Taking Ta–W alloy system as an example, the concentration formulae of alloy genes of DO3-type alloys in BCC structures were derived on the basis of the theory of alloy genes and the number of coordination atoms. The ...Taking Ta–W alloy system as an example, the concentration formulae of alloy genes of DO3-type alloys in BCC structures were derived on the basis of the theory of alloy genes and the number of coordination atoms. The concentrations of alloy genes of DO3-TaW3 and DO3-Ta3W ordered alloys were calculated as functions of composition xW and ordering degree （s）. When s=smax, the concentrations of alloy genes of stoichiometric DO3-TaW3 compound are equal to those of alloys, that is, x8^Ta=0.25（at）,x4^W=0.5（at）,x8^W=0.25（at）The concentrations of alloy genes of stoichiometric DO3-Ta3W compound are also equal to those of alloys, that is,x0^Ta=0.25（at）,x4^Ta=0.5（at）,x0^W=0.25（at）. As ordering degree decreases, alloy genes of DO3-TaW3 and DO3-Ta3W ordered alloys will split. And the degree of splitting of alloy genes increases with the ordering degree decreasing. The atomic states and properties of DO3-TaW3 and DO3-Ta3W ordered alloys were calculated as a function of composition xW. The reason was pointed out that preparation of DO3-TaW3 and DO3-Ta3W intermetallic compounds is difficult due to small differences in their cohesive energies. It will provide theoretical guidance for the scientific designation to new candidate for ultra- high-temperature materials in areo-engine applications.展开更多
线纹尖塘鳢(Oxyeleotris lineolata)具有典型性别生长二态性,雄鱼生长优势显著,doublesex and mab-3 related transcription factor(DMRT)家族是一个与性别决定相关的转录因子家族。基于线纹尖塘鳢性腺转录组数据,共获得2个dmrt基因的c...线纹尖塘鳢(Oxyeleotris lineolata)具有典型性别生长二态性,雄鱼生长优势显著,doublesex and mab-3 related transcription factor(DMRT)家族是一个与性别决定相关的转录因子家族。基于线纹尖塘鳢性腺转录组数据,共获得2个dmrt基因的cDNA序列,分别命名为Oxldmrt1和Oxldmrt3,并采用PCR技术扩增验证2个基因的cDNA序列。运用生物信息学方法分析2个基因序列结构特征,结果显示,Oxldmrt1和Oxldmrt3开放阅读框分别为903 bp和1363 bp,分别编码300个氨基酸和453个氨基酸;OxlDMRT1属于碱性蛋白,而OxlDMRT3属于酸性蛋白;2个基因均含有高度保守的DM结构域,OxlDMRT3还存在DMA结构域。氨基酸聚类分析显示,脊椎动物不同DMRT家族都是独立聚类,OxlDMRT1属于DMRT1家族,OxlDMRT3属于DMRT3家族,DMRT1家族最先聚类,再和DMRT3家族聚类。利用实时荧光定量PCR技术(real-time quantitative PCR,RT-qPCR)分析2个dmrt基因在雌鱼和雄鱼8个组织的表达水平,结果显示,2个基因在精巢中的表达量均显著高于其他组织(P<0.01),Oxldmrt3在脑中也有少量表达;利用RT-qPCR分析2个dmrt基因在早期不同发育时期的表达谱,显示2个基因在受精卵中的表达量均最高,Oxldmrt1在眼囊期的表达量最低,而Oxldmrt3在出膜7 d时的表达量最低。利用荧光原位杂交(fluorescencein situhybridization,FISH)对2个基因在精巢中的表达进行定位,显示2个基因在精巢中表达部位一致,均在精原细胞中有较强的表达信号。综上所述,Oxldmrt1和Oxldmrt3均在线纹尖塘鳢性腺胚胎发育阶段和精巢发育过程中起调节作用,而Oxldmrt1还可能参与胚胎后期性别决定和性别分化调控过程,Oxldmrt3还可能参与神经系统发育。本研究为线纹尖塘鳢性别决定与性别分化相关的分子机制研究提供了参考。展开更多
