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\n \n\n \n \n Asai, M., Miyazawa, H., Yanase, R., Inaba, K., & Nakano, H.\n\n\n \n \n \n \n \n A new species of Acoela possessing a middorsal appendage with a possible sensory function.\n \n \n \n \n\n\n \n\n\n\n Zoological Science, 39(1): 147–156. January 2022.\n \n\n\n\n
\n\n\n\n \n \n \"APaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n  \n \n 36 downloads\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{asai_new_2022,\n\ttitle = {A new species of {Acoela} possessing a middorsal appendage with a possible sensory function},\n\tvolume = {39},\n\tissn = {0289-0003},\n\turl = {https://bioone.org/journals/zoological-science/volume-39/issue-1/zs210058/A-New-Species-of-Acoela-Possessing-a-Middorsal-Appendage-with/10.2108/zs210058.full},\n\tdoi = {10.2108/zs210058},\n\tnumber = {1},\n\turldate = {2022-01-25},\n\tjournal = {Zoological Science},\n\tauthor = {Asai, Masashi and Miyazawa, Hideyuki and Yanase, Ryuji and Inaba, Kazuo and Nakano, Hiroaki},\n\tmonth = jan,\n\tyear = {2022},\n\tpages = {147--156},\n}\n\n
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\n \n\n \n \n Hayakawa, E., Guzman, C., Horiguchi, O., Kawano, C., Shiraishi, A., Mohri, K., Lin, M., Nakamura, R., Nakamura, R., Kawai, E., Komoto, S., Jokura, K., Shiba, K., Shigenobu, S., Satake, H., Inaba, K., & Watanabe, H.\n\n\n \n \n \n \n \n Mass spectrometry of short peptides reveals common features of metazoan peptidergic neurons.\n \n \n \n \n\n\n \n\n\n\n Nature Ecology & Evolution, 6(10): 1438–1448. August 2022.\n \n\n\n\n
\n\n\n\n \n \n \"MassPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{hayakawa_mass_2022,\n\ttitle = {Mass spectrometry of short peptides reveals common features of metazoan peptidergic neurons},\n\tvolume = {6},\n\tissn = {2397-334X},\n\turl = {https://www.nature.com/articles/s41559-022-01835-7},\n\tdoi = {10.1038/s41559-022-01835-7},\n\tabstract = {Abstract\n            The evolutionary origins of neurons remain unknown. Although recent genome data of extant early-branching animals have shown that neural genes existed in the common ancestor of animals, the physiological and genetic properties of neurons in the early evolutionary phase are still unclear. Here, we performed a mass spectrometry-based comprehensive survey of short peptides from early-branching lineages Cnidaria, Porifera and Ctenophora. We identified a number of mature ctenophore neuropeptides that are expressed in neurons associated with sensory, muscular and digestive systems. The ctenophore peptides are stored in vesicles in cell bodies and neurites, suggesting volume transmission similar to that of cnidarian and bilaterian peptidergic systems. A comparison of genetic characteristics revealed that the peptide-expressing cells of Cnidaria and Ctenophora express the vast majority of genes that have pivotal roles in maturation, secretion and degradation of neuropeptides in Bilateria. Functional analysis of neuropeptides and prediction of receptors with machine learning demonstrated peptide regulation of a wide range of target effector cells, including cells of muscular systems. The striking parallels between the peptidergic neuronal properties of Cnidaria and Bilateria and those of Ctenophora, the most basal neuron-bearing animals, suggest a common evolutionary origin of metazoan peptidergic nervous systems.},\n\tlanguage = {en},\n\tnumber = {10},\n\turldate = {2022-10-25},\n\tjournal = {Nature Ecology \\& Evolution},\n\tauthor = {Hayakawa, Eisuke and Guzman, Christine and Horiguchi, Osamu and Kawano, Chihiro and Shiraishi, Akira and Mohri, Kurato and Lin, Mei-Fang and Nakamura, Ryotaro and Nakamura, Ryo and Kawai, Erina and Komoto, Shinya and Jokura, Kei and Shiba, Kogiku and Shigenobu, Shuji and Satake, Honoo and Inaba, Kazuo and Watanabe, Hiroshi},\n\tmonth = aug,\n\tyear = {2022},\n\tpages = {1438--1448},\n}\n\n
