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Rainbow trout (Oncorhynchus mykiss) is a hypoxia-sensitive fish, and its growth, behavior, metabolism, and immunity are affected in hypoxic environments. To elucidate the effects of hypoxic stress on the heart of rainbow trout, biochemical indices and hypoxia-related gene expression were measured during moderate (4.5±0.1 mg/L) and severe hypoxia (3.0±0.1 mg/L) stress for 4 h, 8 h, 12 h, and 24 h; moderate hypoxia for 1 month (TMM); severe hypoxia for 1 month (TMM); and reoxygenation (8.5±0.1 mg/L) for 12 h and 24 h using enzyme activity assays and quantitative real time polymerase chain reaction (RT-qPCR). The results showed that the pyruvate kinase (PK), total cholesterol (TC), lactic acid (LD), and glutamine aminotransferase (GPT) reactivates increased at 8 h, decreased at 24 h, and were significantly higher than the control levels after reoxygenation (P < 0.05) under moderate hypoxic stress. Under severe hypoxic stress, the succinate dehydrogenase (SDH) activities gradually increased and peaked at 8 h (P < 0.05). No significant difference was observed between the control at 24 h and after reoxygenation (P > 0.05). The adenosine triphosphatase (ATPase), lipase (LPS), TC, glutamic transaminase (GOT), and GPT reactivates decreased at 12 h and recovered to normal levels after reoxygenation (P > 0.05). The PK, TC, lactate dehydrogenase (LDH), and GPT reactivates were significantly higher in the TMM and TMS groups than those in the control group (P < 0.05). The expressions of succinate dehydrogenase gene (sdh), factor inhibiting hypoxia-inducible factor-1 (fih1), and hypoxia-inducible factor-1α (hif-1α) were significantly increased at 8 h compared to those of the control (P < 0.05) and returned to normal reactivates after reoxygenation. Under severe hypoxic stress, lactate dehydrogenase gene (ldh), pyruvate kinase gene (pk), sdh, hif-1α, proline hydroxylase domain protein 2 (egln-1), and von Hippel-Lindau (vhl) expressions were significantly increased at 24 h (P < 0.05) compared to those under moderate hypoxic stress. Compared with those of the control group, ldh, pk, sdh, hif-1α, egln-1, and vhl expressions were significantly decreased in the TMM and TMS groups under moderate hypoxic stress with no significant differences (P > 0.05). pk, sdh, and vhl were significantly increased under severe hypoxic stress (P < 0.05). This study indicated that varying levels of dissolved oxygen led to changes in biochemical indices and in the expression of hypoxic-related genes in the heart of rainbow trout. Hypoxic stress affected the cardiac metabolism of rainbow trout, which affected the normal metabolism level and caused damage. Under hypoxic stress, the rainbow trout were able to provide feedback regulation of hypoxic stress through the high expression pattern of hypoxic-related, which prevents the heart from being in a constant state of hypoxic stress, allowing the organism to quickly return to a stable state and perform its normal physiological function. This study provides basic data to further elucidate the regulatory mechanism of cardiac metabolism in rainbow trout under hypoxic stress, it has guiding significance for the intensive and healthy breeding of this fish and the selection and breeding of new hypoxia-tolerant species in the future.

Exopalaemon carinicauda has the highest production in the Yellow Sea and Bohai Sea of China. Compared with those of other shrimp species, E. carinicauda has a short reproductive cycle, fast growth, and adaptability. The pond mono-culture and mixed culture mode is more common in small economic shrimp and can be used as an excellent biological material for crustacean biology research. Dissolved oxygen, an important environmental factor for aquatic animal survival, affects the growth, behavior, reproduction, immunity, and metabolism of aquatic animals and is highly susceptible to hypoxia due to high temperatures, flushing, water pollution, the expansion of the scale of aquaculture, high-density aquaculture, high temperatures, and climate change. Recently, studies have been conducted on the effects of hypoxia on aquatic animals, mainly focusing on immune response, energy consumption, respiration, and antioxidant character. Gill and hepatopancreas tissue are major organs in crustaceans and increasing evidence reveal that gut bacterial community are involved in host immune defense, nutrient absorption, and antioxidant processes. Therefore, investigating the effects of hypoxic stress on the tissue structure and gut bacterial community of E. carinicauda will help to elucidate the mechanism of the response of E. carinicauda to hypoxic environments, which will be useful for its healthy aquaculture. In this study, we collected gill, hepatopancreas, and gut tissues from experimental and control groups after 24 h of hypoxic stress (2.5±0.2) mg/L. The gills and hepatopancreas were sectioned and observed and the changes in gut bacterial community before and after hypoxic stress were analyzed using 16S rRNA gene sequencing. The experimental results showed that gill and hepatopancreas tissues underwent different degrees of damage after hypoxic stress; the gut bacterial community changed, some pillar and epithelial cells of gill tissues were disordered, the number of chloride cells was significantly reduced, chloride cells were changed from irregularly flattened to rounded, the secondary lamellae was aggravated, and the gill tissues changed their morphology and structure to alleviate the hypoxic stress. The number of storage cells in hepatopancreas tissues did not change significantly compared with that of the control group, the lumen contracted significantly, the morphology and structure of the entire hepatic tubule contracted, the volume of transport vacuole increased significantly and even ruptured, and the number of secretory cells decreased significantly. Although shrimp gut bacteria are numerous and diverse the vast majority of gut bacteria are reported to be concentrated in a few dominant bacterial phyla, such as Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes. The richness and diversity of gut bacterial community of individuals in the experimental group changed significantly after hypoxic stress and Proteobacteria and Firmicutes were the dominant bacterial phylum in the guts of the control group, accounting for 81.42% and 11.18% of the total amount, respectively. The amounts of Bacteroidota and Actinobacteriota were significantly higher (P < 0.05), and that of Proteobacteria were significantly lower (P < 0.05) in the experimental group. At the family level, the numbers of Prevotellaceae and Lachnospiraceae were significantly higher (P < 0.05) in the experimental group than those in the control group. Rhodobacteraceae bacteria had a relative high abundance in the gut of healthy E. carinicauda and their amounts were significantly reduced after hypoxic stress. In addition, the numbers of some potential pathogenic bacteria were significantly higher (P < 0.05) in the experimental group. At present, multiple studies are being conducted on aquatic animals under hypoxic stress; however, the effects of hypoxic stress on the tissue structure and intestinal flora of E. carinicauda remains unexplored. In this study, we observed the damage of tissue structure and simultaneously analyzed the changes in intestinal flora of E. carinicauda under hypoxic stress, to deeply study the physiological response to stress under hypoxic conditions of E. carinicauda and provide basic scientific research on the actual production and cultivation of a novel species of E. carinicauda that is resistant to hypoxic conditions. This will provide basic scientific research information for the actual production and cultivation of novel hypoxia-tolerant varieties of E. carinicauda.

Hypoxia is an important characteristic of Tibetan plateau environment. It can lead to apoptosis, but the mechanism of apoptosis caused by hypoxic stress needs further clarification. Here, cattle kidney cell MDBK were used as cell model. The effect of hypoxic stress on apoptosis and its molecular mechanism were explored. MDBK cells were treated with hypoxic stress, apoptosis and mitochondrial apoptotic pathway were significantly increased, and the expression of B-cell lymphoma 6 (BCL6) was significantly decreased. Overexpressing or inhibiting BCL6 demonstrated that BCL6 inhibited the apoptosis. And the increase of apoptosis controlled by hypoxic stress was blocked by BCL6 overexpressing. MDBK cells were treated with hypoxic stress, the expression and the nuclear localization of p53 were significantly increased. Overexpressing or inhibiting p53 demonstrated that hypoxic stress suppressed the expression of BCL6 through p53. Together, these results indicated that hypoxic stress induced the apoptosis of MDBK cells, and BCL6 was an important negative factor for this regulation process. In MDBK cells, hypoxic stress suppressed the expression of BCL6 through p53/BCL6-mitochondrial apoptotic pathway. This study enhanced current understanding of the molecular mechanisms underlying the regulation of apoptosis by hypoxic stress in MDBK cells. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology / Shuisheng Shengwu Xuebao is the property of Editorial Department of Journal of Hydrobiology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We investigated the effects of dietary supplementation with sodium propionate (SP) and tributyrin (TB) on hepatic lipid deposition and antioxidant capacity of spotted seabass (Lateolabrax maculatus) via an 8-week feeding experiment and a hypoxia stress experiment. The fish were fed five experimental diets: a control diet (CON), a diet supplemented with 2 g/kg SP (SP-0.2%), 4 g/kg SP (SP-0.4%), 2 g/kg TB (TB-0.2%), or 4 g/kg TB (TB-0.4%). No significant difference in growth performance was presented among the groups (P > 0.05). The SP-0.4% and TB- 0.2% groups presented significantly lower hepatosomatic and viscerasomatic indexes compared with the CON group. Then, the SP-0.4% and TB-0.2% groups presented stronger resistance to hypoxic stress than the other groups and were analyzed further. The hepatic histology and triglyceride levels revealed that SP- 0.4% and TB-0.2% reduced hepatic lipid deposition. Similarly, the downregulation of malondialdehyde and the upregulation of total antioxidant capacity, superoxide dismutase, and catalase activities and the related gene expression levels revealed that SP-0.4% and TB-0.2% improved the antioxidant capacity. Additionally, the RNA sequencing demonstrated that SP-0.4% and TB- 0.2% regulated gene expression to a similar extent. Among the 117 differentially expressed genes, 67 genes were enriched in the same pattern, and involved the FoxO signaling, PI3K-Akt signaling, and insulin-related pathways. In conclusion, supplementing SP-0.4% and TB-0.2% as feed additives effectively improved hepatic lipid metabolism, antioxidant capacity, and hypoxic stress resistance of spotted seabass. [ABSTRACT FROM AUTHOR]

