Advancing Epigenetics Towards Systems Biology 21

Definition of Epigenetics

Conrad Waddington (1905-1975) is often credited with coining the term epigenetics in 1942 as “the branch of biology which studies the causal interactions between genes and their products, which bring the phenotype into being”. Epigenetics appears in the literature as far back as the mid 19th century, although the conceptual origins date back to Aristotle (384-322 BC). He believed in epigenesis: the development of individual organic form from the unformed. This controversial view was the main argument against our having developed from miniscule fully-formed bodies. Even today the extent to which we are preprogrammed versus environmentally shaped awaits universal consensus. The field of epigenetics has emerged to bridge the gap between nature and nurture. In the 21st century you will most commonly find epigenetics defined as ‘the study of heritable changes in genome function that occur without a change in DNA sequence'. But what do the scientists that work in this rapidly expanding research field have to say?

Brona McVittie reports :: June 2006

“Epigenetics has always been all the weird and wonderful things that can't be explained by genetics.”
Denise Barlow (Vienna, Austria)

“DNA is just a tape carrying information, and a tape is no good without a player. Epigenetics is about the tape player.”
Bryan Turner (Birmingham, UK)

“I would take a picture of a computer and say that the hard disk is like DNA, and then the programmes are like the epigenome. You can access certain information from the hard disk using the programmes on the computer. But there are certain password protected areas and those which are open. I would say we're trying to understand why there are passwords for certain regions and why other regions are open.”
Jörn Walter (Saarland, Germany)

“There is around 2m of DNA in a nucleus of only a few micrometers. We are trying to learn about the mechanisms whereby the DNA gets accessed given the tiny volume of the nucleus.”
Gunter Reuter (Halle, Germany)

“Information management in the nucleus means that some of the genetic information is very very tightly packaged in the genome. Then there is genetic information that has to be on and active all the time, house-keeping genes for example. So epigenetics is a bit like information management at home, something that you need all the time you will not store away, but your old school records you keep packed in boxes in the attic.”
Peter Becker (Munich, Germany)

“The difference between genetics and epigenetics can probably be compared to the difference between writing and reading a book. Once a book is written, the text (the genes or DNA: stored information) will be the same in all the copies distributed to the interested audience. However, each individual reader of a given book may interpret the story slightly differently, with varying emotions and projections as they continue to unfold the chapters. In a very similar manner, epigenetics would allow different interpretations of a fixed template (the book or genetic code) and result in different read-outs, dependent upon the variable conditions under which this template is interrogated.”
Thomas Jenuwein (Vienna, Austria)


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