TOP ＞ 一般口演（若手道場）

一般口演（若手道場） 若手道場　感覚系 Wakate Dojo: Sensory Themes 座長：増田 隆博（九州大学大学院薬学研究院薬理学分野）・田中 達英（奈良県立医科大学） 2022年7月1日　9:00～9:15　沖縄コンベンションセンター 会議場B2　第5会場 2WD05m1-01 UNC-7/Innexinによる線虫 C. elegans の温度情報伝達制御機構 UNC-7/Innexin Regulates Transmission of Temperature Information during C. elegans Thermotaxis *中山 愛梨(1)、中野 俊詩(1)、森 郁恵(1) 1. 名古屋大学大学院理学研究科 *Airi Nakayama(1), Shunji Nakano(1), Ikue Mori(1) 1. Graduate School of Science, Nagoya University, Aichi, Japan Keyword: Hemichannel, Gap junction, Innexin, C. elegans Thermotaxis behavior Gap junction components are known to play fundamental roles in the information processing in the nervous system. Innexins and connexins are transmembrane proteins that form gap junction channels and non-junctional hemichannels. How these components precisely control the output of animal complex behavior is unrevealed. Here we report a neural mechanism by which UNC-7/Innexin regulates Caenorhabditis elegans memory-driven behavior, thermotaxis. Well-fed C. elegans can remember the ambient temperature in association with its past cultivation conditions, and when placed on a thermal gradient without food, migrate towards the cultivation temperature. Inspired by our previous finding that INX-4, a member of innexin family in C. elegans, is required for thermotaxis, we conducted a genome-wide survey of innexin genes and showed that UNC-7 is also required for the thermotaxis by acting in the AFD thermosensory neuron; loss or gain of unc-7 activity specifically in AFD caused thermotaxis defects. Calcium imaging revealed that unc-7mutations did not affect temperature-evoked calcium response in AFD, indicating that UNC-7 functions in the downstream of calcium influx. These results indicate that UNC-7 functions in AFD to regulate thermotaxis by controlling transmission of temperature information from AFD. To identify neurons to which temperature information from AFD is transmitted by UNC-7, we conducted cell ablation experiments. We investigated whether the ablation of individual neuron reported as a chemical or electrical synapse partner of AFD suppresses the effect of unc-7, and observed that the ablation of AIY interneuron, which has been shown to form both chemical and electrical synapses with AFD, suppressed the defect caused by unc-7 overexpression. We therefore asked whether UNC-7 in AFD forms a gap junction with AIY but found that none of the innexin genes expressed in AIY affected thermotaxis when overexpressed or knocked out. These results implied that UNC-7 might function as a hemichannel to transmit temperature information from AFD to AIY. Our study suggests that UNC-7 functions as a hemichannel to regulate a memory-driven behavior and provides an excellent opportunity in which to dissect the molecular mechanisms of hemichannel gating in vivo. Through our research, we hope to elucidate the gating dynamics of hemichannel underlying regulation of neural circuit activity and understand how hemichannel activity contributes to generate animal behavior. 2022年7月1日　9:15～9:30　沖縄コンベンションセンター 会議場B2　第5会場 2WD05m1-02 自由行動下のマウスにおける風味弁別行動課題 Flavor discrimination task in free moving mice *塩谷 和基(1,2)、谷隅 勇太(2,3)、村田 航志(4)、大迫　 優真 (2,3)、大貫 朋哉(5)、高宮 渉吾(2,3)、廣川 順也(2)、櫻井 芳雄(2)、眞部 寛之(2) 1. 立命館大学　生命科学部、2. 同志社大学　脳科学研究科　、3. 日本学術振興会特別研究員、4. 福井大学　医学部、5. 理化学研究所　脳神経科学研究センター　学習・記憶神経回路研究チーム *Kazuki Shiotani(1,2), Yuta Tanisumi(2,3), Murata Koshi(4), Osako Yuma(2,3), Ohnuki Tomoya(5), Takamiya Shogo(2,3), Hirokawa Junya(2), Sakurai Yoshio(2), Manabe Hiroyuki(2) 1. College of Life Sciences, Ritsumeikan University, Shiga, Japan, 2. Graduate School of Brain Science, Doshisha University, Kyoto, Japan, 3. Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan, 4. Faculty of Medical Sciences, University of Fukui, Fukui, Japan, 5. Lab. for the Neural Circuitry of Learning and Memory, RIKEN Center for Brain Science, Saitama, Japan Keyword: flavor, medial prefrontal cortex (mPFC), retronasal olfaction, operant conditioning When we eat pleasant foods, flavor sensation is the most important sense to enjoy the foods. Flavor sensation is the multimodality one, ultimately built upon olfactory (odor), gustatory (taste), and other sensory (i.e. sight, texture, and/or sound) inputs. Of these, odor and taste have been of particular interest in flavor research (Small, 2012). Little is known, however, about the neuronal basis of flavor sensation. Because of the measurement limitations faced in elucidating the neural level of flavor perception in humans, we used rodents as a model animals. First, we have established a flavor discrimination behavioral task to clarify whether mice are able to detect differences in flavor. We have established a new behavioral task by modifying a go/no-go discrimination task. The mouse had to discriminate between sucrose water dissolved in amyl acetate (flavored sucrose water) and sucrose water alone. If flavored sucrose water was delivered to the flavor port, the mouse needed to move to and poke its head into the reward port within 5 sec to obtain reward water (go trial). If sucrose water was presented, it was required to prohibit from poking its head into the reward port for 5 sec (no-go trial). To mask the external odor stimulation from the flavored sucrose water, the mouse was simultaneously presented with an odor stimulation of amyl acetate with an olfactometer at the flavor port during nose poking in both go and no-go trials. The accuracy of performance in this task exceeded 75% in about a month. To verify whether the olfactory pathway was necessary for the discrimination, we examined whether the performance accuracy in this task decreased by blocking the olfaction. Mice were intraperitoneally injected with methimazole or removed their olfactory bulb. These mice showed a dramatic decrease in performance accuracy in this task. To verify whether the taste pathway was necessary to discriminate the flavor difference, 20% benzocaine was applied directly to the exposed dorsal surfaces of their tongues. These mice showed no decrease in performance accuracy in this task. These results indicate that the olfactory rather than taste inputs are essential for flavor discrimination. Next, we recorded the neural activities of the medial prefrontal cortex (mPFC) in this task, because mPFC is known as the key region of flavor sensation. We found that mPFC neurons responded to flavor and non-flavor stimuli. Consequently, the present study suggests that the mice can discriminate the flavor difference and mPFC plays the important role in the flavor discrimination. 2022年7月1日　9:30～9:45　沖縄コンベンションセンター 会議場B2　第5会場 2WD05m1-03 ショウジョウバエにおける聴覚ニューロン群の種特異的な応答特性 Species-specific neural responses of the auditory neurons in Drosophila *大橋 拓朗(1)、石川 由希(1)、粟崎 健(2)、蘇 馬賦(1,3)、上川内 あづさ(1,4) 1. 名古屋大学大学院理学研究科、2. 杏林大学医学部、3. 名古屋大学高等研究院、4. 東北大学大学院生命科学研究科 *Takuro Ohashi(1), Yuki Ishikawa(1), Takeshi Awasaki(2), Matthew Paul Su(1,3), Azusa Kamikouchi(1,4) 1. Grad Sch Sci, Nagoya Univ, Aichi, Japan, 2. Sch Med, Kyorin Univ, Tokyo, Japan, 3. IAR, Nagoya Univ, Aichi, Japan, 4. Grad Sch Life Sci, Tohoku Univ, Miyagi, Japan Keyword: EVOLUTION, HEARING, CALCIUM IMAGING, Drosophila Sound plays an significant role in animal communication. To prevent interspecific hybridization, animals have diversified the acoustic signals used in courtship and selectively respond to conspecific sounds. How the neural mechanisms for processing conspecific auditory signals have been diversified in the evolutionary process has not yet been delineated. Drosophila melanogaster is an excellent model to tackle this question because of the existence of both genetic tools and connectomic data, and the importance of acoustic communication during its’ courtship. Male flies produce a pulse song during courtship to increase female copulation receptivity. The interval between pulses, Inter Pulse Interval (IPI), is species-specific; ~35 ms in D. melanogaster, compared to ~55 ms in the sister species D. simulans. Although the auditory neural circuit involved in the recognition of the conspecific song has been investigated in D. melanogaster, how the homologous circuitry is diversified between species remains unknown. To examine how IPI selectivity differs between species