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排序方式: 共有120条查询结果,搜索用时 31 毫秒
31.
Vereecke D Burssens S Simón-Mateo C Inzé D Van Montagu M Goethals K Jaziri M 《Planta》2000,210(2):241-251
Rhodococcus fascians is a Gram-positive bacterium that infects dicotyledonous and monocotyledonous plants, leading to an alteration in the normal
growth process of the host. The disease results from the modulation of the plant hormone balances, and cytokinins are thought
to play an important role in the induction of symptoms. Generally, on the aerial parts of the plants, existing meristems were
found to be most sensitive to the action of R. fascians, but, depending on the infection procedure, differentiated tissues as well gave rise to shoots. Similarly, in roots not only
actively dividing cells, but also cells with a high competence to divide were strongly affected by R. fascians. The observed symptoms, together with the determined hormone levels in infected plant tissue, suggest that auxins and molecules
of bacterial origin are also involved in leafy gall formation. The complexity of symptom development is furthermore illustrated
by the necessary and continuous presence of the bacteria for symptom persistence. Indeed, elimination of the bacteria from
a leafy gall results in the further development of the multiple embryonic buds of which it consists. This interesting characteristic
offers novel biotechnological applications: a leafy gall can be used for germplasm storage and for plant propagation. The
presented procedure proves to be routinely applicable to a very wide range of plants, encompassing several recalcitrant species.
Received: 14 January 1999 / Accepted: 19 June 1999 相似文献
32.
Characterization of ripening-regulated cDNAs and their expression in ethylene-suppressed charentais melon fruit
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Charentais melons (Cucumis melo cv Reticulatus) are climacteric and undergo extremely rapid ripening. Sixteen cDNAs corresponding to mRNAs whose abundance is ripening regulated were isolated to characterize the changes in gene expression that accompany this very rapid ripening process. Sequence comparisons indicated that eight of these cDNA clones encoded proteins that have been previously characterized, with one corresponding to ACC (1-aminocyclopropane-1-carboxylic acid) oxidase, three to proteins associated with pathogen responses, two to proteins involved in sulfur amino acid biosynthesis, and two having significant homology to a seed storage protein or a yeast secretory protein. The remaining eight cDNA sequences did not reveal significant sequence similarities to previously characterized proteins. The majority of the 16 ripening-regulated cDNAs corresponded to mRNAs that were fruit specific, although three were expressed at low levels in vegetative tissues. When examined in transgenic antisense ACC oxidase melon fruit, three distinct patterns of mRNA accumulation were observed. One group of cDNAs corresponded to mRNAs whose abundance was reduced in transgenic fruit but inducible by ethylene treatment, indicating that these genes are directly regulated by ethylene. A second group of mRNAs was not significantly altered in the transgenic fruit and was unaffected by treatment with ethylene, indicating that these genes are regulated by ethylene-independent developmental cues. The third and largest group of cDNAs showed an unexpected pattern of expression, with levels of mRNA reduced in transgenic fruit and remaining low after exposure to ethylene. Regulation of this third group of genes thus appears to ethylene independent, but may be regulated by developmental cues that require ethylene at a certain stage in fruit development. The results confirm that both ethylene-dependent and ethylene-independent pathways of gene regulation coexist in climacteric fruit. 相似文献
33.
34.
Mondher Boulaaba Soninkhishig Tsolmon Riadh Ksouri Junkyu Han Kiyokazu Kawada Abderrazak Smaoui Chedly Abdelly Hiroko Isoda 《Cytotechnology》2013,65(6):927-936
Taking into account that oxidative stress is among the factors causing cancer-related death; chemoprevention which consists in using antioxidant substances such as phenolics could prevent cancer formation and progression. In the present study, phenolic contents and antioxidant activities of methanolic extracts from the halophyte Tamarix gallica shoots were determined. Moreover, the anticancer effect of this species on human colon cancer cells and the likely underlying mechanisms were also investigated. Shoot extracts showed an appreciable total phenolic content (85 mg GAE/g DW) and a high antioxidant activity (IC50 = 3.3 μg/ml for DPPH test). At 50 and 100 μg/ml, shoot, leaf, and flower extracts significantly inhibited Caco-2 cell growth. For instance, almost all plant part extracts inhibited cell growth by 62 % at the concentration 100 μg/ml. DAPI staining results revealed that these extracts decrease DNA synthesis and confirm their effect on Caco-2 cells proliferation, principally at 100 μg/ml. More importantly, cell mitosis was arrested at G2/M phase. The changes in the cell-cycle-associated proteins (cyclin B1, p38, Erk1/2, Chk1, and Chk2) are correlated with the changes in cell cycle distribution. Taken together, our data suggest that T. gallica is a promising candidate species to be used as a source of anticancer biomolecules. 相似文献
35.
36.
