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11.
The tonoplast amino-acid transporter of barley (Hordeum vulgare L.) mesophyll cells was functionally reconstituted by incorporating solubilized tonoplast membranes, vacuoplast membranes or tonoplast-enriched microsomal vesicles into phosphatidylcholine liposomes. (i) Time-, concentration- and ATP-dependence of amino-acid uptake were similar to results with isolated vacuoles. Although the orientation of incorporation could not be controlled, the results indicate that the transporter functions as a uniport system which allows regulated equilibration by diffusion between the cytosolic and vacuolar amino-acid pools. (ii) The ATP-modulated amino-acid carrier was also successfully reconstituted from barley epidermal protoplasts and Valerianella or Tulipa vacuoplasts, indicating its general occurrence. (iii) Fractionation of solubilized tonoplasts by size-exclusion chromatography followed by reconstitution of the fractions for glutamine transport gave two activity peaks: the first eluted in the region of high-molecular-mass vesicles and the second at a size of 300 kDa for the Triton-protein micelle.Abbreviation SDS-PAGE
sodium dodecyl sulfate-polyacryl-amide gel electrophoresis
This work was part of our research efforts within the Sonderforschungsbereich 176 of the University. We gratefully acknowledge experimental support by Marion Betz and valuable discussions with Professors U. Heber and U.-I. Flügge and Dr. Armin Gross (University of Würzburg) and Dr. E. Martinoia (ETH, Zürich, Switzerland). 相似文献
12.
Streptomycetes possess peptidyl-prolyl cis-trans isomerases that strongly resemble cyclophilins from eukaryotic organisms 总被引:2,自引:0,他引:2
Andreas Pahl Monika Ühlein Holger Bang Wilhelm Schlumbohm Ullrich Keller 《Molecular microbiology》1992,6(23):3551-3558
A functionally active 17.5 kDa peptidyl-prolyl cis-trans isomerase was purified to homogeneity from Streptomyces chrysomallus, a Gram-positive filamentous bacterium. Characterization of the enzyme revealed inhibition and binding characteristics, against the immunsuppressive drug cyclosporin A, which were similar to cyclophilins from eukaryotes such as mammals, plants, fungi and yeasts, but different from those of cyclophilins from enterobacteria such as Escherichia coli. The amino acid sequence of the S. chrysomallus cyclophilin, as deduced from the gene sequence, revealed a striking degree of amino acid sequence identity with the corresponding 17 kDa proteins of humans (66%), Neurospora (70%) and yeast (69%). Comparison with cyclophilin sequences from the Gram-negative enterobacteria revealed much less homology (25% identity with E. coli b, 23% identity with E. coli a). Cyclophilin was detected in each of the four other Streptomyces species tested. The cyclophilins from the various streptomycetes differed in size, varying between 17 and 20.5 kDa. The cyclophilins were abundant in the Streptomyces cells, and present throughout growth. 相似文献
13.
Morphological evidence for a close interaction of chromaffin cells with cortical cells within the adrenal gland 总被引:3,自引:0,他引:3
Stefan R. Bornstein Monika Ehrhart-Bornstein Henning Usadel Michael Böckmann Werner A. Scherbaum 《Cell and tissue research》1991,265(1):1-9
Summary The adrenal medulla appears to exert a regulatory influence on adrenocortical steroidogenesis. We have therefore studied the morphology of rat, porcine and bovine adrenals in order to characterize the contact zones of adrenomedullary and adrenocortical tissues. The distribution of chromaffin cells located within the adrenal cortex and of cortical cells located within the adrenal medulla was investigated. Chromaffin cells were characterized by immunostaining for synaptophysin and chromogranin A, both being considered specific for neuroendocrine cells. Cortical cells were characterized by immunostaining for 17-hydroxylase, an enzyme of the steroid pathway. Cellular contacts of chromaffin cells and cortical cells were examined at the electron microscopical level. In rat and porcine adrenals, rays of chromaffin cells, small cell clusters and single chromaffin cells or small invaginations from the medulla could be detected in all three zones of the cortex. Chromaffin cells often spread in the subcapsular space of the zona glomerulosa. In porcine and bovine adrenals, 17-hydroxylase immunoreactive cells were localized within the medulla. Single cortical cells and small accumulations of cells were spread throughout this region. At the ultrastructural level, the chromaffin cells located within the cortex in pig and rat adrenals formed close cellular contacts with cortical cells in all three zones. Our morphological data provide evidence for a possible paracrine role of chromaffin cells; this may be important for the neuroregulation of the adrenal cortex. 相似文献
14.
