TRANSMISSION PATTERN OF HOBO TRANSPOSABLE ELEMENT IN TRANSGENIC LINESOF DROSOPHILA-MELANOGASTER

This study is an attempt to trace the fate of hobo elements in the gen omes of E strains of Drosophila melanogaster that have been transfecte d with pHFL1, a plasmid containing an autonomous hobo. Such long-term population studies (over 105 generations) could be very useful for bet ter understanding the population and genomic dynamics of transposable elements and their pattern of insertions. Molecular analyses of hobo e lements in the transfected lines were performed using Southern blots o f XhoI-digested genomic DNAs, The complete element was observed in all six injected lines. In two lines we observed, at generation 100, two deleted elements, which did not correspond to Th1 and Th2. The results obtained by the in situ method show that the number of hybridization sites increases in each line and prove that the hobo element may be am plified in an RM genome. The hobo activity does not seem to be systema tically correlated with the number of hobo elements. After generation 85, the evolution of the hobo element's insertion site number depends on the injected line. In all lines, the total number of insertions rem ains quite small, between 0 and 11. Hobo elements are located on each of the chromosomal arms. We describe 'hotspots' - insertion sites pres ent in all lines and in all generations. On the 3R arm, a short invers ion appeared once at generation 85.