中国通货膨胀与相对价格可变性——基于长期效应与短期效应的实证分析

在构建通货膨胀与RPV关系理论模型的基础上,运用面板数据固定效应估计量来检验中国通货膨胀对RPV影响的长期效应,并构建向量误差修正模型来分析中国通货膨胀对RPV影响的短期效应。研究得出,在不考虑确定性因素和外生变量的情况下,从全国来看,总体是短期效应大于长期效应;相反则是长期效应略大于短期效应。在上述两种情况下,各地区的长期效应与短期效应也明显不同。因此,国家应该多考虑不同地区通货膨胀对RPV影响的长期效应与短期效应大小,从而有效地治理通货膨胀和稳定物价水平。     

电离辐射声效应的生物效应

本文研究了电离辐射声效应的生物效应,结果表明,电离辐射通过生物体时产生的瞬时热沉积和声瞬变,在辐射生物效应的机制中起重要作用。     

论运动人才的组织效应

正确认识和处理体育运动人才各种组织效应之间的关系，是增强竞技实力的重要途径：（一）力争最佳的整体效应。（二）潜在效应是表象效应的源泉。（三）从有形中认识无形效应。（四）直接与间接相结合。（五）短期效应服从长期效应。     

技术性贸易壁垒的经济效应及对我国农产品出口的影响

目前,技术性贸易壁垒已成为影响我国农产品出口的重要因素.技术性贸易壁垒具有数量控制和价格控制的双重作用,对出口国在短期和中长期内存在着不同的贸易效应、福利效应和产业效应,其对我国农产品出口既存在短期的消极影响,也可能在一定条件下具有长期积极影响.     

活性基因效应假说

根据前人的研究和杂交育种实践，结合基因组印迹的遗传理论，提出杂种优势产生的活性基因效应的假说．认为生物体的基因分为活性基因和无活性基因两类，杂种优势来源于活性基因的加性效应和互作效应；并将杂种优势部分为一般杂种优势和特殊杂种优势两部分，这有利于对杂种优势作深入的分析研究．     

鱼类中的多倍性及其在鱼类演化中的作用

基因组的多倍化在鱼类演化中起过重要作用。国外已有约170个种、亚种和类型的鱼类被证明或推断为多倍体,涉及14个科,其中有些科被整科地视为四倍体起源。核型的比较表明我国鱼类中同样存在进化多倍体,数目已达28个种、亚种和类型;核DNA值的测定结果进一步确证了这一事实。鱼类多倍体可能主要通过间接途径也可能通过杂种繁殖系统起源,但直接起源方式也许还不能过分排除,特别在我国古代。鱼多倍体一般有比亲缘两性二倍体更强的适应和生长繁殖能力,有进一步演化的能力,但对雌核发育多倍体尚难全面下此结论。研究鱼类中的多倍性现象不但在理论上而且在实践上也有重要意义。     

多倍体小麦物种形成可诱发稳定遗传的胞嘧啶甲基化变异

多倍体小麦及其二倍体祖先物种的基因组DNA经一对同位酶(HpaⅡ/Msp工)消化后,与21个不同类型的低拷贝DNA序列进行Southern杂交.结果发现,多倍体小麦实现物种形成后产生了广泛的胞嘧啶甲基化变异.用同样的21种DNA序列为探针与1个人工合成的六倍体小麦及其亲本的Southern杂交结果表明,甲基化变异已存在于该人工小麦的较早期自交世代(S5,S6和S7).而且,在3个自交世代每代随机选取的3个单株之间的限制性酶切片段长度多态(RFLP)谱带均表现为高度一致;这暗示甲基化变异可能发生得更早,或者,甲基化变异具有非随机性.变化后的RFLP谱带在3个自交世代间表现为稳定遗传.甲基化变异虽在整个基因组范围内发生,但可能具有序列特异性.对这种迅速发生的甲基化变异与异源多倍体基因组进化的两个重要属性即遗传二倍化和基因分化之间的可能关系进行了讨论.     

21世纪水稻育种的新战略——综合利用无融合生殖、异源多倍体化和体细胞杂交技术

从生殖方式改变和作物进化趋势分析,论述了以无融合生殖为基础,结合利用优良基因、多倍体化和现代生物技术的21世纪水稻育种新战略．它包括3个部分：1利用无融合生殖建立快速育种新方法.利用水稻的孤雌生殖和无配子生殖能力,获得早世代稳定品系,建立快速育种方法,把无融合生殖特性与闭颖授粉、优质、抗性等特性结合探索高产优质多抗育种新途径,逐步实现利用无融合生殖固定杂种优势的目的．2利用无融合生殖和多倍体化探索育种新途径异源多倍体化是作物进化的总趋势．水稻是二倍体,基因组小通过无融合生殖、广亲和、异源多倍体化的利用,选育异源多倍体水稻,增加它的遗传变异范围,大幅度提高水稻的产量、质量和抗性．3．无融合生殖水稻和C4作物杂交创造高光效异源多倍体新作物．利用无融合生殖水稻与无融合生殖高光效的C4作物,如高粱、摩擦禾、大黍等杂交,特别是体细胞杂交和基因工程技术,创造具有无融合生殖特性高光效作物新品种     

