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Whole-body vestibular-evoked balance responses decrease following ~ 55 min of normobaric hypoxia. It is unclear how longer durations of hypoxia affect the vestibular control of balance at the muscle and whole-body levels. This study examined how four hours of normobaric hypoxia influenced the vestibular control of balance. Fifteen participants (4 females; 11 males) stood on a force plate with vision occluded and head rotated rightward while subjected to three blocks of binaural, bipolar stochastic electrical vestibular stimulation (EVS; 0–25 Hz, root mean square amplitude = 1.1 mA) consisting of two, 90-s trials. The relationship between EVS and anteroposterior (AP) forces or medial gastrocnemius (MG) electromyography (EMG) was estimated in the time and frequency domains at baseline (BL; 0.21 fraction of inspired oxygen—FIO2) and following two (H2) and four (H4) hours of normobaric hypoxia (0.11 FIO2). The EVS-MG EMG short-latency peak and peak-to-peak amplitudes were smaller than BL at H2 and H4, but the medium-latency peak amplitude was only lower at H4. The EVS-AP force medium-latency peak amplitude was lower than BL at H4, but the short-latency peak and peak-to-amplitudes were unchanged. The EVS-MG EMG coherence and gain were reduced compared to BL at H2 and H4 across multiple frequencies ≥ 7 Hz, whereas EVS-AP force coherence was blunted at H4 (≤ 4 Hz), but gain was unaffected. Overall, the central nervous system's response to vestibular-driven signals during quiet standing was decreased for up to four hours of normobaric hypoxia, and vestibular-evoked responses recorded within postural muscles may be more sensitive than the whole-body response. [ABSTRACT FROM AUTHOR]

Although previous studies have demonstrated that methane (CH4) can mitigate the toxicity of cadmium (Cd) in alfalfa seedlings, the CH4-rich water used in these studies may create hypoxic conditions, potentially influencing the experimental outcomes. Therefore, this study aimed to investigate whether CH4 can reduce Cd toxicity in alfalfa seedlings without the interference of hypoxia and to analyze its underlying mechanisms. Here, it was observed that supplementing oxygen with saturated CH4-rich water can significantly alleviate the inhibition of 75 μM CdCl2 on the growth of alfalfa (Medicago sativa L.) seedlings. Less Cd accumulation was also observed in both root and shoot parts, which could be explained by the CH4-altered cell wall components in alfalfa seedling roots, including covalent and ionic soluble pectin, and the degree of demethylation in pectin, thus enabling a higher proportion of Cd binding to the cell walls and reducing the entry of Cd into the cells. The above actions of CH4 were accompanied by an increase in hydrogen peroxide (H2O2) content and NADPH oxidase activity, which could be blocked by the addition of the NADPH oxidase inhibitor diphenylene iodonium (DPI). Taken together, these results implied that exogenously applied CH4 could alleviate Cd toxicity in alfalfa seedlings by enhancing Cd chelation onto the root cell walls, which might be closely associated with NADPH oxidase-dependent H2O2 signals. These findings could provide insight into the mechanism through which CH4 alleviates Cd toxicity in alfalfa plants. [ABSTRACT FROM AUTHOR]

This study focuses on post-harvest pest management in agriculture, in particular the transition to modified atmospheres as a sustainable alternative to conventional pesticide methods. Using Computational Fluid Dynamics (CFD) simulations, we analysed the dynamics of oxygen distribution within a pest control chamber. We tested four different configurations of nitrogen inlet and outlet positions to determine the most effective setup. The simulations used the twoLiquidMixingFoam solver in OpenFOAM to model gas mixing and diffusion. Our results show that the configuration with the nitrogen inlet at the top and the outlet at the bottom (Case D) was the most efficient. This configuration reached the target oxygen concentration of 1.5% in 4.4 h, significantly faster than the other configurations. These results highlight the importance of inlet and outlet positioning in improving the efficiency of oxygen reduction and ensuring a consistent low oxygen level throughout the chamber. Optimising the placement of nitrogen inlets and outlets has significant potential to improve the effectiveness of modified atmosphere treatments for pest control. Future research should consider additional environmental factors, different storage conditions and insect mortality models to further refine these methods.

Purpose: To investigate the influence of acute normobaric hypoxia on standing balance under single and dual-task conditions, both with and without visual input. Methods: 20 participants (7 female, 20–31 years old) stood on a force plate for 16, 90-s trials across four balance conditions: single-task (quiet stance) or dual-task (auditory Stroop test), with eyes open or closed. Trials were divided into four oxygen conditions where the fraction of inspired oxygen (FIO2) was manipulated (normoxia: 0.21 and normobaric hypoxia: 0.16, 0.145 and 0.13 FIO2) to simulate altitudes of 1100, 3,400, 4300, and 5200 m. Participants breathed each FIO2 for ~ 3 min before testing, which lasted an additional 7–8 min per oxygen condition. Cardiorespiratory measures included heart rate, peripheral blood oxygen saturation, and pressure of end tidal (PET) CO2 and O2. Center of pressure measures included total path length, 95% ellipse area, and anteroposterior and mediolateral velocity. Auditory Stroop test performance was measured as response accuracy and latency. Results: Significant decreases in oxygen saturation and PETO2, and increased heart rate were observed between normoxia and normobaric hypoxia (P < 0.0001). Total path length was higher at 0.13 compared to 0.21 FIO2 for the eyes closed no Stoop test condition (P = 0.0197). No other significant differences were observed. Conclusion: These findings suggest that acute normobaric hypoxia has a minimal impact on standing balance and does not influence auditory Stroop test or dual-task performance. Further investigation with longer exposure is required to understand the impact and time course of normobaric hypoxia on standing balance. [ABSTRACT FROM AUTHOR]

Acute exposure to hypoxia increases postural sway, but the underlying neurophysiological factors are unclear. Golgi tendon organs (GTOs), located within the musculotendinous junction (MTJ), provide inhibitory signals to plantar flexor muscles that are important for balance control; however, it is uncertain if GTO function is influenced by hypoxia. The aim of this study was to determine how normobaric hypoxia influences lower limb tendon-evoked inhibitory reflexes during upright stance. We hypothesized that tendon-evoked reflex area and duration would decrease during hypoxia, indicating less inhibition of postural muscles compared with normoxia. At baseline (BL; 0.21 fraction of inspired oxygen, FIO2) and at ∼2 (H2) and 4 (H4) h of normobaric hypoxia (0.11 FIO2) in a normobaric hypoxic chamber, 16 healthy participants received electrical musculotendinous stimulation (MTstim) to the MTJ of the left Achilles tendon. The MTstim was delivered as two sets of 50 stimuli while the participant stood on a force plate with their feet together. Tendon-evoked inhibitory reflexes were recorded from the surface electromyogram of the ipsilateral medial gastrocnemius, and center of pressure (CoP) variables were recorded from the force plate. Normobaric hypoxia increased CoP velocity (P ≤ 0.002) but not CoP standard deviation (P ≥ 0.12). Compared with BL, normobaric hypoxia reduced tendon-evoked inhibitory reflex area by 45% at H2 and 53% at H4 (P ≤ 0.002). In contrast, reflex duration was unchanged during hypoxia. The reduced inhibitory feedback from the GTO pathway could likely play a role in the increased postural sway observed during acute exposure to hypoxia. NEW & NOTEWORTHY: The Ib pathway arising from the Golgi tendon organ provides inhibitory signals onto motor neuron pools that modifies force and, hence, postural control. Although hypoxia influences standing balance (increases sway), the underlying mechanisms have yet to be unraveled. Our study identified that tendon-evoked inhibition onto a plantar flexor motoneuron pool is reduced by acute exposure to normobaric hypoxia. This reduction of inhibition may contribute to the hypoxia-related increase in postural sway. [ABSTRACT FROM AUTHOR]

