Comparative analysis of energy homeostasis regulation at different altitudes in Hengduan Mountain of red-backed vole, Eothenomys miletus, during high-fat diet acclimation: examining gut microbial and physiological interactions.

The study aimed to explore the similarities and differences in gut microorganisms and their functions in regulating body mass in Eothenomys miletus across different altitudes in the Hengduan Mountains when exposed to a high-fat diet. Eothenomys miletus specimens were gathered from Dali (DL) and Xianggelila (XGLL) in Yunnan Province, China, and categorized into control, high-fat (1 week of high-fat diet), and re-feeding groups (1 week of high-fat diet followed by 2 weeks of standard food). The analysis utilized 16S rRNA sequencing to assess the diversity and structure of intestinal microbial communities in E. miletus. The investigation focused on the impact of high-fat diet consumption and different altitudes on gut microbial diversity, structure, and physiological markers. Results revealed that a high-fat diet influenced the beta diversity of gut microorganisms in E. miletus, leading to variations in microbial community structure between the two regions with different altitudes. High-fat food significantly affected body mass, white adipose tissue mass, triglycerides, and leptin levels, but not food intake. Specific intestinal microorganisms were observed in the high-fat groups, aiding in food digestion and being enriched in particular flora. In particular, microbial genera like Lactobacillus and Hylemonella were enriched in the high-fat group of DL. The enriched microbiota in the control group was associated with plant polysaccharide and cellulose decomposition. Following a high-fat diet, gut microbiota adapted to support lipid metabolism and energy supply, while upon re-feeding, the focus shifted back to cellulose digestion. These findings suggested that alterations in gut microbial composition, alongside physiological markers, play a vital role in adaptation of E. miletus to the diverse habitats of the Hengduan Mountains at varying altitudes.

Enhancing Winter Wheat Soil-Plant Analysis Development Value Prediction through Evaluating Unmanned Aerial Vehicle Flight Altitudes, Predictor Variable Combinations, and Machine Learning Algorithms.

Monitoring winter wheat Soil-Plant Analysis Development (SPAD) values using Unmanned Aerial Vehicles (UAVs) is an effective and non-destructive method. However, predicting SPAD values during the booting stage is less accurate than other growth stages. Existing research on UAV-based SPAD value prediction has mainly focused on low-altitude flights of 10-30 m, neglecting the potential benefits of higher-altitude flights. The study evaluates predictions of winter wheat SPAD values during the booting stage using Vegetation Indices (VIs) from UAV images at five different altitudes (i.e., 20, 40, 60, 80, 100, and 120 m, respectively, using a DJI P4-Multispectral UAV as an example, with a resolution from 1.06 to 6.35 cm/pixel). Additionally, we compare the predictive performance using various predictor variables (VIs, Texture Indices (TIs), Discrete Wavelet Transform (DWT)) individually and in combination. Four machine learning algorithms (Ridge, Random Forest, Support Vector Regression, and Back Propagation Neural Network) are employed. The results demonstrate a comparable prediction performance between using UAV images at 120 m (with a resolution of 6.35 cm/pixel) and using the images at 20 m (with a resolution of 1.06 cm/pixel). This finding significantly improves the efficiency of UAV monitoring since flying UAVs at higher altitudes results in greater coverage, thus reducing the time needed for scouting when using the same heading overlap and side overlap rates. The overall trend in prediction accuracy is as follows: VIs + TIs + DWT > VIs + TIs > VIs + DWT > TIs + DWT > TIs > VIs > DWT. The VIs + TIs + DWT set obtains frequency information (DWT), compensating for the limitations of the VIs + TIs set. This study enhances the effectiveness of using UAVs in agricultural research and practices.

Transcriptome and metabolome analyses reveal chlorogenic acid accumulation in pigmented potatoes at different altitudes.

