GRIN Disorder is a rare neurodevelopmental disease caused by pathogenic variants in GRIN genes encoding subunits of the N-methyl-D-aspartate receptor (NMDAR). GRIN Disorder presents with a wide spectrum of neurological symptoms and currently lacks effective therapeutics and clinically accessible biomarkers to stratify disease severity or monitor treatment response. While NMDARs are well-studied in the central nervous system, they are also expressed in peripheral blood cells, including red blood cells (RBCs), where they modulate calcium signaling and cell function. Here we have used well-established in vivo and ex vivo methods to investigate hematological (primarily RBC-linked) phenotypes in transgenic mice carrying heterozygous Grin1 Y647S (Grin1Y647S/+) variant. We found that Grin1Y647S/+ mice had slightly increased RBC counts associated with increased erythropoiesis and normal erythropoietin levels. Functional assays revealed increased NMDAR-mediated calcium influx in Grin1Y647S/+ RBCs, accompanied by reduced blood viscosity under flow conditions. Our findings provide the first genetic evidence that NMDAR gain-of-function leads to systemic changes in RBC physiology, which may contribute to core phenotypes of NMDAR-related disorders. Results point to several RBC indices that reflect altered NMDAR function in Grin1Y647S/+ mice, providing foundational evidence for the development of peripheral blood biomarkers for patients with GRIN Disorder.

In lowland mammals that ascend to high elevation, hypoxia-induced changes in the pulmonary circulation can give rise to hypoxic pulmonary hypertension (HPH) and associated right-ventricle (RV) hypertrophy. Some mammals that are native to high elevation have evolved a means of attenuating HPH, demonstrating how environmental adaptation may sometimes counteract the effects of ancestral acclimatization responses. Here, we examine elevational variation in heart mass and measures of RV hypertrophy in four closely related species of leaf-eared mice (genus Phyllotis) that are broadly co-distributed across a steep elevational gradient on the Western slope of the Andes. There was a positive relationship overall between heart mass and elevation that reflected proportional changes in both the right and left ventricles. Thus, elevation-related increases in overall heart mass were not generally attributable to RV hypertrophy, suggesting that this group of predominantly highland species have evolved a means of avoiding HPH and/or attenuating the cardiac response to HPH. To gain insight into possible transcriptional mechanisms, we examined patterns of transcriptomic variation in the right ventricles of Phyllotis vaccarum from two geographically distinct highland populations (both from elevations >5000 m) that exhibit strikingly different levels of RV hypertrophy. Suppression of RV hypertrophy is associated with differential expression of key regulatory genes involved in striated muscle, immune processes, and the inflammatory response. Analysis of co-expression modules identified a promising set of candidate genes for mediating the development of RV hypertrophy at extremely high elevations.

Breathing and the hypoxic ventilatory response are vital determinants of gas exchange and metabolism in hypoxia. High-altitude natives are valuable models for elucidating how plasticity and evolutionary adaptation can shape the control of breathing in chronic hypoxia. Here, we review studies on this issue in deer mice, a species found from sea level to over 4300 m elevation. Distinct populations from high and low altitudes have been bred in captivity and compared in common conditions of normoxia or hypoxia. Low-altitude populations exhibit ventilatory acclimatization to hypoxia (VAH), in which chronic hypoxia enhances total ventilation and helps offset declines in arterial O2 pressure. In contrast, high-altitude populations do not express VAH, but instead exhibit a fixed increase in total ventilation in hypoxia and a deeper more effective breathing pattern than lowlanders. Studies of F2 inter-population hybrids suggested that these evolved changes in breathing in highlanders could be largely attributed to sequence variants in two genes. Specifically, the more effective breathing pattern of highlanders was associated with genetic variation in α-globin, whereas the lack of VAH was associated with variation in the hypoxia-inducible factor 2α (HIF-2α) gene Epas1. However, in contrast to the lack of plasticity in highlanders during adulthood alone, life-long hypoxia exposure throughout development and adulthood has a strong effect on the HVR, further augmenting total ventilation and tidal volume. Altogether, these findings in deer mice suggest that the control of breathing in high-altitude natives is shaped by the integration of their unique genotype and developmental environment, improving resilience to harsh and hypoxic environments.