The large yellow croaker (Larimichthys crocea) displays pronounced behavioral changes in response to low oxygen environments, including restlessness, constant floating, and increases in respiratory rate and tail beat frequency. However, the underlying molecular mechanisms governing these behavioral and physiological alterations remain unclear. To address this knowledge gap, the present study employed transcriptome analysis to investigate the molecular responses in the large yellow croaker muscle tissue after the fish were exposed to hypoxic treatment. A total of 4553, 1797, 3222, 3148, and 4815 differentially expressed genes (DEGs) were identified at 1 h, 6 h, 9 h, 24 h, and 72 h after hypoxia treatment, respectively. Subsequent analysis utilizing Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichments unveiled a notable up-regulation of genes related to muscular movement-related pathways, specifically the calcium pathway. This up-regulation coincided with an observed increase in the intracellular Ca2+ concentration and Ca2+ transport enzyme activity, suggesting that hypoxia-induced muscle contraction and relaxation occurred by elevating the intracellular Ca2+ concentration within the muscle tissue. Key DEGs associated with the glycolysis and the TCA cycle pathways were also found to be significantly increased in expression, indicating an activation of energy generation pathways in the muscle of hypoxic large yellow croakers. Conversely, genes related to protein synthesis and cell growth were significantly down-regulated, suggesting an inhibition of energy-consuming processes. Additionally, hypoxia was observed to impact various physiological processes such as oxygen transport, vascular control, and apoptosis. These processes may have been mediated by the up-regulation of HIF-1α and its target genes. Consequently, these results offer novel insights into comprehending the molecular basis of the changes in behavior and physiology of large yellow croaker in response to the stress induced by low oxygen levels.

Extreme environmental conditions have profound impacts on shaping the evolutionary trajectory of organisms. Exposure to these conditions elicits stress responses, that can trigger phenotypic changes in novel directions. The Mexican Tetra, Astyanax mexicanus, is an excellent model for understanding evolutionary mechanisms in response to extreme or new environments. This fish species consists of two morphs; the classical surface‐dwelling fish and the blind cave‐dwellers that inhabit dark and biodiversity‐reduced ecosystems. In this review, we explore the specific stressors present in cave environments and examine the diverse adaptive strategies employed by cave populations to not only survive but thrive as successful colonizers. By analyzing the evolutionary responses of A. mexicanus, we gain valuable insights into the genetic, physiological, and behavioral adaptations that enable organisms to flourish under challenging environmental conditions. Research Highlights: Unique adaptations in cave populations of Astyanax mexicanus makes them a remarkable model to study the mechanisms underlying stress adaptation to environmental challenges. This review explores the remarkable adaptive strategies that allows the cavefish to successfully survive the challenging environmental shift at the time of cave colonization. [ABSTRACT FROM AUTHOR]

In recent years, research on flooding stress and hypoxic responses in plants has gathered increasing attention due to climate change and the important role of O2 in metabolism and signalling. This Collection of Functional Plant Biology on ‘Flooding stress and responses to hypoxia in plants’ presents key contributions aimed at progressing our current understanding on how plants respond to low-O2 conditions, flooding stress and a combination of stresses commonly found in flooded areas. The Collection emphasises the characterisation of diverse plant responses across different developmental stages, from seed germination to fully developed plants, and under different water stress conditions ranging from waterlogging to complete submergence, or simply low-O2 conditions resulting from limited O2 diffusivity in bulky tissues. Additionally, this Collection highlights diverse approaches, including eco-physiological characterisation of plant responses, detailed descriptions of root anatomical characteristics and their surrounding microenvironments, evaluation of the seed microbiota under flooding stress, the modification of gene expression, and evaluations of diverse germplasm collections. [ABSTRACT FROM AUTHOR]

Although previous studies have demonstrated that methane (CH4) can mitigate the toxicity of cadmium (Cd) in alfalfa seedlings, the CH4-rich water used in these studies may create hypoxic conditions, potentially influencing the experimental outcomes. Therefore, this study aimed to investigate whether CH4 can reduce Cd toxicity in alfalfa seedlings without the interference of hypoxia and to analyze its underlying mechanisms. Here, it was observed that supplementing oxygen with saturated CH4-rich water can significantly alleviate the inhibition of 75 μM CdCl2 on the growth of alfalfa (Medicago sativa L.) seedlings. Less Cd accumulation was also observed in both root and shoot parts, which could be explained by the CH4-altered cell wall components in alfalfa seedling roots, including covalent and ionic soluble pectin, and the degree of demethylation in pectin, thus enabling a higher proportion of Cd binding to the cell walls and reducing the entry of Cd into the cells. The above actions of CH4 were accompanied by an increase in hydrogen peroxide (H2O2) content and NADPH oxidase activity, which could be blocked by the addition of the NADPH oxidase inhibitor diphenylene iodonium (DPI). Taken together, these results implied that exogenously applied CH4 could alleviate Cd toxicity in alfalfa seedlings by enhancing Cd chelation onto the root cell walls, which might be closely associated with NADPH oxidase-dependent H2O2 signals. These findings could provide insight into the mechanism through which CH4 alleviates Cd toxicity in alfalfa plants.

Hypoxia increases postural sway compared to normoxia, but the underlying sensorimotor factors remain unclear. An important contributor to balance control is cutaneous feedback arising from the feet, which can be partially characterized by electrically evoking a reflex from a purely cutaneous nerve (i.e., sural) and sampling the subsequent motor activity of a muscle. The purpose of the present study was to determine how normobaric hypoxia influences sural nerve reflex parameters during a standing posture. It was hypothesized that normobaric hypoxia would reduce cutaneous reflex area compared to normoxia. Participants (n = 16; 5 females, 11 males) stood with their feet together while receiving two trials of 50 sural nerve stimulations (200-Hz, 5-pulse train, presented randomly every 3–6 s) at baseline (BL; normoxia), and at 2 (H2) and 4 (H4) h of normobaric hypoxia (~ 0.11 fraction of inspired oxygen in a hypoxic chamber). The sural nerve reflex was recorded using surface electromyography from the left medial gastrocnemius, and characterized by area and duration of the initial positive and negative peaks of the response. When normalized to pre-stimulus electromyography, the area of the peak-to-peak cutaneous reflex was not different than BL (p ≥ 0.14) for up to 4 h of normobaric hypoxia (BL: 0.26 ± 0.22, H2: 0.19 ± 0.19, H4: 0.22 ± 0.20 A.U.). Furthermore, the duration of the response was not different during hypoxia (BL: 73.2 ± 42.4; H2: 75.2 ± 47.0; H4: 77.6 ± 54.6 ms; p ≥ 0.13) than BL. Thus, reflexes arising from cutaneous afferents of the lateral border of the foot are resilient to at least 4 h of normobaric hypoxia. [ABSTRACT FROM AUTHOR]

In the context of post-harvest pest management in agricultural products, the adoption of modified atmospheres presents an eco-friendly alternative to conventional pesticides. This study focuses on nitrogen gas as a potential agent for insect control in stored commodities, utilizing computational simulations (by employing the convection–diffusion equation) to investigate its penetration and distribution within two common storage configurations: chamber-contained pallets and silos. The results highlight the influence of boundary conditions, commodity porosity, and convection effects on nitrogen dispersion. In chamber scenarios, the first boundary condition considers that pallets are placed inside a chamber with uniform (99.5%) nitrogen concentration, whereas in the second one, the concentration gradually increases from 78% to 99.5%. The average duration required for O 2 concentration to reach 1% is approximately 10.7 h and 133.3 h for the two boundary conditions, respectively. Among the agricultural commodities, walnuts (kernels) exhibit the shortest duration, while prunes require the longest time. In silos, convection and diffusion interact to establish a consistent diffusion layer thickness. Most agricultural products exhibit similar behavior, with average times of 13.5 h, 25.4 h, and 37.0 h for three heights (10 m, 20 m, and at the silo's top at 30 m), respectively. [ABSTRACT FROM AUTHOR]

