铜污染对三叶草幼苗生长及活性氧代谢影响的研究

通过水培实验研究了重金属铜(Cu)污染对三叶草(Trifolium pratense)幼苗生长及活性氧代谢系统的影响。结果表明,低浓度Cu污染(<10mg·L^-1)对三叶草幼苗生长无明显抑制现象,甚至促进幼苗生长,植株干重、鲜重和叶片可溶性蛋白及叶绿素含量均略微升高,丙二醛(MDA)水平降低,活性氧清除系统内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性均略微升高,保护酶系统仍保持平衡.但随Cu浓度(10～100mg·L^-1)增加则显示出一定的负效应,三叶草幼苗与对照组相比,植株矮小,须根短且数目少,植株干重、鲜重和可溶性蛋白含量均明显减少,叶片发黄,叶片色素含量下降,并随Cu浓度的增加而变化更显著。同时,随Cu浓度增加,叶片细胞膜透性增大,电导率显著升高,MDA水平上升,且活性氧清除系统遭到破坏,保护酶系统失衡,SOD和CAT活性显著下降,分别降低了26．7％和71．3％,而POD活性却明显上升,比对照升高了10．6倍。     

铜胁迫下链格孢菌对白车轴草生理生态的影响

通过盆栽实验研究了Cu胁迫下接种病原菌链格孢菌(Alternaria tenuis Nees)对白车轴草(Trifolium repens L.)生理生态指标的影响.结果表明:在未接种的对照组中,随着Cu浓度的增大(0~3000mg.kg-1),植株叶片失绿,生物量下降,叶绿素a、b、a b和类胡萝卜素及叶片可溶性蛋白质含量下降;植物体内丙二醛(MDA)高度积累,细胞膜结构遭到损坏,电导率增大;植株活性氧清除系统受损,不能保持原有平衡,超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性显著降低,过氧化物酶(POD)活性升高.接种链格孢菌后,植株叶片色素、膜系统及保护酶系统的损伤均加重,与不接种对照组相比,相同浓度Cu处理的叶绿素a、b、a b和类胡萝卜素、可溶性蛋白质含量、SOD和CAT活性均呈不同程度的下降,而电导率、MDA含量和POD活性则有所上升.     

外源亚精胺对Ca(NO3)2胁迫下黄瓜幼苗生长和活性氧代谢的影响

以温室专用黄瓜品种'津优3号'幼苗为材料,采用营养液栽培方法,研究了叶面喷施1 mmol·L-1亚精胺(Spd)对60 mmol·L-1硝酸钙胁迫下黄瓜幼苗生长和植株体内活性氧代谢的影响.结果显示,Ca(NO3)2胁迫下,黄瓜幼苗叶片和根系O-·2产生速率显著增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)等抗氧化酶活性升高,同时MDA含量和相对电导率明显提高,显著降低了黄瓜幼苗的株高、鲜重和干重;外源喷施Spd提高了硝酸钙胁迫下黄瓜幼苗叶片和根系SOD、POD和CAT活性,降低了O-·2产生速率,MDA含量及相对电导率显著下降.由此可见,外源Spd可通过提高黄瓜幼苗SOD、POD和CAT等保护酶活性来增强其对体内活性氧的有效清除能力,降低膜质过氧化伤害程度,从而缓解硝酸钙胁迫对黄瓜幼苗生长的抑制.     

白茅生长及抗氧化酶系统对铜胁迫的生理响应

通过盆栽实验研究了重金属Cu递进胁迫对白茅幼苗生理生态及抗氧化酶系统的影响。结果表明,随着Cu浓度的增加,平均根长、平均株高、鲜重、干重以及叶片色素含量等指标先增后降,分别在Cu浓度500 mg/kg处达到峰值。最长根长和叶片可溶性蛋白含量则在1000 mg/kg处达到峰值。说明低浓度Cu（〈500 mg/kg）对白茅生长有促进作用,而高浓度Cu（〉1000 mg/kg）则对植株生长产生抑制作用。Cu胁迫还导致叶片细胞膜脂过氧化水平增高,表现为叶片MDA含量随Cu浓度增加而持续上升,其最大值达到对照的5.3倍。抗氧化酶系统中超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和多酚氧化酶（PPO）活性也随Cu浓度增加表现出先升后降的趋势,并均在Cu浓度为1000 mg/kg时达到峰值,但过氧化物酶（POD）活性持续上升,故系统受到高浓度Cu胁迫而失衡,不能有效清除植物体的自由基和过氧化物,使植物产生受害症状。     

