湖北省三种蟋蟀鸣声结构分析（直翅目：蟋蟀总科）

重点对湖北省３种蟋蟀的鸣声结构进行了较系统的分析研究,从频域特征和时域特征明显地显示了种间差异。     

棺头蟋属六种常见蟋蟀鸣声特征分析与种类鉴定(直翅目:蟋蟀总科)

本文对蟋蟀科Ｇｒｙｌｉｄａｅ棺头蟋属Ｌｏｘｏｂｌｅｍｍｕｓ６种常见种类的鸣声特征进行了较为系统的分析研究。从其频域特征和时域特征上明显地显示了种间差异,并将其鸣声特征用于分类。     

Analysis of metabolic network based on conservation of molecular structure

Recent work has revealed much about chemical reactions inside hundreds of organisms as well as universal characteristics of metabolic networks, which shed light on the evolution of the networks. However, characteristics of individual metabolites have been neglected. For example, some carbohydrates have structures that are decomposed into small molecules by metabolic reactions, but coenzymes such as ATP are mostly preserved. Such differences in metabolite characteristics are important for understanding the universal characteristics of metabolic networks. To quantify the structure conservation of metabolites, we defined the "structure conservation index" (SCI) for each metabolite as the fraction of metabolite atoms restored to their original positions through metabolic reactions. As expected, coenzymes and coenzyme-like metabolites that have reaction loops in the network show a higher SCI. Using the index, we found that the sum of metabolic fluxes is negatively correlated with the structure preservation of metabolite. Also, we found that each reaction path around high SCI metabolites changes independently, while changes in reaction paths involving low SCI metabolites coincide through evolution processes. These correlations may provide a clue to universal properties of metabolic networks.     

The concept of stcucture in phytosociology with references to classification of plant communities

Summary The concept of structure in phytosociology has been analysed. Three families of structure characteristics have been distinguished: (1) qualitative constituent, (2) quantitative constituent and (3) relational characteristics. Selected structural features are illustrated in some detail and completed by references. The key role of spatial structure has been emphasized and a simple method for the introduction of the parameters of spatial structure in data processing has been proposed. Some remarks to the present syntaxonomy have been added from the spatial structure point of view.Contribution from the Working Group for Data-Processing, International Society for Vegetation Science.Thanks are due to Drs. J. Jenik and J. Kvt for advice and to the Editors for linguistic help.     

高寒植物长鞭红景天种群结构及数量特征

种群结构及数量特征的研究对揭示种群的形成机制和影响因素有着重要意义。在西藏林芝高山森林生态系统国家野外科学观测研究站所在的西藏色季拉山区,采用样地-样方法对研究站旁阳坡、大阴坡、观景台和山口公路上方的长鞭红景天种群进行了调查,共设76块样地、304个样方,进而对长鞭红景天种群结构及数量特征进行了分析研究。结果表明：长鞭红景天在色季拉山主要分布于6个群落类型：急尖长苞冷杉林（P1）、方枝柏林（P2）、薄毛海绵杜鹃灌丛（P3）、毛小叶垫柳灌丛（P4）、鳞腺杜鹃灌丛（P5）及硬叶柳灌丛（P6）。各群落中长鞭红景天平均密度大小顺序为：P3＞P1＞P2＞P4＞P6＞P5、平均基径为：P6＞P2＞P5＞P4＞P1＞P3、平均高度为：P6＞P2＞P5＞P1＞P3＞P4、平均花茎数为：P6＞P2＞P1＞P3＞P5＞P4、平均花茎环数为：P6＞P5＞P2＞P1＞P3＞P4、平均分枝数为：P6＞P1＞P3＞P2＞P4＞P5、重要值为：P5＞P4＞P3＞P2＞P1＞P6。不同群落类型中,长鞭红景天种群的基径、高度及花茎环数等结构系列均表现出不同程度的残缺现象,总体上也出现幼体数目少、成体和老体数目相对较多,但由于其种子繁殖存在一定周期性,并且在自然状态下也进行着无性繁殖,故其仍是增长型种群。对花茎环数的分析发现,长鞭红景天种群大量繁殖的周期是8~10年。长鞭红景天分枝数在5~8枝的植株数比例超过了50 %,分枝数最多的高达45枝,但这些分枝由于相互争夺从根吸收上来的有限营养的原因而生长相对较细。各枝花茎数情况方面,花茎数为1~2枝的所占比例为32.21%,这些主要是侧枝上的花茎;花茎数在7以上的植株占25.82 %,这主要是主轴上的花茎;总体上主轴上着生花茎多于侧枝上的花茎。基径与生长参数关系方面：长鞭红景天的生长参数都是随基径级增大而总体呈现出增大的趋势。研究结果可为进一步探讨长鞭红景天种群生存机制提供基础。     

