High-altitude Environments Research Articles

Variations in seminal microbiota and their functional implications in chickens adapted to high-altitude environments

Seminal fluid, once believed to be sterile, is now recognized as constituting a complex and dynamic environment inhabited by a diverse community of micro-organisms. However, research on the seminal microbiota in chickens is limited, and microbiota variations among different chicken breeds remain largely unexplored. In this study, we collected semen samples from Beijing You Chicken (BYC) and Tibetan Chicken (TC) and explored the characteristics of the microbiota using 16S rRNA gene sequencing. Additionally, we collected cloacal samples from the TC to control for environmental contamination. The results revealed that the microbial communities in the semen were significantly different from those in the cloaca. Firmicutes and Actinobacteriota were the predominant phyla in BYC and TC semen, respectively, with Lactobacillus and Phyllobacterium being the dominant genera in each group. Additionally, the seminal microbiota of BYC exhibited greater richness and evenness than that of TC. Principal coordinate analysis (PCoA) indicated significant intergroup differences between the seminal microbiotas of BYC and TC. Subsequently, by combining linear discriminant analysis effect size and random forest analyses, we identified Lactobacillus as the predominant microorganism in BYC semen, whereas Phyllobacterium dominated in TC semen. Furthermore, co-occurrence network analysis revealed a more intricate network in the BYC group than in the TC group. Additionally, unique microbial functional characteristics were observed in each breed, with TC exhibiting metabolic features potentially associated with their ability to adapt to high-altitude environments. The results of this study emphasized the unique microbiota present in chicken semen, which may be influenced by genetics and evolutionary history. Significant variations were observed between low-altitude and high-altitude breeds, highlighting the breed-specific implications of the seminal microbiota for reproduction and high-altitude adaptation.

The complete chloroplast genome of Meconopsis torquata (Papaveraceae), a traditional Tibetan medicine

Meconopsis torquata Prain 1906, a national second-class rare and endangered plant, is reported here for the first time for its complete chloroplast genome. The genome is 153,290 bp in length, comprising a large single-copy region (LSC, 83,918 bp), a small single-copy region (SSC, 17,740 bp), and two inverted repeat sequences (IRa and IRb, each 25,816 bp). The overall GC content is 38.7%, with the IR region having the highest content (43.1%). The genome is annotated with 112 unique genes, including 4 rRNA genes, 29 tRNA genes, and 79 protein-coding genes. Analysis of codon usage bias reveals that codons ending in A/T account for 96.7% of those with a Relative Synonymous Codon Usage (RSCU) value above 1. This predominance of A/T-ending codons might be indicative of M. torquata adaptation to high-altitude environments. Phylogenetic analysis reveals a close kinship between M. torquata and M. pinnatifolia and M. paniculata, indicating that the ancestral groups of these species might have a complex evolutionary history. This study uncovers the genetic characteristics and adaptive evolution of M. torquata, offering a new perspective in understanding the phylogenetic relationships within the genus. The findings not only provide a solid theoretical foundation for the conservation and sustainable use of this rare and endangered species but also offer significant scientific support for the conservation of biodiversity.

Study of the Performance of Emulsified Asphalt Shotcrete in High-Altitude Permafrost Regions

To improve the performance of shotcrete in high-altitude and low-temperature environments, emulsified asphalt shotcrete (EASC), which can be used in negative-temperature environments, was prepared by using low-freezing-point emulsified asphalt, calcium aluminate cement, and sodium pyrophosphate as modified materials. The effect of emulsified asphalt on the performance of shotcrete was investigated through concrete spraying and indoor tests. Then, the modification mechanism of emulsified asphalt with respect to EASC was analyzed by combining scanning electron microscopy images and the pore structure characteristics of EASC. The results showed that in a negative-temperature environment, the incorporation of emulsified asphalt delayed the formation of the peak of the cement hydration exotherm, slowed the rate of the cement hydration exotherm, reduced the thermal perturbation of permafrost by EASC, increased the cohesion of the concrete, improved the bond strength between EASC and permafrost, and reduced the rate of rebound. The mechanical strength of the studied EASC decreased upon increasing the amount of emulsified asphalt in the admixture, and its resistance to cracking gradually improved. A content of less than 5% emulsified asphalt could improve the internal pore structure of EASC, thus improving its durability. Increasing the content of emulsified asphalt affected the hydration process of the cement, and the volume content of the capillary pores and macropores increased, which reduced the durability of the EASC.

