The Effect of Salt Stress on the Catabolism of Sugars in Leaves and Roots of a Mangrove Plant, Avicennia marina

1997 ◽  
Vol 52 (3-4) ◽  
pp. 187-192 ◽  
Author(s):  
Yuko Fukushima ◽  
Hamako Sasamoto ◽  
Shigeyuki Baba ◽  
Hiroshi Ashihara

Abstract Respiration and related aspects of metabolism were investigated in the roots and leaves of 2-year-old trees of the mangrove plant, Avicennia marina in the presence of 100, 250 and 500 mᴍ NaCl. The rate of respiration of leaves increased with increasing concentrations of NaCl in the incubation medium, but respiration of roots was not similarly affected. In order to examine the relative rates of catabolism of glucose by the glycolysis-tricarboxylic acid (TCA) cycle and the oxidative pentose phosphate pathway (PP pathway), we determined the rates of release of 14CO2 from [1-14C]glucose and from [ 6 -14C]glucose in segments of roots and leaves. The ratios of rates (C6/C1) in roots varied from 0.30 to 0.44, while ratios of 0.85 to 0.99 were obtained when leaves were incubated in the presence of various concentrations of NaCl. It appeared that the PP pathway was more involved in sugar catabolism in the roots than in the leaves of A. marina. Uniformaly 14C-labelled sucrose, incubated with segments of roots and leaves for 18 h, was converted to CO2, amino acids (mainly glutamine), organic acids (mainly malic acid), sugars and ethanol-insoluble macromolecules. The incorporation of radioactivity into most of these components was not significantly affected by NaCl. However, in leaves (but not in roots) the release of 14CO2 from [ U -14C]sucrose was en­ hanced by NaCl at 250 mᴍ and 500 mᴍ, while the rate of incorporation of radioactivity into macromolecules was reduced by high concentrations of NaCl. Incorporation of radioactivity from [ U -14C]sucrose into malic acid was enhanced in both roots and leaves by an increase in the concentration of NaCl from 100 mᴍ to 500 mᴍ (this concentrations is similar to that in sea water). Independent of the concentration of NaCl, more than half of the radioactivity in the neutral fraction from leaves was incorporated into an unidentified sugar, while in the same fraction from roots, the radioactivity was associated with glucose, fructose and sucrose. On the basis of these results, a discussion is presented of the characteristics of catabolism of sugars in A. marina in relation to salt resistance.

1997 ◽  
Vol 52 (7-8) ◽  
pp. 433-440 ◽  
Author(s):  
Hiroshi Ashihara ◽  
Kyoko Adachi ◽  
Miho Otawa ◽  
Eri Yasumoto ◽  
Yuko Fukushima ◽  
...  

Naturally grown two-month-old seedlings of Avicennia marina contain high concentrations of Na+ and Cl-.+ Our NMR studies revealed an accumulation of glycinebetaine, asparagine and stachyose in A. marina. The highest concentration of glycinebetaine was observed in young leaves, while the distribution of stachyose was restricted in stems and roots. A sparagine comprised more than 96% of total free amino acids in roots and 84% in leaves from two-year-old plants. Little or no accumulation of proline or polyols, which are proposed as compatible solutes in other plants, could be detected in A. marina. The activities of phosphofructokinase, pyrophosphate:fructose-6-phosphate 1-phosphotransferase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase (decarboxylating), phosphoenolpyruvate carboxylase and NAD:malate dehydrogenase from young leaves of A. marina were inhibited by NaCl, while the activity of fructose-1,6-bisphosphate aldolase was activated by 50-200 m M NaCl. There was little or no effect of high concentrations (up to 500 mᴍ ) of glycinebetaine on the activities of any of these enzymes. No significant protection by glycinebetaine was detected against NaCl inhibition of these enzymatic activities. Based on these results, possible mechanisms for the salt-resistance of A. marina cells are discussed.


Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 459 ◽  
Author(s):  
Bing Liu ◽  
Xujian Peng ◽  
Lingjuan Han ◽  
Leiping Hou ◽  
Bin Li

To investigate the effects of exogenous spermidine (Spd) on metabolism changes under salt stress in cucumber roots, a gas chromatography-mass spectrometry (GC-MS) was performed. The results showed that most of the 142 metabolites responded to salt stress or exogenous Spd treatment. Salt stress reduced carbon consumption, resulted in the transformation of glycolysis and the tricarboxylic acid (TCA) cycle to the pentose phosphate pathway (PPP), and meanwhile increased salicylic acid (SA) and ethylene synthesis, and, thus, inhibited the growth of seedlings. However, exogenous Spd further improved the utilization of carbon, the energy-saving pattern of amino acid accumulation, and the control of hydroxyl radicals. In conclusion, Spd could promote energy metabolism and inhibit SA and ethylene synthesis in favor of root growth that contributes to higher salt tolerance. This study provides insight that may facilitate a better understanding of the salt resistance by Spd in cucumber seedlings.


