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Zhantiev R, Korsunovskaya O. Bimodality of auditory receptors in bush-crickets. Сontinued discussion. It's time to experiment. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2023; 339:961-966. [PMID: 37559464 DOI: 10.1002/jez.2745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 07/28/2023] [Accepted: 07/29/2023] [Indexed: 08/11/2023]
Abstract
Continuation of the discussion on the sensitivity of the chordotonal sensilla of the tympanal organ of bush-crickets to vibratory stimuli. We have previously shown that individual receptors registered directly in the tympanal organ perceive vibrations along with sound stimuli. In addition, scolopidia of the crista acustica possess mixed sensitivity, too, as well as receptors of the intermediate organ. The authors of the comment offered their opinion concerning our applied methods as well as our obtained results. In particular, they noted the dissimilarity of our data from the previously obtained data (the 1970s-1990s), mainly in the laboratory of Prof. K. Kalmring, who assumed that only low-frequency receptors, in particular receptors of the intermediate organ, possess mixed sensitivity. At the same time, receptor activity was recorded in the tympanal nerve without morphological identification of receptors (with the exception of one stained neuron in the prothoracic ganglion). We carried out a series of experiments using the method of K. Kalmring and found that it is possible to register several receptors in the tympanal nerve with different reactions during one experiment: to sound only, also both to vibration stimuli and sound. In the latter case, we dealt with low-threshold receptors, which responded to ultrasound, and this with high probability belonged to the crista acustica. Similar data were previously obtained on the bush-cricket Decticus verrucivorus. In this publication, we explain the methodological features of our work and suggest that the loss of sensitivity to vibrations at the level of the tympanal nerve by some auditory receptors may be due to the ephaptic and/or chemical interaction of the tympanal organ receptors with vibroreceptors of the subgenual or other organs. To verify this hypothesis, it is necessary to conduct additional studies, such as physiological, morphological, and immunohistochemical, along the entire vibroacoustic afferent tract, that is, from the peripheral part to the first switches to the corresponding interneurons.
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Affiliation(s)
- Rustem Zhantiev
- Department of Entomology, Lomonosov Moscow State University, Moscow, Russia
| | - Olga Korsunovskaya
- Department of Entomology, Lomonosov Moscow State University, Moscow, Russia
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2
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Loh YM, Su MP, Ellis DA, Andrés M. The auditory efferent system in mosquitoes. Front Cell Dev Biol 2023; 11:1123738. [PMID: 36923250 PMCID: PMC10009176 DOI: 10.3389/fcell.2023.1123738] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 02/17/2023] [Indexed: 03/02/2023] Open
Abstract
Whilst acoustic communication forms an integral component of the mating behavior of many insect species, it is particularly crucial for disease-transmitting mosquitoes; swarming males rely on hearing the faint sounds of flying females for courtship initiation. That males can hear females within the din of a swarm is testament to their fabulous auditory systems. Mosquito hearing is highly frequency-selective, remarkably sensitive and, most strikingly, supported by an elaborate system of auditory efferent neurons that modulate the auditory function - the only documented example amongst insects. Peripheral release of octopamine, serotonin and GABA appears to differentially modulate hearing across major disease-carrying mosquito species, with receptors from other neurotransmitter families also identified in their ears. Because mosquito mating relies on hearing the flight tones of mating partners, the auditory efferent system offers new potential targets for mosquito control. It also represents a unique insect model for studying auditory efferent networks. Here we review current knowledge of the mosquito auditory efferent system, briefly compare it with its counterparts in other species and highlight future research directions to unravel its contribution to mosquito auditory perception.
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Affiliation(s)
- YuMin M. Loh
- Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Matthew P. Su
- Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
- Institute for Advanced Research, Nagoya University, Nagoya, Aichi, Japan
| | - David A. Ellis
- UCL Ear Institute, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
| | - Marta Andrés
- UCL Ear Institute, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
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3
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Hampel S, Eichler K, Yamada D, Bock DD, Kamikouchi A, Seeds AM. Distinct subpopulations of mechanosensory chordotonal organ neurons elicit grooming of the fruit fly antennae. eLife 2020; 9:e59976. [PMID: 33103999 PMCID: PMC7652415 DOI: 10.7554/elife.59976] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 10/25/2020] [Indexed: 11/13/2022] Open
Abstract
Diverse mechanosensory neurons detect different mechanical forces that can impact animal behavior. Yet our understanding of the anatomical and physiological diversity of these neurons and the behaviors that they influence is limited. We previously discovered that grooming of the Drosophila melanogaster antennae is elicited by an antennal mechanosensory chordotonal organ, the Johnston's organ (JO) (Hampel et al., 2015). Here, we describe anatomically and physiologically distinct JO mechanosensory neuron subpopulations that each elicit antennal grooming. We show that the subpopulations project to different, discrete zones in the brain and differ in their responses to mechanical stimulation of the antennae. Although activation of each subpopulation elicits antennal grooming, distinct subpopulations also elicit the additional behaviors of wing flapping or backward locomotion. Our results provide a comprehensive description of the diversity of mechanosensory neurons in the JO, and reveal that distinct JO subpopulations can elicit both common and distinct behavioral responses.