The role of oxidative stress and neuroinflammatory mediators in the pathogenesis of high-altitude cerebral edema in rats

High-altitude environments present extreme conditions characterized by low barometric pressure and oxygen deficiency, which can disrupt brain functioning and cause edema formation. The objective of the present study is to investigate several biomolecule expressions and their role in the development of High Altitude Cerebral Edema in a rat model. Specifically, the study focuses on analyzing the changes in total arginase, nitric oxide, and lipid peroxidation (MDA) levels in the brain following acute hypobaric hypoxic exposure (7620 m, SO2=8.1 %, for 24 h) along with the histopathological assessment. The histological examination revealed increased TNF-α activity, and an elevated number of mast cells in the brain, mainly in the hippocampus and cerebral cortex. The research findings demonstrated that acute hypobaric hypoxic causes increased levels of apoptotic cells, shrinkage, and swelling of neurons, accompanied by the formation of protein aggregation in the brain parenchyma. Additionally, the level of nitric oxide and MDA was found to have increased (p<0.0001), however, the level of arginase decreased indicating active lipid peroxidation and redox imbalance in the brain. This study provides insights into the pathogenesis of HACE by evaluating some biomolecules that play a pivotal role in the inflammatory response and the redox landscape in the brain. The findings could have significant implications for understanding the neuronal dysfunction and the pathological mechanisms underlying HACE development.

Hypermethylation of BMPR2 and TGF-β Promoter Regions in Tibetan Patients with High-Altitude Polycythemia at Extreme Altitude.

Although the expression of many genes is associated with adaptation to high-altitude hypoxic environments, the role of epigenetics in the response to this harsh environmental stress is currently unclear. We explored whether abnormal DNA promoter methylation levels of six genes, namely, ABCA1, SOD2, AKT1, VEGFR2, TGF-β, and BMPR2, affect the occurrence and development of high-altitude polycythemia (HAPC) in Tibetans. The methylation levels of HAPC and the control group of 130 Tibetans from very high altitudes (> 4500m) were examined using quantitative methylation-specific real-time PCR (QMSP). Depending on the type of data, the Pearson chi-square test, Wilcoxon rank-sum test, and Fisher exact test were used to assess the differences between the two groups. The correlation between the methylation levels of each gene and the hemoglobin content was explored using a linear mixed model. Our experiment revealed that the methylation levels of the TGF-β and BMPR2 genes differed significantly in the two groups (p < 0.05) and linear mixed model analysis showed that the correlation between the hemoglobin and methylation of ABCA1, TGF-β, and BMPR2 was statistically significant (p < 0.05). Our study suggests that levels of TGF-β and BMPR2 methylation are associated with the occurrence of HAPC in extreme-altitude Tibetan populations among 6 selected genes. Epigenetics may be involved in the pathogenesis of HAPC, and future experiments could combine gene and protein levels to verify the diagnostic value of TGF-β and BMPR2 methylation levels in HAPC.

Changes in hypoxic and hypercapnic ventilatory responses at high altitude measured using rebreathing methods.

Ventilatory responses to hypoxia and hypercapnia play a vital role in maintaining gas exchange homeostasis and in adaptation to high-altitude environments. This study investigates the mechanisms underlying sensitization of hypoxic and hypercapnic ventilatory response (HVR and HCVR, respectively) in individuals acclimatized to moderate high altitude (3,800 m). Thirty-one participants underwent chemoreflex testing using the Duffin-modified rebreathing technique. Measures were taken at sea level and after 2 days of acclimatization to high altitude. Ventilatory recruitment threshold (VRT), HCVR-Hyperoxia, HCVR-Hypoxia, and HVR were quantified. Acclimatization to high altitude resulted in increased HVR (P < 0.001) and HCVR-Hyperoxia (P < 0.001), as expected. We also observed that the decrease in VRT under hypoxic test conditions significantly contributed to the elevated HVR at high altitude since the change in VRT across hyperoxic and hypoxic test conditions was greater at high altitudes compared to baseline sea-level tests (P = 0.043). Pre-VRT, or basal, ventilation also increased at high altitudes (P < 0.001), but the change did not differ between oxygen conditions. Taken together, these data suggest that the increase in HVR at high altitude is at least partially driven by a larger decrease in the VRT in hypoxia versus hyperoxia at high altitude compared to sea level. This study highlights the intricacies of respiratory adaptations during acclimatization to moderate high altitude, shedding light on the roles of the VRT, baseline respiratory drive, and two-slope HCVR in this process. These findings contribute to our understanding of how human respiratory control responds to hypoxic and hypercapnic challenges at high altitude.NEW & NOTEWORTHY We report the first measurements of the hypoxic ventilatory response (HVR) after 2 days at high altitude using a CO2 rebreathing technique. We evaluated mechanisms by which the HVR becomes elevated with acclimatization (increased hypercapnic ventilatory response sensitivity in hypoxia, increased baseline respiratory drive in hypoxia, or lower ventilatory recruitment thresholds in hypoxia). For the first time, we report that decreases in the ventilatory recruitment threshold in hypoxia contribute to elevated HVR at high altitude.

