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991.
M. Gutmann 《Biotechnic & histochemistry》1993,68(3):161-165
A valuable method for specific localization of proanthocyanidins in plant tissues is given. The specificity is based on the acid hydrolysis of condensed tannins in situ via hot sulfuric acid, yielding bright red anthocyanidins. This treatment did not cause noticeable damage of tissue embedded in glycol methacrylate prior to sectioning. Further proof of specificity was achieved by control staining with the flavan-3-01-selective p-dimethylaminocinnamaldehyde (DMACA) reagent. In addition, comparison of adjacent sections stained with the DMACA reagent may give coarse information about the degree of polymerization of the proanthocyanidins. 相似文献
992.
室旁核在刺激肾神经传入纤维对血浆皮质醇浓度影响中的作用 总被引:3,自引:0,他引:3
本文在氯醛糖麻醉猫中探讨室旁核毁损前、后,电刺激肾神经传入纤维对血浆皮质醇浓度的影响。在动脉压力感受器完整猫中,刺激肾神经传入纤维对血浆皮质醇浓度无明显影响,但在动脉压力感受器去神经和迷走神经切断(SAD+VD)后,电刺激肾神经中枢端引起血浆皮质醇浓度升高。微量注射红藻氨酸毁损双侧室旁核后,可阻断刺激肾神经传入纤维引起的血浆皮质醇浓度升高,这些结果表明:动脉压力感受性反射可抑制刺激猫肾神经传入纤维引起的血浆皮质醇浓度升高;室旁核在刺激肾神经传入纤维引起的血浆皮质醇浓度升高效应中起重要作用。 相似文献
993.
The effect of various metals and regucalcin, a calcium-binding protein isolated from rat liver cytosol, on (Ca2+–Mg2+)-ATPase activity in the plasma membranes of rat liver was investigated. Of various metals (Zn2+, Cu2+, Ni2+, Mn2+, Co2+ and Al3+; 100 M as a final concentration), Mn2+ and Co2+ increased markedly (Ca2+–Mg2+)-ATPase activity, while other metals had no effect. When Ca2+ was not added into enzyme reaction mixture, Mn2+ and Co2+ (25–100 M) did not significantly increase the enzyme activity, indicating that heavy metals act on Ca2+-stimulated phosphorylation of the enzyme. Meanwhile, regucalcin (0.25–1.0 M) caused a remarkable elevation of (Ca2+–Mg2+)-ATPase activity. This increase was not inhibited by the presence of 100 M vanadate, although the effects of Mn2+ and Co2+ (100 M) were inhibited by vanadate. Also, the inhibition of the Mn2+ and Co2+ effects by vanadate was not seen in the presence of regucalcin. Moreover, regucalcin (0.5 M) increased significantly the enzyme activity in the absence of Ca2+. This effect of regulcalcin was not altered by increasing concentrations of Ca2+ added, indicating that the regucalcin effect does not depend on Ca2+. The present results suggest that regucalcin activates directly (Ca2+–Mg2+)-ATPase in liver plasma membranes, and that the activation is not involved in the Ca2+-dependent phosphorylation of the enzyme. 相似文献
994.
Effect of sink size on photosynthesis and carbohydrate content of leaves of three spring wheat varieties 总被引:3,自引:0,他引:3
R. Martínez-Carraseo E. Cervantes P. Pérez R. Morcuende I. M. Martín del Molino 《Physiologia plantarum》1993,89(3):453-459
Effects of CO2 on stomatal movements of Commelina communis L. were studied with plants, epidermal strips and guard cell protoplasts. With plants, the stomatal response induced by a blue light pulse was studied for different ambient CO2 concentration ranging from CO2 -deprived air to 100 Pa in darkness or under red light. It was observed that the blue light response could be obtained not only under a red light background but also in darkness and CO2 -free air, the two responses being quite similar.
With epidermal strips, the effect of CO2 on ferricyanide reductase activity at the guard cell plasmalemma was studied by transmission electron microscopy. In the presence of ferric ions, reduced ferricyanide gives an electron dense precipitate of Prussian Blue. In darkness and air, no precipitate was observed. In darkness and CO2 -free air as well as under light and normal air, a precipitate was found along the plasmalemma of the guard cells, indicating a ferricyanide reductase activity. With guard cell protoplasts suspended in a medium either in equilibrium with air or in a CO2 -free medium the H+ extrusion induced by a blue light pulse added to a red light background was measured. A low CO2 content was obtained by adding photosynthetic algae to the suspension of guard cell protoplasts. In a CO2 -free medium the rate of H+ extrusion was enhanced.
The results are discussed on the basis of a possible competition for reducing power between CO2 fixation and a putative blue light dependent redox chain located on the plasma membrane. 相似文献
With epidermal strips, the effect of CO
The results are discussed on the basis of a possible competition for reducing power between CO
995.
A significant progress in the knowledge of different aspects of nitrate transport in the unicellular cyanobacterium Anacystis (Synechococcus ) has been achieved in the last few years. The main contributions of our group are summarized in this article and discussed in relation to other information available. Endergonic accumulation of nitrate into the cells, indicative of the operation of an active nitrate transport system, has been experimentally substantiated and methods established to evaluate and analyze the activity of the system. Nitrate transport activity is sensitive to regulation exerted by products of both ammonium and CO2 assimilation, thus providing evidence that photosynthetic nitrate assimilation in cyanobacteria is primarily controlled at the level of substrate supply to the cell. The expression of nitrate transport was also shown to be under nitrogen control, being repressed when ammonium is used as the nitrogen source. A 47-kDa polypeptide, which is a major plasma membrane component in nitrate-grown cells but is virtually absent in ammonium-grown cells, was identified as an essential component of the nitrate transporter. More recently, evidence of a strict Na'-dependence of active nitrate transport has been obtained, Δμ(Na+ ) appearing as the driving force of a sodium-nitrate symport system. Kinetic studies indicate also that the nitrate transporter may transport nitrite into the cell. 相似文献
996.
