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关键词： Locomotion   Pattern generation   Coordination   Theoretical models  

摘要： The crustacean swimmeret system includes a distributed set of local circuits that individually control movements of one jointed limb. These modular local circuits occur in pairs in each segmental ganglion, and normally operate synchronously to produce smoothly coordinated cycles of limb movements on different body segments. The system presents exceptional opportunities for computational and experimental investigation of neural mechanisms of coordination because: a. The system will express in vitro the periodic motor pattern that normally drives cycles of swimmeret movements during forward swimming. b. The intersegmental neurons which encode information that is necessary and sufficient for normal coordination have been identified, and their activity can be recorded. c. The local commissural neurons that integrate this coordinating information and tune the phase of each swimmeret are known. d. The complete set of synaptic connections between coordinating neurons and these commissural neurons have been described. e. The synaptic connections onto each local pattern-generating circuit through which coordinating information tunes the circuit's phase have been discovered. These factors make possible for the first time a detailed, comprehensive cellular and synaptic explanation of how this neural circuit produces an effective, behaviorally significant output. This paper is the first comprehensive review of the system's neuroanatomy and neurophysiology, its local and intersegmental circuitry, its transmitter pharmacology, its neuromodulatory control mechanisms, and its interactions with other motor systems. Each of these topics is covered in detail in an attempt to provide a complete review of the literature as a foundation for new research. The series of hypotheses that have been proposed to account for the system's properties are reviewed critically in the context of experimental tests of their validity. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： Polyamines   Membrane transport   Permeases   DNA cloning   Vesicular transport  

摘要： Very limited molecular knowledge exists about the identity and protein components of the ubiquitous polyamine transporters found in animal cells. However, a number of reports have been published over the last 5 years on potential candidates for metazoan polyamine permeases. We review the available evidence on these putative polyamine permeases, as well as establish a useful A << identikit pictureA >> A of the general polyamine transport system, based on its properties as found in a wide spectrum of mammalian cells. Any molecular candidate encoding a putative A << generalA >> A polyamine permease should fit that provided portrait. The current models proposed for the mechanism of polyamine internalization in mammalian cells are also briefly reviewed.

关键词： 水质评价   评价标准   底栖动物   赤水河   长江流域  

摘要： 针对长江流域现有水质评价方法的不足,在赤水河流域对以底栖动物为指示生物的水质评价方法进行了测试。2010年秋季枯水期,研究小组对赤水河干流及部分支流共10个断面开展了数据采集工作,通过对数据的分析,发现底栖动物群落结构能够反应一定的水质污染状况;对部分生物指数进行了测试,结果表明,ASPT计分系统最适宜用于该区域的水质评价,并可以此为基础构建赤水河流域水质生物学评价体系。

关键词： 杖用类   孤雌生殖   两性生殖   生殖转化   研究进展  

摘要： 本文综述了杖角类动物孤雌生殖和两性生殖方式生殖细胞发生、外环境因子诱导两种生殖方式转化的研究现状以及现代生物学技术存枝加类生殖转化机理研究方面取得的成果。

关键词： DEVELOPMENTAL biology   METAMORPHOSIS   GENE expression   RED-eyed treefrog   WOLBACHIA   ESSAYS  

摘要： The environment plays instructive roles in development and selective roles in evolution. This essay reviews several of the instructive roles whereby the organism has evolved to receive cues from the environment in order to modulate its developmental trajectory. The environmental cues can be abiotic (such as temperature or photoperiod) or biotic (such as those emanating from predators, conspecifics, or food), and the "alteration" produces a normal, not a pathological, phenotype, that is appropriate for the environment. In addition, symbiotic organisms can produce important signals during normal development. Environmental cues can be obligatory, such that the organism cannot develop without the environmental cue. These cues often permit and instruct the organism to proceed from one developmental stage to another, as when larvae receive cues to settle and undergo metamorphosis from substrates. Such obligatory cues can also be given by symbionts, as when Wolbachia bacteria prevent apoptosis in developing ovaries of some wasps. Other environmental cues can be used facultatively, allowing organisms to follow different developmental trajectories depending on whether the cue is present or not. This can be seen in the temperature-dependent determination of sex in many reptiles and in the determination of thermotolerance in aphids by their symbiotic bacteria. Signaling from the environment is essential in development, and co-development appears to be normative between symbionts and their hosts. Here, one sees the reciprocal induction of gene expression, just as within the embryonic organism. The ability of organisms to respond to environmental cues by producing different phenotypes may be critically important in evolution, and it may be an essential feature that can facilitate or limit evolution.

