外源H2O2对盐碱胁迫下苹果矮化砧木幼苗生理特性的影响

以2年生苹果矮化砧木M9 T337为试材,采用盆栽试验法,设置浇灌清水(CK)和盐碱胁迫(0.1 mol/L NaCl+NaHCO₃溶液)+ 喷施5种浓度的H₂O₂ ［0(T₁)、0.2 mmol/L(T₂)、0.4 mmol/L(T₃)、0.6 mmol/L(T₄)、0.8 mmol/L(T₅)］ 处理,测定各处理叶片叶绿素含量、光合气体交换参数、渗透调节物质含量、抗氧化酶活性和细胞膜透性,并利用相关性与主成分分析进行综合评价,以探讨外源过氧化氢(H₂O₂)增强其盐碱耐性的生理机制。结果表明：(1)随着盐碱胁迫(T₁)的时间延长,M9 T337幼苗叶片叶绿素a(Chl a)含量、叶绿素b (Chl b)含量、叶绿素总量(Chl t)、净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、可溶性蛋白(SP)含量均呈逐渐下降趋势;胞间CO₂浓度(C_i)、可溶性总糖(TSS)含量、脯氨酸(Pro)含量、过氧化氢酶(CAT)活性、抗坏血酸过氧化物酶(APX)活性、相对电导率(REC)、丙二醛(MDA)含量均呈上升趋势;超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性均呈先升后降趋势。(2)与CK相比,盐碱胁迫+外源H₂O₂(T₂- T₅)处理后M9 T337幼苗叶片各指标均呈现不同幅度变化,且存在明显浓度效应,并以T₃(0.4 mmol/L H₂O₂)处理叶片的Chl a、Chl b、Chl t、SP和G_s降幅最小,C_i、REC、MDA升幅最小,TSS、Pro、APX升幅最大。(3)M9 T337幼苗叶片P_n与T_r、G_s、Chl a、Chl b、Chl t、SP、SOD、POD呈显著正相关,与C_i、MDA、CAT、APX、REC呈显著负相关。(4)综合评价表明,各处理对M9 T337幼苗叶片生理特性的效应依次为：CK>T₃>T₄>T₂>T₅>T₁。研究发现,叶面喷施适宜浓度H₂O₂可有效改善盐碱胁迫下M9 T337幼苗光合能力,显著提高抗氧化酶活性和渗透调节物质的含量,降低细胞膜透性,从而达到缓解盐碱胁迫的作用,并以0.4 mmol/L H₂O₂处理效果最佳。     

红叶野桐叶中的木脂素类化合物

为探究红叶野桐(Mallotus paxii )叶的化学成分,该研究采用正相硅胶、反相硅胶C₁₈、葡聚糖凝胶Sephadex LH-20、反相半制备高效液相等色谱方法对红叶野桐叶提取物进行分离、纯化,利用¹H-NMR、¹³C-NMR、HR-ESI-MS等波谱数据,结合 参考文献,鉴定化合物的结构。结果表明:从红叶野桐叶中分离得到12个木脂素类化合物,分别是7″,8″-threo-buddlenol D(1)、buddlenol D(2)、7″,8″-threo-buddlenol C(3)、buddlenol C(4)、(+)-丁香脂素(5)、表松脂醇(6)、松脂素(7)、1-acetoxyl-2e,6e-dipiperonyl-3,7-dioxabicyclo-[3,3,0]-octane(8)、刺五加酮(9)、落叶松脂醇-4''-O-β-D-吡喃葡萄糖苷(10)、rel-(2α,3β)-7-O-methylcedrusin(11)和dihydrodehydrodiconiferyl-alcohol 4''-O-β-D-glucoside(12)。以上木脂素类化合物均为首次从该植物中分离得到,部分木脂素类化合物具有良好的药理活性如抗菌、抗肿瘤、抗病毒等。该研究结果表明,红叶野桐叶中含有丰富且活性良好的木脂素类化合物,说明其良好的药用价值可能与这些木脂素类化合物有关。     

