研究者詳細 - 濱田　麻友子

論文 - 濱田　麻友子

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Tunicate-specific protein Epi-1 is essential for conferring hydrophilicity to the larval tunic in the ascidian Ciona 査読

Kazu Kuroiwa, Kaoru Mita-Yoshida, Mayuko Hamada, Akiko Hozumi, Atsuo S. Nishino, Yasunori Sasakura

Developmental Biology 520 41 - 52 2025年4月

Environmental DNA Reveals the Impact of Submarine Groundwater Discharge on the Spatial Variability of Coastal Fish Diversity 査読

Nguyen Hong Nhat, Mitsuyo Saito, Shin-ichi Onodera, Mayuko Hamada, Fujio Hyodo, Hideaki Nagare

Biology 13 ( 8 ) 609 - 609 2024年8月

掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG

Submarine groundwater discharge (SGD) has recently been recognized as an influential factor in coastal ecosystems; however, little research has been conducted on its effects on coastal fish diversity. To investigate the relationship between SGD and fish diversity, we conducted a survey at the coastal island scale using the environmental DNA (eDNA) method. Our findings indicate that fish species richness and functional richness peak at stations with high SGD. Environmental variables, such as salinity, dissolved inorganic nitrogen (DIN) concentration, and SGD, significantly influence fish diversity. Carnivore fish richness was negatively correlated with salinity, while planktivore fish richness was positively correlated. Additionally, SGD and DIN concentrations were found to be crucial in shaping omnivorous and pelagic communities, respectively. This study highlights the role of SGD in enhancing nutrient conditions favorable for diverse fish communities and demonstrates the effectiveness of eDNA metabarcoding for rapid marine biodiversity assessment. These findings provide valuable insights for coastal ecosystem monitoring and management.

DOI： 10.3390/biology13080609

The Evolution and Characterization of the RNA Interference Pathways in Lophotrochozoa 査読

Alessandro Formaggioni, Gianmarco Cavalli, Mayuko Hamada, Tatsuya Sakamoto, Federico Plazzi, Marco Passamonti

Genome Biology and Evolution 16 ( 5 ) 2024年5月

掲載種別：研究論文（学術雑誌）出版者・発行元：Oxford University Press (OUP)

Abstract

In animals, three main RNA interference mechanisms have been described so far, which respectively maturate three types of small noncoding RNAs (sncRNAs): miRNAs, piRNAs, and endo-siRNAs. The diversification of these mechanisms is deeply linked with the evolution of the Argonaute gene superfamily since each type of sncRNA is typically loaded by a specific Argonaute homolog. Moreover, other protein families play pivotal roles in the maturation of sncRNAs, like the DICER ribonuclease family, whose DICER1 and DICER2 paralogs maturate respectively miRNAs and endo-siRNAs. Within Metazoa, the distribution of these families has been only studied in major groups, and there are very few data for clades like Lophotrochozoa. Thus, we here inferred the evolutionary history of the animal Argonaute and DICER families including 43 lophotrochozoan species. Phylogenetic analyses along with newly sequenced sncRNA libraries suggested that in all Trochozoa, the proteins related to the endo-siRNA pathway have been lost, a part of them in some phyla (i.e. Nemertea, Bryozoa, Entoprocta), while all of them in all the others. On the contrary, early diverging phyla, Platyhelminthes and Syndermata, showed a complete endo-siRNA pathway. On the other hand, miRNAs were revealed the most conserved and ubiquitous mechanism of the metazoan RNA interference machinery, confirming their pivotal role in animal cell regulation.