植物分子生态学进展（Ⅰ）—遗传结构和杂交

从物种遗传结构和杂交的角度介绍了当前植物分子生态学研究的新进展。对于物种遗传结构,文章分析了物种生物学特性、生态因子对它的影响,强调了种群不同世代遗传结构研究的重要性。而在杂交研究领域,文章揭示了分子生物学手段有着比传统形态分析方法更多的优越性。     

山西省农业生态类型分区的研究

农业生态系统是一个多元综合性概念。它是由地貌、气候、土壤、水文、植被等自然环境要素和人类活动干预形成的农业生物群落两大部分组成。其组成部分及诸要素多重联系,相互作用,在一定的结构中共同实现系统功能。进行农业生态类型分区是为农业生态系统总体结构的优化研究提供科学依据。从而对     

The characteristics of the action of gamma irradiation on the secondary structure of ribonuclease in vitro and the effect of oxygen on this process]

The change in the secondary structure of ribonuclease after 60Co gamma irradiation with a dose of 1,000 Gy in 0.2% aqueous solution was estimated using the circular dichroism method. The beta structures were significantly changed, while other types of the secondary structure (alpha-helix and beta-turns) changed insignificantly. The secondary structure injury was also affected by oxygen. The data are attributed to characteristics of the secondary structure of this enzyme.     

锰过氧化物酶的结构与功能

综述了木素降解的关键酶之一锰过氧化物酶的三维分子结构和催化反应性能,综合概述了通过定点诱变等方法对锰过氧化物酶的结构和功能的研究进展。     

藻类光合作用PSI色素蛋白复合物结构及长波荧光特性

综述了藻类光合作用PSI色素蛋白复合物结构及长波荧光特性的研究进展,并同高等植物进行了比较。藻类PSI结构和长波荧光的多样性同高等植物PSI的同一性形成鲜明对比。认为藻类PSI的这种多样性可能具有门类特征。对藻类和高等植物的PSI进行比较研究,将有助于了解PSI的结构、功能和进化。     

基于分形理论的乡村聚落景观空间特征及演变——以厦门市为例

空间结构和空间形态共同构成乡村聚落景观空间特征,对二者的科学分析是乡村土地利用格局优化的基础.本研究采用分形理论,从全市与分乡镇两个尺度上对厦门市乡村聚落景观空间结构的特征和演变进行定量分析,并提出空间格局优化的相应对策.结果表明: 厦门市乡村聚落景观空间结构与形态的分形特征明显.在全市尺度上,聚集维数、交通网络直通度和空间形态维数随时间变化而增大,而空间关联维数持续减少;乡村聚落景观空间结构呈多中心聚集态分布,交通网络通达性变好,空间结构自组织不断优化,而乡村聚落景观空间形态日趋复杂,空间呈扩展的趋势.在分乡镇尺度上,乡村聚落景观空间特征差异显著,空间结构松散、通达性较弱等问题存在于部分乡镇.未来需加强交通等基础设施投入和中心村建设,提高乡村聚落内部各要素的关联度,促使其空间结构优化.本研究结果为优化乡村聚落空间布局、科学编制乡村土地利用规划提供了有力的技术手段和理论支撑.     

Towards an integrated understanding of the structural characteristics of protein residue networks

A protein residue network or PRN is a network induced by spatial contacts between amino acid residues of a protein. Studies of the structure of PRNs have revealed a list of network characteristics common to a diverse class of proteins. Explanations for the observed network characteristics for protein folding have been suggested but not tested in an integrated way. In this article, in silico experiments are performed to understand how structural characteristics of PRNs influence protein folding as modeled by a search problem. We find that the blend of structural characteristics PRNs possess help to place them in a sweet spot within the space of all network configurations tested. PRNs are plausible 3D structures and yield competitive search performances. Hence, it appears that PRNs are in a form suited to the function they evolved into. However, this conclusion is partially contingent upon the fitness function preferentially satisfying short-range links but also allowing short- and long-range interactions to cooperate towards the satisfaction of all links. We close with a discussion on the rather intricate interplay among the three main structural characteristics of PRNs, i.e., clustering, average path length, and assortativity, and their impact on search performance and 3D structure plausibility.     

The Physical and Geometric Properties of Human Transposon Stem–Loop Structures under Natural Selection

Secondary RNA structures play an important role in transposition, in particular, in RNA recognition by transposon proteins. Previously, we found a conserved structure at the 3′-end of human transposons and proposed a hypothesis about the role of this structure in transposition. Although there is no similarity at the sequence level, the conserved position of this structure points to the fact that structural properties occur that are under positive natural selection. In this paper, the physical and geometric properties of stem-loop structures at the 3′-end of human transposons are identified and compared with properties of the structures of other genome regions. Each stem-loop structure was characterized by a set of ten characteristics: the Gibbs free energy, enthalpy, entropy, hydrophilicity, Shift, Slide, Rise, Tilt, Roll, and Twist. A model has been built using machine-learning methods, which recognizes stem-loop structures according to their physical and geometric characteristics with 94% accuracy. The most important parameters in the recognition model are hydrophilicity, enthalpy, Rise, and Twist. These properties of transposon structure are thought to be under positive natural selection.     

