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31.
Norma J. Greenfield Mussadeq Hussain John Lenard 《Biochimica et Biophysica Acta (BBA)/General Subjects》1987,926(3)
The vacuoles of logarithmic and stationary stage cells were compared by 31P-NMR with regard to pH, orthophosphate (Pi) content and average size of polyphosphate. The vacuoles of stationary cells had lower pH higher Pi content, and polyphosphates of longer average chain lenght, although total polyphosphate content was about the same as in logarithmic cells. The lower vacuolar pH in stationary cells was the major cause of a larger cytoplasmic-vacuolar pH gradient. Addition of NH4Cl, (NH4)2SO4, methylamine or amantadine at pH 8 to cells in either stage caused an icnrease in both cytoplasmic and vacuolar pH, with little or no change in the cytoplasmic-vacuolar pH gradient. However, the administration of ammonium salts to the cells at pH 8.0 resulted in rapid hydrolysis of the intravacuolar polyphosphate to tripolyphosphate and Pi, with attendant redistribution of Pi between the vacuolar and cytoplasmic compartments. 相似文献
32.
It is an accepted hypothesis that the nerve growth factor protein (NGF) plays an important role in the development of vertebrate sympathetic and sensory ganglia and has effects on some central neurons. The best known NGF species is that isolated from the mouse submaxillary gland, MSG-NGF. MSG-NGF can be isolated as a subunit containing protein, 7S-NGF, made up of three dissimilar subunits called alpha-, beta-, and gamma-NGF. Beta-NGF is the biologically active subunit and its synthesis in vivo and in vitro has been demonstrated. Less is known about the synthesis of the alpha- and gamma-NGF or the assembly of the subunits into the 7S complex. In order to develop a clonal model system for the study of NGF synthesis, processing and secretion, affinity chromatography techniques were applied to cell extracts of S180 mouse sarcoma, a cell line known to synthesize NGF. After incubating S180 cells in35S-Methionine, cell extracts were exposed to antibody directed against alpha-NGF, gamma-NGF or beta-NGF covalently bound to Sepharose beads in order to elute and characterize the desired NGF subunits. Parallel experiments using immunoabsorbed [35S]Methionine-beta-NGF were carried out in the presence or absence of excess NGF, in order to demonstrate the specificity of this procedure. Affinity chromatography with a substrate analogue to arginine ester bound to Sepharose beads was also used to isolate de novo synthesized gamma-NGF. We were able to show that the S180 line synthesized alpha-, beta-, and gamma-NGF indistiguishable from alpha-, beta-, and gamma-NGF isolated from mouse submaxillary gland in terms of antigenic and physicochemical properties, and biological and enzymatic activities. These results are consistent with the hypothesis that NGF is synthesized, assembled and secreted by a single cell type.Special Issue dedicated to Dr. E. M. Shooter and Dr. S. Varon. 相似文献
33.
Marina Lotti Michael Noah Marina Stöffler-Meilicke Georg Stöffler 《Molecular & general genetics : MGG》1989,216(2-3):245-253
Summary Ribosomal proteins L4, L5, L20 and L25 have been localized on the surface of the 50S ribosomal subunit of Escherichia coli by immuno-electron microscopy. The two 5S RNA binding proteins L5 and L25 were both located at the central protuberance extending towards its base, at the interface side of the 50S particle. L5 was localized on the side of the central protuberance that faces the L1 protuberance, whereas L25 was localized on the side that faces the L7/L12 stalk. Proteins L4 and L20 were both located at the back of the 50S subunit; L4 was located in the vicinity of proteins L23 and L29, and protein L20 was localized between proteins L17 and L10 and is thus located below the origin of the L7/L12 stalk. 相似文献
34.
Atsuko Matsuoka Akiko Hirosawa Shinasku Natori Shigeo Iwasaki Toshio Sofuni Motoi Ishidate Jr. 《Mutation research》1989,215(2):179-185
The chromosomal aberration test using a Chinese hamster lung cell line (CHL) was carried out on ptaquiloside and its related compounds, hypoloside B, hypoloside C, illudin M and illudin S. Ptaquiloside induced chromosomal aberrations at doses as low as 4.5 μg/ml (0.0113 mM). The clastogenic effect was ph-dependent. The same activity was observed at a 90-fold higher dose at pH 5.3 in the culture medium compared with the activity at pH 74. or pH 8.0. Both hypoloside B and hypoloside C were also clastogenic at almost the same dose levels as that of ptaquiloside. Illudin M and illudin S were also potet clastogens and induced aberrations at much lower doses than ptaquiloside. These results suggest that the clastogenic effect is involved in the mechanism of carcinogenic potency of ptaquiloside in animals. 相似文献
35.
In vivo effect of abscisic acid (ABA) on photosynthetic oxygen evolution was investigated in barley chloroplasts. The most important kinetic parameters of O2-producing reactions were changed. The results show inhibition of the O2-flash yields at ABA concentrations of 10 mol/l and 100 mol/l and an increase in the degree of damping of the oscillations. ABA has a marked effect on the distribution of the oxygenevolving centers in S0 and S1 states and on sum of the centers (S0+S1) estimated according to the Kok model. In addition, the amplitude and the shape of the initial oxygen burst under continuous illumination are also significantly altered. At a concentration of 100 mol/l, ABA strongly inhibits Hill reaction activity measured by DCPIP reduction. The results cannot be explained by the hypothesis of socalled stomata effect. On the other hand, no effects were observed on the investigated parameters in experiments involving ABA applied in vitro to isolated chloroplasts. It is hypothesized that ABA disrupts the granal chloroplasts structure and raises the degree of participation of the cooperative mechanism of O2-evolution connected with the functioning of PS II centers in the stroma situated thylakoids.Abbreviations DCPIP
2,6-Dichlorophenolindophenol
- DCMU
3-(3,4-dichlorophenil)-1,1-dimethylurea
- HEPES
N-2-Hydroxyethylpiperazine-N-2-ethane sulfonic acid
- PSII
photosystem II
- RubisCO
Ribulose-1,5-bis-phosphate carboxylase-oxygenase 相似文献
36.