DOI： 10.1093/gbe/evae098

その他リンク： https://academic.oup.com/gbe/article-pdf/16/5/evae098/58028616/evae098.pdf

Evaluation of the Effects of Environmental Factors on Seasonal Variations in Fish Diversity on a Coastal Island in Western Japan 査読

Nguyen Hong Nhat, Mitsuyo Saito, Mayuko Hamada, Shin-ichi Onodera

Environments 11 ( 3 ) 60 - 60 2024年3月

掲載種別：研究論文（学術雑誌）出版者・発行元：MDPI AG

Coastal habitats are crucial for supporting ecological processes and serve as vital ecosystems for diverse fish species, providing essential functions such as feeding, nursery provision, and reproductive habitats. Fish communities are ecologically important components of coastal ecosystems and are affected by multiple environmental factors. Despite their importance, determining the effects of environmental factors on seasonal variations in fish species diversity and community dynamics remains a challenge. The advent of environmental DNA (eDNA) technology, an environmentally conscious approach, has resulted in considerable advancements in recent years and has been progressively adopted for marine fish population monitoring. Here, we used environmental DNA metabarcoding to study seasonal variations in fish community structure on a coastal island, and we assessed the effects of environmental factors in structuring these communities. Our findings revealed a rich diversity of 72 fish species across 40 families and 23 orders in the seawater surrounding an island of the Seto Inland Sea (SIS), Western Japan. Notably, the composition of fish communities varied significantly between seasons, with seawater temperature, salinity, and dissolved inorganic phosphorus (DIP) concentration identified as important factors correlated with fish communities’ structures. In conclusion, our study provides useful information of fish diversity, and we suggest that eDNA is a valuable technique for monitoring fish diversity in coastal areas. These findings are crucial for ecological studies and the environmental monitoring of oceanic coastal environments.

DOI： 10.3390/environments11030060

Structure of putative epidermal sensory receptors in an acoel flatworm, Praesagittifera naikaiensis 査読

Tosuke Sakagami, Kaho Watanabe, Mayuko Hamada, Tatsuya Sakamoto, Toshimitsu Hatabu, Motonori Ando

Cell and Tissue Research 395 ( 3 ) 299 - 311 2024年2月

掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

Acoel flatworms possess epidermal sensory-receptor cells on their body surfaces and exhibit behavioral repertoires such as geotaxis and phototaxis. Acoel epidermal sensory receptors should be mechanical and/or chemical receptors; however, the mechanisms of their sensory reception have not been elucidated. We examined the three-dimensional relationship between epidermal sensory receptors and their innervation in an acoel flatworm, Praesagittifera naikaiensis. The distribution of the sensory receptors was different between the ventral and dorsal sides of worms. The nervous system was mainly composed of a peripheral nerve net, an anterior brain, and three pairs of longitudinal nerve cords. The nerve net was located closer to the body surface than the brain and the nerve cords. The sensory receptors have neural connections with the nerve net in the entire body of worms. We identified five homologs of polycystic kidney disease (PKD): PKD1-1, PKD1-2, PKD1-3, PKD1-4, and, PKD2, from the P. naikaiensis genome. All of these PKD genes were implied to be expressed in the epidermal sensory receptors of P. naikaiensis. PKD1-1 and PKD2 were dispersed across the entire body of worms. PKD1-2, PKD1-3, and PKD1-4 were expressed in the anterior region of worms. PKD1-4 was also expressed around the mouth opening. Our results indicated that P. naikaiensis possessed several types of epidermal sensory receptors to convert various environmental stimuli into electrical signals via the PKD channels and transmit the signals to afferent nerve and/or effector cells.

DOI： 10.1007/s00441-024-03865-y

その他リンク： https://link.springer.com/article/10.1007/s00441-024-03865-y/fulltext.html

Model systems for discovering evolutionary singularity of bilaterian physiological regulation: lessons from studies on simple/primitive flatworms 査読

Shunsuke Mori, Aoshi Kobayashi, Hirotaka Sakamoto, Mayuko Hamada, Tatsuya Sakamoto, Ryo Nakamura

Biophysics and Physicobiology 2024年

Fbxl4 Regulates the Photic Entrainment of Circadian Locomotor Rhythms in the Cricket Gryllus bimaculatus 査読

