David Penny
Epigenetic mechanisms are increasingly being accepted as an integral part of normal science. Earlier genetic studies appear to have assumed that the only changes were ‘mutations’ as a result of a change in the DNA sequence. If any such changes altered the amino acid sequences then it was effectively a mutation, and if it occurred in a germline cell (including in unicellular organisms) then it could be passed on to subsequent generations. However, it is increasingly apparent that other changes are also important, for example, changes to methylation patterns, and to the histone proteins. Epigenetics was sometimes consider ‘additional’ to classical genetics, but it is still fully dependent on DNA, RNA and protein sequences, and at least since [1] it has been considered a part of normal science. A richer way is to expand classical genetics to include transfer of information between cellular generations. Indeed, it is hard to imagine a unicellular protist that does not modify some of its protein expression levels as a result of environmental changes-gene regulation is integral to biology.