政府推进型工业化与城镇化动态交互效应研究——以三峡库区为例

基于2003—2014年三峡库区工业化与城镇化面板数据,运用面板向量自回归模型进行实证分析,量化工业化与城镇化动态交互效应,并比较重点库区和一般库区两化动态交互效应的差异性。研究结果表明:三峡库区工业化对城镇化发展的提升作用不明显,城镇化发展依赖于前期增长水平;三峡库区城镇化对工业化发展的影响效果明显,短期对工业化发展存在挤出效应,长期对工业化发展存在溢出效应;政府推进力度越强,则工业化与城镇化的市场自发推进特征就越弱。     

霍尔效应

量子反常霍尔效应是我国科学家从该实验上独立观测到的一个重要物理现象,也是世界基础研究领域的一项重要科学发现.这是在美国物理学家霍尔于1880年发现霍尔效应133年后终于实现了反常霍尔效应的量子化,是我国科学家从实验上独立观测到的一个重要物理现象,也是世界基础研究领域的一项重要科学发现.该文将详细讲解霍尔效应的发展历史.     

Transition from haploidy to diploidy

As a direct consequence of sex, organisms undergo a haploid and a diploid stage during their life cycle. Although the relative duration of haploid and diploid phases varies greatly among taxa, the diploid phase is more conspicuous in all higher organisms. Therefore it is widely believed that diploidy offers more evolutionary possibilities and is thus nearly always selected for. We have now performed computer simulations to investigate one possible advantage of diploidy, that is, protection against the expression of deleterious mutations. Instead of comparing isolated haploid and diploid populations, we considered interbreeding haploids and diploids. Diploids invaded the population only when the dominance degree of a single deleterious mutation was smaller than about 1/2, and the condition allowing diploidy to invade depended on how harmful the mutation was.     

Unravelling angiosperm genome evolution by phylogenetic analysis of chromosomal duplication events

Conservation of gene order in vertebrates is evident after hundreds of millions of years of divergence, but comparisons of the Arabidopsis thaliana sequence to partial gene orders of other angiosperms (flowering plants) sharing common ancestry approximately 170-235 million years ago yield conflicting results. This difference may be largely due to the propensity of angiosperms to undergo chromosomal duplication ('polyploidization') and subsequent gene loss ('diploidization'); these evolutionary mechanisms have profound consequences for comparative biology. Here we integrate a phylogenetic approach (relating chromosomal duplications to the tree of life) with a genomic approach (mitigating information lost to diploidization) to show that a genome-wide duplication post-dates the divergence of Arabidopsis from most dicots. We also show that an inferred ancestral gene order for Arabidopsis reveals more synteny with other dicots (exemplified by cotton), and that additional, more ancient duplication events affect more distant taxonomic comparisons. By using partial sequence data for many diverse taxa to better relate the evolutionary history of completely sequenced genomes to the tree of life, we foster comparative approaches to the study of genome organization, consequences of polyploidy, and the molecular basis of quantitative traits.     

The evolutionary origin of complex features

A long-standing challenge to evolutionary theory has been whether it can explain the origin of complex organismal features. We examined this issue using digital organisms--computer programs that self-replicate, mutate, compete and evolve. Populations of digital organisms often evolved the ability to perform complex logic functions requiring the coordinated execution of many genomic instructions. Complex functions evolved by building on simpler functions that had evolved earlier, provided that these were also selectively favoured. However, no particular intermediate stage was essential for evolving complex functions. The first genotypes able to perform complex functions differed from their non-performing parents by only one or two mutations, but differed from the ancestor by many mutations that were also crucial to the new functions. In some cases, mutations that were deleterious when they appeared served as stepping-stones in the evolution of complex features. These findings show how complex functions can originate by random mutation and natural selection.     

Evidence for the evolution of multiple genomes in arbuscular mycorrhizal fungi.

Ancient asexuals directly contradict the evolutionary theories that explain why organisms should evolve a sexual life history. The mutualistic, arbuscular mycorrhizal fungi are thought to have been asexual for approximately 400 million years. In the absence of sex, highly divergent descendants of formerly allelic nucleotide sequences are thought to evolve in a genome. In mycorrhizal fungi, where individual offspring receive hundreds of nuclei from the parent, it has been hypothesized that a population of genetically different nuclei should evolve within one individual. Here we use DNA-DNA fluorescent in situ hybridization to show that genetically different nuclei co-exist in individual arbuscular mycorrhizal fungi. We also show that the population genetics techniques used in other organisms are unsuitable for detecting recombination because the assumptions and underlying processes do not fit the fungal genomic structure shown here. Instead we used a phylogenetic approach to show that the within-individual genetic variation that occurs in arbuscular mycorrhizal fungi probably evolved through accumulation of mutations in an essentially clonal genome, with some infrequent recombination events. We conclude that mycorrhizal fungi have evolved to be multi-genomic.     

