Diffusion dynamics of glycine receptors revealed by single-quantum dot tracking

Semiconductor quantum dots (QDs) are nanometer-sized fluorescent probes suitable for advanced biological imaging. We used QDs to track individual glycine receptors (GlyRs) and analyze their lateral dynamics in the neuronal membrane of living cells for periods ranging from milliseconds to minutes. We characterized multiple diffusion domains in relation to the synaptic, perisynaptic, or extrasynaptic GlyR localization. The entry of GlyRs into the synapse by diffusion was observed and further confirmed by electron microscopy imaging of QD-tagged receptors.     

Nuclear pore complex structure and dynamics revealed by cryoelectron tomography

Nuclear pore complexes (NPCs) are gateways for nucleocytoplasmic exchange. To analyze their structure in a close-to-life state, we studied transport-active, intact nuclei from Dictyostelium discoideum by means of cryoelectron tomography. Subvolumes of the tomograms containing individual NPCs were extracted in silico and subjected to three-dimensional classification and averaging, whereby distinct structural states were observed. The central plug/transporter (CP/T) was variable in volume and could occupy different positions along the nucleocytoplasmic axis, which supports the notion that it essentially represents cargo in transit. Changes in the position of the CP/T were accompanied by structural rearrangements in the NPC scaffold.     

Lineages of acidophilic archaea revealed by community genomic analysis

Novel, low-abundance microbial species can be easily overlooked in standard polymerase chain reaction (PCR)-based surveys. We used community genomic data obtained without PCR or cultivation to reconstruct DNA fragments bearing unusual 16S ribosomal RNA (rRNA) and protein-coding genes from organisms belonging to novel archaeal lineages. The organisms are minor components of all biofilms growing in pH 0.5 to 1.5 solutions within the Richmond Mine, California. Probes specific for 16S rRNA showed that the fraction less than 0.45 micrometers in diameter is dominated by these organisms. Transmission electron microscope images revealed that the cells are pleomorphic with unusual folded membrane protrusions and have apparent volumes of <0.006 cubic micrometer.     

Ecological adaptation during incipient speciation revealed by precise gene replacement

To understand the role of adaptation in speciation, one must characterize the ecologically relevant phenotypic effects of naturally occurring alleles at loci potentially causing reproductive isolation. The desaturase2 gene of Drosophila melanogaster is such a locus. Two geographically differentiated ds2 alleles underlie a pheromonal difference between the Zimbabwe and Cosmopolitan races. We used a site-directed gene replacement technique to introduce an allele of ds2 from the Zimbabwe population into Cosmopolitan flies. We show that the Cosmopolitan allele confers resistance to cold as well as susceptibility to starvation when the entire genetic background is otherwise identical. We conclude that ecological adaptation likely accompanies sexual isolation between the two behavioral races of D. melanogaster.     

木荷种群遗传多样性的ISSR分析

利用ISSR分子标记技术,对木荷种群的遗传多样性和遗传分化进行分析.用12个引物对9个木荷种群共180个个体的样品进行扩增,共测到245个位点,其中多态位点221个,多态位点百分率(P)为90.20%.9个种群的P平均为53.02%.木荷种水平的Shannon信息指数(Ⅰ)为0.4548,Nei指数(h)为0.3016.各种群Ⅰ平均为0.2914,h平均为0.1974.表明木荷物种以及种群水平均具有较高的遗传多样性.AMOVA分子差异分析表明木荷种群的遗传变异34.37%存在于种群间,65.63%存在于种群内,种群间的基因分化系数(Gst)为0.3454.木荷种群间的基因流(Nm)为0.9476.木荷9个种群间的遗传距离平均为0.1547.利用算术加权平均数法(UPGMA)对木荷9个种群进行聚类,结果可分为3大类群.     