High-altitude hypoxia constrains tissue O2 supply, but several high-altitude populations have evolved adaptations to overcome this challenge. Evolved increases in haemoglobin-O2 (Hb-O2) affinity are pervasive across high-altitude taxa, but the influence of such increases on aerobic capacity in hypoxia remains contentious. The influence of Hb-O2 affinity could depend on the capacity to extract O2 from the blood, but this possibility is poorly understood. We examined this issue in deer mice (Peromyscus maniculatus), which are found from sea level to >4300 m elevation in the Rocky Mountains. Mice from populations native to high and low altitudes were born and raised in captivity. Low-altitude mice were acclimated to warm (25°C) normoxia and high-altitude mice were acclimated to cold (5°C) hypoxia (∼12 kPa O2), creating two groups with distinct capacities for O2 transport. Aerobic capacity for thermogenesis was measured in hypoxia after each of three pharmacological treatments: saline (control), efaproxiral (decreases Hb-O2 affinity) and cyanate (increases Hb-O2 affinity). High-altitude mice had greater aerobic capacity in hypoxia, in association with higher arterial O2 saturation ( S a O 2 ${{S}_{{\mathrm{a}}{{{\mathrm{O}}}_2}}}$ ) and lower P50 (O2 pressure at 50% Hb saturation) in most conditions. The P50 at which aerobic capacity was greatest was lower in high-altitude mice than in low-altitude mice. High-altitude mice also had greater uncoupling protein 1 (UCP-1) content in brown adipose tissue and greater cytochrome oxidase activity in gastrocnemius muscle. These results suggest that optimal Hb-O2 affinity and S a O 2 ${{S}_{{\mathrm{a}}{{{\mathrm{O}}}_2}}}$ are greater in high-altitude mice, in association with a greater capacity to extract and consume O2 in thermogenic tissues. KEY POINTS: Evolved increases in haemoglobin-O2 affinity are pervasive across high-altitude taxa, but the influence of such increases on aerobic capacity in hypoxia remains contentious. We examined whether the influence of haemoglobin-O2 affinity on aerobic capacity for thermogenesis is altered in high-altitude deer mice. Using pharmacological treatments to manipulate haemoglobin-O2 affinity, we found that aerobic capacity in hypoxia was greatest at higher affinities in high-altitude mice than in low-altitude mice. Skeletal muscle and brown adipose tissue had more oxidative and thermogenic phenotypes in high-altitude mice. These results suggest that the optimal haemoglobin-O2 affinity in hypoxia is greater in high-altitude deer mice, potentially resulting from a greater capacity to extract and consume O2 in active tissues.

The activating signal co-integrator 1 complex subunit 3 (ASCC3), a multifunctional protein, has been implicated as a prognostic marker in several types of cancer. However, mechanisms underlying its prognostic value are not fully understood. Here, we report that ASCC3 promotes sensitivity to chemotherapeutic drugs that induce replication stress, such as 5-fluorouracil, cisplatin, and hydroxyurea, in colorectal cancer (CRC) cells, likely in a cancer type dependent manner. Increased chemoresistance resulting from ASCC3 loss is not due to reduced genomic instability as evidenced by enhanced accumulation of DNA damage and micronuclei following exposure to these drugs. RNA-seq analysis reveals that ASCC3 stimulates the expression of gene sets associated with mTORC1 signaling, glycolysis, and protein folding pathways in CRC cells. While promoting the serine biosynthesis pathway, we demonstrate, through extracellular flux assays and stable isotopes tracer analysis, that ASCC3 reprograms energy metabolism, favoring glycolysis over oxidative phosphorylation. Furthermore, we find that ASCC3 is required for PERK production upon ER stress. Impaired PERK production is associated with reduced levels of CHOP and caspase 3 following treatment with 5-fluorouracil, indicating that ASCC3 promotes PERK production to enhance cell death upon chemotherapy. Collectively, our work reveals an unexpected role of ASCC3 in connecting replication stress to both metabolic reprogramming and PERK-mediated signaling in CRC cells.

