'How to adapt forests?'-Exploring the role of leaf trait diversity for long-term forest biomass under new climate normals.

Forests, critical components of global ecosystems, face unprecedented challenges due to climate change. This study investigates the influence of functional diversity-as a component of biodiversity-to enhance long-term biomass of European forests in the context of changing climatic conditions. Using the next-generation flexible trait-based vegetation model, LPJmL-FIT, we explored the impact of functional diversity on long-term forest biomass under three different climate change scenarios (video abstract: https://www.pik-potsdam.de/~billing/video/2023/video_abstract_billing_et_al_LPJmLFIT.mp4). Four model set-ups were tested with varying degrees of functional diversity and best-suited functional traits. Our results show that functional diversity positively influences long-term forest biomass, particularly when climate warming is low (RCP2.6). Under these conditions, high-diversity simulations led to an approximately 18.2% increase in biomass compared to low-diversity experiments. However, as climate change intensity increased, the benefits of functional diversity diminished (RCP8.5). A Bayesian multilevel analysis revealed that both full leaf trait diversity and diversity of plant functional types contributed significantly to biomass enhancement under low warming scenarios in our model simulations. Under strong climate change, the presence of a mixture of different functional groups (e.g. summergreen and evergreen broad-leaved trees) was found more beneficial than the diversity of leaf traits within a functional group (e.g. broad-leaved summergreen trees). Ultimately, this research challenges the notion that planting only the most productive and climate-suited trees guarantees the highest future biomass and carbon sequestration. We underscore the importance of high functional diversity and the potential benefits of fostering a mixture of tree functional types to enhance long-term forest biomass in the face of climate change.

Cervical vertebral body replacement using a modern in situ expandable and angulable corpectomy cage system: early clinical and radiological outcome.

PURPOSE: Vertebral body replacement (VBR) cages are commonly implanted to reconstruct the cervical vertebrae in cases of tumour, trauma, spondylodiscitis, and degeneration. Expandable cages have been widely used for this purpose; however, the lacking congruence at the implant-bone interface and consequent implant displacement were considered as a serious drawback of such systems. Aim of this study is to evaluate the early clinical and radiological outcome of a modern in situ not only expandable but also angulable cervical corpectomy cage system. METHODS: A total of 42 patients who underwent a single or multilevel cervical VBR procedure were included and retrospectively evaluated in this single-centre case series. The neurological status was assessed using American Spinal Injury Association (ASIA) score. Complications were categorized into surgical (including implant-associated) and general medical. Radiographic parameters included regional angulation, segmental height, and coronal alignment. RESULTS: Mean age was 59.5 ± 20.6 years. The recorded ASIA score improved postoperatively by 10 points (p  0.0001). Surgical including implant-associated complication rates were 19.05%. Radiographic evaluation showed a height gain of 11.2 mm (p < 0.0001), lordotic correction of 7° (p < 0.0001), and coronal alignment of 3° (p < 0.0001). At the last follow-up, loss of angulation correction of 1.9° (p  0.0002), subsidence of 1.92 mm (p  0.0006), and fusion rates of 68.42% were observed. CONCLUSIONS: The use of an in situ angulable and expandable cage system in cervical VBR seems to offer better results compared to conventional static or expandable cages regarding segmental height gain, lordotic correction, and clinical improvement as well as low complication and revision rates. Significant height gain in multilevel surgeries is associated with higher rates of implant-associated complications.

Drivers of phenological changes in southern Europe.

The life cycle of plants is largely determined by climate, which renders phenological responses to climate change a highly suitable bioindicator of climate change. Yet, it remains unclear, which are the key drivers of phenological patterns at certain life stages. Furthermore, the varying responses of species belonging to different plant functional types are not fully understood. In this study, the role of temperature and precipitation as environmental drivers of phenological changes in southern Europe is assessed. The trends of the phenophases leaf unfolding, flowering, fruiting, and senescence are quantified, and the corresponding main environmental drivers are identified. A clear trend towards an earlier onset of leaf unfolding, flowering, and fruiting is detected, while there is no clear pattern for senescence. In general, the advancement of leaf unfolding, flowering and fruiting is smaller for deciduous broadleaf trees in comparison to deciduous shrubs and crops. Many broadleaf trees are photoperiod-sensitive; therefore, their comparatively small phenological advancements are likely the effect of photoperiod counterbalancing the impact of increasing temperatures. While temperature is identified as the main driver of phenological changes, precipitation also plays a crucial role in determining the onset of leaf unfolding and flowering. Phenological phases advance under dry conditions, which can be linked to the lack of transpirational cooling leading to rising temperatures, which subsequently accelerate plant growth.

