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Systemic Induction of Resistance in Potato Plants Against Phytophthora infestans by Local Treatment with Hyphal Wall Components of the Fungus 总被引:2,自引:0,他引:2
Potato plants (cv.‘Irish Cobbler’ with no major resistance genes to Phytophthora infestans), the lower or upper leaves of which were previously treated with hyphal wall components (HWC) of the fungus by rubbing with carborundum, acquired an induced resistance in other untreated leaves against cultivar-pathogenic races of P. infestans when challenged by spraying with a zoospore suspension. Such induced resistance was significantly shown to exist from at least 1 to 20 days after induction treatment with HWC. Thus, the treated plants were protected from severe late blight disease while non-induced control plants finally died of the disease. The induced resistance was due to a reduction of the number of successfully germinating zoospores, and subsequent penetration and then occurrence of hypersensitive-like cell response to the penetrating organisms. These results suggested that local leaf tissues of potato plants reacting to HWC may provide some systemic information that activates or enhances some resistance to P. infestans. 相似文献
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Optimum growth conditions and inoculation regimes were determined for severalFrankia strains isolated from both Alnus and Casuarina host plants. Growth conditions were estabilished that allowed a reduction in generation time to less than 15 hours for certain Alnus derivedFrankia. Differences in plant growth response were observed with differing inoculum levels and soil mixtures. Elite strains of Alnus derivedFrankia were isolated that elicited similar growth reponses in allAlnus species tested; however, differences were observed betweenFrankia strains and plant growth response of variousCasuarina species tested. 相似文献
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Anomeric specificity of D-glucose phosphorylation by rat liver glucose-6-phosphatase. 总被引:1,自引:1,他引:0
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The anomeric specificity of D-glucose phosphorylation by hepatic glucose-6-phosphatase was examined in rat liver microsomes incubated in the presence of carbamoyl phosphate. At 10 degrees C, the Km for the equilibrated hexose and phosphate donor was close to 56 mM and 11 mM, respectively. The enzymic activity, which was increased in diabetic rats, was about 40% lower in untreated than in sonicated microsomes. No anomeric difference in affinity was found in sonicated microsomes. In untreated microsomes, however, the Km for beta-D-glucose was slightly lower than that for alpha-D-glucose. The maximal velocity was higher with beta- than alpha-D-glucose in both untreated and sonicated microsomes. These data indicate that the phosphotransferase activity of glucose-6-phosphatase cannot account for the higher rate of glycolysis and glycogen synthesis found in hepatocytes exposed to alpha- rather than beta-D-glucose. 相似文献
8.
Structure and evolution of the L11, L1, L10, and L12 equivalent ribosomal proteins in eubacteria, archaebacteria, and eucaryotes 总被引:7,自引:0,他引:7
C Ramirez L C Shimmin C H Newton A T Matheson P P Dennis 《Canadian journal of microbiology》1989,35(1):234-244
The genes corresponding to the L11, L1, L10, and L12 equivalent ribosomal proteins (L11e, L1e, L10e, and L12e) of Escherichia coli have been cloned and sequenced from two widely divergent species of archaebacteria, Halobacterium cutirubrum and Sulfolobus solfataricus, and the L10 and four different L12 genes have been cloned and sequenced from the eucaryote Saccharomyces cerevisiae. Alignments between the deduced amino acid sequences of these proteins and to other available homologous proteins of eubacteria and eucaryotes have been made. The data suggest that the archaebacteria are a distinct coherent phylogenetic group. Alignment of the proline-rich L11e proteins reveals that the N-terminal region, believed to be responsible for interaction with release factor 1, is the most highly conserved region and that there is specific conservation of most of the proline residues, which may be important in maintaining the highly elongated structure of the molecule. Although L11 is the most highly methylated protein in the E. coli ribosome, the sites of methylation are not conserved in the archaebacterial L11e proteins. The L1e proteins of eubacteria and archaebacteria show two regions of very high similarity near the center and the carboxy termini of the proteins. The L10e proteins of all kingdoms are colinear and contain approximately three fourths of an L12e protein fused to their carboxy terminus, although much of this fusion has been lost in the truncated eubacterial protein. The archaebacterial and eucaryotic L12e proteins are colinear, whereas the eubacterial protein has suffered a rearrangement through what appear to be gene fusion events. Within the L12e derived region of the L10e proteins there exists a repeated module of 26 amino acids, present in two copies in eucaryotes, three in archaebacteria, and one in eubacteria. This modular sequence is apparently also present in the L12e proteins of all kingdoms and may play a role in L12e dimerization, L10e-L12e complex formation, and the function of the L10e-L12e complex in translation. 相似文献
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J. M. Ramirez K. G. Pearson 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1990,167(4):475-483
1. The effect of phentolamine on the response properties of insect mechanoreceptors and on the conduction in their axons was examined using electrophysiological techniques. 2. Phentolamine blocked conduction of action potentials along axons, an effect which exhibited 3 characteristics typical of local anesthetics: the effect was frequency-dependent, reversible and varied for nerves with different diameters. 3. The concentration of phentolamine required to block axonal conduction (1-2 x 10(-3) M) was significantly higher than that required to abolish the response of receptors to mechanical stimulation (3-5 x 10(-4) M). 4. All mechanoreceptors that were examined in Locusta migratoria and Periplaneta americana were inactivated by phentolamine (Table 1). The type I receptors (chordotonal, campaniform and hair sensilla) were inactivated within 5-15 min following phentolamine application. The only type II receptor examined (forewing stretch-receptor) underwent a phase of repetitive discharge before being inactivated. 5. Tolazoline and metoclopramide inactivated, like phentolamine, mechanoreceptors at lower concentrations than necessary to block axonal conduction. However, yohimbine and chlorpromazine inactivated mechanoreceptors and blocked axonal conduction at similar concentrations. 6. These findings suggest that phentolamine affects sense-organ specific ionic processes that are more sensitive to the drug than the ionic processes along the axons. 相似文献
10.
Aminopeptidase activity is asymmetrically distributed in selected zones of rat brain 总被引:1,自引:0,他引:1
Levels of soluble aminopeptidase (AP), measured as arylamidase activity using L-Leucine-2-Naphthylamide (Leu-2-NA) as substrate, were determined in the soluble fraction of eleven zones of rat brain. Results showed that AP activity is asymmetrically distributed in frontal cortex and hypothalamus with both left sides having significantly higher levels of AP activity, respectively, than the right sides. Simultaneously, the activities of lactate dehydrogenase (LDH) and glutamate-oxalacetate aminotransferase (GOT) were measured in the same cerebral regions; no significant difference was recorded in these activities between either side of the rat brain in any of the zones studied. Provided that aminopeptidases are involved in the degradation of some endogenously released neuropeptides, the results suggest a new mode of expression of cerebral lateralization. 相似文献