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…
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…
# 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…
# 「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…
# 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？
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
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？
# 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
# 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？
# 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
# 「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
