Fig. 1.

Genotypes for overexpression and control levels of superoxide dismutase (SOD). (a) Genotype of UAS-HS control and overexpression flies obtained from Parkes et al. (1998) containing two P-elements. The P(w+)UAS-hSOD1 insert on the second chromosome carries a GAL4-sensitive upstream activating sequence and a human SOD1 gene. On the third chromosome, P[GAL4] is expressed only in adult motorneurones, thereby activating expression of the hSOD1 gene. (b) The UAS-HS overexpression strain used at UGA was homozygous for the hSOD1 P-element. The third chromosome carries GAL4 and a null mutation (X³⁹) at the Drosophila SOD locus; it is balanced to prevent recombination. The control strain lacks GAL4. (c) Experimental strains result from a cross between UAS-HS males from b and females from 10 recently wild-caught, inbred isofemale strains. Here, + represents wild-caught wild-type alleles. The first three chromosomes of D. melanogaster are shown. Male genotypes are given in a and b; female genotypes are given in c. Numbers on the right represent the number of Drosophila SOD and human SOD alleles being expressed for each genotype. w = white, P = P-element, + = wild-type.