四川华蓥山地区长兴期腕足动物

四川华蓥山地区二叠纪长兴期地层中共采获腕足动物９０种４４属,其中１０新种,新亚种,根据这些丰富的化石材料,文章分析了该区长兴期腕足动物群的性质面貌,并与国内同期灰岩相腕足动物群进行了对比。同时对本区长兴期腕足动物的古生态进行了初步探讨,识别出两个腕足动物群落,,即Ａｃｏｓａｒｉｎａ－Ａｒａｘａｔｈｙｒｉｓ群落和Ｐｅｒｉｇｅｙｅｒｅｌｌａ群落。     

贵州安顺募役剖面晚二叠世腕足动物群落及其生态特征*

本文对贵州募役剖面长兴期腕足动物群进行了系统分类鉴定和古生态分析,发现其与前人所报道的华南同时期腕足动物群存在着显著的差别,以Spiriferellina为绝对优势属,包含少量华南长兴期的常见分子,如Fusichonetes、Araxathyris和Peltichia等。募役剖面的腕足类化石主要产自碎屑岩层位,与华南同期碎屑岩相剖面的腕足动物群落相比,该动物群中的优势分子个体较大、壳体较厚且发育较粗大的壳疹,这可能与长兴期募役剖面动物群所处的特殊栖息地环境(浅水碳酸盐岩台地与深水硅质碎屑岩盆地之间的过渡地带)有关。二叠纪末期大规模的火山作用导致水体中碎屑物质含量增加,影响腕足类的滤食效率,而募役剖面清澈、水动力弱的水体环境,为滤食性的腕足动物提供了有利的环境条件。最后,通过与华南长兴期不同沉积相区腕足动物群落(六枝剖面、稻堆山剖面、中寨剖面、新民剖面、马家山剖面和仁村坪剖面群落)的对比分析,发现募役剖面腕足动物群与毗邻的六枝剖面腕足动物群在属级组成上的相似度较高,且过渡岩相栖息地环境下的腕足动物群在生物灭绝事件前也呈现出高优势度、低均匀度的群落结构特征,指示海洋底栖生物群落已经先于二叠纪末期生物集群灭绝事件出现了早期危机信号。     

贵州贵定长兴阶的腕足动物群

对贵州省贵定地区长兴期腕足动物群进行了系统研究，建立了该地区长兴阶的４个腕足动物组合，并对各个组合的古生态特征进行了初步探讨。描述了腕足动物化石８属９种，其中２新属７新种。     

安庆栖霞组的腕足类化石

我国南方二叠纪地层中的腕足动物群,以晚二叠世的腕足动物研究的最为详细,其次是早二叠世晚期的腕足动物,许多古生物工作者发表了论文,给予论述;而对早二叠世早期的腕足动物群研究则较差。1927年赵亚曾首先研究了长江下游栖霞灰岩中的腕足类化石,并报道了“栖霞石灰岩之腕足类化石”8属、10种、3未定种,其中1新种,但时代并未肯定。在我国栖霞组内以珊瑚及(竹蜓)科化石为主,而又比较标准,地层对比较为重要,所以对栖霞组内的腕足类研究就减少了,直至近十多年来才逐渐的对这一地层的腕足类的研究给予重视。笔者将安庆白鹿尖剖面的腕足类化石研究发表,是因为     

内蒙古准格尔旗对臼沟本溪组及腕足动物群落

介绍了内蒙古准格尔旗对臼沟本溪组含腕足动物地层,对该地区本溪组腕足动物群和性质特点进行了分析。并在识别腕足动物群落的基础上,从种的分异度,种的相对丰度,群落空间分布与能量分配等角度探讨了该腕足动物群落的一些结构模式,指出Ｅｃｈｉｎｏｃｏｃｈｕｓ ｅｌｅｇａｎｓ－Ｏｈｏｒｉｓｔｉｔｅｓ ｗｅｉｎｉｎｇｅｎｓｉｓ腕足动物群落已基本属于演替阶段中的顶极群落。     

河北秦皇岛石门寨地区晚石炭世本溪组下部的腕足动物及其古环境

本文描述了采自石门寨地区本溪组下段地层(含(竹蜓)灰岩之下)中的腕足动物化石并讨论了它的古生态环境。这个腕足动物群具有极大的丰度和很低的分异度,共3属5种,95%以上的个体为Derbyia,只有少数Meekella和Orbiculoidea。这种特殊的腕足动物组合反映当时本区处于非正常浅海环境,使得大多数底栖腕足动物无法生存。Derbyia和Meekella因具长的铰合线,外套膜能充分扩张、能吸收较多氧气,故能够生存、繁衍并形成极大丰度。这一腕足动物群未见于上部层位和其他地区,它的消失是古地理环境激剧变化引起的,是群落演替的结果。     

