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21.
Birgit Rose Toshihiko Yada Werner R. Loewenstein 《The Journal of membrane biology》1986,94(2):129-142
Summary The viralsrc gene downregulates junctional communication, closing cell-to-cell membrane channels presumably by way of the phosphoinositide signal route. We show that TMB-8 [8-N, N-(diethylamino) octyl-3,4,5-trimethoxybenzoate] counteracts this downregulation in cells transformed by temperature-sensitive mutant Rous sarcoma virus: TMB-8 (36–72 m) raises junctional permeability when applied during activity ofsrc protein kinase, i.e., at steady permissive temperature; and TMB-8 inhibits the fall of junctional permeability, when the activity ofsrc protein kinase gets turned on. TMB-8 also (reversibly) inhibits the growth of the cells at permissive temperature and reverses the morphological changes associated with transformation. The morphological reversal lags several hours behind the junctional-permeability reversal. Communication recovers within a few minutes when the activity of thesrc protein kinase is turned off (in absence of TMB-8). Sodium orthovanadate (20 m) prevents this recovery, but it has no major effect on junctional permeability on its own. We discuss possible modes of action of these agents on critical stages of the signal route, related to intracellular Ca2+ and protein kinase C. 相似文献
22.
Abstract Acetobacterium woodii was continuously grown on 3,4,5-trimethoxybenzoate as pure culture or in commensalistic combination with Pelobacter acidigallici and Desulfobacter postgatei . Under pure culture conditions the following growth parameters were determined: μ max = 0.112 h−1 , K s = 1.07 mM, Y max = 35 g/mol, and m = 0.22 mmol·g−1 ·h−1 . In coculture with P. acidigallici the affinity for the substrate increased and the K s value was found to be 135 μM. Under batch culture conditions mixed populations of A. woodii, P. acidigallici , and D. postgatei completely mineralized 3,4,5-trimethoxybenzoate to CO2 , whereas under continuous culture conditions more than 3 mM acetate remained unused. 相似文献
23.
Megumi Kono Koji O'hara Yoshihiro Arai Hideyuki Fukuda Misaki Asakawa Hideomi Nakahara 《FEMS microbiology letters》1985,28(2):213-217
Abstract A susceptibility of 63 clinical isolates of Klebsiella pneumoniae to inorganic and organic mercuric compounds was determined. 18 of them were found to be resistant to fluorescein mercuric acetate (FMA) and merbromin (MB). Moreover, all the resistant strains inactivate the antibacterial effect of FMA. The changes in the amount of organic mercury at the time of inactivation of the drug and the structures of the end products were examined in detail with the plasmid-bearing strain JK9 and its transconjugants of Escherichia coli .
The results showed that FMA was inactivated by an intracellular enzyme produced inducively and was degraded to fluorescein (sodium salt, uranine), which led to the sedimentation of metallic mercury. The discovery of the genes conferring inducible organic mercury-inactivating enzymes determined by plasmids was the next step and their application in the recovery of metallic mercury from organomercurials is now imminent. 相似文献
The results showed that FMA was inactivated by an intracellular enzyme produced inducively and was degraded to fluorescein (sodium salt, uranine), which led to the sedimentation of metallic mercury. The discovery of the genes conferring inducible organic mercury-inactivating enzymes determined by plasmids was the next step and their application in the recovery of metallic mercury from organomercurials is now imminent. 相似文献
24.
Bernhard Knig Patricia A. DiNitto Peter M. Blumberg 《Journal of cellular biochemistry》1985,29(1):37-44
The major phorbol ester receptor is the Ca++-activated, phospholipid-dependent protein kinase C. Diacylglycerol stimulates protein kinase C in a fashion similar to the phorbol esters. Likewise, it inhibits phorbol ester binding competitively. Both results suggest that diacylglycerol is the/an endogenous phorbol ester analogue. Alternatively, the diacylglycerol might simply be acting to modify the phospholipid environment of the protein. If diacylglycerol were indeed functioning as an analogue, it should interact with the receptor stoichiometrically. This interaction can be quantitated by measuring the perturbation in apparent diacylglycerol binding affinity as a function of the ratio of diacylglycerol to receptor. We report here that 1,2-dioleoylglycerol interacts with the receptor with the predicted stoichiometry. 相似文献
25.
