A primordial noble gas component discovered in the Ryugu asteroid and its implications

Ryugu is the C-type asteroid from which material was brought to Earth by the Hayabusa2 mission. A number of individual grains and fine-grained samples analysed so far for noble gases have indicated that solar wind and planetary (known as P1) noble gases are present in Ryugu samples with concentrations higher than those observed in CIs, suggesting the former to be more primitive compared to the latter. Here we present results of analyses of three fine-grained samples from Ryugu, in one of which Xe concentration is an order of magnitude higher than determined so far in other samples from Ryugu. Isotopically, this Xe resembles P1, but with a much stronger isotopic fractionation relative to solar wind and significantly lower 36Ar/132Xe ratio than in P1. This previously unknown primordial noble gas component (here termed P7) provides clues to constrain how the solar composition was fractionated to form the planetary components

A history of mild shocks experienced by the regolith particles on hydrated asteroid Ryugu

Micrometeorites, a possible major source of Earth’s water, are thought to form from explosive dispersal of hydrated chondritic materials during impact events on their parental asteroids. However, this provenance and formation mechanism have yet to be directly confirmed using asteroid returned samples. Here, we report evidence of mild shock metamorphism in the surface particles of asteroid Ryugu based on electron microscopy. All particles are dominated by phyllosilicates but lack dehydration textures, which are indicative of shock-heating temperatures below ~500 °C. Microfault-like textures associated with extensively shock-deformed framboidal magnetites and a high-pressure polymorph of Fe–Cr–sulfide have been identified. These findings indicate that the average peak pressure was -2 GPa. The vast majority of ejecta formed during impact on Ryugu-like asteroids would be hydrated materials, larger than a millimetre, originating far from the impact point. These characteristics are inconsistent with current micrometeorite production models, and consequently, a new formation mechanism is required

Oxygen isotope evidence from Ryugu samples for early water delivery to Earth by CI chondrites

The delivery of water to the inner Solar System, including Earth, is still a debated topic. A preferential role for hydrated asteroids in this process is supported by isotopic measurements. Carbonaceous chondrite (CC) meteorites represent our main source of information about these volatile-rich asteroids. However, the destruction of weaker materials during atmospheric entry creates a bias in our CC data. The return of surface materials from the C-type asteroid 162173 Ryugu by the Hayabusa2 spacecraft provides a unique opportunity to study high-porosity, low-density, primitive materials, unrepresented in the meteorite record. We measured the bulk oxygen isotope composition from four Ryugu particles and show that they most closely resemble the rare CI (CC Ivuna-type) chondrites, but with some differences that we attribute to the terrestrial contamination of the CI meteorites. We suggest that CI-related material is widespread among carbonaceous asteroids and a more important source of Earth’s water and other volatiles than its limited presence in our meteoritic collection indicates

A pristine record of outer Solar System materials from asteroid Ryugu’s returned sample

Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition

A Multisensory Program for Teaching English Phonological Awareness Skills to Japanese Children

本研究では,日本語母語者の音韻処理特徴に応じた年少児向けの英語音韻習得方法の効果を検討した。本研究で検討したのは,英語の音素を表現する手段として文字,絵,動作を学習し,それらの多感覚的な手段を用いて英単語の音声を分析したり,音素から英単語の音声に統合したりする活動を行うという方法(多感覚音韻認識プログラム)であった。多感覚音韻認識プログラムに基づいた活動を継続的に行った多感覚認識I(5〜6歳児35名),メディアを用いて,英語の音素や単語の発声,英語の歌の活動を行った音声体験(4〜6歳児26名),音声体験プログラムに続けて,多感覚音韻認識プログラムに基づいた活動を行った多感覚認識II(4〜6歳児22名),同年齢の統制について,英語音韻習得能力の指標となる3つの課題の成績を比較した。その結果,1)多感覚認識IIは,他の群よりも音韻認識課題の成績が良かった。2)多感覚認識I,多感覚認識IIは,統制よりも,また,多感覚認識IIは,音声体験よりも,1音節反復課題の成績が良かった。3)多感覚認識IIは,他の群より非単語反復課題の正答数や音節再生数が多かった。In the present study, a series of activities was designed in an attempt to improve English phonological learning skills of Japanese children. The activities included analyzing English words into phonemes and blending phonemes into English words using letters, pictures, and actions representing phonemes. The following conditions were compared: (a) Phonological Training I, in which thirty-five 5- to 6-year-olds participated in the activities; (b) Sound Experience, in which twenty-six 4- to 6-year-olds listened to DVDs of English sounds; (c) Phonological Training II, in which twenty-two 4-to 6-year-olds listened to the DVDs and then participated in the activities; and (d) Control, in which 69 children (mean age 6 years 8 months) engaged in no activity related to the program. The children in both of the Phonological Training groups were better at repeating 1-syllable English words out loud than were the children in the Control condition. The children in the Phonological Training II group were better at recognizing phonemes of English words and made more correct responses on English non-word repetition tasks than the children in the other 3 conditions.日本教育心理学会2010年度優秀論文賞受賞論

Crystallization and preliminary crystallographic analysis of p40phox, a regulatory subunit of NADPH oxidase

Human p40phox was expressed, purified and crystallized. Diffraction data were collected to a resolution of 3.0 Å