华丽龙胆GsF3′5′H和GsFNS基因的克隆及表达分析

该研究以华丽龙胆(Gentiana sino ornata)5个不同开放阶段(H₁~H₅)的蓝色花冠为试材,利用RT PCR技术克隆GsF3′5′H和GsFNS全长序列,并进行生物信息学分析,比较GsF3′5′H和GsFNS在不同组织和不同开放阶段的基因表达模式。结果显示：(1)所克隆的GsF3′5′H和GsFNS基因分别包含1 560 bp和1 590 bp开放阅读框(OFR),并分别编码520和529个氨基酸。(2)结构分析显示,GsF3′5′H和GsFNS均具有典型的F3′5′H和FNSⅡ蛋白保守结构域。(3)系统进化树分析表明,GsF3′5′H和GsFNS亲缘关系最近的物种是三花龙胆(Gentiana triflora)。(4)qRT PCR结果显示,GsF3′5′H和GsFNS基因在根、茎、叶和花冠中均表达,其中GsF3′5′H基因在花冠H₃阶段表达量最高。GsFNS在根中表达量最高,其次在花冠H₄阶段两基因的表达均较高。研究推测,GsF3′5′H基因表达产生的飞燕草素苷和GsFNS表达产生的黄酮共着色作用可能使华丽龙胆的花冠呈更稳定艳丽的蓝色,为蓝色花分子育种提供重要的基因资源。     

甘蔗茎叶的化学成分及抗氧化活性研究

为研究甘蔗(Saccharum officinarum)茎叶的化学成分及抗氧化活性,该文对甘蔗茎叶以甲醇提取,提取物采用柱色谱(SiO₂、Sephadex LH-20、Rp-18)进行分离纯化,根据质谱和核磁共振技术鉴定所得化合物的结构,并通过DPPH法测定化合物的清除自由基能力。结果表明:(1)从甘蔗茎叶部位共分离鉴定22个化合物,分别为对羟基苯甲醛(1)、对甲氧基桂皮酸(2)、4-甲氧基苯甲醛(3)、香草醛(4)、4-羟基肉桂酸甲酯(5)、对羟基苯甲酸(6)、(2-羟基苯基)(苯基)甲酮(7)、对甲基苯甲酸(8)、咖啡酸甲酯(9)、乌头酸A(10)、乌头酸E(11)、5-O-二甲氧基肉桂酰基奎尼酸(12)、槲皮素(13)、槲皮素-3-O-α-L-阿拉伯糖苷(14)、槲皮素-3-O-β-D-吡喃半乳糖苷(15)、硫代二丙酸双十八烷基酯(16)、α-conidendrin(17)、rel-(2α,3β)-7-O-methylcedrusin(18)、3-O-阿魏酰奎宁酸甲酯(19)、木犀草素(20)、(5S,6S)-5,6-dihydro-3,8,10-trihydroxy-5-(4-hydroxy-3-methoxyphenyl)-6-hydroxymethyl-2, 4-dimethoxy-7H-benzo [c]xanthen-7-one)(21)和5-O-阿魏酰奎宁酸甲酯(22),其中化合物2-3、7-11、14-19、21-22为首次从该植物中分离得到。(2)通过DPPH法对含量大的15个化合物(1-9、11-16)进行自由基清除能力的筛选,其中化合物12(5-O-二甲氧基肉桂酰基奎尼酸)显示了较好的抗氧化活性(IC₅₀值为 49.58 μg·mL^-1)。该研究结果丰富了甘蔗抗氧化活性物质基础,为其进一步开发利用提供了科学依据。     

南美蟛蜞菊中的酚酸类化学成分

为了解南美蟛蜞菊[Wedelia trilobata (L.) Hitchc.]的化学成分, 从其全株中分离得到9 个酚酸类化合物。经光谱分析, 分别鉴定为6-乙酰基-7-羟基-2,3-二甲基色原酮 (1)、七叶内酯 (2)、丁香醛 (3)、5-羟甲基糠醛 (4)、对羟基苯甲酸 (5)、水杨酸 (6)、反式对羟基桂皮酸 (7)、咖啡酸甲酯 (8) 和反式咖啡酸 (9)。化合物1~8 为首次从该植物中分离得到。     

