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81.
Jan Van Parijs Hilde M. Joosen Willy J. Peumans Jan M. Geuns André J. Van Laere 《Archives of microbiology》1992,158(1):19-25
The lectin from stinging nettle rhizomes, Urtica dioica agglutinin (UDA), did not affect the evolution of wet and dry weight, protein, nucleic acid, ATP, cAMP and glycerol content during early germination of Phycomyces blakesleeanus spores. However, earlier investigations established a strongly reduced mycelial growth of several phytopathogenic fungi by this small plant lectin. Total uptake and incorporation of radioactive precursors showed no differences between UDA or control hyphae, but UDA significantly altered the distribution patterns of [14C]-glucose incorporated into the walls of Phycomyces blakesleeanus (more label was recovered in the chitin fraction). Moreover, a small but significant stimulation of chitin synthase and a similar inhibition of chitin deacetylase was found in cell wall preparations. These observations could lead to a better understanding of plant-pathogen interrelationships and to a further elucidation of cell wall structure in fungi.Abbreviations GlcNAc
N-Acetylglucosamine
- PDB
potato dextrose broth
- PMM
Phycomyces minimal medium
- UDA
Urtica dioica agglutinin
- TEA
tri-ethyl-amine
- DAB
1,4-diaminobutanone 相似文献
82.
Summary The obtention of embryogenic competence in Actinidia deliciosa var. deliciosa cv. Hayward is reported. Axillary buds from shoots submitted to cold (4°C) and starvation for 1.5 months, developed leaves with embryogenic competence. These leaves, cultured in darkness for 1.5 months on a medium containing zeatin as a sole growth regulator, originated compact structures from which embryos developed. The plating orientation and sectioning of leaves strongly affected the expression of the embryogenic potential. A selected fraction of the protoplasts isolated from these leaves was able to develop in an embryogenic way. The germination of the embryos is still only occasional.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- 2-iP
6-dimethylallyl aminopurine
- IAA
indole-3-acetic acid
- NOA
naphthoxyacetic acid
- SEM
Scanning Electron Microscopy 相似文献
83.
Viability measurements of hybridoma cells in suspension cultures 总被引:1,自引:0,他引:1
José M. Coco-Martin Jan W. Oberink Tiny A. M. van der Velden-de Groot E. Coen Beuvery 《Cytotechnology》1992,8(1):57-64
Several methods were applied to determine the viability of hybridoma cells in suspension. These methods include dye inclusion
and exclusion assays such as the classical trypan blue exclusion assay, the propidium iodide (PI) exclusion assay and the
fluorescein diacetate (FDA) inclusion assay. Furthermore, the relation was studied between release of lactate dehydrogenase
(LDH) by hybridoma cells and their viability. Also the ATP content of the cells and cellular heterogeneity as measured with
a flow cytometer were determined in relation to cellular viability.
The dye inclusion and exclusion assays using trypan blue, FDA, PI were shown to be useful methods to determine cellular viability.
With the FDA and PI methods it was possible to obtain additional information about cells which are in a transition state between
viable and non-viable. The viability according to the scatter properties of the cells appears to reflect the overall condition
of the cells, although interpretation of the results is difficult. Measurement of LDH release in the culture fluid or the
cytoplasmic ATP content could not be used as parameters for cell viability. 相似文献
84.
José L. Caballero Eduardo Martinez Francisco Malpartida David A. Hopwood 《Molecular & general genetics : MGG》1991,230(3):401-412
Summary Sequence analysis of the actVA region of the actinorhodin biosynthetic gene cluster of Streptomyces coelicolor revealed a succession of six open reading frames (ORFs), all running in the same direction and extending over 5.32 kb. The protein product of actVA-ORF1 strongly resembles that of another gene, elsewhere in the act cluster (actII-ORF2), which codes for a trans-membrane protein previously implicated in actinorhodin export from the mycelium. This suggests that the two gene products may co-operate in actinorhodin export, perhaps being sufficient for self-protection of the organism against suicide. At least four of the other five ORFs are implicated in the control of the C-6 and C-8 ring-hydroxylation reactions, lacking in actVA mutants, that occur at middle to late stages in the actinorhodin biosynthetic pathway. This conclusion was reached by genetic mapping of actVA mutants to actVA-ORF3 and-ORF5 (and perhaps -ORF4), and by the finding of strong resemblances between the protein products of actVA-ORF2 and -ORF6 and the products of genes of the oxytetracycline or tetracenomycin gene clusters that have been implicated in ring-hydroxylation reactions in the biosynthesis of these other aromatic polyketide antibiotics. 相似文献
85.
Claire Domon Jean-Luc Evrard Datta T.N. Pillay André Steinmetz 《Molecular & general genetics : MGG》1991,229(2):238-244
Summary Metabolism of sulfonylurea herbicides by Streptomyces griseolus ATCC 11796 is carried out via two cytochromes P-450, P-450SU1 and P-450SU2. Mutants of S. griseolus, selected by their reduced ability to metabolize a fluorescent sulfonylurea, do not synthesize cytochrome P-450SU1 when grown in the presence of sulfonylureas. Genetic evidence indicated that this phenotype was the result of a deletion of > 15 kb of DNA, including the structural genes for cytochrome P-450SU1 and an associated ferredoxin Fd-1 (suaC and suaB, respectively). In the absence of this monooxygenase system, the mutants described here respond to the presence of sulfonylureas or phenobarbital in the growth medium with the expression of only the suhC,B gene products (cytochrome P-450SU2 and Fd-2), previously observed only as minor components in wild-type cells treated with sulfonylurea. These strains have enabled an analysis of sulfonylurea metabolism mediated by cytochrome P-450SU2 in the absence of P-450SU1, yielding an in vivo delineation of the roles of the two different cytochrome P-450 systems in herbicide metabolism by S. griseolus. 相似文献
86.