铝胁迫对海莲幼苗保护酶系统及脯氨酸含量的影响

为探讨Al~(3+)胁迫对海莲的影响,研究了10～50 mmol/L Al~(3+)处理下海莲幼苗叶片和根系的过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)的活性以及可溶性蛋白质、丙二醛(MDA)和游离脯氨酸(Pro)含量的变化。结果表明,海莲幼苗能耐受50 mmol/L的Al~(3+)胁迫处理,具有较高的耐铝性。但在50 mmol/L Al~(3+)处理时,海莲幼苗叶片和根系的质膜系统膜脂过氧化加重,MDA含量增加;细胞活性氧代谢失衡。在保护酶系统中,Al~(3+)处理促进了叶片中APX和POD活性的提高,降低了CAT的活性,SOD的活性呈下降趋势;海莲根部POD和SOD活性均显著提高,而CAT活性下降。25～50 mmol/LAl~(3+)处理下,海莲叶片和根部可溶性蛋白质含量均显著下降;Pro的含量在叶片和根均有显著增加。     

外源一氧化氮供体SNP对黑麦草种子萌发和幼苗生长的影响

采用水培试验,研究了不同浓度NO供体硝普钠(SNP)对黑麦草种子萌发和幼苗生长的影响。结果表明:50和100μmol.L-1SNP促进了黑麦草种子的发芽率、幼苗干物质积累速率、萌发种子α-淀粉酶活性、幼苗叶片可溶性蛋白质及叶绿素含量的提高。根和叶片中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性及还原型谷胱甘肽(GSH)、抗坏血酸(ASC)含量增加,超氧阴离子(O.2-)积累速率和过氧化氢(H2O2)含量下降,丙二醛(MDA)积累降低。高浓度SNP(500~2000μmol.L-1)抑制种子的萌发和幼苗生长,幼苗叶绿素、可溶性蛋白质及GSH、ASC含量下降,MDA含量和H2O2、O.2-产生速率提高,SOD、POD和APX活性降低,但叶片CAT活性升高。推测NO可能通过提高种子淀粉酶活性和幼苗活性氧清除能力,促进黑麦草种子的萌发和幼苗生长。     

氯化胆碱对盐胁迫黄瓜幼苗渗透调节物质及活性氧代谢系统的影响

以盐敏感型黄瓜品种津春4号为材料,采用水培方法研究了叶面喷施不同浓度(0.5、1.0和1.5 mmol·L-1)氯化胆碱(CC)对NaCl胁迫(75 mmol·L-1)下黄瓜幼苗鲜重、叶片叶绿素、渗透调节物质含量及活性氧代谢系统的影响.结果表明:(1)单独CC处理可提高黄瓜叶片的叶绿素、可溶性糖和可溶性蛋白含量以及过氧化氢酶(CAT)与过氧化物酶(POD)活性,降低O2·-产生速率,但对植株鲜重及超氧化物岐化酶(SOD)活性影响不大;(2)NaCl胁迫处理增加了黄瓜幼苗叶片中可溶性糖和可溶性蛋白含量,增强了SOD、POD和CAT活性,提高了O2·-产生速率及丙二醛(MDA)的含量,但同时降低了叶绿素含量与植株鲜重;(3)盐胁迫前CC预处理可缓解黄瓜幼苗叶绿素含量和植株鲜重的下降、以及MDA含量和O2·-产生速率的上升趋势,且进一步提高了盐胁迫下黄瓜叶片中SOD、POD和CAT活性.因此,适宜浓度的氯化胆碱可显著提高盐胁迫下黄瓜叶片的抗氧化酶活性,提高清除活性氧的能力,缓解盐胁迫对黄瓜幼苗细胞膜的伤害,增强黄瓜幼苗的耐盐性.     

