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21.
Numazawa M Ando M Zennyoji R 《The Journal of steroid biochemistry and molecular biology》2002,82(1):65-73
To gain insight into the catalytic function of aromatase, we studied aromatization of a series of 6alpha- and 6beta-ether-substituted (methoxy, ethoxy, and n-butoxy) androst-4-ene-3,17-dione (AD) steroids (1 and 2) and their androsta-1,4-diene-3,17-dione (ADD) derivatives (3 and 4) with human placental aromatase by gas chromatography-mass spectrometry (GC-MS). Among the steroids examined, 6beta-methoxy and 6beta-ethoxyADDs (4a and 4b) are suicide substrates of aromatase. All of the steroids were found to be converted into the corresponding 6-alkoxy estrogens. Introduction of the alkoxy groups at C-6 of AD or ADD decreased the ability of these to serve as a substrate of aromatase. In 6alpha-alkoxy steroid series, compounds 1 and 3, the aromatization rate increased by elongating the 6-methoxy group up to the n-butoxy group whereas, in the 6beta-isomers series, 2 and 4, the rate decreased due to this structural modification. 6beta-Alkoxy steroids, 2 and 4, including the suicide substrates, were extremely poor substrates for the aromatization reaction. Apparent K(m) values obtained for 6alpha-alkoxy compounds 1 and 3 were similar to each other, ranging from 92 to 111nM, as shown by their previously-obtained K(i) values. The findings indicate that the stereochemistry as well as the bulkiness of the 6-ether-substituent play an important role in the ability to serve as a substrate. It is also predicted that the aromatization reaction and the mechanism-based inactivation reaction would be related and have a definite partition number which is characteristic to the compound in a series of suicide substrates. 相似文献
22.
Yoshiizumi K Nakajima F Dobashi R Nishimura N Ikeda S 《Bioorganic & medicinal chemistry》2002,10(8):2445-2460
Scavenger receptors have been proven to be implicated in the formation of atherosclerotic lesions. A series of novel derivatives of sulfatides were synthesized, and their inhibitory activities against incorporation of DiI-acetyl-LDL into macrophages were evaluated in order to clarify the structure-activity relationships of sulfatides as a scavenger receptor inhibitor and find out novel inhibitors with synthetic easiness. The chemical modification of the substructures of sulfatides led to the establishment of the following structure-activity relationships; (1) the ceramide moiety can be replaced with another structure bearing two long chains, (2) the galactose moiety can be replaced with another structure or be deleted without a large decrease in the inhibitory activity, (3) the sulfate moiety was crucial, and it was the most preferable functional group for a potent inhibitory activity. The inhibitory activity of (S)-2-octadecanoylamino-2-tetradecylcarbamoyl)ethyl sulfate sodium salt (3a) against incorporation of DiI-acetyl-LDL into macrophages was proven to be based on the inhibition against the binding of acetyl-LDL to the surface of macrophages. We discovered novel scavenger receptor inhibitors with synthetic easiness, such as (S)-2-octadecanoylamino-2-(tetradecylcarbamoyl)ethyl sulfate sodium salt (3a) and 2-octadecanoylamino-1-(octadecanoylaminomethyl)ethyl sulfate sodium salt (13q). 相似文献
23.
NRSF regulates the fetal cardiac gene program and maintains normal cardiac structure and function 总被引:1,自引:0,他引:1
24.
Sakuragi Mayumi Igota Hiromasa Uno Hiroyuki Kaji Koichi Kaneko Masami Akamatsu Rika Maekawa Koji 《Ecological Research》2003,18(4):347-354
The major factors affecting migration in large herbivores have been shown to be access to food resources and the risk of predation. Three migratory types of deer (resident, north migrant and east migrant) occur within a wintering female sika deer (Cervus nippon) population in eastern Hokkaido, Japan. We tested the hypothesis that north and east migrants feed on a higher quality diet than residents during summer, based on analyses of fecal nitrogen content. Fresh fecal pellets were collected in 18 summer ranges in the wintering area, northern area and eastern area between 1–5 August 2000. Fecal nitrogen content for all sampling sites was positively correlated with elevation, but was not correlated with distance from the wintering area. North migrants that inhabited higher (above 300m elevation) summer ranges fed on a higher quality diet than residents. In contrast, the dietary quality of east migrants that migrated over a long distance and inhabited lower (below 300m elevation) summer ranges was similar to that of residents. We conclude that east migrants may have gained significant benefit from the use of agricultural pastures with low population density conditions and without hunting; however, the recent population control program has reduced this benefit by avoiding the use of pasturelands. 相似文献
25.