标准号: DIN SPEC 1042 Berichtigung 1-2012

标准号: DIN EN ISO 6887-4-2012

关键词： 苜蓿多糖   生物学功能   免疫调节   动物生产  

摘要： 苜蓿多糖(Alfalfa Polysaccharides)是苜蓿(Medicage stativa L.)中所含有的一类生物大分子聚合物,具有广泛的生物学活性。本文从苜蓿多糖的理化性质、提取工艺、生物学功能以及其在动物生产上的应用等方面的研究进展进行了综述。

关键词： 风采   名师   动物生物学   中国动物学会   无脊椎动物学   本科课程   教学指导委员会  

摘要： 许崇任,北京大学元培学院院长、生命科学学院副院长、教授,教育部高等学校生物科学与工程教学指导委员会副主任委员,中国动物学会副理事长。先后讲授无脊椎动物学及实验、生态学及实验、动物学及实验、动物生物学及实验等本科课程。

关键词： 大型底栖动物   海浪河   水质评价   群落结构   典范对应分析  

摘要： 本研究在牡丹江海浪河选择10个典型断面,于2009-2010年春、夏、秋、冬四季共进行4次采样工作,对其大型底栖动物进行定性和定量分析。采用多元统计方法分析了群落结构和生物多样性,通过典范对应分析探讨了大型底栖动物与环境因子的关系,为海浪河的环境保护和生态恢复提供参考性依据。 调查期间共采到大型底栖动物55种。其中,水生昆虫最多,38种,占69.1%；环节动物次之,11种,占20.0%；软体动物5种,占9.1%；甲壳动物1种,占1.8%,年平均密度为536.4ind./m2。海浪河大型底栖动物的种数时空变化明显,时间变化为夏季>冬季>春季>秋季,空间变化为上游>中游>下游,这种差异与其特定的环境因子有一定关系。 调查期间,海浪河大型底栖动物多样性指数中的Shannon-Wiener指数全年为0.60-5.00,平均值以夏季最高(3.89),秋季最低(1.13)；Margalef指数全年为0.41-2.58,平均值以夏季最高(1.71),秋季最低(0.91)；BI指数全年为3.89-9.59,平均值以秋季最高(8.76),夏季最低(6.29)；Goodnight-whitely指数全年为0.9%-99.6%,平均值以春季最高(83.0%),夏季最低(22.7%)。Shannon-Wiener指数的变化趋势是夏季>冬季>春季>秋季；Margalef指数是夏季>春季>冬季>秋季；BI指数是秋季>春季>冬季>夏季；Goodnight-whitely指数是春季>秋季>冬季>夏季。 TWINSPAN分类结果表明,海浪河各断面大型底栖动物群落结构差异明显,春季、夏季、秋季和冬季各断面群落组成可划分为3或4类,组内相似性较高,组间群落差异大,各断面群落结构的差异与海浪河的水文条件及季节变化相关。 不同季节对海浪河大型底栖动物群落结构具有显著影响的因子不同。典范对应分析结果表明,溶解氧、水温、营养盐是影响海浪河大型底栖动物组成和物种分布的主要因素。 根据多样性污染指数评价标准来看,河夹大坝(1#)、斗银河口(4#)、英雄桥(5#)断面水质为中-重度污染,其它断面水质也都处于不同程度的污染状态。