論文 - 福永　津嵩

Lncrrisearch: A web server for lncRNA-RNA interaction prediction integrated with tissue-specific expression and subcellular localization data

Tsukasa Fukunaga, Junichi Iwakiri, Yukiteru Ono, Michiaki Hamada

Frontiers in Genetics 10 （ MAY ） 462 - 462 2019年

筆頭著者, 査読有り

　概要を見る

Long non-coding RNAs (lncRNAs) play critical roles in various biological processes, but the function of the majority of lncRNAs is still unclear. One approach for estimating a function of a lncRNA is the identification of its interaction target because functions of lncRNAs are expressed through interaction with other biomolecules in quite a few cases. In this paper, we developed “LncRRIsearch,” which is a web server for comprehensive prediction of human and mouse lncRNA-lncRNA and lncRNA-mRNA interaction. The prediction was conducted using RIblast, which is a fast and accurate RNA-RNA interaction prediction tool. Users can investigate interaction target RNAs of a particular lncRNA through a web interface. In addition, we integrated tissue-specific expression and subcellular localization data for the lncRNAs with the web server. These data enable users to examine tissue-specific or subcellular localized lncRNA interactions. LncRRIsearch is publicly accessible at http://rtools.cbrc.jp/LncRRIsearch/.

• Access to Document (DOI)

A Novel Method for Assessing the Statistical Significance of RNA-RNA Interactions Between Two Long RNAs

Tsukasa Fukunaga, Michiaki Hamada

Journal of Computational Biology 25 （ 9 ） 976 - 986 2018年09月

筆頭著者, 責任著者, 査読有り,  ISSN  1066-5277

　概要を見る

RNA-RNA interactions are key mechanisms through which noncoding RNA (ncRNA) regions exert biological functions. Computational prediction of RNA-RNA interactions is an essential method for detecting novel RNA-RNA interactions because their comprehensive detection by biological experimentation is still quite difficult. Many RNA-RNA interaction prediction tools have been developed, but they tend to produce many false positives. Accordingly, assessment of the statistical significance of computationally predicted interactions is an important task. However, there is no method to evaluate the statistical significance of RNA-RNA interactions that is applicable to interactions between two long RNA sequences. We developed a method to calculate the p-value for the minimal interaction energy between two long RNA sequences. The developed method depends on the fact that minimum interaction energies of RNA-RNA interactions between long RNAs follow a Gumbel distribution when repeat sequences in RNAs are masked. To show the usefulness of the developed method, we applied it to whole human 5′-untranslated region (UTR) and 3′-UTR sequences to detect novel 5′-UTR-3′-UTR interactions. We thus identified two significant 5′-UTR-3′-UTR interactions. Specifically, the human small proline-rich repeat protein 3 shows conserved 5′-UTR-3′-UTR interactions with some nucleotide variations preserving base pairings among primates. Our developed method enables us to detect statistically significant RNA-RNA interactions between long RNAs such as long ncRNAs. Statistical significance estimates help in identification of interactions for experimental validation and provide novel insights into the function of ncRNA regions.

• Access to Document (DOI)

Computational approaches for alternative and transient secondary structures of ribonucleic acids

Tsukasa Fukunaga, Michiaki Hamada

Briefings in Functional Genomics 18 （ 3 ） 182 - 191 2018年06月

筆頭著者, 査読有り,  ISSN  2041-2649

　概要を見る

Transient and alternative structures of ribonucleic acids (RNAs) play essential roles in various regulatory processes, such as translation regulation in living cells. Because experimental analyses for RNA structures are difficult and time-consuming, computational approaches based on RNA secondary structures are promising. In this article, we review computational methods for detecting and analyzing transient/alternative secondary structures of RNAs, including static approaches based on probabilistic distributions of RNA secondary structures and dynamic approaches such as kinetic folding and folding pathway predictions.

