采用秋水仙碱创制优质、抗热同源四倍体不结球白菜

以不同浓度秋水仙素处理二倍体不结球白菜(Brassica campestrisssp.chinensisM ak ino)子叶生长点,对变异株进行了形态解剖学、农艺学、细胞学及营养品质鉴定。结果表明:0.1 mol/L秋水仙素处理6次的效果最佳。与二倍体相比,四倍体植株、气孔、花器官均表现巨大性;气孔密度、结实率显著降低;四倍体白菜蛋白质、可溶性糖和维生素C含量比二倍体分别增加15.69%、71.25%和22.18%;夏季高温条件下四倍体表现出良好的丰产性和抗热性。     

淹水胁迫对不结球白菜渗透调节物质含量的影响

以不结球白菜‘新矮青’品种为材料,研究了不同时间(1、3、5、7d)和不同程度(根淹、半淹、全淹)淹水处理及解除淹水恢复生长后叶片内渗透调节物质含量的变化规律。结果表明:(1)在根淹和半淹胁迫处理下,不结球白菜叶片中可溶性糖、可溶性蛋白和游离脯氨酸含量随处理时间的延长呈先上升后下降的趋势;全淹胁迫下,这3种渗透调节物质的含量随处理时间的延长出现不同程度的下降。(2)解除淹水恢复生长7d后,各处理组的不结球白菜叶片中渗透调节物质的含量在短期(1d)淹水下基本恢复正常,在长期淹水条件下未完全恢复;全淹处理组恢复能力较弱,而根淹处理组恢复能力相对较强;可溶性糖的恢复幅度高于可溶性蛋白和游离脯氨酸。     

不结球白菜小孢子胚植株再生及倍性研究

以不结球白菜子叶型小孢子胚为外植体,研究冷处理、活性炭及AgNO3对小孢子植株再生的影响,并对再生植株染色体倍性进行鉴定.结果表明:对小孢子胚进行5 d的4℃冷处理培养能提高其胚芽诱导率和胚芽数;培养基中添加1.0 g/L的活性炭对提高小孢子胚芽诱导率没有明显效果,但能有效减轻胚芽的玻璃化;添加5.0或7.0 mg/L的AgNO3对小孢子胚芽诱导有显著效果.染色体倍性鉴定结果表明:不结球白菜小孢子植株的染色体自然加倍率较高,在50%～100%之间;不同基因型不结球白菜小孢子植株的倍性变异具有多样性;在部分基因型中嵌合体占较高比例,最高达到42.86%.     

野生南荻与芒杂种多倍体诱导研究

用不同浓度秋水仙素处理野生南荻×芒(Miscanthus lutarioriparia×Miscanthus sinensis)远缘杂交后代以诱导产生多倍体,并对变异株进行形态学和细胞学鉴定,以期获得稳定的四倍体植株并分析其生理特性。结果表明:(1)采用秋水仙素加入培养基处理法和秋水仙素溶液浸泡处理法都可获得一定频率的多倍体植株;胚性愈伤组织以0.2%秋水仙素浸泡处理48h的诱变效果较好,四倍体诱导率达8.7%;芽在0.05%秋水仙素培养基中处理15d较好,四倍体诱导率达10.6%;生根苗在0.1%秋水仙素培养基中处理10d较好,四倍体诱导率达11.1%。(2)经体细胞染色体计数,加倍植株染色体数为2n=4x=76,对照植株的染色体数目为2n=2x=38。(3)生长2年的多倍体植株形态、叶片大小、茎粗、茎壁厚、节间等性状表现出巨大性和超亲优势。     

四倍体不结球白菜的诱导及染色体倍性鉴定

用不同浓度秋水仙素处理子叶期不结球白菜生长点对其进行染色体倍性操作,根据形态解剖学、细胞学特征和流式细胞仪进行倍性鉴定.结果表明,浓度为0.2%的秋水仙素处理4次的效果最好,四倍体诱变率为8.42%.与二倍体相比,四倍体植株叶片、花器官、气孔等均表现巨大性;气孔密度和结实率降低;抽薹较晚.用流式细胞仪进行倍性鉴定,对照DNA相对含量为100,疑似株为200,表明是四倍体;疑似株有2个值与对照的比值约为1和2,表明是嵌合体(2x 4x).流式细胞仪鉴定结果与染色体计数法鉴定结果一致,表明流式细胞仪可以较准确地检测不结球白菜突变株倍性.     

