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Kasahara M Naruse K Sasaki S Nakatani Y Qu W Ahsan B Yamada T Nagayasu Y Doi K Kasai Y Jindo T Kobayashi D Shimada A Toyoda A Kuroki Y Fujiyama A Sasaki T Shimizu A Asakawa S Shimizu N Hashimoto S Yang J Lee Y Matsushima K Sugano S Sakaizumi M Narita T Ohishi K Haga S Ohta F Nomoto H Nogata K Morishita T Endo T Shin-I T Takeda H Morishita S Kohara Y 《Nature》2007,447(7145):714-719
Teleosts comprise more than half of all vertebrate species and have adapted to a variety of marine and freshwater habitats. Their genome evolution and diversification are important subjects for the understanding of vertebrate evolution. Although draft genome sequences of two pufferfishes have been published, analysis of more fish genomes is desirable. Here we report a high-quality draft genome sequence of a small egg-laying freshwater teleost, medaka (Oryzias latipes). Medaka is native to East Asia and an excellent model system for a wide range of biology, including ecotoxicology, carcinogenesis, sex determination and developmental genetics. In the assembled medaka genome (700 megabases), which is less than half of the zebrafish genome, we predicted 20,141 genes, including approximately 2,900 new genes, using 5'-end serial analysis of gene expression tag information. We found single nucleotide polymorphisms (SNPs) at an average rate of 3.42% between the two inbred strains derived from two regional populations; this is the highest SNP rate seen in any vertebrate species. Analyses based on the dense SNP information show a strict genetic separation of 4 million years (Myr) between the two populations, and suggest that differential selective pressures acted on specific gene categories. Four-way comparisons with the human, pufferfish (Tetraodon), zebrafish and medaka genomes revealed that eight major interchromosomal rearrangements took place in a remarkably short period of approximately 50 Myr after the whole-genome duplication event in the teleost ancestor and afterwards, intriguingly, the medaka genome preserved its ancestral karyotype for more than 300 Myr. 相似文献
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Efforts to reclaim amended and raw bentonite spoils with six plant species (two forbs, three shrubs, and one tree) were evaluated over a 4-year period. Plant species included fourwing saltbush ( Atriplex canescens [Pursh] Nutt.), big sagebrush ( Artemisia tridentata tridentata Nutt.), Rocky Mountain Juniper ( Juniperus scopulorum Sarg.), Russian olive ( Elaeagnus angustifolia L.) common yarrow ( Achillea millifolium L.) and scarlet globemallow ( Sphaeralcea coccinea [Pursh] Rydb.). Spoil treatments included addition of gypsum, sawdust, perlite, straw, and vermiculite; the control treatment was amended. Fourwing saltbush had 52% survival across all spoil treatments, with greatest survival occurring on perlite-treated spoil (80%), followed by gypsum (70%) and vermiculite amendments (70%). Survival of other plant species ranged from 0 to 2% averaged across all treatments after 4 years. No differences in plant survival occurred among amendments when all species were considered. 相似文献
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Lai CW Kim NY Utsunomiya S Roumpos G Deng H Fraser MD Byrnes T Recher P Kumada N Fujisawa T Yamamoto Y 《Nature》2007,450(7169):529-532
The effect of quantum statistics in quantum gases and liquids results in observable collective properties among many-particle systems. One prime example is Bose-Einstein condensation, whose onset in a quantum liquid leads to phenomena such as superfluidity and superconductivity. A Bose-Einstein condensate is generally defined as a macroscopic occupation of a single-particle quantum state, a phenomenon technically referred to as off-diagonal long-range order due to non-vanishing off-diagonal components of the single-particle density matrix. The wavefunction of the condensate is an order parameter whose phase is essential in characterizing the coherence and superfluid phenomena. The long-range spatial coherence leads to the existence of phase-locked multiple condensates in an array of superfluid helium, superconducting Josephson junctions or atomic Bose-Einstein condensates. Under certain circumstances, a quantum phase difference of pi is predicted to develop among weakly coupled Josephson junctions. Such a meta-stable pi-state was discovered in a weak link of superfluid 3He, which is characterized by a 'p-wave' order parameter. The possible existence of such a pi-state in weakly coupled atomic Bose-Einstein condensates has also been proposed, but remains undiscovered. Here we report the observation of spontaneous build-up of in-phase ('zero-state') and antiphase ('pi-state') 'superfluid' states in a solid-state system; an array of exciton-polariton condensates connected by weak periodic potential barriers within a semiconductor microcavity. These in-phase and antiphase states reflect the band structure of the one-dimensional polariton array and the dynamic characteristics of metastable exciton-polariton condensates. 相似文献
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The Drosophila fruitless (fru) gene product Fru has been postulated to be a neural sex determination factor that directs development of the central nervous system (CNS), thereby producing male-typical courtship behaviour and inducing male-specific muscle. Male-specific Fru protein is expressed in small groups of neurons scattered throughout the CNS of male, but not female, Drosophila. Collectively, these observations suggest that Fru 'masculinizes' certain neurons, thereby establishing neural substrates for male-typical behaviour. However, specific differences between neurons resulting from the presence or absence of Fru are unknown. Previous studies have suggested that Fru might result in sexual differences in the CNS at the functional level, as no overt sexual dimorphism in CNS structure was discernible. Here we identify a subset of fru-expressing interneurons in the brain that show marked sexual dimorphism in their number and projection pattern. We also demonstrate that Fru supports the development of neurons with male-specific dendritic fields, which are programmed to die during female development as a result of the absence of Fru. Thus, Fru expression can produce a male-specific neural circuit, probably used during heterosexual courtship, by preventing cell death in identifiable neurons. 相似文献
7.
【目的】将SWAT(soil and water assessment tool)模型运用于重庆三峡库区长江支流的流域径流过程研究,为流域水资源的合理调控提供理论依据。【方法】以位于重庆市西部的璧南河流域为研究对象,构建SWAT模型对该流域的径流过程进行模拟。【结果】1)率定期与验证期流域月均径流量模拟值与实测值吻合度较好,率定期和验证期的Nash-Suttcliffe效率系数、确定性系数和相对误差接近一致,表明SWAT模型在璧南河流域具有很好的适用性。2) 2013—2021年璧南河流域年平均径流总量为1.79×108 m3,多年平均径流深为346.04 mm。各子流域产流主要集中在汛期(6—10月),非汛期产流量不足;季节产流量分配不均匀,夏秋季节产流量高,春冬季节产流量低;流域产流量整体呈下降趋势。3)流域径流深在空间上呈现东西两侧高、中间低的分布特征,多年径流深变化率呈现出高产流量区域的产流量变化率低、低产流量区域的产流量变化率高的空间分布规律;产流量高值区主要集中在吴滩、三合、广普、建龙等镇(街道),产流量低值区主要位于陈食、丁家、... 相似文献
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刘玉记 《佛山科学技术学院学报(自然科学版)》1994,(6)
在齿轮图.的每个齿的齿顶分别加上 m_1,m_2,…,m_n,条悬挂边后构成的图称为齿顶边星图,记为,(m_1,m_2,…,m_n).本文给出了、(m_1,m_2…,m_n)的优美标号,从而证明了.(m_1,m_2,…,m_n)是优美图;当m_1=m_2=…,m_n=k 时,(k,k,…k)即为 k 顶边星图,于是解决了“所有的 k 顶边星图都是优美图”这一猜想. 相似文献
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本文根据力矩分配法的思路,提出了一种适用于无侧移结构内力计算的快速力矩分配法,可以一次计算出杆端弯矩,十分方便。计算表明,本文方法精度较高,值得推广。 相似文献