[Superunstable systems in Drosophila melanogaster: analysis of mutations in the ocelliless locus].

Six super-unstable mutations were obtained after crossing the M-cytotype strain of Drosophila melanogaster, where transpositions of the Stalker mobile element occur, with the pi 2 strain. One of these mutations appeared at the ocelliless locus. Detailed genetic analysis of this mutation and its numerous super-unstable derivatives was performed. Eleven allelic classes with different expression of the oc phenotype were isolated. The main features of super-instability at the ocelliless locus have been described and found to be common for all super-unstable systems obtained in our experiments. The role of the P element in the induction of super-instability is discussed.