Lake Bacterial Communities in North Patagonian Andes: The Effect of the Nothofagus pumilio Treeline.

One of the most noticeable environmental discontinuities in mountains is the transition that exists in vegetation below and above the treeline. In the North Patagonian Andean lakes (between 900 and 1950 m a.s.l.), we analyzed the bacterial community composition of lakes in relation to surrounding vegetation (erected trees, krummholz belt, and bare rocks), dissolved organic carbon (DOC), and total dissolved nutrients (nitrogen, TDN and phosphorus, TDP). We observed a decrease in DOC, TDP, and TDN concentrations with altitude, reflecting shifts in the source inputs entering the lakes by runoff. Cluster analysis based on bacterial community composition showed a segregation of the lakes below treeline, from those located above. This first cluster was characterized by the cyanobacteria Cyanobium PCC-6307, while in the krummholz belt and bare rocks, bacterial communities were dominated by Actinobacteria hgcl-clade and Proteobacteria (Sandarakinorhabdus and Rhodovarius), with the presence of pigments such as actinorhodopsin, carotenoids, and bacteriochlorophyll a. The net relatedness index (NRI), which considers the community phylogenetic dispersion, showed that lakes located on bare rocks were structured by environmental filtering, while communities of lakes below treeline were structured by species interactions such as competition. Beta-diversity was higher among lakes below than among lakes located above the treeline. The contribution of species turnover was more important than nestedness. Our study brings light on how bacterial communities may respond to changes in the surrounding vegetation, highlighting the importance of evaluating different aspects of community structure to understand metacommunity organization.

Behavioural Thermoregulation of Flowers via Petal Movement.

Widely documented in animals, behavioural thermoregulation mitigates negative impacts of climate change. Plants experience especially strong thermal variability but evidence for plant behavioural thermoregulation is limited. Along a montane elevation gradient, Argentina anserina flowers warm more in alpine populations than at lower elevation. We linked floral temperature with phenotypes to identify warming mechanisms and documented petal movement and pollinator visitation using time-lapse cameras. High elevation flowers were more cupped, focused light deeper within flowers and were more responsive to air temperature than low; cupping when cold and flattening when warm. At high elevation, a 20° increase in petal angle resulted in a 0.46°C increase in warming. Warming increased pollinator visitation, especially under cooler high elevation temperatures. A plasticity study revealed constitutive elevational differences in petal cupping and stronger temperature-induced floral plasticity in high elevation populations. Thus, plant populations have evolved different behavioural responses to temperature driving differences in thermoregulatory capacity.

Reference equations for DLNO and DLCO in Mexican Hispanics: influence of altitude and race.

OBJECTIVES: This study aimed to evaluate pulmonary diffusing capacity for nitric oxide (DLNO) and pulmonary diffusing capacity for carbon monoxide (DLCO) in Mexican Hispanics born and raised at 2240 m altitude (midlanders) compared with those born and raised at sea level (lowlanders). It also aimed to assess the effectiveness of race-specific reference equations for pulmonary diffusing capacity (white people vs Mexican Hispanics) in minimising root mean square errors (RMSE) compared with race-neutral equations. METHODS: DLNO, DLCO, alveolar volume (VA) and gas transfer coefficients (KNO and KCO) were measured in 392 Mexican Hispanics (5 to 78 years) and compared with 1056 white subjects (5 to 95 years). Reference equations were developed using segmented linear regression (DLNO, DLCO and VA) and multiple linear regression (KNO and KCO) and validated with Least Absolute Shrinkage and Selection Operator. RMSE comparisons between race-specific and race-neutral models were conducted using repeated k-fold cross-validation and random forests. RESULTS: Midlanders exhibited higher DLCO (mean difference: +4 mL/min/mm Hg), DLNO (mean difference: +7 mL/min/mm Hg) and VA (mean difference: +0.17 L) compared with lowlanders. The Bayesian information criterion favoured race-specific models and excluding race as a covariate increased RMSE by 61% (DLNO), 18% (DLCO) and 4% (KNO). RMSE values for VA and KCO were comparable between race-specific and race-neutral models. For DLCO and DLNO, race-neutral equations resulted in 3% to 6% false positive rates (FPRs) in Mexican Hispanics and 20% to 49% false negative rates (FNRs) in white subjects compared with race-specific equations. CONCLUSIONS: Mexican Hispanics born and raised at 2240 m exhibit higher DLCO and DLNO compared with lowlanders. Including race as a covariate in reference equations lowers the RMSE for DLNO, DLCO and KNO and reduces FPR and FNR compared with race-neutral models. This study highlights the need for altitude-specific and race-specific reference equations to improve pulmonary function assessments across diverse populations.

