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Biological Reviews of the Cambridge... Apr 2022Elucidating the physiological mechanisms that underlie thermal stress and discovering how species differ in capacities for phenotypic acclimatization and evolutionary...
Elucidating the physiological mechanisms that underlie thermal stress and discovering how species differ in capacities for phenotypic acclimatization and evolutionary adaptation to this stress is critical for understanding current latitudinal and vertical distribution patterns of species and for predicting their future state in a warming world. Such mechanistic analyses require careful choice of study systems (species and temperature-sensitive traits) and design of laboratory experiments that reflect the complexities of in situ conditions. Here, we critically review a wide range of studies of intertidal molluscs that provide mechanistic accounts of thermal effects across all levels of biological organization - behavioural, organismal, organ level, cellular, molecular, and genomic - and show how temperature-sensitive traits govern distribution patterns and capacities for coping with thermal stress. Comparisons of congeners from different thermal habitats are especially effective means for identifying adaptive variation. We employ these mechanistic analyses to illustrate how species differ in the severity of threats posed by rising temperature. Counterintuitively, we show that some of the most heat-tolerant species may be most threatened by increases in temperatures because of their small thermal safety margins and minimal abilities to acclimatize to higher temperatures. We discuss recent molecular biological and genomic studies that provide critical foundations for understanding the types of evolutionary changes in protein structure, RNA secondary structure, genome content, and gene expression capacities that underlie adaptation to temperature. Duplication of stress-related genes, as found in heat-tolerant molluscs, may provide enhanced capacity for coping with higher temperatures. We propose that the anatomical, behavioural, physiological, and genomic diversity found among intertidal molluscs, which commonly are of critical importance and high abundance in these ecosystems, makes this group of animals a highly appropriate study system for addressing questions about the mechanistic determinants of current and future distribution patterns of intertidal organisms.
Topics: Acclimatization; Adaptation, Physiological; Animals; Climate Change; Ecosystem; Mollusca; Temperature
PubMed: 34713568
DOI: 10.1111/brv.12811 -
Nutrients Mar 2021The aim of this study was to assess the history of exertional heat illness (EHI), heat preparation, cooling strategies, heat related symptoms, and hydration during an...
The aim of this study was to assess the history of exertional heat illness (EHI), heat preparation, cooling strategies, heat related symptoms, and hydration during an ultra-endurance running event in a warm and humid environment. This survey-based study was open to all people who participated in one of the three ultra-endurance races of the Grand Raid de la Réunion. Ambient temperature and relative humidity were 18.6 ± 5.7 °C (max = 29.7 °C) and 74 ± 17%, respectively. A total of 3317 runners (56% of the total eligible population) participated in the study. Overall, 78% of the runners declared a history of heat-related symptoms while training or competing, and 1.9% reported a previous diagnosis of EHI. Only 24.3% of study participants living in temperate climates declared having trained in the heat before the races, and 45.1% of all respondents reported a cooling strategy during the races. Three quarter of all participants declared a hydration strategy. The planned hydration volume was 663 ± 240 mL/h. Fifty-nine percent of the runners had enriched their food or drink with sodium during the race. The present study shows that ultra-endurance runners have a wide variability of hydration and heat preparation strategies. Understandings of heat stress repercussions in ultra-endurance running need to be improved by specific field research.