Photorespiration, an essential component of plant metabolism, was upregulated under abiotic stress conditions, such as high light or drought. One of the signals for such upregulation was the rise in reactive oxygen species (ROS). Photorespiration was expected to mitigate oxidative stress by reducing ROS levels. However, it was unclear if ROS levels would increase when photorespiration was lowered. Our goal was to examine the redox status in leaves when photorespiratory metabolism was restricted under low O2 (medium flushed with N2 gas) or by adding aminooxyacetic acid (AOA), a photorespiratory inhibitor. We examined the impact of low O2 and AOA in leaves of Arabidopsis thaliana under dark, moderate, or high light. Downregulation of typical photorespiratory enzymes, including catalase (CAT), glycolate oxidase (GO), and phosphoglycolate phosphatase (PGLP) under low O2 or with AOA confirmed the lowering of photorespiratory metabolism. A marked increase in ROS levels (superoxide and H2O2) indicated the induction of oxidative stress. Thus, our results demonstrated for the first time that restricted photorespiratory conditions increased the extent of oxidative stress. We propose that photorespiration is essential to sustain normal ROS levels and optimize metabolism in cellular compartments of Arabidopsis leaves. [ABSTRACT FROM AUTHOR]

Abstract Background Cardiac fibrosis is one of the top killers among fibrotic diseases and continues to be a global unaddressed health problem. The lack of effective treatment combined with the considerable socioeconomic burden highlights the urgent need for innovative therapeutic options. Here, we evaluated the anti-fibrotic properties of extracellular vesicles (EVs) derived from human induced pluripotent stem cells (hiPSCs) that were cultured under various oxygen concentrations. Methods EVs were isolated from three hiPSC lines cultured under normoxia (21% O2; EV-N) or reduced oxygen concentration (hypoxia): 3% O2 (EV-H3) or 5% O2 (EV-H5). The anti-fibrotic activity of EVs was tested in an in vitro model of cardiac fibrosis, followed by a detailed investigation of the underlying molecular mechanisms. Sequencing of EV miRNAs combined with bioinformatics analysis was conducted and a selected miRNA was validated using a miRNA mimic and inhibitor. Finally, EVs were tested in a mouse model of angiotensin II-induced cardiac fibrosis. Results We provide evidence that an oxygen concentration of 5% enhances the anti-fibrotic effects of hiPS-EVs. These EVs were more effective in reducing pro-fibrotic markers in activated human cardiac fibroblasts, when compared to EV-N or EV-H3. We show that EV-H5 act through the canonical TGFβ/SMAD pathway, primarily via miR-302b-3p, which is the most abundant miRNA in EV-H5. Our results show that EV-H5 not only target transcripts of several profibrotic genes, including SMAD2 and TGFBR2, but also reduce the stiffness of activated fibroblasts. In a mouse model of heart fibrosis, EV-H5 outperformed EV-N in suppressing the inflammatory response in the host and by attenuating collagen deposition and reducing pro-fibrotic markers in cardiac tissue. Conclusions In this work, we provide evidence of superior anti-fibrotic properties of EV-H5 over EV-N or EV-H3. Our study uncovers that fine regulation of oxygen concentration in the cellular environment may enhance the anti-fibrotic effects of hiPS-EVs, which has great potential to be applied for heart regeneration. Graphical Abstract

Background: Cardiac fibrosis is one of the top killers among fibrotic diseases and continues to be a global unaddressed health problem. The lack of effective treatment combined with the considerable socioeconomic burden highlights the urgent need for innovative therapeutic options. Here, we evaluated the anti-fibrotic properties of extracellular vesicles (EVs) derived from human induced pluripotent stem cells (hiPSCs) that were cultured under various oxygen concentrations. Methods: EVs were isolated from three hiPSC lines cultured under normoxia (21% O2; EV-N) or reduced oxygen concentration (hypoxia): 3% O2 (EV-H3) or 5% O2 (EV-H5). The anti-fibrotic activity of EVs was tested in an in vitro model of cardiac fibrosis, followed by a detailed investigation of the underlying molecular mechanisms. Sequencing of EV miRNAs combined with bioinformatics analysis was conducted and a selected miRNA was validated using a miRNA mimic and inhibitor. Finally, EVs were tested in a mouse model of angiotensin II-induced cardiac fibrosis. Results: We provide evidence that an oxygen concentration of 5% enhances the anti-fibrotic effects of hiPS-EVs. These EVs were more effective in reducing pro-fibrotic markers in activated human cardiac fibroblasts, when compared to EV-N or EV-H3. We show that EV-H5 act through the canonical TGFβ/SMAD pathway, primarily via miR-302b-3p, which is the most abundant miRNA in EV-H5. Our results show that EV-H5 not only target transcripts of several profibrotic genes, including SMAD2 and TGFBR2, but also reduce the stiffness of activated fibroblasts. In a mouse model of heart fibrosis, EV-H5 outperformed EV-N in suppressing the inflammatory response in the host and by attenuating collagen deposition and reducing pro-fibrotic markers in cardiac tissue. Conclusions: In this work, we provide evidence of superior anti-fibrotic properties of EV-H5 over EV-N or EV-H3. Our study uncovers that fine regulation of oxygen concentration in the cellular environment may enhance the anti-fibrotic effects of hiPS-EVs, which has great potential to be applied for heart regeneration. [ABSTRACT FROM AUTHOR]

In this study, we aimed to identify long noncoding RNAs (lncRNAs) in root tips of the model legume Medicago truncatula using previously generated nuclear, total polyA, ribosome‐associated polyA, and Riboseq RNA datasets, which might shed light on their localization and potential regulatory roles. RNA‐seq data were mapped to the version 5 of the M. truncatula A17 genome and analyzed to identify genome annotated lncRNAs and putative new root tip (NRT) lncRNAs. lncRNAs were classified according to their genomic location relative to chromatin accessible regions, protein‐coding genes and transposable elements (TE), finding differences between annotated lncRNAs and NRT lncRNAs, both in their genomic position as well as in the type of TEs in their vicinity. We investigated their response to submergence and found a set of regulated lncRNAs that were preferentially upregulated in the nucleus, some of which were located nearby genes of the conserved submergence upregulated gene families, and chromatin accessible regions suggesting a potential regulatory role. Finally, the accumulation of lncRNAs under submergence was validated by reverse transcription quantitative polymerase chain reaction on nuclear RNA, providing additional evidence of their localization, which could ultimately be required for their function. [ABSTRACT FROM AUTHOR]

Food-deprivation state (fed, fasted, starved) affected rock crabs physiological and biochemical responses to hypoxia in Cancer irroratus. Fasted and starved crabs were better adapted to deal with hypoxia than fed animals; however, avoidance behavior is usually considered as the first defense to environmental stressors for decapod crustaceans. We examined the effects of food deprivation on the crab's behavior to hypoxia using the Loligo® shuttle box system, an automated system with a pair of connected water chambers with regulated flow and oxygen level. Crabs (starved, fasted and fed) that were offered a choice of two different oxygen saturations did not appear to actively avoid the hypoxia regimes tested (50% and 20% oxygen saturation). We used novel algorithms to analyze the data and found that crabs altered rheotaxis (movement towards or away from a current of water) and corresponding moving speed as a function of oxygen saturation. The food-deprivation state did influence thigmotaxis (contact with walls/objects when exploring an open space): starved crabs became bolder and more likely to explore open areas of the apparatus. Technological advancements such as the fully automated shuttle box have improved our ability to collect and analyze behavioral data; however, our study also highlighted some of the potential problems of relying solely on such apparatus to study the behavior of benthic crustaceans. [ABSTRACT FROM AUTHOR]