• Access to Document (DOI)

MitoFish and mifish pipeline: A mitochondrial genome database of fish with an analysis pipeline for environmental DNA metabarcoding

Yukuto Sato, Masaki Miya, Tsukasa Fukunaga, Tetsuya Sado, Wataru Iwasaki

Molecular Biology and Evolution 35 （ 6 ） 1553 - 1555 2018年06月

査読有り,  ISSN  0737-4038

　概要を見る

Fish mitochondrial genome (mitogenome) data form a fundamental basis for revealing vertebrate evolution and hydrosphere ecology. Here, we report recent functional updates of MitoFish, which is a database of fish mitogenomes with a precise annotation pipeline MitoAnnotator. Most importantly, we describe implementation of MiFish pipeline for metabarcoding analysis of fish mitochondrial environmental DNA, which is a fast-emerging and powerful technology in fish studies. MitoFish, MitoAnnotator, and MiFish pipeline constitute a key platform for studies of fish evolution, ecology, and conservation, and are freely available at http://mitofish.aori.u-Tokyo.ac.jp/ (last accessed April 7th, 2018).

• Access to Document (DOI)

Identification and analysis of ribosome-associated lncRNAs using ribosome profiling data

Chao Zeng, Tsukasa Fukunaga, Michiaki Hamada

BMC Genomics 19 （ 1 ） 414 - 414 2018年05月

査読有り

　概要を見る

Background: Although the number of discovered long non-coding RNAs (lncRNAs) has increased dramatically, their biological roles have not been established. Many recent studies have used ribosome profiling data to assess the protein-coding capacity of lncRNAs. However, very little work has been done to identify ribosome-associated lncRNAs, here defined as lncRNAs interacting with ribosomes related to protein synthesis as well as other unclear biological functions. Results: On average, 39.17% of expressed lncRNAs were observed to interact with ribosomes in human and 48.16% in mouse. We developed the ribosomal association index (RAI), which quantifies the evidence for ribosomal associability of lncRNAs over various tissues and cell types, to catalog 691 and 409 lncRNAs that are robustly associated with ribosomes in human and mouse, respectively. Moreover, we identified 78 and 42 lncRNAs with a high probability of coding peptides in human and mouse, respectively. Compared with ribosome-free lncRNAs, ribosome-associated lncRNAs were observed to be more likely to be located in the cytoplasm and more sensitive to nonsense-mediated decay. Conclusion: Our results suggest that RAI can be used as an integrative and evidence-based tool for distinguishing between ribosome-associated and free lncRNAs, providing a valuable resource for the study of lncRNA functions.

• Access to Document (DOI)

Solar-panel and parasol strategies shape the proteorhodopsin distribution pattern in marine Flavobacteriia

Yohei Kumagai, Susumu Yoshizawa, Yu Nakajima, Mai Watanabe, Tsukasa Fukunaga, Yoshitoshi Ogura, Tetsuya Hayashi, Kenshiro Oshima, Masahira Hattori, Masahiko Ikeuchi, Kazuhiro Kogure, Edward F. Delong, Wataru Iwasaki

ISME Journal 12 （ 5 ） 1329 - 1343 2018年05月

査読有り,  ISSN  1751-7362

　概要を見る

Proteorhodopsin (PR) is a light-driven proton pump that is found in diverse bacteria and archaea species, and is widespread in marine microbial ecosystems. To date, many studies have suggested the advantage of PR for microorganisms in sunlit environments. The ecophysiological significance of PR is still not fully understood however, including the drivers of PR gene gain, retention, and loss in different marine microbial species. To explore this question we sequenced 21 marine Flavobacteriia genomes of polyphyletic origin, which encompassed both PR-possessing as well as PR-lacking strains. Here, we show that the possession or alternatively the lack of PR genes reflects one of two fundamental adaptive strategies in marine bacteria. Specifically, while PR-possessing bacteria utilize light energy ("solar-panel strategy"), PR-lacking bacteria exclusively possess UV-screening pigment synthesis genes to avoid UV damage and would adapt to microaerobic environment ("parasol strategy"), which also helps explain why PR-possessing bacteria have smaller genomes than those of PR-lacking bacteria. Collectively, our results highlight the different strategies of dealing with light, DNA repair, and oxygen availability that relate to the presence or absence of PR phototrophy.

