Fig. 1.

Heterozyotes of null (DC0^B3/+) and strong (DC0^H2/+) DC0 mutations significantly improve memory retention, whereas heterozygotes of weaker DC0 alleles (DC0^B10/+ and DC0^H3/+) do not. The DC0^B3 mutation truncates PKAc by >50 aa, is genetically and phenotypically indistinguishable from deficiency lines lacking DC0, and is likely to be a null mutation in DC0. DC0^H2 is classified as a severe or strong DC0 mutation based on the early lethality of hemizyotes. DC0^H3, DC0^B10, and DC0^B12 (data not shown) are classified as medium and weak alleles based on complementation studies and the lethal phase of hemizygotes. Severity of alleles is based on classification by Lane and Kalderon (24). Note that the null allele improves memory to a greater extent than the strong allele, whereas the medium and weak alleles do not improve memory at all. n ≥6 for all data points. DC0^B3/+ and DC0^H2/+ curves show significant differences compared with wild type with respect to genotype, retention time, and interaction between genotype and retention time as analyzed by 2-way ANOVA (P < 0.003 in all cases). DC0^B10/+ and DC0^H3/+ curves show no significant differences from wild-type with respect to genotype. Bonferroni post hoc analyses indicate that DC0^B3/+ and DC0^H2/+ lines do not show significant differences from wild type at retention times of 0 and 1 h but do show significant differences at 3 and 7 h. *, P < 0.05; ***, P < 0.001.