Hypoxia-inducible factor-1α attenuates renal podocyte injury in male rats in a simulated high-altitude environment by upregulating Krüppel-like factor 4 expression.

Previous studies have shown that podocyte injury is involved in the development of proteinuria in rats under hypobaric hypoxia conditions. Prolyl hydroxylase inhibitors (PHIs) may reduce proteinuria. This study aimed to further investigate whether the protective effects of hypoxia-inducible factor 1α (HIF1α) on podocyte injury induced by hypobaric hypoxia are related to Krüppel-like factor 4 (KLF4). Rats were housed in a low-pressure oxygen chamber to simulate a high-altitude environment (5000m), and a PHI was intraperitoneally injected. Urinary protein electrophoresis was performed and the morphology of the podocytes was observed by electron microscopy. Rat podocytes were cultured under 1% O2, and siRNA was used to interfere with KLF4 expression. The protein expression levels of HIF1α, KLF4, CD2-associated protein (CD2AP) and nephrin were determined by western blotting. Compared with those in the experimental group, the rats in the intervention group on day 14 had lower urinary protein levels, increased protein expression levels of CD2AP and nephrin, and reduced podocyte injury. The results of in vitro experiments showed that the protein expression levels of KLF4, CD2AP and nephrin were greater in the PHI intervention group and lower in the HIF1α inhibitors group than in the low-oxygen group. The protein expression of CD2AP and nephrin in the siKLF4-transfected podocytes treated with PHI and HIF1α inhibitors did not differ significantly from that in the low-oxygen group. HIF1α may be involved in reducing progressive high-altitude proteinuria by regulating KLF4 expression and contributing to the repair of podocyte injury induced by hypobaric hypoxia.

A Survey of Flow Field and Combustion Characteristics under Subatmospheric Pressure

This paper presents a summary of and introduction to research on high-altitude and subatmospheric combustion concerning turbine and scramjet engines. The investigation includes theoretical analysis, experimental studies, and numerical simulations. The analysis encompasses the flow field structure, fuel atomization, and combustion performance. Subsequently, recent research on the combustion performance of liquid fuels, solid fuels, and gaseous fuels under high-altitude and low-pressure plateau environments is reviewed. This includes an evaluation of flame height, flame temperature, combustion rate, fire spread rate, and heat radiation flux. Additionally, combustion performance prediction models for high-altitude environments based on experimental and theoretical analysis have been introduced. Lastly, issues in subatmospheric combustion in the aerospace and plateau fire fields are presented based on the current research.

Effect of foaming characteristics of air entrained agents on mechanical properties and pore structures of cement-based materials in plateau mountainous regions

