Author
H. Gimmler
Bio: H. Gimmler is an academic researcher from University of Würzburg. The author has an hindex of 2, co-authored 2 publications receiving 148 citations.
Papers
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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
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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
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
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
94 citations
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