Identifier

etd-04132009-162140

Degree

Doctor of Philosophy (PhD)

Department

Biological Sciences

Document Type

Dissertation

Abstract

Gene expression is regulated by the chromatin environment and various cis-regulatory elements. Gene activators and repressors target specific regulatory elements in the genome to regulate nearby genes. But they function only in limited regions called domains. In each domain, genes are regulated independently without interference from outside. Boundary elements (insulators), binding sites for insulator proteins, are proposed to separate neighboring domains. One function of insulators is to block interactions between an enhancer and a promoter if positioned between them; the second function is to block the spreading of certain chromatin states along chromatin. BEAF-32 (with two 32 kDa variants: BEAF-32A and BEAF-32B) is one of insulator proteins. The binding of BEAF at the insulator scs’, which was originally found at the edge of 87A heat shock puff on Drosophila polytene chromosome, is essential for the insulator activities. We examined the heat shock induced histone modifications at the region of the transgenic heat shock puff, and studied if the presence of a nearby 2scs’ insulator can block these modifications from further spreading. On immunostaining Drosophila polytene chromosomes, hundreds of regions are seen to be associated with BEAF. To map BEAF binding sites in the Drosophila genome, we hybridized 32A and 32B ChIP DNA to genome-tiling microarrays. Different binding characteristics were observed for 32A and 32B. Nearly 2000 BEAF binding regions were identified. Most of these sites are located at gene promoters, and analysis of these target genes reveals a link between BEAF and gene expression.

Date

2009

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Craig M. Hart

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