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21.
Valérie Toulon Hervé Sentenac Jean-Baptiste Thibaud André Soler David Clarkson Claude Grignon 《Planta》1989,179(2):235-241
The effect of HCO
3
-
on ion absorption by young corn roots was studied in conditions allowing the independent control of both the pH of uptake solution and the CO2 partial pressure in air bubbled through the solution. The surface pH shift in the vicinity of the outer surface of the plasmalemma induced by active H+ excretion was estimated using the initial uptake rate of acetic acid as a pH probe (Sentenac and Grignon (1987) Plant Physiol. 84, 1367). Acetic acid and orthophosphate uptake rates and NO
3
-
accumulation were slowed down, while 86Rb+ uptake and K+ accumulation rates were increased by HCO
3
-
. These effects were similar to those induced by 4-(2-hydroxyethyl)-1-piperazineethane sulfonic acid/2-amino-2-(hydroxymethyl)-1,3-propanediol (Hepes-Tris). They were more pronounced when the H+ excretion was strong, were rapidly reversible and were not additive to those of Hepes-Tris. The hypothesis is advanced that the buffering system CO2/H2CO3/HCO
3
-
accelerated the diffusion of equivalent H+ inside the cell wall towards the medium. This attenuated the surface pH shift in the vicinity the plasma membrane and affected the coupling between the proton pump and cotransport systems.Abbreviations FW
fresh weight
- Hepes
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- Jaa
acetic acid influx
- JK
+
K+ influx
- JPi
orthophosphate influx
- Mes
2-(N-morpholino)ethanesulfonic acid
- pCO2
CO2 partial pressure
- Tris
2-amino-2-(hydroxymethyl)-1,3-propanediol 相似文献
22.
G. -J. A. Vidugiris A. V. Gudavičius V. J. Razumas J. J. Kulys 《European biophysics journal : EBJ》1989,17(1):19-23
Surface enhanced Raman scattering (SERS) of some enzymes (alkaline phosphatase, horseradish peroxidase and lactoperoxidase) and some amino acids (tryptophan, tyrosine and phenylalanine) on silver electrodes has been studied. The spectral band intensities of certain amino acids and amino acid residues were determined by their orientation on the surface and depended on the electrode potential (E).Abbreviations SERS
surface enhanced Raman scattering
- Trp
tryptophan
- Tyr
tyrosine
- Phe
phenylalanine
- E
electrode potential
- ORC
oxidation-reduction cycle 相似文献
23.
云南呈贡梁王山现代花粉雨的研究 总被引:13,自引:1,他引:12
本文通过对云南呈贡梁王山5块表土分析,初步研究了主要植物花粉的百分含量与其植物覆盖率之间的数量关系,并用校正系数R值表示。按照R值的大小,分为两组:R>1属于超代表性,包括有松、桤木、马桑、蒿和部分蕨类植物;R<1属于低代表性,包括有油杉、栲和石栎、滇青冈、栎、铁仔。在分析松粉分布特征基础上,认为昆明地区西风急流对松粉的传播是主要因素。 相似文献
24.
The surface potential of the purple membrane was measured by a novel method by using an artificial bacteriorhodopsin whose chromophore was 13-CF3 retinal instead of retinal. When attached to the apoprotein by a Schiff base, the intrinsic pK of the 13-CF3 chromophore is around 7.3. The apparent pK of this pigment depends on the surface potential and thus on the electrolyte concentration. This allowed us to determine the surface charge density using the Gouy-Chapman equation. The surface charge density was found to be −1.65 ± 0.15 × 10−3 electronic charges per Å2 or about 2 negative charges/bacteriorhodopsin. This large value for the surface potential probably explains both part of the strong apparent association of divalent cations with the membrane and the effect of low salt concentrations on light-induced proton release from the purple membrane. 相似文献
25.
Summary Monoclonal antibodies were raised against germinal vesicles which were isolated from fully grown oocytes of the ascidianHalocynthia roretzi. Immunoblot analyses revealed that one of the antibodies, designated Hgv-2, recognized a single band with a molecular weight of about 83 kDa. The antibody, visualized by indirect immunohistochemistry, reacted only with the germinal vesicles of oocytes and did not react with test cells, follicle cells, and other somatic cells of the gonad. During embryogenesis the antigenicity was found in interphase nuclei of all embryonic cells. The antibody did not react with chromosomes or the mitotic apparatus. The antigenicity was retained by interphase nuclei of larval cells, but it disappeared from nuclei of juveniles about 7 days after metamorphosis. 相似文献
26.