Association between frailty and activities of daily living disability in older adults residing in a high-altitude Peruvian Andean community: the Aunqui-Andes study.

BACKGROUND: The prevalence of frailty and activities of daily living (ADL) disability may be higher in high-altitude Andean regions, due to chronic hypoxia, malnutrition, and physical challenges. and their association is relevant. This study aimed to evaluate the association between frailty and ADL disability among older adults residing in the Totos district in Peru during the year 2022. METHODS: A cross-sectional study was conducted in Totos district (mean altitude: 3286 m above sea level), located in Ayacucho, Peru, during 2022. A complete census was employed including residents aged 60 and above. The exposure variable was frailty, defined by fulfilling 3 or more criteria of the Fried phenotype. The outcome variable was ADL disability, defined as a score below 95 on the Barthel index. Generalized linear models with a Poisson family, logarithmic link function, and robust variances were employed to estimate crude prevalence ratios and adjusted prevalence ratios (aPRs), along with their corresponding 95% confidence intervals (CIs). RESULTS: We evaluated 272 older adults with a mean age of 74 years, of whom 59.9% were female, 62.1% were cohabiting or married and 83.1% had not completed primary education. We found that 19.5% were frail, while 51.1% had ADL disability. In the adjusted regression model, we found frailty increased the prevalence of ADL disability (aPR = 1.77; 95%CI: 1.44-2.16; p < 0.001). CONCLUSION: Frailty was associated with an increased prevalence of ADL disability. These findings could contribute to establishing government intervention plans to manage disability and frailty within the high-risk group comprising older adults living at high altitudes.

Performance in the Six-Minute Walking Test Does Not Discriminate Excessive Erythrocytosis Patients in a Severe Hypoxic Environment.

BACKGROUND: Chronic exposure to severe hypoxia causes an increase in hematocrit (Hct) and hemoglobin concentration ([Hb]), which can lead to excessive erythrocytosis (EE) and impact physical performance. This work aims to determine the differences in the six-minute walking test (6MWT) between EE and healthy subjects residing at more than 5000 m. METHODS: A prospective, cross-sectional study was performed on 71 men (36 healthy and 25 suffering from EE) living in La Rinconada, Peru (5100 m). Basal levels of [Hb] and Hct were obtained. All the subjects performed the 6MWT, and distance reached, vital signs, dyspnea, and fatigue (Borg scale) at the end of the test were recorded. RESULTS: The average [Hb] and Hct levels in the control group were 18.7 ± 1.2 g/dL and 60.4 ± 7.1%, respectively, contrasting with EE subjects, who showed 23.4 ± 1.6 g/dL and 73.6 ± 5.9% (p < 0.001). However, no statistically significant differences were observed in BMI or other anthropometric parameters. At the end of the 6MWT, the distance traveled and vital constants were similar between both groups, except for arterial oxygen saturation, which was consistently lower in subjects with EE throughout the test. CONCLUSION: EE does not significantly affect 6MWT performance at high altitudes, nor the hemodynamic control during moderate aerobic exercise of subjects who live permanently in a severely hypoxic environment.

Mountain sickness in altitude inhabitants of Latin America: A systematic review and meta-analysis.