Blood Pressure Normalization-Independent Cardioprotective Effects of Endogenous, Physical Activity-Induced αCGRP (α Calcitonin Gene-Related Peptide) in Chronically Hypertensive Mice.

RATIONALE: αCGRP (α calcitonin gene-related peptide), one of the strongest vasodilators, is cardioprotective in hypertension by reducing the elevated blood pressure. OBJECTIVE: However, we hypothesize that endogenous, physical activity-induced αCGRP has blood pressure-independent cardioprotective effects in chronic hypertension. METHODS AND RESULTS: Chronically hypertensive (one-kidney-one-clip surgery) wild-type and αCGRP-/- sedentary or voluntary wheel running mice were treated with vehicle, αCGRP, or the αCGRP receptor antagonist CGRP8-37. Cardiac function and myocardial phenotype were evaluated echocardiographically and by molecular, cellular, and histological analysis, respectively. Blood pressure was similar among all hypertensive experimental groups. Endogenous αCGRP limited pathological remodeling and heart failure in sedentary, chronically hypertensive wild-type mice. In these mice, voluntary wheel running significantly improved myocardial phenotype and function, which was abolished by CGRP8-37 treatment. In αCGRP-/- mice, αCGRP treatment, in contrast to voluntary wheel running, improved myocardial phenotype and function. Specific inhibition of proliferation and myofibroblast differentiation of primary, murine cardiac fibroblasts by αCGRP suggests involvement of these cells in αCGRP-dependent blunting of pathological cardiac remodeling. CONCLUSIONS: Endogenous, physical activity-induced αCGRP has blood pressure-independent cardioprotective effects and is crucial for maintaining cardiac function in chronic hypertension. Consequently, inhibiting endogenous αCGRP signaling, as currently approved for migraine prophylaxis, could endanger patients with hypertension.

Expression of Hypoxia-Inducible Factor 1α (HIF-1α) and Genes of Related Pathways in Altered Gravity.

Immune system deterioration in space represents a major risk, which has to be mitigated for exploration-class missions into the solar system. Altered gravitational forces have been shown to regulate adaptation processes in cells of the immune system, which are important for appropriate risk management, monitoring and development of countermeasures. T lymphocytes and cells of the monocyte-macrophage system are highly migratory cell types that frequently encounter a wide range of oxygen tensions in human tissues and in hypoxic areas, even under homeostatic conditions. Hypoxia-inducible factor 1 and 2 (HIF's) might have an important role in activation of T cells and cells of the monocyte-macrophages system. Thus, we investigated the regulation of HIF-dependent and, therefore, hypoxia-signaling systems in both cell types in altered gravity and performed transcript and protein analysis from parabolic flight and suborbital ballistic rocket experiments. We found that HIF-1α and HIF-1-dependent transcripts were differently regulated in altered gravity, whereas HIF-1α-dependent gene expression adapted after 5 min microgravity. Inter-platform comparisons identified PDK1 as highly responsive to gravitational changes in human U937 myelomonocytic cells and in Jurkat T cells. We suggest HIF-1 as a potential pharmacological target for counteracting immune system deterioration during space flight.

A 3'-UTR mutation creates a microRNA target site in the GFPT1 gene of patients with congenital myasthenic syndrome.

Mutations in the gene encoding glutamine-fructose-6-phosphate transaminase 1 (GFPT1) cause the neuromuscular disorder limb-girdle congenital myasthenic syndrome (LG-CMS). One recurrent GFPT1 mutation detected in LG-CMS patients is a c.*22C>A transversion in the 3'-untranslated region (UTR). Because this variant does not alter the GFPT1 open reading frame, its pathogenic relevance has not yet been established. We found that GFPT1 protein levels were reduced in myoblast cells of the patients carrying this variant. In silico algorithms predicted that the mutation creates a microRNA target site for miR-206*. Investigation of the expression of this so far unrecognized microRNA confirmed that miR-206* (like its counterpart miR-206) is abundant in skeletal muscle. MiR-206* efficiently reduced the expression of reporter constructs containing the mutated 3'-UTR while no such effect was observed with reporter constructs containing the wild-type 3'-UTR or when a specific anti-miR-206* inhibitor was added. Moreover, anti-miR-206* inhibitor treatment substantially rescued GFPT1 expression levels in patient-derived myoblasts. Our data demonstrate that the c.*22C>A mutation in the GFPT1 gene leads to illegitimate binding of microRNA resulting in reduced protein expression. We confirm that c.*22C>A is a causative mutation and suggest that formation of microRNA target sites might be a relevant pathomechanism in Mendelian disorders. Variants in the 3'-UTRs should be considered in genetic diagnostic procedures.

