A Semantic Approach to Teaching English in Japanese High School

Article教職研究, 4:103-141 (2011)departmental bulletin pape

Recent Advances in Our Understanding of the Biosynthesis of Sulfur Modifications in tRNAs

Sulfur is an essential element in all living organisms. In tRNA molecules, there are many sulfur-containing nucleosides, introduced post-transcriptionally, that function to ensure proper codon recognition or stabilization of tRNA structure, thereby enabling accurate and efficient translation. The biosynthesis of tRNA sulfur modifications involves unique sulfur trafficking systems that are closely related to cellular sulfur metabolism, and “modification enzymes” that incorporate sulfur atoms into tRNA. Herein, recent biochemical and structural characterization of the biosynthesis of sulfur modifications in tRNA is reviewed, with special emphasis on the reaction mechanisms of modification enzymes. It was recently revealed that TtuA/Ncs6-type 2-thiouridylases from thermophilic bacteria/archaea/eukaryotes are oxygen-sensitive iron-sulfur proteins that utilize a quite different mechanism from other 2-thiouridylase subtypes lacking iron-sulfur clusters such as bacterial MnmA. The various reaction mechanisms of RNA sulfurtransferases are also discussed, including tRNA methylthiotransferase MiaB (a radical S-adenosylmethionine-type iron-sulfur enzyme) and other sulfurtransferases involved in both primary and secondary sulfur-containing metabolites

The Effects of Inbreeding on the Survival Time and the Development of Japanese Quail Embryos Cultured in Vitro

本研究は,近親交配が日本ウズラ塔養胚の生存日数と発育に及ぼす影響について検討する目的で,全きょうだい交配によって近交世代を進めた場合の日本ウズラ培養胚の生存日数と発育を無作為交配群と比較して検討した. 材料は当研究室で無作為交配によって維持している閉鎖集団を起源とする近交群と無作為交配群である. 胚の培養はプラスチックラップを用い,38.0°,39.5°,35.0℃の培養温度のチャンバー内で行なった. なお,チャンバー内の湿度はいずれの場合も100%とした. 得られた結果は要約すると,以下の通りである. 1.本実験では,まず胚の最適な培養開始時期について検討した. その結果,胚の最適な培養開始時期は孵卵後2.5日目であることが明らかとなった. そこで,以後の実験ではすべて孵卵後2.5日目に培養を開始した. 2,いずれの培養温度条件下においても,近交群での培養胚の生存日数は近交世代に伴い減少し,無作為交配群に比較して短くなることが認められた. 両群間の生存日数の差異は培養温度38.0℃で最も著しかった. 3.いずれの培養温度条件下においても,近交群での培養胚の発育は無作為交配群の場合に比較して全般にわたって遅延がみられ,またその発育遅延はすでに培養開始時においても認められた. 4.以上の結果から,近交群における培養胚の生存日数の減少と発育の遅延はポリジーンのヘテロ性の低下ならびに有害遺伝子のホモ化による胚の活力減退と発育速度の低下に起因したものと考察した

Utility of Distal Forearm DXA as a Screening Tool for Primary Osteoporotic Fragility Fractures of the Distal Radius A Case-Control Study

Background: Osteoporotic fragility fractures frequently occur at the distal part of the radius. This suggests that initial osteoporosis evaluation at this site may inform screening and treatment to prevent additional fractures. The purpose of this study was to investigate the utility of distal forearm dual x-ray absorptiometry (DXA) as a screening tool to assess the risk of fragility fractures at the distal part of the radius. Methods: This retrospective, case-control study included postmenopausal women who had sustained a distal radial fracture (fracture group, n = 110) and postmenopausal women with no history of fracture (control group, n = 95). DXA measurements at the spine, hip, and distal part of the forearm (ultra-distal, mid-distal, and one-third distal sections) were compared between the groups on the basis of bone mineral density (BMD), T-score, and the proportion of patients with a T-score of £–2.5 standard deviations (SD). We also investigated the regional differences on the basis of T-score among the skeletal sites. Furthermore, the reliability of distal forearm DXA measurements was validated by assessing the statistical correlation (r) with volumetric BMD by computed tomography (CT). Results: Compared with the control group, the fracture group showed significantly lower BMD and T-scores and higher proportions of patients with a T-score of £–2.5 SD at the ultra-distal, mid-distal, and one-third distal forearm; however, the spine and hip measurements did not differ significantly between the 2 groups. With respect to regional differences, in the fracture group, T-scores were significantly lower and the proportions of patients with a T-score of £–2.5 SD were significantly higher for the 3 distal forearm sites compared with the spine and hip. DXA measurements at all 3 of the distal forearm regions exhibited high correlation with volumetric BMD by CT (r = 0.83 to 0.92). Conclusions: Some postmenopausal women were found to exhibit bone loss preferentially at the distal part of the radius, which may render them vulnerable to fragility fractures. Forearm DXA for the assessment of local bone loss may demonstrate benefit in screening for those at risk for distal radial fractures and facilitate the early identification of patients who require intervention for osteoporosis. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.Miyamura S., Kuriyama K., Ebina K., et al. Utility of Distal Forearm DXA as a Screening Tool for Primary Osteoporotic Fragility Fractures of the Distal Radius A Case-Control Study. JBJS Open Access 5, E0036 (2020); https://doi.org/10.2106/JBJS.OA.19.00036