Simple Summary: Under heat stress, the aerobic metabolic activity of the body is significantly accelerated, which easily leads to hypoxia of high-oxygen consumption tissues, such as the mammary gland. In dairy cattle growing in the high-temperature and high-humidity environment in Guangxi, especially those in the peak period of lactation with strong metabolism, the lack of oxygen in the mammary cells is more obvious, and the milk volume and composition are greatly affected, and even lead to metabolic disorders. Nitidine chloride (NC) is a natural alkaloid with antioxidant properties that can remove excess reactive oxygen species (ROS). However, there is limited information on the effect of NC on BMECs hypoxic injury and its molecular mechanism. In this study, molecular biological methods combined with non-targeted metabolomics were used to study the protective effect of NC on BMECs induced by hypoxic stress. Based on the results obtained, we found that NC has a protective effect on hypoxic mitochondria and regulates amino acid metabolism in response to hypoxic stress. Hypoxia in the mammary gland epithelial cells of milk buffalo (BMECs) can affect milk yield and composition, and it can even cause metabolic diseases. Nitidine chloride (NC) is a natural alkaloid with antioxidant properties that can scavenge excessive reactive oxygen species (ROS). However, the effect of NC on the hypoxic injury of BMECs and its molecular mechanisms are still unknown. Here, an immunofluorescence assay, transmission electron microscopy (TEM), and flow cytometry, combined with untargeted metabolomics, were used to investigate the protective effect of NC on hypoxic stress injury in BMECs. It was found that NC can significantly reduce cell activity (p < 0.05) and inhibit cellular oxidative stress (p < 0.05) and cell apoptosis (p < 0.05). A significant decrease in mitophagy mediated by the PINK1-Parkin pathway was observed after NC pretreatment (p < 0.05). In addition, a metabolic pathway enrichment analysis demonstrated that the mechanisms of NC against hypoxic stress may be related to the downregulation of pathways involving aminoacyl tRNA biosynthesis; arginine and proline metabolism; glycine, serine, and threonine metabolism; phenylalanine, tyrosine, and tryptophan biosynthesis; and phenylalanine metabolism. Thus, NC has a protective effect on hypoxic mitochondria, and it can regulate amino acid metabolism in response to hypoxic stress. The present study provides a reference for the application of nitidine chloride to regulate the mammary lactation function of milk buffalo. [ABSTRACT FROM AUTHOR]

Abstract Terrestrial organisms are likely to face hypoxic stress during natural disasters such as floods or landslides, which can lead to inevitable hypoxic conditions for those commonly residing within soil. Pardosa pseudoannulata often inhabits soil crevices and has been extensively studied, yet research on its response to hypoxic stress remains unclear. Therefore, we investigated the adaptive strategies of Pardosa pseudoannulata under hypoxic stress using metabolomics and transcriptomics approaches. The results indicated that under hypoxic stress, metabolites related to energy and antioxidants such as ATP, D-glucose 6-phosphate, flavin adenine dinucleotide (FAD), and reduced L-glutathione were significantly differentially expressed. Pathways such as the citric acid (TCA) cycle and oxidative phosphorylation were significantly enriched. Transcriptome analysis and related assessments also revealed a significant enrichment of pathways associated with energy metabolism, suggesting that Pardosa pseudoannulata primarily copes with hypoxic environments by modulating energy metabolism and antioxidant-related substances.

Terrestrial organisms are likely to face hypoxic stress during natural disasters such as floods or landslides, which can lead to inevitable hypoxic conditions for those commonly residing within soil. Pardosa pseudoannulata often inhabits soil crevices and has been extensively studied, yet research on its response to hypoxic stress remains unclear. Therefore, we investigated the adaptive strategies of Pardosa pseudoannulata under hypoxic stress using metabolomics and transcriptomics approaches. The results indicated that under hypoxic stress, metabolites related to energy and antioxidants such as ATP, D-glucose 6-phosphate, flavin adenine dinucleotide (FAD), and reduced L-glutathione were significantly differentially expressed. Pathways such as the citric acid (TCA) cycle and oxidative phosphorylation were significantly enriched. Transcriptome analysis and related assessments also revealed a significant enrichment of pathways associated with energy metabolism, suggesting that Pardosa pseudoannulata primarily copes with hypoxic environments by modulating energy metabolism and antioxidant-related substances. [ABSTRACT FROM AUTHOR]

Early-life stress affects brain development, eventually resulting in adverse behavioral and physical health consequences in adulthood. The present study assessed the hypothesis that short-term early-life stress during infancy before weaning, a period for the maturation of mastication and sleep, poses long-lasting adverse effects on masticatory function and intraoral sensations later in life. Rat pups were exposed to either maternal separation (MS) or intermittent hypoxia (IH-Infancy) for 6 h/day in the light/sleep phase from postnatal day (P)17 to P20 to generate "neglect" and "pediatric obstructive sleep apnea" models, respectively. The remaining rats were exposed to IH during P45–P48 (IH-Adult). Masticatory ability was evaluated based on the rats' ability to chew pellets and bite pasta throughout the growth period (P21–P70). Intraoral chemical and mechanical sensitivities were assessed using two-bottle preference drinking tests, and hind paw pain thresholds were measured in adulthood (after P60). No differences were found in body weight, grip force, and hind paw sensitivity in MS, IH-Infancy, and IH-Adult rats compared with naïve rats. Masticatory ability was lower in MS and IH-Infancy rats from P28 to P70 than in naïve rats. MS and IH-Infancy rats exhibited intraoral hypersensitivity to capsaicin and mechanical stimulations in adulthood. The IH-Adult rats did not display inferior masticatory ability or intraoral hypersensitivity. In conclusion, short-term early-life stress during the suckling–mastication transition period potentially causes a persistent decrease in masticatory ability and intraoral hypersensitivity in adulthood. The period is a "critical window" for the maturation of oral motor and sensory functions. [ABSTRACT FROM AUTHOR]

We investigated the effects of dietary supplementation with sodium propionate (SP) and tributyrin (TB) on hepatic lipid deposition and antioxidant capacity of spotted seabass (Lateolabrax maculatus) via an 8-week feeding experiment and a hypoxia stress experiment. The fish were fed five experimental diets: a control diet (CON), a diet supplemented with 2 g/kg SP (SP-0.2%), 4 g/kg SP (SP-0.4%), 2 g/kg TB (TB-0.2%), or 4 g/kg TB (TB-0.4%). No significant difference in growth performance was presented among the groups (P > 0.05). The SP-0.4% and TB-0.2% groups presented significantly lower hepatosomatic and viscerasomatic indexes compared with the CON group. Then, the SP-0.4% and TB-0.2% groups presented stronger resistance to hypoxic stress than the other groups and were analyzed further. The hepatic histology and triglyceride levels revealed that SP-0.4% and TB-0.2% reduced hepatic lipid deposition. Similarly, the downregulation of malondialdehyde and the upregulation of total antioxidant capacity, superoxide dismutase, and catalase activities and the related gene expression levels revealed that SP-0.4% and TB-0.2% improved the antioxidant capacity. Additionally, the RNA sequencing demonstrated that SP-0.4% and TB-0.2% regulated gene expression to a similar extent. Among the 117 differentially expressed genes, 67 genes were enriched in the same pattern, and involved the FoxO signaling, PI3K-Akt signaling, and insulin-related pathways. In conclusion, supplementing SP-0.4% and TB-0.2% as feed additives effectively improved hepatic lipid metabolism, antioxidant capacity, and hypoxic stress resistance of spotted seabass.