Pigmented potato tubers are abundant in chlorogenic acids (CGAs), a metabolite with pharmacological activity. This article comprehensively analyzed the transcriptome and metabolome of pigmented potato Huaxingyangyu and Jianchuanhong at four altitudes of 1800 m, 2300 m, 2800 m, and 3300 m. A total of 20 CGAs and intermediate CGA compounds were identified, including 3-o-caffeoylquinic acid, 4-o-caffeoylquinic acid, and 5-o-caffeoylquinic acid. CGA contents in Huaxinyangyu and Jianchuanhong reached its maximum at an altitude of 2800 m and slightly decreased at 3300 m. 48 candidate genes related to the biosynthesis pathway of CGAs were screened through transcriptome analysis. Weighted gene co-expression network analysis (WGCNA) identified that the structural genes of phenylalanine deaminase (PAL), coumarate-3 hydroxylase (C3H), cinnamic acid 4-hydroxylase (C4H) and the transcription factors of MYB and bHLH co-regulate CGA biosynthesis. The results of this study provide valuable information to reveal the changes in CGA components in pigmented potato at different altitudes.

Environmental fate of microplastics in high-altitude basins: the insights into the Yarlung Tsangpo River Basin.

Microplastics (MPs) have been found in remote high-altitude areas, but the main source and migration process remained unclear. This work explored the characteristics and potential sources of MPs in the Yarlung Tsangpo River Basin. The average abundances of MPs in water, sediment, and soil samples were 728.26 ± 100.53 items/m3, 43.16 ± 5.82 items/kg, and 61.92 ± 4.29 items/kg, respectively, with polypropylene and polyethylene as the main polymers. The conditional fragmentation model revealed that the major source of MPs lower than 4000 m was human activities, while that of higher than 4500 m was atmospheric deposition. Community analysis was further conducted to explore the migration process and key points of MPs among different compartments in the basin. It was found that Lhasa (3600 m) and Shigatse (4100 m) were vital sources of MPs inputs in the midstream and downstream, respectively. This work would provide new insights into the fate of MPs in high-altitude areas.

High-flow nasal cannula oxygen reduced hypoxemia in patients undergoing gastroscopy under general anesthesia at ultra-high altitude: a randomized controlled trial.

BACKGROUND: Hypoxemia can occur in people at ultra-high altitude (above 3500 m) even at rest, and patients undergoing gastroscopy under general anesthesia have higher risk of hypoxemia. Supplementary oxygen via standard nasal cannula (SNC) is the standard of care for most patients who undergo gastroscopy under general anesthesia, which provides oxygen flow up to 15 L/min. High-flow nasal cannula (HFNC) could deliver oxygen at a rate up to 60 L/min, which is recommended by the American Society of Anesthesiologists Practice Guidelines. We speculated that the benefit with HFNC is more prominent in high-altitude areas, and aimed to compare the incidence of hypoxemia during gastroscopy under general anesthesia at ultra-high altitude with oxygen supply via either HFNC or SNC. METHODS: The trial was registered at at Chinese Clinical Trial Registry (ChiCTR2100045513; date of registration on 18/04/2021). Adult patients undergoing gastroscopy with anesthesia (estimated duration of anesthesia at ≥ 15 min) were randomized at a 1:1 ratio to receive HFNC oxygen or SNC oxygen. The primary outcome was hypoxemia (SpO2 < 90% for any duration). Secondary outcomes included severe hypoxemia (SpO2 < 75% for any duration or SpO2 < 90% but ≥ 75% for ≥ 60 s) and hypotension, as defined by reduction of mean arterial blood pressure by ≥ 25% from the baseline. RESULTS: A total of 262 patients were enrolled: 129 in the HFNC group and 133 in the SNC group. All patients received the designated intervention. Student's t-test, Mann-Whitney U test and χ2 test were employed in the study. The rate of hypoxemia was 9.3% (12/129) in the HFNC group versus 36.8% (49/133) in the SNC group [risk ratio (95% confidence interval): 0.25(0.14-0.45); P < 0.001). The HFNC group also had lower rate of severe hypoxemia [0.0% (0/129) versus 11.3% (15/133); risk ratio (95% confidence interval): 0.03(0.00-0.55); P < 0.001, respectively]. The rate of hypotension did not differ between the 2 groups [22.5% (29/129) in HFNC group versus 21.1% (28/133) in SNC group; risk ratio (95% confidence interval): 1.07(0.67-1.69) ; P = 0.779]. CONCLUSION: HFNC oxygen reduced the incidence of hypoxemia during anesthesia in adult patients undergoing gastroscopy at ultra-high altitude.