A bioluminescent assay for the determination of phosphoenolpyruvate carboxykinase activity in nanogram-sized tissue samples 总被引:1,自引:0,他引:1
Monika Wimmer 《Analytical biochemistry》1988,170(2):376-381
A highly specific and sensitive assay for the determination of phosphoenolpyruvate carboxykinase (PEPCK) in nanogram-sized tissue samples is described. This test system is based on the stoichiometric transformation of phosphoenolpyruvate into ATP. In a subsequent step ATP is quantified by bioluminescent techniques. The applicability of this assay system is shown by measurements in liver samples with normal and high PEPCK activity levels. 相似文献
15.
A plasmodial alpha-tubulin cDNA from Physarum polycephalum. Nucleotide sequence and comparative analysis 总被引:5,自引:0,他引:5
Günter Krämmer Monika Singhofer-Wowra Klaus Seedorf Melvyn Little Tim Schedl 《Journal of molecular biology》1985,183(4):633-638
As the first step towards correlating structure and function of tubulin in the slime mold Physarum polycephalum we have elucidated the nucleotide sequence of a cDNA that appears to code for all but the last 25 to 30 C-terminal amino acids of a plasmodial alpha-tubulin. Differences in amino acid sequence from those of other alpha-tubulins are distributed fairly evenly throughout the sequence, although a relatively extensive conserved region is found in position 396 to 426 near the C terminus. A small region in position 298 to 307 contains a cluster of amino acid residues unique to Physarum alpha-tubulin. The sequence is 70% homologous to two yeast alpha-tubulins and about 83% homologous to five animal alpha-tubulins. A comparison of the homologies of all the known alpha-tubulins indicates that a large decrease in the accepted point mutation rate has occurred during the evolution of the metazoa, suggesting a major functional specialization of microtubules. 相似文献
16.
Identification and isolation of the primary aggregation factor from the cell membrane of the sponge Geodia cydonium 总被引:1,自引:0,他引:1
Prof. Dr. Werner E. G. Müller Jürgen Conrad Rudolf K. Zahn Monika Gramzow Branko Kurelec Gerhard Uhlenbruck 《Molecular and cellular biochemistry》1985,67(1):55-64
Summary The primary aggregation factor (pAF) of sponge cells is a glycoprotein that is firmly associated with the cell membrane. Polyspecific antibodies (anti-GM) prepared from sera raised against membranes of cells from the siliceous sponge Geodia cydonium were found to inhibit initial aggregation of homologous cells. The inhibition of aggregation, caused by anti-GM was neutralized by pAF. The pAF had been successfully solubilized and enriched by affinity chromatography, gel filtration and density gradient centrifugation, if checked by polyacrylamide gel electrophoresis in the presence of urea. The Mr of the native pAF was approximately 40 000 as estimated by gel filtration; under denaturing conditions three protein species (Mr: 16 500, 15 500 and 13 500) were identified in the pAF preparation. The pAF was precipitable by Ca++ and did not cross-react with antisera against homologous purified secondary aggregation factor and lectin. It is mainly composed of protein (48.0%) and carbohydrate (50.2%). The isolated pAF restored the aggregation potency not only of factor-depleted Geodia cells but also of cells from other Demospongiae. However, the pAF displayed no aggregation enhancing effect on urea-treated cells from species belonging to the Calcispongiae or Hexactinellida. We hypothesize that in contrast to the secondary aggregation, the initial aggregation of Geodia cells is mediated by the one-component system, the bivalent and bifunctional pAF. 相似文献
17.
Enhancement of cadmium effects on growth and nutrient composition of birch (Betula pendula) by buthionine sulphoximine (BSO) 总被引:5,自引:0,他引:5
Gussarsson Monika; Asp Hkan; Adalsteinsson Sveinn; Jensn Paul 《Journal of experimental botany》1996,47(2):211-215
Binding of Cd to non-specific metal-binding peptides (phytochelatins)in birch roots has been suggested as an explanation for toleranceto Cd toxicity in birch (Betula pendula). In the present study,the tolerance of birch roots to Cd was further investigatedby using buthionine sulphoximine (BSO) as an inhibitor of phytochelatinsynthesis. Birch seedlings, grown in nutrient solution at pH4.2, were exposed to 0 or 2 µM CdCl2 combined with 0 or0.1 mM BSO for 6 d. Plant growth (fresh weight increase andshoot to root dry weight ratio) and the nutrient compositionin fine roots, whole roots and shoots were determined. The effectsof Cd on growth confirms the results of earlier studies on birch,suggesting a reduced shoot growth, but preserved or stimulatedroot growth. When Cd and BSO were combined, overall plant growthwas severely reduced. BSO was also shown to aggravate Cd-inducedreductions of root and shoot concentrations of K, Ca and Mgbut to impede the accumulation of Cd. The results suggest that phytochelatins participate in protectingthe root against Cd interferences with growth, possibly by restrictingCd-induced changes in the nutrient composition of the plant. Key words: Betula pendula, buthionine sulphoximine, cadmium, phytochelatins, roots, tolerance 相似文献
18.
