植物系统获得性抗性的分子机理

系统获得性抗性(systemic acquired resistance, SAR)是水杨酸(salicylic acid,SA)介导的植物对病原物的广谱抗病反应,NPR1和WRKY是SA信号传递过程中的重要转录因子.SAR的发生需要可移动信号(mobile signal)由局部到系统的长途运输,水杨酸甲酯(methyl salicylate, MeSA)和茉莉酸(jasmonic acid,JA)是两种可能的可移动信号.     

中国裸子植物的多样性和地理分布

<正>郑万钧和傅立国(1978)在《中国植物志》(FRPS)第七卷中将裸子植物分为4纲12科。这4个纲分别是苏铁纲、银杏纲、松杉纲和盖子植物纲,对应于Pilger(1926)的4个目,与Pilger和Meilchior(1954)的不同在于把银杏科从苏铁纲中独立为银杏纲,红豆杉科从松杉纲中独立为红豆杉纲(附表1)。FRPS记载中国产裸子植物有11科,分别是苏铁科(Cycadaceae)、银杏科(Ginkgoaceae)、松科(Pinaceae)、杉科(Taxodiaceae)、柏科(Cupressaceae)、罗汉松科(Podocarpaceae)、三尖杉科(Cephalotaxaceae)、南洋     

Harpin_(Pss)诱导的烟草早期防卫反应及钙的参与

Harpin_(Pss)可引发烟草过敏反应。超氧化物歧化酶能抑制,而过氧化氢酶不能抑制harpin_(Pss)诱导产生的这个反应,表明是超氧阴离子(O_2~-)是harpin_(Pss)诱导的烟草过敏反应的必要因子。Harpin_(Pss)还可引起烟草悬浮细胞活性氧的释放和胞外碱性化这两个早期防卫反应。Diphenylene iodonium能消除这种活性氧的诱导,这提示harpin_(Pss)可能是通过诱导NADPH氧化酶而产生O_2~_的。EGTA在无Ca~(2 )培养基中,能消除harpin_(Pss)诱导的烟草悬浮培养物的这两种防卫反应,再向培养基加Ca~(2 ),可恢复harpin_(Pss)的效应。LaCl_3、verapamil、新霉素、U-73122和LiCl也能抑制harpin_(Pss)诱导的这些反应,这表明由Ca~(2 )通道介导的Ca~(2 )内流和胞内Ca~(2 )库中Ca~(2 )的释放也参与了harpin_(Pss)诱导的早期防卫反应和过敏反应。在加harpin_(Pss)后很长时期内加放线菌素D、环己亚胺,都能抑制由它引发的过敏性细胞坏死过程,但它们对harpin_(Pss)诱导的活性氧的产生没有影响。表明O_2~-只是harpin_(Pss)诱发过敏性细胞凋亡的一个促发信号,过敏反应是更复杂的过程,需有基因持续地表达。     

表达绿色荧光蛋白嵌合狂犬病病毒HEP-GFP株的拯救

狂犬病毒(Rabies Virus,RV)是人和犬、猫等多种动物狂犬病的病原,其基因组是单股负链RNA,基因组结构为3'-核蛋白(N)基因-磷蛋白(P)基因-基质蛋白(M)基因-糖蛋白(G)基因-大蛋白(L)基因-5'.     

唇形科鼠尾草属的物种多样性与分布

为全面了解唇形科鼠尾草属(Salvia)植物的多样性和分布格局及其形成机制, 作者查阅了国际权威生物多样性信息网站(GBIF, The Plant List)、中国数字植物标本馆(CVH)、教学标本资源共享平台和中国自然保护区标本资源共享平台中该属物种名称及标本采集信息, 以及国内32家标本馆的标本, 分析并绘制其物种分布图。结果显示, 具有明确地理坐标的世界和中国分布信息分别有57,674条和11,596条, 已接受种名952个。在世界范围内, 以中南美洲(510种)物种数量最多, 其次是西亚(270种)、欧洲(117种)、东亚(97种)和北美(94种); 在国家尺度上, 以墨西哥物种数量最多(322种), 其次是俄罗斯(109种)、土耳其(88种)、美国(85种)和中国(82种)。在中国, 以云南和四川省鼠尾草种数最多(合计占全国的63%), 两省分布最多的县域地区分别是玉龙县(23种)、香格里拉县(20种)、大理市(13种)和木里县(17种)、宝兴县(13种)、马边县(13种)。在自然地理区域上, 以横断山区最为丰富, 占该属全国物种总数的52.8%, 特有种达23种; 广布种以荔枝草(S. plebeia)分布的县域数量最多(395县), 其次是鼠尾草(S. japonica) (199)、丹参(S. miltiorrhiza) (192)、贵州鼠尾草(S. cavaleriei) (173)、华鼠尾草(S. chinensis) (153)和粘毛鼠尾草(S. roborowskii) (100)。鼠尾草属主要分布于北半球温带及亚热带高海拔地区, 中国是东亚的多样性分布中心, 代表性广布种及狭域特有种均有分布, 尤以云南、四川以及横断山区的物种多样性和特有种比例最高。     