The low temperature normally applied to prevent fruit decay during the storage of apples, can also triggers the onset of a chilling injury disorder known as superficial scald. In this work, the etiology of this disorder and the mechanism of action of two preventing strategies, such as the application of 1-MCP (1-methylcyclopropene) and storage at low oxygen concentration in 'Granny Smith' and 'Ladina' apple cultivars were investigated. The metabolite assessment highlighted a reorganization of specific metabolites, in particular flavan-3-ols and unsaturated fatty acids, while the genome-wide transcriptomic analysis grouped the DEGs into four functional clusters. The KEGG pathway and GO enrichment analysis, together with the gene-metabolite interactome, showed that the treatment with 1-MCP prevented the development of superficial scald by actively promoting the production of unsaturated fatty acids, especially in 'Granny Smith'. 'Ladina', more susceptible to superficial scald and less responsive to the preventing strategies, was instead characterized by a higher accumulation of very long chain fatty acids. Storage at low oxygen concentration stimulated a higher accumulation of ethanol and acetaldehyde together with the expression of genes involved in anaerobic respiration, such as malate, alcohol dehydrogenase and pyruvate decarboxylase in both cultivars. Low oxygen concentration, likewise 1-MCP, through a direct control on ethylene prevented the onset of superficial scald repressing the expression of PPO, a gene encoding for the polyphenol oxidase enzyme responsible of the oxidation of chlorogenic acid. Moreover, in 'Granny Smith' apple, the expression of three members of the VII subgroups of ERF genes, encoding for elements coordinating the acclimation process to hypoxia in plants was observed. The global RNA-Seq pattern also elucidated a specific transcriptomic signature between the two cultivars, disclosing the effect of the different genetic background in the control of this disorder. [ABSTRACT FROM AUTHOR]

We carried out trials on the commercial applications of nitrogen in different industrial structures, using phosphine-susceptible and -resistant populations of three stored product beetle species, the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), and the saw-toothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). Twelve different trials were conducted in total, five in chambers and seven in large silos in Greece, following different temperatures and exposure times. In most of our trials, complete mortality was recorded, with the exception of two silos in which survival was recorded for T. castaneum and O. surinamensis, while S. oryzae was classified as the most susceptible species. Moreover, low or no progeny production was recorded for most of the trials. Our results indicate that nitrogen, through the reduction in the oxygen level, could be used for the control of stored product insects that are resistant to phosphine, and can be further utilized in resistance management strategies. [ABSTRACT FROM AUTHOR]

In the context of post-harvest pest management in agricultural products, the adoption of modified atmospheres presents an eco-friendly alternative to conventional pesticides. This study focuses on nitrogen gas as a potential agent for insect control in stored commodities, utilizing computational simulations (by employing the convection–diffusion equation) to investigate its penetration and distribution within two common storage configurations: chamber-contained pallets and silos. The results highlight the influence of boundary conditions, commodity porosity, and convection effects on nitrogen dispersion. In chamber scenarios, the first boundary condition considers that pallets are placed inside a chamber with uniform (99.5%) nitrogen concentration, whereas in the second one, the concentration gradually increases from 78% to 99.5%. The average duration required for O2 concentration to reach 1% is approximately 10.7 h and 133.3 h for the two boundary conditions, respectively. Among the agricultural commodities, walnuts (kernels) exhibit the shortest duration, while prunes require the longest time. In silos, convection and diffusion interact to establish a consistent diffusion layer thickness. Most agricultural products exhibit similar behavior, with average times of 13.5 h, 25.4 h, and 37.0 h for three heights (10 m, 20 m, and at the silo’s top at 30 m), respectively.

Dynamic Controlled Atmosphere (DCA) is beneficial in maintaining specific quality parameters but, due to the extreme oxygen levels applied, can cause adverse effects on the fruit by inducing excessive anaerobic metabolism and the production of off-flavors. The metabolic adaptation and responses of apples (Malus domestica Borkh.) cv. Red Delicious to static or dynamic oxygen concentrations (0.3 and 0.8%, with sequential shifts) during cold storage for 7 months were studied by monitoring quality parameters and the expression of genes involved in sugar, fermentative metabolism, and ethylene physiology. Ethanol content reached the highest levels (around 400 mg/kg FW) under 0.3% oxygen concentration and fruit firmness appeared to be reduced in samples accumulating the highest levels of ethanol. Oxygen switch was effective in reducing the ethanol concentrations with timing-dependent variable effects. The expression of fermentative (alcohol dehydrogenase, lactate dehydrogenase, pyruvate decarboxylase) and sugar metabolism (β-amylase; phosphofructokinase; sucrose synthase) genes resulted to be differently affected by the hypoxic conditions imposed, in particular during the early stages of storage. Sucrose synthase expression appeared to be highly sensitive to changes in low oxygen concentration. Ethylene biosynthesis (ACC synthase and oxidase) genes showed marked differences in their expression in relation to the static and dynamic protocols and the hypoxic conditions, as well as six Ethylene Responsive Factors (ERF) genes, some of them possibly involved in the oxygen sensing mechanism operating in fruit tissues.

In order to better solve the phenomenon of low oxygen in the corner of return airway caused by abnormal gas emission in goaf during shallow coal seam mining, by analyzing the source and reason of low oxygen phenomenon, a prediction model of oxygen concentration in the corner of return airway based on genetic algorithm (GA) and random forest (RF) technology was proposed. The training sample set was established by using the field data obtained from actual monitoring, including the oxygen concentration in the return airway corner, the periodic pressure step distance of the roof, the surface temperature and atmospheric pressure. GA was used to optimize the parameters in the RF model, including trees and leaves in the forest. The results showed that the model prediction error was minimum when the number of trees was 398 and the number of leaves was 1. In addition, GA was used to optimize the number of hidden neurons and the initial weight threshold of the back-propagation neural network (BPNN). In order to verify the superiority of the model, the GA optimized RF and BPNN model are compared with the conventional RF and BPNN model. Analyze the average absolute percentage error (MAPE), root mean square error (RMSE), and average absolute error (MAE) of the prediction data of each model. The results show that the optimized RF prediction model is better than other models in terms of prediction accuracy. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hypoxia influences standing balance and vestibular function. OBJECTIVE: The purpose here was to investigate the effect of hypoxia on the vestibular control of balance. METHODS: Twenty participants (10 males; 10 females) were tested over two days (normobaric hypoxia and normoxia). Participants stood on a force plate (head rotated leftward) and experienced random, continuous electrical vestibular stimulation (EVS) during trials of eyes open (EO) and closed (EC) at baseline (BL), after 5 (H1), 30 (H2) and 55-min (H3) of hypoxia, and 10-min into normoxic recovery (NR). Vestibular-evoked balance responses were quantified using cumulant density, coherence, and gain functions between EVS and anteroposterior forces. RESULTS: Oxyhemoglobin saturation, end-tidal oxygen and carbon dioxide decreased for H1-3 compared to BL; however, end-tidal carbon dioxide remained reduced at NR with EC (p≤0.003). EVS-AP force peak-to-peak amplitude was lower at H3 and NR than at BL (p≤0.01). At multiple frequencies, EVS-AP force coherence and gain estimates were lower at H3 and NR than BL for females; however, this was only observed for coherence for males. CONCLUSIONS: Overall, vestibular-evoked balance responses are blunted following normobaric hypoxia >30 min, which persists into NR and may contribute to the reported increases in postural sway. [ABSTRACT FROM AUTHOR]

