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Title: Nucleosome positioning on the chicken β-globin genes
Author: Edgar, Melanie
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2000
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This project identified the positions occupied by nucleosomes in vitro and in vivo throughout a region containing the reciprocally-expressed chicken globin genes, epsilon and beta-adult. The placement of individual nucleosomes on their promoters and shared enhancer influences local chromatin architecture which may in turn contribute to the regulation of these genes. In addition, periodicities detected in the long-range placement of nucleosomes may participate in the folding of long stretches of the chromatin fibre into an inactive higher order structure. Furthermore, as the in vitro map shows the distribution of nucleosomes as determined by the underlying DNA sequence, comparison of the in vitro and in vivo data would reveal the extent to which the DNA sequence of the globin genes determines their chromatin structure in active and inactive tissues. The monomer extension technique was used in vitro in both original (Yenidunya et al., 1994) and modified form (this study), to map DNA sequence-directed positioning throughout a 3.8 kb region encompassing the epsilon-globin gene. This map, juxtaposed with that for the beta-adult globin region (Davey et al., 1995) reveals the precise location and relative strength of nucleosome positioning sequences throughout 8 kb of continuous sequence. Indirect end-labelling was employed to map nucleosome positions in vivo, in chicken brain and adult chicken erythrocytes; in brain, the whole globin domain is inactive, and packaged into a repressed higher order structure; in adult erythrocytes, where the entire globin domain has adopted a more open, accessible chromatin structure, the beta-adult gene is in an active state and epsilon is silenced. Many of the strong in vitro nucleosome positioning sites, which exhibited a marked periodicity, were occupied in vivo in brain. This suggests that the DNA sequence of the globin genes creates a long-range chromatin structure which may be involved in folding the domain into the inactive, higher order chromatin fibre.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available