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951.
Ping-Lung Huang Li-Jen Liao Chi-Chu Tsai Zin-Huang Liu 《Plant Cell, Tissue and Organ Culture》2011,105(1):73-78
Although suckers and seedlings can be used for the propagation of bromeliads, the low number of propagules and cross-variation
limit their uniformity and mass cultivation. In this study, high-efficiency shoot organogenesis and plant regeneration were
achieved on callus derived from petal and ovary explants of Aechmea fasciata (Bromeliaceae). Calluses were induced on half-strength Murashige and Skoog inorganic salts (1/2MS) supplemented with 1.0–1.5 mg
l−1 2,4-dichlorophenoxyacetic acid in combination with 1.0 or 0.5 mg l−1 α-naphthaleneacetic acid (NAA), and shoots regenerated after transfer to 1/2MS basal medium containing the combination of
1.0 mg l−1 NAA + 0.5 mg l−1 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea. Those plantlets grown under a middle light intensity (50 μmol m−2 s−1) showed a dramatic increase in survival percentage (up to 95%) and the maximum number of newly developing roots. The plantlets
that were transplanted onto pots were successfully grown in the greenhouse. 相似文献
952.
953.
Velho RV Caldas DG Medina LF Tsai SM Brandelli A 《Letters in applied microbiology》2011,52(6):660-666
Aims: To investigate the expression of sboA and ituD genes among strains of Bacillus spp. at different pH and temperature. Methods and Results: Different Bacillus strains from the Amazon basin and Bacillus subtilis ATCC 19659 were investigated for the production of subtilosin A and iturin A by qRT‐PCR, analysing sboA and ituD gene expression under different culture conditions. Amazonian strains presented a general gene expression level lower than B. subtilis ATCC 19659 for sboA. In contrast, when analysing the expression of ituD gene, the strains from the Amazon, particularly P40 and P45B, exhibited higher levels of expression. Changes in pH (6 and 8) and temperature (37 and 42°C) caused a decrease in sboA expression, but increased ituD expression among strains from Amazonian environment. Conclusions: Temperature and pH have an important influence on the expression of genes sboA (subtilosin A) and ituD (iturin A) among Bacillus spp. The strains P40 and P45B can be useful for the production of antimicrobial peptide iturin A. Significance and Impact of the Study: Monitoring the expression of essential biosynthetic genes by qRT‐PCR is a valuable tool for optimization of the production of antimicrobial peptides. 相似文献
954.
Wearable hip protectors (padded garments) represent a promising strategy to decrease impact force and hip fracture risk during falls, and a wide range of products are currently marketed. However, little is known about how design features of hip protectors influence biomechanical effectiveness. We used a mechanical test system (simulating sideways falls) to measure the attenuation in femoral neck force provided by 26 commercially available hip protectors at three impact velocities (2, 3, and 4m/s). We also used a materials testing machine to characterize the force-deflection properties of each device. Regression analyses were performed to determine which geometric (e.g., height, width, thickness, volume) and force-deflection properties were associated with force attenuation. At an impact velocity of 3m/s, the force attenuation provided by the various hip protectors ranged between 2.5% and 40%. Hip protectors with lower stiffness (measured at 500N) provided greater force attenuation at all velocities. Protectors that absorbed more energy demonstrated greater force attenuation at the higher impact velocities (3 and 4m/s conditions), while protectors that did not directly contact (but instead bridged) the skin overlying the greater trochanter attenuated more force at velocities of 2 and 3m/s. At these lower velocities, the force attenuation provided by protectors that contacted the skin overlying the greater trochanter increased with increasing pad width, thickness, and energy dissipation. By providing a comparison of the protective value of a large range of existing hip protectors, these results can help to guide consumers and researchers in selecting hip protectors, and in interpreting the results of previous clinical trials. Furthermore, by determining geometric and material parameters that influence biomechanical performance, our results should assist manufacturers in designing devices that offer improved performance and clinical effectiveness. 相似文献
955.
