Masaca's Blog 2

独り言・日記・愚痴・戯言・備忘録・・・。なんとでもお呼び下され(笑)。

Science News | June 27(3), 2008

2008-06-27 22:31:47 | Science News
  • 時事ドットコム：最も原始的な両生類化石＝３億８０００万年前、ラトビアで－欧州チーム
  • Ventastega curonica and the origin of tetrapod morphology.
    Per E. Ahlberg, Jennifer A. Clack, Erivns Lukševics, Henning Blom, Ivars Zupinš.
    Nature 453, 1199-1204 (2008) | doi:10.1038/nature06991
    The gap in our understanding of the evolutionary transition from fish to tetrapod is beginning to close thanks to the discovery of new intermediate forms such as Tiktaalik roseae. Here we narrow it further by presenting the skull, exceptionally preserved braincase, shoulder girdle and partial pelvis of Ventastega curonica from the Late Devonian of Latvia, a transitional intermediate form between the 'elpistostegids' Panderichthys and Tiktaalik and the Devonian tetrapods (limbed vertebrates) Acanthostega and Ichthyostega. Ventastega is the most primitive Devonian tetrapod represented by extensive remains, and casts light on a part of the phylogeny otherwise only represented by fragmentary taxa: it illuminates the origin of principal tetrapod structures and the extent of morphological diversity among the transitional forms.
    　# 日本の最古は2億4千万年前…世界最古は3億8千万年前…何なんだ、この1億2千万年の差は…
  • 地中海のサメ、過去２００年で９７％以上減少 : 科学 : YOMIURI ONLINE（読売新聞）
  • NEW SCIENTIFIC STUDY SHOWS WORRYING DECLINE IN THE MED'S TOP PREDATORS - LENFEST OCEAN PROGRAM (PDF)
  • SHARK DECLINES IN THE MEDITERRANEAN SEA - LENFEST OCEAN PROGRAM RESEARCH SERIES
  • Loss of Large Predatory Sharks from the Mediterranean Sea.
    FRANCESCO FERRETTI, RANSOM A. MYERS, FABRIZIO SERENA, HEIKE K. LOTZE.
    Conservation Biology, OnlineEarly Articles | doi:10.1111/j.1523-1739.2008.00938.x
    Evidence for severe declines in large predatory fishes is increasing around the world. Because of its long history of intense fishing, the Mediterranean Sea offers a unique perspective on fish population declines over historical timescales. We used a diverse set of records dating back to the early 19th and mid 20th century to reconstruct long-term population trends of large predatory sharks in the northwestern Mediterranean Sea. We compiled 9 time series of abundance indices from commercial and recreational fishery landings, scientific surveys, and sighting records. Generalized linear models were used to extract instantaneous rates of change from each data set, and a meta-analysis was conducted to compare population trends. Only 5 of the 20 species we considered had sufficient records for analysis. Hammerhead (Sphyrna spp.), blue (Prionace glauca), mackerel (Isurus oxyrinchus and Lamna nasus), and thresher sharks (Alopias vulpinus) declined between 96 and 99.99% relative to their former abundance. According to World Conservation Union (IUCN) criteria, these species would be considered critically endangered. So far, the lack of quantitative population assessments has impeded shark conservation in the Mediterranean Sea. Our study fills this critical information gap, suggesting that current levels of exploitation put large sharks at risk of extinction in the Mediterranean Sea. Possible ecosystem effects of these losses involve a disruption of top-down control and a release of midlevel consumers.
    　# 97～99%も減ったって？…じゃぁ、元々どれだけいたんだって話だわな
    　# ちゅうかさぁ、この論文探すのにエライ苦労したがな…なんと、記事をベタコピーしただけのエントリーの多いことか…
  • ｉＰＳ細胞：京大と理研連携　科技会議が推進策 - 毎日ｊｐ(毎日新聞)
    　# まぁ、理研神戸はほとんど京大のために建ったようなものだからな…
  • 燃料電池：家庭用の名称「エネファーム」に統一 - 毎日ｊｐ(毎日新聞)
    　# 「エネファーム」…変換したらさっそく「絵寝ファーム」になったがな
    　# 「エコジョーズ」みたいな名前で何かと勘違いしそう…
  • 文科省：主要断層帯、再調査へ　「未知・無警戒」探る - 毎日ｊｐ(毎日新聞)
    　# 断層って、調べても調べても調べきらないような気がするのは気のせいですか？
  • カルシウム摂取量と腰椎骨折との関連について　-- 概要 --
  • Calcium intake and the 10-year incidence of self-reported vertebral fractures in women and men: The Japan Public Health Centre-based Prospective Study.
