冷敏感植物的低温光抑制及其生化保护机制

阐述了冷敏感植物光抑制的发光机理、光与低温在光抑制中的关系及冷敏感植物在低温光抑制过程中的生理化变化,并结合冷锻炼对植物的影响,介绍了植物防制光破坏的生化机制。     

低温对黄瓜光系统Ⅱ的影响

以对低温敏感的植物黄瓜（Cucumis Sativus L.)为材料,研究了冷害温度对光合作用的影响,冷害温度对光合作用中的光系统I无伤害,而抑制了光系统II的活性,使黄瓜叶片或叶绿体的可变荧光,放氧活性,DCIP光还原活性都受到明显抑制,加入人工电子供体可使受到抑制的可变荧光,DCIP光还原活性恢复到对照水平,表明冷害温度对黄瓜光系统II的抑制是发生在光系统II的氧化侧而对光系统II的反应中心无伤害。     

低温对黄瓜光系统Ⅱ的影响

以对低温敏感的植物黄瓜（Cucumis Sativus L.)为材料,研究了冷害温度对光合作用的影响,冷害温度对光合作用中的光系统I无伤害,而抑制了光系统II的活性,使黄瓜叶片或叶绿体的可变荧光,放氧活性,DCIP光还原活性都受到明显抑制,加入人工电子供体可使受到抑制的可变荧光,DCIP光还原活性恢复到对照水平,表明冷害温度对黄瓜光系统II的抑制是发生在光系统II的氧化侧而对光系统II的反应中心无伤害。     

果品蔬菜的冷害现象

在植物的逆境生理中,低温胁迫对植物造成的伤害已引起人们广泛的关注和研究。低温伤害可分为冻害和冷害两大类型,冻害是指冰点以下低温引起植物体内结冰(细胞间隙结冰或细胞内结冰),使原生质脱水凝固或受机械损伤而造成的伤害现象。冷害主要是指热带、亚热带植物由于冰点以上低温(10—12℃)引起的代谢失调而造成细胞伤害的现象。根据植物对冷害的反应速度可将冷害分为两类:一是直     

植物抗冷分子生物学研究进展（综述）

温度是植物生长的必要条件,然而低温却是限制作物生产的重要因素,为此,各国政府及研究部门一直都把植物低温适应性问题作为一个重要的研究课题．按照低温的不同程度,植物的低温伤害可分为冷害（ｃｈｉｌｌｉｎｇ ｉｎｊｕｒｙ;零上低温对植物的伤害）和冻害（ｆｒｅｅｚｉｎｇ ｉｎｊｕｒｙ;零下低温对植物的伤害）两大类。早期关于植物冷害机理和抗冷机理的研究,是从比较冷敏感（ｃｈｉｌｌｉｎｇ－ｓｅｎｓｉｔｉｖｅ）植物和抗冷（ｃｈｉｌｌｉｎｇ－ｉｎｓｅｎｓｉｔｉｖｅ）植物或比较未经冷驯化的植物（ｎｏｎ－ｃｏｌｄ－ａｃ…     

光和暗条件下低温对黄瓜和水稻叶绿素蛋白质复合体的影响

本试验以黄瓜和水稻幼苗为材料,研究了光照和黑暗条件下低温对植物叶绿素蛋白质复合体的影响。SDS—PAGE电泳结果表明:5℃及12h 280μmol m~(-2)S~(-1)处理2d,Chl-蛋白质复合体的降解明显大于5℃暗低温处理;低温与光照对P700-CPa_1的影响大于LHCP。叶绿素荧光测定表明;5℃及12h 280μmol m~(-2)s~(-1)的处理对PSⅡ的影响亦大于暗低温处理。由此认为:低温与光对植物叶绿体的PSⅠ和PSⅡ都有明显的影响,其机理可能与常温下高光强引起的光抑制相类似;不同的是低温下中等光强就能引起光抑制。因此,在光照低温下往往加剧植物冷害的发生。     

植物的抗性生理（二）

2植物的抗寒性低温会使作物受到不同程度的伤害以至死亡,按照低温的不同程度,植物受到的伤害可分为冻害和冷害2大类。冻害是气温下降到冰点以下,植物体内结冰所致。我国北方地区晚秋和早春,寒流入侵,气温骤降,常常造成越冬作物和果木的严重冻害。冷害是零度以上低温对植物的伤害。常会引起喜温植物的生理障碍,代谢失调,受伤以至死亡。植物的抗寒性研究对于农林业生产十分重要。那么,具备抗寒性特点的植物是如何感知寒冷,又是如何产生对寒冷的适应性呢？2．1植物对寒冷信号的感受和传导抗寒基因表达为抗寒力的过程,也就是植物体内…     

低温胁迫下植物线粒体膜与抗氰呼吸的关系

主要论述了植物处于低温胁迫下其线粒体膜脂与膜蛋白的变化以及在低温伤害反应中植物所产生的活性氧对抗氰呼吸的影响。     

关于水稻的耐光抑制和育种问题

高光强对植物的伤害可分为两个方面:一是光合活动的受抑,通常称为光合作用的光抑制。二是叶绿素的漂白和细胞的破坏,由于这是依光的和依氧的过程,通常称为光氧化。在C_3作物中光抑制是个普遍现象,它可能发生在分子、叶绿体、叶片的各级水平上。逆境条件(如高温、低温、干旱、盐害、大气污染等胁迫)会进一步加重光抑制,叶片易于出现光氧化伤害的失绿。这是大田常见     

植物低温光抑制及可能的光保护机制研究进展

综述了近年来有关植物低温光抑制和光保护机制的研究进展。与以往对光抑制的定义不同,现在认为光抑制既包括光对光合作用反应中心的损伤,也包括植物为避免光破坏而形成的生理生化保护机制。该文主要从三个方面展开论述:低温下光抑制发生的原因及光抑制的位点;低温光抑制时可能的光保护机制;低温光抑制下过剩光能的耗散机制。     

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.