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bioRxiv2020

A chromosome-level genome assembly for the Eastern Fence Lizard (Sceloporus undulatus), a reptile model for physiological and evolutionary ecology

High-quality genomic resources facilitate population-level and species-level comparisons to answer questions about behavioral ecology, morphological and physiological adaptations, as well as the evolution of genomic architecture. Squamate reptiles (lizards and snakes) are particularly diverse in characteristics that have intrigued evolutionary biologists, but high-quality genomic resources for squamates are relatively sparse. Lizards in the genus Sceloporus have a long history as important ecological, evolutionary, and physiological models, making them a valuable target for the development of genomic resources. We present a high-quality chromosome-level reference genome assembly, SceUnd1.0, (utilizing 10X Genomics Chromium, HiC, and PacBio data) and tissue/developmental stage transcriptomes for the Eastern Fence Lizard, Sceloporus undulatus. We performed synteny analysis with other available squamate chromosome-level assemblies to identify broad patterns of chromosome evolution including the fusion of micro- and macrochromosomes in S. undulatus. Using this new S. undulatus genome assembly we conducted reference-based assemblies for 34 other Sceloporus species to improve draft nuclear genomes assemblies from 1% coverage to 43% coverage on average. Across these species, typically >90% of reads mapped for species within 20 million years divergence from S. undulatus, this dropped to 75% reads mapped for species at 35 million years divergence. Finally we use RNAseq and whole genome resequencing data to compare the three assemblies as references, each representing an increased level of sequencing, cost and assembly efforts: Supernova Assembly with data from10X Genomics Chromium library; HiRise Assembly that added data from HiC library; and PBJelly Assembly that added data from PacBio sequencing. We found that the Supernova Assembly contained the full genome and was a suitable reference for RNAseq, but the chromosome-level scaffolds provided by the addition of the HiC data allowed the reference to be used for other whole genome analysis, including synteny and whole genome association mapping analyses. The addition of PacBio data provided negligible gains. Overall, these new genomic resources provide valuable tools for advanced molecular analysis of an organism that has become a model in physiology and evolutionary ecology.

genomics↗

bioRxiv2020

Oscillating and stable genome topologies underlie hepatic physiological rhythms during the circadian cycle

The circadian clock drives extensive temporal gene expression programs controlling daily changes in behavior and physiology. In mouse liver, transcription factors dynamics, chromatin modifications, and RNA Polymerase II (PolII) activity oscillate throughout the 24-hour (24h) day, regulating the rhythmic synthesis of thousands of transcripts. Also, 24h rhythms in gene promoter-enhancer chromatin looping accompany rhythmic mRNA synthesis. However, how chromatin organization impinges on temporal transcription and liver physiology remains unclear. Here, we applied time-resolved chromosome conformation capture (4C-seq) in livers of WT and arrhythmic Bmal1 knockout mice. In WT, we observed 24h oscillations in promoter-enhancer contact at multiple loci including the core-clock genes Period1, Period2 and Bmal1. In addition, we detected rhythmic PolII activity, chromatin modifications and transcription involving stable chromatin loops at gene promoters representing key liver function such as glucose and lipid metabolism and detoxification. Intriguingly, these contacts persisted in clock-impaired mice in which both PolII activity and chromatin marks no longer oscillated. Finally, we observed chromatin interaction hubs connecting neighbouring genes showing coherent transcription regulation across genotypes. Thus, both clock-controlled and clock-independent chromatin topology underlie rhythmic regulation of liver physiology.

genomics↗

bioRxiv2020

Environmental and physiological factors affecting high-throughput measurements of bacterial growth

