企业并购中的商誉问题

对近年来在我国悄然兴起的企业并购浪潮进行了分析,指出在并购中产生的商誉受并购业务的会计处理方法以及众多的现实及潜在因素的影响,其采用的方法也需要进一步调整和完善。对商誉问题的正确认识和科学处理,有助于产权制度改革及社会资源的整体优化。     

“遗传印记”现象的研究

“遗传印记”现象是由于子代体内来自父母双方的等位基因一方表达、另一方沉默造成的，对该现象的研究是分子遗传学研究的新兴领域之一。目前，通过一些研究方法，对“遗传印记”的分子机制已有一定的认识，随着对“遗传印记”研究的逐渐深入，必将深化人们对遗传和生命本质的认识。     

Genomic perspectives in microbial oceanography

The global ocean is an integrated living system where energy and matter transformations are governed by interdependent physical, chemical and biotic processes. Although the fundamentals of ocean physics and chemistry are well established, comprehensive approaches to describing and interpreting oceanic microbial diversity and processes are only now emerging. In particular, the application of genomics to problems in microbial oceanography is significantly expanding our understanding of marine microbial evolution, metabolism and ecology. Integration of these new genome-enabled insights into the broader framework of ocean science represents one of the great contemporary challenges for microbial oceanographers.     

基于DEA方法的企业并购目标选择策略

针对企业并购(MA)目标选择问题,利用数据包络分析(DEA)方法从效率和规模两方面进行研究,提出一个考虑个体偏好的并购目标选择循环策略.首先定义一个体现企业个体偏好的并购方案偏好函数,再利用该函数筛选出可行并购方案.在此基础上,利用可行并购方案的交叉效率选出最佳并购方案,该并购方案参与下一轮循环直至无可行并购方案.最后,通过一个算例说明了该方法的可行性和有效性.     

Detectable radio flares following gravitational waves from mergers of binary neutron stars

Mergers of neutron-star/neutron-star binaries are strong sources of gravitational waves. They can also launch subrelativistic and mildly relativistic outflows and are often assumed to be the sources of short γ-ray bursts. An electromagnetic signature that persisted for weeks to months after the event would strengthen any future claim of a detection of gravitational waves. Here we present results of calculations showing that the interaction of mildly relativistic outflows with the surrounding medium produces radio flares with peak emission at 1.4 gigahertz that persist at detectable (submillijansky) levels for weeks, out to a redshift of 0.1. Slower subrelativistic outflows produce flares detectable for years at 150 megahertz, as well as at 1.4 gigahertz, from slightly shorter distances. The radio transient RT 19870422 (ref. 11) has the properties predicted by our model, and its most probable origin is the merger of a compact neutron-star/neutron-star binary. The lack of radio detections usually associated with short γ-ray bursts does not constrain the radio transients that we discuss here (from mildly relativistic and subrelativistic outflows) because short γ-ray burst redshifts are typically >0.1 and the appropriate timescales (longer than weeks) have not been sampled.     

家兔基因文库的建立

根据鸟枪法克隆基因的原则，建立了家兔总ＤＮＡ文库。为适应同位素标记探针法克隆筛选方法，建立了以人噬菌体为载体的文库。每个重组子携家兔基因组ＤＮＡ平均２０ｋｂ，共获重组噬菌体达１０＾６。以人生长激素ｃＤＮＡ为探针，采用噬菌斑原位杂交、斑点杂交和Ｓｏｕｔｈｅｒｎ杂交等操作，对以噬菌体为载体的文库进行了筛选和有效性验证。结果表明：（１）人生长激素与兔生长激素的ＤＮＡ存在相当的同源性，以人生长激素ｃＤＮＡ     

