中国科学家参与完成“水稻基因组序列全图”

新华社北京8月11日电综合新华社驻伦敦记者曹丽君、总社记者张忠霞报道,日本、美国、中国等多国科学家在11日出版的英国Nature杂志上报告说,他们已绘制完成了“水稻基因组序列全图”,其覆盖率和精确度均远远高于此前发表的草图。据称,这是目前在高等生物中最精确、最完整的测序工作之一。     

基于图像处理华中五味子叶面积的回归测算

采用数字图像处理法测定华中五味子叶面积,分别构建了老枝和新梢上叶片的面积与叶形特征值（叶长、叶宽和叶长宽乘积）的相关性回归方程,并进行检验的结果显示,叶长宽乘积与叶面积的相关性最高,以其构建的回归方程测算的叶面积精确度最高,是一种简便而科学的非破坏性的测定华中五味子叶面积的方法。     

缺失数据和贝叶斯系统发育分析精确度之探索

The effect of missing data on phylogenetic methods is a potentially important issue in our attempts to reconstruct the Tree of Life. If missing data are truly problematic, then it may be unwise to include species in an analysis that lack data for some characters (incomplete taxa) or to include characters that lack data for some species. Given the difficulty of obtaining data from all characters for all taxa (e.g., fossils), missing data might seriously impede efforts to reconstruct a comprehensive phylogeny that includes all species. Fortunately, recent simulations and empirical analyses suggest that missing data cells are not themselves problematic, and that incomplete taxa can be accurately placed as long as the overall number of characters in the analysis is large. However, these studies have so far only been conducted on parsimony, likelihood, and neighbor-joining methods. Although Bayesian phylogenetic methods have become widely used in recent years, the effects of missing data on Bayesian analysis have not been adequately studied. Here, we conduct simulations to test whether Bayesian analyses can accurately place incomplete taxa despite extensive missing data. In agreement with previous studies of other methods, we find that Bayesian analyses can accurately reconstruct the position of highly incomplete taxa (i.e., 95% missing data), as long as the overall number of characters in the analysis is large. These results suggest that highly incomplete taxa can be safely included in many Bayesian phylogenetic analyses.     

氨基酸分析的准确度和精确度（续）

氨基酸分析的准确度和精确度（续）ＲｉｃｈａｒｄＬＤａｖｉｅｓ,ＤＲｏｂｉｎＢａｉｇｅｎｔ,ＭａｌｃｏｌｍＳＬｅｖｉｔｔ,ＹａｓｉｎＭｏｌｌａｈ,ＣａｒｌＪＲａｙｎｅｒ和ＡｌｉｓｏｎＢＦｒｅｎｓｈａｍ著张林生译魏景刚校西北农业大学实验中心陕西杨陵７１２...     

我国旱地小麦区域试验精确度及其环境综合评价

选用2003-2009年我国4个麦区、233个品种(系)、82个试点组成的全国旱地冬春小麦区域试验产量资料,研究了我国旱地小麦国家区域试验点的精确度、环境鉴别力和代表性,并对试验环境进行综合评价．结果表明：一年一点试验平均试验误差变异系数(CV)为6.1%,平均相对最小显著差数(RLSD)为10.5%,一年多点试验的CV值均在8.2%以内,大多数试点的CV和RLSD控制得较好,试验精确度和品种比较精确度均较高．试点分辨力以西北春小麦组最强,其他3个产区差别不大．试点代表性以东北春小麦组最好、西北春小麦组最差．在综合考虑试点分辨力和代表性基础上,借助GGE模型构建环境综合评价参数（r_g-h）,结果显示,我国旱地小麦理想试点比例只有32.4%,产区间比较,理想试点的比例依次为：西北春小麦旱地组（40.9%）＞东北春小麦旱地组（33.3%）＞黄淮冬小麦旱地组（30.4%）＞北部冬小麦旱地组（21.4%）.     

