基于天然产物的蛋白酪氨酸磷酸酶1B 抑制剂的虚拟筛选

蛋白酪氨酸磷酸酶1B(protein tyrosine phosphatase 1B,PTP1B)是治疗Ⅱ型糖尿病的靶点之一,筛选PTP1B抑制剂具有十分重要的意义.本文采用分子对接虚拟筛选方法,构建共含有42 296个小分子的天然产物库,分别与PTP1B靶点蛋白进行分子对接,以原配体的结合能量为阈值,经过三轮筛选选取打分值高于阈值的小分子进行药代动力学参数和毒性参数预测,最终筛选出3个PTP1B抑制剂,对苯醌类化合物7、异香豆素类衍生物10和Clavepictine类似物11.结合方式研究表明,3个候选抑制剂类药性良好,均具有较好的PTP1B抑制活性,其中化合物10和11的PTP1B抑制活性未见报道.对化合物10进行体外抑制活性检测,其IC50为(74.58±1.23)μmol/L,可作为潜在Ⅱ型糖尿病治疗药物.     

马铃薯花芽分化与内源激素动态变化的关系

以马铃薯2个开花品种YS205和HZ88以及未开花品种YS304为材料,采用石蜡切片法观察花芽分化的解剖学特征,并用酶联免疫吸附法(ELISA)测定开花与未开花品种不同时期叶内4种内源激素——生长素(IAA)、赤霉素(GA3)、玉米核苷素(ZR)、脱落酸(ABA)含量的动态变化,探讨成花过程中叶片内源激素含量和比值的变化与成花的关系,为马铃薯花期调控、栽培和杂交育种提供理论依据。结果显示:(1)马铃薯花芽内部发育与外部形态之间有相对稳定的时序性对应关系,从花芽分化初期生长锥逐渐向上凸起,到雌雄蕊原基形成,完成整个花芽分化仅用了1周左右的时间,此阶段YS205和HZ88的花芽分化过程无明显差异,而YS304未成花。(2)随着花器官的不断发育,HZ88子房形成2室,每室多个胚珠,而YS205的子房在发育过程中发生了变异,形成完整的3室;YS205和HZ88都先后经历了授粉受精过程,HZ88具有一定的自交结实率,YS205无坐果率。(3)马铃薯3个品种的IAA、GA3、ZR和ABA含量在花芽分化前期均较低,且无明显差异性;随后,3个品种的IAA和GA3含量均呈先升后降的单峰变化曲线,但YS304上升和下降的速度较2个开花品种快,而且YS205和HZ88的ZR和ABA含量则始终高于YS304。(4)开花品种YS205和HZ88的ABA/IAA、ABA/GA3、ZR/IAA、ZR/GA3比值均高于未开花品种YS304,且随生育期变化趋势不同。研究表明,较低水平的IAA、GA3和高水平的ABA、ZR均有利于促进马铃薯花芽分化,反之则抑制花原基形态的建成。     

烟草NtNHX1 3基因的克隆及表达特性

以栽培烟草‘云烟87’为材料,通过同源克隆方法分离了烟草NHX（Na⁺,K⁺/H⁺ exchanger）基因NtNHX1 3。结果表明：NtNHX1 3基因CDS长度1 617 bp,编码蛋白质长度为538 aa,蛋白理论等电点为8.67,分子量为59.34 kD。预测NtNHX1 3属于膜蛋白,含有11个跨膜区,且含有NHX类蛋白保守位点氨氯吡嗪咪结合位点。进化树分析显示,NtNHX1 3与菊苣、野菊花NHX遗传距离最近。qRT PCR组织特异性表达分析表明,NtNHX1 3在烟草叶片中表达量最高,根、茎、花中也有表达;盐胁迫处理后NtNHX1 3基因的表达上调,表明该基因参与了盐胁迫反应;打顶初期NtNHX1 3基因的表达呈逐渐上调的趋势,与该时期钾含量逐渐升高相吻合。研究推测,NtNHX1 3具有将钾离子从细胞质转运至液泡的功能。     

