向日葵未受精胚珠培养时胚状体发生的显微观察

由开花前1—4天的向日葵子房中取出胚珠,在液体培养基上进行漂浮培养,诱导了未受精的卵细胞发育为单倍体的胚状体.亦诱导了珠被绒毡层产生胚状体。对两种胚状体的发生和发育过程及其形态发生特点作了显微观察与描述。     

依兰(番荔枝科)雌配子体发育研究

荔枝科是被子植物的基部类群之一,依兰属是番荔枝科较为原始的类群,其有性生殖过程,特别是胚胎发生与发育的研究结果,可以补充被子植物胚胎学原始特征的相关基础资料。该研究利用常规石蜡切片技术,对依兰胚珠、大孢子和雌配子体的发生发育过程进行了观察。结果表明:依兰的胚珠为倒生胚珠、厚珠心、三层珠被,第三层珠被(中间珠被)发生在大孢子母细胞时期,于外珠被与内珠被之间、胚珠合点端两侧发生并隆起;雌配子体为蓼型。此外,依兰的个别胚珠中存在双雌配子体现象,且两个雌配子体均由大孢子母细胞发育而来,大小、形状相近,呈线形排列。该研究结果对于揭示原始被子植物胚胎发育特征具有重要意义。     

无核葡萄胚挽救影响因素的研究

分别以‘底莱特’和‘大粒红无核’自交、‘红宝石无核’ב新郁’和‘爱莫无核’ב黑奥林’胚珠为材料进行无核葡萄胚挽救影响因素的研究。结果显示:(1)‘底莱特’自交和‘红宝石无核’ב新郁’胚珠剥胚后萌发率分别为11.4%和10.0%,高于横切胚珠情况下的萌发率(5.5%、0.6%);(2)用Nitsch培养基培养的‘大粒红无核’自交和‘爱莫无核’ב黑奥林’胚珠的胚萌发率分别为9.5%和5.6%,胚状体诱导率分别为6.3%和3.9%,明显高于ER培养基的萌发率。结果表明:剥胚有利于无核葡萄胚的萌发;Nitsch比ER培养基更有利于胚萌发和胚状体诱导;同时,由于杂交亲本染色体倍性的差异导致胚萌发率不同,表现为:二倍体无核自交>二倍体无核×二倍体有核>二倍体无核×四倍体有核。     

巴西橡胶树未受精胚珠培养时愈伤组织与胚状体的起源(简报)

THEORIGINOFCALLUSANDEMBRYOIDINCULTUREDUNFERTILIZEDOVULESOFHEVEABRASILIENSISYangXiaoqua(DepartmentofFallScience,SouthChinaUniversityofTechnolop,Guangzhou510641)FuJiarui(DepartmentofBiology,ZhongshanUniversity,Guangzhou510275)迄今为止,利用未受精胚珠高体培养诱导木本植物形成单倍体植株的仅有杨树及巴西橡胶树两例[1-3],但均缺乏详细的胚胎学观察资料,胚状体的起源不甚清楚。在某些草本植物中,起源问题已有详细的研究。例如向日葵未受精胚珠离体培养时,胚状体起源于未受精的卵…     

橡胶树内珠被培养研究进展

橡胶树自根幼态无性系是20世纪70年代末培育的新型种植材料,集中了实生苗和芽接苗的优点,具有生长快、产量高、茎干圆锥度大的特点,极有可能取代芽接苗成为第3代种植材料.内珠被培养是获得自根幼态无性系的重要手段,可经初级体胚发生或持续体胚发生再生植株.初级体胚/微繁植株长势好、产量高,但再生频率低;持续体胚发生再生频率高,但体胚/微繁植株变异、感病、产量低.利用持续体胚发生体系进行了超低温保存和遗传转化研究,均取得了成功.     

珠被及其发育

珠被是胚珠外的保护层,在被子植物中,通常由１～２层组成。如果有２层珠被则依内外不同而称为内珠被和外珠被;当胚珠只有１层珠被时,则称为单珠被。它往往比２层珠被厚而且细胞数目多。无论单珠被还是双珠被,除了珠孔以外,它们完全将珠心包围起来。受精后,在胚珠发...     

南瓜未受精胚珠的离体培养及植株再生

以南瓜(Cucurbita moschata)品种试验1号为材料, 以未受精胚珠为外植体, 研究了激素种类、外植体发育时期、高温预处理时间和AgNO₃浓度对胚状体诱导的影响。结果表明, 2,4-D、NAA和6-BA组合有利于胚状体的形成, 出胚效果最好的培养基为MS+1.0 mg·L^–12,4-D+0.25 mg·L^–1NAA+0.5 mg·L^–16-BA, 出胚率达31.1%; 雌花开放当天的胚珠出胚率最高(26.7%), 且愈伤组织形成频率低(<5%); 外植体在黑暗、高温(35°C)条件下处理5天有利于胚状体的形成, 出胚率为32.2%。培养基中添加AgNO₃对胚状体形成的抑制作用明显。胚状体转移至成苗培养基后可形成正常小苗, 出苗率最高可达64.3%, 植株再生过程经历了典型的胚胎发育途径。细胞学观察结果表明, 胚状体极有可能起源于胚囊珠孔端的细胞, 即卵细胞或助细胞。     

影响玉米胚状体建成关键因素研究进展

利用胚状体对玉米进行离体繁殖具有数量多、速度快、成苗率高、染色体稳定等优点。影响胚状体发生和分化频率的因素较多,主要集中在基因型、外植体、激素和培养基成份等几个方面。该文对胚状体诱导、分化的影响因素及其机理的最近研究进展进行综述。     

甘蓝花药培养胚状体诱导形成影响因子研究

用甘蓝F1、F2和自交系S33个世代6种基因型材料进行甘蓝花药培养诱导胚状体形成影响因子研究。结果显示:(1)高浓度蔗糖对甘蓝胚状体形成具有显著的诱导作用,6%蔗糖浓度是甘蓝花药培养的最适浓度,其胚状体的诱导率最高达12.2%;(2)材料基因型是影响花药培养的主要因素,F2和F1代材料胚状体诱导效果好,且胚状体诱导率F2代(F2P192和F2P194)18.9%比F1代(F1S17和F1S13)17.1%较高,但差异不显著,自交系S3代材料很难诱导出胚状体;(3)B5培养基比MS培养基更适合甘蓝花药胚状体的诱导培养。结果表明,甘蓝F2代是其花药诱导培养胚状体的最佳基因型材料,B5 2.0 mg/L 2,4-D 2.0 mg/L KT 6%Suc是甘蓝花药诱导培养胚状体的最适培养基。     

金花茶子叶在离体培养中胚状体的发生和小植株的形成

研究了金花茶(Camellia chrysantha(Hu)Tuyama)子叶在离体培养中体细胞胚状体发生的条件。在MS基本培养基中附加苄基嘌呤(BA)或苄基嘌呤与萘乙酸(NAA)组合,诱导了胚状体发生。组织学观察表明,胚状体起源于子叶的表皮细胞。在增添细胞分裂素和生长素的MS或改良B_5液体培养基里振荡培养,明显地促进了胚状体根的生长和茎的发育。胚状体在继代培养中能保持旺盛的再生能力。已得到两个繁殖率较高的胚状体无性系。在合适的条件下,胚状体能长成正常的小植株。     

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.