-
The New Phytologist Apr 2022Evergreen species are widespread across the globe, representing two major plant functional forms in terrestrial models. We reviewed and analysed the responses of... (Review)
Review
Evergreen species are widespread across the globe, representing two major plant functional forms in terrestrial models. We reviewed and analysed the responses of photosynthesis and respiration to warming in 101 evergreen species from boreal to tropical biomes. Summertime temperatures affected both latitudinal gas exchange rates and the degree of responsiveness to experimental warming. The decrease in net photosynthesis at 25°C (A ) was larger with warming in tropical climates than cooler ones. Respiration at 25°C (R ) was reduced by 14% in response to warming across species and biomes. Gymnosperms were more sensitive to greater amounts of warming than broadleaved evergreens, with A and R reduced c. 30-40% with > 10°C warming. While standardised rates of carboxylation (V ) and electron transport (J ) adjusted to warming, the magnitude of this adjustment was not related to warming amount (range 0.6-16°C). The temperature optimum of photosynthesis (T ) increased on average 0.34°C per °C warming. The combination of more constrained acclimation of photosynthesis and increasing respiration rates with warming could possibly result in a reduced carbon sink in future warmer climates. The predictable patterns of thermal acclimation across biomes provide a strong basis to improve modelling predictions of the future terrestrial carbon sink with warming.
Topics: Acclimatization; Carbon Dioxide; Photosynthesis; Plant Leaves; Respiration; Temperature; Trees; Tropical Climate
PubMed: 35007351
DOI: 10.1111/nph.17951 -
The Journal of Physiology Mar 2021Iron acts as a cofactor in the stabilization of the hypoxic-inducible factor family, and plays an influential role in the modulation of hypoxic pulmonary...
KEY POINTS
Iron acts as a cofactor in the stabilization of the hypoxic-inducible factor family, and plays an influential role in the modulation of hypoxic pulmonary vasoconstriction. It is uncertain whether iron regulation is altered in lowlanders during either (1) ascent to high altitude, or (2) following partial acclimatization, when compared to high-altitude adapted Sherpa. During ascent to 5050 m, the rise in pulmonary artery systolic pressure (PASP) was blunted in Sherpa, compared to lowlanders; however, upon arrival to 5050 m, PASP levels were comparable in both groups, but the reduction in iron bioavailability was more prevalent in lowlanders compared to Sherpa. Following partial acclimatization to 5050 m, there were differential influences of iron status manipulation (via iron infusion or chelation) at rest and during exercise between lowlanders and Sherpa on the pulmonary vasculature.
ABSTRACT
To examine the adaptational role of iron bioavailability on the pulmonary vascular responses to acute and chronic hypobaric hypoxia, the haematological and cardiopulmonary profile of lowlanders and Sherpa were determined during: (1) a 9-day ascent to 5050 m (20 lowlanders; 12 Sherpa), and (2) following partial acclimatization (11 ± 4 days) to 5050 m (18 lowlanders; 20 Sherpa), where both groups received an i.v. infusion of either iron (iron (iii)-hydroxide sucrose) or an iron chelator (desferrioxamine). During ascent, there were reductions in iron status in both lowlanders and Sherpa; however, Sherpa appeared to demonstrate a more efficient capacity to mobilize stored iron, compared to lowlanders, when expressed as a Δhepcidin per unit change in either body iron or the soluble transferrin receptor index, between 3400-5050 m (P = 0.016 and P = 0.029, respectively). The rise in pulmonary artery systolic pressure (PASP) was blunted in Sherpa, compared to lowlanders during ascent; however, PASP was comparable in both groups upon arrival to 5050 m. Following partial acclimatization, despite Sherpa demonstrating a blunted hypoxic ventilatory response and greater resting hypoxaemia, they had similar hypoxic pulmonary vasoconstriction when compared to lowlanders at rest. Iron-infusion attenuated PASP in both groups at rest (P = 0.005), while chelation did not exaggerate PASP in either group at rest or during exaggerated hypoxaemia ( = 67 mmHg). During exercise at 25% peak wattage, PASP was only consistently elevated in Sherpa, which persisted following both iron infusion or chelation. These findings provide new evidence on the complex interplay of iron regulation on pulmonary vascular regulation during acclimatization and adaptation to high altitude.
