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51.
Molecular cloning of a metallothionein-like gene from Nicotiana glutinosa L. and its induction by wounding and tobacco mosaic virus infection. 总被引:4,自引:1,他引:3
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The cloning and characterization of genes expressed in plant disease resistance could be an initial step toward understanding the molecular mechanisms of disease resistance. A metallothionein-like gene that is inducible by tobacco mosaic virus and by wounding was cloned in the process of subtractive cloning of disease resistance-response genes in Nicotiana glutinosa. One 530-bp cDNA clone (KC9-10) containing an open reading frame of 81 amino acids was characterized. Genomic Southern blot hybridization with the cDNA probe revealed that tobacco metallothionein-like genes are present in few or in one copy per diploid genome. Northern blot hybridization detected strong induction of a 0.5-kb mRNA by wounding and tobacco mosaic virus infection, but only mild induction was detected when copper was tested as an inducer. Methyl jasmonate, salicylic acid, and ethylene were also tested as possible inducers of this gene, but they had no effect on its expression. The possible role of this gene in wounded and pathogen-stressed plants is discussed. 相似文献
52.
Purification and characterization of a fibrinolytic enzyme produced from Bacillus sp. strain CK 11-4 screened from Chungkook-Jang. 总被引:13,自引:0,他引:13
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Bacillus sp. strain CK 11-4, which produces a strongly fibrinolytic enzyme, was screened from Chungkook-Jang, a traditional Korean fermented-soybean sauce. The fibrinolytic enzyme (CK) was purified from supernatant of Bacillus sp. strain CK 11-4 culture broth and showed thermophilic, hydrophilic, and strong fibrinolytic activity. The optimum temperature and pH were 70 degrees C and 10.5, respectively, and the molecular weight was 28,200 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The first 14 amino acids of the N-terminal sequence of CK are Ala-Gin-Thr-Val-Pro-Tyr-Gly-Ile-Pro-Leu-Ile-Lys-Ala-Asp. This sequence is identical to that of subtilisin Carlsberg and different from that of nattokinase, but CK showed a level of fibrinolytic activity that was about eight times higher than that of subtilisin Carlsberg. The amidolytic activity of CK increased about twofold at the initial state of the reaction when CK enzyme was added to a mixture of plasminogen and substrate (H-D-Val-Leu-Lys-pNA). A similar result was also obtained from fibrin plate analysis. 相似文献
53.
H. L. Sudan C. J. Kerry I. R. Mellor S. -K. Choi D. Huang K. Nakanishi P. N. R. Usherwood 《Invertebrate neuroscience : IN》1995,1(2):159-172
The effects of philanthotoxin-343 (PhTX-343; tyrosyl-butanoyl-spermine) and photolabile analogues of this synthetic toxin
on locust (Schistocerca gregaria) skeletal muscle have been investigated using whole muscle preparations (twitch contractions), single muscle fibres (excitatory
postsynaptic currents (EPSCs)) and muscle membrane patches containing single quisqualate-sensitive glutamate receptors (qGluR).
Analogues containing an azido group attached to either the butanoyl side-chain of PhTX-343 or as a substitute for the hydroxyl
moiety of the tyrosyl residue were about 6 fold more potent antagonists than PhTX-343; those with an azido group located at
the distal end of the toxin molecule were generally 2–3 fold less potent than PhTX-343. When these compounds were tested in
subdued light, they were reversible antagonists of the muscle twitch, EPSC and qGluR. When a muscle was irradiated with U.V.
during application of photolabile toxin combined with either neural stimulation of the muscle orl-glutamate application, antagonism of the twitch, EPSC and qGluR was complete and irreversible. 相似文献
54.
