Subject: CyO, sp* balancer variant Subject: CyO, sp* balancer variant We received stocks from Ting Wu, Harvard University, balanced over a CyO chromosome marked with an unknown allele of speck. The allele is probably sp1 rather than a spontaneous sp allele, because the sp-marked CyO was recognized in stocks where the nonbalancer homologue was marked with sp1. It likely recombined onto CyO, since sp is distal to the most distal CyO breakpoint.