The Warburg Effect in a Chloroplast-Free Preparation from <i>Euglena gracilis</i>

Ellyard, Peter W.; Pietro, Anthony San

doi:10.1104/pp.44.12.1679

Cited by 10 publications

(3 citation statements)

References 9 publications

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“…Respiration of algae in light, usually called photorespiration, results from the oxidation of photosynthetic products namely glycolate which occurs at rates 3 to 5 times more than in dark (Zelitch, 1973) . Ellyard & San Pietro (1969) studied the Warburg effect in darkness in Euglena and concluded that inhibition by oxygen may occur partly in the photosynthetic carbon reduction cycle . Wetzel & Hough (1973) stated that the rate of oxidation of glycolic acid, a direct product of Calvin cycle photosynthesis, is highly influenced by and is proportional to oxygen concentration, light intensity and temperature .…”

Section: Short Term and Long Term Incubationmentioning

confidence: 99%

Diurnal, seasonal and vertical study of primary production in Sathiar reservoir

Kannan

Job

1980

Hydrobiologia

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Gross primary production in Sathiar reservoir showed that it is comparable to and as high as in other eutrophic waters . The diel periodicity of photosynthesis which shows a peculiar decline in early afternoon, has been shown to be linked with photorespiration due to high oxygen tension . Besides temperature and transparency the trophogenic area appears to regulate gross primary production . In Sathiar nutrients are not limiting GPP and the main factors controlling it are linked with phytoplankton biomass, water level changes and therefore with precipitation . The maximum production density was always at the surface except in the months of December and January .

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Section: Short Term and Long Term Incubationmentioning

confidence: 99%

Diurnal, seasonal and vertical study of primary production in Sathiar reservoir

Kannan

Job

1980

Hydrobiologia

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“…It is well documented that 02 reversibly inhibits photosynthetic CO2 assimilation and 02 evolution in a variety of plant systems, including intact leaves, algae, leaf cells, and isolated chloroplasts (5,9,19). Although the mechanism of the inhibition of photosynthesis by 02 iS presently a controversial topic, there is little doubt that the site of 02 interaction is the photosynthetic carbon reduction cycle (4,7,8). It may well be that glycidate stimulated the linear rates of chloroplast CO2 fixation in the presence of 02 by relieving the 02 inhibition of photosynthesis.…”

Section: Glycidate and Chloroplast Photosynthesismentioning

confidence: 99%

Effect of Glycidate on Glycolate Formation and Photosynthesis in Isolated Spinach Chloroplasts

Chollet

1976

Plant Physiol.

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Preparation of Chloroplasts. Chloroplasts were isolated from leaves of spinach (Spinacia oleracea L., var. Virginia Blight Resistant) grown in a growth chamber at 21 C with a 10-hr day (2100 ft-c) and 16 C night. The light-dark cycle in the chamber was adjusted so that the plants received about 30 min of illumination before chloroplast isolation. Chloroplasts were prepared essentially as described by Jensen (12) with some modifications. The rinsed leaves, about 10 g after deribbing, were chopped gently at 4 C with razor blades in 45 ml of a grinding medium containing 330 mm sorbitol, 50 mm MES, 2 mM Na2EDTA, 1 mM MgCI2, I mm MnCI2, 0.5 mm K2HPO, (entire solution adjusted with NaOH to pH 6.5 at 4 C) plus 5 mm freshly prepared isoascorbate. The slurry was squeezed through two layers of Miracloth and centrifuged for 50 sec at 2000g. The chloroplast pellet was resuspended and stored in the dark at 4 C in the sorbitol-salt solution described above except that 50 mm HEPES (pH 6.7) replaced MES and the isoascorbate concentration was reduced to 2.5 mm. Chl was determined by the method of Arnon (1), and the chloroplast preparations contained 110 to 650 ,ug Chl/ml.Photosynthetic "C02 Assimilation. Photosynthetic CO2 fixation by the isolated chloroplasts was determined by H'4CO3-incorporation at 25 C and 3700 ft-c (74 nanoeinsteins/cm2 sec, 400-700 nm) under various He/02 atmospheres. Unless noted otherwise, the reaction vessels contained chloroplasts (5-32 tig of Chl), resuspension medium adjusted to pH 7.8, 5 mm freshly prepared Na4P207, +3 mm glycidate, and 1 mm NaH 4CO3 (2)(3)(4) Ci/mole) in a final volume of I ml. Vessels containing all the reaction medium components except chloroplasts and "4C-bicarbonate were sealed and repeatedly evacuated and refilled with the appropriate He/02 mixture and chilled, after which the chloroplasts were introduced with a 20-gauge syringe needle.Following a 4-min preillumination without shaking in the photosynthetic Warburg bath, the reactions were initiated by injecting NaH14CO3 and terminated at varying times by injecting 0.1 ml of 6 N acetic acid. Contents of the flasks were thoroughly mixed, aliquots dried at 25 C under a stream of N2, and dpm 237 www.plantphysiol.org on May 11, 2018 -Published by Downloaded from