OBJECTIVE: Chronic and acute mountain sickness is known worldwide, but most of the available information comes from the eastern continent (Himalayas) without taking into account the west which has the most recent group located at altitude, the Andes. The aim of this study was to synthesize the evidence on the prevalence of acute and chronic mountain sickness in Latin American countries (LATAM). METHODS: A systematic search of the variables of interest was performed until July 8, 2023 in the Web of Science, Scopus, PubMed and Embase databases. We included studies that assessed the prevalence of mountain sickness in high-altitude inhabitants (>1500 m.a.s.l) who lived in a place more than 12 months. These were analyzed by means of a meta-analysis of proportions. To assess sources of heterogeneity, subgroup analyses and sensitivity analyses were performed by including only studies with low risk of bias and excluding extreme values (0 or 10,000 ratio). PROSPERO (CRD42021286504). RESULTS: Thirty-nine cross-sectional studies (10,549 participants) met the inclusion criteria. We identified 5 334 and 2 945 events out of 10,000 with acute and chronic mountain sickness in LATAM countries. The most common physiological alteration was polycythemia (2,558 events), while cerebral edema was the less common (46 events). Clinical conditions were more prevalent at high altitudes for both types of MS. CONCLUSION: Acute mountain sickness (AMS) occurs approximately in 5 out of 10 people at high altitude, while chronic mountain sickness (CMS) occurs in 3 out of 10. The most frequent physiological alteration was polycythemia and the least frequent was cerebral edema.

Phytosociology and ecological framework of forest tree species in the Toormang Valley, Dir Lower, Hindu Kush Range, Pakistan.

The phytosociological survey was conducted during 2018-2020. The research area was classified into five ecological zones based on habitat, physiognomy and species composition. Pc-Ord software was used for cluster analysis and four vegetation communities were established. The Quercus baloot-Quercus incana community is situated in Sair at an altitude of 1196 (mean ± SE) m altitude with a 14.1 ± 0 slope angle and contains eleven tree species. The Pinus wallichiana- Ailanthus altissima community had a relatively small number of tree species reported in Shakawlie at 1556 (mean ± SE) with a 17.5 ± 0 slope angle. The Pinus wallichiana- Quercus incana community is distributed in Wali Kandao and Mangi Kandao at altitudes of 2030.5 (mean ± SE) m and the slope angle was 19.2 ± 1.4. This community possesses a total of twenty-one tree species and is highly diverse. Similarly, the Populus alba - Platanus orientalis group was present in Banr Pate, with an altitude of 1613 (mean ± SE) m and a 16.3 slope angle. The principal component analysis (PCA) and non-metric multidimensional scaling (NMS) ordination methods were applied to study the relationships between ecological and soil variables with trees species. The NMS ordination of axis 1 was significantly correlated with Sand% (p<0.2), Nitrogen% (p<0.1) and Pb (mg/kg) (r= 0.876751, p<0.05), while the ordination of axis 2 was significantly correlated with Silt% (p<0.2), Sand% (p<0.2), Organic matter% (p<0.2), K (mg/kg) (r=0.882433, p<0.02), Fe (mg/kg)(r=0.614833, p<0.2), Ca (mg/kg) (r=0.721712, p< 0.2) and Zn (mg/kg) (r=0.609545, p<0.2). Similarly, the PCA ordination of axis 1 revealed that it was significantly correlated with phosphorus, calcium and slope angle, while that of axis 2 was significantly correlated with altitude, zinc and manganese.

Altitude is correlated with body size differences among Cotesia flavipes (Hymenoptera: Braconidae) wasps collected in two mountain ranges.

Living at high altitudes impose physiological and ecological challenges to which species may respond altering their body size, body proportions, and the shape of their body parts. Despite the importance of this topic for understanding the origin of species diversity, little attention has been invested in this phenomenon at the populational level. This paper study the relationship between altitude and body size, body proportions, and forewing shape venation of two populations of the parasitoid wasp Cotesia flavipes. Wasps were collected from Diatraea spp. larvae from sugarcane crops in two Colombian mountain ranges that cover between 600 m and 2143 m of altitude. Linear measurements of different body regions and geometric morphometrics of the forewing were subject to multivariate comparisons and allometric analyses to assess variation and to compare trends between ranges. Central (600 m to 1704 m) and Eastern Cordillera (877 m to 2143 m) populations showed different trends between body size and altitude. Allometric trends were not uniform within or between populations nor between structures. The allometric slopes of five body measurements from a single altitude differed from these from its own mountain range suggesting that body size trends along the cordilleras are a consequence of altitude and not of intrinsic body resource allocation processes. Wing shape between populations differed; however, these changes were poorly related to altitude. In agreement with recent studies in other groups, the observed allometric and wing shape differences between the two C. flavipes populations could be a plasticity response to altitude with interesting implications for posterior genetic differentiation.