Aquaporin 1 controls the functional phenotype of pulmonary smooth muscle cells in hypoxia-induced pulmonary hypertension.

Vascular remodelling in hypoxia-induced pulmonary hypertension (PH) is driven by excessive proliferation and migration of endothelial and smooth muscle cells. The expression of aquaporin 1 (AQP1), an integral membrane water channel protein involved in the control of these processes, is tightly regulated by oxygen levels. The role of AQP1 in the pathogenesis of PH, however, has not been directly addressed so far. This study was designed to characterize expression and function of AQP1 in pulmonary vascular cells from human arteries and in the mouse model of hypoxia-induced PH. Exposure of human pulmonary vascular cells to hypoxia significantly induced the expression of AQP1. Similarly, levels of AQP1 were found to be upregulated in lungs of mice with hypoxia-induced PH. The functional role of AQP1 was further tested in human pulmonary artery smooth muscle cells demonstrating that depletion of AQP1 reduced proliferation, the migratory potential, and, conversely, increased apoptosis of these cells. This effect was associated with higher expression of the tumour suppressor gene p53. Using the mouse model of hypoxia-induced PH, application of GapmeR inhibitors targeting AQP1 abated the hypoxia-induced upregulation of AQP1 and, of note, reversed PH by decreasing both right ventricular pressure and hypertrophy back to the levels of control mice. Our data suggest an important functional role of AQP1 in the pathobiology of hypoxia-induced PH. These results offer novel insights in our pathogenetic understanding of the disease and propose AQP1 as potential therapeutic in vivo target.

Differential expression and localization of Ankrd2 isoforms in human skeletal and cardiac muscles.

Four human Ankrd2 transcripts, reported in the Ensembl database, code for distinct protein isoforms (360, 333, 327 and 300 aa), and so far, their existence, specific expression and localization patterns have not been studied in detail. Ankrd2 is preferentially expressed in the slow fibers of skeletal muscle. It is found in both the nuclei and the cytoplasm of skeletal muscle cells, and its localization is prone to change during differentiation and upon stress. Ankrd2 has also been detected in the heart, in ventricular cardiomyocytes and in the intercalated disks (ICDs). The main objective of this study was to distinguish between the Ankrd2 isoforms and to determine the contribution of each one to the general profile of Ankrd2 expression in striated muscles. We demonstrated that the known expression and localization pattern of Ankrd2 in striated muscle can be attributed to the isoform of 333 aa which is dominant in both tissues, while the designated cardiac and canonical isoform of 360 aa was less expressed in both tissues. The 360 aa isoform has a distinct nuclear localization in human skeletal muscle, as well as in primary myoblasts and myotubes. In contrast to the isoform of 333 aa, it was not preferentially expressed in slow fibers and not localized to the ICDs of human cardiomyocytes. Regulation of the expression of both isoforms is achieved at the transcriptional level. Our results set the stage for investigation of the specific functions and interactions of the Ankrd2 isoforms in healthy and diseased human striated muscles.

Alveolar macrophages are essential for protection from respiratory failure and associated morbidity following influenza virus infection.

Alveolar macrophages (AM) are critical for defense against bacterial and fungal infections. However, a definitive role of AM in viral infections remains unclear. We here report that AM play a key role in survival to influenza and vaccinia virus infection by maintaining lung function and thereby protecting from asphyxiation. Absence of AM in GM-CSF-deficient (Csf2-/-) mice or selective AM depletion in wild-type mice resulted in impaired gas exchange and fatal hypoxia associated with severe morbidity to influenza virus infection, while viral clearance was affected moderately. Virus-induced morbidity was far more severe in Csf2-/- mice lacking AM, as compared to Batf3-deficient mice lacking CD8α+ and CD103+ DCs. Csf2-/- mice showed intact anti-viral CD8+ T cell responses despite slightly impaired CD103+ DC development. Importantly, selective reconstitution of AM development in Csf2rb-/- mice by neonatal transfer of wild-type AM progenitors prevented severe morbidity and mortality, demonstrating that absence of AM alone is responsible for disease severity in mice lacking GM-CSF or its receptor. In addition, CD11c-Cre/Ppargfl/fl mice with a defect in AM but normal adaptive immunity showed increased morbidity and lung failure to influenza virus. Taken together, our results suggest a superior role of AM compared to CD103+ DCs in protection from acute influenza and vaccinia virus infection-induced morbidity and mortality.

