PYRIMIDINE AUXOTROPHY AND COMPLEMENTATION MAP OF RUDIMENTARY LOCUS OF DROSOPHILA-MELANOGASTER

The complementation pattern of 12 rudimentary mutations was analyzed at 2 different levels. When analyzed on the basis of complementation for a wing abnormality the mutations can be divided into 3 groups, each of which is believed to affect the activity of 1 of the first 3 enzymes of pyrimidine synthesis. However, when the mutants are analyzed for complementation on the basis of a 2nd phenotype, pyrimidine auxotrophy, the distinction between 2 of these 3 groups is not evident. The disparity in the 2 patterns probably reflects a different threshold of gene activity required for the detection of an auxotrophic phenotype as compared to that at which a wing abnormality is detectable. At least the first 2 enzymes of pyrimidine synthesis are contained within a single multifunctional protein complex.