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“…Strictly speaking it is not an 'effect' but a phenotype (the Warburg phenotype). Its use is also rather confusing because one of Warburg's other discoveries, the inhibitory effect of O 2 on photosynthesis (Warburg and Krippahl 1960), became known as 'the Warburg effect' in photosynthesis research (Ellyard and San Pietro 1969;Robinson et al 1980). Warburg hypothesized ('Hypothese über die Entstehung der Tumoren' (Warburg et al 1924)) that tumours could be caused by chronic hypoxia of normal tissue.…”

Section: Bioenergetics Of Cancer Cells; the Warburg Phenotypementioning

confidence: 99%

Mammalian NADH:ubiquinone oxidoreductase (Complex I) and nicotinamide nucleotide transhydrogenase (Nnt) together regulate the mitochondrial production of H2O2—Implications for their role in disease, especially cancer

Albracht

Meijer

Rydström

2011

J Bioenerg Biomembr

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Mammalian NADH:ubiquinone oxidoreductase (Complex I) in the mitochondrial inner membrane catalyzes the oxidation of NADH in the matrix. Excess NADH reduces nine of the ten prosthetic groups of the enzyme in bovine-heart submitochondrial particles with a rate of at least 3,300 s −1 . This results in an overall NADH→O 2 rate of ca. 150 s −1 . It has long been known that the bovine enzyme also has a specific reaction site for NADPH. At neutral pH excess NADPH reduces only three to four of the prosthetic groups in Complex I with a rate of 40 s −1 at 22°C. The reducing equivalents remain essentially locked in the enzyme because the overall NADPH→O 2 rate (1.4 s −1 ) is negligible. The physiological significance of the reaction with NADPH is still unclear. A number of recent developments has revived our thinking about this enigma. We hypothesize that Complex I and the Δp-driven nicotinamide nucleotide transhydrogenase (Nnt) co-operate in an energy-dependent attenuation of the hydrogen-peroxide generation by Complex I. This co-operation is thought to be mediated by the NADPH/NADP + ratio in the vicinity of the NADPH site of Complex I. It is proposed that the specific H 2 O 2 production by Complex I, and the attenuation of it, is of importance for apoptosis, autophagy and the survival mechanism of a number of cancers. Verification of this hypothesis may contribute to a better understanding of the regulation of these processes.

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The Warburg Effect in a Chloroplast-Free Preparation from Euglena gracilis

Cited by 10 publications

References 9 publications

Diurnal, seasonal and vertical study of primary production in Sathiar reservoir

Diurnal, seasonal and vertical study of primary production in Sathiar reservoir

Effect of Glycidate on Glycolate Formation and Photosynthesis in Isolated Spinach Chloroplasts

Mammalian NADH:ubiquinone oxidoreductase (Complex I) and nicotinamide nucleotide transhydrogenase (Nnt) together regulate the mitochondrial production of H2O2—Implications for their role in disease, especially cancer

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