蛇含委陵菜的木脂素类成分及其细胞毒活性研究

为了研究蛇含委陵菜(Potentilla kleiniana)的化学成分及其肿瘤细胞毒活性,该研究综合运用D-101大孔树脂、硅胶、Sephadex LH-20、Toyopearl HW-40F及半制备高效液相等现代色谱分离技术对蛇含委陵菜60%乙醇提取物进行分离纯化,根据化合物的理化性质结合核磁共振波谱(NMR)、高分辨质谱(HR-ESI-MS)鉴定化合物的结构,并采用MTT法测定各化合物对人宫颈癌细胞株Hela的细胞毒活性。结果表明:(1)从蛇含委陵菜中分离鉴定了13个木脂素类化合物,分别为(+)-松脂素(1)、(+)-8-羟基松脂素(2)、(+)-丁香脂素(3)、(+)-杜仲树脂酚(4)、(+)-松脂素-4-O-β-D-吡喃葡萄糖苷(5)、(+)-8''-羟基松脂素-4-O-β-D-吡喃葡萄糖苷(6)、(+)-8''-羟基松脂素-4''-O-β-D-吡喃葡萄糖苷(7)、(+)-松脂素-8''-O-β-D-吡喃葡萄糖苷(8)、schilignan F(9)、(+)-松脂素-4, 4''-O-双吡喃葡萄糖苷(10)、(+)-落叶松脂素-4''-O-β-D-吡喃葡萄糖苷(11)、neoolivil-4-O-β-D-glucopyranoside(12)、3,3''-bis [3,4-dihydro-4-hydroxy-6-methoxy-2H-1-benzopyran](13)。其中,化合物1-4、7、8、10、12、13为首次从委陵菜属植物中分离得到,化合物5、6、9、11为首次从蛇含委陵菜中分离得到。(2)细胞毒试验结果显示,化合物1、3、4对Hela细胞具有较好的抑制活性,其半数抑制浓度IC₅₀值分别为(69.94±1.89)、(66.25±2.11)、(59.81±1.73)μmol·L^-1。该研究结果进一步丰富了蛇含委陵菜的化学成分,为抗宫颈癌药物的研发提供物质基础。     

林分因子对云顶山不同人工林林下植物多样性的影响

该研究采用典型抽样法,以成都云顶山5种人工林——柏木 枫杨林(BF)、银杏 楠木林(YN)、光皮梾木 香樟林(GZ)、枫杨 桤木林(FQ)、柏木林(CB)为研究对象,分析不同人工林的林下植物组成与多样性特征,并确定影响林下植物多样性的主导林分因子,为当地人工林经营管理提供理论依据。结果表明：(1)研究区共记录林下植物168种,隶属于62科130属;5种人工林灌木层与草本层的科属种数均以GZ最多。(2)5种不同人工林灌木层与草本层的优势种数分别为7、4、7、6、4种和5、4、9、9、10种,数量都较少。(3)5种人工林的Shannon Wiener多样性指数(H)、Simpson优势度指数(H′)、物种丰富度指数(D)、Pielou均匀度指数(J_sw) 均基本表现为草本层>灌木层,BF、GZ灌木层的D略高;灌木层的H、H′、D值均以GZ最大,但不同人工林的J_sw差异不显著;草本层的H、H′、D、J_sw均基本呈现CB>FQ>GZ>BF>YN趋势,GZ的D值略高于FQ。(4)6个林分因子对灌木层4个物种多样性指数的影响均无显著差异;林分平均树高、平均枝下高、平均胸径、平均冠幅和林分密度是影响草本层H、D的主要因子,但各林分因子对草本层H′、J_sw的影响差异不显著。研究认为,林分结构对林下草本层物种多样性的影响更大,平均树高、平均枝下高、平均胸径、平均冠幅、林分密度对草本层多样性有显著影响。     

