扬子区后Llandovery世（志留纪）胞石的发现及其意义

坟头组时代争论长期不能统一的原因之一,在于各家对坟头组涵盖范围理解不一,坟头组有广义和狭义之分：以侯家塘组的顶为底,以秀山动物群的最高层位为顶的坟头组概念,为狭义坟头组,以侯家塘组,茅山组之间岩层的总答和为坟头组的概念,为广义坟头组,本文建议使用狭义坟头组概念,以求定义统一。坟头组之上,茅山组之下还存在寨山组和新河庄组（新组）。宁镇山脉志留系存在倒序,脱顶,丢层等问题,建议将坟头组,寨山组的标准剖     

西昆仑地区志留系温泉沟群的疑源类和几丁虫

西昆仑地区处于中亚腹地的高寒缺氧地带,区域地质研究程度较低。下志留统温泉沟群中-下部轻变质的碎屑岩中一直未发现可靠的化石证据。最近,在温泉沟地区志留纪地层中发现较丰富的Leiosphaeridia,Flo-risphaeridium,Conochitina,Ancyrochitina,Desmochitina,Eisenackitina,Rhabdochitina,Cyathochitina,Lag-enochitina和?Eremochitina属等疑源类和几丁虫化石分子,为温泉沟群中-下部轻变质碎屑岩的时代确定提供了重要的微体化石方面依据。     

上扬子区奥陶系Nemagraptus gracilis 笔石带的几丁虫

作者系统描述了在重庆城口廖子口和宜昌分乡普溪河奥陶系庙坡组Nemagraptusgracilis笔石带中发现的几丁虫化石,共7属9种。由于此前对该层位的几丁虫研究较少,因此本次所发现的几丁虫化石具有重要的生物地层意义。     

基于线粒体DNA D-loop区部分序列分析舟山海域带鱼种群遗传结构

{{@ convertAbstractHtml(article.abstractinfoCn, "cn")}}       

POPULATION GENETIC STRUCTURE OF FINLESS PORPOISES, NEOPHOCAENA PHOCAENOIDES, IN CHINESE WATERS, INFERRED FROM MITOCHONDRIAL CONTROL REGION SEQUENCES

Seven hundred and twenty base pairs (bp) of the mitochondrial control region from 73 finless porpoises, Neophocaena phocaenoides , in Chinese waters were sequenced. Thirteen variable sites were determined and 17 haplotypes were defined. Of these, 5 and 7 were found only in the Yellow Sea population and the South China Sea population, respectively, whereas no specific haplo-type was found in the Yangtze River population. Phylogenetic analyses using NJ and ML algorithm did not divide the haplotypes into monophyletic clades representing recognized geographic populations of finless porpoises in Chinese waters, suggesting the existence of migration and gene flow among populations. Analysis of molecular variance showed the obvious population genetic structure (φ_st= 0.41, P < 0.05); however, the structure was mainly between either the Yangtze River population or the Yellow Sea population and the South China Sea population. The genetic diversity (nucleotide diversity and haplotypic diversity) of the Yellow Sea population was significantly higher than those of the Yangtze River population and the South China Sea population, suggesting the relatively later divergence of the latter two populations and supporting the Yellow Sea population as the original center of Neophocaena .     

核苷酸序列比对在生物系统发育研究中的应用

作为确定分子数据初级同源性(primary homology)的过程,比对的重要性在于后续算法的选择.本文对其在生物系统发育研究中的作用及其基本步骤与算法做了简要说明;从理论与实践相结合的角度介绍了使用最为广泛的软件,讨论了其中的空位(gap)问题、参数问题和比对结果校正等问题;并且对此领域中前沿的基因组比对研究进展做了概述.     

