The Changing Concept of Epigenetics

Abstract

We discuss the changing use of epigenetics, a term coined by Conrad Waddington in the 1940s, and how the epigenetic approach to development differs from the genetic approach. Originally, epigenetics referred to the study of the way genes and their products bring the phenotype into being. Today, it is primarily concerned with the mechanisms through which cells become committed to a particular form or function and through which that functional or structural state is then transmitted in cell lineages. We argue that modern epigenetics is important not only because it has practical significance for medicine, agriculture, and species conservation, but also because it has implications for the way in which we should view heredity and evolution. In particular, recognizing that there are epigenetic inheritance systems through which non‐DNA variations can be transmitted in cell and organismal lineages broadens the concept of heredity and challenges the widely accepted gene‐centered neo‐Darwinian version of Darwinism.

Quelle place pour l’épigénétique ?

“…On peut déconstruire à plaisir le gène: cela ne peut faire oublier que les structures et les fonctions des êtres vivants reposent sur les propriétés de macromolécules complexes, et que les organismes ont inventé un mécanisme sophistiqué et précis pour reproduire la structure primaire de celles-ci. En revanche, l'idée d'un programme génétique était une extension indue de ce méca-nisme de reproduction des constituants macromoléculaires à l'organisme entier: la notion de programme génétique ne subsiste plus aujourd'hui que sous la forme d'une vague métaphore 1 . Cela laisse beaucoup de place à l'épigénétique: à la possibilité que l'environnement modifie les caractéristiques des organismes vivants, et que ces modifications soient transmises au cours de générations.…”

“…Quelle en est la raison? Les premiers éléments de réponse se dégagent de l'étude des contextes historiques dans lesquels le terme a été créé: il a été introduit en effet deux fois [1]. Au début des années 1940, il est proposé par le généticien Conrad Waddington pour désigner une nouvelle science visant à étudier les mécanismes par lesquels le génotype engendre le phénotype [2].…”

Epigenetic Landscape of Parkinson's Disease: Emerging Role in Disease Mechanisms and Therapeutic Modalities

“…This constant repertoire of expression maintained throughout the lifespan above the basic regulation provided by the DNA sequence information constitutes the epigenome. Conrad Waddington in 1942 coined the term epigenetics and provided a basic definition: "the branch of biology which studies the causal interactions between genes and their products, which bring the phenotype into being" [3]. The recent interpretation of epigenetics involves all potentially heritable variations of gene expression without a change in DNA sequence [4].…”

Epigenetics and genetic determinism

“…Hoffmeyer and Emmeche (1991) proposed that the central feature of living systems is what they called their "code duality" ("the ability of the system to represent itself in two different codes, one digital and one analog"). "Every life form exists both as itself, i.e., as an organism of 'flesh and blood', and as a coded description of itself, the latter being lodged within the remarkable DNA molecules of which the genetic material is composed.…”