Avoiding contingent incidents by quadrotors due to one or two propellers failure.

With the increasing impact of drones in our daily lives, safety issues have become a primary concern. In this study, a novel supervisor-based active fault-tolerant (FT) control system is presented for a rotary-wing quadrotor to maintain its pose in 3D space upon losing one or two propellers. Our approach allows the quadrotor to make controlled movements about a primary axis attached to the body-fixed frame. A multi-loop cascaded control architecture is designed to ensure robustness, stability, reference tracking, and safe landing. The altitude control is performed using a proportional-integral-derivative (PID) controller, whereas linear-quadratic-integral (LQI) and model-predictive-control (MPC) have been investigated for reduced attitude control and their performance is compared based on absolute and mean-squared error. The simulation results affirm that the quadrotor remains in a stable region, successfully performs the reference tracking, and ensures a safe landing while counteracting the effects of propeller(s) failures.

The association between living altitude and serum leptin concentrations in native women.

Background: Lower diabetes prevalence and cardiovascular mortality have been observed in residents at a higher altitude. Leptin is associated with incident diabetes and adverse cardiovascular outcomes, and our aim was to investigate the association of living altitude with serum leptin concentrations. Methods: Two cross-sectional surveys were used in this study, including native populations living at Tibet (high altitude) and Beijing (low altitude). A propensity score was conducted for matching age and body mass index (BMI) between native women at high and low altitude. Pearson's correlation analysis was performed to evaluate the correlation of leptin with other variables. Results: A total of 1414 native women were included in this study, including 594 at high altitude and 820 at low altitude. The serum leptin concentrations of native women living at high altitude were 13.74 ± 11.03 ng/ml, which was significantly lower than that of native women living at low altitude (20.90 ± 12.91 ng/ml). After matching age and BMI, women living at the high altitude still had lower serum leptin concentrations. After adjusting for the potential confounding factors, the correlation coefficient between Ln (leptin) and BMI of women at high altitude was significantly lower than that of women at low altitude (0.228 versus 0.559; P <0.0001). The serum leptin concentrations of each BMI subgroup (<18.5, 18.5 to <25, 25 to <30, ≥ 30 kg/m2) in women at high altitude were lower than that in women at low altitude. Conclusions: Serum leptin concentrations were significantly decreased in native women living at high altitude, and living altitude may alter the correlation of BMI and leptin. The findings of our study support that residents at high altitude have a protective effect with regards to improving cardiovascular and metabolic outcomes.

Spatial structure and composition of invertebrates in high altitude rivers of the central Andes (Olaroz Salar, Argentina).

This study aimed to examine the spatial variation in sets of micro and macroinvertebrates and to detect how physicochemical and environmental variables affect community structures in high Andean rivers. Six sites were sampled in three rivers of the Argentinian plateau, in altitudes between 3900-4400 masl during the dry season (May-October 2017). The variables that affected the structure of the micro and macroinvertebrate communities were: altitude, conductivity, turbidity, water temperature, hardness, oxygen, and lead. Sites with high levels of arsenic, lead and boron were identified. Assemblages of species common to high Andean courses were recorded on a north-south axis. The registered community structure has similarities with High Andean streams of Bolivia and rivers of the Catamarca plateau, increasing the differences in composition and assemblages towards the south (Mendoza and Patagonian Andes). Diptera was the best represented with Orthocladiinae and Podonominae, reaching better representativeness at higher altitudes. Together with them, Austrelmis, Hydracarina, Hirudinea, Nais, Hyalella constitute the dominant group. There is a trend towards a decrease in the richness of species with respect to altitude, related to the proximity of the Salar and the increase in conductivity, carbonates and hardness.

[Sleep-Disordered Breathing at High Altitude: Its Characteristics and Research Progress in Treatment].

Hypobaric hypoxia in regions of high altitude may increase the risk of having sleep-disordered breathing (SDB). SDB at high altitude mainly refers to the SDB incurred in highlanders and lowlanders at a high altitude. At present, research on SDB at high altitude is mainly focused on these two groups of people. On the one hand, highlanders have SDB at a higher prevalence and greater severity than lowlanders do and highlanders have a prolonged duration of apnea when they travel to low-altitude regions. On the other hand, the severity of SDB increased in lowlanders when they travel to high altitude, represented mainly by an increase in central and hypopnea events. In terms of treatment, a substantial number of studies have shown that medication, including acetazolamide and dexamethasone, and nocturnal oxygen supplementation could improve SDB in lowlanders when they travel to high altitude. However, not much research has been done on the treatment of SDB in highlanders and it has only been reported that nocturnal oxygen supplementation was an available treatment option. Herein, we summarized the latest research findings on SDB at high altitude, providing the basis for further studies about the characteristics and treatments for highlanders with SDB.

