The courtship ritual of Drosophila males toward females has been extensively studied to elucidate the mechanisms of behavioral plasticity in insects. Courtship is an innate, fixed sequence of behaviors that results in mating. The implementation of this instinct involves adjusting specific parameters of the courtship behaviors, such as sound production, to increase the likelihood of successful copulation. Moreover, courtship can be temporarily suppressed following an unsuccessful attempt with a previously mated female. While the neural mechanisms underlying courtship learning are well described, the interaction between male behavioral sequencing and known female-derived determinants of suppression (e.g., cVA from mated females and active rejection behaviors) remains unclear. In our study, we characterized the structure of male courtship towards virgin, mated, and immature females. We found that changes in the frequencies of transitions between courtship behaviors provide adaptive restructuring in the implementation of this ritual. Courtship towards mated females causes males to reinitiate the ritual more frequently, and we hypothesize that repeated unsuccessful initiations may ultimately result in courtship suppression. When courting immature females, males neither attempt copulation nor restart the ritual, which may explain the absence of courtship suppression with this type of female and raises the question of the evolutionary significance of courtship towards immature females.

This study aimed to establish a comprehensive behavioral profile of male Drosophila after a space flight to the International Space Station (ISS). Climbing, locomotor activity, and courtship behavior were examined after a 7.5-day space mission in Drosophila males. Behavioral evaluations postflight conducted both on Drosophila males, which, aged 1-2 days, had been sent to the ISS, and on males, who underwent development from first instar larvae to early pupal stages under space flight conditions. The results revealed that imago space travel resulted in a lasting decline in performance across all behavioral tests for no less than 13 days after landing. The larval development of Drosophila males during space travel leads to unstable behavioral issues that nevertheless go on up to 21 days after landing in such fruit flies. Space experience affects Drosophila nervous system function and changes the operating mode of walk and song central pattern generators (CPG). Future research will answer the question of which molecular genetic alterations induced by space flight factors are responsible for lasting post-space flight nervous system and behavioral changes.

In animals, social experience plays an important role in the adaptive modification of behavior. Previous social experience changes locomotor activity in Drosophila melanogaster. In females, suppression of locomotion is observed only when flies are in aggregations, but males retain a reduced level of locomotor activity up to 5 days after being isolated from the group. The mechanisms underlying such behavioral plasticity still largely are unknown. In this study, we aimed to identify new candidate genes involved in the social experience-dependent modification of locomotor activity. We tested the effect of social experience on spontaneous locomotor activity in various mutant males, including those with impaired learning and memory, circadian rhythms, some biochemical pathways, and sensory systems. The results of the present study indicate that the biogenic amines and olfactory perception appear to play key roles in social experience-induced changes in locomotor activity. Also, we performed a screen of the collection of mutants carrying random autosomal insertions of PdL transposon. We isolated five candidate genes, of which two genes, Dek and Hel89B, encode proteins related to the formation of the epigenetic code, implying that epigenetic factors regulating gene expression may be involved in social experience-dependent modification of locomotor behavior.

Social experience (housing in an unisexual group) modifies locomotor activity in Drosophila. In females, suppression of locomotion occurs only when flies are in aggregations [1], but males retain a lowered level of locomotor activity up to 5 days after their separation from a group [2]. The mechanism by which social experience (housing in a group) affects locomotor activity in Drosophila males is yet unknown. To study the genetic control and clarify the mechanisms of behavioral changes resulting from social experience, we have tested the locomotor activity modifications in various mutants, including those with impaired learning and memory, circadian rhythms, some biochemical pathways, and sensory systems. The results of the present study show that these changes do not seem to be based on the learning and memory mechanisms. The biogenic amines (dopamine and octopamine) seems to play a principal role in the changes in locomotor activity caused by social experience. Also, the dependence of this behavioral modification on olfactory perception was shown. This implies the possible participation of pheromones, which should be verified in future research. Also, with the same aim, we have performed the screening of our collection of mutants carrying random autosomal insertions of PdLtransposon. Five candidate genes presumably playing a role in behavioral modifications resulting from social experience were revealed (Dek, Hel89B, RpL41, CG11791 and NaCP60E). The results imply a possible role for epigenetic regulation of gene expression in the modification of locomotor behavior caused by social experience.

Drosophila melanogaster is a popular model organism in the study of memory due to a wide arsenal of methods used to analyze neuronal activity. The most commonly used tests in research of behavioral plasticity are shock avoidance associated with chemosensory cues and courtship suppression after mating failure. Many authors emphasize the value of courtship suppression as a model of behavior most appropriate to natural conditions. However, researchers often investigate courtship suppression using immobilized and decapitated females as targets of courtship by males, which makes the data obtained from such flies less valuable. In our study, we evaluate courtship suppression towards immature mobile non-receptive females after training with mated or immature females combined with an aversive stimulus (quinine). We have shown that the previously described mechanisms of courtship suppression, as a result of the association of the courtship object with the repellent, as well as due to increased sensitivity to the anti-aphrodisiac cVA after mating failure, are not confirmed when immature mobile females are used. We discuss the reasons for the discrepancies between our results and literature data, define the conditions to be met in the courtship suppression test if the aim is to analyze the natural forms of behavioral plasticity, and present data on the test modifications to approximate conditions to natural ones.