牛肉冷藏过程中品质变化的动力学分析

【目的】研究宰后冷藏过程中牦牛肉和西门塔尔杂交牛肉的肉用品质.【方法】试验以3~5岁的牦牛肉和西门塔尔杂交牛肉背最长肌为研究对象,分析了4℃冷藏过程中样品肉用品质(pH、失水率、熟肉率、剪切力和肉色)的变化,采用动力学探究了样品肉用品质的变化规律.【结果】在4℃有氧贮藏条件下,牦牛肉和西门塔尔杂交牛肉的pH、熟肉率均先降低后升高,在第5天达到最小值,剪切力先升高后降低,第3天达到最大值,失水率和b*值均先升高后降低,在第5天达到最大值,L*值和a*值持续降低;与西门塔尔杂交牛肉相比,牦牛肉的pH、失水率、L*值低于西门塔尔杂交牛肉,剪切力、熟肉率、a*值和b*值高于西门塔尔杂交牛肉.【结论】贮藏过程中牦牛肉的剪切力、L*值、a*值可以进行线性拟合,a*值的拟合度最高;pH、失水率、熟肉率和b*值不可以进行线性拟合,失水率的拟合度最低.贮藏过程中西门塔尔杂交牛肉的L*值、a*值可以进行线性拟合,a*值的拟合度最高;pH、失水率、熟肉率、剪切力和b*值不可以进行线性拟合,b*值的拟合度最低.     

Control of fusion pore dynamics during exocytosis by Munc18

Intracellular membrane fusion is mediated by the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins. All vesicle transport steps also have an essential requirement for a member of the Sec1 protein family, including the neuronal Munc18-1 (also known as nSec1) in regulated exocytosis. Here, in adrenal chromaffin cells, we expressed a Munc18 mutant with reduced affinity for syntaxin, which specifically modified the kinetics of single-granule exocytotic release events, consistent with an acceleration of fusion pore expansion. Thus, Munc18 functions in a late stage in the fusion process, where its dissociation from syntaxin determines the kinetics of postfusion events.     

Cell lineage analysis by intracellular injection of fluorescent tracers

Cell lineages during development of the leech are revealed by injection of a fluorescent peptide, rhodamine-D-peptide, into identified embryonic cells. Use of this peptide together with a nuclear stain showed a stereotypic cleavage pattern of stem cells and their progeny. Combined injection of rhodamine-D-peptide and pronase demonstrated the arrest of stem cell production in the pronase-injected teloblast.     

基于SSR标记的广东省甘蔗黑穗病菌遗传多样性研究

利用SSR标记分析了30个来自广东省甘蔗主产区的甘蔗黑穗病菌菌株的遗传多样性。用19对带型较稳定且条带清晰的引物从供试菌株群体中检测到了39个多态性位点,平均每个引物得到2.05条多态性带。UPGMA聚类分析表明,在约0.74的相似系数水平,SSR标记把30个菌株划分为5个类群,类群1有22个菌株,包含了绝大部分来自粤西和粤北的菌株及全部的广州市郊菌株;在约0.8的相似系数水平,类群1可以进一步分为2个亚群体,亚群体1包含了90%的粤北菌株,亚群体2则包含了50%的粤西菌株。研究结果表明:该菌的遗传多样性与菌株的地理来源呈显著相关,而与品种间的相关性不大。     

Single, rapid coastal settlement of Asia revealed by analysis of complete mitochondrial genomes

A recent dispersal of modern humans out of Africa is now widely accepted, but the routes taken across Eurasia are still disputed. We show that mitochondrial DNA variation in isolated "relict" populations in southeast Asia supports the view that there was only a single dispersal from Africa, most likely via a southern coastal route, through India and onward into southeast Asia and Australasia. There was an early offshoot, leading ultimately to the settlement of the Near East and Europe, but the main dispersal from India to Australia approximately 65,000 years ago was rapid, most likely taking only a few thousand years.     

Genomic-SSR 和EST-SSR在柱花草种间的遗传差异

为了探讨genomic-SSR与EST-SSR标记在柱花草种间的遗传差异,利用两种SSR标记技术,对来自不同种的12份柱花草种质进行了遗传分析,并对两种不同标记进行比较.结果表明:EST-SSR标记相比genomic-SSR在柱花草不同种间具有更好的通用性,EST-SSR检测到的等位基因数和PIC指数平均值分别是4.6和0.610,genomic-SSR检测到的等位基因数和PIC指数平均值分别是5.6和0.702.聚类结果表明,genomic-SSR和EST-SSR均能有效鉴别所有供试柱花草种质.     