Regular exercise is a well-established means to improve brain health and prevent age-related neurological diseases, including dementia (Marques-Aleixo et al., 2020). The precise mechanisms how direct exercise effects are transmitted to the brain remain incompletely understood. However, the increased oxygen demand and associated metabolic stress in the primarily affected tissues – the working skeletal muscle, the cardiovascular and the respiratory system – likely play crucial roles in exercise-signalling to the brain (Severinsen & Pedersen, 2020). Besides the mobilization of beneficial circulating factors, the modulation of blood properties and blood-flow, the immune system and the autonomous system are involved. Intriguingly, physiological stress induced by low environmental oxygen availability (hypoxia) can induce the activation of similar processes like exercise. The aim of this contribution is to evaluate the role of hypoxia in the benefits of exercise on the brain. Accumulating evidence demonstrates the potential of direct modulation of inspired oxygen levels to improve neurological diseases (Burtscher et al., 2021). Reduced all-cause mortality in people living at moderate altitudes (and therefore in chronic, mild hypobaric hypoxia) may also be associated with reduced risk of neurological diseases, including of stroke (Faeh et al., 2009). This is surprising, because the hypoxic stress at moderate altitudes (usually defined as altitudes between 1,500 and 2,500 m) is generally considered too low to induce substantial hypoxia adaptations. It is thus possible that the combination of moderate environmental hypoxia at moderate altitude with the increased oxygen demand during exercise is required to promote protective adaptations, such as of the brain. Considering this possibility, synergistic and complementary molecular and systemic responses and adaptations to exercise and hypoxia may benefit the brain. Among the involved molecular processes are mitochondrial changes following cellular stress that are also linked to the regulation of adaptations by the transcription factor hypoxia inducible factor, which is activated by both hypoxia and exercise. Mitochondria are the main molecular oxygen consumers, respond sensitively to stress and dispose of a wide array of intra- and intercellular communication modes (Memme et al., 2021). Moreover, exerkines, blood-borne factors released in response to exercise, have emerged as important mediators of inter-organ exercise-signalling (Severinsen & Pedersen, 2020) and modulate the autonomic and immune system in response to hypoxic and metabolic stress. In conclusion, the activation of endogenous responses to hypoxic and metabolic stress are powerful means to improve brain health and healthy aging. Based on the overlapping and distinct physiological responses to hypoxia and exercise, brain benefits of exercising at higher altitudes and advances in the development of customized strategies to improve brain resilience are promising approaches to target neurological diseases. While the safe performance of exercise in moderate altitudes is already considered an impactful way to improve brain health, the optimization of combined exercise and (artificially induced) hypoxia for specific target groups requires further in-depth investigation. References Burtscher, J., Mallet, R. T., Burtscher, M., & Millet, G. P. (2021). Hypoxia and brain aging: Neurodegeneration or neuroprotection? Ageing Research Reviews, 68, Article 101343. https://doi.org/10.1016/j.arr.2021.101343 Faeh, D., Gutzwiller, F., Bopp, M., & Group, S. N. C. S. (2009). Lower mortality from coronary heart disease and stroke at higher altitudes in Switzerland. Circulation, 120(6), 495-501. https://doi.org/10.1161/CIRCULATIONAHA.108.819250 Marques-Aleixo, I., Beleza, J., Sampaio, A., Stevanović, J., Coxito, P., Gonçalves, I., Ascensão, A., & Magalhães, J. (2020). Preventive and therapeutic potential of physical exercise in neurodegenerative diseases. Antioxidants & Redox Signaling, 34(8), 674–693. https://doi.org/10.1089/ars.2020.8075 Memme, J. M., Erlich, A. T., Phukan, G., & Hood, D. A. (2021). Exercise and mitochondrial health. The Journal of Physiology, 599(3), 803-817. https://doi.org/10.1113/jp278853 Severinsen, M. C. K., & Pedersen, B. K. (2020). Muscle-organ crosstalk: The emerging roles of myokines. Endocrine Reviews, 41(4), 594-609. https://doi.org/10.1210/endrev/bnaa016

Triploid rainbow trout is a hypoxia-sensitive fish species, and is susceptible to death in summer with high water temperature induced acute hypoxia. The study was conducted to evaluate the effect of high protein diet and high carbohydrate diet on hypoxic tolerance of triploid rainbow trout. Two isolipidic and isoenergetic diets with low protein-high carbohydrate level (LPHC) and high protein-low carbohydrate level (HPLC) were specifically formulated. After the feeding trial with 80 days, two group fish were treated with acute hypoxic challenge. Plasma biochemical parameters, hepatic anti-stress, antioxidant and immune related genes expression, and hepatic glucose, lipid, protein and amino acid metabolism related genes expression were then analyzed. The results showed that compared with HPLC diet, LPHC diet could result in excessive plasma levels of alanine aminotransferase (ALT; 36.3 VS 14.0 U/L), aspartate aminotransferase (AST; 978 VS 366 U/L), alkaline phosphatase (ALP; 374 VS 204 U/L), creatine phosphokinase (CPK; 7538 VS 4937 U/L) and lactate dehydrogenase (LDH; 940 VS 451 U/L). In addition, HPLC diet could remodel metabolism of glucose, lipid and protein based on the mRNA expression levels of the genes regulating glycometabolism, lipometabolism, and protein and amino acids metabolism. HPLC diet also enhanced the mRNA expression levels of the genes regulating anti-stress (HSP70, HIF-1a and HIF-2a), antioxidant (Nrf2, SOD, CAT, GPx and HO-1) and immune (IFN-γ, IL-1β, TNF-α and IL-8). In total, LPHC diet could aggravate hypoxic stress of triploid rainbow trout, while HPLC diet could improve fish hypoxic tolerance.

Postharvest losses of fruits and vegetables can occur due to cell breakdown and browning during controlled atmosphere storage as a result of low oxygen (O2) stress. Therefore, the study was designed to better understand the underlying mechanisms of the response of isolated tomato fruit cells incubated at low O2 (hypoxic and anoxic) conditions as a model system. The O2 stress conditions used for the experiment were based on the results of the Michaelis–Menten constant (Km) of respiration. A total of 56 polar metabolites belonging mainly to different functional groups, including amino acids, organic acids, sugars and sugar alcohols, were identified using GC-MS. O2 stress stimulated the biosynthesis of most of the free amino acids while decreasing the synthesis of most of the organic acids (especially those linked to the tricarboxylic acid cycle), sugars (except for ribose) and other nitrogen-containing compounds. The down-regulation of these TCA cycle metabolites served to provide energy to ensure the survival of the cell. Increases in the sugar alcohol levels and induction of fermentative metabolism were observed under low O2 stress. By employing multivariate statistics, metabolites were identified that were essential to the oxygen stress response and establishing the correlation between metabolite abundance, oxygen levels, and incubation period were achievable. A higher correlation was observed between the O2 levels and most of the metabolites.

The aim of this study was to investigate the effects of sodium butyrate (SB) supplementation on growth performance, antioxidant enzyme activities, inflammatory factors, and hypoxic stress in largemouth bass (Micropterus salmoides). Diets were supplemented with different doses of SB at 0 (SB0), 0.5 (SB1), 1.0 (SB2) and 2.0 (SB3) g/kg. The hypoxic stress experiment was performed after 56 days of culture. The results showed that compared with the SB0 group, the final body weight, weight gain rate and protein deposition rate of the SB3 group were significantly increased (P<0.05), while FCR was significantly decreased (P<0.05). The contents of dry matter, crude lipids, and ash in the SB2 group were significantly higher than those in the SB0 group (P<0.05). The urea level was significantly decreased (P<0.05), and the glucose content was significantly increased (P<0.05) in the SB supplement group. Compared with the SB0 group, the SB2 group had significant reductions in the levels of serum triglyceride, cholesterol, elevated-density lipoprotein cholesterol, and low-density lipoprotein (P<0.05), and significant reductions in the levels of liver alkaline phosphatase and malondialdehyde (P<0.05). The total antioxidant capacity of the SB1 group was higher than that of other groups (P<0.05). Compared with the SB0 group, the mRNA expression of TLR22, MyD88, TGF-β1, IL-1β and IL-8 in the SB2 group significantly decreased (P<0.05). The cumulative mortality rate was significantly decreased in the SB2 and SB3 groups in comparison with that in the SB0 group after three hours of hypoxic stress (P<0.05). In a 56-day feeding trial, SB enhanced largemouth bass growth by increasing antioxidant enzyme activity and inhibiting TLR22-MyD88 signaling, therefore increasing cumulative mortality from hypoxic stress in largemouth bass. [ABSTRACT FROM AUTHOR]

Dissolved oxygen (DO) is crucial for fish farming, and when fish experience hypoxic stress, negative effects such as the disruption of normal physiological activities, a decline in aerobic swimming ability, and feeding restriction will occur. In this study, healthy Epinephelus coioides individuals were subjected to hypoxic (DO = 0.6 ± 0.1 mg/L) and reoxygenation treatments (DO = 6.0 ± 0.1 mg/L), with a normoxic group (DO = 6.0 ± 0.1 mg/L) set as the control. Transcriptome sequencing (RNA-seq) was performed on the brains of E. coioides in hypoxia-sensitive (EBW), hypoxia-tolerant (EBS), and normoxic control (CB) groups. In total, 1174 differentially expressed genes (DEGs) were screened from the three groups. KEGG analysis revealed several pathways, including the HIF-1 signaling pathway, and immune-related pathways such as MAPK signaling, microRNAs (miRNAs), and oxidative phosphorylation pathways enriched in the EBS group, and cAMP signaling pathway enriched in the EBW group. Moreover, a variety of significant hypoxia-responsive DEGs involved in energy metabolism and immune reactions were identified in the EBS and EBW groups. qRTPCR analysis showed that the key DEGs HIF-1α, LDH-A, PPARα, PNP, RAB13, DDIT4, TNF-1, and ALDOA were significantly upregulated in the brain tissues of E. coioides under acute hypoxic stress and that their expression returned to normoxic levels after reoxygenation, indicating that they provided energy to the organism and regulated severe damage and lesions appearing in the brains of E. coioides during hypoxic stress to prolong the survival time of the organism. Altogether, these results suggest that hypoxia disrupts the expression patterns of multiple genes in E. coioides and that these genes may participate in resistance and adaptation to hypoxia in the organisms by regulating apoptosis, proliferation, differentiation, and energy metabolism.