Concrete freeze-thaw damage is common in high-altitude regions. Adding an appropriate amount of air-entraining agents (AEA) can improve the flowability of fresh concrete and the frost resistance of hardened concrete, without significantly affecting concrete strength. However, the existing studies of the influence and mechanism of AEAs on concrete mainly focus on conventional environmental tests and simulated conditions, with less consideration to the various environmental factors caused by real altitude changes. In this study, five types of AEAs are utilized according to bubble shaking tests in two different altitude environments: Chengdu, Sichuan (altitude: 300 m; air pressure: 96.7 kPa), and Aba Prefecture, Sichuan (altitude: 3700 m; air pressure: 66.7 kPa). Physical and mechanical properties as well as pore structure tests are also conducted on AEA paste and concrete. The results show that the relationship between air bubble sizes and surface tension of AEA solutions is the closest, with larger bubble sizes, smaller bubble volumes, and poorer foaming properties observed at high-altitude regions. Adding an appropriate amount of AEA can improve concrete workability. In high-altitude and low-temperature regions, AEA concrete exhibits better slump retention. The addition of triterpenoid saponin AEA increases the proportion of small pores (0.5 μm–200 μm) in paste and concrete, with a lower growth rate observed at high altitudes compared to lower altitudes. Additionally, the average pore diameter and bubble spacing coefficient of hardened paste decrease, optimizing the pore structure. Triterpenoid saponin AEA is recommended for improving concrete performance in high-altitude environments, with a recommended dosage of 0.01 %.

Genomic and transcriptomic analysis reveals the genetic diversity and adaptive signatures of Maduo sheep

The alpine grassland ecosystem is characterized by high-altitude, hypoxia, harsh cold and strong radiation conditions, and the unique growth performance and stress resistance of indigenous domestic animals. Maduo sheep, a newly discovered Tibetan sheep breed living in the source area of the Yellow River, is famous for its high-quality wool and meat production. However, its genome and genetic features still need to be deciphered. The genomes of 12 Maduo sheep were sequenced on a genome-wide scale and compared with those of 6 other Tibetan sheep breeds. Population structure analyses revealed that Maduo sheep were distinctly separated from other Tibetan sheep breeds with a higher genetic diversity. Strong selective signatures were detected by the FST and XP-CLR results, identifying MREG, RXFP2 and SYNDIG1 in Maduo sheep. To explore the molecular regulation of Maduo sheep adaptability to the high-altitude environment, the muscle tissues of 3 Tibetan sheep populations living at different altitudes (1500 m, 2500 m and 4200 m) were sampled for RNA sequencing. We found 132, 269 and 149 specific transcripts from 1500 m, 2500 m and 4200 m groups respectively. A total of 327 differentially expressed transcripts were found in both 2500 m vs. 1500 m and 4200 m vs. 1500 m comparisons, which were closely related to stem cell differentiation, p38-MAPK cascade, skeletal system morphogenesis, etc. On the other hand, 122 differentially expressed transcripts were found in both 4200 m vs. 1500 m and 4200 m vs. 2500 m comparisons, which should be responsible for adaptive immune response, cytoskeleton, apoptotic regulation and so on. This study provides important genomic insights into the genetic resources of Maduo sheep and could be helpful for understanding the mechanisms of hypoxic adaptability.

High-altitude-induced alterations in intestinal microbiota.

In high-altitude environments characterized by low pressure and oxygen levels, the intestinal microbiota undergoes significant alterations. Whether individuals are subjected to prolonged exposure or acute altitude changes, these conditions lead to shifts in both the diversity and abundance of intestinal microbiota and changes in their composition. While these alterations represent adaptations to high-altitude conditions, they may also pose health risks through certain mechanisms. Changes in the intestinal microbiota induced by high altitudes can compromise the integrity of the intestinal mucosal barrier, resulting in gastrointestinal dysfunction and an increased susceptibility to acute mountain sickness (AMS). Moreover, alterations in the intestinal microbiota have been implicated in the induction or exacerbation of chronic heart failure. Targeted modulation of the intestinal microbiota holds promise in mitigating high-altitude-related cardiac damage. Dietary interventions, such as adopting a high-carbohydrate, high-fiber, low-protein, and low-fat diet, can help regulate the effects of intestinal microbiota and their metabolic byproducts on intestinal health. Additionally, supplementation with probiotics, either through dietary sources or medications, offers a means of modulating the composition of the intestinal microbiota. These interventions may offer beneficial effects in preventing and alleviating AMS following acute exposure to high altitudes.