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Affiliation(s)
- Stefanie Hampel
- Institute of Neurobiology, University of Puerto Rico Medical Sciences CampusSan JuanPuerto Rico
| | - Katharina Eichler
- Institute of Neurobiology, University of Puerto Rico Medical Sciences CampusSan JuanPuerto Rico
| | - Daichi Yamada
- Division of Biological Science, Graduate School of Science, Nagoya UniversityNagoyaJapan
| | - Davi D Bock
- Department of Neurological Sciences, Larner College of Medicine, University of VermontBurlingtonUnited States
| | - Azusa Kamikouchi
- Division of Biological Science, Graduate School of Science, Nagoya UniversityNagoyaJapan
| | - Andrew M Seeds
- Institute of Neurobiology, University of Puerto Rico Medical Sciences CampusSan JuanPuerto Rico
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4
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Kim H, Horigome M, Ishikawa Y, Li F, Lauritzen JS, Card G, Bock DD, Kamikouchi A. Wiring patterns from auditory sensory neurons to the escape and song-relay pathways in fruit flies. J Comp Neurol 2020; 528:2068-2098. [PMID: 32012264 DOI: 10.1002/cne.24877] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 01/21/2020] [Accepted: 01/22/2020] [Indexed: 02/06/2023]
Abstract
Many animals rely on acoustic cues to decide what action to take next. Unraveling the wiring patterns of the auditory neural pathways is prerequisite for understanding such information processing. Here, we reconstructed the first step of the auditory neural pathway in the fruit fly brain, from primary to secondary auditory neurons, at the resolution of transmission electron microscopy. By tracing axons of two major subgroups of auditory sensory neurons in fruit flies, low-frequency tuned Johnston's organ (JO)-B neurons and high-frequency tuned JO-A neurons, we observed extensive connections from JO-B neurons to the main second-order neurons in both the song-relay and escape pathways. In contrast, JO-A neurons connected strongly to a neuron in the escape pathway. Our findings suggest that heterogeneous JO neuronal populations could be recruited to modify escape behavior whereas only specific JO neurons contribute to courtship behavior. We also found that all JO neurons have postsynaptic sites at their axons. Presynaptic modulation at the output sites of JO neurons could affect information processing of the auditory neural pathway in flies.
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Affiliation(s)
- Hyunsoo Kim
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Mihoko Horigome
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Yuki Ishikawa
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Feng Li
- HHMI Janelia Research Campus, Ashburn, Virginia
| | | | | | - Davi D Bock
- HHMI Janelia Research Campus, Ashburn, Virginia
| | - Azusa Kamikouchi
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
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5
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Blagburn JM. A new method of recording from the giant fiber of Drosophila melanogaster shows that the strength of its auditory inputs remains constant with age. PLoS One 2020; 15:e0224057. [PMID: 31910219 PMCID: PMC6946141 DOI: 10.1371/journal.pone.0224057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 12/13/2019] [Indexed: 11/19/2022] Open
Abstract
There have been relatively few studies of how central synapses age in adult Drosophila melanogaster. In this study we investigate the aging of the synaptic inputs to the Giant Fiber (GF) from auditory Johnston's Organ neurons (JONs). In previously published experiments an indirect assay of this synaptic connection was used; here we describe a new, more direct assay, which allows reliable detection of the GF action potential in the neck connective, and long term recording of its responses to sound. Genetic poisoning using diphtheria toxin expressed in the GF with R68A06-GAL4 was used to confirm that this signal indeed arose from the GF and not from other descending neurons. As before, the sound-evoked action potentials (SEPs) in the antennal nerve were recorded via an electrode inserted at the base of the antenna. It was noted that an action potential in the GF elicited an antennal twitch, which in turn evoked a mechanosensory response from the JONs in the absence of sound. We then used these extracellular recording techniques in males and female of different ages to quantify the response of the JONs to a brief sound impulse, and also to measure the strength of the connection between the JONs and the GF. At no age was there any significant difference between males and females, for any of the parameters measured. The sensitivity of the JONs to a sound impulse approximately doubled between 1 d and 10 d after eclosion, which corresponds to the period when most mating is taking place. Subsequently JON sensitivity decreased with age, being approximately half as sensitive at 20 d and one-third as sensitive at 50 d, as compared to 10 d. However, the strength of the connection between the auditory input and the GF itself remained unchanged with age, although it did show some variability that could mask any small changes.
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Affiliation(s)
- Jonathan M. Blagburn
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, PR, United States of America
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6
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Raad H, Robichon A. The pleiotropic effects of Innexin genes expressed in Drosophila glia encompass wing chemosensory sensilla. J Neurosci Res 2019; 97:1319-1330. [PMID: 31257643 DOI: 10.1002/jnr.24485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 06/05/2019] [Accepted: 06/07/2019] [Indexed: 11/07/2022]
Abstract
The neuroanatomy of Drosophila wing chemosensilla and the analysis of their sensory organ precursor cell lineage have demonstrated that they are surprisingly related to taste perception. The microarchitecture of wing bristles limits the use of electrophysiology methods to investigate wing chemosensory mechanisms. However, by monitoring the fluorescence of the complex calcium/GCaMP, calcium flux triggered upon tastant stimulation was observed within sensilla aligned along the wing anterior nerve. This string of fluorescent puncta was impaired in wings of Innexin 2 (Inx2) mutant flies; although it is unclear whether the Innexin proteins act at the level of the wing imaginal disc, adult wing and/or at both levels. Glial cells known to shelter Innexin(s) expression have no documented role in adult chemosensory sensilla. Our data suggest that Innexin(s) are likely required for the maturation of functional wing chemosensilla in adulthood. The unexpected presence of most Innexin transcripts in adult wing RNAseq data set argues for the expression of Innexin proteins in the larval imaginal wing disc that are continued in wing chemosensilla at adulthood. OPEN PRACTICES: This article has earned an Open Data badge for making publicly available the digitally-shareable data necessary to reproduce the reported results. The data is available as supporting materials and includes the electronic lab notebook. Learn more about the Open Practices badges from the Center for Open Science: https://osf.io/tvyxz/wiki.