Ameloblastoma (AM) is the most common odontogenic tumor. Although it is benign in nature, it generally presents aggressive behavior. In addition to this, resection procedures largely affect the physiological and psychological functions of the patient whereas conservative treatments like enucleation increase the risk of recurrence in the future. The risk for malignant transformation into ameloblastic carcinoma is also high. Therefore, a better understanding of different pathological pathways for AM is crucial. Among all the pathways, the hypoxic pathway plays a major role as the increased peripheral cell proliferation reduces the blood supply to the central cells leading to hypoxic stress. This stress triggers the key transcription gene which is necessary for the adaption to this microenvironment. This key gene upregulates various other proteins, all of them having different mechanisms from each other. Hypoxic stress does not initiate cellular proliferation, but it is a necessary adaptive pathway that is vital for future proliferation. Hence, it is necessary to understand the expressions of all the genes involved in this adaptive process so that in the future a gene-targeted therapy can be designed. This will lead to a decrease in the risk for malignant transformation as well as recurrent behavior of AM. [ABSTRACT FROM AUTHOR]

• In the sealed bottles, the dissolved oxygen content slowly decreased from 5.6 mg/L to 1.8 mg/L. • No M. mutica died until six hours of hypoxia stress, and all died by the 8th hour. • Inflammation and apoptosis in the lungs was observed after hypoxia stress. • 38,981 genes and 1566 differentially expressed genes were obtained after hypoxia stress. • The DEGs were enriched in the inflammation, apoptosis, sugar transport, fructose and mannose metabolism. Mauremys mutica is a widely cultured pond turtle in China that can hold its breath underwater for up to 7 h. However, the adaptive mechanism of this hypoxia-resistant phenotype remains unknown. In the present study, no M. mutica died until 6 h of hypoxic stress. Inflammation was observed in the lungs of dead individuals along with a lung cell apoptosis rate of 12.3% in the death group, which was about six times that of the survival group. Transcriptome sequencing produced 379,659,748 clean reads, and 38,981 genes were obtained. A total of 1566, 1555 and 756 differentially expressed genes (DEGs) were detected between the survival group and the death group, the survival group and the control group, and the death group and the control group, respectively. And the DEGs were enriched in the inflammation, apoptosis, sugar transport, antioxidant , fructose, and mannose metabolism, arginine and proline metabolism, glycosaminoglycan biosynthesis, P53, and MAPK signaling pathways. This study offers new insight into the molecular mechanisms occurring in the lungs of M. mutica during acute hypoxia, which may facilitate genetic selection for hypoxia-resistant lines in M. mutica. [ABSTRACT FROM AUTHOR]

Hypoxia, a common cause of programmed cell death or apoptosis, represents a neuropathological process. Although certain response proteins to hypoxic stress and their effects on cell status and fate have been identified, the real-time quantification of smaller neurochemicals to understand pathogenic mechanism in live rat brain during such stress remains unexplored. In this study, by employing a cutting-edge electrochemical tool developed with carbon nanotube-sheathed carbon fiber microelectrode that offers remarkable selectivity and temporal/spatial resolution for monitoring ascorbate, we observed a substantial efflux of ascorbate in response to hypoxic stress in live rat brain. Furthermore, using a small molecule compound as channel inhibitor to investigate the behavior of ascorbate efflux, we found that this efflux is closely correlated with N -methyl- D -aspartic acid receptor-induced neuronal excitability. Notably, antagonistic actions on volume-sensitive anion channel can suppress ascorbate efflux evoked by hypoxic stress, further revealing that ascorbate fluctuation is volume-sensitive anion channel-dependent. This research not only facilitates a greater understanding of the neurochemical mechanism in hypoxia but also uncovers a potential biomarker for future closed-loop therapies. [Display omitted] • Employing advanced ascorbate sensing technology offering high in vivo selectivity, a significant efflux of ascorbate was captured in response to acute hypoxic stress in live rat brain. • The ascorbate efflux is initiated by the NMDA receptor-mediated neuronal excitotoxicity. • Ascorbate fluctuation is volume-sensitive anion channel-dependent. [ABSTRACT FROM AUTHOR]

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Objective. To evaluate the effect on biological, nutritional, and hematoimmune indicators of juvenile Cherax quadricarinatus were cultivated and fed with a probiotic mixture. Materials and methods. A completely randomized design (DCA) with six treatments: 0 (control), 1×102 µL, 2×102 µL, 3×102 µL, 4×102 µL and 5×102 µL of a probiotic mixture (Bacterol Shrimp Forte), with three repetitions each, 18 experimental tanks of diameter 1.7 m and area of 2.26 m2 were used, with a density of 20 juveniles (0.95 ± 0.10g and 7.78 ± 0.77mm) per tank for 60 days. Biological (weight, length, weight gain, weight increase, specific growth rate, length gain, length increase and survival), nutritional (feed conversion, feed efficiency and protein efficiency rate) and hematoimmune (total of hemocytes, differential hemocytes, phagocytic rate, superoxide dismutase and hypoxic stress) parameters were measured. Results. For biological indicators, the best results (p<0.05) were obtained when using 4×102 µL of the probiotic (final weight: 9.11 g; final length: 68.95 mm; specific growth rate: 3.74). Regarding the nutritional parameters, the best results were found with for 3×102 µL (feed conversion: 1.09, feed efficiency: 0.91, and protein efficiency: 2.61); although there were no differences between 3×102 and 4×102 µL. For the hematoimmune response, there were differences (p<0.05) for all the indicators under study, with a better performance for 4×102 µL of the probiotic mixture. Conclusions. The probiotic mixture induces the hematoimmune, biological, and nutritional response with the best response for concentrations of 3×102 µL, 4×102 µL. [ABSTRACT FROM AUTHOR]

Postharvest management of cabbage relies on high-intensity cooling to control postharvest physiology, minimising quality loss despite incurring significant energy and environmental costs. As an alternative, we hypothesised that controlled atmosphere (CA) could allow increased storage temperature by supporting physiological regulation, while maintaining quality and reducing energy demand. This study examined the effect CA (1.5 kPa CO 2 and 6 kPa O 2) at 5 or 10 °C on cabbage quality, with the aim of proposing a more sustainable and resilient supply chain. CA treatment was effective at reducing head respiration at higher temperature, with CA/10 °C treatment achieving lower respiration rates than Control/5 °C. Improved head colour retention and maintenance of stump quality were observed in cabbage under CA conditions. CA effects were seen also at a regulatory level; CA promoted an average of 25.4% reduction in abscisic acid accumulation potentially as part of a wider hypoxia stress response and was successful in decreasing expression of the senescence-coordinating transcription factor BoORE15. This finding was linked with a lower in downstream expression of pheophytinase and subtilisin protease. These results demonstrated that CA treatment fundamentally modified postharvest physiology in cabbage, which can be exploited to enable storage at warmer temperatures, contributing to supply chains with lower energy demand and its associated environmental benefits. • CA treatment can reduce cabbage respiration rate more than temperature alone. • CA delays senescence and adventitious root development. • Hypoxia impacts hormones, mainly abscisic acid accumulation maintaining quality. • CA reduces expression of regulatory promotors of senescence such as the BoORE15. • CA delays BoPPH expression at 10 °C implying regulatory chlorophyll reduction in air. [ABSTRACT FROM AUTHOR]