眼镜蛇科蛇毒对S180,EAC腹水癌治疗作用研究 总被引:1,自引:0,他引:1
本文报道金环蛇、扁颈蛇、眼镜蛇、银环蛇蛇毒及其细胞毒对小鼠S180,EAC腹水癌的治疗作用。结果表明,蛇毒及其细胞毒在体外有明显杀灭癌细胞作用,体内有较明显的治疗作用,动物存活时间延长,接种率降低。肿瘤细胞呈现不同程度形态变化,主要为膜破裂,坏死等。治疗效应由强到弱为金环蛇毒,扁颈蛇毒,金环蛇细胞毒,眼镜蛇毒,眼镜蛇细胞毒。银环蛇毒无作用。 相似文献
37.
38.
Kiyoshi Takahashi Tadashi Yoshino Tadaatsu Akagi Katsuya Miyatani Kazuhiko Hayashi Hiroshi Sonobe Yuji Ohtsuki 《Virchows Archiv. B, Cell pathology including molecular pathology》1990,59(1):159-164
In order to clarify the function of human S100β- positive T-cells, S100β-positive T-leukemia cells (S100β TLC) were examined in vitro. S100β TLC were obtained from the peripheral blood of a patient with S100β-positive T-cell leukemia and enriched by an E-rosetting method. Two dimensional flow cytometric analysis indicated that the
vast majority of the E-positive fraction were S100β TLC expressing CD3 and CD8 antigens. Although S100β TLC expressed CD3 antigen, they were negative for the α/β and γ/δ T-cell antigen receptor (TCR) defined by monoclonal antibodies
(mabs) WT-31 and δ TCS-1, respectively. It was speculated that S100β TLC initially expressed α/β TCR but lost it during malignant transformation. When S100β TLC were cultured for 24 h, they acquired cytotoxic activity towards various NK-sensitive cell lines including K-562, Molt-3
and CEM-CCLF, but did not exhibit lysing activity towards NK-resistant cell lines including Raji, Daudi and MT-1. Despite
the NK-activity of cultured S100β TLC, they lacked the morphological features of large granular lymphocytes (LGL). S100β TLC did not exhibit lymphokine-activated killer (LAK) activity. When S100β TLC were cocultivated with NK-sensitive cells or NK-resistant cells, they selectively bound to NK-sensitive cells, indicating
that they lysed target cells by cell-to-cell contact. The finding that S100 β TLC lacked TCR molecules and their NK activity
was not inhibited by mabs reactive with the CD3-TCR complex indicated that the CD3-TCR complex was not involved in their target
recognition. These findings suggest that S100 β-positive T-cells are functionally similar to NK cells. We discuss the roles
of S100 β-positive T-cells in the human immune system. 相似文献
39.
Organization and nucleotide sequence of the genes for ribosomal protein S2 and elongation factor Ts in Spirulina Platensis 总被引:2,自引:0,他引:2
Anna Maria Sanangelantoni Raffaele C. Calogero Francesca R. Butarelli Caludio O. Gualerzi Orsola Tiboni 《FEMS microbiology letters》1990,66(1-3):141-146
A 6.5 kb region from the genome of the cyanobacterium Spirulina platensis was cloned using as a probe the Escherichia coli gene for ribosomal protein S2. Sequence analysis revealed, in this region, the presence of the gene for ribosomal protein S2 and part of the gene for the elongation factor Ts (EF-Ts). The arrangement rpsB-spacer-tsf resembles that reported for E. coli. The deduced amino acid sequences of the platensis S2 and EF-Ts show significant homology with the E. coli counterparts. 相似文献
40.
Uptake ofl-[35S]cysteic acid (L-CA) in rat synaptic membrane vesicles was investigated. Preincubation with either 10 mMl-glutamic acid (L-Glu), 25 mM L-CA, 10 mMdl-homocysteic acid, or 25 mMdl-2-amino-4-phosphonobutyrate on membrane vesicles enhanced L-[35S]CA and L-[3H]Glu uptake. Na+ (5 mM) and omission of Cl– from the assay medium decreased L-[35S]CA uptake into both 10 mM L-Glu-loaded and non-loaded membrane vesicles. The anion transport blockers, 4-acetamide-4-isothiocyano-2,2-disulfonic acid stibene (SITS) and 4,4-diisothiocyano-2,2-disulfonic acid stilbene (DIDS), inhibited L-[35S]CA uptake in a dose-dependent manner. The maximal uptake rate for L-[35S]CA was decreased by 50 M SITS, while the apparent Km value of L-CA was not changed. SITS increased the EC50 value of Cl– for L-[35S]CA uptake from 5 mM to 10 mM with reduction of the maximal effect. These results suggested that L-[35S]CA uptake into synaptic membrane vesicles was mediated by a SITS-sensitive hetero-exchange transport with non-labeled substrates.Abbreviations SITS
4-Acetamide-4-isothiocyano-2,2-disulfonic acid stilbene
- DIDS
4,4-Diisothiocyano-2,2-disulfonic acid stilbene
- CA
Cysteic acid
- APB
2-Amino-4-phosphonobutyrate
- CSA
Cysteine sulfinic acid
- EGTA
Ethyleneglycol bis(aminoethylether) tetraacetate
- GABA
-Aminobutyric acid 相似文献