川东南中奥陶统大沙坝组的腕足动物群

四川东南部长宁双河及其附近地区的中奥陶统上部大沙坝组以特殊的岩相和生物相有别于黔北的可比地层十字铺组和鄂西的牯牛潭组,地层中漂浮相化石(笔石)与底栖壳相化石(如腕足动物和三叶虫)多次交互出现,笔石动物属于上层下垂对笔石动物群(Didymograptus artus Fauna),时代为中奥陶世Darriwilian(相当于Arenig最晚期至Llanvirn)。在所采集的3300余枚化石标本中有近90％是腕足动物化石,经研究共鉴定出19属21种,分属于4目7超科15科,正形贝目和扭月贝目分别有8属,占全部属群的84％。根据属的生物地理分布,该动物群中广布型分子7属、区域性分子6属,仅限于华南的土著性分子占总量的31．6％,显示出此期华南腕足动物群具有较强的地方性色彩,进一步证实中奥陶世海洋生物强分区性的推断。该腕足动物群宜称作Saucrorthis-Glyptorthis动物群。在统计分析的基础上,识别出Saucrorthis-Glyptorthis群落,包括三个以腕足动物占优势的化石群集(association),即Glyptorthis?simplex群集、Saucrorthis obscura群集和Calyptolepta chengkouensis群集,并结合沉积岩石学以及其它共生化石门类进行群落生态分析,认为该群落所生活的环境以正常浅海砂泥质底域为主(相当于BA2-3)。与上扬子台地贵州遵义十字铺组和重庆城口厚坪组两个相近腕足动物群相比,长宁地区中奥陶世的Saucrorthis-Glyptorthis动物群更接近于厚坪组所产者。与世界上其它一些同期且具相似生态位的动物群相比,除与哈萨克斯坦南部的同期动物群比较接近外,与澳大利亚、北美、英国等地的同期动物群几乎毫无联系,指示华南中奥陶世腕足动物群可能代表一个独特的生物地理小区。     

陕西汉中梁山乐平统底部王坡页岩中的腕足动物化石北大核心CSCD

报道陕西汉中梁山瓜德鲁普统与乐平统界线附近王坡页岩(斑脱岩)中的腕足动物化石4属6种:Neochonetes(Huangichonetes)substrophomenoides,Orthothetina ruber,O.regularis,O.sp.,?Martinia orbicularis,和Hustedia indica。该腕足动物群以吴家坪期暖水型腕足动物为主,既含有瓜德鲁普世孑遗分子,又具有乐平世吴家坪期新兴分子,显示了过渡类型的特点。陕南吴家坪期初期腕足动物化石群的发现,对识别瓜德鲁普世末期灭绝事件后腕足动物在吴家坪期初期的多样性和乐平世初腕足动物的复苏和辐射提供了重要的化石信息。     

陕西汉中梁山乐平统底部王坡页岩中的腕足动物化石

报道陕西汉中梁山瓜德鲁普统与乐平统界线附近王坡页岩(斑脱岩)中的腕足动物化石4属6种:Neochonetes(Huangichonetes)substrophomenoides,Orthothetina ruber,O.regularis,O.sp.,?Martinia orbicularis,和Hustedia indica。该腕足动物群以吴家坪期暖水型腕足动物为主,既含有瓜德鲁普世孑遗分子,又具有乐平世吴家坪期新兴分子,显示了过渡类型的特点。陕南吴家坪期初期腕足动物化石群的发现,对识别瓜德鲁普世末期灭绝事件后腕足动物在吴家坪期初期的多样性和乐平世初腕足动物的复苏和辐射提供了重要的化石信息。     

河北秦皇岛石门寨地区晚石炭世本溪组下部的腕足动物及其古环境

本文描述了采自石门寨地区本溪组下段地层(含(竹蜓)灰岩之下)中的腕足动物化石并讨论了它的古生态环境。这个腕足动物群具有极大的丰度和很低的分异度,共3属5种,95%以上的个体为Derbyia,只有少数Meekella和Orbiculoidea。这种特殊的腕足动物组合反映当时本区处于非正常浅海环境,使得大多数底栖腕足动物无法生存。Derbyia和Meekella因具长的铰合线,外套膜能充分扩张、能吸收较多氧气,故能够生存、繁衍并形成极大丰度。这一腕足动物群未见于上部层位和其他地区,它的消失是古地理环境激剧变化引起的,是群落演替的结果。     

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.