A further characterization of the cinnamon gene in Drosophila melanogaster

Summary

The X-linked, xanthine dehydrogenase (XDH) deficient cinnamon (cin, 1-0.0) eye color mutant of Drosophila melanogaster is a female sterile and as a result, cannot be maintained as a homozygous stock. Since the eye color of cin progeny from heterozygous females is maternally affected, genotypically cin flies have a wild type eye color. Supplementation of the culture medium with 0.02% allopurinol (4-hydroxypyrazolo (3,4-d), pyrimidine) (an XDH inhibitor) causes maternally affected cin flies to express a fully mutant eye color while it has no effect on the eye color of wild type flies. Using an allopurinol screening system we successfully induced two new alleles cin ³ and cin ⁴ with ethyl methane sulfonate (EMS). cin ³ is more severe than cin ⁴ and cin with respect to three cin phenotypes suggesting that cin and cin ⁴ are leaky. cin ³ mutants have no greater levels of XDH throughout development than do maternally affected ma-l flies while cin and cin ⁴ have higher XDH levels as late as the 96 h pupa. Using overlapping deficiencies and duplications, an unequivocal order of genes mapping at the tip of the X-chromosome (1-0.0) was obtained: l(1)J1, cin, arth, y, ac, sc and svr. Gynandromorphs marked with cin and y were employed to demonstrate that the action of cin ⁺ is non-autonomous. A selection scheme using a combination of allopurinol and purine which renders cin flies conditionally lethal is described.