High myopia at high altitudes.

Background: Optic nerve sheath diameter (ONSD) increases significantly at high altitudes, and is associated with the presence and severity of acute mountain sickness (AMS). Exposure to hypobaria, hypoxia, and coldness when hiking also impacts intraocular pressure (IOP). To date, little is known about ocular physiological responses in trekkers with myopia at high altitudes. This study aimed to determine changes in the ONSD and IOP between participants with and without high myopia (HM) during hiking and to test whether these changes could predict symptoms of AMS. Methods: Nine participants with HM and 18 without HM participated in a 3-day trek of Xue Mountain. The ONSD, IOP, and questionnaires were examined before and during the trek of Xue Mountain. Results: The ONSD values increased significantly in both HM (p = 0.005) and non-HM trekkers (p = 0.018) at an altitude of 1,700 m. In the HM group, IOP levels were greater than those in the non-HM group (p = 0.034) on the first day of trekking (altitude: 3,150 m). No statistically significant difference was observed between the two groups for the values of ONSD. Fractional changes in ONSD at an altitude of 1,700 m were related to the development of AMS (r pb = 0.448, p = 0.019) and the presence of headache symptoms (r pb = 0.542, p = 0.004). The area under the ROC curve for the diagnostic performance of ONSD fractional changes at an altitude of 1,700 m was 0.859 for predicting the development of AMS and 0.803 for predicting the presence of headache symptoms. Conclusion: Analysis of changes in ONSD at moderate altitude could predict AMS symptoms before an ascent to high altitude. Myopia may impact physiological accommodation at high altitudes, and HM trekkers potentially demonstrate suboptimal regulation of aqueous humor in such environments.

Evaluation of cardiac index and right ventricular hypertrophy index in rats under a chronic hypoxic environment at high altitude.

High-altitude areas are characterized by low pressure and hypoxia, which have a significant impact on various body systems. This study aimed to investigate the alterations in cardiac index and right ventricular hypertrophy index(RVHI) in rats at different altitudes.Twenty-one male Sprague-Dawley (SD) rats aged 4 weeks were randomly divided into three groups based on altitude. The rats were raised for 28 weeks and then transferred to Qinghai University Plateau Medicine Laboratory. Body weight was measured, heart organs were isolated and weighed, and cardiac index and right ventricular hypertrophy index were determined. Statistical analysis was performed on the data from the three groups. Compared with the plain group, the body weight of the middle-altitude group was significantly decreased (P < 0.05), and cardiac index, RVHI-1, RVHI-2 increased significantly ((P < 0.05). The body weight, whole heart mass, right ventricular mass were significantly decreased in high-altitude group (P < 0.05), RVHI-1 and RVHI-2 were significantly increased (P < 0.05). Compared with the middle-altitude group, the body weight, whole heart mass and right ventricular mass of the high-altitude group were significantly decreased (P < 0.05), and RVHI-1 and RVHI-2 were significantly increased (P < 0.05). Increasing altitude led to a decrease in body weight, whole heart mass, and right ventricular mass in rats, indicating structural changes in the right heart. Additionally, the proportion of right heart to body weight and whole heart increased with altitude.

Characterization of lipid composition and nutritional quality of yak ghee at different altitudes: A quantitative lipidomic analysis.

