Some derivatives of TM6 carry a suppressor of SD activity, (see also FBrf0044429).
Homozygous lethal. Suppresses crossing over in chromosome 3. Has unbroken regions with genetic lengths of approximately 10, 15, 20 and 30 units. UbxP15 listed (in error) as "Ubx67b" in Lindsley and Grell, (FBrf0063385).