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W. D. Jeschke

Bio: W. D. Jeschke is an academic researcher from University of Würzburg. The author has contributed to research in topics: Photophosphorylation & Ankistrodesmus. The author has an hindex of 2, co-authored 2 publications receiving 147 citations.

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Journal ArticleDOI
TL;DR: A handy method was developed, which permits the separation of labelled intermediates of plant metabolism by thin-layer chromatography on cellulose layers, which is especially suitable for experiments with large numbers of samples.

137 citations

Journal ArticleDOI
TL;DR: It is concluded that the inhibition of (32)P- Incorporation and of (14)C-incorporation into phosphorylated compounds in vivo is due to an uncoupling by X-rays of photophosphorylation as in vitro.
Abstract: The incorporation of (32)P and (14)C into organic compounds by Ankistrodesmus is strongly inhibited by X-rays. In the same phosphorylated compounds (32)P-incorporation apparently is more severely inhibited by X-rays than the (14)C-labelling. The (32)P-incorporation into organic compounds is more strongly inhibited than (32)P-labelling of inorganic phosphate in the cell. The inhibition of (32)P-incorporation into a number of compounds is strikingly uniform. It is concluded that the inhibition of (32)P-incorporation and of (14)C-incorporation into phosphorylated compounds in vivo is due to an uncoupling by X-rays of photophosphorylation as in vitro. The difference in X-ray sensitivity of (14)C- and (32)P-incorporation into one organic phosphorous compound is attributed to a dual action of X-rays on (32)P-incorporation in organic compounds (both via the uncoupling of photophosphorylation) and only a single effect on (14)C-incorporation and (32)P-labelling of inorganic phosphate. The effect of X-rays on (14)C-incorporation into organic compounds included inhibition in most cases but also stimulation as in the case of glycolic acid. These differences may be due to interference in the intercellular regulations following the application of X-rays. The inhibition of (14)C-incorporation in many cases exhibits different behaviour at low (<200 krad) and high doses. These changes are discussed on the assumption that at the lower doses X-rays cause uncoupling of photophosphorylation and at the higher doses an additional inhibition of electron transport.

10 citations


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Journal ArticleDOI
01 Jan 1979-Planta
TL;DR: The uptake of sucrose against a concentration gradient into the dextran-impermeable [3H]-H2O space of these organelles was studied and an ATPase activity dependent on both Mg2+ and K+ seems to be localized at the inner surface of the tonoplast.
Abstract: Vacuoles were isolated from red beets (Beta vulgaris L.) by slicing the tissue and separated using a discontinuous dextran gradient centrifugation. The uptake of sucrose against a concentration gradient into the dextran-impermeable [3H]-H2O space of these organelles was studied using silicone layer filtering centrifugation on both fluorometric and 14C-measurement of sucrose. The rate is 24 nmol sucrose (unit betacyanin)-1 h-1 and appears to be stimulated by ATP to an uptake rate of 34 nmol. Control experiments with slices cut from red beet tissue and incubated with [14C]sucrose gave comparable results. An ATPase activity dependent on both Mg2+ and K+ seems to be localized at the inner surface of the tonoplast. This activity is strongly inhibited by EDAC and tartrate and there is no effect of oligomycin, whereas a slight stimulation was caused by DCCD.

123 citations

Journal ArticleDOI
TL;DR: Photosynthesis and translocation of photosynthetic products from symbiotic zooxanthellae in four species of temperate-latitude invertebrates were investigated in vivo and in vitro, and host control of symbiotic partners was discussed.
Abstract: Photosynthesis and translocation of photosynthetic products from symbiotic zooxanthellae in four species of temperate-latitude invertebrates were investigated in vivo and in vitro. In vivo, zooxanthellae fixed 14C and translocated a substantial proportion of fixed products to host tissues. In vitro, the effect of host tissue extracts on isolated zooxanthellae varied. Extracts of the soft coral Capnella gaboensis, lysed zooxanthellae after a relatively short exposure. Those of the zoanthid Zoanthus robustus and the nudibranch Pteraeolidia ianthina had little effect on translocation of organic carbon from zooxanthellae. In contrast, host extract of the scleractinian coral Plesiastrea versipora stimulated the release of up to 42% of the total 14C fixed, and the magnitude of release was positively correlated with the protein concentration of the extract. Host extracts had no effect on photosynthetic rates in algal symbionts. The effect of P. versipora extract on isolated zooxanthellae was studied. This extrac...

120 citations

Journal ArticleDOI
01 Apr 1990-Planta
TL;DR: In the plastids of Cuscuta reflexa the number of thylakoids is strongly reduced compared with true chloroplasts and no typical grana are visible, and in C. europaea no Rubisco activity was detected but there was a moderate activity of phosphoenolpyruvate-carboxylase.
Abstract: In the plastids of Cuscuta reflexa the number of thylakoids is strongly reduced compared with true chloroplasts and no typical grana are visible. The plastids of Cuscuta europaea lack thylakoids and the stroma is filled with either starch grains or lipid droplets. In Cuscuta reflexa both chlorophylls are present in low concentrations, while in C. europaea chlorophylls are totally absent. Light slightly stimulates the incorporation of 14CO2 in C. reflexa. This is in accordance with a low activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) which was measured in extracts of this parasite. No stimulation of 14CO2 incorporation by light was observed in C. europaea. Instead, a relatively strong incorporation was measured in darkness. Malate and aspartate were the main products of this incorporation. In agreement with these results, no Rubisco activity was detected in C. europaea but there was a moderate activity of phosphoenolpyruvate-carboxylase. The presence of the genes for both subunits of Rubisco (rbcL, rbcS) and of the gene which codes for the 32-kDa protein of photosystem II (psbA) was established for C. europaea by hybridization experiments. In both species only very small amounts of transcripts of these genes were detected.

93 citations

Journal ArticleDOI
TL;DR: Among 27 ‘leafy’ indoor decorative plants, a screening experiment revealed no outstanding species with regard to its capacity for metabolism of formaldehyde, and rate of uptake through stomata was too low to justify claims that plants contribute usefully to indoor air purification.
Abstract: Uptake, translocation and metabolism of 14C-labelled formaldehyde in the leaves of Epipremnum aureum (Golden Potho) and Ficus benjamina (Weeping Fig) were investigated. Plants were exposed in light and dark to 14C-formaldehyde (500 μg m−3) in gas exposure chambers. The amount of 14C-incorporation into the soluble (water-extractable) and insoluble fractions of leaves, stem sections and roots was determined. The soluble 14C-activity was fractionated by ion exchange chromatography followed by thin-layer chromatography/autoradiography. Approximately 60–70% of the applied 14C-formaldehyde was recovered from the plants. In the light about five times more 14C-formaldehyde was assimilated than in the dark. The amount of 14C-label derived from 14C-formaldehyde, which was incorporated into acid-stable metabolites, was enhanced to an even larger extent in the light. The 14C-activity pattern closely resembled the general labelling spectrum of photosynthates, obtained after a 14CO2 exposure. A substantial amount of labelled material, mostly sucrose, was translocated into the stems and roots. Our results suggest that in the light 14C enters the Calvin cycle after an enzymatic two-step oxidation process of 14C-formaldehyde to 14CO2. The activities of the respective enzymes, formaldehyde dehydrogenase and formate dehydrogenase, were determined. Among 27 ‘leafy’ indoor decorative plants, a screening experiment revealed no outstanding species with regard to its capacity for metabolism of formaldehyde, and rate of uptake through stomata was too low to justify claims that plants contribute usefully to indoor air purification.

90 citations