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\n Abstract The evolutionary origins of neurons remain unknown. Although recent genome data of extant early-branching animals have shown that neural genes existed in the common ancestor of animals, the physiological and genetic properties of neurons in the early evolutionary phase are still unclear. Here, we performed a mass spectrometry-based comprehensive survey of short peptides from early-branching lineages Cnidaria, Porifera and Ctenophora. We identified a number of mature ctenophore neuropeptides that are expressed in neurons associated with sensory, muscular and digestive systems. The ctenophore peptides are stored in vesicles in cell bodies and neurites, suggesting volume transmission similar to that of cnidarian and bilaterian peptidergic systems. A comparison of genetic characteristics revealed that the peptide-expressing cells of Cnidaria and Ctenophora express the vast majority of genes that have pivotal roles in maturation, secretion and degradation of neuropeptides in Bilateria. Functional analysis of neuropeptides and prediction of receptors with machine learning demonstrated peptide regulation of a wide range of target effector cells, including cells of muscular systems. The striking parallels between the peptidergic neuronal properties of Cnidaria and Bilateria and those of Ctenophora, the most basal neuron-bearing animals, suggest a common evolutionary origin of metazoan peptidergic nervous systems.\n
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\n \n\n \n \n Ito, T., Morita, M., Okuno, S., Inaba, K., Shiba, K., Munehara, H., Koya, Y., Homma, M., & Awata, S.\n\n\n \n \n \n \n \n Fertilization modes and the evolution of sperm characteristics in marine fishes: Paired comparisons of externally and internally fertilizing species.\n \n \n \n \n\n\n \n\n\n\n Ecology and Evolution, 12(12). December 2022.\n \n\n\n\n
\n\n\n\n \n \n \"FertilizationPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{ito_fertilization_2022,\n\ttitle = {Fertilization modes and the evolution of sperm characteristics in marine fishes: {Paired} comparisons of externally and internally fertilizing species},\n\tvolume = {12},\n\tissn = {2045-7758, 2045-7758},\n\tshorttitle = {Fertilization modes and the evolution of sperm characteristics in marine fishes},\n\turl = {https://onlinelibrary.wiley.com/doi/10.1002/ece3.9562},\n\tdoi = {10.1002/ece3.9562},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2022-12-07},\n\tjournal = {Ecology and Evolution},\n\tauthor = {Ito, Takeshi and Morita, Masaya and Okuno, Seiya and Inaba, Kazuo and Shiba, Kogiku and Munehara, Hiroyuki and Koya, Yasunori and Homma, Mitsuo and Awata, Satoshi},\n\tmonth = dec,\n\tyear = {2022},\n}\n\n
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\n \n\n \n \n Jokura, K., Sato, Y., Shiba, K., & Inaba, K.\n\n\n \n \n \n \n \n Two distinct compartments of a ctenophore comb plate provide structural and functional integrity for the motility of giant multicilia.\n \n \n \n \n\n\n \n\n\n\n Current Biology,S0960982222016037. October 2022.\n \n\n\n\n
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@article{jokura_two_2022,\n\ttitle = {Two distinct compartments of a ctenophore comb plate provide structural and functional integrity for the motility of giant multicilia},\n\tissn = {09609822},\n\turl = {https://linkinghub.elsevier.com/retrieve/pii/S0960982222016037},\n\tdoi = {10.1016/j.cub.2022.09.061},\n\tlanguage = {en},\n\turldate = {2022-10-25},\n\tjournal = {Current Biology},\n\tauthor = {Jokura, Kei and Sato, Yu and Shiba, Kogiku and Inaba, Kazuo},\n\tmonth = oct,\n\tyear = {2022},\n\tpages = {S0960982222016037},\n}\n\n
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\n \n\n \n \n Nakano, H., Isowa, Y., & Inaba, K.\n\n\n \n \n \n \n \n JAMBIO and its coastal organism joint surveys: Network of marine stations explores Japanese coastal biota.\n \n \n \n \n\n\n \n\n\n\n Zoological Science, 39(1): 1–6. February 2022.\n \n\n\n\n
\n\n\n\n \n \n \"JAMBIOPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n  \n \n 30 downloads\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{nakano_jambio_2022,\n\ttitle = {{JAMBIO} and its coastal organism joint surveys: {Network} of marine stations explores {Japanese} coastal biota},\n\tvolume = {39},\n\tissn = {0289-0003},\n\tshorttitle = {{JAMBIO} and {Its} {Coastal} {Organism} {Joint} {Surveys}},\n\turl = {https://bioone.org/journals/zoological-science/volume-39/issue-1/zs210069/JAMBIO-and-Its-Coastal-Organism-Joint-Surveys--Network-of/10.2108/zs210069.full},\n\tdoi = {10.2108/zs210069},\n\tnumber = {1},\n\turldate = {2022-02-04},\n\tjournal = {Zoological Science},\n\tauthor = {Nakano, Hiroaki and Isowa, Yukinobu and Inaba, Kazuo},\n\tmonth = feb,\n\tyear = {2022},\n\tpages = {1--6},\n}\n\n