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Affiliation(s)
- Hussein Raad
- INRA, CNRS, Université Côte d'Azur, Institut Sophia Agrobiotech, Sophia Antipolis, France.,Lebanese International University, Mazraa, Lebanon
| | - Alain Robichon
- INRA, CNRS, Université Côte d'Azur, Institut Sophia Agrobiotech, Sophia Antipolis, France
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7
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Lapshin DN, Vorontsov DD. Directional and frequency characteristics of auditory neurons in Culex male mosquitoes. J Exp Biol 2019; 222:jeb.208785. [DOI: 10.1242/jeb.208785] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 09/27/2019] [Indexed: 11/20/2022]
Abstract
The paired auditory organ of mosquito, the Johnston's organ (JO), being the receiver of particle velocity component of sound, is directional by its structure. However, to date almost no physiological measurements of its directionality was done. In addition, the recent finding on the grouping of the JO auditory neurons into the antiphase pairs demanded confirmation by different methods. Using the vector superposition of the signals produced by two orthogonally oriented speakers, we measured the directional characteristics of individual units as well as their relations in physiologically distinguishable groups – pairs or triplets. The feedback stimulation method allowed to discriminate responses of the two simultaneously recorded units, and to show that they indeed responded in antiphase. Units of different frequency tuning as well as high-sensitive units (thresholds of 27 dB SPVL and below) were found in every angular sector of the JO, providing the mosquito with the ability to produce complex auditory behaviors.
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Affiliation(s)
- Dmitry N. Lapshin
- Institute for Information Transmission Problems of the Russian Academy of Sciences (Kharkevich Institute) Bolshoy Karetny per. 19, Moscow, 127994, Russia
| | - Dmitry D. Vorontsov
- Koltzov Institute of Developmental Biology Russian Academy of Sciences Vavilova 26, Moscow, 119334, Russia
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8
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Fast intensity adaptation enhances the encoding of sound in Drosophila. Nat Commun 2018; 9:134. [PMID: 29317624 PMCID: PMC5760620 DOI: 10.1038/s41467-017-02453-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 12/01/2017] [Indexed: 12/14/2022] Open
Abstract
To faithfully encode complex stimuli, sensory neurons should correct, via adaptation, for stimulus properties that corrupt pattern recognition. Here we investigate sound intensity adaptation in the Drosophila auditory system, which is largely devoted to processing courtship song. Mechanosensory neurons (JONs) in the antenna are sensitive not only to sound-induced antennal vibrations, but also to wind or gravity, which affect the antenna's mean position. Song pattern recognition, therefore, requires adaptation to antennal position (stimulus mean) in addition to sound intensity (stimulus variance). We discover fast variance adaptation in Drosophila JONs, which corrects for background noise over the behaviorally relevant intensity range. We determine where mean and variance adaptation arises and how they interact. A computational model explains our results using a sequence of subtractive and divisive adaptation modules, interleaved by rectification. These results lay the foundation for identifying the molecular and biophysical implementation of adaptation to the statistics of natural sensory stimuli.
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9
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Azevedo AW, Wilson RI. Active Mechanisms of Vibration Encoding and Frequency Filtering in Central Mechanosensory Neurons. Neuron 2017; 96:446-460.e9. [PMID: 28943231 DOI: 10.1016/j.neuron.2017.09.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 07/26/2017] [Accepted: 09/05/2017] [Indexed: 12/11/2022]
Abstract
To better understand biophysical mechanisms of mechanosensory processing, we investigated two cell types in the Drosophila brain (A2 and B1 cells) that are postsynaptic to antennal vibration receptors. A2 cells receive excitatory synaptic currents in response to both directions of movement: thus, twice per vibration cycle. The membrane acts as a low-pass filter, so that voltage and spiking mainly track the vibration envelope rather than individual cycles. By contrast, B1 cells are excited by only forward or backward movement, meaning they are sensitive to vibration phase. They receive oscillatory synaptic currents at the stimulus frequency, and they bandpass filter these inputs to favor specific frequencies. Different cells prefer different frequencies, due to differences in their voltage-gated conductances. Both Na+ and K+ conductances suppress low-frequency synaptic inputs, so cells with larger voltage-gated conductances prefer higher frequencies. These results illustrate how membrane properties and voltage-gated conductances can extract distinct stimulus features into parallel channels.
