Abstract
Specific sequences are designated for de novo DNA methylation at CpG dinucleotides in mammalian germ cells. The result is the long-term transcriptional silencing of the methylated sequences, most of which are retrotransposons and CpG-rich sequences associated with imprinted genes. There is profound sexual dimorphism in both the nature of the sequences that undergo de novo methylation in germ cells and in the mechanism by which de novo methylation is regulated. The restriction of future gene expression by the imposition of heritable methylation patterns in germ cell genomes is characteristic of mammals but is rare in other taxa.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Review
MeSH terms
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Animals
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DNA (Cytosine-5-)-Methyltransferases / genetics
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DNA (Cytosine-5-)-Methyltransferases / metabolism
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DNA Methylation*
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Dinucleoside Phosphates / metabolism
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Epigenesis, Genetic*
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Female
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Gene Silencing
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Genomic Imprinting
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Germ Cells / cytology
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Germ Cells / metabolism*
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Male
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Mammals / genetics*
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Oocytes / cytology
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Oocytes / metabolism
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RNA Interference
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Sex Characteristics
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Spermatogonia / cytology
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Spermatogonia / metabolism
Substances
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Dinucleoside Phosphates
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cytidylyl-3'-5'-guanosine
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DNA (Cytosine-5-)-Methyltransferases