The presence of uracil-DNA glycosylase in insects is dependent upon developmental complexity.

The metamorphosis of insects can, in a general way, be divided between those organisms that undergo pupation accompanied by cellular histolysis and those that gradually develop into adults without an intervening pupal stage of development. In the former case, the death of a cell population is an integral part of development that is tightly associated with massive DNA degradation during pupation. In that regard, it has been suggested that uracil-containing DNA acts as a target for the nucleolytic breakdown of DNA during histolysis in insects (Deutsch, W. A. (1987) Mutat. Res. 184, 209-215), thus placing into question how compatible the existence of uracil-DNA glycosylases would be for this form of developmental signal. As a result, we tested for the presence of a uracil-DNA glycosylase in insects representative of those having an intervening pupal stage of development and those that do not. We show here that a nonpupating insect contains a uracil-DNA glycosylase activity. Conversely, crude extracts of Drosophila melanogaster, as well as of three other insect populations that undergo pupation similar to that found in Drosophila, do not contain detectable levels of this DNA repair activity. Thus, there appears to be a consistent correlation between cellular destruction during development and the absence of a uracil-DNA glycosylase, which supports the possibility that uracil-containing DNA may play an important role in those cells targeted for death.