Clonal Analysis in the Examination of Gene Function in Drosophila

Clonal analysis in Drosophila has been successfully used to address numerous biological questions of fundamental importance, including issues of cell lineage, fate determination, autonomy of gene action and pattern formation (1 , 2 ). Clonal analysis has been particularly useful for the study of genes that would be lethal in a homo-zygous mutant state; this approach also makes it possible to recover essential genes in mosaic screens (3 ).