Programmed Cell Death During Secondary Xylem Differentiation in Eucommia ulmoides

Programmed cell death (PCD) during secondary xylem differentiation in Eucommia ulmoides Oliv. was examined using electron microscopy and by investigation of DNA fragmentation and degradation of caspase-like proteases (CLPs). DNA ladders were detected in developing secondary xylem by gel electrophoresis. DNA fragmentation was further confirmed by using the TdT-mediated dUTP nick-end labeling (TUNEL) method. Western blotting analysis showed that CLPs (caspase-8- and caspase-3-like proteases) and PARP (poly (ADP-ribose) polymerase) were degraded during secondary xylem differentiation. The results thus indicated that secondary xylem differentiation in E ulmoides was a typical process of PCD and the degradation of CLPs might be a constitutive PCD event during secondary xylem differentiation.

月见草的生药学研究

本文对月见草的药用部分——种子,作了外形和细胞组织的生药学观察。附形态、组织简、详图四幅。

Chemical Constituents of the Suspension Cell Cultures of Maytenus hookeri

Suspension cell cultures of Maytenus hookeri Loos. (Celastraceae) in SH media were established from the calli induced from the leaves and young steins of M. hookeri on MS media with the supplement of 2 mg/L 2,4-D and 0.1 mg/L KIN (kinetin). Ethyl acetate extract of the cultures showed inhibitory activities against Penicillium avellaneum UC-4376 which was sensitive to maytansinoids. Exhaustive isolation of natural products from a large scale of suspension cell cultures did not yield maytansine instead of affording nine compounds including one novel triterpenoid, named 2, 3-diacetoxyl maytenusone (1), and eight known ones including squalene (2), beta-sitosterol (3), 2', 3', 4-triacetyl-sitoindoside I (4), salaspermic acid (5), maytenonic acid (6), 2alpha-hydroxy-maytenonic acid (7), 6, 11,12-trihydroxy-8, 11, 13-abietrien-7-one (8) and 11, 12-dihydroxy-8, 11, 13-abietatrien-7-one (9) elucidated on the basis of 1D and 2D NMR data. The H-1-NMR and C-13-NMR assignments were made for 1, 5, 6 and 7, while the C-13-NMR assignments for 5 and 6 were revised. The chemical results suggested that the suspension cell cultures of M. hookeri did not produce maytansinoids under the reported experiment conditions.

Genistein sensitizes ovarian carcinoma cells to chemotherapy by switching the cell cycle progression in vitro

Objective:To address how genistein sensitizes the chemotherapy-resistant ovarian carcinoma cells and promotes apoptosis in the respect of cell cycle and the regulation of survivin expression in the process.Methods:Ovarian SKOV-3 carcinoma cell line was treated with genistein or cisplatin either alone or in combination.Cell viability was showed by MTT method.Cell cycle and apoptosis were detected by flow cytometry.Survivin mRNA and protein were revealed by RT-PCR and immunocytochemistry,respectively.Results:Genistein could reduce the cell viability in a dose-dependent manner,while cisplatin did so at a much higher level.In contrast,if the two agents were treated in combination,half growth inhibition(IC50) value for cisplatin was reduced remarkably and the effect was synergistic as analyzed by isobologram.In particular,the reduced cell viability was exhibited by a switch in cell cycle progression,as the cells were arrested in G2/M phase and the G0/G1 phase-fraction was significantly decreased.The reduced cell viability appeared to involve apoptosis,based on our results from flow cytometry and Hoechst 33258 staining.In the meanwhile,genistein performed the inhibitory effect on cisplatin-induced survivin expression.Conclusion:Genistein can sensitize ovarian carcinoma cells to cisplatin therapy with the inhibition of survivin expression as the potential mechanism.

Genetic improvement of Trichoderma ability to induce systemic resistance

The beneficial applications of Trichoderma spp. in agriculture include not only the control of plant pathogens, but also the improvement of plant growth, micronutrient availability, and plant tolerance to abiotic stress. In addition, it has been suggested that these fungi are able to increase plant disease resistance by activating induced systemic resistance (ISR) . The mode of action of these beneficial fungi in the Trichoderma -plant-pathogen interaction are many, complex and not completely understood. Numerous lytic enzymes have been characterized, the encoding genes (ech42 gluc78, nag1 from T. atroviride strain P1) cloned, and their role in biocontrol demonstrated. The corresponding biocontrol-related inducible promoters have been used in a reporter system based on the Aspergillus niger glucose oxidase gene (goxA) to monitor biocontrol activity. Glucose oxidase catalyzes the oxygen-dependent oxidation of D-glucose to D-glucono-1,5-lactone and hydrogen peroxide; this latter compound is known to have an antifungal effect and activate the plant defence cascade, thus increasing resistance to pathogen attack. T. atroviride P1 transformants with various promoters gox were tested as seed coating treatments on bean seeds planted in soil infested with a soilborne fungal pathogen. Successively, the emergent leaves were inoculated with a foliar pathogen to determine the effect of the GOX transformants on biocontrol and resistance to pathogen attack. Inoculations with the P1-GOX transformants not only reduced disease symptoms caused by a soil pathogen, but also the lesions of various foliar pathogens applied far from the Trichoderma colonization, thus activating ISR. A similar approach is being use to genetically improve T. harzianum T22, a rhizosphere competent and commercially marketed strain not transformed yet, by using four different gox gene constructs under the control of constitutive and inducible promoters. Plasmids have been introduced in Trichoderma by protoplasts co-transformation. hygromicin resistant progeny selected, and mitotically stable transformants analysed to confirm the presence of the novel enzyme activity. Progenies are being tested for biocontrol ISR inducing activity.