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排序方式: 共有400条查询结果,搜索用时 78 毫秒
161.
Riccardo Villa Alessandra M. Martorana Suguru Okuda Louise J. Gourlay Marco Nardini Paola Sperandeo Gianni Dehò Martino Bolognesi Daniel Kahne Alessandra Polissi 《Journal of bacteriology》2013,195(5):1100-1108
Lipopolysaccharide is a major glycolipid component in the outer leaflet of the outer membrane (OM), a peculiar permeability barrier of Gram-negative bacteria that prevents many toxic compounds from entering the cell. Lipopolysaccharide transport (Lpt) across the periplasmic space and its assembly at the Escherichia coli cell surface are carried out by a transenvelope complex of seven essential Lpt proteins spanning the inner membrane (LptBCFG), the periplasm (LptA), and the OM (LptDE), which appears to operate as a unique machinery. LptC is an essential inner membrane-anchored protein with a large periplasm-protruding domain. LptC binds the inner membrane LptBFG ABC transporter and interacts with the periplasmic protein LptA. However, its role in lipopolysaccharide transport is unclear. Here we show that LptC lacking the transmembrane region is viable and can bind the LptBFG inner membrane complex; thus, the essential LptC functions are located in the periplasmic domain. In addition, we characterize two previously described inactive single mutations at two conserved glycines (G56V and G153R, respectively) of the LptC periplasmic domain, showing that neither mutant is able to assemble the transenvelope machinery. However, while LptCG56V failed to copurify any Lpt component, LptCG153R was able to interact with the inner membrane protein complex LptBFG. Overall, our data further support the model whereby the bridge connecting the inner and outer membranes would be based on the conserved structurally homologous jellyroll domain shared by five out of the seven Lpt components. 相似文献
162.
Takanori Yoshikawa Suguru Ozawa Naoki Sentoku Jun-Ichi Itoh Yasuo Nagato Shuji Yokoi 《Planta》2013,238(1):229-237
Juvenile-to-adult phase change is an indispensable event which guarantees a successful life cycle. Phase change has been studied in maize, Arabidopsis and rice, but is mostly unknown in other species. Soybean/Fabaceae plants undergo drastic changes of shoot architecture at the early vegetative stage including phyllotactic change and leaf type alteration from simple to compound. These characteristics make soybean/Fabaceae plants an interesting taxon for investigating vegetative phase change. Following the expansion of two cotyledons, two simple leaves simultaneously emerge in opposite phyllotaxy. The phyllotaxy of the third and fourth leaves is not fixed; both opposite and distichous phyllotaxis are observed within the same population. Leaves were compound from the third leaf. But the third leaf was rarely simple. Morphological and quantitative changes in early vegetative phase were recognized in leaf size, leaf shape, number of trichomes, stipule size and shape, and shoot meristem shape. Two microRNA genes, miR156 and miR172, are known to be associated with vegetative phase change. Examination of the expression level revealed that miR156 expression was high in the first two leaves and subsequently down-regulated, and that of miR172 showed the inverse expression pattern. These expression patterns coincided with the case of other species. Taken all data together, the first and second leaves represent juvenile phase, the fifth and upper leaves adult phase, and the third and fourth leaves intermediate stage. Further investigation of soybean phase change would give fruitful understandings on plant development. 相似文献
163.
Suguru Kimoto Katsuhiko Kimoto Hiroshi Murakami Atsuko Gunji Nana Ito Yasuhiko Kawai 《Gerodontology》2013,30(3):187-193
doi: 10.1111/j.1741‐2358.2012.00658.x Survival analysis of mandibular complete dentures with acrylic‐based resilient liners Objective: The purpose of this long‐term randomised controlled trial was to compare the longevity of dentures constructed using a conventional acrylic resin (CAR) to that of dentures constructed using an acrylic‐based resilient liner (ARL). Materials and methods: The follow‐up study was essentially carried out by annual telephone calls to each of the 67 participants. The Kaplan–Meier method and life‐table analysis were used for univariate analyses. The Cox proportional‐hazards test was used as a final model for statistically adjusting predictor variables such as sex, clinician type, mandibular denture type and age at denture delivery. Results: The denture type was likely to affect the survival time of the dentures, while the sex and clinician type were not. The group using acrylic‐based resilient denture liners had twice the risk of having shorter denture‐survival times than those using conventional acrylic resin dentures. Younger participants were likely to have a reduced risk of having shorter denture‐survival times than older participants. Conclusion: We conclude that mandibular complete dentures constructed using ARL are twice as likely as dentures constructed using CAR to have shorter denture survival times, mainly because of material deterioration. 相似文献
164.
165.
Masahiko Muraji Sadao Wakamura Hiroe Yasui Norio Arakaki Yasutsune Sadoyama Suguru Ohno Kunihiko Matsuhira 《Applied Entomology and Zoology》2011,46(3):363-373
Genetic variation of the white-spotted longicorn beetle Anoplophora spp., distributed on the Japanese mainland and the Ryukyu Islands, was examined using nucleotide sequences of mitochondrial
DNA. Two fragments, a 1.2-kb-long fragment containing portions of the cytochrome oxidase subunit I and II genes and a 1.4-kb-long
fragment containing portions of 16S and 12S rDNAs, were sequenced. In phylogenetic analyses based on the sequences, 294 individuals
collected at 75 localities were divided into two major groups (groups A and B) and then split into seven subgroups (A1–A4
and B1–B3). In group A, the closely related subgroups A1, A2, and A3 were mainly distributed on the Japanese mainland and
were roughly separated among geographic areas, although the range of A3 spread significantly from Kyushu to the Central Ryukyu
Islands. The sequence of A4, detected from one individual collected in eastern Honshu, was almost the same as that reported
for A. chinensis (Forster) on the Chinese continent. In group B, subgroups B1 and B2 were restricted to the Central and Southern Ryukyu Islands,
respectively, while B3 was distributed widely in both regions. Based on the results, we discuss the geographic origin of the
haplotypes and movement of the insects between geographic areas. 相似文献
166.
