Retains eight IGS repeats.
Construct: bb fragment carrying the promoter proximal region of the intergenic spacer (IGS) and all of the external transcribed sequences (ETS), completely lacks 18S.
Improves male fertility but not recovery of reciprocal products from Df(1)X-1/Dp(1;Y)BSYy+ males.
Heterozygotes with Dp(1;Y)BSYy+ display no stimulation of X-Y disjunction in adult testes when recombined with Df(1)X-1, in genetic and cytological assays.