To cope with hypoxic stress, ancient organisms have developed evolutionally conserved programs centered on hypoxia-inducible transcriptional factors (HIFs). HIFs and their regulatory proteins have evolved as rheostats to adapt cellular metabolism to atmospheric oxygen fluctuations, but the amplitude of their transcriptional programs has tremendously increased along evolution to include a wide spectrum of physiological and pathological processes. The bone marrow represents a notable example of an organ that is physiologically exposed to low oxygen levels and where basal activation of hypoxia signaling appears to be intrinsically wired within normal and neoplastic hematopoietic cells. HIF-mediated responses are mainly piloted by the oxygen-labile a subunits HIF1a and HIF2a, and current literature suggests that these genes have a functional specification that remains to be fully defined. Since their identification in the mid 90s, HIF factors have been extensively studied in solid tumors, while their implication in leukemia has lagged behind. In the last decades however, many laboratories have addressed the function of hypoxia signaling in leukemia and obtained somewhat contradictory results. Suppression of HIFs expression in different types of leukemia has unveiled common leukemia-promoting functions such as stimulation of bone marrow neoangiogenesis, maintenance of leukemia stem cells and chemoresistance. However, genetic studies are revealing that a definition of HIF factors as bona fide tumor promoters is overly simplistic, and, depending on the leukemia subtype, the specific oncogenic event, or the stage of leukemia development, activation of hypoxia-inducible genes may lead to opposite consequences. With this article we will provide an updated summary of the studies describing the regulation and function of HIF1a and HIF2a in blood malignancies, spanning from acute to chronic, lymphoid to myeloid leukemias. In discussing these data, we will attempt to provide plausible explanations to contradictory findings and point at what we believe are areas of weakness in which further investigations are urgently needed. Gaining additional knowledge into the role of hypoxia signaling in leukemia appears especially timely nowadays, as new inhibitors of HIF factors are entering the clinical arena for specific types of solid tumors but their utility for patients with leukemia is yet to be determined. [ABSTRACT FROM AUTHOR]

Microcystin-LR (MC-LR) is widely present in waters around the world, but its potential toxic effects and mechanisms on amphibian gills remain unknown. In the present study, tadpoles (Lithobates catesbeianus) were exposed to environmentally realistic concentrations of 0.5, 2 μg/L MC-LR, and 0 μg/L MC-LR (Control) for 30 days with the objective to unveil the impairment of gill health. The lysozyme was downregulated, while pattern recognition receptors and complement and adaptive immune processes were upregulated and the ability of gill supernatant to inhibit pathogenic bacteria decreased in the 0.5 and 2 μg/L MC-LR groups. The transcriptions of epithelial barrier components (e.g., CLDN1) were significantly decreased in MC-LR-exposed gills, while the gill content of lipopolysaccharide (LPS) endotoxins and the transcriptions of downstream responsive genes (e.g., TLR4 and NF-κB) were concurrently increased. In addition, the number of eosinophils and the expression of pro-inflammatory cytokines (e.g., IL-1β and TNF-α) were increased. These results imply that exposure of tadpoles to low environmentally concentrations of MC-LR leads to inflammation, increased permeability, and a reduced ability to inhibit pathogenic bacteria. The epithelial cells of inner gill filaments increased and transcriptions of hypoxic stress genes (e.g., HIF-1α, FLT1, and SERPINE1) were upregulated within the exposed group. As a consequence, exposure to MC-LR may lead to hypoxic stress. MC-LR exposure also drove gill microbiota to a dysbiosis. The relative abundance of Elizabethkingia was positively correlated with content of LPS and transcriptions of NF-κB and TNF-α. Overall, this study presents the first evidence about the pronounced impacts of MC-LR exposure on gills of amphibians, highlighting the susceptibility of early developing tadpoles to the environmental risks of MC-LR. [ABSTRACT FROM AUTHOR]

To cope with hypoxic stress, ancient organisms have developed evolutionally conserved programs centered on hypoxia-inducible transcriptional factors (HIFs). HIFs and their regulatory proteins have evolved as rheostats to adapt cellular metabolism to atmospheric oxygen fluctuations, but the amplitude of their transcriptional programs has tremendously increased along evolution to include a wide spectrum of physiological and pathological processes. The bone marrow represents a notable example of an organ that is physiologically exposed to low oxygen levels and where basal activation of hypoxia signaling appears to be intrinsically wired within normal and neoplastic hematopoietic cells. HIF-mediated responses are mainly piloted by the oxygen-labile α subunits HIF1α and HIF2α, and current literature suggests that these genes have a functional specification that remains to be fully defined. Since their identification in the mid 90s, HIF factors have been extensively studied in solid tumors, while their implication in leukemia has lagged behind. In the last decades however, many laboratories have addressed the function of hypoxia signaling in leukemia and obtained somewhat contradictory results. Suppression of HIFs expression in different types of leukemia has unveiled common leukemia-promoting functions such as stimulation of bone marrow neoangiogenesis, maintenance of leukemia stem cells and chemoresistance. However, genetic studies are revealing that a definition of HIF factors as bona fide tumor promoters is overly simplistic, and, depending on the leukemia subtype, the specific oncogenic event, or the stage of leukemia development, activation of hypoxia-inducible genes may lead to opposite consequences. With this article we will provide an updated summary of the studies describing the regulation and function of HIF1α and HIF2α in blood malignancies, spanning from acute to chronic, lymphoid to myeloid leukemias. In discussing these data, we will attempt to provide plausible explanations to contradictory findings and point at what we believe are areas of weakness in which further investigations are urgently needed. Gaining additional knowledge into the role of hypoxia signaling in leukemia appears especially timely nowadays, as new inhibitors of HIF factors are entering the clinical arena for specific types of solid tumors but their utility for patients with leukemia is yet to be determined.

Hypoxia is a known stress factor in mammals and has been shown to potentially impair male fertility, which manifests as spermatogenic dysfunction and decreased semen quality. Studies have shown that RNA modifications, the novel post-transcriptional regulators, are involved in spermatogenesis, and hypoxia-induced alterations in RNA modification in testes and sperm cells may be associated with impaired spermatogenesis in mice. However, the molecular mechanisms via which RNA modifications influence spermatogenesis under hypoxic stress conditions are unclear. In this study, we generated a mouse Germ Cell-2 spermatid (GC-2spd) hypoxia model by culturing cells in a 1% O2 incubator for 48 h or treating them with CoCl2 for 24 h. The hypoxia treatment significantly inhibited proliferation and induced apoptosis in GC-2spd cells. The RNA modification signatures of total RNAs (2 types) and differentially sized RNA fragments (7 types of approximately 80 nt-sized tRNAs; 9 types of 17–50 nt-sized sncRNAs) were altered, and tRNA stability was partially affected. Moreover, the expression profiles of sncRNAs, such as microRNAs, tsRNAs, rsRNAs, and ysRNAs, were significantly regulated, and this might be related to the alterations in RNA modification and subsequent transcriptomic changes. We comprehensively analyzed alterations in RNA modification signatures in total RNAs, tRNAs (approximately 80 nt), and small RNAs (17–50 nt) as well as the expression profiles of sncRNAs and transcriptomes in hypoxia-treated GC-2spd cells; our data suggested that RNA modifications may be involved in cellular responses under hypoxic stress conditions and could provide a basis for a better understanding of the molecular mechanisms underlying male infertility.

Barley (Hordeum vulgare L.) is the most susceptible cereal species to excess moisture stress. Waterlogging-induced hypoxia causes major morphological, physiological, and metabolic changes, some of which are regulated by the action of plant growth regulators and signal molecules including nitric oxide. Recent studies have evidenced the participation of phytoglobins in attenuating hypoxic stress during conditions of excessive moisture through their ability to scavenge nitric oxide and influence the synthesis and response of growth regulators. This review will highlight major cellular changes linked to plant responses to waterlogging stress with emphasis on phytoglobins. [ABSTRACT FROM AUTHOR]

Abstract Background Abscisic acid (ABA) and proline play important roles in rice acclimation to different stress conditions. To study whether cross-talk exists between ABA and proline, their roles in rice acclimation to hypoxia, rice growth, root oxidative damage and endogenous ABA and proline accumulation were investigated in two different rice genotypes (‘Nipponbare’ (Nip) and ‘Upland 502’ (U502)). Results Compared with U502 seedlings, Nip seedlings were highly tolerant to hypoxic stress, with increased plant biomass and leaf photosynthesis and decreased root oxidative damage. Hypoxia significantly stimulated the accumulation of proline and ABA in the roots of both cultivars, with a higher ABA level observed in Nip than in U502, whereas the proline levels showed no significant difference in the two cultivars. The time course variation showed that the root ABA and proline contents under hypoxia increased 1.5- and 1.2-fold in Nip, and 2.2- and 0.7-fold in U502, respectively, within the 1 d of hypoxic stress, but peak ABA production (1 d) occurred before proline accumulation (5 d) in both cultivars. Treatment with an ABA synthesis inhibitor (norflurazon, Norf) inhibited proline synthesis and simultaneously aggravated hypoxia-induced oxidative damage in the roots of both cultivars, but these effects were reversed by exogenous ABA application. Hypoxia plus Norf treatment also induced an increase in glutamate (the main precursor of proline). This indicates that proline accumulation is regulated by ABA-dependent signals under hypoxic stress. Moreover, genes involved in proline metabolism were differentially expressed between the two genotypes, with expression mediated by ABA under hypoxic stress. In Nip, hypoxia-induced proline accumulation in roots was attributed to the upregulation of OsP5CS2 and downregulation of OsProDH, whereas upregulation of OsP5CS1 combined with downregulation of OsProDH enhanced the proline level in U502. Conclusion These results suggest that the high tolerance of the Nip cultivar is related to the high ABA level and ABA-mediated antioxidant capacity in roots. ABA acts upstream of proline accumulation by regulating the expression of genes encoding the key enzymes in proline biosynthesis, which also partly improves rice acclimation to hypoxic stress. However, other signaling pathways enhancing tolerance to hypoxia in the Nip cultivar still need to be elucidated.