Bacterial growth in nutrient-rich and starvation conditions is intrinsically tied to the environmental history and physiological state of the population. While high-throughput technologies have enabled rapid analyses of mutant libraries, technical and biological challenges complicate data collection and interpretation. Here, we present a framework for the execution and analysis of growth measurements with improved accuracy over standard approaches. Using this framework, we demonstrate key biological insights that emerge from consideration of culturing conditions and history. We determined that quantification of the background absorbance in each well of a multi-well plate is critical for accurate measurements of maximal growth rate. Using mathematical modeling, we demonstrated that maximal growth rate is dependent on initial cell density, which distorts comparisons across strains with variable lag properties. We established a multiple-passage protocol that alleviates the substantial effects of glycerol on growth in carbon-poor media, and we tracked growth rate-mediated fitness increases observed during a long-term evolution of Escherichia coli in low glucose concentrations. Finally, we showed that growth of Bacillus subtilis in the presence of glycerol induces a long lag in the next passage due to inhibition of a large fraction of the population. Transposon mutagenesis linked this phenotype to the incorporation of glycerol into lipoteichoic acids, revealing a new role for these envelope components in resuming growth after starvation. Together, our investigations underscore the complex physiology of bacteria during bulk passaging and the importance of robust strategies to understand and quantify growth. Abstract ImportanceHow starved bacteria adapt to and multiply in replete nutrient conditions is intimately linked to their history of previous growth, their physiological state, and the surrounding environment. While automated equipment has enabled high-throughput growth measurements, data interpretation and knowledge gaps regarding the determinants of growth kinetics complicate comparisons between strains. Here, we present a framework for growth measurements that improves accuracy and attenuates the effects of growth history. We determined that background absorbance quantification and multiple passaging cycles allows for accurate growth-rate measurements even in carbon-poor media, which we used to reveal growth-rate increases during long-term laboratory evolution of Escherichia coli. Using mathematical modeling, we showed that maximum growth rate depends on initial cell density. Finally, we demonstrated that growth of Bacillus subtilis with glycerol inhibits the future growth of most of the population, due to lipoteichoic-acid synthesis. These studies highlight the challenges of accurate quantification of bacterial growth behaviors.

microbiology↗

bioRxiv2020

Are single peripheral measurements of baseline oxytocin in saliva and plasma reliable biomarkers of the physiology of the oxytocin system in humans?

BackgroundSingle measurements of salivary and plasmatic oxytocin are used as indicators of the physiology of the oxytocin system. However, questions remain about whether they are sufficiently stable to provide valid biomarkers of the physiology of the oxytocin system, and whether salivary oxytocin can accurately index its plasmatic concentrations. MethodsUsing radioimmunoassay, we measured baseline plasmatic and/or salivary oxytocin from two independent datasets. Dataset A comprised 17 healthy men sampled on four occasions approximately at weekly intervals. We administered exogenous oxytocin intravenously and intranasally in a triple dummy, within-subject, placebo-controlled design and compared baseline levels and the effects of routes of administration. Dataset B comprised baseline plasmatic oxytocin measurements from 20 healthy men sampled on two separate occasions. Additionally, in dataset A, we tested whether salivary oxytocin can predict plasmatic oxytocin at baseline and after intranasal and intravenous oxytocin administration. ResultsSingle measurements of plasmatic and salivary oxytocin showed poor reliability across visits in both datasets. Intranasal administration of exogenous oxytocin increases salivary oxytocin, but intravenous administration of a considerable dose does not produce any changes. Saliva and plasma oxytocin did not correlate at baseline or after administration of exogenous oxytocin. ConclusionsOur findings question the use of single measurements of baseline oxytocin concentrations in saliva and plasma as valid biomarkers of the physiology of the oxytocin system in humans. Salivary oxytocin is a weak surrogate for plasmatic oxytocin. The increases in salivary oxytocin observed after intranasal oxytocin most likely reflect unabsorbed peptide and should not be used to predict treatment effects.

neuroscience↗

bioRxiv2020

Programming animal physiology and behaviors through engineered bacteria

A central goal of synthetic biology is to predictably and efficiently reprogram living systems to perform computations and carry out specific biological tasks. Although there have been many advances in the bio-computational design of living systems, these advances have mainly been applied to microorganisms or cell lines; programming animal behavior and altering animal physiology remain challenges for synthetic biology because of the system complexity. Here, we present a bacteria-animal symbiont system in which engineered bacteria recognize external signals and modulate animal gene expression, twitching behavior, and fat metabolism through RNA interference. By using genetic circuits in bacteria to control RNA expression, we programmed the physiology and behavior of the model animal Caenorhabditis elegans with logic gates. We anticipate that engineered bacteria can be used more extensively to program animal metabolism and behaviors for agricultural, therapeutic, and basic science applications. One Sentence SummaryAnimal physiology and behaviors are programmed via engineered bacteria.

