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971.
Takeshi Uemura Kyohei Higashi Miki Takigawa Toshihiko Toida Keiko Kashiwagi Kazuei Igarashi 《The international journal of biochemistry & cell biology》2009,41(12):2538-2545
We proposed that a group of genes whose expression is enhanced by polyamines at the level of translation in Escherichia coli and mammalian cells be referred to as a “polyamine modulon”. In Saccharomyces cerevisiae, proteins whose synthesis is enhanced by polyamines at the level of translation were searched for using a polyamine-requiring mutant of S. cerevisiae deficient in ornithine decarboxylase (YPH499 Δspe1). Addition of spermidine to the medium recovered the spermidine content and enhanced cell growth of the YPH499 Δspe1 mutant by 3–5-fold. Under these conditions, synthesis of COX4, one of the subunits of cytochrome C oxidase (complex IV), was enhanced by polyamines about 2.5-fold at the level of translation. Accordingly, the COX4 gene is the first member of a polyamine modulon in yeast. Polyamines enhanced COX4 synthesis through stimulation of the ribosome shunting of the stem–loop structures (hairpin structures) during the scanning of the 5′-untranslated region (5′-UTR) of COX4 mRNA by 40S ribosomal subunit-Met-tRNAi complex. 相似文献
972.
D. Hanajima S. Haruta T. Hori M. Ishii K. Haga Y. Igarashi 《Journal of applied microbiology》2009,106(1):118-129
Aims: To study the microbial community responsible for the reduction of the polluting load during aerobic digestion of pig slurry.
Methods and Results: We analysed bacterial succession by nonculture-based methods and determined the physicochemical parameters and polluting substances during 6 days of aerobic digestion. The bacterial subpopulations evolved by aeration, predominantly Bacillus spp., degraded organic matter and vigorously consumed oxygen, as indicated by low oxidation–reduction potential (ORP). In this phase, the volatile fatty acid (VFA) levels drastically decreased, and VFAs were almost depleted on day 4. Simultaneously, the ammonia concentration decreased to its lowest level on day 4; thereafter, it increased until the end of the process. After the decrease in the total organic carbon content in the supernatant of the decomposed slurry, the ORP increased (∼0 mV), and the microbial community showed an abundance of lineages belonging to the phylum Proteobacteria.
Conclusions: Bacillus was the predominant member of the bacterial community driving the VFA-removal process. Their predominance was related to the presence of available carbon, including VFAs and changes in ORP.
Significance and Impact of the Study: Information on the relationships among the involved microbes, polluting materials and physicochemical parameters will aid process design and retrofitting of the process. 相似文献
Methods and Results: We analysed bacterial succession by nonculture-based methods and determined the physicochemical parameters and polluting substances during 6 days of aerobic digestion. The bacterial subpopulations evolved by aeration, predominantly Bacillus spp., degraded organic matter and vigorously consumed oxygen, as indicated by low oxidation–reduction potential (ORP). In this phase, the volatile fatty acid (VFA) levels drastically decreased, and VFAs were almost depleted on day 4. Simultaneously, the ammonia concentration decreased to its lowest level on day 4; thereafter, it increased until the end of the process. After the decrease in the total organic carbon content in the supernatant of the decomposed slurry, the ORP increased (∼0 mV), and the microbial community showed an abundance of lineages belonging to the phylum Proteobacteria.
Conclusions: Bacillus was the predominant member of the bacterial community driving the VFA-removal process. Their predominance was related to the presence of available carbon, including VFAs and changes in ORP.
Significance and Impact of the Study: Information on the relationships among the involved microbes, polluting materials and physicochemical parameters will aid process design and retrofitting of the process. 相似文献
973.
