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1.
Scavenging of superoxide radical by ascorbic acid 总被引:1,自引:0,他引:1
Using acetaldehyde and xanthine oxidase as the source of suPeroxide radical, the second order rate constant for the reaction
between ascorbic acid and superoxide radical was estimated to be 8.2 X 107 M-1 s-1. In rats, the average tissue concentration of ascorbic acid was of the order of 10-3 M and that of superoxide dismutase was of the order of 10-6 M. So, taking together both the rate constants and the tissue concentrations, the efficacy of ascorbic acid for scavenging
superoxide radical in animal tissues appears to be better than that of suPeroxide dismutase. The significance of ascorbic
acid as a scavenger of superoxide radical has been discussed from the point of view of the evolution of ascorbic acid synthesizing
capacity of terrestrial vertebrates. 相似文献
2.
Based on pollen and floral morphology,Blechum grandiflorum is transferred toRuellia, and the nameR. mirandana is proposed for this species. A new species,Ruellia tuxtlensis, is described which is distinguishable fromR. mirandana by its longer spike and elliptic bracts. It is presently known only from the lowlands of Veracruz, Mexico. 相似文献
3.
The large family of signal transducing proteins known as G proteins are heterotrimers that dissociate into an independent α-subunit and βγ-subunit complex after ligand binding or other stimulation. For Gα, at least 30 distinct sequences representing 10 different classes have been identified. On the other hand, cDNAs for only three Gβ-subunit genes have been isolated so far. All three of the Gβ genes have been chromosomally mapped in the human, but only two in the mouse. Using a human retinal cDNA for the third G protein β-subunit, we have mapped the corresponding gene, termed Gnb-3, to mouse Chromosome 6 with somatic cell hybrids and have positioned it distal to but near the marker Raf-1 by analysis of the progeny of three genetic crosses. 相似文献
4.
Summary In the qualitative short-day plant Impatiens balsamina, gibberellic acid (GA3) not only promoted the formation of floral buds in response to suboptimal photoinductive conditions and reduced the number of SD cycles that are required for their development into flowers, but also caused initiation of floral buds under non-inductive photoperiods. In plants treated with repeated applications of GA3, the floral buds developed into flowers irrespective of whether the apex was left intact or was removed. In those that received a single application of GA3 the floral buds developed into flowers only in decapitated plants. 相似文献
5.
Pei-Wen Chiang SuQing Wang Paul Smithivas Woo-Joo Song Saravanan Ramamoorthy Joseph Hillman Sheryl Puett Margaret L. Van Keuren Eric Crombez Arun Kumar Thomas W. Glover Diane E. Miller Chun-Hui Tsai C.Clare Blackburn Xiao-Ning Chen Zhiguang Sun Jan-Fang Cheng Julie R. Korenberg David M. Kurnit 《Genomics》1996,34(3):328
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8.
Alterations of Phospholipid Metabolism in Rat Cerebral Cortex Mince Induced by Cationic Amphiphilic Drugs 总被引:3,自引:3,他引:0
Abstract Cationic amphiphilic drugs (CADs) of varied clinical use were screened to determine their capacity to alter the pattern of labeling with 32 Pj of cerebral cortex mince phospholipids. The altered phospholipid labeling patterns were qualitatively similar, the prominent features being reduced incorporation into phosphatidylcholine and increased incorporation into phosphatidic acid. Relative potencies were: (±)-propranolol > chlorpromazine = 4,4'-bis(diethylaminoethoxy) α,β -diethyldiphenylethane > desipramine > di-bucaine > pimozide > oxymetazoline = fenfluramine = haloperidol = chloroquine > amphetamine = no drug added. Propranolol was used to study the action of CADs further. Its effect was time- and dose-dependent, but in contrast with pineal gland, no label appeared in phosphatidyl-CMP (CDP-diacylglycerol), nor did dialysis of the mince to reduce diffusible substrates or exogenous addition of substrates cause appearance of liponucleotide. Thus lack of diffusible precursors is not responsible for CAD effects in vitro. Pulse-chase experiments with 32 P1 and [2-3 H]glycerol suggested that inhibition of phosphatidate phosphohydrolase may be partly responsible for the observed alterations in phospholipid labeling in the presence of CADs. 相似文献
9.
Ion-specific electrodes were used to study the binding of Hg2+, Pb2+, Cu2+, and Cd2+ ions to widely used bacterial growth media (Nutrient broth, trypticase soy broth, the medium of Foot and Taylor [6] and of Nelsonet al.[12]) and to media components [yeast extract, peptone, tryptone, proteose peptone, and casamino acids (acid hydrolyzed casein)]. Volatilization of Hg2+ from aqueous solutions could be prevented by any of the growth media or their components. All media bound large amounts of Hg2+, Pb2+, and Cu2+, but much less Cd2+. Of the media components, casamino acids showed the most binding activity for all metal ions; the relative affinity of other media components to different ions varied with the cation studied. In general, the Irving-Williams [8] series for cation affinity to organic ligands was followed: Hg2+>Pa2+ Cu2+ Cd2+.After adding 20 ppm of Hg2+, Pb2+, or Cu2+ (concentrations inhibitory to the growth of most microorganisms) to the growth media, 80 ppb or less remained as free cations in the solution. This might suggest that such ions enter bacterial cells as organic complexes, or that bacterial cells can compete successfully with growth media for the bound ions. 相似文献