Li CY Chao LK Wang SC Chang HZ Tsai ML Fang SH Liao PC Ho CL Chen ST Cheng WC Chiang CS Kuo YH Hua KF Hsu IC 《Journal of cellular physiology》2011,226(9):2338-2349
Honokiol (HNK) is a phenolic compound isolated from the bark of houpu (Magnolia officinalis), a plant widely used in traditional Chinese and Japanese medicine. While substantial evidence indicates that HNK possesses anti-inflammatory activity, its effect on dendritic cells (DCs) during the inflammatory reaction remains unclear. The present study investigates how HNK affects lipopolysaccharide (LPS)-stimulated human monocyte-derived DCs. Our experimental results show that HNK inhibits the inflammatory response of LPS-induced DCs by (1) suppressing the expression of CD11c, CD40, CD80, CD83, CD86, and MHC-II on LPS-activated DCs, (2) reducing the production of TNF-α, IL-1β, IL-6, and IL-12p70 but increasing the production of IL-10 and TGF-β1 by LPS-activated DCs, (3) inhibiting the LPS-induced DC-elicited allogeneic T-cell proliferation, and (4) shifting the LPS-induced DC-driven Th1 response toward a Th2 response. Further, our results show that HNK inhibits the phosphorylation levels of ERK1/2, p38, JNK1/2, IKKα, and IκBα in LPS-activated DCs. Collectively, the findings show that the anti-inflammatory actions of HNK on LPS-induced DCs are associated with the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways. 相似文献
956.
Icilin is recognized as a chemical agonist of nociceptors and can activate TRPM8 channels. However, whether this agent has
any effects on immune cells remains unknown. In this study, the effects of icilin on ion currents were investigated in RAW
264.7 murine macrophage-like cells. Icilin (1–100 μM) increased the amplitude of nonselective (NS) cation current (I
NS) in a concentration-dependent manner with an EC50 value of 8.6 μM. LaCl3 (100 μM) or capsazepine (30 μM) reversed icilin-induced I
NS; however, neither apamin (200 nM) nor iberiotoxin (200 nM) had any effects on it. In cell-attached configuration, when the
electrode was filled with icilin (30 μM), a unique population of NS cation channels were activated with single-channel conductance
of 158 pS. With the use of a long-lasting ramp pulse protocol, increasing icilin concentration produced a left shift in the
activation curve of NS channels, with no change in the slope factor of the curve. The probability of channel opening enhanced
by icilin was increased by either elevated extracellular Ca2+ or application of ionomycin (10 μM), while it was reduced by BAPTA-AM (10 μM). Icilin-stimulated activity is associated with
an increase in mean open time and a reduction in mean closed time. Under current-clamp conditions, icilin caused membrane
depolarization. Therefore, icilin interacts with the TRPM8-like channel to increase I
NS and depolarizes the membrane in these cells. 相似文献
957.
Rad51 and Rad54 play crucial roles during homologous recombination. The biochemical activities of human Rad51 (hRad51) and human Rad54 (hRad54) and their interactions with each other are well documented. However, it is not known how these two proteins work together to bypass heterologous sequences; i.e. mismatched base pairs, during homologous recombination. In this study, we used a fluorescence resonance energy transfer assay to monitor homologous recombination processes in real time so that the interactions between hRad54 and hRad51 during DNA strand exchange and branch migration, which are two core steps of homologous recombination, could be characterized. Our results indicate that hRad54 can facilitate hRad51-promoted strand exchange through various degrees of mismatching. We propose that the main roles of hRad51 in homologous recombination is to initiate the homology recognition and strand-exchange steps and those of hRad54 are to promote efficient branch migration, bypass potential mismatches and facilitate long-range strand exchanges through branch migration of Holliday junctions. 相似文献
958.
