Clones are known to have an almost identical genome to the nuclear transfer cloning donor, but clones often exhibit phenotypic differences that distinguish them from the donor. One of the main reasons for phenotypic differences is therefore not genetic, but lies in epigenetics, specifically in DNA methylation. This changes the activation of the non-coding part of the genome without changing the DNA sequence. Environmental factors can affect the change in the methylation pattern of DNA, whereby DNA methyltransferase cleaves methyl groups from DNA. As a result, there is inactivation or changes in the expression of genes, which in turn affects the phenotype of the individual. Cloned individuals created by nuclear transfer are particularly important in epigenetic research, as they can be exposed to different environments after birth and the impact of different environmental factors on the same genome can be compared. Therefore, cloning by nuclear transfer is a crucial model for studying the influence of environment on phenotype.
|