骆驼蓬提取物浸种对小麦幼苗生长及抗氧化酶活性的影响

以不同浓度骆驼蓬提取液浸种处理小麦。研究对幼苗生长及抗氧化酶活性的影响。结果表明,骆驼蓬提取液浸种后小麦幼苗的根长、株高和干重增加,根冠比增大;幼苗根系活力增强,根系超氧化物歧化酶（SOD）活性提高,过氧化氢酶（CAT）活性先升后降,过氧化物酶（POD）活性下降,过氧化物酶同工酶表达受抑;叶片叶绿素和可溶性蛋白质含量增加,叶片SOD、POD活性提高,过氧化物酶同工酶表达增强,CAT活性降低。根系和叶片丙二醛（MDA）含量下降。     

铜胁迫下链格孢菌对白车轴草生理生化特性的影响

通过盆栽实验研究了Cu胁迫下接种链格孢菌(AlternariatenuisNees)对源自Cu污染区(记作种群Ⅰ)和非污染区(记作种群Ⅱ)白车轴草(TrifoliumrepensL)生理生化特性的影响。结果表明,两种群白车轴草在Cu处理后接种链格孢菌,0~1500mg·kg-1时叶片电导率、MDA含量均高于未接种组,且随浓度增加而升高,2000mg·kg-1时电导率低于未接种组,MDA含量降低但仍高于未接种组。两种群接种后叶绿素、蛋白质含量较未接种组下降,且随Cu浓度增加而降低,其中叶绿素含量与浓度呈显著或极显著负相关,种群Ⅰ和种群Ⅱ相关系数分别为-0.954*和-0.961**。链格孢菌使白车轴草SOD活性低浓度(0和500mg·kg-1)高于未接种组,高浓度则降低。接种后POD活性随Cu浓度增加先增后减,500mg·kg-1浓度下接种组POD高于未接种组,而在其他浓度下,显著低于未接种组。0~1000mg·kg-1时接种组CAT活性高于未接种组,随土壤Cu浓度增加先增后减。3种保护酶对胁迫的敏感性为POD>SOD>CAT。高浓度Cu(2000mg·kg-1)胁迫下,白车轴草保护酶系统的受损打破了体内活性氧产生与清除之间的正常平衡状态,积累了过量的活性氧,膜脂过氧化程度加重,对白车轴草产生毒害,且这种毒害在接种链格孢菌后表现更为严重。两种群白车轴草相比,种群Ⅰ植物在土壤Cu<2000mg·kg-1时可生存,感染链格孢菌后生长土壤Cu浓度应控制在1500mg·kg-1以内;种群Ⅱ在Cu胁迫浓度不超过1500mg·kg-1,链格孢菌和Cu双重胁迫时不超过1000mg·kg-1可生长。种群Ⅰ在Cu处理、链格孢菌单一或双重胁迫下表现的抗逆性较Ⅱ强。     

豆链格孢菌对白车轴草生理代谢及活性氧清除系统酶的影响

通过盆栽实验,研究了接种豆链格孢菌对白车轴草叶组织细胞膜透性、色素含量、丙二醛(MDA)含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性的影响.结果表明,豆链格孢菌使白车轴草叶组织细胞膜透性上升,电导率显著升高,膜脂过氧化加强,MDA水平上升,色素含量下降.电导率和MDA含量均与感病时间呈显著正相关,而色素含量与感病时间呈显著负相关.豆链格孢菌刺激其寄主白车轴草叶片膜脂过氧化作用发生,积累大量的活性氧,使其超出防御酶的清除能力,致使活性氧清除系统遭到破坏,保护酶系统失衡,其中SOD和CAT活性显著下降,而POD活性明显上升.接种12d后,SOD和CAT分别降低了55.2%和37.8%,而POD比对照升高约1.6倍.     

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.