THE ISOLATION AND CHARACTERIZATION OF DROSOPHILA DNA SEQUENCES WHICH ARE CONSERVED THROUGHOUT EUKARYOTIC EVOLUTION
Abstract
The research presented in this thesis concerns the isolation and characterization of a simple, repetitive DNA sequence, poly d(TG) (.)poly d(CA) , in the Drosophila genome. This sequence is of great interest, because, unlike any other sequence identified to date, it is conserved in eukaryotes, deficient in prokaryotes, and has the ability to form Z-DNA. These sequences were isolated from a genomic library, as well as detected within large cloned regions of overlapping DNAs. They were found to be well dispersed in the Drosophila genome, and present preferentially in euchromatin although some sequences were detected in heterochromatin. They showed no preference for specific structural sites in polytene chromosomes. These sequences averaged 60 bp in length and were present in high frequency (2000 - 6000 copies/diploid genome). When the locations of these elements were mapped to transcribed regions of DNA, the majority were sited outside these regions. Results of Northern blot analysis and genomic cDNA library screening suggest that these elements are transcribed at a very low frequency (<0.1%). The function of these elements is not known, but their widely dispersed distribution and their potential to form Z-DNA suggests several potential roles, such as targeting recombination sites and/or influencing gene expression by affecting DNA conformation.
Degree
Ph.D.
Subject Area
Biology
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