Overexpression of isoform B of Dgp-1 gene enhances locomotor activity in senescent Drosophila males and under heat stress.

Here, we describe the longevity and locomotor behavior of senescent Drosophila males with altered expression of Dgp-1 gene. In comparison with the wild-type Canton-S (CS) males, six characteristics of the phenotype of Dgp-1[843k] mutant were found: (1) low expression of isoform A; (2) augmented expression of isoform B; (3) reduction in the mean lifespan; (4) decrease in the running speed in 3-day-old flies; (5) maintenance of a high run frequency in senescent flies; and (6) resistance to heat stress manifested as maintenance of a high run frequency at 29 °C. After cessation of "cantonization" process, mean lifespan of the mutant males drifted from low to high values finally exceeding that for CS. In contrast, behavioral phenotype of the mutant was robust. Using the GAL4/UAS system, we showed that neurospecific overexpression of isoform B resulted in a slight decrease of longevity and a high level of run frequency in the senescent flies, similar to that in Dgp-1[843K] mutant. In addition, a decreased level of reactive oxygen species was found in Dgp-1[843K] mutant males maintained under stress conditions. The elevated resistance to oxidative stress probably explains the two distinctive features of the mutation: resistance to aging processes and thermal stress displayed at behavioral level.

Gene CG15630 (fipi) is involved in regulation of the interpulse interval in Drosophila courtship song.

To study the central pattern generators functioning, previously we identified genes, whose neurospecific knockdowns led to deviations in the courtship song of Drosophila melanogaster males. Reduced expression of the gene CG15630 caused a decrease in the interpulse interval. To investigate the role of CG15630, which we have called here fipi (factor of interpulse interval), in the courtship song production, at first, we have characterized fipi transcripts and protein (FIPI) in the mutant flies carrying P insertion and deletions in this gene and in flies with its RNAi knockdown. FIPI is homologous to the mammalian NCAM2 protein, an important factor of neuronal development in the olfactory system. In this study, we have revealed that local fipi knockdown in the antennal olfactory sensory neurons (OR67d and IR84a), which are responsible for reception of chemosignals modulating courtship behavior, alters the interpulse interval in the opposite directions. Thus, a proper fipi expression seems to be necessary for perception of sexual chemosignals, and the effect of fipi knockdown on IPI value depends on the type of chemoreceptor neurons affected.

The effect of neurospecific knockdown of candidate genes for locomotor behavior and sound production in Drosophila melanogaster.

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.

nemy encodes a cytochrome b561 that is required for Drosophila learning and 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 alpha-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.

Novel memory mutants in Drosophila: behavioral characteristics of the mutant nemyP153.

BACKGROUND: Starting from Benzer's initiative, the approach of forward genetics has been widely used to isolate mutations affecting learning and memory. For this aim, mainly the odor-shock conditioning was employed. We have isolated P insertional mutations affecting memory after courtship conditioning - another form of classical conditioning in Drosophila. Here we report the behavioral characteristics of one of these mutants, which we have called nemy (no extended memory). RESULTS: The courtship activity of Drosophila males is reduced when a male has a previous experience of courting a fertilized female. In the wild-type strain C-S (K), this conditioned courtship inhibition lasts for 1-3 h in the test with a virgin female, and at least for 8 h in the test with a subsequent fertilized female. The mutant males nemyP153 display distinct memory deficiency in both tests already 0.5 h after training. The mutant males show an increased level of locomotor activity unrelated to courtship, and spend more time in such an element of courtship as pursuit. This, however, seems to be a pleiotropic effect of the mutation, independent from its influence on the courtship conditioning. The mutation reduces also memory performance after the odor-shock classical conditioning. At the same time, the sensory and motor functions involved in this type of learning seem to be normal. CONCLUSIONS: Insertion of P-lacW vector into 49B region of the second chromosome (mutation nemyP153) causes an increased level of locomotor activity, memory deficiency after the courtship conditioning and subnormal acquisition after the odor-shock conditioning.