Sana M’hir Jean-Marc Aldric Thami El-Mejdoub Jaqueline Destain Mondher Mejri Moktar Hamdi Phillippe Thonart 《World journal of microbiology & biotechnology》2008,24(12):2775-2781
The aim of this work was to select strains with proteolytic activity on wheat gliadin, among lactic acid bacteria, previously
isolated from Tunisian fermented wheat dough. Hydrolysis of gliadin, as sole nitrogen source, in an agar medium was visualized
by a clear zone surrounding colonies. The increase in absorbance due to gliadin breakdown was measured spectrophotometrically
using O-phthaldialdehyde (OPA) on Gliadin Glucose Broth medium. Fermented liquid dough inoculated with individual selected Enterococcus faecalis, showed a decrease of the gliadin concentration from 45 g/kg to 18 g/kg determined by sandwich ELISA test (R-7001). Only
the enterococci strains show an hydrolysis of gliadin proteins. Strains showing proteolytic activity are gaining more and
more importance in cereal based fermented foods and may help to reduce gliadin involved in coeliac disease. 相似文献
37.
Falleh H Ksouri R Chaieb K Karray-Bouraoui N Trabelsi N Boulaaba M Abdelly C 《Comptes rendus biologies》2008,331(5):372-379
Polyphenols are bioactive molecules exhibiting a lot of scientific attention due to their multiple biological activities. This study compared phenolic contents and antioxidant activity in Cynara cardunculus L. organs and focus on leaf phenolic compounds identification by RP-HPLC and their antibacterial activity. The analyzed organs exhibited different total polyphenol contents (7-14.8 mg GAE g(-1) DW). Leaf and seed phenolic contents were similar and two times higher than those in flowers. The same tendency was observed for the amount of flavonoids and tannins. However, seed extracts displayed the highest DPPH. scavenging ability with the lowest IC50 value (23 microg ml(-1)), followed by leaves and flowers (over 50 microg ml(-1)). In contrast, leaves showed the highest capacity to quench superoxide (IC50: 1 microg ml(-1)) as compared to seeds (6 microg ml(-1)). In addition, cardoon leaves were efficient to inhibit growth of pathogenic bacteria mainly against Staphylococcus aureus and Escherichia coli. The identification of phenolic compounds from leaves revealed that syringic and trans-cinnamic acids were the major molecules. 相似文献
38.
Exogenous ethylene stimulates the long-term expression of genes related to anthocyanin biosynthesis in grape berries 总被引:8,自引:0,他引:8
39.
Characterization of an endophytic whorl-forming Streptomyces from Catharanthus roseus stems producing polyene macrolide antibiotic 总被引:1,自引:0,他引:1
Rakotoniriana EF Chataigné G Raoelison G Rabemanantsoa C Munaut F El Jaziri M Urveg-Ratsimamanga S Marchand-Brynaert J Corbisier AM Declerck S Quetin-Leclercq J 《Canadian journal of microbiology》2012,58(5):617-627
An endophytic whorl-forming Streptomyces sp. designated as TS3RO having antifungal activity against a large number of fungal pathogens, including Sclerotinia sclerotiorum, Rhizoctonia solani, Colletotrichum gloeosporioides, Cryphonectria parasitica, Fusarium oxysporum, Pyrenophora tritici-repentis, Epidermophyton floccosum, and Trichophyton rubrum, was isolated from surface-sterilized Catharanthus roseus stems. Preliminary identification showed that Streptomyces cinnamoneus subsp. sparsus was its closest related species. However, strain TS3RO could readily be distinguished from this species using a combination of phenotypic properties, 16S rDNA sequence similarity, and phylogenetic analyses. Thus, the whorl-forming Streptomyces sp. strain TS3RO is likely a new subspecies within the Streptomyces cinnamoneus group. Direct bioautography on a thin-layer chromatography plate with Cladosporium cucumerinum was conducted throughout the purification steps for bioassay-guided isolation of the active antifungal compounds from the crude extract. Structural elucidation of the isolated bioactive compound was obtained via LC-MS spectrometry, UV-visible spectra, and nuclear magnetic resonance data. It revealed that fungichromin, a known methylpentaene macrolide antibiotic, was the main antifungal component of TS3RO strain, as shown by thin-layer chromatography bioautography. This is the first report of an endophytic whorl-forming Streptomyces isolated from the medically important plant Catharanthus roseus. 相似文献
40.
Taxus sp. cell, tissue and organ cultures as alternative sources for taxoids production: a literature survey 总被引:12,自引:0,他引:12
Mondher Jaziri Abdesslam Zhiri Yan-Wen Guo Jean-Pierre Dupont Koichiro Shimomura Hiroki Hamada Maurice Vanhaelen Jacques Homès 《Plant Cell, Tissue and Organ Culture》1996,46(1):59-75
The literature concerning the tissue culture of Taxus sp. as an alternative source for taxoid production is reviewed. The aim of this review is to summarize and discuss the progress achieved with the approaches and methods used for the establishment of various Taxus culture systems, the methods used for the evaluation of taxoid production, the multiple factors which control taxoid production and the feasibility of the in vitro production of taxoids on a commercial scale. 相似文献