A GDP/GTP exchange factor involved in linking a spatial landmark to cell polarity

In both animal and yeast cells, signaling pathways involving small guanosine triphosphatases (GTPases) regulate polarized organization of the actin cytoskeleton. In the budding yeast Saccharomyces cerevisiae, the Ras-like GTPase Bud1/Rsr1 and its guanosine 5'-diphosphate (GDP)/guanosine 5'-triphosphate (GTP) exchange factor Bud5 are involved in the selection of a specific site for growth, thus determining cell polarity. We found that Bud5 is localized at the cell division site and the presumptive bud site. Its localization is dependent on potential cellular landmarks, such as Bud3 and Axl2/Bud10 in haploid cells and Bud8 and Bud9 in diploid cells. Bud5 also physically interacts with Axl2/Bud10, a transmembrane glycoprotein, suggesting that a receptor-like transmembrane protein recruits a GDP/GTP exchange factor to connect an intrinsic spatial signal to oriented cell growth.     

牛冠状病毒4H12/1D4单链基因片段在大肠杆菌中的表达

用ＥｃｏＲＩ酶切ＰＲ５Ｂ４质粒，采用“Ｖ”字形内槽电洗脱法回收约０．８０４Ｋｂ牛冠状病毒基因工程抗体４Ｈ１２／１Ｄ４单链基因片段，并将其插入载体质粒ＰＥＴ－１７ｂ的ＥｃｏＲＩ位点构成重组质粒ＰＥＴ－Ｄ４，将重组质粒转化ＤＨ５α感受态细胞，在ＩＰＴＧ的诱导下表达，细菌裂解物经ＳＤＳ－ＰＡＧＥ电泳筛选，发现含ＰＥＴ－Ｄ４细菌经诱导新增一条约２８ＫＤα蛋白带，该蛋白带与设计基因工程抗体的大小相符，经光密度扫描，表达量约占菌体总蛋白的１４％     

双氰胺减少铵态氮肥施用后潮土N2O排放的机制

为探讨双氰胺（DCD）减少铵态氮肥施用后氧化亚氮（N₂O）的排放机制,通过开展好氧培养试验,研究DCD配施铵态氮（NH₄⁺-N）或亚硝态氮（NO₂^--N）对潮土土壤N₂O排放的影响,同时添加不同浓度NO₂^--N模拟NO₂^--N累积对N₂O和CO₂排放的影响。结果表明： DCD仅对NH₄⁺-N氧化过程中N₂O排放有抑制作用,对NO₂^--N还原过程中产生的N₂O没有影响;培养前7 d,DCD显著抑制NH₄⁺-N的氧化过程,降低净硝化速率,而在添加NO₂^--N土壤中加入DCD后净硝化速率显著增加,培养30 d后,DCD对NH₄⁺-N和NO₂^--N氧化过程均没有影响;添加外源NO₂^--N明显促进了N₂O排放,其排放通量显著高于不施肥的对照处理; N₂O累积排放量同NO₂^--N浓度呈正相关,CO₂累积排放量同NO₂^--N浓度呈显著负相关。研究表明,DCD可以避免NO₂^--N大量累积而产生的毒害作用,但仅对氨氧化过程N₂O减排有效果,因此亟待研发适于抑制NO₂^--N产生N₂O的新型抑制剂。     

荧光抗体在热带作物小粒种咖啡的C_3/C_4属性鉴别中的应用

用从烟草提纯的 1,5-二磷酸核酮糖 ( Ru BP)羧化酶制备兔抗 Ru BP羧化酶抗体 ,并以异硫氰酸盐荧光素 ( FITC)标记抗体 .采用直接免疫荧光法对典型 C3植物水稻、C4 植物甘蔗和小粒种咖啡等进行了 Ru BP羧化酶的组织化学定位 .结果表明 :C3和 C4 植物叶切片中 Ru BP羧化酶的分布明显不同 ,C3植物的特异荧光位于叶肉细胞 ,C4 植物的特异荧光绝大部分位于维管束鞘细胞 ;小粒种咖啡的特异荧光仅分布在叶肉细胞 .因此认为 ,小粒种咖啡应属 C3植物     

Binding of HTLV-III/LAV to T4+ T cells by a complex of the 110K viral protein and the T4 molecule

