On the Theory of Speciation Induced by Transposable Elements

A simple methematical model describes the invasion of panmictic, sexually reproducing populations by a newly introduced transposon. The model places important constraints on the properties that transposons must have to successfully invade a population and describes the kinetics with which such an invasion will occur. Invasibility conditions serve as a basis for new, detailed scenarios whereby transposon-mediated depression in fitness produces reproductive isolation of populations. These scenarios, in turn, lead to several speculations concerning the role of transposons in evolution.     

The Role of the Principle of Object-relatedness in the Theory of Activity

The present state of the theory of activity (by which we mean the concept developed by Leont'ev and his school) undoubtedly deserves serious discussion. Such a discussion must not be reduced, as often happens, to a critique of this theory by representatives of other schools and currents in psychology that are based on different theoretical positions (i.e., to a criticism from without), on the one hand, or to an unconditional acceptance of all of its postulates by proponents of this theory, on the other. In my view, the kind of critique of this theory that is most relevant and acutely necessary in terms of both its prospects of development and the extent to which its perceptions accord with other psychological currents is of another sort, namely, a critique from within, by which I mean analysis of its own laws, of the internal logic of development of the theory, and of its internal contradictions, which define its present status and the dynamics of its development. Such an analysis should enable us to stimulate more effectively the internal mechanism of development and self-development of the theory of activity and ensure a transition from a period of stagnation that has produced nothing of note to a progressive evolution of its content and its explanatory power.     

Founder mutations in the Netherlands

In this part of a series on founder mutations in the Netherlands, we review a Dutch family carrying the SCN5a 1795insD mutation. We describe the advances in our understanding of the premature sudden cardiac deaths that have accompanied this family in the past centuries. The mutation carriers show a unique overlap of long-QT syndrome (type 3), Brugada syndrome and progressive cardiac conduction defects attributed to a single mutation in the cardiac sodium channel gene SCN5a. It is at present one of the largest and best-described families worldwide and we have learned immensely from the mouse strains with the murine homologue of the SCN5a 1795insD mutation (SCN5a 1798insD). From the studies currently performed we are about to obtain new insights into the phenotypic variability in this monogenic arrhythmia syndrome, and this might also be relevant for other arrhythmia syndromes and the general population. (Neth Heart J 2009;17:422–8.)     

中国作物种质资源学科的奠基者——记中国农业科学院董玉琛院士

董玉琛院士是我国作物种质资源学科的奠基人之一。将个人的成长置于学科发展和社会大背景下,从时代变迁与个人选择、学科发展与个人贡献、学术特点、科学精神与人格魅力4个方面系统梳理了董玉琛院士学术成长历程,探究其取得成功的影响因素,以启发和激励青年学者,传承和弘扬老科学家的科学精神。     

物种形成基因及其功能

什么是物种?新物种是如何形成的？这些问题是生命科学研究的重大问题.物种的形成是在生殖隔离的基础上某些新的生物学性状的形成和保留,是生物进化的最基本过程,其实质是基因结构突变的积累与功能的分化. 地理隔离使群体中的基因不能交流,基因突变也会影响个体间交配趣向,从而造成交配隔离或者交配后杂合体的基因组不亲和、杂交不育甚至杂交不活,使不同的群体逐渐分化为新物种. 随着分子生物学与基因组学的飞速发展,进化生物学家已经发现一些与物种形成有关的基因-物种形成基因（speciation genes）,鉴定并了解这些基因的功能,不仅能使我们在分子水平上理解新物种形成的实质和规律、而且对于我们突破种间屏障进行远缘杂交育种也有重要的理论指导意义.本文综述了目前对几个物种形成基因及其功能的研究进展,为该领域的进一步研究提供资料.     

"物种的形成"的教学设计

1 教学目标 1.1 知识与技能1 1)阐明并解释物种、隔离等相关概念. 2)运用所学概念分析物种形成的过程. 3)概述物种形成的主要环节以及各环节对于物种形成的作用.     