Dynamic Controlled Atmosphere (DCA) is beneficial in maintaining specific quality parameters but, due to the extreme oxygen levels applied, can cause adverse effects on the fruit by inducing excessive anaerobic metabolism and the production of off flavors. The metabolic adaptation and responses of apples (Malus domestica Borkh.) cv. Red Delicious to static or dynamic oxygen concentrations (0.3 and 0.8%, with sequential shifts) during cold storage for 7 months were studied by monitoring quality parameters and the expression of genes involved in sugar, fermentative metabolism, and ethylene physiology. Ethanol content reached the highest levels (around 400 mg/kg FW) under 0.3% oxygen concentration and fruit firmness appeared to be reduced in samples accumulating the highest levels of ethanol. Oxygen switch was effective in reducing the ethanol concentrations with timingdependent variable effects. The expression of fermentative (alcohol dehydrogenase, lactate dehydrogenase, pyruvate decarboxylase) and sugar metabolism (ß-amylase; phosphofructokinase; sucrose synthase) genes resulted to be differently affected by the hypoxic conditions imposed, in particular during the early stages of storage. Sucrose synthase expression appeared to be highly sensitive to changes in low oxygen concentration. Ethylene biosynthesis (ACC synthase and oxidase) genes showed marked differences in their expression in relation to the static and dynamic protocols and the hypoxic conditions, as well as six Ethylene Responsive Factors (ERF) genes, some of them possibly involved in the oxygen sensing mechanism operating in fruit tissues. [ABSTRACT FROM AUTHOR]

Low oxygen (LO) conditions slow the deterioration and improve the quality of fresh horticultural produce. We analyzed the metabolites of perianths stored under LO (1 % O 2) and ambient oxygen conditions (control) to clarify the mechanisms associated with improvement in cut gladiolus spike quality by capillary electrophoresis time-of-flight mass spectrometry and high-performance liquid chromatography. The findings showed that the developmental progression of floret states (i.e., budding, open, and wilted) in cut gladiolus spikes was relatively slow during and after LO storage. In a metabolomic examination of 80 metabolites present in the perianths of 5th florets, 27 metabolites were identified by ANOVA and subjected to partial least squares discriminant analysis. Based on the variable importance in projection score, two intermediate metabolites of the glycolytic pathway, ribulose 5-phosphate and sucrose, along with several amino acids, were identified as being important for differentiating between the control and LO conditions. The accumulation of phosphoenolpyruvic acid and 3-phosphoglyceric acid during LO storage implies that aerobic respiration is suppressed under LO conditions. While the concentrations of sucrose increased during LO storage, those of glucose and fructose increased after LO storage, indicating that LO conditions affect sugar metabolism. These changes may slow the rate at which floret states develop under LO conditions. In addition, β-alanine, 4-aminobutanoic acid characteristically increased under LO conditions compared to control conditions, potentially as an adaptation to hypoxic conditions. • Growth of perianths in cut gladiolus spikes was slow during low oxygen (LO) storage. • Increases of PEP and 3-PG indicates the restriction of aerobic respirations under LO. • There were differences of changes of soluble sugars between the control and LO. • Three non-proteinogenic amino acids characteristically increased under LO. [ABSTRACT FROM AUTHOR]

Estuaries and coastal waters are sensitive to ecological degradation but receive some of the highest levels of pollutants. One impact of these pollutants is increased greenhouse gas generation, which is significant, but difficult to estimate due to high variability and data paucity. This paper investigates key controls on methane (CH 4) and nitrous oxide (N 2 O) in the urban, mesotidal, stratified Clyde estuary, Scotland, between January 2020 and October 2022. Measurements covered the estuary longitudinally, through tidal cycles and across the river-estuary transition. Dissolved CH 4 and N 2 O were always supersaturated relative to air exhibiting strong spatial and temporal variability. Estuary surface freshwater layer CH 4 concentrations were positively correlated with turbidity and exceeded 5.4 μmol l−1. Lower saline layer CH 4 concentrations exceeded 10.8 μmol l−1 and were highest after freshwater flushing events. The CH 4 concentrations decreased exponentially with salinity persistence (time since last freshwater flushing event), reducing by 50% after 10 days of continuously saline water. Salinity persistence likely provides a tipping point between the dominance of different microbial communities. Considering the persistence of saline conditions can explain much of the previously reported variability in estuarine CH 4. In the surface freshwater layer, N 2 O exceeded 0.15 μmol l−1, while in the lower saline layer N 2 O exceeded 0.21 μmol l−1, despite lower dissolved nitrogen, increasing the N 2 O per unit available nitrogen. There was a significant inverse exponential correlation (R2 = 0.96) between N 2 O and dissolved oxygen in the lower layer, with low oxygen driving elevated N 2 O concentrations. This study provides unique insights into the conditions that generate CH 4 and N 2 O in a stratified urban-impacted estuary. [Display omitted] • CH 4 decreased exponentially with salinity persistence (50% after 10 days). • CH 4 concentrations were reinviorgated by freshwater flushing events. • Low dissolved oxygen exponentially increased N 2 O concentrations. • Nutrients, flushing and stratification all contributed to low dissolved oxygen. [ABSTRACT FROM AUTHOR]

BACKGROUND: Data are provided on the utilization of modified atmospheres, at a commercial scale, against stored product insect populations that are resistant to phosphine. The method is evaluated on different populations of two major stored‐product beetle species, Rhyzopertha dominica and Oryzaephilus surinamensis. The trials were carried out in commercial facilities, in which nitrogen was introduced through an embedded nitrogen generator. Each chamber contained three or four pallets of either currants or herbs. A computational model was developed to evaluate the nitrogen concentration. RESULTS: In most trials, 100% mortality was recorded for both beetle species and all populations, regardless of the temperature and exposure intervals tested. Control progeny production ranged between 20 and 45 adults per vial for R. dominica, and 29 and 27 adults per vial for O. surinamensis. Simulation results reveal that nitrogen can easily penetrate the currants, and its concentration is uniform (differences are below 1.5%) across the pallet. Additionally, the simulation model revealed that lower temperatures do not have an impact on the nitrogen concentration profiles. CONCLUSIONS: The modified atmosphere applications evaluated here were proved to be effective for all populations, regardless of the level of resistance to phosphine, and any survival could be attributed to the short exposure intervals. Modified atmosphere applications can be effective at a considerably short exposure interval, even at 2.5 days, which is an incontestable advantage for the use of this method against insects, at exposures comparable with those of commercial fumigations. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

In order to solve the problem of low oxygen in the first working face 5-20101 of Qinglongsi Coal Mine, in this paper, combined with the working face mining and the surrounding basic situation, it is found that the influence of atmospheric pressure change, low temperature oxidation of the residual coal in goaf, water and gas displacement in goaf and positive pressure fan ventilation in tail-lane are the important reasons for low oxygen in working face. Some technical measures have been taken, such as establishing the monitoring system of spontaneous combustion, reducing the negative pressure of mine ventilation, strengthening the sealing of air leakage above and below the mine, inerting the floating coal in the goaf, improving the progress of the working face and injecting nitrogen into the goaf, so as to effectively solve the problem of low oxygen in the mining process of the working face and ensure the safe production of the mine.

Based on the mining practice of Shendong Bulianta Coal Mine, this paper analyzes and summarizes the low-oxygen problems in the mining process of the fully mechanized working face in the overlying large goaf of the close distance coal seams, and finds that the low-oxygen phenomenon presents the annual season, time of day, and special weather, and other laws, and divides low oxygen into two categories: local low oxygen and large area low oxygen. Taking the 22410 fully mechanized mining face of Bulianta Coal Mine as the research object, it proposes personnel management and control of key positions, real-time monitoring of gas in high-probability low-oxygen areas, equipment and facilities in key areas, low-oxygen early warning and comprehensive emergency treatment technologies for local low oxygen; aiming at large-area low oxygen, a comprehensive emergency response technology for pressure-equalized ventilation, “three-network integration” emergency linkage, and emergency rescue was proposed to ensure the safe production of mines.

