Plants often develop the capacity to tolerate moderate and reversible environmental stresses, such as drought, and to re-establish normal development once the stress has been removed. An example of this phenomenon is provided by cut rose (Rosa hybrida) flowers, which experience typical reversible dehydration stresses during post-harvest handling after harvesting at the bud stages. The molecular mechanisms involved in rose flower dehydration tolerance are not known, however. Here, we characterized a dehydration- and abscisic acid (ABA)-induced ferritin gene (RhFer1). Dehydration-induced free ferrous iron (Fe ) is preferentially sequestered by RhFer1 and not transported outside of the petal cells, to restrict oxidative stresses during dehydration. Free Fe accumulation resulted in more serious oxidative stresses and the induction of genes encoding antioxidant enzyme in RhFer1-silenced petals, and poorer dehydration tolerance was observed compared with tobacco rattle virus (TRV) controls. We also determined that RhABF2, an AREB/ABF transcription factor involved in the ABA signaling pathway, can activate RhFer1 expression by directly binding to its promoter. The silencing of RhABF2 decreased dehydration tolerance and disrupted Fe homeostasis in rose petals during dehydration, as did the silencing of RhFer1. Although both RhFer1 and Fe transporter genes are induced during flower natural senescence in plants, the silencing of RhABF2 or RhFer1 accelerates the petal senescence processes. These results suggest that the regulatory module RhABF2/RhFer1 contributes to the maintenance of Fe levels and enhances dehydration tolerance through the action of RhFer1 locally sequestering free Fe under dehydration conditions, and plays synergistic roles with transporter genes during flower senescence.
Exercise plays an important role in the prevention and treatment of chronic liver disease and associated metabolic disorders. A single bout of exercise induces tissue blood flow redistribution, which decreases splanchnic circulation and leads to physiologic hypoxia in the gastrointestinal system and liver. The transcription factor, hypoxia inducible factor-1α (HIF-1α), and its regulator, prolylhydroxylase 2 (PHD2), play pivotal roles in the response to oxygen flux by regulating downstream gene expression levels in the liver. We hypothesized that exercise increases the HIF-1α levels in the liver, and that the hepatic PHD2/HIF-1α axis is involved in postexercise restoration of systemic energy homeostasis. Through constant O consumption, CO production, food and water intake, and physical activity detection with metabolic chambers, we observed that one 30-min session of swimming exercise enhances systemic energy metabolism in mice. By using the noninvasive bioluminescence imaging ROSA26 oxygen-dependent domain Luc mouse model, we reveal that exercise increases in vivo HIFα levels in the liver. Intraperitoneal injections of the PHD inhibitor, dimethyloxalylglycine, mimicked exercise-induced HIFα increase, whereas the HIF-1α inhibitor, PX-478, blocked this effect. We next constructed liver-specific knockout (LKO) mouse models with albumin- Cre-mediated, hepatocyte-specific Hif1a and Phd2 deletion. Compared with their controls, Hif1a-LKO and Phd2-LKO mice exhibited distinct patterns of hepatic metabolism-related gene expression profiles. Moreover, Hif1a-LKO mice failed to restore systemic energy homeostasis after exercise. In conclusion, the current study demonstrates that a single bout of exercise disrupts systemic energy homeostasis, increasing the HIF-1α levels in the liver. These findings also provide evidence that the hepatic PHD2/HIF-1α axis is involved in postexercise systemic metabolic homeostasis.-Luo, B., Xiang, D., Wu, D., Liu, C., Fang, Y., Chen, P., Hu, Y.-P. Hepatic PHD2/HIF-1α axis is involved in postexercise systemic energy homeostasis.
Unit variance (UV) scaling, mean centering (CTR) scaling, and Pareto (Par) scaling are three commonly used algorithms in the preprocessing of metabolomics data. Based on our NMR-based metabolomics studies, we found that the clustering identification performances of these three scaling methods were dramatically different as tested by the spectra data of 48 young athletes’ urine samples, spleen tissue (from mice), serum (from mice), and cell (from Staphylococcus aureus) samples. Our data suggested that for the extraction of clustering information, UV scaling could serve as a robust approach for NMR metabolomics data for the identification of clustering analysis even with the existence of technical errors. However, for the purpose of discriminative metabolite identification, UV scaling, CTR scaling, and Par scaling could equally extract discriminative metabolites efficiently based on the coefficient values. Based on the data presented in this study, we propose an optimal working pipeline for the selection of scaling algorithms in NMR-based metabolomics analysis, which has the potential to serve as guidance for junior researchers working in the NMR-based metabolomics research field.
