植物中表达口蹄疫病毒抗原研究进展

口蹄疫(foot-and-mouth disease,FMD)是由口蹄疫病毒(foot-and-mouth disease virus,FMDV)引起的一种急性、烈性、高度接触性传染病,严重危害畜牧养殖业健康发展。口蹄疫灭活疫苗是口蹄疫防控的主导产品,为控制口蹄疫流行起到了重要作用;但是也存在抗原不稳定、在生产制备过程中存在因病毒灭活不彻底而散毒的风险、生产成本较高等问题。与传统的微生物和动物生物反应器相比,通过转基因技术以植物作为生物反应器生产抗原蛋白,具有成本低廉、安全便捷、易于储运等一些优势,且无需蛋白提取纯化过程,可直接食用免疫;但也存在着表达量低、控制性差等问题。因此,通过植物生物反应器表达口蹄疫病毒抗原蛋白,可能是一种具有一定优势但仍需不断优化的疫苗生产手段。本文综述了在植物中表达活性蛋白的主要策略,以及通过植物生物反应器表达口蹄疫病毒抗原蛋白的研究进展,并讨论了目前面临的问题与挑战,以期为相关工作提供一定的借鉴和参考。     

The hippocampus as a cognitive graph

A theory of cognitive mapping is developed that depends only on accepted properties of hippocampal function, namely, long-term potentiation, the place cell phenomenon, and the associative or recurrent connections made among CA3 pyramidal cells. It is proposed that the distance between the firing fields of connected pairs of CA3 place cells is encoded as synaptic resistance (reciprocal synaptic strength). The encoding occurs because pairs of cells with coincident or overlapping fields will tend to fire together in time, thereby causing a decrease in synaptic resistance via long-term potentiation; in contrast, cells with widely separated fields will tend never to fire together, causing no change or perhaps (via long-term depression) an increase in synaptic resistance. A network whose connection pattern mimics that of CA3 and whose connection weights are proportional to synaptic resistance can be formally treated as a weighted, directed graph. In such a graph, a "node" is assigned to each CA3 cell and two nodes are connected by a "directed edge" if and only if the two corresponding cells are connected by a synapse. Weighted, directed graphs can be searched for an optimal path between any pair of nodes with standard algorithms. Here, we are interested in finding the path along which the sum of the synaptic resistances from one cell to another is minimal. Since each cell is a place cell, such a path also corresponds to a path in two-dimensional space. Our basic finding is that minimizing the sum of the synaptic resistances along a path in neural space yields the shortest (optimal) path in unobstructed two-dimensional space, so long as the connectivity of the network is great enough. In addition to being able to find geodesics in unobstructed space, the same network enables solutions to the "detour" and "shortcut" problems, in which it is necessary to find an optimal path around a newly introduced barrier and to take a shorter path through a hole opened up in a preexisting barrier, respectively. We argue that the ability to solve such problems qualifies the proposed hippocampal object as a cognitive map. Graph theory thus provides a sort of existence proof demonstrating that the hippocampus contains the necessary information to function as a map, in the sense postulated by others (O'Keefe, J., and L. Nadel. 1978. The Hippocampus as a Cognitive Map. Clarendon Press, Oxford, UK). It is also possible that the cognitive mapping functions of the hippocampus are carried out by parallel graph searching algorithms implemented as neural processes. This possibility has the great attraction that the hippocampus could then operate in much the same way to find paths in general problem space; it would only be necessary for pyramidal cells to exhibit a strong nonpositional firing correlate.     

Improvement of plant cryosection

Cryosection in plants is usually challenging because of the larger amounts of water contained in plant cell than animal cell.The formation of ice crystals within the plant cells easily destroys subcell...     

山西蟒河国家级自然保护区猕猴食源植物区系特征

于2012~2013年,以样带法、样方法和无样地法相结合,分4次对蟒河国家级自然保护区猕猴栖息地食源植物种类进行了实地调查,并分析了其区系特征。研究发现:(1)蟒河保护区猕猴栖息地内有维管植物659种,隶属102科374属,其中54科126属261种为猕猴的食源植物,占猕猴栖息地植物科、属、种总数的52.94%、33.69%和39.61%;蔷薇科是食源植物中包含种类最多的科,有16属39种,其次为豆科,含11属23种。(2)蟒河保护区内猕猴食源植物区系特征为:食源植物所在科有6个分布型和2个变型,所在属有13个分布型和6个变型;在属的分布类型中,温带性质分布类型的属占优势,有75个,占总属数的66.96%,其中北温带分布类型的属46个,占总属数的41.07%;热带性质分布类型的属有24个,地中海区、中亚、东亚和中国特有分布成分的属共有13个,分别占总属数的21.43%和11.61%,说明蟒河保护区内猕猴食源植物区系为暖温带性质。     

五裂红柱兰--云南兰科一新种

Cymbidiumisanorchidgenusmainlydistributedintropicaland subtropicalAsia,withsomespeciesextendingtoPapuaNewGuinea andAustralia.Altogether44specieswererecognizedbyDuPuyand Cribbin1988,ofwhichhalfthenumberweresaidtobefoundin China.ManyyearslaterthenumberofChinesespecieshadgoneup to29(Chen,1999),andtodayprobablyover40,includingboth newlydescribedspeciesandnewrecords.Thenewspeciesdescribed herewascollectedfromMaguanCountyinsoutheasternYunnan,wheretheplantswerefoundgrowingontreesorrocks.Theywer…     

