甜抓属一新物种（双二倍体）合成及定性

采用胚胎拯求方法,首次成功实现了栽培黄瓜（Cucumis sativus L.,2n=14）与同属野生种C.hystrix Chakr.(2n=24）间可重复的种间杂交。杂交F1植株形态一致。其中多分枝、密棕茸毛（尤其是在花瓣和雌蕊上）、桔黄色花冠及卵圆形果实这些特征与亲本Chystrix相似,而第一雌花节位则与亲本黄瓜（C.sativus）相似。其它性状如株径、节长、叶和花的形状和大小等都介于双亲之间而呈中间型,将杂种F1植株自交并与两亲本进行回交,结果表明F1杂种的雄蕊和雌蕊都是不育的。这可能是由于杂种染色体数目为奇数（2n＝19,其中7条来自黄瓜,12条来自野生黄瓜）,缺乏同源性而导致减数分裂不正常。利用体细胞无性系突变方法,对杂种的染色体数进行了加倍,流动细胞计量仪测定表明,加倍的F1植株（双二倍体）占再生植株的7.3%,形态一致,其DNA含量为2.35pg,而F1（二倍体）的含量为1.17pg。新合成的双二倍体植株能释放花粉,并且能形成含种子的果实。对生长和发育、营养价值及抗性等方面初步研究表明,这一新物种可望成为一新型作物种,在未来农业中占有一席之地。通过不同杂交可形成两种类型的果实：一种为腌渍类型,该株系每株可着生30多个大约10cm长的果实,可一次性采由;另一种为耐弱光类型,果形细长,基本上元种子,适合于部分遮荫的环境,如温室栽培。营养分析表明,新物种果实的蛋白质含量为0.78%,矿物质0.35,均分别高于普通黄瓜含量0.62%和0.27%。对根结线虫筛选试验结果表明,C.hystrix具有高度抗性,其抗性通过正反交可部分转移到F1代和双二倍体中。     

野黄瓜(Cucumis hystrix Chakr.)与3种不同基因型栽培黄瓜(C.sativus L)

野黄瓜(Cucum is hystrix,2n=24)为短日照植物,因其与栽培黄瓜(C.sativus,2n=14)花期不遇等杂交障碍的存在而使种间杂交难以顺利进行。对野黄瓜短光照处理40 d以上,使得两者花期相遇,成功地进行了野黄瓜与3种不同基因型栽培黄瓜(“二早子”、“长春密刺”和“NC4406”)的正反杂交,从中获得了3种杂交组合的幼胚。采用改良的方法对这3种基因型杂种胚进行胚胎拯救,再生频率达80%以上,其杂种的真实性通过植物学性状观察、体细胞染色体计数和天冬氨酸转氨酶(AAT)同工酶分析得到了证实。研究中还发现不同基因型杂种F1的育性存在明显差异,其中以C.hystrixדNC4406”育性最高,花粉可染率达23.3%,是在二倍体水平上进行育种利用的良好材料。     

大白菜与紫甘蓝种间杂种的获得与鉴定

以不同类型的大白菜与紫甘蓝为材料,运用蕾期授粉结合胚挽救技术获得大白菜与紫甘蓝的种间杂种,并对其进行细胞学鉴定.结果表明,大白菜与紫甘蓝杂交,获得了57株F1代幼苗;对根尖染色体数量进行观察和杂种花粉特性调查发现,其中47株具有预期的染色体数目,2n =19,鉴定为真杂种,其花粉败育;另有6株具有38条染色体,鉴定为种间异源双二倍体,应该是发生了染色体自然加倍,其花粉可育.可育的杂种F1代与大白菜回交,获得了大白菜-紫甘蓝BC1代材料.田间观测结果显示,杂种F1代植株综合性状均介于双亲之间,BC1代植株包球明显,综合性状偏向母本大白菜.     

萝卜甘蓝的研究进展与前景

由于品种间杂交育种的局限性,远缘杂交早已被证明是一种大有前途的育种途径。远缘杂交在十字花科作物改良中的应用也已有多年的历史。最典型的例子是萝卜（Raphanus sativus,2n=18）与甘蓝（Brassica oderacea, 2n=18）的杂种后代— 萝卜甘蓝(Raphanobrassica,2n=36）的获得。所谓萝卜甘蓝,是指萝卜与甘蓝杂交的双二倍体后代,现一般用来泛指萝卜属与芸苔属的稳定的属间杂种后代。其获得途径有二：一是在二倍体亲本的水平上杂交,杂种F,经过染色体加倍成为双二倍体;一是在同源四倍体亲本的水平上杂交,直接获得双二倍体杂种。萝卜甘蓝的研究已进行了室少60年,仍未能在农业生产上广泛利用,其原因主要是远缘杂种的育性障碍以及这种杂种在生产上是否有应用价值。     

Cucumis sativus × C.hystrix种间杂种的形态学和细胞学观察

以甜瓜属种间杂种F1(2n=19,华南型黄瓜"二早子"×Cucumis hystrix)为试材,对其形态学、细胞学和育性作了观察分析.结果表明该杂种无雌花,雄花不能正常开放,表现高度不育.该杂种F1长势瘦弱,与笔者以前报道的种间杂种F1(C. hystrix与华北型黄瓜"北京截头"正反交)相比,在育性和形态学性状上有明显差异.花粉母细胞减数分裂观察发现,杂种F1的终变期和中期Ⅰ主要以17条单价体(Ⅰ)和1个二价体(II)存在;整个花粉母细胞的减数分裂行为异常,经常可见染色体滞后和纺锤丝定向紊乱,形成多极染色体,末期II后形成多分体,以致不能发育成正常的花粉粒,导致杂种F1高度不育.     