高精度相对和绝对定量的等量异位标签在定量蛋白质组学研究中的新进展

蛋白质组学逐渐从定性研究转向定量研究。在定量蛋白质组学技术中,相对和绝对定量的等量异位标签(Isobaric tags for relative and absolute quantitation,iTRAQ)是应用最广泛的技术之一,具有通量高、稳定性强及不受样品来源制约等优点,几乎可以对任意样品进行标记,而且可以同时对多达8个样品进行定量分析,有效地提高了通量。iTRAQ技术不断改进,其定量准确性显著提高,适用的平台越来越多,为微生物、动物、植物、生物医学领域蛋白质及其翻译后修饰组研究创造了条件。文中综述了高精度iTRAQ技术在定量蛋白质组学研究中的最新发展及其应用。     

类群取样与系统发育分析精确度之探索

Appropriate and extensive taxon sampling is one of the most important determinants of accurate phylogenetic estimation. In addition, accuracy of inferences about evolutionary processes obtained from phylogenetic analyses is improved significantly by thorough taxon sampling efforts. Many recent efforts to improve phylogenetic estimates have focused instead on increasing sequence length or the number of overall characters in the analysis, and this often does have a beneficial effect on the accuracy of phylogenetic analyses. However, phylogenetic analyses of few taxa (but each represented by many characters) can be subject to strong systematic biases, which in turn produce high measures of repeatability (such as bootstrap proportions) in support of incorrect or misleading phylogenetic results. Thus, it is important for phylogeneticists to consider both the sampling of taxa, as well as the sampling of characters, in designing phylogenetic studies. Taxon sampling also improves estimates of evolutionary parameters derived from phylogenetic trees, and is thus important for improved applications of phylogenetic analyses. Analysis of sensitivity to taxon inclusion, the possible effects of long-branch attraction, and sensitivity of parameter estimation for model-based methods should be a part of any careful and thorough phylogenetic analysis. Furthermore, recent improvements in phylogenetic algorithms and in computational power have removed many constraints on analyzing large, thoroughly sampled data sets. Thorough taxon sampling is thus one of the most practical ways to improve the accuracy of phylogenetic estimates, as well as the accuracy of biological inferences that are based on these phylogenetic trees.     

氨基酸分析的准确度和精确度

五个实验室分两部分协作研究改进和测定氨基酸分析的准确皮和精确度。末公开发表的第一部分结果由各实验室按照自己的最佳实验操作处理。本文报道第二部分,分析了三个纯化的和六个常规的蛋白质,每种蛋白质用三种不同的方法处理（常规水解、延长水解和下文提及到的氧化水解）。文献中报道的结果得到了证实,尽管其结果不太一致,还常有一些特殊的结果。得到文献充分证明的处理结果对于分析工作适应不同的要求是必不可少的。由于重复性变异较高,没有对某一个实验结果做进一步的统计分析。重复性（实验室内部）的变异系数为４．１％,再现性（实验室之间）的变异系数为１３．１％。纯化蛋白的最佳氨基酸估计和根据一个实验室的５个氨基酸与另一个实验室的５个氨基酸的偏差提供的排列顺序（Ｐ＜０．０１）计算的估计是不符的。对常规蛋白质结果的删除临界值采用Ｐ＜０．０１时,最佳估计的９．９％被删除,偏差为８．１％,奇异值为３．２％,偏差和奇异共有者为１．３％。当这些值被删除时,１９／９６平均值变化不超过４％,９／９６变化为４～８％,８／９６变化更大些,集合的变异系数由８．２％降到５．４％。在这种临界值下,常规蛋白质的每个实验室结果中有０～３１％删除。在较低的临界值（Ｐ＜?     

2种方法在血清β2-微球蛋白检测中的效果对比

目的:探讨散射免疫法和荧光免疫层析法在血清β2-微球蛋白中的检测效果对比观察及精确度。方法:选取2016年10月-2017年8月我院收治的肝肾功能损伤患者88例,对患者分别应用散射免疫法以及荧光免疫层析法进行检测。对比两组方法血清β2-微球蛋白的检测结果、灵敏度、特异性以及精确度。结果:检测结果方面,荧光免疫分析法患者的检测率明显高于散射免疫法,漏检率明显低于散射免疫法(P0.05);荧光免疫层析法的灵敏度、特异性以及诊断符合率明显高于散射免疫法(P0.05);各项指标水平方面,患者血清β2-微球蛋白、肌酐、尿酸以及尿素等指标的水平明显高于正常水平(P0.05);精确度方面,荧光免疫层析法批间、批内的精确度明显高于散射免疫法(P0.05)。结论:对患者应用荧光免疫层析法检测血清β2-微球蛋白,有较高的检测符合率、灵敏度以及准确度,能够满足临床检测过程中的要求,进而有利于患者的诊断和治疗,临床上应当进一步推广应用。     

达芬奇与解剖学

2012年5月,史上最大的达芬奇人体解剖素描展在英国白金汉宫女王画廊举行,展览中大量达芬奇生前有关人体解剖的笔记和素描图让观众们大开眼界。一提起达芬奇,人们自然会想到那脍炙人口的传世之作《蒙娜丽莎》。但是,谁又知晓他不仅