Nogo-A is a negative regulator of CNS angiogenesis.

Nogo-A is an important axonal growth inhibitor in the adult and developing CNS. In vitro, Nogo-A has been shown to inhibit migration and cell spreading of neuronal and nonneuronal cell types. Here, we studied in vivo and in vitro effects of Nogo-A on vascular endothelial cells during angiogenesis of the early postnatal brain and retina in which Nogo-A is expressed by many types of neurons. Genetic ablation or virus-mediated knock down of Nogo-A or neutralization of Nogo-A with an antibody caused a marked increase in the blood vessel density in vivo. In culture, Nogo-A inhibited spreading, migration, and sprouting of primary brain microvascular endothelial cells (MVECs) in a dose-dependent manner and induced the retraction of MVEC lamellipodia and filopodia. Mechanistically, we show that only the Nogo-A-specific Delta 20 domain exerts inhibitory effects on MVECs, but the Nogo-66 fragment, an inhibitory domain common to Nogo-A, -B, and -C, does not. Furthermore, the action of Nogo-A Delta 20 on MVECs required the intracellular activation of the Ras homolog gene family, member A (Rho-A)-associated, coiled-coil containing protein kinase (ROCK)-Myosin II pathway. The inhibitory effects of early postnatal brain membranes or cultured neurons on MVECs were relieved significantly by anti-Nogo-A antibodies. These findings identify Nogo-A as an important negative regulator of developmental angiogenesis in the CNS. They may have important implications in CNS pathologies involving angiogenesis such as stroke, brain tumors, and retinopathies.

Liver iron modulates hepcidin expression during chronically elevated erythropoiesis in mice.

UNLABELLED: The liver-derived peptide hepcidin controls the balance between iron demand and iron supply. By inhibiting the iron export activity of ferroportin, hepcidin modulates iron absorption and delivery from the body's stores. The regulation of hepcidin, however, is not completely understood and includes a variety of different signals. We studied iron metabolism and hepcidin expression in mice constitutively overexpressing erythropoietin (Epo) (Tg6 mice), which leads to excessive erythropoiesis. We observed a very strong down-regulation of hepcidin in Tg6 mice that was accompanied by a strong increase in duodenal expression of ferroportin and divalent metal tranporter-1, as well as enhanced duodenal iron absorption. Despite these compensatory mechanisms, Tg6 mice displayed marked circulating iron deficiency and low levels of iron in liver, spleen, and muscle. To elucidate the primary signal affecting hepcidin expression during chronically elevated erythropoiesis, we increased iron availability by either providing iron (thus further increasing the hematocrit) or reducing erythropoiesis-dependent iron consumption by means of splenectomy. Both treatments increased liver iron and up-regulated hepcidin expression and the BMP6/SMAD pathway despite continuously high plasma Epo levels and sustained erythropoiesis. This suggests that hepcidin expression is not controlled by erythropoietic signals directly in this setting. Rather, these results indicate that iron consumption for erythropoiesis modulates liver iron content, and ultimately BMP6 and hepcidin. Analysis of the BMP6/SMAD pathway targets showed that inhibitor of DNA binding 1 (ID1) and SMAD7, but not transmembrane serine protease 6 (TMPRSS6), were up-regulated by increased iron availability and thus may be involved in setting the upper limit of hepcidin. CONCLUSION: We provide evidence that under conditions of excessive and effective erythropoiesis, liver iron regulates hepcidin expression through the BMP6/SMAD pathway.

Present, past and future of the European rock fern Asplenium fontanum: combining distribution modelling and population genetics to study the effect of climate change on geographic range and genetic diversity.

BACKGROUND AND AIMS: Climate change is expected to alter the geographic range of many plant species dramatically. Predicting this response will be critical to managing the conservation of plant resources and the effects of invasive species. The aim of this study was to predict the response of temperate homosporous ferns to climate change. METHODS: Genetic diversity and changes in distribution range were inferred for the diploid rock fern Asplenium fontanum along a South-North transect, extending from its putative last glacial maximum (LGM) refugia in southern France towards southern Germany and eastern-central France. This study reconciles observations from distribution models and phylogeographic analyses derived from plastid and nuclear diversity. KEY RESULTS: Genetic diversity distribution and niche modelling propose that genetic diversity accumulates in the LGM climate refugium in southern France with the formation of a diversity gradient reflecting a slow, post-LGM range expansion towards the current distribution range. Evidence supports the fern's preference for outcrossing, contradicting the expectation that homosporous ferns would populate new sites by single-spore colonization. Prediction of climate and distribution range change suggests that a dramatic loss of range and genetic diversity in this fern is possible. The observed migration is best described by the phalanx expansion model. CONCLUSIONS: The results suggest that homosporous ferns reproducing preferentially by outcrossing accumulate genetic diversity primarily in LGM climate refugia and may be threatened if these areas disappear due to global climate change.

