藏南古近系柳区砾岩孢粉化石的发现及初步研究

作者首次对柳区砾岩夹层中的泥岩和泥质粉砂岩进行了孢粉学研究,共鉴定出52个形态属.其孢粉组合特征是:以被子植物花粉占优势(62.77%-83.19%),其次是裸子植物花粉(11.95%-32.31%),蕨类植物孢子最少(4.80%-10.38%).被子植物花粉以具孔类为主,三孔沟或三沟类花粉在组合中有一定含量.裸子植物花粉以具双气囊类居多.孢粉植物群的总体特征表明其时代可能为古近纪晚期.当时的古植被为落叶阔叶林或针阔混交林,气候较温暖湿润,主要为暖温带的环境.     

Stellatopollis花粉之发现及其意义

本文描述了首次发现于我国早白圣世的原始被子植物花粉Ｓｔｅｌｌａｔｏｐｏｌｌｉｓ。这一发现进一步表明，这类花粉在早白垩世期间分布广泛，是早期被子植物花粉组合的重要组成部分，对大范围内的地层对比和早期被子植物演化的研究具有重要的价值。本文还介绍了我们所使用的对同一粒花粉进行光镜和扫描电镜联合观察照相的一种既简单又经济的方法．     

朝鲜安州盆地早白垩世孢粉组合

报道朝鲜安州盆地下白垩统龙盘组孢子花粉３４ 属５９ 种（包括２ 新种）,并根据孢粉组合讨论了地质时代和古气候特征。龙盘组孢粉组合以裸子植物花粉为主,蕨类植物孢子次之,出现少许原始被子植物花粉。松柏纲花粉在组合中占绝对优势;海金沙科和莎草蕨科孢子则在蕨类中占优势。根据孢粉组合,龙盘组的时代应属早白垩世巴列姆期至阿普第期;安州盆地当时气候温暖偏干,属亚热带半干旱型     

海南白沙盆地早白垩世孢粉化石的发现及其意义

本文是报道在海南白沙盆地中生代“红层”中首次发现的孢粉化石,介绍了这一孢粉组合的基本特征,共50属75种,其中包括早期被子植物花粉2属3种,将其地质时代确定为早白垩世的阿普第期。根据孢粉组合推论当时的古气候可能属于热带、亚热带,本区当时可能处于干旱气候带与潮湿赤道气候带之间的过渡地带。     

内蒙古钱家店凹陷晚白垩世姚家组的孢粉组合研究

内蒙古钱家店凹陷ML12井等12口井的孢粉材料,是目前所知该凹陷姚家组孢粉类型最丰富、数量最多且保存最完好的,已鉴定出孢粉共计116属,包括蕨类植物孢子51属、裸子植物花粉32属和被子植物花粉33属。根据姚家组中蕨类植物孢子分异度较高及相对含量较低、裸子植物花粉分异度较低及相对含量高、被子植物花粉分异度较低及相对含量波动幅度巨大的孢粉组合特征,将其命名为Exesipollenites-Nevesisporites-Retitricolpites组合。该组合与大庆长垣姚家组孢粉组合具有很好的横向对比性。以塔里木盆地西部东巴组中、下段被子植物花粉的演化阶段为参照标准,钱家店凹陷晚白垩世姚家组的孢粉组合时代应为晚白垩世Coniacian期—Santonian期。本文中的工作填补了钱家店凹陷姚家组孢粉组合研究的空白,并为深入认识我国北方区姚家组沉积时期植物群的特征提供了重要的证据。     

