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1.
Incomplete ischemia of the spinal cord was produced in dogs by 40 min occlusion of the abdominal aorta that was followed by 5–40 min of recirculation. Amino acid incorporation into ribosomes in vitro in the presence of venous blood sera was estimated. The most significant reduction in incorporation was produced by sera of the dogs following a short recirculation period (5–10 min). No significant changes were observed at the end of the ischemic period nor at longer periods of recirculation. The decrease in incorporation might be the consequence of inactivation or absence of a substance stimulating polypeptide synthesis in vitro, normally present in blood sera of intact dogs, that temporarily loses its activity during recirculation. 相似文献
2.
Flagellar ultrastructure and flagella-associated antigens of Campylobacter fetus. 总被引:8,自引:3,他引:5
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Ultrastructural examinations of the flagellum of Compylobacter (Vibrio) fetus were performed throughout the growth cycle. Filament diameters, exceeding 17.6 nm during the exponential phase, were substantially greater than those reported for unsheathed flagella of other genera with the exception of Pseudomonas fluorescens. Filament diameters increased during growth, reaching a mean width of 21.2 nm in middle to late stationary phase. Internal flagellar structure, principally of the parallel lined variety, was observed during the later periods of growth but not during exponential or early stationary phase. Despite the unusually large filament sizes, no evidence of a flagellar sheath was observed after selected treatments (0.01 N HCl, 6 M urea, tris(hydroxymethyl) amino-methane-hydrochloride buffer, warm water) or examination of thin sections. To determine whether alterations in filament size and variable ability to demonstrate filament fine structure were correlated with progressive changes in serological activity, agglutination and immobilization tests were conducted with antisera directed against intact flagella, the principal flagellar antigen, the O antigen, and a superficial glycoprotein which has been found in association with the flagellum and the cell envelope. Significant differences in the serological activity of cells at different growth intervals were not noted with any of the sera employed. 相似文献
3.
Genetic tailoring of N-linked oligosaccharides: the role of glucose residues in glycoprotein processing of Saccharomyces cerevisiae in vivo 总被引:1,自引:0,他引:1
In higher eukaryotes a quality control system monitoring the folding state
of glycoproteins is located in the ER and is composed of the proteins
calnexin, calreticulin, glucosidase II, and UDP-glucose: glycoprotein
glucosyltransferase. It is believed that the innermost glucose residue of
the N- linked oligosaccharide of a glycoprotein serves as a tag in this
control system and therefore performs an important function in the protein
folding pathway. To address this function, we constructed Saccharomyces
cerevisiae strains which contain nonglucosylated (G0), monoglucosylated
(G1), or diglucosylated (G2) glycoproteins in the ER and used these strains
to study the role of glucose residues in the ER processing of
glycoproteins. These alterations of the oligosaccharide structure did not
result in a growth phenotype, but the induction of the unfolded protein
response upon treatment with DTT was much higher in G0 and G2 strains as
compared to wild-type and G1 strains. Our results provide in vivo evidence
that the G1 oligosaccharide is an active oligosaccharide structure in the
ER glycoprotein processing pathway of S.cerevisiae. Furthermore, by
analyzing N- linked oligosaccharides of the constructed strains we can
directly show that no general glycoprotein glucosyltransferase exists in S.
cerevisiae.
相似文献
4.
In the study behavior of molecular electrostatic potential, averaged local ionization energy, and reaction electronic flux along the reaction coordinate of hydration process of three representative Ru(II) and Pt(II) complexes were explored using both post-HF and DFT quantum chemical approximations. Previously determined reaction mechanisms were explored by more detailed insight into changes of electronic properties using ωB97XD functional and MP2 method with 6–311++G(2df,2pd) basis set and CCSD/6–31(+)G(d,p) approach. The dependences of all examined properties on reaction coordinate give more detailed understanding of the hydration process. Figure
The ALIE and MEP changes during cisplatin hydration 相似文献
5.
The protective effect of aminoguanidine on cerebral ischemic damage in the rat brain 总被引:8,自引:0,他引:8
Danielisová V Némethová M Burda J 《Physiological research / Academia Scientiarum Bohemoslovaca》2004,53(5):533-540
The NADPH-diaphorase (NADPH-d) histochemical technique is commonly used to localize the nitric oxide (NO) produced by the enzyme nitric oxide synthase (NOS) in neural tissue. The expression of inducible nitric oxide synthase (iNOS) is induced in the late stage of cerebral ischemia, and NO produced by iNOS contributes to the delay in recovery from brain neuronal damage. The present study was performed to investigate whether the increase in nitric oxide production via inducible nitric oxide synthase was suppressed by the administration of aminoguanidine, a selective iNOS inhibitor, as it follows a decrease of NADPH-diaphorase activity (a marker for NOS) after four-vessel occlusion used as an ischemic model. The administration of aminoguanidine (100 mg/kg i.p., twice per day up to 3 days immediately after the ischemic insult) reduced the number of NADPH-diaphorase positive cells to control levels. Our results indicated that aminoguanidine suppressed NADPH-diaphorase activity, and also decreased the number of NADPH-diaphorase positive cells in the CA1 region of the hippocampus following ischemic brain injury. 相似文献
6.
