Flies indistinguishable from wild type. Testis colour: yellow-orange, but not dependable for classification. Causes striking changes in compounds that fluoresce in ultraviolet light on paper chromatograms of testes. Isoxanthopterin content of testis sheath greatly reduced. A blue fluorescent compound not otherwise detected in D.melanogaster (the "lix" substance) is present. Drosopterins present in the testis sheath and quantities of sepiapteridine, biopterin, "Compound A," and a "riboflavin-like" compound are elevated. The colored pteridine gives testis sheath its darker color. Pteridine accumulation in testis sheath alone is affected. RK3.