中华鲟(Acipenser sinensis)及相关种类的mtDNA控制区串联重复序列及其进化意义

采用PCR技术和DNA测序技术,发现了我国一级珍稀保护动物中华鲟(Acipenser sinensis)线粒体DNA(mtDNA)的控制区(D-loop)存在数目不等的串联重复序列,该重复序列造成了中华鲟广泛的异质性现象。从分子水平进行了不同类型重复序列变化规律的研究,同时还初探了重复序列在我国其它几种鲟鱼类的存在情况,发现在白鲟(Psephurus gladius)、达氏鲟(A. dabryanus)和史氏鲟(A. schrenckii)均存在类似的重复序列结构。

云南西双版纳片断热带雨林鼠形啮齿类的物种多样性研究

该文以３个不同面积和环境状况的片断热带雨林即西双版纳傣族“龙山林”和１个自然保护区对照样地为工作样区, 对热带雨林片断化后, 鼠形啮齿类物种多样性的变化及其与环境的关系等进行了研究, 结果如下：(1)４个样地铗捕获得的鼠形啮齿类种数分别为３、３、４和５种; (2)城子龙山和保护区对照样地的多样性指数较高(分别为2.058和1.944), 而曼养广龙山和曼俄龙山的物种多样性指数仅为1.165和1.350; (３)各“龙山”的鼠形啮齿类物种多样性与其面积大小的相关性较弱, 而与样地的隔离状况及人为干扰破坏的程度有较显著的相关性; (4)样地内鼠种组成的变化也和样地隔离状态及人为干扰破坏程度的不同密切相关; (5)各样地鼠形啮群落中生物量的分布也很不均匀。

3H的辐射生物学效应的研究 Ⅲ:3H-Thymidine 诱发水棉(Spirogyra SP.)产 生微核仁的电子显微镜观察

结果显示,水绵细胞分裂间期的核仁为近球形,由核仁颗粒区和立体网状的核仁纤维区组成。水绵在含有10uci/ml的3H-Thymidine培养基培养1400h后,受到细胞内外,细胞核内外3H的 辐射作用,分裂间期核仁增大,核仁中小部分纤能区或颗粒区的物质成团离开核仁,在核中,核仁旁形成"微核仁"。这种微核仁与通常用普通显微镜观察到 的"微核不同"。图3参15

Dynamic behaviour of gas jets in laser cutting

The efficiency and overall quality of a laser cutting operation is highly dependent on the assist gas parameters. The desire to cut thicker material has led to the observation of small process operating windows for thicker sections. The gas jet delivery and subsequent dynamical behaviour have significant effects on the cutting operation as the sample thickness increases. To date, few workers have examined the dynamical behaviour of the gas jet. This paper examines the characteristics of oxygen gas jets during CO2 laser cutting of steel. Particular emphasis is placed on the mass transfer effects that are operating within the kerf. Oxygen concentration levels within a model kerf are measured for various laser cutting set-ups. The results show a substantial reduction in oxygen concentration within the kerf. A system for oxygen concentration maintenance is described and cutting results from this system are compared with conventional techniques for cutting steels in the range 10 to 20mm thick. A theoretical analysis of turbulent mass transfer within a kerf is presented and compared with experiment.

复合垂直流人工湿地基质生化活性研究

文章测定了复合垂直流人工湿地基质生物膜生物量的空间分布、纤维素分解作用强度、氨化作用强度、酚分解作用强度、耗氧速率、厌氧活性等指标,结果表明:下行流池基质的纤维素分解作用、氨化作用、酚分解作用、耗氧速率等均高于上行流池,表层高于中下层,各指标变化趋势与生物膜生物量的空间分布存在明显的一致性;下行流池表层基质是污染物降解的主要空间;但上行流池基质的厌氧活性高于下行池;同时发现钴离子对基质厌氧微生物活性存在一定的影响,随着浓度的升高表现为先激活后降低。这些研究为阐明人工湿地净化机理提供了理论依据。

光滑侧链藻——中国淡水硅藻新记录

2004~2006年,对武汉东湖的底栖藻类进行了生态学调查研究。在对底栖硅藻的定性和定量研究中,发现了一种中心纲种类为中国新记录,它具有一些海洋角盘藻科种类的特征,如眼纹斑(Ocellus)等。经鉴定为光滑侧链藻Pleurosira laevis(Ehrenberg) Compere。参考Compere 1982年的研究,我们同意他的看法,即以前在我国台湾发现的台湾多变筒藻Proteucylindrus taiwanensis Li et Chiang和广东发现的Cerataulus laevis var

中华鲟(Acipenser sinensis)及相关种类的mtDNA控制区串联重复序列及其进化意义

采用 PCR技术和 DNA测序技术 ,发现了我国一级珍稀保护动物中华鲟 ( Acipensersinensis)线粒体 DNA( mt DNA)的控制区 ( D- loop)存在数目不等的串联重复序列 ,该重复序列造成了中华鲟广泛的异质性现象 .从分子水平进行了不同类型重复序列变化规律的研究 ,同时还初探了重复序列在我国其它几种鲟鱼类的存在情况 ,发现在白鲟 ( Psephurus gladius)、达氏鲟 ( A.dabryanus)和史氏鲟 ( A.schrenckii)均存在类似的重复序列结构 .序