The cold and hypoxic conditions at high altitude can challenge the ability of small endotherms to meet the high energy demands of locomotion and thermoregulation. We examined how high-altitude natives overcome this challenge through plastic and/or evolved improvements in locomotory performance. Deer mice (Peromyscus maniculatus) native to high and low altitude were born and raised in captivity, then acclimated to warm normoxia or cold hypoxia as adults. Running endurance was then measured in both warm normoxia and cold hypoxia across groups. Among mice acclimated to warm normoxia, endurance was greater in highlanders compared with lowlanders. Acclimation to cold hypoxia increased endurance in lowlanders, partially approaching values in highlanders. Body temperature declined while running in cold hypoxia in lowlanders, but highlanders were better at avoiding such declines. Our data suggest that evolved changes in thermoregulatory ability and muscle phenotype combine to improve locomotory performance in cold hypoxia in high-altitude deer mice.

Small mammals at high altitude face the challenge of maintaining high rates of thermogenesis to cope with cold temperatures despite low O2 availability to fuel aerobic metabolism. We examined how adjustments in mitochondrial physiology across skeletal muscles might help overcome this challenge in deer mice (Peromyscus maniculatus) native to high altitude. Mice from high- and low-altitude populations were born and raised in captivity, and adults were acclimated to warm normoxia or cold (5°C) hypoxia (∼12 kPa O2 for 6-8 weeks) in a full-factorial design. Mitochondrial respiration and reactive oxygen species (ROS) emission were measured in the diaphragm, vastus medialis, vastus lateralis and gluteus maximus, complemented by measurements of mitochondrial abundance by transmission electron microscopy. In general, acclimation to cold hypoxia increased mitochondrial volume density (in some cases due to a preferential enrichment of subsarcolemmal mitochondria), mitochondrial respiration and/or complex IV activity, and also reduced ROS emission (measured both ex vivo and in vivo) in multiple muscles. Overlaid upon these effects of acclimation, high-altitude mice exhibited greater mitochondrial respiratory capacity than low-altitude mice in the diaphragm, and greater respiratory capacity of complex IV in all muscles except the gluteus maximus. High-altitude mice also exhibited lower ROS emission or more pronounced reductions in ROS emission in some conditions. These findings suggest that plastic and evolved changes in mitochondrial physiology can help improve energy supply and mitigate oxidative stress in small mammals at high altitude.

Andean leaf-eared mice (Phyllotis vaccarum) live at the highest elevations of any mammal, and they also have the broadest elevational range, from sea level to mountain summits of >6700 meters. Highland populations have evolved an enhanced thermogenic capacity in hypoxia relative to lowland conspecifics, and this improved physiological performance is associated with an increased mitochondrial respiratory capacity in skeletal muscle. Population genomic analyses identified mechanisms of hypoxia adaptation and revealed an unanticipated dimension of environmental adaptation in P. vaccarum because selection on biotransformation pathways suggests an evolved capacity to metabolize plant-derived dietary toxins. The world's highest-dwelling mammal has adapted to habitats at both the low- and high-elevation limits of its range, and much of the elevation-related selection relates to previously unappreciated aspects of feeding ecology.