synthetic biology↗

bioRxiv2020

INFLUENCE OF SOME LEGUMINOUS TREES AND ARBUSCULAR MYCORRHIZAL FUNGI ON THE PHYSIOLOGY AND YIELD OF DIOSCOREA ROTUNDATA -POIR

This work compares the physiological and yield characteristics of white yam (Dioscorea rotundata - Poir) under Arbuscular mycorrhizal fungi (AMF) inoculation, green manures of Gliricidia sepium, Leucaena leucocephala and other soil amendments. The experiment was conducted on the plot of land that had been overcropped, located at the back of the male Hostel, Federal College of Education, Abeokuta, Ogun State, Nigeria. The land was cleared and heaped at 1m x 1m apart. The experimental design employed was a complete randomized design in 5 replicates. The treatments were Glomus deserticola (GD), Glomus fasciculatum (GF), Gliricidia sepium (GS), Leucaena leucocephala (LL), Poultry manure (PM) and NPK fertilizers. Soils were dug from the heaps, 20 g of the inoculums of AMF (GD/ GF) were poured into the dug hole, seeds were laid on it and covered with soil (for GD & GF treatments). Others were applied at one week after sprouting. Growth and yield Parameters were determined at harvest while relative water and chlorophyll contents were measured forth nightly from 10 weeks after treatment. Data obtained were subjected to ANOVA while means were separated by Duncan multiple range test at P> 0.05. Results showed that growth, yield and physiological characters were enhanced in GD, GD+GF, GS and PM treated plants more than in inorganic fertilizers treated plants. There was a positive significant relationship between white yams growth, physiology and tuber yield. The study justifies the use of plant/animal manures and Arbuscular mycorrhizal fungi in place of inorganic fertilizers.

ecology↗

bioRxiv2020

Physiological, Biochemical and Microstructural Changes in Rice (Oryza sativa L.) under Varying pH Levels

Soil acidification exerts detrimental effects on rice plant leading to severe reduction in its yield. In the present study, we investigated the physiological, biochemical and microstructural changes in the leaves of rice cultivars, namely, Jhilli Dhan (JD) and Gora Dhan (GD), under varying pH conditions (pH 6.5, 5.5, 4.5 and 3.5). Seedlings were grown at varying pH levels for 14 days under controlled conditions. Root and shoot growth and chlorophyll content were found to be decreased with increasing acidity, whereas electrolyte leakage was increased with increasing acidity. Overall, seedling growth was significantly reduced at pH 3.5, while, it was maximum at pH 6.5 treatment, which might be the result of cumulative altered physiological parameters. Further, biochemical parameters, namely total soluble sugar (TSS), proline content and lipid peroxidation were found to be positively correlated with acidity. Microstructural changes were observed through Swept-Source Optical Coherence Tomography (SS-OCT) and Field Emission Scanning Electron Microscope (FESEM). The thickness between different layers of leaves was found to be disintegrating at low pH conditions and the thickness of parenchyma cells was reduced significantly. FESEM analysis revealed changes in characteristics of stomata under acidic stress. The understanding of physiological, biochemical and microstructural changes in rice leaves under varying pH conditions may help in developing rice with improved tolerance towards soil acidity stress.

plant biology↗

bioRxiv2020

Synchrony in the periphery: inter-subject correlation of physiological responses during live music concerts

A concert is a common event at which people gather to share a musical experience. While techniques are increasingly offering insights into naturalistic stimuli perception, this study extended methods to a more ecological context in order to explore real-world music listening within a concert setting. Cardiorespiratory, skin conductance, and facial muscle responses were measured from participants attending one of three concerts with live chamber music performances of works of varying Western Classical styles (Viennese Classical, Contemporary, and Romantic). Collective physiological synchronisation of audience members was operationalised via inter-subject correlation (ISC). By assessing which musical features (obtained via Music Information Retrieval and music-theoretical analyses) evoked moments of high synchrony, logistic regressions revealed that tempo consistently predicted physiological synchrony across all concerts in Classical and Romantic styles, but not the Contemporary style. Highly synchronised responses across all three concert audiences seemed to occur during structural transitional passages, boundaries, and at phrase repetitions. The results support the idea that group synchronisation is linked to musical arousal, structural coherence, and familiarity. By employing physiological ISC and an inter-disciplinary musical analysis, the current study demonstrates a novel approach to gain valuable insight into experiences of naturalistic stimuli in an ecological context.

