Epigenetic Processes as Evolutionary Advanced Molecular Mechanisms to Cope with the Continuous Interaction Between DNA and the Environment

Abstract

The traditional concept that the phenotype of an organism is the resultant of the genetic code and the influence from the environment has recently acquired implications not previously suspected. Evidence has been accumulating showing that the once thought “static” interaction between gene coded information and its final gene expression has revealed as a complex dynamic process that continually updates in time. These processes are known as epigenetic mechanisms, where a heritable change in a gene expression is produced without modifications in the primary DNA structure. Diverse functional strategies have been evolved in evolution dealing the existence of double content of DNA information or lack of allele gene information, such as the case of sexual chromosomes represented by the unequal X and Y partners. Processes such as the gene dosage compensation, gene imprinting and the functional role of metastable epialleles, are just a few of the many complex expressions of epigenetic mechanisms. In this review these processes are discussed under the perspective of evolution, intending to show that they are “flexible” solutions to cover problems arising from the continuous interaction of DNA and the environment. Finally, these concepts are applied to the HSR gene expression where evidence from a study of our laboratory working in children of the province of La Rioja (Argentina) has showed that environmental factors can apparently modify the phenotypic attributable expression to this gene.