    Kazutoshi Nakamura, Norie Kurahashi, Junko Ishihara, Manami Inoue, Shoichiro Tsugane, the Japan Public Health Centre-based Prospective Study Group.
    British Journal of Nutrition, First View article | doi:10.1017/S0007114508993533
    The purpose of this study was to evaluate the effect of low Ca intake on the 10-year incidence of vertebral fractures in cohorts I and II of the Japan Public Health Centre-based Prospective Study. The baseline studies were conducted in 1990–1994, with the follow-up studies conducted after 10 years. We analysed 33 970 subjects aged 40–59 years in cohort I and 41 664 subjects aged 40–69 years in cohort II. At baseline, the intake of Ca was assessed as a predictor, using validated FFQ. A meta-analysis was performed to estimate a summary relative risk (RR) for the two cohort studies. The 10-year cumulative incidences of self-reported vertebral fractures were 0·38 % for cohort I and 0·56 % for cohort II. In women, lower Ca intake was associated with a higher incidence of vertebral fractures (P for trend = 0·001), with the lowest quartile of Ca intake having a significantly higher incidence (0·89/1000 persons per year or RR 2·10 (95 % CI 1·25, 3·55)) than that (0·42/1000 persons per year) of the highest. In addition, the RR calculated using energy-adjusted Ca intake (by the residual method) as an outcome was 1·92 (95 % CI 1·28, 2·88). However, no such association was observed in men. An increase of Ca intake should be considered as a preventive strategy for vertebral fractures in peri- and post-menopausal women with a low Ca intake.
    　# ま、いつも通り、女性はカルシウムをたくさん摂りましょうって話です
  • アフリカの熱帯魚：右利きは左利きを好む　異型交配で確認 - 毎日ｊｐ(毎日新聞)
  • Evidence of disassortative mating in a Tanganyikan cichlid fish and its role in the maintenance of intrapopulation dimorphism.
    Tetsumi Takahashi, Michio Hori.
    Biology Letters, FirstCite | doi:10.1098/rsbl.2008.0244
    Morphological dimorphism in the mouth-opening direction (‘lefty’ versus ‘righty’) has been documented in several fish species. It has been suggested that this deflection is heritable in a Mendelian one-locus, two-allele fashion. Several population models have demonstrated that lateral dimorphism is maintained by negative frequency-dependent selection, resulting from interactions between predator and prey species. However, other mechanisms for the maintenance of lateral dimorphism have not yet been tested. Here, we found that the scale-eating cichlid fish Perissodus microlepis exhibited disassortative mating, in which reproductive pairings between lefties and righties occurred at higher than expected frequency (p<0.001). A previous study reported that a lefty–righty pairing produces a 1:1 ratio of lefty:righty young, suggesting that disassortative mating contributes to the maintenance of lateral dimorphism. A combination of disassortative mating and negative frequency-dependent selection may stabilize lateral dimorphism more than would a single mechanism.