Author(s):  
Н. Демиденко ◽  
N. Demidenko

In the Mezen bay and estuaries Mezen and Kuloy can be high concentrations of mud suspension there, involving the formation at times mobile suspensions and settled mud. Within estuaries the river water is mixed with the sea water by the action of tidal motions, by waves on the sea surface and by the river discharge forcing its way to the sea. Nearly all shallow tidal estuaries, where currents exceed about 1,0m s-1 and where sand is present, have sand waves. Sand waves have a variety of cross-sectional and plan forms.


AMB Express ◽  
2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Genan Wang ◽  
Bingyi Shi ◽  
Pan Zhang ◽  
Tingbin Zhao ◽  
Haisong Yin ◽  
...  

Abstractβ-poly(l-malic acid) (PMLA) is a water-soluble biopolymer used in medicine, food, and other industries. However, the low level of PMLA biosynthesis in microorganisms limits its further application in the biotechnological industry. In this study, corn steep liquor (CSL), which processes high nutritional value and low-cost characteristics, was selected as a growth factor to increase the PMLA production in strain, Aureobasidium melanogenum, and its metabolomics change under the CSL addition was investigated. The results indicated that, with 3 g/L CSL, PMLA production, cell growth, and yield (Yp/x) were increased by 32.76%, 41.82%, and 47.43%, respectively. The intracellular metabolites of A. melanogenum, such as amino acids, organic acids, and key intermediates in the TCA cycle, increased after the addition of CSL, and the enrichment analysis showed that tyrosine may play a major role in the PMLA biosynthesis. The results presented in this study demonstrated that the addition of CSL would be an efficient approach to improve PMLA production.


2011 ◽  
Vol 2 (2) ◽  
pp. 143-147 ◽  
Author(s):  
M. Gnanadesigan ◽  
M. Anand ◽  
S. Ravikumar ◽  
M. Maruthupandy ◽  
M. Syed Ali ◽  
...  

2020 ◽  
Author(s):  
Shouan Zhu ◽  
Albert Batushansky ◽  
Anita Jopkiewicz ◽  
Dawid Makosa ◽  
Kenneth M. Humphries ◽  
...  

ABSTRACTObjectiveObesity accelerates the development of osteoarthritis (OA) during aging and is associated with altered chondrocyte cellular metabolism. The objective of this study was to investigate the role of sirtuin 5 (SIRT5) in regulating chondrocyte protein lysine malonylation (MaK) and cellular metabolism under obesity-related conditions.MethodsMaK and SIRT5 were immunostained in knee articular cartilage of obese db/db mice and different aged C57BL6 mice with or without destabilization of the medial meniscus (DMM) surgery to induce OA. Primary chondrocytes were isolated from 7-day-old WT and Sirt5−/− mice and treated with varying concentrations of glucose and insulin to mimic obesity. Sirt5-dependent effects on MaK and metabolism were evaluated by Western blot, Seahorse Respirometry, and gas/chromatography-mass/spectrometry (GC-MS) metabolic profiling.ResultsMaK was significantly increased in cartilage of db/db mice and in chondrocytes treated with high concentrations of glucose and insulin (GluhiInshi). Sirt5 protein was increased in an age-dependent manner following joint injury, and Sirt5 deficient primary chondrocytes had increased MaK, decreased glycolysis rate, and reduced basal mitochondrial respiration. GC-MS identified 41 metabolites. Sirt5 deficiency altered 13 distinct metabolites under basal conditions and 18 metabolites under GluhiInshi treatment. Pathway analysis identified a wide range of Sirt5-dependent altered metabolic pathways that include amino acid metabolism, TCA cycle, and glycolysis.ConclusionThis study provides the first evidence that Sirt5 broadly regulates chondrocyte metabolism. We observed changes in Sirt5 and MaK levels in cartilage with obesity and joint injury, suggesting that the Sirt5-MaK pathway may contribute to altered chondrocyte metabolism that occurs during OA development.


