诱导玉米花粉植株的初步研究

玉米花药培养试验表明，以培养基M，为基础，补加2, 4-D2.0毫克／升和激动素1.0一2.0毫克／升，将蔗糖浓度作适当提高，即从‘％ 提高到12-24%范围，诱导花粉愈伤组织的频率可从0.52%提高到1. 03-1.09 % o夏季7-8月形成的愈伤组织没有分化出绿芽，只分化根。秋季9-11月形成的愈伤组织转入以ms为基本培养基，补加NAA 0.2-2。毫克／升和激动素0.5--2.0毫克／升灼分化培养基中，诱导出了绿芽、叶和根，并发育为绿色小植株。细胞学观察证明所获得的植株来源于花粉细胞。     

小麦花药培养中花药密度效应的初步研究

在大麦花药培养中,花药密度对花粉愈伤组织产量有明显影响。欲得大量的愈伤组织,每毫升液体培养基上需接种60枚甚至更多的花药。利用条件培养基,可提高单位体积培养基上花药有效密度,进而提高大麦花粉愈伤组织的产量。在水稻花药培养中,花粉愈伤组织产量也有随花药密度而提高的趋势。     

水稻花粉植株的诱导条件及影响诱导频率的某些因素

在离体培养条件下,测定了水稻花药中花粉愈伤组织形成的条件,并对影响花粉愈伤组织的形成和分化的某些因素进行了实验,得到以下主要结果: 1.掌握合适的花粉发育时期(单核后期接近第一次花粉分裂),在仅仅含有2毫克/升2,4-D和6％蔗糖的简单培养基上就得到了花粉愈伤组织,对于花粉细胞最初分裂的推动,生长素、碳源和渗透压是必要的条件。由无机盐、微量元素、维生素、糖及生长物质组成的复杂培养基对于花粉愈伤组织的发生和早期生长并非必需,但有利于愈伤组织的进一步生长。 2.培养基中蔗糖的作用,在于充当碳源和调节渗透压,在维持一定渗透压的条件下,过高浓度的蔗糖会抑制愈伤组织的形成。 3.椰乳、酪蛋白水解物及单核苷酸等有机附加物对花粉愈伤组织的形成及以后的器官分化都有明显的良好作用。 4.培养基中附加低浓度8p.p.m.、40p.p.m的2-氯乙基磷酸(乙烯利)和接种前在10℃下,预先处理稻穗48小时,都有明显的提高花粉愈伤组织发生频率的作用。 5.花粉愈伤组织的年龄对愈伤组织的器官分化能力有明显的影响,随愈伤组织年龄的增长而降低了花粉植株的诱导频率。     

改进水稻花药培养方法的途径

用液面漂浮方式培养水稻花药,研究了培养基的蔗糖浓度、激素成分、附加秋水仙碱对花粉愈伤组织的诱导、分化及花粉植株倍性的影响。提出改进水稻花药培养方法的途径,其要点是:用液体培养基培养花药;在培养初期,调整培养条件以增加对等核分裂花粉数和提高染色体加倍频率;在多细胞团花粉突破花粉壁生长之前,将其从开裂的花药中分离出来进行单花粉固着培养形成愈伤组织,并使愈伤组织在生长的早期转向分化。     

大麦花药培养中若干因素对愈伤组织形成的影响

在大麦花药培养中,提高花粉愈伤组织产量的关键在于低温预处理(Huang and Sunderland 1982)及花药因子(许智宏等1984)的利用。后者包括使用条件培养基或较高的接种密度。在培养基中附加较高浓度的肌醇(0.1％)亦能大幅度地提高花粉愈伤组织的产量(Xu and Sunderland 1981)。在     

诱导玉米花粉植株的初步研究

玉米花药培养试验表明,以培养基MS为基础,补加2,4-D2.0毫克/升和激动素1.0—2.0毫克/升,将蔗糖浓度作适当提高,即从6％提高到12—24％范围,诱导花粉愈伤组织的频率可从0.52％提高到1.03—1.09％。夏季7—8月形成的愈伤组织没有分化出绿芽,只分     

小麦(Triticum aestivum)雄核发育的细胞学研究

本工作对小麦花粉胚和愈伤组织的诱导条件和雄核发育的细胞学现象作了研究。结果如下:(1)N_6培养基诱导花粉愈伤组织的效果显著优于 MS 培养基。外源激素对于雄核发育的启动不是必需的,但对愈伤组织进一步的生长却是不可缺少的。(2)用花药整体制片法研究了雄核发育的各种途径,结果表明,不均等分裂和均等分裂的小孢子都能形成花粉胚,但前者占较大比例。(3)在部分多细胞花粉和白化苗中观察到染色体断片和微核,推测白化或畸形的花粉植株可能起源于具微核的花粉。(4)细胞的核内再复制和游离核的融合是产生二倍体和多倍体花粉植株的重要原因。     

桑树花粉愈伤组织的诱导与花粉细胞学研究

讨论影响桑树花粉愈伤组织诱导频率的问题 ,描述花粉细胞早期发育和愈伤组织的分化过程     

黑麦(Secale cereale L.)花药培养及其雄核发育

离体培养黑麦花药,单核花粉可以通过不等分裂和均等分裂由营养性质的核发育成花粉胚状体或愈伤组织,并且最后形成了单倍体植株。接种前对穗子进行适当的低温处理,可以有效地提高胚状体和愈伤组织的生成率。根据多核和多细胞花粉的败育情况,认为新壁的形成和花粉外壁的适时破裂是已经启动分裂的小孢子能否发育成胚状体和愈伤组织的两个关键问题。     

BA对大麦花药培养中药壁的衰退和植株再生频率的影响

用含20ppm 6-BA的0.1％吐温-80溶液喷施花粉为单核前期的大麦上部叶片和穗部,明显影响大麦花药培养效率。实验结果表明:1)BA处理可明显延缓培养花药的药壁衰退进程。2)BA处理后的花药,在培养期间,其死亡的花粉数比对照大大减少,相反其双核或多核的花粉数比对照明显增加。3)BA处理虽然没有促进大麦花粉愈伤组织的诱导率,但显著地促进愈伤组织的生长。提高愈伤组织成长率,增加可转入分化培养的愈伤组织块数。4)BA处理促进愈伤组织的再分化,尤其是绿苗的分化。     

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.