LATHEO, A NEW GENE INVOLVED IN ASSOCIATIVE LEARNING AND MEMORY IN DROSOPHILA-MELANOGASTER, IDENTIFIED FROM P-ELEMENT MUTAGENESIS

Genetic dissection of learning and memory in Drosophila has been limited by the existence of ethyl methanesulfonate (EMS)-induced mutations in only a small number of X-linked genes. To remedy this shortcoming, we have begun a P element mutagenesis to screen for autosomal mutations that disrupt associative learning and/or memory. The generation of "P-tagged" mutant alleles will expedite molecular cloning of these new genes. Here, we describe a behavior-genetic characterization of latheo(P1), a recessive, hypomorphic mutation of an essential gene. latheo(P1) flies perform poorly in olfactory avoidance conditioning experiments. This performance deficit could not be attributed to abnormal olfactory acuity or shock reactivity-two task-relevant "peripheral" behaviors which are used during classical conditioning. Thus, the latheo(P1) mutation appears to affect learning/memory specifically. Consistent with chromosomal in situ localization of the P element insertion, deficiencies of the 49F region of the second chromosome failed to complement the behavioral effect of the latheo(P1) mutation. Further complementation analyses between latheo(P1) and lethal alleles, produced by excision of the latheo(P1) insert or by EMS or gamma-rays, in the 49F region mapped the latheo mutation to one vital complementation group. Flies heterozygous for latheo(P1) and one of two EMS lethal alleles or one lethal excision allele also show the behavioral deficits, thereby demonstrating that the behavioral and lethal phenotypes co-map to the same locus.