Hypoxia at high altitude can constrain aerobic metabolism and elicit physiological responses that are detrimental to health and fitness. Responses of the sympathoadrenal system are vital for coping with acute hypoxia but can become maladaptive with prolonged activation in chronic hypoxia. We examined how adrenal function is altered in high-altitude populations of deer mice (Peromyscus maniculatus), which have evolved to overcome chronic hypoxia in their native environment. High- and low-altitude populations were each born and raised in common laboratory conditions and then acclimated to normoxia or chronic hypoxia during adulthood. High-altitude mice exhibited lower plasma epinephrine concentrations than low-altitude mice in both normoxia and hypoxia. Primary cultures of chromaffin cells were used to examine the cellular mechanisms underlying differences in epinephrine secretion from the adrenal medulla. Chromaffin cells from high-altitude mice did not mount a diminished Ca2+ response to nicotinic stimulation, but cellular catecholamine stores were much lower in high-altitude mice than in low-altitude mice. Histological analyses of the adrenal gland showed that high-altitude mice did not have smaller adrenal medullae. Therefore, reductions in chromaffin cell catecholamine stores were the primary mechanism for lower secretion rates and circulating concentrations of catecholamines in high-altitude mice, which may help avoid sympathoadrenal overactivity in chronic hypoxia. Further exploratory analysis found that high-altitude mice have a larger adrenal cortex and higher plasma concentrations of corticosterone, which could reflect changes in stress responsiveness or metabolic regulation. Therefore, multiple evolved changes in the physiology of the adrenal gland may contribute to high-altitude adaptation in deer mice. NEW & NOTEWORTHY Prolonged activation of the sympathoadrenal system can become maladaptive in chronic hypoxia, but few previous studies have examined adrenal function in high-altitude natives. Comparing high-altitude versus low-altitude populations of mice, we show that high-altitude mice synthesize and store fewer catecholamines in adrenal chromaffin cells and thus have lower secretion rates and circulating concentrations of catecholamines in hypoxia.

The cold and hypoxic conditions at high altitude place high demands on the cardiovascular system to sustain circulatory O2 transport. High-altitude natives have evolved to overcome cold hypoxia, but the cardiovascular mechanisms involved remain poorly understood in most taxa. Here, we investigated the evolved changes in reflex control of cardiovascular function in deer mice (Peromyscus maniculatus) native to high altitude. High- and low-altitude populations of deer mice were each bred in captivity and then chronically acclimated to warm normoxia (25°C, ∼20 kPa O2) or cold hypoxia (5°C, 12 kPa O2) for 6-8 weeks. Cardiovascular function was measured in vivo using physiological telemeters, complemented by wire myography to examine vascular function ex vivo. High-altitude mice acclimated to cold hypoxia exhibited greater heart rates and were better able to maintain blood pressure in moderate and severe hypoxia, in association with less pronounced depression of metabolism and body temperature. High-altitude mice also exhibited greater baroreflex sensitivity than low-altitude mice across acclimation environments, as reflected by greater changes in heart rate and smaller changes in arterial blood pressure during pharmacological manipulations. Mesenteric arteries from each population exhibited similar ex vivo smooth muscle contractions in response to phenylephrine (α1-adrenoceptor agonist), and similar endothelium-dependent relaxation in response to acetylcholine, suggesting that evolved changes in the baroreflex arise from adjustments in autonomic control of the heart and/or other resistance vessels. These evolved changes in cardiovascular function and reflex control may be valuable for supporting high metabolic rates in the cold and hypoxic environment at high altitude.

The impacts of heat exposure on mitochondrial physiology are poorly understood in most mammals. We examined the thermal effects on muscle mitochondrial function in deer mice (Peromyscus maniculatus), a species in which running endurance is impaired when heat exposure increases body temperature beyond 40 °C. Mitochondrial physiology was examined at 37, 40, and 42 °C using both permeabilized fibres and isolated mitochondria from the gastrocnemius muscle. Hot temperatures increased leak respiration, reduced the coupling efficiency of oxidative phosphorylation, and increased reactive oxygen species (ROS) emission. These results suggest that heat exposure reduces mitochondrial efficiency, which could contribute to impairments in running performance, and may also induce oxidative stress. Thermal effects on mitochondrial function may thus represent a potential vulnerability during heat exposure in mammals.