The plant mitochondrial electron transport chain influences carbon and nitrogen metabolism under near anoxic conditions through its involvement in the phytoglobin-nitric oxide cycle, where the respiratory chain reduces nitrite to nitric oxide (NO), followed by NO conversion to nitrate by class 1 phytoglobin. Wild type (WT) and transgenic tobacco (Nicotiana tabacum L.) with differing amounts of alternative oxidase (AOX) were used to manipulate NO generation under hypoxia, and to examine whether this in turn influenced the gene expression of two stress-related amino acid biosynthetic pathways, the plastid-localized phosphorylated pathway of serine biosynthesis (PPSB), and the γ-aminobutyric acid (GABA) shunt. Under hypoxia, leaf NO emission rate was highest in AOX overexpressors and lowest in AOX knockdowns, with WT showing an intermediate rate. In turn, the rate of NO emission correlated with the degree to which amino acids accumulated. This amino acid accumulation was associated with the increased expression of the enzymes of the stress-related amino acid biosynthetic pathways. However, induction of the PPSB occurred much earlier than the GABA shunt. This work shows that high rates of NO turnover associate with rapid gene induction of the PPSB, establishing a clear link between this pathway and the maintenance of carbon, nitrogen and energy metabolism under hypoxia.

The plant mitochondrial electron transport chain influences carbon and nitrogen metabolism under near anoxic conditions through its involvement in the phytoglobin-nitric oxide cycle, where the respiratory chain reduces nitrite to nitric oxide (NO), followed by NO conversion to nitrate by class 1 phytoglobin. Wild type (WT) and transgenic tobacco (Nicotiana tabacum L.) with differing amounts of alternative oxidase (AOX) were used to manipulate NO generation under hypoxia, and to examine whether this in turn influenced the gene expression of two stress-related amino acid biosynthetic pathways, the plastid-localized phosphorylated pathway of serine biosynthesis (PPSB), and the γ-aminobutyric acid (GABA) shunt. Under hypoxia, leaf NO emission rate was highest in AOX overexpressors and lowest in AOX knockdowns, with WT showing an intermediate rate. In turn, the rate of NO emission correlated with the degree to which amino acids accumulated. This amino acid accumulation was associated with the increased expression of the enzymes of the stress-related amino acid biosynthetic pathways. However, induction of the PPSB occurred much earlier than the GABA shunt. This work shows that high rates of NO turnover associate with rapid gene induction of the PPSB, establishing a clear link between this pathway and the maintenance of carbon, nitrogen and energy metabolism under hypoxia. [ABSTRACT FROM AUTHOR]

Fish gills are the primary organ that respond to sudden changes in the dissolved oxygen (DO) level in the aquatic environment. Hypoxic stress impairs the normal function of gill tissues. However, little is known about the mechanisms of the response of yellow catfish gills to hypoxic stress. In this study, we compared transcriptomic and physiological changes in gill tissues of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) between a hypoxia-treated group (DO: 1.5 mg/L) and a control group (DO: 6.5 mg/L). In fish in the hypoxia-treated group, gill filaments underwent adaptive changes, and the number of vacuoles in gill tissues increased. Exposure to hypoxic conditions for 96 h resulted in increased anaerobic metabolism and decreased antioxidant and immune capacity in gill tissues. Transcriptome analyses revealed 1556 differentially expressed genes, including 316 up-regulated and 1240 down-regulated genes, between fish in the hypoxia-treated and control groups. Functional analyses indicated that the main pathway enriched with differentially expressed genes was immune response, followed by energy metabolism and signal transduction. Under hypoxic stress, the transcript levels of genes involved in the NOD-like receptor signaling pathway initially increased rapidly but then decreased over time, suggesting that the NOD-like receptor-mediated immune response plays an essential role in hypoxia tolerance and resistance in hybrid yellow catfish. Our results provide novel insights into which immune-related genes and pathways are activated under hypoxic stress, and reveal details of early adaptation of the immune response and defense mechanisms under hypoxic stress. • Hypoxia changed gill structure and reduced gill antioxidant and immune capacity. • RNA-Seq analyses revealed activation of immune response under hypoxic stress. • NLR signing may play a crucial role in the hypoxia-induced immune response. [ABSTRACT FROM AUTHOR]

Protein arginine methyltransferases (PRMTs) are a family of enzymes involved in gene regulation and protein/histone modifications. PRMT8 is primarily expressed in the central nervous system, specifically within the cellular membrane and synaptic vesicles. Recently, PRMT8 has been described to play key roles in neuronal signaling such as a regulator of dendritic arborization, synaptic function and maturation, and neuronal differentiation and plasticity. Here, we examined the role of PRMT8 in response to hypoxia‐induced stress in brain metabolism. Our results from liquid chromatography mass spectrometry, mitochondrial oxygen consumption rate, and protein analyses indicate that PRMT8(−/−) knockout mice presented with altered membrane phospholipid composition, decreased mitochondrial stress capacity, and increased neuroinflammatory markers, such as tumor necrosis factor alpha and ionized calcium binding adaptor molecule 1 (Iba1, a specific marker for microglia/macrophage activation) after hypoxic stress. Furthermore, adenovirus‐based overexpression of PRMT8 reversed the changes in membrane phospholipid composition, mitochondrial stress capacity, and neuroinflammatory markers. Together, our findings establish PRMT8 as an important regulatory component of membrane phospholipid composition, short‐term memory function, mitochondrial function, and neuroinflammation in response to hypoxic stress. [ABSTRACT FROM AUTHOR]

Objective: Amyotrophic lateral sclerosis (ALS) is a progressive and fatal motor neuron disease. Hypoxic stress is suspected as the pathogenesis of ALS, however, no positron emission tomography (PET) study for hypoxic stress has been conducted in the spinal cord of ALS patients. Methods: In the present study, we examined cervical spinal hypoxic stress of nineALS patients with upper extremity (U/E) atrophy by18F-fluoromisonidazole (FMISO) PET. Results: On the ipsilateral side of C1 and C5 levels, 18F-FMISO uptake increased significantly compared with the contralateral side (*p < 0.05) and the control subject (**p < 0.01). In addition, a strong correlation was found between 18F-FMISO uptake of the C5 level and the rate of progression of the ALS FRS-R score (R = 0.781, *p = 0.013). Conclusion: These results indicate that hypoxic stress increased in the spinal cord of ALS patients with a close link to ALS progression. Both hypoxic stress and a compromised response to hypoxia, which may lead to subsequent motor neuron death, could be a potential therapeutic target for ALS. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to determine the prenatal causes of slight lateral ventricular enlargement in healthy infants.Methods: We examined 1089 healthy infants who weighed at least 2000 g and were born at a gestational age of at least 36 weeks. We assessed the presence of ventricular enlargement when an apparent space was observed in the frontal horn or body of the lateral ventricle of the brain by a transfontanel ultrasound scan. We investigated the relationships between slight lateral ventricular enlargement and various prenatal factors.Results: Slight lateral ventricular enlargement was observed in 497 (45.6%) infants. Slight lateral ventricular enlargement was related to maternal anemia (p = .004; odds ratio = 1.630; 95% CI: 1.168-2.276), threatened premature labor (p = .010; odds ratio = 1.441; 95% CI: 1.093-1.900), and diabetes mellitus (p = .022; odds ratio = 2.020; 95% CI: 1.109-3.682) using multiple logistic regression analysis. The birth weight of the infants with slight lateral ventricular enlargement was heavier than that of those without ventricular enlargement at 36-40 weeks of gestation. Forty infants with ventricular enlargement had head circumferences greater than the 90th percentile, while only one infant without ventricular enlargement did (p < .001). In addition, 22 infants with ventricular enlargement had head circumferences less than the 10th percentile, while only 4 infants without ventricular enlargement did (p < .001). In 497 infants with ventricular enlargement, the numbers of infants with left side dominant, equivalent, and right side dominant ventricular enlargement were 289 (58.1%), 110 (22.1), and 98 (19.7%), respectively.Conclusions: Slight lateral ventricular enlargement could be caused by several pathological conditions in utero, including brain atrophy, ventricular enlargement, the influence of blood flow in the brain, and various pathological changes in different brain regions. [ABSTRACT FROM AUTHOR]