A total of 627 cattle representing seven breeds from south central Nebraska, USA were tested for 37 BoLA antigens which behave as products of 37 distinct alleles of the class I BoLA-A locus. Four antigens were absent from all breeds tested. The other antigens showed marked and statistically significant differences in breed distribution. There was no evidence for blank (null) alleles. The number of alleles in each breed ranged from 10 to 20. The Hereford and Simmental populations tested were less polymorphic than the Angus, Brown Swiss, Charolais, Gelbvieh and Limousin populations. 相似文献
27.
Hiroshi Suzuki Hideaki Taguchi Kazuko Nishimura Makoto Miyaji Akira Nakamura Hironori Nakajima 《Mycopathologia》1988,104(1):7-17
Summary The authors succeeded in establishing a murine model of systemic candidiasis being disseminated from the primary gastrointestinal lesions caused by oral inoculation of Candida albicans. Using this model, an attempt was made for detecting the Candida antigen by enzyme-linked immunosorbent assay using avidin-biotin (AB-ELISA) from the serum of infected mice.Gastrointestinal candidiasis was formed in all of the 20 mice treated with the drugs (antibiotics, antineoplastic agents, hydrocortisone, etc.) and inoculated orally with C. albicans. Fourteen of these mice suffered from submucosal candidiasis, and C. albicans was cultured from the visceral organs in 12 of them. The assay by AB-ELISA was able to detect 1.0 ng/ml Candida mannan in the mouse serum. The Candida antigen was detected in the sera of 11 of the 14 mice with submucosal candidiasis. However, the antigen could not be detected in the sera of the 6 mice with intramucosal candidiasis.The assay by AB-ELISA is more sensitive and specific for the diagnosis of systemic candidiasis than other serological assays. 相似文献
28.
Flow cytometry (FCM) in conjunction with immunocytochemical-labeling was used to analyze and screen a population of Escherichia coli clones containing a genomic library from the oil-degrading microorganism Acinetobacter calcoaceticus RAG-1 for the isolation of clones which expressed specific RAG-1 surface antigens. Reconstruction experiments using mixed populations indicated that RAG-1 cells could be clearly distinguished at a ratio of one RAG-1 cell to 500 Escherichia coli cells. Using this technique two clones, WM143 and WM191, were isolated and shown by restriction endonuclease cleavage and Southern hybridization to contain plasmids carrying inserts of RAG-1 DNA of 9.4 and 9.8 kb respectively.Non-common abbreviations FCM
flow cytometry
- FITC
fluorescein-iso-thiocyanate
- LB
Luria broth
- MM
minimal salt medium
- PBS
phosphate buffered saline
- PMSF
phenylmethylsulfonyl fluoride 相似文献
29.
John M. Fairbrother Réal Lallier Linda Leblanc Mario Jacques Serge Larivière 《FEMS microbiology letters》1988,56(3):247-252
Abstract The production of fimbrial antigen F165 by Escherichia coli strains was found to be dependent on the composition of the culture medium and was repressed in the presence of alanine or high levels of glucose, in anaerobic conditions or at growth temperatures of lower than 37°C. Optimal F165 production was found on a minimal medium containing 1% (w/v) casamino acids (MD-1). F165 antigen was isolated from bacteria by mechanical shearing, precipitated with ammonium sulfate, and purified by deoxycholate treatment and gel filtration on Superose 12. The purified fimbriae retained their native morphology as observed by electron microscopy and consisted of two separate protein subunits with apparent molecular weights of 17 500 and 19 000 on sodium dodecyl sulfate-polyacrylamide gels. 相似文献
30.
M. Wachsman L. Aurelian J. C. R. Hunter M. E. Perkus E. Paoletti 《Bioscience reports》1988,8(4):323-334
We studied the effect of the temporal regulation of herpes simplex virus (HSV) type 1 glycoprotein D (gD-1) expression in Ia+ epidermal cells (EC) and macrophages on virus specific immunity and protection from HSV-2 challenge. gD-1 was expressed on the surface of cells infected with a vaccinia recombinant containing gD-1 under the control of an early vaccinia virus promoter (VP176). It was not expressed in cells infected with a recombinant (VP254) in which gD-1 is controlled by a late vaccinia virus promoter. BALB/c mice immunized with both recombinants seroconverted to HSV-2 as determined by neutralization. However, HSV specific delayed type hypersensitivity (DTH) responses were significantly (p<0.025) higher in VP176 than VP254 immunized animals. Both VP176 and VP254 immunized mice were protected from severe neurological disease due to HSV-2 challenge at 14 days post immunization, but long term protection was observed only in VP176 immunized mice. 相似文献