A conjoint analysis of renal structure and omics characteristics reveal new insight to yak high-altitude hypoxia adaptation

BackgroundYaks have unique adaptive mechanisms to the hypoxic environment, in which the kidney plays an important role. The aim of this study was to explore the histological changes of yak kidney at different altitudes and the metabolites and genes associated with adaptation to the hypoxic environment. MethodsWe analyzed the tissue structure and transcriptomic metabolomic data of yak kidney tissue at two altitudes, 2600 and 4400 m. We compared and identified the morphological adaptations of the kidney and the metabolites and genes associated with hypoxia adaptation in yaks. Changes in renal morphological adaptations, differential metabolites and genes were compared and identified, combining the two in a joint analysis. ResultsHigh-altitude yak kidneys showed significant adaptive changes: increased mitochondria, increased glomerular thylakoid area, and decreased localized ribosomes. Transcriptomics and metabolomics identified 69 DAMs (Differential metabolites) and 594 DEGs (differential genes). Functional enrichment analysis showed that the DAMs were associated with protein digestion and absorption, ABC transporter, and MTOR signaling pathway; the DEGs were significantly enriched in Cholesterol metabolism and P53 signaling pathway. The joint analysis indicated that metabolites such as lysine and arginine, as well as key genes such as ABCB5 and COL1A2, were particularly affected under hypoxic conditions, whereas changes in mitochondria in the tissue structure may be related to the expression of MFN1 and OPA1, and changes in glomerular thylakoid membranes are related to VEGFA and TGFB3. ConclusionThe kidney regulates metabolites and gene expression related to hormone synthesis, protein metabolism, and angiogenesis by adjusting the mitochondrial and glomerular thylakoid membrane structure to support the survival of yaks in high-altitude environments.

Transcriptomics reveals age-related changes in ion transport-related factors in yak lungs.

Yaks inhabit high-altitude, low-oxygen regions, where ion transport functions play a crucial role in maintaining intracellular and extracellular ionic balance and regulating pulmonary vascular tension. These functions affect pulmonary ventilation and blood flow rate, aiding tissue development and enhancing oxygen transfer efficiency, thus facilitating better adaptation to hypoxic environments. To investigate the regulatory mechanisms of ion transport-related factors on the growth and development of yak lungs, we employed RNA sequencing (RNA-seq)for sequencing the transcriptome in the lung tissues of neonatal (1-day-old), juvenile (1-year-old), and adult (4-year-old) yaks. We also performed differential gene expression and functional analyses. The results yielded 26 genes associated with ion transport, mainly enriched in the salivary and pancreatic secretion pathways. Finally, we used several methods including quantitative polymerase chain reaction (qRT-PCR), and Western blotting (WB), immunohistochemical (IHC) and immunofluorescence (IF) staining to determine the distribution of the expression of the ion transport genes FOXI1, KCNMA1, and SLC12A2 in yak lung tissues. qRT-PCR and WB results indicated that mRNA and protein relative expression levels of FOXI1 and SLC12A2 were significantly higher in neonatal yaks than in juvenile and adult yaks (all p < 0.05), whereas those of KCNMA1 were significantly higher in adult yaks than in neonatal and juvenile yaks (all p < 0.05). IHC and IF results demonstrated that FOXI1, KCNMA1, and SLC12A2 were distributed among the epithelial mucosal layers (including ciliated, goblet, and Clara cells) of the yaks' bronchi and their branches in the lungs across different age groups of yak. Therefore, our results suggested that FOXI1, KCNMA1, and SLC12A2 may be strongly associated with the development and aging processes in yak lungs. These results provide insights into the molecular mechanisms underlying the yak's adaptation to high-altitude environments and valuable references for further research.

Impact of high-altitude acclimatization and de-acclimatization on the intestinal microbiota of rats in a natural high-altitude environment.

Intestinal microorganisms play an important role in the health of both humans and animals, with their composition being influenced by changes in the host's environment. We evaluated the longitudinal changes in the fecal microbial community of rats at different altitudes across various time points. Rats were airlifted to high altitude (3,650 m) and acclimatized for 42 days (HAC), before being by airlifted back to low altitude (500 m) and de-acclimatized for 28 days (HADA); meanwhile, the control group included rats living at low altitude (500 m; LA). We investigated changes in the gut microbiota at 12 time points during high-altitude acclimatization and de-acclimatization, employing 16S rRNA gene sequencing technology alongside physiological indices, such as weight and daily autonomous activity time. A significant increase in the Chao1 index was observed on day 14 in the HAC and HADA groups compared to that in the LA group, indicating clear differences in species richness. Moreover, the principal coordinate analysis revealed that the bacterial community structures of HAC and HADA differed from those in LA. Long-term high-altitude acclimatization and de- acclimatization resulted in the reduced abundance of the probiotic Lactobacillus. Altitude and age significantly influenced intestinal microbiota composition, with changes in ambient oxygen content and atmospheric partial pressure being considered key causal factors of altitude-dependent alterations in microbiota composition. High-altitude may be linked to an increase in anaerobic bacterial abundance and a decrease in non-anaerobic bacterial abundance. In this study, the hypobaric hypoxic conditions at high-altitude increased the abundance of anaerobes, while reducing the abundance of probiotics; these changes in bacterial community structure may, ultimately, affect host health. Overall, gaining a comprehensive understanding of the intestinal microbiota alterations during high-altitude acclimatization and de-acclimatization is essential for the development of effective prevention and treatment strategies to better protect the health of individuals traveling between high- and low-altitude areas.