[Factors affecting pulmonary arterial pressure in response to high-altitude hypoxic stress].

The alteration of pulmonary artery pressure is an important physiological indicator to reflect the organism's adaptation to acclimatization or the pathological injury in response to high-altitude hypoxic environment. The effects of hypoxic stress at different altitudes for different time on pulmonary artery pressure are different. There are many factors involved in the changes of pulmonary artery pressure, such as the contraction of pulmonary arterial smooth muscle, hemodynamic changes, abnormal regulation of vascular activity and abnormal changes of cardiopulmonary function. Understanding of the regulatory factors of pulmonary artery pressure in hypoxic environment is crucial in clarifying the relevant mechanisms of hypoxic adaptation, acclimatization, prevention, diagnosis, treatment and prognosis of acute and chronic high-altitude diseases. In recent years, great progress has been made in the study regarding the factors affecting pulmonary artery pressure in response to high-altitude hypoxic stress. In this review, we discuss the regulatory factors and intervention measures of pulmonary arterial hypertension induced by hypoxia from the aspects of hemodynamics of circulatory system, vasoactive state and changes of cardiopulmonary function.

Extensive prevalence and significant genetic differentiation of Blastocystis in high- and low-altitude populations of wild rhesus macaques in China.

BACKGROUND: Blastocystis is a common intestinal protist with a wide range of hosts. Thus far, 38 subtypes have been identified. In recent years, wild animals have been confronted with habitat fragmentation as well as an increasing risk of zoonotic disease transmission due to human disturbance. Only limited data are available on Blastocystis infection and subtype distribution in wild rhesus macaques in China. The aim of the present study was to investigate the prevalence and genetic diversity of Blastocystis in nine wild rhesus macaque populations in China. METHODS: A total of 276 faecal samples were collected from five high-altitude populations (high-altitude group [HAG]; 2800-4100 m a.s.l.) and four low-altitude populations (low-altitude group [LAG]; 5-1000 m a.s.l) of rhesus macaques. PCR-based analysis, using a new primer pair for the amplification of a 1690-bp sequence of the small subunit ribosomal RNA (SSU rRNA) gene, was used for prevalence and genetic diversity analysis. RESULT: Analysis of faecal samples revealed that Blastocystis infection was common in rhesus macaques, with an infection positivity rate of 80.1% (n = 221/276 samples). There was no significant difference (P = 0.121) in positivity rate between the LAG (84.3%) and HAG (76.8%). Overall, 33 haplotypes were obtained and classified into four subtypes (STs), of which three were potentially zoonotic subtypes (ST1, 29.7%; ST2, 16.7%; ST3, 31.9%) and one that was first identified in this study and named ST39 (12.0%). The STs were distributed differently among the rhesus macaque populations, except for ST3, which was found in all populations. Phylogenetic analyses revealed two major divergent clades of ST3 for the HAG and LAG. Genetic diversity analysis showed a high genetic diversity of ST3 (haplotype diversity: 0.846; nucleotide diversity: 0.014) in the rhesus macaques, but a high genetic differentiation (FST > 0.25) and a low gene flow (Nm = 0.09) between the HAG and LAG. CONCLUSION: Our study, which is the first investigation on Blastocystis infection in multiple wild rhesus macaque populations in China, indicates a potential risk of zoonotic transmission of Blastocystis in the study areas. Blastocystis ST3 showed high genetic diversity in wild rhesus macaques and significant genetic differentiation between the HAG and LAG. Our results provide fundamental information on the genetic diversity and prevalence of Blastocystis in wild rhesus macaque populations.

Development and validation of nomogram including high altitude as a risk factor for COPD: A cross-sectional study based on Gansu population.

