汞对水稻幼苗部分生理生化指标的影响

目的:探究Hg2 对水稻幼苗生长的影响。方法:通过水培实验,研究分析了水稻幼苗在不同浓度Hg2 (0~2.0mmol/L)胁迫下株高、鲜重、叶绿素含量和过氧化物酶(POD)活性的变化。结果:表明0.05mmol/L的Hg2 短时间内对水稻幼苗生长有一定的促进作用,高于0.05mmol/L的处理,随着Hg2 浓度的增加,植株生长明显受到限制。当Hg2 浓度≤0.1mmol/L时,POD活性先上升后下降,而Hg2 浓度≥0.5mmol/L时则持续降低。结论:Hg2 对水稻幼苗生长抑制程度与处理浓度和处理时间成正相关。     

重金属对水稻和小麦DNA甲基化水平的影响

和对照相比,0．025（或0.05)-0.1mmol/L的Cu^2 （或0．05）－1．0mmol/L的Cd^2 或Hg^2 导致水稻（或小麦）叶DNA中的5－甲基胞嘧啶百分含量大幅度上升;当Cu^2 浓度＞0.1mmol/L时,小麦和水稻叶DNA中5－甲基胞嘧啶的百分含量随Cu^2 浓度的增高略有下降,但仍高于对照。0.1-1.0mmol/L的Cu^2 ,Cd^2 和Hg^2 也导致小麦穗DNA为5－甲基胞嘧啶的百分含量随Cu^2 ,Cd^ 和Cd^2 能使小麦和水稻根系DNA中5－甲基胞嘧啶的百分含量显著高于对照,而0.1-1.0mmol/L的Hg^2 以及1．0mmol/L的Cu^2 和Cd^2 则造成小麦和水稻根系DNA中5－甲基胞嘧啶的百分含量显著低于对照。     

Hg2+、Cd2+和Cu2+对菹草光合系统及保护酶系统的毒害作用

研究了Hg2 、Cd2 、Cu2 对高等水生沉水植物菹草光合系统及保护酶系统的毒害作用。结果表明 :3种离子均使菹草叶片叶绿体自发荧光强度、叶绿素含量、光合速率降低。Hg2 、Cd2 、Cu2 对菹草保护酶系统存在不同的影响 ,短时间低浓度条件下 ,诱导超氧化物歧化酶 (SOD )、过氧化氢酶 (CAT)、过氧化物酶(POD)活性上升 ,随着污染时间的延长、污染浓度的增加 ,酶活性下降 ,其中SOD活性上升持续时间最长 ,下降最慢。 3种离子均使菹草可溶性蛋白含量减少。Hg2 、Cu2 毒性较强 ,Cd2 毒性较弱。Hg2 、Cu2 对菹草的致死浓度为 0 .5～ 1mg/L ,Cd2 为 1～ 2 .5mg/L     

几种重金属离子对光倒刺鲃胚胎发育的毒性

在水温24～26℃条件下,采用半静止式生物毒性实验法,分析了不同浓度的Cu2 、Zn2 、Cd2 对光倒刺纪(Spinibarbus hollandi)胚胎发育的毒性效应,以及Cu2 -Cd2 、Pb2 .-Zn2 对光倒刺钯胚胎发育的联合毒性效应.结果表明,在各种不同浓度的重金属离子溶液实验组中胚胎的孵化率均较低,与对照组差异极显著(P＜0.01);各种重金属在胚胎发育过程中引起各种畸形;除了Cu2 ≥0.10 mg/L、Cu2 -Cd2 ≥0.50 mg/L、Pb2 -Zn2 ≥2.00 mg/L实验组会促进胚胎发育速率外,其余各种离子溶液的各实验组均在不同程度上减慢胚胎的发育速率.3种重金属对光倒刺(鱼巴)胚胎发育的毒性效应表现为Cu2 ＞Cd2 ＞Zn2 .Cu2 、Cd2 、Zn2 、Cu2 .-Cd2 混合、Pb2 -Zn2 混合离子对光倒刺(鱼巴)胚胎发育的安全浓度分别为0.009 ms/L、0.065 mg/L、0.023mg/L、0.011mg/L、0.523 mg/L.Cu2 与Cd2 对光倒刺(鱼巴)胚胎的联合毒性为拮抗作用.     

