Biology subjects

Kamikouchi, A.

Publications and source records attributed to Kamikouchi, A..

12 recordsLinked to original sources

bioRxiv2026

Sex peptide-SPR-serotonin signaling regulates mating-induced Sex peptide replenishment in Drosophila, suggesting an ancestral role in males

Seminal fluid not only assists successful fertilization but also induces changes in female post-mating behavior and physiology. Consequently, males with depleted or inadequate seminal fluid produce fewer offspring. Males of iteroparous species therefore increase seminal fluid production to replenish exhausted supplies. However, it remains unclear how mating-induced replenishment of seminal fluid components is regulated at the molecular and cellular levels. Here, we show that replenishment of Sex peptide (SP) in male Drosophila melanogaster requires both SP and its receptor SPR. Mechanistically, mating-induced SP replenishment in the male accessory gland (MAG) is regulated by MAG-projecting serotonergic neurons, and this regulation depends on SPR, which is likely activated by SP as it passes through the reproductive tract during mating. This inter-tissue signaling pathway is not limited to SP but also coordinates the post-mating upregulation of an additional seminal fluid protein gene. While SP-SPR signaling is a well-known regulator of female post-mating responses, we demonstrate that it also modulates male physiology. Furthermore, comparative analyses across 12 drosophilid species are consistent with the hypothesis that SP-SPR signaling acquired a role in males before its role in canonical female post-mating responses evolved. We therefore propose that the role of SP-SPR signaling as a mating signal in males is ancestral to its more familiar but evolutionarily derived role in females.

physiology↗

bioRxiv2026

The sex determination gene doublesex is essential for female-specific flight and hearing properties in Aedes aegypti mosquitoes

The acoustic communication system supporting reproduction in disease-transmitting mosquitoes is sexually dimorphic, from the sounds that mosquitoes make to the properties of their flagellar ears. The molecular mechanisms shaping these dimorphisms, however, remain unclear. Here, we explored the contributions of the female-specific isoform of the sex determination gene doublesex (dsxF) in specifying female-unique properties in the acoustic communication system of Aedes aegypti mosquitoes. CRISPR-Cas9 based generation of a novel dsxF knockout line found that dsxF mutant females were flightless due to lack of expression of a female-specific myosin gene, myo-fem, in the thorax. We found that DsxF directly binds to four different enhancer sites of myo-fem to promote gene expression. We observed that dsxF female ears exhibited intersex neuroanatomical characteristics and contained a more extensive auditory efferent network than control females. At the peripheral hearing function level, dsxF female ears displayed intersex tuning frequencies associated with increased expression of hearing genes in dsxF female ears compared to control females. We identified three hearing genes transcriptionally inhibited by DsxF via direct binding. DsxF is a bifunctional transcription factor, activating female-specific gene expression in thoraces whilst repressing male-biased gene expression in ears to coordinate female-unique features across sensory and motor systems.

neuroscience↗

bioRxiv2026

The sex determination gene fruitless is essential for male Aedes aegypti mosquito swarming and attraction to female flight sounds

Aggregating male mosquitoes locate females by showing strong and innate attraction to female flight sounds, with these behaviors forming the basis of mating in the worlds deadliest animal. In contrast, females do not show aggregation or sound attraction behaviors. Despite being documented for almost a century, the molecular underpinnings of these behavioral dimorphisms remain unknown. Here, we found that by disrupting the male-specific isoform of the key sex determination gene fruitless (referred to as fruM) in Aedes aegypti, mutant males behave like females. fruM mutant males show complete abolition of aggregation and sound attraction behaviors, resulting in failure to locate females for mating. We identified strong fruitless expression in control male ears, with the loss of FruM severely disrupting mutant male ability to amplify female flight sounds compared to control males. fruM mutant male ears propagate frequency-specific, sound-evoked electrical signals at about one-sixth the magnitude of control males, significantly reducing the amount of auditory information relayed to the brain. fruitless thus plays a significant role in determining proper male peripheral hearing function, which enables male hearing behaviors essential for mating. Transcriptomic analyses of mosquito ears enabled identification of essential hearing genes under the transcriptional influence of FruM. We propose that FruM fine-tunes the masculinization of mosquito ears through shaping male-specific hearing cellular machineries that support male attraction to female flight sounds. We conclude that FruM is the master regulator of male-specific reproductive behaviors in mosquitoes and propose fruitless, as well as fruitless-dependent genes, as novel targets for control strategies. HighlightsO_LIFruM is the master regulator of male swarming and attraction to female flight sounds C_LIO_LIFruM in male ears is essential for male amplification of female flight sounds C_LIO_LIFruM in male ears modulates sound-evoked electrical signal propagation to the brain C_LIO_LIFruM regulates essential hearing gene expression C_LI

