渗透胁迫下稻苗中铁催化的膜脂过氧化作用

在－０．７ＭＰａ渗透胁迫下,水稻幼苗体内和Ｈ２Ｏ２大量产生,Ｆｅ２＋积累,膜脂过氧化作用加剧。水稻幼苗体内Ｆｅ２＋含量与膜脂过氧化产物ＭＤＡ含量呈极显著的正相关。外源Ｆｅ２＋、Ｆｅ３＋、Ｈ２Ｏ２、Ｆｅ２＋＋Ｈ２Ｏ２、ＤＤＴＣ均能刺激膜脂过氧化作用,而铁离子的螯合剂ＤＴＰＡ则有缓解作用。ＯＨ的清除剂苯甲酸钠和甘露醇能明显地抑制渗透胁迫下Ｆｅ２＋催化的膜脂过氧化作用。这都表明渗透胁迫下水稻幼苗体内铁诱导的膜脂过氧化作用主要是由于其催化Ｆｅｎｔｏｎ型Ｈａｂｅｒ－Ｗｅｉｓｓ反应形成ＯＨ所致。     

冷锻炼对水稻和黄瓜幼苗SOD,GR活性及GSH,AsA含量的影响

水稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）和黄瓜（Ｃｕｃｕｍ ｉｓｍ ｅｌｏ Ｌ．）幼苗在昼夜温度为１５ ℃／１０ ℃、白天光照１２ ｈ,光强为２５０ μｍ ｏｌ·ｍ － ２·ｓ－ １的条件下锻炼３ ｄ,明显地提高幼苗叶片中膜保护酶——超氧物歧化酶（ＳＯＤ）、谷胱甘肽还原酶（ＧＲ）活性和内源抗氧化剂——还原型谷胱甘肽（ＧＳＨ）、抗坏血酸（ＡｓＡ）的含量。经冷锻炼和未锻炼的幼苗移置４ ℃、光强为２５０ μｍ ｏｌ·ｍ － ２·ｓ－ １下胁迫处理２ ｄ,未锻炼苗叶片中ＳＯＤ、ＧＲ 活性和ＧＳＨ、ＡｓＡ 含量明显下降,而经冷锻炼的苗则相对比较稳定。从脂质过氧化产物——丙二醛（ＭＤＡ）含量及幼苗的存活率亦看出：冷锻炼苗具有较低的脂质过氧化水平和较高的幼苗存活率。由此认为：冷锻炼能提高水稻和黄瓜幼苗细胞膜的稳定性,从而增强了耐低温光胁迫的能力     

钙对水稻幼苗抗冷性的影响

ＣａＣｌ２浸种提高水稻幼苗叶片中结合态钙、内源抗氧化剂（ＧＳＨ、ＡｓＡ）含量和膜保护酶（ＣＡＴ、ＳＯＤ和ＰＯＤ）活性,也增加可溶性蛋白质中煮沸稳定蛋白质（ｂｏｉｌｉｎｇ－ｓｔａｂｌｅｐｒｏｔｅｉｎ）的含量。冷胁迫期间,ＣａＣｌ２并能减少因冷胁迫引起的ＧＳＨ、ＡｓＡ含量,ＣＡＴ、ＳＯＤ和ＰＯＤ活性以及煮沸稳定蛋白质下降的程度。在恢复期间,经ＣａＣｌ２处理的幼苗其ＧＳＨ、ＡＳＡ、ＣＡＴ、ＳＯＤ和ＰＯＤ以及煮沸稳定蛋白质水平均有回升。     

渗透胁迫下稻苗中铁催化的膜脂过氧化作

在－０．７ＭＰａ渗透胁迫下,水和思苗体内Ｏ２↑－．和Ｈ２Ｏ２大量产生,Ｆｅ＾２＋含量与膜脂过氧化产物ＭＤＡ含量呈极显著的正相关。外源Ｆｅ＾２＋、Ｆｅ＾３＋、Ｈ２Ｏ２、Ｆｅ＾２＋＋Ｈ２Ｏ２、ＤＤＴＣ均能刺激膜脂过氧化作用,而铁离子的螯合剂ＤＴＰＡ则有缓解作用。ＯＨ的清除剂苯甲酸钠和甘露醇能明显地抑制渗透胁迫下Ｆｅ＾２＋催化的膜脂过氧化作用。这都表明渗透胁迫下水稻幼苗体内铁诱导的膜脂过氧化作用主要是由     

低温胁迫下红松幼苗活性氧的产生及保护酶的变化

在不同低温胁迫时间下,对红松（Ｐｉｎｕｓ ｋｏｒａｉｅｎｓｉｓ Ｓｉｅｂ．ｅｔ．Ｚｕｃｃ）幼苗针叶中Ｈ２Ｏ２、Ｏ＾－．２、膜脂过氧化产物丙二醛（ＭＤＡ）、组织自动化氧化速率及保护酶超氧化物歧化酶（ＳＯＤ）、过氧化物酶（ＰＯＤ）、过氧化氢酶（ＣＡＴ）和抗坏血酸过氧化物酶（ＡＳＰ）的动态变化过程进行了测定。结果表明,随着低温胁迫时间的延长,Ｏ＾－．２产生速率和Ｈ２Ｏ２含量先上升后下降;ＭＤＡ的含量呈波     

