花(鱼骨)胚胎发育及卵黄囊仔鱼形态的初步观察

运用多种处理方法对花的胚胎发育进行连续观察,并对其卵黄囊仔鱼形态变化进行初步观察与测量。观察结果显示:(1)花胚胎发育可以划分为22个明显的时期,包括7个主要的发育阶段;(2)在(20±1)℃条件下,仔鱼在出膜后的第3天开口摄食,卵黄囊在第7天基本消失,此阶段仔鱼的全长平均日增长率为4．67％,而以第4天增长最快。该实验结果将为花的人工繁殖及苗种培育,特别是为仔鱼在营养转换阶段的培育提供了理论参考。     

Conditional and joint multiple-SNP analysis of GWAS summary statistics identifies additional variants influencing complex traits

We present an approximate conditional and joint association analysis that can use summary-level statistics from a meta-analysis of genome-wide association studies (GWAS) and estimated linkage disequilibrium (LD) from a reference sample with individual-level genotype data. Using this method, we analyzed meta-analysis summary data from the GIANT Consortium for height and body mass index (BMI), with the LD structure estimated from genotype data in two independent cohorts. We identified 36 loci with multiple associated variants for height (38 leading and 49 additional SNPs, 87 in total) via a genome-wide SNP selection procedure. The 49 new SNPs explain approximately 1.3% of variance, nearly doubling the heritability explained at the 36 loci. We did not find any locus showing multiple associated SNPs for BMI. The method we present is computationally fast and is also applicable to case-control data, which we demonstrate in an example from meta-analysis of type 2 diabetes by the DIAGRAM Consortium.     

Evidence of widespread selection on standing variation in Europe at height-associated SNPs

Strong signatures of positive selection at newly arising genetic variants are well documented in humans, but this form of selection may not be widespread in recent human evolution. Because many human traits are highly polygenic and partly determined by common, ancient genetic variation, an alternative model for rapid genetic adaptation has been proposed: weak selection acting on many pre-existing (standing) genetic variants, or polygenic adaptation. By studying height, a classic polygenic trait, we demonstrate the first human signature of widespread selection on standing variation. We show that frequencies of alleles associated with increased height, both at known loci and genome wide, are systematically elevated in Northern Europeans compared with Southern Europeans (P < 4.3 × 10(-4)). This pattern mirrors intra-European height differences and is not confounded by ancestry or other ascertainment biases. The systematic frequency differences are consistent with the presence of widespread weak selection (selection coefficients ～10(-3)-10(-5) per allele) rather than genetic drift alone (P < 10(-15)).     

重要麦类作物表达序列标签(EST)计划研究进展

EST是指作为基因表达标签的一段长度150～500 bp的cDNA序列.EST计划旨通过大规模对随机挑取的cDNA克隆测序,获得、研究大批EST,进而研究生物体生长发育、繁殖分化、遗传变异、衰老死亡等系列生命过程.本文综述了重要麦类作物EST计划的研究进展,包括发展EST分子标记、构建遗传学图谱、分离与鉴定新基因、比较基因组学以及基因表达研究等,并对EST计划在麦类作物研究中存在的问题及应用前景进行了分析.     

苦味受体基因家族功能和演化研究的最新进展

苦味的识别作为一种防御机制, 能帮助动物避免摄入有毒物质, 它在动物的长期进化过程中起着至关重要的作用. 由于不同动物具有不同的生存环境和取食偏好, 使苦味识别能力在动物的长期进化中产生了分化. 苦味的识别源于苦味物质和苦味受体的结合, 所以对编码苦味受体基因的研究成为研究苦味识别的分子基础. 近年来, 随着体外功能实验体系的建立, 越来越多苦味受体的配体被发现. 另一方面, 随着许多脊椎动物基因组的测序完成, 人们对苦味受体基因家族的演化研究也取得了很大的进展. 对演化驱动力的研究, 能够使我们了解不同物种中苦味受体功能的变化趋势, 从而帮助我们发现更多的苦味配体. 本文主要介绍了苦味受体基因家族的功能及其在脊椎动物中演化的最新进展, 并对苦味受体基因家族今后的研究提出了展望.     

真空凝固天然橡胶胶乳及其生胶性能

在真空条件下, 天然胶乳橡胶粒子会膨胀、破裂, 从而引起天然胶乳的凝固. 本研究 首次将真空技术引入天然胶乳凝固领域. 真空凝固天然胶乳可物理控速、凝固彻底、胶清清澈、污染低. 与酸凝固天然胶乳的生胶及微生物凝固天然胶乳的生胶相比, 真空凝固胶具备多孔、叠层结构, 干燥失水快、抗氧指数(PRI)高、硫化速度较快, 硫化后物理机械性能在3 种硫化胶中最优. 本研究为天然胶乳的凝固提供了一种新的物理方法.     

Over-expression of an Arabi-dopsisd δ-OAT gene enhances salt and drought tolerance in transgenic rice

Riceisoneofthemostimportantcropsintheworld,sincemorethanhalfoftheworldspopulationisfedonrice(OryzasativaL.).Althoughmuchhasbeendoneonfoodsecurityforlong,osmoticstress,duetodroughtandsalinity,isstillthemostseriousfactorthataffectstheyieldofrice[1].Ithaslongbeenfoundthatplantsaccumulateosmolytestomaintainosmoticbalanceandtoprotectsubcellularstructures[2].Theseosmolytesaremainlysmallmolecularweightorganiccompoundsandproteinprotec-tants.Prolineisregardedasthemostwidely-distributedosmolyteandwitht…     

番茄丛矮病毒组(Tombusviruses)成员外壳蛋白是一种单双链DNA结合蛋白

应用South-western技术以番茄丛矮病毒组(tombusvirus)6种病毒为材料研究了它们的外壳蛋白对单双链DNA的结合作用。结果表明tombus-组6种病毒(PLCV,AMCV,CNV,CyRSV,PAMV,TBSV)的外壳蛋白及PLCV重组外壳蛋白是一种单双链DNA结合蛋白,对单链DNA的结合能力远远超过双链DNA。这种结合作用可能与在tombus一组病毒外壳蛋白立体空间结构有关,因为当蛋白变性时结合作用大大降低。另外,一旦外壳蛋白与单链DNA发生相互作用,用4moL/L尿素或0.1％SDS在90°C水浴中难以洗掉。Tombus一组病毒外壳蛋白这种对单双链DNA的结合作用可能表明它们是一种参与病毒体内运输或调节复制的蛋白。     

NaCl胁迫对不同品种萝卜种子 发芽特性的影响

采用6个有代表性的萝卜栽培品种,以不同浓度NaCl对种子发芽作盐胁迫处理。研究结果表明,在发芽期的耐盐力上,6个品种间存在明显差异。“廿日樱桃”耐盐力最强在100 mmol