基于线粒体控制区的云南澜沧江和海南岛主要水系宽额鳢遗传变异分析

为了解中国宽额鳢的遗传背景以更好地保护和开发利用资源,测定了云南澜沧江和海南岛南渡江、万泉河与昌化江等4个水系9个群体74尾宽额鳢线粒体控制区411 bp序列,发现52个变异位点和20个单倍型;在系统树上可分为云南、海南毛阳群体和海南其他群体等3个分支。谱系间Fst为0.786-0.672(P0.01),基因流Nm为0.153-0.244; 74.352%的变异来自谱系间,谱系间分化时间为2.070-0.350 Ma。推测海南与云南宽额鳢分化可能受云贵高原隆起和海南岛与陆地分离等地质事件影响;海南2个谱系的形成则可能是受到了五指山山脉隆起的影响。云南组群与海南组群间Fst为0.765(P0.01),基因流Nm为0.149, 70.360%的变异来自不同地理组群间,表明云南组群和海南组群间高度分化。相比同区域分布的鱼类,宽额鳢总体的单倍型多样性和核苷酸多样性均较高(Hd=0.9030.016, =0.0360.003),其中海南琼中和石壁群体的核苷酸多样性()最高均为0.008;云南勐腊群体最低为0.000;但各个地理群体均比总体的遗传多样性低,可能是后者由多个谱系叠加所致。在简约性网络图中单倍型呈非典型星状分布,中性检验为非显著负值和核苷酸不配对分析呈现多峰分布,表明宽额鳢群体历史上较为稳定,没有出现显著种群扩张。       

重庆城口大塘口下奥陶统红花园组和湄潭组下部的几丁虫

文中图示和描述了重庆城口大塘口奥陶系红花园组和湄潭组下部营盘段的几丁虫计 6属, 17种。其中包括 7个未定种和 3个新种 (Conochitinadatangkouensissp. nov., C. wengxigouensissp. nov., Rhabdochitinachenk ouensesp. nov. )。讨论了几丁虫的地理和地层分布特点及其与笔石生物带的关系,阐明了红花园组和湄潭组下部营盘段不同笔石带(A. filiformis, D. bifidus和A. suecicus笔石带)中几丁虫的组合特征,并与国外同期地层几丁虫组合进行了对比。     

THE GENESIS OF CONDENSED SEQUENCES IN THE TETHYAN JURASSIC

Pelagic limestones of the west Sicilian Middle Jurassic are used as type examples in this examination of Tethyan condensed sequences. Two main processes were involved in the genesis of this type of deposit: stratigraphic condensation (minimal sediment input) and reworking. The lack of nannoplankton during most of the Jurassic caused stratigraphic condensation, and the particular environment in which these beds were deposited – that of topographic high – was considerably influenced by currents; thus reworking led to a further reduction in sediment thickness. The presence of algal stromatolites in certain condensed sequences and the traces of boring algae in associated ferromanganese nodules suggest deposition within the photic zone. A maximum depth of 200 metres is inferred. Many features of condensed sequences are comparable with those on Recent seamounts; these include presence of ferromanganese nodules and crusts, mixed faunas, calcarenite lenses, algal biscuits, and evidence of submarine solution and lithification. Jurassic Tethyan condensed sequences can thus be interpreted as ancient seamount deposits.     

线粒体DNA序列变异显示鸭绿江茴鱼为黑龙江茴鱼同物异名

经测序获得北极茴鱼鸭绿江亚种Thymallus arcticus yaluensis和黑龙江茴鱼T.grubii共26尾的线粒体DNA控制区基因全序列,以下游黑龙江茴鱼T.tugarinae、北极茴鱼指名亚种T.a.arcticus和欧洲茴鱼T.thymallus作外群,构建了茴鱼属部分种分子系统发育树,以探讨北极茴鱼鸭绿江亚种分类地位的有效性。结果显示,鸭绿江茴鱼与黑龙江茴鱼的4个地理种群(呼玛河、甘河、牡丹江、松花江)间的Kimura 2-parameter遗传距离仅为0·007~0·015,处于黑龙江茴鱼不同地理种群间的变异范围之内(0·004~0·015),明显小于属内种间的遗传距离(0·046~0·062)。以邻接法(NJ)和最大简约法(MP)构建的茴鱼属部分种系统发育树表明,鸭绿江茴鱼未构成独立的单系群,也未与北极茴鱼T.a.arcticus形成亚种关系,而是聚到黑龙江茴鱼种群内部,共同构为一个单系群。研究表明,鸭绿江茴鱼T.a.yaluensis并非有效种,应为黑龙江茴鱼T.grubii的同物异名,可视为黑龙江茴鱼的一个地理生态种群。     