The 33 kDa protein of photosystem II is a low-affinity calcium- and lanthanide-binding protein 总被引:3,自引:0,他引:3
We have shown that the isolated 33 kDa protein of photosystem II contains one calcium and one lanthanide low-affinity binding site with binding constants (K(D)) on the order of 10(-5) M. Binding of calcium or lanthanides to this site induces conformational changes in the protein that manifest in fluorescence emission spectra of the protein, circular dichroism spectra, and calorimetric thermograms where the phase transitions are shifted to lower temperatures. The role of calcium binding to the 33 kDa protein in the attainment of its native structure and the significance of this interaction for the oxygen evolution process are discussed. 相似文献
7.
Burda K Kruk J Strzalka K Schmid GH 《Zeitschrift für Naturforschung. C, Journal of biosciences》2002,57(9-10):853-857
We have found that copper(II) ions at about equimolar Cu2+/photosystem II (PS II) reaction center proportions stimulate oxygen evolution nearly twofold. This high affinity Cu-binding site is different from the binding sites of Mn and Ca ions. The analysis of the Cu2+ content in PS II preparations isolated from wild-type tobacco and a tobacco mutant deficient in light-harvesting complex suggests that Cu2+ may be a native component of PS II and may take part in the oxygen evolution process. At higher concentrations, Cu2+ ions inhibit oxygen evolution and quench fluorescence. 相似文献
8.
Imbach T Grünewald S Schenk B Burda P Schollen E Wevers RA Jaeken J de Klerk JB Berger EG Matthijs G Aebi M Hennet T 《Human genetics》2000,106(5):538-545
Congenital disorders of glycosylation (CDG), formerly known as carbohydrate-deficient glycoprotein syndrome, represent a family of genetic diseases with variable clinical presentations. Common to all types of CDG characterized to date is a defective Asn-linked glycosylation caused by enzymatic defects of N-glycan synthesis. Previously, we have identified a mutation in the ALG6 alpha1,3 glucosyltransferase gene as the cause of CDG-Ic in four related patients. Here, we present the identification of seven additional cases of CDG-Ic among a group of 35 untyped CDG patients. Analysis of lipid-linked oligosaccharides in fibroblasts confirmed the accumulation of dolichyl pyrophosphate-Man9GlcNAc2 in the CDG-Ic patients. The genomic organization of the human ALG6 gene was determined, revealing 14 exons spread over 55 kb. By polymerase chain reaction amplification and sequencing of ALG6 exons, three mutations, in addition to the previously described A333 V substitution, were detected in CDG-Ic patients. The detrimental effect of these mutations on ALG6 activity was confirmed by complementation of alg6 yeast mutants. Haplotype analysis of CDG-Ic patients revealed a founder effect for the ALG6 allele bearing the A333 V mutation. Although more than 80% of CDG are type Ia, CDG-Ic may be the second most common form of the disease. 相似文献
9.
The xanthophyll cycle is one of the mechanisms protecting the photosynthetic apparatus against the light energy excess. Its action is still not well understood on the molecular level.Our model makes it possible to follow independently the kinetics of the two de-epoxidation steps occurring in the xanthophyll cycle: the conversion of violaxanthin into antheraxanthin and the conversion of antheraxanthin into zeaxanthin. Using a simple form of the transition rates of these two conversions, we model the time evolution of the concentration pattern of violaxanthin, antheraxanthin and zeaxanthin during the de-epoxidation process. The model has been applied to describe the reactions of de-epoxidation in a system of liposome membranes composed of phosphatidylcholine and monogalactosyldiacylglycerol. Results obtained within the model fit very well with the experimental data. Values of the transition probabilities of the violaxanthin conversion into antheraxanthin and the antheraxanthin conversion into zeaxanthin calculated by means of the model indicate that the first stage of the de-epoxidation process is much slower than the second one. 相似文献
10.
A human immunodeficiency virus prime-boost immunization regimen in humans induces antibodies that show interclade cross-reactivity and neutralize several X4-, R5-, and dualtropic clade B and C primary isolates
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Verrier F Burda S Belshe R Duliege AM Excler JL Klein M Zolla-Pazner S 《Journal of virology》2000,74(21):10025-10033
A human immunodeficiency virus (HIV) vaccine that will be useful in diverse geographic regions will need to induce a broad immune response characterized by cross-clade immunity. To test whether a clade B-based HIV candidate vaccine could induce interclade humoral responses, including neutralizing activity against primary HIV-1 isolates, sera were tested from recipients of a vaccine consisting of recombinant canarypox virus vCP205 and recombinant gp120(SF2). Serum antibodies exhibited strong immunochemical cross-reactivity with V3 peptides from clades B, C, and F, with weaker activity for several V3 peptides from clades A, D, G, and H; essentially no reactivity could be demonstrated with V3 peptides from clades E and O. Extensive cross-clade reactivity was also documented by enzyme-linked immunosorbent assay with all nine recombinant HIV envelope glycoproteins tested from clades B, D, and E. In addition, vaccinees' sera displayed significant neutralizing activity against 5 of 14 primary isolates tested, including one X4 virus and two dualtropic viruses (from clade B) and two R5 viruses (from clades B and C). This is the first demonstration of the induction by a candidate HIV vaccine constructed from clade B laboratory strains of HIV of neutralizing activity against R5 and clade C primary isolates. The data suggest that, by virtue of their ability to induce cross-clade immune responses, appropriately formulated HIV vaccines based on a finite number of HIV isolates may ultimately be able to protect against the wide range of HIV isolates affecting the populations of many geographic regions. 相似文献