Epigenetic inheritance refers to the inheritance of phenotypes that cannot be explained by DNA sequence or the environment. Despite research into the transmission of these traits in recent years, it is not yet known how epigenetic traits are inherited. One hypothesis, which was investigated by Martin and Zhang (2007), is that the pattern of DNA and histone methylation provides the means of epigenetic inheritance. Histones are proteins that package DNA, allowing it to fit inside the cell. Methylation involves the addition of a chemical known as a methyl group to the DNA strand. Previous research has shown that when histone proteins are modified it can lead to activation or silencing of some genes.
Martin and Zhang (2007) investigated the hypothesis that methylation patterns of histones are passed on during DNA replication. While there is no proof of how this occurs, it is believed that the method of histone replication is semi-conservative. This means that the histone proteins split in two, and half remains bound to each strand of DNA. The other half is then reformed, resulting in two histone proteins. It is also believed that modifications to histones are also transmitted during replication. These modifications include patterns of histone methylation, which would provide a method of inheritance of epigenetic traits. Martin and Zhang (2007) provide a detailed study of this phenomenon.
By Lauren Wilson
Student Number: 41208238
Reference
Martin, C. & Zhang, Y. 2007, ‘Mechanisms of epigenetic inheritance’, Current Opinion in Cell Biology, vol. 19, pp. 266-272.
