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21.
The incorporation of uridine into RNA in brain slices was studied. Optimal conditions for uridine incorporation were determined. The characteristics of the product suggest that de novo DNA-directcd synthesis of fairly high molecular weight material takes place. Incorporation into RNA of several areas of brain was studied. The incorporation was also studied as a function of the age of the animal. Finally, an apparent correlation was observed between the decrease in uridine incorporation with age and the increase of the enzyme uridine nucleosidase which hydrolyses uridine to uracil, a material which cannot be incorporated into RNA. 相似文献
22.
The Photosynthetic Electron Transport Chain of Chlamydomonas reinhardi. VII. Photosynthetic Phosphorylation by a Mutant Strain of Chlamydomonas reinhardi Deficient in Active P700 总被引:7,自引:5,他引:2 下载免费PDF全文
Electron transport activity and absorbance changes associated with P700 were investigated in a mutant strain of Chlamydomonas reinhardi with impaired photosynthesis. This mutant strain, ac-8oa, cannot reduce NADP with electrons from either water or dye and ascorbate, but it has considerable Hill activity. The mutant strain shows none of the absorbance changes characteristic of P700. Although unable to carry out cyclic photosynthetic phosphorylation, ac-8oa is able to synthesize ATP when ferricyanide is provided as an electron acceptor.
These observations lead to the conclusion that a site for the coupling of photosynthetic phosphorylation with electron transport must exist between the 2 photochemical systems.
相似文献23.
24.
Alice K. Strangway 《CMAJ》1960,83(20):1040-1046
25.
Alice Stewart 《BMJ (Clinical research ed.)》1960,2(5209):1381-1382
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27.
Peter L. Pingerelli Hiroshi Mizukami Monica J. Mooney Alice L. Schlaepfer 《The protein journal》1989,8(2):183-196
S100b is a calcium-binding protein that will bind to many calmodulin target molecules in a Ca2+-dependent manner. In order to study the Ca2+-dependent binding properties of S100b, its interaction with a calmodulin antagonist, trifluoperazine (TFP), was investigated using [19F]- and [1H]-NMR and UV-difference spectroscopy. It was estimated from [19F]-NMR that in the absence of Ca2+, thek 1/2 value of TFP was 130 µM, while itsk 1/2 value decreased to 28 µM in the presence of Ca2+. The addition of KCl was not antagonistic to the Ca2+-dependent interaction of TFP to S100b. The chemical exchange rate of TFP with Ca2+-bound S100b was estimated to be 9×102 sec?1. By comparison with TFP-calmodulin exchange rates, it is suggested that the TFP-binding site on S100b is structurally different from its binding sites on calmodulin. Proton NMR resonance broadening in the range 6.8–7.2 ppm, corresponding to phenylalanine nuclei of S100b, indicates that these residues may be involved in TFP binding. Addition of Ca2+ to a 1:1 mixture of S100b and TFP resulted in a red-shifted UV-difference spectrum, while no significant difference spectrum was detected when Mg2+ was added to a S100b-TFP solution. Thus, we suggest that Ca2+ induces the exposure of a hydrophobic domain on S100b containing one or more phenylalanine residues that will bind TFP but that this domain is different from the hydrophobic domain on calmodulin. 相似文献
28.
Robert Y. Kanterman Christian C. Felder Douglas E. Brenneman Alice L. Ma Sandra Fitzgerald Julius Axelrod 《Journal of neurochemistry》1990,54(4):1225-1232
The alpha 1-adrenergic receptor has been shown to mediate the release of arachidonic acid in FRTL5 thyroid cells and MDCK kidney cells. In primary cultures of spinal cord cells, norepinephrine stimulated release of arachidonic acid (from neurons only) and turnover of inositol phospholipids (from neurons and glia) via alpha 1-adrenergic receptors. These two responses were dissociated by treatment with phorbol ester and pertussis toxin, which inhibited production of inositol phosphates with no appreciable effect on release of arachidonic acid. Extracellular calcium was required for release of arachidonic acid, but not for production of inositol phosphates. The calcium channel blockers nifedipine and verapamil inhibited release of arachidonic acid only. However, 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8), a compound that blocks intracellular calcium release, diminished production of inositol phosphates, but had little effect on release of arachidonic acid. These results suggest that alpha 1-adrenergic receptors couple to release of arachidonic acid in primary cultures of spinal cord cells by a mechanism independent of activation of phospholipase C, possibly via the activation of phospholipase A2. 相似文献
29.
Catabolic plasmids of environmental and ecological significance 总被引:13,自引:0,他引:13
The environmental and ecological significance of catabolic plasmids and their host strains are discussed in the context of their potential application for environmental biotechnology. Included is a comprehensive list of naturally occurring discrete catabolic plasmids isolated from either natural habitats or selective enrichment studies. General properties, such as plasmid maintenance, stability and transfer, are discussed together with the techniques for plasmid detection and monitoring in the environment. The issues concerning the construction of catabolic strains with new or broader substrate ranges and the uses of monocultures or consortia for in situ treatment are addressed. 相似文献
30.