Intertwined interspecies relationships: approaches to untangle the microbial network 总被引:1,自引:0,他引:1
Shin Haruta Souichiro Kato Kyosuke Yamamoto Yasuo Igarashi 《Environmental microbiology》2009,11(12):2963-2969
In nature, microorganisms live by interacting with each other. Microbiological studies that only consider pure cultures are not sufficient to adequately describe the natural behaviour of microbes. Several microbial interactions have been recognized to affect the growth or metabolism of others; e.g. syntrophic cometabolism, competition, production of inhibitors or activators, and predation. It is believed that third‐party organisms easily affect the two‐species relationships and these relationships form the basis of interspecies networks within microbial communities. A microbial network contributes to ‘functional redundancy’ or ‘structural diversity’ and the microbial communities effectively act as a multicellular organism. It is necessary to understand not only the physiological activity of members within microbial communities but also their roles to regulate the activity or population of others. To access the microbial network, we require (i) comprehensive determination of all possible interspecies relationships among microbes, (ii) knock‐out experiments by which certain members can be removed or suppressed, and (iii) supplemental addition of microbes or activation of certain members. Microbial network studies have started using defined microbial communities, i.e. a mixed culture that is composed of three or four species. In order to expand these studies to microflora in nature, microbial ecology requires the help of mathematical biology. 相似文献
974.
Yasuko Watanabe Manabu Igarashi Yuhei Shimoyama Tohru Yamamori Mikinori Kuwabara Osamu Inanami 《Biochemical and biophysical research communications》2010,394(3):522-38545
To explore Cu(II) ion coordination by His186 in the C-terminal domain of full-length prion protein (moPrP), we utilized the magnetic dipolar interaction between a paramagnetic metal, Cu(II) ion, and a spin probe introduced in the neighborhood of the postulated binding site by the spin labeling technique (SDSL technique). Six moPrP mutants, moPrP(D143C), moPrP(Y148C), moPrP(E151C), moPrP(Y156C), moPrP(T189C), and moPrP(Y156C,H186A), were reacted with a methane thiosulfonate spin probe and a nitroxide residue (R1) was created in the binding site of each one. Line broadening of the ESR spectra was induced in the presence of Cu(II) ions in moPrP(Y148R1), moPrP(Y151R1), moPrP(Y156R1), and moPrP(T189R1) but not moPrP(D143R1). This line broadening indicated the presence of electron-electron dipolar interaction between Cu(II) and the nitroxide spin probe, suggesting that each interspin distance was within 20 Å. The interspin distance ranges between Cu(II) and the spin probes of moPrP(Y148R1), moPrP(Y151R1), moPrP(Y156R1), and moPrP(T189R1) were estimated to be 12.1 Å, 18.1 Å, 10.7 Å, and 8.4 Å, respectively. In moPrP(Y156R1,H186A), line broadening between Cu(II) and the spin probe was not observed. These results suggest that a novel Cu(II) binding site is involved in His186 in the Helix2 region of the C-terminal domain of moPrPC. 相似文献
975.
CD8(+) T cells provide broad immunity to viruses, because they are able to recognize all types of viral proteins. Therefore, the development of vaccines capable of inducing long-lived memory CD8(+) T cells is desired to prevent diseases, especially those for which no vaccines currently exist. However, in designing CD8(+) T cell vaccines, the role of CD4(+) T cells in the induction and maintenance of memory CD8(+) T cells remains uncertain. In the present study, the necessity or not of CD4(+) T cells in the induction and maintenance of memory CD8(+) T cells was investigated in mice immunized with liposome-coupled CTL epitope peptides. When OVA-derived CTL epitope peptides were chemically coupled to the surfaces of liposomes and inoculated into mice, both primary and secondary CTL responses were successfully induced. The results were further confirmed in CD4(+) T cell-eliminated mice, suggesting that CD4(+) T cells were not required for the generation of memory CD8(+) T cells in the case of immunization with liposome-coupled peptides. Thus, surface-linked liposomal antigens, capable of inducing long-lived memory CD8(+) T cells without the contribution of CD4(+) T cells, might be applicable for the development of vaccines to prevent viral infection, especially for those viruses that evade humoral immunity by varying their surface proteins, such as influenza viruses, HIV, HCV, SARS coronaviruses, and Ebola viruses. 相似文献
976.