脂蛋白(a)合成的调节

脂蛋白(a) ［ LP(a)］是一种与低密度脂蛋白(LDL)结构极其相似的脂蛋白,它由LDL脂质核心、载脂蛋白B100(apoB100)及特异性的成分载脂蛋白(a)［ apo(a)］组成. 大量的研究表明,高LP(a)是动脉粥样硬化独立的危险因素.而LP(a)在血浆中的水平及致病能力取决于其合成的速率及其颗粒的大小. 因此, 如何抑制LP(a)合成,进而从源头减少LP(a) 的血浆水平,对动脉粥样硬化的防治具有重要的意义.本文就当前关于影响LP(a)合成的环节及相关机制进行综述, 从而为降LP(a)药物的研究提供新的视角.     

东海浮游磷虾类的生态类型

根据1997～2000年东海23°30'～33°00'N、118°30'～128°00'E海域4个季节海洋调查,运用磷虾类物种丰度和同步的温、盐度资料,进行曲线拟合,构造数学模型,计算各种磷虾分布的最适温度和盐度,并参考其地理和季节分布特征,对东海浮游磷虾类生态类型进行定量分析.结果表明,在磷虾优势种中,太平洋磷虾(Euphausia pacifica)是温带外海种,小型磷虾(E. nana)是暖温带外海种,中华假磷虾(Pseudeuphausia sinica)是亚热带近海种,宽额假磷虾(P. latifrons)是热带大洋种.这些物种的高丰度区依次代表黄海冷水团,冬春季的混合水团,夏秋季的混合水团和暖流水团的位置,是良好的水团指示种.柔弱磷虾(E. tenera)、隆柱螯磷虾(Stylocheiron carinatum)、长额磷虾(E. diomedeae)、近缘柱螯磷虾(S. affine)、Nematoscelis sp.、瘦线脚磷虾(N. gracilis)、长线脚磷虾(N. atlantica)、Stylocheiron sp.、三晶柱螯磷虾(S. suhmii)和二晶柱螯磷虾(S. microphthalma)是热带大洋种.娇嫩线脚磷虾(Nematoscelis tenella)、三刺燧磷虾(Thysanopoda tricuspidata)、大眼磷虾(E. sanzoi)、拟磷虾(E. similis)、鸟喙磷虾(E. mutica)、短磷虾(E. brevis)、卷叶磷虾(E. recurva)和Euphausia sp.是亚热带外海种.在确定磷虾类生态类型过程中,最适温度具有更好的参考价值.     

试论长臂猿的中国起源

本文通过中国长臂猿的地理地史分布, 尤其是亚洲新第三纪(Neogene Period) 中新世(Miocene) 的上猿(Pliop ithecus)、醉猿(Diony sopithecus shuang ouensis)、池猿(L accop ithecusrobustus)、滇猿(Dianopithecus progressus) 及第四纪(Quaternary Period) 更新世(Pleistocene Epoch) 丰富的黑长臂猿(Hylobates concolor) 等化石的发现, 结合现生类群的分布和黑长臂猿的行为生态研究结果等有关资料综合论述了现生长臂猿的亚洲中国起源; 黑长臂猿则是解决这一问题的关键物种。     

子一代表型数的估计式

设A_(11)A_(12)B_(11)B_(12)…N_(11)N_(12)和A_(21)A_(21)B_(21)B_(21)…N_(21)N_(22)分别是亲本P_1和P_2的基因型;a_(11),a_(12),a_(21)和a_(22)是控制同一性状的一组具有显隐关系的等位基因(a=A,…,N)。假定这n组等位基因互不连锁,且一组等位基因与另一组等位基因间没有相互作用,那么公式     