    　# 右利き・左利きに遺伝的背景があるんだろうか？
  • 卵子を使わず万能細胞をつくる | Japanese JoongAngIlbo | 中央日報
    　# 韓国でiPS細胞…世界３番目…「韓国動物繁殖学会学術大会および第４回韓日共同シンポジウムで発表」…
    　# 「すでに国内外特許を出願」？…「米日研究チームが適用した方法よりも優れた方法を使い、幹細胞抽出効率は５倍以上に高まった」…
    　# ベクターが新しいってことなのか？…けど、基本的に特許は成立せんわな
  • バイオテクノロジー：実用化へ新戦略まとめる…官民会議 - 毎日ｊｐ(毎日新聞)
    　# 政府がカタカナ語を多用すると安っぽく感じるのは気のせいですか？
  • 2008年6月25日「『目に見える研究拠点』のすべり出しは」　サイエンスポータルレビュー　科学技術 全て伝えます SciencePortal
    　# 形を変えようが何だろうが、出てくる問題点はいつも似たり寄ったり…つまり、根本的には何も解決していないってことだよね
  • 2008年6月27日「震源断層の長さ30キロ 地震動重力加速度の4倍超」　サイエンスポータル編集ニュース　科学技術 全て伝えます サイエンスポータル / SciencePortal
  • 平成２０年（２００８年）岩手・宮城内陸地震に関する情報
    　# 「1G＝重力加速度980ガル」？…ほほぉ、1 Gal = 1 cm/s2 = 0.01 m/s2だったのね

    • Science News | June 27(2), 2008

    2008-06-27 22:31:37 | Science News
  • Biotechnology Japan | 海外重要発表、米Medical College of Georgia、HLA-Gダイマーが、免疫応答を制御すると発表
  • Modulation of dendritic cell differentiation by HLA-G and ILT4 requires the IL-6―STAT3 signaling pathway.
    Siyuan Liang, Vladimir Ristich, Hisashi Arase, Jean Dausset, Edgardo D. Carosella, Anatolij Horuzsko.
    PNAS 105, 8357-8362 (2008) | doi:10.1073/pnas.0803341105
    The expression of Ig-like transcript (ILT) inhibitory receptors is a characteristic of tolerogenic dendritic cells (DCs). However, the mechanisms of modulation of DCs via ILT receptors remain poorly defined. HLA-G is a preferential ligand for several ILTs. Recently, we demonstrated that triggering of ILT4 by HLA-G1 inhibits maturation of human monocyte-derived conventional DCs and murine DCs from ILT4 transgenic mice, resulting in diminished expression of MHC class II molecules, CD80 and CD86 costimulatory molecules, and prolongation of skin allograft survival. Different isoforms of HLA-G have diverse effects on the efficiency to induce ILT-mediated signaling. In this work, we show that HLA-G1 tetrameric complex and HLA-G5 dimer, but not HLA-G5 monomer, induce strong ILT-mediated signaling. We determined that the arrest of maturation of ILT4-positive DCs by HLA-G ligands involves the IL-6 signaling pathway and STAT3 activation. Ligation of ILT4 with HLA-G on DCs results in recruitment of SHP-1 and SHP-2 protein tyrosine phosphatases. We propose a model where SHP-2 and the IL-6–STAT3 signaling pathway play critical roles in the modulation of DC differentiation by ILT4 and HLA-G.
    　# HLA-G1は四量体、HLA-G5は二量体でILT媒介シグナリングを強く誘導するそうな
  • Biotechnology Japan | 岡崎統合バイオサイエンスセンターの岡村康司教授ら、細胞のイオン透過を解析、単一サブユニットで機能する電位依存性プロトンチャンネルは2量体で発現
  • Multimeric nature of voltage-gated proton channels.
    Hans P. Koch, Tatsuki Kurokawa, Yoshifumi Okochi, Mari Sasaki, Yasushi Okamura, H. Peter Larsson.
    Proc. Natl. Acad. Sci. USA, Early Edition | doi:10.1073/pnas.0801553105
    Voltage-gated potassium channels are comprised of four subunits, and each subunit has a pore domain and a voltage-sensing domain (VSD). The four pore domains assemble to form one single central pore, and the four individual VSDs control the gate of the pore. Recently, a family of voltage-gated proton channels, such as HV or voltage sensor only protein (VSOP), was discovered that contain a single VSD but no pore domain. It has been assumed that VSOP channels are monomeric and contain a single VSD that functions as both the VSD and the pore domain. It remains unclear, however, how a protein that contains only a VSD and no pore domain can conduct ions. Using fluorescence measurements and immunoprecipitation techniques, we show here that VSOP channels are expressed as multimeric channels. Further, FRET experiments on constructs with covalently linked subunits show that VSOP channels are dimers. Truncation of the cytoplasmic regions of VSOP reduced the dimerization, suggesting that the dimerization is caused mainly by cytoplasmic protein–protein interactions. However, these N terminus- and C terminus-deleted channels displayed large proton currents. Therefore, we conclude that even though VSOP channels are expressed mainly as dimers in the cell membrane, single VSOP subunits could function independently as proton channels.
