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关键词： Animals   Brain   Central Nervous System Diseases   Humans   Receptors   Glutamate   Research Support   U.S. Gov't   P.H.S.  

摘要： Glutamate is the principal excitatory neurotransmitter in the mammalian central nervous system. After release from presynaptic terminals, glutamate binds to both ionotropic and metabotropic receptors to mediate fast, slow, and persistent effects on synaptic transmission and integrity. There are three types of ionotropic glutamate receptors. N-Methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA), and kainate receptors are principally activated by the agonist bearing its name and are permeable to cationic flux;hence, their activation results in membrane depolarization. All ionotropic glutamate receptors are believed to be composed of four distinct subunits, each of which is topologically arranged with three transmembrane-spanning and one pore-lining (hairpin loop) domain. In contrast, metabotropic glutamate receptors are G protein (guanine nucleotide-binding protein) -coupled receptors linked to second-,messenger systems. Group I metabotropic glutamate receptors are linked to phospholipase C, which results in phosphoinositide hydrolysis and release of calcium from intracellular stores. Group II and group III metabotropic glutamate receptors are negatively linked to adenylate cyclase, which catalyzes the production of cyclic adenosine monophosphate. Each metabotropic glutamate receptor is composed of seven transmembrane-spanning domains, similar to other members of the superfamily of metabotropic receptors, which includes noradrenergic, muscarinic acetylcholinergic, dopaminergic, serotonergic (except type 3 receptors), and gamma-aminobutyric acid (GABA) type B receptors. This review summarizes the relevant molecular biology and ontogeny of glutamate receptors in the central nervous system and highlights some of the roles that they can play during brain development and in certain disease states.

关键词： Animals   Body Constitution   Evolution   Female   Growth   Male   Models, Biological   Random Allocation   Reproducibility of Results   Selection (Genetics)   Sex Reversal, Gonadal   Sexual Maturation   Sexual Maturation   Species Specificity   Time Factors  

摘要： Organisms that change sex during their lifetime use a variety of strategies--they may be female first, male first or even repetitive sex changers. Natural selection should favour those individuals that change sex at a time when it increases their reproductive value. Allsop and West claim that the relative timing of sex change is invariant across all animals, with individuals changing sex at 72% of their maximum body size, and infer that natural selection for sex change must therefore be fundamentally similar across animals. Here we explain why we believe that Allsop and West"s claims are not supported by their analysis or by their empirical data.

关键词： 胰岛素样生长因子-I   IGF-Ⅰ   细胞营养因子   中枢神经系统   转基因动物模型   生物学作用  

摘要： 胰岛素样生长因子 I(IGF I)是一种多功能性的细胞营养因子 ,在中枢神经系统的发育过程中发挥着重要的作用。近年来 ,针对IGF I在中枢神经系统 (CNS)中的生物学作用开展了大量的研究。综述了利用IGF I及其所属蛋白家族部分成员的转基因动物模型研究它们在中枢神经系统中的分布和对中枢神经系统各组成部分生长发育的影响及其临床学上的应用。

关键词： 蛙类   中国大鲵   生物学  

摘要： 综合论述了中国养殖的6种主要两栖动物:虎纹蛙RanatigrinarugulosaWiegmann、棘胸蛙RanaspinosaDavid、中国林蛙RanatemporariachensinensisDavid、牛蛙RanacatesbeianaShaw、猪蛙Ranagrylio和中国大鲵MegalobatrachusdavidianusBlanchara的生物学研究成果,包括养殖种类与地理分布,栖息习性,对盐度、温度、湿度、溶解氧、pH值的适应,摄食方式与食物组成,生长与繁殖生物学;展望了其生物学研究前景。

关键词： 动物种群   集体主义   社会生物学   斑羚   鹤  

摘要： 动物界尽管存在着残酷的生存斗争，但是也存在着相互合作和帮助的现象，这是由生存需要导致的结果。不同的动物之间有时有着相对稳定的互相关系，特别是大动物和小动物之间。

