The object of our investigation was an inbred LA strain of Drosophila melanogaster. This strain was selected during more than 700 generations for low male mating activity and was characterized by complex abnormalities and the remarkably high level of spontaneous mutability. The last property is determined by hobo-system of hybrid dysgenesis. LA strain's hobo-activity potential in H-E system of hybrid dysgenesis comprise 30-40%. It may be drastically increased up to 70-80% through LA-strain chromosome isogenization in dysgenic crosses. In genomes of independent isogenic LA substrains, numerous directional transpositions of hobo-element take place. In spite of it, the retention of hobo-element insertion sites inherent in original LA persist. The obtained data open up a new possibilities to study the genome instability mechanisms.