Single exchange generates highly unstable single ring chromosomes as seen by very low recovery of ring-bearing daughters and by 16-46% gynandromorphs among single-ring-bearing progeny. Single rings apparently deficient for proximal euchromatic material, as they are Male lethal in combination with a normal Y but survive in combination with BSY or su(f)+Y.
C(1)TM5, YSIn(1)EN.+; originally y w v B KS . y