The overall goal of this work was to assess the ability of Natural Killer cells to kill cultures of patient-derived glioblastoma cells. Herein we report impressive levels of NK-92 mediated killing of various patient-derived glioblastoma cultures observed at ET (effector: target) ratios of 5:1 and 1:1. This enabled direct comparison of the degree of glioblastoma cell loss across a broader range of glioblastoma cultures. Importantly, even at high ET ratios of 5:1, there are always subpopulations of glioblastoma cells that prove very challenging to kill that evade the NK-92 cells. Of value in this study has been the application of ECIS (Electric Cell–Substrate Impedance Sensing) biosensor technology to monitor the glioblastoma cells in real-time, enabling temporal assessment of the NK-92 cells. ECIS has been powerful in revealing that at higher ET ratios, the glioblastoma cells are acutely sensitive to the NK-92 cells, and the observed glioblastoma cell death is supported by the high-content imaging data. Moreover, long-term ECIS experiments reveal that the surviving glioblastoma cells were then able to grow and reseed the culture, which was evident 300–500 h after the addition of the NK-92 cells. This was observed for multiple glioblastoma lines. In addition, our imaging provides evidence that some NK-92 cells appear to be compromised early, which would be consistent with potent evasive mechanisms by the glioblastoma tumour cells. This research strongly highlights the potential for NK-92 cells to kill glioblastoma tumour cells and provides a basis to identify the mechanism utilised by the surviving glioblastoma cells that we now need to target to achieve maximal cytolysis of the resistant glioblastoma cells. It is survival of the highly resistant glioblastoma clones that results in tumour relapse.

High elevation imposes unrelenting and unavoidable hypoxia on species inhabiting these environments, providing an excellent natural setting for studying convergent or divergent evolution. By integrating measures of phenotypic variation, gene regulation, and functional performance, our study demonstrates that recent colonizers of high-elevation environments exhibit fundamentally different cardiovascular changes compared to long-term natives of these environments. Through the studying of heart morphological phenotypes, we showed that recent colonizers exhibit signs of cardiac hypertrophy, reflected by increased relative heart mass (heart mass/body mass) and cardiomyocyte size compared to their low-elevation relatives. In contrast, native species show no signs of cardiac hypertrophy and instead have 3-fold higher capillary densities than the colonizers, a change that likely enhances tissue oxygen diffusing capacity in the former. Using phylogenetic principal component analysis to quantify multivariate trait divergence, we show that native species are similar in cardiovascular phenotype and underlying gene expression, but differ appreciably from recent colonizers. We further demonstrate, using a functional assay, that differential expression of two genes (IRS2 and AKT1) in a conserved regulatory pathway mediates cardiomyocyte hypertrophy, which could explain the observed variation in cardiomyocyte size between native species and recent colonizers. This regulatory basis of variation in cardiac phenotype involves the differential expression of genes in a cardiomyocyte hypertrophy pathway that is conserved across birds, humans and other mammals. Collectively, our study highlights that evolutionary history is a critical determinant of cardiovascular variation in high-elevation environments.

High-altitude life poses physiological challenges to all animals due to decreased environmental oxygen (O2) availability (hypoxia) and cold. Supporting high metabolic rates and body temperatures with limited O2 is challenging. Many birds, however, thrive at high altitudes. The O2-transport cascade describes the pathway involved in moving O2 from the environment to the tissues encompassing: (i) ventilation, (ii) pulmonary O2 diffusion, (iii) circulation, (iv) tissue O2 diffusion, and (v) mitochondrial O2 use for ATP production. Shared avian traits such as rigid lungs with cross-current gas exchange and unidirectional airflow aid in O2 acquisition and transport in all birds. Many high-altitude birds, however, have evolved enhancements to some or all steps in the cascade. In this review, we summarize the current literature on gas exchange and O2 transport in high-altitude birds, providing an overview of the O2-transport cascade that principally draws on the literature from high-altitude waterfowl, the most well-studied group of high-altitude birds. We close by discussing two important avenues for future research: distinguishing between the influences of plasticity and evolution and investigating whether the morphological and physiological differences discussed contribute to enhanced locomotor or thermogenic performance, a potential critical link to fitness.This article is part of the theme issue 'The biology of the avian respiratory system'.

Fieldwork provides opportunities for students to develop employability-enhancing transferable skills as well as technical, discipline-specific skills and disciplinary knowledge. However, the extent to which staff purposely plan transferable skills outcomes of field courses, and, therefore, whether they are communicated to students is unknown. We investigated whether staff intentionally plan transferable skills development opportunities into fieldwork by interviewing academic staff responsible for planning and leading residential field courses at a UK university. We also conducted a thematic analysis of associated module specifications and teaching materials to understand whether transferable skills were signposted to colleagues and students. Our findings show that although most staff recognise that their field courses help students to develop transferable skills, staff awareness of skills and professional development outcomes is narrowly focused on technical skills and discipline-related careers. Furthermore, those transferable skills outcomes that staff are aware of are not fully translated into module specifications and infrequently signposted to students via teaching materials. These findings suggest that transferable skills form a hidden curriculum of fieldwork. To maximise the employability benefits of fieldwork, we recommend that all skills should be signposted to students both during field course teaching and also via the associated teaching materials.