Mitogen- and isoproterenol-induced changes of [Ca2+]i in T cells attached to a glass substrate were examined. Murine (C57BL/6) splenic T cells were attached to coverslips or 35-mm dishes (MatTek) precoated with Cell Tak® (3.5 µg/cm2). The cells were then loaded with fluorescent dye (2 µg/ml of fura2-AM or fluo3-AM) and changes in [Ca2+]i in a population of cells (using a spectrofluorometer) or in single cells (using a confocal microscope) were measured during continuous superfusion. Population measurements of [Ca2+]i demonstrated that concanavalin A (Con A, 2 or 5 µg/ml) caused an increase in [Ca2+]i that rose to a peak and then declined to a steady state. The concentration-response relationship (0.05–5 µg/ml) had an EC50 of 0.3 µg/ml. Isoproterenol decreased the Con A-induced elevation of steady state [Ca2+]i. In single cell studies, the increase in [Ca2+]i in response to Con A typically occurred in about 50% of the cells in a microscope field, and the delay before activation varied among cells. Taken together, these data demonstrate that Cell Tak® can be used to attach T cells to glass coverslips and will be useful for the study of signaling mechanisms in T cells. 相似文献
55.
A new orphan member of the nuclear hormone receptor superfamily that interacts with a subset of retinoic acid response elements. 总被引:18,自引:5,他引:13
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M Baes T Gulick H S Choi M G Martinoli D Simha D D Moore 《Molecular and cellular biology》1994,14(3):1544-1552
We have identified and characterized a new orphan member of the nuclear hormone receptor superfamily, called MB67, which is predominantly expressed in liver. MB67 binds and transactivates the retinoic acid response elements that control expression of the retinoic acid receptor beta 2 and alcohol dehydrogenase 3 genes, both of which consist of a direct repeat hexamers related to the consensus AGGTCA, separated by 5 bp. MB67 binds these elements as a heterodimer with the 9-cis-retinoic acid receptor, RXR. However, MB67 does not bind or activate other retinoic acid response elements with alternative hexamer arrangements or any of several other wild-type and synthetic hormone response elements examined. The transactivation of retinoic acid response elements by MB67 is weaker than that conferred by the retinoic acid receptors but does not require the presence of all-trans retinoic acid, 9-cis-retinoic acid, or any exogenously added ligand. We propose that MB67 plays an important role in the complex network of proteins that govern response to retinoic acid and its metabolites. 相似文献
56.
Structures of wild-type and mutant signal sequences of Escherichia coli ribose binding protein. 总被引:2,自引:1,他引:1
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The structure of a chemically synthesized 25-residue-long functional signal peptide of Escherichia coli ribose binding protein was compared with that of a nonfunctional mutant-signal peptide using circular dichroism and two-dimensional 1H NMR in solvents mimicking the amphiphilic environments. The functional peptide forms an 18-residue-long alpha-helix starting from the NH2-terminal region and reaching to the hydrophobic stretch in a solvent consisting of 10% dimethylsulfoxide, 40% water, and 50% trifluoroethanol (v/v). The nonfunctional mutant peptide, which contains a Pro at position 9 instead of a Leu in the wild-type peptide, does not have any secondary structure in that solvent but forms a 12-residue-long alpha-helix within the hydrophobic stretch in water/trifluoroethanol (50:50, v/v) solvent. It seems that the Pro-9 residue in the nonfunctional peptide disturbs the helix propagation from the hydrophobic stretch to the NH2-terminal region. Because both of these peptides have stable helices within the hydrophobic stretch, it may be concluded that the additional 2 turns of the alpha-helix in the NH2-terminal region of the wild-type signal peptide is important for its function. 相似文献
57.