Efficient and comprehensive analysis of lipid profiles in yak ghee samples collected from different elevations is crucial for optimal utilization of these resources. Unfortunately, such research is relatively rare. Yak ghee collected from three locations at different altitudes (S2: 2986 m; S5: 3671 m; S6: 4508 m) were analyzed by quantitative lipidomic. Our analysis identified a total of 176 lipids, and 147 s lipid of them were upregulated and 29 lipids were downregulated. These lipids have the potential to serve as biomarkers for distinguishing yak ghee from different altitudes. Notably, S2 exhibited higher levels of fatty acids (21:1) and branched fatty acid esters of hydroxy fatty acids (14:0/18:0), while S5 showed increased levels of phosphatidylserine (O-20:0/19:1) and glycerophosphoric acid (19:0/22:1). S6 displayed higher levels of triacylglycerol (17:0/20:5/22:3), ceramide alpha-hydroxy fatty acid-sphingosine (d17:3/34:2), and acyl glucosylceramides (16:0-18:0-18:1). Yak ghee exhibited a high content of neutralizing glycerophospholipids and various functional lipids, including sphingolipids and 21 newly discovered functional lipids. Our findings provide insights into quantitative changes in yak ghee lipids during different altitudes, development of yak ghee products, and screening of potential biomarkers.

Review of Athletic Guidelines for High-Altitude Training and Acclimatization.

Ramchandani, Rashi, Ioana Tereza Florica, Zier Zhou, Aziz Alemi, and Adrian Baranchuk. Review of athletic guidelines for high-altitude training and acclimatization. High Alt Med Biol. 00:000-000, 2024. Introduction: Exposure to high altitude results in hypobaric hypoxia with physiological acclimatization changes that are thought to influence athletic performance. This review summarizes existing literature regarding implications of high-altitude training and altitude-related guidelines from major governing bodies of sports. Methods: A nonsystematic review was performed using PubMed and OVID Medline to identify articles regarding altitude training and guidelines from international governing bodies of various sports. Sports inherently involving training or competing at high altitude were excluded. Results: Important physiological compensatory mechanisms to high-altitude environments include elevations in blood pressure, heart rate, red blood cell mass, tidal volume, and respiratory rate. These responses can have varying effects on athletic performance. Governing sport bodies have limited and differing regulations for training and competition at high altitudes with recommended acclimatization periods ranging from 3 days to 3 weeks. Discussion: Physiological changes in response to high terrestrial altitude exposure can have substantial impacts on athletic performance. Major sport governing bodies have limited regulations and recommendations regarding altitude training and competition. Existing guidelines are variable and lack substantial evidence to support recommendations. Additional studies are needed to clarify the implications of high-altitude exposure on athletic ability to optimize training and competition.

Multi-omics revealed the formation mechanism of characteristic volatiles in Tibetan yak cheese induced by different altitudes.

The variation in volatiles, bacteria and metabolites of Tibetan yak cheese (TYC) from different altitudes were characterized with multi-omics to reveal the formation mechanism of characteristic volatile compounds (C-VOCs) in TYC induced by altitudes. 22C-VOCs (odor activity value, OAV > 1) were identified in TYCs, and hexanal, dodecanol, 2,3-butanediol, butyl isobutyate, etc., C-VOCs were confirmed induced by altitude. Lactobacillus, Kocuria, etc., bacteria and benzyl thiocyanate, trehalose, sarcosine, etc., metabolites were screened as the variable bacteria and metabolites for TYCs regulated by altitude, respectively. Pediococcus and carbonhydrates maybe the main contributors for the formation of C-VOCs in TYCs induced by altitudes. The formation of dodecanol, 2,3-butanediol and hexanal maybe derived from sarcosine and EPA, and the generation of butyl isobutyrates maybe originated from 1,6-DP-fructose and threonic acid facilitating by Pediococcus. This research will help us gain insight into the contribution of altitude to the formation of volatiles in TYCs.

Allelic variation of PmCBF03 contributes to the altitude and temperature adaptability in Japanese apricot (Prunus mume Sieb. et Zucc.).