Low-oxygen conditions (hypoxia) have been associated primarily with cell-cycle arrest in dividing cells. Macrophages are typically quiescent in G0 but can proliferate in response to tissue signals. Here we show that hypoxia (1% oxygen tension) results in reversible entry into the cell cycle in macrophages. Cell cycle progression is largely limited to G0-G1/S phase transition with little progression to G2/M. This cell cycle transitioning is triggered by an HIF2α-directed transcriptional program. The response is accompanied by increased expression of cell-cycle-associated proteins, including CDK1, which is known to phosphorylate SAMHD1 at T592 and thereby regulate antiviral activity. Prolyl hydroxylase (PHD) inhibitors are able to recapitulate HIF2α-dependent cell cycle entry in macrophages. Finally, tumor-associated macrophages (TAMs) in lung cancers exhibit transcriptomic profiles representing responses to low oxygen and cell cycle progression at the single-cell level. These findings have implications for inflammation and tumor progression/metastasis where low-oxygen environments are common. [Display omitted] • 1% oxygen results in reversible cell cycle re-entry in macrophages • Transition triggered by HIF2α-directed transcriptional program and MEK-ERK activation • CDK1 accumulation is accompanied by SAMHD1 phosphorylation at T592 • Cell cycle and hypoxia signatures seen in tumor-associated macrophage transcriptomes Meng et al. show that 1% oxygen results in cell cycle re-entry in macrophages. Mechanistically, this is triggered by an HIF2α-directed transcriptional program and accompanied by reversible activation of the canonical MEK/ERK proliferation pathway. CDK1-associated SAMHD1 phosphorylation at T592 in hypoxic macrophages renders them more susceptible to lentiviral transduction. [ABSTRACT FROM AUTHOR]

We carried out trials on the commercial applications of nitrogen in different industrial structures, using phosphine-susceptible and -resistant populations of three stored product beetle species, the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), and the saw-toothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). Twelve different trials were conducted in total, five in chambers and seven in large silos in Greece, following different temperatures and exposure times. In most of our trials, complete mortality was recorded, with the exception of two silos in which survival was recorded for T. castaneum and O. surinamensis, while S. oryzae was classified as the most susceptible species. Moreover, low or no progeny production was recorded for most of the trials. Our results indicate that nitrogen, through the reduction in the oxygen level, could be used for the control of stored product insects that are resistant to phosphine, and can be further utilized in resistance management strategies.

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Abstract Background Restoring community walking remains a highly valued goal for persons recovering from traumatic incomplete spinal cord injury (SCI). Recently, studies report that brief episodes of low-oxygen breathing (acute intermittent hypoxia, AIH) may serve as an effective plasticity-inducing primer that enhances the effects of walking therapy in persons with chronic (> 1 year) SCI. More persistent walking recovery may occur following repetitive (weeks) AIH treatment involving persons with more acute SCI, but this possibility remains unknown. Here we present our clinical trial protocol, designed to examine the distinct influences of repetitive AIH, with and without walking practice, on walking recovery in persons with sub-acute SCI (

In order to better solve the phenomenon of low oxygen in the corner of return airway caused by abnormal gas emission in goaf during shallow coal seam mining, by analyzing the source and reason of low oxygen phenomenon, a prediction model of oxygen concentration in the corner of return airway based on genetic algorithm (GA) and random forest (RF) technology was proposed. The training sample set was established by using the field data obtained from actual monitoring, including the oxygen concentration in the return airway corner, the periodic pressure step distance of the roof, the surface temperature and atmospheric pressure. GA was used to optimize the parameters in the RF model, including trees and leaves in the forest. The results showed that the model prediction error was minimum when the number of trees was 398 and the number of leaves was 1. In addition, GA was used to optimize the number of hidden neurons and the initial weight threshold of the back-propagation neural network (BPNN). In order to verify the superiority of the model, the GA optimized RF and BPNN model are compared with the conventional RF and BPNN model. Analyze the average absolute percentage error (MAPE), root mean square error (RMSE), and average absolute error (MAE) of the prediction data of each model. The results show that the optimized RF prediction model is better than other models in terms of prediction accuracy.

In order to determine the main control factors of the low oxygen event in the fully mechanized mining face of Bulianta mine, fault tree analysis and analytic hierarchy process were used to establish a low oxygen event model for the fully mechanized mining face.The FTA was used to determine the basic events of low oxygen events in working face, the structural importance of basic events was calculated and the corresponding discriminant factors was determined. The AHP method was used to classify the various causes and construct the matrix, and the nine-element scale method was used to redistribute the weights of each factor in the criterion and indicator layers of the model, and finally determine the corresponding weight of each factor. The research results show that the main controlling factors of low oxygen events in Bulianta Mine are shallow buried depth and poor rock soundness, which ranks first in the total indexes, and the strong spontaneous combustion tendency of the coal and air leakage in the working face, which ranks second in the total indexes. [ABSTRACT FROM AUTHOR]

Effect of low temperature and low oxygen concentration on biochemical attributes, antioxidant enzyme activities, phenolics profile and expression of phenylpropanoid pathway-related genes was investigated in crabapple (Malus profusion) fruit. Crabapple fruit were kept at room temperature (RT, 20 ± 2 °C and 25 ± 2 °C alternatively at 12 h cycle) or low temperature (LT, 10 ± 2 °C and 25 ± 2 °C alternatively at 12 h cycle) and supplemented with either normal oxygen (21%) or low oxygen levels (5%) for 9 days. Results revealed higher concentrations of soluble solids, titratable acids, and ascorbic acid in fruit stored at LT + 5% O2. Likewise, total phenolics, peroxidase activity, and 2,2´-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)-radical scavenging activity were observed to be significantly higher in fruit stored at low temperature (LT + 5% O2 > LT + 21% O2), followed by those stored at room temperature (RT + 5% O2 > RT + 21% O2). In contrast, H2O2 and malondialdehyde contents were significantly enhanced in fruit stored at room temperature (RT + 21% O2 and RT + 5% O2), whereas fruit stored at low temperature showed minimum inhibition in superoxide dismutase, catalase and ascorbate peroxidase activities. In addition, low temperature induced biosynthesis of phenolic acids, whereas no considerable changes were observed in flavanols and dihydrochalcones during storage. Low temperature and oxygen conditions (LT + 5% O2) significantly enhanced the biosynthesis of flavonols (glycosylated quercetin derivatives) and cyanidin 3-galactoside, compared to LT + 21% O2, RT + 5% O2 and RT + 21% O2 conditions. In addition, low temperature also up-regulated the expression of MpFLS and MpUFGT in fruit tissues. Moreover, correlation analysis suggested positive association of antioxidant capacity with the biosynthesis of flavonols and anthocyanins in fruit stored at LT + 5% O2. [ABSTRACT FROM AUTHOR]

Purpose: The present study aimed to identify the physiological characteristics of cells by investigating the change in gene expression and protein levels during extracellular matrix (ECM) synthesis in the intervertebral disc (IVD) under hypoxic conditions. Materials and Methods: To test the effect of oxygen on cell growth and ECM synthesis of chondrocyte-like cells, the cells from IVD were separated and cultured in two hypoxia-mimicking systems: chemical hypoxic conditions using deferoxamine (DFO), and physiological hypoxic conditions using a hypoxic chamber for 7 days. Chondrocyte like cells cultured without DFO and under the normal oxygen concentration (21% O2 and 5% CO2, 37°C) served as the controls. Results: Chondrocyte-like cells cultured in the presence of 6% oxygen demonstrated a 100% increase in cellular proliferation compared to the control. The cells treated with chemical hypoxic conditions demonstrated a dose-dependent increase in the mRNA expression of glucose transporter-1, GAPDH, aggrecan, and type II collagen on Day 1. When treated with 100 μM DFO, the cells showed a 50% increase in the levels of proteoglycan protein on Day 7. The cells treated with chemical hypoxic condition demonstrated increase in sulfated glycosaminoglycan (GAG) protein levels on Day 7. Moreover, the cells cultured in the presence of 6% oxygen showed a 120% increase in sulfated GAG levels on Day 7. Conclusion: The oxygen concentration had an important role in the viability, proliferation, and maturation of chondrocyte-like cells in IVD. In addition, chondrocyte-like cells are sensitive to the concentration of oxygen. [ABSTRACT FROM AUTHOR]