Kazuki Takeuchi, Mirai Matsuka, Tsugumichi Shinohara, Mayuko Hamada, Yasuaki Tomiyama, Kenji Tomioka

Zoological Science 40 ( 1 ) 2023年1月

Quantitative PCR method to detect an extremely endangered bitterling fish (Rhodeus atremius suigensis) using environmental DNA 査読

Kanoko Otsuki, Mayuko Hamada, Noriyuki Koizumi, Tatsuya Sakamoto, Kazuyoshi Nakata

Landscape and Ecological Engineering 2022年11月

De novo transcriptome analysis of the centrohelid Raphidocystis contractilis to identify genes involved in microtubule-based motility. 査読国際誌

Risa Ikeda, Tosuke Sakagami, Mayuko Hamada, Tatsuya Sakamoto, Toshimitsu Hatabu, Noboru Saito, Motonori Ando

The Journal of eukaryotic microbiology 70 ( 2 ) e12955 2022年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

The centrohelid heliozoan Raphidocystis contractilis has many radiating axopodia, each containing axopodial microtubules. The axopodia show rapid contraction at nearly a video rate (30 frames per second) in response to mechanical stimuli. The axopodial contraction is accompanied by cytoskeletal microtubule depolymerization, but the molecular mechanism of this phenomenon has not been elucidated. In this study, we performed de novo transcriptome sequencing of R. contractilis to identify genes involved in microtubule dynamics such as the rapid axopodial contraction. The transcriptome sequencing generated 7.15-Gbp clean reads in total, which were assembled as 31,771 unigenes. Using the obtained gene sets, we identified several microtubule-severing proteins which might be involved in the rapid axopodial contraction, and kinesin-like genes that occur gene duplication. On the other hand, some genes for microtubule motor proteins involved in the formation and motility of flagella were not found in R. contractilis, suggesting that the gene repertoire of R. contractilis reflected the morphological features of non-flagellated protists. Our transcriptome analysis provides basic information for the analysis of the molecular mechanism underlying microtubule dynamics in R. contractilis.

DOI： 10.1111/jeu.12955

緑藻はどのようにヒドラと共生してきたか

御代川涼, 小早川義尚, 濱田麻友子, 楠見淳子

植物科学最前線 13 13 - 30 2022年5月

d-Serine controls epidermal vesicle release via NMDA receptor, allowing tissue migration during the metamorphosis of the chordate Ciona. 査読国際誌

Gabriel Krasovec, Akiko Hozumi, Tomoyuki Yoshida, Takayuki Obita, Mayuko Hamada, Akira Shiraishi, Honoo Satake, Takeo Horie, Hisashi Mori, Yasunori Sasakura

Science advances 8 ( 10 ) eabn3264 2022年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

d-Serine, a free amino acid synthesized by serine racemase, is a coagonist of N-methyl-d-aspartate-type glutamate receptor (NMDAR). d-Serine in the mammalian central nervous system modulates glutamatergic transmission. Functions of d-serine in mammalian peripheral tissues such as skin have also been described. However, d-serine's functions in nonmammals are unclear. Here, we characterized d-serine-dependent vesicle release from the epidermis during metamorphosis of the tunicate Ciona. d-Serine leads to the formation of a pocket that facilitates the arrival of migrating tissue during tail regression. NMDAR is the receptor of d-serine in the formation of the epidermal pocket. The epidermal pocket is formed by the release of epidermal vesicles' content mediated by d-serine/NMDAR. This mechanism is similar to observations of keratinocyte vesicle exocytosis in mammalian skin. Our findings provide a better understanding of the maintenance of epidermal homeostasis in animals and contribute to further evolutionary perspectives of d-amino acid function among metazoans.