Japanese apricot is an important subtropical deciduous fruit tree in China, widely distributed in different altitude areas. How does it adapt to the different temperature environments in these areas? In this study, we identified a low-temperature transcription factor PmCBF03 on chromosome 7 through adaptive analysis of populations at different altitudes, which has an early termination single nucleotide polymorphism mutation. There were two different types of variation, PmCBF03A type in high-altitude areas and PmCBF03T type in low-altitude areas. PmCBF03A gene increased the survival rate, Fv/Fm values, antioxidant enzyme activity, and expression levels of antioxidant enzyme genes, and reducing electrolyte leakage and accumulation of reactive oxygen species in transgenic Arabidopsis under low temperature and freezing stress. Simultaneously, PmCBF03A gene promoted the dormancy of transgenic Arabidopsis seeds than wild-type. Biochemical analysis demonstrated that PmCBF03A directly bound to the DRE/CRT element in the promoters of the PmCOR413, PmDAM6 and PmABI5 genes, promoting their transcription and enhanced the cold resistance and dormancy of the overexpressing PmCBF03A lines. While PmCBF03T gene is unable to bind to the promoters of PmDAM6 and PmABI5 genes, leading to early release of dormancy to adapt to the problem of insufficient chilling requirement in low-altitude areas.

Hypobaric hypoxia drives selection of altitude-associated adaptative alleles in the Himalayan population.

Genetic variants play a crucial role in shaping the adaptive phenotypes associated with high-altitude populations. Nevertheless, a comprehensive understanding of the specific impacts of different environments associated with increasing altitudes on the natural selection of these genetic variants remains undetermined. Hence, this study aimed to identify genetic markers responsible for high-altitude adaptation with specific reference to different altitudes, majorly focussing on an altitude elevation range of ∼1500 m and a corresponding decrease of ≥5 % in ambient oxygen availability. We conducted a comprehensive genome-wide investigation (n = 192) followed by a validation study (n = 514) in low-altitude and three high-altitude populations (>2400 m) of Nubra village (NU) (3048 m), Sakti village (SKT) (3812 m), and Tso Moriri village (TK) (4522 m). Extensive genetic analysis identified 86 SNPs that showed significant associations with high-altitude adaptation. Frequency mapping of these SNPs revealed 38 adaptive alleles and specific haplotypes that exhibited a strong linear correlation with increasing altitude. Notably, these SNPs spanned crucial genes, such as ADH6 and NAPG along with the vastly studied genes like EGLN1 and EPAS1, involved in oxygen sensing, metabolism, and vascular homeostasis. Correlation analyses between these adaptive alleles and relevant clinical and biochemical markers provided evidence of their functional relevance in physiological adaptation to hypobaric hypoxia. High-altitude population showed a significant increase in plasma 8-isoPGF2α levels as compared to low-altitude population. Similar observation showcased increased blood pressure in NU as compared to TK (P < 0.0001). In silico analyses further confirmed that these alleles regulate gene expression of EGLN1, EPAS1, COQ7, NAPG, ADH6, DUOXA1 etc. This study provides genetic insights into the effects of hypobaric-hypoxia on the clinico-physiological characteristics of natives living in increasing high-altitude regions. Overall, our findings highlight the synergistic relationship between environment and evolutionary processes, showcasing physiological implications of genetic variants in oxygen sensing and metabolic pathway genes in increasing high-altitude environments.

Maturity Assessment of Different Table Grape Cultivars Grown at Six Different Altitudes in Lebanon.

Table grapes are harvested based on well-known maturity indices that must be monitored after fruit veraison. The aim of this study was to assess these indices across multiple locations and environmental conditions, encompassing different table grape cultivars such as Black Pearl, Crimson Seedless, Superior Seedless, and Red Globe. For this reason, grape sampling was conducted across six distinct locations characterized by varying altitudes above sea level (m asl) and environmental conditions over the ripening season. The main maturity indices, including pH, sugar content, titratable acidity, berry firmness, and other parameters were monitored over the growing season. Moreover, the quantification of total polyphenols, total anthocyanins, and antioxidant activity was determined using spectrophotometric assays at harvesting. The study has examined the effect of the vineyard's location on grape quality and its interaction with the cultivar and environment. Crimson Seedless maintained a relatively high level of acidity with altitude near harvesting. Black Pearl exhibited a notable decline in both sugar content and berry firmness as elevation increased, whereas Red Globe demonstrated contrasting outcomes. The optimal maturity of Superior Seedless was observed at an elevation of 1000 m asl. Black Pearl and Crimson Seedless exhibited better adaptability to intermediate elevations (650 and 950 m asl), while Red Globe and Superior Seedless showed better adaptability to higher elevations (1000-1150 m asl). Among the studied cultivars, Black Pearl exhibited significantly higher levels of total polyphenols and anthocyanins, while close values were noticed between red and green cultivars.

