found in the circulatory system, including LV contractility, LV preload, heart rate, aortic compliance, and peripheral resistance. Subsequent control over such parameters ultimately captures physiological hemodynamic effects of LV systolic dysfunction, preload (cardiac) diseases, and afterload (arterial) diseases. The detailed design and fabrication of the proposed setup is also provided.

bioengineering↗

bioRxiv2022

Physiological and transcriptional profiling of surfactin exerted antifungal effect against Candida albicans

Given the risk of Candida albicans overgrowth in the gut, novel complementary therapies should be developed to reduce fungal dominancy. This study highlights the antifungal characteristics of a Bacillus subtilis-derived secondary metabolite, surfactin with high potential against C. albicans. Surfactin inhibited the growth of C. albicans following a 1-hour exposure, in addition to reduced adhesion and morphogenesis. Specifically, surfactin did not affect the level of reactive oxygen species but increased the level of reduced glutathione. Surprisingly, ethanol production enhanced following 2 hours of surfactin exposure. Surfactin treatment caused a significant reduction in intracellular iron, manganese and zinc content compared to control cells, whereas the level of copper was not affected. Alongside these physiological properties, surfactin also enhanced fluconazole efficacy. To gain detailed insights into the surfactin-related effects on C. albicans, genome-wide gene transcription analysis was performed. Surfactin treatment resulted in 1390 differentially expressed genes according to total transcriptome sequencing (RNA-Seq). Of these, 773 and 617 genes with at least a 1.5-fold increase or decrease in transcription, respectively, were selected for detailed investigation. Several genes involved in morphogenesis or related to metabolism (e.g., glycolysis, fermentation, fatty acid biosynthesis) were down-regulated. Moreover, surfactin decreased the expression of ERG1, ERG3, ERG9, ERG10 and ERG11 involved in ergosterol synthesis, whereas genes associated with ribosome biogenesis and iron metabolism and drug transport-related genes were up-regulated. Our data demonstrate that surfactin significantly influences the physiology and gene transcription of C. albicans, and could contribute to the development of a novel innovative complementary therapy. ImportanceAlthough gut colonization by Candida albicans can be considered normal, it may be associated with intestinal diseases. Furthermore, Candida dominance in the gut may pose a potent risk for systemic candidiasis, especially for immunocompromised individuals. In recent years, interest has been growing for the use of Bacillus subtilis as a safe and effective probiotic for human healthcare. Surfactin is a B. subtilis-derived lipopeptide with potential antifungal activity; however, the mechanism underlying this remains unknown. In this study, surfactin negatively affected the adherence, morphogenesis and metabolism of C. albicans and increased ethanol production. These were associated with a reduction in intracellular iron, manganese and zinc while the copper content was not affected. Alongside these physiological modulations, surfactin also had a potent synergistic effect on fluconazole. Our results provide a definitive explanation for the surfactin-related antifungal effect of B. subtilis; furthermore, these data provide a good basis for future probiotic development.

microbiology↗

bioRxiv2022

Digital whole-community phenotyping to assess morphological and physiological features of plant communities in the field

Traits link observable patterns in plants to ecosystem functions and processes and help to derive general rules and predictions about responses to environmental gradients, global change and perturbations. Ecological field studies often use manual low-throughput methods to assess plant phenotypes and integrate species-specific traits to community-wide indices. In contrast, greenhouse or lab-based studies, mostly in agriculture, employ high-throughput phenotyping for plant individuals to track their growth or fertilizer and water demand. We customized an automated plant phenotyping system (PlantEye F500, Phenospex, Heerlen, The Netherlands) for its mobile application in the field for digital whole-community phenotyping (DWCP). By scanning whole plant communities, we gather, within seconds and non-invasively, multispectral and physiological information while simultaneously capturing the 3-dimensional structure of the vegetation. We demonstrated the potential of DWCP by tracking plant community responses to experimental land-use treatments over two years. DWCP captured short- and long-term changes in morphological and physiological plant community properties in response to mowing and fertilizer treatments and thus reliably informed about changes in land-use. In contrast, manually measured community-weighted mean traits and species composition remained largely unaffected and were not informative about these treatments. Thus, DWCP proved to be an efficient method to measure morphological and physiological characteristics of plant communities, complements other methods in trait-based ecology, provides indicators of ecosystem states, and may help to forecast tipping points in plant communities often associated with irreversible changes in ecosystems.

