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101.
Leaf-specific thionins of barley (Hordeum vulgare L.) have been identified as a novel class of cell-wall proteins toxic to plant-pathogenic fungi and possibly involved in the defence mechanism of plants. The distribution of these polypeptides has been studied in the host-pathogen system of barley and Erisyphe graminis DC.f.sp. hordei Marchal (powdery mildew). Immunogold-labelling of thionins in several barley cultivars indicates that resistance or susceptibility may be attributed to the presence or absence of thionins at the penetration site in walls and papillae of epidermal leaf cells.All of the leaf-specific thionin genes are confined to the distal end of the short arm of chromosome 6 of barley. None of the genes for cultivarspecific resistance to powdery mildew which have previously been mapped on barley chromosomes are found close to this locus. 相似文献
102.
Jürgen Voigt Dieter Mergenhagen Petra Münzner Hans-Peter Vogeler Klaus Nagel 《Planta》1989,178(4):456-462
In light-dark-synchronized cultures of the unicellular green algaChlamydomonas reinhardtii, release of zoospores from the wall of the mother cell normally takes place during the second half of the dark period. The recently isolated mutant ls, however, needs light for the liberation of zoospores when grown photoautotrophically under a 12 h light-12 h dark regime. The light-induced release of zoospores was found to be prevented by addition of the photosystem-II inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Furthermore, light dependence of this process was shown to be abolished when the mutant ls was grown either photoautotrophically under a 14 h light-10 h dark regime or in the presence of acetate. Our findings indicate that the light-dependency of zoospore liberation observed in cultures of this particular mutant during photoautotrophic growth under a 12 h light-12 h dark regime might be attributed to an altered energy metabolism. The light-induced release of zoospores was found to be prevented by addition of cycloheximide or chloramphenicol, antibiotics which inhibit protein biosynthesis by cytoplasmic and organellar ribosomes, respectively. Actinomycin D, an inhibitor of RNA synthesis, however, did not affect the light-induced liberation of zoospores.Sporangia accumulate in stationary cultures of the mutant ls. Release of zoospores was observed when these sporangia were collected by centrifugation and incubated in the light after resuspension in fresh culture medium. Since liberation of zoospores was not observed after dilution of the stationary cultures with fresh culture medium, we suppose that components which interfere with the action of the sporangial autolysin are accumulated in the culture medium of the mutant ls.Abbreviation DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea 相似文献
103.
Studies of the oxysterol inhibition of tumor cell growth 总被引:2,自引:0,他引:2
The oxysterols 3 beta-hydroxy-5 alpha-cholest-8-en-11-one, 3 beta-hydroxy-5 alpha-cholest-8-en-7-one, 3 beta-hydroxy-5 alpha-cholest-8(14)-en-7-one, 3 beta-hydroxy-4,4'-dimethylcholest-5-ene-7 one, 4,4'-dimethylcholest-5-ene-3 beta, 7 alpha-diol, 4,4'-dimethylcholest-5-ene-3 beta, 7 beta-diol, lanost-8-ene-3 beta, 25-diol, 25-hydroxylanost-8-en-3-one, 9 alpha, 11 alpha-epoxy-5 alpha-cholest-7-en-3 beta-ol, 3 beta-hydroxycholest-5 alpha-en-22-one, and 3 beta-hydroxycholest-5-en-22-one oxime were evaluated with respect to their ability to inhibit cell growth. All of the sterols were found to possess cytotoxicity when incubated with hepatoma (HTC) and lymphoma (RDM-4) cells in culture at 10-30 microM concentrations. 相似文献
104.
A mutant rat major histocompatibility haplotype showing a large deletion of class I sequences 总被引:2,自引:2,他引:0
The LEW.1LM1 inbred rat strain, which has been derived from a (LEW×LEW.1W) F2 hybrid, carries a major histocompatibility (RT1) haplotype which is distinct from that of the LEW strain (RT1
1) in that certainRT1.C region-determined class I antigens are not expressed. Here we show that this phenotypic defect is due to genomic deletion
of about 100 kb of theRT1.C region. Certain deleted DNA fragments have been cloned from the wild-type DNA into the EMBL4 vector. Five clones have been
characterized and are shown to possess different restriction maps and to each carry a single stretch of class I cross-hybridizing
sequences. Probes derived from the non-class I coding part of two clones detect fragments which are present in the wild-type
but absent from thelm1 mutant. The type of deletion described here in the rat is discussed in the context ofH-2D/Q deletions in the mouse. 相似文献
105.
106.
107.