Topics: Acclimatization; Adult; Drinking; Female; Heat Stress Disorders; Hot Temperature; Humans; Humidity; Male; Marathon Running; Middle Aged; Water
PubMed: 33810371
DOI: 10.3390/nu13041085 -
American Journal of Physiology. Heart... Dec 2020High-altitude (>2,500 m) exposure results in increased muscle sympathetic nervous activity (MSNA) in acclimatizing lowlanders. However, little is known about how... (Comparative Study)
Comparative Study
High-altitude (>2,500 m) exposure results in increased muscle sympathetic nervous activity (MSNA) in acclimatizing lowlanders. However, little is known about how altitude affects MSNA in indigenous high-altitude populations. Additionally, the relationship between MSNA and blood pressure regulation (i.e., neurovascular transduction) at high-altitude is unclear. We sought to determine ) how high-altitude effects neurocardiovascular transduction and ) whether differences exist in neurocardiovascular transduction between low- and high-altitude populations. Measurements of MSNA (microneurography), mean arterial blood pressure (MAP; finger photoplethysmography), and heart rate (electrocardiogram) were collected in ) lowlanders ( = 14) at low (344 m) and high altitude (5,050 m), ) Sherpa highlanders ( = 8; 5,050 m), and ) Andean (with and without excessive erythrocytosis) highlanders ( = 15; 4,300 m). Cardiovascular responses to MSNA burst sequences (i.e., singlet, couplet, triplet, and quadruplet) were quantified using custom software (coded in MATLAB, v.2015b). Slopes were generated for each individual based on peak responses and normalized total MSNA. High altitude reduced neurocardiovascular transduction in lowlanders (MAP slope: high altitude, 0.0075 ± 0.0060 vs. low altitude, 0.0134 ± 0.080; = 0.03). Transduction was elevated in Sherpa (MAP slope, 0.012 ± 0.007) compared with Andeans (0.003 ± 0.002, = 0.001). MAP transduction was not statistically different between acclimatizing lowlanders and Sherpa (MAP slope, = 0.08) or Andeans (MAP slope, = 0.07). When resting MSNA is accounted for (ANCOVA), transduction was inversely related to basal MSNA (bursts/minute) independent of population (RRI, = 0.578 < 0.001; MAP, = -0.627, < 0.0001). Our results demonstrate that transduction is blunted in individuals with higher basal MSNA, suggesting that blunted neurocardiovascular transduction is a physiological adaptation to elevated MSNA rather than an effect or adaptation specific to chronic hypoxic exposure. This study has identified that sympathetically mediated blood pressure regulation is reduced following ascent to high-altitude. Additionally, we show that high altitude Andean natives have reduced blood pressure responsiveness to sympathetic nervous activity (SNA) compared with Nepalese Sherpa. However, basal sympathetic activity is inversely related to the magnitude of SNA-mediated fluctuations in blood pressure regardless of population or condition. These data set a foundation to explore more precise mechanisms of blood pressure control under conditions of persistent sympathetic activation and hypoxia.
Topics: Acclimatization; Adult; Altitude; Arterial Pressure; Cardiovascular System; Female; Heart Rate; Homeostasis; Humans; Male; Middle Aged; Muscle, Skeletal; Nepal; Peru; Sympathetic Nervous System; Time Factors
PubMed: 32986967
DOI: 10.1152/ajpheart.00364.2020 -
Journal of Thermal Biology Aug 2019The human eccrine sweat gland is central to the evolution of the human genus, permitting an enormous thermoregulatory sweating capacity that was essential to the human... (Review)
Review
The human eccrine sweat gland is central to the evolution of the human genus, permitting an enormous thermoregulatory sweating capacity that was essential to the human niche of high physical activity in open, hot, semi-arid environments. Despite a century of research inventorying the structure and function of eccrine glands and the physiological responses of human heat acclimation, we do not have a clear understanding of how intraspecific differences in eccrine density affect thermoregulation. Similarly, existing data does not comprehensively catalogue modern human diversity in this trait, nor do we understand the relative influences of evolutionary forces and phenotypic plasticity in shaping this diversity.
Topics: Acclimatization; Biological Evolution; Eccrine Glands; Hot Temperature; Humans; Sweating
PubMed: 31466771
DOI: 10.1016/j.jtherbio.2019.07.024 -
Current Opinion in Insect Science Oct 2020Acclimation and other forms of plasticity that can increase stress resistance feature strongly in discussions surrounding climate change impacts or vulnerability... (Review)
Review
Acclimation and other forms of plasticity that can increase stress resistance feature strongly in discussions surrounding climate change impacts or vulnerability projections of insects and other ectotherms. There is interest in compiling databases for assessing the adequacy of acclimation for dealing with climate change. Here, we argue that the nature of acclimation is context dependent and therefore that estimates summarised across studies, especially those that have assayed stress using diverse methods, are limited in their utility when applied as a standardized metric or to a single general context such as average climate warming. Moreover, the dynamic nature of tolerances and acclimation drives important variation that is quickly obscured through many summary statistics or even in effect size analyses; retaining a strong focus on the temporal-level, population-level and treatment-level variance in forecasting climate change impacts on insects is essential. We summarise recent developments within the context of climate change and propose how future studies might validate the role of acclimation by integration across field studies and mechanistic modelling. Despite arguments to the contrary, to date no studies have convincingly demonstrated an important role for acclimation in recent climate change adaptation of insects. Paramount to these discussions is i) developing a strong conceptual framework for acclimation in the focal trait(s), ii) obtaining novel empirical data dissecting the fitness benefits and consequences of acclimation across diverse contexts and timescales, with iii) better coverage of under-represented geographic regions and taxa.
