基于国内、外中学生物学教材对进化论先驱拉马克的重新评价

拉马克作为生物进化论的先驱,\"用进废退\"和\"获得性遗传\"打破了神创论和物种不变的观点,开创了生物学。但在达尔文的\"自然选择\"提出之后,拉马克学说在生物学领域被很大程度地放弃或忽视。通过比较国内、外中学生物学教材,提出中学生物学课堂关于生物进化的教学策略,探讨近年来表观遗传学在进化理论的重要发展,以辩证的思维对进化论先驱拉马克进行了重新评价。     

遗传学的发展与现代达尔文主义的产生

在达尔的进化论中,对于进化的遗传机制,他相信获得性遗传。为了能够建立一种包括遗传、变异和进化的理论,特别是为了说明获得性遗传的原因,达尔复活了古希腊名医生希波克拉底的遗传学说,并称之为“泛生子假说”。该遗传理论认为生物体的各种性状都有独立、可分的颗粒基础——泛生子。同时,达尔相信融合性遗传,即父母的遗传因素在后代中是混合起来,不再分开。但是泛生子的存在并没有任何事实根据。     

达尔文主义的新天地

1882年,达尔文临死前心满意足地看到了他的两个思想产儿之一——共同祖先学说已获得了生物学界的公认,已难以找到生物学家还会怀疑进化的事实。但是他更心爱的另一个思想产儿——自然选择学说却遭遇不同的命运,只吸引了少数追随者。它面临的一些科学难题在当时没有令人满意的解答,而它的思想含义——那种机械的、看上     

对自然选择的再认识

对自然选择的再认识＠阎锡海对自然选择的再认识阎锡海尽管举世公认,达尔文是一位可以与被誉为近代科学巨匠的牛顿相媲美的著名生物学家,他在１９世纪中期所创立的以自然选择为核心的生物进化理论,被视为２０世纪以前生物学领域最为辉煌的成就,但是它同其它科学一样,是一定...     

遗传学对进化论的推动

遗传学起自于孟德尔的豌豆杂交试验,他于1866年发表论文<植物杂交试验>并曾经把文章寄给达尔文,但由于他思想的超前性和当时社会正处于进化理论的大讨论中,孟德尔的工作并没有得到太多的重视.     

被误解的命运：从达尔文理论到达尔文主义

1859年,达尔文发表了《物种起源》一书,系统地阐述了进化论思想。在书的结尾,他写下了一句意味深长的话：“人类的起源和历史也将由此得到许多启示。”然而,一百年后的1959年,美国著名遗传学家H．J．穆勒在纪念《物种起源》发表100周年大会上与另一位知名学者却发出不约而同的感慨：“这一百年来没有达尔文也是一样的。”     

我多组学关联分析揭示表观等位基因在拟南芥环境适应性进化中的作用及机制

表观等位基因一般是指仅由DNA甲基化差异引起的表达量不同的等位基因,对植物形态结构和各种生理过程具有重要影响。但自然条件下环境因素对植物表观等位基因的影响还不清楚,同时表观等位基因在植物环境适应性进化中的作用和机制还亟待探究。为了在全基组水平鉴定拟南芥(Arabidopsis thaliana)中与特定环境因素相关的表观等位基因,并分析它们参与拟南芥环境适应性进化的可能机制,本研究利用623株拟南芥生态型的转录组、甲基化组和种源地气候数据进行多组学关联分析,并同时进行了蛋白互作网络和基因富集分析。以春季和夏季降水量为例,本研究最终鉴定到5个基因(AGL36、AT2G34100、AT4G09360、LSU4和AT5G56910)可能具有相应的表观等位基因,基因内部或附近特定区域不同甲基化水平对它们的表达可能具有调控作用。其中与种子发育有关的印记基因AGL36首次被发现可能作为表观等位基因参与拟南芥环境适应性进化,其他4个基因均与生物胁迫响应有关。自然条件下降水量能影响当地病虫害的严重程度,而DNA甲基化能通过影响这4个免疫基因的表达来影响拟南芥免疫能力。在长期演化过程中有利于个体适应当地降水模式的表观等位基因受到正向选择,这可能是这些表观等位基因参与拟南芥降水适应性进化的潜在机制。通过蛋白互作网络、GO功能分析和KEGG通路分析,本研究还首次发现LSU4可能与LSU基因家族其他成员一样参与硫代谢网络,并通过影响硫代葡萄糖苷代谢参与拟南芥生物胁迫响应。     

表观遗传学在长期进化中的作用可能十分有限

拉马克曾提出,环境条件对物种的变化起主导作用,而因环境条件影响所获取的新性状可以遗传给后代.然而当达尔文的进化论发表以后,这一理论也就趋于没落.近十年的研究表明,环境的确可以影响动物或     