Youn-Kyoung Goo M. Alaa Terkawi Honglin Jia G. Oluga Aboge Hideo Ooka Bryce Nelson Suk Kim Fujiko Sunaga Kazuhiko Namikawa Ikuo Igarashi Yoshifumi Nishikawa Xuenan Xuan 《Parasitology international》2010,59(3):481-486
The effects of artesunate, a water-soluble artemisinin derivative, against Babesia species, including Babesia bovis, Babesia gibsoni and Babesia microti were studied. Cultures of B. bovis and B. gibsoni were treated with 0.26, 2.6, 26 and 260 μM artesunate, showing inhibition of parasite growth at concentrations equal to and greater than 2.6 μM artesunate by days 3 post-treatment for B. gibsoni and B. bovis in a dose-dependent manner. Consistent with in vitro experiments, artesunate was effective in the treatment of mice infected with B. microti at doses equal to and greater than 10 mg/kg of body weight on days 8–10 post-infection. Taken together, these results suggest that artesunate could be a potential drug against Babesia infection. 相似文献
977.
Kengo Sasaki Masahiko Morita Shin-ichi Hirano Daisuke Sasaki Naoya Ohmura Yasuo Igarashi 《Applied microbiology and biotechnology》2010,87(4):1579-1586
We have reported for the first time that agricultural and cellulosic waste, i.e., rice straw was directly applied to methanogenic
bioreactors containing carbon fiber textiles (CFT) as supporting material. Addition of CFT to the methanogenic bioreactors
enhanced the conversion of dichromate chemical oxygen demand of the substrate to methane (41%) to a greater extent than bioreactors
without CFT (9%). In addition, removal of rice straw as a suspended solid was increased from 31% (in bioreactors without CFT)
to 57% (in those with CFT). Methanogenic 16S rRNA gene analysis showed that the abundance of acetoclastic methanogen, genus
Methanosarcina, was about 11 times higher in bioreactors with CFT (suspended fraction plus retained fraction to CFT) than in bioreactors
without CFT (suspended fraction), resulting in lower concentration of acetate in bioreactors with CFT (0.4 mM) than in those
without CFT (29.7 mM). On the other hand, the abundance of hydrogenotrophic methanogen, genus Methanobacterium, in bioreactors with CFT was similar to those without CFT. Bacterial communities in bioreactors with CFT were different from
those in bioreactors without CFT. Our results indicated that specific microbial community and cooperative relationships between
microorganisms in reactors containing CFT facilitated efficient decomposition of rice straw and its conversion to methane. 相似文献
978.
979.
Boehlke C Kotsis F Patel V Braeg S Voelker H Bredt S Beyer T Janusch H Hamann C Gödel M Müller K Herbst M Hornung M Doerken M Köttgen M Nitschke R Igarashi P Walz G Kuehn EW 《Nature cell biology》2010,12(11):1115-1122
The mTOR pathway is the central regulator of cell size. External signals from growth factors and nutrients converge on the mTORC1 multi-protein complex to modulate downstream targets, but how the different inputs are integrated and translated into specific cellular responses is incompletely understood. Deregulation of the mTOR pathway occurs in polycystic kidney disease (PKD), where cilia (filiform sensory organelles) fail to sense urine flow because of inherited mutations in ciliary proteins. We therefore investigated if cilia have a role in mTOR regulation. Here, we show that ablation of cilia in transgenic mice results in enlarged cells when compared with control animals. In vitro analysis demonstrated that bending of the cilia by flow is required for mTOR downregulation and cell-size control. Surprisingly, regulation of cell size by cilia is independent of flow-induced calcium transients, or Akt. However, the tumour-suppressor protein Lkb1 localises in the cilium, and flow results in increased AMPK phosphorylation at the basal body. Conversely, knockdown of Lkb1 prevents normal cell-size regulation under flow conditions. Our results demonstrate that the cilium regulates mTOR signalling and cell size, and identify the cilium-basal body compartment as a spatially restricted activation site for Lkb1 signalling. 相似文献
980.
Mineyo Iwase Yoko Satta Hirohisa Hirai Yuriko Hirai Naoyuki Takahata 《BMC evolutionary biology》2010,10(1):225