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The effect of externally applied L-cysteine and glutathione (GSH) on ATP sulphurylase and adenosine 5'-phosphosulphate reductase (APR), two key enzymes of assimilatory sulphate reduction, was examined in Arabidopsis thaliana root cultures. Addition of increasing L-cysteine to the nutrient solution increased internal cysteine, gamma-glutamylcysteine and GSH(More)
Adenosine 5'-phosphosulfate (APS) sulfotransferase and APS reductase have been described as key enzymes of assimilatory sulfate reduction of plants catalyzing the reduction of APS to bound and free sulfite, respectively. APS sulfotransferase was purified to homogeneity from Lemna minor and compared with APS reductase previously obtained by functional(More)
The clonogenic growth inhibition, the cell cycle dependence of N4-hexadecyl-1-beta-D-arabinofuranosylcytosine (NHAC) cytotoxicity and the capability to induce apoptosis in ara-C-sensitive and -resistant HL-60 cells were investigated and compared with arabinofuranosylcytosine (ara-C). In the clonogenic assay with sensitive HL-60 cells, ara-C was slightly(More)
The arabinofuranosylcytosine (AraC) derivative N4-octadecyl-1-beta-D-arabinofuranosylcytosine (NOAC) and its (5'-->5')-heterodinucleoside phosphate analog NOAC-AraC were compared with AraC for cytotoxicity, cell-cycle dependence, phosphorylation by deoxycytidine (dC) kinase and apoptosis induction in native, AraC- or NOAC-resistant HL-60 cells. NOAC was(More)
We present a map of 511 keV electron-positron annihilation emission, based on data accumulated with the SPI spectrometer aboard ESA's INTEGRAL gamma-ray observatory, that covers approximately ∼ 95% of the celestial sphere. Within the exposed sky area, 511 keV line emission is significantly detected towards the galactic bulge region and, at a very low level,(More)
We present a measurement of the sky distribution of positronium (Ps) annihilation continuum emission obtained with the SPI spectrometer on board ESA's INTEGRAL observatory. The only sky region from which significant Ps continuum emission is detected is the Galactic bulge. The Ps continuum emission is circularly symmetric about the Galactic centre, with an(More)
The activity of the enzymes catalyzing the first two steps of sulfate assimilation, ATP sulfurylase and adenosine 5'-phosphosulfate reductase (APR), are confined to bundle sheath cells in several C(4) monocot species. With the aim to analyze the molecular basis of this distribution and to determine whether it was a prerequisite or a consequence of the C(4)(More)
Cysteine synthesis from sulfide and O-acetyl-L-serine (OAS) is a reaction interconnecting sulfate, nitrogen, and carbon assimilation. Using Lemna minor, we analyzed the effects of omission of CO(2) from the atmosphere and simultaneous application of alternative carbon sources on adenosine 5'-phosphosulfate reductase (APR) and nitrate reductase (NR), the key(More)
With the aim of analysing the relative importance of sugar supply and nitrogen nutrition for the regulation of sulphate assimilation, the regulation of adenosine 5'-phosphosulphate reductase (APR), a key enzyme of sulphate reduction in plants, was studied. Glucose feeding experiments with Arabidopsis thaliana cultivated with and without a nitrogen source(More)
The coding sequence of the wild-type, cys-sensitive, cysE gene from Escherichia coli, which encodes an enzyme of the cysteine biosynthetic pathway, namely serine acetyltransferase (SAT, EC 2.3.1. 30), was introduced into the genome of potato plants under the control of the cauliflower mosaic virus 35S promoter. In order to target the protein into the(More)