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排序方式: 共有194条查询结果,搜索用时 156 毫秒
21.
Daisuke Sekine Ikuko Munemura Mei Gao Wataru Mitsuhashi Tomonobu Toyomasu Hideki Murayama 《Physiologia plantarum》2006,126(2):163-174
'La France' pear ( Pyrus communis L.) fruit stored at 1°C for 1 month (short-term storage) before transfer to 20°C softened and developed a melting texture during ripening, whereas fruit stored for 5 months (long-term storage) before transfer to 20°C softened but did not develop a melting texture. To clarify the mechanisms involved in fruit softening and textural changes, the cDNAs encoding cell-wall hydrolases were isolated by RT-PCR, and their expression and localization were investigated in 'La France' pears. Genes encoding three polygalacturonases (PG; EC 3.2.1.15), four pectin methylesterases (PME; EC 3.1.1.11), one α -arabinofuranosidase (ARF; EC 3.2.1.55), three β -galactosidases (GAL; EC 3.2.1.23), and two endo-1,4- β - d -glucanases (Cel; EC 3.2.1.4) were isolated. Among these 13 isolated genes, PcPG1 was the only gene for which the mRNA expression levels increased in both the short- and long-term stored fruits. This suggested that PcPG1 is involved in fruit softening rather than in the development of the melting texture. In contrast, the expression levels of PcPG3 , PcPME1 , PcPME2 , PcPME3 , PcGAL1 , PcGAL2 , and PcCel2 increased during ripening only in the short-term stored fruit. These genes might thus be involved in the development of the melting texture. 相似文献
22.
Sagor GH Takahashi H Niitsu M Takahashi Y Berberich T Kusano T 《Plant cell reports》2012,31(7):1227-1232
We previously proposed the defensive role of a signal pathway triggered by the polyamine spermine (Spm) in the reaction against avirulent viral pathogens in Nicotiana tabacum and Arabidopsis thaliana. In this study, we showed that thermospermine (T-Spm), an isomer of Spm, is also active in inducing the expression of the genes involved in the Spm-signal pathway at a similar dose as Spm. Furthermore, we found that T-Spm enhances the expression of a subset of pathogenesis-related genes whose expression is induced during cucumber mosaic virus (CMV)-triggered hypersensitive response. In consistent with the above observation, we further showed that exogenous T-Spm can repress CMV multiplication with same efficiency as Spm. KEY MESSAGE: Polyamine thermospermine, an isomer of spermine, is able to induce a subset of hypersensitive response-related defense genes and can suppress cucumber mosaic virus multiplication in Arabidopsis thaliana. 相似文献
23.
T Yaguchi Y Goto K Kido H Mochimaru T Sakurai N Tsukamoto C Kudo-Saito T Fujita H Sumimoto Y Kawakami 《Journal of immunology (Baltimore, Md. : 1950)》2012,189(5):2110-2117
Cancer-induced immunosuppression is a major problem reducing antitumor effects of immunotherapies, but its molecular mechanism has not been well understood. We evaluated immunosuppressive roles of activated Wnt/β-catenin pathways in human melanoma for dendritic cells (DCs) and CTLs. IL-10 expression was associated with β-catenin accumulation in human melanoma cell lines and tissues and was induced by direct β-catenin/TCF binding to the IL-10 promoter. Culture supernatants from β-catenin-accumulated melanoma have activities to impair DC maturation and to induce possible regulatory DCs. Those immunosuppressive culture supernatant activities were reduced by knocking down β-catenin in melanoma cells, partly owing to downregulation of IL-10. Murine splenic and tumor-infiltrating DCs obtained from nude mice implanted with human mutant β-catenin-overexpressed melanoma cells had less ability to activate T cells than did DCs from mice with control melanoma cells, showing in vivo suppression of DCs by activated Wnt/β-catenin signaling in human melanoma. This in vivo DC suppression was restored by the administration of a β-catenin inhibitor, PKF115-584. β-catenin-overexpressed melanoma inhibited IFN-γ production by melanoma-specific CTLs in an IL-10-independent manner and is more resistant to CTL lysis in vitro and in vivo. These results indicate that Wnt/β-catenin pathways in human melanoma may be involved in immunosuppression and immunoresistance in both induction and effector phases of antitumor immunoresponses partly through IL-10 production, and they may be attractive targets for restoring immunocompetence in patients with Wnt/β-catenin-activated melanoma. 相似文献
24.
25.
Mitsuteru Suzuki Pramod Tandon Masaya Ishikawa Takayuki Toyomasu 《Plant biotechnology reports》2008,2(2):123-131
Vitrification methods are convenient for cryopreserving plant specimens, as the specimens are plunged directly into liquid
nitrogen (LN) from ambient temperatures. However, tissues and species with poor survival are still not uncommon. The development
of vitrification solutions with high survival that cover a range of materials is important. We attempted to develop new vitrification
solutions using bromegrass cells and found that VSL, comprising 20% (w/v) glycerol, 30% (w/v) ethylene glycol, 5% (w/v) sucrose,
10% (w/v) DMSO and 10 mM CaCl2, gave the highest survival following cryopreservation, as determined by fluorescein diacetate staining. However, the cryopreserved
cells showed little regrowth, for unknown reasons. To check its applicability, VSL was used to cryopreserve gentian axillary
buds and the performance was compared with those of conventional vitrification solutions. Excised gentian stem segments with
axillary buds (shoot apices) were two-step precultured with sucrose to induce osmotic tolerance prior to cryopreservation.