Abstract Microbial methane oxidation is a major biofilter preventing larger emissions of this powerful greenhouse gas from marine coastal areas into the atmosphere. In these zones, various electron acceptors such as sulfate, metal oxides, nitrate, or oxygen can be used. However, the key microbial players and mechanisms of methane oxidation are poorly understood. In this study, we inoculated a bioreactor with methane‐ and iron‐rich sediments from the Bothnian Sea to investigate microbial methane and iron cycling under low oxygen concentrations. Using metagenomics, we investigated shifts in microbial community composition after approximately 2.5 years of bioreactor operation. Marker genes for methane and iron cycling, as well as respiratory and fermentative metabolism, were identified and used to infer putative microbial metabolism. Metagenome‐assembled genomes representing novel Verrucomicrobia, Bacteroidetes, and Krumholzibacteria were recovered and revealed a potential for methane oxidation, organic matter degradation, and iron cycling, respectively. This work brings new hypotheses on the identity and metabolic versatility of microorganisms that may be members of such functional guilds in coastal marine sediments and highlights that microorganisms potentially composing the methane biofilter in these sediments may be more diverse than previously appreciated.

The marine environment is predicted to become warmer and more hypoxic, and these conditions may become a challenge for marine fish species. Phenotypically plastic responses facilitating acclimatization to changing environments can be mediated by DNA methylation through the modulation of gene expression. To investigate whether temperature and hypoxia exposure induce DNA methylation changes, we challenged post-smolt Atlantic salmon (Salmo salar) to increasing temperatures (12 → 20°C, 1°C week–1) under normoxia or moderate hypoxia (∼70% air saturation) and compared responses in the liver after 3 days or 4 weeks at 20°C. DNA methylation was studied in six genes related to temperature stress (cirbp, serpinh1), oxidative stress (prdx6, ucp2), apoptosis (jund), and metabolism (pdk3). Here, we report that exposure to high temperature, alone or combined with hypoxia, affected the methylation of CpG sites within different genomic regulatory elements around the transcription start of these temperature/hypoxia biomarker genes. Yet, we uncovered distinct CpG methylation profiles for each treatment group, indicating that each environmental condition may induce different epigenetic signatures. These CpG methylation responses were strongly dependent on the duration of stress exposure, and we found reversible, but also persistent, CpG methylation changes after 4 weeks of exposure to 20°C. Further, several of these changes in CpG methylation correlated with transcriptional changes, and thus, can be considered as regulatory epigenetic marks (epimarkers). Our study provides insights into the dynamic associations between CpG methylation and transcript expression in Atlantic salmon, and suggests that this epigenetic mechanism may mediate physiological acclimation to short-term and long-term environmental changes.

While investigating the preservation of the aroma of various spices we compared the effects of hermetic conditions, vacuum and carbon dioxide versus aerated storage. The quality of the tested spices stored under hermetic conditions was comparable to those stored in vacuum after 120 d of storage. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure. Throughout the investigation on specialty coffee, the volatility was evaluated as particularly important because coffee taste and aroma are influenced by compounds that are volatile. We hypothesize that hermetic storage reduces the rate of the volatiles to spread to the atmosphere. Dry food commodities can be stored for extended periods, provided there is no insect infestation and their water activity is low enough to prevent microbial growth. However, in aerated storages quantitative and qualitative losses still occur. If the moisture content is maintained sufficiently low, insects and quality loss remain the main concern for the quality preservation of durable agricultural commodities. Although in hermetic storage, the major emphasis is placed on the control of insect pests, for quality preservation just maintaining the vapor pressure in the sealed structure is sufficient. Quality preservation under hermetic conditions remains an aspect that deserves more attention. This characteristic of hermetic storage is the tendency to maintain within the hermetic structure the substances that have the ability to vaporize.

Penicillium digitatum and P. italicum are the major postharvest pathogens in citrus. To reduce postharvest decay, the use of low-oxygen (0.9 kPa O2) (LO) or low-pressure (6.6 kPa) (LP) treatments were evaluated during the storage of navel oranges for four or eight days. The results showed that exposure to both LO and LP treatments reduced in vivo pathogen growth compared to the untreated (UTC) oranges, with LO being the most effective. The effects of LO and LP on fruit metabolism and quality were further assessed, and it was found that there was no effect on fruit ethylene production, respiration rate, TSS (total soluble solids), TA (titratable acidity) or fruit firmness. However, both LO and LP treatments did have an effect on juice ethanol concentration and fruit weight-loss. The effect of adding exogenous ethylene at either LP (1 µL/L) or atmospheric pressure (AP) (at either 0.1, 1 µL/L) was also evaluated, and results showed that the addition of ethylene at these concentrations had no effect on mould diameter at LP or AP. Therefore, both LO of 0.9 kPa O2 and LP of 6.6 kPa at 20 °C are potential non-chemical postharvest treatments to reduce mould development during storage with minimal effects on fruit quality.

Background: Restoring community walking remains a highly valued goal for persons recovering from traumatic incomplete spinal cord injury (SCI). Recently, studies report that brief episodes of low-oxygen breathing (acute intermittent hypoxia, AIH) may serve as an effective plasticity-inducing primer that enhances the effects of walking therapy in persons with chronic (> 1 year) SCI. More persistent walking recovery may occur following repetitive (weeks) AIH treatment involving persons with more acute SCI, but this possibility remains unknown. Here we present our clinical trial protocol, designed to examine the distinct influences of repetitive AIH, with and without walking practice, on walking recovery in persons with sub-acute SCI (< 12 months) SCI. Our overarching hypothesis is that daily exposure (10 sessions, 2 weeks) to AIH will enhance walking recovery in ambulatory and non-ambulatory persons with subacute (< 12 months) SCI, presumably by harnessing endogenous mechanisms of plasticity that occur soon after injury.Methods: To test our hypothesis, we are conducting a randomized, placebo-controlled clinical trial on 85 study participants who we stratify into two groups according to walking ability; those unable to walk (non-ambulatory group) and those able to walk (ambulatory group). The non-ambulatory group receives either daily AIH (15, 90s episodes at 10.0% O2 with 60s intervals at 20.9% O2) or daily SHAM (15, 90s episodes at 20.9% O2 with 60s intervals at 20.9% O2) intervention. The ambulatory group receives either 60-min walking practice (WALK), daily AIH + WALK, or daily SHAM+WALK intervention. Our primary outcome measures assess overground walking speed (10-Meter Walk Test), endurance (6-Minute Walk Test), and balance (Timed Up & Go Test). For safety, we also measure levels of pain, spasticity, systemic hypertension, and autonomic dysreflexia. We record outcome measures at baseline, days 5 and 10, and follow-ups at 1 week, 1 month, 6 months, and 12 months post-treatment.Discussion: The goal of this clinical trial is to reveal the extent to which daily AIH, alone or in combination with task-specific walking practice, safely promotes persistent recovery of walking in persons with traumatic, subacute SCI. Outcomes from this study may provide new insight into ways to enhance walking recovery in persons with SCI.Trial Registration: ClinicalTrials.gov, NCT02632422 . Registered 16 December 2015. [ABSTRACT FROM AUTHOR]