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Affiliation(s)
- Anthony W Azevedo
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Rachel I Wilson
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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10
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Lapshin DN, Vorontsov DD. Frequency organization of the Johnston organ in male mosquitoes (Diptera, Culicidae). J Exp Biol 2017; 220:3927-3938. [DOI: 10.1242/jeb.152017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 08/23/2017] [Indexed: 01/18/2023]
Abstract
The Johnston's organs (JO) of mosquitoes are the most complex mechanosensitive organs yet found in insects. Previous findings on behavior of mosquitoes suggest that, together with exceptional sensitivity, their auditory system can discriminate frequencies. Analysis of compound responses of the JO did not provide unambiguous evidence of such discrimination, even less did it help to find its mechanism. Using the feedback stimulation method, we measured the tuning frequencies of the JO sensory neurons. Here we present electrophysiological evidence that male mosquitoes of Culex pipiens possess at least eight groups of auditory neurons which are distinct in their frequency tuning, with individual frequencies ranging from 85 to 470 Hz. Most of the neurons are tuned to 190 – 270 Hz, which corresponds to the difference between a male and a female flight tones. Axons of the JO sensory units propagate graded amplified receptor potentials rather than all-or-none action potentials, are grouped into pairs or triplets and often respond in anti-phase to each other. Some features of the mosquito auditory system suggest an analogy to the retinal mechanisms. Together with our previous findings on frequency tuning in female mosquitoes of different species, this study presents evidence in favor of sophisticated frequency analysis of sound in mosquitoes.
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Affiliation(s)
- Dmitry N. Lapshin
- Institute for Information Transmission Problems of the Russian Academy of Sciences (Kharkevich Institute), Bolshoy Karetny per. 19, Moscow, 127994, Russia
| | - Dmitry D. Vorontsov
- Koltzov Institute of Developmental Biology Russian Academy of Sciences, Vavilova 26, Moscow, 119334, Russia
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11
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Silva IMD, Pereira KDS, Spranghers T, Zanuncio JC, Serrão JE. Antennal Sensilla and Sexual Dimorphism of the Parasitoid Trichospilus pupivorus (Hymenoptera: Eulophidae). MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2016; 22:913-921. [PMID: 27411894 DOI: 10.1017/s1431927616011314] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Sensory structures (sensilla) of insects are present in high number in the antennae are important for perceiving environmental cues. Thus, sensilla play an important role in the localization, discrimination, and acceptance of a possible host by parasitoid insects. The sensilla, classified according to their shape, size, and distribution, may also show sexual dimorphism in insects. The types and distribution of antennal sensilla in female and male parasitoid Trichospilus pupivorus (Ferriere, 1930) (Hymenoptera: Eulophidae) were evaluated. T. pupivorus females had longer antennae than males. Both males and females have ten sensilla types with higher abundance of placoid sensilla in females, which suggest a possible functional dimorphism.
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Affiliation(s)
- Isabel Moreira da Silva
- 1Departamento de Fitotecnia,Universidade Federal de Viçosa,Viçosa,Minas Gerais 36570-900,Brasil
| | - Kleber de Sousa Pereira
- 2Departamento de Entomologia/BIOAGRO,Universidade Federal de Viçosa,Viçosa,Minas Gerais 36570-900,Brasil
| | - Thomas Spranghers
- 3Department of Crop Protection, Faculty of Bioscience Engineering,Ghent University,Coupure Links 653,B-9000 Gent,Belgium
| | - José Cola Zanuncio
- 2Departamento de Entomologia/BIOAGRO,Universidade Federal de Viçosa,Viçosa,Minas Gerais 36570-900,Brasil
| | - José Eduardo Serrão
- 4Departamento de Biologia Geral,Universidade Federal de Viçosa,Viçosa,Minas Gerais 36570-900,Brasil
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12
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Hale ME, Katz HR, Peek MY, Fremont RT. Neural circuits that drive startle behavior, with a focus on the Mauthner cells and spiral fiber neurons of fishes. J Neurogenet 2016; 30:89-100. [DOI: 10.1080/01677063.2016.1182526] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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13
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Pézier AP, Jezzini SH, Bacon JP, Blagburn JM. Shaking B Mediates Synaptic Coupling between Auditory Sensory Neurons and the Giant Fiber of Drosophila melanogaster. PLoS One 2016; 11:e0152211. [PMID: 27043822 PMCID: PMC4833477 DOI: 10.1371/journal.pone.0152211] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 03/10/2016] [Indexed: 11/18/2022] Open
Abstract
The Johnston’s Organ neurons (JONs) form chemical and electrical synapses onto the giant fiber neuron (GF), as part of the neuronal circuit that mediates the GF escape response in Drosophila melanogaster. The purpose of this study was to identify which of the 8 Drosophila innexins (invertebrate gap junction proteins) mediates the electrical connection at this synapse. The GF is known to express Shaking B (ShakB), specifically the ShakB(N+16) isoform only, at its output synapses in the thorax. The shakB2 mutation disrupts these GF outputs and also abolishes JON-GF synaptic transmission. However, the identity of the innexin that forms the presynaptic hemichannels in the JONs remains unknown. We used electrophysiology, immunocytochemistry and dye injection, along with presynaptically-driven RNA interference, to investigate this question. The amplitude of the compound action potential recorded in response to sound from the base of the antenna (sound-evoked potential, or SEP) was reduced by RNAi of the innexins Ogre, Inx3, Inx6 and, to a lesser extent Inx2, suggesting that they could be required in JONs for proper development, excitability, or synchronization of action potentials. The strength of the JON-GF connection itself was reduced to background levels only by RNAi of shakB, not of the other seven innexins. ShakB knockdown prevented Neurobiotin coupling between GF and JONs and removed the plaques of ShakB protein immunoreactivity that are present at the region of contact. Specific shakB RNAi lines that are predicted to target the ShakB(L) or ShakB(N) isoforms alone did not reduce the synaptic strength, implying that it is ShakB(N+16) that is required in the presynaptic neurons. Overexpression of ShakB(N+16) in JONs caused the formation of ectopic dye coupling, whereas ShakB(N) prevented it altogether, supporting this conclusion and also suggesting that gap junction proteins may have an instructive role in synaptic target choice.