Gentian axillary buds cryopreserved using VSL following the appropriate preculturing approach exhibited 78% survival (determined
by the regrowth capacity), which was comparable to PVS2 and PVS1 and far better than PVS3. VSL had a wider optimal incubation
time (20–45 min) than PVS2 and was more suitable for cryopreserving gentian buds. The optimal duration of the first step of
the preculture was 7–11 days, and preculturing with sucrose and glucose gave a much higher survival than fructose and maltose.
VSL was able to vitrify during cooling to LN temperatures, as glass transition and devitrification points were detected in
the warming profiles from differential scanning calorimetry. VSL and its derivative, VSL+, seem to have the potential to be
good alternatives to PVS2 for the cryopreservation of some materials, as exemplified by gentian buds.
Mitsuteru Suzuki, Pramod Tandon and Masaya Ishikawa contributed equally to the work. 相似文献
26.
Human myosin Vc is a low duty ratio nonprocessive motor 总被引:1,自引:0,他引:1
Watanabe S Watanabe TM Sato O Awata J Homma K Umeki N Higuchi H Ikebe R Ikebe M 《The Journal of biological chemistry》2008,283(16):10581-10592
There are three distinct members of the myosin V family in vertebrates, and each isoform is involved in different membrane trafficking pathways. Both myosin Va and Vb have demonstrated that they are high duty ratio motors that are consistent with the processive nature of these motors. Here we report that the ATPase cycle mechanism of the single-headed construct of myosin Vc is quite different from those of other vertebrate myosin V isoforms. K(ATPase) of the actin-activated ATPase was 62 microm, which is much higher than that of myosin Va ( approximately 1 mum). The rate of ADP release from actomyosin Vc was 12.7 s(-1), which was 2 times greater than the entire ATPase cycle rate, 6.5 s(-1). P(i) burst size was 0.31, indicating that the equilibrium of the ATP hydrolysis step is shifted to the prehydrolysis form. Our kinetic model, based on all kinetic data we determined in this study, suggests that myosin Vc spends the majority of the ATPase cycle time in the weak actin binding state in contrast to myosin Va and Vb. Consistently, the two-headed myosin Vc construct did not show processive movement in total internal reflection fluorescence microscope analysis, demonstrating that myosin Vc is a nonprocessive motor. Our findings suggest that myosin Vc fulfills its function as a cargo transporter by different mechanisms from other myosin V isoforms. 相似文献
27.
Toyomasu T Kagahara T Okada K Koga J Hasegawa M Mitsuhashi W Sassa T Yamane H 《Bioscience, biotechnology, and biochemistry》2008,72(2):562-567
Rice (Oryza sativa L.) produces a variety of diterpene phytoalexins, such as momilactones, phytocassanes, and oryzalexins. Momilactone B was previously identified as an allelopathic substance exuded from the roots of rice. We identified in this present study momilactone A and phytocassanes A-E in extracts of, and exudates from, the roots of rice seedlings. The concentration of each compound was of the same order of magnitude as that of momilactone B. Expression analyses of the diterpene cyclase genes responsible for the biosynthesis of momilactones and phytocassanes suggest that these phytoalexins found in roots are primarily biosynthesized in those roots. None of phytocassanes B-E exhibited allelopathic activity against dicot seedling growth, whereas momilactone A showed much weaker allelopathic activity than momilactone B. The exudation of diterpene phytoalexins from the roots might be part of a system for defense against root-infecting pathogens. 相似文献
28.
H Toshima H Oikawa T Toyomasu T Sassa 《Bioscience, biotechnology, and biochemistry》2001,65(5):1244-1247
The drimane sesquiterpenes, (+)-albicanol (2) and (+)-albicanyl acetate (3), were synthesized from an optically active bicyclic diol [(+)-1] that had been obtained via the recently developed optical resolution of a general synthetic intermediate for drimane sesquiterpenes. The crucial step in the previous syntheses was markedly improved by the modified Wittig methylenation of a silyloxy ketone (7). The high overall yield (77% in 4 or 5 steps from (+)-1) by this total synthesis makes it possible to synthesize the other biologically active drimane sesquiterpenes. 相似文献
29.
Zen-ichiro Hamauzu Tetsuo Toyomasu Daizo Yonezawa 《Bioscience, biotechnology, and biochemistry》2013,77(12):2445-2450
Gliadin was fractionated into three fractions; ω-gliadin, Fraction III (γ-gliadin) and Fraction IV (α- and β-gliadin). The determination of the molecular weights (MW) of the three fractions was performed by both SDS-polyacrylamide gel electrophoresis (SDS–PAGE) and sedimentation equilibrium. In SDS–PAGE, ω-gliadin gave three bands (MW 50,000, 54,000 and 64,000), Fraction III two bands (MW 38,000 and 46,000) and Fraction IV two bands (MW 33,000 and 38,000), The sedimentation analysis showed that each fraction was fairly homogeneous relative to molecular weight. The molecular weights obtained by sedimentation were 28,000 for Fraction III and 27,000 for both Fraction IV and ω-gliadin. The disagreement in molecular weight between sedimentation and gel electrophoresis was discussed. 相似文献
30.
G. H. M. Sagor Thomas Berberich Seiji Kojima Masaru Niitsu Tomonobu Kusano 《Plant cell reports》2016,35(6):1247-1257