Understanding processes underlying cross-taxon congruence in species composition along elevational gradients.

Changes in species diversity of different taxa along environmental gradients are usually correlated, resulting in a pattern called cross-taxon congruence. This pattern can be due to functional relationships between taxa, a common response to niche-related processes, or stochastic processes. However, it remains unclear the extent to which they contribute to the association among patterns of changes in species composition, (i.e., beta diversity), and whether these changes are related to species nestedness and turnover. Here we described patterns of change in the taxonomic composition of plant and orthopteran assemblages along an elevational gradient in Cordoba province, central Argentina. We assessed cross-taxon congruence and identified the main environmental variables accounting for such patterns. Mantel correlations showed congruence between the patterns of taxonomic dissimilarity of plants and orthopterans. According Generalized disiimilarity models (GDM) the main environmental variables driving the patterns were temperature for both taxa, and changes in soil nutrient content for plants, spatial effects were also found. Beta diversity was mainly due to species turnover for orthopterans and plants, indicating replacement by species adapted to elevational conditions. Niche-related process, such as environmetal filtering, along with neutral processes may have contributed to cross-taxon congruence in beta diversity.

Ethnic, geographical and altitude considerations and maternal mortality associated with HELLP syndrome in Ecuador: a population-based cohort study.

BACKGROUND: Eclampsia and pre-eclampsia rank as the third leading causes of maternal death in Ecuador, following pre-existing chronic diseases and postpartum haemorrhage, as reported by the Ecuadorian National Institute of Statistics and Census (INEC). In contrast, HELLP (Haemolysis, Elevated Liver enzymes, Low Platelet count) syndrome remains underexplored epidemiologically, not only in Latin America but globally. This study marks the first population-based investigation into HELLP syndrome incidence and mortality in Ecuador, examining geographical variations, altitude influences and ethnic backgrounds. METHODS: Conducted as a retrospective population-based cohort study from 2015 to 2017, this research delves into the incidence, risk factors and maternal mortality associated with HELLP syndrome in Ecuador. Utilising data from INEC and the Ecuadorian Ministry of Health, we identified HELLP syndrome cases through ICD-10 (International Classification of Diseases, tenth revision) coding in hospitalised individuals. Logistic regression analysis was employed to explore association, whilst geospatial statistical analysis focused on cantons to identify significant spatial clusters. Primary outcome measures include HELLP syndrome incidence and maternal mortality, supplying crucial insights into the syndrome's impact on maternal health in Ecuador. RESULTS: The incidence of HELLP syndrome is 0.76 (0.69-0.84)/ 1000 deliveries. Afro-Ecuadorian communities have a higher risk (Odds Ratio (OR) = 2.18 (1.03-4.63)) compared to Indigenous Ecuadorian communities. Living at mid-level or high altitude is a significant risk factor OR of 2.79 (2.19-3.55) and an OR 3.61 (2.58-5.03), respectively. Being an older mother was also identified as a risk factor. Women living more than 20 km from the obstetric unit have an OR of 2.55 (2.05-3.18). Moreover, we found that cantons with higher crude HELLP syndrome incidence also have lower numbers of physicians (R = 0.503, p-value < 0.001). The mortality incidence of women with HELLP syndrome is 21.22 (12.05-20.59)/1000 deliveries with HELLP syndrome diagnoses. CONCLUSIONS: High altitude, advanced maternal age and geographical distance between residence and health centres are risk factors for HELLP syndrome. Maternal mortality in women with HELLP syndrome is higher than pre-eclampsia and eclampsia but comparable with previous reports in other countries.

Species morphology better predicts plant-hummingbird interactions across elevations than nectar traits.

