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71.
Richoux J. P. Cordonnier J. L. Bouhnik J. Clauser E. Corvol P. Menard J. Grignon G. 《Cell and tissue research》1983,233(2):439-451
Cell and Tissue Research - The renin substrate, angiotensinogen, was localized by immunocytochemistry in liver and kidney of normal rats by the use of an antiserum directed against pure rat... 相似文献
72.
Preparation of Corn Root Plasmalemma with Low Mg-ATPase Latency and High Electrogenic H Pumping Activity after Phase Partitioning 总被引:2,自引:2,他引:0 下载免费PDF全文
Crude plasma membranes of corn (Zea mays L.) roots were obtained according to MI De Michelis and RM Spanswick (1986 Plant Physiol 81: 542-547). This preparation, which contained tightly sealed vesicles displaying Mg-ATP dependent H+-transport, was purified by phase partitioning. The percentage of inside-out vesicles (10%) was determined from the Mg-ATPase latency, revealed with lysophosphatidylcholine. A Triton X-100 treatment described previously (JP Grouzis, R Gibrat, J Rigaud, C Grignon 1987 Biochim Biophys Acta 903: 449-464) was applied to phase-partitioned plasma membranes. The percentage of catalytic sites freely accessible to Mg-ATP increased to 50% after Triton X-100 treatment. Treated vesicles remained capable of electrogenic H+-pumping, as demonstrated by Mg:ATP-dependent quinacrine fluorescence quenching and oxonol absorbance shift. As expected from the large increase of the catalytic sites accessibility, increases of the dye responses were observed. Concanavalin A binding was estimated from microelectrophoretic measurements of individual vesicles. Statistical analysis of concanavalin A binding and Mg-ATPase latency suggest that treated membranes have lost their asymmetric structure. 相似文献
73.
Charge Balance in NO(3)-Fed Soybean: Estimation of K and Carboxylate Recirculation 总被引:1,自引:1,他引:0 下载免费PDF全文
Soybeans (Glycine max L. Merr., cv Kingsoy) were grown on media containing NO3− or urea. The enrichments of shoots in K+, NO3−, and total reduced N (Nr), relative to that in Ca2+, were compared to the ratios K+/Ca2+,NO3−/Ca2+, and Nr/Ca2+ in the xylem saps, to estimate the cycling of K+, and Nr. The net production of carboxylates (R−) was estimated from the difference between the sums of the main cations and inorganic anions. The estimate for shoots was compared to the theoretical production of R− associated with NO3− assimilation in these organs, and the difference was attributed to export of R− to roots. The net exchange rates of H+ and OH− between the medium and roots were monitored. The shoots were the site of more than 90% of total NO3− reduction, and Nr was cycling through the plants at a high rate. Alkalinization of the medium by NO3−-fed plants was interrupted by stem girdling, and not restored by glucose addition to the medium. It was concluded that the majority of the base excreted in NO3− medium originated from R− produced in the shoots, and transported to the roots together with K+. As expected, cycling of K+ and reduced N was favoured by NO3− nutrition as compared to urea nutrition. 相似文献
74.
David T. Clarkson Malcolm J. Hawkesford Jean-Claude Davidian Claude Grignon 《Planta》1992,187(3):306-314
The uptake of sulphate into roots of barley seedlings is highly sensitive to phenylglyoxal (PhG), an arginine-binding reagent. Uptake was inhibited by >80% by a 1-h pre-treatment of roots with 0.45 mol · m–3 PhG. Inhibition was maximal in pre-treatment solutions buffered between pH 4.5 and 6.5. Phosphate uptake, measured simultaneously by double-labelling uptake solutions with 32P and 35S, was less susceptible to inhibition by PhG, particularly at pH <6.5, and was completely insensitive to the less permeant reagent p-hydroxyphenylglyoxal (OH-PhG) administered at 1 mol · m–3 at pH at 5.0 or 8.2; sulphate uptake was inhibited in -S plants by 90% by OH-PhG-treatment. Root respiration in young root segments was unaffected by OH-PhG pre-treatment for 1 h and inhibited by only 17% after 90 min pre-treatment. The uptake of both ions was inhibited by the dithiol-specific reagent, phenylarsine oxide even after short exposures (0.5–5.0 min). Sulphate uptake was more severely inhibited than that of phosphate, but in both cases inhibition could be substantially reversed by 5 min washing of treated roots by 5 mol · m–3 dithioerythritol. After longer pre-treatment (50 min) with phenylarsine oxide, inhibition of the ion fluxes was not relieved by washing with dithioerythritol. Inhibition of sulphate influx by PhG was completely reversed by washing the roots for 24 h with culture solution lacking the inhibitor. The reversal was dependent on protein synthesis; less than 20% recovery was seen in the presence of 50 mmol · m–3 cycloheximide. Sulphate uptake declined rapidly when -S roots were treated with cycloheximide. In the same roots the phosphate influx was little affected, small significant inhibitions being seen only after 4 h of treatment. Respiration was depressed by only 20% in apical and by 31% in basal root segments by cycloheximide pre-treatment for 2 h. Similar rates of collapse of the sulphate uptake and insensitivity of phosphate uptake were seen when protein synthesis was inhibited by azetidine carboxylic acid, p-fluorophenylalanine and puromycin. Considering the effects of all of the protein-synthesis inhibitors together leads to the conclusion that the sulphate transporter itself, or some essential sub-component of the uptake system, turns over rapidly with a half-time of about 2.5 h. The turnover of the phosphate transporter is evidently much slower. The results are discussed in relation to strategies for identifying the transport proteins and to the regulation of transporter activity during nutrient stress.Abbreviations CAP
chloramphenicol
- CHM
cycloheximide
- DTE
dithioerythritol
- OH-PhG
p-hydroxyphenylglyoxal
- PhAsO
phenylarsine
- PhG
phenylglyoxal
Paper dedicated to the memory of the late Ken Treharne who did much to encourage this collaboration.D.T.C. gratefully acknowledges a fellowship provided by Le Ministére des Etrangers during his stay in Montpellier. 相似文献
75.