Human T-lymphotropic virus type III (HTLV-III) or lymphadenopathy-associated virus (LAV) is tropic for human T cells with the helper-inducer phenotype, as defined by reactivity with monoclonal antibodies specific for the T4 molecule. Treatment of T4+ T cells with monoclonal antibodies to T4 antigen blocks HTLV-III/LAV binding, syncytia formation, and infectivity. Thus, it has been inferred that the T4 molecule itself is a virus receptor. In the present studies, the surfaces of T4+ T cells were labeled radioactively, and then the cells were exposed to virus. After the cells were lysed, HTLV-III/LAV antibodies were found to precipitate a surface protein with a molecular weight of 58,000 (58K). By blocking and absorption experiments, this 58K protein was identified as the T4 molecule. No cell-surface structures other than the T4 molecule were involved in the antibody-antigen complex formation. Two monoclonal antibodies, each reactive with a separate epitope of the T4 molecule, were tested for their binding capacities in the presence of HTLV-III/LAV. When HTLV-III/LAV was bound to T4+ T cells, the virus blocked the binding of one of the monoclonal antibodies, T4A (OKT4A), but not of the other, T4 (OKT4). When HTLV-III/LAV was internally radiolabeled and bound to T4+ T cells which were then lysed, a viral glycoprotein of 110K (gp110) coprecipitated with the T4 molecule. The binding of gp110 to the T4 molecule may thus be a major factor in HTLV-III/LAV tropism and may prove useful in developing therapeutic or preventive measures for the acquired immune deficiency syndrome.     

应用3种方法评价4种新氯化烟碱类杀虫剂对棉花粉蚧的毒力

【目的】探讨棉花粉蚧Phenacoccus solenopsis Tinsley的化学防治,筛选高效的防治药剂.【方法】采用浸叶法、浸渍法和药膜法评价吡虫啉、啶虫脒、噻虫嗪和烯啶虫胺4种新氯化烟碱类杀虫剂对棉花粉蚧3龄若虫的毒力.【结果和结论】40 mg·L-1噻虫嗪处理24和48 h后3龄若虫的死亡率:浸叶法为90.0%、98.8%,浸渍法为98.9%、100.0%,药膜法为85.8%、85.8%.应用浸叶法测得的4种杀虫剂对3龄若虫的相对毒力为噻虫嗪啶虫脒烯啶虫胺吡虫啉,浸渍法依次为噻虫嗪吡虫啉啶虫脒烯啶虫胺,药膜法依次为噻虫嗪啶虫脒吡虫啉烯啶虫胺.3种方法测定结果均显示噻虫嗪对棉花粉蚧有相对较高的毒力.3种毒力测定方法中,就吡虫啉而言以浸渍法测定的毒力最高,药膜法次之,浸叶法最低;啶虫脒以浸渍法和药膜法相近,浸叶法较低;噻虫嗪浸渍法较高,药膜法和浸叶法较低;烯啶虫胺3种方法测定的毒力相近.浸渍法较好地反映了新氯化烟碱类杀虫剂对粉蚧的触杀、通过内吸而导致的胃毒等综合作用.     

Divergent responses of tiller and grain yield to fertilization and fallow precipitation: Insights from a 28-year long-term experiment in a semiarid winter wheat system

Tillering is an important phenological stage, which is strongly related to the yield in spike components and final grain yield during winter wheat growth. Precipitation during the fallow season (fallow precipitation) influences tillering in winter wheat on the semi-arid Chinese Loess Plateau. However, little work has been done regarding tiller number changes under various types of fertilization and amounts of fallow precipitation on a long-term scale. Effects of fallow precipitation and fertilization on tiller were investigated in a winter wheat (Triticum aestivum L.) system in a 28-year field study (1990 to 2017) in a semiarid agro-ecosystem. Tiller number, spike number and grain yield were measured in four fertilization conditions: control without fertilizer (CK); mineral nitrogen fertilizer alone (N); mineral phosphorus fertilizer alone (P); mineral nitrogen and phosphorus fertilizer together (NP). Based on the long-term annual fallow precipitation, dry years (<mean annual fallow precipitation) and wet years (>mean annual fallow precipitation) were distinguished. Phosphorus fertilization alone significantly increased the mean annual tiller number (23%), and the increase in tiller number was higher in wet years (29%) than in the dry years (17%). However, nitrogen fertilization alone had little effect on mean tiller number, while nitrogen and phosphorus together significantly increased mean annual tiller number (30%), mean tiller number in wet years (45%) and mean tiller number in dry years (17%). Tiller number was significantly and positively correlated with fallow precipitation in dry years for all fertilizer treatments, whereas it was weakly and either positively or negatively correlated with fallow precipitation in wet years depending on the treatment. This study found positive correlations between tiller number and fallow precipitation in the CK and NP treatments, and it found negative correlations between tiller number and fallow precipitation in the treatments with nitrogen fertilization alone or phosphorous fertilization alone in wet years. Understanding the impacts of fallow precipitation and fertilization on tiller development shed light on ways to improve crop production in rain-fed agricultural regions.     

