Pyruvate,Pi dikinase (PPDK, EC 2.7.9.1) and NADP-malate dehydrogenase (MDH, EC 1.1.1.82) were activated in the light and inactivated following a dark treatment in mesophyll protoplasts of maize. DCMU (up to 33 micromolar), an inhibitor of noncyclic electron transport, inhibited activation of MDH much more strongly than it did PPDK. Antimycin A (6.6-33 micromolar), an inhibitor of cyclic photoph...

Substituted 1,2,3-thiadiazolyl-phenyl-ureas were found to be inhibitors of energy conservation in respiration and photosynthesis. The most effective dichlorophenylderivative uncouples ATP formation in isolated chloroplasts or mitochondria, at a concentration of about 2 and 9 /uu respec­ tively. At a certain concentration range the compounds also appear to be energy transfer inhibitors, similar ...

Light dependent (35 Klux) chlorophyll bleaching in autotrophically grown Euglena gracilis cells at slightly acidic pH (6.5-5.4) is stimulated by the photosystem II blockers DCMU and DBMIB (both 10(-5) M) as well as by the autooxidizable photosystem I electron acceptor, paraquat (10(-3) M). Chlorophyll photobleaching is accompanied by the formation of thiobarbituric acid -- sensitive material ("...

A Synechocystis 6714 mutant resistant to the phenol-type herbicide ioxynil was isolated and characterized. Ioxynil was shown to inhibit both the donor and the acceptor sides of photosystem II, but at different concentrations. The mutation found in the psbA gene (encoding the D, protein) at codon 266 (asparagine to threonine) [G. Ajlani, I. Meyer, C. Vernotte, and C. Astier, FEBS Lett. 246, 207—...

Using crude extracts from the cyanobacterium Anabaena variabilis glutamine synthetase (GS) activity was rapidly irreversibly reduced to about 60% during dark incubation („sponta­ neous GS inactivation“). An additional decrease was observed by the addition of ammonia in the light („ammonia-mediated inactivation“). Both effects were prevented by EDTA, MnCl2 or catalase indicative of the involveme...

In the recent years, increasing labour cost and shortage of being major constraints to follow manual harvesting in cotton staggered manner. Further, it is very expensive farmers would like increasingly opt for mechanical harvesting. this context, suggested that research should focus reduce cultivation substantially by promoting use synchronized maturity defoliants encourage agriculture, are use...

The objective of this work was to evaluate the acute toxicity commercial herbicides Karmex® (diuron: DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea) and Herbipol® (glyphosate: N-(phosphonomethyl) glycine) on megalopae Callinectes sapidus measure their relative abundance in association larval postlarval species crustaceans from estuary Jamapa River, Veracruz. Collections were made overnight using ...

Photosystem II, Active Particles, Polypeptides, Thylakoid Membrane, Anacystis A thylakoid membrane preparation isolated from the blue-green alga Anacystis nidulans was freed from carboxysomes, soluble enzymes and the pigment P750 by floating in a discontinuous sucrose density gradient. In a buffer containing sucrose and the zwitterionic detergent Miranol S2M-SF the thylakoids were loaded on a l...

TI1vwo basically differenlt svstemlls have been described by which chloroplast preparations are able to synthesize ATP in the light: cyclic and nioncyclic photophosphorylation (2, 3). Other systems producing ATP in the light. e.g. pseudocyclic (or aerobic) anid oxidative photoplhosphorylatioins might only be variations of the 2 basic types (26. 27). A main feature of true cyclic photophosphoryl...

Abstract Several phytoplankton species produce the metabolites dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) but their intracellular roles need to be better understood. To improve understanding of DMSP antioxidant function suggested by Sunda et al. (2002), we exposed diatom Skeletonema costatum, Prymnesiophyceae Phaeocystis globosa dinoflagellate Heterocapsa triquetra experimen...