籼稻花药培养的研究——提高愈伤组织诱导率与分化率及根芽分化

3年来通过对籼稻(Oryza sativa subsp.hsien)花药培养的研究,愈伤组织的诱导率从0.2%提高到平均为2.85%,最高达18.75%;绿苗分化率从5%以下提高到平均为13.1%最高达到45.5%。在6个籼稻品种、38个籼×籼杂种中成功地诱导出了绿苗。本文着重研究了提高诱导率的有关因素。以单核晚期花粉的花药愈伤组织诱导频率最高。籼稻花粉去分化过程相对地要求较低浓度的培养基,籼稻花药对高浓度的改良 RM-1964培养基完全没反应。用杂种的诱导率较亲本材料为高。以易于诱导愈伤组织或易于分化绿苗的品种作亲本的杂种后代,诱导率与绿苗分化率亦较高。籼稻形成愈伤组织的高峰是在接种后的50—60天之间。愈伤组织分化的高潮是在转移后10—30天之间。籼稻愈伤组织的分化以先分化根的类型最多,在先分化根的愈伤组织中有36.74%能再分化出芽来。     

紫外光照射小麦花药的研究

紫外光照射小麦花药进行组织培养,通过2年的试验结果初步表明:紫外光对诱导愈伤组织和分化绿苗有一定的作用,从多数试验材料的愈伤组织诱导率与绿苗分化率,照射1秒的比照射2秒、6秒、8秒和未照射的对照高。     

小麦成熟胚愈伤组织诱导及分化研究

以2个小麦品种成熟胚为外植体进行离体培养,研究了不同预处理、不同2,4-D浓度及与KT组合、不同蔗糖浓度等因素对愈伤组织诱导及分化的影响。结果表明:4℃低温预处理可提高愈伤组织的出愈率及再生苗率,2个材料的出愈率及再生苗率均达到90%和30%以上;在不同预处理条件下,2,4-D浓度对出愈率及再生苗率的影响与基因型有关,2,4-D浓度为1~2 mg/L更有利于愈伤组织诱导及分化;附加KT能缓解高浓度2,4-D对再生苗率的抑制作用,而对于在1、2 mg/L 2,4-D的培养基中附加KT则不表现这种作用;蔗糖浓度则在30 g/L条件下更有利于愈伤组织诱导。因此通过4℃低温预处理,在MS基本培养基中附加1~2mg/L 2,4-D及30 g/L蔗糖亦可促进小麦成熟胚愈伤组织的诱导和分化。     

提高春小麦花粉植株诱导率的研究

本文研究了影响春小麦花粉植株诱导率的几种主要因素。供试材料为1990年温室种植的杂种F_1代,试验结果表明,诱导培养基中附加细胞分裂素BA或BA与KT相结合能显著提高愈伤组织分化率;0.17M的葡萄糖加0.17M的蔗糖比用0.26M的蔗糖愈伤组织诱导率高60％以上;愈伤组织在18～25℃比在23～25℃下培养绿苗率显著提高;接种前2～3℃预处理幼穗72小时对提高出愈率和绿苗分化率有明显效果。     

佛手瓜简化培养基诱导小麦花粉植株的研究

我们研究了佛手瓜简化培养基(表1)诱导小麦花粉植株;以马铃薯简化培养基(简称“薯“)作为诱导愈伤组织的对照培养基和MS 吲哚乙酸0.5毫克/升 激动素2毫克/升(简称MS)作为愈伤组织分化的对照培养基。 愈伤组织的诱导结果是“薯”和“瓜 激素”两种培养基的诱导频率因不同材料而异(表2,表3)。多数的材料是“薯”的诱导频率较高,但这两种培养基诱导的愈伤组织转移至MS分化培养基时,前者分化白苗率较高,后者分化绿苗率较高。值得注意的是“瓜”培养基诱导的愈伤组组频率高于“瓜 激素”(表3)。 愈伤组织的分化是“瓜(分)”对愈伤组织的分化频率仅为MS的二分之一;同时前者比后者分化绿苗率也较低(表4)。然而,“瓜(分) Fe”与MS对愈伤组织的分化频率几乎相等,绿苗分化率前者高于后者(表5)。     