银鱼是我国重要的经济鱼类,为了解云南杞麓湖和星云湖银鱼群体的遗传多样性与遗传结构,经PCR扩增与测序获得653 bp COI和1205 bp Cytb基因序列。COI基因39条序列共检测到5个单倍型,单倍型多样性、核苷酸多样性、平均核苷酸差异数分别为0...银鱼是我国重要的经济鱼类,为了解云南杞麓湖和星云湖银鱼群体的遗传多样性与遗传结构,经PCR扩增与测序获得653 bp COI和1205 bp Cytb基因序列。COI基因39条序列共检测到5个单倍型,单倍型多样性、核苷酸多样性、平均核苷酸差异数分别为0.323±0.093、0.00060±0.00020、0.39406。Cytb基因38条序列共检测到6个单倍型,单倍型多样性、核苷酸多样性、平均核苷酸差异数分别为0.413±0.097、0.00102±0.00033、1.22760。COI和Cytb基因的AMOVA分子变异显示群体内的方差组分比率(92.39%,87.03%)大于群体间的方差组分比率(7.61%,12.97%),显示遗传变异主要发生在群体内;且群体间存在中度遗传分化和基因流。COI系统发育树显示杞麓湖和星云湖银鱼序列同新银鱼属未定种、太湖新银鱼和陈氏新银鱼聚为单系支;Cytb树显示两湖银鱼序列同太湖新银鱼和陈氏新银鱼聚为单系支,支持率为100%。单倍型网络图显示两湖银鱼群体的所有单倍型并没有单独聚在一起。此外,COI基因的中性检验和核苷酸错配分布结果显示杞麓湖和两个湖泊总的数据集的群体在历史上发生过群体扩张事件。上述结果表明杞麓湖和星云湖银鱼群体遗传多样性水平较低,无显著的群体遗传结构。展开更多
基金Project(50954006) supported by the National Natural Science Foundation of ChinaProject(2014-12) supported by the Environmental Protection Department of Hunan,China+1 种基金Project(2016TP1007) supported by the Hunan Provincial Science and Technology Plan Project,ChinaProject(2016-01) supported by the Development and Reform Commission of Hunan Province,China
文摘Taking Ta–W alloy system as an example, the concentration formulae of alloy genes of DO3-type alloys in BCC structures were derived on the basis of the theory of alloy genes and the number of coordination atoms. The concentrations of alloy genes of DO3-TaW3 and DO3-Ta3W ordered alloys were calculated as functions of composition xW and ordering degree （s）. When s=smax, the concentrations of alloy genes of stoichiometric DO3-TaW3 compound are equal to those of alloys, that is, x8^Ta=0.25（at）,x4^W=0.5（at）,x8^W=0.25（at）The concentrations of alloy genes of stoichiometric DO3-Ta3W compound are also equal to those of alloys, that is,x0^Ta=0.25（at）,x4^Ta=0.5（at）,x0^W=0.25（at）. As ordering degree decreases, alloy genes of DO3-TaW3 and DO3-Ta3W ordered alloys will split. And the degree of splitting of alloy genes increases with the ordering degree decreasing. The atomic states and properties of DO3-TaW3 and DO3-Ta3W ordered alloys were calculated as a function of composition xW. The reason was pointed out that preparation of DO3-TaW3 and DO3-Ta3W intermetallic compounds is difficult due to small differences in their cohesive energies. It will provide theoretical guidance for the scientific designation to new candidate for ultra- high-temperature materials in areo-engine applications.
文摘银鱼是我国重要的经济鱼类,为了解云南杞麓湖和星云湖银鱼群体的遗传多样性与遗传结构,经PCR扩增与测序获得653 bp COI和1205 bp Cytb基因序列。COI基因39条序列共检测到5个单倍型,单倍型多样性、核苷酸多样性、平均核苷酸差异数分别为0.323±0.093、0.00060±0.00020、0.39406。Cytb基因38条序列共检测到6个单倍型,单倍型多样性、核苷酸多样性、平均核苷酸差异数分别为0.413±0.097、0.00102±0.00033、1.22760。COI和Cytb基因的AMOVA分子变异显示群体内的方差组分比率(92.39%,87.03%)大于群体间的方差组分比率(7.61%,12.97%),显示遗传变异主要发生在群体内;且群体间存在中度遗传分化和基因流。COI系统发育树显示杞麓湖和星云湖银鱼序列同新银鱼属未定种、太湖新银鱼和陈氏新银鱼聚为单系支;Cytb树显示两湖银鱼序列同太湖新银鱼和陈氏新银鱼聚为单系支,支持率为100%。单倍型网络图显示两湖银鱼群体的所有单倍型并没有单独聚在一起。此外,COI基因的中性检验和核苷酸错配分布结果显示杞麓湖和两个湖泊总的数据集的群体在历史上发生过群体扩张事件。上述结果表明杞麓湖和星云湖银鱼群体遗传多样性水平较低,无显著的群体遗传结构。
