过表达ZmSKIP基因提高烟草抗低温胁迫的能力

以野生型和过表达ZmSKIP基因烟草为试材, 研究了低温胁迫下过表达ZmSKIP对烟草抗氧化能力的影响。测定了不同低温处理时间下过表达ZmSKIP转基因烟草T3代植株和野生型植株抗氧化酶如超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）活性和丙二醛（MDA）含量以及相对电导率, 结果表明, 低温下, 相对于野生型植株, 转基因烟草具有较高的抗氧化酶活性和较低的相对电导率和MDA含量, 说明过表达ZmSKIP提高了转基因植株的耐低温胁迫能力。     

低温胁迫对巨尾桉幼苗膜脂过氧化及保护酶的影响

以木本植物巨尾桉幼苗为材料 ,研究低温胁迫对巨尾桉膜脂过氧化及保护酶的影响 ,测定了幼苗叶片的O 2(超氧阴离子 )产生速率、H2 O2 、(过氧化氢 )、MDA(丙二醛 )含量、相对电导率和SOD(超氧化物歧化酶 )、POD(过氧化物酶 )、CAT(过氧化氢酶 )、APX(抗坏血酸过氧化物酶 )活性。结果表明 :低温胁迫使叶片O 2 产生速率、H2 O2 、MDA含量和相对电导率增加 ,但抗寒锻炼植株的增幅远小于对照 ;抗寒锻炼植株的SOD、POD、CAT和APX活性均低于对照。     

过表达LeNLP4转录因子提高番茄抗低温胁迫能力

NAC（NAM-ATAF1,2-CUC2）转录因子在植物胁迫响应中起重要作用。为了探讨三舭丹基因在番茄抗低温胁迫中的功能,分离了番茄LeNLP4转录因子基因,并获得转正义LeNLP4基因番茄植株。荧光定量PCR分析表明,LeNLP4的表达受低温诱导。与野生型植株相比,在4℃胁迫下转基因植株具有较高的生长量和光系统II（PSH）最大光化学效率（Fv／Fm）、过氧化氢（H2O2）和超氧阴离子（O2-）清除速率、抗坏血酸过氧化物酶（APX）和超氧化物歧化酶（SOD）活性,以及较低的丙二醛（MDA）含量和相对电导率（REC）。过表达株系中SICBF1的表达高于野生型。上述结果表明,LeNLP4的过表达提高了转基因番茄抗低温胁迫能力。     

低温胁迫下钼对冬小麦抗氧化防御系统及膜脂过氧化的影响

研究了低温（0～5℃）胁迫下钼对冬小麦抗氧化系统和膜脂过氧化的影响。结果表明,低温胁迫下施钼植株电解质渗漏率和丙二醛含量显著降低。施用钼肥提高了冬小麦叶片中抗氧化酶类如超氧化物歧化酶（SOD,EC1．15．1．1）、过氧化物酶（POX,EC1．11．1．7）和过氧化氢酶（CAT,ECl．11．1．6）的活性。低温胁迫下施钼对抗氧化酶（SOD、POX和CAT）活性提高幅度比常温下高。不论常温还是低温下,施铝均提高了冬小麦叶片中抗坏血酸和脯氨酸含量,低温胁迫下提高幅度更大。常温下缺钼和施钼处理后,叶片中类胡萝卜素含量差异不显著;低温下施钼后,冬小麦叶片类胡萝卜素含量显著增加。因此,低温胁迫下施钼植株活性氧清除能力增强、细胞膜伤害减轻可能是冬小麦抗寒力提高的原因之一。     

抗坏血酸对高温胁迫下猕猴桃苗抗热性相关生理指标的影响

以美味猕猴桃组培苗品种秦美为试材,研究抗坏血酸（AsA）对高温胁迫下猕猴桃苗抗热性相关生理指标影响的结果表明,抗坏血酸可抑制高温胁迫下猕猴叶细胞膜透性和丙二醛（MDA）含量的增大,但增强超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）和抗坏血酸过氧化物酶（APX）的活性。     