Shiota Hajime; Satoh Rika; Watabe Ken-ichi; Harada Hiroshi; Kamada Hiroshi 《Plant & cell physiology》1998,39(11):1184-1193
A carrot gene homologous to the ABI3 gene of Arabidopsis wasisolated from a carrot somatic embryo cDNA library and designatedC-ABI3. The sequence of C-ABI3 was very similar to those ofABI3 of Arabidopsis and VP1 of maize in certain conserved regions.The expression of C-ABI3 was detected specifically in embryogeniccells, somatic embryos and developing seeds. Thus, expressionof C-ABI3 was limited to tissues that acquired desiccation tolerancein response to endogenous or exogenous abscisic acid (ABA).Endogenous levels of ABA in seeds increased transiently andthen desiccation of seeds started. The expression of C-ABI3in developing seeds was observed prior to the increase in levelsof endogenous ABA that was followed by desiccation of seeds.In transgenic mature leaves in which C-ABI3 was ectopicallyexpressed, expression of ECP31, ECP63 and ECP40 was inducedby treatment with ABA, which indicates that the expression ofECP genes was controlled by the pathway(s) that involved C-ABI3and ABA. This suggests that C-ABI3 has the same function asVP1/ABI3 factor in carrot somatic embryos. (Received March 4, 1998; Accepted September 4, 1998) 相似文献
26.
Hirofumi Kurita Shota Takahashi Atsushi Asada Minako Matsuo Kenta Kishikawa Akira Mizuno Rika Numano 《PloS one》2015,10(12)
Electroporation is the most widely used transfection method for delivery of cell-impermeable molecules into cells. We developed a novel gene transfection method, water-in-oil (W/O) droplet electroporation, using dielectric oil and an aqueous droplet containing mammalian cells and transgene DNA. When a liquid droplet suspended between a pair of electrodes in dielectric oil is exposed to a DC electric field, the droplet moves between the pair of electrodes periodically and droplet deformation occurs under the intense DC electric field. During electrostatic manipulation of the droplet, the local intense electric field and instantaneous short circuit via the droplet due to droplet deformation facilitate gene transfection. This method has several advantages over conventional transfection techniques, including co-transfection of multiple transgene DNAs into even as few as 103 cells, transfection into differentiated neural cells, and the capable establishment of stable cell lines. In addition, there have been improvements in W/O droplet electroporation electrodes for disposable 96-well plates making them suitable for concurrent performance without thermal loading by a DC electric field. This technique will lead to the development of cell transfection methods for novel regenerative medicine and gene therapy. 相似文献
27.
Tetsuya Tanaka Md. Morshedur Rahman Banzragch Battur Damdinsuren Boldbaatar Min Liao Rika Umemiya-Shirafuji Xuenan Xuan Kozo Fujisaki 《In vitro cellular & developmental biology. Animal》2010,46(6):560-565
Human defensins play a fundamental role in the initiation of innate immune responses to some microbial pathogens. In this
paper, we show that human α-defensin-5 displays a parasiticidal role against Toxoplasma gondii, the causative agent of toxoplasmosis. Exposure of the tachyzoite form of T. gondii to defensin induced aggregation and significantly reduced parasite viability in a concentration-dependent peptide. Pre-incubation
of tachyzoites with human α-defensin-5 followed by exposure to a mouse embryonal cell line (NIH/3T3) significantly reduced
T. gondii infection in these cells. Thus, human α-defensin-5 is an innate immune molecule that causes severe toxocity to T. gondii and plays an important role in reducing cellular infection. This is the first report showing that human α-defensin-5 causes
aggregation, leading to Toxoplasma destruction. 相似文献
28.