Della-Maria J Zhou Y Tsai MS Kuhnlein J Carney JP Paull TT Tomkinson AE 《The Journal of biological chemistry》2011,286(39):33845-33853
Recent studies have implicated a poorly defined alternative pathway of nonhomologous end joining (alt-NHEJ) in the generation of large deletions and chromosomal translocations that are frequently observed in cancer cells. Here, we describe an interaction between two factors, hMre11/hRad50/Nbs1 (MRN) and DNA ligase IIIα/XRCC1, that have been linked with alt-NHEJ. Expression of DNA ligase IIIα and the association between MRN and DNA ligase IIIα/XRCC1 are altered in cell lines defective in the major NHEJ pathway. Most notably, DNA damage induced the association of these factors in DNA ligase IV-deficient cells. MRN interacts with DNA ligase IIIα/XRCC1, stimulating intermolecular ligation, and together these proteins join incompatible DNA ends in a reaction that mimics alt-NHEJ. Thus, our results provide novel mechanistic insights into the alt-NHEJ pathway that not only contributes to genome instability in cancer cells but may also be a therapeutic target. 相似文献
959.
Lin RK Zhou N Lyu YL Tsai YC Lu CH Kerrigan J Chen YT Guan Z Hsieh TS Liu LF 《The Journal of biological chemistry》2011,286(38):33591-33600
Studies in animal models have indicated that dietary isothiocyanates (ITCs) exhibit cancer preventive activities through carcinogen detoxification-dependent and -independent mechanisms. The carcinogen detoxification-independent mechanism of cancer prevention by ITCs has been attributed at least in part to their ability to induce apoptosis of transformed (initiated) cells (e.g. through suppression of IκB kinase and nuclear factor κB as well as other proposed mechanisms). In the current studies we show that ITC-induced apoptosis of oncogene-transformed cells involves thiol modification of DNA topoisomerase II (Top2) based on the following observations. 1) siRNA-mediated knockdown of Top2α in both SV40-transformed MEFs and Ras-transformed human mammary epithelial MCF-10A cells resulted in reduced ITC sensitivity. 2) ITCs, like some anticancer drugs and cancer-preventive dietary components, were shown to induce reversible Top2α cleavage complexes in vitro. 3) ITC-induced Top2α cleavage complexes were abolished by co-incubation with excess glutathione. In addition, proteomic analysis revealed that several cysteine residues on human Top2α were covalently modified by benzyl-ITC, suggesting that ITC-induced Top2α cleavage complexes may involve cysteine modification. Interestingly, consistent with the thiol modification mechanism for Top2α cleavage complex induction, the thiol-reactive selenocysteine, but not the non-thiol-reactive selenomethionine, was shown to induce Top2α cleavage complexes. In the aggregate, our results suggest that thiol modification of Top2α may contribute to apoptosis induction in transformed cells by ITCs. 相似文献
960.
Yang FL Yang YL Liao PC Chou JC Tsai KC Yang AS Sheu F Lin TL Hsieh PF Wang JT Hua KF Wu SH 《The Journal of biological chemistry》2011,286(24):21041-21051
The active components of a primary pyrogenic liver abscess (PLA) Klebsiella pneumoniae in stimulating cytokine expression in macrophages are still unclear. The capsular polysaccharide (CPS) of PLA K. pneumoniae is important in determining clinical manifestations, and we have shown that it consists of repeating units of the trisaccharide (→3)-β-D-Glc-(1→4)-[2,3-(S)-pyruvate]-β-D-GlcA-(1→4)-α-L-Fuc-(1→) and has the unusual feature of extensive pyruvation of glucuronic acid and acetylation of C(2)-OH or C(3)-OH of fucose. We demonstrated that PLA K. pneumoniae CPS induces secretion of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) by macrophages through Toll-like receptor 4 (TLR4) and that this effect was lost when pyruvation and O-acetylation were chemically destroyed. Furthermore, expression of TNF-α and IL-6 in PLA K. pneumoniae CPS-stimulated macrophages was shown to be regulated by the TLR4/ROS/PKC-δ/NF-κB, TLR4/PI3-kinase/AKT/NF-κB, and TLR4/MAPK signaling pathways. 相似文献