To evaluate the efficacy of group embryo culture under low-oxygen tension in benchtop incubators on human embryo development in vitro. The study was designed as a prospective, patient blind, randomized, controlled trial of a complex intervention. One hundred forty-eight women undergoing IVF were recruited in our fertility practice and randomized into two groups: intervention group (study culture strategy) or control group (control culture strategy). Intervention group embryos were cultured grouped under low-oxygen tension in benchtop incubators while control group embryos were cultured individually under atmospheric oxygen tension in large-box incubators. Using the study culture strategy, there were a significantly higher implantation rate (65.1% vs 49.2%; RR, 1.42; 95% CI, 1.17–1.73) and live birth delivery rate per embryo transfer (52.7% vs 39.5%; RR, 1.33; 95% CI, 1.02–1.75) with the first fresh embryo transfer. Cumulative implantation rate (56.7% vs 43.6%; RR, 1.30; 95% CI, 1.05–1.62) and cumulative live birth rate per embryo transfer (47.4% vs 36.2%; RR, 1.31; 95% CI, 1.01–1.69) were also statistically significantly increased in the study culture strategy. Human embryos exposed to our study culture condition strategy had statistically significant increased cumulative implantation rate and cumulative live birth rate per embryo transferred. Our findings suggest that this strategy specially favours poor quality embryos. Clinical Trial Registration Number: NCT 01904006 [ABSTRACT FROM AUTHOR]

Hypoxia is the most detrimental threat to humans residing at high altitudes, affecting multifaceted cellular responses that are crucial for normal homeostasis. Inhalation of nitric oxide has been successfully implemented to combat the hypoxia effect in the high altitude patients. We hypothesize that nitric oxide (NO) restores the peripheral blood mononuclear cell‐matrix deadhesion during hypoxia. In the present study, we investigate the cellular action of exogenous NO in the hypoxia‐mediated diminution of cell‐matrix adhesion of PBMNC and NO bioavailability in vitro. The result showed that NO level and cell‐matrix adhesion of PBMNC were significantly reduced in hypoxia as compared with normoxia, as assessed by the DAF‐FM and cell adhesion assay, respectively. In contrast, cellular oxidative damage response was indeed upregulated in hypoxic PBMNC. Further, gene expression analysis revealed that mRNA transcripts of cell adhesion molecules (Integrin α5 and β1) and eNOS expressions were significantly downregulated. The mechanistic study revealed that administration of NO and 8‐Br‐cGMP and overexpression of eNOS‐GFP restored the basal NO level and recovers cell‐matrix adhesion in PBMNC via cGMP‐dependent protein kinase I (PKG I) signalling. In conclusion, NO‐cGMP/PKG signalling may constitute a novel target to recover high altitude–afflicted cellular deadhesion. Significance of this study: Cellular adhesion is a complex multistep process. The ability of cells to adhere to extracellular matrix is an essential physiological process for normal homeostasis and function. Hypoxia exposure in the PBMNC culture has been proposed to induce oxidative damage and cellular deadhesion and is generally believed to be the key factor in the reduction of NO bioavailability. In the present study, we demonstrated that NO donor or overexpression of eNOS‐GFP has a protective effect against hypoxia‐induced cellular deadhesion and greatly improves the redox balance by inhibiting the oxidative stress. Furthermore, this protective effect of NO is mediated by the NO‐cGMP/PKG signal pathway, which may provide a potential strategy against hypoxia. [ABSTRACT FROM AUTHOR]

ChlR is a MarR-type transcriptional regulator that activates the transcription of the chlAII-ho2-hemN operon in response to low oxygen conditions in the cyanobacterium Synechocystis sp. PCC 6803. Upon exposure to low oxygen conditions, ChlR activates transcription of the operon that encodes enzymes critical to tetrapyrrole biosynthesis under low oxygen conditions. We previously identified a super-activator variant, D35H, of ChlR that constitutively activates transcription of the operon. To gain insight into the low-oxygen induced activation of ChlR, we obtained eight additional super-activator variants of ChlR including D35H from pseudorevertants of a chlAI-disrupted mutant. Most substitutions were located in the N-terminal region of ChlR. Mapping of the substituted amino acid residues provided valuable structural insights that uncovered the activation mechanism of ChlR. Super-activator variants of ChlR isolated in this work constitutively activate the transcription of the chlAII operon even under aerobic conditions where the wild type ChlR is inactive. [ABSTRACT FROM AUTHOR]

Low‐headspace oxygen was used in the hydroponic design to evaluate the toxicity of sulfide to wild rice (Zizania palustris). Oxygen levels in the headspace gas phase were maintained at <0.005 atm. The results indicated that mesocotyl emergence was the most sensitive endpoint (≥3.1 mg/L sulfide and 0.8 mg/L iron [Fe]). At 2.8 mg Fe/L, ≥7.8 mg/L sulfide was required to reduce emergence, shoot weight, and shoot length. Overall, the results were similar to those of previous studies in which atmospheric oxygen was maintained in the headspace gas phase, demonstrating that the oxygen level in the headspace gas phase during mesocotyl emergence and early growth was not a significant factor in sulfide tolerance. Environ Toxicol Chem 2020;39:659–666. © 2020 SETAC [ABSTRACT FROM AUTHOR]

Cyclooxygenase (COX) is proposed to regulate cerebral blood flow (CBF); however, accurate regional contributions of COX are relatively unknown at baseline and particularly during hypoxia. We hypothesized that COX contributes to both basal and hypoxic cerebral vasodilation, but COX-mediated vasodilation is greater in the posterior versus anterior cerebral circulation. CBF was measured in 9 healthy adults (28 ± 4 yr) during normoxia and isocapnic hypoxia (fraction of inspired oxygen = 0.11), with COX inhibition (oral indomethacin, 100mg) or placebo. Four-dimensional flow magnetic resonance imaging measured cross-sectional area (CSA) and blood velocity to quantify CBF in 11 cerebral arteries. Cerebrovascular conductance (CVC) was calculated (CVC = CBF × 100/mean arterial blood pressure) and hypoxic reactivity was expressed as absolute and relative change in CVC [ΔCVC/Δ pulse oximetry oxygen saturation (SpO2)]. At normoxic baseline, indomethacin reduced CVC by 44 ± 5% (P < 0.001) and artery CSA (P < 0.001), which was similar across arteries. Hypoxia (SpO2 80%-83%) increased CVC (P < 0.01), reflected as a similar relative increase in reactivity (% ΔCVC/-Δ SpO2) across arteries (P < 0.05), in part because of increases in CSA (P < 0.05). Indomethacin did not alter ΔCVC or ΔCVC/Δ SpO2 to hypoxia. These findings indicate that 1) COX contributes, in a largely uniform fashion, to cerebrovascular tone during normoxia and 2) COX is not obligatory for hypoxic vasodilation in any regions supplied by large extracranial or intracranial arteries. [ABSTRACT FROM AUTHOR]

To date, there is no direct evidence of telomerase activity in adult lung epithelial cells, but typical culture conditions only support cell proliferation for 30‐40 population doublings (PD), a point at which telomeres remain relatively long. Here we report that in in vitro low stress culture conditions consisting of a fibroblast feeder layer, rho‐associated coiled coil protein kinase inhibitor (ROCKi), and low oxygen (2%), normal human bronchial epithelial basal progenitor cells (HBECs) divide for over 200 PD without engaging a telomere maintenance mechanism (almost four times the "Hayflick limit"). HBECs exhibit critically short telomeres at 200 PD and the population of cells start to undergo replicative senescence. Subcloning these late passage cells to clonal density, to mimic lung injury in vivo, selects for rare subsets of HBECs that activate low levels of telomerase activity to maintain short telomeres. CRISPR/Cas9 knockout of human telomerase reverse transcriptase or treatment with the telomerase‐mediated telomere targeting agent 6‐thio‐2′deoxyguanosine abrogates colony growth in these late passage cultures (>200 PD) but not in early passage cultures (<200 PD). To our knowledge, this is the first study to report such long‐term growth of HBECs without a telomere maintenance mechanism. This report also provides direct evidence of telomerase activation in HBECs near senescence when telomeres are critically short. This novel cell culture system provides an experimental model to understand how telomerase is regulated in normal adult tissues. [ABSTRACT FROM AUTHOR]