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121.
Anders Sonesson Erik Jantzen Torill Tangen Ulrich Zähringer 《Archives of microbiology》1994,162(4):215-221
Lipopolysaccharides (LPS) from Legionella bozemanii serogroup 1 and Legionella longbeachae serogroup 1 were subjected to chemical analyses. The lipid A part of both LPSs contained 2,3-dideoxy-2,3-diamino-d-glucose as major constituents and d-glucosamine and glycerol as minor constituents of the sugar backbone structure. Both LPSs exhibited a very complex fatty acid composition. Twenty amide-linked 3-hydroxy fatty acids were detected in LPS of L. longbeachae, whereas seventeen were encountered in LPS of L. bozemanii. Both LPSs contained nine ester-linked nonhydroxy fatty acids and the unique long-chain fatty acids 27-oxo-octacosanoic acid, 29-oxotriacontanoic acid, heptacosane-1,27-dioic acid and nonacosane-1,29-dioic acid. SDS-PAGE showed that L. bozemanii produced smooth-form LPS, whereas L. longbeachae LPS was mainly of the R-type. Composition analyses were in accordance with these electrophoretic patterns. d-Quinovosamine and l-fucosamine constituted 80 mol% of the polysaccharide part of L. bozemanii LPS. Other sugars identified were d-glucosamine, d-mannose, d-glucose, l-rhamnose, d-glycero-d-manno-heptose, l-glycero-d-mannoheptose, 2-keto-3-deoxy-octonic acid and glycerol. The polysaccharide chain from LPS of L. longbeachae appeared to be shorter, but composed of the same sugars except l-fucosamine. Both LPSs contained glycerol phosphate and glucosamine phosphate and L. longbeachae LPS contained in addition glucose phosphate.Abbreviations
EI
Electron impact
-
GlcN3N
2,3-Diamino-2,3-dideoxy-d-glucose
-
HPAEC
High pH anion-exchange chromatography
-
Kdo
2-Keto-3-deoxy-octonic acid
-
LPS
Lipopolysaccharide
-
PCP
Phenol/chloroform/petroleum ether solvent
-
PED
Pulsed electrochemical detection
-
PS
Polysaccharide
-
TFA
Trifluoroacetyl
-
TMS
Trimethylsilyl 相似文献
122.
Molecular response of the lipid headgroup to bilayer hydration monitored by 2H-NMR. 总被引:7,自引:7,他引:0
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The effect of hydration on the conformation and dynamics of the phosphatidylcholine headgroup has been investigated by 2H-NMR measurements of liquid crystalline dioleoylphosphatidylcholine in multilamellar liposomes. Deuterium quadrupole splittings (delta nu Q) and spin-lattice relaxation rates (1/T1) were recorded for three selectively labeled headgroup segments (alpha, beta, and gamma) over the range of water/lipid mole ratios from 4 to 100. The smooth changes in delta nu Q and 1/T1 are found to essentially parallel each other and can be described by a single exponential decay function. Progressive hydration thus induces a concerted change in headgroup conformation together with an increase in its rate of motion (detected by delta nu Q and 1/T1, respectively). The enhanced mobility is partially due to a shift in the lipid phase transition temperature (as monitored by differential scanning calorimetry) and is furthermore attributed to an entropic contribution. It is concluded that the choline dipole becomes slightly raised in its average orientation into the aqueous layer and that the rate is increased at which the headgroup is fluctuating and protruding. The observed molecular changes can thus be accommodated within a model where the effective accessible headgroup volume expands with increasing hydration. 相似文献
123.
Yosepha Shahak Christof Klughammer Ulrich Schreiber Etana Padan Inge Herrman Günter Hauska 《Photosynthesis research》1994,39(2):175-181
The reduction by sulfide of exogenous ubiquinone is compared to the reduction of cytochromes in chromatophores of Rhodobacter capsulatus. From titrations with sulfide values for Vmax of 300 and 10 moles reduced/mg bacteriochlorophyll a·h, and for Km of 5 and 3 M were estimated, for decyl-ubiquinone-and cytochrome c-reduction, respectively. Both reactions are sensitive to KCN, as has been found for sulfide-quinone reductase (SQR) in Oscillatoria limnetica, which is a flavoprotein. Effects of inhibitors interfering with quinone binding sites suggest that at least part of the electron transport from sulfide in R. capsulatus employs the cytochrome bc
1-complex via the ubiquinone pool.Abbreviations BChl a
bacteriochlorophyll a
- DAD
diaminodurene
- decyl-UQ
decyl-ubiquinone
- LED
light emitting diode
- NQNO
2-n-nonyl-4-hydroxyquinoline-N-oxide
- PQ-1
plastoquinone 1
- SQR
sulfide-quinone reductase (E.C. 1.8.5.'.)
