Genome structure of the Lactobacillus temperate phage Φg1e: the whole genome sequence and the putative promoter/repressor system

The complete genome sequence of a Lactobacillus temperate phage Φg1e was established. The double-stranded DNA is composed of 42 259 bp, and encodes for sixty-two possible open reading frames (ORF) as well as several potential regulatory sequences. Based on comparative analysis with other related proteins of the Lactobacillus and Lactococcus phages as well as the Escherichia coli phages (such as lambda), functions were putatively assigned to several Φg1e ORFs: cng and cpg (encoding for repressors), hel (helicase), ntp (NTPase), and several ORFs (e.g., minor capsid proteins). An about 1000-bp DNA region of Φg1e containing cpg and cng was inferred to function as a promoter/repressor system for the Φg1e lysogenic and lytic pathway

The Lifestyle of the Segmented Filamentous Bacterium: A Non-Culturable Gut-Associated Immunostimulating Microbe Inferred by Whole-Genome Sequencing

Numerous microbes inhabit the mammalian intestinal track and strongly impact host physiology; however, our understanding of this ecosystem remains limited owing to the high complexity of the microbial community and the presence of numerous non-culturable microbes. Segmented filamentous bacteria (SFBs), which are clostridia-related Gram-positive bacteria, are among such non-culturable populations and are well known for their unique morphology and tight attachment to intestinal epithelial cells. Recent studies have revealed that SFBs play crucial roles in the post-natal maturation of gut immune function, especially the induction of Th17 lymphocytes. Here, we report the complete genome sequence of mouse SFBs. The genome, which comprises a single circular chromosome of 1 620 005 bp, lacks genes for the biosynthesis of almost all amino acids, vitamins/cofactors and nucleotides, but contains a full set of genes for sporulation/germination and, unexpectedly, for chemotaxis/flagella-based motility. These findings suggest a triphasic lifestyle of the SFB, which comprises two types of vegetative (swimming and epicellular parasitic) phases and a dormant (spore) phase. Furthermore, SFBs encode four types of flagellin, three of which are recognized by Toll-like receptor 5 and could elicit the innate immune response. Our results reveal the non-culturability, lifestyle and immunostimulation mechanisms of SFBs and provide a genetic basis for the future development of the SFB cultivation and gene-manipulation techniques

Two-step stabilization of orbital order and the dynamical frustration of spin in the model charge-transfer insulator KCuF3

We report a combined experimental and theoretical study of KCuF3, which offers - because of this material's relatively simple lattice structure and valence configuration (d9, i.e., one hole in the d-shell) - a particularly clear view of the essential role of the orbital degree of freedom in governing the dynamical coupling between the spin and lattice degrees of freedom. We present Raman and x-ray scattering evidence that the phase behaviour of KCuF3 is dominated above the Neel temperature (T_N = 40 K) by coupled orbital/lattice fluctuations that are likely associated with rotations of the CuF6 octahedra, and we show that these orbital fluctuations are interrupted by a static structural distortion that occurs just above T_N. A detailed model of the orbital and magnetic phases of KCuF3 reveals that these orbital fluctuations - and the related frustration of in-plane spin-order-are associated with the presence of nearly degenerate low-energy spin-orbital states that are highly susceptible to thermal fluctuations over a wide range of temperatures. A striking implication of these results is that the ground state of KCuF3 at ambient pressure lies near a quantum critical point associated with an orbital/spin liquid phase that is obscured by emergent Neel ordering of the spins; this exotic liquid phase might be accessible via pressure studies.Comment: 13 pages, 3 figure

「勉強」の概念の変化 : 理科嫌い・理科離れの背景

理工系離れや理科嫌い・理科離れに見られるような現象は，理工系の教科や理科だけに特有なものではなく他の領域や分野でも見られる。こうした現象は一般には勉強嫌い・勉強離れと呼べるものであり，この背景には勉強の概念の変化があると考えられる。そこで本研究では，理科嫌い・理科離れは勉強嫌い・勉強触れの一つの現われであり，この間題の解明には，勉強の概念とその変化を明らかにすることが必要である，との立場から論述する。勉強の概念には非快適要素が含まれ それが勉強嫌い・勉強離れを作り，理科嫌い・理科離れの原因ともなる。非快適要素を何らかの変換装置で快適要素に変える必要がある。変換装置の一例として環境教育を取り上げ，環境問題に対する学生の意識調査を行った。この調査結果から，環境問題を解決するために理科の学習が必要と考えている学生は，不要と考えている学生より，理科嫌いの割合が少ないという傾向が見られたThere has been a disscusion that likes and dislikes of science came from the tendency to avoid an academic disipline. The original concept of "BENKYO" has included unpleasant factors which produced the dislikes of science. We need the transformer that will make unpleasant factors into pleasent ones