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\n \n\n \n \n Shiba, K., & Inaba, K.\n\n\n \n \n \n \n \n The roles of two CNG channels in the regulation of ascidian sperm chemotaxis.\n \n \n \n \n\n\n \n\n\n\n International Journal of Molecular Sciences, 23(3): 1648. January 2022.\n \n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 18 downloads\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{shiba_roles_2022,\n\ttitle = {The roles of two {CNG} channels in the regulation of ascidian sperm chemotaxis},\n\tvolume = {23},\n\tissn = {1422-0067},\n\turl = {https://www.mdpi.com/1422-0067/23/3/1648},\n\tdoi = {10.3390/ijms23031648},\n\tabstract = {Spermatozoa sense and respond to their environmental signals to ensure fertilization success. Reception and transduction of signals are reflected rapidly in sperm flagellar waveforms and swimming behavior. In the ascidian Ciona intestinalis (type A; also called C. robusta), an egg-derived sulfated steroid called SAAF (sperm activating and attracting factor), induces both sperm motility activation and chemotaxis. Two types of CNG (cyclic nucleotide-gated) channels, Ci-tetra KCNG (tetrameric, cyclic nucleotide-gated, K+-selective) and Ci-HCN (hyperpolarization-activated and cyclic nucleotide-gated), are highly expressed in Ciona testis from the comprehensive gene expression analysis. To elucidate the sperm signaling pathway to regulate flagellar motility, we focus on the role of CNG channels. In this study, the immunochemical analysis revealed that both CNG channels are expressed in Ciona sperm and localized to sperm flagella. Sperm motility analysis and Ca2+ imaging during chemotaxis showed that CNG channel inhibition affected the changes in flagellar waveforms and Ca2+ efflux needed for the chemotactic turn. These results suggest that CNG channels in Ciona sperm play a vital role in regulating sperm motility and intracellular Ca2+ regulation during chemotaxis.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2022-02-07},\n\tjournal = {International Journal of Molecular Sciences},\n\tauthor = {Shiba, Kogiku and Inaba, Kazuo},\n\tmonth = jan,\n\tyear = {2022},\n\tpages = {1648},\n}\n\n
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\n Spermatozoa sense and respond to their environmental signals to ensure fertilization success. Reception and transduction of signals are reflected rapidly in sperm flagellar waveforms and swimming behavior. In the ascidian Ciona intestinalis (type A; also called C. robusta), an egg-derived sulfated steroid called SAAF (sperm activating and attracting factor), induces both sperm motility activation and chemotaxis. Two types of CNG (cyclic nucleotide-gated) channels, Ci-tetra KCNG (tetrameric, cyclic nucleotide-gated, K+-selective) and Ci-HCN (hyperpolarization-activated and cyclic nucleotide-gated), are highly expressed in Ciona testis from the comprehensive gene expression analysis. To elucidate the sperm signaling pathway to regulate flagellar motility, we focus on the role of CNG channels. In this study, the immunochemical analysis revealed that both CNG channels are expressed in Ciona sperm and localized to sperm flagella. Sperm motility analysis and Ca2+ imaging during chemotaxis showed that CNG channel inhibition affected the changes in flagellar waveforms and Ca2+ efflux needed for the chemotactic turn. These results suggest that CNG channels in Ciona sperm play a vital role in regulating sperm motility and intracellular Ca2+ regulation during chemotaxis.\n
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\n \n\n \n \n Shibata, D., Morita, M., Sato, Y., Shiba, K., Kitanobo, S., Yokoya, R., & Inaba, K.\n\n\n \n \n \n \n \n Axonemal growth and alignment during paraspermatogenesis in the marine gastropod Strombus luhuanus.\n \n \n \n \n\n\n \n\n\n\n Frontiers in Cell and Developmental Biology, 10: 905748. June 2022.\n \n\n\n\n