D Desor R J Royer P Netter J C Guedenet G Faure B Krafft G Grignon 《Comptes rendus des séances de la Société de biologie et de ses filiales》1978,172(6):1057-1062
Rattus norvegicus females were treated by diphenylhydantoin (D.P.H.), all along pregnancy and lactation. 4 groups were constituted: a 100 mg DPH/kg/day group, a 50 mg DPH/kg/day group; a placebo group (treated with pure water), and control group. D.P.H. was given twice a day by a gastric tube. The cerebellar Purkinje cells studied through light microscopy and transmission electron microscopy in young rats (25 days old) showed no visible alteration. 2 motorcoordination tests were applied to the young rats, during their 2nd and 3rd weeks of post-natal life. Young rats of DPH 100, DPH 50 and placebo groups showed a backwardness relatively to control. This backwardness may be attributed to the maternal forced feeding stress, but not to a specific action of the DPH. 相似文献
76.
Potassium Stimulation of Corn Root Plasmalemma ATPase : II. H-Pumping in Native and Reconstituted Vesicles with Purified ATPase 总被引:1,自引:1,他引:0
The stimulation by K+ of the initial rate of H+-pumping by ATPase was studied in native plasmalemma (Zea mays L. var Mona) vesicles and in reconstituted vesicles with enzyme purified on a glycerol gradient. In reconstituted vesicles, a very high H+-pumping rate (200,000% quenching per minute per milligram protein) was obtained with 9-amino-6-chloro-2-methoxyacridine provided that the pump was short-circuited by K+-valinomycin. A constant ionic strength was used to prevent indirect stimulation by the electrostatic effects of K+ salts. Indirect stimulation of H+-pumping by the short-circuiting effect of internal K+, could be abolished by using the permeant anions NO3− and Br− in native, but not in reconstituted vesicles. In both materials, half-stimulation of the H+-pumping by K+ was observed at about 5 millimolar. The same stimulation was obtained when K+ was present only in the external solution or when it was present both outside and inside the vesicles. It was concluded that the stimulating effect of K+ on the H+-pumping evidenced in these experiments on both native and reconstituted vesicles was due to a direct effect of the cation on the cytoplasmic face of the ATPase. These results are discussed within the context of the hypothesis of an active K+ transport driven by the ATPase through a direct H+/K+ exchange mechanism. 相似文献
77.
Salinity effects on germination,growth, and seed production of the halophyte Cakile maritima 总被引:1,自引:0,他引:1
The growth ofEucalyptus regnans seedlings in forest soil is enhanced when it has been air-dried. In undried forest soil seedlings grow poorly and develop
purple coloration in the foliage, indicating P deficiency. This paper reports the results of pot experiments designed to investigate
the relationship between growth and P acquisition, ectomycorrhizal infection and age of seedlings grown in air-dried and undried
soil. The effect on seedling growth of their inoculation with air-dried or undried soil or with ectomycorrhizal roots from
plants growing in air-dried or undried soil was also investigated. Ectomycorrhizal root tips were detected in 3-week-oldE. regnans seedlings in both air-dried and undried soil, and from then on the frequency of ectomycorrhizal root tips increased rapidly.