Background: Chronic Obstructive Pulmonary Disease (COPD) is a common and harmful disease that requires an effective tool to early screen high-risk individuals. Gansu has unique environments and customs, leading to the different prevalence and etiology of COPD from other regions. The association between altitude and COPD once attracted epidemiologists' attention. However, the prevalence in Gansu and the role of altitude are still unclarified. Methods: In Gansu, a multistage stratified cluster sampling procedure was utilized to select a representative sample aged 40 years or older. The questionnaire and spirometry examination were implemented to collect participants' information. The diagnosis and assessment of COPD were identified by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criterion, while post-bronchodilator FEV1/FVC < LLN was for sensitivity analysis. Furthermore, the effect of high altitude on COPD was evaluated by the logistic regression model after propensity score matching (PSM). Finally, the participants were randomly divided into training and validation sets. The training set was used to screen the relative factors and construct a nomogram which was further assessed by the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA) in the two sets. Results: There were 2,486 eligible participants in the final analysis, of which 1,584 lived in low altitudes and 902 lived in high altitudes. Based on the GOLD criterion, the crude and standardized prevalences in Gansu were 20.4% (18.7-22.0) and 19.7% (17.9-21.6). After PSM, the logistic regression model indicated that high altitude increased COPD risk [PSM OR: 1.516 (1.162-1.978)]. Altitude, age, sex, history of tuberculosis, coal as fuel, and smoking status were reserved for developing a nomogram that demonstrated excellent discrimination, calibration, and clinical benefit in the two sets. Conclusions: COPD has become a serious public health problem in Gansu. High altitude is a risk factor for COPD. The nomogram has satisfactory efficiency in screening high-risk individuals.

Ecological drivers and consequences of torpor in Andean hummingbirds.

Daily torpor allows endotherms to save energy during energetically stressful (e.g. cold) conditions. Although studies on avian torpor have mostly been conducted under laboratory conditions, information on the usage of torpor in the wild is limited to few, predominantly temperate-zone species. We studied torpor under seminatural conditions from 249 individuals from 29 hummingbird species across a 1920 m elevational gradient in the western Andes of Colombia using cloacal thermistors. Small birds were more likely to use torpor than large birds, but only at low ambient temperatures, where torpor was prolonged. We also found effects of proxy variables for body condition and energy expenditure on the use of torpor, its characteristics, and impacts. Our results suggest that context-dependency and phylogenetic variation in the probability of deploying torpor can help understand clade-wide patterns of elevational distribution in Andean hummingbirds.

[Associations between glycated hemoglobin and glucose indicators in adults in areas at different altitude in China].

Objective: To explore the associations of glycated hemoglobin (HbA1c) with FPG and oral glucose tolerance test 2-hour (OGTT-2 h) in areas at different altitude in China. Methods: Subjects who participated in 2018-2019 China Chronic Disease and Risk Factor Surveillance and had no prior type 2 diabetes diagnosis were included. Subsequently, they were categorized into three groups based on altitude of living area (<2 000, 2 000- and ≥3 000 m). With adjustment for intracluster correlation, multivariable linear regression analysis was performed to evaluate the associations of HbA1c with FPG and OGTT-2 h in the context of HbA1c was normal (<5.7%) or abnormal (≥5.7%). Furthermore, the shape of relationships between HbA1c and glucose indicators was examined using restricted cubic spline. Finally, receiver operating characteristic curve was used to evaluate the diagnostic performance of HbA1c for diabetes. Results: A total of 157 277 subjects were included in the analysis. While FPG and OGTT-2 h levels gradually decreased with increase of altitude, HbA1c level was similar among the three groups. When HbA1c was <5.7%, its association with FPG and OGTT-2 h was weak and no obvious difference was observed among the three groups. When HbA1c was ≥5.7%, the FPG and OGTT-2 h increased by 15.45% (95%CI:14.71%- 16.18%) and 24.54% (95%CI:23.18%-25.91%) respectively per one standard deviation increase in HbA1c in group in area at altitude <2 000 m. However, the FPG and OGTT-2 h increased by 13.08% (95%CI:10.46%-15.76%) and 21.72% (95%CI:16.39%-27.31%), respectively, in group in area at altitude 2 000- m, and increased by 11.41% (95%CI:9.32%-13.53%) and 20.03% (95%CI:15.38%- 24.86%), respectively, in group of altitude ≥3 000 m. The restricted cubic spline indicated that the curve showing the association of HbA1c with FPG and OGTT-2 h was flat when HbA1c was <5.7%, but showed a positive linear relationship when HbA1c was ≥5.7%. The area under curve for detecting diabetes was 0.808 (95%CI:0.803-0.812) in group of altitude <2 000 m and 0.728 (95%CI:0.660-0.796, P=0.022) in group of altitude ≥3 000 m. The relevant optimal cutoff value of HbA1c was 5.7%, with a sensitivity of 65.4% and a specificity of 83.0%, and 6.0%, with a sensitivity of 48.3% and a specificity of 93.7%, respectively. Conclusions: When HbA1c was ≥5.7%, the association between HbA1c and glucose indicators became weaker as the increase of altitude. In the area at altitude ≥3 000 m, it may not be appropriate to use HbA1c in the diagnosis of diabetes.

