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Sato DS, Nakamura M, Teresa Aguado M, Miura T. Secondary-tail formation during stolonization in the Japanese green syllid, Megasyllis nipponica. Evol Dev 2024; 26:e12477. [PMID: 38644594 DOI: 10.1111/ede.12477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 03/28/2024] [Accepted: 04/03/2024] [Indexed: 04/23/2024]
Abstract
Benthic annelids belonging to the family Syllidae show a distinctive sexual reproduction mode called "stolonization," in which posterior segments are transformed into a reproductive individual-like unit called a "stolon." Megasyllis nipponica forms a stolon head and a secondary tail in the middle of the trunk before a stolon detaches, while, in the case of posterior amputation, posterior regeneration initiates at the wound after amputation. To understand the difference between posterior regeneration and secondary-tail formation during stolonization, detailed comparisons between the developmental processes of these two tail-formation types were performed in this study. Morphological and inner structural observations (i.e., cell proliferation and muscular/nervous development) showed that some processes of posterior regeneration, such as blastema formation and muscular/nervous regeneration at the amputation site, are missing during secondary-tail formation. In contrast, the secondary tail showed some unique features, such as the formation of ventrolateral half-tail buds that later fused in the middle and muscle/nerve branches formed before the detachment of the stolon. These novel features in the process of stolonization are suggested to be adaptive since the animals need to recover a posterior end quickly to stolonize again.
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Affiliation(s)
- Daisuke S Sato
- Misaki Marine Biological Station, The University of Tokyo, Miura, Kanagawa, Japan
| | - Mayuko Nakamura
- Misaki Marine Biological Station, The University of Tokyo, Miura, Kanagawa, Japan
| | - María Teresa Aguado
- Animal Evolution & Biodiversity, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Toru Miura
- Misaki Marine Biological Station, The University of Tokyo, Miura, Kanagawa, Japan
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Nakamura M, Oguchi K, Sato DS, Kato S, Okanishi M, Hayashi Y, Aguado MT, Miura T. Morphological, histological and gene-expression analyses on stolonization in the Japanese Green Syllid, Megasyllis nipponica (Annelida, Syllidae). Sci Rep 2023; 13:19419. [PMID: 37993494 PMCID: PMC10665476 DOI: 10.1038/s41598-023-46358-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 10/31/2023] [Indexed: 11/24/2023] Open
Abstract
Benthic annelids belonging to the family Syllidae (Annelida, Errantia, Phyllodocida) exhibit a unique reproduction mode called "schizogamy" or "stolonization", in which the posterior body part filled with gametes detaches from the original body, as a reproductive unit (stolon) that autonomously swims and spawns. In this study, morphological and histological observations on the developmental processes during stolonization were carried out in Megasyllis nipponica. Results suggest that the stolon formation started with maturation of gonads, followed by the formation of a head ganglion in the anteriormost segment of the developing stolon. Then, the detailed stolon-specific structures such as stolon eyes and notochaetae were formed. Furthermore, expression profiles of genes involved in the anterior-posterior identity (Hox genes), head determination, germ-line, and hormone regulation were compared between anterior and posterior body parts during the stolonization process. The results reveal that, in the posterior body part, genes for gonadal development were up-regulated, followed by hormone-related genes and head-determination genes. Unexpectedly, Hox genes known to identify body parts along the anterior-posterior axis showed no significant temporal expression changes. These findings suggest that during stolonization, gonad development induces the head formation of a stolon, without up-regulation of anterior Hox genes.
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Affiliation(s)
- Mayuko Nakamura
- Misaki Marine Biological Station, School of Science, The University of Tokyo, Misaki, Miura, Kanagawa, 238-0225, Japan
| | - Kohei Oguchi
- Misaki Marine Biological Station, School of Science, The University of Tokyo, Misaki, Miura, Kanagawa, 238-0225, Japan
| | - Daisuke S Sato
- Misaki Marine Biological Station, School of Science, The University of Tokyo, Misaki, Miura, Kanagawa, 238-0225, Japan
| | - Sumika Kato
- Misaki Marine Biological Station, School of Science, The University of Tokyo, Misaki, Miura, Kanagawa, 238-0225, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo, Bunkyo, Tokyo, 113-0033, Japan
| | - Masanori Okanishi
- Misaki Marine Biological Station, School of Science, The University of Tokyo, Misaki, Miura, Kanagawa, 238-0225, Japan
- Faculty of Human Environmental Studies, Hiroshima Shudo University, Ozuka-Higashi, Asaminami, Hiroshima, 731-3195, Japan
| | - Yoshinobu Hayashi
- Department of Biology, Keio University, Hiyoshi, Yokohama, 223-8521, Japan
| | - M Teresa Aguado
- Animal Evolution and Biodiversity, Georg-August-Universität Göttingen, 37073, Göttingen, Germany
| | - Toru Miura
- Misaki Marine Biological Station, School of Science, The University of Tokyo, Misaki, Miura, Kanagawa, 238-0225, Japan.
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Hayashi Y, Oguchi K, Nakamura M, Koshikawa S, Miura T. Construction of a massive genetic resource by transcriptome sequencing and genetic characterization of Megasyllis nipponica (Annelida: Syllidae). Genes Genet Syst 2022; 97:153-166. [PMID: 36070927 DOI: 10.1266/ggs.21-00137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Understanding the processes and consequences of the morphological diversity of organisms is one of the major goals of evolutionary biology. Studies on the evolution of developmental mechanisms of morphologies, or evo-devo, have been extensively conducted in many taxa and have revealed many interesting phenomena at the molecular level. However, many other taxa exhibiting intriguing morphological diversity remain unexplored in the field of evo-devo. Although the annelid family Syllidae shows spectacular diversity in morphological development associated with reproduction, its evo-devo study, especially on molecular development, has progressed slowly. In this study, we focused on Megasyllis nipponica as a new model species for evo-devo in syllids and performed transcriptome sequencing to develop a massive genetic resource, which will be useful for future molecular studies. From the transcriptome data, we identified candidate genes that are likely involved in morphogenesis, including genes involved in hormone regulation, sex determination and appendage development. Furthermore, a computational analysis of the transcriptome sequence data indicated the occurrence of DNA methylation in coding regions of the M. nipponica genome. In addition, flow cytometry analysis showed that the genome size of M. nipponica was approximately 524 megabases. These results facilitate the study of morphogenesis in molecular terms and contribute to our understanding of the morphological diversity in syllids.
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Affiliation(s)
| | - Kohei Oguchi
- Misaki Marine Biological Station, School of Science, The University of Tokyo.,National Institute of Advanced Industrial Science and Technology (AIST)
| | - Mayuko Nakamura
- Misaki Marine Biological Station, School of Science, The University of Tokyo
| | - Shigeyuki Koshikawa
- Faculty of Environmental Earth Science, Hokkaido University.,Graduate School of Environmental Science, Hokkaido University
| | - Toru Miura
- Misaki Marine Biological Station, School of Science, The University of Tokyo
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