Virology: independent virus development outside a host

Viruses are thought to be functionally inactive once they are outside and independent of their host cell. Here we describe an exceptional property of a newly discovered virus that infects a hyperthermophilic archaeon growing in acidic hot springs: the lemon-shaped viral particle develops a very long tail at each of its pointed ends after being released from its host cell. The process occurs only at the temperature of the host's habitat (75-90 degrees C) and it does not require the presence of the host cell, an exogenous energy source or any cofactors. This host-independent morphological development may be a strategy for viral survival in an environment that is unusually harsh and has limited host availability.     

Transient dynamics of an altered large marine ecosystem

Overfishing of large-bodied benthic fishes and their subsequent population collapses on the Scotian Shelf of Canada's east coast and elsewhere resulted in restructuring of entire food webs now dominated by planktivorous, forage fish species and macroinvertebrates. Despite the imposition of strict management measures in force since the early 1990s, the Scotian Shelf ecosystem has not reverted back to its former structure. Here we provide evidence of the transient nature of this ecosystem and its current return path towards benthic fish species domination. The prolonged duration of the altered food web, and its current recovery, was and is being governed by the oscillatory, runaway consumption dynamics of the forage fish complex. These erupting forage species, which reached biomass levels 900% greater than those prevalent during the pre-collapse years of large benthic predators, are now in decline, having outstripped their zooplankton food supply. This dampening, and the associated reduction in the intensity of predation, was accompanied by lagged increases in species abundances at both lower and higher trophic levels, first witnessed in zooplankton and then in large-bodied predators, all consistent with a return towards the earlier ecosystem structure. We conclude that the reversibility of perturbed ecosystems can occur and that this bodes well for other collapsed fisheries.     

Genome-wide atlas of gene expression in the adult mouse brain

Molecular approaches to understanding the functional circuitry of the nervous system promise new insights into the relationship between genes, brain and behaviour. The cellular diversity of the brain necessitates a cellular resolution approach towards understanding the functional genomics of the nervous system. We describe here an anatomically comprehensive digital atlas containing the expression patterns of approximately 20,000 genes in the adult mouse brain. Data were generated using automated high-throughput procedures for in situ hybridization and data acquisition, and are publicly accessible online. Newly developed image-based informatics tools allow global genome-scale structural analysis and cross-correlation, as well as identification of regionally enriched genes. Unbiased fine-resolution analysis has identified highly specific cellular markers as well as extensive evidence of cellular heterogeneity not evident in classical neuroanatomical atlases. This highly standardized atlas provides an open, primary data resource for a wide variety of further studies concerning brain organization and function.     

Feline sarcoma virus polyprotein P115 binds a host phosphoprotein in transformed cells

Several independent isoltes of feline sarcoma virus (FeSV) have been described. Such viruses are apparently derived by genetic recombination between feline leukaemia virus (FeLV) genomic RNA and host cellular genetic sequences with transforming potential. Two FeSV isolates, one originally described by Gardner and the second by Snyder-Theilen, have been shown to encode polyproteins of around 115,000 molecular weight. Both polyproteins contain FeLV structural components (p15, p12) at their amino terminus in addition to nonstructural carboxyl terminal components encoded by acquired sequences within the FeSV genome. We have previously shown that Gardner FeSV P115 contains multiple sites of phosphorylation within its nonstructural component and possesses an associated protein kinase activity. In the present study we describe the expression in cells derived from a number of mammalian species, of a highly conserved celklular phosphoprotein with binding affinity for Gardner FeSV P115. This protein, designated P150, exhibits an associated protein kinase activity and is immunologically and structurally distinct from polyproteins encoded by the Gardner or Snyder-Theilen strains of FeSV.     

Evasion of intracellular host defence by hepatitis C virus

Viral infection of mammalian cells rapidly triggers intracellular signalling events leading to interferon alpha/beta production and a cellular antiviral state. This 'host response' is our first line of immune defence against infection as it imposes several barriers to viral replication and spread. Hepatitis C virus (HCV) evades the host response through a complex combination of processes that include signalling interference, effector modulation and continual viral genetic variation. These evasion strategies support persistent infection and the spread of HCV. Defining the molecular mechanisms by which HCV regulates the host response is of crucial importance and may reveal targets for novel therapeutic strategies.     

艺术情感表现与器乐演奏特征分析

艺术是生活的调味品,是对生活的另一种诠释,丰富的情感让艺术更具生命力和感染力。在演奏艺术中,情感表达非常重要,不仅可以提升演奏的表现力,还可以升华作品蕴涵的情感。不同的演奏特征可以表现不同的艺术情感。要不断提高艺术修养,注重艺术审美,深刻理解作品,正确处理演奏技巧和情感的关系,增强情感在演奏中的表现力。     

The impact of specialized enemies on the dimensionality of host dynamics

Although individual species persist within a web of interactions with other species, data are usually gathered only from the focal species itself. We ask whether evidence of a species' interactions be detected and understood from patterns in the dynamics of that species alone. Theory predicts that strong coupling between a prey and a specialist predator/parasite should lead to an increase in the dimensionality of the prey's dynamics, whereas weak coupling should not. Here we describe a rare test of this prediction. Two natural enemies were added separately to replicate populations of a moth. For biological reasons that we identify here, the prediction of increased dimensionality was confirmed when a parasitoid wasp was added (although this increase had subtleties not previously appreciated), but the prediction failed for an added virus. Thus, an imprint of the interactions may be discerned within time-series data from component species of a system.     

