[The study of insertion sequence on IS2. I. Polarity and inserted direction of IS2]

By using flj B, flj A selecting system, we investigated the effects of the insertion of IS2 into certain genes and found that IS2 could be inserted into the gene from either the left side or the right side resulting in the loss of its activity and inhibition of the next gene's expression within the same transcription. The polarities were different when IS2 was inserted from the left side or the right side. The results from the artificial testing system were the same as those obtained from the natural state.