Topics: Acclimatization; Adaptation, Physiological; Animals; Climate Change; Insecta; Stress, Physiological
PubMed: 32570175
DOI: 10.1016/j.cois.2020.04.005 -
Physiological and Biochemical Zoology :... 2021AbstractConservation translocations are important in maintaining viable wildlife populations of vulnerable species within their indigenous ranges. To be effective,...
AbstractConservation translocations are important in maintaining viable wildlife populations of vulnerable species within their indigenous ranges. To be effective, population restoration efforts (e.g., head start programs) must consider the species' life history, regional ecology, and physiology and the health status of wild and translocated populations. The decline of Blanding's turtles () has prompted the initiation of head start programs, but the health and short-term survival of head-started juveniles released to the wild is largely unknown. From May to October 2016 and 2017, we radio tracked captive-reared, recently released juvenile Blanding's turtles and monitored their survivorship and monthly physiological health. We aimed to (1) compare physiological metrics of juveniles before and after release from captivity and between head-started cohorts, (2) identify seasonal trends in physiological metrics of recently released juveniles, (3) compare physiological metrics of recently released and formerly released juveniles, and (4) identify predictors of juvenile survivorship after release from captivity. Juvenile short-term survival was low compared with other studies. Most physiological metrics did not change after release from captivity, negating significant juvenile stress before or after release. Physiological metrics for recently released cohorts varied seasonally, suggesting that these juveniles were likely in good health. Some physiological metrics differed between recently released and formerly released juveniles, demonstrating a potential postrelease acclimatization period. Finally, no physiological metrics significantly predicted survival, but surviving juveniles had a higher percentage of fat. In all, juvenile deaths were not due to poor turtle health but rather to predation from human-subsidized mesocarnivores. Therefore, head-started juvenile Blanding's turtles released in suburban areas may benefit from antipredator training and mesocarnivore control at release sites.
Topics: Acclimatization; Animals; Animals, Wild; Turtles
PubMed: 34569914
DOI: 10.1086/716832 -
Nature Communications Feb 2024Animals must sense and acclimatize to environmental temperatures for survival, yet their thermosensing mechanisms other than transient receptor potential (TRP) channels...
Animals must sense and acclimatize to environmental temperatures for survival, yet their thermosensing mechanisms other than transient receptor potential (TRP) channels remain poorly understood. We identify a trimeric G protein-coupled receptor (GPCR), SRH-40, which confers thermosensitivity in sensory neurons regulating temperature acclimatization in Caenorhabditis elegans. Systematic knockdown of 1000 GPCRs by RNAi reveals GPCRs involved in temperature acclimatization, among which srh-40 is highly expressed in the ADL sensory neuron, a temperature-responsive chemosensory neuron, where TRP channels act as accessorial thermoreceptors. In vivo Ca imaging demonstrates that an srh-40 mutation reduced the temperature sensitivity of ADL, resulting in supranormal temperature acclimatization. Ectopically expressing SRH-40 in a non-warmth-sensing gustatory neuron confers temperature responses. Moreover, temperature-dependent SRH-40 activation is reconstituted in Drosophila S2R+ cells. Overall, SRH-40 may be involved in thermosensory signaling underlying temperature acclimatization. We propose a dual thermosensing machinery through a GPCR and TRP channels in a single sensory neuron.