The ultrastructure of the body cuticle in species of six of seven representative genera of Stilbonematinae (Eubostrichus, Catanema, Laxus, Robbea, Leptonemella, and Stilbonema) was investigated using SEM and TEM techniques. Additionally, one species of Spirinia (Spiriniinae) and one of Desmodora (Desmodorinae) were studied for outgroup comparison. The body cuticle of all investigated stilbonematids shows a consistent
pattern composed of specific elements in a characteristic arrangement to each other. This pattern does not occur in Stilbonematinae
alone, but also in Desmodorinae and Spiriniinae. Furthermore, a comparison within the Desmodorida reveals that this cuticular
pattern apparently is present in the cuticle of representatives of Monoposthiidae, Epsilonematidae, and Draconematidae. The
present results lead to the following conclusions: (1) the cuticle of Stilbonematinae contains no autapomorphic characters
for this taxon, (2) there is a common cuticular pattern within the Desmodorida, and (3) this pattern is an autapomorphic character
for the order Desmodorida.
Accepted: 4 February 1996 相似文献
19.
Pseudomonas sp. strain 267 isolated from soil promoted growth of different plants under field conditions and enhanced symbiotic nitrogen fixation in clover under gnotobiotic conditions. This strain produced pyoverdine-like compound under low-iron conditions and secreted vitamins of the B group. The role of fluorescent siderophore production in the beneficial effect of strain 267 on nodulated clover plants was investigated. Several non-fluorescent (Pvd-) Tn5 insertion mutants of Pseudomonas sp. strain 267 were isolated and characterized. The presence of Tn5 insertions was confirmed by Southern analysis of EcoRI digested genomic DNA of each derivative strain. The siderophore-negative mutants were compared to the parental strain with respect to their growth promotion of nodulated clover infected with Rhizobium leguminosarum bv. trifolii 24.1. We found that all isolated Pvd- mutants stimulated growth of nodulated clover plants in a similar manner to the parental strain. No consistent differences were observed between strain 267 and Pvd- derivatives strains with respect to their plant growth promotion activity under gnotobiotic conditions.Dr Deryto died in august 1994 相似文献
20.
Gábor Kocsy Monika Brunner Adrian Rüegsegger Peter Stamp Christian Brunold 《Planta》1996,198(3):365-370
The effect of chilling on enzymes, substrates and products of sulfate reduction, gultathione synthesis and metabolism was studied in shoots and roots of maize (Zea mays L.) genotypes with different chilling sensitivity. At full expansion of the second leaf, chilling at 12 °C inhibited dry weight increase in shoots and roots compared to controls at 25 °C and induced an increase in adenosine 5-phosphosulfate sulfotransferase and -glutamylcysteine synthetase (EC 6.3.2.2) activity in the second leaf of all genotypes tested. Glutathione synthetase (EC 6.3.2.3) activity was about one order of magnitude higher than -glutamylcysteine synthetase activity, but remained unchanged during chilling except for one genotype. During chilling, cysteine and glutathione content of second leaves increased to significantly higher levels in the two most chilling-tolerant genotypes. Comparing the most tolerant and most sensitive genotype showed that chilling induced a greater incorporation of35S from [35S]sulfate into cysteine and glutathione in the chilling-tolerant than in the sensitive genotype. Chilling decreased the amount of35S-label incorporated into proteins in shoots of both genotypes, but had no effect on this incorporation in the roots. Glutathione reductase (EC 1.6.4.2) and nitrate reductase (EC 1.6.6.1) activity were constitutively higher in the chilling-tolerant genotypes, but showed no changes in most examined genotypes during 3 d at 12 °C. Our results indicate that in maize glutathione is involved in protection against chilling damage.Abbreviations APSSTase
adenosine 5-phosphosulfate sulfotransferase
- EC
-glutamylcysteine
- GR
glutathione reductase
- OSH
glutathione
- NR
nitrate reductase
We thank M. Suter for preparing [35S]adenosine 5-phosphosulfate, Dr. A. Fleming (both our Institute) for correcting the English and M. Soldati (Eschlikon, Switzerland) for his help with the plant material. This work was supported by COST 814 Crop development for the wet and cool regions of Europe. 相似文献