英語の多感覚音韻認識プログラムが日本人幼児の英語音韻習得に及ぼす効果

本研究では,日本語母語者の音韻処理特徴に応じた年少児向けの英語音韻習得方法の効果を検討した。本研究で検討したのは,英語の音素を表現する手段として文字,絵,動作を学習し,それらの多感覚的な手段を用いて英単語の音声を分析したり,音素から英単語の音声に統合したりする活動を行うという方法(多感覚音韻認識プログラム)であった。多感覚音韻認識プログラムに基づいた活動を継続的に行った多感覚認識I(5〜6歳児35名),メディアを用いて,英語の音素や単語の発声,英語の歌の活動を行った音声体験(4〜6歳児26名),音声体験プログラムに続けて,多感覚音韻認識プログラムに基づいた活動を行った多感覚認識II(4〜6歳児22名),同年齢の統制について,英語音韻習得能力の指標となる3つの課題の成績を比較した。その結果,1)多感覚認識IIは,他の群よりも音韻認識課題の成績が良かった。2)多感覚認識I,多感覚認識IIは,統制よりも,また,多感覚認識IIは,音声体験よりも,1音節反復課題の成績が良かった。3)多感覚認識IIは,他の群より非単語反復課題の正答数や音節再生数が多かった。In the present study, a series of activities was designed in an attempt to improve English phonological learning skills of Japanese children. The activities included analyzing English words into phonemes and blending phonemes into English words using letters, pictures, and actions representing phonemes. The following conditions were compared: (a) Phonological Training I, in which thirty-five 5- to 6-year-olds participated in the activities; (b) Sound Experience, in which twenty-six 4- to 6-year-olds listened to DVDs of English sounds; (c) Phonological Training II, in which twenty-two 4-to 6-year-olds listened to the DVDs and then participated in the activities; and (d) Control, in which 69 children (mean age 6 years 8 months) engaged in no activity related to the program. The children in both of the Phonological Training groups were better at repeating 1-syllable English words out loud than were the children in the Control condition. The children in the Phonological Training II group were better at recognizing phonemes of English words and made more correct responses on English non-word repetition tasks than the children in the other 3 conditions.日本教育心理学会2010年度優秀論文賞受賞論

Lacrimo-Auriculo-Dento-Digital Syndrome Is Caused by Reduced Activity of the Fibroblast Growth Factor 10 (FGF10)-FGF Receptor 2 Signaling Pathway▿

Lacrimo-auriculo-dento-digital (LADD) syndrome is characterized by abnormalities in lacrimal and salivary glands, in teeth, and in the distal limbs. Genetic studies have implicated heterozygous mutations in fibroblast growth factor 10 (FGF10) and in FGF receptor 2 (FGFR2) in LADD syndrome. However, it is not clear whether LADD syndrome mutations (LADD mutations) are gain- or loss-of-function mutations. In order to reveal the molecular mechanism underlying LADD syndrome, we have compared the biological properties of FGF10 LADD and FGFR2 LADD mutants to the activities of their normal counterparts. These experiments show that the biological activities of three different FGF10 LADD mutants are severely impaired by different mechanisms. Moreover, haploinsufficiency caused by defective FGF10 mutants leads to LADD syndrome. We also demonstrate that the tyrosine kinase activities of FGFR2 LADD mutants expressed in transfected cells are strongly compromised. Since tyrosine kinase activity is stimulated by ligand-induced receptor dimerization, FGFR2 LADD mutants may also exert a dominant inhibitory effect on signaling via wild-type FGFR2 expressed in the same cell. These experiments underscore the importance of signal strength in mediating biological responses and that relatively small changes in receptor signaling may influence the outcome of developmental processes in cells or organs that do not possess redundant signaling pathway

Crystal Structure of the C-Terminal Globular Domain of Oligosaccharyltransferase from <i>Archaeoglobus fulgidus</i> at 1.75 Å Resolution

Protein N-glycosylation occurs in the three domains of life. Oligosaccharyltransferase (OST) transfers glycan to asparagine in the N-glycosylation sequon. The catalytic subunit of OST is called STT3 in eukaryotes, AglB in archaea, and PglB in eubacteria. The genome of a hyperthermophilic archaeon, <i>Archaeoglobus fulgidus</i>, encodes three AglB paralogs. Two of them are the shortest AglBs across all domains of life. We determined the crystal structure of the C-terminal globular domain of the smallest AglB to identify the minimal structural unit. The <i>Archaeoglobus</i> AglB lacked a β-barrel-like structure, which had been found in other AglB and PglB structures. In agreement, the deletion in a larger <i>Pyrococcus</i> AglB confirmed its dispensability for the activity. By contrast, the <i>Archaeoglobus</i> AglB contains a kinked helix bearing a conserved motif, called DK/MI motif. The lysine and isoleucine residues in the motif participate in the Ser/Thr recognition in the sequon. The <i>Archaeoglobus</i> AglB structure revealed that the kinked helix contained an unexpected insertion. A revised sequence alignment based on this finding identified a variant type of the DK motif with the insertion. A mutagenesis study of the <i>Archaeoglobus</i> AglB confirmed the contribution of this particular type of the DK motif to the activity. When taken together with our previous results, this study defined the classification of OST: one group consisting of eukaryotes and most archaea possesses the DK-type Ser/Thr pocket, and the other group consisting of eubacteria and the remaining archaea possesses the MI-type Ser/Thr pocket. This classification provides a useful framework for OST studies