25 years of lipid-lowering therapy: secular trends in therapy of coronary patients.

BACKGROUND AND AIM: Guidelines on dyslipidemia and lipid-lowering therapy (LLT) over the years recommend lower low-density lipoprotein cholesterol (LDL-C) goals by more intense therapy. Nevertheless, LDL­C has increased in the general population. Real-world trends of LLT medication as well as of LDL­C levels in cardiovascular high-risk patients are unclear. METHODS: From 2158 patients who were referred for elective coronary angiography, lipid medication was analyzed at admission in three cardiovascular observational studies (OS) over the last 25 years: OS1: 1999-2000, OS2: 2005-2008 and OS3: 2022-2023. The three studies were performed at the same cardiology unit of a tertiary care hospital in Austria. RESULTS: The proportion of patients without LLT significantly decreased from OS1 through OS2 to OS3 (49.4%, 45.6%, and 18.5%, respectively, ptrend < 0.001). Moreover, the percentage of patients under high-intensity statin treatment significantly increased from 0% to 5.1%, and 56.5% (ptrend < 0.001). Significantly more patients became treated by more than one compound (OS1: 1.8%, OS2: 1.6%, OS3: 31.2%; ptrend < 0.001). In the latest OS3, a trend to fixed-dose combination of statins with ezetimibe was observed. Mean LDL­C levels decreased from 129 mg/dL over 127 mg/dL to 83 mg/dL, respectively (ptrend < 0.001). Of the patients on high-intensity therapy 34% met the recent ESC/EAS goals (LDL-C < 55 mg/dL), but only 3% on non-intense therapy. CONCLUSION: We conclude that during the observational period of a quarter of a century, treatment intensity increased and LDL­C levels improved considerably. Guidelines apparently matter in this high-risk population and are considered by primary care physicians.

Current Practices of Medication Plans in Austrian Patients Undergoing Coronary Angiography: An In-Depth Analysis.

A complete medication plan (MPlan) increases medication safety and adherence and is crucial in care transitions. Countries that implemented a standardized MPlan reported benefits on patients' understanding and handling of their medication. Austria lacks such a standardization, with no available data on the issue. Objective: This study aimed to investigate the current state of all medication documentations (MDocs) at hospital admission in a population at high risk for polypharmacy in Austria. Methods: We enrolled 512 consecutive patients undergoing elective coronary angiography. Their MDocs and medications were recorded at admission. MDocs were categorized, whereby a MPlan was defined as a tabular list including medication name, dose, route, frequency and patient name. Results: Out of 485 patients, 55.1% had an MDoc (median number of drugs: 6, range 2-17), of whom 24.7% had unstructured documentation, 18.0% physicians' letters and 54.3% MPlans. Polypharmacy patients did not have a MDoc in 31.3%. Crucial information as the patients's name or the originator of the MDoc was missing in 31.1% and 20.4%, respectively. Patients with MDoc provided more comprehensive medication information (p = 0.019), although over-the-counter-medication was missing in 94.5% of MDocs. A discrepancy between the MPlan and current medication at admission existed in 64.4%. In total, only 10.7% of our patient cohort presented an MPlan that was in accordance with their current medication. Conclusion: The situation in Austria is far from a standardized MPlan generated in daily routine. Numerous MPlans do not represent the current medication and could pose a potential risk for the effectiveness and safety of pharmacotherapy.

A Comprehensive Insight and In Silico Analysis of CircRNAs in Hepatocellular Carcinoma: A Step toward ncRNA-Based Precision Medicine.

