The Almost-Forgotten Fifth Nucleotide in DNA: An Introduction -- Pattern Formation -- Replication and Translation of Epigenetic Information -- DNA Methyltransferases: Facts, Clues, Mysteries -- DNA Methylation in Plants -- Determinant of Promoter Activity -- De Novo Methylation, Long-Term Promoter Silencing, Methylation Patterns in the Human Genome, and Consequences of Foreign DNA Insertion -- DNA Methyltransferases -- Establishment and Maintenance of DNA Methylation Patterns in Mammals -- Molecular Enzymology of Mammalian DNA Methyltransferases -- Epigenetic Phenomena -- Familial Hydatidiform Molar Pregnancy: The Germline Imprinting Defect Hypothesis? -- Dual Inheritance -- Mutagenesis and Repair -- Mutagenesis at Methylated CpG Sequences -- Cytosine Methylation and DNA Repair.