Ecdysoneless Homolog (ECD)

Ecd encodes an as yet functionally undescribed protein that is conserved throughout eukaryotes. The ecd conditional allele contains an amino acid substitution, whereas three non-conditional larval lethal mutations result in truncated Ecd proteins. Ecd is expressed in the ecdysone-producing larval ring gland. However, development of ecd-null early larval lethal mutants cannot be advanced by Ecd expression targeted to the ring gland or by hormone feeding. Cell-autonomous ecd function, suggested by these experiments, is evidenced by the inability of ecd clones to survive within developing imaginal discs. Ecd is also expressed in the ovary, and is required in both the follicle cells and the germline for oocyte development. These defects, induced by the loss of ecd, provide the first direct evidence for a cell-autonomous function of this evolutionarily conserved protein.