Lipid profiles and their relation to glycemic control in Saudi Arabia: The role of altitudes and environmental factor.

Background: The height from sea levels, environmental factors, human-environment interactions, and lifestyle significantly influence the lipid profile and glycemic control of a population. Objective: This study aims to explore the influence of altitude on lipid profiles and glycemic control among the Saudi population at sea level and high altitude. Methods: In this retrospective cross-sectional study, a large dataset of patients of both gender and over 30 years old attending internal medicine clinics from two different regions at different heights from sea level, Jeddah (sea level) and Asir region (high altitudes) and referred to commercial laboratories for glycated haemoglobin (HbA1c) and lipids profile. Results: Compared to the Asir region, the Jeddah region had significantly higher mean values for fasting blood sugar (FBG), total cholesterol (TC), low-density lipoprotein (LDL-C), and triglycerides (TG) (P < 0.05). Every 1 mg/dL increase in FBG results in a 0.662 mg/dL increase in TG from the Jeddah region. However, it was a 0.318 mg/dL increase in TG from the Asir region. HbA1c demonstrated a significant (P < 0.05) strong positive correlation with TC, low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and lipid ratio. FBG levels were also associated with a high level of TC/HDL-C (ß = 0.137 95% confidence interval [CI]: 0.11-0.21; P < 0.05), LDL-C/high-density lipoprotein cholesterol (HDL-C) (ß = 0.50; 95% CI: 0.31-1.49; P < 0.05), and TG/HDL-C (ß = 0.14; 95% CI = 0.12-0.15; P < 0.05) in Jeddah region. However, significantly high blood pressure was observed in the population from high altitudes. Conclusion: Our results demonstrated a significant positive correlation between lipid profile and glycemic control with high prevalence at sea level.

Risk factors for mortality in patients with acute exacerbation of cor pulmonale in plateau.

BACKGROUND: The risk factors for mortality might differ between patients with acute exacerbation of chronic pulmonary heart disease in plains and plateaus, while there is a lack of evidence. METHOD: Patients diagnosed with cor pulmonale at Qinghai Provincial People's Hospital were retrospectively included between January 2012 and December 2021. The symptoms, physical and laboratory examination findings, and treatments were collected. Based on the survival within 50 days, we divided the patients into survival and death groups. RESULTS: After 1:10 matching according to gender, age, and altitude, 673 patients were included in the study, 69 of whom died. The multivariable Cox proportional hazards analysis showed that NYHA class IV (HR = 2.03, 95%CI: 1.21-3.40, P = 0.007), type II respiratory failure (HR = 3.57, 95%CI: 1.60-7.99, P = 0.002), acid-base imbalance (HR = 1.82, 95%CI: 1.06-3.14, P = 0.031), C-reactive protein (HR = 1.04, 95%CI: 1.01-1.08, P = 0.026), and D-dimer (HR = 1.07, 95%CI: 1.01-1.13, P = 0.014) were risk factors for death in patients with cor pulmonale at high altitude. Among patients living below 2500 m, cardiac injury was a risk factor for death (HR = 2.47, 95%CI: 1.28-4.77, P = 0.007), while no significant association was observed at ≥ 2500 m (P = 0.057). On the contrary, the increase of D-dimer was only a risk factor for the death of patients living 2500 m and above (HR = 1.23, 95% CI: 1.07-1.40, P = 0.003). CONCLUSION: NYHA class IV, type II respiratory failure, acid-base imbalance, and C- reactive protein may increase the risk of death in patients with cor pulmonale. Altitude modified the association between cardiac injury, D-dimer, and death in patients with cor pulmonale.