Hypoxia and cold temperatures create unique physiological challenges for high-altitude organisms that can vary depending on lifestyle. While nearly all studies of air-breathing animals at high altitude are from terrestrial species, species that breath-hold dive underwater at high altitude encounter a very different set of selective pressures influencing their phenotype. The goal of this publication is to highlight the changes in O2 transport and utilization in high-altitude diving birds relative to divers at sea level, and the extent to which these changes are qualitatively distinct from phenotypic changes in non-diving species at high altitude. For example, while high capacities for sustained O2 transport may be required for sustained flight and thermogenesis (particularly in small endotherms), high-altitude breath-hold diving is a form of intense exercise uniquely defined by transient and sometimes severe O2 depletion (hypoxemia) and CO2 accumulation (hypercapnia), interspersed by recovery between dives when O2 stores must be rapidly replenished despite the hypoxic environment at high altitude. Given this, diving behavior may preclude or constrain the physiology of divers, such that high-altitude divers are predicted to exhibit qualitatively distinct phenotypic changes compared to non-divers, as each likely experience unique signals for phenotypic plasticity and selective pressures driving their evolution. Here, we reanalyze and synthesize new and recent findings describing O2 transport for two high-altitude breath-hold divers in the Andes of South America, the ruddy duck (Oxyura jamaicensis) and the torrent duck (Merganetta armata). Analysis across the O2-transport cascade including (1) ventilation, (2) pulmonary O2 diffusion, (3) circulatory O2 delivery, (4) tissue O2 diffusion, and (5) tissue O2 utilization reveals that different routes to functional adaptation have emerged between diving and non-diving birds in the high Andes. While ruddy ducks and torrent ducks differed in numerous ways, we found that these two high-altitude divers had generally much higher blood-O2 carrying capacity relative to non-divers. Furthermore, unlike non-diving high-altitude waterfowl, these highaltitude divers did not increase Hb-O2 affinity at high altitude, because Hb-O2 affinity was already high in the low-altitude diving ancestor. Due to these factors, these divers always had higher arterial O2 content (CaO2) than non-divers, but unlike the non-divers, there was never any difference in CaO2 between high- and low-altitude populations among the divers. Finally, high-altitude divers exhibited greater magnitudes of body temperature (Tb) suppression during hypoxia than their corresponding low-altitude populations, whereas hypoxic Tb suppression was similar between high- and lowaltitude taxa among non-divers. In fact, the ruddy duck had the lowest Tb of all species under extreme hypoxia. Such changes may be beneficial by reducing the metabolic cost of thermogenesis during dives in cold alpine waters. Further insight into the unique physiology of high-altitude divers would benefit from future study of cardiorespiratory control and pulmonary function during the recovery phase between dives, as well as mitochondrial bioenergetics, reactive oxygen species (ROS) production, and antioxidant defense.

The programme leader is crucial to the success of a higher education provider's educational portfolio. However, programme leader development is under-researched and is too often conceptualised in a negative way, as the solution to a problem. Here we adopt a positive approach by undertaking an Appreciative Inquiry with programme leaders to understand their development needs. Our work identifies domains of reward and responsibility intrinsic to the programme leader role. Mapping these against a Competence-Based Higher Education Framework, we propose a holistic model for the academic development of programme leaders. We encourage others to adapt this model to their institutional contexts.

Most previous studies of muscle plasticity and adaptation in high-altitude environments have focused on a very limited number of skeletal muscles. Comparing high-altitude versus low-altitude populations of deer mice, we show that a large number of muscles involved in shivering, locomotion, body posture, ventilation, and mastication exhibit greater mitochondrial enzyme activities in the high-altitude population. Therefore, evolved increases in mitochondrial oxidative capacity across skeletal muscles contribute to high-altitude adaptation.