Genetic transformation and plant regeneration of watermelon using Agrobacterium tumefaciens 总被引:1,自引:0,他引:1
Adventitious shoots formed on the proximal cut edges of different cotyledonary explants of watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai; cvs. Sweet Gem and Gold Medal] cultured on Murashige and Skoog's (MS) medium with 1 mgl-1 6-benzyladenine (BA). Light (16-h photoperiod, about 7 Wm-2 cool-white fluorescent lamps) was essential for shoot formation. To obtain transformed plants, cotyledonary explants of Sweet Gem were cocultured with Agrobacterium tumefaciens LBA4404, a disarmed strain harboring a binary vector pBI121 carrying the CaMV 35S promoter--glucuronidase (GUS) gene fusion used as a reporter gene and NOS promoter-neomycin phosphotransferase gene as a positive selection marker, for 48 h on MS medium with 1 mgl-1 BA and 200 M -hydroxyacetosyringone. After 48 h of culture, explants were transferred to medium with 1 mgl-1 BA 250 mgl-1 carbenicillin, and 100 mgl-1 kanamycin and cultured in the light. Adventitious shoots formed on the explants after 4 weeks of culture. When subjected to GUS histochemical assay, young leaves obtained from the shoots showed a positive response at a frequency of up to 16%. Preculturing cotyledonary explants on MS medium with 1 mgl-1 BA for 5 d enhanced the competence of the cells to be transformed by Agrobacterium. Southern blot analysis confirmed that the GUS gene was incorporated into the genomic DNA of the GUS-positive regenerants. The transformed plants were grown to maturity. 相似文献
58.
Pressure-volume technique was utilized to evaluate salinity response among three populations ofSpartina patens (Ait.) Muhl. from Louisiana Gulf coast marshes. Plants were subjected to salinities of 85 and 425 mol m?3 for 77 d in a greenhouse. Ψw and Ψπ decreased in all populations in response to increases in salinity. There were 32% decrease in Ψsat, 42% decrease in Ψtlp in response to salinity changes from 85 to 425 mol m?3 in the Ferblanc population. Similarly, there were 35% and 41% decrease in Ψsat in the Clovelly and Lake Tambour populations, respectively. All populations showed the ability to adapt to the increased salinity as was evidenced by osmotic adjustment. However, the Lake Tambour population appeared to have superior ability to adapt to high salinity through having a significantly lower osmotic potential at saturation (Ψsat), osmotic potential at turgor loss point (Ψtlp), and maximum turgor potential (ΨP(max)) compared to other populations. Ferblanc and Clovelly populations revealed the ability to adapt to saline environments to a lesser extent as compared to the Lake Tambour population. Results indicate that there is a potential for selection of superior strains ofSpartina patens for use in marsh restoration projects aiming at prevention of wetland loss in certain coastal areas. 相似文献
59.
Oral liposarcomas are uncommon diseases, the most predominant histopathological subtype being atypical lipomatous tumour/well-differentiated liposarcoma. In regard to its clinical aspects in the oral cavity, it is challenging to confirm a diagnosis and develop a treatment plan. In this case report, we present a rare case of atypical lipomatous tumour/well-differentiated liposarcoma in the right cheek of a 77-year-old male patient. Conservative surgery was performed considering the histopathological subtype of the neoplasm. Knowledge of the clinical and histopathological characteristics of this rare disease is essential to maintaining function and aesthetics through conservative treatment in older patients. 相似文献
60.
Jong An Lee Jung Ho Ahn Gi Bae Kim Sol Choi Ji Yeon Kim Sang Yup Lee 《Biotechnology and bioengineering》2023,120(1):203-215
Microbial production of various TCA intermediates and related chemicals through the reductive TCA cycle has been of great interest. However, rumen bacteria that naturally possess strong reductive TCA cycle have been rarely studied to produce these chemicals, except for succinic acid, due to their dependence on fumarate reduction to transport electrons for ATP synthesis. In this study, malic acid (MA), a dicarboxylic acid of industrial importance, was selected as a target chemical for mass production using Mannheimia succiniciproducens, a rumen bacterium possessing a strong reductive branch of the TCA cycle. The metabolic pathway was reconstructed by eliminating fumarase to prevent MA conversion to fumarate. The respiration system of M. succiniciproducens was reconstructed by introducing the Actinobacillus succinogenes dimethylsulfoxide (DMSO) reductase to improve cell growth using DMSO as an electron acceptor. Also, the cell membrane was engineered by employing Pseudomonas aeruginosa cis-trans isomerase to enhance MA tolerance. High inoculum fed-batch fermentation of the final engineered strain produced 61 g/L of MA with an overall productivity of 2.27 g/L/h, which is the highest MA productivity reported to date. The systems metabolic engineering strategies reported in this study will be useful for developing anaerobic bioprocesses for the production of various industrially important chemicals. 相似文献