The main objective of the present study was to determine metabolic profile changes in the brains of rats after simulated heliox saturated diving (HSD) to 400 meters of sea water compared to the blank controls. Alterations in the polar metabolome in the rat brain due to HSD were investigated in cortex, hippocampus, and striatum tissue samples by applying an NMR-based metabolomic approach coupled with biochemical detection in the cortex. The reduction in glutathione and taurine levels may hypothetically boost antioxidant defenses during saturation diving, which was also proven by the increased malondialdehyde level, the decreased superoxide dismutase, and the decreased glutathione peroxidase in the cortex. The concomitant decrease in aerobic metabolic pathways and anaerobic metabolic pathways comprised downregulated energy metabolism, which was also proven by the biochemical quantification of the metabolic enzymes Na-K ATPase and LDH in cerebral cortex tissue. The significant metabolic abnormalities of amino acid neurotransmitters, such as GABA, glycine, and aspartate, decreased aromatic amino acids, including tyrosine and phenylalanine, both of which are involved in the metabolism of dopamine and noradrenaline, which are downregulated in the cortex. Particularly, a decline in the level of N-acetyl aspartate is associated with neuronal damage. In summary, hyperbaric decompression of a 400 msw HSD affected the brain metabolome in a rat model, potentially including a broad range of disturbing amino acid homeostasis, metabolites related to oxidative stress and energy metabolism, and destabilizing neurotransmitter components. These disturbances may contribute to the neurochemical and neurological phenotypes of HSD.
In terms of improving the dynamic response characteristics of brushless AC synchronous generators, the concept of integrated design of AC exciter and rotating rectifier and their electromagnetic characteristics are studied, and the conditions and judgment methods for determining their operating modes are obtained in theoretical design and simulation design, pointing out that when the brushless excitation system operates in or is close to mode III, i.e., the rectifier always has three or four diodes in each operating cycle. The linear current amplifier characteristics can be basically achieved when the brushless excitation system is operated in mode III or is close to mode III, i.e., the rectifier always has three or four diodes alternating in each operating cycle. The impact of the key parameters of the AC exciter at different rotational speeds and temperatures on the characteristics of the linear current amplifier was explored, and an engineering prototype was manufactured. The related test verified the correctness of the concept of integrated electromagnetic design and simulation calculation. This study provides an engineered design method for enhancing the dynamic response properties of the brushless AC synchronous generators.
PURPOSE Long‐time saturation exposure may induce anxiety, loss of appetite, and digestive disorders, which relate to impairment of intestinal mucosal immune system and gut microbiota homeostasis. Our study examined the effects of 4‐day of saturation exposure on gut microbiota and intestinal antimicrobial peptides (AMPs) in mice. METHOD 20 male C57 Mice, 8‐week old, were randomly divided into saturation exposure group (SE, n=10) and control group (CON, n=10). SE exposed to N2/O2 mixed gas at 500kPa for 4 days in pressure chamber. Intestines were excised and stained with HE and AB‐PAS. Feces and Intestines were collected and extract gDNA and RNA respectively. We used qPCR to assay bacterial population (Bacteroides, Clostridia, Lactobacilli, Enterobacteria, and Akkermansia muciniphila) of the feces, and the AMPs (Defα5/β1, Retnlβ, Reg3β/γ) of small intestine and colon. RESULTS Within 4 days, SE mice did not exhibit nitrogen narcosis behavior. By comparing with the 16S rRNA genes, results revealed a significant increase in the relative abundances of A. muciniphila (9.28±5.67) and Clostridia (3.45±0.63) in SE. The relative abundance of Lactobacilli was lower (0.40±0.24) in SE. Moreover, a distinct increase of Enterobacteria (23.34±8.88) was observed in SE compared with CON. Gene expressions for Defα5/β1 in SE were decreased in small intestine, while Defβ1 and Reg3γ in SE were significantly decreased, and Defα5 and Reg3β increased in colon. CONCLUSION In sum, the data showed that a four‐day saturation exposure induced changes in the mRNA level of AMPs, and the gut microbiota composition in mice. Found: NSFC 31471135
A better understanding of the neurological molecular mechanisms induced by an extreme environment of hyperbaric decompression could contribute to the improvement of diving procedures. The main objective of the present study was to determine metabolic profile changes in the brains of rats after simulated heliox saturated diving (HSD) to 400 meters of sea water (msw) (4.0 MPa) with heliox to 5 bar (pO2 = 50 kPa) compared to the blank controls. Alterations in the polar metabolome in the rat brain due to hyperbaric heliox saturation were investigated in cortex, hippocampus, and striatum tissue samples by applying an NMR-based metabolomic approach coupled with biochemical detection in the cortex. The reduction in glutathione and taurine levels may hypothetically boost antioxidant defenses during saturation diving, which was also proven by the increased malondialdehyde level, the decreased superoxide dismutase, and the decreased glutathione peroxidase in the cortex. The concomitant decrease in aerobic metabolic pathways and anaerobic metabolic pathways comprised downregulated energy metabolism, which was also proven by the biochemical quantification of the metabolic enzymes Na-K ATPase and LDH in cerebral cortex tissue. The significant metabolic abnormalities of amino acid neurotransmitters, such as GABA, glycine, and aspartate, decreased aromatic amino acids, including tyrosine and phenylalanine, both of which are involved in the metabolism of dopamine and noradrenaline, which are downregulated in the cortex. In particular, a decline in the level of N-acetyl aspartate is associated with neuronal damage. In summary, hyperbaric decompression of a 400 msw HSD affected the brain metabolome in a rat model, potentially including a broad range of disturbing amino acid homeostasis, metabolites related to oxidative stress and energy metabolism, and destabilizing neurotransmitter components. These disturbances may contribute to the neurochemical and neurological phenotypes of HSD.