\n\n\n\n \n \n \"AxonemalPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 18 downloads\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{shibata_axonemal_2022,\n\ttitle = {Axonemal growth and alignment during paraspermatogenesis in the marine gastropod \\textit{{Strombus} luhuanus}},\n\tvolume = {10},\n\tissn = {2296-634X},\n\turl = {https://www.frontiersin.org/articles/10.3389/fcell.2022.905748/full},\n\tdoi = {10.3389/fcell.2022.905748},\n\tabstract = {Parasperm are non-fertilizing sperm that are produced simultaneously with fertile eusperm. They occur in several animal species and show considerable morphological diversity. We investigated the dynamics of axonemes during paraspermatogenesis in the marine snail\n              S. luhuanus\n              . Mature parasperm were characterized by two lateral undulating membranes for motility and many globular vesicles. Axonemes were first observed as brush-like structures that extruded from the anterior region. Multiple axonemes longer than the brush then started to extend inside the cytoplasm towards the posterior region. The mass of the axonemes separated into two lateral rows and formed an undulating membrane that drives bidirectional swimming in the mature parasperm. The central pair of axonemes was aligned in the undulating membrane, resulting in cooperative bend propagation. During paraspermatogenesis, centrioles were largely diminished and localized to the anterior region. CEP290, a major component of the transition zone, showed a broad distribution in the anterior area. Axonemes in the posterior region showed a 9 + 0 structure with both outer and inner arm dyneins. These observations provide a structural basis for understanding the physiological functions of parasperm in marine reproductive strategies.},\n\turldate = {2022-07-12},\n\tjournal = {Frontiers in Cell and Developmental Biology},\n\tauthor = {Shibata, Daisuke and Morita, Masaya and Sato, Yu and Shiba, Kogiku and Kitanobo, Seiya and Yokoya, Ryo and Inaba, Kazuo},\n\tmonth = jun,\n\tyear = {2022},\n\tpages = {905748},\n}\n\n
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\n Parasperm are non-fertilizing sperm that are produced simultaneously with fertile eusperm. They occur in several animal species and show considerable morphological diversity. We investigated the dynamics of axonemes during paraspermatogenesis in the marine snail S. luhuanus . Mature parasperm were characterized by two lateral undulating membranes for motility and many globular vesicles. Axonemes were first observed as brush-like structures that extruded from the anterior region. Multiple axonemes longer than the brush then started to extend inside the cytoplasm towards the posterior region. The mass of the axonemes separated into two lateral rows and formed an undulating membrane that drives bidirectional swimming in the mature parasperm. The central pair of axonemes was aligned in the undulating membrane, resulting in cooperative bend propagation. During paraspermatogenesis, centrioles were largely diminished and localized to the anterior region. CEP290, a major component of the transition zone, showed a broad distribution in the anterior area. Axonemes in the posterior region showed a 9 + 0 structure with both outer and inner arm dyneins. These observations provide a structural basis for understanding the physiological functions of parasperm in marine reproductive strategies.\n
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\n \n\n \n \n Sugiura, K., Shiba, K., Inaba, K., & Matsumoto, M.\n\n\n \n \n \n \n \n Morphological differences in tardigrade spermatozoa induce variation in gamete motility.\n \n \n \n \n\n\n \n\n\n\n BMC Zoology, 7(1): 8. December 2022.\n \n\n\n\n
\n\n\n\n \n \n \"MorphologicalPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 18 downloads\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n\n\n\n
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@article{sugiura_morphological_2022,\n\ttitle = {Morphological differences in tardigrade spermatozoa induce variation in gamete motility},\n\tvolume = {7},\n\tissn = {2056-3132},\n\turl = {https:///bmczool.biomedcentral.com/articles/10.1186/s40850-022-00109-w},\n\tdoi = {10.1186/s40850-022-00109-w},\n\tabstract = {Abstract\n            \n              Background\n              \n                Fertilization is an event at the beginning of ontogeny. Successful fertilization depends on strategies for uniting female and male gametes that developed throughout evolutionary history. In some species of tardigrades, investigations of reproduction have revealed that released spermatozoa swim in the water to reach a female, after which the gametes are stored in her body. The morphology of the spermatozoa includes a coiled nucleus and a species-specific-length acrosome. Although the mating behaviour and morphology of tardigrades have been reported, the motility of male gametes remains unknown. Here, using a high-speed camera, we recorded the spermatozoon motilities of two tardigrades,\n                Paramacrobiotus\n                sp. and\n                Macrobiotus shonaicus,\n                which have longer and shorter spermatozoa, respectively.