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'Herbicides' in keywords Facet   section ZfN Section C:Volume 043  [X]
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1988 (3)
1Author    Angela Weber, Elke Fischer, Helmut Schipp Von Branitz, Ulrich LüttgeRequires cookie*
 Title    The Effects of the Herbicide Sethoxydim on Transport Processes in Sensitive and Tolerant Grass Species I. Effects on the Electrical Membrane Potential and Alanine Uptake  
 Abstract    Sethoxydim is a postemergence herbicide used to control grass weeds. Application at concen-trations higher than 0.1 mM to leaf segments of the sensitive grass species Poa pratensis and Festuca ovina and the tolerant species Poa annua and Festuca rubra, caused a reduction of the electrical membrane potential (AE). The depolarization was reversible and depended linearly on the herbicide concentration. The passive diffusion component of AE was not affected by sethoxy-dim indicating that the herbicide did not change passive permeability characteristics of the plas-malemma. Consequently sethoxydim reduced the active component of AE that depended on primary active transport processes across the plasmalemma. Moreover, sethoxydim increased the reduction of AE of grass leaf cells that was associated with the onset of H + -amino acid cotrans-port. Simultaneously the uptake of alanine into leaf segments was reduced. From these results it had to be concluded that the plasmalemma-bound H + -ATPase was inhibited by sethoxydim in sensitive and tolerant grasses. In vitro ATP hydrolysis of plasmalemma vesicles isolated from grass leaves by polymer phase partitioning, however, was not inhibited by sethoxydim. Apparent-ly another primary active transport mechanism that may contribute to an electrochemical H + -gradient across the plasmalemma, i.e. a plasmalemma-bound redox system, should be the site of inhibition responsible for the membrane effects of sethoxydim observed in vivo. 
  Reference    Z. Naturforsch. 43c, 249—256 (1988); received December 23 1987 
  Published    1988 
  Keywords    Plasmalemma, Membrane ATPase, Herbicide, Sethoxydim, Amino Acid Uptake 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0249.pdf 
 Identifier    ZNC-1988-43c-0249 
 Volume    43 
2Author    Angela Weber, Ulrich LüttgeRequires cookie*
 Title    The Effects of the Herbicide Sethoxydim on Transport Processes in Sensitive and Tolerant Grass Species II. Effects on Membrane-Bound Redox Systems in Plant Cells  
 Abstract    Leaf slices of sethoxydim-sensitive (Poa pratensis, Festuca ovina) and tolerant (Poa annua, Festuca rubra) grass species were found to be able to reduce extracellular ferricyanide by electron transport across the plasmalemma. This reduction was inhibited by the herbicide sethoxydim, and the sensitive species were much more strongly affected than the tolerant ones. The inhibition was concentration dependent. Sethoxydim affected the electron transport in isolated Poo chloroplasts. Polarographic and photometric measurements of ferricyanide reduction suggested photosystem II to be the site of action. Inhibition occurred only in the sensitive species Poa pratensis and was linearly dependent on concentration. In isolated mitochondria from sensitive Zea mays coleop-tiles sethoxydim also acted as an inhibitor of electron transport. Only slight inhibition was meas-ured with mitochondria from tubers of tolerant potato (Solanum tuberosum). It is concluded that sethoxydim generally acts as inhibitor of membrane-bound redox systems. The specific inhibition of the plasmalemma-bound redox system of sethoxydim-sensitive plants could contribute to a selective action of the herbicide. 
  Reference    Z. Naturforsch. 43c, 257—263 (1988); received December 23 1987 
  Published    1988 
  Keywords    Sethoxydim, Herbicide, Redox Systems, Isolated Organelles, Plasmalemma 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0257.pdf 
 Identifier    ZNC-1988-43c-0257 
 Volume    43 
3Author    Walter Oettmeier, Klaus Masson, Andreas DonnerRequires cookie*
 Title    QSAR of Nitro-diphenylethers as Inhibitors of Cyclic Photophosphorylation  
 Abstract    A number of 25 nitro-diphenylethers have been synthesized and assayed for their inhibitory activity in N-methylphenazonium-methosulfate mediated cyclic photophosphorylation. Their p/50-values were in the range from 3.5 to 5.3. A QSAR-analysis revealed that the lipophilicity of the nitro-diphenylethers as expressed by Z:t played a major role. In addition, the Taft steric parameter £s in positions 6', 4' and 2' (in decreasing order) contributed to the inhibitory activity. For maximal biological activity, positions 4' and 6' should be left unsubstituted whereas a bulky substituent is required for position 2'. 
  Reference    Z. Naturforsch. 43c, 705—708 (1988); received May 31 1988 
  Published    1988 
  Keywords    Cyclic Photophosphorylation, Herbicides, Nitro-diphenylethers, Quantitative Structure-Activity Relationship 
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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0705.pdf 
 Identifier    ZNC-1988-43c-0705 
 Volume    43