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The concept of epigenetics has been known about since the 1940s, but it is only in the last 10 years that research has shown just how wide ranging its effects are. It is now a very widely-used term, but there is still a lot of confusion surrounding what it actually is and does.
Epigenetics is a new textbook that brings together the structure and machinery of epigenetic modification, how epigenetic modification controls cellular functions, and the evidence for the relationship between epigenetics and disease. It is a valuable source of information about all aspects of the subject for undergraduate students, graduate students, and professionals.
imprint endogenous genes has not been established. DNA methylation has not been reported for C. elegans, yet this species can apparently imprint a subset of transgenes during early embryogenesis. And in contrast with mammals and plants, in which DNA methylation is generally associated with gene inactivation, mealybugs show the opposite relationship between DNA methylation and gene activity. The inactive heterochromatinized paternal genome is hypomethylated relative to the active, hypermethylated
in the developing mouse embryo as a cluster of approximately 50 alkaline phosphatase-positive cells located in the extraembryonic mesoderm at the base of the allantois (Figure 11.7). PGCs are present in the hindgut epithelium of the 4-week human embryo and thereafter escape into the neighboring mesenchymal tissues to begin their migration via the dorsal mesentery to the developing gonads, where they arrive at approximately week 6 of gestation. In both mouse and human, the early gonads are
Transcription-factor-binding sites on the 5 region of DNMT1. The line at the top of the diagram shows the density of CG bases across the 5 -control sequences of the gene relative to the positions of control elements in the physical map of the region. The position of putative binding sites for the transcription factors AP-1 and E2F, areas in which the retinoblastoma protein (Rb) represses gene activity, and regions that enhance gene activity through binding of the protein c-Jun are indicated.
the N-terminal tails is central to the whole business of genome control by histone modification, and Figure 6.1 shows the amino acid sequences of these crucial structures and the types of covalent modification to which they are subject. Even at a most fundamental level, a plethora of different post-translational modifications correlate with regions of silenced or transcriptionally active chromatin. There is substantial evidence that the primary mechanism by which many specific post-translational
polypeptide-encoding regions. Promoters are often located quite close to the DNA base pairs that comprise the first codon of the coding sequence (the transcription start site), but this does not always apply, and we also see some genes that have promoter elements located at considerable distances from the transcription start site. In eukaryotes, there are often several regions of DNA in or near the promoters whose function is to regulate the rate of transcription up or down, or to stop it