Rika Ozawa Cinzia M Bertea Maria Foti Ravishankar Narayana Gen-Ichiro Arimura Atsushi Muroi Massimo E Maffei Junji Takabayashi 《Plant signaling & behavior》2010,5(3):308-310
Exogenous polyamines [cadaverine (Cad), putrescine (Put), spermidine (Spd) and spermine (Spm)] elicit the production of volatiles in Lima bean (Phaseolus lunatus). Among the tested PAs, Spm induces the production of some volatile terpenoids that are known to be induced by the spider mite Tetranychus urticae. Spm treatment elicits the biosynthesis of Jasmonic acid (JA), a phytohormone known to regulate the production of the volatile terpenoids. The treatment with JA together with Spm resulted in the increased volatile emission, and predatory mites Phytoseiulus persimilis preferred JA and Spm-treated leaves over those treated with JA alone.5 JA and Spm treatment has no effects on polyamine oxidase (PAO) and Cu-amine oxidase (CuAO) but has a significant induction of calcium influx, ROS production, enzyme activities for NADPH-oxidase complex, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and glutathione peroxidase, and gene expressions except for NADPH-oxidase complex.5 Here, we report that a plasma membrane potential (Vm) depolarization was observed after polyamine perfusion with an increasing trend: Spm, Cad, Put and Spd. JA perfusion did not alter Vm but the perfusion of JA and the polyamines significantly increased Cad and Put Vm depolarization. When JA was perfused with polyamines, a negative correlation was found between Vm depolarization and the number of amino group of the polyamines tested.Key words: polyamines, lima bean, herbivore-induced volatile organic compounds, calcium and ROS signalling, jasmonic acid, quantitative gene expression, transmembrane potentialPolyamines are involved in plants’ stress responses and growth. By activating biosynthesis of nucleic acids, polyamines concern the plant growth and differentiation.1–3 Furthermore, it has been reported that polyamines are involved in the response against environmental stress and plant disease.1–4 We recently reported that exogenously applied polyamines ∼diamines [cadaverine (Cad), putrescine (Put)], triamine [spermidine (Spd)] and tetraamine ]spermine (Spm)]∽ induce volatile emission in Lima bean leaves.5 Membrane potentials (Vm) and intracellular calcium variations were also studied in Lima bean leaves after perfusion with the polyamines and with these addition of JA and here we report on these additional results.The primary candidate for intercellular signaling in higher plants is the stimulus-induced change in Vm.6 The plasma membrane potential (Vm), which lies in the range of −50 to −200 mV in Lima bean leaves,7 may be shifted either to more negative (hyperpolarization) or to more positive values (depolarization) in response to various biotic or abiotic stresses.Measurement of Vm were performed and data statistically treated as previously described (ANOVA and Tukey-Kramer’s HSD test).7 Perfusion with the polyamines (Fig. 1 single arrow) shows a specific response of the leaf tissues with a different Vm depolarization, depending on the polyamine. In general, a Vm depolarization was observed after polyamine perfusion with an increasing trend: Spm, Cad, Put and Spd (Fig. 1). Spm and Spd Vm depolarization values were significantly different (p < 0.05) from all other polyamines, whereas no significant difference was found between Put and Cad Vm depolarization (p = 0.435). In all cases, Vm depolarization was reversed by washing polyamine-treated leaves with a fresh buffer solution (Fig. 1 double arrow); however, a full recovery of the Vm was observed only for Put (Fig. 1). The linearization of the data from Figure 1 allowed to calculate the rate of Vm depolarization after perfusion of the polyamines which was higher for Spd (6.0 mV min−1; R = 0.96), equal for Put and Cad (4.8 mV min−1; Put R = 0.95; Cad R = 0.97) and lower for Spm (3.0 mV min−1; R = 0.96).Open in a separate windowFigure 1Effect of 1 mM polyamines (arrow) on the Vm of Lima bean palisade cells. Spermine (Spm) caused the lowest Vm depolarization, whereas spermidine (Spd) showed the highest values of Vm depolarization. intermediate values were found when putrescine (Put) and cadaverine (cad) were perfused. after washing the tissues with fresh buffer (double arrow) Vm was always hyperpolarized, however the initial potential was recovered only for Put, while for all other polyamines the Vm never reached the initial values. Metric bars indicate standard deviation.Perfusion with JA caused a slight and not significant (p = 0.332) Vm depolarization (Fig. 2) with respect to control. The addition of JA caused a significant increase (p < 0.01) in Vm depolarization when perfused with Cad, with respect to the sole perfusion with Cad (Fig. 1). The same was observed when JA was perfused with Put, whereas not significant differences were observed when Spm (p = 0.513) and Spd (p = 0.107) were perfused with JA (Fig. 2), with respect to the sole perfusion with Spm and Spd (Fig. 1). The linearization of the data from Figure 2 allowed to calculate the rate of Vm depolarization after perfusion of the polyamines + JA, which was higher for Cad (24.40 mV min−1; R = 0.99), almost equal for Put and Spd (Put: 14.21 mV min−1, R = 0.99; Spd: 13.49 mV min−1, R = 0.99) and lower for Spm (1.34 mV min−1; R = 0.93). For JA the rate of Vm