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Buthidazole (3-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-4-hydroxy-1-methyl-2-imidazolidinone) and tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N'-dimethylurea) are two new promising herbicides for selective weed control in corn (Zea mays L.) and sugarcane (Saccharum
Intact spinach chloroplasts, capable of high rates of photochemical oxygen evolution with CO2 as electron acceptor (120-350 mumol O2 mg chlorophyll-1 h-1) were examined for cytochrome redox changes. The response of the cytochromes in intact chloroplasts to oxidants and reductants appears to be
1. Spinach chloroplasts, pre-incubated with ferricyanide, acquire the ability to make ATP in the dark provided they are supplied with a reductant and a lipophilic mediator that can penetrate the membrane. The mediator must be of the type that, upon oxidation, releases protons into the surrounding
The regulation by adenylates of activities of various partial electron transport systems in spinach chloroplasts was studied using systems from H2O to 2,5-dimethyl-p-benzoquinone, H2O to 2,6-dichlorophenolindophenol, reduced 2,6-dichlorophenolindophenol to methyl viologen, and H2O to methyl viologen
The effect of increasing assay medium sorbitol concentration from 0.33 to 1.0 molar on the photosynthetic reactions of intact and broken spinach (Spinacia oleracea L. var. Long Standing Bloomsdale) chloroplasts was investigated by monitoring O(2) evolution supported by the addition of glyceric acid
Flow cytometry data of spinach thylakoid membrane preparations indicate the presence of a homogeneous thylakoid population. Fluorescence data from a flow cytometer and comparison with data from two other fluorometers show that chlorophyll a fluorescence detected with a flow cytometer has the
The role of an electron transport pathway associated with aerobic carbohydrate degradation in isolated, intact chloroplasts was evaluated. This was accomplished by monitoring the evolution of (14)CO(2) from darkened spinach (Spinacia oleracea) and Chlamydomonas reinhardtii chloroplasts externally
The organization of electron transport in photosystem II of spinach (Spinacia oleracea) chloroplasts was studied by means of various chelators and uncouplers. The partial reactions used included H(2)O-->methyl viologen, H(2)O-->silicomolybdic acid H(2)O-->ferricyanide, and
The isolation of a cytochrome f/b6 complex from spinach chloroplasts, with high yield and purity is reported. The complex consists of five polypeptides with a molecular mass of 34, 33, 23.5, 20 and 17.5 kDa, and contains one cytochrome f, two cytochromes b6 and the Rieske Fe-S center with two
Partition in an aqueous Dextran-polyethylene glycol two-phase system has been used for the separation of chloroplast membrane vesicles obtained by press treatment of a grana-enriched fraction after unstacking in a low salt buffer. The fractions obtained were analysed with respect to chlorophyll,
Inside-out thylakoid vesicles have been separated from right-side-out material after press disruption of chloroplast lamellae. The sepration was obtained by partitionin an aqueous dextran-polyethylene glycol two-phase system, a method which utilizes differences in surface properties for separation
The antioxidant effect of reduced plastoquinone was studied in chloroplast membranes. Isolated spinach thylakoid membranes were subjected to strong illumination followed by analysis of pigment bleaching and lipid peroxidation. The plastoquinone pool was kept in the reduced or oxidized state during
The functional size of Photosystem II (PS II) was investigated by radiation inactivation. The technique provides an estimate of the functional mass required for a specific reaction and depends on irradiating samples with high energy γ-rays and assaying the remaining activity. The analysis is based
The photoreduction of soluble plastocyanin in a homologous reconstituted system requires a resolved Photosystem II preparation and the cytochrome b6-f complex from spinach chloroplasts. Oxygen evolution is linked quantitatively to plastocyanin reduction in the reconstituted system, indicating that