A theoretical framework of tracer methods for marine sediment dynamics

A new theoretical framework of tracer methods is proposed in the present contribution, on the basis of mass conservation. This modet is applicable for both artificial and natural tracers. It can be used to calculate the spatial distribution patterns of sediment transport rate, thus providing independent information and verification for the results derived from empirical formulae. For the procedures of the calculation, first, the tracer concentration and topographic maps of two times are obtained. Then, the spatial and temporal changes in the concentration and seabed etevation are calculated, and the boundary conditions required are determined by fietd observations (such as flow and bedform migration measurements). Finally, based upon eqs. (1) and (13), the transport rate is calculated and expressed as a function of the position over the study area. Further, appropriate modifications to the modet may allow the tracer to have different densities and grain size distributions from the bulk sediment.     

苦荞蛋白磷酸酶2C家族的鉴定及表达分析

为了研究苦荞蛋白磷酸酶2C(PP2C)家族的成员和分类,及后续探究其在苦荞生长发育中的功能,本文利用生物信息学方法对苦荞PP2C家族进行鉴定、分类,并对其基因结构、保守基序、分子进化等进行分析.结果表明,苦荞PP2C家族有81个成员,划分为A-K的11个亚族,并且在同亚族中序列特征相似,而不同亚族间序列特征有一定差异;苦荞PP2C家族有14次基因重复事件.此外,qRT-PCR分析结果表明其A亚族基因在苦荞根、茎、叶、花、果中均有表达,除FtPP2C44外的8个基因在苦荞花、果中表达量较高;在苦荞幼苗中,除FtPP2C08外的8个基因均受ABA诱导表达量上调.上述结果揭示了苦荞PP2C家族的成员组成、序列特征、扩增和其A亚族基因的组织表达模式及受ABA诱导表达情况.     

开发海洋能源，建设海洋强国

海洋能源开发是海洋强国建设的重要支撑。论述了近年来科技创新为海洋能源勘探开发做出的巨大贡献,提出了中国海洋能源开发未来的主攻方向及建议:加大近海非常规油气开发技术攻关,为中国油气工业提供更多现实的贡献;加大深海油气勘探开发力度,打造中国油气产业未来的重要接替区;突破天然气水合物规模化开发关键技术,早日实现商业化开采;打造深海能源开发装备舰队,支撑海洋强国建设;抢占先机,布局并推进大洋矿产的勘探开发;进一步加强极地科研攻关,深度参与极地开发。     

Molecular cloning of the whole biosynthetic pathway of a Streptomyces antibiotic and its expression in a heterologous host

The application of molecular cloning to antibiotic-producing microorganisms should lead to enhanced antibiotic productivity and to the biosynthesis of novel antibiotics by in vitro interspecific recombination. To allow such approaches, the genes for antibiotic synthesis must be isolated, analysed and perhaps modified. Certain Streptomyces species produce nearly two-thirds of the known natural antibiotics; the recent development of cloning systems in the genus makes it possible to isolate and analyse Streptomyces genes. However, antibiotics are metabolites which require sets of several enzymes for their synthesis and attempts to isolate the corresponding genes have so far yielded clones carrying either individual genes of the set, or only incomplete gene sets. We describe here the isolation of a large continuous segment of Streptomyces coelicolor DNA which apparently carries the complete genetic information required for synthesis of an antibiotic, actinorhodin , from simple primary metabolites. Not only can the cloned DNA 'complement' all available classes of actinorhodin non-producing mutants of S. coelicolor but, on introduction into a different host, Streptomyces parvulus , it directs the synthesis of the antibiotic. The tendency for the genes for antibiotic synthesis to be clustered together on the chromosomes of Streptomyces species and the availability of plasmid vectors which can carry stable inserts of DNA larger than 30 kilobase pairs (kb) and which can be introduced efficiently into Streptomyces protoplasts, suggest that the experiments described have general significance for this area of biotechnology.     

埃博拉病毒入侵宿主细胞的分子机制

 埃博拉病毒是一类能够感染并引起人和灵长类动物发生埃博拉出血热的烈性囊膜病毒。发现近40年中,埃博拉病毒给人类生命带来了极大威胁。然而,目前人们对于埃博拉病毒的了解非常有限,尤其是病毒与其宿主细胞受体的结合机制和膜融合机制相关信息的缺失,使得针对埃博拉病毒的特效药物的设计和研发工作阻碍重重。本文综述了埃博拉病毒分类、形态、病毒蛋白和病毒生命周期,着重介绍了高福院士团队在埃博拉病毒入侵宿主细胞的分子机制研究中的成果。通过结构学手段解析了埃博拉病毒激活态囊膜糖蛋白GPcl与宿主细胞受体NPC1分子的复合物结构,从原子水平上阐明了埃博拉病毒与宿主细胞相互识别的机制,并在结构基础上对病毒的膜融合促发机制做出推测,提出以埃博拉病毒为代表的新的（第5种）囊膜病毒膜融合激发机制,为抗埃博拉病毒药物和疫苗的设计提供了结构基础。