Pseudouridine at position 55 in tRNA controls the contents of other modified nucleotides for low-temperature adaptation in the extreme-thermophilic eubacterium Thermus thermophilus

Pseudouridine at position 55 (Ψ55) in eubacterial tRNA is produced by TruB. To clarify the role of the Ψ55 modification, we constructed a truB gene disruptant (ΔtruB) strain of Thermus thermophilus which is an extreme-thermophilic eubacterium. Unexpectedly, the ΔtruB strain exhibited severe growth retardation at 50°C. We assumed that these phenomena might be caused by lack of RNA chaperone activity of TruB, which was previously hypothetically proposed by others. To confirm this idea, we replaced the truB gene in the genome with mutant genes, which express TruB proteins with very weak or no enzymatic activity. However the growth retardation at 50°C was not rescued by these mutant proteins. Nucleoside analysis revealed that Gm18, m5s2U54 and m1A58 in tRNA from the ΔtruB strain were abnormally increased. An in vitro assay using purified tRNA modification enzymes demonstrated that the Ψ55 modification has a negative effect on Gm18 formation by TrmH. These experimental results show that the Ψ55 modification is required for low-temperature adaptation to control other modified. 35S-Met incorporation analysis showed that the protein synthesis activity of the ΔtruB strain was inferior to that of the wild-type strain and that the cold-shock proteins were absence in the ΔtruB cells at 50°C

Chemical and biological approaches to improve the efficiency of homologous recombination in human cells mediated by artificial restriction DNA cutter

A chemistry-based artificial restriction DNA cutter (ARCUT) was recently prepared from Ce(IV)/EDTA complex and a pair of pseudo-complementary peptide nucleic acids. This cutter has freely tunable scission-site and site specificity. In this article, homologous recombination (HR) in human cells was promoted by cutting a substrate DNA with ARCUT, and the efficiency of this bioprocess was optimized by various chemical and biological approaches. Of two kinds of terminal structure formed by ARCUT, 3′-overhang termini provided by 1.7-fold higher efficiency than 5′-overhang termini. A longer homology length (e.g. 698 bp) was about 2-fold more favorable than shorter one (e.g. 100 bp). When the cell cycle was synchronized to G2/M phase with nocodazole, the HR was promoted by about 2-fold. Repression of the NHEJ-relevant proteins Ku70 and Ku80 by siRNA increased the efficiency by 2- to 3-fold. It was indicated that appropriate combination of all these chemical and biological approaches should be very effective to promote ARCUT-mediated HR in human cells

モウサイカンチュウ ノ チョウリュウドウ ヘリウム ノ ネツ デンタツ 2

We have measured the heat transfer in superfluid helium in a glass capillary tube. The vortex viscosity calculated from pressure difference across the tube was linear to L_0^ in the range 15ddd and L_0d^2,we could evaluate the vortex-wall interaction parameter ξ\u27 and ξ

Cell-to-Cell Transformation in Escherichia coli: A Novel Type of Natural Transformation Involving Cell-Derived DNA and a Putative Promoting Pheromone

Escherichia coli is not assumed to be naturally transformable. However, several recent reports have shown that E. coli can express modest genetic competence in certain conditions that may arise in its environment. We have shown previously that spontaneous lateral transfer of non-conjugative plasmids occurs in a colony biofilm of mixed E. coli strains (a set of a donor strain harbouring a plasmid and a plasmid-free recipient strain). In this study, with high-frequency combinations of strains and a plasmid, we constructed the same lateral plasmid transfer system in liquid culture. Using this system, we demonstrated that this lateral plasmid transfer was DNase-sensitive, indicating that it is a kind of transformation in which DNase-accessible extracellular naked DNA is essential. However, this transformation did not occur with purified plasmid DNA and required a direct supply of plasmid from co-existing donor cells. Based on this feature, we have termed this transformation type as ‘cell-to-cell transformation’. Analyses using medium conditioned with the high-frequency strain revealed that this strain released a certain factor(s) that promoted cell-to-cell transformation and arrested growth of the other strains. This factor is heat-labile and protease-sensitive, and its roughly estimated molecular mass was between ∼9 kDa and ∼30 kDa, indicating that it is a polypeptide factor. Interestingly, this factor was effective even when the conditioned medium was diluted 10–5–10–6, suggesting that it acts like a pheromone with high bioactivity. Based on these results, we propose that cell-to-cell transformation is a novel natural transformation mechanism in E. coli that requires cell-derived DNA and is promoted by a peptide pheromone. This is the first evidence that suggests the existence of a peptide pheromone-regulated transformation mechanism in E. coli and in Gram-negative bacteria