籼型杂交稻亲本成熟胚愈伤组织再生体系的建立

本文给出了6个籼型杂交稻亲本成熟胚愈伤组织再生体系建立优化措施。采用6个有重要育种价值的杂交籼稻亲本成熟胚盾片诱导愈伤组织作为分化再生的外植体,通过调节2,4-D浓度、培养基成分、接种方式、激素组合和愈伤组织分化途径,建立适合籼稻遗传转化的再生体系。结果表明,MB培养基是较为合适的愈伤组织诱导培养基类型,6个品种在MB培养基上的愈伤组织诱导率均在60％-80％之间。半粒米的接种方式能够明显提高愈伤组织诱导率,提高幅度达到28．2％。通过调节2,4-D浓度和激素组合,愈伤组织诱导率最高可达到97．9％,两步分化法和适当干燥处理能够提高愈伤组织的分化效率,6品种愈伤组织分化率均在50％-90％之间。初步建立了6个杂交籼稻亲本品种成熟胚愈伤组织的再生体系,为以后遗传转化奠定基础。     

反向核不育水稻FHS组织培养高频率植株再生

以反向核不育水稻品系FHS为研究材料,对其成熟胚愈伤组织的诱导及其再生条件进行了研究。研究结果表明,通过选择合适的培养基和调节2,4-D的浓度,胚性愈伤组织的诱导率可以达到92.5%。通过调节MS培养基中KT和NAA的浓度,并加入适量的CuSO4,植株再生频率高达81.3%。由此可见,合适的激素浓度的高低与FHS植株再生频率的高低呈现出一定的相关性。     

影响小麦成熟胚再生频率因素的研究(简报)

以小麦成熟胚为外植体,研究了基本培养基、预处理类型、接种方式、植物激素的浓度和不同组合以及分化培养基中是否添加抗生素对愈伤组织诱导和分化的影响．在此基础上建立了一套高效的小麦成熟胚植株再生系统。经过试验,我们选择在MS培养基上接种经无菌水预处理的纵切成熟胚作为起始的试验条件。在含2mg／L2,4-D的MS培养基上．初级愈伤组织的诱导频率可达80％以上．在继代培养基中添加0．5mg／L6-BA和0．2mg／LNAA可以显著提高胚性愈伤组织的产生。而在再生培养基中加入适当浓度的头孢霉素可以有效提高胚性愈伤组织再生出小植株的比例。利用该再生系统,我们从5个小麦优良主栽品种的成熟胚再生出了可育的植株,再生频率达15．3％-34．5％。     

硬粒小麦×天蓝偃麦草属间杂种无性系的建立

本实验以“人民麦”ד天蓝偃麦草”F_0成熟胚、F_1幼穗及“珂珂瑞特”ד天蓝偃麦草”F_1幼穗为外植体,在MS+2mg/L2,4-D的培养基上诱导愈伤组织,在无激素的MS培养基上诱导再生植株。产生胚性愈伤组织的频率最高为78.9％。植株再生方式为体细胞胚胎发生方式,再生频率最高为100％。胚性愈伤组织经13个月的继代培养仍具再生能力。发现一种特殊分化现象,即小花结构的分化,并对产生这种现象的原因进行了分析。     

不同基因型玉米的再生能力和胚性与非胚性愈伤组织DNA的差异

研究了细胞分裂素在玉米愈伤组织诱导和植株再生中的作用,结果表明低浓度（０ ．２ ｍｇ／Ｌ） 的细胞分裂素能促进玉米幼胚诱导的愈伤组织再生,６ＢＡ 的效果比ＫＴ更好。不同品种的玉米幼胚诱导的愈伤组织的再生能力差异显著,普甜１ 号和苏玉１ 号的再生频率高达７８ ％ 和７５ ％ ,糯玉米和掖单９ 号仅为１０ ％ 和８ ％ 。植株再生途径也有所不同,普甜１ 号以器官发生为主要途径,苏玉１号则以体胚发生途径为主。经长期继代的愈伤组织失去再生能力,通过ＲＡＰＤ 方法比较发现胚性与非胚性愈伤组织的基因组之间存在差异,说明组织培养过程中愈伤组织的ＤＮＡ 发生了变异。     