南海海绵Pachychalinasp.化学成份的研究

从中国南海海绵Pachychalina sp.正丁醇可溶部分获得了5个化合物,通过UV,IR,~1H-NMR,~(13)C-NMR,MS,~1H-~1HDQFCOSY等实验确定了它们的结构分别是:对羟基苯醋酸甲酯(1),胸腺嘧啶(2),尿嘧啶(3),胸腺嘧啶脱氧核苷(4)和尿嘧啶脱氧核苷(5)。其中化合物(1)是首次从我国南海海洋生物中获得;化合物(5)则是首次从海绵中分离得到的天然产物。     

Identification of natural rubber and characterization of rubber biosynthetic activity in fig tree

Natural rubber was extracted from the fig tree (Ficus carica) cultivated in Korea as part of a survey of rubber producing plants. Fourier transform infrared and (13)C nuclear magnetic resonance analysis of samples prepared by successive extraction with acetone and benzene confirmed that the benzene-soluble residues are natural rubber, cis-1,4-polyisoprene. The rubber content in the latex of fig tree was about 4%, whereas the rubber content in the bark, leaf, and fruit was 0.3%, 0.1%, and 0.1%, respectively. Gel-permeation chromatography revealed that the molecular size of the natural rubber from fig tree is about 190 kD. Similar to rubber tree (Hevea brasiliensis) and guayule (Parthenium argentatum Gray), rubber biosynthesis in fig tree is tightly associated with rubber particles. The rubber transferase in rubber particles exhibited a higher affinity for farnesyl pyrophosphate than for isopentenyl pyrophosphate, with apparent K(m) values of 2.8 and 228 microM, respectively. Examination of latex serum from fig tree by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed major proteins of 25 and 48 kD in size, and several proteins with molecular mass below 20 and above 100 kD. Partial N-terminal amino acid sequencing and immunochemical analyses revealed that the 25- and 48-kD proteins were novel and not related to any other suggested rubber transferases. The effect of EDTA and Mg(2+) ion on in vitro rubber biosynthesis in fig tree and rubber tree suggested that divalent metal ion present in the latex serum is an important factor in determining the different rubber biosynthetic activities in fig tree and rubber tree.     

Isolation and Characterization of Photosystem Ⅱ of Porphyra yezoensis Ueda

The thylakoid membranes were isolated and purified from gametophyte of Porphyra yezoensis Ueda (P. yezoensis) by sucrose density gradient ultracentrifugation. After P. yezoensis gametophyte thylakoid membranes were solubilized with SDS, the photosystem Ⅱ (PSⅡ) particles were isolated and purified. The activity of PSⅡ     

巴西橡胶树43 kD橡胶粒子膜蛋白基因的cDNA克隆及表达

对43 kD的橡胶粒子膜蛋白进行了分离纯化和其N端氨基酸序列分析,根据N端氨基酸序列,设计一简并引物,通过3'RACE(Rapid Amplification ofcDNA Ends)的方法,获得了43 kD的橡胶粒子膜蛋白的cDNA.该cDNA含有1 385个核苷酸,含有完整的阅读框架,编码381个氨基酸.在终止密码子下游,包含有一个239bp的3'非编码区.该cDNA由5个首尾相连的重复单元组成,每个单元编码76个氨基酸组成的泛素(ubiquitin)单体.编码43 kD橡胶粒子蛋白的基因具有多个拷贝,在胶乳、叶片和树皮都表达.     

我国市售婴儿配方乳粉油脂配料使用情况分析

目的：了解我国市售婴儿配方乳粉的油脂配料使用情况及脂肪酸提供情况,为提升婴儿配方乳粉的营养水平及制定产品相关标准提供参考。方法：多渠道收集婴儿配方乳粉标签信息,统计分析油脂配料的种类、组合、最高添加量构成比及标识含量,比较全脂乳产品与脱脂乳产品、牛乳基产品与羊乳基产品、高必需脂肪酸产品与全部产品间的差异。均数和率的比较分别采用t检验和卡方检验。结果：共纳入269个婴儿配方乳粉。配料表分析显示,85%的产品使用了4种及以上的油脂配料,葵花籽油和椰子油在全部产品中的添加率最高,分别为88%、76%。牛、羊乳基配方粉的油脂配料使用情况存在差异,牛乳基配方粉中脂肪、亚油酸及α-亚麻酸的标识含量略高于羊乳基配方粉（P<0.05）。脱脂乳配方粉中,棕榈油添加率为32%,显著高于全脂乳产品 （P<0.05）。44例使用了棕榈油的产品中仅有4例强化了1,3-二油酸2-棕榈酸甘油三酯。结论：牛、羊乳基配方粉中的必需脂肪酸标识含量基本一致。现市售婴儿配方乳粉以多种油脂组合使用的方式,以尽可能模拟母乳脂肪酸模式,但有些油脂类原料使用的科学性还有待进一步研究。     