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Affiliation(s)
- Adeline P. Pézier
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico, United States of America
| | - Sami H. Jezzini
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico, United States of America
| | - Jonathan P. Bacon
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Jonathan M. Blagburn
- Institute of Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico, United States of America
- * E-mail:
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14
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Engrailed alters the specificity of synaptic connections of Drosophila auditory neurons with the giant fiber. J Neurosci 2014; 34:11691-704. [PMID: 25164665 DOI: 10.1523/jneurosci.1939-14.2014] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We show that a subset of sound-detecting Johnston's Organ neurons (JONs) in Drosophila melanogaster, which express the transcription factors Engrailed (En) and Invected (Inv), form mixed electrical and chemical synaptic inputs onto the giant fiber (GF) dendrite. These synaptic connections are detected by trans-synaptic Neurobiotin (NB) transfer and by colocalization of Bruchpilot-short puncta. We then show that misexpressing En postmitotically in a second subset of sound-responsive JONs causes them to form ectopic electrical and chemical synapses with the GF, in turn causing that postsynaptic neuron to redistribute its dendritic branches into the vicinity of these afferents. We also introduce a simple electrophysiological recording paradigm for quantifying the presynaptic and postsynaptic electrical activity at this synapse, by measuring the extracellular sound-evoked potentials (SEPs) from the antennal nerve while monitoring the likelihood of the GF firing an action potential in response to simultaneous subthreshold sound and voltage stimuli. Ectopic presynaptic expression of En strengthens the synaptic connection, consistent with there being more synaptic contacts formed. Finally, RNAi-mediated knockdown of En and Inv in postmitotic neurons reduces SEP amplitude but also reduces synaptic strength at the JON-GF synapse. Overall, these results suggest that En and Inv in JONs regulate both neuronal excitability and synaptic connectivity.
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15
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Boekhoff-Falk G, Eberl DF. The Drosophila auditory system. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2013; 3:179-91. [PMID: 24719289 DOI: 10.1002/wdev.128] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 08/28/2013] [Accepted: 09/10/2013] [Indexed: 11/10/2022]
Abstract
Development of a functional auditory system in Drosophila requires specification and differentiation of the chordotonal sensilla of Johnston's organ (JO) in the antenna, correct axonal targeting to the antennal mechanosensory and motor center in the brain, and synaptic connections to neurons in the downstream circuit. Chordotonal development in JO is functionally complicated by structural, molecular, and functional diversity that is not yet fully understood, and construction of the auditory neural circuitry is only beginning to unfold. Here, we describe our current understanding of developmental and molecular mechanisms that generate the exquisite functions of the Drosophila auditory system, emphasizing recent progress and highlighting important new questions arising from research on this remarkable sensory system.
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Affiliation(s)
- Grace Boekhoff-Falk
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
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16
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Lehnert BP, Baker AE, Gaudry Q, Chiang AS, Wilson RI. Distinct roles of TRP channels in auditory transduction and amplification in Drosophila. Neuron 2013; 77:115-28. [PMID: 23312520 PMCID: PMC3811118 DOI: 10.1016/j.neuron.2012.11.030] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2012] [Indexed: 11/26/2022]
Abstract
Auditory receptor cells rely on mechanically gated channels to transform sound stimuli into neural activity. Several TRP channels have been implicated in Drosophila auditory transduction, but mechanistic studies have been hampered by the inability to record subthreshold signals from receptor neurons. Here, we develop a non-invasive method for measuring these signals by recording from a central neuron that is electrically coupled to a genetically defined population of auditory receptor cells. We find that the TRPN family member NompC, which is necessary for the active amplification of sound-evoked motion by the auditory organ, is not required for transduction in auditory receptor cells. Instead, NompC sensitizes the transduction complex to movement and precisely regulates the static forces on the complex. In contrast, the TRPV channels Nanchung and Inactive are required for responses to sound, suggesting they are components of the transduction complex. Thus, transduction and active amplification are genetically separable processes in Drosophila hearing.
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Affiliation(s)
- Brendan P Lehnert
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
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17
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Abstract
Most animals exhibit innate auditory behaviors driven by genetically hardwired neural circuits. In Drosophila, acoustic information is relayed by Johnston organ neurons from the antenna to the antennal mechanosensory and motor center (AMMC) in the brain. Here, by using structural connectivity analysis, we identified five distinct types of auditory projection neurons (PNs) interconnecting the AMMC, inferior ventrolateral protocerebrum (IVLP), and ventrolateral protocerebrum (VLP) regions of the central brain. These auditory PNs are also functionally distinct; AMMC-B1a, AMMC-B1b, and AMMC-A2 neurons differ in their responses to sound (i.e., they are narrowly tuned or broadly tuned); one type of audioresponsive IVLP commissural PN connecting the two hemispheres is GABAergic; and one type of IVLP-VLP PN acts as a generalist responding to all tested audio frequencies. Our findings delineate an auditory processing pathway involving AMMC→IVLP→VLP in the Drosophila brain.