- UQ
ubiquinone 10
- Qc
the quinone reduction site on the cytochrome b
6
f/bc
1, complex (also termed Qi or Qr or Qn)
- Qs
the quinone reduction site on SQR
- Qz
quinol oxidation site on the b
6
f/bc
1, complex (also termed Qo or Qp) 相似文献
124.
Hanns Ulrich Seitz Dorothea Elisabeth Gärtner 《Plant Cell, Tissue and Organ Culture》1994,38(2-3):337-344
In contrast to undifferentiated cell suspension cultures of Digitalis lanata, photomixotrophic shoot cultures of Digitalis purpurea accumulate cardiac glycosides in substantial concentrations. They are used to investigate enzymes of the cardenolide pathway. All cardenolides are 5-configurated. The progesterone 5-reductase and the 3-hydroxysteroid-5-oxidoreductase are present in shoot cultures but not in undifferentiated cell cultures. These enzymes provide precursors for cardenolides, whereas the presence of the progesterone 5-reductase, also present in shoot cultures, is discussed with regard to its role in phytosterol biosynthesis and may be attributed to the general steroid pathway. The progesterone 5-reductase had an activity maximum during the early growth period seven days after onset of cultivation, whereas the corresponding progesterone 5-reductase activity was highest on day 11. The maximum cardenolide accumulation was after 24 days. The enzyme activities present in crude extracts from shoot cultures were characterized with regard to their requirements for NADPH and NADH, pH-optimum, temperature optimum, affinity to their substrates and their localization in the cell. The progesterone 5-reductase was purified 769-fold.Abbreviations DW
dry weight
- FW
fresh weight
- PVP
polyvinylpyrrolidone 相似文献
125.
Nucleotide sequence information from a partial genomic clone, a cDNA clone, a RACE clone and a PCR fragment was combined to reconstruct the first reported complete gene sequence encoding a large legumin subunit, designated LelB3. The length difference to the well-characterized major legumin subunits is caused by an extended glutamin/glutamic acid-rich region encoded by the C-terminal part of the chain. Amino acid sequence comparisons reveal that gene LelB3 is more closely related to B-type than to A-type legumin genes of Vicia faba. Gene LelB3 is a member of a small gene family as indicated by published (Pich and Schubert, Biol Zbl 112 (1993); 342–350) and limited own data. 相似文献
126.
Tn163 is a transposable element identified in Rhizobium leguminosarum bv. viciae by its high insertion rate into positive selection vectors. The 4.6 kb element was found in only one further R. leguminosarum bv. viciae strain out of 70 strains investigated. Both unrelated R. leguminosarum bv. viciae strains contained one copy of the transposable element, which was localized in plasmids native to these strains. DNA sequence analysis revealed three large open reading frames (ORFs) and 38 bp terminal inverted repeats. ORF1 encodes a putative protein of 990 amino acids displaying strong homologies to transposases of class 11 transposons. ORF2, transcribed in the opposite direction, codes for a protein of 213 amino acids which is highly homologous to DNA invertases and resolvases of class II transposons. Homology of ORF1 and ORF2 and the genetic structure of the element indicate that Tn163 can be classified as a class II transposon. It is the first example of a native transposon in the genus Rhizobium. ORF3, which was found not to be involved in the transposition process, encodes a putative protein (256 amino acids) of unknown function. During transposition Tn163 produced direct repeats of 5 bp, which is typical for transposons of the Tn3 family. However, one out of the ten insertion sites sequenced showed a 6 by duplication of the target DNA; all duplicated sequences were A/T rich. Insertion of Tn163 into the sacB gene revealed two hot spots. Chromosomes of different R. leguminosarum bv. viciae strains were found to be highly refractory to the insertion of Tn163. 相似文献
127.
Siegfried L. Krauss 《Oecologia》1994,97(2):256-264
The breeding system of the extremely diverse species Persoonia mollis (Proteaceae) was characterized to, firstly, assess its importance as a mechanism promoting diversity and, secondly, to investigate the mode of control over selective fruit abortion. Fruit quantity and quality was assessed following self-and outcross-pollination manipulations. Twenty percent of outcrossed flowers set fruit, compared to only 1% of flowers fertilized with self-pollen. Fruits produced by self-fertilization were 72% of the weight of cross-fertilized fruits. Fruits produced by self-fertilization were significantly fewer in number and lighter than fruits following natural pollination of unmanipulated flowers (17% fruit set), but outcrossed and naturally pollinated fruits were equivalent. Flower to fruit demography suggested that a post-zygotic mechanism may be preferentially selecting the most vigorous zygote genotypes, as ovary abscission occurs mostly between 4 and 30 weeks after pollination, regardless of pollen source. Self-pollen tube growth was found to be inhibited within the styly, while pollen tubes were found in the ovary for 50% of all outcrossed flowers. These data suggest that a pre-zygotic pseudo self-incompatibility mechanism is the cause of low fruit set following self-pollination. The breeding system of P. mollis was found to promote outbreeding, with an emphasis on flexibility and post-zygotic choice following pre-zygotic pseudo self-incompatibility.Publication no. 120 from the Ecology and Genetics Group of the University of Wollongong 相似文献
128.