depolarization was 0.19 mV min−1 (R = 0.96). With the addition of JA, a negative correlation was found between Vm depolarization and the number of amino group of the polyamines tested.Open in a separate windowFigure 2Effect of 1 mM polyamines + 0.1 mMJA (arrow) on the Vm of Lima bean palisade cells. the perfusion with Ja did not cause any variation in the Vm. addition of JA to Spm and Spd caused the same Vm depolarization observed in the absence of JA, whereas when JA was added to Put and Cad a stronger and significantly different Vm depolarization was observed. even in this case washing the tissues with fresh buffer (double arrow) caused a Vm hyperpolarized, however in this case Spd reached Vm values significantly more negative that the initial Vm. Metric bars indicate standard deviation. For abbreviations see Figure 1.Since ion fluxes through channels directly influence Vm, it seems reasonable to assume that molecules able to act on channel activity might be considered as important factors inducing electrical signals. Among the various channels, calcium and potassium channels are predominantly involved in cell signaling.8 In the present study, rapid and reversible Vm depolarization observed upon perfusion of Lima bean mesophyll cells with polyamines was found to be significantly increased when JA was added to Cad and Put. The reversibility of the Vm may be linked to the overall physico-chemical amphiphilic properties of polyamines, probably depending on non covalent interaction with plasma membrane molecules, as polyamines occur in plants in free form, bound electrostatically to negatively charged molecules, and conjugated to small molecules and proteins.9 Liu et al.10 showed that Spm, Spd, Cad and Put strongly inhibited opening and closing of stomata in Vicia faba, suggesting that polyamines target inward potassium channels in guard cells and modulate stomatal movements, so providing a link between abiotic stress, polyamine levels and stomatal regulation. Moreover, the transport of polyamines across the plasma membrane of plant cells is energy-dependent and calcium is involved in the uptake mechanism.1,11 Both mechanisms can be correlated to the observed Vm depolarization, and the positive correlation between intracellular Ca2+ concentration5 and Vm depolarizing activity of polyamines confirms the involvement of Ca2+ during polyamine uptake.11 相似文献
29.
The function of bcl-2 in preventing cell death is well known, but the mechanisms whereby bcl-2 functions are not well characterized. One mechanism whereby bcl-2 is thought to function is by alleviating the effects of oxidative stress upon the cell. To examine whether Bcl-2 can protect cells against oxidative injury resulting from post-hypoxic reoxygenation (H/R), we subjected rat fibroblasts Rat-1 and their bcl-2 transfectants b5 to hypoxia (5% CO2, 95% N2) followed by reoxygenation (5% CO2, 95% air). The bcl-2 transfectants exhibited the cell viability superior to that of their parent non-transfectants upon treatment with reoxygenation after 24-, 48-, or 72-h hypoxia, but not upon normoxic serum-deprivation or upon serum-supplied hypoxic treatment alone. Thus bcl-2 transfection can prevent cell death of some types, which occurred during H/R but yet not appreciably until termination of hypoxia. The time-sequential events of H/R-induced cell death were shown to be executed via (1) reactive oxygen species (ROS) production at 1-12 h after H/R, (2) activation of caspases-1 and -3, at 1-3 h and 3-6 h after H/R, respectively, and (3) loss of mitochondrial membrane potential (DeltaPsi) at 3-12 h after H/R. These cell death-associated events were prevented entirely except caspase-1 activation by bcl-2 transfection, and were preceded by Bcl-2 upregulation which was executed as early as at 0-1 h after H/R for the bcl-2 transfectants but not their non-transfected counterpart cells. Thus upregulation of Bcl-2 proteins may play a role in prevention of H/R-induced diminishment of cell viability, but may be executed not yet during hypoxia itself and be actually operated as promptly as ready to go immediately after beginning of H/R, resulting in cytoprotection through blockage of either ROS generation, caspase-3 activation, or DeltaPsi decline. 相似文献
30.
Mating disruption method against the vine mealybug,Planococcus ficus: effect of sequential treatment on infested vines
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Rakefet Sharon Tirtza Zahavi Tamar Sokolsky Carmit Sofer‐Arad Maor Tomer Rika Kedoshim Ally R. Harari 《Entomologia Experimentalis et Applicata》2016,161(1):65-69
The vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), is a major pest of vineyards. Here, we tested the efficacy of the mating disruption method against the pest when applied during one or two successive years in high and low infestation levels. Following 1 year of treatment, at low initial infestation levels a shutdown of pheromone traps was observed, along with a significant reduction in infested vines. With initially high infestation levels, a gradual reduction in infested vines was observed, with a trap shutdown seen only after the second year of pheromone application. We discuss the implications of the male mating disruption method for this pest in which the wingless females are aggregated with limited movement among vines, offering multiple mating opportunities for the flying male. 相似文献