The transposable hobo element plays the role as a causative agent to produce chromosome rearrangements in the Uc-1 X chromosome. In the present study, the Notch mutation rate in an inbred Uc-1 strain ranged between a low value of 3.52±0.74 percent to a high one of 6.25±1.13 percent. Cytological analysis revealed 82 deficiencies and three different inversions, associated with the Notch mutations. And in situ hybridization showed that the hobo elements were participated in all of the chromosome mutations which had labels with the hobo probe at each of the breakpoints. This result suggested that hobo existing in the Notch locus interacts with the other hobo elements on the same chromosome to produce the structural rearrangements.