ecology↗

bioRxiv2022

Physiological Levels of Estrogen and Progesterone Modulate CR3 expression on, and Neisseria gonorrhoeae Infection of, Primary, Human, Cervical Epithelial Cells

Despite advances made in our understanding of Neisseria gonorrhoeae pathogenesis, factors dictating the divergent presentation of gonococcal disease observed between men and women, in vivo, remain unclear. Clinical data indicate that gonococcal pathogenesis of the female genital tract is influenced by steroid hormones. Notwithstanding, there are limited data addressing how steroid hormones modulate gonococcal pathogenesis. Hence, we investigated the effect(s) of physiological concentrations of estrogens and progestogens on N. gonorrhoeae viability and on complement-mediated infection of primary cervical cells. In contrast to previous studies that showed a bacteriostatic effect of non-physiological concentrations of steroid hormones on gonococci, our data indicate that physiological concentrations of estrogens and progestogens do not inhibit gonococcal growth in vitro or during infection of primary cervical cells. Estradiol promoted complement receptor 3 recruitment to the cervical cell surface and, thus, the ability of gonococci to associate with these cells. Progesterone-predominant assay conditions resulted in decreased expression of Opa proteins by gonococci, increased complement production by cervical cells, and increased iC3b opsonization of gonococci during cervical cell challenge. Collectively, our data support clinical observations and demonstrate that estrogens and progestogens distinctly modulate gonococcal cervical infection.

microbiology↗

bioRxiv2022

Integration and evaluation of magnetic stimulation in physiology setups

A large number of behavioral experiments have demonstrated the existence of a magnetic sense in many animal species. Further, studies with immediate gene expression markers have identified putative brain regions involved in magnetic information processing. In contrast, very little is known about the physiology of the magnetic sense and how the magnetic field is neuronally encoded. In vivo electrophysiological studies reporting neuronal correlates of the magnetic sense either have turned out to be irreproducible for lack of appropriate artifact controls or still await independent replication. Thus far, the research field of magnetoreception has little exploited the power of ex vivo physiological studies, which hold great promise for enabling stringent controls. However, tight space constraints in a recording setup and the presence of magnetizable materials in setup components and microscope objectives make it demanding to generate well-defined magnetic stimuli at the location of the biological specimen. Here, we present a solution based on a miniature vector magnetometer, a coil driver, and a calibration routine for the coil system to compensate for magnetic distortions in the setup. The magnetometer fits in common physiology recording chambers and has a sufficiently small spatial integration area to allow for probing spatial inhomogeneities. The coil-driver allows for the generation of defined non-stationary fast changing magnetic stimuli. Our ex vivo multielectrode array recordings from avian retinal ganglion cells show that artifacts induced by rapid magnetic stimulus changes can mimic the waveform of biological spikes on single electrodes. However, induction artifacts can be separated clearly from biological responses if the spatio-temporal characteristics of the artifact on multiple electrodes is taken into account. We provide the complete hardware design data and software resources for the integrated magnetic stimulation system.

neuroscience↗

bioRxiv2022

Mouse lemur transcriptomic atlas elucidates primate genes, physiology, disease, and evolution