Stromal low temperature compartment derived from the inner membrane of the chloroplast envelope 总被引:3,自引:0,他引:3
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Leaf discs of four dicotyledonous species, when incubated at temperatures of 4 to 18°C (optimum at 12°C) for 30 or 60 minutes, responded by accumulations of membranes in the chloroplast stroma in the space between the inner membrane of the envelope and the thylakoids. The accumulated membranes, here referred to as the low temperature compartment, were frequently continuous with the envelope membrane and exhibited kinetics of formation consistent with a derivation from the envelope. Results were similar for expanding leaves of garden pea (Pisum sativum), soybean (Glycine max), spinach (Spinacia oleracea), and tobacco (Nicotiana tabacum). We suggest that the stromal low temperature compartment may be analogous to the compartment induced to form between the transitional endoplasmic reticulum and the Golgi apparatus at low temperatures. The findings provide evidence for the possibility of a vesicular transfer of membrane constituents between the inner membrane of the chloroplast envelope and the thylakoids of mature chloroplasts in expanding leaves. 相似文献
87.
Activation of Plasma Membrane NADH Oxidase Activity by Products of Phospholipase A 总被引:1,自引:0,他引:1
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An auxin-stimulated NADH oxidase activity (NADH oxidase I) of plasma membrane vesicles, highly purified by aqueous two-phase partition from soybean (Glycine max Merr.) hypocotyls was activated by lysophospholipids and fatty acids, both products of phospholipase A action. The activation of NADH oxidase activity occurred slowly, suggesting a mechanism whereby the lipids acted to stabilize the enzyme in a more active configuration. In contrast to activation by lipids, the activation by auxin was rapid. The average Km of the NADH oxidase after activation by lipids was four- to fivefold less than the Km before activation. The Vmax was unchanged by activation. The increases occurred in the presence of detergent and thus were not a result of exposure of latent active sites. Also, the activation did not result from activation of a peroxidase or lipoxygenase. Fatty acid esters, where growth promoting effects have been reported, also activated the auxin-stimulated oxidase. However, the auxin stimulation of NADH oxidase I did not appear to be obligatorily mediated by phospholipase A, nor did inhibitors of phospholipase A2 block the stimulation of the oxidase by auxins. 相似文献
88.
The primary structure of the HLA-A2 subtype A*0204 (isoelectric focusing variant A2.A) has been determined. cDNA encoding this subtype was amplified by the polymerase chain reaction. Four independent full-lenght cDNA clones encoding A*0204 were analyzed to obtain a consensus sequence for this subtype. A*0204 differs from A*0201 by a single nucleotide change of G to T through the coding regions, resulting in an Arg to Met change at position 97. This substitution accounts for the isoelectric focusing pattern of the subtype. The same change occurs in other HLA-A specificities in association with other changes in its vicinity. The absence of additional substitutions in A*0204 suggests that it could have arisen from A*0201 by point mutation, and that recurrent mutations may take place during HLA diversification. The spatial location of this change implies that A*0204 must be a functional variant. Comparison of its sequence with other HLA-A2 subtypes reveals that much of the HLA-A2 subtype polymorphism is generated by variations in four neighboring positions, including position 97, which are located in two adjacent -strands on the floor of the peptide binding site of the molecule.The nucleotide sequence data reported in this paper have been submitted to the EMBL nucleotide sequence database and have been assigned the accession number X57954.
Address correspondence and offprint requests to: J. A. López de Castro. 相似文献
89.
Cecilia Zazueta José A. Holguín Jorge Ramírez 《Journal of bioenergetics and biomembranes》1991,23(6):889-902
We describe a calcium transport that is sensitive to ruthenium red in liposomes reconstituted with mitochondrial extracts. This system is able to build an internally negative membrane potential, which allows the electrogenic influx of Ca2+ and Sr2+. Proteins with molecular weights higher than 35 kDa were incorporated to the vesicles, and enhanced the accumulation of the cation in an energy-dependent fashion. 相似文献
90.
Chloramphenicol acetyl transferase (CAT) gene was used as a reporter gene to assess the conditions for polyethylene glycol (PEG)-mediated transfection of kiwifruit protoplasts. The effect of plasmid concentration and the presence of carrier DNA were each assessed by analysing CAT activity in transfected protoplasts using thin-layer chromatography (TLC) autoradiographic detection of acetylated chloramphenicol. A gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) non-radioactive method was developed for monitoring CAT gene activity. This method provides a high speed of analysis (30 min) and precise means of detecting acetylated products at the nanomolar level, enabling quantification at very low transfection rates. Using this method we optimized plasmid and PEG concentration and also assessed the effect of heat shock on transfection. The best CAT activity was obtained using 30% polyethylene glycol 4000 and by submitting protoplasts to heat shock (45 °C, 5 min) prior to transfection. 相似文献