利用EST-SSR分子标记检测鹅掌楸种间渐渗杂交

引进物种常与本土近缘种间发生杂交而导致基因渐渗,进而影响本地种的遗传系统。鹅掌楸(Liriodendron chinense)为我国濒危树种之一,鹅掌楸种间杂交可配性高,近10年来随着北美鹅掌楸(L.tulipifera)的大量引种及杂交鹅掌楸的繁殖推广,鹅掌楸种间发生基因渐渗的可能性大大增加。本文以5个包含鹅掌楸、北美鹅掌楸、杂交鹅掌楸的人工混交林为实验群体,每个群体包含19–130个成年个体及60–117个自然更新小苗或半同胞子代,利用EST-SSR(simple sequence repeat based on expressed sequence tag)分子标记对各子代群体进行亲本分析,探究鹅掌楸种间自然交配方式以检测鹅掌楸种间渐渗杂交;同时,以亲子群体等位基因频率的回归系数作为渐渗系数,定量分析鹅掌楸属种间基因渐渗。结果表明:在研究的5个鹅掌楸混生群体中,均检测到种间渐渗杂交,且渐渗杂交的方向与效应大小在不同群体间有差异。研究还发现,各树种基因渐渗程度与其种群个体数有关,种群个体数越多,其渐渗能力越强。据此,我们还探讨了鹅掌楸种质资源保护策略。     

鹅掌楸属(木兰科)次生木质部导管穿孔板的比较研究

利用扫描电子显微镜对鹅掌楸属仅存的2个自然种鹅掌楸和北美鹅掌楸的次生木质部导管穿孔板特征进行了详细的研究。结果显示,鹅掌楸属的2个种均以梯状穿孔板为主,同时存在网状-梯状混合穿孔板。鹅掌楸和北美鹅掌楸的导管穿孔板具有明显差异:(1)鹅掌楸具网状穿孔板,而北美鹅掌楸没有观察到;(2)北美鹅掌楸具单穿孔板,而鹅掌楸在该实验中未发现;(3)北美鹅掌楸具有横隔较粗的梯状穿孔板且横隔数目较多;(4)鹅掌楸的导管穿孔板多数横隔较少;(5)北美鹅掌楸的穿孔板倾斜角度较大;(6)北美鹅掌楸具麻黄式穿孔板的存在,且有纹孔膜残留存在。研究认为,北美鹅掌楸导管分子穿孔板分化较鹅掌楸更为剧烈。     

利用RAPD标记分析北美鹅掌楸与鹅掌楸种间遗传多样性

利用ＲＡＰＤ标记技术对鹅掌楸属（Ｌｉｒｉｏｄｅｎｄｒｏｎ Ｌ．）２个现存种鹅掌楸（Ｌｉｒｉｏｄｅｎｄｒｏｎ ｃｈｉｎｅｎｓｅ （Ｈｅｍｓｌ．）Ｓａｒｇ）和北美鹅掌楸（Ｌｉｒｉｏｄｅｎｄｒｏｎ ｔｕｌｉｐｉｆｅｒａ ｌｉｎｎ．）的遗传多样性进行分析,结果表明：２个种都有较高的遗传多样性,但北美鹅掌楸的遗传多样性水平高于鹅掌楸;鹅掌楸的遗传变异主要来自地理种源内,而北美鹅掌楸的遗传变异主要来自地理种源     

鹅掌楸配子选择与雄性繁殖适合度

在多父本等量花粉混合授粉的交配实验设计基础上, 利用SSR分子标记对其子代进行父本分析, 研究鹅掌楸的配子选择与雄性繁殖适合度。参试亲本为鹅掌楸2个种的5个单株(鹅掌楸(Liriodendron chinense)2株, 即FY和LS; 北美鹅掌楸(L. tulipifera)3株, 即LYS、MSL和NK)。结果表明: 鹅掌楸的配子选择个体间差异较大。作为母本, NK和LYS倾向于选择异种雄配子, 而MSL和LS则倾向于选择同种雄配子; 在同种雄配子的选择中, NK、LYS和LS倾向于自交, 而MSL则倾向于异交。以北美鹅掌楸为母本时, 北美鹅掌楸与鹅掌楸的雄性繁殖贡献率分别为45.5%和54.5%, 北美鹅掌楸的雄性繁殖适合度为鹅掌楸的0.556倍。以鹅掌楸为母本时, 二者的繁殖贡献率分别为15.6%和84.4%, 北美鹅掌楸的雄性繁殖适合度为鹅掌楸的0.123倍。总体上看, 鹅掌楸的雄性繁殖适合度高于北美鹅掌楸, 鹅掌楸与北美鹅掌楸均表现为自交亲和。     