at the behavioral level, we first compared female copulation rates when exposed to artificial pulse songs with various IPIs. We found that D. simulans copulated relatively more and quicker compared to D. melanogaster when exposed to songs with longer IPIs. We next compared the morphology of two upstream song-relay neurons (JON and AMMC-B1) between the species by generating novel genetic tools in D. simulans. To label the homologous neurons in both species, we transferred the genetic drivers which label D. melanogaster’s auditory neurons to D. simulans using the PhiC31 system. Using these novel driver lines, we identified a high degree of conservation in the circuit morphology. We also found these neurons share the same cholinergic properties in both species via immunohistochemistry using an Anti-Choline Acetyltransferase antibody. Finally, to compare the sound response properties of AMMC-B1 between species, we observed the neural response to artificial pulse songs with different IPIs. Using a novel model fitting paradigm, we found small, yet significant, interspecific differences in the response properties. The fitting predicted that AMMC-B1 of D. simulans responds less to short 15-ms-IPI songs than that of D. melanogaster. This indicates that the response of the auditory neurons differs between the related species, whose auditory signals are diversified. The interspecific differences of AMMC-B1 responses, which we identified in this study, do not appear to explain their distinct IPI preferences for longer IPIs at the behavioral level. Investigation of changes in the profile of higher-order neurons is necessary to provide further information on the circuit level differences in IPI selectivity between species. 2022年7月1日　9:45～10:00　沖縄コンベンションセンター 会議場B2　第5会場 2WD05m1-04 MAP2の消失が聴覚末梢系の情報伝達に与える影響 Effect of MAP2 loss on signal processing in the auditory peripheral system *田中 一樹(1)、宮坂 知宏(1)、原田 彰宏(2)、小林 耕太(1) 1. 同志社大学大学院生命医科学研究科、2. 大阪大学大学院医学系研究科 *Kazuki Tanaka(1), Tomohiro Miyasaka(1), Akihiro Harada(2), Kohta I Kobayasi(1) 1. Grad Sch LifeSci, Univ of Doshisha, Kyoto, Japan, 2. Grad Sch Med, Univ of Osaka, Osaka, Japan Keyword: MAP2, Auditory signal processing, Hearing loss, Outer hair cell A microtubule-associated protein 2 (MAP2) is one of the major neural MAPs and evolutionally conserved from C. elegans to mammals. This suggests its importance in neuronal function. However, the significance of MAP2 for the development and maintenance of nervous system functions remains unclear. To elucidate the function of MAP2 in vivo, we observed the behavior of MAP2 knockout (MKO) mice, and found that MKO mice develop without any apparent physical abnormalities but show a reduced startle response or avoidance to loud noise. Therefore, we hypothesized that the loss of MAP2 causes hearing loss, and measured the auditory brainstem response (ABR) to 2, 4, 8, 16, 32, 50, 60, 64, 68, and 72 kHz sound stimuli to verify the function of MAP2 in the auditory signal processing. Auditory thresholds of MKO mice were higher than those of WT mice at 4 -32 kHz, with a maximum increase of 40 dB at 16 kHz. WT mice showed ABR from 2 kHz to 64 kHz, but MKO mice did not show ABR above 50 kHz. In addition, MKO mice exhibited an increase in ABR latency and a decrease in amplitude, which are characteristic of sensorineural hearing loss in the peripheral site (e.g., cochlea hair cell, cochlea nerve). To clarify the site of the hearing loss in MKO mice, we observed the localization of MAP2 in the cochlea using wholemount immunostaining. MAP2 was expressed in the cochlear outer hair cells (OHC), inner hair cells (IHC), and cochlear neurons. The amount of MAP2 expression was higher in OHC than in IHC. In addition, the number of both OHCs and IHCs did not change through low to high-frequency regions after MAP2 gene deletion. These results suggest that MAP2 contributes to the maintenance of hearing sensitivity, especially in the high-frequency range, and the contribution of MAP2 to the microtubules rigidity in the OHCs will be discussed as a possible mechanism of hearing loss in the MKO mice.