A recessive gene controlling male sterility sensitive to short daylength/low temperature in wheat (Triticum aestivum L.)

Utilization of a two-line breeding system via photoperiod-thermo sensitive male sterility has a great potential for hybrid production in wheat (Triticum aestivum L.). 337S is a novel wheat male sterile line sensitive to both short daylength/low temperature and long daylength/high temperature. Five F₂ populations derived from the crosses between 337S and five common wheat varieties were developed for genetic analysis. All F₁’s were highly fertile while segregation occurred in the F₂ populations with a ratio of 3 fertile:1 sterile under short daylength/low temperature. It is shown that male sterility in 337S was controlled by a single recessive gene, temporarily designated as wptms3. Bulked segregant analysis (BSA) coupled with simple sequence repeat (SSR) markers was applied to map the sterile gene using one mapping population. The wptms3 gene was mapped to chromosome arm 1BS and flanked by Xgwm413 and Xgwm182 at a genetic distance of 3.2 and 23.5 cM, respectively. The accuracy and efficiency of marker-assisted selection were evaluated and proved essential for identifying homozygous recessive male sterile genotypes of the wptms3 gene in F₂ generation.     

我国英语专业学生话语标记使用策略调查分析

话语标记语对话语的整体连贯和构建起着重要作用。运用大量的真实语料调查了我国学生口语话语标记的使用情况,并从定量、定性的角度分析比较高分组和低分组学生使用话语标记时存在的差异及导致这种结果的可能原因,将对二语学习者提高口语会话策略、口语教学和口语能力测评等提供一定的借鉴意义。     

论矿物材料计算与设计

矿产资源产业是国民经济的基础产业,非金属矿产是重要的固体矿产之一,80%的矿物用于材料工业,矿物加工是矿产资源高效利用、制备矿物材料的重要加工技术环节,矿物材料是国民经济中高新技术材料的重要组成,材料科学及矿物材料学科的发展,为矿物材料计算与设计理论的提出奠定了实际基础.借鉴材料设计与计算的理论和方法,在总结、分析和研究矿物加工及矿物材料制备方面大量的理论研究和实际成果的基础上,提出了矿物材料计算与设计及功能性矿物材料、复合材料化学改性药剂分子设计与模拟的学术思想,论述了矿物材料计算与设计的基本科学技术问题、研究内容、相关学科体系、研究层次及其学科地位.其意义在于:使矿物加工工程学科发展和功能性矿物材料的研发,建立在基本科学原理基础之上,将矿物加工工程学科的主要研究内容统一在总体的方向、目标之内,横向拓展了相关学科理论的研究范围;根据矿物结构、组成,通过设计与计算,对矿物材料性能进行预测、预报,进而为制备提供最佳技术路线;对于已知性能的矿物材料优化制备路线,系统分析各种矿物的结构与组成及其所具备固有性质,针对各种材料性质要求,排列对应关系,为复合材料的制备奠定基础,进而实现矿物资源的高效开发和利用,同时,使得材料设计或计算材料的学科基础向研究矿物组成与结构的纵向延伸,丰富了材料科学思想.     

分子伴侣与蛋白质折叠

新合成的多肽链必须先经折叠和装配后形成特定的三维结构才具有活性．在多肽链折叠过程中，往往会产生折叠异常蛋白，形成集聚体．分子伴侣可有效地调控多肽链的正确折叠，从而避免集聚体的形成．文章主要对分子伴侣的定义、作用、种类、特性等做一介绍。     

话语标记语的认知语用制约功能研究

话语标记语是一种常见的话语现象.从关联理论观点出发,话语标记语能对话语的理解形成某种制约.即通过话语标记语制约听话人认知语境的构建使听话人进一步寻找话语与认知语境之间的关联,达到说话人期待的语境效果,实现成功交际.话语标记语能对语用过程实施一种认知上的语用制约.     

DNA标记及其在鱼类中的应用

DNA分子标记是继形态标记、细胞标记和生化标记之后发展起来的一种比较理想的遗传标记技术。本文简要介绍RFLP、RAPD、AFLP、SSR、SNP、EST、mtDNA等DNA分子标记的类型,基本原理和特点,以及分子标记技术在鱼类遗传图谱构建、基因定位和分子标记辅助育种等方面的应用前景予以展望。     

二化螟隐花色素基因cryptochrome1和cryptochrome2的克隆与表达谱分析

隐花色素基因(cryptochrome,简称cry)是一类生物钟基因,参与生物体昼夜节律调控。本实验克隆了二化螟2个隐花色素基因,分别命名为Cs-cry1和Cs-cry2(Genbank登录号分别为HG780135和KF977409),其分别包含1605 bp和2289 bp的开放阅读框,分别编码由534和762个氨基酸组成的蛋白;Cs-cry1与其它鳞翅目昆虫cry1的相似性较高,而Cs-cry2与其它鳞翅目昆虫cry2的相似性较高,这与系统进化分析结果相一致;半定量RT-PCR研究表明Cs-cry1和Cs-cry2基因在二化螟成虫触角、头、雄、腹、足和翅等不同组织中均有表达。实验结果为二化螟昼夜节律分子机制研究提供了理论依据。     

“你V”类话语标记的使用倾向及相关问题

文章从句法环境和语用功能两个方面分析了“你V”类话语标记的使用倾向,认为这些差异在一定程度上是受到语义俯瞰的制约和影响.话语标记的使用倾向反映出其语法化程度的高低.总体而言,“你V”的语法化程度从高到低依次为：“你看”＞“你说”＞“你想”＞“你知道”,这一结果是由“V”的表义功能、“V”的词性类别、“你V”的适用语体以及“你V”的音节数目等因素的共同作用造成的.     

Therapeutic radionuclides in nuclear medicine: current and future prospects

The potential use of radionuclides in therapy has been recognized for many decades. A number of radionuclides, such as iodine-131 (¹³¹I), phosphorous-32 (³²P), strontium-90 (⁹⁰Sr), and yttrium-90 (⁹⁰Y), have been used successfully for the treatment of many benign and malignant disorders. Recently, the rapid growth of this branch of nuclear medicine has been stimulated by the introduction of a number of new radionuclides and radiopharmaceuticals for the treatment of metastatic bone pain and neuroendocrine and other malignant or non-malignant tumours. Today, the field of radionuclide therapy is enjoying an exciting phase and is poised for greater growth and development in the coming years. For example, in Asia, the high prevalence of thyroid and liver diseases has prompted many novel developments and clinical trials using targeted radionuclide therapy. This paper reviews the characteristics and clinical applications of the commonly available therapeutic radionuclides, as well as the problems and issues involved in translating novel radionuclides into clinical therapies.