水稻CPR5基因参与氧化胁迫响应

为探讨水稻(Oryza sativa L.)中CPR5 基因的功能,以其cDNA 文库为基础进行序列比对,并将1 个同源性较高的序列命名为OsCPR5.生物信息学分析表明,OsCPR5 的开放阅读框长度为1551 bp,编码516 个氨基酸.软件预测该编码蛋白可能是1 个具有5 个跨膜区的膜蛋白和核定位蛋白.组织表达和亚细胞定位分析表明,OsCPR5 在根中的表达水平较高,且广泛分布在细胞膜、细胞质和细胞核上.逆境胁迫分析实验表明,植物激素脱落酸(Abscisic acid, ABA)、过氧化氢(Hydrogen peroxide,H₂O₂)、氯化钠(NaCl)、甲基紫精(Methyl viologen, MV)等环境胁迫可诱导OsCPR5 的上调表达,其中氧化胁迫相关的MV 和H₂O₂ 处理效果最为明显.拟南芥(Arabidopsis thaliana)转基因株系atcpr5/OsCPR5 在浓度为0.5 μmol L^-1、 1.0 μmol L^-1 的MV以及6 mmol L^-1、 8 mmol L^-1 的H₂O₂ 处理下,种子萌发率明显高于atcpr5 突变体.这揭示了OsCPR5 基因在植物抗氧化胁迫响应中具有一定的作用.     

广藿香内生真菌Ogataea sp. RW-S10次级代谢产物研究

为挖掘广藿香(Pogostemon cablin)内生真菌活性代谢产物,采用多种柱色谱分离方法从广藿香内生真菌Ogataea sp.RW-S10的次级代谢产物中分离得到7个化合物,根据波谱数据分别鉴定为ogataearin (1)、phenylalaninol (2)、对羟基苯乙酮(3)、bis(dethio)bis(methylsulfanyl) gliotoxin (4)、N-苯乙基乙酰胺(5)、lumichrome (6)和dehydroxypaxilline (7),其中化合物1为新化合物。化合物1具有α-葡萄糖苷酶抑制活性,其IC₅₀值为39.38 μmol/L。     

Effects of iron chelates on the transferrin-free culture of rat dermal fibroblasts through active oxygen generation

Summary Effects of nonchelating and chelating agents at 10 mM on the serum-free culture of rat dermal fibroblasts were investigated. A strong iron-chelating agent, iminodiacetic acid (IDA), and a weak one, dihydroxyethylglycine (DHEG), decreased iron permeation into preconfluent fibroblasts. A weak iron-chelating agent, glycylglycine (GG), a nonchelating agent, N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES), and human apotransferrin (10 μg/ml) increased the permeation with time. Iron may be essential for survival of fibroblasts because subconfluent fibroblasts exposed to 100 μM FeSO₄ in combination with transferrin, HEPES, or GG significantly decreased to release lactate dehydrogenase into the medium. Superoxide dismutase and dimethyl sulfoxide blocked the enzyme release, suggesting that superoxide and hydroxyl radical induce cellular damage but hydrogen peroxide (H₂O₂) generated by superoxide dismutation does not. GG significantly reduced H₂O₂ cytotoxicity. DHEG acted as a potent promoter of the iron-stimulated cellular damage if ascorbate or H₂O₂ was added to the medium. FeSO₄ and FeCl₃ (50 to 100 μM) individually combined with IDA maximally promoted fibroblast proliferation. Ascorbate increased formation of thiobarbituric acid-reactive substances from deoxyribose in the medium supplemented with FeSO₄ and either IDA or DHEG. Conversely, ascorbate decreased the formation in the medium with FeSO₄ and with or without other agents. Fibroblast proliferation may thus be stimulated through the active oxygen generation mediated by a redox-cycling between Fe³⁺ and Fe²⁺, which are dissolved in the medium at a high concentration, rather than through delivery of iron into the cells.     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.