Fig. 2. Linkage analysis of the headless mutation. (A) Primers used for mapping N. vitripennis (Nv) and N. giraulti (Ng) hunchback. Lowercase letters on the Ng-specific primer indicate sites of mismatch: a T/C SNP at the 3' end and a destabilizing mismatch four bases from the 3' end. (B) PCR controls with Nv and Ng genomic DNA demonstrating the efficacy of the Ng-specific primer. (C) Strategy for inter-specific cross to test linkage of Nv hunchback to headless. If hunchback is linked to headless then surviving hemizygous sons of the experimental F1 mothers should all have Ng hunchback.