• Naringenin (NG) prevented hypoxic stress-induced behavioral impairments. • NG inhibited hypoxic stress-induced oxidative stress. • NG inhibited hypoxic stress-induced up-regulation of inflammatory proteins. • NG attenuated hypoxic stress-induced neuronal degeneration. • NG increased BDNF expression in hypoxic mice brain. Oxidative and inflammatory signaling pathways have been identified as important targets for mitigating hypoxic stress-induced neurological complications. Thus, the effects of naringenin, a potent antioxidant, anti-inflammatory and neuroprotective bioflavonoid on hypoxic stress-induced depressive-like and anxiety-related behaviors in mice, and the underlying molecular mechanisms were evaluated in this study. Thirty-five male Swiss mice were distributed into 5 groups (n = 7). Mice in group I (non-stress control) and group 2 (stress-control) both had vehicle (5 % DMSO), while groups 3–5 received naringenin (10, 25 and 50 mg/kg), intraperitonally. Thirty minutes later, mice in groups 2–5 were subjected to 15 min hypoxic stress, daily for 14 days. Locomotor activity, anxiety and depression were evaluated on day 15. The mice brains were processed for malondialdehyde, glutathione, superoxide-dismutase (SOD), catalase, tumor necrosis factor-alpha (TNF-α) and interleukin-1β assays. The serum corticosterone concentration and expressions of the brain immunopositive cells of inducible nitric oxide synthase (iNOS), nuclear factor kappa-B (NF-kB) and brain derived neurotrophic factor (BDNF) as well as histomorphological changes of the amygdala were also determined. Naringenin (25−50 mg/kg) ameliorated the hypolocomotion, depressive- and anxiety-like behaviors in hypoxic mice. The increased brain contents of malondialdehyde, TNF-α, interleukin-1β, and decreased antioxidant (glutathione and SOD) status were attenuated by naringenin. Naringenin (10 mg/kg) increases BDNF expression but did not significantly (p < 0.05) alter corticosterone and catalase contents. The increased expressions of iNOS and NF-kB as well as loss of amygdala neuronal cells were reduced by naringenin (10 mg/kg). Overall, these findings suggest that naringenin improves depressive- and anxiety-like behaviors in mice exposed to hypoxic stress by modulating oxido-inflammatory insults and NF-kB/BDNF expressions. [ABSTRACT FROM AUTHOR]

Background: Under hypoxia, exaggerated compensatory responses may lead to acute mountain sickness. The excessive vasodilatory effect of nitric oxide (NO) can lower the hypoxic pulmonary vasoconstriction (HPV) and peripheral blood pressure. While NO is catalyzed by various nitric oxide synthase (NOS) isoforms, the regulatory roles of these types in the hemodynamics of pulmonary and systemic circulation in living hypoxic animals remain unclear. Therefore, this study aims to investigate the regulatory effects of different NOS isoforms on pulmonary and systemic circulation in hypoxic rats by employing selective NOS inhibitors and continuously monitoring hemodynamic parameters of both pulmonary and systemic circulation., Methods: Forty healthy male Sprague-Dawley (SD) rats were randomly divided into four groups: Control group (N G -nitro-D-arginine methyl ester, D-NAME), L-NAME group (non-selective NOS inhibitor, N G -nitro-L-arginine methyl ester), AG group (inducible NOS inhibitor group, aminoguanidine), and 7-NI group (neurological NOS inhibitor, 7-nitroindazole). Hemodynamic parameters of rats were monitored for 10 min after inhibitor administration and 5 min after induction of hypoxia [15% O 2 , 2200 m a. sl., 582 mmHg (76.5 kPa), Xining, China] using the real-time dynamic monitoring model for pulmonary and systemic circulation hemodynamics in vivo. Serum NO concentrations and blood gas analysis were measured., Results: Under normoxia, mean arterial pressure and total peripheral vascular resistance were increased, and ascending aortic blood flow and serum NO concentration were decreased in the L-NAME and AG groups. During hypoxia, pulmonary arterial pressure and pulmonary vascular resistance were significantly increased in the L-NAME and AG groups., Conclusions: This compensatory mechanism activated by inducible NOS and endothelial NOS effectively counteracts the pulmonary hemodynamic changes induced by hypoxic stress. It plays a crucial role in alleviating hypoxia-induced pulmonary arterial hypertension., (© 2024 The Author(s). Animal Models and Experimental Medicine published by John Wiley & Sons Australia, Ltd on behalf of The Chinese Association for Laboratory Animal Sciences.)

Abstract Background Waterlogging is one of the main abiotic stresses that limit wheat production. Quantitative proteomics analysis has been applied in the study of crop abiotic stress as an effective way in recent years (e.g. salt stress, drought stress, heat stress and waterlogging stress). However, only a few proteins related to primary metabolism and signal transduction, such as UDP - glucose dehydrogenase, UGP, beta glucosidases, were reported to response to waterlogging stress in wheat. The differentially expressed proteins between genotypes of wheat in response to waterlogging are less-defined. In this study, two wheat genotypes, one is sensitive to waterlogging stress (Seri M82, named as S) and the other is tolerant to waterlogging (CIGM90.863, named as T), were compared in seedling roots under hypoxia conditions to evaluate the different responses at proteomic level. Results A total of 4560 proteins were identified and the number of differentially expressed proteins (DEPs) were 361, 640, 788 in S and 33, 207, 279 in T in 1, 2, 3 days, respectively. These DEPs included 270 common proteins, 681 S-specific and 50 T-specific proteins, most of which were misc., protein processing, DNA and RNA processing, amino acid metabolism and stress related proteins induced by hypoxia. Some specific proteins related to waterlogging stress, including acid phosphatase, oxidant protective enzyme, S-adenosylmethionine synthetase 1, were significantly different between S and T. A total of 20 representative genes encoding DEPs, including 7 shared DEPs and 13 cultivar-specific DEPs, were selected for further RT-qPCR analysis. Fourteen genes showed consistent dynamic expression patterns at mRNA and protein levels. Conclusions Proteins involved in primary metabolisms and protein processing were inclined to be affected under hypoxia stress. The negative effects were more severe in the sensitive genotype. The expression patterns of some specific proteins, such as alcohol dehydrogenases and S-adenosylmethionine synthetase 1, could be applied as indexes for improving the waterlogging tolerance in wheat. Some specific proteins identified in this study will facilitate the subsequent protein function validation and biomarker development.

Abstract Background Plants often suffer from hypoxic stress during waterlogging and hydroponic culturing. This study investigated the response of cucumber (Cucumis sativus L.) plant growth parameters, leaf photosynthesis, chlorophyll fluorescence, fast chlorophyll a fluorescence transient (OJIP), and fruit quality parameters to hypoxic stress alleviated by exogenous calcium. During the fruiting period, cucumber plants were exposed to hypoxia and hypoxia + Ca2+ treatment (4 mM Ca2+) for 9 d. Result Exogenous calcium application enhanced the biomass and fruit quality of hypoxic stressed cucumber and also increased the net photosynthesis rate, stomatal conductance, intercellular CO2 concentration, maximum quantum efficiency of photosystem II photochemistry, actual photochemical efficiency of PSII, photochemical quenching coefficient, and non-photochemical quenching coefficient. Additionally, measurement of chlorophyll a fluorescence transients showed the positive K- and L-bands were more pronounced in leaves treated with hypoxia compared with those with hypoxia + Ca2+, indicating that hypoxic treatment induced uncoupling of the oxygen-evolving complex and inhibited electron transport beyond plastoquinone pool (Qa, Qb) including possible constraints on the reduction of end electron acceptors of photosystem I. Exogenous calcium can reduce these stress-induced damages in cucumber. Conclusion This research focused the effect of exogenous calcium on cucumber photosynthesis during the fruiting period under hypoxic stress. Hypoxic stress might impair the photosynthetic electron-transport chain from the donor side of PSII up to the reduction of end acceptors of PSI, and exogenous calcium enhanced electron transport capacity and reduced hypoxic damage of cucumber leaves.

