A search for Drosophila mutants with phenotypes similar to human diseases might help to unravel evolutionary conserved genes implicated in polygenic human disorders. Among these are neurodegenerative diseases, characterized by a late onset disturbance of memory, synaptic and glial pathology, structural brain impairments and altered content of the intermediates of the kynurenine pathway, the modulators of glutamate excito- and oxidative toxicity. This pathway is conserved in insects, in rodents, and in humans. We tested the Drosophila mutants cardinal (3-hydroxykynurenine excess) and cinnabar (kynurenic acid excess) for age-dependent changes in memory, synaptic pathology, structural brain plasticity and glial immunoreactivity. The mutant cardinal demonstrated a decline in learning and memory from the 12th to the 29th day of life in a paradigm of conditioned courtship suppression. Memory decline was accompanied by a sharp decrease in immunoreactivity to the synaptic cysteine string protein, and alterations in volumetric parameters of the mushroom bodies, the brain structures implicated in memory.

Although many genes have been shown to play essential roles in learning and memory, the precise molecular and cellular mechanisms underlying these processes remain to be fully elucidated. Here, we present the molecular and behavioral characterization of the Drosophila memory mutant nemy. We provide multiple lines of evidence to show that nemy arises from a mutation in a Drosophila homologue of cytochrome B561. nemy is predominantly expressed in neuroendocrine neurons in the larval brain, and in mushroom bodies and antennal lobes in the adult brain, where it is partially coexpressed with peptidyl ␣-hydroxylating monooxygenase (PHM), an enzyme required for peptide amidation. Cytochrome b561 was found to be a requisite cofactor for PHM activity and we found that the levels of amidated peptides were reduced in nemy mutants. Moreover, we found that knockdown of PHM gave rise to defects in memory retention. Altogether, the data are consistent with a model whereby cytochrome B561-mediated electron transport plays a role in memory formation by regulating intravesicular PHM activity and the formation of amidated neuropeptides.

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In Drosophila, courtship reduction in male flies that have previous experience of courting a mated female is a result of the counterconditioning of an attractive unconditioned stimulus (US)—the aphrodisiac—which becomes an aversive conditioned stimulus (CS) after being paired with an aversive US—the antiaphrodisiac. In a retention test with a virgin female lacking the antiaphrodisiac, males retain a lower level of courtship for 3 hr after training. However, a measure of courtship suppression, the learning index (LI), decreases significantly after only 1 hr. In contrast, in the retraining test with a mated female, the LI shows no decrease for 8 hr but falls below significance 16 hr after training. These results are discussed in terms of the transfer of training. Nonspecific transfer and nonassociative behavioral modifications play little, if any, role in the transfer of training. The retraining test is recommended as a new protocol for studying conditioned courtship. According to the model proposed here, in tests with a virgin female, the duration of memory retention is limited by the retention of the direct association between the CS and the aversive motivational system or by the retention of an internal representation of the US. In retraining tests, the CS–US association seems to be the only factor involved in transfer 3 or more hours after training.

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A Panova & Nikolai G Kamyshev (2014) The effect of neurospecific knockdown of candidate genes for locomotor behavior and sound production in Drosophila melanogaster, Fly, 8:3, 176-187, DOI: 10.4161/19336934.2014.983389 To link to this article: https://doi.org/10. 4161/19336934.2014.983389 Molecular mechanisms underlying the functioning of central pattern generators (CPGs) are poorly understood. Investigations using genetic approaches in the model organism Drosophila may help to identify unknown molecular players participating in the formation or control of motor patterns. Here we report Drosophila genes as candidates for involvement in the neural mechanisms responsible for motor functions, such as locomotion and courtship song. Twenty-two Drosophila lines, used for gene identification, were isolated from a previously created collection of 1064 lines, each carrying a P element insertion in one of the autosomes. The lines displayed extreme deviations in locomotor and/or courtship song parameters compared with the whole collection. The behavioral consequences of CNS-specific RNAi-mediated knockdowns for 10 identified genes were estimated. The most prominent changes in the courtship song interpulse interval (IPI) were seen in flies with Sps2 or CG15630 knockdown. Glia-specific knockdown of these genes produced no effect on the IPI. Estrogen-induced knockdown of CG15630 in adults reduced the IPI. The product of the CNS-specific gene, CG15630 (a predicted cell surface receptor), is likely to be directly involved in the functioning of the CPG generating the pulse song pattern. Future studies should ascertain its functional role in the neurons that constitute the song CPG. Other genes (Sps2, CG34460), whose CNS-specific knockdown resulted in IPI reduction, are also worthy of detailed examination.

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This article presents results obtained from studies of the plasticity of changes in social behavior in Drosophila (interactions between individuals in groups) in conditions of homo- and heterogeneous environments. This is the first report of data illustrating self-starting acquisition by female Drosophila of a classical conditioned reflex to contextual factors signaling possible threats from other individuals and blocking the initiation of activity. A previously described operant conditioned reflex also helped flies avoid aggression from other individuals and make more efficient use of food resources by decreasing the initially high level of activity. Classical conditioning had the effect that the fly did not need to repeat acquisition of the conditioned reflex each time: when placed into an analogous situation, the fly's activity automatically decreased as a result of exposure to the conditioned stimulus, i.e., contextual factors.