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Juszczuk IM Flexas J Szal B Dabrowska Z Ribas-Carbo M Rychter AM 《Physiologia plantarum》2007,131(4):527-541
The effects of changes in mitochondrial DNA in cucumber ( Cucumis sativus L.) mosaic mutant (MSC16) on respiration, photosynthesis and photorespiration were analyzed under non-stressed conditions. Decreased respiratory capacity of complex I in MSC16 mitochondria was indicated by lower respiration rates of intact mitochondria with malate and by rotenone-inhibited NADH or malate oxidation in the presence of alamethicin. Moreover, blue native PAGE indicated decreased intensity of protein bands of respiratory chain complex I in MSC16 leaves. Concerning the redox state, complex I impairment could be compensated to some extent by increased external NADH dehydrogenases (NDex NADH) and alternative oxidase (AOX) capacity, the latter presenting differential expression in the light and in the dark. Although MSC16 mitochondria have a higher AOX protein level and an increased capacity, the AOX activity measured in the dark conditions by oxygen discrimination technique is similar to that in wild-type (WT) plants. Photosynthesis induction by light followed different patterns in WT and MSC16, suggesting changes in feedback chloroplast ΔpH caused by different adenylate levels. At steady-state, net photosynthesis was only slightly impaired in MSC16 mutants, while photorespiration rate (PR) was significantly increased. This was the result of large decreases in both stomatal and mesophyll conductance to CO2 , which resulted in a lower CO2 concentration in the chloroplasts. The observed changes on CO2 diffusion caused by mitochondrial mutations open a whole new view of interaction between organelle metabolism and whole tissue physiology. The sum of all the described changes in photosynthetic and respiratory metabolism resulted in a lower ATP availability and a slower plant growth. 相似文献
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For optimal plant growth and development, cellular nitrogen (N) metabolism must be closely coordinated with other metabolic pathways, and mitochondria are thought to play a central role in this process. Recent studies using genetically modified plants have provided insight into the role of mitochondria in N metabolism. Mitochondrial metabolism is linked with N assimilation by amino acid, carbon (C) and redox metabolism. Mitochondria are not only an important source of C skeletons for N incorporation, they also produce other necessary metabolites and energy used in N remobilization processes. Nitric oxide of mitochondrial origin regulates respiration and influences primary N metabolism. Here, we discuss the changes in mitochondrial metabolism during ammonium or nitrate nutrition and under low N conditions. We also describe the involvement of mitochondria in the redistribution of N during senescence. The aim of this review was to demonstrate the role of mitochondria as an integration point of N cellular metabolism. 相似文献
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Ovum transport in mammalian oviducts involves two main effectors: ciliary motility and muscle contractility. To study the relative contribution of cilia to ovum transport in the rat, we blocked smooth muscle activity with isoproterenol, a beta-adrenergic agonist, and measured transport rates of surrogate ova in situ. Transport rates before isoproterenol administration were 0.04 mm/s in the cephalic ampulla and 0.03 mm/s in the caudal ampulla; rates were unchanged after administration of isoproterenol. To determine if isoproterenol affected ciliary activity, we measured ciliary beat frequency with laser-scattering spectroscopy over the effective isoproterenol dosage. Isoproterenol did not cause a significant change in ciliary beat frequency. Our results show that in the rat oviductal ampulla, ciliary motion is capable of transporting ova in the absence of muscle contractility. 相似文献
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Short‐term ammonium supply induces cellular defence to prevent oxidative stress in Arabidopsis leaves
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Anna Podgórska Maria Burian Anna M. Rychter Allan G. Rasmusson Bożena Szal 《Physiologia plantarum》2017,160(1):65-83
