ABSTRACT
DNA methylation is catalyzed by a family of DNA methyltransferases (DNMTs) that transfer a methyl group from S-adenyl methionine (SAM) to the fifth carbon of a cytosine residue to form 5mC. DNA methylation affects the interaction between the histone and DNA, which changes the chromosome structure and has reverse relationship with gene expression in general. Up to now, more and more studies have confirmed that environmental factors can alter epigenetic modifications, which do not involve in changing DNA sequence. So it can explain the phenotype of creature in a certain degree. This article focused on the influence of environmental factors, such as temperature, nutrient supply, heavy metal, early stress and radiation, on DNA methylation change. As a matter of fact, it does not only change the DNA methylation in parents and offspring but also their behavior and phenotype. Overall, this review will help us get better understanding of the relationship between environmental factors and gene expression regulation.