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Rennenberg H Huber B Schröder P Stahl K Haunold W Georgii HW Slovik S Pfanz H 《Plant physiology》1990,92(3):560-564
Spruce (Picea Abies L.) trees from the same clone were supplied with different, but low, amounts of plant available sulfate in the soil (9.7-18.1 milligrams per 100 grams of soil). Branches attached to the trees were enclosed in a dynamic gas exchange cuvette and analyzed for the emission of volatile sulfur compounds. Independent of the sulfate supply in the soil, H2S was the predominant reduced sulfur compound continuously emitted from the branches with high rates during the day and low rates in the night. In the light, as well as in the dark, the rates of H2S emission increased exponentially with increasing water vapor flux from the needles. Approximately 1 nanomole of H2S was found to be emitted per mole of water. When stomata were closed completely, only minute emission of H2S was observed. Apparently, H2S emission from the needles is highly dependent on stromatal aperture, and permeation through the cuticle is negligible. In several experiments, small amounts of dimethylsulfide and carbonylsulfide were also detected in a portion of the samples. However, SO2 was the only sulfur compound consistently emitted from branches of spruce trees in addition to H2S. Emission of SO2 mainly proceeded via an outburst starting before the beginning of the light period. The total amount of SO2 emitted from the needles during this outburst was correlated with the plant available sulfate in the soil. The diurnal changes in sulfur metabolism that may result in an outburst of SO2 are discussed. 相似文献
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G V Brown R F Anders R L Coppel R B Saint A F Cowman H D Stahl K R Lingelbach G F Mitchell M P Alpers D J Kemp 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1984,307(1131):179-187
A library of cDNA clones expressing proteins of the asexual blood stages of a Papua New Guinean isolate of Plasmodium falciparum (isolate FCQ27/PNG (FC27] was constructed in the bacteriophage vector lambda gt11-Amp3. In an in situ colony immunoassay, human serum was used to identify colonies producing natural immunogens. Sera from donors of defined clinical status, or reactive to a defined subset of natural immunogens were used to identify clones of particular interest (for example, clones reacting with convalescent but not with acute serum or clones expressing the isolate specific S-antigen of FC27). Antisera raised by immunizing mice and rabbits with cloned antigens were used to characterize the P. falciparum proteins corresponding to the antigen-positive clones. Nucleotide sequence analysis of an antigen found on the surface of cells infected with ring stage parasites revealed an unusual sequence coding for eight, four and three amino acid repeats rich in acidic amino acids. The discussion centres on the use of cloned antigens as tools for the analysis of the host-protective immune response and selection of candidate vaccine molecules. 相似文献
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Marianne Frolich J.Frederick Krall Rochelle E. Stahl Stanley G. Korenman 《Archives of biochemistry and biophysics》1982,217(2):473-478
The activation of uterine smooth muscle adenylate cyclase was studied by pretreating the particulate form of the enzyme with the GTP analog guanyl-5′-yl imidodiphosphate (Gpp(NH)p). Pretreatment with Gpp(NH)p left the enzyme in an irreversibly activated state which survived subsequent washing in guanyl nucleotide-free buffer. Activation under these conditions was multiphasic with rapid and slow components. At 23 °C slow activation proceeded at about the rate of rapid activation. The onset of the slow phase took longer at lower temperatures. Routine adenylate cyclase assay conditions (conversion of [32P]ATP to cyclic [32P]AMP) carried out without pretreatment probably characterized the rapidly activated component. The simplest kinetic model suggests not only the generally accepted two-step association reaction, but also implies the existence of more than one enzyme form, each of which is characterized by a separate activation rate. The complex kinetics of activation might be explained by a heterogeneous mixture of unassociated and preassociated nucleotide binding and catalytic subunits. 相似文献
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Martin Diatewa Yves Boulanger AndréJ.C. Stahl 《Biochemical and biophysical research communications》1982,106(2):520-525
The α and β subunits of yeast mitochondrial Phe-tRNA synthetase are separated and isolated by means of chromatography on DEAE-cellulose, after enzyme alkylation with iodoacetate. The comparison of amino acid compositions of yeast mitochondrial and cytoplasmic native Phe-tRNA synthetases and their components shows significant differences. Results indicate that the two enzymes are coded for by different nuclear genes. 相似文献