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Besson M, Sinakevitch I, Melon C, Iché-Torres M, Birman S. Involvement of the drosophila taurine/aspartate transporter dEAAT2 in selective olfactory and gustatory perceptions. J Comp Neurol 2011; 519:2734-57. [DOI: 10.1002/cne.22649] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Lieber T, Kidd S, Struhl G. DSL-Notch signaling in the Drosophila brain in response to olfactory stimulation. Neuron 2011; 69:468-81. [PMID: 21315258 DOI: 10.1016/j.neuron.2010.12.015] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2010] [Indexed: 12/01/2022]
Abstract
Delta/Serrate/Lag2 (DSL) ligands and their Notch family receptors have profound and pervasive roles in development. They are also expressed in adult tissues, notably in mature neurons and glia in the brain, where their roles are unknown. Here, focusing on the sense of smell in adult Drosophila, we show that Notch is activated in select olfactory receptor neurons (ORNs) in an odorant-specific fashion. This response requires olfactory receptor activity and the Notch ligand Delta. We present evidence that Notch activation depends on synaptic transmission by the ORNs in which the receptors are active and is modulated by the activity of local interneurons in the antennal lobe. It is also subject to regulatory inputs from olfactory receptor activity in other ORNs. These findings identify a correlate of stimulus-dependent brain activity and potentially new forms of neural integration and plasticity.
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Affiliation(s)
- Toby Lieber
- Howard Hughes Medical Institute, Department of Genetics and Development, Columbia University College of Physicians and Surgeons, 701 W 168th Street, New York, NY 10032, USA
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Kamikouchi A, Albert JT, Göpfert MC. Mechanical feedback amplification inDrosophilahearing is independent of synaptic transmission. Eur J Neurosci 2010; 31:697-703. [DOI: 10.1111/j.1460-9568.2010.07099.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Oh HW, Campusano JM, Hilgenberg LGW, Sun X, Smith MA, O'Dowd DK. Ultrastructural analysis of chemical synapses and gap junctions between Drosophila brain neurons in culture. Dev Neurobiol 2008; 68:281-94. [PMID: 18044733 DOI: 10.1002/dneu.20575] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Dissociated cultures from many species have been important tools for exploring factors that regulate structure and function of central neuronal synapses. We have previously shown that cells harvested from brains of late stage Drosophila pupae can regenerate their processes in vitro. Electrophysiological recordings demonstrate the formation of functional synaptic connections as early as 3 days in vitro (DIV), but no information about synapse structure is available. Here, we report that antibodies against pre-synaptic proteins Synapsin and Bruchpilot result in punctate staining of regenerating neurites. Puncta density increases as neuritic plexuses develop over the first 4 DIV. Electron microscopy reveals that closely apposed neurites can form chemical synapses with both pre- and postsynaptic specializations characteristic of many inter-neuronal synapses in the adult brain. Chemical synapses in culture are restricted to neuritic processes and some neurite pairs form reciprocal synapses. GABAergic synapses have a significantly higher percentage of clear core versus granular vesicles than non-GABA synapses. Gap junction profiles, some adjacent to chemical synapses, suggest that neurons in culture can form purely electrical as well as mixed synapses, as they do in the brain. However, unlike adult brain, gap junctions in culture form between neuronal somata as well as neurites, suggesting soma ensheathing glia, largely absent in culture, regulate gap junction location in vivo. Thus pupal brain cultures, which support formation of interneuronal synapses with structural features similar to synapses in adult brain, are a useful model system for identifying intrinsic and extrinsic regulators of central synapse structure as well as function.
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Affiliation(s)
- Hyun-Woo Oh
- Department of Anatomy and Neurobiology, University of California, Irvine, California 92697-1280, USA
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22
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Abstract
The reproductive biology of Drosophila melanogaster is described and critically discussed, primarily with regard to genetic studies of sex-specific behavior and its neural underpinnings. The investigatory history of this system includes, in addition to a host of recent neurobiological analyses of reproductive phenotypes, studies of mating as well as the behaviors leading up to that event. Courtship and mating have been delved into mostly with regard to male-specific behavior and biology, although a small number of studies has also pointed to the neural substrates of female reproduction. Sensory influences on interactions between courting flies have long been studied, partly by application of mutants and partly by surgical experiments. More recently, molecular-genetic approaches to sensations passing between flies in reproductive contexts have aimed to "dissect" further the meaning of separate sensory modalities. Notable among these are olfactory and contact-chemosensory stimuli, which perhaps have received an inordinate amount of attention in terms of the possibility that they could comprise the key cues involved in triggering and sustaining courtship actions. But visual and auditory stimuli are heavily involved as well--appreciated mainly from older experiments, but analyzable further using elementary approaches (single-gene mutations mutants and surgeries), as well as by applying the molecularly defined factors alluded to above. Regarding regulation of reproductive behavior by components of Drosophila's central nervous system (CNS), once again significant invigoration of the relevant inquiries has been stimulated and propelled by identification and application of molecular-genetic materials. A distinct plurality of the tools applied involves transposons inserted in the fly's chromosomes, defining "enhancer-trap" strains that can be used to label various portions of the nervous system and, in parallel, disrupt their structure and function by "driving" companion