Summary Isolated plasma membrane vesicles purified by aqueous polymer two-phase partitioning were used as a model system for studies on the membrane-associated (cortical) cytoskeleton in plants. Actin, as identified by immunoblotting, was found to be specifically attached to plasma membrane vesicles from cauliflower (Brassica oleracea L.). The actin was not washed off as the vesicles were turned inside-out, indicative of a fairly strong attachment. Triton X-100 extraction of plasma membrane vesicles resulted in an insoluble and hence pelletable fraction where actin could be found together with several other proteins. Our results show that the cortical cytoskeleton is to some extent co-purified with the plasma membrane, and we believe that well defined, inside-out and right-side-out plasma membrane vesicles can be used to study the structure and dynamics of the plant cortical cytoskeleton.Abbreviations ATP
adenosine 5-triphosphate
- BCIP
5-bromo-4-chloro-3-indolyl phosphate
- BSA
bovine serum albumin
- CCD
counter-current distribution
- DTT
dithiothreitol
- EDTA
ethylene-diamine-tetraacetic acid
- EGTA
ethylene glycol-bis(-aminoethyl ether)
- GSII
1,3--glucan synthase
- HEPES
N-[2-hydroxyethyl]-piperazine-N-[2-ethane sulfonic acid]
- MES
2-(N-morpholino)ethane sulfonic acid
- NBT
p-nitro blue tetrazolium chloride
- IDP
inosine 5-diphosphate
- PAGE
polyacrylamide gel electrophoresis
- PBS
phosphate buffered saline
- PIPES
piperazine-N,N-bis(2-ethane-sulfonic acid)
- PPB
potassium phosphate buffer
- PM
plasma membrane
- PMSF
phenylmethylsulfonyl fluoride
- PVDF
polyvinylidene difluoride
- PVPP
polyvinylpolypyrrolidone
- SDS
sodium dodecyl sulfate
- TBS
Tris-buffered saline
- TTBS
Tris-buffered saline with Tween 20
- Tris
tris(hydroxymethyl) aminomethane 相似文献
997.
Ahuva Golik Nathan Cohen Yoram Ramot Joseph Maor Rita Moses Joshua Weissgarten Yuval Leonov David Modai 《Biological trace element research》1993,39(2-3):171-175
Zinc status was assessed in patients with type II diabetes mellitus and congestive heart failure (CHF). Three groups of patients
were enrolled into the study: Group 1: 15 patients with type II diabetes mellitus and CHF; Group 2: 20 patients with isolated
type II diabetes mellitus; and Group 3: nine patients with isolated CHF. Twenty-four-hour urine was measured for creatinine,
protein, and zinc, and blood was drawn for creatinine, proteins, liver enzymes, hemoglobin A1c, and zinc. Insulin treatment and hemoglobin A1c were comparable in the diabetic patients of groups 1 and 2, but group 1 was also treated with captopril and diuretics like
the CHF patients of group 3. Plasma zinc levels were statistically similar in all three groups, but urinary zinc excretion
(μmol/24 h) and urinary zinc: creatinine (μmol/mmol) ratio were significantly higher in the type II diabetics and CHF group
(27.2±1.5; 1.69±0.6, respectively) compared to the diabetic patients alone (19.4±0.76; 0.97±0.3, respectively) and the CHF
patients (9.7±0.3; 0.62±0.3, respectively). Patients with type II diabetes mellitus and CHF were treated with higher doses
of captopril than the CHF patients (56.25±24 mg vs 18.8±11 mgP<0.05). Thus, patients with type II diabetes mellitus and CHF excrete larger amounts of zinc, which may eventually lead to
zinc deficiency. 相似文献
998.
用扫描电镜、X—射线能谱仪和等离子耦合吸收光谱(ICP)分析发现,培养在含NaCl培养液中,小麦柜吸收大量Na~ 和Cl~-,K~ 和Ca~(2 )的吸收降低,质膜相对透性提高,K~ 、Na~ 和Cl~-的相对外渗百分率增加。培养在补充CaCl_2含NaCl培养液的,Na~ 和Cl~-含量明显减低,K~ 和Ca~(2 )提高,质膜相对透性下降,K~ 、Na~ 和Cl~-相对外渗百分率减少。由气相色谱分析可知,用含NaCl或补充CaCl_2培养液培养的幼苗,根的膜脂脂肪酸组分没有变化,但培养在补充CaCl_2的培养液中的根,亚麻酸含量和脂肪酸不饱和指数下降。 相似文献
999.
1000.
The merits of radiochemical neutron activation analysis (RNAA) and inductively coupled plasma mass spectrometry (ICP-MS) are
critically discussed for the determination of trace and ultratrace elements in normal human serum. For RNAA, two semiautomated
procedures, allowing the determination of up to 18 elements, are briefly described. ICP-MS has a series of interesting features
for the determination of trace elements. Matrix and spectral interferences can mostly be avoided or corrected for. After a
simple 5- or 10-fold dilution and addition of an internal standard, more than 20 elements can be measured precisely and accurately. 相似文献