MicroRNA对胃癌调控作用的研究进展

微小RNA(microRNA, miRNA)是一类源于真核生物自身基因组的非编码小RNA,参与了肿瘤发生的多个阶段,通过直接靶向抑制其下游靶mRNA的表达或利用其竞争性内源RNA(如lncRNA)间接调控靶基因的表达,在癌症进程中发挥促癌或抑癌作用。胃癌是一种常见的高发病率、高转移率、高侵袭率和高死亡率的恶性肿瘤,大量研究表明,胃癌细胞的恶性生物学行为、表观遗传学改变和化疗耐药性等均与miRNAs的异常表达密切相关。特别注意的是,外泌体源性miRNAs通过外泌体的包装及运载,在细胞之间或细胞与微环境之间传递,也是胃癌进展中必不可少的一环。本文重点概述了miRNAs通过不同信号通路及调控机制在胃癌恶性增殖、凋亡、侵袭、转移、DNA甲基化和化疗耐药等方面的作用,针对miRNAs作用机制的研究可能为胃癌的诊断与治疗提供新见解。     

The molecular and mathematical basis of Waddington's epigenetic landscape: A framework for post‐Darwinian biology?

The Neo-Darwinian concept of natural selection is plausible when one assumes a straightforward causation of phenotype by genotype. However, such simple 1:1 mapping must now give place to the modern concepts of gene regulatory networks and gene expression noise. Both can, in the absence of genetic mutations, jointly generate a diversity of inheritable randomly occupied phenotypic states that could also serve as a substrate for natural selection. This form of epigenetic dynamics challenges Neo-Darwinism. It needs to incorporate the non-linear, stochastic dynamics of gene networks. A first step is to consider the mathematical correspondence between gene regulatory networks and Waddington's metaphoric 'epigenetic landscape', which actually represents the quasi-potential function of global network dynamics. It explains the coexistence of multiple stable phenotypes within one genotype. The landscape's topography with its attractors is shaped by evolution through mutational re-wiring of regulatory interactions - offering a link between genetic mutation and sudden, broad evolutionary changes.     

The Case of Paul Kammerer: Evolution and Experimentation in the Early 20th Century

To some, a misguided Lamarckian and a fraud, to others a martyr in the fight against Darwinism, the Viennese zoologist Paul Kammerer (1880–1926) remains one of the most controversial scientists of the early 20th century. Here his work is reconsidered in light of turn-of-the-century problems in evolutionary theory and experimental methodology, as seen from Kammerer’s perspective in Vienna. Kammerer emerges not as an opponent of Darwinism, but as one would-be modernizer of the 19th-century theory, which had included a role for the inheritance of acquired characteristics. Kammerer attempted a synthesis of Darwinism with genetics and the chromosome theory, while retaining the modifying effects of the environment as the main source of favorable variation, and he developed his program of experimentation to support it. Kammerer never had a regular university position, but worked at a private experimental laboratory, with sidelines as a teacher and a popular writer and lecturer. On the lecture circuit he held forth on the significance of his science for understanding and furthering cultural evolution and he satisfied his passion for the arts and performance. In his dual career as researcher and popularizer, he did not always follow academic convention. In the contentious and rapidly changing fields of heredity and evolution, some of his stances and practices, as well as his outsider status and part-Jewish background, aroused suspicion and set the stage for the scandal that ended his career and prompted his suicide.     

Revisiting the eclipse of Darwinism

The article sums up a number of points made by the author concerning the response to Darwinism in the late nineteenth and early twentieth centuries, and repeats the claim that a proper understanding of the theorys impact must take account of the extent to which what are now regarded as the key aspects of Darwins thinking were evaded by his immediate followers. Potential challenges to this position are described and responded to.     

Spontaneous mutations in bacteria: chance or necessity?

Several investigators have recently reported that significant numbers ofappropriately adapted mutants can be induced in bacterial and yeast strains by exposing stationary phase cells to specific environmental challenges. The resulting mutants are said to be both selection-induced and demonstrably non-random in origin; if this interpretation is correct, it is in direct conflict with the conventional neo-Darwinian view, which is that spontaneous mutants are truly random in origin and arise without the intervention of any overtly adaptive forces. We believe that there are alternative ways of accounting for the appearance of many (and probably all) of the additional mutants which proponents of the adaptive mutation theory claim are observed only after they applied the appropriate selective pressure. Having reviewed the available evidence, we consider that most (if not all) of the sorts of mutants which are said to have been induced following exposure of stationary-phase cells to intense selective pressure are equally likely to have been generated during the operation of certain well-known, conventional (and essentially random) cellular DNA repair processes. Evidence in support of our view can be found in the mainstream literature on the origins of spontaneous mutations. We also note that some of the molecular models which have recently been proposed to explain the production of selection-induced mutations preferentially (or even only) in genes of adaptive significance may turn out to be of considerable interest in their own right, even although the mutants whose origins they were intended to explain may turn out to have arisen in a manner which is totally independent of the conditions used for their selection.