The effect of phorbol myristate acetate, phorbol dibutyrate, ethanol, dimethylsulfoxide, phenol, and seven metabolites of phenol on metabolic cooperation were assessed as a function of mutant cell recovery from populations of cocultivated hypoxanthine-guanine phosphoribosyl transferase-deficient mutant (HGPRT–) and wild-type (HGPRT+) Chinese hamster V79 lung fibroblasts. Phorbol myristate acetate and phorbol diputyrate, two established tumor promoters, were potent inhibitors of metabolic cooperation. Ethanol and dimethylsulfoxide, solvents commonly used to prepare chemicals for testing, weakly inhibited metabolic cooperation. Phenol and phenylglucuronide had no effect on metabolic cooperation. Four oxidative metabolites (1,4-benzoquinone, catechol, hydroxyquinol and quinol) inhibited metabolic cooperation. Phenylsulfate weakly inhibited metabolic cooperation. Conversely, 2-methoxyphenol, a methylated derivative of catechol, appeared to enhance metabolic cooperation. These results generallyAbbreviations CAS
Chemical Abstracts Service
- DMSO
dimethylsulfoxide
- ETOH
ethanol
- HGPRT
hypoxanthine-guanine phosphoribosyl transferase
- HGPRT+
HGPRT-competent
- HGPRT–
HGPRT-te]deficient
- MC
metabolic cooperation
- MC+
metabolic cooperation-competent
- MC–
metabolic cooperation-deficient
- MEM
minimum essential medium
- PDBu
phorbol dibutyrate
- PMA
phorbol myristate acetate
- 6TG
6-thioguanine
- 6TGr
6-thioguanine-resistant
- 6TGs
6-thioguanine-sensitive
- V79/MC assay
Chinese hamster V79 lung fibroblast assay for metabolic cooperation 相似文献
26.
27.
A new approach to high sensitivity differential hybridization 总被引:4,自引:0,他引:4
We describe a new approach to differential hybridization, designed to identify cDNA clones representing rare mRNA species. Duplicate filters carrying a library of cDNA from phorbolmyristate acetate (PMA)-induced EL-4 cells in λgt11 were hybridized with high concentrations of unlabeled, cloned, single-stranded cDNA from induced and control EL-4 cells, respectively. Plaques binding single-stranded cDNA were revealed by a second round of hybridization with 35S-labeled DNA complementary to the vector moiety of the single-stranded cDNA. Plaques corresponding to PMA-induced mRNAs occurring at a level of about 1 part in 15000 were isolated. We believe the method is at least ten times more sensitive than conventional differential hybridization. 相似文献
28.
A method is presented for the rapid enzymatic determination of acetate in spent bacterial culture supernatants. The assay is based on a previously published assay for acetate kinase [Bergmeyer et al. (1974) in Methods of Enzymatic Analysis (Bergmeyer, H. V., ed.), Vol. 1, pp. 425-426, Verlag Chemie-Academic Press, New York/London], and is sufficiently sensitive to detect acetate levels of 50 microM. The assay is cheaper than commercially available assays and is particularly useful for occasional use by laboratories not equipped for routine acetate analysis using gas chromatography. The application of the assay to the measurement of acetate in bacterial cultures is described, though it should also be applicable to other biological fluids and foodstuffs. 相似文献
29.
Gliding motility, ultrastructure and nutrition of two newly isolated filamentous sulfate-reducing bacteria, strains 5ac10 and 4be13, were investigated. The filaments were always attached to surfaces. Growth was supported by addition of insoluble aluminium phosphate or agar as substrata for gliding movement. Electron microscopy of ultrathin sections revealed cell walls characteristic of Gramnegative bacteria; the undulated structure of the outer membrane may pertain to the translocation mechanism. Intracytoplasmic membranes were present. Acetate, higher fatty acids, succinate or fumarate served as electron donors and carbon sources. Strain 5ac10 grew also with lactate, but not with benzoate that was used only by strain 4be13. Strain 5ac10 was able to grow slowly on H2 plus CO2 or formate in the presence of sulfate without additional organic carbon source. The capacity of complete oxidation was shown by stoichiometric measurements with acetate plus sulfate. Both strains contained b- and c-type cytochromes. Desulfoviridin was detected only in strain 5ac10. The two filamentous gliding sulfate reducers are described as new species of a new genus, Desulfonema limicola and Desulfonema magnum. 相似文献
30.
Jila H. Boal Scott F. Deamond Daniel E. Callahan Sarah A. Bruce Paul O. P. Ts'o L. L. Kan 《Cell biochemistry and biophysics》1989,14(3):245-256
The nuclear magnetic resonance (NMR) parameters, spin-lattice (T1), and spin-spin (T2) relaxation time, are usually longer for neoplastic cells than for normal cells of the same cell type. This has generally
been true at low NMR frequencies (≤100 MHz) when comparisons have been made between normal and neoplastic cells that have
both spent a short time in culture. We have previously demonstrated that although the T1 values of paired normal and neoplastic Syrian hamster (SH) fibroblastic cells in culture are not significantly different
when measured at 300 MHz, the 300 MHz T2 values for the neoplastic cells are smaller than those of the normal cells. (Xin et al. (1986),Cell Biophysics
8, 213.) Since treatment of normal diploid cells with polypeptide growth factors or tumor promoters frequently results in reversible
expression of neoplasia-associated phenotypes, T1 and T2 were obtained at 300 MHz for treated and untreated SH cells to see if these compounds could also produce smaller 300 MHz
T2 values. Secondary culture SH fetal fibroblast cells were treated with epidermal growth factor (EGF), fibroblast growth factor
(FGF), phorbol-12,13-didecanoate (PDD) and 4-α-phorbol-12,13-didecanoate (4αPDD). Treatment with either growth factor resulted
in smaller T2 values, but a statistically significant decrease was not observed for PDD or 4αPDD. The observed reductions in T2 values were correlated with the morphological and growth-stimulatory effects of these compounds on the cells. 相似文献