DOI： 10.1126/sciadv.abn3264

Vasopressin-oxytocin–type signaling is ancient and has a conserved water homeostasis role in euryhaline marine planarians 査読

Aoshi Kobayashi, Mayuko Hamada, Masa-aki Yoshida, Yasuhisa Kobayashi, Naoaki Tsutsui, Toshio Sekiguchi, Yuta Matsukawa, Sho Maejima, Joseph J. Gingell, Shoko Sekiguchi, Ayumu Hamamoto, Debbie L. Hay, John F. Morris, Tatsuya Sakamoto, Hirotaka Sakamoto

Science Advances 8 ( 9 ) 2022年3月

掲載種別：研究論文（学術雑誌）出版者・発行元：American Association for the Advancement of Science (AAAS)

Vasopressin/oxytocin (VP/OT)–related peptides are essential for mammalian antidiuresis, sociosexual behavior, and reproduction. However, the evolutionary origin of this peptide system is still uncertain. Here, we identify orthologous genes to those for VP/OT in Platyhelminthes, intertidal planarians that have a simple bilaterian body structure but lack a coelom and body-fluid circulatory system. We report a comprehensive characterization of the neuropeptide derived from this VP/OT-type gene, identifying its functional receptor, and name it the “platytocin” system. Our experiments with these euryhaline planarians, living where environmental salinities fluctuate due to evaporation and rainfall, suggest that platytocin functions as an “antidiuretic hormone” and also organizes diverse actions including reproduction and chemosensory-associated behavior. We propose that bilaterians acquired physiological adaptations to amphibious lives by such regulation of the body fluids. This neuropeptide-secreting system clearly became indispensable for life even without the development of a vascular circulatory system or relevant synapses.

DOI： 10.1126/sciadv.abk0331

Observing Phylum-Level Metazoan Diversity by Environmental DNA Analysis at the Ushimado Area in the Seto Inland Sea 査読

Takeshi Kawashima, Masa-aki Yoshida, Hideyuki Miyazawa, Hiroaki Nakano, Natumi Nakano, Tatsuya Sakamoto, Mayuko Hamada

Zoological Science 39 ( 1 ) 157 - 165 2022年1月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Zoological Society of Japan

The dynamics of microscopic marine plankton in coastal areas is a fundamental theme in marine biodiversity research, but studies have been limited because the only available methodology was collection of plankton using plankton-nets and microscopic observation. In recent years, environmental DNA (eDNA) analysis has exhibited potential for conducting comprehensive surveys of marine plankton diversity in water at fixed points and depths in the ocean. However, few studies have examined how eDNA analysis reflects the actual distribution and dynamics of organisms in the field, and further investigation is needed to determine whether it can detect distinct differences in plankton density in the field. To address this, we analyzed eDNA in seawater samples collected at 1 km intervals at three depths over a linear distance of approximately 3.0 km in the Seto Inland Sea. The survey area included a location with a high density of Acoela (Praesagittifera naikaiensis). However, the eDNA signal for this was little to none, and its presence would not have been noticed if we did not have this information beforehand. Meanwhile, eDNA analysis enabled us to confirm the presence of a species of Placozoa that was previously undiscovered in the area. In summary, our results suggest that the number of sequence reads generated from eDNA samples in our project was not sufficient to predict the density of a particular species. However, eDNA can be useful for detecting organisms that have been overlooked using other methods.

DOI： 10.2108/zs210073

The gastrin-releasing peptide/bombesin system revisited by a reverse-evolutionary study considering Xenopus 査読国際誌

Asuka Hirooka, Mayuko Hamada, Daiki Fujiyama, Keiko Takanami, Yasuhisa Kobayashi, Takumi Oti, Yukitoshi Katayama, Tatsuya Sakamoto, Hirotaka Sakamoto

Scientific Reports 11 ( 1 ) 13315 - 13315 2021年6月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