Features of Coagulo-Fibrinolytic Derangement Due to Bleeding in Nonacclimatized Rabbits Acutely Exposed to High Altitude.

Zhong, Xin, Wenqiong Du, Zhaowen Zong, Renqing Jiang, Yijun Jia, Zhao Ye, and Haoyang Yang. Features of coagulo-fibrinolytic derangement due to bleeding in nonacclimatized rabbits acutely exposed to high altitude. High Alt Med Biol. 24:68-75, 2023. Background: The present study aimed to observe the time course of coagulo-fibrinolytic derangement due to bleeding in rabbits acutely exposed to high altitude (HA). Materials and Methods: Forty-eight rabbits were randomly divided into four groups and were subjected to minor bleeding at low altitude, major bleeding at low altitude, minor bleeding after acute exposure to HA, and major bleeding after acute exposure to HA. To produce minor and major bleeding, 10% and 30% of the total blood volume was removed, respectively. At designated time points, samples were taken for laboratory examination. Results: While minor bleeding at low altitude led to minor coagulo-fibrinolytic derangements, it led to complicated derangements at HA, which presented as an early hypercoagulable state and transition to hypocoagulable and hyperfibrinolytic states with lower clot firmness. Major bleeding at HA resulted in greater derangements of the R time, K values, the D-dimer concentration, the alpha angle, maximum amplitude, and the concentration of fibrinogen than were observed at low altitude. Conclusions: The extent of coagulo-fibrinolytic derangements due to bleeding in rabbits after acute exposure to HA was more severe and complicated than that at low altitude. Therefore, proper resuscitation should be applied based on these changes.

Evaluation of blood cellular and biochemical parameters in rats under a chronic hypoxic environment at high altitude.

BACKGROUND: The purpose of this study was to explore the changes in blood cellular and biochemical parameters of rats in a natural environment of low pressure and low oxygen on the plateau. METHODS: Male Sprague-Dawley rats in two groups were raised in different environments from 4 weeks of age for a period of 24 weeks. They were raised to 28 weeks of age and then transported to the plateau medical laboratory of Qinghai University. Blood cellular and biochemical parameters were measured and the data of the two groups were statistically analyzed. RESULTS: 1. RBC in the HA group was higher than that in the Control group, but there was no significant difference between the two groups (p > 0.05), Compared with the Control group, HGB, MCV, MCH, MCHC and RDW in the HA group were significantly higher (p < 0.05). 2. Compared with the Control group, WBC, LYMP, EO, LYMP% and EO% in the HA group decreased significantly (p < 0.05), and ANC% increased significantly (p < 0.05). 3. In the platelet index, compared with the Control group, PLT in the HA group was significantly reduced (p < 0.05), PDW, MRV, P-LCR were significantly increased (p < 0.05). 4. In blood biochemical indicators, compared with the Control group, AST, TBIL, IBIL, LDH in the HA group decreased significantly (p < 0.05), CK in the HA group increased significantly (p < 0.05). CONCLUSIONS: 1. The indexes related to red blood cells, white blood cells, platelets and some biochemical indexes in the blood of rats at high altitude have changed. 2. Under the high altitude environment, the oxygen carrying capacity of SD rats is improved, the resistance to disease may be reduced, the coagulation and hemostasis functions may be affected, and there is a risk of bleeding. The liver function, renal function, heart function and skeletal muscle energy metabolism may be affected. 3. This study can provide an experimental basis for the research on the pathogenesis of high-altitude diseases from the perspective of blood.KEY MESSAGESIn this study, red blood cells, white blood cells, platelets and blood biochemical indicators were included in the real plateau environment to comprehensively analyze the changes of blood cellular and biochemical parameters in rats under the chronic plateau hypobaric hypoxia environment.From the perspective of blood, this study can provide an experimental basis for research on the pathogenesis of high-altitude diseases.Explore the data support of oxygen-carrying capacity, disease resistance and energy metabolism of the body in the natural environment at high altitude.

Weak gene-gene interaction facilitates the evolution of gene expression plasticity.