Topics: Acclimatization; Altitude; Humans; Hypoxia; Iron; Vasoconstriction
PubMed: 33442904
DOI: 10.1113/JP281114 -
Journal of Applied Physiology... Feb 2022High-altitude exposure results in a hyperventilatory-induced respiratory alkalosis followed by renal compensation (bicarbonaturia) to return arterial blood pH (pHa)...
High-altitude exposure results in a hyperventilatory-induced respiratory alkalosis followed by renal compensation (bicarbonaturia) to return arterial blood pH (pHa) toward sea-level values. However, acid-base balance has not been comprehensively examined in both lowlanders and indigenous populations-where the latter are thought to be fully adapted to high altitude. The purpose of this investigation was to compare acid-base balance between acclimatizing lowlanders and Andean and Sherpa highlanders at various altitudes (∼3,800, ∼4,300, and ∼5,000 m). We compiled data collected across five independent high-altitude expeditions and report the following novel findings: ) at 3,800 m, Andeans ( = 7) had elevated pHa compared with Sherpas ( = 12; < 0.01), but not to lowlanders ( = 16; 9 days acclimatized; = 0.09); 2) at 4,300 m, lowlanders ( = 16; 21 days acclimatized) had elevated pHa compared with Andeans ( = 32) and Sherpas ( = 11; both < 0.01), and Andeans had elevated pHa compared with Sherpas ( = 0.01); and ) at 5,000 m, lowlanders ( = 16; 14 days acclimatized) had higher pHa compared with both Andeans ( = 66) and Sherpas ( = 18; < 0.01, and = 0.03, respectively), and Andean and Sherpa highlanders had similar blood pHa ( = 0.65). These novel data characterize acid-base balance acclimatization and adaptation to various altitudes in lowlanders and indigenous highlanders. Lowlander, Andean, and Sherpa arterial blood data were combined across five independent high-altitude expeditions in the United States, Nepal, and Peru to assess acid-base status at ∼3,800, ∼4,300, and ∼5,000 m. The main finding was that Andean and Sherpa highlander populations have more acidic arterial blood, due to elevated arterial carbon dioxide and similar arterial bicarbonate compared with acclimatizing lowlanders at altitudes ≥4,300 m.
Topics: Acclimatization; Acid-Base Equilibrium; Altitude; Altitude Sickness; Expeditions; Humans
PubMed: 35023761
DOI: 10.1152/japplphysiol.00757.2021 -
Aerospace Medicine and Human Performance Dec 2023High-altitude [>2400 m (7874 ft)] acclimatization has been well studied with physiological adaptations like reductions in body weight and exercise capacity....
High-altitude [>2400 m (7874 ft)] acclimatization has been well studied with physiological adaptations like reductions in body weight and exercise capacity. However, despite the significance of moderate altitude [MA, 1524-2438 m (5000-8000 ft)], acclimatization at this elevation is not well described. We aimed to investigate differences in mice reared at MA compared to sea level (SL). We hypothesized that MA mice would be smaller and leaner and voluntarily run less than SL mice. C57BL/6 mice reared for at least three generations in Laramie, WY [2194 m (7198 ft), MA], were compared to C57BL/6J mice from Bar Harbor, ME [20 m (66 ft), SL]. We quantified body composition and exercise outputs as well as cardiopulmonary morphometrics. Subsets of MA and SL mice were analyzed to determine differences in neuronal activation after exercise. When body weight was normalized to tibia length, SL animals weighed 1.30 g ⋅ mm while MA mice weighed 1.13 g · mm. Total fat % and trunk fat % were higher in MA mice with values of 41% and 39%, respectively, compared to SL mice with values of 28% and 26%, respectively. However, no differences were noted in leg fat %. MA animals had higher heart mass (119 mg) and lower lung mass (160 mg) compared to SL mice heart mass (100 mg) and lung mass (177 mg). MA mice engaged in about 40% less voluntary wheel-running activity than SL animals. Physiological differences are apparent between MA and SL mice, prompting a need to further understand larger scale implications of residence at moderate altitude.