Mouse lemurs (Microcebus spp.) are an emerging primate model organism. However, little is known about their genetics or cellular and molecular biology. In the accompanying paper, we used large-scale single cell RNA-sequencing of 27 organs and tissues to identify over 750 molecular cell types, characterize their full transcriptomic profiles, and study evolution of primate cell types. Here we use the atlas to characterize mouse lemur genes, mutations, physiology, and disease. We uncover thousands of previously unidentified lemur genes and hundreds of thousands of new splice junctions that globally define lemur gene structures and reveal over 85,000 primate splice junctions missing in mice. We systematically explore the lemur immune system, comparing the global expression profiles of key immune genes in health and disease, and molecular mapping of immune cell development, trafficking, and their local and global activation to infection. We characterize primate/lemur-specific physiology and disease including molecular features of the immune program, of lemur adipocytes that exhibit dramatic seasonal rhythms, and of metastatic endometrial cancer that resembles the human malignancy. We identify and describe the expression patterns of over 400 primate genes missing in mice, many with similar expression patterns in human and lemur and some implicated in human disease. Finally, we provide an experimental framework for reverse genetic analysis by identifying naturally-occurring nonsense (null) mutations in three primate genes missing in mice and analyzing their transcriptional phenotypes. This work establishes mouse lemur as a tractable primate model organism for genetic and molecular analysis, and it prioritizes primate genes, splice junctions, physiology, and disease for future study.

genetics↗

bioRxiv2022

Quantitative physiology and proteome adaptations of Bifidobacterium breve NRBB57 at near-zero growth rates

In natural environments, nutrients are usually scarce causing microorganisms to grow slow while staying metabolically active. These natural conditions can be simulated using retentostat cultivations. The present study describes the physiological and proteome adaptations of the probiotic Bifidobacterium breve NRBB57 from high (0.4 h-1) to near-zero growth rates. Lactose-limited retentostat cultivations were carried out for 21 days in which the bacterial growth rate progressively reduced to 0.00092 h-1, leading to a 3.4-fold reduction of the maintenance energy requirement. Lactose was mainly converted into acetate, formate and ethanol at high growth rates while in the retentostat lactate production increased. Interestingly, the consumption of several amino acids (serine, aspartic acid and glutamine/arginine) and glycerol increased over time in the retentostat. Morphological changes and viable but non-culturable cells were also observed in the retentostat. Proteomes were compared for all growth rates, revealing a down-regulation of ribosomal proteins at near-zero growth rates and an up-regulation of proteins involved in the catabolism of alternative energy sources. Finally, we observed induction of the stringent response and stress defence systems. Retentostat cultivations were proven useful to study the physiology of B. breve, mimicking the nutrient scarcity of its complex habitat, the human gut. IMPORTANCEIn natural environments, nutrients are usually scarce causing microorganisms to grow slow while staying metabolically active. In this study we used retentostat cultivation to investigate how the probiotic Bifidobacterium breve adapts its physiology and proteome under severe nutrient limitation resulting in near-zero growth rates (<0.001 h-1). We showed that the nutrient limitation induced a multifaceted response including stress defence and stringent response, metabolic shifts and the activation of novel alternative energy producing pathways.

microbiology↗

bioRxiv2022

Differential gene expression analysis and physiological response characteristics of passion fruit (Passiflora edulis) buds under high-temperature stress

High temperature in summer is an unfavorable factor for passion fruit (Passiflora edulis), which can lead to restricted growth, short flowering period, few flower buds, low fruit setting rate, severe fruit drop, and more deformed fruit. To explore the molecular physiology mechanism of passion fruit responding to high-temperature stress, we use Zhuangxiang Mibao, a hybrid passion fruit cultivar, as the test material. Several physiological indicators were measured and compared between high-temperature (average temperature 38{degrees}C) and nonmoral temperature (average temperature 25{degrees}C) conditions, including photosynthesis, chlorophyll fluorescence parameters, POD, SOD activity and malondialdehyde content. We performed RNA-seq analysis combined with biochemistry experiment to investigate the gene and molecular pathways that respond to high-temperature stress. The results showed that some physiological indicators in the high-temperature group, including the net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, and the maximum chemical quantum yield of PS||, were significantly lower than those of the control group. Malondialdehyde content was substantially higher than the control group, while superoxide dismutase and superoxide dismutase activities decreased to different degrees. Transcriptome sequencing analysis showed that 140 genes were up-regulated and 75 genes were down-regulated under high-temperature stress. GO and KEGG annotation analysis of differentially expressed genes revealed many metabolic pathways related to high-temperature stress. Further investigation revealed that 30 genes might be related to high-temperature stress, such as CAO, GSH, WRKY, and HSP, which have also been reported in other species. The results of real-time fluorescence quantitative PCR and RNA-seq of randomly selected ten genes are consistent, which suggests that the transcriptome sequencing results were reliable. Our study provides a theoretical basis for the mechanism of passion fruit response to high-temperature stress. Also, it gives a theoretical basis for the subsequent breeding of new heat-resistant passion fruit varieties.