\n              \n            \n            \n              Results\n              \n                The movement of spermatozoa was faster in\n                Paramacrobiotus\n                sp. than in\n                M. shonaicus\n                , but the beat frequencies of the tails were equal, suggesting that the long tail improved acceleration. In both species, the head part consisting of a coiled nucleus and an acrosome did not swing, in contrast to the tail. The head part of\n                Paramacrobiotus\n                sp. spermatozoa swung harder during turning; in contrast, the tail of\n                M. shonaicus\n                moved more widely than the head. Finally, after mating, the spermatozoa that reached the female aggregated around the cloaca while waiting to enter her body in both tested species.\n              \n            \n            \n              Conclusions\n              \n                This study provides results for the first observations and analyses of individual spermatozoon motility in tardigrades. A comparison of the spermatozoon movements of the two tardigrades suggested that the motilities of the male gametes were affected by morphological differences, where the longer spermatozoa swam faster and the shorter ones showed more stable swimming. Swimming was mainly induced by tail movement, but the long head of\n                Paramacrobiotus\n                sp. spermatozoa might be especially important for turning. In addition, observations of mated female cloacae suggested that the head parts of the spermatozoa were required for aggregation around the cloaca of a mated female.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2022-02-07},\n\tjournal = {BMC Zoology},\n\tauthor = {Sugiura, Kenta and Shiba, Kogiku and Inaba, Kazuo and Matsumoto, Midori},\n\tmonth = dec,\n\tyear = {2022},\n\tpages = {8},\n}\n\n
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\n Abstract Background Fertilization is an event at the beginning of ontogeny. Successful fertilization depends on strategies for uniting female and male gametes that developed throughout evolutionary history. In some species of tardigrades, investigations of reproduction have revealed that released spermatozoa swim in the water to reach a female, after which the gametes are stored in her body. The morphology of the spermatozoa includes a coiled nucleus and a species-specific-length acrosome. Although the mating behaviour and morphology of tardigrades have been reported, the motility of male gametes remains unknown. Here, using a high-speed camera, we recorded the spermatozoon motilities of two tardigrades, Paramacrobiotus sp. and Macrobiotus shonaicus, which have longer and shorter spermatozoa, respectively. Results The movement of spermatozoa was faster in Paramacrobiotus sp. than in M. shonaicus , but the beat frequencies of the tails were equal, suggesting that the long tail improved acceleration. In both species, the head part consisting of a coiled nucleus and an acrosome did not swing, in contrast to the tail. The head part of Paramacrobiotus sp. spermatozoa swung harder during turning; in contrast, the tail of M. shonaicus moved more widely than the head. Finally, after mating, the spermatozoa that reached the female aggregated around the cloaca while waiting to enter her body in both tested species. Conclusions This study provides results for the first observations and analyses of individual spermatozoon motility in tardigrades. A comparison of the spermatozoon movements of the two tardigrades suggested that the motilities of the male gametes were affected by morphological differences, where the longer spermatozoa swam faster and the shorter ones showed more stable swimming. Swimming was mainly induced by tail movement, but the long head of Paramacrobiotus sp. spermatozoa might be especially important for turning. In addition, observations of mated female cloacae suggested that the head parts of the spermatozoa were required for aggregation around the cloaca of a mated female.\n
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