水稻幼苗冷锻炼过程中钙的效应

冷锻炼处理提高了水稻（Ｏｒｙｚａ ｓａｔｉｖａ Ｌ．）幼苗叶片中抗氧化剂（还原型谷胱甘肽,ＧＳＨ;抗坏血酸,ＡｓＡ）含量和膜保护酶（超氧化物歧化酶,ＳＯＤ）的活性,同时也提高了可溶性蛋白质中热稳定蛋白的含量。ＣａＣｌ２ 浸种处理对上述冷锻炼的作用有加强的效果,且明显地提高了过氧化氢酶（ＣＡＴ）和过氧化物酶（ＰＯＤ）的活性。有无ＣａＣｌ２ 处理的冷锻炼处理均减轻冷胁迫引起的ＧＳＨ 及ＡｓＡ 含量、ＳＯＤ 活性及热稳定蛋白质含量的下降程度,有利于幼苗在恢复过程中ＧＳＨ、ＡｓＡ、ＣＡＴ、ＳＯＤ、ＰＯＤ及热稳定蛋白质水平迅速回升。结合ＣａＣｌ２ 处理的冷锻炼苗在冷胁迫恢复生长时增长迅速,且苗健壮浓绿,说明ＣａＣｌ２浸种对冷锻炼处理提高水稻幼苗的抗冷力有明显的促进作用,这与ＣａＣｌ２ 浸种结合冷锻炼能更有效的提高细胞膜保护能力有关     

铜锌超氧物歧化酶对几种羟自由基产生系统的影响

应用脱氧核糖降解法研究了ＣｕＺｎ－ＳＯＤ对几种·ＯＨ产生系统的作用机理．结果证明：ＳＯＤ对Ｆｅ（３＋）·Ｏ·Ｈ２Ｏ２系统中·ＯＨ的产生有明显的抑制作用,而失活ＳＯＤ或ＢＳＡ对它的抑制作用不大;在Ｆｅ（２＋）·Ｈ２Ｏ２和ＣＵ（２＋）·Ｈ２Ｏ２系统中,ＳＯＤ、失活ＳＯＤ和ＢＡＳ均能抑制·ＯＨ的产生;在Ｆｅ（２＋）·Ｏ系统中,ＳＯＤ对·ＯＨ产生作用不大,而失活ＳＯＤ或ＢＳＡ对它有明显的抑制作用．由此推测ＳＯＤ对·ＯＨ形成可能有三方面的影响：１．对Ｏ的清除作用,阻断Ｈａｂｅｒ－Ｗｅｉｓｓ反应;２．对金属离子的络合作用,降低·ＯＨ的产额;３．促进Ｈ２Ｏ２的积累,加快Ｆｅｎｔｏｎ反应．     

盐度和CO2倍增环境下碱蓬幼苗呼吸酶活性的变化

研究了生长在正常大气ＣＯ２和ＣＯ２倍增环境中的盐生植物碱蓬（Ｓｕａｅｄａｓａｌｓａ）幼苗呼吸酶活性对ＫＣｌ和ＮａＣｌ的反应．结果表明,在ＣＯ２倍增（７００μｌ·Ｌ－１）和正常大气ＣＯ２（３５０μｌ·Ｌ－１）下,３００ｍｍｏｌ·Ｌ－１ＫＣｌ和ＮａＣｌ均能抑制琥珀酸脱氢酶（ＳＤＨ）和苹果酸脱氢酶（ＭＤＨ）活性,而异柠檬酸脱氢酶（ＩＤＨ）活性为ＮａＣｌ抑制、ＫＣｌ促进;ＮａＣｌ和ＫＣｌ明显抑制细胞色素氧化酶（ＣＯ）和光呼吸中乙醇酸氧化酶（ＧＯ）、羟基丙酮酸还原酶（ＨＰＲ）活性;并指出在ＫＣｌ胁迫下,ＣＯ２使三羧酸循环（ＴＣＡＣ）的运行变慢,ＮａＣｌ胁迫下使其加快,ＴＣＡＣ运行限速步骤与ＭＤＨ无关,ＣＯ为盐对呼吸代谢影响的重要位点．另外,Ｋ＋、Ｎａ＋对蛋白表达的影响有差异,ＣＯ２可使盐胁迫下的碱蓬幼苗蛋白表达降低．     

百草枯和苯甲酸钠对渗透胁迫下抗旱性不同玉米品种愈伤组织的影响

两个品种玉米愈伤组织经０．５和５ｍｍｏｌ／Ｌ的百草枯处理３ｈ后,在渗透胁迫下处理２４ｈ电解质泄漏率增加;Ｈ２Ｏ２和ＭＤＡ积累;ＡｓＡ和ＣＡＲ含量的减少加剧。０．５和５ｍｍｏｌ／Ｌ的苯甲酸钠减轻渗透胁迫诱导的氧化伤害,促进ＣＡＴ活性的增加;使ＳＯＤ、ＧＲ、ＡＰ和ＰＯＤ能维持较高的活性;ＡｓＡ和ＣＡＲ含量降低的幅度减小。     

NMR法研究天花粉蛋白TDK肽片段的溶液构象

用ＨＮＭＲ法测定ＴＤＫ肽在Ｈ２Ｏ（ＨＯＤＫ）,５０％六氟丙醇（ＦＰＤＫ）和２ｍｏｌ／ＬＧｕ．ＨＣｌ（ＧＵＤＫ）溶液构象。在ＨＯＤＫ和ＦＰＤＫ中,ＴＤＫ肽的两段序列Ａｓｐ０－Ｉｌｅ４,Ｓｅｒ９－Ｉｌｉ１７分别具有较稳定的α－螺旋含量;而ＧＵＤＫ的ＳＡＬＳ序列仍能检测到有序残存结构。并假设ＳＡＬＳ序列是肽链形成二级结构的原始核心。     

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.