In air-dried soil, seedlings were fully ectomycorrhizal at 9 weeks, and the occurrence of maximum ectomycorrhizal infection
coincided with enhanced P acquisition and the initiation of rapid seedling growth. In undried forest soil, seedling growth
remained poor, even though the seedlings had well-developed ectomycorrhizae and the incidence of ectomycorrhizal root tips
was the same as in air-dried soil. The dominant ectomycorrhizae in airdried soil were associated with an ascomycete fungus,
whereas in undried, undisturbed soil they were commonly associated with basidiomycete fungi. Inoculation of sterile soil/sand
mix with washed ectomycorrhizal roots from air-dried soil increased the P acquisition and growth of the seedlings significantly
compared with controls, whereas ectomycorrhizal inocula from undried soil had no effect on seedling growth, although both
inocula resulted in a similar incidence of ectomycorrhizal root tips. Similarly, addition of a small amount of air-dried soil
into sterile soil/sand mix resulted in a significantly greater increase in the P content and dry weight of the seedlings,
compared with the control, than addition of undried soil. In both treatments, the incidence of ectomycorrhial root tips was
similar. As (i) the differentiation in seedling growth between air-dried and undried soil occurred after seedlings became
ectomycorrhizal, (ii) the dominant ectomycorrhizae in air-dried soil were different from those in undried soil, and (iii)
inocula from air-dried soil, but not from undried soil, stimulated seedling growth in sterile soil/sand mix, it is concluded
that development of particular ectomycorrhizae may be involved in seedling growth stimulation and enhanced P acquisition associated
with air drying of forest soil. 相似文献
78.
Regulation by external K+ in a maize inward shaker channel targets transport activity in the high concentration range 总被引:2,自引:0,他引:2 下载免费PDF全文
An inward Shaker K(+) channel identified in Zea mays (maize), ZmK2.1, displays strong regulation by external K(+) when expressed in Xenopus laevis (African clawed frog) oocytes or COS cells. ZmK2.1 is specifically activated by K(+) with an apparent K(m) close to 15 mM independent of the membrane hyperpolarization level. In the absence of K(+), ZmK2.1 appears to enter a nonconducting state. Thus, whatever the membrane potential, this maize channel cannot mediate K(+) influx in the submillimolar concentration range, unlike its relatives in Arabidopsis thaliana. Its expression is restricted to the shoots, the strongest signal (RT-PCR) being associated with vascular/bundle sheath strands. Based on sequence and gene structure, the closest relatives of ZmK2.1 in Arabidopsis are K(+) Arabidopsis Transporter 1 (KAT1) (expressed in guard cells) and KAT2 (expressed in guard cells and leaf phloem). Patch-clamp analyses of guard cell protoplasts reveal a higher functional diversity of K(+) channels in maize than in Arabidopsis. Channels endowed with regulation by external K(+) similar to that of ZmK2.1 (channel activity regulated by external K(+) with a K(m) close to 15 mM, regulation independent of external Ca(2+)) constitute a major component of the maize guard cell inward K(+) channel population. The presence of such channels in maize might reflect physiological traits of C4 and/or monocotyledonous plants. 相似文献
79.
Cd-induced growth reduction in the halophyte <Emphasis Type="Italic">Sesuvium portulacastrum</Emphasis> is significantly improved by NaCl 总被引:2,自引:0,他引:2
Ghnaya T Slama I Messedi D Grignon C Ghorbel MH Abdelly C 《Journal of plant research》2007,120(2):309-316
The effects of Cd2+ and NaCl, applied together or separately, on growth and uptake of Cd2+ were determined for the halophyte Sesuvium portulacastrum L. Seedlings were cultivated in the presence of 50 or 100 μmol L−1 Cd2+ alone or combined with 100 or 400 mmol L−1 NaCl. Data showed that alone, Cd2+ induced chlorosis, necrosis, and inhibited growth. Addition of NaCl to Cd2+-containing medium restored growth and alleviated the toxicity, however. NaCl also enhanced the amounts of Cd2+ accumulated in the shoots. All Cd2+ treatment reduced K+ and Ca2+ uptake and transport to the shoots. Accumulation of Na+ in the shoots was not affected by Cd2+, however. Thus S. portulacastrum maintained its halophytic characteristics in the presence of Cd2+. We suggest this halophyte could be used for phytoextraction of Cd2+ from salt-contaminated sites. 相似文献
80.
Membrane resistances, electrical potentials and intracellular K+ activity have been studied in protoplasts of Acer pseudoplatanus L. using microelectrodes. The plasmalemma appears to be damaged during protoplast processing, so that it is almost completely depolarized. The positive polarization of the protoplasts is a property of their tonoplast. The osmotic shock of general dilution of the medium brings about a slight positive polarization of the protoplasts, which probably is the consequence of a dilution of the ionic contents of the cell. A rapid dilution of extracellular potassium produces the same effect by a considerable efflux of K+ , which changes the concentration gradient so that electropositivity is accentuated. In general, certain states of shock can cause such polarization. These results, particularly the development of internal potassium activity, help in understanding the initial cause of the positive polarization that is sometimes observed in protoplasts. 相似文献