西藏林芝盆地新生代晚期的自然环境

<正> 一地质概况林芝盆地,位于青藏高原的东南部,东经94°20′;北纬29°30′,海拔高程为2950—3080米。林芝盆地为一狭长条状的山间盆地,东西长约15公里,南北宽约2公里,尼洋河自西北向东南纵贯盆地。另一条林芝河由东而西流入盆地。两条河流流经盆地破坏了原来的湖相沉积物,都汇集到雅鲁藏布江中(图1)。1975年中国科学院青藏高原综合科学考察队,在林芝盆地东南县城建筑公司砖瓦厂,发现了古湖相沉积物和尼洋河阶地堆积物。残存的古湖相沉积物面积不大,但含有哺乳类动物化石和植物化石。在林芝尼洋河右岸一     

江苏发现始新世化石

1986年,江苏溧阳上黄乡采石场,工人们在石灰岩之间的裂隙堆积物中发现了一些动物的骨头和牙齿化石,他们向有关文化部门报告了这件事并引起有关专家的重视。这些裂隙堆积物是一些砂砾岩及粘土,动物化石     

消息报导与学术动态

河狸化石在江南的踪迹古脊椎动物与古人类研究所在今年4月份,派人前往苏南的太湖中的西山小岛,调查古脊椎动物和古人类的文化遗物。这个地点是上海市文管会在太湖地区购买石料时发现的。它是属于石灰岩山头上的裂隙堆积。在这次现场采集到的少量的动物化石之中,有一种河狸化石,仅有一两个不完整的牙齿代表。河狸科(castoridae)的化石通常是作为北方动物羣的种类,代表比较寒冷的气候。在我国更新世时     

黄海岸边发现大象化石

近日 ,在山东省日照市黄海岸边沙滩上发现了一块古动物化石。经中科院古脊椎动物与古人类研究所专家鉴定为古脊椎动物大象的下牙化石。属真象类 ,是古菱齿象。化石呈灰褐色 ,重５公斤 ,石化保存程度好 ,牙齿上还有水中浮游动物遗体化石。在黄海岸边发现古大象化石还是第一次 ,它的发现为人们对古脊椎动物的认识提供了珍贵的实物资料 ,同时对研究我国更新世中、晚期古脊椎动物群分布有着重要的意义这是一枚不完整的象牙 ,嚼面下陷 ,表明它是一枚下牙 ,它齿冠高 ,齿脊频率可能齿４,白垩质丰富 ,是属真象类中的古菱齿象 ,也可能是南方象 ,这两…     

太原市附近的剑齿象和梅氏犀

太原市黄案挖砂工程中,发现了一些脊椎动物化石,古脊椎动物与古人类研究所太原工作站获悉之后,派张引成同志前往察看,并承挖砂工程处袁福典同志将发现的化石交太原工作站保存研究。发现的化石计有两种:一为梅氏犀,一为师氏剑齿象,兹概略记述如下:梅氏犀     

辽宁本溪发现更新世晚期哺乳动物化石

<正> 一九七九年,辽宁本溪市博物馆刘兴林等人在溪湖区三道岗洞穴堆积物中发现了一批哺乳动物化石.最近,笔者同高尚华、许振宏等同志对这个化石地点(E123°45′21″、N41°20′24″)进行了试掘.该地点的堆积物赋存于中奥陶统马家沟组石灰岩洞中.洞内堆积面积约15平方米,我们仅在距洞口约4米处挖了一个1米宽、2米长深达洞底仅1米的探沟.堆积物为褐黄     

安徽繁昌发现早更新世早期哺乳动物群

１９９８年５月,国家“九五”攀登专项“早期人类起源及环境背景研究”安徽课题组金昌柱、郑龙亭在安徽繁昌地区进行地质古生物调查时,发现一处名叫人字洞的裂隙型洞穴,采得了可能属于早更新世的大批哺乳动物化石和几件有人工打击痕迹的石制品,引起了学术界的关注。人字洞遗址位于长江南岸繁昌县孙村镇水泥厂癞痢山采石场（东经１１８°５’７７”,北纬３１°５’３８”）。洞穴堆积物发育于三叠系薄层状灰岩中,最大宽约８ｍ,可见厚度３０ｍ余,由褐色含少量角砾的亚粘土、棕红色合大块角砾的亚粘土以及灰色、棕色混杂的泥质砂岩组成…     

广东东江流域首次发现溶洞化石动物群

今年７月河源市地质矿产局在该市上莞镇进行石灰石矿简测规划时发现距该镇不远的碧寿溶洞中有丰富的古哺乳动物化石 ,经谷祖纲等有关专家鉴定属大熊猫———剑齿象动物群 ,时代为距今２０万年前的中晚更新世 ,与华北的周口店和广东曲江马坝动物群可以对比 ,在动物化石层中还发现一些疑为人齿与人肢骨的化石（未经权威鉴定） ,该类化石动物群在广东的西江、北江流域有多处发现 ,但在东江流域发现尚属首次 ,而且化石之多品种之繁亦属罕见。上莞碧寿洞位于东经１１４°５９′３２″,北纬２４°０４′１０″。溶洞长大于３００米（未见底） ,海…     

恐龙为什么能在古纬度75°的地方生活?

1972年Rouse等在加拿大北纬约66°的育空东北部地区的晚白垩世的含煤地层中发现了恐龙化石。按 Van Valen和 Sloan(1977)的估计,育空的恐龙化石地点晚白垩世的古纬度约为75°。在全世界的恐龙产地中,它是迄今所知古纬度最北的。现代北纬75°地方已在阿拉斯加及巴芬岛的北方,也在除太梅尔半岛外的西伯利亚的北方。在那些地方,按么枕生(1959)的计算,一年中会有97天极夜。     

河南确山早上新世裂隙堆积中发现大量蛇类化石

<正>确山后胥山隶属驻马店市,位于河南南部,淮河以北。此地喀斯特残丘极为发育,残丘顶面的裂隙中有大量新生代晚期的脊椎动物化石堆积。20世纪40年代始,这里曾发现大量的“龙骨”（哺乳动物化石）。20世纪90年代开始,中国科学院古脊椎所金昌柱研究员和河南省文物考古研究所李占杨研究馆员等人在确山后胥山开展地质古生物调查和发掘,1992年,《中国岩溶》初步报道了该地区一些脊椎动物化石名录。     

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.