transgenes predesigned for these experimental purposes. Thus, certain components of interneuronal routes, functioning along pathways whose starting points are sensory reception by the peripheral nervous system (PNS), have been manipulated to enhance appreciation of sexually important sensory modalities, as well as to promote understanding of where such inputs end up within the CNS: Where are reproductively related stimuli processed, such that different kinds of sensation would putatively be integrated to mediate sex-specific behavioral readouts? In line with generic sensory studies that have tended to concentrate on chemical stimuli, PNS-to-CNS pathways focused upon in reproductive experiments relying on genic enhancers have mostly involved smell and taste. Enhancer traps have also been applied to disrupt various regions within the CNS to ask about the various ganglia, and portions thereof, that contribute to male- or female-specific behavior. These manipulations have encompassed structural or functional disruptions of such regions as well as application of molecular-genetic tricks to feminize or masculinize a given component of the CNS. Results of such experiments have, indeed, identified certain discrete subsets of centrally located ganglia that, on the one hand, lead to courtship defects when disrupted or, on the other, must apparently maintain sex-specific identity if the requisite courtship actions are to be performed. As just implied, perturbations of certain neural tissues not based on manipulating "sex factors" might lead to reproductive behavioral abnormalities, even though changing the sexual identity of such structures would not necessarily have analogous consequences. It has been valuable to uncover these sexually significant subsets of the Drosophila nervous system, although it must be said that not all of the transgenically based dissection outcomes are in agreement. Thus, the good news is that not all of the CNS is devoted to courtship control, whereby any and all locales disrupted might have led to sex-specific deficits; but the bad news is that the enhancer-trap approach to these matters has not led to definitive homing-in on some tractable number of mutually agreed-upon "courtship centers" within the brain or within the ventral nerve cord (VNC). The latter neural region, which comprises about half of the fly's CNS, is underanalyzed as to its sex-specific significance: How, for example, are various kinds of sensory inputs to posteriorly located PNS structures processed, such that they eventually end up modulating brain functions underlying courtship? And how are sex-specific motor outputs mediated by discrete collections of neurons within VNC ganglia--so that, for instance, male-specific whole-animal motor actions and appendage usages are evoked? These behaviors can be thought of as fixed action patterns. But it is increasingly appreciated that elements of the fly's reproductive behavior can be modulated by previous experience. In this regard, the neural substrates of conditioned courtship are being more and more analyzed, principally by further usages of various transgenic types. Additionally, a set of molecular neurogenetic experiments devoted to experience-dependent courtship was based on manipulations of a salient "sex gene" in D. melanogaster. This well-defined factor is called fruitless (fru). The gene, its encoded products, along with their behavioral and neurobiological significance, have become objects of frenetic attention in recent years. How normal, mutated, and molecularly manipulated forms of fru seem to be generating a good deal of knowledge and insight about male-specific courtship and mating is worthy of much attention. This previews the fact that fruitless matters are woven throughout this chapter as well as having a conspicuous section allocated to them. Finally, an acknowledgment that the reader is being subjected to lengthy preview of an article about this subject is given. This matter is mentioned because--in conjunction with the contemporary broadening and deepening of this investigatory area--brief summaries of its findings are appearing with increasing frequency. This chapter will, from time to time, present our opinion that a fair fraction of the recent minireviews are replete with too many catch phrases about what is really known. This is one reason why the treatment that follows not only attempts to describe the pertinent primary reports in detail but also pauses often to discuss our views about current understandings of sex-specific behavior in Drosophila and its underlying biology.
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Allen MJ, Murphey RK. The chemical component of the mixed GF-TTMn synapse in Drosophila melanogaster uses acetylcholine as its neurotransmitter. Eur J Neurosci 2007; 26:439-45. [PMID: 17650116 PMCID: PMC1974813 DOI: 10.1111/j.1460-9568.2007.05686.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The largest central synapse in adult Drosophila is a mixed electro-chemical synapse whose gap junctions require the product of the shaking-B (shak-B) gene. Shak-B2 mutant flies lack gap junctions at this synapse, which is between the giant fibre (GF) and the tergotrochanteral motor neuron (TTMn), but it still exhibits a long latency response upon GF stimulation. We have targeted the expression of the light chain of tetanus toxin to the GF, to block chemical transmission, in shak-B2 flies. The long latency response in the tergotrochanteral muscle (TTM) was abolished indicating that the chemical component of the synapse mediates this response. Attenuation of GAL4-mediated labelling by a cha-GAL80 transgene, reveals the GF to be cholinergic. We have used a temperature-sensitive allele of the choline acetyltransferase gene (chats2) to block cholinergic synapses in adult flies and this also abolished the long latency response in shak-B2 flies. Taken together the data provide evidence that both components of this mixed synapse are functional and that the chemical neurotransmitter between the GF and the TTMn is acetylcholine. Our findings show that the two components of this synapse can be separated to allow further studies into the mechanisms by which mixed synapses are built and function.
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Affiliation(s)
- Marcus J Allen
- Department of Biosciences, University of Kent, Canterbury, Kent, UK.