A homoleptic hexanuclear Cu cluster, [(Cu(DSB)(CBT))2(Cu2Br)2][PPh4]2 (1-PPh4) [DSB = 2,3-disulfidobenzoate; CBT = 3-carboxybenzene-1,2-bis(thiolate)] was synthesized as dark green crystals by the reaction of CuCl2 with 2,3-dimercaptobenzoic acid in acetate buffer solution. The X-ray crystal study of 1-PPh4 revealed its unique structural features: (1) one of two types of crystallographically distinct Cu centers adopted a square planer geometry and the other center had a tetrahedral geometry, and (2) intermolecular H-bonding interactions connected between carboxylic acid group of CBT and the carboxylate group of DSB led to the construction of an unprecedented topologic architecture of a zigzag patterned infinite sheet. In addition, taking into account the total charge of the molecule, which contained 2,3-disulfidobenzoate and 3-carboxybenzene-1,2-bis(thiolate), and the diamagnetic nature of 1-PPh4, 1-PPh4 led to it is assignment as a mixed-valence Cu(I)/Cu(III) cluster. Such mixed valence states of Cu atoms were also examined by density functional theory calculation. 相似文献
167.
Lactobacillus bulgaricus OLL1181 activates the aryl hydrocarbon receptor pathway and inhibits colitis 总被引:1,自引:0,他引:1
Takamura T Harama D Fukumoto S Nakamura Y Shimokawa N Ishimaru K Ikegami S Makino S Kitamura M Nakao A 《Immunology and cell biology》2011,89(7):817-822
Increasing evidence suggests that the aryl hydrocarbon receptor (AhR) pathway has an important role in the regulation of inflammatory responses. Most recently, we have shown that the activation of the AhR pathway by a potent AhR agonist inhibits the development of dextran sodium sulfate (DSS)-induced colitis, a model of human ulcerative colitis, by the induction of prostaglandin E2 (PGE2) in the large intestine. Because several strains of probiotic lactic acid bacteria have been reported to inhibit DSS-induced colitis by unidentified mechanisms, we hypothesized that particular strains of lactic acid bacterium might have the potential to activate the AhR pathway, thereby inhibiting DSS-induced colitis. This study investigated whether there are specific lactic acid bacterial strains that can activate the AhR pathway, and if so, whether this AhR-activating potential is associated with suppression of DSS-induced colitis. By using AhR signaling reporter cells, we found that Lactobacillus bulgaricus OLL1181 had the potential to activate the AhR pathway. OLL1181 also induced the mRNA expression of cytochrome P450 family 1A1 (CYP1A1), a target gene of the AhR pathway, in human colon cells, which was inhibited by the addition of an AhR antagonist, α-naphthoflavon (αNF). In addition, mice treated orally with OLL1181 showed an increase in CYP1A1 mRNA expression in the large intestine and amelioration of DSS-induced colitis. Thus, OLL1181 can induce activation of the intestinal AhR pathway and inhibit DSS-induced colitis in mice. This strain of lactic acid bacterium has therefore the potential to activate the AhR pathway, which may be able to suppress colitis. 相似文献
168.
Five species of oral Veillonella, V. atypica, V. denticariosi, V. dispar, V. parvula, and V. rogosae, have been suggested to be early colonizers of dental biofilm and causes of opportunistic infections and oral malodor. However,
the pathogenicity and the distribution of oral Veillonella spp. have not been clarified. Previously, oral Veillonella spp. were identified by using 16S rDNA sequence analysis. In addition, recently, Veillonella isolates from human tongue biofilm were identified by rpoB gene sequences, but these procedures are time-consuming and complex. To overcome this problem, Igarashi et al. have designed
species-specific primer sets for oral Veillonella spp. by using a highly variable region in the rpoB gene. In the present study, the distribution and frequency of oral Veillonella spp. in the tongue biofilm of healthy adults in their 20s were examined by using these species-specific primer sets. Tongue
biofilms of these subjects were found to be divided into two groups based on the distribution and frequency of oral Veillonella spp. In one group, V. rogosae was the predominant species; the other group consisted of mainly V. dispar and V. atypica. Multiple factors may influence these differences in distribution and frequency of oral Veillonella spp. in tongue biofilm. This is the first report also demonstrating the availability of the species-specific primer sets
for PCR to determine the distribution and frequency of oral Veillonella spp. in the tongue biofilm of healthy adults in their 20s. 相似文献
169.
Takashi Okabe Megumi Kumagai Yoshihiro Nakajima Suguru Shirotake Kiichiro Kodaira Masafumi Oyama Munehisa Ueno Masaaki Ikeda 《PloS one》2014,9(10)
In mammals, the circadian rhythm central generator consists of interactions among clock genes, including Per1/2/3, Cry1/2, Bmal1, and Clock. Circadian rhythm disruption may lead to increased risk of cancer in humans, and deregulation of clock genes has been implicated in many types of cancers. Among these genes, Per2 is reported to have tumor suppressor properties, but little is known about the correlation between Per2 and HIF, which is the main target of renal cell carcinoma (RCC) therapy. In this study, the rhythmic expression of the Per2 gene was not detectable in renal cancer cell lines, with the exception of Caki-2 cells. In Caki-2 cells, HIF1α increased the amplitude of Per2 oscillation by directly binding to the HIF-binding site located on the Per2 promoter. These results indicate that HIF1α may enhance the amplitude of the Per2 circadian rhythm. 相似文献