Theory Biosci. (2000) 119: 187-208.
The Organism: A Crucial Genomic Context in Molecular
Epigenetics?
Linda Van Speybroeck
Key words:
epigenesis, epigenetics, chromatin structure, gene-centrism, genomic context,
organism, Developmental Systems Theory.
Summary:
Whereas genetics refers to the study and mapping of linear nucleotide sequences, their
mutations and inheritance, epigenetics refers to the structural organization and
evolution of the genome. Epigenetic studies indicate that not all heritable information
leading to the phenotype is “inscribed” in the DNA base sequence. In this sense,
epigenetics – as the term indicates – goes beyond genetics, thereby (1) leaving behind
the gene-centered view from within molecular biology itself, and (2) urging biophilosophers to change their focus from criticizing the central dogma to evaluating
new developments in molecular research.
In the epigenetic approach, a hierarchy of genomic contexts can be revealed,
consisting basically of an intracellular, an intercellular, and an organismic level. The
first explorations on the organismic level suggest that under certain conditions the
somatic constitution of the organism and how it stands in close interaction with its
environment are to be taken into account as factors influencing the genomic
constitution. Depending on the specificity of these conditions, the organism and its
history and actuality can be seen as a crucial genomic context – leading to a more
complex perception of the local dynamics and the structure of the genome and its
consequences for development and evolution.
This “organism in the world” view fits well with the philosophical tradition of
Developmental Systems Theory, although epigeneticists seek to enlarge the genetic
picture of biology by gradually expanding the range of molecular processes which
influence the genome, thereby decentralizing the sovereign role of the genome,
without loosing track of experimental demands.