Retains eight IGS repeats.
Deletion derivative that retains a segment of the 5' and 3' intergenic spacer (IGS) but deletes the bb transcription unit.
Improves recovery of reciprocal products from Df(1)X-1/Dp(1;Y)BSYy+ males as well as male fertility. Increases fertility of Df(1)X-1; T(Y;2)B80 from 0 to 9.1%.