Plants can assimilate nitrogen from soil pools of both ammonium and nitrate, and the relative levels of these two nitrogen sources are highly variable in soil. Long‐term ammonium nutrition is known to cause damage to Arabidopsis that has been linked to mitochondrial oxidative stress. Using hydroponic cultures, we analysed the consequences of rapid shifts between nitrate and ammonium nutrition. This did not induce growth retardation, showing that Arabidopsis can compensate for the changes in redox metabolism associated with the variations in nitrogen redox status. During the first 3 h of ammonium treatment, we observed distinct transient shifts in reactive oxygen species (ROS), low‐mass antioxidants, ROS‐scavenging enzymes, and mitochondrial alternative electron transport pathways, indicating rapid but temporally separated changes in chloroplastic, mitochondrial and cytosolic ROS metabolism. The fast induction of antioxidant defences significantly lowered intracellular H2O2 levels, and thus protected Arabidopsis leaves from oxidative stress. On the other hand elevated extracellular ROS production in response to ammonium supply may be involved in signalling. The response pattern displays an intricate plasticity of Arabidopsis redox metabolism to minimise stress in responses to nutrient changes. 相似文献
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Bożena Szal Agata Jastrzębska Marek Kulka Karolina Leśniak Anna Podgórska Tiit Pärnik Hiie Ivanova Olav Keerberg Per Gardeström Anna M. Rychter 《Planta》2010,232(6):1371-1382
The MSC16 cucumber (Cucumis sativus L.) mitochondrial mutant was used to study the effect of mitochondrial dysfunction and disturbed subcellular redox state
on leaf day/night carbon and nitrogen metabolism. We have shown that the mitochondrial dysfunction in MSC16 plants had no
effect on photosynthetic CO2 assimilation, but the concentration of soluble carbohydrates and starch was higher in leaves of MSC16 plants. Impaired mitochondrial
respiratory chain activity was associated with the perturbation of mitochondrial TCA cycle manifested, e.g., by lowered decarboxylation
rate. Mitochondrial dysfunction in MSC16 plants had different influence on leaf cell metabolism under dark or light conditions.
In the dark, when the main mitochondrial function is the energy production, the altered activity of TCA cycle in mutated plants
was connected with the accumulation of pyruvate and TCA cycle intermediates (citrate and 2-OG). In the light, when TCA activity
is needed for synthesis of carbon skeletons required as the acceptors for NH4
+ assimilation, the concentration of pyruvate and TCA intermediates was tightly coupled with nitrate metabolism. Enhanced incorporation
of ammonium group into amino acids structures in mutated plants has resulted in decreased concentration of organic acids and
accumulation of Glu. 相似文献
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Plasma membranes were isolated from roots of bean (Phaseolus vulgaris L.) plants cultured on phosphate sufficient or phosphate deficient medium. The phospholipid composition of plasma membranes
was analyzed and compared with that of the microsomal fraction. Phosphate deficiency had no influence on lipid/protein ratio
in microsomal as well as plasma membrane fraction. In phosphate deficient roots phospholipid content was lower in the plasma
membrane, but did not change in the microsomal fraction. Phosphatidylcholine and phosphatidylethanolamine were two major phospholipids
in plasmalemma and microsomal membranes (80 % of the total). After two weeks of phosphate starvation a considerable decrease
(about 50 %) in phosphatidylcholine and phosphatidylethanolamine in microsomal membranes was observed. The decline in two
major phospholipids was accompanied by an increase in phosphatidic acid and lysophosphatidylcholine content. The effect of
alterations in plasma membrane phospholipids on membrane function e.g. nitrate uptake is discussed. 相似文献
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During the post-hypoxic period, symptoms of oxidative stress and activation of enzymatic and non-enzymatic antioxidant systems were observed in several plant tissues. In the roots, mitochondrial respiratory chain is the main source of ROS. Superoxide anion radical is formed in the mitochondrial electron-transport chain at the level of Complexes I and III. The purpose of this work was to estimate superoxide anion production by the mitochondria isolated after a period of hypoxic treatment. Seedlings of barley (Hordeum vulgare L.) were grown on a nutrient medium flushed for 5 d with air (control) or nitrogen (hypoxia) and then transferred for 24 h to aerated medium (post-hypoxia). Production of superoxide anion by the mitochondria was measured by SOD-inhibitable oxidation of adrenaline to adrenochrome with NADH as a respiratory substrate. Hypoxic treatment increased mitochondrial activity but decreased mitochondrial superoxide anion appearance outside the mitochondrial membrane as compared to the mitochondria isolated from the roots continuously grown on aerated medium. The result of lower superoxide anion determination is attributed to increased antioxidants concentration during hypoxia. This was confirmed by inhibition of O2− production by exogenous GSH and stimulation by addition of 1-chloro-2,4-dinitrobenzene (CDNB), which depleted endogenous mitochondrial GSH. 相似文献