鹅掌楸配子选择与雄性繁殖适合度

在多父本等量花粉混合授粉的交配实验设计基础上, 利用SSR分子标记对其子代进行父本分析, 研究鹅掌楸的配子选择与雄性繁殖适合度。参试亲本为鹅掌楸2个种的5个单株（鹅掌楸（Liriodendron chinense）2株, 即FY和LS; 北美鹅掌楸（L. tulipifera）3株, 即LYS、MSL和NK）。结果表明： 鹅掌楸的配子选择个体间差异较大。作为母本, NK和LYS倾向于选择异种雄配子, 而MSL和LS则倾向于选择同种雄配子; 在同种雄配子的选择中, NK、LYS和LS倾向于自交, 而MSL则倾向于异交。以北美鹅掌楸为母本时, 北美鹅掌楸与鹅掌楸的雄性繁殖贡献率分别为45.5%和54.5%, 北美鹅掌楸的雄性繁殖适合度为鹅掌楸的0.556倍。以鹅掌楸为母本时, 二者的繁殖贡献率分别为15.6%和84.4%, 北美鹅掌楸的雄性繁殖适合度为鹅掌楸的0.123倍。总体上看, 鹅掌楸的雄性繁殖适合度高于北美鹅掌楸, 鹅掌楸与北美鹅掌楸均表现为自交亲和。     

鹅掌楸属遗传多样性分析评价

以鹅掌楸的冬芽为材料,提取DNA做模板,用14个引物对131个鹅掌楸样本进行RAPD分析,扩增出235个谱带,显示该属植物具有丰富的遗传多样性。结果表明：①中国鹅掌楸群体多态位点百分率为88．98％,北美鹅掌楸91．06％,杂种鹅掌楸89．98％。②中国鹅掌楸遗传变异分量在群体间占33．03％,群体内占66．97％;北美鹅掌楸分别为8.73％和91.27％;主要变异均存在于个体间。③聚类表征图表明杂种鹅掌楸与北美鹅掌楸的遗传距离较近。     

鹅掌楸在中国的自然分布及其特点

鹅掌楸（Ｌｉｒｉｏｄｅｎｄｒｏｎｃｈｉｎｅｎｓｅ（Ｈｅｍｓｌ．）Ｓａｒｇ．）星散分布于长江流域以南海拔４５０～１８００ｍ阔叶林中。依其自然地理区域,鹅掌楸在我国西部,从北由大巴山,经武陵山、大娄山,伸向云贵高原东部,形成一条东北．西南走向分布带,在东部和中南部,有５个各自以中、低山为中心,被平原相间隔的“岛”状分布。较大种群多分布在我国西部。与北美鹅掌楸（Ｌ．ｔｕｌｉｐｉｆｅｒａＬ．）在北美洲的分布相比,鹅掌楸为星散间断分布,天然更新不良,在自然群落中多为偶见种。中国东部和西部鹅掌楸在形态上存在较明显的差别,西部种群在花被片颜色,叶片裂片变化及同工酶等方面表现出与北美鹅掌楸有更多的相似特性。因而推论,现存鹅掌楸属的这两个对应种,在地史上是通过欧洲及大西洋陆桥建立联系的     

中国鹅掌楸与北美鹅掌楸种间杂交的胚胎学研究

中国鹅掌楸与北美鹅掌楸种间杂交的胚胎学研究尹增芳,樊汝汶（南京林业大学,南京２１００３７）应用控制授粉、常规行蜡切片技术,研究了中国鹅掌楸（ＬｉｒｉｏｄｅｎｄｒｏｎＣｈｉｎｅｎｓｅ）×北美鹅掌楸（Ｌｉｒｉｏｄｅｎｄｒｏｎｔｕｌｉｐｉｆｅｒａ）种间杂交...     

鹅掌楸属种间杂种与亲本花粉壁的超微结构的比较观察

以杂种鹅掌楸及其亲本中国鹅掌楸(Liriodendron chinense)和北美鹅掌楸(L. tulipifera)为材料,研究花粉形状及花粉壁的超微结构。结果表明,杂种与亲本间花粉壁超微结构具有明显的差异,它们可作为种间及杂种与亲本的识别与区分的依据。从杂种鹅掌楸与双亲的花粉壁的纹饰的遗传关系来看,前者花粉壁表面皱疣状隆起的纹饰表明,北美鹅掌楸花粉壁纹饰特征在杂种鹅掌楸中得到充分表现。     

利用SSR 分子标记对鹅掌楸自由授粉子代的父本分析

利用自行开发的12个EST-SSR分子标记, 采用最大似然法对鹅掌楸(L.chinense (Hemsl.) Sarg.)实验群体3个半同胞家系的180个子代进行父本分析。结果表明, 每个SSR位点的等位基因数为3-7, 平均为4.67; 其平均观测杂合度(Ho)、平均期望杂合度(He)及平均多态信息含量(PIC)分别为0.458、0.635和0.580。利用12个SSR标记可在95%的可信度确定114个子代的父本, 占子代群体的63.3%, 其累积排除概率为98.52%。自由授粉状态下, 鹅掌楸的自交率为1.6%, 而北美鹅掌楸自交率为0, 且种内交配比例大于种间交配。鹅掌楸平均有效花粉散布距离为20-30 m, 最大散布距离为70 m。     

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.