提高小麦愈伤组织分化频率的因素

研究了影响小麦愈伤组织诱导、芽分化及其植株再生的一些因素。结果表明：在愈伤组织诱导和继代过程中添加ＡＢＡ（１．０ｍｇ／Ｌ）有利于小麦中晚期幼胚致密愈伤组织的诱导及再生能力的保持;外植体来源尤其是基因型对长期培养的愈伤组织再生能力有很大影响;不同的外源激素（ＫＴ、６－ＢＡ、ＩＡＡ、ＴＤＺ和玉米素等）也影响芽分化频率,其中ＴＤＺ可明显提高芽分化频率;在转入分化培养前对愈伤组织进行干燥处理可有效地提高其     

大麦成熟胚愈伤组织的诱导和植株再生的研究

以10个大麦优良品种为实验材料,成熟胚为外植体,研究基因型、种子的不同切割方式、培养基、激素等对大麦成熟胚愈伤组织的诱导及植株再生的影响.结果表明,种子纵切后接种出愈率显著高于横切;改良MS培养基能提高出愈率;在愈伤组织诱导过程中,不同品种对激素2,4-D与Dicamba的反应表现不同;初代愈伤组织经过3次继代培养后会转变为两种类型的胚性愈伤组织;不同品种的植株再生在不同浓度有机添加物的分化培养基上表现不同;长时间的继代培养,一些品种在植株再生过程中出现一定数量的白化苗.供试材料均能进行愈伤组织诱导,但是只有部分品种能再生植株.本实验筛选出愈伤组织诱导频率和绿苗分化率均较高,适合于遗传转化的受体材料,如87-3175、87-0053、97-4010、97-6004及208813-509.     

不同基因型玉米的再生能力和胚性与非胚性愈伤组织DNA的差异

研究了细胞分裂素在玉米愈伤组织诱导的植株再生中的作用,结果表明低浓度（０．２ｍｇ／Ｌ）的细胞分裂素能促进玉米幼胚诱导的愈伤组织再生,６－ＢＡ的效果比ＫＴ更好。不同品种的玉米幼胚诱导的愈伤组织的再生能力差异显著,普甜１号和苏玉１号的再生频率高达７８％和７５％,糯玉米和掖单９号仅为１０％和８％。植株再生途径也有所不同,普甜１号以器官发生为主要途径,苏玉１号则以体胚发生途径为主。经长期继代的愈伤组织失去     

几种匍匐翦股颖成熟胚愈伤组织诱导及植株再生

利用成熟种子作为外植体,分析了2,4-D对匍匐翦股颖胚性愈伤组织诱导与植株再生体系的影响,并对体细胞胚的发生过程进行了观察.实验结果表明,在2.0 mg/L 2,4-D 0.1 mg/L 6-BA时胚性愈伤组织的诱导频率最高.随着2,4-D浓度的增加,愈伤组织的诱导和分化能力明显下降.在再生过程中采用1.0 mg/L的6-BA达到了比较好的效果,愈伤组织的再生频率大部分在90%以上.同时发现适当提高肌醇浓度可以使苗长得较为粗壮.在实验中发现匍匐翦股颖的体细胞胚发生过程为球形胚、心形胚、鱼雷胚和子叶胚.     

基因型和胚龄对小麦未成熟胚离体培养反应的影响

本文对34种基因型的小麦未成熟胚在离体培养中的反应进行了比较。结果表明,94％的供试基因型愈伤组织诱导率都可达到80％以上,若排除供体植株环境条件的不同和接种过程中的人为因素可能造成的影响,不同基因型的愈伤组织诱导率看来没有根本的差异。愈伤组织分化率因基因型的不同变动在0—60％之间,平均为32.7％。虽然同一基因型的盾片愈伤组织分化率在不同年份中有所不同,但是愈伤组织是否具有再生能力?看来是个稳定的遗传性状。因此小麦未成熟胚对愈伤组织诱导的反应和愈伤组织的再生能力可能具有不同的遗传基础。本文的结果还表明,虽然最适于培养的未成熟胚的大小为1毫米左右,伹小至0.3毫米的未成熱胚仍能以几乎100％的频率形成愈伤组织,60％左右的愈伤组织能分化出再生檀株,只是所需的时间比1毫米左右的胚较长。     

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.