Topics: Animals; Caenorhabditis elegans; Temperature; Sensory Receptor Cells; Caenorhabditis elegans Proteins; Acclimatization; Receptors, G-Protein-Coupled
PubMed: 38396085
DOI: 10.1038/s41467-024-46042-z -
Acta Physiologica (Oxford, England) Apr 2022Ascent to high altitude is accompanied by a reduction in partial pressure of inspired oxygen, which leads to interconnected adjustments within the neuromuscular system.... (Review)
Review
Ascent to high altitude is accompanied by a reduction in partial pressure of inspired oxygen, which leads to interconnected adjustments within the neuromuscular system. This review describes the unique challenge that such an environment poses to neuromuscular fatigability (peripheral, central and supraspinal) for individuals who normally reside near to sea level (SL) (<1000 m; ie, lowlanders) and for native highlanders, who represent the manifestation of high altitude-related heritable adaptations across millennia. Firstly, the effect of acute exposure to high altitude-related hypoxia on neuromuscular fatigability will be examined. Under these conditions, both supraspinal and peripheral fatigability are increased compared with SL. The specific mechanisms contributing to impaired performance are dependent on the exercise paradigm and amount of muscle mass involved. Next, the effect of chronic exposure to high altitude (ie, acclimatization of ~7-28 days) will be considered. With acclimatization, supraspinal fatigability is restored to SL values, regardless of the amount of muscle mass involved, whereas peripheral fatigability remains greater than SL except when exercise involves a small amount of muscle mass (eg, knee extensors). Indeed, when whole-body exercise is involved, peripheral fatigability is not different to acute high-altitude exposure, due to competing positive (haematological and muscle metabolic) and negative (respiratory-mediated) effects of acclimatization on neuromuscular performance. In the final section, we consider evolutionary adaptations of native highlanders (primarily Himalayans of Tibet and Nepal) that may account for their superior performance at altitude and lesser degree of neuromuscular fatigability compared with acclimatized lowlanders, for both single-joint and whole-body exercise.
Topics: Acclimatization; Altitude; Altitude Sickness; Fatigue; Humans; Hypoxia; Oxygen
PubMed: 35007386
DOI: 10.1111/apha.13788 -
Plant, Cell & Environment Nov 2023Climate change is causing alterations in annual temperature regimes worldwide. Important aspects of this include the reduction of winter chilling temperatures as well as... (Review)
Review
Climate change is causing alterations in annual temperature regimes worldwide. Important aspects of this include the reduction of winter chilling temperatures as well as the occurrence of unpredicted frosts, both significantly affecting plant growth and yields. Recent studies advanced the knowledge of the mechanisms underlying cold responses and tolerance in the model plant Arabidopsis thaliana. However, how these cold-responsive pathways will readjust to ongoing seasonal temperature variation caused by global warming remains an open question. In this review, we highlight the plant developmental programmes that depend on cold temperature. We focus on the molecular mechanisms that plants have evolved to adjust their development and stress responses upon exposure to cold. Covering both genetic and epigenetic aspects, we present the latest insights into how alternative splicing, noncoding RNAs and the formation of biomolecular condensates play key roles in the regulation of cold responses. We conclude by commenting on attractive targets to accelerate the breeding of increased cold tolerance, bringing up biotechnological tools that might assist in overcoming current limitations. Our aim is to guide the reflection on the current agricultural challenges imposed by a changing climate and to provide useful information for improving plant resilience to unpredictable cold regimes.
Topics: Cold Temperature; Seasons; Temperature; Plants; Arabidopsis; Climate Change; Gene Expression Regulation, Plant; Acclimatization
PubMed: 37438895
DOI: 10.1111/pce.14669 -
Plant, Cell & Environment Dec 2022Strigolactones are phytohormones with many attributed roles in development, and more recently in responses to environmental stress. We will review evidence of the latter... (Review)
Review
Strigolactones are phytohormones with many attributed roles in development, and more recently in responses to environmental stress. We will review evidence of the latter in the frame of the classic distinction among the three main stress acclimation strategies (i.e., avoidance, tolerance and escape), by taking osmotic stress in its several facets as a non-exclusive case study. The picture we will sketch is that of a hormonal family playing important roles in each of the mechanisms tested so far, and influencing as well the build-up of environmental memory through priming. Thus, strigolactones appear to be backstage operators rather than frontstage players, setting the tune of acclimation responses by fitting them to the plant individual history of stress experience.
Topics: Plants; Stress, Physiological; Lactones; Acclimatization
PubMed: 36207810
DOI: 10.1111/pce.14461