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91.
The 1000-1300 cm-1 region of the infrared spectrum of dipalmitoylphosphatidylcholine (DPPC) and other phosphate-containing molecules has been studied by the Fourier-transform technique. Three absorption bands have been assigned to various vibrational modes of the DPPC phosphate group, with maximum wavenumbers at 1060, 1086 and 1222 cm-1. These values are the same above and below Tc of the phospholipid. Dehydration produces band-shifts toward higher wavenumbers . 相似文献
92.
B A Pirola F Mayer I A Borthwick G Srivastava B K May W H Elliott 《European journal of biochemistry》1984,144(3):577-579
The structure of chick embryo liver 5-aminolaevulinate synthase has been examined by electron microscopic studies using negative staining. From the different projections of the enzyme particles observed in electron micrographs, a model for the enzyme molecule has been proposed. In this model, an enzyme molecule consists of two curved and identical subunits associated in opposite polarities. From the dimensions of an enzyme molecule subunit measured from electron micrographs, the relative molecular mass of each subunit is estimated to be 70 000. 相似文献
93.
Mineralization dynamics in fallow dryland wheat plots,Colorado 总被引:2,自引:0,他引:2
Summary There was a flush of mineralization in fallow wheat plots in the wet and warm summer of 1982 at Akron, Colorado. Peak mineralization rates and concentrations of N and P coincided with a 2.5-fold increase in protozoan biomass. No-till contained considerably more activity than stubble mulch plots, especially in the surface 2.5 cm and there was more water storage in no-till on all dates. Differential management of agricultural residues and the resultant effects upon the microbial community significantly altered patterns of nutrient cycling. 相似文献
94.
Ontogenetic Changes in the Transport of Indol-3yl-acetic Acid into Maize Roots from the Shoot and Caryopsis 总被引:2,自引:2,他引:0 下载免费PDF全文
The quantities of endogenous indol-3yl-acetic acid (IAA) in endosperms and scutella of 6-day-old maize seedlings (Zea mays L. cv Giant White Horsetooth) were determined by a fluorimetric method. Endosperms were found to contain 33.4 nanograms IAA per plant, and scutella 7.5 nanograms IAA per plant. [5-3H]IAA applied to endosperms of 6-day-old seedlings moved into the roots and radioactivity accumulated at the apex of the primary root within 8 hours. Two to 7-day-old seedlings were treated simultaneously with [5-3H]IAA in the endosperm and [2-14C] IAA on the shoot apex. The patterns of transport into the root were found to change during ontogeny: in successively older plants, transport from the shoot into the roots increased relative to transport from the endosperm into the roots. The auxin required for the growth of maize roots could, therefore, partially be contributed by the shoot and endosperm. Ontogenetic changes in the relative importance of these two supplies could be of significance for the integration of growth and development between shoot and root. 相似文献
95.
Suspensions of rat pancreatic microsomal fraction release alpha-amylase and ribonuclease on incubation at 37 degrees C, but not at 2 degrees C. The release is abolished by proteolytic enzymes. Ribonuclease associated with the microsomal fraction is protected from subtilisin BPN' attack, but is sensitive after release. 相似文献
96.
H L Elliott F Dryburgh G S Fell S Sabet A I Macdougall 《BMJ (Clinical research ed.)》1978,1(6120):1101-1103
In the west of Scotland the incidence of dialysis encephalopathy has been confined to three geographical areas where the concentration of aluminium in the water supply is greatly increased owing to the addition of aluminium sulphate. Eight patients with encephalopathy who dialysed at home in these areas had greatly increased serum aluminium concentrations, and a significant correlation was found between serum aluminium concentrations and the concentrations of aluminium in the water supply. This study provides further evidence that the dialysis encephalopathy syndrome is due to aluminium intoxication, the major source of aluminium being the water supply from which dialysis fluid prepared. 相似文献
97.
Richters Valda Elliott Gary Sherwin Russell P. 《In vitro cellular & developmental biology. Plant》1978,14(5):458-464
Summary The lungs of 12 mice, half of which were exposed to continuous 0.5 ppm nitrogen dioxide for 3 weeks, were explanted in culture,
and the instances of macrophage congregation were quantitated according to numbers of target cells involved, categories of
congregation from three to 11 or more, numbers of macrophages participating in each category for the total cultures, and the
influence of delaying explantation for 24 and 96 hr. A total of 9042 macrophages and 2140 epithelial and spindle target cells
were counted in the outgrowths from 306 explants. The incidence of macrophage congregation (or numbers of target cells) was
greater for the cultures from the NO2-exposed animals, both with respect to total incidences between groups (p→0), and the 0-hr (p<0.001) and 24-hr (p<0.01) culture
subgroups. In addition, the values for T3 to T6 macrophage congregation were individually and consistently greater for the exposed animal group. Postmortem interval stress
at 96 hr appeared to result in large colonies, but they were reduced greatly in number. Also the incidence of macrophage congregation
fell by 28% as compared to 0-hr and 24-hr subgroups.
Supported by Grants NHLI No. HL 17412 and EPA No. R. 800881. 相似文献
98.
Tadao Okazaki Masathosi Shimizu Carl E. Arbesman Elliott Middleton 《Prostaglandins & other lipid mediators》1978,15(3):423-427
Sera used in cell cultures contain significant amount of prostaglandins (PGs). In order to vaoid any effects of contaminating PGs, the present study employed a serum-free culture medium and confirmed the inhibitory effect of prostaglandin E (PGE) on the human lymphocyte activation which had been observed previously employing a serum-containing medium. PGE1 displayed a significantly stronger inhibitory effect on the cells than previously shown. Furthermore, reported enhancement of PGE synthesis by mitogen-activated lymphocytes could not be reproduced. 相似文献
99.
100.
The mechanism by which the utilization of transferrin-bound iron is linked with cellular metabolism was investigated using rabbit reticulocytes and bone marrow cells. The rate of metabolism was altered by the use of inhibitors which act at different sites in the metabolic pathway (NaF, sodium fluoroacetate, rotenone, 2,4-dinitrophenol, NaCN) and by the addition of metabolic substrates (inosine, sodium pyruvate, sodium lactate). Measurements were made of the rates of iron and transferrin uptake and, in many of the experiments, of cellular ATP and NADH concentrations. The results showed that there was a significant correlation between the rate of iron uptake and the ATP concentration of the cells, but no correlation was found with the NADH concentration. The rate of transferrin uptake was inhibited to a lesser degree than that of iron uptake, and only when the ATP concentration had fallen below that necessary to inhibit iron uptake. It is concluded that the rate of uptake of transferrin-bound iron by immmature erythroid cells is dependent on the intracellular concentration of ATP but is independent of the NADH concentration. 相似文献