• Access to Document (DOI)

RIblast: an ultrafast RNA-RNA interaction prediction system based on a seed-and-extension approach

Tsukasa Fukunaga, Michiaki Hamada

Bioinformatics (Oxford, England) 33 （ 17 ） 2666 - 2674 2017年09月

筆頭著者, 責任著者, 査読有り,  ISSN  1367-4803

　概要を見る

Motivation: LncRNAs play important roles in various biological processes. Although more than 58 000 human lncRNA genes have been discovered, most known lncRNAs are still poorly characterized. One approach to understanding the functions of lncRNAs is the detection of the interacting RNA target of each lncRNA. Because experimental detections of comprehensive lncRNA-RNA interactions are difficult, computational prediction of lncRNA-RNA interactions is an indispensable technique. However, the high computational costs of existing RNA-RNA interaction prediction tools prevent their application to large-scale lncRNA datasets.

• Access to Document (DOI)

Inactivity periods and postural change speed can explain atypical postural change patterns of Caenorhabditis elegans mutants

Tsukasa Fukunaga, Wataru Iwasaki

BMC Bioinformatics （BIOMED CENTRAL LTD）  18 （ 1 ） 46 2017年01月

筆頭著者, 責任著者, 査読有り,  ISSN  1471-2105

　概要を見る

Background: With rapid advances in genome sequencing and editing technologies, systematic and quantitative analysis of animal behavior is expected to be another key to facilitating data-driven behavioral genetics. The nematode Caenorhabditis elegans is a model organism in this field. Several video-tracking systems are available for automatically recording behavioral data for the nematode, but computational methods for analyzing these data are still under development. Results: In this study, we applied the Gaussian mixture model-based binning method to time-series postural data for 322 C. elegans strains. We revealed that the occurrence patterns of the postural states and the transition patterns among these states have a relationship as expected, and such a relationship must be taken into account to identify strains with atypical behaviors that are different from those of wild type. Based on this observation, we identified several strains that exhibit atypical transition patterns that cannot be fully explained by their occurrence patterns of postural states. Surprisingly, we found that two simple factors-overall acceleration of postural movement and elimination of inactivity periods-explained the behavioral characteristics of strains with very atypical transition patterns; therefore, computational analysis of animal behavior must be accompanied by evaluation of the effects of these simple factors. Finally, we found that the npr-1 and npr-3 mutants have similar behavioral patterns that were not predictable by sequence homology, proving that our data-driven approach can reveal the functions of genes that have not yet been characterized. Conclusion: We propose that elimination of inactivity periods and overall acceleration of postural change speed can explain behavioral phenotypes of strains with very atypical postural transition patterns. Our methods and results constitute guidelines for effectively finding strains that show "truly" interesting behaviors and systematically uncovering novel gene functions by bioimage-informatic approaches.

• Access to Document (DOI)

Rtools: a web server for various secondary structural analyses on single RNA sequences

Michiaki Hamada, Yukiteru Ono, Hisanori Kiryu, Kengo Sato, Yuki Kato, Tsukasa Fukunaga, Ryota Mori, Kiyoshi Asai

Nucleic acids research （OXFORD UNIV PRESS）  44 （ W1 ） W302 - W307 2016年07月

査読有り,  ISSN  0305-1048

　概要を見る

The secondary structures, as well as the nucleotide sequences, are the important features of RNA molecules to characterize their functions. According to the thermodynamic model, however, the probability of any secondary structure is very small. As a consequence, any tool to predict the secondary structures of RNAs has limited accuracy. On the other hand, there are a few tools to compensate the imperfect predictions by calculating and visualizing the secondary structural information from RNA sequences. It is desirable to obtain the rich information from those tools through a friendly interface. We implemented a web server of the tools to predict secondary structures and to calculate various structural features based on the energy models of secondary structures. By just giving an RNA sequence to the web server, the user can get the different types of solutions of the secondary structures, the marginal probabilities such as base-paring probabilities, loop probabilities and accessibilities of the local bases, the energy changes by arbitrary base mutations as well as the measures for validations of the predicted secondary structures. The web server is available at http://rtools.cbrc.jp, which integrates software tools, CentroidFold, CentroidHomfold, IPKnot, CapR, Raccess, Rchange and RintD.