neuroscience↗

bioRxiv2025

Mating status-dependent dopaminergic modulation of auditory sensory neurons in Drosophila

Mating status often modulates responses to courtship sounds in animals. The neural mechanisms underlying this modulation, however, have not been well clarified. Here, we show that dopaminergic signals are involved in modulating the responses of auditory sensory neurons in Drosophila melanogaster females depending on their mating status. These neurons abundantly express three types of dopamine receptors, with some having direct synaptic connections with dopaminergic neurons. Of these receptors, suppressing the expression of Dop1R2 reduces sound responses of auditory sensory neurons in unmated but not mated females. Moreover, expression of Dop1R2 in auditory sensory neurons enhances the song response behavior of unmated females, manifested by copulation receptivity when exposed to songs. Our research suggests that dopaminergic modulation via Dop1R2 is involved in mating state-dependent regulation of auditory sensory processing.

neuroscience↗

bioRxiv2025

cAMP-related second messenger pathways modulate hearing function in Aedes aegypti mosquitoes

The powerful ears of male Aedes aegypti mosquitoes facilitate identification and localization of mating partners via detection of female flight tones. Male hearing function is modulated by the efferent release of neurotransmitters, though the secondary mechanisms underlying this modulation remain unclear. Here, we investigated these mechanisms using octopamine as a model, as octopamine modulates hearing function and the erection status of fibrillar hairs lining male ears. We found that pharmacological interference with octopamine receptors alters hearing function at multiple levels and identified the second messenger cAMP as likely mediating these changes. Furthermore, the erection status of male ear fibrillar hairs could be altered by targeting specific sub-types of octopamine receptors, but these changes were not linked to changes in ear frequency tuning. Finally, we suggest that octopamine 2 receptors linked to fibrillar hair erection may not always produce functional proteins across species, with downstream implications for hearing behaviors. HighlightsO_LIOctopamine and its receptors are found throughout Aedes aegypti mosquito ears C_LIO_LIPharmacological interference with octopamine receptors modulates hearing function C_LIO_LIModulating levels of the second messenger cAMP also alters hearing function C_LIO_LIEar frequency tuning does not correlate with the erection of hairs lining male ears C_LI

neuroscience↗

bioRxiv2024

YORU: social behavior detection based on user-defined animal appearance using deep learning

The creation of tools using deep learning methodologies for animal behavior analysis has revolutionized neuroethology. They allow researchers to analyze animal behaviors and reveal causal relationships between specific neural circuits and behaviors. However, the application of such annotation/manipulation systems to social behaviors, in which multiple individuals interact dynamically, remains challenging. Here, we applied an object detection algorithm to classify animal social behaviors. Our system, packaged as "YORU" (Your Optimal Recognition Utility), classifies animal behaviors, including social behaviors, based on the shape of the animal as a "behavior object". It successfully classified several types of social behaviors ranging from vertebrates to insects. We also integrated a closed-loop control system for operating optogenetic devices into the YORU package. YORU enables real-time delivery of photostimulation feedback to specific individuals during specific behaviors, even when multiple individuals are close together. We hope that the YORU system will accelerate the understanding of the neural basis of social behaviors.