根肿病胁迫下外源SA对不结球白菜抗性诱导和生理生化的影响

以不结球白菜‘新矮青’为试验材料,采用菌土接种法接种根肿病菌,研究不同浓度(0.2~0.8mmol·L~(-1))的外源水杨酸(SA)对根肿病胁迫下不结球白菜植株抗性诱导和感病植株生长的影响,以及植株叶片和根系中防御酶系统的变化规律,探讨外源SA对防治不结球白菜根肿病的可行性。结果显示:(1)根肿病显著影响不结球白菜的生长,加剧植物的膜脂过氧化程度;适宜浓度的外源SA能不同程度地缓解不结球白菜所受根肿病的侵害,并以0.6mmol·L~(-1) SA处理效果最好。(2)外源SA显著降低了根肿病的发病率和病情指数,提高了抗根肿病的诱抗效果,并缓解感病对不结球白菜的生长抑制,显著促进感病植株的生长。(3)外源SA提高了不结球白菜叶片和根系中的超氧化物歧化酶(SOD)、过氧化物酶(POD)和抗坏血酸-过氧化物酶(APX)的抗氧化酶活性,以及多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)、谷胱甘肽还原酶(GR)的防御酶活性;显著降低了植株叶片和根系中的MDA、H2O2含量及O-·2产生速率。研究表明,外源SA诱导不结球白菜对根肿病的抗性,缓解根肿病的伤害,且具有剂量效应,以根部灌施0.6mmol·L~(-1)SA的效果最好;在根肿病的胁迫下,SA可提高不结球白菜植株抗氧化酶和防御酶的活性,增强渗透调节能力和细胞活性氧清除能力,降低根肿病对植株的伤害,从而促进生长。     

不结球白菜幼苗对中、碱性钠盐胁迫响应差异性研究

不结球白菜(Brassica campestris ssp. chinensis)是重要的蔬菜作物,近年来由于不合理的灌溉及栽培方式导致设施土壤次生盐渍化越来越严重,对蔬菜生产造成不良影响,盐碱胁迫也会抑制不结球白菜正常生长。以往有关不结球白菜耐盐碱研究更多的是关注中性盐对不结球白菜生长与生理的影响,而有关碱性盐对不结球白菜生长与生理的研究则较少。本研究通过水培实验,设置不同的盐碱胁迫处理,研究不结球白菜对中、碱性钠盐胁迫响应差异机制。研究发现:同等胁迫浓度下,相比于中性盐胁迫,碱性碳酸盐胁迫下不结球白菜幼苗的鲜重、生物量、各个叶绿素a、叶绿素b、类胡萝卜素和总叶绿素含量降低更多。相比也中性盐,碱性盐对不结球白菜抗氧化系统影响更大,过氧化物酶(POD)和超氧化物歧化酶(SOD)活性更高MDA含量和质膜透性(MI)值更高,而过氧化酶(CAT)活性则在碱胁迫下较低。相比于中性盐胁迫,碱性碳酸盐胁迫下不结球白菜体内脯氨酸和可溶性糖的积累量更高,对不结球白菜渗透调节系统影响更大。根据实验结果得出,相比于中性盐胁迫,碱性碳酸盐胁迫对不结球白菜生长抑制作用更强,对其生理影响更大。     

不结球白菜热激蛋白基因克隆及表达

从不结球白菜'暑绿'中克隆到一个受热激诱导的小分子量热激蛋白(sHSP)基因,命名为BcHSP(DDBJ登录号为AB367955),该基因核苷酸序列全长722 bp,编码157个氨基酸,与芜菁、芥蓝、拟南芥等有90%以上的相似性.实时定量检测表明,不结球白菜BcHSP转录表达受热激诱导,以叶片中表达量最高,BcHSP在不结球白菜叶片中表达特征说明它可能与植物叶片的耐热性关系更为密切.     

大花蕙兰四倍体的离体诱导和鉴定

采用组织培养方法研究了秋水仙素处理对大花蕙兰类原球茎增殖、分化和四倍体诱导的效应.结果表明,秋水仙素处理明显抑制类原球茎的增殖和分化,提高类原球茎褐变率和死亡率;在试验浓度和时间范围内,秋水仙素浓度越高,处理时间越长,抑制作用越强,解除抑制作用所需的继代次数越多.所有秋水仙素处理均能诱导出四倍体,但不同处理的四倍体诱导率不同,当处理浓度为0.05%、时间为5 d时,四倍体诱导率最高,为23.7%.二倍体及其四倍体的气孔保卫细胞长度和气孔密度均存在极显著的差异.四倍体植株比二倍体矮,茎部较粗壮,株型紧凑,叶片颜色浓绿、质地变硬.秋水仙素处理和组织培养相结合是创建大花蕙兰多倍体的有效方法.     

不结球白菜晚抽薹BcFLC3基因的克隆及表达分析

根据大白菜BcFLC3基因(GenBank登录号AY036890.1)保守域序列设计引物,扩增不结球白菜晚抽薹BcFLC3基因的核心片段,结合RACE技术获得该基因1 017 bp的全长cDNA序列.序列分析结果表明,该cDNA包含完整开放阅读框,编码197个氨基酸的蛋白质,其分子量为21.62 kD,等电点9.36.荧光定量 PCR分析表明,不结球白菜经4℃低温处理后,BcFLC3基因在叶片中的表达量抽薹前明显高于抽薹后;低温处理后BcFLC3基因在不同部位的表达量存在明显差异,表达量由高到低依次为叶、茎、花蕾、花和根.Southern杂交结果表明,BcFLC3基因在不结球白菜基因组中为多拷贝.     

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.