    　# 一瞬、YOさんと見間違えた…
    　# 「VSOP」＝「voltage sensor only protein」って、絶対狙ってるよね
  • 時事ドットコム：火星北半球に大楕円クレーター＝冥王星程度の天体衝突か－米研究チーム
  • 初期の火星に天体衝突　英科学誌に３論文 - MSN産経ニュース
  • The Borealis basin and the origin of the martian crustal dichotomy.
    Jeffrey C. Andrews-Hanna, Maria T. Zuber, W. Bruce Banerdt.
    Nature 453, 1212-1215 (2008) | doi:10.1038/nature07011
    The most prominent feature on the surface of Mars is the near-hemispheric dichotomy between the southern highlands and northern lowlands. The root of this dichotomy is a change in crustal thickness along an apparently irregular boundary, which can be traced around the planet, except where it is presumably buried beneath the Tharsis volcanic rise. The isostatic compensation of these distinct provinces and the ancient population of impact craters buried beneath the young lowlands surface suggest that the dichotomy is one of the most ancient features on the planet. However, the origin of this dichotomy has remained uncertain, with little evidence to distinguish between the suggested causes: a giant impact or mantle convection/overturn. Here we use the gravity and topography of Mars to constrain the location of the dichotomy boundary beneath Tharsis, taking advantage of the different modes of compensation for Tharsis and the dichotomy to separate their effects. We find that the dichotomy boundary along its entire path around the planet is accurately fitted by an ellipse measuring approximately 10,600 by 8,500 km, centred at 67° N, 208° E. We suggest that the elliptical nature of the crustal dichotomy is most simply explained by a giant impact, representing the largest such structure thus far identified in the Solar System.
  • Mega-impact formation of the Mars hemispheric dichotomy.
    Margarita M. Marinova, Oded Aharonson, Erik Asphaug.
    Nature 453, 1216-1219 (2008) | doi:10.1038/nature07070
    The Mars hemispheric dichotomy is expressed as a dramatic difference in elevation, crustal thickness and crater density between the southern highlands and northern lowlands (which cover ∼42% of the surface). Despite the prominence of the dichotomy, its origin has remained enigmatic and models for its formation largely untested. Endogenic degree-1 convection models with north–south asymmetry are incomplete in that they are restricted to simulating only mantle dynamics and they neglect crustal evolution, whereas exogenic multiple impact events are statistically unlikely to concentrate in one hemisphere. A single mega-impact of the requisite size has not previously been modelled. However, it has been hypothesized that such an event could obliterate the evidence of its occurrence by completely covering the surface with melt or catastrophically disrupting the planet. Here we present a set of single-impact initial conditions by which a large impactor can produce features consistent with the observed dichotomy's crustal structure and persistence. Using three-dimensional hydrodynamic simulations, large variations are predicted in post-impact states depending on impact energy, velocity and, importantly, impact angle, with trends more pronounced or unseen in commonly studied smaller impacts. For impact energies of ∼(3–6) × 1029 J, at low impact velocities (6–10 km s-1) and oblique impact angles (30–60°), the resulting crustal removal boundary is similar in size and ellipticity to the observed characteristics of the lowlands basin. Under these conditions, the melt distribution is largely contained within the area of impact and thus does not erase the evidence of the impact's occurrence. The antiquity of the dichotomy is consistent with the contemporaneous presence of impactors of diameter 1,600–2,700 km in Mars-crossing orbits, and the impact angle is consistent with the expected distribution.
  • Implications of an impact origin for the martian hemispheric dichotomy.