Topics: Animals; Mice; Altitude; Mice, Inbred C57BL; Altitude Sickness; Acclimatization; Body Weight
PubMed: 38176033
DOI: 10.3357/AMHP.6234.2023 -
International Journal of Molecular... Nov 2020Drought is a serious threat to the farming community, biasing the crop productivity in arid and semi-arid regions of the world. Drought adversely affects seed... (Review)
Review
Drought is a serious threat to the farming community, biasing the crop productivity in arid and semi-arid regions of the world. Drought adversely affects seed germination, plant growth, and development via non-normal physiological processes. Plants generally acclimatize to drought stress through various tolerance mechanisms, but the changes in global climate and modern agricultural systems have further worsened the crop productivity. In order to increase the production and productivity, several strategies such as the breeding of tolerant varieties and exogenous application of growth regulators, osmoprotectants, and plant mineral nutrients are followed to mitigate the effects of drought stress. Nevertheless, the complex nature of drought stress makes these strategies ineffective in benefiting the farming community. Seed priming is an alternative, low-cost, and feasible technique, which can improve drought stress tolerance through enhanced and advanced seed germination. Primed seeds can retain the memory of previous stress and enable protection against oxidative stress through earlier activation of the cellular defense mechanism, reduced imbibition time, upsurge of germination promoters, and osmotic regulation. However, a better understanding of the metabolic events during the priming treatment is needed to use this technology in a more efficient way. Interestingly, the review highlights the morphological, physiological, biochemical, and molecular responses of seed priming for enhancing the drought tolerance in crop plants. Furthermore, the challenges and opportunities associated with various priming methods are also addressed side-by-side to enable the use of this simple and cost-efficient technique in a more efficient manner.
Topics: Acclimatization; Crops, Agricultural; Dehydration; Droughts; Feasibility Studies; Germination; Seedlings; Seeds; Stress, Physiological
PubMed: 33158156
DOI: 10.3390/ijms21218258 -
Ecology Letters Oct 2022Understanding the factors affecting thermal tolerance is crucial for predicting the impact climate change will have on ectotherms. However, the role developmental... (Review)
Review
Understanding the factors affecting thermal tolerance is crucial for predicting the impact climate change will have on ectotherms. However, the role developmental plasticity plays in allowing populations to cope with thermal extremes is poorly understood. Here, we meta-analyse how thermal tolerance is initially and persistently impacted by early (embryonic and juvenile) thermal environments by using data from 150 experimental studies on 138 ectothermic species. Thermal tolerance only increased by 0.13°C per 1°C change in developmental temperature and substantial variation in plasticity (~36%) was the result of shared evolutionary history and species ecology. Aquatic ectotherms were more than three times as plastic as terrestrial ectotherms. Notably, embryos expressed weaker but more heterogenous plasticity than older life stages, with numerous responses appearing as non-adaptive. While developmental temperatures did not have persistent effects on thermal tolerance overall, persistent effects were vastly under-studied, and their direction and magnitude varied with ontogeny. Embryonic stages may represent a critical window of vulnerability to changing environments and we urge researchers to consider early life stages when assessing the climate vulnerability of ectotherms. Overall, our synthesis suggests that developmental changes in thermal tolerance rarely reach levels of perfect compensation and may provide limited benefit in changing environments.