Circular RNAs (circRNAs) are cardinal players in numerous physiological and pathological processes. CircRNAs play dual roles as tumor suppressors and oncogenes in different oncological contexts, including hepatocellular carcinoma (HCC). Their roles significantly impact the disease at all stages, including initiation, development, progression, invasion, and metastasis, in addition to the response to treatment. In this review, we discuss the biogenesis and regulatory functional roles of circRNAs, as well as circRNA-protein-mRNA ternary complex formation, elucidating the intricate pathways tuned by circRNAs to modulate gene expression and cellular processes through a comprehensive literature search, in silico search, and bioinformatics analysis. With a particular focus on the interplay between circRNAs, epigenetics, and HCC pathology, the article sets the stage for further exploration of circRNAs as novel investigational theranostic agents in the dynamic realm of HCC.

Acute and chronic elevation of erythropoietin in the brain improves exercise performance in mice without inducing erythropoiesis.

Application of recombinant human erythropoietin (rhEpo) improves exercise capacity by stimulating red blood cell production that, in turn, enhances oxygen delivery and utilization. Apart from this, when applied at high doses, rhEpo crosses the blood-brain barrier, triggering protective neuronal effects. Here we show a fundamental new role by which the presence of Epo in the brain augments exercise performance without altering red blood cell production. Two different animal models, the transgenic mouse line Tg21, which constitutively overexpresses human Epo exclusively in the brain without affecting erythropoiesis, and wild-type mice treated with a single high dose of rhEpo, demonstrate an unexpected improvement in maximal exercise performance independent of changes in total hemoglobin mass, as well as in whole blood volume and cardiovascular parameters. This novel finding builds a more complete understanding regarding the central effects of endogenously produced and exogenously applied Epo on exercise performance.

Optimal hematocrit for maximal exercise performance in acute and chronic erythropoietin-treated mice.

Erythropoietin (Epo) treatment increases hematocrit (Htc) and, consequently, arterial O(2) content. This in turn improves exercise performance. However, because elevated blood viscosity associated with increasing Htc levels may limit cardiac performance, it was suggested that the highest attainable Htc may not necessarily be associated with the highest attainable exercise capacity. To test the proposed hypothesis that an optimal Htc in acute and chronic Epo-treated mice exists--i.e., the Htc that facilitates the greatest O(2) flux during maximal exercise--Htc levels of wild-type mice were acutely elevated by administering novel erythropoiesis-stimulating protein (NESP; wtNESP). Furthermore, in the transgenic mouse line tg6 that reaches Htc levels of up to 0.9 because of constitutive overexpression of human Epo, the Htc was gradually reduced by application of the hemolysis-inducing compound phenylhydrazine (PHZ; tg6PHZ). Maximal cardiovascular performance was measured by using telemetry in all exercising mice. Highest maximal O(2) uptake (VO(2max)) and maximal time to exhaustion at submaximal exercise intensities were reached at Htc values of 0.58 and 0.57 for wtNESP, and 0.68 and 0.66 for tg6PHZ, respectively. Rate pressure product, and thus also maximal working capacity of the heart, increased with elevated Htc values. Blood viscosity correlated with VO(2max). Apart from the confirmation of the Htc hypothesis, we conclude that tg6PHZ adapted better to varying Htc values than wtNESP because of the higher optimal Htc of tg6PHZ compared to wtNESP. Of note, blood viscosity plays a critical role in limiting exercise capacity.

Expression of hypoxia-inducible genes is suppressed in altered gravity due to impaired nuclear HIF1α accumulation.

Extravehicular activities, the backbone of manned space exploration programs, set astronauts into mild hypoxia. Unfortunately, microgravity aggravates threatening symptoms of hypoxia such as vision impairment and brain edema. Hypoxia-inducible factors (HIFs) sense cellular hypoxia and, subsequently, change the cells' expression profile instantaneously by rapidly translocating-most likely cytoskeleton-dependently-into the nucleus and subsequently forming transcription complexes with other proteins. We tested the hypothesis that this fundamental process could be altered by sudden changes in gravitational forces in parabolic flights using a newly developed pocket-size cell culture lab that deoxygenizes cells within 15 min. Sudden gravity changes (SGCs 1g-1.8g-0g-1.8g-1g) during hypoxic exposure suppressed expression of the HIF1α-dependent genes investigated as compared with hypoxia at constant 1g. Normoxic cells subjected to SGCs showed reduced nuclear but not cytoplasmatic HIF1α signal and appeared to have disturbed cytoskeleton architecture. Inhibition of the actin-dependent intracellular transport using a combination of myosin V and VI inhibitors during hypoxia mimicked the suppression of the HIF1α-dependent genes observed during hypoxic exposure during SGCs. Thus, SGCs seem to disrupt the cellular response to hypoxia by impairing the actin-dependent translocation of HIF1α into the nucleus.