红杉属植物在中国云南中新世首次发现

化石标本采自中国云南省中部楚雄市吕合煤矿的石鼓村层 ,该层为灰色至浅灰色细砂岩至粗砂岩、粉砂质粘土层和褐煤层 ,地质时代属中新世 ① 。石鼓村层的孢粉组合以被子植物占绝对优势(90 % ) ,其中热带、亚热带植物成分类型较多 ,如金缕梅科、棕榈科等 ,温带植物成分类型较少 ,如榆科、桦木科等 ;裸子植物花粉占整个孢粉组合的 9% ,主要是松科和杉科花粉 ;蕨类植物孢子仅占整个孢粉组合的 1% ,以水龙骨单缝孢为主。本次发现的标本小枝长约 2 .8ｃｍ ,宽约 1.6ｃｍ ,小枝基部稍膨大。叶螺旋状排列 ,基部扭转 ,在同一平面排成 2列 ,以 30～ 70…     

甘肃酒泉下新民堡群孢粉组合及地质时代

下新民堡群主要由黑色纸状页岩夹灰绿色厚层砂岩和灰色薄层泥灰岩组成,底部具砾岩,为湖相沉积,总厚1,135米。我们处理了取自红柳峡、新民堡、旱峡等六个自然剖面和两个钻孔的162块岩样,从其中33块样品中发现大量孢子花粉。本文描述了下新民堡群孢子花粉19属20种(型)包括2新种。下新民堡群孢粉组合以裸子植物花粉占绝对优势(占93.3％);蕨类孢子次之(占5.9％);被子植物花粉含量虽少,但在组合中起重要作用。该组合的主要特征是松柏类花粉占优势、富含海金砂科孢子和出现被子植物花粉。由于欧亚和北美大陆早白垩世植物群通常都具这些特点,作者认为下新民堡群的地质时代应属早白垩世。根据孢粉组合所反映的植物群,酒泉盆地早白垩世的气候与现今华南相似,无疑是温热湿润的,属亚热带型。     

内蒙古二连盆地早白垩世巴彦花群被子植物花粉

内蒙古二连盆地早白垩世巴彦花群含有类型丰富、保存精美的被子植物花粉。本文利用光学显微镜观察和扫描电镜观察相结合的方法,对这些花粉类型进行了较详细的研究。研究结果表明,巴彦花群的被子植物花粉主要由属于金粟兰科的Hammenia和Singhipollis,悬铃木科/金缕梅科的Tricolpites以及亲缘关系不明的Polyporites组成。这一被子植物花粉组合面貌指示的地质时代为中晚阿尔必期(Albian)。据相关现生植物的地理分布及煤夹层的存在,推测在早白垩世晚期二连盆地处于湿润的亚热带气候环境中。     

黑龙江省鸡西城子河组被子植物化石层的孢粉研究

城子河组为黑龙江省鸡西盆地主要含煤岩组,在其顶部已发现迄今已知全球最早期的被子植物大化石,近来在该层又陆续发现多粒被子植物花粉,为研究被子植物的发生及早期演化提供了有力佐证。本文报道了被子植物化石层的被子植物花粉及与其伴生的丰富多样的蕨类植物孢子和裸子植物花粉,共３８属６１种,其中描述了５属５种,包括２新种,推断其时代为Ｂａｒｅｍｉａｎ期,并倾向于Ｂａｒｅｍｉａｎ早期。推测当时该地为以海金沙科等多种蕨类植物及松柏类植物为主,兼具早期被子植物的十分繁茂植物群,气候为湿润的亚热带型。     

新疆塔里木盆地早白垩世孢粉组合

本文记述了新疆塔里木盆地下白垩统卡普沙良群孢子花粉55属108种包括6新种,建立了本区早白垩世孢粉组合序列,并根据孢粉组合讨论了地质时代和古气候特征,亚格列木组孢粉组合以裸子植物松柏类为主,缺乏被子植物花粉,其时代相当于贝利亚斯期至凡兰吟期;舒善河组孢粉组合仍以裸子植物为主,但出现原始被子植物花粉,时代应属豪特里维斯至巴列姆期;巴西盖组孢粉组合的海金沙科孢子和被子植物花粉都有显著增加,时代应属阿普第期至阿尔必期,本区早白垩世古气候应属亚热带干燥或半干燥型,但在巴列姆期至阿尔必期相对潮湿。     

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.