摘要： 本文综述外因遗传学的提出、发展的各个主要阶段和该学科的确立。基因特性可以从两个层面来进行研究，（1）是遗传物质的传递，（2）是从基因型到表型这个过程。外因遗传学从1942年沃丁顿提出，经1987年霍利迪的发展，到现今在各类生物包括人类中积累了丰富的资料，并能够用化学分子来说明其作用机理。外因遗传学现代的定义为：基因功能的改变,凡未牵涉到DNA的序列，又可通过细胞的有丝或减数分裂而遗传者，称为外因遗传。作者介绍了外因遗传的范围，如：X染色体剂量补偿、基因组印记、分化细胞的基因组重新编程、癌基因、转录的分子调节、RNA介导的基因沉默、组蛋白码、着丝粒的遗传和进化以及外因遗传的进化。此外，还有科学界的反应和评价，包括其在人类生物学和医学方面的重要性和该理论的重大的意义。组蛋白码不同于DNA码，DNA码需要精确拷贝，而且是静止的；而外因遗传就不是如此之僵硬，而具有一定的弹性，因为组蛋白码是决定于其上下文的,可在不同场景下组合成不同的码,它是为其他的蛋白质所读的。遗传需要稳定性,也需要根据内因和外因的变化而有灵活性,DNA码和组蛋白码相辅相成,对复杂的生物是必备的。
The Meaning of Epigenetics
HU Kai
The Tropical Biology Center,Hainan University,Haikou,Hainan 570028,China
Abstract:Epigenetics,the term was introduced by Conrad H.Waddington,in 1942,he said that to compare genetics with epigenetics,the study of the processes by which genotype gives rise to phenotype.In 1987,Robin Holliday redefined epigenetic as “Nuclear inheritance which is not based on differences in DNA sequence”.The author of this paper introduced that in Science,10 August 2001,there was a special collection of review articles focused on the topic of epigenetics.The new “histone code” hypothesis states that the highly modifiable amino termini could carry their own combinatorial codes to help control phenotype,and that part of this code is heritable.And in light of this hypothesis,researchers are approaching further possibilities in human biology and types of cancer and other diseases.
Key words：epigenetics; gene expressing

关键词: 基因的表达, 外因遗传学