Chinmo is the larval member of the molecular trinity that directs Drosophila metamorphosis

Significance The genome of insects with complete metamorphosis contains the instructions for making three distinct body forms, that of the larva, of the pupa, and of the adult. However, the molecular mechanisms by which each gene set is called forth and stably expressed are poorly understood. A half century ago, it was proposed that there was a set of three master genes that inhibited each other’s expression and enabled the expression of genes for each respective stage. We show that the transcription factor chinmo is essential for maintaining the larval stage in Drosophila , and with two other regulatory genes, broad and E93 , makes up the trinity of mutually repressive master genes that underlie insect metamorphosis.