渗透胁迫下多花黑麦草叶内过氧化物酶活性和脯氨酸含量以及质膜相对透性的变化

多花黑麦草幼苗于３ 叶期转移至１／２Ｈｏａｇｌａｎｄ 溶液中培养,同时加入ＰＥＧ６０００ 用以模拟５种强度的渗透胁迫。植物叶内过氧化物酶活性、游离脯氨酸含量和质膜相对透性均对渗透胁迫强度的增加作出了反应,但反应的敏感性依次降低。从时间进程上看,过氧化物酶活性升降在前,游离脯氨酸积累继之,嗣后出现质膜相对透性增高。每个测定日内叶片中游离脯氨酸含量与质膜相对透性呈显著至极显著正相关。     

渗透胁迫下多花黑麦草叶内过氧化物酶活性和脯氨酸含量以及质 …

多花黑麦草幼苗于３叶期转移至１／２Ｈｏａｇｌａｎｄ溶液中培养,同时加入ＰＥＧ６０００用以模拟５种强度的渗透胁迫。植物叶内过氧化物酶活性、游离脯氨酸含量和质膜相对透性均对渗透胁迫强度的增加作出了反应,但反应的敏感性依次降低。从时间进程上看,过氧化物酶活性升降在前,游离脯氨酸积累继之,嗣后出现质膜相对透性增高。每个测定日内叶片中游脯氨酸含量与质膜相对透性呈显著至极显著正相关。     

渗透胁迫下多效唑对刺槐幼苗体内多胺、脯氨酸和保护酶系统的影响

刺槐幼苗在PEG渗透胁迫下,相对含水量(RWC)降低,质膜透性增加,游离腐胺、脯氨酸的积累和超氧物歧化酶(SOD)、过氧化氢酶(CAT)活性提高,腐胺、亚精胺比值(Put/Spd)增加。渗透胁迫下用多效唑(PP_(333))作浸根和浸种处理,提高刺槐幼苗RWC和游离脯氨酸含量,减少质膜透性和 Put/Spd比值,降低SOD、CAT活性和腐胺含量。腐胺水平的变化与幼苗的水分状况有关,与质膜透性的变化趋势一致。     

外源芦丁预处理对水分胁迫下玉米幼苗的生理效应

以玉米(Zeamays L.)品种'郏单958'为材料.采用营养液水培法,研究了外源芦丁(Rutin)对聚乙二醇(PEG)胁迫下幼苗叶片质膜相对透性、脯氨酸、可溶性糖含量及保护酶活性的影响.结果显示:(1)在15%PEG-6000胁迫下,玉米叶片的MDA含量、质膜相对透性、脯氨酸和可溶性蛋白质含量均显著增加,保护酶SOD、CAT、POD活性显著升高.(2)一定浓度芦丁(>0.40 g/L)预处理可显著抑制水分胁迫下玉米幼苗叶片MDA含量的上升,降低叶片质膜相对透性,并诱导SOD、POD和CAT活性提高.降低脯氨酸和可溶性蛋白质含量.说明外源芦丁能够提高玉米幼苗的抗氧化作用,缓解水分胁迫引起的膜脂过氧化,保护细胞膜免受或减少损伤·达到提高植物抗旱性的目的.     

茉莉酸对小麦幼苗UV-B抗性的生理学效应研究

以小麦品种‘西农88’(Triticum aestivum L.,cv.Xinong 88)为材料,研究了外源施加不同浓度茉莉酸(1、2.5、5、10 mmol/L)对UV-B辐射(1.5 kJ·m-2·d-1)下小麦幼苗光合色素、抗氧化酶、丙二醛、游离脯氨酸、紫外吸收物、花青素、根系活力等生理指标以及对其生长的影响,探讨了茉莉酸在UV-B辐射胁迫中的可能作用及其作用机制.研究结果表明,外源茉莉酸对小麦幼苗生理指标产生显著影响,并且表现出浓度效应,其中较低浓度的茉莉酸(1 mmol/L和2.5 mmol/L)能明显提高小麦幼苗的UV-B抗性.表现为低浓度茉莉酸显著提高UV-B辐射下小麦幼苗叶片中的总叶绿素含量、过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性.并且外源施加的茉莉酸还能够增加小麦幼苗的游离脯氨酸含量,降低脂质过氧化水平,提高花青素含量,增强根系活力.可见,茉莉酸通过提高小麦幼苗的抗氧化酶活性,增加渗透调节物含量以及保护性色素含量,从而缓解膜脂过氧化程度和提高防御物质含量,进而增强植物抵抗UV-B辐射胁迫的能力,保证小麦幼苗正常生长.     

