茴香组织培养中体细胞胚胎发生的组织细胞学研究

将茴香幼茎或叶柄的愈伤组织转入附加6-BA和低浓度2,4-D的MS培养基以后,愈伤组织逐步由松软状转变成为颗粒状的胚性愈伤组织,胚状体起源于胚性愈伤组织中的单个细胞或胚性细胞团。在含NAA和6-BA的培养基中,胚状体发育成熟,并再生小植株。茴香的胚状体主要以单细胞内起源方式发生。首先由胚状体单个原始细胞分裂形成2-细胞原胚,2-细胞原胚以三种方式进行分裂:1.T- 形分裂;2.直线形分裂;3.田字形分裂。不同的分裂方式决定了胚柄的有无。茴香胚状体的发育过程与合子胚基本相同。由原胚发育成为球形胚,依次经过心形胚和鱼雷胚阶段,形成成熟的子叶胚。在胚状体发育的每一个阶段,都有其分生组织的活动中心。球形胚期,两团分生组织位于胚体中部对应的两点;心形胚期,位于两侧和中部;鱼雷胚期,分生组织的分布在子叶形成区域呈倒“U”形,在下胚轴部位呈中空的梭形。到子叶期,分生组织从两片子叶伸向胚根,呈“Y”形分布。两子叶间产生茎生长点,由生长点分化出叶原基。胚状体最终发育成为完整植株。     

2，4-D诱导的花生体细胞胚发生的组织学研究

花生成熟胚胚叶在MS附加 2 0mg/L 2 ,4_D的培养基上诱导 2 0d后 ,转移至无激素培养基MS0 继续培养 ,可获高频体细胞胚发生。组织学观察表明 ,体细胞胚起源于胚叶上表皮及表皮下数层细胞 ,这些细胞脱分化形成细胞质浓厚、细胞核大的胚性细胞团 ,胚性细胞团继续分裂形成体细胞胚。体细胞胚的发育过程经历球形胚、心形胚、鱼雷胚、子叶胚四个时期     

2,4-D诱导的花生体细胞胚发生的组织学研究

花生成熟胚胚叶在佃附加20mg/L 2,4-D的培养基上诱导20d后,转移至无激素培养基MS0继续培养,可获高频体细胞胚发生。组织学观察表明,体细胞胚起源于胚叶上表皮及表皮下数层细胞,这些细胞脱分化形成细胞质浓厚、细胞核大的胚性细胞团,胚性细胞团继续分裂形成体细胞胚。体细胞胚的发育过程经历球形胚、心形胚、鱼雷胚、子叶胚四个时期。     

辣椒游离小孢子细胞团培养的胚状体形成

从预培养15天后的花药中机械游离小孢子及其细胞团,经28℃液体悬浮暗培养．30天后,获得了自球形期胚到子叶期胚发育程度不等的各类胚状体。从12个花药中可以形成高达22个胚状体,且子叶期胚的比例约为23％。显微镜检表明,这些胚状体来自游离的小孢子细胞．经核的对称分裂形成多核细胞或者早期形成多细胞团,最后经细胞的分裂分化形成。胚状体体表具毛,活力有差异。在适当培养基上,具活力的鱼雷期及子叶期胚状体均能发育成正常植株。7℃、32℃、35℃8天的胁迫处理均能诱导小孢子胚状体发生。但花药培养中7℃、35℃处理下的出胚率较32℃下高,而游离小孢子细胞团培养中以35℃、32℃下较好。7℃处理下获得的胚状体数很少．对产生这种现象的原因进行了探讨。出胚率在基因型间,不同胁迫处理温度间表现明显差异。而在温度处理的不同天数间差异不明显。流式细胞仪对再生株真叶的DNA含量分析表明．获得的再生株中具有单倍体、双单倍体以及单倍一双倍嵌合体植株。本结果为进一步开展辣椒雄性生殖途径的胚状体发育研究。提高辣椒成熟胚状体的频率提供了实验体系。     

油茶子叶体细胞胚形成的细胞学观察

以油茶子叶块为外植体,在附加2.0mg·L-1 2,4-D和1.0mg·L-1KT的MS培养基上进行培养,观察诱导产生的体细胞胚性愈伤组织细胞学结构.结果表明:油茶体细胞胚可直接起源于表皮或近表皮的单细胞原胚或者多细胞团.其中,单细胞原胚先分裂形成二细胞原胚,二细胞原胚再进一步分裂后聚集形成多细胞团,最终经过球形胚、梨形胚、心形胚发育形成一个完整的体细胞胚.     