<title>Abstract</title>Bombesin is a putative antibacterial peptide isolated from the skin of the frog, <italic>Bombina bombina</italic>. Two related (bombesin-like) peptides, gastrin-releasing peptide (GRP) and neuromedin B (NMB) have been found in mammals. The history of GRP/bombesin discovery has caused little attention to be paid to the evolutionary relationship of GRP/bombesin and their receptors in vertebrates. We have classified the peptides and their receptors from the phylogenetic viewpoint using a newly established genetic database and bioinformatics. Here we show, by using a clawed frog (<italic>Xenopus tropicalis</italic>), that GRP is not a mammalian counterpart of bombesin and also that, whereas the GRP system is widely conserved among vertebrates, the NMB/bombesin system has diversified in certain lineages, in particular in frog species. To understand the derivation of GRP system in the ancestor of mammals, we have focused on the GRP system in <italic>Xenopus</italic>. Gene expression analyses combined with immunohistochemistry and Western blotting experiments demonstrated that GRP peptides and their receptors are distributed in the brain and stomach of <italic>Xenopus</italic>. We conclude that GRP peptides and their receptors have evolved from ancestral (GRP-like peptide) homologues to play multiple roles in both the gut and the brain as one of the <italic>‘gut-brain peptide’</italic> systems.

DOI： 10.1038/s41598-021-92528-x

その他リンク： http://www.nature.com/articles/s41598-021-92528-x

A Reference Genome from the Symbiotic Hydrozoan, Hydra viridissima 査読

Mayuko Hamada, Noriyuki Satoh, Konstantin Khalturin

G3; Genes|Genomes|Genetics 10 ( 11 ) 3883 - 3895 2020年11月

担当区分：筆頭著者,　責任著者掲載種別：研究論文（学術雑誌）出版者・発行元：Oxford University Press (OUP)

Various <italic>Hydra</italic> species have been employed as model organisms since the 18^th century. Introduction of transgenic and knock-down technologies made them ideal experimental systems for studying cellular and molecular mechanisms involved in regeneration, body-axis formation, senescence, symbiosis, and holobiosis. In order to provide an important reference for genetic studies, the <italic>Hydra magnipapillata</italic> genome (species name has been changed to <italic>H. vulgaris</italic>) was sequenced a decade ago (Chapman <italic>et al.</italic>, 2010) and the updated genome assembly, Hydra 2.0, was made available by the National Human Genome Research Institute in 2017. While <italic>H. vulgaris</italic> belongs to the non-symbiotic brown hydra lineage, the green hydra, <italic>Hydra viridissima</italic>, harbors algal symbionts and belongs to an early diverging clade that separated from the common ancestor of brown and green hydra lineages at least 100 million years ago (Schwentner and Bosch 2015; Khalturin <italic>et al.</italic>, 2019). While interspecific interactions between <italic>H. viridissima</italic> and endosymbiotic unicellular green algae of the genus <italic>Chlorella</italic> have been a subject of interest for decades, genomic information about green hydras was nonexistent. Here we report a draft 280-Mbp genome assembly for <italic>Hydra viridissima</italic> strain A99, with a scaffold N50 of 1.1 Mbp. The <italic>H. viridissima</italic> genome contains an estimated 21,476 protein-coding genes. Comparative analysis of Pfam domains and orthologous proteins highlights characteristic features of <italic>H. viridissima</italic>, such as diversification of innate immunity genes that are important for host-symbiont interactions. Thus, the <italic>H. viridissima</italic> assembly provides an important hydrozoan genome reference that will facilitate symbiosis research and better comparisons of metazoan genome architectures.

DOI： 10.1534/g3.120.401411

GABA-Induced GnRH Release Triggers Chordate Metamorphosis 査読国際誌

Akiko Hozumi, Shohei Matsunobu, Kaoru Mita, Nicholas Treen, Takaho Sugihara, Takeo Horie, Tetsushi Sakuma, Takashi Yamamoto, Akira Shiraishi, Mayuko Hamada, Noriyuki Satoh, Keisuke Sakurai, Honoo Satake, Yasunori Sasakura

Current Biology 30 ( 8 ) 1555 - 1561.e4 2020年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Elsevier BV