外源半胱氨酸对铜胁迫下小麦幼苗生长、铜积累量及抗氧化系统的影响

采用滤纸培养法,研究了不同浓度的L-半胱氨酸（L-Cys）对200μmol/L铜离子胁迫下小麦幼苗生长、铜积累量、和抗氧化系统的影响。结果表明,（1）200μmol/L的铜离子可抑制小麦幼苗生长,使根长、生物量、总叶绿素含量极显著下降,可溶性蛋白和还原性谷胱甘肽（GSH）含量,超氧化物歧化酶（SOD）和抗坏血酸氧化酶（APX）活性略微上升,丙二醛（MDA）含量和细胞膜透性极显著上升。（2）外源Cys在1.0—5.0mmol/L时,受铜胁迫的小麦幼苗生长势与对照无差异,在1.0和2.5mmol/L下,根长、生物量、叶绿素a和总叶绿素含量与对照无显著差异,与Cu处理组差异显著（P<0.01）。（3）高于1.0mmol/L的外源Cys可极显著增加铜胁迫下小麦叶片和根系中的铜积累量。（4）外源Cys极显著提高了铜胁迫下小麦幼苗可溶性蛋白和GSH含量,并使SOD和APX活性持续维持在较低水平;外源Cys浓度低于2.5mmol/L时,MDA含量极显著下降,低于5.0mmol/L时,细胞膜透性极显著升高;多酚氧化酶（PPO）活性先上升后下降,除Cys为0.5mmol/L处理外,其它各处理间PPO活性均无显著差异。综合来看,喷施1.0—2.5mmol/L的外源Cys可提高小麦幼苗对铜胁迫的耐受性。     

施用N、P、K肥后铜对小麦种子萌发和幼苗生长影响的研究

以不同质量浓度Cu处理下小麦种子萌发和幼苗生长的状况为对照 ,研究增施N、P、K肥后 ,小麦种子萌发和幼苗生长所受到的影响。结果表明 :施加N、P、K肥有利于叶绿素的合成。在低质量浓度Cu( 2 0～80mg/L)条件下 ,施加N、P、K肥有利于增强小麦淀粉酶的活性 ,促进小麦种子的萌发 ,高质量浓度Cu( 1 5 0～3 0 0mg/L)条件下 ,施加N、P、K肥降低小麦淀粉酶活性 ,抑制小麦种子的萌发。施肥后 ,小麦脯氨酸含量较对照组均有所上升     

铜胁迫对穿心莲幼苗生长及生理特性的影响

通过对盆栽穿心莲(Andrographis paniculata)幼苗浇灌Cu SO4溶液实验,研究外施Cu2+对穿心莲幼苗的生理特性和药效成分含量的影响。结果显示,外施Cu2+对穿心莲幼苗的生长、生理生化指标和穿心莲内酯、脱水穿心莲内酯的含量均有显著影响。当Cu SO4溶液浓度超过6.25 mmol/L时,Cu2+能显著抑制穿心莲幼苗株高、叶长、叶宽的增长,且随胁迫时间的延长和Cu2+浓度的增大抑制作用增强;穿心莲叶片中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量均随Cu2+浓度增大和胁迫时间的延长而升高,当Cu SO4溶液浓度达到12.5 mmol/L且胁迫20 d和30 d时,叶片中SOD活性达到对照组的168.3%和171.18%;过氧化物酶(POD)、过氧化氢酶(CAT)活性则随Cu2+浓度的增大呈先升高后下降的趋势;当外施Cu SO4溶液浓度大于1.25 mmol/L时,与对照相比,穿心莲药效成分穿心莲内酯和脱水穿心莲内酯的含量均显著降低(P0.05)。研究结果表明,外施Cu SO4溶液浓度高于6.25 mmol/L时,能显著影响穿心莲幼苗的生理特性和有效成分含量,从而降低穿心莲药材的产量和质量。     

