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11.
Using isolated pea thylakoids, the relative rate of QA
- oxidation has been estimated under various conditions, from the restoration of the induction curves following a dark period and from light 1-induced changes in modulated chlorophyll fluorescence excited by light 2.Alterations of
QinfA
sup–
oxidation rates were observed under conditions which affected the degree of thylakoid stacking, the lipid fluidity and the integrity of the membranes. The results are discussed in terms of the interactions between QA
- and the plastoquinone pool with particular emphasis on lateral diffusion.Abbreviations DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- EDTA
Ethylenediaminetetracetate
- Hepes
N-2-hydroxyethyl piperazine-N-2-ethanesulphonic acid
- NADP
nicotinamide adenine dinucleotide phosphate 相似文献
12.
We have confirmed a method yielding reproducible and reliable spectrometric parameters derived from spin-labeled erythrocyte ghosts using nitroxide derivatives of maleimide compounds. The disorder parameter, W/S, was shown to vary with changes in the structure of the label, the conditions utilized for labeling such as ionic strength and erythrocyte age and the presence of drugs such as alcohol and acetaminophen. The nitroxide spectrum was also found to change with increasing and decreasing temperature in an irreversible manner. These findings should permit increased reliance to be placed on the spin-labeling technique when used to monitor changes in membrane lipid or protein assembly. 相似文献
13.
14.
Lipid composition of the vascular system during infancy, childhood, and young adulthood 总被引:1,自引:0,他引:1
The object of this study was to determine the changes in lipid composition that occur in blood vessels from infancy to young adulthood. Analyses included levels of total cholesterol, total triglyceride, phospholipid, and cholesteryl ester fatty acids, and the distribution of saturated and unsaturated fatty acids. Triglyceride, total and monoenoic fatty acids, and linoleic acid were lower in the ascending, thoracic, and abdominal aorta than in the pulmonary artery and inferior vena cava. Phospholipids and arachidonic acid were higher in aortic segments than in the other two vessels. Aortic lipids showed significant changes with increasing age: total cholesterol and total fatty acids decreased from <1 wk to 5 yr, then increased to 22 yr of age. Triglycerides decreased whereas cholesteryl esters increased from 10 to 22 yr of age. Saturated fatty acids decreased from 1 wk to 10 yr, then remained relatively constant. Linoleic acid (3.7-9.8% of total fatty acids) and arachidonic acid (15.8-21.7%) both increased with age; the increase in cholesteryl linoleate was highly significant. After 10 yr of age, total cholesterol and total fatty acids were significantly higher in abdominal than in ascending and thoracic segments of aorta. 相似文献
15.
16.
Summary Blood vessels of the perioesophageal nerve ganglia (brain) of Octopus vulgaris and the stellate ganglia of Sepia officinalis are described. The vessels have an incomplete endothelium, a complete basement membrane and a complete investment of pericytes. The pericytes are joined by specialised membrane junctions but these are not tight junctions. The main type of neuron/vessel arrangement is one where there is a collagen-filled space between the pericytes and the surrounding glial cells. Axons or neurons are sometimes applied directly to the vessel pericytes and in the neuropil, pericytes contact glial cells that ensheath bundles of axons. Blood spaces between neurons are also present.We would like thank Professor J. Z. Young and Dr. E. G. Gray for encouragement and advice, Mrs. Jane Astafiev for drawing Fig. 11, Mr. S. Waterman for photographic assistance and Miss Cheryl Martin for secretarial and other assistance. 相似文献
17.
18.
A quantitative comparison of dual control of a hormone response element by progestins and glucocorticoids in the same cell line 总被引:3,自引:0,他引:3
S K Nordeen B Kühnel J Lawler-Heavner D A Barber D P Edwards 《Molecular endocrinology (Baltimore, Md.)》1989,3(8):1270-1278
Progesterone receptor-containing T47D human breast cancer cells are responsive to progestins but fail to respond to other steroid hormones, in particular dexamethasone, because they have no measurable levels of receptors for estrogens, androgens, or glucocorticoids. To quantitatively study dual responsiveness of the mouse mammary tumor virus (MMTV) promoter to progestins and glucocorticoids, we have stably transfected T47D cells with a glucocorticoid receptor (GR) expression vector. A cloned derivative (A1-2) was isolated that expresses a normal, full length GR, as assessed by steroid binding and Western immunoblot with a monoclonal anti-GR antibody. Moreover, GR is expressed at levels (80,000-100,000 molecules per cell) comparable to the high levels of endogenous progesterone receptor (200,000 molecules per cell). In A1-2 cells transiently transfected with an MMTV-chloramphenicol acetyl transferase reporter gene, induction by glucocorticoid was substantially greater (5-fold) than induction mediated by progestins. These results suggest that glucocorticoids may be the primary regulator of MMTV. 相似文献
19.
J. De Las Rivas B. Crystall P. J. Booth J. R. Durrant S. Özer G. Porter D. R. Klug J. Barber 《Photosynthesis research》1992,34(3):419-431
A Photosystem two (PS II) core preparation containing the chlorophyll a binding proteins CP 47, CP 43, D1 and D2, and the non-chlorophyll binding cytochrome-b559 and 33 kDA polypeptides, has been isolated from PS II-enriched membranes of peas using the non-ionic detergent heptylthioglucopyranoside and elevated ionic strengths. The primary radical pair state, P680+Pheo-, was studied by time-resolved absorption and fluorescence spectroscopy, under conditions where quinone reduction and water-splitting activities were inhibited. Charge recombination of the primary radical pair in PS II cores was found to have lifetimes of 17.5 ns measured by fluorescence and 21 ns measured by transient decay kinetics under anaerobic conditions. Transient absorption spectroscopy demonstrated that the activity of the particles, based on primary radical pair formation, was in excess of 70% (depending on the choice of kinetic model), while time-resolved fluorescence spectroscopy indicated that the particles were 91% active. These estimates of activity were further supported by steady-state measurements which quantified the amount of photoreducible pheophytin. It is concluded that the PS II core preparation we have isolated is ideal for studying primary radical pair formation and recombination as demonstrated by the correlation of our absorption and fluorescence transient data, which is the first of its kind to be reported in the literature for isolated PS II core complexes from higher plants.Abbreviations CP 43 and CP 47
chlorophyll binding proteins of PS II having apparent molecular weights on SDS-PAGE of 43 kDa and 47 kDa, respectively
- D1 and D2 polypeptides
PS II reaction centre polypeptides encoded by the psbA and psbD genes, respectively
- HPLC
high performance liquid chromatography
- PS II
Photosystem two
- SDS-PAGE
sodium dodecyl sulphate-polyacrylamide gel electrophoresis
- P680
primary electron donor of PS II
- Pheo
phenophytin a
- SPC
single photon counting
- PBQ
phenyl-p-benzoquinone
- DPC
1,5-diphenylcarbazide
AFRC Photosynthesis Research Group, Department of Biochemistry 相似文献
20.
A. Barber 《Cell and tissue research》1982,226(2):267-273
Summary The glyoxylic acid monoamine-detecting technique of Bolstad et al. (1979) was applied to wholemounts of intact ganglia of the gastropod mollusc Philine aperta. A dense network of fluorescent varicosities was found in the sheath of the suboesophageal, visceral and genital ganglia, and most of their nerves. Drug treatment experiments suggest that these projections to the neural sheath contain serotonin. The significance of these terminals in the sheath is discussed and proposals for further work are given. 相似文献