Metamorphosis, a widespread life history strategy in metazoans, allows dispersal and use of different ecological niches through a dramatic body change from a larval stage [1, 2]. Despite its conservation and importance, the molecular mechanisms underlying its initiation and progression have been characterized in only a few animal models. In this study, through pharmacological and gene functional analyses, we identified neurotransmitters responsible for metamorphosis of the ascidian Ciona. Ciona metamorphosis converts swimming tadpole larvae into vase-like, sessile adults. Here, we show that the neurotransmitter GABA is a key regulator of metamorphosis. We found that gonadotropin-releasing hormone (GnRH) is a downstream neuropeptide of GABA. Although GABA is generally thought of as an inhibitory neurotransmitter, we found that it positively regulates secretion of GnRH through the metabotropic GABA receptor during Ciona metamorphosis. GnRH is necessary for reproductive maturation in vertebrates, and GABA is an important excitatory regulator of GnRH in the hypothalamus during puberty [3, 4]. Our findings reveal another role of the GABA-GnRH axis in the regulation of post-embryonic development in chordates.

DOI： 10.1016/j.cub.2020.02.003

A Nearly Complete Genome of Ciona intestinalis Type A (C. robusta) Reveals the Contribution of Inversion to Chromosomal Evolution in the Genus Ciona. 査読国際誌

Yutaka Satou, Ryohei Nakamura, Deli Yu, Reiko Yoshida, Mayuko Hamada, Manabu Fujie, Kanako Hisata, Hiroyuki Takeda, Noriyuki Satoh

Genome biology and evolution 11 ( 11 ) 3144 - 3157 2019年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

Since its initial publication in 2002, the genome of Ciona intestinalis type A (Ciona robusta), the first genome sequence of an invertebrate chordate, has provided a valuable resource for a wide range of biological studies, including developmental biology, evolutionary biology, and neuroscience. The genome assembly was updated in 2008, and it included 68% of the sequence information in 14 pairs of chromosomes. However, a more contiguous genome is required for analyses of higher order genomic structure and of chromosomal evolution. Here, we provide a new genome assembly for an inbred line of this animal, constructed with short and long sequencing reads and Hi-C data. In this latest assembly, over 95% of the 123 Mb of sequence data was included in the chromosomes. Short sequencing reads predicted a genome size of 114-120 Mb; therefore, it is likely that the current assembly contains almost the entire genome, although this estimate of genome size was smaller than previous estimates. Remapping of the Hi-C data onto the new assembly revealed a large inversion in the genome of the inbred line. Moreover, a comparison of this genome assembly with that of Ciona savignyi, a different species in the same genus, revealed many chromosomal inversions between these two Ciona species, suggesting that such inversions have occurred frequently and have contributed to chromosomal evolution of Ciona species. Thus, the present assembly greatly improves an essential resource for genome-wide studies of ascidians.

DOI： 10.1093/gbe/evz228

Medusozoan genomes inform the evolution of the jellyfish body plan. 査読国際誌

Konstantin Khalturin, Chuya Shinzato, Maria Khalturina, Mayuko Hamada, Manabu Fujie, Ryo Koyanagi, Miyuki Kanda, Hiroki Goto, Friederike Anton-Erxleben, Masaya Toyokawa, Sho Toshino, Noriyuki Satoh

Nature ecology & evolution 3 ( 5 ) 811 - 822 2019年5月

記述言語：英語掲載種別：研究論文（学術雑誌）

Cnidarians are astonishingly diverse in body form and lifestyle, including the presence of a jellyfish stage in medusozoans and its absence in anthozoans. Here, we sequence the genomes of Aurelia aurita (a scyphozoan) and Morbakka virulenta (a cubozoan) to understand the molecular mechanisms responsible for the origin of the jellyfish body plan. We show that the magnitude of genetic differences between the two jellyfish types is equivalent, on average, to the level of genetic differences between humans and sea urchins in the bilaterian lineage. About one-third of Aurelia genes with jellyfish-specific expression have no matches in the genomes of the coral and sea anemone, indicating that the polyp-to-jellyfish transition requires a combination of conserved and novel, medusozoa-specific genes. While no genomic region is specifically associated with the ability to produce a jellyfish stage, the arrangement of genes involved in the development of a nematocyte-a phylum-specific cell type-is highly structured and conserved in cnidarian genomes; thus, it represents a phylotypic gene cluster.