Using an original method, we have received Drosophila melanogaster with a deficiency including a complete sequence of quick-to-court gene. In this report, we describe the behavioural features of this new deletion mutant. There were no serious deviations from the normal mating behaviour in flies with the deletion, but the behaviour of deletion mutants still had some features. Of all the elements, only the frequency of licking significantly increased in mutants. The duration of mating elements did not change in flies with deletion, and the latent period decreased only for following the female and licking. We have found that mutant males produce more courtship song than control males when courting Oregon R females as estimated by the pulse song index. In our experiment, mutant females provoked much less pulse song production by Oregon R males than control females do. Moreover, Oregon R males initiate courtship song towards mutant females later than towards control females. In other words, the study of pulse song production showed that the deficiency in females leads to a decrease in the intensity of courtship of wild-type males, whereas the deficiency in males leads to more intensive care for wild-type females.

Results of behavioral tests made postflight after two independent travels of Drosophila melanogaster to International Space Station (ISS) are presented. In Experiment 1, the first instar larvae were launched, and the eclosed imagoes gave the next generation that developed from the egg at ISS. After return to Earth the behavior of adult males of the next generation was examined. In Experiment 2, the newly emerged adult males were launched and after 7.5 days of staying at ISS were tested in the lab. In Experiment 1, we found pronounced influence of development in Space on subsequent locomotor behavior of adult flies. In flies developed in Space, all three independent parameters of locomotor behavior (run frequency, run duration and running speed) were increased, at least at certain time points, during the first hour of registration. At the same time, the climbing ability of experimental flies was reduced. In Experiment 2, no changes in the climbing ability were detected. During the first 30 min after registration beginning the flown flies performed less frequent but more extended runs than the control flies did. However, later the flown flies demonstrated an increased run frequency. Additionally, the interpulse interval in the pulse courtship song was shorter in the flown males. Taken together, the results point to a considerable activation of the central nervous system in flies developed at the ISS and to a minor one in the adult flies travelled to the ISS. This shows that earlier stages of development are more sensitive to spaceflight factors than the adult stage.

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.

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.

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.

Previous social experience may affect subsequent behavior. It was shown by other authors that Drosophila melanogaster males kept individually are more aggressive and sexually active than males kept in a group. In the present study, we tested the locomotor activity of individual males and females previously reared either individually, or in a group. We found that keeping 20 young males for three days together led to a strong long-term (up to 5 days) reduction in their further locomotor activity as individuals. Rearing of young males in groups of other sizes (2, 5, 10, and 30) produced a smaller or no after-effect. At the same time, we have not found any difference in subsequent behavior of individual females previously kept either individually, or in a group. We suppose that in a group, flies learned to suppress their locomotor activity to prevent unpleasant contacts with other animals (operant learning). It seems that in males this learning is more efficient because of the higher level of aggression producing the stronger negative reinforcement.

To investigate molecular mechanisms of central pattern generators (CPG s) functioning, we carried out a screening of collection of Drosophila P-insertional mutants for strong deviations in locomotion and courtship song. In 21 mutants, the site of the P-insertion was localized by sequencing of the fragments of genomic DNA flanking the P-element. Bioinformational analysis revealed a list of candidate genes, potential players in development and functioning of CPG s. Possible involvement of certain identified genes in rhythmic motor activity is suggested for the first time (CG15630, Map205).

Transmission of behavioral traits from mother to hybrids of first generation, revealed in researches performed under guidance of M.E. Lobashev and V.V. Ponomarenko since the middle of last century, is clearly adaptive and seems to be a phenomenon of general significance in biology. From the contemporary positions it may be explained by various genetic processes: sex-linked inheritance, cytoplasmic inheritance, maternal effect of nuclear genes, genomic imprinting. The review considers all of them with most attention to possible mechanisms of the late maternal effect of nuclear genes.

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 nemy(P153) 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 nemy(P153)) causes an increased level of locomotor activity, memory deficiency after the courtship conditioning and subnormal acquisition after the odor-shock conditioning.

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.

Evolutionary conservation of homologous genes that cause related phenotypes in humans and Drosophila help to unravel genes implicated in polygenic human diseases. Among them are neurodegenerative disorders, such as Huntington, Parkinson, Alzheimer and HIV-induced diseases. They are characterized by a late onset disturbances of memory, changes in volumetric indices of the brain structures involved in memory formation, synaptic and glial pathology, and altered content of the intermediates of the kynurenine pathway, the endogenous modulators of the NMDA receptors. This pathway in conserved in insects, rodents and humans. We, therefore, studied the effects of aberrant tryptophan metabolism on memory, brain plasticity, synaptic and glial immunoreactivity in the Drosophila mutants vermilion (no kynurenines) and cinnabar (excess of neuroprotective kynurenic acid) over the life time. The mutant vermilion demonstrated gradual decline of 3-th memory performance and complete memory failure on the 28th day of life in a paradigm of conditioned courtship suppression. A drastic increase in the volume of the calyces of the mushroom bodies, and a decay in immunochemical staining of this brain structure with antibodies to synaptic protein csp and glia, precede the age-dependent memory defect and develop from the 12th day of adult life.

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.