2018 ◽  
Vol 1 (4) ◽  
Author(s):  
Beibei Liu ◽  
Shujie Lou

Objective atherosclerosis has been associated with the progression of cognitive impairment and dementia. Several features, such as high oxygen consumption, a large content of peroxidation-sensitive polyunsaturated fatty acids (PUFAs) and a strong dependency on the supply of glucose make the brain vulnerable to even small metabolic changes. The hippocampus is closely related to memory and learning function, and prone to ischemic injury. However, using metabolomics technology to explore metabolites of hippocampus from atherosclerosis animals is rarely reported. We aim to reveal the metabolic changes during atherosclerosis, and clarify the possible role of exercise in regulating hippocampus metabolism. Methods we established a rat model of atherosclerosis(n=18) along with control group (n=10). The model group was assigned into the AS group (n=8) and the TAS group (n=8), which was intervened by running exercise for 4 weeks. A Y maze test was performed to evaluate initial memory. Metabolomics based on GC-MS was applied to detect small molecules metabolites in rat hippocampus. Results we found that the AS and TAS group both showed elevation in HDL, meanwhile decrement in TC and LDL after 4 weeks’ intervention. The behavioral test showed rats from AS group entered less frequently into and spent less time in the novel arm than rats from C group (P<0.01), while other indexes showed no difference. Compared to the C group, metabolites including xylulose 5-phosphate, threonine, succinate and nonanoic acid were markedly elevated, whereas methyl arachidonic acid and methyl stearate decreased in the AS group. Meanwhile, the levels of succinic acid, branched chain amino acids, nonanoic acid and desmosterol decreased, whereas methyl arachidonic acid, methyl stearate, and glyceraldehyde-3-phosphate elevated in the hippocampus of the TAS group in comparison with the AS group. Conclusions A series of metabolic changes implicated in the hippocampus of atherosclerotic rats, including a decrease in anaerobic glycolysis and TCA cycle, an activation of pentose phosphate pathway, and a disturbance in fatty acid oxidation and cholesterol synthesis, which could lead to insufficient ATP in the hippocampus and related to the behavioral changes of atherosclerotic rats, while running exercise may take part in regulating metabolism to normal state in the hippocampus of atherosclerotic rats.


2004 ◽  
Vol 70 (12) ◽  
pp. 7277-7287 ◽  
Author(s):  
Christoph Wittmann ◽  
Patrick Kiefer ◽  
Oskar Zelder

ABSTRACT Metabolic fluxes in the central metabolism were determined for lysine-producing Corynebacterium glutamicum ATCC 21526 with sucrose as a carbon source, providing an insight into molasses-based industrial production processes with this organism. For this purpose, 13C metabolic flux analysis with parallel studies on [1-13CFru]sucrose, [1-13CGlc]sucrose, and [13C6 Fru]sucrose was carried out. C. glutamicum directed 27.4% of sucrose toward extracellular lysine. The strain exhibited a relatively high flux of 55.7% (normalized to an uptake flux of hexose units of 100%) through the pentose phosphate pathway (PPP). The glucose monomer of sucrose was completely channeled into the PPP. After transient efflux, the fructose residue was mainly taken up by the fructose-specific phosphotransferase system (PTS) and entered glycolysis at the level of fructose-1,6-bisphosphate. Glucose-6-phosphate isomerase operated in the gluconeogenetic direction from fructose-6-phosphate to glucose-6-phosphate and supplied additional carbon (7.2%) from the fructose part of the substrate toward the PPP. This involved supply of fructose-6-phosphate from the fructose part of sucrose either by PTSMan or by fructose-1,6-bisphosphatase. C. glutamicum further exhibited a high tricarboxylic acid (TCA) cycle flux of 78.2%. Isocitrate dehydrogenase therefore significantly contributed to the total NADPH supply of 190%. The demands for lysine (110%) and anabolism (32%) were lower than the supply, resulting in an apparent NADPH excess. The high TCA cycle flux and the significant secretion of dihydroxyacetone and glycerol display interesting targets to be approached by genetic engineers for optimization of the strain investigated.


2005 ◽  
Vol 187 (9) ◽  
pp. 2967-2973 ◽  
Author(s):  
Cuong Vuong ◽  
Joshua B. Kidder ◽  
Erik R. Jacobson ◽  
Michael Otto ◽  
Richard A. Proctor ◽  
...  

ABSTRACT Staphylococcal polysaccharide intercellular adhesin (PIA) is important for the development of a mature biofilm. PIA production is increased during growth in a nutrient-replete or iron-limited medium and under conditions of low oxygen availability. Additionally, stress-inducing stimuli such as heat, ethanol, and high concentrations of salt increase the production of PIA. These same environmental conditions are known to repress tricarboxylic acid (TCA) cycle activity, leading us to hypothesize that altering TCA cycle activity would affect PIA production. Culturing Staphylococcus epidermidis with a low concentration of the TCA cycle inhibitor fluorocitrate dramatically increased PIA production without impairing glucose catabolism, the growth rate, or the growth yields. These data lead us to speculate that one mechanism by which staphylococci perceive external environmental change is through alterations in TCA cycle activity leading to changes in the intracellular levels of biosynthetic intermediates, ATP, or the redox status of the cell. These changes in the metabolic status of the bacteria result in the attenuation or augmentation of PIA production.


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