The X and 4th chromosome nondisjunction defects seen in FM7/X females heterozygous for Df(3L)66C-T2-10 are largely rescued by expression of mtrmS137A.Scer\UAS.T:Zzzz\FLAG under the control of Scer\GAL4nos.UTR.T:Hsim\VP16 (nondisjunction rates are 3.5% and 4.3% respectively in the rescued flies, compared to 0.9% and 0.9% in controls).