慶應義塾研究者情報データベース

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• 2012年04月

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  2015年03月

  東京大学, 大学院理学系研究科, 生物科学専攻

  大学院, 卒業, 博士

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• 理学, 東京大学

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• Search for putative gene regulatory motifs in CAHS3, linked to anhydrobiosis in a tardigrade Ramazzottius varieornatus, in vivo and in silico

  Ishikawa S., Tanaka S., Arakawa K.

  Genes to Cells 29 （ 12 ） 1144 - 1153 2024年12月

  ISSN  13569597

  　概要を見る

  Tardigrades possess the ability to enter an almost completely dehydrated state, anhydrobiosis. The CAHS (cytosolic abundant heat-soluble) protein family has been identified as one of the anhydrobiosis-related proteins. In particular, CAHS3 protein from an anhydrobiotic tardigrade, Ramazzottius varieornatus, shows heat-solubility and reversible condensation and is one of the most highly expressed among the CAHS paralogs. A recently developed tardigrade-specific vector showed tissue-specific expression of RvCAHS3 most pronounced in the epidermis in vivo, contrary to the idea that anhydrobiotic genes are uniformly expressed in all tardigrade cells. In this study, we investigated the regulation of RvCAHS3 gene expression through in vivo expression experiments using tardigrade vectors with a series of truncated upstream regions coupled with in silico analysis to identify the anhydrobiosis-related genes that are expressed under the same regulatory system as RvCAHS3. As a result, the 300–350 bp region upstream of RvCAHS3 is critical for regulating gene expression in tardigrade vector experiments, and three motifs conserved between two species of anhydrobiotic tardigrades were identified within a 500 bp region directly upstream of RvCAHS3 start codon. These motifs, which have also been identified upstream of other CAHS genes, could be associated with the regulatory system of anhydrobiosis-related genes in tardigrades.

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• In vivo expression vector derived from anhydrobiotic tardigrade genome enables live imaging in Eutardigrada

  Tanaka S., Aoki K., Arakawa K.

  Proceedings of the National Academy of Sciences of the United States of America 120 （ 5 ）  2023年01月

  ISSN  00278424

  　概要を見る

  Water is essential for life, but anhydrobiotic tardigrades can survive almost complete dehydration. Anhydrobiosis has been a biological enigma for more than a century with respect to how organisms sustain life without water, but the few choices of genetic toolkits available in tardigrade research have been a challenging circumstance. Here, we report the development of an in vivo expression system for tardigrades. This transient transgenic technique is based on a plasmid vector (TardiVec) with promoters that originated from an anhydrobiotic tardigrade Ramazzottius varieornatus. It enables the introduction of GFP-fused proteins and genetically encoded indicators such as the Ca2+ indicator GCaMP into tardigrade cells; consequently, the dynamics of proteins and cells in tardigrades may be observed by fluorescence live imaging. This system is applicable for several tardigrades in the class Eutardigrada: the promoters of anhydrobiosis-related genes showed tissue-specific expression in this work. Surprisingly, promoters functioned similarly between multiple species, even for species with different modes of expression of anhydrobiosis-related genes, such as Hypsibius exemplaris, in which these genes are highly induced upon facing desiccation, and Thulinius ruffoi, which lacks anhydrobiotic capability. These results suggest that the highly dynamic expression changes in desiccation-induced species are regulated in trans. Tissue-specific expression of tardigrade-unique unstructured proteins also suggests differing anhydrobiosis machinery depending on the cell types. We believe that tardigrade transgenic technology opens up various experimental possibilities in tardigrade research, especially to explore anhydrobiosis mechanisms.

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• Time-series transcriptomic screening of factors contributing to the cross-tolerance to UV radiation and anhydrobiosis in tardigrades

  Yoshida Y., Satoh T., Ota C., Tanaka S., Horikawa D.D., Tomita M., Kato K., Arakawa K.

  BMC Genomics 23 （ 1 ）  2022年12月

  　概要を見る

  Background: Tardigrades are microscopic animals that are capable of tolerating extreme environments by entering a desiccated state of suspended animation known as anhydrobiosis. While antioxidative stress proteins, antiapoptotic pathways and tardigrade-specific intrinsically disordered proteins have been implicated in the anhydrobiotic machinery, conservation of these mechanisms is not universal within the phylum Tardigrada, suggesting the existence of overlooked components. Results: Here, we show that a novel Mn-dependent peroxidase is an important factor in tardigrade anhydrobiosis. Through time-series transcriptome analysis of Ramazzottius varieornatus specimens exposed to ultraviolet light and comparison with anhydrobiosis entry, we first identified several novel gene families without similarity to existing sequences that are induced rapidly after stress exposure. Among these, a single gene family with multiple orthologs that is highly conserved within the phylum Tardigrada and enhances oxidative stress tolerance when expressed in human cells was identified. Crystallographic study of this protein suggested Zn or Mn binding at the active site, and we further confirmed that this protein has Mn-dependent peroxidase activity in vitro. Conclusions: Our results demonstrated novel mechanisms for coping with oxidative stress that may be a fundamental mechanism of anhydrobiosis in tardigrades. Furthermore, localization of these sets of proteins mainly in the Golgi apparatus suggests an indispensable role of the Golgi stress response in desiccation tolerance.