neuroscience↗

bioRxiv2020

Sleep-specific changes in physiological brain pulsations

Sleep is known to increase the convection of interstitial brain metabolites along with cerebrospinal fluid (CSF). We used ultrafast magnetic resonance encephalography (MREGBOLD) to quantify the effect of sleep on physiological (vasomotor, respiratory and cardiac) brain pulsations driving the CSF convection in humans. Transition to electroencephalography verified sleep occurred in conjunction with power increase and reduced spectral entropy (SE) of physiological brain pulsations. During sleep, the greatest increase in spectral power was in very-low frequency (VLF < 0.1 Hz) waves, followed by respiratory and cardiac brain pulsations. SE reduction coincided with decreased vigilance in awake state and could robustly (ROC 0.88, p < 0.001) differentiate between sleep vs. awake states, indicating the sensitivity of SE of the MREGBOLD signal as a marker for sleep level. In conclusion, the three physiological brain pulsation contribute to the sleep-associated increase in glymphatic CSF convective flow in an inverse frequency order. HighlightsO_LIBrain tissue contains almost no connective tissue, this enabling pressure waves to initiate long-distance brain pulsations C_LIO_LIBrain pulsations are induced by vasomotion, respiration, and the cardiac cycle C_LIO_LISleep strikingly increases spectral power and decreases spectral entropy of brain pulsations, especially for the very low frequency vasomotor waves C_LIO_LISpectral entropy of brain pulsations detected by MREG is a sensitive measure of vigilance, resembling the corresponding entropy changes detected by scalp EEG C_LI

neuroscience↗

bioRxiv2020

Amazonian soil metagenomes indicate different physiological strategies of microbial communities in response to land use change

Despite the global importance in ecological processes, the Amazon rainforest has been subjected to high rates of deforestation, mostly for pasturelands, over the last few decades. In this study, we used a combination of deep shotgun metagenomics and a machine learning approach to compare physiological strategies of microbial communities between contrasting forest and pasture soils. We showed that microbial communities (bacteria, archaea and viruses), and the composition of protein-coding genes are distinct in each ecosystem. The diversities of these metagenomic datasets are strongly correlated, indicating that the protein-coding genes found in any given sample of these soil types are predictable from their taxonomic lineages. Shifts in metagenome profiles reflected potential physiological differences caused by forest-to-pasture conversion with alterations in gene abundances related to carbohydrate and energy metabolisms. These variations in these gene contents are associated with several soil factors including C/N, temperature and H++Al3+ (exchangeable acidity). These data underscore that microbial community taxa and protein-coding genes co-vary. Differences in gene abundances for carbohydrate utilization, energy, amino acid, and xenobiotic metabolisms indicate alterations of physiological strategy with forest-to-pasture conversion, with potential consequences to C and N cycles. Our analysis also indicated that soil virome was altered and shifts in the viral community provide insights into increased health risks to human and animal populations.

microbiology↗

bioRxiv2020

Age- and sex- dependent changes in locus coeruleus physiology and anxiety-like behavior in response to acute stress

