Mosaic analysis of lethal mutations in Drosophila.

The effects of various lethal mutations were studied when they were present in the hemizygous state as sectors in genetic mosaics (gynandromorphs) of Drosophila melanogaster. Sixty percent of the lethals studied can survive to adulthood in combination with normal tissue in mosaics, whereas the remainder cause the death of such mosaic animals. Some of the gynandromorph-viable lethals appeared to be locally active, in that they allowed the survival of only those mosaics in which the male tissue was present in the abdomen. The regions affected by these lethals were identified more precisely by analysis of the tissue distributions in the surviving gynandromorphs.