影响小麦花粉植株分化的几个因素

以小麦杂种Ｆ１代花粉愈伤组织为材料，研究了影响花粉植株分化的几个因素。试验结果表明，随着花药培养时间的延长．其愈伤组织的分化能力逐渐降低；分化培养基中附加ＫＴ和ＢＡ两种细胞分裂素相结合有利于绿苗分化；４℃─５℃低温处理愈伤组织２４小时能提高绿苗分化率。     

籼稻花药培养研究——Ⅰ.基本培养基及附加成分在诱导籼稻花药产生愈伤组织及根芽分化中的作用

对6个籼稻(oryza sativa Subsp.Shien)品种和39个籼×籼杂种的花药在离体条件下进行培养,有5个品种及35个杂种得到了愈伤组织,平均诱导率为2.18％。在3个品种及11个籼×籼杂种中得到了绿苗或绿芽。本文着重报道基本培养基及其附加成分在诱导籼稻花药产生愈伤组织及根芽分化中的作用。 1.试验了几种诱导愈伤组织的培养基,以Miller培养基 2,4—D2毫克/升 酵母浸出液1,000毫克/升 激动素1毫克/升 吲哚乙酸2毫克/升 椰乳15％为最好。诱导率高者可达11—15％,平均诱导率在3％以上。 2.Ms、Nitsch及Miller培养基均可诱导籼稻花药愈伤组织分化出绿色的花粉植株。 3.籼稻花药愈伤组织的分化,随着激动素/生长素比值的增高,绿苗分化率及总分化率均有提高的趋势。而粳稻的这种关系不甚明显。 4.Miller培养基附加2毫克/升的吲哚乙酸对促进具茎、叶而无根的籼稻花粉小植株产生根有很好的作用。在这种培养基上,不仅可以诱导根的发生,而且根系发达,生长较弱的苗转移到这种培养基后,因根系健壮,生势好,转入盆栽,基本可以全部成活。     

扁桃愈伤组织诱导及分化的研究

以扁桃优良品种'Naporeil'的茎段、叶片和花药作为外殖体,分别对其进行愈伤组织诱导和分化研究,以筛选愈伤组织的最佳诱导增殖培养基、分化培养基和生根培养基.结果表明,该品种以茎段、花药作为外殖体最易诱导获得愈伤组织,叶片不适宜作为外殖体诱导愈伤组织;愈伤组织的最佳诱导增殖培养基均为B5+0.5 mg/L 2,4-D+0.2 mg/L 6-BA+1.0 mg/L NAA,愈伤组织诱导率为100%,增殖倍数最高可达7倍;茎段愈伤组织的分化培养基为MS+0.2 mg/L NAA+0.8 mg/L 6-BA+0.5 mg/L ZT,分化率为71%;花药愈伤组织未见分化.由茎段愈伤组织再分化获得的不定芽在1/2MS+0.5 mg/L IBA培养基上诱导生根,并给以黑暗预处理可使生根率达80%以上.     

水稻花药液体培养下影响愈伤组织诱导和分化的一些因素的研究

水稻花药液体漂浮培养能大幅度提高愈伤组织诱导频率,但这些愈伤组织的分化能力很低。为了提高液体培养下愈伤组织的分化频率,试验了5种诱导培养基和4种分化培养基。结果表明,诱导培养基对愈伤组织分化能力的高低起主要作用,其中以过滤灭菌的马铃薯提取液培养基的效果最好,绿苗分化率可高达50％;分化培养基对愈伤组织分化频率的影响较小,且不甚规律。浮在液面上的愈伤组织比沉在培养液底部的愈伤组织有较高的分化能力。愈伤组织转移时间的早晚对分化频率也有很大影响。     

不同培养基对水稻胚性愈伤组织诱导及分化的影响

以水稻成熟胚为材料诱导愈伤组织,统计在不同基本培养基上的愈伤诱导率以及绿苗分化率,分析不同基本培养基及外源激素的含量和比例对愈伤组织生长及分化的影响。结果表明,试验材料对基本培养基具有选择性,MS培养基对籼稻种胚愈伤的诱导培养效果较好,NB培养基则更适合粳稻种胚愈伤的诱导培养;诱导继代培养基中加入多种氨基酸组合可有效提高出愈率和分化率,特别是粳稻的愈伤组织的诱导和分化需要多种氨基酸的共同作用;不同基因型水稻材料对激素和氨基酸组合的需求不同。     

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.