应用近红外反射光谱技术测定油菜芽期耐旱性的研究

针对油菜芽期耐旱鉴定,提出了用近红外反射光谱技术（NIR法）预测油菜吸胀24 h电导率、PEG模拟干旱条件下的相对发芽率、相对鲜重和鲜重耐旱指数等4个芽期耐旱相关性状的方法。以采集的49份不同耐旱水平甘蓝型油菜近红外光谱数据为基础,采用偏最小二乘法和多元回归算法建立了最优定标模型,并获得较高的决定系数(0.71～0.86)和较低的标准误差(1～15.65)。验证集评估结果表明,NIR法与室内鉴定法测定油菜4个芽期耐旱相关性状无显著差异,且具有极显著的相关关系(决定系数0.72～0.89)。研究表明,近红外光谱技术用于油菜芽期耐旱性鉴定是可行的,可用于耐旱育种早代选择。     

沙棘微扦插不定根发生的形态解剖学研究

利用石蜡切片法对沙棘微扦插不定根的发生进行形态解剖学研究。结果表明:沙棘属于诱导型生根,观察到其不定根原基起源于2个区域,一部分根原基起源于维管形成层细胞,另一部分起源于韧皮部薄壁细胞区域。沙棘不定根原基继续发育时,一部分沿射线向外生长,另一部分向外生长的同时会与茎段的髓连接起来,这种现象在其他树种中尚未发现。沙棘插穗不定根的发生整体上可分为4个阶段:1）维管形成层细胞和韧皮部薄壁细胞分裂出一些排列紧密、细胞质浓、具有分生组织特点的薄壁细胞团;2）新形成的薄壁细胞团不断分裂并且脱分化,形成具有很强分生能力的不定根原基发端细胞;3）根原基发端细胞继续分裂,沿着射线向远离轴心的方向伸展,从而形成根原基;4）根原基穿过韧皮射线和皮层,向外继续朝皮孔方向发展,最终从皮孔伸出形成不定根,不定根伸出皮孔前内部维管系统发育完善并与茎部维管系统相连接。      

Genome-wide identification of WOX gene family in apple and a functional analysis of MdWOX4b during adventitious root formation

The plant-specific WUSCHEL-related homeobox(WOX) genes are crucial for plant growth and development.Here,we systematically identified the MdWOX gene family in apple at the genome-wide level,and analyzed the phylogenetic relationships,conserved motifs,gene structure,and syntenic relationships of the MdWOX genes.A total of 18 MdWOX genes were identified and phylogenetic analysis placed them into three clades.The phylogenetic relationships among the WOXs were further supported by the analyses of ge...     

茄子不同器官在不同生育期对氮磷钾吸收差异的比较分析

以茄子品种‘杭茄2008’为试材,对茄子主要矿质营养氮磷钾的吸收规律进行了研究。分别于不同生育期测定茄子的根、茎、叶、果等器官的氮、磷、钾含量。结果表明：全生育期茄子单株吸收的养分以钾(K)素为最多,达11.41 g;氮(N)素次之,为4.19 g ;磷(P)素最少,仅1.19 g。不同生育期茄子单株吸收的氮磷钾,均以苗期最少,分别占全生育期的3.3%,3.5%和2.6%;始果期次之,分别占14.6%,10.8%和16.9%;盛果期吸收最大,分别占48.9%,47.9%和49.2%。氮磷钾分配比例均以果实中最高,分别占53.2%,68.9%和55.3%;根中最低;但叶中氮含量高于茎中,而茎中磷和钾含量均高于叶中。生长期中茄子日积累氮磷钾的最佳曲线方程为三次曲线方程,此方程要优于常用的线性方程和对数曲线方程。当鲜茄产量为3 941 kg·667 m-2时,每生产1 000 kg鲜茄吸收的氮(N)、磷(P)和钾(K)量分别为2.13,0.60和5.78 kg,N∶P∶K吸收比例为1.00∶0.28∶2.71。     

应用16S rDNA序列分析对马铃薯贮藏期三个病原细菌菌株的鉴定

通过对甘肃天祝引起马铃薯病害的细菌的分离培养和致病性测定,有3个细菌菌株能够引起马铃薯贮藏期腐烂病.通过16S rDNA序列分析,2个菌株被鉴定为Erwinia persicinus,1个菌株为Microbacterium phyllosphaerae.3个菌株均为革兰氏阴性菌,且对贮藏期的马铃薯均有不同程度的致病性,能引起马铃薯的腐烂.     

