Figure 1.

Ethyl methanesulfonate (EMS) mutagenesis screen for new su(Hw) mutants. Males homozygous for a third chromosome marked with a yellow (y)⁺, white⁺(w)⁺ P-element (P[y⁺, w⁺]¹⁵⁵⁹⁸) were fed EMS and were mated to females carrying the third chromosome balancer TM6B, Tb. F1 males were selected that carried the mutagenized third chromosome (P[y⁺, w⁺]¹⁵⁵⁹⁸*) and the TM6B, Tb balancer chromosome. These males were mated to virgin females carrying the multiply marked X-chromosome with three gypsy-induced mutations (y², ct⁶, f¹) and a su(Hw) null allele carried with the TM6B, Tb balancer. The non-Tb F2 male progeny were screened for reversal of the gypsy-induced mutations and the non-Tb F2 female progeny were screened for infertility. If either outcome was obtained, then P[y⁺, w⁺]¹⁵⁵⁹⁸*/ TM6B, Tb males and females were crossed to establish a stock. Of more than 8000 chromosomes screened, 52 putative su(Hw) alleles were identified in the F2 generation. Four stocks were generated with confirmed su(Hw) mutations.