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21.
By use of the pressure-clamp technique, the hydraulic conductivity of the brackish-water alga Lamprothamnium was found to be 5·10-6 cm s-1 bar-1. The dimensions of the internodes are so small that it is possible, for the first time, to measure a complete volume relaxation upon clamping the turgor pressure to a preset value by a feedback control of the pressure probe. As theoretically predicted, the values of the hydraulic conductivity obtained from the initial slope of the volume relaxation induced by the pressure clamp are in agreement (within experimental error) with those obtained from the half-time of the relaxation process. The cell volume also obtained from the analysis of the volume relaxation is the osmotically effective cell volume and is therefore slightly smaller than the value obtained by taking the dimensions of the cell including the cell wall.Abbreviations and symbols Lp
hydraulic conductivity
- P
turgor pressure
- Sv
initial slope of volume relaxion
- T1/2
half-time of volume relaxation
Dedicated to Professor Dr. H. Ziegler on the occasion of his 60th birthday 相似文献
22.
Y. Heslop-Harrison B. J. Reger J. Heslop-Harrison 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1985,70(3):252-258
Summary Foreign pollen tubes in the stigma of Zea mays can be prevented from reaching the ovary cavity by the unusual length of the pollen tube pathway. A simple and rapid procedure is described for overcoming this difficulty by pollinating the basal parts of the stigmas without removing the ensheathing bracts (husks). The method maintains high humidity in the vicinity of the ovaries, and by conserving photosynthetic tissues probably also ensures a more normal O2 /CO2 balance in the neighbourhood of the stigmas than do bagging procedures. It is shown that Sorghum pollen tubes readily reach the ovary after pollination by the method. Their presence induces some of the characteristic post-pollination effects caused by Zea pollen tubes, but they frequently also stimulate premature enlargement of the nucellus and lysis of nucellar cells. Although Sorghum tubes have been traced across the inner ovary wall, they have not been seen to enter the micropyle, and hybrid embryos have not yet been obtained. 相似文献
23.
Presynaptic modulation by noradrenaline and an opioid of the substance P-induced release of [3H]acetylcholine from the myenteric plexus 总被引:1,自引:0,他引:1
Substance P (7.5-750 nM) applied in superfusion dose-dependently released 3H from isolated strips of myenteric plexus-longitudinal muscle of the guinea-pig ileum loaded with [3H]choline. Separation of the [3H]acetylcholine and [3H]choline components of the released radioactivity revealed that in response to substance P (SP) administration only the release of [3H]acetylcholine increased above resting level. A slowly developing tachyphylaxis to the effect of SP was observed. Evidence has been obtained that the slow tachyphylaxis developed to the acetylcholine-releasing effect of SP was not due to the exhaustion of releasable acetylcholine pool. Release of acetylcholine by 150 nM SP was completely prevented by tetrodotoxin or in a Ca2+-free medium and greatly reduced in the presence of noradrenaline or the opioid receptor agonist (D-Met2,Pro5)-enkephalinamide. The effect of noradrenaline and the opioid peptide was apparently prevented by yohimbine and naloxone, respectively. 相似文献
24.
Peter H. Seidl Jochen R. Golecki Norbert Franken Karl Heinz Schleifer 《Archives of microbiology》1985,142(2):121-127
The peptide subunit pentapeptide H-L-Ala-D-Glu(L-Lys-D-Ala-D-Ala-OH)-NH2 of peptidoglycan was localized in the cell walls of several Gram-positive bacteria employing the indirect immunoferritin technique. Specific antibodies to the D-alanyl-D-alanine moiety of non-crosslinked peptide subunit pentapeptide were raised in rabbits by immunization with synthetic immunogen albumin-(CH2CO-Gly-L-Ala-L-Ala-D-Ala-D-Ala-OH)39. Specificity of these antibodies for the peptide subunit pentapeptide and not for the peptide subunit tetrapeptide was corroborated in a Farr-type radio-active hapten binding assay. Specificity of labelling with ferritin was established by immunoelectron microscopic controls, and by the excellent correlation between specific labelling of cells with ferritin and the particular peptidoglycan primary structure of bacterial strains investigated. Cells of Lactobacillus gasseri, Streptococcus pyogenes and Staphylococcus aureus revealing non-crosslinked peptide subunit pentapeptides in their peptidoglycans could specifically be labelled. Lactobacillus acidophilus and Bacillus subtilis, on the contrary, missing such pentapeptides, failed in labelling.The implication of this method to possibly localize the points of attack of penicillin or cycloserine is discussed.Abbreviations used meso-A2pm
meso-diaminopimelic acid
- DSM
Deutsche Sammlung für Mikroorganismen, Göttingen, FRG
This paper is dedicated to Professor Gerhart Drews on the occasion of his 60th birthday 相似文献
25.
