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161.
162.
Yoshihiko Sawa Ken-ichiro Shibata Mamoru Noda Tsuguo Watanabe 《Microbiology and immunology》1994,38(4):257-262
A 90 kDa protein of Mycoplasma salivarium was released from cell membranes of the organism with Triton X-100 and purified by ion-exchange chromatography and chromatofocusing. The protein was eluted at pH 5.5 by chromatofocusing. The protein was shown to react with the Fc fragments of IgG from human and nine different animal species and did not distinguish between IgG from different species, while protein A, tested for comparative purposes, displayed a strong specificity for human and swine IgG. Furthermore, the protein reacted with antigen specific goat IgG (specific for gamma chains of human IgG), sheep red blood cells (SRBC) sensitized with rabbit antiserum to SRBC, that is, the Fc part of rabbit IgG, and concanavalin A as well. These findings may suggest that the protein is a lectin which binds the carbohydrate moiety of the Fc part of IgG. 相似文献
163.
Kumar B. Reddy Barbara A. Hocevar Philip H. Howe 《Journal of cellular biochemistry》1994,56(3):418-425
Transforming growth factor β1 (TGFβ1) inhibits epithelial cell proliferation late in the G1 phase of the cell cycle. We examined the effect of TGFβ1 on known late G1 cell cycle regulators in an attempt to determine the molecular mechanism of growth inhibition by this physiological inhibitor. The results demonstrate the TGFβ1 inhibits the late G1 and S phase specific histone H1 kinase activity of p33cdk2. This inhibitiion is not dur to TGFβ1's effect on p33cdk2 synthesis, but rather due to its negative effect on the late G1 phosphorylation of p33cdk2. It is also shown that TGFβ1 inhibits both late G1 cyclin A and cyclin E associated histon H1 kinase activities. The inhibitor has no effects on the synthesis of cyclin E but to inhibit the synthesis of cyclin A protein in a cell cycle dependent manner. If TGFβ1 is added to cells which have progressed futher than 8 hours into G1, then it is without inhibitory effect on cyclin A synthesis. These effect on TGFβ1 on late G1 cell cycle regulators correlate well with its inhibitory effects on cellular growth and suggest that these G1 cyclin dependent kinases might serve as targets for TGFβ1-mediated growth arrest. 相似文献
164.
Twenty-four weanling male Wistar rats were divided into four groups fed diets containing adequate or deficient levels of selenium
(0.5 ppm [+ Se] or <0.02 ppm [−Se] and protein (15% [+Pro] or 5% [−Pro]), but adequate levels of all other nutrients for 4
wk to determine the effects of Se deficiency and protein deficiency on tissue Se and glutathione peroxidase (GSHPx) activity
in rats. Plasma, heart, liver, and kidney Se and GSHPx were significantly lower in Se-deficient groups in relation to Se-sufficient
groups. In Se-deficient groups, Se and GSHPx were significantly higher in −Se−Pro rats in heart, liver, and kidney. Data analysis
showed that there were significant interaction effects between dietary Se and protein on Se and GSHPx of rats. It is assumed
that under the condition of Se deficiency. a low level of protein may decrease Se and GSHPx utilization, increase GSHPx synthesis,
and result in Se redistribution. This could account for high levels of Se and GSHPx in the −Se−Pro rats compared to −Se+Pro
rats. 相似文献
165.
Evaluation of the role of State transitions in determining the efficiency of light utilisation for CO2 assimilation in leaves 总被引:2,自引:0,他引:2
Wheat leaves were exposed to light treatments that excite preferentially Photosystem I (PS I) or Photosystem II (PS II) and induce State 1 or State 2, respectively. Simultaneous measurements of CO2 assimilation, chlorophyll fluorescence and absorbance at 820 nm were used to estimate the quantum efficiencies of CO2 assimilation and PS II and PS I photochemistry during State transitions. State transitions were found to be associated with changes in the efficiency with which an absorbed photon is transferred to an open PS II reaction centre, but did not correlate with changes in the quantum efficiencies of PS II photochemistry or CO2 assimilation. Studies of the phosphorylation status of the light harvesting chlorophyll protein complex associated with PS II (LHC II) in wheat leaves and using chlorina mutants of barley which are deficient in this complex demonstrate that the changes in the effective antennae size of Photosystem II occurring during State transitions require LHC II and correlate with the phosphorylation status of LHC II. However, such correlations were not found in maize leaves. It is concluded that State transitions in C3 leaves are associated with phosphorylation-induced modifications of the PS II antennae, but these changes do not serve to optimise the use of light absorbed by the leaf for CO2 assimilation.Abbreviations Fm, Fo, Fv
maximal, minimal and variable fluorescence yields
- Fm, Fv
maximal and variable fluorescence yields in a light adapted state
- LHC II
light harvesting chlorophyll a/b protein complex associated with PS II
- qP
photochemical quenching
- A820
light-induced absorbance change at 820 nm
- PS I, PS II
relative quantum efficiencies of PS I and PS II photochemistry
- CO
2
quantum yield of CO2 assimilation 相似文献
166.
167.