豆科植物SHR-SCR模块——根瘤“奠基细胞”的命运推手

豆科植物-根瘤菌共生固氮是可持续性农业氮肥的最重要来源。根瘤作为豆科植物共生固氮的一种特化植物侧生器官, 提供了根瘤菌生物固氮必需的微环境, 是根瘤菌的安身之本, 因此, 根瘤的正常发育是实现豆科植物-根瘤菌共生固氮的结构基础。根瘤器官的从头发生主要起始于根瘤菌诱导的根皮层细胞分裂。通常认为豆科植物的根皮层具备有别于非豆科植物根皮层的某种特异属性, 从而响应根瘤菌并与之建立固氮共生, 但长期以来该属性决定的分子机制一直不明确。近日, 中国科学院分子植物科学卓越创新中心王二涛团队以蒺藜苜蓿(Medicago truncatula)等豆科植物和拟南芥(Arabidopsis thaliana)等非豆科植物为研究对象, 发现豆科植物中保守的SHR-SCR干细胞模块决定了其皮层细胞分裂潜能从而赋予根瘤器官发生的命运。该研究揭示了豆科植物根瘤发育的全新机制, 提供了研究和理解植物-根瘤菌固氮共生进化的重要线索, 对提高豆科作物固氮效率和非豆科作物固氮工程具有重要意义。     

The Founder of Plant Taxonomy in China:HU Hsen-Hsu

HU Hsen-Hsu(胡先骕,courtesy name 步曾,Buzeng)was born in Xinjian,Jiangxi Province of China in 1894(Fig.1).He received a bachelor's degree of biology from the Univers...     

The Legume SHR-SCR Module Predetermines Nodule Founder Cell Identity

豆科植物-根瘤菌共生固氮是可持续性农业氮肥的最重要来源。根瘤作为豆科植物共生固氮的一种特化植物侧生器官, 提供了根瘤菌生物固氮必需的微环境, 是根瘤菌的安身之本, 因此, 根瘤的正常发育是实现豆科植物-根瘤菌共生固氮的结构基础。根瘤器官的从头发生主要起始于根瘤菌诱导的根皮层细胞分裂。通常认为豆科植物的根皮层具备有别于非豆科植物根皮层的某种特异属性, 从而响应根瘤菌并与之建立固氮共生, 但长期以来该属性决定的分子机制一直不明确。近日, 中国科学院分子植物科学卓越创新中心王二涛团队以蒺藜苜蓿(Medicago truncatula)等豆科植物和拟南芥(Arabidopsis thaliana)等非豆科植物为研究对象, 发现豆科植物中保守的SHR-SCR干细胞模块决定了其皮层细胞分裂潜能从而赋予根瘤器官发生的命运。该研究揭示了豆科植物根瘤发育的全新机制, 提供了研究和理解植物-根瘤菌固氮共生进化的重要线索, 对提高豆科作物固氮效率和非豆科作物固氮工程具有重要意义。     

Speciation in the yeast genusMetschnikowia

Genetic studies were employed to rationalize speciation in the yeast genusMetschnikowia. Using haploid cultures derived parasexually or from isolated single ascospores, hybrids were produced between mostMetschnikowia taxa. The results provided strong evidence for the acceptance ofM. bicuspidata as type of the genus, and enabled clarification of the relationships among the recognized species. Speciation was based primarily on ascus and ascospore morphology, as classification based on physiological properties was shown to be ineffective.Metschnikowia bicuspidata var.californica var. nov. is described, and some possible evolutionary trends are discussed.Partial support for J. I. P. from a C.S.I.R.O., Australia, Overseas Postgraduate studentship is gratefully acknowledged.     

Speciation in the vanadate-alanylhistidine-peroxide system

The speciation in the quaternary aqueous H+-H2VO4(-)-H2O2-L-alpha-alanyl-L-histidine (Ah) system has been determined from quantitative 51V NMR measurements and potentiometric data (glass electrode). The study was performed in 0.150 M Na(Cl) medium at 25 degrees C. Data were evaluated with the computer program LAKE, which is able to treat combined potentiometric and NMR data. In the ternary H+-H2VO4(-)-Ah system, two complexes, (H+)p(H2VO4-)q(Ah)r, having (p, q, r) values (0, 1, 1) and (1, 1, 1) (pKa = 6.88) explain all data. In the quaternary H+-H2VO4(-)-H2O2-Ah system, seven complexes were determined in addition to all binary and ternary complexes, four with a V/X/Ah ratio 1:1:1 and three with a ratio 1:2:1 (X = peroxo ligand). VX2Ah2- and VX2Ah- (pKa = 8.26) are the main quaternary complexes and predominate in the pH range 5 to 9. Chemical shifts, compositions and formation constants for all the quaternary complexes are given, and equilibrium conditions are illustrated in distribution diagrams.