Species traits greatly influence interactions between plants and pollinators where floral nectar is the primary energy source fostering this mutualism. However, very little is known about how nectar traits mediate interactions in pollination networks compared with morphological traits. Here, we evaluated the role of morphological and nectar traits in shaping plant-hummingbird interaction networks along an elevation gradient. For this, we assessed patterns in floral phenotypic traits and network properties of plant species across elevations in Costa Rica. We also analysed whether plant species with generalized flower traits are ecological generalists and how morphological trait matching versus nectar traits affect interactions. We found marked variation in floral phenotypic traits and flower abundance of hummingbird-visited plant species across 10 sites along the elevation gradient. We did not find evidence for a relationship between flower morphology and nectar traits or between morphological and ecological generalization of plant species. Plant-hummingbird interaction frequency increased when the lengths of hummingbird bill and flower corolla were similar, indicating morphological matching, whereas nectar traits were unrelated to interactions. While nectar may play a difficult-to-detect secondary role within plant-hummingbird networks, our results reinforce the idea that morphological matching is an important factor in structuring ecological communities.

Genetic Signatures of Positive Selection in Human Populations Adapted to High Altitude in Papua New Guinea.

Papua New Guinea (PNG) hosts distinct environments mainly represented by the ecoregions of the Highlands and Lowlands that display increased altitude and a predominance of pathogens, respectively. Since its initial peopling approximately 50,000 years ago, inhabitants of these ecoregions might have differentially adapted to the environmental pressures exerted by each of them. However, the genetic basis of adaptation in populations from these areas remains understudied. Here, we investigated signals of positive selection in 62 highlanders and 43 lowlanders across 14 locations in the main island of PNG using whole-genome genotype data from the Oceanian Genome Variation Project (OGVP) and searched for signals of positive selection through population differentiation and haplotype-based selection scans. Additionally, we performed archaic ancestry estimation to detect selection signals in highlanders within introgressed regions of the genome. Among highland populations we identified candidate genes representing known biomarkers for mountain sickness (SAA4, SAA1, PRDX1, LDHA) as well as candidate genes of the Notch signaling pathway (PSEN1, NUMB, RBPJ, MAML3), a novel proposed pathway for high altitude adaptation in multiple organisms. We also identified candidate genes involved in oxidative stress, inflammation, and angiogenesis, processes inducible by hypoxia, as well as in components of the eye lens and the immune response. In contrast, candidate genes in the lowlands are mainly related to the immune response (HLA-DQB1, HLA-DQA2, TAAR6, TAAR9, TAAR8, RNASE4, RNASE6, ANG). Moreover, we find two candidate regions to be also enriched with archaic introgressed segments, suggesting that archaic admixture has played a role in the local adaptation of PNG populations.

Relation between air quality and asthma in high-altitude places, La Paz, Bolivia (3,600 m a.s.l.) / Relación entre la calidad del aire y el asma en habitantes de grandes altitudes, La Paz, Bolivia (3.600 m.s.n.m.).

Introduction. Asthma is a chronic disease affecting millions of people around the world. Air quality is a major factor in triggering asthma symptoms. Objective. To analyze air quality and asthma in high-altitude residents of La Paz, Bolivia. Materials and methods. In this analytical, descriptive, and retrospective study, we collected data from patients diagnosed with asthma at the Instituto Nacional del Tórax and the Instituto Boliviano de Biología de Altura. In addition, air quality monitoring of particulate matter was carried out at the stations of the Red de Monitoreo de la Calidad del Aire. Results. Women represented 56.9% of cases at the Instituto Nacional del Tórax and the Instituto Boliviano de Biología de Altura. In both institutions, the average age was 47 years and patients were overweight or obese. Increases in PM2.5 were recorded in autumn, winter and spring from 2014, 2016 to 2019 and 2015 in all four seasons. PM10 showed increases in autumn and winter from 2014 to 2020 within the established limits. We observed a positive and significant association between PM2,5 concentration and the spirometry parameters of forced vital capacity, peak expiratory flow, and "reversibility percentage" or "bronchodilator response percentage". The association of PM10 and forced vital capacity, forced expiratory volume in the first second, and peak expiratory flow, was also statistically significant. Conclusion. Asthma cases occur on average at 47 years of age in overweight or obese people. We observed a positive association between particles PM2,5 and PM10 with spirometric parameters, stronger with particulate matter PM2,5.