Bioluminescence of the insect pathogen Xenorhabdus luminescens 总被引:2,自引:0,他引:2
Luminescence of batch cultures of Xenorhabdus luminescens was maximal when cultures approached stationary phase; the onset of in vivo luminescence coincided with a burst of synthesis of bacterial luciferase, the enzyme responsible for luminescence. Expression of luciferase was aldehyde limited at all stages of growth, although more so during the preinduction phase. Luciferase was purified from cultures of X. luminescens Hm to a specific activity of 4.6 x 10(13) guanta/s per mg of protein and found to be similar to other bacterial luciferases. The Xenorhabdus luciferase consisted of two subunits with approximate molecular masses of 39 and 42 kilodaltons. A third protein with a molecular mass of 24 kilodaltons copurified with luciferase, and in its presence, either NADH or NADPH was effective in stimulating luminescence, indicating that this protein is an NAD(P)H oxidoreductase. Luciferases from two other luminous bacteria, Vibrio harveyii (B392) and Vibrio cholerae (L85), were partially purified, and their subunits were separated in 5 M urea and tested for complementation with the subunits prepared from X. luminescens Hb. Positive complementation was seen with luciferase subunits among all three species. The slow decay kinetics of the Xenorhabdus luciferase were attributed to the alpha subunit. 相似文献
108.
Klaus Rohde 《Systematic parasitology》1989,14(2):79-91
The following gill monogeneans are described, based on a survey of 240 Rastrelliger kanagurta, 12 R. faughni and 185 R. brachysoma (Scombridae) from many geographical areas: Eyelavera typica from R. kanagurta, R. faughni and R. brachysoma, Indomazocraes jagannath from R. kanagurta and R. faughni, Kuhnia sprostonae from R. kanagurta and R. brachysoma, and Kuhnia scombercolias from R. kanagurta and R. brachysoma. Eyelavera parukhini Lebedev, 1980 is synonymised with E. typica, Scomberocotyle eyela Unnithan, 1964 with Indomazocraes jagannath, Kuhnia microlepidotusi Gupta & Krishna, 1977 and K. kanagurta Mamaev & Parukhin, 1986 with K. sprostonae, K. arabica Mamaev & Parukhin, 1986 with K. scombercolias Nasir & Fuentes Zambrano, 1983. It is emphasized that populations of Monogenea from the same host species or genus in different geographical areas are likely to be conspecific, and should not be described as different species, if they differ only slightly from each other. Monogenea that differ from insufficiently described species in minor detail should not be described as new species unless material of the original species has been examined. 相似文献
109.
Andrea Schmidt Stephanie Bringer-Meyer Karl Poralla Hermann Sahm 《Applied microbiology and biotechnology》1989,30(2):170-175
Summary The influence of different primary aliphatic alcohols on the activities of two key enzymes in hopanoid biosynthesis of Zymomonas mobilis was investigated. By use of 14C- and 3H-labelled substrates the enzymes 3-hydroxy-3-methylglutaryl-CoA-reductase and squalene-hopenecyclase were detected with activities of 1.6 pmol x (min x mg protein)-1 and 2.3 pmol x- (min x mg protein)-1, respectively. Cells grown in the presence of 6% (v/v) ethanol did not show higher activities of these enzymes than cells grown in the presence of 1% (v/v) ethanol. Furthermore, 3-hydroxy-3-methylglutaryl-CoA-reductase was not activated by ethanol. However, ethanol activated the squalene-hopene-cyclase when added to the enzyme test system. Besides ethanol, propanol also had a positive effect on the squalene-hopene-cyclase: the enzyme's activity increased 1.7-fold in the presence of either alcohol at a concentration of 6% (v/v). This corresponded with a similar increase of hopanoid content of whole cells when grown in the presence of 6% (v/v) added ethanol or propanol. These results indicated that the squalene-hopene-cyclase has a regulatory function in the alcohol dependent hopanoid biosynthesis of Z. mobilis.Abbreviation HMG-CoA-reductase
3-hydroxy-3-methylglutaryl-coenzyme A-reductase 相似文献
110.
Heike Schmidt Rüdiger Bode Ida A. Samsonova Dieter Birnbaum 《Applied microbiology and biotechnology》1989,31(5-6):463-466
Summary Mutants of Candida maltosa were isolated that lacked saccharopine reductase (lys9) and saccharopine dehydrogenase (lys1) and were able to accumulate -aminoadipate--semialdehyde (AASA) in the cell and excrete it into the culture medium. The effects of incubation time, lysine concentration, and carbon and nitrogen sources on AASA production were examined. In the presence of 15 g glucose/1, 1.25 g NH4H2PO4/l and 50 mg l-lysine/l in a minimal salt medium C. maltosa G285 (lys1) produced about 80–90 mg AASA/l during 48 h of growth. A simple and rapid procedure to isolate AASA from the medium using Dowex 50X4 is described. 相似文献