关键词： 哺乳动物   外周皮肤   感受器   分子生物学   伤害性感受器  

摘要： 伤害性感受器(nociceptor)是Sherrington(1906)首次提出的概念，指对伤害性或持续性刺激特异敏感的感受器，广泛分布于无毛或有毛皮肤、肌肉、关节和内脏器官的游离神经终末，一般认为属于Aδ和C类神经纤维，前者传导速度为5～30m／s，后者为0．5～2m／s；伤害性刺激(noxious stimulus)是指引起正常组织损伤的刺激。伤害性感觉机制的主

关键词： 水生动物   虹彩病毒   分子生物学   蛙病毒属  

摘要： 摘要: 近年来在世界范围出现的由虹彩病毒感染引起的水生动物高发病率和高死亡率现象给水产业造成了重大经济损失,引起了病毒学家们的热切关注,根据ICTV第七次报告,虹彩病毒科(Iridoviridae)分为4个属,包括感染脊椎动物的蛙病毒属(Ranavirus)和淋巴囊肿病毒属(Lymphocystivirus),以及感染无脊椎动物的虹彩病毒属(Iridovirus)和绿虹彩病毒属(Chloriridovirus).  

关键词： PALEONTOLOGY   PHENOTYPE   FOSSILS   VERTEBRATES   GENETIC research   PALEONTOLOGISTS  

摘要： Competing interpretations of human origins and evolution have recently proliferated despite the accelerated pace of fossil discovery. These controversies parallel those involving other vertebrate families and result from the difficulty of studying evolution among closely related species. Recent advances in developmental and quantitative genetics show that some conventions routinely used by hominid and other mammalian paleontologists are unwarranted. These same advances provide ways to integrate knowledge of the genotype into the study of the phenotype. The result is an approach that promises to yield a fuller understanding of evolution below the family level.

关键词： 动物   寄生虫病   免疫诊断   分子生物学  

摘要： 1.1 0　建立动物寄生虫病免疫诊断方法的关键要素　衡量各种免疫诊断方法的优劣一般根据三项要素 ,即敏感性、特异性和实用性。三项皆高 (强 )者为优。敏感性的高低以能检测到抗体或抗原量的多少为依据 ,即能检出越少的量越敏感 ,但在临诊应用时则以阳性检出率高低为依据 ,越高越好 ;特异性是以非特异性反应多少为依据 ,少则强 ,在临诊应用时以假阳性反应高低为依据 ,越低越强。决定敏感性和特异性高低的原因不仅取决于不同的方法种类 ,也同样取决于抗原 (抗体 )制备技术 ,阳阴性判定标准 (阈值 )的制定、操作者的技术水平 ,所用试剂质量、仪器器材的先进程度 ,实验动物的质量等多项因素。实际上遇到较多

关键词： ecological risk assessment   home range   critical patch size   populations   modeling  

摘要： Many contaminant releases to the terrestrial environment are of small areal extent. Thus, rather than evaluating the ecological impact on species in the immediate vicinity of the release, it may be more ecologically meaningful to determine if population impacts occur at the landscape level. In order to do this, the cumulative impact of all releases in the landscape under consideration must be evaluated. If the release sites are viewed as localized areas that are no longer available for use by ecological receptors (i.e., no longer part of the habitat), this can be thought of as a form of habitat fragmentation. Habitat fragmentation is typically viewed as the loss of large areas of habitat within a landscape, leaving small isolated patches of intact habitat within a hostile matrix. Small-scale contaminant releases, on the other hand, result in small uninhabitable areas within a primarily intact habitat. With this consideration in mind, we analyzed the wildlife and conservation biology literature to determine if information on habitat size requirements such as home-range or critical patch size could inform us about the potential for impact at the landscape level from release sites based on the size of the release alone. We determined that evaluating the impact of release size had to be conducted within a contextual basis (considering the existing state of the landscape). Therefore, we also reviewed the population modeling literature to determine if models could be developed to further evaluate the impact of the spatial extent of chemical releases on the landscape. We identified individual-based models linked to geographic information systems to have the greatest potential in investigating the role of release size with respect to population impacts at the landscape level.