neuroscience↗

bioRxiv2024

Sexually dimorphic auditory representation in Aedes aegypti brains

Male attraction to female flight sounds is a vital, reproducible component of courtship in many species of mosquitoes; however, female acoustic behaviours have proven challenging to define. To investigate sexual dimorphisms in acoustic behaviours, previous reports have largely focused on differences in mosquito peripheral ear anatomy and function. Whilst molecular investigations have recently begun on the auditory periphery, sexual dimorphisms in central processing of acoustic information have not yet been explored. Here we used a combination of neurotracing, calcium imaging and molecular analyses to examine sexual dimorphisms in auditory processing in the yellow fever mosquito Aedes aegypti. We identified shared and dimorphic neurons connecting male and female ears to the primary auditory processing centre in the brain, and defined multiple distinct neuronal clusters based on responses to auditory stimulation. We finally used transcriptomic and proteomic analyses to investigate the molecular factors underlying these differences, with motile ciliary-related terms significantly enriched in males.

neuroscience↗

bioRxiv2024

The voltage-gated potassium channel Shal (Kv4) contributes to active hearing in Drosophila

The full complement of ion channels which influence insect auditory mechanotransduction, and the mechanisms by which their influence is exerted, remain unclear. Shal (Kv4), a Shaker family member encoding voltage-gated potassium channels in Drosophila melanogaster, has been shown to localize to dendrites in some neuron types, suggesting a potential role for Shal in Drosophila hearing, including mechanotransduction. A GFP-protein trap was used to visualize the localization of the Shal channel in Johnstons organ neurons responsible for hearing in the antenna. Shal protein was localized to the cell body and the proximal dendrite region of sensory neurons, suggesting its involvement not only in general auditory function, but specifically in mechanotransduction. Electrophysiological recordings conducted to assess neural responses to auditory stimuli in mutant Shal flies revealed significant decreases in auditory responses. Laser Doppler Vibrometer recordings indicated abnormal antennal free fluctuation frequencies in mutant lines, indicating an effect on active antennal tuning, and thus active transduction mechanisms. This suggests that Shal participates in coordinating energy-dependent antennal movements in Drosophila that are essential for tuning the antenna to courtship song frequencies. Significance StatementThe study of fruit fly hearing has revealed mechanosensitive ion channels that participate in mechanotransduction, and as in mammalian hearing, energy-dependent mechanisms actively amplify and tune auditory processes. Identifying distinct roles played by different ion channels is essential to better understand this process. Here, we explore the influence of a specific voltage-gated potassium channel, Shal, on fly hearing, and find that it affects specific parts of the mechanotransduction process. Our research uncovers Shals localization in sensory dendrite regions of auditory neurons, where it contributes to shaping mechanotransduction and active antennal tuning. Understanding Shals involvement in auditory function and mechanotransduction deepens our knowledge of fly hearing and unveils a key player in the coordination of energy-dependent active antennal movements.

neuroscience↗

bioRxiv2023

Neural-circuit basis of song preference learning in fruit flies

As observed in human language learning and song learning in birds, the fruit fly Drosophila melanogaster changes its auditory behaviors according to prior sound experiences. Female flies that have heard male courtship songs of the same species are less responsive to courtship songs of different species. This phenomenon, known as song preference learning in flies, requires GABAergic input to pC1 neurons in the central brain, with these neurons playing a key role in mating behavior by integrating multimodal sensory and internal information. The neural circuit basis of this GABAergic input, however, has not yet been identified. Here, we find that pCd-2 neurons, totaling four cells per hemibrain and expressing the sex-determination gene doublesex, provide the GABAergic input to pC1 neurons for song preference learning. First, RNAi-mediated knockdown of GABA production in pCd-2 neurons abolished song preference learning. Second, pCd-2 neurons directly, and in many cases mutually, connect with pC1 neurons, suggesting the existence of reciprocal circuits between pC1 and pCd-2 neurons. Finally, GABAergic and dopaminergic inputs to pCd-2 neurons are necessary for song preference learning. Together, this study suggests that reciprocal circuits between pC1 and pCd-2 neurons serve as a sensory and internal state-integrated hub, allowing flexible control over female copulation. Consequently, this provides a neural circuit model that underlies experience-dependent auditory plasticity. SignificanceTo find a suitable mate, an organism must adapt its behavior based on past experiences. In the case of Drosophila, female assessments of male song signals, which contain information about the status and species of the sender, are experience dependent. Here, we show that reciprocal circuits in the central brain modulate the females song response depending on her previous auditory experiences. These circuits exhibit feedback and lateral inhibition motifs, and are regulated by dopaminergic and GABAergic inputs. While the effects of prior auditory experiences on sound responsiveness have been extensively studied in other species, our research advances the use of Drosophila as a model for dissecting the circuitry underlying experience-dependent auditory plasticity at single-cell resolution.

