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41.
Two out of ten Rg-specific antisera tested contain a third antibody specific for the β chain of C4. Analysis of the β chains
of 66 unrelated individuals by sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that the epitope detected
is located exclusively on the light (L) β chain. A strong, but incomplete, association between the β chain epitope and the
expression of the Rg: 2 determinant on the α chain of the same protein was also observed. While H (heavy) and L β chains were
not associated with a particular C4 isotype, previously unrecorded associations of β chain polymorphism with theDR locus have been established. 相似文献
42.
Direct evidence for a role of intramitochondrial Ca2+ in the regulation of oxidative phosphorylation in the stimulated rat heart. Studies using 31P n.m.r. and ruthenium red. 总被引:2,自引:1,他引:1
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J F Unitt J G McCormack D Reid L K MacLachlan P J England 《The Biochemical journal》1989,262(1):293-301
1. The concentrations of free ATP, phosphocreatine (PCr), Pi, H+ and ADP (calculated) were monitored in perfused rat hearts by 31P n.m.r. before and during positive inotropic stimulation. Data were accumulated in 20 s blocks. 2. Administration of 0.1 microM-(-)-isoprenaline resulted in no significant changes in ATP, transient decreases in PCr, and transient increases in ADP and Pi. However, the concentrations of all of these metabolites returned to pre-stimulated values within 1 min, whereas cardiac work and O2 uptake remained elevated. 3. In contrast, in hearts perfused continuously with Ruthenium Red (2.5 micrograms/ml), a potent inhibitor of mitochondrial Ca2+ uptake, administration of isoprenaline caused significant decreases in ATP, and also much larger and more prolonged changes in the concentrations of ADP, PCr and Pi. In this instance values did not fully return to pre-stimulated concentrations. Administration of Ruthenium Red alone to unstimulated hearts had minor effects. 4. It is proposed that, in the absence of Ruthenium Red, the transmission of changes in cytoplasmic Ca2+ across the mitochondrial inner membrane is able to maintain the phosphorylation potential of the heart during positive inotropic stimulation, through activation of the Ca2+-sensitive intramitochondrial dehydrogenases (pyruvate, NAD+-isocitrate and 2-oxoglutarate dehydrogenases) leading to enhanced NADH production. 5. This mechanism is unavailable in the presence of Ruthenium Red, and oxidative phosphorylation must be stimulated primarily by a fall in phosphorylation potential, in accordance with the classical concept of respiratory control. However, the full oxidative response of the heart to stimulation may not be achievable under such circumstances. 相似文献
43.
Local interaction of maternal and fetal placental blood flows was studied in two groups of unanaesthetized near-term sheep. Five sheep were exposed to a simulated dive to 100 feet of seawater (4.03 atmospheres) for 25 min. Six fetuses received an infusion of noradrenaline (6.8 micrograms/[kg x min]). Radioactive microspheres were administered simultaneously to mother and fetus before (control) and after (test) the experimental manipulation. Maternal and fetal relative activities, defined as % of total placental radioactivity divided by % of total placental weight, were calculated for 1-g pieces of cotyledonary tissue under control and test conditions. Pieces of cotyledons were defined as matched if the direction of change in relative activity from control to test was the same for mother and fetus. In the absence of an interaction between the maternal and fetal placental circulations, the probability of a piece of cotyledon being matched is 0.5. In each series of experiments the proportion of all cotyledon pieces having maternal and fetal relative activities that changed in the same direction was significantly greater than 0.5. Thus, the majority of the placental mass responds to a physical or chemical perturbation of the fetus in such a way that changes in relative perfusion are qualitatively matched in the adjacent maternal and fetal placental circulations. 相似文献
44.
45.
Foodstuffs were artificially contaminated with Escherichia coli carrying plasmid pBR322, dot blotted onto nylon membranes and briefly subjected to microwaves in the presence of 1·5 mol/l NaC1/0·5 mol/l NaOH. Subsequent hybridization with a biotin-labelled probe specific for pBR322 enabled the detection of cell concentrations > 104 cells/dot blot, equivalent to 2 × 107 cells/g food tested. This shortened and simplified method was effective for all ten foods tested, generated low background levels and should be applicable to a wide range of bacteria. 相似文献
46.
Evidence for M?ssbauer spectroscopy for different forms of iron core in Pseudomonas aeruginosa bacterial ferritin.
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N M Reid D P Dickson C Greenwood A Thompson F H Kadir G R Moore 《The Biochemical journal》1990,272(1):263-264
Mössbauer spectroscopic studies of whole cells of Pseudomonas aeruginosa, grown under different conditions, indicate that the predominant form of iron in the cells varies significantly. These differences are interpreted in terms of differences in the nature of the iron cores of the bacterial ferritin, which result from different growth conditions. 相似文献
47.
48.
Lidija Simova Carolyn Williams Georgi D. Efremov Aleksandra Gordova-Muratovska Stojka Suštić Eila K. Watson Robert Williamson 《Human genetics》1990,85(4):432-433
Summary Chromosomes from 19 unrelated Southern Yugoslav families in which cystic fibrosis (CF) occurs were analysed for the presence
of the ΔF508 mutation, using polymerase chain reaction amplification followed by dot blot and polyacrylamide gel analysis.
Of the 38 CF chromosomes, 15 (39.5%) carry the ΔF508 deletion. Restriction fragment length polymorphism haplotypes for KM19/PstI, XV2c/TaqI and J3.11/PstI marker loci were determined and are compared for a total of 34 N and 37 CF chromosomes. 相似文献
49.
50.
Phytohormone mutants in plant research 总被引:2,自引:0,他引:2
James B. Reid 《Journal of Plant Growth Regulation》1990,9(1-3):97-111
The techniques used for the production and identification of plant hormone mutants are described. The properties used to classify these mutants into the broad synthesis and sensitivity categories are discussed, and the genetic considerations needed to allow their effective use in plant hormone research examined. A brief outline of significant recent work on the gibberellin (GA), abscisic acid (ABA), auxin, ethylene, cytokinin and phytochrome mutants is provided. Suggestions for future emphasis are made, particularly relating to an examination of the tissue and ontogenetic specificity of the plant hormone genes. 相似文献