长江三峡地区干流河岸植物群落的初步研究

以长江三峡干流河岸植物群落为研究对象，对群落的物种组成、物种多样性进行了分析，并利用TWINSPAN方法对植物群落进行等级式划分。结果表明：河岸植物区系组成较为复杂，以温带成分为主，有着较高比率的世界分布成分。植物生活习性方面，草本种类的比率略高于木本种类，藤本种类较少。灌、草丛群落之间的物种多样性差异不显著。TWINSPAN和DCA分析显示，河岸植物群落可分为6大类群，这些类群呈现沿湿度梯度方向的分布格局。

异源精子质膜蛋白质在银鲫卵雌核发育初级控制中的作用

<正> 已有研究揭示,在银鲫卵受精孔区域可能存在识别两类不同来源精子(同源精子和异源精子)的特异性受体,换句话说,就是在两类精子的某一部位应存在被银鲫卵上初级控制特异性受体识别的位点。近年来,对脊椎动物的受精生物学研究发现,精子质膜上(特别是质膜表面)具有许多蛋白质受体,它们在受精过程中,对精子的激动、精子对卵子的吸附以及精卵间的相互识别等有着重要作用。据此,我们可以推测,精子识别银鲫卵初级控制受体的位点也可能存在于其质膜蛋白质中。为了能够证实这一假设,本实验采用胰蛋白酶处理异源(红鲤)精子,再与银鲫卵子

西藏原生动物肉足虫一新种和两新亚种的描述

<正> 中国科学院青藏综合科学考察队于1966、1973—1976年在西藏全境采集了大量的水生生物标本,作者从中共观察到原生动物458种,其中肉足虫170种,纤毛虫288种。关于西藏原生动物的分类区系、地理分布、生态特点等已另有报道。本文仅对匣壳虫属Centropyxis中一新种、二新亚种进行描述。

Molecular cloning and characterization of carp (Cyprinus carpio L.) CD8 beta and CD4-like genes

Partial cDNA sequences of both CD8 beta and CD4-like (CD4L) genes of common carp (Cyprinus carpio L.) were isolated from thymus cDNA library by the method of suppression subtractive hybridization (SSH). Subsequently the full length cDNAs of carp CD8 and CD4L were obtained by means of 3' RACE and 5' RACE, respectively. The full length cDNA of carp CD8 is 1164 bp and encodes 207 amino acids including a signal peptide region of 24 amino acids, a transmembrane region of 23 amino acids from aa 167 to aa189 and an immunoglobulin V-set from aa 19 to aa 141. Similar to other species CD8 beta s,carp CD8 beta also lacks p56(lck) domain in the cytoplasmic region. The full length cDNA of carp CD4L is 2001 bp and encodes 458 amino acids including four immunoglobulin (Ig)-like domains in the extracellular region, a transmembrane region of 23 amino acids at the C-terminal region from aa 402 to aa 424 and a cytoplasmic tail. Similar to mammalian, avian CD4s and fugu CD4L, carp CD4L also has the conserved p56(lck) tyrosine kinase motif (C-X-C) in the cytoplasmic region. RT-PCR analysis demonstrated that carp CD8 beta and CD4L genes were both expressed predominantly in thymus. The results from this study can be used to understand the evolution of both the CD8 beta and CD4 molecules which can be used as markers for cytotoxic and helper T cells in carp. (c) 2007 Published by Elsevier Ltd.

Temperature- and salinity-dependent development of a Nordic strain of Ichthyophthirius multifiliis from rainbow trout

During the twentieth century evidence was presented which suggested the presence of various strains and races of the parasite Ichthyophthirius multifiliis Fouquet. However, ecological profiles of various parasite isolates from different climatic zones are sparse. Such stringent characterizations of parasite development at defined abiotic conditions could provide valuable criteria for the different races: profile comparison from various localities is one way to differentiate these strains. Baseline investigations were therefore performed on the associations between abiotic factors (temperature/salinity) and the development of theronts in tomocysts of I. multifiliis isolated from rainbow trout in a Danish trout farm. It was shown that tomocyst formation and theront development took place between 5 and 30degreesC. Development rates and sizes of theronts were clearly affected by temperature: theronts escaped tomocysts already after 16-27 h at 25degreesC and 30degreesC, whereas this process took 8-9 days at 5degreesC. Likewise, theront size decreased steadily from a maximum of 57.4 x 28.6 mum at 5degreesC to 28.6 x 20.0 mum at 30degreesC. This size variation was only partly associated with the number of theronts that appeared at different temperatures. The lowest number of theronts escaping from one tomocyst was indeed found at 5-7degreesC (mean 329-413). At 11.6, 17.0 and 21degreesC. the highest number of theronts appeared (mean 546-642). However, at 25 and 30degreesC, the number decreased (458 and 424, respectively). Additional studies on the salinity dependent development of the parasite (at 11.6degreesC) showed that salinities above 5 p.p.t. totally inhibited development. Even at 5 p.p.t. the developmental time significantly increased and the number of theronts produced from one tomocyst decreased.