NaCl对小麦苗叶片脯氨酸氧化酶活性和游离脯氨酸累积的影响

在含NaCl营养液中培养的小麦幼苗较之无NaCl营养液中的幼苗。其脯氨酸氧化酶活性降低,而游离脯氨酸含量则升高;培养液的渗透势越低,培养时间越长,则脯氨酸氧化酶的活性越低,且游离脯氨酸的含量越高。去除胁迫后酶活性恢复,脯氯酸含量下降。不同渗透剂对氧化酶活性抑制强弱顺序为MgCl_2>NaCl>甘露醇,引起脯氨酸累积效应的强度顺序为MgCl_2>NaCl>甘露醇。超微结构显示,高NaCl浓度下部分线粒体结构受损伤,膜和嵴部分消失。     

渗透胁迫下稻苗中游离脯氨酸累积与膜脂过氧化的关系

杂交稻幼苗经聚乙二醇（ＰＧＥ４０００）渗透胁迫（－０．９５ＭＰａ）处理,幼苗含水量及相对含水量下降,游离脯氨酸和膜脂过氧化产物丙二醛（ＭＤＡ）含量上升,质膜透性增大。随ＰＥＧ渗透胁迫时间延长,幼苗膜脂饱和脂肪酸含量逐渐增加,不饱和脂肪酸含量降低,不饱和脂肪酸指数（ＩＵＦＡ）减少。脯氨酸累积与ＭＤＡ增长及膜透性加大呈正相关性,与膜脂脂肪酸不饱和度呈负相关性。讨论了游离脯氨酸累积与细胞透性的相关性,以     

低温胁迫对苜蓿幼苗存活及生理生化指标的影响

用秋眠级为2级至9级的11个苜蓿品种,每品种被随机分为对照组和5个处理组,研究低温胁迫和苜蓿品种对幼苗存活和叶片生理生化指标的影响。结果表明:低温胁迫和苜蓿品种对幼苗存活率、叶片生理生化指标的影响均极显著,而且二者对它们的互作效应也极显著。子叶期幼苗在-7.5℃下处理12 h,存活率仅为3.26%。幼苗在-5℃下处理12 h,存活率为54.73%,但叶片游离脯氨酸含量、过氧化物酶活性、质膜相对透性和根系活力极显著提高;每天把幼苗置于-5℃下2 h至3 h锻炼7天,幼苗存活率可提高到95%以上,叶片游离脯氨酸、可溶性糖、可溶性蛋白质含量,超氧化物歧化酶活性、根系活力和质膜相对透性均极显著提高。结果表明:4级至9级品种的存活率极显著低于2级至3级的品种;6级至9级品种叶片游离脯氨酸含量、过氧化物酶活性、质膜相对透性极著显低于2级至3级的品种。     

壳聚糖对蝴蝶兰幼苗耐热性的诱导作用

为了评价壳聚糖对蝴蝶兰幼苗耐热性的诱导效应,分别采用0(以无壳聚糖为对照)、25、50、100、200和400 mg·L~(-1)壳聚糖溶液处理蝴蝶兰幼苗,并置于42℃下胁迫3 d,测定了蝴蝶兰幼苗的生理指标变化。结果表明:当壳聚糖浓度由25 mg·L~(-1)增大到100mg·L~(-1)时,蝴蝶兰幼苗叶片的SOD、POD、CAT活性、脯氨酸、可溶性糖、叶绿素和类胡萝卜素含量不断增加,而质膜透性和丙二醛含量不断下降,但可溶性蛋白含量没有显著变化;特别是在100 mg·L~(-1)时,SOD、POD和CAT活性、脯氨酸、可溶性糖、叶绿素和类胡萝卜素含量增加到最大值且极显著高于对照,而质膜透性和丙二醛含量下降至最小值且极显著低于对照,蝴蝶兰幼苗遭受了轻微的高温伤害;随着壳聚糖浓度由200 mg·L~(-1)增大至400mg·L~(-1),SOD、POD和CAT活性、脯氨酸、可溶性蛋白、可溶性糖、叶绿素和类胡萝卜素含量极显著下降,而质膜透性和丙二醛含量极显著上升,蝴蝶兰幼苗的受害趋于加重;由此可见,100 mg·L~(-1)壳聚糖处理能显著提高蝴蝶兰幼苗的耐热性。     

外源精胺对水分胁迫下小麦幼苗保护酶活性的影响

通过营养液培养试验,研究了水分胁迫下外源精胺(Spm)对抗旱性不同的小麦品种幼苗叶片质膜相对透性及保护酶活性的影响.结果表明:水分胁迫下,小麦叶片的质膜相对透性、M DA含量增加、SOD、CAT和POD活性上升,外源精胺处理可延缓水分胁迫下小麦叶片质膜相对透性和M DA含量上升,提高了SOD、CAT、POD酶活性的上升幅度;并且对抗旱性弱的品种保护酶活性增幅高于抗旱性强的品种.因此,外源精胺处理对抗旱性弱的品种缓解水分胁迫作用大于抗旱性强的品种.     

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.