Introducción. El asma es una enfermedad crónica que afecta a millones de personas en todo el mundo. La calidad del aire es uno de los factores clave que puede desencadenar los síntomas del asma. Objetivo. Analizar la calidad del aire y su relación con el asma en habitantes de grandes altitudes en La Paz (Bolivia). Materiales y métodos. Se desarrolló un estudio analítico, descriptivo y retrospectivo. Se recolectaron datos de pacientes con diagnóstico de asma en el Instituto Nacional del Tórax y en el Instituto Boliviano de Biología de Altura. Además, se monitoreó la calidad del aire y su material particulado en las estaciones de la "Red de monitoreo de la calidad del aire". Resultados. El 56,9 % de los casos fueron mujeres del Instituto Nacional del Tórax y el 45,7 % del Instituto Boliviano de Biología de Altura. En ambas instituciones, la media de edad fue de 47 años y los pacientes presentaban sobrepeso u obesidad. Se registraron incrementos de material particulado fino (PM2,5) en otoño, invierno y primavera, en 2014, 2016-2019 y en las cuatro estaciones del 2015. El material particulado inhalable grueso (PM10) se incrementó en otoño e invierno del 2014 al 2020, dentro de los límites establecidos. Se observó una asociación positiva y significativa entre la concentración de material particulado PM2,5 y los parámetros espirométricos de capacidad vital forzada, flujo espiratorio máximo y el porcentaje de reversión. La relación de partículas PM10 y los parámetros espirométricos de capacidad vital forzada, volumen espiratorio máximo en el primer segundo y flujo espiratorio máximo, también fue estadísticamente significativa. Conclusión. Los casos de asma se presentaron en promedio a los 47 años y en personas con sobrepeso u obesidad. Se observó una asociación positiva entre el material particulado, PM2,5 y PM10, con los parámetros espirométricos, la cual fue más marcada con las partículas PM2,5.

Experimental warming and drying increase older carbon contributions to soil respiration in lowland tropical forests.

Tropical forests account for over 50% of the global terrestrial carbon sink, but climate change threatens to alter the carbon balance of these ecosystems. We show that warming and drying of tropical forest soils may increase soil carbon vulnerability, by increasing degradation of older carbon. In situ whole-profile heating by 4 °C and 50% throughfall exclusion each increased the average radiocarbon age of soil CO2 efflux by ~2-3 years, but the mechanisms underlying this shift differed. Warming accelerated decomposition of older carbon as increased CO2 emissions depleted newer carbon. Drying suppressed decomposition of newer carbon inputs and decreased soil CO2 emissions, thereby increasing contributions of older carbon to CO2 efflux. These findings imply that both warming and drying, by accelerating the loss of older soil carbon or reducing the incorporation of fresh carbon inputs, will exacerbate soil carbon losses and negatively impact carbon storage in tropical forests under climate change.

Moderate altitude as a risk factor for isolated congenital malformations. Results from a case-control multicenter-multiregional study.

BACKGROUND: Living in high-altitude regions has been associated with a higher prevalence of some birth defects. Moderate altitudes (1500-2500 m) have been associated with some congenital heart diseases and low birth weight. However, no studies have been conducted for other isolated congenital malformations. OBJECTIVES: To estimate the prevalence at birth of isolated congenital malformations in low and moderate altitudes and to determine if moderate altitudes are a risk factor, such as high altitudes, for isolated congenital malformations adjusted for other factors. METHODS: The study consisted of a case-control multicenter-multiregional study of 13 isolated congenital malformations. Cases included live births with isolated congenital malformations and controls at low (10-1433 m) and moderate altitudes (1511-2426 m) from a Mexican registry from January 1978 to December 2019. Prevalence per 10,000 (95% CI) per altitude group was estimated. We performed unadjusted and adjusted logistic regression models (adjusted for maternal age, parity, malformed relatives, socioeconomic level, and maternal diabetes) for each isolated congenital malformation. RESULTS: Hydrocephaly and microtia had a higher at-birth prevalence, and spina bifida, preauricular tag, and gastroschisis showed a lower at-birth prevalence in moderate altitudes. Moderate altitudes were a risk factor for hydrocephaly (aOR 1.39), microtia (aOR 1.60), cleft-lip-palate (aOR 1.27), and polydactyly (aOR 1.32) and a protective effect for spina bifida (aOR 0.87) compared with low altitudes. CONCLUSIONS: Our findings provide evidence that moderate altitudes as higher altitudes are an associated risk or protective factor to some isolated congenital malformations, suggesting a possible gradient effect.