Shifts in the Thermal Dependence of Locomotor Performance across an Altitudinal Gradient in Native Populations of Xenopus laevis.

AbstractEctothermic species are dependent on temperature, which drives many aspects of their physiology, including locomotion. The distribution of the native populations of Xenopus laevis is characterized by an exceptional range in latitude and altitude. Along altitudinal gradients, thermal environments change, and populations experience different temperatures. In this study, we compared critical thermal limits and thermal performance curves of populations from the native range across an altitudinal gradient to test whether optimal temperatures for exertion differ depending on altitude. Data on exertion capacity were collected at six different temperatures (8°C, 12°C, 16°C, 19°C, 23°C, and 27°C) for four populations spanning an altitudinal gradient (60, 1,016, 1,948, and 3,197 m asl). Results show that the thermal performance optimum differs among populations. Populations from cold environments at high altitudes exhibit a lower optimal performance temperature than populations from warmer environments at lower altitudes. The ability of this species to change its optimal temperature for locomotor exertion across extremely different climatic environments within the native range may help explain its exceptional invasive potential. These results suggest that ectothermic species capable of adapting to broad altitudinal ranges may be particularly good at invading novel climatic areas, given their ability to cope with a wide range of variation in environmental temperatures.

Neurodynamics of Awareness Detection in Tibetan Immigrants: Evidence from Electroencephalography Analysis.

The psychological effects of long-term exposure to high-altitude environments have attracted great attention. These effects are usually attributed to the diminished cognitive resources due to high-altitude exposure. This study employed electroencephalography (EEG) to investigate the effects of exposure duration on awareness detection tasks. Neither reaction time nor accuracy showed the direct effects of the exposure duration, so did the model indexes obtained from drift diffusion model analysis. However, event-related potentials (ERP) analysis revealed that exposure duration was associated with changes in the visual awareness negativity (VAN) and the late positivity (LP) components, which in turn affected reaction time. Specifically, longer exposure durations were associated with lower VAN and higher LP, resulting in shorter reaction times and greater drift rate. In contrast to previous studies, the reverse relationship between VAN and LP may reflect a compensatory response to the reduced cognitive resources caused by high-altitude exposure. Additionally, increased LP and shorter reaction times with exposure duration may reflect a resistance to the high-altitude environment. We also conducted time-frequency analysis and found that theta power did not vary with exposure duration, suggesting that the reduction in cognitive resources remains stable in these individuals over time. Overall, our study provides new insights into the dynamic effects of high-altitude environments on awareness detection in the presence of reduced cognitive resources.

Metabolites and gene expression in the myocardium of fasting rats in an acute hypoxic environment.

With the rising demand for entry to extremely high altitudes (HAs), rapid adaptability to extremely hypoxic environments is a challenge that we need to explore. Fasting was used to evaluate acute hypoxia tolerance at HA and was proven to be an effective method for improving the survival rate at extreme HA. Our experiments also showed that fasting pretreatment for 72 h significantly increased the 24 h survival rate of rats at 7620 m from 10 to 85% and protected the myocardium cells of rats. Here, we compared the metabolites and gene expression in the myocardium of SD rats pretreated with fasting and nonfasting at normal altitude and extreme HA. Our findings demonstrated that the dynamic contents of detected differential metabolites (DMs) between different rat groups were consistent with the expression of differentially expressed genes (DEGs), and DM clusters also showed strong correlations with DEG clusters. DM clusters related to amino acids and lipids were significantly lower in the fasting groups, and the correlated DEG clusters were enriched in mitotic pathways, including CDK1, CDC7, NUF2, and MCM6, suggesting that fasting can attenuate mitotic processes in cardiac tissues and reduce the synthesis of amino acids and lipids. L-Glutamine-related metabolites were particularly low at extreme HA without pretreatment but were normal in the fasting groups. The DEGs in the cluster related to L-glutamine-related metabolites were enriched for T-cell receptor V(D)J recombination, the Hippo signaling pathway, the Wnt signaling pathway, the cGMP-PKG signaling pathway, and the mTOR signaling pathway and were significantly downregulated, indicating that the content of L-glutamine decreased at extreme HA, while fasting increased it to adapt to the environment. Moreover, abundant fatty acids were detected when rats were exposed to extreme HA without pretreatment. Our study revealed the fasting and hypoxic environment-related factors in SD rats and provided new insights into the genetic and molecular characteristics in the myocardium, which is critical to developing more potential rapid adaptation methods to extreme HA.