Rubber elongation factor from Hevea brasiliensis. Identification, characterization, and role in rubber biosynthesis

The presence of a protein, rubber elongation factor (REF), which is tightly bound to serum-free rubber particles purified from Hevea brasiliensis latex, is necessary for prenyltransferases from a number of sources to add multiple cis-isoprene units to rubber molecules. These prenyltransferases show normal farnesyl pyrophosphate synthase activity (two trans additions of isopentenyl pyrophosphate to dimethylallyl pyrophosphate) in the absence of REF bound to rubber particles. REF bound to rubber molecules can be highly purified from all other proteins in whole latex by treatment of rubber particles with low concentrations of detergent. Treatment of rubber particles with trypsin which hydrolyzes bound REF, removal of REF with high concentrations of various detergents, or treatment of whole latex with polyclonal antibodies specific for REF all prevent prenyltransferase from adding [14C]isopentenyl pyrophosphate to rubber molecules. However, we have not been successful using detergent-solubilized REF in the reconstitution of in vitro rubber biosynthesis with either REF-depleted rubber particles or allylic pyrophosphate primers. REF has a molecular mass of 14,600 Da and is associated specifically with rubber particles in whole latex. It makes up between 10-60% of the total protein in whole latex but is absent in C-serum, the supernatant fluid obtained when rubber particles are removed by centrifugation. The amount of REF in whole latex is proportional to the rubber content. Based on a number average molecular mass of 500,000 Da for rubber and the content of rubber and REF in whole latex or serum-free rubber particles, the stoichiometry of REF molecules to rubber molecules is 1:1 in both cases. There is sufficient REF to form a monomolecular protein layer coating large rubber particles (700-1,000 nm). In the electron microscope, serum-free rubber particle preparations contain particles with diameters from 800 to as small as 10 nm. In the presence of 1% sodium dodecyl sulfate no particles smaller than 100 nm are observed. We suggest that the smaller particles may be mainly composed of REF molecules.     

毕赤酵母表达的HBV全长Pres蛋白的分离纯化

巴斯德-毕赤酵母工程菌株GS115-PreS经发酵在甲醇诱导下可高效表达分泌型全长PreS蛋白。Western blot证明发酵液中存在着可溶性的分子量为48kD的PreS蛋白和蛋白质颗粒,蛋白质颗粒主要成分为48kD的全长Pres蛋白和28kD的S蛋白,电镜观察发现蛋白质颗粒直径为30nm。发酵液经过脱盐、浓缩处理后,上清液经DEAESFF阴离子交换柱得到纯化的PreS蛋白;超速离心和蔗糖密度梯度离心得到蛋白颗粒。该颗粒的主要组分为全长PreS蛋白（PreS1＋PreS2＋S）,还有少量的主蛋白（S）。ELISA检测证明全长PreS蛋白和蛋白颗粒有着良好的抗原性, P/N显示蛋白颗粒的抗原性比PreS蛋白的抗原性高。     

The Human U5-220kD Protein (hPrp8) Forms a Stable RNA-Free Complex with Several U5-Specific Proteins, Including an RNA Unwindase, a Homologue of Ribosomal Elongation Factor EF-2, and a Novel WD-40 Protein

The human small nuclear ribonucleoprotein (snRNP) U5 is biochemically the most complex of the snRNP particles, containing not only the Sm core proteins but also 10 particle-specific proteins. Several of these proteins have sequence motifs which suggest that they participate in conformational changes of RNA and protein. Together, the specific proteins comprise 85% of the mass of the U5 snRNP particle. Therefore, protein-protein interactions should be highly important for both the architecture and the function of this particle. We investigated protein-protein interactions using both native and recombinant U5-specific proteins. Native U5 proteins were obtained by dissociation of U5 snRNP particles with the chaotropic salt sodium thiocyanate. A stable, RNA-free complex containing the 116-kDa EF-2 homologue (116kD), the 200kD RNA unwindase, the 220kD protein, which is the orthologue of the yeast Prp8p protein, and the U5-40kD protein was detected by sedimentation analysis of the dissociated proteins. By cDNA cloning, we show that the 40kD protein is a novel WD-40 repeat protein and is thus likely to mediate regulated protein-protein interactions. Additional biochemical analyses demonstrated that the 220kD protein binds simultaneously to the 40- and the 116kD proteins and probably also to the 200kD protein. Since the 220kD protein is also known to contact both the pre-mRNA and the U5 snRNA, it is in a position to relay the functional state of the spliceosome to the other proteins in the complex and thus modulate their activity.     