plant biology↗

bioRxiv2022

Physiological constraints on the rapid dopaminergic modulation of striatal reward activity

While the contribution of dopaminergic (DA) neurons to associative learning is firmly established, their importance for influencing imminent behavior on short (subsecond) timescales is less clear. Mechanistically, it is thought that DA neurons drive these behavioral changes because of their ability to rapidly alter striatal spiking activity. However, due to limitations of previous approaches, the straightforward prediction that striatal spiking is rapidly influenced by physiologically relevant DA signals has not been rigorously tested. Here, we monitored changes in spiking responses in the ventral striatum while transiently reducing or increasing DA levels. Contrary to the predicted effect, neither spontaneous nor reward-evoked striatal spiking activity was strongly influenced by optogenetic manipulations, except when DA exceeded reward-matched levels. These findings challenge the view that DA plays a major role in rapidly influencing striatal activity. Finally, they suggest a need to distinguish between the modulatory functions of DA under physiological and supra-physiological conditions.

neuroscience↗

bioRxiv2022

Physiological Condition Dependent Changes in Ciliary GPCR Localization in the Brain

Primary cilia are small immotile cellular appendages which mediate diverse types of singling and are found on most mammalian cell types including throughout the central nervous system. Cilia are known to localize certain G protein-coupled receptors (GPCRs) and are critical for mediating the signaling of these receptors. Several of these neuronal GPCRs have recognized roles in feeding behavior and energy homeostasis. Heterologous cell line and model systems like C. elegans and Chlamydomonas have implicated both dynamic GPCR cilia localization and cilia length and shape changes as key for signaling. However, it is unclear if mammalian ciliary GPCRs utilize similar mechanisms in vivo and under what physiological conditions these processes may occur. Here, we use the ciliary GPCRs, melanin concentrating hormone receptor 1 (MCHR1) and neuropeptide-Y receptor 2 (NPY2R) as model ciliary receptors to determine if dynamic localization to cilia occurs. We tested physiological conditions in which these GPCRs have been implicated such as feeding behavior, obesity, and circadian rhythm. Cilia were imaged using confocal microscopy and analyzed with a computer assisted approach allowing for unbiased and high throughput analysis of cilia. We analyzed GPCR positive cilia, cilia frequency as well as cilia length and receptor occupancy. Interestingly we observed changes in ciliary length, receptor occupancy, and cilia frequency under different conditions, but no consistent theme across GPCRs or brain nuclei was observed. A better understanding of the subcellular localization dynamics of ciliary GPCRs could reveal unrecognized molecular mechanisms regulating behaviors like feeding. Significance StatementOften, primary cilia localize specific G protein-coupled receptors (GPCRs) for subcellular signaling. Cell lines and model systems have indicated that cilia deploy dynamic GPCR localization and change their shape or length to modulate signaling. We used mice to assess neuronal cilia GPCRs under physiological conditions associated with both the receptors known functions and ciliopathy clinical features like obesity. We show that certain cilia with specific GPCRs appear to dynamically alter their length while others appear relatively stable under these conditions. These results implicate multiple themes across cilia GPCR mediated signaling and indicate that not all cilia modulate GPCR signaling using the same mechanisms. These data will be important for potential pharmacological approaches to target cilia GPCR-mediated signaling.

neuroscience↗

bioRxiv2022

The circadian clock conveys thermal and photoperiodic cues to modulate EYES ABSENT via the neuropeptide PDF to regulate seasonal physiology

