半干旱黄土高原地区春小麦地膜覆盖研究概述

在黄土高原半干旱地区春小麦上进行的地膜覆盖试验表明,地膜覆盖通过改善耕层土壤生态环境条件,即通过改善水,热状况,活化土壤养分,对提高水分和养分利用效率,实现粮食增产具有重要作用,但近年来在生产实践和科学实验中发现,不合理的长期全生育期地膜覆盖,因在作物生长前期和中期覆膜作物较不覆膜作物生长好,覆膜作物在生长期水分蒸腾损失严重,土壤水分的蒸散（蒸发＋蒸腾）损失远比不覆膜土壤严重,在作物生长后期降水少或没有补充灌溉时,会产生严重的水分肋迫现象,显著抑制小穗分化和灌浆,最终导致收获得指数和产量下降,同时,地膜覆盖的增产作用在一定程度上是以耗竭土壤肥力,特别是在有机物质为代 的,因此,不正确的地膜覆盖（如全生育期的地膜覆盖）,不仅有时起不到显著的增产作用,而且易造成土壤养分,特别是土壤中硝态氮的累积和损失,肥料利用效率降低,土壤生态条件恶化,下降,难以持续高产,因此在确定地膜覆盖范式时,必须要考虑底墒,作物生育期降水,地膜覆盖的阶段性和氮肥的施用等。     

精液源性病毒感染增强因子SEVI-HIV性传播中的重要因素

精液源性病毒增强因子(Semen-derived enhancer of viral infection,SEVI)是前列腺酸性磷酸酶(Prostatic acidphosphatase,PAP)位于PAP248-286的多肽片段,可增强人免疫缺陷病毒(Human immunodeficiency virus,HIV)的感染性。SEVI促进HIV感染的作用机制包括:①富含阳离子氨基酸残基的SEVI能通过静电作用降低HIV病毒颗粒与靶细胞之间的静电排斥;②SEVI在人体液中呈无序状态,利于病毒与靶细胞膜相互作用;③SEVI直接捕获HIV颗粒,提高病毒在靶细胞表面沉降速度,促进病毒与靶细胞的吸附和融合。目前已发现能抑制SEVI活性的物质包括:绿茶来源的EGCG(没食子儿茶素没食子酸酯)、氨基喹啉类小分子化合物Surfen、ThT类似物BTA-EG6等,能通过阻断HIV与SEVI结合或阻止其淀粉样纤维的形成,降低SEVI的病毒感染增强作用。研究SEVI的生物学特性及作用机制对防治HIV感染具有较为重要的指导意义。     

禄丰古猿地点的小哺乳动物化石

过去十年,在禄丰古猿地点作了多次的发掘和筛洗,采集到包括食虫类,翼手类,啮齿类和兔形类在内的一千余件标本,使这一小哺乳动物的化石组合从1979年首次报道的6种增加到了38种,成为我国南方新第三纪中期最丰富而有代表性的小哺乳动物群。材料的初步鉴定表明:动物群中有代表我国首次发现的化石科和属;并有相当数量与华北、印巴次大陆和欧洲有密切亲缘关系的类型;其地质时代属最晚中新世保德期,相当于欧洲陆相哺乳动物分期的土洛里期(Turolian)。     

六种检测猪瘟病毒方法的比较

【目的】本研究旨在比较6种检测猪瘟病毒方法的优缺点。【方法】应用病毒分离、胶体金免疫层析试纸条、抗原捕捉ELISA、反转录-聚合酶链式反应(RT-PCR)、TaqMan荧光定量RT-PCR(RT-qPCR)和反转录-环介导等温扩增方法(RT-LAMP)等6种方法,分别对50份疑似猪瘟病料中的猪瘟病毒(Classical swine fevervirus,CSFV)进行检测。【结果】结果表明:RT-qPCR和RT-LAMP方法检出阳性样品数为13份,RT-PCR为11份,病毒分离为10份,抗原捕捉ELISA为9份,胶体金试纸条为8份;6种方法均检测为阳性8份,均为阴性37份。【结论】结果提示,在对猪瘟病毒进行检测时,RT-qPCR、RT-LAMP和RT-PCR由于其灵敏性高,可作为首选检测方法,但操作时需要避免假阳性的出现;病毒分离方法虽然操作繁琐,但结果准确,是确诊猪瘟必不可少的检测方法;抗原捕捉ELISA和胶体金试纸条检测时间较短,由于其敏感性较低所限,主要用于对畜群进行检测,不适合个体检测。     