不同小麦品种苗期对混合形态氮素营养的反应

采用水培方法研究了不同基因型小麦对不同NH 4/NO-3 混合比例营养的反应。结果表明 ,增铵营养对 40个基因型小麦的早期生长均有促进作用 ,但各个基因型的表现不尽一致。与单一NO-3 营养相比 ,增铵营养显著提高了茎干重、总干重、单株分蘖数、叶片叶绿素含量、植株氮含量和氮积累量 ,但对根干重没有影响。营养液中 2 5 %～ 5 0 %的NH 4比例对植株生长更为有利。与单一NO-3 营养相比 ,单一NH 4营养下植株的叶绿素含量和氮含量较高 ,但茎干重、总干重、单株分蘖数和氮积累量较低。分析表明 ,植株在增铵营养中干物质积累的增加与单株分蘖数和氮积累量相关。     

靶向加工番茄elF4E1的CRISPR/Cas9载体有效性验证

【目的】验证基于CRISPR/Cas9系统构建的靶向编辑加工番茄(Solanum lycopersicum) eIF4E1基因载体的有效性,为CRISPR/Cas9系统在培育PVY抗性植株中的应用提供技术支持。【方法】构建靶向编辑番茄真核翻译起始因子elF4E1基因的CRISPR/Cas9系统表达载体,用农杆菌渗透法瞬时转化番茄植株,PCR扩增已转化植株靶位点周围DNA序列后用HaeⅢ进行酶切,回收未切开的条带与pGEM-T载体连接后进行单克隆测序。【结果】对测得的9个克隆序列进行比对分析,在PAM (protospacer adjacent motifs)上游的6~8 bp的碱基处均发生突变,并且都为单碱基的替换,导致多肽链中单个氨基酸的替换。【结论】利用CRISPR/Cas9基因组编辑系统构建的载体能够特异性地靶向加工番茄eIF4E1基因,为利用CRISPR/Cas9系统敲除eIF4E1基因,获得抗PVY病毒的番茄育种材料奠定了基础。     

Toll样受体4(896A/G)基因多态性与溃疡性结肠炎易感性的Meta分析

目的 研究Toll样受体4(TLR4)896A>G位点基因多态性与溃疡性结肠炎(UC)发病风险的关系。方法 检索相关英文及中文数据库筛选文献,以OR值及95%CI为效应指标,运用RevMan 5.2和Stata 11.0进行Meta分析和敏感性分析,并采用Egger′s test评价发表偏倚。结果 研究共纳入14篇文献,包括2 174例UC患者和3 134例对照者。Meta分析结果表明携带等位基因G的人群较携带等位基因A的人群患UC的风险性增加,在各个基因模型下均差异有统计学意义[等位基因模型G/A:OR=1.41,95%CI(1.21~1.66),P<0.000 1;显性模型AG+GG/AA:OR=1.37,95%CI(1.16~1.62),P=0.000 2;隐性模型GG/AA+AG:OR=3.74,95%CI(1.78~7.86),P=0.000 5;共显性模型AG/AA:OR=1.42,95%CI(1.07~1.87),P=0.01;共显性模型GG/AA:OR=3.85,95%CI(1.82~8.12),P=0.000 4]。亚组分析结果表明,在等位基因模型G/A、显性模型AG+GG/AA、共显性模型AG/AA下,差异仅在白种人中存在。结论 TLR4 896A>G基因多态性与UC易感性相关,携带等位基因G会增加白种人患UC的发病风险。由于该研究纳入有关亚洲人群及非洲人群的文献数量较少,相关结果需要更多研究予以验证。     