• Access to Document (DOI)

GroupTracker: Video tracking system for multiple animals under severe occlusion

Tsukasa Fukunaga, Shoko Kubota, Shoji Oda, Wataru Iwasaki

Computational Biology and Chemistry （ELSEVIER SCI LTD）  57   39 - 45 2015年12月

筆頭著者, 責任著者, 査読有り,  ISSN  1476-9271

　概要を見る

Quantitative analysis of behaviors shown by interacting multiple animals can provide a key for revealing high-order functions of their nervous systems. To resolve these complex behaviors, a video tracking system that preserves individual identity even under severe overlap in positions, i.e., occlusion, is needed. We developed GroupTracker, a multiple animal tracking system that accurately tracks individuals even under severe occlusion. As maximum likelihood estimation of Gaussian mixture model whose components can severely overlap is theoretically an ill-posed problem, we devised an expectation-maximization scheme with additional constraints on the eigenvalues of the covariance matrix of the mixture components. Our system was shown to accurately track multiple medaka (Oryzias latipes) which freely swim around in three dimensions and frequently overlap each other. As an accurate multiple animal tracking system, GroupTracker will contribute to revealing unexplored structures and patterns behind animal interactions. The Java source code of GroupTracker is available at https://sites.google.com/site/fukunagatsu/software/group-tracker.

• Access to Document (DOI)

MiFish, a set of universal PCR primers for metabarcoding environmental DNA from fishes: Detection of more than 230 subtropical marine species

M. Miya, Y. Sato, T. Fukunaga, T. Sado, J. Y. Poulsen, K. Sato, T. Minamoto, S. Yamamoto, H. Yamanaka, H. Araki, M. Kondoh, W. Iwasaki

Royal Society Open Science （ROYAL SOC）  2 （ 7 ） 150088 2015年07月

査読有り,  ISSN  2054-5703

　概要を見る

We developed a set of universal PCR primers (MiFish-U/E) for metabarcoding environmental DNA (eDNA) from fishes. Primers were designed using aligned whole mitochondrial genome (mitogenome) sequences from 880 species, supplemented by partial mitogenome sequences from 160 elasmobranchs (sharks and rays). The primers target a hypervariable region of the 12S rRNA gene (163–185 bp), which contains sufficient information to identify fishes to taxonomic family, genus and species except for some closely related congeners. To test versatility of the primers across a diverse range of fishes, we sampled eDNA from four tanks in the Okinawa Churaumi Aquarium with known species compositions, prepared dual-indexed libraries and performed paired-end sequencing of the region using high-throughput next-generation sequencing technologies. Out of the 180 marine fish species contained in the four tanks with reference sequences in a custom database, we detected 168 species (93.3%) distributed across 59 families and 123 genera. These fishes are not only taxonomically diverse, ranging from sharks and rays to higher teleosts, but are also greatly varied in their ecology, including both pelagic and benthic species living in shallow coastal to deep waters. We also sampled natural seawaters around coral reefs near the aquarium and detected 93 fish species using this approach. Of the 93 species, 64 were not detected in the four aquarium tanks, rendering the total number of species detected to 232 (from 70 families and 152 genera). The metabarcoding approach presented here is non-invasive, more efficient, more cost-effective and more sensitive than the traditional survey methods. It has the potential to serve as an alternative (or complementary) tool for biodiversity monitoring that revolutionizes natural resource management and ecological studies of fish communities on larger spatial and temporal scales.

• Access to Document (DOI)

Capr: Revealing structural specificities of rna-binding protein target recognition using clip-seq data

Tsukasa Fukunaga, Haruka Ozaki, Goro Terai, Kiyoshi Asai, Wataru Iwasaki, Hisanori Kiryu

Genome Biology （BioMed Central Ltd.）  15 （ 1 ） R16 2014年

筆頭著者, 責任著者, 査読有り,  ISSN  1474-7596

　概要を見る

RNA-binding proteins (RBPs) bind to their target RNA molecules by recognizing specific RNA sequences and structural contexts. The development of CLIP-seq and related protocols has made it possible to exhaustively identify RNA fragments that bind to RBPs. However, no efficient bioinformatics method exists to reveal the structural specificities of RBP-RNA interactions using these data. We present CapR, an efficient algorithm that calculates the probability that each RNA base position is located within each secondary structural context. Using CapR, we demonstrate that several RBPs bind to their target RNA molecules under specific structural contexts.

