Effects of a conditional drosophila PKA mutant on olfactory learning and memory

Abstract

The requirement for cAMP-dependent protein kinase (PKA) in associative learning of Drosophila was assessed in mutant flies hemizygous for a cold-sensitive allele, X4, of the DC0 gene, which encodes the major catalytic subunit of PKA. DC0X4 hemizygotes died as third-instar larvae at 18°C, the restrictive temperature, but were viable when raised at 25°C. Shifting adult DC0X4 hemizygotes from 25°C to 18°C led to a decrease in PKA activity from 24% to 16% of wild-type without impairing viability. At 25°C, DC0X4 hemizygotes exhibited reduced initial learning relative to controls but normal memory decay in a Pavlovian olfactory learning assay. Shifting the temperature from 25°C to 18°C prior to training reduced initial learning to a similar extent in DC0X4 hemizygotes and controls but resulted in a steeper memory decay curve only in DC0X4 hemizygotes. These observations are suggestive of a role for PKA in medium-term memory formation in addition to its previously established role in initial learning. © 1995 by Cold Spring Harbor Laboratory Press.