Adolescence is a critical period of development with increased sensitivity toward psychological stressors. Many psychiatric conditions emerge during adolescence and animal studies have shown that that acute stress has long-term effects on hypothalamic pituitary adrenal axis function and behavior. We recently demonstrated that acute stress produces long-term electrophysiological changes in locus coeruleus and long-lasting anxiety-like behavior in adolescent male rats. Based on prior reports of increased stress sensitivity during adolescence and increased sensitivity of female locus coeruleus toward corticotropin releasing factor, we hypothesized that the same acute stressor would cause different behavioral and physiological responses in adolescent female and adult male rats one week after stressor exposure. In this study, we assessed age and sex differences in how an acute psychological stressor affects corticosterone release, anxiety-like behavior, and locus coeruleus physiology at short- and long-term intervals. All groups of animals responded to stress with elevated corticosterone levels at the acute time point. One week after stressor exposure, adolescent females showed decreased firing of locus coeruleus neurons upon current injection and increased exploratory behavior compared to controls. The results were in direct contrast to changes observed in adolescent males, which showed increased anxiety-like behavior and increased spontaneous and induced firing locus coeruleus neurons a week after stressor exposure. Adult males were both behaviorally and electrophysiologically resilient to the long-term effects of acute stress. Therefore, there may be a normal developmental trajectory for locus coeruleus neurons which promotes stress resilience in adults, but stressor exposure during adolescence perturbs their function. Furthermore, while locus coeruleus neurons are more sensitive to stressor exposure during adolescence, the effect varies between adolescent males and females. These findings suggest that endocrine, behavioral, and physiological responses to stress vary among animals of different age and sex, and therefore these variables should be taken into account when selecting models and designing experiments to investigate the effects of stress. These differences in animals may also allude to age and sex differences in the prevalence of various psychiatric illnesses within the human population.

neuroscience↗

bioRxiv2020

Investigations into modifications of neuromuscular physiology by axonal transport disruptions in Drosophila SOD1 mutants

The reactive oxygen species (ROS)-scavenging enzyme Cu/Zn superoxide dismutase (SOD1) is an evolutionarily conserved mechanism for the maintenance of oxidative homeostasis, and missense mutations in the human SOD1 gene are associated with the motor neuron degenerative disease amyotrophic lateral sclerosis (ALS). Mutations in the Drosophila melanogaster SOD1 gene (Sod) shorten fly lifespan, attenuate motor function, and induce developmental mortality. We have previously found morphological and physiological defects at the neuromuscular junctions (NMJs) of hypomorphic Sodn108 and ALS model SodG85R mutant larvae. Here, we report genetic interactions causing striking modifications of Sod mutant phenotypes by mutations in the gene Prickle (Pk), which are linked to planar cell polarity, epilepsy, and axonal transport disruptions. Pk is expressed as two isoforms prickle-spiny-legs (sple) and prickle-prickle (pk), which are each suppressed by specific hypomorphic mutations (sple1 and pk1). Interestingly, Sod phenotypes are distinctly modified depending on both the Pk isoform suppressed, and whether said suppression is heterozygous or homozygous. Heterozygous sple1 and pk1 improved the developmental survival of Sod mutants, whereas homozygous sple1 and pk1 drastically increased mortality. Further, only heterozygous sple1 and pk1 clearly ameliorated morphological defects at the neuromuscular junctions of Sod mutant larvae. Pharmacological treatment of Sod mutants reveals allele-specific motor neuron terminal hyperexcitability, characterized by synaptic transmissions of extended duration and abnormal presynaptic Ca2+ transients. Heterozygous sple1 mutation suppresses this Sod mutant terminal hyperexcitability, but pk1 does not. We reversed this suppressive effect of sple1 by pharmacological blockade of Ca2+-activated K+ channel slowpoke. Altogether, this study builds on our prior knowledge of Sod mutant development and physiology to show that axonal transport-linked gene mutations strikingly modify Sod mutant phenotypes, providing strong evidence for a role of intracellular transport in alterations of neuromuscular morphology and physiology by SOD1 mutations.

neuroscience↗

bioRxiv2021

Trophic position derived from amino-acid nitrogen isotopes reflect physiological status of both predator and prey over four decades

