Retains ten IGS repeats.
Deletion derivative that deletes part (28S and 5.8S rDNA) of the bb transcription unit.
An X-linked copy of P{rib7.HJ+B} results in a significant decrease in the percentage of sex chromosome nondisjunction in T(1;4)mscd1 males. An X-linked copy of P{rib7.HJ+B} has no significant effect on the percentage of sex chromosome nondisjunction in T(1;4)mscd2 males.
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 70.2%.