夜间增温下施硅对稻田CH4好氧氧化及其氮响应的影响

【目的】研究硅肥对增温稻田甲烷(CH₄)好氧氧化速率的影响效应,为探索未来全球变暖背景下稻田温室气体减排措施提供科学依据。【方法】采用田间开放式增温系统对稻田土壤进行夜间增温,共设4个处理：夜间常温不施硅(CK)、夜间增温不施硅(NW)、夜间常温施硅(Si)和夜间增温施硅(NW+Si)。采集上述处理4年后的耕层根际土和非根际土,在无氮添加和氮添加(NH₄⁺、NO₃^-和尿素)条件下进行室内培养,采用¹³CH₄标记方法,研究稻田CH₄好氧氧化速率和固碳特征及其对氮肥的响应。【结果】Si处理稻田土壤的总有机碳和水溶性有机碳含量分别为23.2 g/kg和216.7 mg/kg,较CK稻田提高10.5%和26.7%;而NW处理的总有机碳和水溶性有机碳则分别较CK稻田降低11.9%和9.9%。施硅处理(Si和NW+Si)根际土的CH₄好氧氧化速率显著高于不施硅处理(CK和NW)(P<0.05),其...     

淮河流域稻麦轮作系统CH4通量模拟及减排研究

为研究气候变化下不同管理措施对淮河流域稻麦轮作农田生态系统CH₄通量的影响,通过参数率定后的DNDC(DeNitrification-DeComposition)模型,估算了淮河流域历史时期(2000—2020年)及未来(2021—2049年)RCP4.5(中等排放强度情景)和RCP8.5(高排放强度情景)两种情景下稻麦轮作农田CH₄通量时空分布特征,评估了未来气候变化下多种田间管理措施对流域CH₄的减排能力。结果表明：淮河流域历史时期区域CH₄通量平均排放强度为125.3 kg·hm^-2,未来两种情景(RCP4.5和RCP8.5)下区域CH₄通量平均排放强度分别为140.5 kg·hm^-2和150.5 kg·hm^-2,总体均呈显著上升趋势(P<0.01)。空间上,未来两种情景下CH₄通量空间分布特征相似,均呈现南部和西北部地区CH₄通量高,东北部和中西部地区CH...     

RNA病毒诱导的烟草WRKY转录因子基因的应急表达

植物和病毒在基因水平上的互作是植物感病和抗病的分子基础。以模式植物烟草及其3种RNA病毒（马铃薯Y型病毒,Potato virus Y,PVY;烟草花叶病毒,Tobacco mosaic virus,TMV;黄瓜花叶病,Cucumber mosaic virus,CMV）为试材,旨在研究受病毒共同诱导、并可能在植物抗病反应中具有重要功能的转录因子基因。试验首先获得10个受病毒诱导的烟草同源基因。在比较了3种病毒侵染、低温和盐害协迫以及逆境信号物质(茉莉酸甲酯与水杨酸)处理对上述基因表达的影响后发现, 3种RNA病毒所诱导的植物基因有所不同。但属于WRKY基因家族的06G基因受3种病毒的共同、高效诱导,其表达水平与叶片发育程度呈负相关。研究结果表明, 该基因在植物病毒病发生及植物抗病分子育种中可能有重要意义。     

Development of a method using multispectral imagery and spatial pattern metrics to quantify stress to wheat fields caused by Diuraphis noxia

The Russian wheat aphid, Diuraphis noxia, is an important pest of winter wheat, Triticum aestivum, and barley, Hordeum vulgare that has caused an annual economic loss estimated at over 1 billion dollars since it first appeared in the United States. The objective of this study was to determine the potential of combining multispectral imagery with spatial pattern recognition to identify and spatially differentiate D. noxia infestations in wheat fields. Multispectral images were acquired using an MS3100-CIR multispectral camera. D. noxia, drought, and agronomic conditions were identified as major causes for stresses found in wheat fields. Seven spatial metrics were computed for each stress factor. The analysis of spatial metrics quantitatively differentiated the three types of stress found within wheat fields. Detection and differentiation of wheat field stress may help in mapping stress and may have implications for site-specific monitoring systems to identify D. noxia infestations and help to target pesticide applications.     

干季中云南松对纵坑切梢小蠹伴生菌(Leptographium yunnanense)抗性的变化

利用云南半帚孢测试了干季中云南松抗性的变化规律。结果表明,云南松抗性的相对强弱与降雨量及环境温度均表现出一定程度的负相关关系,相关系数分别为r=-0.7798和r=-0.4627,|r0.05|=0.811,P>0.05。在干季前期,温度较低,降雨量偏少,松树的针叶及韧皮含水量较低,伴生菌的生长力较低,云南松的抗性相对增强,这一时期内纵坑切梢小蠹危害较轻;而干季后期,温度逐渐升高,降雨量也有所增加,松树含水量较高,伴生菌的生长力增强,云南松的抗性相对减弱,因此该时期内纵坑切梢小蠹的蛀干危害较严重。     