Organisms adapt to seasonal changes in photoperiod and temperature to survive; however, the mechanisms by which these signals are integrated in the brain are poorly understood. We previously reported that EYES ABSENT (EYA) in Drosophila shows higher levels in cold temperature or short photoperiod, and genetic ablation of eya in the fly brain inhibits reproductive dormancy, suggesting that EYA promotes winter physiology. Nevertheless, the mechanisms by which EYA senses seasonal cues are unclear. Pigment-Dispersing Factor (PDF) is a neuropeptide important for photoentrainment and regulation of circadian output rhythms. Interestingly, PDF also regulates reproductive dormancy, suggesting that it may mediate the function of the circadian clock in modulating seasonal physiology. In this study, we investigated the role of PDF signaling in mediating the impact of EYA on seasonal biology. First, we subjected flies to different photoperiodic and temperature regimes and observed that PDF abundance is lower in cold and short days, compared to warm and long days. Interestingly, the response of PDF to seasonal cues is opposite of what was observed for EYA. We then determined the potential for PDF to convey seasonal cues and modulate EYA function in seasonality by assessing coexpression of EYA and PDF receptor. Our results indicated that PDF receptor (PDFR) is indeed coexpressed with EYA in the fly brain, including in the circadian clock neuronal network and neurons in the pars intercerebralis. We then manipulated PDF signaling in eya+ cells to show that PDF modulates seasonal adaptations in daily activity rhythm and ovary development via EYA-dependent and independent mechanisms. At the molecular level, manipulating PDF signaling impacted EYA protein abundance. Specifically, we showed that protein kinase A (PKA), an effector of PDF signaling, phosphorylates EYA and promotes its degradation. This explains the opposite responses of PDF and EYA abundance to changes in seasonal cues. In summary, our results support a model in which PDF signaling negatively modulates EYA levels to regulate seasonal physiology, linking the circadian clock to the modulation of seasonal adaptations.

neuroscience↗

bioRxiv2022

Identification of genomic regions of dry bean (Phaseolus vulgaris L.) associated with agronomic and physiological traits under drought stressed and well-watered conditions using genome-wide association study

Understanding the genetic basis of traits of economic importance under drought stress (DS) and well-watered (NS) conditions is important in enhancing genetic gains in dry beans (Phaseolus vulgaris L.). This research aims to: (i) identify markers associated with agronomic and physiological traits for drought tolerance and (ii) identify drought-related putative candidate genes within the mapped genomic regions. An Andean and Mesoamerican diversity panel (AMDP) comprising of 185 genotypes was screened in the field under drought stress (DS) and well-watered (NS) conditions for two successive seasons. Agronomic and physiological traits, viz., days to 50% flowering (DFW), plant height (PH), days to physiological maturity (DPM), grain yield (GYD), 100-seed weight (SW), leaf temperature (LT), leaf chlorophyll content (LCC) and stomatal conductance (SC) were phenotyped. Principal component and association analysis were conducted using filtered 9370 Diversity Arrays Technology sequencing (DArTseq) markers. The mean PH, GYD, SW, DPM, LCC and SC of the AMDP was reduced by 12.1, 29.6, 10.3, 12.6, 28.5 and 62.0%, respectively under DS. Population structure analysis revealed two sub-populations, which correspond to the Andean and Mesoamerican gene pools. Markers explained 0.08 - 0.10, 0.22 - 0.23, 0.29 - 0.32, 0.43 - 0.44, 0.65 - 0.66 and 0.69 - 0.70 of the total phenotypic variability (R2) for SC, LT, PH, GYD, SW and DFW, respectively under DS conditions. For NS, R2 varied from 0.08 (LT) to 0.70 (DPM). Overall, 68 significant (p < 10-03) marker-trait associations (MTAs) and 22 putative candidate genes were identified across DS and NS conditions. Most of the identified genes had known biological functions related to regulating the response to moisture stress. The findings provide new insights into the genetic architecture of moisture stress tolerance in common bean. The findings also provide potential candidate SNPs and putative genes that can be utilized in gene discovery and marker-assisted breeding for drought tolerance after validation.

genetics↗

bioRxiv2022

DRG afferents that mediate physiologic and pathologic mechanosensation from the distal colon

