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101.
Methyl 3‐Hydroxymyristate,a Diffusible Signal Mediating phc Quorum Sensing in Ralstonia solanacearum
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Prof. Kenji Kai Hideyuki Ohnishi Mika Shimatani Shiho Ishikawa Yuka Mori Prof. Akinori Kiba Prof. Kouhei Ohnishi Prof. Mitsuaki Tabuchi Prof. Yasufumi Hikichi 《Chembiochem : a European journal of chemical biology》2015,16(16):2309-2318
Ralstonia solanacearum, a plant pathogenic bacterium causing “bacterial wilt” on crops, uses a quorum sensing (QS) system consisting of phc regulatory elements to control its virulence. Methyl 3‐hydroxypalmitate (3‐OH PAME) was previously identified as the QS signal in strain AW1. However, 3‐OH PAME has not been reportedly detected from any other strains, and this suggests that they produce another unknown QS signal. Here we identify (R)‐methyl 3‐hydroxymyristate [(R)‐3‐OH MAME] as a new QS signal that regulates the production of virulence factors and secondary metabolites. (R)‐3‐OH MAME was synthesized by the methyltransferase PhcB and sensed by the histidine kinase PhcS. The phylogenetic trees of these proteins from R. solanacearum strains were divided into two groups, according to their QS signal types—(R)‐3‐OH MAME or (R)‐3‐OH PAME. These results demonstrate that (R)‐3‐OH MAME is another crucial QS signal and highlight the unique evolution of QS systems in R. solanacearum. 相似文献
102.
Summary Novel vinyl polymers bearing monoazacrown ether-type side chains with a number average molecular weigh of over 5000 were radically synthesized from the 16-membered α-methylenemacrolide monomers. The obtained polymers possessed a Na+ or K+ selective extraction ability, whereas K+ was preferentially extracted by the monomers. The polymer having the N-(2-naphthoyl)azacrown ether pendant groups showed a selective UV-responsive complexation with Li+ in 1,2-dichloroethane-CH3CN. 相似文献
103.
In order to improve Cu(II) adsorption ability of chelating resins based on a macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane-5,7-dione (L) bound to crosslinked copolymers, the resins were prepared by reaction of L with poly(glycidyl methacrylate)s crosslinked with ethylene glycol dimethacrylate (1G), tetraethylene glycol dimethacrylate (4G) or nonaethylene glycol dimethacrylate (9G). By systematically changing the amounts of each crosslinker (degree of crosslinking) and of isobutyl acetate (IBA) as diluent in the suspension polymerization of the monomers, precursory copolymers with various degrees of crosslinking as well as with different specific surface areas (SSAs) were prepared, and then L was introduced into them. Ligand contents, SSAs, and Cu(II) adsorption abilities of the resulting resins were evaluated, and it was clarified that resins derived from precursors (prepared by using 4G or 9G in the presence of 120–160 vol % of IBA) exhibit high capacities for Cu(II), whereas the capacities of resins crosslinked with 1G are not so high. Further detailed study on the uptake of metal ions using the resins RG4D(10)-140 and RG9D(10)-140 (derived from the precursors prepared by using 10 mol % of the respective crosslinkers 4G and 9G in the presence of 140 vol % of IBA) showed that RG9D(10)-140 is much superior to RG4D(10)-140 in the column-mode adsorption of Cu(II). These results indicate that not only the selection of the suitable crosslinker but also the use of a pertinent amount of the diluent are very important in improving the complexing abilities of the polymer-bound L. © 1996 John Wiley & Sons, Inc. 相似文献
104.
Akinori Kidera Toshihiro Higashira Yuko Ikeda Kenji Urayama Shinzo Kohjiya 《Polymer Bulletin》1997,38(4):461-468
Size distribution of polymer clusters in pre-gel state has been measured by means of gel permeation chromatography (GPC)
for crosslinking system between bifunctional prepolymer and trifunctional crosslinker. Experimental chromatograms have been
obtained at various degree of conversion, and compared with theoretical chromatograms predicted by the Flory-Stockmayer model.