Nitrogen isotope analyses of amino-acids ({delta}15N-AA) are increasingly used to decipher food webs. Interpretation of {delta}15N-AA in consumers relies on the assumption that physiological status has a negligible influence on the trophic enrichment factor (TEF). Recent experiments have shown that this is not always the case and there is a need to validate derived trophic position (TP) estimates using ecological data. We analyzed {delta}15N-AA in cod and herring (1980-2019) from the Baltic Sea, a species-poor system where dramatic reduction in condition status of cod has occurred. We expected that TEFcod-herring in trophic AAs would increase during periods of poor cod growth, resulting in inflated TP estimates. We found that TEF and TP estimates were negatively linked to individual condition status, prey fat content and the hypoxic state of the ecosystem. Statistically adjusting for these variables resulted in lower cod TP, highlighting the importance of including ecological knowledge when interpreting TP. Scientific Significance StatementNitrogen stable isotope analyses in amino acids are increasingly used in ecology to understand how environmental change impacts food-webs. Specifically, it is used to more accurately calculate trophic position (TP) of consumers. Controlled experiments have shown that physiological status can alter amino acid isotope composition and TP interpretation, but field studies are lacking. We use 40 years of archived material to demonstrate that TP estimates in Baltic Sea cod and its prey herring are directly related to physiological status. This has important implications for interpreting the real trophic ecology of consumers under environmental stress. By simultaneously measuring condition status in both predator and prey it is possible to adjust for them as confounding variables and decipher actual consumer TP.

ecology↗

bioRxiv2021

Physiology and ecology combine to determine host and vector importance for Ross River virus and other vector-borne diseases

Identifying the key vector and host species driving transmission is notoriously difficult for vector-borne zoonoses, but critical for disease control. Here, we present a general approach for quantifying the role hosts and vectors play in transmission that integrates species physiological competence with their ecological traits. We apply this model to the medically important arbovirus Ross River virus (RRV), in Brisbane, Australia. We found that vertebrate species with high physiological competence werent the most important for community transmission. Instead, we estimated that humans (previously overlooked as epidemiologically important hosts) potentially play an important role in RRV transmission, in part, because highly competent vectors readily feed on them and are highly abundant. By contrast, vectors with high physiological competence were also important for community transmission. Finally, we uncovered two potential transmission cycles: an enzootic cycle involving birds and an urban cycle involving humans. This modelling approach has direct application to other zoonotic arboviruses.

ecology↗

bioRxiv2021

Unravelling the Physiological Correlates of Mental Workload Variations in Tracking and Collision Prediction Tasks: Implications for Air Traffic Controllers

ObjectiveWe have designed tracking and collision prediction tasks to elucidate the differences in the physiological response to the workload variations in basic ATC tasks to untangle the impact of workload variations experienced by operators working in a complex ATC environment. BackgroundEven though several factors influence the complexity of ATC tasks, keeping track of the aircraft and preventing collision are the most crucial. MethodsPhysiological measures, such as electroencephalogram (EEG), eye activity, and heart rate variability (HRV) data, were recorded from 24 participants performing tracking and collision prediction tasks with three levels of difficulty. ResultsThe neurometrics of workload variations in the tracking and collision prediction tasks were markedly distinct, indicating that neurometrics can provide insights on the type of mental workload. The pupil size, number of blinks and HRV metric, root mean square of successive difference (RMSSD), varied significantly with the mental workload in both these tasks in a similar manner. ConclusionOur findings indicate that variations in task load are sensitively reflected in physiological signals, such as EEG, eye activity and HRV, in these basic ATC-related tasks. ApplicationThese findings have applicability to the design of future mental workload adaptive systems that integrate neurometrics in deciding not just when but also what to adapt. Our study provides compelling evidence in the viability of developing intelligent closed-loop mental workload adaptive systems that ensure efficiency and safety in ATC and beyond. PrecisThis article identifies the physiological correlates of mental workload variation in basic ATC tasks. The findings assert that neurometrics can provide more information on the task that contributes to the workload, which can aid in the design of intelligent mental workload adaptive system.

neuroscience↗

bioRxiv2021

Typical somatomotor physiology of the hand is preserved in a patient with an amputated arm

