Regulated Synthesis and Role of DNA Methyltransferase During Meiosis
In mammals, the methylation of cytosine residues in DNA is postulated to be involved in a number of processes including gene regulation, development, X-chromosome inactivation, genomic imprinting, and carcinogenesis. Sex- and sequence-specific patterns of DNA methylation are established in the germ line (1–3) and further modified during embryogenesis. The chemical modification of genes by DNA methylation provides a way in which genes can be turned on or off at specific times. Overall, the sperm genome is more methylated than that of the oocyte (4). Methylation of DNA is one of the major candidates proposed to mark the mother’s and father’s genes differently, in the process of genomic imprinting, which is also initiated in the germ line (5, 6). Our objectives are to determine the mechanisms by which DNA methylation patterns are established during spermatogenesis and the impact on the early embryo of disrupting DNA methylation in male germ cells. Our results to date indicate that DNA methylation is highly regulated in the germ line (1, 7–10) and suggest that decreases in DNA methylation in male germ cells result in alterations in sperm production and abnormalities in early embryo development (11).
KeywordsGerm Line Male Germ Cell Pachytene Spermatocyte Early Embryo Development Seminiferous Epithelium Cycle
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