Despite the importance of aggression in the behavioral repertoire of most animals, relatively little is known of its proximate causation and control. To take advantage of modern methods of genetic analysis for studying this complex behavior, we have developed a quantitative framework for studying aggression in common laboratory strains of the fruit fly, Drosophila melanogaster. In the present study we analyze 73 experiments in which socially naive male fruit flies interacted in more than 2,000 individual agonistic interactions. This allows us to (i) generate an ethogram of the behaviors that occur during agonistic interactions; (ii) calculate descriptive statistics for these behaviors; and (iii) identify their temporal patterns by using sequence analysis. Thirty-minute paired trials between flies contained an average of 27 individual agonistic interactions, lasting a mean of 11 seconds and featuring a variety of intensity levels. Only few fights progressed to the highest intensity levels (boxing and tussling). A sequential analysis demonstrated the existence of recurrent patterns in behaviors with some similarity to those seen during courtship. Based on the patterns characterized in the present report, a detailed examination of aggressive behavior by using mutant strains and other techniques of genetic analysis becomes possible.
SummaryBackgroundAfter mating, Drosophila females undergo a remarkable phenotypic switch resulting in decreased sexual receptivity and increased egg laying. Transfer of male sex peptide (SP) during copulation mediates these postmating responses via sensory neurons that coexpress the sex-determination gene fruitless (fru) and the proprioceptive neuronal marker pickpocket (ppk) in the female reproductive system. Little is known about the neuronal pathways involved in relaying SP-sensory information to central circuits and how these inputs are processed to direct female-specific changes that occur in response to mating.ResultsWe demonstrate an essential role played by neurons expressing the sex-determination gene doublesex (dsx) in regulating the female postmating response. We uncovered shared circuitry between dsx and a subset of the previously described SP-responsive fru+/ppk+-expressing neurons in the reproductive system. In addition, we identified sexually dimorphic dsx circuitry within the abdominal ganglion (Abg) critical for mediating postmating responses. Some of these dsx neurons target posterior regions of the brain while others project onto the uterus.ConclusionsWe propose that dsx-specified circuitry is required to induce female postmating behavioral responses, from sensing SP to conveying this signal to higher-order circuits for processing and through to the generation of postmating behavioral and physiological outputs.
Dopamine (DA) and serotonin (5HT) are reported to serve important roles in aggression in a wide variety of animals. Previous investigations of 5HT function in adult Drosophila behavior have relied on pharmacological manipulations, or on combinations of genetic tools that simultaneously target both DA and 5HT neurons. Here, we generated a transgenic line that allows selective, direct manipulation of serotonergic neurons and asked whether DA and 5HT have separable effects on aggression. Quantitative morphological examination demonstrated that our newly generated tryptophan hydroxylase (TRH)-Gal4 driver line was highly selective for 5HT-containing neurons. This line was used in conjunction with already available Gal4 driver lines that target DA or both DA and 5HT neurons to acutely alter the function of aminergic systems. First, we showed that acute impairment of DA and 5HT neurotransmission using expression of a temperature sensitive form of dynamin completely abolished mid- and high-level aggression. These flies did not escalate fights beyond brief low-intensity interactions and therefore did not yield dominance relationships. We showed next that manipulation of either 5HT or DA neurotransmission failed to duplicate this phenotype. Selective disruption of 5HT neurotransmission yielded flies that fought, but with reduced ability to escalate fights, leading to fewer dominance relationships. Acute activation of 5HT neurons using temperature sensitive dTrpA1 channel expression, in contrast, resulted in flies that escalated fights faster and that fought at higher intensities. Finally, acute disruption of DA neurotransmission produced hyperactive flies that moved faster than controls, and rarely engaged in any social interactions. By separately manipulating 5HT- and DA- neuron systems, we collected evidence demonstrating a direct role for 5HT in the escalation of aggression in Drosophila.
Summary Background In many insect species, cuticular hydrocarbons serve as pheromones that can mediate complex social behaviors. In Drosophila melanogaster, several hydrocarbons including the male sex pheromone 11-cis-vaccenyl acetate (cVA) and female-specific 7,11-dienes influence courtship behavior and can function as cues for short-term memory associated with the mating experience. Behavioral and physiological studies suggest that other unidentified chemical communication cues are likely to exist. To more fully characterize the hydrocarbon profile of the D. melanogaster cuticle, we applied direct ultraviolet laser desorption/ionization orthogonal time-of-flight mass spectrometry (UV-LDI-o-TOF MS) and analyzed the surface of intact fruit flies at a spatial resolution of approximately 200 μm. Results We report the chemical and spatial characterization of 28 species of cuticular hydrocarbons, including a new major class of oxygen-containing compounds. Using UV-LDI MS, pheromones previously shown to be expressed exclusively by one sex, e.g. cVA, 7,11-heptacosadiene, and 7,11-nonacosadiene, appear to be found on both male and female flies. In males, cVA co-localizes at the tip of the ejaculatory bulb with a second acetylated hydrocarbon named CH503. We describe the chemical structure of CH503 as 3-O-acetyl-1,3-dihydroxy-octacosa-11,19-diene and show one behavioral role for this compound as a long-lived inhibitor of male courtship. Like cVA, CH503 is transferred from males to females during mating. Unlike cVA, CH503 remains on the surface of females for at least 10 days. Conclusions Oxygenated hydrocarbons comprise one major previously undescribed class of compounds on the Drosophila cuticular surface. In addition to cVA, a newly-discovered long chain acetate, CH503, serves as a mediator of courtship-related chemical communication.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.