毕赤酵母发酵生产颗粒性乙肝表面抗原的条件优化

乙型肝炎病毒的流行对人们的生命健康造成了极大的威胁, 而有效准确的诊断和预防性疫苗是阻止其流行的主要手段, 乙肝表面抗原是诊断试剂和疫苗的主要成分。本试验在构建稳定表达HBsAg的毕赤酵母菌株后, 对其发酵条件进行了研究。采用摇瓶分批培养方法, 探讨了不同培养基、溶解氧、诱导物甲醇的浓度以及pH值等因素对菌体生长与重组蛋白表达的影响。在10 L发酵罐上采用分批补料培养的方法研究了进行扩大培养生产重组HBsAg。结果表明, FBS无机盐合成培养基是理想的工业发酵培养基, 溶解氧对菌体的生长与表达有显著的影响, 甲醇诱导最佳终浓度为1% (V/V), 发酵的最适pH值为5.4~6.0。发酵罐放大培养后, ELISA和 SDS-PAGE分析表明重组HBsAg获得了高效表达, 最终菌体生物量达到310 OD600, 表达量达到27 mg/L。电子显微镜观察表达重组乙肝抗原可以自组装为22 nm类病毒颗粒, 为HBV的新一代早期血清学诊断和疫苗的大规模生产提供了一定的参考。     

Development of mechanistically based model for simulating soluble microbial products generation in an aerated/non-aerated SBR

Soluble microbial products (SMPs) are considered as the main organic components in wastewater treatment plant effluent from biological wastewater treatment systems. To investigate and explore SMP metabolism pathway for further treatment and control, two innovative mechanistically based activated sludge models were developed by extension of activated sludge model no.3 (ASM3). One was the model by combining SMP formation and degradation (ASM3-SMP model) processes with ASM3, and the other by combining both SMP and simultaneous substrate storage and growth (SSSG) mechanisms with ASM3 (SSSG-ASM3-SMP model). The detailed schematic modification and process supplements were introduced for comprehensively understanding all the mechanisms involved in the activated sludge process. The evaluations of these two models were demonstrated by a laboratory-scale sequencing batch reactor (SBR) operated under aerated/non-aerated conditions. The simulated and measured results indicated that SMP comprised about 83% of total soluble chemical oxygen demand (SCOD) in which biomass-associated products (BAPs) were predominant compared with utilization-associated products (UAPs). It also elucidated that there should be a minimum SMP value as the reactive time increases continuously and this conclusion could be used to optimize effluent SCOD in activated sludge processes. The comparative results among ASM3, ASM3-SMP and SSSG-ASM3-SMP models and the experimental measurements (SCOD, ammonia and nitrate nitrogen) showed clearly the best agreement with SSSG-ASM3-SMP simulation values (R = 0.993), strongly suggesting that both SMP formation and degradation and SSSG mechanisms are necessary in biologically activated sludge modeling for municipal wastewater treatment.     

Human umbilical cord-derived MSC culture: the replacement of animal sera with human cord blood plasma

Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) hold great potential for their therapeutic use in various clinical diseases. Many publications have reported on human blood-derived alternatives to animal serum for culturing mesenchymal stem cells, such as human serum, allogenic umbilical cord blood serum, and human platelet derivatives. However, it is not clear whether human umbilical cord blood plasma (UCBP), as the surplusage of umbilical cord blood mesenchymal stem cell extraction, could be used. In this study, in order to make the best of umbilical cord blood, the human UCBP was dialyzed to replace fetal bovine serum (FBS) in the culture medium. hUC-MSCs were cultured in the new medium. Cell growth rate, specific biomarkers, and differentiation properties were detected to characterize the cell proliferation and MSC-specific properties. The hUC-MSCs cultured in such derived medium were verified with proliferation rate, cluster differentiation markers, cell cycle, as well as differentiation capabilities. Such dialyzed human UCBP is fully comparable with, if not superior to, FBS in deriving and culturing hUC-MSCs.     