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Ai H, Nishino H, Itoh T. Topographic organization of sensory afferents of Johnston's organ in the honeybee brain. J Comp Neurol 2007; 502:1030-46. [PMID: 17444491 DOI: 10.1002/cne.21341] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Johnston's organ (JO) in insects is a multicellular mechanosensory organ stimulated by movement of the distal part of the antenna. In honeybees JO is thought to be a primary sensor detecting air-particle movements caused by the waggling dance of conspecifics. In this study projection patterns of JO afferents within the brain were investigated. About 720 somata, distributed around the periphery of the second segment of the antenna (pedicel), were divided into three subgroups based on their soma location: an anterior group, a ventral group, and a dorsal group. These groups sent axons to different branches (N2 to N4) diverged from the antennal nerve. Dye injection into individual nerve branches revealed that all three groups of afferents, having fine collaterals in the dorsal lobe, sent axons broadly through tracts T6I, T6II, and T6III to terminate ipsilaterally in the medial posterior protocerebral lobe, the dorsal region of the subesophageal ganglion, and the central posterior protocerebral lobe, respectively. Within these termination fields only axon terminals running in T6I were characterized by thick processes with large varicosities. Differential staining using fluorescent dyes revealed that the axon terminals of the three groups were spatially segregated, especially in T6I, showing some degree of somatotopy. This spatial segregation was not observed in axon terminals running in other tracts. Our results show that projection patterns of JO afferents in the honeybee brain fundamentally resemble those in the dipteran brain. The possible roles of extensive termination fields of JO afferents in parallel processings of mechanosensory signals are discussed.
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Affiliation(s)
- Hiroyuki Ai
- Division of Biology, Department of Earth System Science, Fukuoka University, Fukuoka 814-0180, Japan.
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25
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Baker DA, Beckingham KM, Armstrong JD. Functional dissection of the neural substrates for gravitaxic maze behavior in Drosophila melanogaster. J Comp Neurol 2007; 501:756-64. [PMID: 17299758 DOI: 10.1002/cne.21257] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In animals, sensing gravity is supported by mechanosensory neurons that send information to the central brain for integration along with other modalities. In Drosophila, candidate sensory organs for detecting the gravity vector were predicted from the results of a recent forward genetic screen. This analysis also suggested possible roles for the central complex and antennal system in Drosophila. Using the same vertical maze assay employed in the original screen, we investigated the roles of these candidate neural structures by spatial and temporal inactivation of synaptic transmission with the GAL4/UAS-shibire[ts1] system. We correlate changes in the maze behavior of flies with specific inhibition of synaptic transmission for key brain neuropil that includes the central complex and antenno-glomerular tract. Further, our results point toward a minimal, or nonexistent, role for the mushroom bodies.
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Affiliation(s)
- Dean Adam Baker
- School of Informatics, University of Edinburgh, Edinburgh, UK
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Schlurmann M, Hausen K. Motoneurons of the flight power muscles of the blowflyCalliphora erythrocephala: Structures and mutual dye coupling. J Comp Neurol 2007; 500:448-64. [PMID: 17120285 DOI: 10.1002/cne.21182] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The morphologies of the motoneurons of the dorsolongitudinal and the three dorsoventral flight power muscles (DLM, DVM 1-3) of Calliphora were investigated by means of cobalt backfills and intracellular biocytin stainings. The DLM is innervated by four prothoracic motoneurons supplying the four ventral muscle fibers and one mesothoracic motoneuron supplying the two dorsal fibers. The three fibers of the DVM 1 and the two fibers of the DVM 2 are innervated by five mesothoracic motoneurons, whereas the two fibers of the DVM 3 are innervated by two prothoracic motoneurons. In general, the motoneurons of each muscle have a common ventral soma cluster located in a characteristic position on the ipsilateral side of the thoracic ganglion, show similar dendritic arborizations in the mesothoracic wing neuropil, and have the same axon pathway. Only the soma of the common motoneuron of two dorsal fibers of the DLM is situated dorsally in the contralateral hemiganglion. The motoneurons of each muscle were found to be strongly dye coupled with each other, indicating that they are connected by gap junctions. In addition, the motoneurons of each muscle establish characteristic coupling patterns with the motoneurons of the other flight power muscles on both sides of the thorax and with two bilateral groups of local mesothoracic interneurons. The revealed coupling patterns are assumed to be of major relevance for the generation the characteristic, rhythmic flight activity of the motoneurons described in previous studies.
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Affiliation(s)
- M Schlurmann
- Zoologisches Institut, Universität Köln, 50923 Köln, Germany.
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Eberl DF, Boekhoff-Falk G. Development of Johnston's organ in Drosophila. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2007; 51:679-87. [PMID: 17891726 PMCID: PMC3417114 DOI: 10.1387/ijdb.072364de] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Hearing is a specialized mechanosensory modality that is refined during evolution to meet the particular requirements of different organisms. In the fruitfly, Drosophila, hearing is mediated by Johnston's organ, a large chordotonal organ in the antenna that is exquisitely sensitive to the near-field acoustic signal of courtship songs generated by male wing vibration. We summarize recent progress in understanding the molecular genetic determinants of Johnston's organ development and discuss surprising differences from other chordotonal organs that likely facilitate hearing. We outline novel discoveries of active processes that generate motion of the antenna for acute sensitivity to the stimulus. Finally, we discuss further research directions that would probe remaining questions in understanding Johnston's organ development, function and evolution.
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Affiliation(s)
- Daniel F Eberl
- Department of Biology, University of Iowa, Iowa City, IA 52242-1324, USA.
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