外源褪黑素对低温胁迫下茄子幼苗生长及其光合作用和抗氧化系统的影响

以‘沪茄08-1’茄子幼苗为试验材料,采用基质栽培方式,研究了叶面喷施50~200μmol·L-1外源褪黑素(melatonin,MT)对低温胁迫[(10±1)℃(昼)/(5±1)℃(夜)]下茄子幼苗生长、光合作用和抗氧化系统等生理指标的影响,以明确外源MT在茄子幼苗抵御低温逆境方面的生理机制。结果显示:(1)低温胁迫处理后,茄子幼苗株高、茎粗、地上部鲜重和根系鲜重、叶绿素含量、叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均显著降低,丙二醛(MDA)含量、超氧阴离子产生速率(O-·2)和过氧化氢(H2O2)含量均显著增加。(2)幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、脱氢抗坏血酸还原酶(DHAR)活性及抗坏血酸(AsA)和谷胱甘肽(GSH)含量均显著升高,而其脯氨酸(Pro)和可溶性蛋白质含量均显著增加;外源MT处理可有效增强低温胁迫条件下茄子幼苗叶片中SOD、POD、CAT、APX、GR、DHAR活性,提高AsA和GSH含量,增加Pro和可溶性蛋白含量,显著抑制其叶片MDA、O-·2及H2O2的积累。研究表明,外源MT主要通过增强低温胁迫下茄子幼苗的光合作用以及清除活性氧的能力,减缓低温胁迫的危害,提高茄子幼苗对低温胁迫的耐性。     

渝17S对低温胁迫的响应及耐冷机制初步研究

重庆及西南稻区水稻幼苗期倒春寒频发,常常导致秧苗生长迟缓,白化、烂秧等发生,制约了优质水稻安全生产和轻简化技术的应用.本研究以耐冷性较强的渝17S和对低温敏感的Y58S为材料,对比研究了3叶龄幼苗经4℃低温处理后,二者可溶性糖、海藻糖、脯氨酸、丙二醛和过氧化氢的含量,超氧化物歧化酶、过氧化氢酶和抗坏血酸过氧化物酶的活性...     

低温胁迫下棉花幼苗对外源水杨酸的生理响应

以棉花幼苗为试材,通过叶面喷施不同浓度水杨酸的处理方法,研究外源水杨酸对低温胁迫下棉花幼苗的缓解效应。结果表明,0.6~0.8 mmol＆#183;L-1水杨酸预处理可以显著降低棉花幼苗叶片相对电导率（REC）和丙二醛（MDA）的积累量,从而缓解低温对质膜的过氧化伤害,并通过提高超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）的活性和可溶性糖、可溶性蛋白、脯氨酸等渗透调节物质的含量来适应低温环境。     

过表达单脱氢抗坏血酸还原酶基因提高番茄抗UV-B胁迫能力

以野生型（WT）和转正义叶绿体单脱氢抗坏血酸还原酶基因（LeMDAR）番茄为试材,探讨了UV-B胁迫下过表达LeMDAR对番茄抗氧化能力的影响。测定了不同时间uV-B处理下番茄抗坏血酸（AsA）含量,脱氢抗坏血酸（DHA）含量,单脱氢抗坏血酸还原酶（MDAR）活性,光合速率和叶绿素荧光参数等。在UV-B处理下,转基因番茄植株的AsA含量、MDAR酶及抗坏血酸过氧化物酶（APx）活性、H：0：和超氧阴离子清除速率、净光合速率（只）高于野生型番茄。此外,紫外胁迫下,转基因株系丙二醛（MDA）含量和相对电导率（REC）较野生型增加的少。上述结果表明,MDAR对抗抗坏血酸再生具有重要作用,过表达LeMDAR提高了番茄植株抗氧化能力,对光合机构有保护作用。     

抗氧化系统参与循环干旱锻炼提高烟草植株抗旱性的形成

对漂浮育苗的烟草幼苗进行控水-半萎焉-复水-恢复的循环干旱锻炼。结果表明,这种干旱锻炼能显著提高烟草叶片抗氧化剂谷胱甘肽（GSH）、抗坏血酸（AsA）的含量、还原型抗氧化剂在总抗氧化剂中的比例和抗氧化酶包括超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）、过氧化氢酶（CAT）、愈创木酚过氧化物酶（GPX）、谷胱甘肽还原酶（GR）的活性,降低丙二醛（MDA）的含量。当烟草植株遭受后续的干旱胁迫时,与未锻炼的对照相比,干旱锻炼过的烟草植株能保持较高的GSH和AsA含量、还原型抗氧化剂在总抗氧化剂中的比例和抗氧化酶（SOD、APx、CAT、GPX和GR）活性,以及较低的MDA含量,表明这种循环干旱锻炼提高了细胞抗氧化能力,有助于缓解烟草植株由干旱引起的氧化胁迫及其所导致的伤害,最终提高其抗旱性。这些结果表明。抗氧化系统参与了循环干旱锻炼提高烟草植株抗旱性的形成过程。     

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.