Assessing the impact of mining on cyclic and linear methylsiloxane distribution in Tibetan soils: Source contribution and transport pattern

The pervasive presence of methylsiloxanes (MSs), comprising linear and cyclic congeners, in the environment poses significant ecological risks, yet the understanding of their transport mechanisms and deposition patterns remains limited. This study analyzed the concentrations of 12 linear-MSs (L3–L14) and 7 cyclic-MSs (D3–D9) in 29 surface soil samples collected across varying altitudes (3726 to 4863 m) near the Jiama mining sector in Tibet, aiming to investigate the distribution and transport dynamics of MSs from the emission source. The distribution of total MS concentration (ranging from 50.1 to 593 ng/g) showed a remarkable correlation with proximity to the mining site, suggesting the emergent source of mining activities for the MSs in the remote environment of the Tibetan Plateau. Employing the innovative model of robust absolute principal component scores-robust geographically weighted regression (RAPCS-RGWR), the analysis predicted that the mining operations contributing 57.1 % of the total soil MSs, would significantly surpass contributions from traffic emissions (14.7 %), residential activities (13.2 %), and the environmental factor of total organic matter content (14.9 %). The Boltzmann equation effectively modeled the distribution pattern of soil MSs, highlighting atmospheric transport and gravitational settling as key distribution mechanisms. However, linear-MSs exhibited longer transport distances than cyclic-MSs and were more profoundly affected by prevailing wind directions, suggesting their differential environmental behaviors and risks. Our study underscored that the mining sector possibly emerged as a significant source of Tibetan MSs, and provided insights into the transport and fate of MSs in remote, high-altitude environments. The findings emphasize the need for targeted pollution control strategies to mitigate the environmental footprint of mining activities in Tibet and similar regions.

Consumption of probiotic SLAB51 enhances ventilatory acclimatization to high altitude

Ventilatory acclimatization to hypoxia (VAH) is crucial for adjusting to physiologically stressful high-altitude environments. Increased ventilatory and cardiac responses to low-oxygen (O2) may partially mitigate deleterious effects at high altitude. Previous studies show that administration of the probiotic SLAB51 (O2booster; Hecto, Seoul, South Korea) improves O2 saturation in patients suffering from COVID-19 and O2-treated prematurely born babies. Since changes in ventilation may contribute to increase O2 saturation, we hypothesize that acute administration of SLAB51 to sojourners traveling to high altitude will increase respiratory responses to hypoxia. We measured minute ventilation (VI) and heart rate (HR) during normoxia and acute isocapnic hypoxia in 17 healthy participants (9 males, 8 females) of Latino ancestry with residence at sea level in San Diego and surrounding areas. We performed control experiments at sea level and then the participants were taken to White Mountain Barcroft Station (12,470ft / 3,800m) to repeat the measurements. At high altitude, the participants underwent a double-blind, placebo-controlled study with administration of placebo (n=8) or SLAB51 probiotic (n=9) up to three times per day for up to four days. Recordings of physiological parameters were obtained during steady-state at different gas mixtures with continuous monitoring of O2 saturation to target 10% desaturation during the acute hypoxia stimulus. We measured hypoxic ventilatory and heart rate responses (HVR and HHRR, respectively) and compared results between placebo and probiotic groups (mean ± SEM). As expected, high altitude increased VI and HR values compared to sea-level measurements in all participants. However, at high altitude, we found a significant increase of VI (p&lt;0.02) in participants consuming SLAB51 (0.275+0.015 L/min per Kg) when compared to those administered with placebo (0.207±0.025 L/min per Kg) during exposure to acute hypoxia. Administration of SLAB51 did not produce differences in HR responses at high altitude, and HVR and HHRR were not significantly different with SLAB51 treatment. Our results show that consumption of the probiotic SLAB51 increases ventilatory responses to hypoxia at high altitude without affecting hypoxia-induced changes in HR, suggesting that SLAB51 probiotic intervention may contribute to ventilatory acclimatization to hypoxia, although future studies are required to determine the mechanisms underlying this potential response. Supported by LEA Altitude Performance Fund. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Recent selection and introgression facilitated high-altitude adaptation in cattle