黄河干流河岸带C4植物群落特征及其对水库生态效应的指示

于2008年9月16日至10月31日对黄河干流河岸带植物群落开展了系统调查。共采集高等植物124种,分属于32科、97属,其中C4植物9科、24属、34种,占科、属、种总数的28%、25%和27%。对该区域的研究结果还表明：（1）C4植物主要分布于单子叶植物纲的禾本科和莎草科,两者共占C4植物总种数的61%。（2）从上游到下游C4植物种数递增,但中游C4/C3比、C4植物密度和生物量要明显高于上游和下游。（3）C4植物种数及C4/C3比与海拔、年均气温、年均降水量及年均流量均有相关关系,C4植物生物量仅和年均降水量显著相关。（4）水库位置的C4/C3比要明显高于其临近样区,说明C4植物对水库干扰下河岸带植被的动态变化具有一定的指示作用。     

干涉合成孔径雷达监测湿地水位研究综述

湿地水位是表征湿地水文情势的重要指标,干涉合成孔径雷达(InSAR)监测湿地水位具有空间分辨率高、精度高、成本低和效益好等突出优势。本文简要介绍了InSAR监测湿地水位的先决条件,系统阐述了InSAR监测湿地水位技术的类型及其优缺点,重点探讨了InSAR监测湿地水位的影响因素。InSAR监测湿地水位须满足三大前提条件:1)存在非淹没水生植被;2)主要后向散射机制为双回波散射;3)干涉相干性超过一定的阈值。目前,该水位监测技术已从传统的InSAR技术发展到STBAS、MM和DSI等改进的InSAR技术,已由监测相对水位变化发展到监测绝对水位和水深时间序列。InSAR监测湿地水位的影响因素包括合成孔径雷达(SAR)的工作参数和湿地本身的特性。最后,指出该领域未来亟待加强的研究方向为:探讨该水位监测技术应用于更多具有不同后向散射特性及干涉相干性特征的其他生态区的潜力;开发多传感器、多轨道、多波段、多极化和多时相的InSAR新算法;引入新的SAR数据源;加强InSAR监测湿地水位的“副产品”,如湿地水文连通性、流向和流态等研究。     

Intein 介导的重组人AR DBD的原核可溶性表达、纯化及活性鉴定

雄激素受体通过DNA结合域与效应元件结合发挥作用,在以往的研究中多采用与GST或Protein A融合的方式对雄激素受体的DNA结合域(AR DBD)进行重组表达,但获得无融合标签的纯AR DBD的操作非常繁琐。现借助内含肽介导的自剪切作用经一步亲和层析得到纯度较高的无融合标签的AR DBD,以利于对其性质和功能的研究。通过PCR方法扩增了编码人雄激素受体520~644位氨基酸的核苷酸序列,将该序列克隆入pTWIN1融合表达载体,转化大肠杆菌BL21(DE3)后对诱导温度及IPTG浓度进行优化,重组蛋白几乎全部可溶表达。将可溶性部分吸附到几丁质亲和层析柱上,通过pH诱导的内含肽自剪切作用释放出不含融合标签的重组人AR DBD蛋白,凝胶阻滞分析证明该蛋白只特异性结合保守的雄激素响应元件(ARE),具备正常的生物学活性。     

新型抗结核分枝杆菌药物筛选模型的建立

为建立基于酶水平和细胞水平的新型抗结核分枝杆菌（Mycobacterium tuberculosis）药物的筛选模型,以M.tuberculosis H37Rv基因组DNA为模板,PCR特异性扩增异柠檬酸裂解酶（ICL）基因,构建表达载体,在E.coli BL21（DE3）中高效表达,使用N i2＋亲和层析柱纯化重组ICL,检测其活性。优化ICL酶反应条件,考察待筛选样品溶剂对酶活性的影响,建立ICL抑制剂酶水平筛选模型;考察与优化耻垢分枝杆菌（Mycobacterium smegma）在以乙酸盐为唯一碳源的培养基中的生长状况,建立基于M.sm egma的乙醛酸代谢途径抑制剂的细胞水平筛选模型;利用上述2种筛选模型对1 060种可能具有拮抗活性的微生物代谢样品进行初筛和复筛,两者筛选结果正相关性较好。     

运动对人体自由基代谢的影响

自由基代谢普遍存在于机体各组织。正常情况下,人体自由基的产生与清除处于平衡状态。而人体自由基产生过多或机体清除自由基能力下降将给机体带来损伤。本文采用文献资料法,阐述了自由基的类型、功能、自由基产生的机制以及抗氧化系统的种类等基本理论。通过对力竭运动、耐力运动和无氧运动3种不同形式的运动对自由基代谢及抗氧化酶活性的研究得出结论:不同的运动形式及负荷方式对体内自由基代谢及抗氧化酶活性将产生不同影响;运动对自由基代谢影响具有器官与组织差异性。这些研究成果为科学指导运动训练和健身活动、快速有效的消除运动性疲劳并增强运动能力提供重要的科学理论依据。