BACKGROUND: Individual organisms may exhibit phenotypic plasticity when they acclimate to different conditions. Such plastic responses may facilitate or constrain the adaptation of their descendant populations to new environments, complicating their evolutionary trajectories beyond the genetic blueprint. Intriguingly, phenotypic plasticity itself can evolve in terms of its direction and magnitude during adaptation. However, we know little about what determines the evolution of phenotypic plasticity, including gene expression plasticity. Recent laboratory-based studies suggest dominance of reversing gene expression plasticity-plastic responses that move the levels of gene expression away from the new optima. Nevertheless, evidence from natural populations is still limited. RESULTS: Here, we studied gene expression plasticity and its evolution in the montane and lowland populations of an elevationally widespread songbird-the Rufous-capped Babbler (Cyanoderma ruficeps)-with reciprocal transplant experiments and transcriptomic analyses; we set common gardens at altitudes close to these populations' native ranges. We confirmed the prevalence of reversing plasticity in genes associated with altitudinal adaptation. Interestingly, we found a positive relationship between magnitude and degree of evolution in gene expression plasticity, which was pertinent to not only adaptation-associated genes but also the whole transcriptomes from multiple tissues. Furthermore, we revealed that genes with weaker expressional interactions with other genes tended to exhibit stronger plasticity and higher degree of plasticity evolution, which explains the positive magnitude-evolution relationship. CONCLUSIONS: Our experimental evidence demonstrates that species may initiate their adaptation to new habitats with genes exhibiting strong expression plasticity. We also highlight the role of expression interdependence among genes in regulating the magnitude and evolution of expression plasticity. This study illuminates how the evolution of phenotypic plasticity in gene expression facilitates the adaptation of species to challenging environments in nature.

Unanticipated metabolic plasticity in response to chronic hypoxia.

In this issue of Cell Metabolism, Midha et al. investigate the metabolic changes in mice after exposure to reduced oxygen tension for an acute or chronic duration. Their organ-specific findings may help explain physiological observations in humans living at high altitude but raise additional questions concerning pathological hypoxia after vascular damage or in cancer.

Oceanic climate changes threaten the sustainability of Asia's water tower.

Water resources sustainability in High Mountain Asia (HMA) surrounding the Tibetan Plateau (TP)-known as Asia's water tower-has triggered widespread concerns because HMA protects millions of people against water stress1,2. However, the mechanisms behind the heterogeneous trends observed in terrestrial water storage (TWS) over the TP remain poorly understood. Here we use a Lagrangian particle dispersion model and satellite observations to attribute about 1 Gt of monthly TWS decline in the southern TP during 2003-2016 to westerlies-carried deficit in precipitation minus evaporation (PME) from the southeast North Atlantic. We further show that HMA blocks the propagation of PME deficit into the central TP, causing a monthly TWS increase by about 0.5 Gt. Furthermore, warming-induced snow and glacial melt as well as drying-induced TWS depletion in HMA weaken the blocking of HMA's mountains, causing persistent northward expansion of the TP's TWS deficit since 2009. Future projections under two emissions scenarios verified by satellite observations during 2020-2021 indicate that, by the end of the twenty-first century, up to 84% (for scenario SSP245) and 97% (for scenario SSP585) of the TP could be afflicted by TWS deficits. Our findings indicate a trajectory towards unsustainable water systems in HMA that could exacerbate downstream water stress.

Red-listed plants are contracting their elevational range faster than common plants in the European Alps.

Mountain ecosystems are exposed to multiple anthropogenic pressures that are reshaping the distribution of plant populations. Range dynamics of mountain plants exhibit large variability with species expanding, shifting, or shrinking their elevational range. Using a dataset of more than 1 million records of common and red-listed native and alien plants, we could reconstruct range dynamics of 1,479 species of the European Alps over the last 30 y. Red-listed species were not able to track climate warming at the leading edge of their distribution, and further experienced a strong erosion of rear margins, resulting in an overall rapid range contraction. Common natives also contracted their range, albeit less drastically, through faster upslope shift at the rear than at the leading edge. By contrast, aliens quickly expanded upslope by moving their leading edge at macroclimate change speed, while keeping their rear margins almost still. Most red-listed natives and the large majority of aliens were warm-adapted, but only aliens showed high competitive abilities to thrive under high-resource and disturbed environments. Rapid upward shifts of the rear edge of natives were probably driven by multiple environmental pressures including climate change as well as land-use change and intensification. The high environmental pressure that populations encounter in the lowlands might constrain the ability of expanding species to shift their range into more natural areas at higher elevations. As red-listed natives and aliens mostly co-occurred in the lowlands, where human pressures are at their highest, conservation should prioritize low-elevation areas of the European Alps.