The properties of dorsal root ganglia (DRG) neurons that innervate the distal colon are poorly defined, hindering our understanding of their roles in normal physiology and gastrointestinal disease. Here, we report genetically defined subsets of colon innervating DRG neurons with diverse morphologic and physiologic properties. Four colon innervating DRG neuron populations are mechanosensitive and exhibit distinct force thresholds to colon distension. The highest threshold population, selectively labeled using Bmpr1b genetic tools, is necessary and sufficient for behavioral responses to high colon distension, which is partly mediated by the mechanosensory ion channel Piezo2. This HTMR population mediates behavioral over-reactivity to colon distension caused by inflammation in a model of inflammatory bowel disease. Thus, like cutaneous mechanoreceptor populations, colon innervating DRG afferents exhibit distinct anatomical and physiological properties and tile force threshold space, and genetically defined colon innervating HTMRs mediate pathophysiological responses to colon distension revealing a target population for therapeutic intervention.

neuroscience↗

bioRxiv2022

Quantifying physiological trait variation with automated hyperspectral imaging in rice

Advancements in hyperspectral imaging (HSI) and establishment of dedicated plant phenotyping facilities have enabled researchers to gather large quantities of plant spectral images with the aim of inferring target phenotypes non-destructively. However, large volumes of data that result from HSI and corequisite specialized methods for analysis may prevent plant scientists from taking full advantage of these systems. Here, we explore estimation of physiological traits in 23 rice accessions using an automated HSI system. Under contrasting nitrogen conditions, HSI data are used to classify treatment groups with [≥] 83% accuracy by utilizing support vector machines. Out of the 14 physiological traits collected, leaf-level nitrogen content (N, %) and carbon to nitrogen ratio (C:N) could also be predicted from the hyperspectral imaging data with normalized root mean square error of predictions smaller than 14% (R2 of 0.88 for N and 0.75 for C:N). This study demonstrates the potential of using an automated HSI system to analyze genotypic variation for physiological traits in a diverse panel of rice; to help lower barriers of application of hyperspectral imaging in the greater plant science research community, analysis scripts used in this study are carefully documented and made publicly available. HIGHLIGHTData from an automated hyperspectral imaging system are used to classify nitrogen treatment and predict leaf-level nitrogen content and carbon to nitrogen ratio during vegetative growth in rice.

plant biology↗

bioRxiv2022

Physiology and mathematical modeling of immobilized Saccharomyces spp. in beer fermentation

There is an ever-increasing demand for reduction of unit operations and a growing interest in the physiology of yeasts used in beer fermentation. In this context, cell immobilization is an interesting alternative, since it reduces steps to separate biomass from fermented broth. Yet, physiological alterations in yeast metabolism caused by immobilization are still to be fully described. Thus, the main objective of this work was to evaluate the physiology of three brewers S. cerevisiae yeast strains (SY025, SY067 and SY001) immobilized on a porous cellulose-based support. Batch fermentations in malt extract 12 {degrees}P were carried out for all strains both in free and immobilized forms in order to compare kinetic parameters obtained from distinct process conditions. Mathematical modeling was performed following two viewpoints: modeling of fermentation kinetics by parameter estimation from experimental data and application of a reaction-diffusion model for estimation of substrate concentration gradient inside the immobilization support. Moreover, fermentations with different initial substrate and biomass concentrations were carried out using strain SY025, aiming to evaluate their influence over flavor compounds, using statistical models. Compared to free cells, immobilized yeasts showed both higher glycerol yield (SY025, 40%; SY067, 53%; SY001, 19%) and biomass yield in the system (SY025, 67%; SY067, 78%; SY001, 56%). On the other hand, free cells presented higher ethanol yields when compared to immobilized ones (SY025, 9%; SY067, 9%; and SY001, 13%). According to the model developed, a substrate gradient inside the support was predicted, but with low mass transfer limitations. KEY POINTSO_LIYeast immobilization not always hinder biomass growth, here it was stimulated. C_LIO_LIA classic kinetic model describes accurately immobilized yeast fermentations. C_LIO_LIPhysiology changes occur in immobilization even with low mass transfer limitations. C_LI

bioengineering↗