    F. Nimmo, S. D. Hart, D. G. Korycansky, C. B. Agnor.
    Nature 453, 1220-1223 (2008) | doi:10.1038/nature07025
    The observation that one hemisphere of Mars is lower and has a thinner crust than the other (the 'martian hemispheric dichotomy') has been a puzzle for 30 years. The dichotomy may have arisen as a result of internal mechanisms such as convection. Alternatively, it may have been caused by one or several giant impacts, but quantitative tests of the impact hypothesis have not been published. Here we use a high-resolution, two-dimensional, axially symmetric hydrocode to model vertical impacts over a range of parameters appropriate to early Mars. We propose that the impact model, in addition to excavating a crustal cavity of the correct size, explains two other observations. First, crustal disruption at the impact antipode is probably responsible for the observed antipodal decline in magnetic field strength. Second, the impact-generated melt forming the northern lowlands crust is predicted to derive from a deep, depleted mantle source. This prediction is consistent with characteristics of martian shergottite meteorites and suggests a dichotomy formation time ∼100 Myr after martian accretion, comparable to that of the Moon-forming impact on Earth.
    　# 何と巨大な衝突…

    • Science News | June 27(1), 2008

    2008-06-27 22:31:25 | Science News
  • 過度の携帯電話利用が若者の睡眠に影響――研究者が報告 - ITmedia News
  • Excessive mobile phone use affects sleep in teens
  • Teens & Sleep Loss - Sleep Education.com
    　# 携帯電話の使いすぎはよろしくないと…これって若者に限った話じゃないと思うんだが…
  • プラズマで飛ぶ空飛ぶ円盤、米研究者が設計 - ITmedia News
  • University of Florida News - University of Florida professor designs plasma-propelled flying saucer
    　# 特許出願かぁ…大変なんだよなぁ…
  • GenomeWeb News: Children's Oncology Group to Use Helicos Sequencing Tech for Sarcoma Study
  • Helicos Biosciences Corporation - Helicos BioSciences Announces Collaboration with Children's Oncology Group to Elucidate Genomic Signatures in Ewing's Sarcoma
    　# 第三世代シーケンサーはもう既に動き始めています
  • asahi.com（朝日新聞社）：オゾン層回復→南極は温暖化？　国際グループ予測 - サイエンス
  • The Impact of Stratospheric Ozone Recovery on the Southern Hemisphere Westerly Jet.
    S.-W. Son, L. M. Polvani, D. W. Waugh, H. Akiyoshi, R. Garcia, D. Kinnison, S. Pawson, E. Rozanov, T. G. Shepherd, K. Shibata.
    Science 320, 1486-1489 (2008) | DOI: 10.1126/science.1155939
    In the past several decades, the tropospheric westerly winds in the Southern Hemisphere have been observed to accelerate on the poleward side of the surface wind maximum. This has been attributed to the combined anthropogenic effects of increasing greenhouse gases and decreasing stratospheric ozone and is predicted to continue by the Intergovernmental Panel on Climate Change/Fourth Assessment Report (IPCC/AR4) models. In this paper, the predictions of the Chemistry-Climate Model Validation (CCMVal) models are examined: Unlike the AR4 models, the CCMVal models have a fully interactive stratospheric chemistry. Owing to the expected disappearance of the ozone hole in the first half of the 21st century, the CCMVal models predict that the tropospheric westerlies in Southern Hemisphere summer will be decelerated, on the poleward side, in contrast with the prediction of most IPCC/AR4 models.