Heber Ulrich; Wagner Ute; Kaiser Werner; Neimanis Spidola; Bailey Karen; Walker David 《Plant & cell physiology》1994,35(3):479-488
Induction of photosynthesis in leaves was prolonged, and steadystate photosynthesis was inhibited by very high CO2 concentrationswhich cause cytoplasmic acidification. Prolonged exposure tohigh CO2 relieved initially observed inhibition of photosynthesisat least partially. The sensitivity of carbon assimilation tohigh CO2 was different in different plant species. Acidificationby CO2 (or subsequent alkalization) was detected by measuringrapid CO2-release from the tissue and by monitoring fluorescenceof pH-indicating dyes which had been fed to the leaves throughthe petiole. The results indicate that two different mechanismsoperate in leaves to achieve and maintain pH homeostasis. Rapidand efficient pH-adjustment is provided by proton/cation exchangeacross the tonoplast. Slower and less efficient regulation occursby formation or consumption of base. In the presence of highCO2 concentrations, protons are pumped from the cytosol intoalready acidic vacuoles. In turn, vacuolar cations replace exportedprotons in the cytosol permitting bicarbonate accumulation andincreasing the pH of the acidified cytosol. Similarly effectiveand fast proton/cation exchange relieves acid-stress in thechloroplast stroma and permits photosynthesis to proceed withhigh quantum efficiency or high light-saturated rates in thepresence of CO2 concentrations which would, in the absence offast cytoplasmic pH regulation, inhibit photosynthesis. By inference,proton/cation exchange must also occur across the mitochondrialboundary. After cytoplasmic pH adjustment in the presence ofhigh CO2, removal of CO2 results in transient cytoplasmic alkalizationand, subsequently, in the return of cytoplasmic pH values tolevels observed prior to acid-stress. In addition to fast pHregulation by rapid proton/cation exchange across biomembranes,slow base production (e.g. NH3-formation) also contributes torelieving acid stress. Base produced in the presence of highCO2 is rapidly consumed after removal of CO2. Implications of the findings in regard to forest damage by potentiallyacidic air pollutants such as SO2 are briefly discussed. (Received November 8, 1993; Accepted February 3, 1994) 相似文献
129.
Photosynthetic characteristics of transgenic tobacco (Nicotiana tabacum L.) plants with a soluble pyrophosphatase in the cytosol of their leaf cells were compared to those of wild-type plants. Although the development of the transgenic plants was somewhat retarded compared to the wild type, as shown by stunted growth and delayed flowering, photosynthetic responses were comparable in transgenic and wild-type leaves of similar physiological age. In particular, light-dependent proton transport into the vacuoles of leaf mesophyll cells was not decreased in leaves of the transgenic plants, which did not contain pyrophosphate in the cytosol owing to the presence of a soluble pyrophosphase. This shows that light-stimulated proton pumping did not require the pumping activity of the tonoplast pyrophosphatase. Apparently, light-stimulated proton pumping can be based solely on the activity of the tonoplast ATPase.Abbreviation CDCF
5-(and 6-)arboxy-2,7-dichlorofluorescein
This work was supported within the Sonderforschungsbereiche 176 and 251 of the University of Würzburg. 相似文献
130.
Liang Ru Shi Dirk Eichelbauer Franz Borchard Herbert Jürgens Ulrich Göbel E. Marion Schneider 《Cancer immunology, immunotherapy : CII》1994,38(3):208-213
A selection of 16 monoclonal antibodies has been produced against a fresh Ewing's sarcoma (ES) tumor mixed with a permanent ES cell line. The majority of antibodies identify an 80-kDa molecule, which is not detected on healthy tissues except on certain cultured monocytes. One antibody recognize the CD2 ligand MIC2 and 2 antibodies (numbers 13 and 16) define a higher-molecular-mass antigen. Antibody 16 is also expressed on mesenchymal fibroblasts of bone marrow or fetal origin. Tumorspecific antigen expression is potentially linked to the chromosome 22 abnormality decribed in Ewing's sarcoma. 相似文献