核基因序列在昆虫分子系统学上的应用

核基因中含有更加丰富的生物学信息,运用核基因序列或将核基因序列与线粒体基因序列相结合研究昆虫的系统发育正成为分子系统学领域的一种发展趋势.核糖体基因中18S rDNA、28S rDNA、ITS已在昆虫分子系统学中得到了广泛的应用.与核糖体基因相比,虽然编码蛋白的核基因应用于昆虫分子系统学的种类不少,但大部分都是应用于双翅目和鳞翅目昆虫的分子系统学研究中,能够成功地普遍用于多个目昆虫的系统学研究的核基因并不多.本文简要介绍了应用于昆虫分子系统学的核中核糖体基因和编码蛋白的核基因,并分析了核基因序列在分子系统学应用上的局限性和应用前景.     

CHARACTERIZATION OF POLY(A) SEQUENCES IN BRAIN RNA

—Nuclear and polysomal brain RNA from the rabbit bind to Millipore filters and oligo(dT)-cellulose suggesting the presence of poly(A) sequences. The residual polynucleotide produced after RNase digestion of ³²P pulse-labelled brain RNA is 95% adenylic acid and 200-250 nucleotides in length. After longer isotope pulses the polysomal poly(A) sequence appears heterodisperse in size and shorter than the nuclear poly (A). Poly(A) sequences of brain RNA are located at the 3′-OH termini as determined by the periodate-[³H]NaBH₄ labelling technique. Cordycepin interferes with the processing of brain mRNA as it inhibits in vivo poly(A) synthesis by about 80% and decreases the appearance of rapidly labelled RNA in polysomes by about 45%. A small poly(A) molecule 10-30 nucleotides in length is present in rapidly labelled RNA. It appears to be less sensitive to cordycepin than the larger poly(A) and is not found in polysomal RNA.     

核酸序列重复片段的统计分析

对核酸序列编码区的重复片段进行了统计分析。发现不同物种的序列具有近似相等的约化重复长度和次数,研究了重复区内碱基分布的特点,并讨论了此结果可能的生物学涵义。     

光裸方格星虫野生与养殖群体线粒体控制区序列的遗传差异分析

基于线粒体控制区序列对光裸方格星虫（Sipunculus nudus Linnaeus,1766）的2个养殖群体（营盘YP、竹林ZL）和4个野生群体（防城港FC、钦州QZ、大冠沙DG和越南海防YN）的91个个体进行遗传差异分析,研究光裸方格星虫养殖和野生群体的遗传变异情况。结果显示:获得的514 bp DNA序列中,野生与养殖群体的多态性位点数分别为82和60,均显示出对AT的偏倚性。共定义85个单倍型,共享单倍型4个,其中共享单倍型Hap5为原始单倍型,营盘群体均为独享单倍型。各群体的单倍型多样性（H_d）相同,野生群体的平均核苷酸多样性（P_i）（0.01531）略高于养殖群体（0.01514）,6个群体的遗传多样性水平依次为YN > YP > QZ > FC > ZL > DG。各群体间的遗传分化并不显著（P>0.05）,光裸方格星虫的遗传变异主要来自群体内个体间（99.08%）,同时未发现明显的地理谱系结构。研究表明,光裸方格星虫野生群体的遗传多样性水平总体略高于养殖群体;滩涂底播养殖方式较池塘养殖更利于维持光裸方格星虫遗传多样性;各群体间不存在显著的遗传分化,养殖群体正逐渐积累遗传变异,但尚未足够以形成其独立的遗传结构。     

EARLY LLANDOVERY CHITINOZOANS FROM JORDAN

Abstract:  Chitinozoans recovered from cores BG-14 and WS-6 in southern and eastern Jordan are described. Sample ages are well-constrained by graptolite data to the ascensus-acuminatus and vesiculosus graptolite biozones. Eighteen chitinozoan taxa are recognized, with Spinachitina  fragilis , Plectochitina  nodifera , Ancyrochitina  laevaensis and Belonechitina  postrobusta allowing correlation with both local and global chitinozoan and graptolite biozonations for the Rhuddanian. One new species of chitinozoan is erected, Belonechitina  pseudarabiensis sp. nov.