Ancestral polyploidy in seed plants and angiosperms

Whole-genome duplication (WGD), or polyploidy, followed by gene loss and diploidization has long been recognized as an important evolutionary force in animals, fungi and other organisms, especially plants. The success of angiosperms has been attributed, in part, to innovations associated with gene or whole-genome duplications, but evidence for proposed ancient genome duplications pre-dating the divergence of monocots and eudicots remains equivocal in analyses of conserved gene order. Here we use comprehensive phylogenomic analyses of sequenced plant genomes and more than 12.6 million new expressed-sequence-tag sequences from phylogenetically pivotal lineages to elucidate two groups of ancient gene duplications-one in the common ancestor of extant seed plants and the other in the common ancestor of extant angiosperms. Gene duplication events were intensely concentrated around 319 and 192 million years ago, implicating two WGDs in ancestral lineages shortly before the diversification of extant seed plants and extant angiosperms, respectively. Significantly, these ancestral WGDs resulted in the diversification of regulatory genes important to seed and flower development, suggesting that they were involved in major innovations that ultimately contributed to the rise and eventual dominance of seed plants and angiosperms.     

Genome-wide genetic analysis of polyploidy in yeast

Polyploidy, increased sets of chromosomes, occurs during development, cellular stress, disease and evolution. Despite its prevalence, little is known about the physiological alterations that accompany polyploidy. We previously described 'ploidy-specific lethality', where a gene deletion that is not lethal in haploid or diploid budding yeast causes lethality in triploids or tetraploids. Here we report a genome-wide screen to identify ploidy-specific lethal functions. Only 39 out of 3,740 mutations screened exhibited ploidy-specific lethality. Almost all of these mutations affect genomic stability by impairing homologous recombination, sister chromatid cohesion, or mitotic spindle function. We uncovered defects in wild-type tetraploids predicted by the screen, and identified mechanisms by which tetraploidization affects genomic stability. We show that tetraploids have a high incidence of syntelic/monopolar kinetochore attachments to the spindle pole. We suggest that this defect can be explained by mismatches in the ability to scale the size of the spindle pole body, spindle and kinetochores. Thus, geometric constraints may have profound effects on genome stability; the phenomenon described here may be relevant in a variety of biological contexts, including disease states such as cancer.     

The evolutionary foundation of genomic imprinting in lower vertebrates

In mammals,genomic imprinting confers developmental asymmetry and complementation on the parental genomes and makes both parental genomes essential for complete development.Genomic imprinting is,therefore,the first regulatory step of genome-wide gene expression of embryogenesis and thought to be the epigenetic foundation of bisexual reproduction.However,how the genomic imprinting is originated,established and maintained during vertebrate evolution remains unknown.Because no endogenous imprinting gene has be...     

Predator-induced behaviour shifts and natural selection in field-experimental lizard populations

The role of behaviour in evolutionary change has long been debated. On the one hand, behavioural changes may expose individuals to new selective pressures by altering the way that organisms interact with the environment, thus driving evolutionary divergence. Alternatively, behaviour can act to retard evolutionary change: by altering behavioural patterns in the face of new environmental conditions, organisms can minimize exposure to new selective pressures. This constraining influence of behaviour has been put forward as an explanation for evolutionary stasis within lineages and niche conservatism within clades. Nonetheless, the hypothesis that behavioural change prevents natural selection from operating in new environments has never been experimentally tested. We conducted a controlled and replicated experimental study of selection in entirely natural populations; we demonstrate that lizards alter their habitat use in the presence of an introduced predator, but that these behavioural shifts do not prevent patterns of natural selection from changing in experimental populations.     

The genomic and epidemiological dynamics of human influenza A virus

The evolutionary interaction between influenza A virus and the human immune system, manifest as 'antigenic drift' of the viral haemagglutinin, is one of the best described patterns in molecular evolution. However, little is known about the genome-scale evolutionary dynamics of this pathogen. Similarly, how genomic processes relate to global influenza epidemiology, in which the A/H3N2 and A/H1N1 subtypes co-circulate, is poorly understood. Here through an analysis of 1,302 complete viral genomes sampled from temperate populations in both hemispheres, we show that the genomic evolution of influenza A virus is characterized by a complex interplay between frequent reassortment and periodic selective sweeps. The A/H3N2 and A/H1N1 subtypes exhibit different evolutionary dynamics, with diverse lineages circulating in A/H1N1, indicative of weaker antigenic drift. These results suggest a sink-source model of viral ecology in which new lineages are seeded from a persistent influenza reservoir, which we hypothesize to be located in the tropics, to sink populations in temperate regions.