During the past 3000 years, cattle on the Qinghai-Xizang Plateau have developed adaptive phenotypes under the selective pressure of hypoxia, ultraviolet (UV) radiation, and extreme cold. The genetic mechanism underlying this rapid adaptation is not yet well understood. Here, we present whole-genome resequencing data for 258 cattle from 32 cattle breeds/populations, including 89 Tibetan cattle representing eight populations distributed at altitudes ranging from 3400 m to 4300 m. Our genomic analysis revealed that Tibetan cattle exhibited a continuous phylogeographic cline from the East Asian taurine to the South Asian indicine ancestries. We found that recently selected genes in Tibetan cattle were related to body size (HMGA2 and NCAPG) and energy expenditure (DUOXA2). We identified signals of sympatric introgression from yak into Tibetan cattle at different altitudes, covering 0.64%–3.26% of their genomes, which included introgressed genes responsible for hypoxia response (EGLN1), cold adaptation (LRP11), DNA damage repair (LATS1), and UV radiation resistance (GNPAT). We observed that introgressed yak alleles were associated with noncoding variants, including those in present EGLN1. In Tibetan cattle, three yak introgressed SNPs in the EGLN1 promoter region reduced the expression of EGLN1, suggesting that these genomic variants enhance hypoxia tolerance. Taken together, our results indicated complex adaptation processes in Tibetan cattle, where recently selected genes and introgressed yak alleles jointly facilitated rapid adaptation to high-altitude environments.

Influences of ski-runs, meadow management and climate on the occupancy of reptiles and amphibians in a high-altitude environment of Italy.

Alpine ecosystems harbour a rich and highly specialised biodiversity, which is particularly susceptible to anthropogenic disturbances such as habitat loss and fragmentation as well as to climate change. Combined with other forms of land-use conversion, construction and maintenance of ski resorts can have severe consequences on alpine biodiversity. In this study, we show how one amphibian and two reptile species, namely Rana temporaria, Zootoca vivipara and Vipera berus, respond to such impacts by means of a multi-season occupancy analysis. We found all three species both in and outside ski-runs, showing that these habitats do not necessarily preclude their occurrence. Contrarily, this is influenced more by microhabitat availability, such as ground vegetation, humid areas and rock cover, rather than by macro-characteristics like elevation or habitat type. Moreover, we found a climatic influence on the year-to-year occupancy change of the species, with activity-month conditions being more relevant than overwintering ones. Our results demonstrate how, in the specific case of reptiles and amphibians, ski resorts do not necessarily limit species' occurrence and that a mild series of management actions might secure the species' persistence in the area.

Impact of Haemoglobin and Haematocrit on the Incidence of Thrombosis in the Individuals Exposed to High-Altitude

Impact of Haemoglobin and Haematocrit on the Incidence of Thrombosis in the Individuals Exposed to High-Altitude

Identification of a Rye Spring Mutant Derived from a Winter Rye Variety by High-Altitude Environment Screening Using RNA Sequencing Technology.

Wintergrazer-70 and Ganyin No1 are high-yield forage varieties suitable for cultivation in high-altitude areas of Tibet (4300 m above sea level). Ganyin No1 was developed from Wintergrazer-70, with the latter serving as its parent variety. Ganyin No1 was identified as a spring variety, and subsequent RNA sequencing was conducted. RNA sequencing analysis identified 4 differentially expressed genes related to vernalization and 28 genes related to photoperiod regulation. The Sc7296g5-i1G3 gene is related to the flowering inhibition of rye, which may be related to the phenotypic difference in the Ganyin No1 variety in winter and spring. This finding provides valuable insights for future research on Ganyin No1, especially in addressing feed shortages in Tibet during winter and spring.