Friedman T B, Johnson D H
Science. 1977 Jul 29;197(4302):477-9. doi: 10.1126/science.406675.
The appearance of urate oxidase activity in the Malpighian tubules of Drosophlia melanogaster is synchronized with the time of emergence of the imago from the puparium. A developmental clock within the Malpighian tubules specifies the time of appearances of urate oxidase activity.