Topics: Acclimatization; Climate Change; Hot Temperature; Plastics; Temperature
PubMed: 36006770
DOI: 10.1111/ele.14083 -
Environment International Mar 2023Climate change will have adverse impacts on human health, which are amplified in cities. For these impacts, there are direct, indirect, and deferred pathways. The first... (Review)
Review
Climate change will have adverse impacts on human health, which are amplified in cities. For these impacts, there are direct, indirect, and deferred pathways. The first category is well-studied, while indirect and deferred impacts are not well-understood. Moreover, the factors moderating the impacts have received little attention, although understanding these factors is critical for adaptation. We developed a conceptual framework that shows the pathways of climate impacts on human health, focusing specifically on the factors of urban environment moderating the emergence and severity of these health impacts. Based on the framework and literature review, we illustrate the mechanisms of direct, indirect, and deferred health impact occurrence and the factors that exacerbate or alleviate the severity of these impacts, thus presenting valuable insights for anticipatory adaptation. We conclude that an integrated systemic approach to preventing health risks from climate change can provide co-benefits for adaptation and address multiple health risks. Such an approach should be mainstreamed horizontally to all sectors of urban planning and should account for the spatiotemporal aspects of policy and planning decisions and city complexity.
Topics: Humans; Cities; Climate Change; Acclimatization
PubMed: 36921561
DOI: 10.1016/j.envint.2023.107837 -
The Journal of Physiology Dec 2022
Topics: Humans; Altitude; Adrenergic Agents; Acclimatization; Hemodynamics; Hypoxia; Regional Blood Flow
PubMed: 36314729
DOI: 10.1113/JP283688 -
Sensors (Basel, Switzerland) Jul 2022Sensors are devices that output signals for sensing physical phenomena and are widely used in all aspects of our social production activities. The continuous recording... (Review)
Review
Sensors are devices that output signals for sensing physical phenomena and are widely used in all aspects of our social production activities. The continuous recording of physical parameters allows effective analysis of the operational status of the monitored system and prediction of unknown risks. Thanks to the development of deep learning, the ability to analyze temporal signals collected by sensors has been greatly improved. However, models trained in the source domain do not perform well in the target domain due to the presence of domain gaps. In recent years, many researchers have used deep unsupervised domain adaptation techniques to address the domain gap between signals collected by sensors in different scenarios, , using labeled data in the source domain and unlabeled data in the target domain to improve the performance of models in the target domain. This survey first summarizes the background of recent research on unsupervised domain adaptation with time series sensor data, the types of sensors used, the domain gap between the source and target domains, and commonly used datasets. Then, the paper classifies and compares different unsupervised domain adaptation methods according to the way of adaptation and summarizes different adaptation settings based on the number of source and target domains. Finally, this survey discusses the challenges of the current research and provides an outlook on future work. This survey systematically reviews and summarizes recent research on unsupervised domain adaptation for time series sensor data to provide the reader with a systematic understanding of the field.
Topics: Acclimatization; Neural Networks, Computer; Time Factors
PubMed: 35898010
DOI: 10.3390/s22155507 -
PloS One 2023Two well-established numerical representations of the coagulation cascade either initiated by the intrinsic system (Chatterjee et al., PLOS Computational Biology 2010)...
Two well-established numerical representations of the coagulation cascade either initiated by the intrinsic system (Chatterjee et al., PLOS Computational Biology 2010) or the extrinsic system (Butenas et al., Journal of Biological Chemistry, 2004) were compared with thrombin generation assays under realistic pathological conditions. Biochemical modifications such as the omission of reactions not relevant to the case studied, the modification of reactions related to factor XI activation and auto-activation, the adaptation of initial conditions to the thrombin assay system, and the adjustment of some of the model parameters were necessary to align in vitro and in silico data. The modified models are able to reproduce thrombin generation for a range of factor XII, XI, and VIII deficiencies, with the coagulation cascade initiated either extrinsically or intrinsically. The results emphasize that when existing models are extrapolated to experimental parameters for which they have not been calibrated, careful adjustments are required.
Topics: Thrombin; Acclimatization; Biological Assay; Blood Coagulation; Computational Biology
PubMed: 37639392
DOI: 10.1371/journal.pone.0290531