Epigenetic: reading between the lines of the genetic code

Abstract

The concept of epigenetics has evolved since Waddington defined it as the study of the causal mechanisms operating in embryogenesis. Although it is possible to draw a typology of meanings through its conceptual history, epigenetics has gradually changed the approach to the biological problems related to development towards the problems associated with the evo-devo. Thus, the classic opposition between epigenesis and preformation as ways of understanding embryogenesis, is part of the history of epigenetics and has contributed to its current significancee. At present, it is considered that
epigenetic states and epigenetic regulation refer to situations in which the various levels of genetic expression can coexist in similar environmental conditions without significant changes in the genomic sequence. The modulation of the epigenetic mechanisms allows, by definition, the alteration of cell phenotype without altering the genotype. There are numerous epigenetic mechanisms of control: methylation and acetylation of histones, incorporation of histone variants, remodeling of nucleosomes, DNA methylation, chromatin organization of higher order, chromosomal interactions and the cell nucleus influence in the spatial organization of chromatin. Altogether, these additional signals contribute to the
dynamic remodeling of chromatin under different development options. Although all genetic information is written in the DNA as a four-character code, epigenetics describes the art of reading between the lines.