Molecular cloning and nucleotide sequences of cDNAs specific for rat liver ribosomal proteins S17 and L30 总被引:10,自引:0,他引:10
O Nakanishi M Oyanagi Y Kuwano T Tanaka T Nakayama H Mitsui Y Nabeshima K Ogata 《Gene》1985,35(3):289-296
cDNA clones coding for rat liver ribosomal proteins S17 and L30 have been isolated by positive hybridization-translation assay from a cDNA library prepared from 8-9S poly(A)+RNA from free polysomes of regenerating rat liver. The cDNA clone specific for S17 protein (pRS17-2) has a 466-bp insert with the poly(A) tail. The complete amino acid (aa) sequence of S17 protein was deduced from the nucleotide sequence of the cDNA. S17 protein consists of 134 aa residues with an Mr of 15 377. The N-terminal aa sequence of S17 protein determined by automatic Edman degradation is consistent with the sequence data. The aa sequence of S17 shows strong homology (76.9%) to that of yeast ribosomal protein 51 [Teem and Rosbash, Proc. Natl. Acad. Sci. USA 80 (1983) 4403-4407] in the two-thirds N-terminal region. The cDNA clone specific for L30 protein (pRL30) has a 394-bp insert. The aa sequence of L30 protein was deduced from the nucleotide sequence of the cDNA. The protein consists of 114 aa residues with an Mr of 12 652. When compared with the N-terminal aa sequence of rat liver L30 protein [Wool, Annu. Rev. Biochem. 48 (1979) 719-754], pRL30 was found not to contain the initiation codon and 5'-noncoding region. The cDNA showed twelve silent changes in the coding region, one point mutation and one base deletion in the 3'-noncoding region, compared with mouse genomic DNA for L30 protein [Wiedemann and Perry, Mol. Cell Biol. 4 (1984) 2518-2528]. 相似文献
26.
Astrid Christiani Peter Hügelmeyer Prof. Dr. Wilhelm Stockem 《Cell and tissue research》1986,246(1):163-168
Summary Various stabilization and extraction procedures were tested to demonstrate the ultrastructural organization of the cytoskeleton in normal, locomoting Amoeba proteus. Most reliable results were obtained after careful fixation in glutaraldehyde/lysine followed by prolonged extraction in a polyethylene glycol/Triton X-100 solution. Before dehydration in a graded series of ethanol and critical-point drying, the amoebae were split by the sandwich-technique, i.e., by mechanical cleavage of cells mounted between two poly-L-lysine-coated glass slides. Platinum-carbon replicas as well as thin sections prepared from such cell fragments revealed a cytoskeleton composed of at least four different types of filaments: (1) 5–7-nm filaments organized as a more or less ordered cortical network at the internal face of the plasma membrane and probably representing F-actin; (2) 10–12-nm filaments running separately or slightly aggregated through the cytoplasm and probably representing intermediate filaments; (3) 24–26-nm filaments forming a loose network and probably representing microtubules; and (4) 2–4-nm filaments as connecting elements between the other cytoskeleton constituents. Whereas microfilaments are responsible for protoplasmic streaming and other motile phenomena, the function of intermediate filaments and cytoplasmic microtubules in amoebae is still obscure. 相似文献
27.
An apparatus suitable for the recovery of proteins from polyacrylamide gels on a milligram scale by displacement electrophoresis (isotachophoresis) is described along with a buffer system that is suitable for this purpose with most proteins. The technique is illustrated by the recovery of a protein from a 15% polyacrylamide gel. The recovery was almost quantitative and the eluted protein showed little contamination upon quantitative amino acid analysis and automatic Edman degradation. 相似文献
28.
E Gianazza G Dossi F Celentano P G Righetti 《Journal of biochemical and biophysical methods》1983,8(2):109-133
A new technique for generating extended pH gradients (5 pH units) in Immobiline gels is reported. The previously described (J. Biochem. Biophys. Methods 7, 1983, 123-142) five-chamber gradient mixer has been replaced by a two-vessel device. A single mixture of the available Immobilines (pK 3.6, 4.6, 6.2, 7.0, 8.5 and 9.3) is made, with relative concentrations adjusted so as to produce the most uniform buffering power throughout the desired pH interval. This mixture is then divided into two portions, which are titrated to the extremes of the required pH span with an acidic titrant (Immobiline pK approximately 1) and a basic species (Immobiline pK 9.95). Highly reproducible pH gradients (pH 4-9) are thus generated, which appear extremely useful for the first dimensioned of 2-dimensional techniques. Our previously reported computer program has been implemented with an optimization algorithm which, given any cocktail of Immobilines, automatically adjusts the relative initial concentrations until the smoothest possible beta power is found. For the first time it is possible to perform IEF under controlled physico-chemical parameters: pH span and linearity, beta power, ionic strength and molarity of the buffering species. 相似文献
29.
30.
本文介绍了Barnett等1985年编制并由剑桥大学发行的计算机软件《酵母鉴定程序》,以及如何使用该程序在IBM PC DOS操作系统上进行酵母菌的分类鉴定。我们使用该程序对从云南鸡足山和紫金山两地森林土壤中分离到的82株酵母菌进行了分类鉴定,其中:鉴定到种的有47株,占总株数的57.3%;鉴定到属但未能直接定到种的有21株,占总株数的25.6%;暂未定名的有14株,占总株数的17.1%。 相似文献