neuroscience↗

bioRxiv2021

Biogenic action of Lactobacillus plantarum SBT2227 promotes sleep in Drosophila melanogaster

Lactic acid bacteria (LAB) influence multiple aspects of host brain function via the production of active metabolites in the gut, which is known as the pre/pro-biotic action. However, little is known about the biogenic effects of LAB on host brain function. Here, we reported that the Lactobacillus plantarum SBT2227 promoted sleep in Drosophila melanogaster. Administration of SBT2227 primarily increased the amount of sleep and decreased sleep latency at the beginning of night-time. The sleep-promoting effects of SBT2227 were independent of the existing gut flora. Furthermore, heat treatment or mechanical crushing of SBT2227 did not suppress the sleep-promoting effects, indicative of biogenic action. Transcriptome analysis, and RNAi mini-screening for gut-derived peptide hormones revealed the requirement of neuropeptide F, a homologue of the mammalian neuropeptide Y, for the action of SBT2227. These biogenic effects of SBT2227 on the host sleep provide new insights into the interaction between the brain and gut bacteria.

animal behavior and cognition↗

bioRxiv2020

Auditory experience prevents loss of the innate song preference as a selective cue in Drosophila

Auditory learning is a prerequisite step for acoustic communication learning, which was previously assumed to be restricted to animals with high levels of cognition, such as humans, cetaceans, and birds. How animals that rely on auditory learning for acoustic communication form sound preferences is not known. Fruit flies are a recently proposed novel animal model for studying experience-dependent auditory perceptual plasticity because of their ability to acquire song preferences via song exposure. Whether fruit flies have innate courtship song preferences, however, is unclear. Here we report that, similar to songbirds, fruit flies exhibit an innate preference for conspecific courtship songs. Maintenance of innate song preference requires song input, reminiscent of the song learning process in songbirds. Our findings also indicate that the response to conspecific and heterospecific songs manifests temporal and experience-dependent differentiation, which may underlie innate song preference and its plasticity. In addition, we find that flies have a robust ability to reacquire song preference during aging. Fruit flies thus offer a novel and simple approach for studying sound preference formation and its underlying mechanisms.

neuroscience↗

bioRxiv2020

Convergence of distinct subpopulations of mechanosensory neurons onto a neural circuit that elicits grooming

Diverse subpopulations of mechanosensory neurons detect different mechanical forces and influence behavior. How these subpopulations connect with central circuits to influence behavior remains an important area of study. We previously discovered a neural circuit that elicits grooming of the Drosophila melanogaster antennae that is activated by an antennal mechanosensory chordotonal organ, the Johnstons organ (JO) (Hampel et al., 2015). Here, we describe anatomically and physiologically distinct JO mechanosensory neuron subpopulations and define how they interface with the circuit that elicits antennal grooming. We show that the subpopulations project to distinct zones in the brain and differ in their responses to mechanical stimulation of the antennae. Each subpopulation elicits grooming through direct synaptic connections with a single interneuron in the circuit, the dendrites of which span the different mechanosensory afferent projection zones. Thus, distinct JO subpopulations converge onto the same neural circuit to elicit a common behavioral response.

neuroscience↗