Comparative analysis of leukemia and risk estimation in working age population between provinces of Ecuador.

Leukemia is associated with exposure to radiation, benzene derivatives, and pesticides. Previous research has documented an increase in work-related leukemia in the Latin American Andean region. To date, there are only few studies in Ecuador on the impact of oil exploitation on adjacent indigenous communities. Our study aims to show the impact of leukemia on the working-age population. For the calculation of morbidity and mortality rates, we used hospital discharge and death records from the National Institute of Statistics of Ecuador. These data were collected and adjusted to the corresponding province's population for further analysis. Large differences were observed between provinces in adjusted rates of leukemia mortality and morbidity in the working-age population. The variations in altitude among different areas in Ecuador give the provinces a distinct geographic identity. Likewise, the provinces with the highest morbidity and mortality rankings, such as Azuay, Loja, Imbabura, and Tungurahua, have an average altitude above 2000 meters. As a result, there are variations in the average temperature, exposure to solar and cosmic radiation, and mining and farming methods. The observed differences warrant the future collection of geolocation data for affected individuals. This could help to better understand how leukemia cases have demogrpahic hotspots in the country, identify possible risk factors associated with the disease in each region, and design more effective prevention and control strategies.

La leucemia es una enfermedad a consecuencia, además de factores genéticos, de la exposición a radiaciones, derivados del benceno y pesticidas. Investigaciones anteriores han documentado un aumento de la leucemia ocupacional en la región andina de América Latina. Hasta la fecha, existen sólo unos pocos estudios en Ecuador sobre el impacto de la explotación petrolera en las comunidades indígenas. Nuestro objetivo es mostrar el impacto de la leucemia en la población en edad de trabajar. Para el cálculo de las tasas de morbimortalidad se utilizaron los registros de altas hospitalarias y defunciones del Instituto Nacional de Estadística del Ecuador. Estos datos fueron recopilados y estimadas las tasas ajustadas. Se observaron grandes diferencias entre provincias en las tasas ajustadas de mortalidad y morbilidad por leucemia en la población en edad de trabajar. Asimismo, las provincias con mayor ranking de morbilidad y mortalidad, como Azuay, Loja, Imbabura y Tungurahua, coinciden en tener una altitud promedio superior a los 2000 metros. Hay provincias de baja altitud en la costa y provincias por encima de los 2000 metros en la sierra, lo que le da a las provincias del Ecuador una identidad geográfica distintiva. Como resultado, existen variaciones en la temperatura promedio, la exposición a la radiación solar y cósmica, y actividades de minería y agricultura. Las diferencias observadas, recomiendan la recopilación futura de datos de geolocalización de las personas afectadas. Esto podría ayudarnos a comprender mejor cómo se distribuyen los casos de leucemia, identificar posibles factores de riesgo asociados a la enfermedad en cada región y diseñar estrategias de prevención y control más efectivas.

Oxygen Saturation Curve Analysis in 2298 Hypoxia Awareness Training Tests of Military Aircrew Members in a Hypobaric Chamber.

We aim to provide reference values for military aircrews participating in hypoxia awareness training (HAT). We describe several parameters with potential biomedical interest based on selected segments and slopes of the changes in oxygen saturation (SatO2) during a standard HAT. A retrospective analysis of 2298 records of the SatO2 curve was performed, including 1526 military men aged 30.48 ± 6.47 years during HAT in a hypobaric chamber. HAT consisted of pre-oxygenation at 100% and an ascent to 7620 m, followed by O2 disconnection starting the phase of descent of SatO2 until reaching the time of useful consciousness (TUC), and finally reconnection to 100% O2 in the recovery phase. Using an ad hoc computational procedure, the time taken to reach several defined critical values was computed. These key parameters were the time until desaturation of 97% and 90% (hypoxia) after oxygen mask disconnection (D97/D90) and reconnection (R97/R90) phases, the time of desaturation (TUC-D97) and hypoxia (TUC-D90) during disconnection, the total time in desaturation (L97) or hypoxia (L90), and the slopes of SatO2 drop (SDSAT97 and SDSAT90) and recovery (SRSAT97). The mean of the quartiles according to TUC were compared by ANOVA. The correlations between the different parameters were studied using Pearson's test and the effect size was estimated with ω2. Potentially useful parameters for the HAT study were those with statistical significance (p < 0.05) and a large effect size. D97, D90, R97, and R90 showed significant differences with small effect sizes, while TUC-D97, TUC-D90, L97, L90, and SDSAT97 showed significant differences and large effect sizes. SDSAT97 correlated with TUC (R = 0.79), TUC-D97 (R = 0.81), and TUC-D90 (R = 0.81). In conclusion, several parameters of the SatO2 curve are useful for the study and monitoring of HAT. The SDSAT97 measured during the test can estimate the TUC and thus contribute to taking measures to characterize and protect the aircrew members.