CO2倍增对不同氮水平下小麦幼苗根系及叶片NR活性的影响

以小麦品种'小偃22'幼苗为材料,采用开顶式气室和水培实验研究了不同供氮水平(2.5、5.0、10.0和 15.0 mmol·L-1)下小麦幼苗植株生长量、根系形态、有机碳分泌速率和硝酸还原酶(NR)活性对大气CO2浓度升高的响应.结果显示,大气CO2浓度倍增均增加了小麦幼苗各生长阶段根冠生物量以及根系长度、面积、有机碳分泌速率和叶片NR活性.随供氮水平的提高,各生长阶段幼苗根冠生物量、根长和面积以及叶片NR活性呈上升趋势,而有机碳分泌速率呈下降趋势;根冠比变化不同阶段表现不一致,一叶一心期呈下降趋势,二叶一心期和三叶一心期分别以15.0和10.0 mmol·L-1氮水平较高.研究表明,大气CO2浓度升高可促进小麦幼苗根系生长和有机碳分泌速率,提高其氮素同化能力;增加介质供氮有利于高CO2浓度条件下小麦幼苗根冠生长和氮素同化,提高根冠比,减少根系有机碳过度分泌引起的碳损耗.     

一氧化氮对盐胁迫下小麦幼苗根生长和氧化损伤的影响

0.05和0.10 mmol/L一氧化氮(NO)供体硝普钠(sodium mtropmsside,SNP)处理明显减轻NaCl浓度为150 mmo1/L左右的盐胁迫对小麦幼苗根生长的抑制效应,其中0.05mmol/L的SNP效果最明显;0.30mmol/L以上的SNP处理对根抑制无明显缓解作用;当NaCl浓度大于300 mmol/L时,各种浓度的SNP均不能减轻盐胁迫对根生长的抑制.以N O清除剂血红蛋白(hemoglobin,Hb)以及NOx-,K3Fe(CN)6等为对照,观察到0.05 mmol/L的SNP能不同程度地提高150mmo/L盐胁迫下小麦幼苗根尖细胞中超氧化物歧化酶(SOD)、过氧化物酶(POD)和抗坏血酸过氧化物酶(ascorbateperoxidase,APX)活性,明显降低MDA、H2O2和O2-.的积累,阻断盐胁迫诱导的根尖细胞DNA片段化,表明NO能有效缓解盐胁迫引起的小麦幼苗根尖细胞的氧化损伤.     

外源脱落酸对小麦幼苗抗镉胁迫能力的影响

以小麦(Triticum aestivum L.)为试材,采用水培法研究了100mg/L镉(Cd2+)胁迫条件下施用外源脱落酸(ABA)对小麦幼苗生长及某些生理生化指标的影响。结果表明:(1)100mg/L Cd2+胁迫下,小麦叶片膜脂过氧化产物丙二醛(MDA)含量显著提高,植株生长受到抑制;(2)外源ABA能够明显提高Cd2+胁迫小麦幼苗的根系活力,增加其叶片SOD、CAT和POD活性,促进其脯氨酸积累,降低MDA的含量,并以5.0μmol/L ABA的效果最明显;(3)1.0～5.0μmol/L外源ABA不同程度地缓解Cd2+胁迫对小麦幼苗生长的抑制作用,且5.0μmol/L时效果最明显,其株高、根长、总干重分别比单一Cd2+胁迫处理显著提高6.73%、149%和10.52%,而10.0μmol/LABA反而加重了Cd2+对小麦幼苗生长的伤害。因此,适宜浓度的外源ABA能够通过增加体内保护酶活性和脯氨酸含量来缓解Cd2+胁迫对小麦幼苗生长的抑制作用,增强小麦幼苗的抗Cd2+胁迫能力,并以5.0μmol/L ABA处理效果最好。     

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.