DOI： 10.1038/s41559-019-0853-y

Metabolic co-dependence drives the evolutionarily ancient Hydra-Chlorella symbiosis. 査読国際誌

Mayuko Hamada, Katja Schröder, Jay Bathia, Ulrich Kürn, Sebastian Fraune, Mariia Khalturina, Konstantin Khalturin, Chuya Shinzato, Nori Satoh, Thomas Cg Bosch

eLife 7 2018年5月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Many multicellular organisms rely on symbiotic associations for support of metabolic activity, protection, or energy. Understanding the mechanisms involved in controlling such interactions remains a major challenge. In an unbiased approach we identified key players that control the symbiosis between Hydra viridissima and its photosynthetic symbiont Chlorella sp. A99. We discovered significant up-regulation of Hydra genes encoding a phosphate transporter and glutamine synthetase suggesting regulated nutrition supply between host and symbionts. Interestingly, supplementing the medium with glutamine temporarily supports in vitro growth of the otherwise obligate symbiotic Chlorella, indicating loss of autonomy and dependence on the host. Genome sequencing of Chlorella sp. A99 revealed a large number of amino acid transporters and a degenerated nitrate assimilation pathway, presumably as consequence of the adaptation to the host environment. Our observations portray ancient symbiotic interactions as a codependent partnership in which exchange of nutrients appears to be the primary driving force.

DOI： 10.7554/eLife.35122

Evolution of the chordate regeneration blastema: Differential gene expression and conserved role of notch signaling during siphon regeneration in the ascidian Ciona 査読

Mayuko Hamada, Spela Goricki, Mardi S. Byerly, Noriyuki Satoh, William R. Jeffery

DEVELOPMENTAL BIOLOGY 405 ( 2 ) 304 - 315 2015年9月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACADEMIC PRESS INC ELSEVIER SCIENCE

The regeneration of the oral siphon (OS) and other distal structures in the ascidian Ciona intestinalis occurs by epimorphosis involving the formation of a blastema of proliferating cells. Despite the long-standing use of Ciona as a model in molecular developmental biology, regeneration in this system has not been previously explored by molecular analysis. Here we have employed microarray analysis and quantitative real time RT-PCR to identify genes with differential expression profiles during OS regeneration. The majority of differentially expressed genes were downregulated during OS regeneration, suggesting roles in normal growth and homeostasis. However, a subset of differentially expressed genes was upregulated in the regenerating OS, suggesting functional roles during regeneration. Among the upregulated genes were key members of the Notch signaling pathway, including those encoding the delta and jagged ligands, two fringe modulators, and to a lesser extent the notch receptor. In situ hybridization showed a complementary pattern of delta1 and notch gene expression in the blastema of the regenerating OS. Chemical inhibition of the Notch signaling pathway reduced the levels of cell proliferation in the branchial sac, a stem cell niche that contributes progenitor cells to the regenerating OS, and in the OS regeneration blastema, where siphon muscle fibers eventually re-differentiate. Chemical inhibition also prevented the replacement of oral siphon pigment organs, sensory receptors rimming the entrance of the OS, and siphon muscle fibers, but had no effects on the formation of the wound epidermis. Since Notch signaling is involved in the maintenance of proliferative activity in both the Ciona and vertebrate regeneration blastema, the results suggest a conserved evolutionary role of this signaling pathway in chordate regeneration. The genes identified in this investigation provide the foundation for future molecular analysis of OS regeneration. (C) 2015 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.ydbio.2015.07.017

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