Genomic island variability facilitates Prochlorococcus-virus coexistence

Prochlorococcus cyanobacteria are extremely abundant in the oceans, as are the viruses that infect them. How hosts and viruses coexist in nature remains unclear, although the presence of both susceptible and resistant cells may allow this coexistence. Combined whole-genome sequencing and PCR screening technology now enables us to investigate the effect of resistance on genome evolution and the genomic mechanisms behind the long-term coexistence of Prochlorococcus and their viruses. Here we present a genome analysis of 77 substrains selected for resistance to ten viruses, revealing mutations primarily in non-conserved, horizontally transferred genes that localize to a single hypervariable genomic island. Mutations affected viral attachment to the cell surface and imposed a fitness cost to the host, manifested by significantly lower growth rates or a previously unknown mechanism of more rapid infection by other viruses. The mutant genes are generally uncommon in nature yet some carry polymorphisms matching those found experimentally. These data are empirical evidence indicating that viral-attachment genes are preferentially located in genomic islands and that viruses are a selective pressure enhancing the diversity of both island genes and island gene content. This diversity emerges as a genomic mechanism that reduces the effective host population size for infection by a given virus, thus facilitating long-term coexistence between viruses and their hosts in nature.     

Genomic approaches to studying the human microbiota

The human body is colonized by a vast array of microbes, which form communities of bacteria, viruses and microbial eukaryotes that are specific to each anatomical environment. Every community must be studied as a whole because many organisms have never been cultured independently, and this poses formidable challenges. The advent of next-generation DNA sequencing has allowed more sophisticated analysis and sampling of these complex systems by culture-independent methods. These methods are revealing differences in community structure between anatomical sites, between individuals, and between healthy and diseased states, and are transforming our view of human biology.     

绿头鸭基因组微卫星分布规律研究

[目的]研究绿头鸭(Anas platyrhynchos)的全基因组微卫星分布特征及规律.[方法]利用生物信息学方法对已报道的绿头鸭全基因组查询搜索并进行特征分析.[结果]在绿头鸭1 070 Mbp的基因组中,1～6个碱基重复的微卫星数量有476 957个,总长度为9 101 935 bp,相对丰度为445.77个·Mb-1,占全基因长度的0.83％.不同重复类型的微卫星中单碱基的数量最多,有326 468个,长度为5 444 144 bp,占基因组微卫星总数的68.45％;然后依次是四碱基、二碱基、三碱基、五碱基和六碱基,数量分别为66 753,30 262,29 712,20 248和3 514个,长度分别为1 504 868,501 244,527 310,920 915和203 454 bp,分别占基因组微卫星总数的14％,6.34％,6.22％,4.25％和0.74％.绿头鸭基因组中,分布数量最多的14种拷贝类型按数量由多到少排列依次是A,A A AC,A A AT,AT,A AT,AC,A AC,A A A AC,C,AG,AAAAT,AAAG,AAGG和AGG,这些拷贝类型的数量均超过2 500个,合计占基因组微卫星总数的95.1％,有明显的A偏倚.[结论]研究结果为绿头鸭微卫星的筛选和开展进一步的分子生物学研究奠定了基础.     

基因组图谱的新发现

当你纵览干细胞的全基因组扫描时你会得到什么？那是一篇高被引论文——该论文为探索基因组的制图工作者开辟了新大陆。此研究由哈佛和麻省理工学院Broad研究所的Bradley Bernstein和Eric Lander及其同事完成,是关于应用新的DNA测序技术揭示细胞调控的文章,位居本期热点论文第5名。     

Genomic organization of EDSV strain AA-2

The genomic organization of egg drop syndrome virus strain AA-2 isolated in China is reported here. The genome was found to be 32 838 bp in length, approximately 2 kb shorter than those of the human subgenus C adenoviruses. Analysis of open reading frames indicated that the genes for major viral structural proteins (55 K, Penton base, pⅦ, pⅩ, pⅥ, Hexon, 100 K, pⅧ and Fiber), as well as EP, DNA polymerase and ⅣaⅡ are present in the expected locations in the genome. EDSV possesses no identifiable E3 and E4 regions and most proteins encoded by E3 and E4 regions of other adenoviruses genome were not presented in EDSV.     

蒲公英药材总DNA的提取

采用改良的CTAB法、SDS法、高盐低pH法提取蒲公英药材基因组总DNA,通过紫外吸收、琼脂糖凝胶电泳检测其纯度与浓度.结果表明,改良的CTAB法所得DNA纯度最高,电泳条带最清晰、完整性好,可作为RAPD,ISSR等分子生物学研究.