Plants are aerobic organisms that have evolved to maintain specific requirements for oxygen (O2), leading to a correct respiratory energy supply during growth and development. There are certain plant developmental cues and biotic or abiotic stress responses where O2 is scarce. This O2 deprivation known as hypoxia may occur in hypoxic niches of plant-specific tissues and during adverse environmental cues such as pathogen attack and flooding. In general, plants respond to hypoxia through a complex reprogramming of their molecular activities with the aim of reducing the impact of stress on their physiological and cellular homeostasis. This review focuses on the fine-tuned regulation of hypoxia triggered by a network of gaseous compounds that includes O2, ethylene, and nitric oxide. In view of recent scientific advances, we summarize the molecular mechanisms mediated by phytoglobins and by the N-degron proteolytic pathway, focusing on embryogenesis, seed imbibition, and germination, and also specific structures, most notably root apical and shoot apical meristems. In addition, those biotic and abiotic stresses that comprise hypoxia are also highlighted. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate hematological, biochemical, and gasometric parameters of tambaqui juveniles (Colossoma macropomum) exposed to hypoxia and subsequent recovery. Six animals were subjected to normoxia (basal) treatment with dissolved oxygen (DO) 6.27 ± 0.42 mg L−1. Water flow and aeration were reduced for 3 days (hypoxia), during which DO was 0.92 ± 0.37 mg L−1. Water flow and aeration were then reestablished with DO remaining similar to basal. The treatments were as follows: normoxia (basal); 24 h after initiating hypoxia (24H); 72 h after initiating hypoxia (72H); 24 h after reestablishing normoxia (24R); 48 h after reestablishing normoxia (48R); and 96 after reestablishing normoxia (96R). The highest glucose level was recorded at 24H (P < 0.05); the highest lactate level was at 72R; and the highest blood pH was at 24H and 72H (P < 0.05). The highest concentration of PvCO2 was at 24H (P < 0.05), while at 96R it was equivalent to basal (P > 0.05). The variable PvO2 was only higher than basal at 24R (P < 0.05). Juvenile C. macropomum managed to reestablish the main stress indicators (glucose and lactate) at 96R, while the other indicators varied during the study, with homeostatic physiology being reestablished during the recovery period. [ABSTRACT FROM AUTHOR]

Hypoxia stress may affect the fish intestine and thereby threaten the growth and survival of the fish. Teprenone is a clinically effective agent in protecting gastrointestinal mucosa. This study aims to assess the effect of teprenone in the intestine of Chinese sea bass Lateolabrax maculatus under intermittent hypoxic stress. L. maculatus juveniles were either raised under intermittent hypoxic condition or normal condition (NC). Part of the hypoxic-intervened fish were treated with teprenone at different concentrations (HTs), and the rest were regarded as hypoxic control (HC). Histological analysis was performed on the epithelial tissue of the fish intestine. High-throughput sequencing technology was used to analyze the diversity and composition of the microbial community in L. maculatus intestine. Reduced villi length and goblet cell, exfoliated enterocyte, and improper arrangement of villi were observed in HC compared with NC and HTs. Proteobacteria, Firmicutes, and Bacteroidetes represented the most abundant phyla in each sample. Significantly higher microbial diversity was detected in HC compared with NC (P < 0.05). At the phylum level, HC presented significantly decreased relative abundance of Proteobacteria, and significantly increased relative abundance of Bacteroidetes, Chloroflex, and Cyanobacteria compared with NC (P < 0.05). At the class level, HC showed significantly reduced relative abundance of Alphaproteobacteria and Bacilli, and significantly increased relative abundance of Clostridia, Gammaproteobacteria, and Bacteroides (P < 0.05). Teprenone protects the intestine from epithelial damages and maintains the microbial harmony in L. maculatus under intermittent hypoxic stress. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of this study?The acute hypoxic compensatory reaction is based on haemodynamic changes, and β‐adrenoceptors are involved in haemodynamic regulation. What is the role of β‐adrenoceptors in haemodynamics during hypoxic exposure?What is the main finding and its importance?Activation of β2‐adrenoceptors attenuates the increase in pulmonary artery pressure during hypoxic exposure. This compensatory reaction activated by β2‐adrenoceptors during hypoxic stress is very important to maintain the activities of normal life. The acute hypoxic compensatory reaction is accompanied by haemodynamic changes. We monitored the haemodynamic changes in rats undergoing acute hypoxic stress and applied antagonists of β‐adrenoceptor (β‐ARs) subtypes to reveal the regulatory role of β‐ARs on haemodynamics. Sprague–Dawley rats were randomly divided into control, atenolol (β1‐AR antagonist), ICI 118,551 (β2‐AR antagonist) and propranolol (non‐selective β‐AR antagonist) groups. Rats were continuously recorded for changes in haemodynamic indexes for 10 min after administration. Then, a hypoxic ventilation experiment [15% O2, 2200 m a.sl., 582 mmHg (0.765 Pa), PO2 87.3 mmHg; Xining, China] was conducted, and the indexes were monitored for 5 min after induction of hypoxia. Plasma catecholamine concentrations were also measured. We found that, during normoxia, the mean arterial pressure, heart rate, ascending aortic blood flow and pulmonary artery pressure were reduced in the propranolol and atenolol groups. Catecholamine concentrations were increased significantly in the atenolol group compared with the control group. During hypoxia, mean arterial pressure and total peripheral resistance were decreased in the control, propranolol and ICI 118,551 groups. Pulmonary arterial pressure and pulmonary vascular resistance were increased in the propranolol and ICI 118,551 groups. During hypoxia, catecholamine concentrations were increased significantly in the control group, but decreased in β‐AR antagonist groups. In conclusion, the β2‐AR is involved in regulation of pulmonary haemodynamics in the acute hypoxic compensatory reaction, and the activation of β2‐ARs attenuates the increase in pulmonary arterial pressure during hypoxic stress. This compensatory reaction activated by β2‐ARs during hypoxic stress is very important to maintain activities of normal life. [ABSTRACT FROM AUTHOR]

Background: Abscisic acid (ABA) and proline play important roles in rice acclimation to different stress conditions. To study whether cross-talk exists between ABA and proline, their roles in rice acclimation to hypoxia, rice growth, root oxidative damage and endogenous ABA and proline accumulation were investigated in two different rice genotypes ('Nipponbare' (Nip) and 'Upland 502' (U502)). Results: Compared with U502 seedlings, Nip seedlings were highly tolerant to hypoxic stress, with increased plant biomass and leaf photosynthesis and decreased root oxidative damage. Hypoxia significantly stimulated the accumulation of proline and ABA in the roots of both cultivars, with a higher ABA level observed in Nip than in U502, whereas the proline levels showed no significant difference in the two cultivars. The time course variation showed that the root ABA and proline contents under hypoxia increased 1.5- and 1.2-fold in Nip, and 2.2- and 0.7-fold in U502, respectively, within the 1 d of hypoxic stress, but peak ABA production (1 d) occurred before proline accumulation (5 d) in both cultivars. Treatment with an ABA synthesis inhibitor (norflurazon, Norf) inhibited proline synthesis and simultaneously aggravated hypoxia-induced oxidative damage in the roots of both cultivars, but these effects were reversed by exogenous ABA application. Hypoxia plus Norf treatment also induced an increase in glutamate (the main precursor of proline). This indicates that proline accumulation is regulated by ABA-dependent signals under hypoxic stress. Moreover, genes involved in proline metabolism were differentially expressed between the two genotypes, with expression mediated by ABA under hypoxic stress. In Nip, hypoxia-induced proline accumulation in roots was attributed to the upregulation of OsP5CS2 and downregulation of OsProDH, whereas upregulation of OsP5CS1 combined with downregulation of OsProDH enhanced the proline level in U502. Conclusion: These results suggest that the high tolerance of the Nip cultivar is related to the high ABA level and ABA-mediated antioxidant capacity in roots. ABA acts upstream of proline accumulation by regulating the expression of genes encoding the key enzymes in proline biosynthesis, which also partly improves rice acclimation to hypoxic stress. However, other signaling pathways enhancing tolerance to hypoxia in the Nip cultivar still need to be elucidated. [ABSTRACT FROM AUTHOR]

As an economically and ecologically important freshwater fish, silver carp (Hypophthalmichthys molitrix) is sensitive to low oxygen tension. Prolyl hydroxylase domain (PHD) proteins are critical regulators of adaptive responses to hypoxia for their function of regulating the hypoxia inducible factor-1 alpha subunit (HIF-1α) stability via hydroxylation reaction. In the present study, three PHD genes were cloned from H. molitrix by rapid amplification of cDNA ends (RACE). The total length of HmPHD1, HmPHD2, and HmPHD3 were 2981, 1954, and 1847 base pair (bp), and contained 1449, 1080, and 738 bp open reading frames (ORFs) that encoded 482, 359, and 245 amino acids (aa), respectively. Amino acid sequence analysis showed that HmPHD1, HmPHD2, and HmPHD3 had the conserved prolyl 4-hydroxylase alpha subunit homolog domains at their C-termini. Meanwhile, the evaluation of phylogeny revealed PHD2 and PHD3 of H. molitrix were more closely related as they belonged to sister clades, whereas the clade of PHD1 was relatively distant from these two. The transcripts of PHD genes are ubiquitously distributed in H. molitrix tissues, with the highest expressional level of HmPHD1 and HmPHD3 in liver, and HmPHD2 in muscle. After acute hypoxic treatment for 0.5 h, PHD genes of H. molitrix were induced mainly in liver and brain, and different from HmPHD1 and HmPHD2, the expression of HmPHD3 showed no overt tissue specificity. Furthermore, under continued hypoxic condition, PHD genes exhibited an obviously rapid but gradually attenuated response from 3 h to 24 h, and upon reoxygenation, the transcriptional expression of PHD genes showed a decreasing trend in most of the tissues. These results indicate that the PHD genes of H. molitrix are involved in the early response to hypoxic stress, and they show tissue-specific transcript expression when performing physiological regulation functions. This study is of great relevance for advancing our understanding of how PHD genes are regulated when addressing the hypoxic challenge and provides a reference for the subsequent research of the molecular mechanisms underlying hypoxia adaptation in silver carp.