Ecological distribution and genetic diversity of Azolla in Uganda.

BACKGROUND: Azolla is an important aquatic fern whose agronomic potential has not been fully exploited in Uganda. This study aimed at determining the genetic variation in the Azolla species existing in Uganda and the factors influencing their distribution in the different agro-ecological zones of Uganda. Molecular characterization was preferred in this study because of its efficiency in detecting variations among closely related species. RESULTS: Four species of Azolla were identified in Uganda with 100, 93.36, 99.22 and 99.39% sequence identities to the reference database sequences of; Azolla mexicana, Azolla microphylla, Azolla filiculoides and Azolla cristata, respectively. These different species were distributed in four out of the ten agro-ecological zones of Uganda which are situated in close vicinity to large water masses. The principal component analysis (PCA) results revealed that maximum rainfall and altitude significantly accounted for the variations in the distribution of Azolla with factor loadings of 0.921 and 0.922, respectively. CONCLUSION: Massive destruction coupled with prolonged disturbance of Azolla's habitat negatively affected its growth, survival and distribution in the country. Therefore, there is a need to develop standard methods that can preserve the various species of Azolla, so as to salvage them for future use, research and reference.

Impact of high altitude on composition and functional profiling of oral microbiome in Indian male population.

The oral cavity of human contains bacteria that are critical for maintaining the homeostasis of the body. External stressors such as high altitude (HA) and low oxygen affect the human gut, skin and oral microbiome. However, compared to the human gut and skin microbiome, studies demonstrating the impact of altitude on human oral microbiota are currently scarce. Alterations in the oral microbiome have been reported to be associated with various periodontal diseases. In light of the increased occurrence of HA oral health related problems, the effect of HA on the oral salivary microbiome was investigated. We conducted a pilot study in 16 male subjects at two different heights i.e., H1 (210 m) and H2 (4420 m). Total of 31 saliva samples,16 at H1 and 15 at H2 were analyzed by utilizing the 16S rRNA high-throughput sequencing, to explore the relationship between the HA environment and salivary microbiota. The preliminary results suggesting that, the most abundant microbiome at the phylum level are: Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. Interestingly, 11 genera were identified at the both heights with different relative abundances. In addition, the salivary microbiome was more diverse at H1 compared to H2 as demonstrated by decreased alpha diversity. Further, predicted functional results indicate that microbial metabolic profiles significantly decreased at H2 as compared to H1, including two major metabolic pathways involving carbohydrates, and amino acids. Our findings show that HA induces shifts in the composition and structure of human oral microbiota which can affect host health homeostasis.

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).

[Responses of blood parameters and hemoglobin subtypes in plateau zokors and plateau pikas to different altitude habitats].

The plateau zokor (Myospalax baileyi) and plateau pika (Ochotona curzoniae) are native species unique to the Qinghai-Tibetan Plateau with successful adaptation to the hypoxic environment. In this study, the number of red blood cells, hemoglobin concentration, mean hematocrit and mean volume of red blood cells were measured in plateau zokors and plateau pikas at different altitudes. Hemoglobin subtypes of two plateau animals were identified by mass spectrometry sequencing. The forward selection sites in two animals' hemoglobin subunits were analyzed by PAML4.8 program. Homologous modeling was used to analyze the effect of forward selection sites on the affinity of hemoglobin to oxygen. The adapting strategies of plateau zokors and plateau pikas to hypoxia at different altitudes were analyzed through comparing blood parameters between the two species. The results indicated that, with increasing altitudes, plateau zokors responded to hypoxia by increasing red blood cell count and decreasing red blood cell volume, while plateau pikas took the opposite strategies to plateau zokors. In erythrocytes of plateau pikas, both adult α2ß2 and fetal α2ε2 hemoglobins were identified, while erythrocytes of plateau zokors only had adult α2ß2 hemoglobin, however the affinities and the allosteric effects of the hemoglobin of plateau zokors were significantly higher than those of plateau pikas. Mechanistically, in the α and ß subunits of hemoglobin of plateau zokors and pikas, the numbers and the sites of the positively selected amino acids as well as the side chain groups polarities and orientations of the amino acids differed significantly, which may result in the difference of the affinities to oxygen of hemoglobin between plateau zokors and pikas. In conclusion, the adaptive mechanisms to respond to hypoxia in blood properties of plateau zokors and plateau pikas are species-specific.