野黄瓜与栽培黄瓜正反交异源四倍体序列消除的初步研究

不同分类群的异源多倍体在二倍化过程中, 正反交序列消除往往表现出不同特征, 暗示了在不同物种中, 核质互作在多倍体进化过程的作用不同。利用13对EcoRI-NN/MseI-NNN选择性引物, 对野黄瓜Cucumis hystrix (2n=24)与栽培黄瓜C. sativus (2n=14)的正反交F1、异源四倍体及二倍体亲本DNA进行AFLP分析。结果表明: 杂交后代基因组的杂合性诱发了F1与异源四倍体广泛的序列消除; 细胞质可能会影响部分亲本序列消除的频率, 但是正反交在序列消除频率上差异不显著, 并且在序列消除时间(均始于F1代)及消除类型上也表现出一致性, 表明核质互作并不是影响序列消除的主要因素; 实验还发现, 正反交不能影响序列的倾向性丢失, 染色体数少的黄瓜条带易发生丢失。     

多花黑麦草与普通小麦的杂交

多花黑麦草二倍体种,具有14条染色体。用普通小麦与多花黑麦草杂交,获得了杂种,杂交结实率为0.058%。杂种F1表现为畸形,其体细胞染色体数为28,F1植株产生的花粉败育,雌蕊不孕,用普通小麦和多花黑麦草回交均未获得回交种子,有待于用秋水仙素加倍染色体以获得异源四倍体。     

薯蓣属植物人工杂交后代的检测

以湖北武当山的盾叶薯蓣(Dioscorea zingiberensis C.H.Wright)为主要亲本,与重庆金佛山的盾叶薯蓣、小花盾叶薯蓣(D.parviflora C.T.Ting)及黄独(D.bulbifera L.)进行种内和种间杂交,并获得部分杂交组合的F1代植株。将F0代种子与F1代植株进行结实率及种子萌发率比较,并与亲本进行过氧化物酶(POD)、超氧化物歧化酶(SOD)和酯酶(EST)同工酶比较。结果表明,不同亲本及其杂交后代的结实率、种子萌发率和实生苗存活率均存在明显差异;亲本和F1代的同工酶酶谱较丰富,部分杂种与亲本的相似度较高,并出现各自的特征酶带。运用同工酶技术可以鉴别杂种的真伪。     

野黄瓜(Cucumis hystrix Chakr.)与3种不同基因型栽培黄瓜(C.sativus L.)种间杂交及杂种鉴定

野黄瓜（Cucumis hystrix ,2n=24）为短日照植物,因其与栽培黄瓜（Csativus,2n=14）花期不遇等杂交障碍的存在而使种间杂交难以顺利进行。对野黄瓜短光照处理40d以上,使得两者花期相遇,成功地进行了野黄瓜与3种不同基因型栽培黄瓜（“二早子”、“长春密刺”和“NC4406”）的正反杂交,从中获得了3种杂交组合的幼胚。采用改良的方法对这3种基因型杂种胚进行胚胎拯救,再生频率达80％以上,其杂种的真实性通过植物学性状观察、体细胞染色体计数和天冬氨酸转氨酶（AAT）同工酶分析得到了证实。研究中还发现不同基因型杂种F1的育性存在明显差异,其中以C.hystrix x“NC4406”育性最高,花粉可染率达23．3％,是在二倍体水平上进行育种利用的良辑材料．     

节节麦×大麦杂种胚再生植株的细胞遗传学研究

以节节麦(2n=14)为母本和大麦(2n=14)进行杂交,两组合平均结实率为31 .11%。对31个幼胚进行愈伤组织诱导培养,其中2个形成全能性愈伤组织进而分化出再生杂种植株。细胞学观察表明,杂种胚再生植株均是染色体加倍的节节麦-大麦双二倍体(2n=28)或染色体再加倍的多倍体。节节麦-大麦双二倍体在减数分裂中期Ⅰ染色体配对平均构型为14.79Ⅰ+1.95Ⅱ+ 4.53Ⅱ′+0.01Ⅲ,表现为自交不育。杂种胚再生植株染色体数目再加倍的多倍体有少数产生了自交种子。 Abstract:Hybridizations between Aegilops tauschii(2n=14)and Hordeum vulgare(2n=14)were made using Ae.tauschii as female.The mean frequency of seed set was 31.11% in two cross combinations,13 hybrid embryos were cultured for inducing callus,of which 2 produced totipotent callus,and plants were regenerated from them.These plants were Ae.tauschii-H.vulgare amphidiploids with doubling chromosome number(2n=28)and octoploids with repeatedly doubling chromosome number(2n=50~56).The Ae.tauschii-H.vulgare amphidiploids were sterile and their average chromosome pairing at MI were 14.79I+1.95II+4.53II′+0.01III.Some octoploid(2n=56)plants produced seeds after selfing.     

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.