Vessel length as a key hydraulic structure in woody plants: A review

导管作为多数被子植物木质部水分运输的主要通道, 了解其结构及功能对研究被子植物水力学特性及植物对环境的适应性有着重要的作用。导管长度作为导管解剖特征之一, 对水分运输的安全性及有效性有着重要的影响。该文概述了导管长度测量及计算的方法, 导管长度在种内及种间的分布, 导管长度与导管直径的关系, 导管长度与导水率的关系及导管长度对建立栓塞脆弱曲线的影响, 并对未来导管长度的研究工作重点提出了建议: 1)改进灌注物质, 使灌注更加充分且更利于观察、提高计算精度、发展活体动态测量技术; 2)建立导管在植物不同器官及整体的分布网络以及不同生活型、不同地区的导管长度数据库; 3)对导管直径在导管方向的变化, 导管长度与其他导管特性之间的关系进行研究; 4)光学测量建立栓塞脆弱曲线技术的兴起, 可为解决离心机法建立栓塞脆弱曲线的真实与准确与否的争议提供新的方向。更深入地了解导管长度在植物水力功能中担负的角色, 可以为耐旱、抗旱品种选育提供理论基础。     

The effect of floor type on the performance,cleanliness, carcass characteristics and meat quality of dairy origin bulls

The aim of this study was to evaluate the effect of using different floor types to accommodate growing and finishing beef cattle on their performance, cleanliness, carcass characteristics and meat quality. In total, 80 dairy origin young bulls (mean initial live weight 224 kg (SD=28.4 kg)) were divided into 20 blocks with four animals each according to live weight. The total duration of the experimental period was 204 days. The first 101 days was defined as the growing period, with the remainder of the study defined as the finishing period. Cattle were randomly assigned within blocks to one of four floor type treatments, which included fully slatted flooring throughout the entire experimental period (CS); fully slatted flooring covered with rubber strips throughout the entire experimental period (RS); fully slatted flooring during the growing period and moved to a solid floor covered with straw bedding during the finishing period (CS-S) and fully slatted flooring during the growing period and moved to fully slatted flooring covered with rubber strips during the finishing period (CS-RS). Bulls were offered ad libitum grass silage supplemented with concentrates during the growing period. During the finishing period, bulls were offered concentrates supplemented with chopped barley straw. There was no significant effect of floor type on total dry matter intake (DMI), feed conversion ratio, daily live weight gain or back fat depth during the growing and finishing periods. Compared with bulls accommodated on CS, RS and CS-RS, bulls accommodated on CS-S had a significantly lower straw DMI (P<0.01). Although bulls accommodated on CS and CS-S were significantly dirtier compared with those accommodated on RS and CS-RS on days 50 (P<0.05) and 151 (P<0.01), there was no effect of floor type on the cleanliness of bulls at the end of the growing and finishing periods. There was also no significant effect of floor type on carcass characteristics or meat quality. However, bulls accommodated on CS-S had a tendency for less channel, cod and kidney fat (P=0.084) compared with those accommodated on CS, RS and CS-RS. Overall, floor type had no effect on the performance, cleanliness, carcass characteristics or meat quality of growing or finishing beef cattle.     

欧洲球螋的检疫

北京出入境检验检疫局从美国进境旅客携带的石榴中检出欧洲球螋。了解欧洲球螋的基本特性,能为相关部门对其检疫鉴定提供参考依据。对欧洲球螋的相关文献进行了查阅和整理,详细介绍了欧洲球螋的分类地位、分布、形态特征及近似种等信息,我国出入境检验检疫部门对球螋属的截获情况,讨论了欧洲球螋的检疫意义。认为欧洲球螋在我国无分布且具有一定的入侵风险,口岸应对该虫引起足够的重视。