PURPOSEProlonged saturation exposure induces digestive disorders, affecting health related life quality of divers. The diversity of the gut microbiota has been associated with various health parameters. Therefore, we hypothesized that prolonged saturation diving would result intestinal microbiota dysbiosis in human. In this case report, the feces of elite divers were collected after a saturation diving mission to examine the gut microbiome.METHODTwo elite male divers were recruited for this study. This study was approved by the Research Ethics Committee of Naval Medical Research Institute. Exclusion criteria included having antibiotic treatment within previous month, drinking alcoholic within one week, or suffering from any gastrointestinal or immunological disease. During the entire experiment, divers were provided the same diet and living condition. Divers were compressed to depth of 300 m with helium‐oxygen, and held for 24 hours to saturation. During the saturation stay, they made an excursion diving to 330 m undersea, then surfaced after a 15‐day decompression. Their feces were collected within 24 hours before compression (0–1, 0–2), immediately (1–1, 1–2) and a one‐month recovery after decompression (2–1, 2–2). The fecal microbial DNA was extracted and sequenced on an Illumina MiSeq platform. Principal coordinates analysis was applied to detect the differences of gut microbiota compositions of all samples. The similarity of all gut microbiota compositions were analyzed, and presented in the Heatmap.RESULTSPre‐mission (one week before mission) physical examination was applied. Diver 1: age 26, 56 kg, BMI 20.5; Diver 2: age 30, 74 kg, BMI 23.9. The gut microbiota composition and diversity baseline of two divers were no different. Shown in Venn diagram of diver 1, 49 genera were shared by samples of all three periods, while 6 in 0‐1, 13 in 1‐1 and 18 in 2‐1 were unique. And in diver 2, 49 genera were found in samples of all periods, while 7 in 0‐2, 9 in 1‐2 and 12 in 2‐2 were not overlapped. The relative abundances of gut flora in each sample were presented in phylum and genus levels. The major alteration of gut microbiota occurred in phylum of Firmicutes. The relative abundances of Terrisporobacter genus, in which some species were related to infections, turned from 0.047±0.032% before compression, to 4.293±3.381% after decompression, then drop to 0.077±0.052. On the contrary, the genus of Ruminococcaceae, which have several beneficial bacteria, took 0.496±0.087% of microflora before compression, decreased to 0.015±0.009%, and increased to 0.747±0.005% after recovery. Significant changes of some nutrients and energy metabolism related microbes were found in both saturation exposure and recovery. Despite the variation of the microbiota relative abundances, 0‐2 and 1‐2, as well as 2‐1 and 2‐2, showed notable similarity. Meanwhile, after living together for nearly two months, the mircrobiota compositions tended to be similar.CONCLUSIONIn our study, saturation exposure or recovery remarkably influenced divers' gut flora. As the change pattern of some pathogens, divers may be vulnerable to infectious diseases or digestive disorders during saturation exposure. Compositions of nutrients and energy metabolism related microbes were changed notably, but presented large interpersonal variations. Analysis of related physiological indices and further studies are needed in order to illustrate the effects of saturation exposure on divers' microbiota and health.Support or Funding InformationFound: PLA Youth Training Project for Medical Science (16QNP022), Major Logistics Projects of PLA ( AHJ11J004, AWS16J033), National Natural Science Foundation of China (31471135, 31701040), Shanghai Sailing Program (17YF1418000) and Chenguang Program (16CG57).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
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