Electrophysiological signals in the human motor system may change in different ways after deafferentation, with some studies emphasizing reorganization while others propose retained physiology. Understanding whether motor electrophysiology is retained over longer periods of time can be invaluable for patients with paralysis (e.g. ALS or brainstem stroke) when signals from sensorimotor areas may be used for communication or control over neural prosthetic devices. In addition, a maintained electrophysiology can potentially benefit the treatment of phantom limb pains through prolonged use of these signals in a brain-machine interface (BCI). Here, we were presented with the unique opportunity to investigate the physiology of the sensorimotor cortex in a patient with an amputated arm using electrocorticographic (ECoG) measurements. While implanted with an ECoG grid for clinical evaluation of electrical stimulation for phantom limb pain, the patient performed attempted finger movements with the contralateral (lost) hand and executed finger movements with the ipsilateral (healthy) hand. The electrophysiology of the sensorimotor cortex contralateral to the amputated hand remained very similar to that of hand movement in healthy people, with a spatially focused increase of high-frequency band (65-175Hz; HFB) power over the hand region and a distributed decrease in low-frequency band (15-28Hz; LFB) power. The representation of the three different fingers (thumb, index and little) remained intact and HFB patterns could be decoded using support vector learning at single-trial classification accuracies of >90%, based on the first 1-3s of the HFB response. These results demonstrate that hand representations are largely retained in the motor cortex. The intact physiological response of the amputated hand, the high distinguishability of the fingers and fast temporal peak are encouraging for neural prosthetic devices that target the sensorimotor cortex.

neuroscience↗

bioRxiv2021

Physiological and transcriptomic variability indicative of differences in key functions within a single coral colony

Polyps in different locations on individual stony coral colonies experience variation in numerous environmental conditions including flow and light, potentially leading to transcriptional and physiological differences across the colony. Here, we describe high-resolution physiological measurements and differential gene expression from multiple locations within a single colony of Stylophora pistillata, aiming to relate these to environmental gradients across the coral colony. We observed broad transcriptional responses in both the host and photosymbiont in response to height above the substrate, cardinal direction, and, most strongly, location along the branch axis. Specifically, several key physiological processes in the host appear more active toward branch tips including several metabolic pathways, toxin production for prey capture or defense, and biomolecular mechanisms of biomineralization. Further, the increase in gene expression related to these processes toward branch tips is conserved between S. pistillata and Acropora spp. The photosymbiont appears to respond transcriptionally to relative light intensity along the branch and due to cardinal direction. These differential responses were observed across the colony despite its genetic homogeneity and likely inter-polyp communication. While not a classical division of labor, each part of the colony appears to have distinct functional roles related to polyps differential exposure to environmental conditions.

genomics↗

bioRxiv2021

Neuroanatomical organization and functional roles of PVN MC4R pathways in physiological and behavioral regulations

ObjectiveThe paraventricular nucleus of hypothalamus (PVN) is an integrative center in the brain orchestrating a wide range of physiological and behavioral responses. While the PVN melanocortin 4 receptor (MC4R) signaling (PVNMC4R+) is undoubtedly involved in feeding regulation, the neuroanatomical organization of PVNMC4R+ pathway and its role in diverse physiological and behavioral regulations have not been fully understood. Here we aimed to better characterize the input-output organization of PVNMC4R+ neurons and further test their potential functional roles beyond feeding. MethodsUsing a combination of viral tools, we performed a comprehensive mapping of PVNMC4R+ circuits and tested the effects of chemogenetic activation of PVNMC4R+ neurons on thermogenesis, cardiovascular control and other behavioral regulations beyond feeding. ResultsWe found that PVNMC4R+ neurons broadly innervate many different brain regions known to be important not only for feeding but also for neuroendocrine and autonomic control of thermogenesis and cardiovascular function, including but not limited to preoptic area, median eminence, parabrachial nucleus, locus coeruleus, nucleus of solitary tract, ventrolateral medulla and thoracic spinal cord. Contrary to broad efferent projections, PVNMC4R+ neurons receive monosynaptic inputs from limited brain regions, including medial preoptic nucleus, arcuate and dorsomedial hypothalamic nuclei, and supraoptic nucleus. Consistent with broad efferent projections, chemogenetic activation of PVNMC4R+ neurons not only suppressed feeding but also led to an apparent increase in heart rate, blood pressure and brown adipose tissue thermogenesis. Strikingly, these physiological changes accompanied an unexpected repetitive bedding-removing behavior followed by hypoactivity and resting-like behavior. ConclusionsOur results clarify the neuroanatomical organization of PVNMC4R+ circuits and shed new light on the roles of PVNMC4R+ pathways in autonomic control of thermogenesis, cardiovascular function and other behavioral regulations.

neuroscience↗