水稻愈伤组织内部胚性细胞的形成及发育

发育成胚状体的水稻愈伤组织表面胚性细胞, 在继代过程中被非胚性细胞旺盛的分裂所包围, 渐渐形成内部胚性细胞。其形态结构与表面胚性细胞相同, 但周围缺乏表面细胞下面的一层至几层含丰富的淀粉粒的细胞。内部胚性细胞形成团后先在以处形成突起, 产生根冠原, 逐渐形成根而突出愈伤组织。内部胚性细胞可向四周同时但不同步形成根冠原。未见芽或胚状体从内部胚性细胞产生。推测胚性愈伤组织失支胚胎发生能力及分化能力可能部分地与胚性细胞部分裂或分裂不旺盛、而非胚性细胞分裂旺盛从而使胚性细胞被包围、稀释有关。     

玉米花粉胚状体发育过程中DNA,RNA蛋白质含量及合成动态变化

继代培养的玉米花粉胚状体的发育过程可划分为6个时期:胚性细胞团时期、球形胚时期、心形胚时期、梨形胚时期、子叶形胚时期以及分化期。我们应用微量生化分析技术以及放射性同位素液体闪烁计数技术研究了玉米花粉胚状体发育过程的DNA、RNA、蛋白质含量及合成动态,发现DNA、RNA和蛋白质含量在胚性细胞团期较高,然后下降,但到了分化期时又有所升高。DNA合成速度在胚性细胞团时期较高,在以后的各时期降低并保持平稳。RNA和蛋白质的合成动态呈相似的变化规律。这个结果说明DNA、RNA和蛋白质在胚状体发育早期的活跃代谢,可能与胚性细胞的快速分裂以及胚性结构的形成有关,而后期的活跃代谢可能与胚状体的分化有关。     

水稻愈伤组织内部胚性细胞的形成及发育

发育成胚状体的水稻愈伤组织表面胚性细胞,在继代过程中被非胚性细所包围,渐渐形成内部胚性细胞。共形态结构与表面胚性细胞相同,但周围缺乏表面细胞下面的一层至几层含丰富的淀粉粒的细胞,内部胚性细胞形成团后行然以外形成突起,产生根冠原,逐渐形成根而突出愈伤组织,内部胚性细胞可向四周同时但不同步形成根冠原,未见芽或胚状体从内部胚性细胞产生,推测胚性愈伤组织失支胚胎发生能力及分化能力可能部分与胚性细胞部分裂或分裂不旺盛、,而非胚性细胞分旺盛从而使胚性细胞被包围,。稀释有关。     

黄瓜胚性细胞悬浮培养及其原生质体的植株再生

黄瓜子叶原生质体来源的胚性愈伤组织,在液体培养中形成胚性悬浮细胞系,已继代两年,仍保持胚胎发生能力,不同的ABA和蔗糖浓度对胚状体的生长发育和同步化有明显影响。1mg/l的ABA和7－9％的蔗糖能显著地减少培养物的愈伤化,并同步地控制胚状体处于球形或球形后期,低浓度的蔗糖（1％）有利于胚状体的早期萌发,继代3－5天的胚性是浮细胞团酶解后,获得大量有活力的原生质体,原生质体在DPDK,液滴或浅层培养,或褐藻酸钠包埋培养中活跃分裂,形成细胞团和球形胚,转至固体培养基上或将包埋培养物直接转入液体振荡培养,胚状体可不断增殖,胚状体在大量元素减半,不加外源激素的MS培养基上发育成小植株。     

黄连体细胞胚胎发生的研究

黄连(Coptis chinensis)叶片外植体在 MS 2,4-D 1 ppm 培养基上很容易产生愈伤组织。愈伤组织在转入分化培养基 MS 6-BA 0.5ppm NAA 1ppm 培养基上以后,能产生大量胚状体。胚状体可经过球形、心形、鱼雷形及子叶期等诸阶段发育成小植株。对胚状体用4%的藻酸钠和2%的氯化钙进行人工种皮包埋后,在无菌条件下,胚状体转变成苗。愈伤组织在分化培养基上经几次继代后,整个愈伤组织可转变为胚性愈伤组织并形成一个个胚性细胞团。胚状体可从其表面或愈伤组织内的任一细胞团产生。这一研究结果为获得大量分散的单个胚状体及人工种子的研制提供了良好的实验系统。     

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.