• Access to Document (DOI)

Mitofish and mitoannotator: A mitochondrial genome database of fish with an accurate and automatic annotation pipeline

Wataru Iwasaki, Tsukasa Fukunaga, Ryota Isagozawa, Koichiro Yamada, Yasunobu Maeda, Takashi P. Satoh, Tetsuya Sado, Kohji Mabuchi, Hirohiko Takeshima, Masaki Miya, Mutsumi Nishida

Molecular Biology and Evolution （OXFORD UNIV PRESS）  30 （ 11 ） 2531 - 2540 2013年11月

査読有り,  ISSN  0737-4038

　概要を見る

Mitofish is a database of fish mitochondrial genomes (mitogenomes) that includes powerful and precise de novo annotations for mitogenome sequences. Fish occupy an important position in the evolution of vertebrates and the ecology of the hydrosphere, and mitogenomic sequence data have served as a rich source of information for resolving fish phylogenies and identifying new fish species. The importance of a mitogenomic database continues to grow at a rapid pace as massive amounts of mitogenomic data are generated with the advent of new sequencing technologies. A severe bottleneck seems likely to occur with regard to mitogenome annotation because of the overwhelming pace of data accumulation and the intrinsic difficulties in annotating sequences with degenerating transfer RNA structures, divergent start/stop codons of the coding elements, and the overlapping of adjacent elements. To ease this data backlog, we developed an annotation pipeline named MitoAnnotator. MitoAnnotator automatically annotates a fish mitogenome with a high degree of accuracy in approximately 5 min; thus, it is readily applicable to data sets of dozens of sequences. MitoFish also contains re-annotations of previously sequenced fish mitogenomes, enabling researchers to refer to them when they find annotations that are likely to be erroneous or while conducting comparative mitogenomic analyses. For users who need more information on the taxonomy, habitats, phenotypes, or life cycles of fish, MitoFish provides links to related databases. MitoFish and MitoAnnotator are freely available at http://mitofish.aori.u-tokyo.ac.jp/ (last accessed August 28, 2013); all of the data can be batch downloaded, and the annotation pipeline can be used via a web interface. © The Author 2013.

• Access to Document (DOI)

Evolutionary Origin of the Scombridae (Tunas and Mackerels): Members of a Paleogene Adaptive Radiation with 14 Other Pelagic Fish Families

Masaki Miya, Matt Friedman, Takashi P. Satoh, Hirohiko Takeshima, Tetsuya Sado, Wataru Iwasaki, Yusuke Yamanoue, Masanori Nakatani, Kohji Mabuchi, Jun G. Inoue, Jan Yde Poulsen, Tsukasa Fukunaga, Yukuto Sato, Mutsumi Nishida

PLoS ONE 8 （ 9 ） e73535 2013年09月

査読有り,  ISSN  1932-6203

　概要を見る

Uncertainties surrounding the evolutionary origin of the epipelagic fish family Scombridae (tunas and mackerels) are symptomatic of the difficulties in resolving suprafamilial relationships within Percomorpha, a hyperdiverse teleost radiation that contains approximately 17,000 species placed in 13 ill-defined orders and 269 families. Here we find that scombrids share a common ancestry with 14 families based on (i) bioinformatic analyses using partial mitochondrial and nuclear gene sequences from all percomorphs deposited in GenBank (10,733 sequences) and (ii) subsequent mitogenomic analysis based on 57 species from those targeted 15 families and 67 outgroup taxa. Morphological heterogeneity among these 15 families is so extraordinary that they have been placed in six different perciform suborders. However, members of the 15 families are either coastal or oceanic pelagic in their ecology with diverse modes of life, suggesting that they represent a previously undetected adaptive radiation in the pelagic realm. Time-calibrated phylogenies imply that scombrids originated from a deep-ocean ancestor and began to radiate after the end-Cretaceous when large predatory epipelagic fishes were selective victims of the Cretaceous-Paleogene mass extinction. We name this clade of open-ocean fishes containing Scombridae "Pelagia" in reference to the common habitat preference that links the 15 families. © 2013 Miya et al.

• Access to Document (DOI)