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1988 (1)
1985 (1)
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    Friedrich, C. Hristian, B. Aum AnnRequires cookie*
 Title    A Patch Clamp Study of Tonoplast Electrical Properties in Vacuoles Isolated from Chenopodium rubrum Suspension Cells  
 Abstract    -W ilhelm B en tru p , B ernd H offm ann , M aria G o g arten -B o ek els, Jo h a n n P ete r G ogarten The patch clamp technique has been applied to isolated vacuoles from green suspension cells of Chenopodium rubrum to record electrical parameters of the tonoplast. In a symmetrical K* solution of 46 mM, the membrane displays a near zero voltage, whereas 2 mM ATP will hyper-polarize it to 15 or 20 mV (vacuole positive). The conductance amounts to about one S-m~2. Fluctuations of the clamp current are explained by an unknown channel species having opening times of 5 — 10 ms. Together with previous work on a tonoplast vesicle preparation and unpub­ lished data on vacuoles from our laboratory, the present results indicate an electrogenic mem­ brane ATPase pumping protons from the cytoplasm to the vacuole. 
  Reference    Z. Naturforsch. 40c, 886 (1985); received October 23 1985 
  Published    1985 
  Keywords    Patch Clamp, Membrane ATPase, Tonoplast, Vacuole, Chenopodium rubrum L 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0886.pdf 
 Identifier    ZNC-1985-40c-0886 
 Volume    40