    　# オゾンホールによる紫外線増加という一面だけを見ていてはいけないということですね…
    　# ねぇ、科学記事って、古くても見つけたものを適当に書けばいいの？
  • asahi.com（朝日新聞社）：「きぼう」いっぱい 宇宙飛行士の応募、過去最多 - サイエンス
  • ３２１倍の狭き門、宇宙飛行士募集に過去最多の９６３人 : 科学 : YOMIURI ONLINE（読売新聞）
  • ＪＡＸＡ：宇宙飛行士応募、過去最高の９６３人　シャトル効果？ - 毎日ｊｐ(毎日新聞)
    　# ある意味、応募できるだけでも羨ましく思える自分は、それだけ歳をとってしまったということか…
  • asahi.com（朝日新聞社）：人工ブラックホール、地球は無事か　学者「心配ご無用」 - サイエンス
  • Earth Will Survive After All, Physicists Say - NYTimes.com
  • The safety of the LHC
    　# 仮に大丈夫じゃなかったとしたら、ミニブラックホールが出来た瞬間に地球上の全てがそこに吸い込まれるんだろうか
  • 早大と東京農工大が共同大学院創設…「先端健康科学」を研究 : 科学 : YOMIURI ONLINE（読売新聞）
  • 早稲田大学｜これまでの記事｜プレスリリース｜東京農工大学との大学間交流に関する包括協定ならびに共同大学院創設について
    　# 「先端健康科学」って何だ？…なんか「健康」に関係していれば何でもアリみたいです
  • 学芸員養成、履修増加へ　博物館機能の強化狙う　文科省 - MSN産経ニュース
    　# 学芸員って、資格を取るまではいいけど、就職先ってあるの？
  • 万能細胞の推進策決定へ - MSN産経ニュース
    　# 面白い研究課題も国策化した途端に何だかなぁって思えるのは何故だ？
  • 残飯や廃プラスチックなどを使う小型「ゴミ発電機」、米軍基地で稼働中 | WIRED VISION
  • Tactical biorefineries go to Iraq | Cleantech.com
    　# 効率云々を考えて文句を言っているよりも、まずやってみることの方が重要なんだよな
  • Biotechnology Japan | 記者発表、独立行政法人 理化学研究所、蛍光タンパク質「ドロンパ」のフォトクロミズムの分子機構を解明へ
  • Biotechnology Japan | 理研など、蛍光たんぱく質Dronpaのフォトクロミズム機構解明、発色団の可動性が蛍光効率を決定
  • 蛍光タンパク質「ドロンパ」のフォトクロミズムの分子機構を解明へ | 独立行政法人 理化学研究所プレスリリース
  • Light-dependent regulation of structural flexibility in a photochromic fluorescent protein.
    Hideaki Mizuno, Tapas Kumar Mal, Markus Wälchli, Akihiro Kikuchi, Takashi Fukano, Ryoko Ando, Jeyaraman Jeyakanthan, Junichiro Taka, Yoshitsugu Shiro, Mitsuhiko Ikura, Atsushi Miyawaki.
    Proc. Natl. Acad. Sci. USA, Early Edition | doi:10.1073/pnas.0709599105
    The structural basis for the photochromism in the fluorescent protein Dronpa is poorly understood, because the crystal structures of the bright state of the protein did not provide an answer to the mechanism of the photochromism, and structural determination of the dark state has been elusive. We performed NMR analyses of Dronpa in solution at ambient temperatures to find structural flexibility of the protein in the dark state. Light-induced changes in interactions between the chromophore and β-barrel are responsible for switching between the two states. In the bright state, the apex of the chromophore tethers to the barrel by a hydrogen bond, and an imidazole ring protruding from the barrel stabilizes the plane of the chromophore. These interactions are disrupted by strong illumination with blue light, and the chromophore, together with a part of the β-barrel, becomes flexible, leading to a nonradiative decay process.
    　 # さすが宮脇先生…あいかわらずいい仕事してます
  • Biotechnology Japan | Boston小児病院、Massachusetts総合病院など、心臓の発生にかかわる新たな前駆細胞を発見
  • Epicardial progenitors contribute to the cardiomyocyte lineage in the developing heart.
    Bin Zhou, Qing Ma, Satish Rajagopal, Sean M. Wu, Ibrahim Domian, José Rivera-Feliciano, Dawei Jiang, Alexander von Gise, Sadakatsu Ikeda, Kenneth R. Chien, William T. Pu.
    Nature, Advance online publication | doi:10.1038/nature07060
    The heart is formed from cardiogenic progenitors expressing the transcription factors Nkx2-5 and Isl1. These multipotent progenitors give rise to cardiomyocyte, smooth muscle and endothelial cells, the major lineages of the mature heart. Here we identify a novel cardiogenic precursor marked by expression of the transcription factor Wt1 and located within the epicardium―an epithelial sheet overlying the heart. During normal murine heart development, a subset of these Wt1+ precursors differentiated into fully functional cardiomyocytes. Wt1+ proepicardial cells arose from progenitors that express Nkx2-5 and Isl1, suggesting that they share a developmental origin with multipotent Nkx2-5+ and Isl1+ progenitors. These results identify Wt1+ epicardial cells as previously unrecognized cardiomyocyte progenitors, and lay the foundation for future efforts to harness the cardiogenic potential of these progenitors for cardiac regeneration and repair.
    　# 転写因子Wt1がキーのようです