Radiation environment in high-altitude Antarctic plateau: Recent measurements and model studies.

Polar regions are the most exposed to secondary particles and radiation produced by primary cosmic rays in the atmosphere, because naturally they are with marginal geomagnetic shielding. In addition, the secondary particle flux contributing to the complex radiation field is enhanced at high-mountain altitudes compared to sea level because of the reduced atmospheric attenuation. At present, there are very few systematic experimental measurements of environmental dose at high southern latitudes, specifically at high-altitude region. Here, we report a campaign of measurements with different devices, that is passive and Liulin-type dosimeters, of the radiation background at high-mountain Antarctic station Vostok (3488 m above sea level, 78° 27' S; 106° 50' E). We compare the measurements with a Monte Carlo-based model for the propagation of the cosmic rays through the atmosphere and assessment of the radiation field in the atmosphere. We employed the model to estimate the radiation dose at Vostok station during the ground-level enhancement at 28 October 2021. As in previous studies by other teams, we show that the annual dose equivalent at high-altitude Antarctic facilities can significantly exceed the limit of 1 mSv established for the general population by the ICRP.

Genetic Adaptation of Siberian Larch (Larix sibirica Ledeb.) to High Altitudes.

Forest trees growing in high altitude conditions offer a convenient model for studying adaptation processes. They are subject to a whole range of adverse factors that are likely to cause local adaptation and related genetic changes. Siberian larch (Larix sibirica Ledeb.), whose distribution covers different altitudes, makes it possible to directly compare lowland with highland populations. This paper presents for the first time the results of studying the genetic differentiation of Siberian larch populations, presumably associated with adaptation to the altitudinal gradient of climatic conditions, based on a joint analysis of altitude and six other bioclimatic variables, together with a large number of genetic markers, single nucleotide polymorphisms (SNPs), obtained from double digest restriction-site-associated DNA sequencing (ddRADseq). In total, 25,143 SNPs were genotyped in 231 trees. In addition, a dataset of 761 supposedly selectively neutral SNPs was assembled by selecting SNPs located outside coding regions in the Siberian larch genome and mapped to different contigs. The analysis using four different methods (PCAdapt, LFMM, BayeScEnv and RDA) revealed 550 outlier SNPs, including 207 SNPs whose variation was significantly correlated with the variation of some of environmental factors and presumably associated with local adaptation, including 67 SNPs that correlated with altitude based on either LFMM or BayeScEnv and 23 SNPs based on both of them. Twenty SNPs were found in the coding regions of genes, and 16 of them represented non-synonymous nucleotide substitutions. They are located in genes involved in the processes of macromolecular cell metabolism and organic biosynthesis associated with reproduction and development, as well as organismal response to stress. Among these 20 SNPs, nine were possibly associated with altitude, but only one of them was identified as associated with altitude by all four methods used in the study, a nonsynonymous SNP in scaffold_31130 in position 28092, a gene encoding a cell membrane protein with uncertain function. Among the studied populations, at least two main groups (clusters), the Altai populations and all others, were significantly genetically different according to the admixture analysis based on any of the three SNP datasets as follows: 761 supposedly selectively neutral SNPs, all 25,143 SNPs and 550 adaptive SNPs. In general, according to the AMOVA results, genetic differentiation between transects or regions or between population samples was relatively low, although statistically significant, based on 761 neutral SNPs (FST = 0.036) and all 25,143 SNPs (FST = 0.017). Meanwhile, the differentiation based on 550 adaptive SNPs was much higher (FST = 0.218). The data showed a relatively weak but highly significant linear correlation between genetic and geographic distances (r = 0.206, p = 0.001).