The Latex of Hevea brasiliensis Contains High Levels of Both Chitinases and Chitinases/Lysozymes

The latex of the commercial rubber tree, Hevea brasiliensis, was fractionated by ultracentrifugation as described by G. F. J. Moir ([1959] Nature 184: 1626-1628) into a top layer of rubber particles, a cleared cytoplasm, and a pellet that contains primarily specialized vacuoles known as lutoids. The proteins in each fraction were resolved by two-dimensional gel electrophoresis. Both the pellet fraction and cleared cytoplasm contained large amounts of relatively few proteins, suggesting that laticifers serve a very specialized function in the plant. More than 75% of the total soluble protein in latex was found in the pellet fraction. Twenty-five percent of the protein in the pellet was identified as chitinases/lysozymes, which are capable of degrading the chitin component of fungal cell walls and the peptidoglycan component of bacterial cell walls. Both the chitinase and lysozyme activities were localized exclusively in the pellet or lutoid fraction. The chitinases/lysozymes were resolved into acidic and basic classes of proteins and further purified. An acidic protein (molecular mass 25.5 kD) represented 20% of the chitinase activity in latex; this protein lacked the low level of lysozyme activity that is associated with many plant chitinases. Six basic proteins, having both chitinase and lysozyme activities in various ratios and molecular mass of 27.5 or 26 kD, were resolved. Two of the basic proteins had very high lysozyme specific activities which were comparable to the specific activities reported for animal lysozymes. Like animal lysozymes, but unlike previously characterized plant chitinases/lysozymes, these basic chitinases/lysozymes were also capable of completely lysing or clearing suspensions of bacterial cell walls. These results suggest that laticifers may serve a defensive role in the plant.     

The micromorphology and protein characterization of rubber particles in Ficus carica,Ficus benghalensis and Hevea brasiliensis

Rubber biosynthesis takes place on the surface of rubber particles. These particles are surrounded by a monolayer membrane in which the rubber transferase is anchored. In order to gain better insight into whether rubber particles from different plant species share common structural characteristics, the micromorphology of rubber particles from Ficus carica, Ficus benghalensis, and Hevea brasiliensis was examined by electron microscopy. Rubber particles of all three species were spherical in shape, and the size of rubber particles of H. brasiliensis was much smaller than those of F. carica and F. benghalensis. In addition, investigations were undertaken to compare the cross-reactivity of the antibody raised against either the H. brasiliensis small rubber particle protein (SRPP) which is suggested to be involved in rubber biosynthesis, or the cis-prenyltransferase (CPT) which has an activity similar to rubber transferase. Both western analysis and TEM-immunogold labelling studies showed that rubber particles of F. carica and F. benghalensis do not contain the SRPP. None of the rubber particles in F. carica, F. benghalensis and H. brasiliensis contained the CPT, suggesting that the CPT itself could not catalyse the formation of high molecular weight rubber. These results indicate that rubber particles in the three different plant species investigated share some degree of similarity in architecture, and that the SRPP and CPT themselves are not the core proteins necessary for rubber biosynthesis.     

The 76 kD cell-adhesion factor from crayfish haemocytes promotes encapsulation in vitro

Summary Semigranular cells from the crayfish, Pacifastacus leniusculus, were separated by Percoll gradient centrifugation and were used to study the encapsulation of foreign particles. The semigranular cells were found strongly to encapsulate glass beads coated with haemocyte lysate in which the prophenoloxidase-activating system had been activated with laminarin or with a low concentration of calcium ions. The granular cells only weakly encapsulated these particles. The encapsulationpromoting factor was purified from haemocyte lysates and found to be a 76 kD protein which was recognized by an antiserum to the previously described 76 kD cell-adhesion factor. After the last step in purification (Con A-Sepharose chromatography), the flowthrough consisted of several proteins, which had some, but less, encapsulation-promoting activity and contained a 30 kD band that was also recognized by the antiserum to the 76 kD cell-adhesion factor. If the haemocyte lysate prepared in low [Ca²⁺] was incubated with a -1,3-glucan prior to purification, no 76 kD protein could be isolated but only a 30 kD protein. The 30 kD protein thus seems to be a degradation product of the 76 kD cell-adhesion factor. We conclude that the 76 kD protein which is released from degranulating haemocytes, and to a lesser extent its 30 kD fragment, can promote encapsulation. Phenoloxidase did not have any encapsulation-promoting activity.