Experimental size distribution at low conversion is well described by the theory. On the other hand, experimental chromatograms
at higher conversions show a long tail in lower elution volume region which is unexpected by the theory. This result suggests
that clusters with relatively linear structure which is not predicted by the theory are formed. The formation of the clusters
with fairly linear structure is estimated to originate from unequality in reactivity of sites in crosslinker which is due
to steric hindrance by the reacted sites.
Received: 29 November 1996/Revised: 25 December 1996/Accepted: 27 December 1996 相似文献
105.
Cooklev Todor Nishihara Akinori Yoshida Toshiyuki Sablatash Mike 《Multidimensional Systems and Signal Processing》1998,9(1):39-76
In the paper new design methods for multidimensional two-channel perfect reconstruction (PR) FIR filter banks are described. The filters have linear phase, achieve an arbitrarily high number of vanishing moments and can be used to obtain biorthogonal wavelet bases. Two-dimensional wavelet bases with square, rectangular, and hexagonal support are constructed. A design method that trades off vanishing moments and frequency selectivity is described. These two properties are both important in subband coding, but they each require a share of the degrees of freedom available from the total number of filter coefficients. Novel analytic formulae are derived and are applied to provide illustrative examples. 相似文献
106.
The release of 133Xe from (Th,U)O2 was studied at a low fission density by using a post-irradiation technique. The uranium concentrations of the specimens ranged from 0.15 to 20 mol% U02. Heating curves of the release gave almost the same pattern in shape, while the total release, which was the combination of an in-pile release and a post-irradiation release up to 1000°C, increased with uranium concentration except for the nominally pure ThO2. Effects of preparation conditions of specimens such as atmosphere, temperature and stoichiometry were also studied and found to be minor. Possible release mechanisms were discussed. 相似文献
107.
Summary MgCl2 supported titanium catalysts were prepared by mechanical pulverization or MgCl2 with titanium compounds using two types of machines, rotatory mill and vibratory mill. Both methods gave substantially the same results, although vibratory mill much saved the milling time. The nature of the fixed titanium compounds was not homogeneous, and the titanium compounds fixed at an earlier stage of milling, which could be located at exposed active edge positions of MgCl2 particles, showed higher activity in ethylene polymerization. On the other hand, those fixed at the later stage showed lower activity and caused reaggregation of the particles. Furthermore, chlorine-free titanate compounds, Ti(OBu)4 and Ti(OEt)4, also could be fixed on MgCl2 which showed high activity in ethylene polymerization. 相似文献
108.
V. V. Srinivasu Ken-ichi Itoh Akinori Hashizume V. Sreedevi Hideaki Kohmoto Tamio Endo R. Ricardo da Silva Yakov Kopelevich Sergio Moehlecke Takami Masui Kazuya Hayashi 《Journal of Superconductivity》2001,14(1):41-46
Nonresonant microwave absorption (NMA) measurements were carried out at liquid-nitrogen temperature on a high quality Bi2212 single crystal, as a function of microwave power in three mutual orientations of crystal ab plane, dc field (Hdc), and microwave magnetic field (Hw). NMA line shapes in Bi2212 crystal are complicated with a narrow peak (P1 peak) located near zero field, followed by a much broader second peak (P2 peak) in the particular orientations. More excitingly, we show that the P2 peak qualitatively evolves as a function of microwave power in the orientation of Hdc ab plane,
plane, and Hdc Hw. In this configuration, as the microwave power is progressively increased, the broad P2 peak first gets smeared off and then a multiple peak structure appears, which develops into another narrower second peak (Ps-peak) at high enough microwave powers. In the orientation of
plane, Hw ab plane, and Hdc Hw, we report for the first time the appearance and disappearance of a new second peak (P2-like peak) as a function of microwave power. 相似文献
109.
110.