Methenamine-Silver Staining: a Simple and Sensitive Staining Method for Senile Plaques and Neurofibrillary Tangles 总被引:1,自引:0,他引:1
Chie Haga Kenji Ikeda Kiyoshi Iwabuchi Haruhiko Akiyama Hiromi Kondoh Kenji Kosaka 《Biotechnic & histochemistry》1994,69(5):295-300
An improved methenamine-silver impregnation method is presented which exhibits sensitivity for amyloid substances comparable to that of anti-β protein immunostaining. In optimally treated sections, this technique stained both β-amyloid deposits and neurofibrillary tangles, which are known to have a β-pleated structure. This simple procedure allows a large number of sections to be stained for routine examination. 相似文献
168.
K. Pomeroy D. C. W. Brown Y. Takahata 《In vitro cellular & developmental biology. Plant》1994,30(4):196-203
Summary Microspore-derived embryos fromBrassica napus cv. Topas (low erucic acid) and Reston (high erucic acid) were subjected to treatment with abscisic acid (ABA) during late-stage
embryo development and then dried under controlled relative humidities to mature dry seed levels of moisture. Exogenously
medium-supplied ABA arrested growth and development, reduced moisture content, increased total fatty acids on a dry weight
basis, and stimulated systhesis of proteins in microspore-derived embryos. ABA also resulted in a higher proportion of 22∶1
in cv. Reston (high 22∶1) and increased the level of fatty acid unsaturation in cv. Topas (low 22∶1). The accumulation of
two proteins that co-migrated with cruciferin and napin on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional
gels were also promoted by exposure to ABA, and the degree of accumulation was dependent on the concentration and time of
application of ABA. Controlled desiccation of microspore embryos, used to simulate normal maturation and dehydration of zygotic
embryos during seed development, did not seem to cause an increase of either storage proteins, total fatty acids, or 22∶1
(in cv. Reston), suggesting that dehydration is not a prerequisite for these processes, at least in culturedBrassica embryos. 相似文献
169.
Maura Turriani Rossana Pesi Antonella Nardone Gino Turchi Francesco Sgarrella Pier Luigi Ipata Maria Grazia Tozzi 《Journal of biochemical and molecular toxicology》1994,9(1):51-57
Nucleoside phosphotransferase acting on inosine and deoxyinosine has been partially purified from cultured Chinese hamster lung fibroblasts (V79). The activity is associated with a cytosolic 5′-nucleotidase acting on IMP and deoxyIMP. The transfer of the phosphate group from IMP to inosine catalyzed by this enzyme was activated by ATP and 2,3-bisphosphoglycerate. Inosine, deoxyinosine, guanosine, deoxyguanosine, and the nucleoside analogs 2′,3′-dideoxyinosine and 8-azaguanosine are substrates, while adenosine and deoxyadenosine are not. IMP, deoxyIMP, GMP, and deoxyGMP are the best phosphate donors. The cytosolic 5′-nucleotidase/phosphotransferase substrate, 8-azaguanosine, was found to be very toxic for cultured fibroblasts (LD50 = 0.32 μM). Mutants resistant to either 8-azaguanosine and the correspondent base 8-azaguanine were isolated and characterized. Our results indicated that the 8-azaguanosine-resistant cells were lacking both cytosolic 5′-nucleotidase and hypoxanthine-guanine phosphoribosyltransferase, while 8-azaguanine resistant cells were lacking only the latter enzyme. Despite this observation, both mutants displayed 8-azaguanosine resistance, thus indicating that cytosolic 5′-nucleotidase is not essential for the activation of this nucleoside analog. 相似文献
170.
Graeme Milligan 《Journal of neurochemistry》1993,61(3):845-851
Abstract: Levels of the guanine nucleotide binding proteins G11α and Gqα, which produce receptor regulation of phosphoinositidase C., were measured immunologically in 13 regions of rat central nervous system. This was achieved by immunoblotting membranes from these regions with antisera (CQ series) that identify these two polypeptides equally, following separation of the membranes using sodium dodecyl sulphate-polyacrylamide gel electrophoresis conditions that can resolve Gqα and G11α. In all regions examined, Gqα was more highly expressed than G11α. Ratios of levels of Gqα to G11α varied between the regions from 5:1 to 2:1. Quantitative measurements of the levels of Gqα and G11α in each region were obtained by comparison with known amounts of purified liver Gqα and G11α and with E. coli expressed recombinant Gqα. Areas that expressed Gqα highly included olfactory bulb (930 ng/ mg of membrane protein), frontal cortex (700 ng/mg of membrane protein), parietal occipital cortex (670 ng/mg of membrane protein), caudate putamen (1,003 ng/mg of membrane protein), hippocampus (1,045 ng/mg of membrane protein), hypothalamus (790 ng/mg of membrane protein), and cerebellum (950 ng/mg of membrane protein). More modest levels were observed in thalamus (450 ng/mg of membrane protein), pituitary (480 ng/mg of membrane protein), optic chiasma (330 ng/mg of membrane protein), and spinal cord (350 ng/mg of membrane protein). Gna was more evenly expressed with values ranging from about 170 ng/mg of membrane protein in spinal cord and optic chiasma to close to 300 ng/mg of membrane protein in regions expressing high levels of Gqα. A third polypeptide could be identified by the CQ antisera in all brain regions. The possibility that this polypeptide is the α subunit of G14 is discussed. 相似文献