Experimental evidence of climate change extinction risk in Neotropical montane epiphytes.

Climate change is conjectured to endanger tropical species, particularly in biodiverse montane regions, but accurate estimates of extinction risk are limited by a lack of empirical data demonstrating tropical species' sensitivity to climate. To fill this gap, studies could match high-quality distribution data with multi-year transplant experiments. Here, we conduct field surveys of epiphyte distributions on three mountains in Central America and perform reciprocal transplant experiments on one mountain across sites that varied in elevation, temperature and aridity. We find that most species are unable to survive outside of their narrow elevational distributions. Additionally, our findings suggest starkly different outcomes from temperature conditions expected by 2100 under different climate change scenarios. Under temperatures associated with low-emission scenarios, most tropical montane epiphyte species will survive, but under emission scenarios that are moderately high, 5-36% of our study species may go extinct and 10-55% of populations may be lost. Using a test of tropical species' climate tolerances from a large field experiment, paired with detailed species distribution data across multiple mountains, our work strengthens earlier conjecture about risks of wide-spread extinctions from climate change in tropical montane ecosystems.

How many animal-pollinated angiosperms are nectar-producing?

The diversity of plant-pollinator interactions is grounded in floral resources, with nectar considered one of the main floral rewards plants produce for pollinators. However, a global evaluation of the number of animal-pollinated nectar-producing angiosperms and their distribution world-wide remains elusive. We compiled a thorough database encompassing 7621 plant species from 322 families to estimate the number and proportion of nectar-producing angiosperms reliant on animal pollination. Through extensive sampling of plant communities, we also explored the interplay between nectar production, floral resource diversity, latitudinal and elevational gradients, contemporary climate, and environmental characteristics. Roughly 223 308 animal-pollinated angiosperms are nectar-producing, accounting for 74.4% of biotic-pollinated species. Global distribution patterns of nectar-producing plants reveal a distinct trend along latitudinal and altitudinal gradients, with increased proportions of plants producing nectar in high latitudes and altitudes. Conversely, tropical communities in warm and moist climates exhibit greater floral resource diversity and a lower proportion of nectar-producing plants. These findings suggest that ecological trends driven by climate have fostered the diversification of floral resources in warmer and less seasonal climates, reducing the proportion of solely nectar-producing plants. Our study provides a baseline for understanding plant-pollinator relationships, plant diversification, and the distribution of plant traits.

Taxonomic diversity and environmental tolerance of cultivable extremophilic bacteria from a high-altitude meltwater pond on Ojos del Salado (Chile).

Earth harbors unique environments where only microorganisms adapted to extreme conditions, known as extremophiles, can survive. This study focused on a high-altitude meltwater pond, located in the Puna de Atacama, Dry Andes. The extremophilic bacteria of this habitat must adapt to a range of extremities, including cold and dry climate, high UV radiation, high daily temperature fluctuations, low-nutrient availability, and negative water balance. This study aimed to explore the taxonomic diversity of cultivable extremophilic bacteria from sediment samples of a desiccated, high-altitude, meltwater pond using media with different organic matter contents and different incubation temperatures. Based on the 16S rRNA gene sequence analysis, the isolates were identified as members of the phyla Actinobacteria, Proteobacteria, and Firmicutes. The most abundant genera were Arthrobacter and Pseudoarthrobacter. The isolates had oligocarbophilic and psychrotrophic properties, suggesting that they have adapted to the extreme environmental parameters of their natural habitats. The results indicate a positive correlation between nutrient concentration and temperature tolerance.