外源茉莉酸对稻瘟病菌引起褐点型坏死斑的水稻防御响应的影响

[目的]解析外源茉莉酸(JA)对JA合成/响应、水杨酸(SA)合成/受体及防御相关基因表达的影响,为进一步揭示JA调控稻瘟病菌侵染引起褐点型坏死斑的水稻抗病作用机制提供基础数据.[方法]以接种稻瘟病菌菌株Y92-66b后形成褐点型坏死斑的地方中抗水稻月亮谷为研究材料,分别利用400μmol/L JA和200μmol/L JA抑制剂(IBU)外源处理接种稻瘟病菌后引起褐点型坏死斑(72 h)的水稻月亮谷,调查水稻稻瘟病症状,同时利用实时荧光定量PCR(qRT-PCR)检测JA合成/响应、SA合成/受体、防御和蔗糖/果糖合成酶基因的表达.[结果]外源JA有效减轻了水稻稻瘟病症状.同时,JA诱导水稻JA合成基因OsLOX1、OsOPR1、OsOPR7、OsJIMT、OsHPL3和OsAOS2在72 h时上调表达,至96和120 h时,只有OsAOS2、OsOPR7和OsLOX1上调表达,其余3个基因下调表达;外源JA未诱导OsLOX3表达;JA诱导水稻JA响应基因OsCOI1a、OsMYC2、OsJAZ1、OsJAZ9和OsbHLH35在72 h时上调表达,至120 h时,只有OsCOI1a和OsJAZ1上调表达,其余3个基因均下调表达;外源JA未诱导OsCOI1b和JiOsPR10表达.JA诱导SA受体基因OsNPR4在72 h时显著上调表达(P<0.05,下同),96 h时下调表达,至120 h时又上调表达但不显著(P>0.05).JA诱导SA合成相关基因OsPAD4在72 h时显著上调表达,OsEDS1在120 h时显著上调表达.外源JA诱导防御基因OsPR5在72 h时开始上调表达,至96 h时显著上调表达;外源JA未诱导OsPR4a表达.外源JA诱导参与细胞壁合成的蔗糖合成酶基因OsRSUS1和果糖合成酶基因OsFRK-2表达,IBU则加重了水稻稻瘟病症状,同时抑制大部分JA合成/响应、蔗糖/果糖合成酶和防御基因的表达.[结论]外源JA主要通过诱导稻瘟菌引起的褐点型坏死斑的水稻JA合成/响应基因、参与细胞壁合成的蔗糖/果糖合成酶及防御基因表达参与水稻防御响应.     

金标免疫层析试条检测样品中黄曲霉毒素B1的误差分析

为了扩大金标免疫层析试条(GICA)检测食品和饲料中黄曲霉毒素B1的应用范围,研究了样品基质对试剂条信号强度的影响,探讨了GICA测定饲料和各种发酵类食品样品时,提取液中NaCl、金属离子(Fe3+,Cu2+,Pb2+,As3+)和脂肪含量对检测结果的影响,并研究了消除影响的方法。结果表明,3种阴性样品(大米、玉米和小麦粉)均存在不同程度的非特异性干扰,大米的影响最小,其次为玉米和小麦粉,大米的最佳稀释倍数为10倍,玉米和小麦粉为30倍;随NaCl质量浓度增加,检测结果有偏向假阳性的趋势;4种金属离子对检测结果的影响程度依次为Fe3+>Cu2+>Pb2+>As3+;随着样品中油脂含量的增高,用GICA检测结果偏阳性的程度加剧。对粗提取液用氯仿法萃取后挥干再溶解,可将盐离子和重金属离子对测定的影响控制在允许范围之内;用石油醚脱脂,可使油脂对测定结果的影响降到最低。     

糜子干旱后复水过程中基因表达谱的初步分析

为探索在干旱后复水条件下糜子抗旱种质的基因表达特点,寻找与其复水后快速恢复生长相关的基因,利用抑制消减杂交(Suppressive subtraction hybridization,SSH)技术,以糜子干旱后复水处理叶片的cDNA为tester,干旱胁迫处理叶片的cDNA为driver,构建了一个抑制消减杂交文库。在文库中随机选取100个克隆(插入片段≥250 bp)测序,所获序列去除载体、引物及接头序列后,利用NCBI的BLAST序列比对分析软件分别对GenBank的dbEST数据库和非冗余蛋白数据库进行序列比对分析。序列同源性分析显示,文库中序列的同源基因主要以与新陈代谢、能量代谢、转录、蛋白加工、细胞信号转导及细胞组分生物合成相关的基因为主,其中以新陈代谢及细胞组分生物合成相关的基因数最多,分别占到与已知蛋白同源的EST的22.4%和10.3%。表明植物在干旱后复水条件下产生一系列的信号传导,同时启动相应的转录机制,激活响应基因的表达,以适应逆境的改变。