AM真菌群落结构与功能研究进展

在总结最近10 a来有关丛枝菌根(AM)真菌研究的基础上,讨论了AM真菌群落结构的概念、特征、功能以及寄主植物、土壤条件、其他土壤微生物、农业技术等因素对AM真菌群落结构的影响及其调控途径;介绍了研究AM真菌群落结构的方法;探讨了今后研究的方向与前景。     

Polymorphism and structure of populations of Siberian spruce (<Emphasis Type="Italic">Picea obovata</Emphasis> Ledeb.) at the northern limits of the species distribution

Polymorphism of the main morphological characteristics of Siberian spruce (Picea obovata Ledeb.), which are used for diagnosing the species, as well as the population structure, was studied at the northern limits of the species habitat and compared with characteristics of spruce from the central regions of the area. The results obtained give an insight into the population structure of Siberian spruce and a pattern of its variation within the area.     

A statistical approach using network structure in the prediction of protein characteristics

MOTIVATION: The Majority Vote approach has demonstrated that protein-protein interactions can be used to predict the structure or function of a protein. In this article we propose a novel method for the prediction of such protein characteristics based on frequencies of pairwise interactions. In addition, we study a second new approach using the pattern frequencies of triplets of proteins, thus for the first time taking network structure explicitly into account. Both these methods are extended to jointly consider multiple organisms and multiple characteristics. RESULTS: Compared to the standard non-network-based method, namely the Majority Vote method, in large networks our predictions tend to be more accurate. For structure prediction, the Frequency-based method reaches up to 71% accuracy, and the Triplet-based method reaches up to 72% accuracy, whereas for function prediction, both the Triplet-based method and the Frequency-based method reach up to 90% accuracy. Function prediction on proteins without homologues showed slightly less but comparable accuracies. Including partially annotated proteins substantially increases the number of proteins for which our methods predict their characteristics with reasonable accuracy. We find that the enhanced Triplet-based method does not currently yield significantly better results than the enhanced Frequency-based method, suggesting that triplets of interactions do not contain substantially more information about protein characteristics than interaction pairs. Our methods offer two main improvements over current approaches--first, multiple protein characteristics are considered simultaneously, and second, data is integrated from multiple species. In addition, the Triplet-based method includes network structure more explicitly than the Majority Vote and the Frequency-based method. AVAILABILITY: The program is available upon request. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.     

热带北缘鹅凰嶂季雨林四种群落特征及成熟度分析

为分析我国热带北缘季雨林的不同演替阶段的群落特征,该研究对广东阳春鹅凰嶂典型季雨林中4种(A、B、C、D)不同植物群落展开调查,对群落的物种组成、多样性和空间结构等进行分析,判断成熟度差异,预测演替方向,并提出优化建议。结果表明:(1)4种群落林层单一,小径级木与下层木占主体地位,具有1～3种明显的优势树种。(2)Shannon-Wiener指数为2.72～3.74,Simpson指数为0.90～0.97,Pielou均匀度指数为0.74～0.89,各群落多样性特征差异显著。(3)4种群落乔木胸径大小比数为0.49～0.51,角尺度为0.56～0.61,混交度为0.54～0.83,林分空间结构指数为60.57～71.44,林分空间结构距离为53.15～68.53。(4)综合群落基本特征、多样性和空间结构特征的分析得出,各群落的成熟度排名为D>A>C>B。综上认为,4种群落都处于演替前期或中期,乔木个体胸径和树高发展空间较大; 群落整体处于中庸生长状态,个体均呈轻微聚集分布,树种表现为中度、强度或极强度混交,空间结构与理想林分存在一定距离。随着成熟度的增加,4种群落都继续以阳性树种作为主要优势树种进行演替,并初步具备该区域地带性顶极群落的典型植被特征; 季雨林群落物种多样性提高,并向混交度增加、空间结构优化、稳定性增强的趋势演替。该研究结果为群落构建机制和森林结构优化等提供科学依据。未来应对该区域加强监管与保护,同时应对该地区的植被生态学和生物多样性保护展开广泛监测与深入研究。     

PII signaling proteins of cyanobacteria and green algae. New features of conserved proteins

The characteristics of signal PII proteins identified in bacteria, archaea, and plants are presented. Special attention is paid to the properties and functions of PII proteins in microorganisms with oxygenic photosynthesis type: cyanobacteria and unicellular green algae. The structure and regulation of PII proteins are reviewed. The mechanisms of interactions of PII proteins with effectors and cellular targets are analyzed in detail. The conservative properties and unique characteristics of proteins from representatives of pro-and eukaryotic phototrophs are discussed.