QTLMapping forAdult-Plant Resistance to Stripe Rust in a CommonWheat RIL Population Derived from Chuanmai 32/Chuanyu 12

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a devastating wheat disease worldwide. The Chinese wheat cultivar Chuanmai 32 has shown stable resistance to stripe rust for 10 yr in Sichuan Province, a hotspot for stripe rust epidemics. The objective of the present study was to map quantitative trait loci (QTL) for adult-plant resistance (APR) to stripe rust in a population of 140 recombinant inbred lines (RILs) derived from Chuanmai 32/Chuanyu 12. Field trials were conducted in Chengdu and Yaan, Sichuan, from 2005 to 2008, providing stripe rust reaction data for 6 environments. 797 simple sequence repeat (SSR) markers were screened for association with stripe rust reaction, initially through bulked segregant analysis (BSA). Based on the mean disease values averaged across environments, the broad-sense heritability of maximum disease severity (MDS) was 0.75. Two QTLs for stripe rust resistance were detected by composite interval mapping (CIM). They were designated QYr.caas-3BL and QYr.caas-3BS and explained from 6.6 to 20.1%, respectively, of the phenotypic variance across environments. QYr.caas-3BL came from Chuanmai 32; QYr.caas-3BS with lower effect was from the susceptible parent Chuanyu 12. Both QTLs appear to be new.     

江淮丘陵区塘坝灌溉能力估算及其演变特征

目的探究氮素调控对江淮丘陵地区冬小麦—夏玉米一年两熟(麦玉两熟) N₂O排放及产量的影响,为该地区小麦和玉米稳产减排提供理论依据。方法以江淮丘陵地区麦玉两熟为研究对象,设置不施氮肥(CK)、常规施氮(CN)、生物炭与氮肥配施(SN)、硝化抑制剂与氮肥配施(XN)和叶面喷肥(PN) 5个处理,采用静态箱—气相色谱法,分析不同氮素调控措施下土壤N₂O排放和作物产量变化。结果土壤N₂O排放呈季节性变化,主要集中在施肥和降雨后的15 d内,玉米季是排放高峰期。与CN处理相比,小麦季XN和SN处理的N₂O累积排放量分别显著降低46.07%和25.10%,玉米季XN、SN和PN处理的N₂O累积排放量分别显著降低70.70%、64.01%和9.87%。从周年排放看, XN和SN处理的N₂O累积排放量比CN处理分别显著降低59.36%和46.21%,PN与CN处理间无显著差异。与CN处理相比,XN和SN处理的作物周年产量分别显著增加13.35%和11.27%,N₂O排放系数分别显著降低59.50%和46.28%。结论综合考虑N₂O排放和作物产量,硝化抑制剂与氮肥配施可作为江淮丘陵地区麦玉两熟稳产减排的最佳氮肥调控措施。     

六溴环十二烷短期暴露对红鳍笛鲷幼鱼甲状腺激素T3和T4含量的影响

为研究六溴环十二烷(HBCD)短期暴露对红鳍笛鲷的甲状腺素干扰效应及相关机理,实验室条件下分别将红鳍笛鲷幼鱼暴露于3个不同浓度的HBCD(8.6、43.0、215μg·L-1)溶液中24、48、96 h后,以肝脏和脑组织中三碘甲腺原氨酸(T3)和四碘甲腺原氨酸(T4)含量及T3/T4比值为生物标志物,评价HBCD短期暴露对红鳍笛鲷肝、脑组织甲状腺功能的影响。结果表明,HBCD对红鳍笛鲷幼鱼肝、脑组织甲状腺具有明显的干扰作用,且8.6、43.0μg·L-1浓度暴露下对T3、T4含量以诱导作用为主,215μg·L-1浓度暴露下短时间内表现为极显著的诱导作用(P0.01),随暴露时间延长则表现为极显著的抑制作用(P0.01)。此外,HBCD暴露过程中,肝组织T3/T4比值均极显著低于对照组(P0.01),且呈明显的时间-效应和剂量-效应关系;脑组织T3/T4比值则随暴露浓度和暴露时间呈现较大差异,主要表现为短时间暴露T3/T4比值高于对照组、长时间暴露T3/T4比值低于对照组。研究表明,红鳍笛鲷肝脏和脑组织甲状腺素T3、T4含量及T3/T4比值对实验室3种浓度的HBCD胁迫均具有足够的灵敏度,在一定程度上可为环境中甲状腺激素干扰物的筛选和生态风险评价提供重要的科学依据。