猪消化道中产苯乳酸乳酸菌的益生特性研究

【目的】建立一种简单有效的产苯乳酸乳酸菌的筛选方法,并筛选到高产苯乳酸的乳酸菌。【方法】菌株经过添加了苯丙氨酸的培养基厌氧培养后,利用高效液相色谱法检测发酵液中苯乳酸的含量。【结果】从猪的消化道中共分离得到31株产苯乳酸的乳酸菌,其中菌株R53的苯乳酸产量最大,为321.7 mg/L。菌株R53对.OH、O2和DPPH都有清除能力,清除率分别达到11.2%、52.7%和63.2%。同时R53也能降低培养基中胆固醇的含量,清除率为32.5%。【结论】乳酸菌R53经菌落形态、细胞形态、生化反应实验、16S rDNA测序,最终确定为植物乳杆菌。植物乳杆菌R53能产生苯乳酸,具有清除胆固醇和抗氧化能力。     

The murine pan T cell marker CD96 is an adhesion receptor for CD155 and nectin-1

The CD155 ligand CD96 is an immunoglobulin-like protein tentatively allocated to the repertoire of human NK receptors. We report here that the CD96/CD155-interaction is preserved between man and mouse although both receptors are only moderately conserved in amino acid sequence. Moreover, murine CD96 (mCD96) binds to nectin-1, a receptor related to CD155. Applying newly generated monoclonal antibodies specifically recognizing mCD96, an expression profile is revealed resembling closely that of human CD96 (hCD96) on cells of hematopoietic origin. A panel of anti-mCD96 but also recently established anti-mCD155 antibodies effectively prevents formation of CD96/CD155-complexes. This was exploited to demonstrate that the only available receptor for mCD96 present on thymocytes is mCD155. Moreover, T cell adhesion to insect cells expressing mCD155 is blocked by these antibodies depending on the T cell subtype. These results suggest a function of the CD96/CD155-adhesion system in T cell biology.     

Permeability of the infective juveniles of Steinernema carpocapsae to glycerol during osmotic dehydration and its effect on biochemical adaptation and energy metabolism

Permeability of the sheath and cuticle of the infective juveniles (IJs) of Steinernema carpocapsae to glycerol and its effect on biochemical adaptation of the IJs to osmotic dehydration were examined by incubating both sheathed and exsheathed IJs in glycerol-d5 solution then monitoring the changes in levels of deuterium labelled and non-labelled glycerol and trehalose. Energy metabolism of the IJs during osmotic dehydration and subsequent rehydration and the effect of the permeated glycerol on this process were investigated by examining and comparing the changes in mean dry weight and key biochemical composition of the IJs dehydrated in glycerol and sodium chloride solutions. The results show: (1) similarly to evaporative dehydration, osmotic dehydration induces IJs to synthesise the protectants glycerol and trehalose; (2) glycerol permeates the sheath and the cuticle into the body of IJs during dehydration in glycerol solution. Part of the permeated glycerol plays a role as protectant like that synthesised by IJs from their energy reserve materials while part is incorporated into trehalose; (3) the sheath reduces the rate of permeation of glycerol and therefore affects the equilibrium glycerol and trehalose levels of the IJs and also the time needed to reach the equilibrium levels; (4) the reduction in mean dry weight and lipids of the IJs during dehydration in glycerol solution is substantially less than those dehydrated in sodium chloride solution. Both the total protectant level and the ratio of glycerol to trehalose of the IJs dehydrated in glycerol solution are higher than those dehydrated in sodium chloride solution; (5) glycogen reserves of the IJs play a role as a buffer reservoir of the protectants during both dehydration and rehydration but the principal sources of the protectants during dehydration are more likely to be lipids and proteins rather than glycogen.