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• Deciphering the Biological Enigma—Genomic Evolution Underlying Anhydrobiosis in the Phylum Tardigrada and the Chironomid Polypedilum vanderplanki

  Yoshida Y., Tanaka S.

  Insects 13 （ 6 ）  2022年06月

  　概要を見る

  Anhydrobiosis, an ametabolic dehydrated state triggered by water loss, is observed in several invertebrate lineages. Anhydrobiotes revive when rehydrated, and seem not to suffer the ultimately lethal cell damage that results from severe loss of water in other organisms. Here, we review the biochemical and genomic evidence that has revealed the protectant molecules, repair systems, and maintenance pathways associated with anhydrobiosis. We then introduce two lineages in which anhydrobiosis has evolved independently: Tardigrada, where anhydrobiosis characterizes many species within the phylum, and the genus Polypedilum, where anhydrobiosis occurs in only two species. Finally, we discuss the complexity of the evolution of anhydrobiosis within invertebrates based on current knowledge, and propose perspectives to enhance the understanding of anhydrobiosis.

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• Multiomics study of a heterotardigrade, Echinisicus testudo, suggests the possibility of convergent evolution of abundant heat-soluble proteins in Tardigrada

  Murai Y., Yagi-Utsumi M., Fujiwara M., Tanaka S., Tomita M., Kato K., Arakawa K.

  BMC Genomics 22 （ 1 ）  2021年12月

  　概要を見る

  Background: Many limno-terrestrial tardigrades can enter an ametabolic state, known as anhydrobiosis, upon desiccation, in which the animals can withstand extreme environments. Through genomics studies, molecular components of anhydrobiosis are beginning to be elucidated, such as the expansion of oxidative stress response genes, loss of stress signaling pathways, and gain of tardigrade-specific heat-soluble protein families designated CAHS and SAHS. However, to date, studies have predominantly investigated the class Eutardigrada, and molecular mechanisms in the remaining class, Heterotardigrada, still remains elusive. To address this gap in the research, we report a multiomics study of the heterotardigrade Echiniscus testudo, one of the most desiccation-tolerant species which is not yet culturable in laboratory conditions. Results: In order to elucidate the molecular basis of anhydrobiosis in E. testudo, we employed a multi-omics strategy encompassing genome sequencing, differential transcriptomics, and proteomics. Using ultra-low input library sequencing protocol from a single specimen, we sequenced and assembled the 153.7 Mbp genome annotated using RNA-Seq data. None of the previously identified tardigrade-specific abundant heat-soluble genes was conserved, while the loss and expansion of existing pathways were partly shared. Furthermore, we identified two families novel abundant heat-soluble proteins, which we named E. testudo Abundant Heat Soluble (EtAHS), that are predicted to contain large stretches of disordered regions. Likewise the AHS families in eutardigrada, EtAHS shows structural changes from random coil to alphahelix as the water content was decreased in vitro. These characteristics of EtAHS proteins are analogous to those of CAHS in eutardigrades, while there is no conservation at the sequence level. Conclusions: Our results suggest that Heterotardigrada have partly shared but distinct anhydrobiosis machinery compared with Eutardigrada, possibly due to convergent evolution within Tardigrada. (276/350).

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• 最強生物クマムシの乾眠メカニズムの解析

  田中, 冴

  Keio SFC journal （慶應SFC学会）  22 （ 2 ） 178 - 190 2022年

  ISSN  13472828

• 近赤外光を用いた、糖異性体のin vivo測定法の確立

  田中, 冴

  科学研究費補助金研究成果報告書 2018年

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• Reply to Tanaka and Kunieda: Control protein GFP also shows a mesh-like structure in desiccating tardigrade cells

  Tanaka S., Arakawa K.

  Proceedings of the National Academy of Sciences of the United States of America 120 （ 48 ）  2023年

  ISSN  00278424

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• 近赤外光を用いた、糖異性体のin vivo測定法の確立

  2017年04月

  -

  2019年03月

  文部科学省・日本学術振興会, 科学研究費助成事業, 田中　冴, 若手研究(B), 補助金,  研究代表者

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• ゲノム分子生物学１

  2026年度

• ゲノム分子生物学２

  2026年度