9318934 Abstract Hobo is a transposable element found in the genome of Drosophila. In the X chromosome, the interaction of these elements has been found to result in chromosomal rearrangements. This hobo activity can be repressed by genetic factor(s) present in the genome of the Oregon R (OR) strain of fruit fly. This repression is complete and our data suggest that zygotic expression of either chromosomal genes or defective hobo elements, or a combination of those factors are responsible for the repression. The primary goal of this proposal is to identify and map these factors. A special genetic strain with 95 defective hobo elements has been isolated from the OR strain. The position of defective hobo elements in this strain divides the genome into about 100 cytological regions. Through genetic manipulations, the smallest number of regions that are associated with the repression of Uc-1 hobo activity will be identified. Cytogenetic analysis will be used to map the repression to a more precise section within each region. In addition, specially constructed plasmids will be introduced into the Uc-1 genome to test if antisense-hobo RNA can repress hobo activity. %%% Mapping a genetic function with defective transposable elements as genetic markers is simple in concept; however, it has not been attempted before. Our attempts to map the repressors of hobo activity will provide information about the usefulness and practicality of such an undertaking. It will also help us to understand the process of hobo-mediated chromosome restructuring. ***
