Riken Research Volume 8 Number 11

NOVEMBER 2013 RIKEN RESEARCH VOLUME 8 NUMBER 11

Unraveling splicing in plant development RIKEN PLACES: Introducing the facilities that drive RIKEN’s world-class research The Center for Developmental Biology in Kobe applies its pioneering research to regenerative medicine. TABLE OF CONTENTS

Table of contents

HIGHLIGHT OF THE MONTH 4 Multifunctional molecules aid mutation analysis RESEARCH HIGHLIGHTS 6 Rapid recall to fight familiar foes 7 Improvements in efficiency stack up 4 8 A new twist in plant development 9 Seeing the brain at greater depth 10 Drug treatment improves survival of insulin-producing cells 11 Unraveling the secrets of the turtle shell 12 A better trigger for targeted drug delivery 13 An energy-efficiency lead for nitrogen fertilizer production 11 14 From a drop of blood, a clone 15 Visualizing how infection exacerbates lung disease 16 Honing in on developmental epigenetics RIKEN PLACES 17 Realizing the potential of regenerative biology FRONTLINE 18 Monitoring the rapidly changing Universe 18 RIKEN PEOPLE 22 Promoting sound management at RIKEN NEWS ROUNDUP 23 RIKEN forges new ties in India RIKEN–Shanghai Jiao Tong University joint workshop RIKEN signs Memorandum of Understanding with Shanghai 23 Institute of Optics and Fine Mechanics

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RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp 3 HIGHLIGHT OF THE MONTH

Biology Multifunctional molecules aid mutation analysis

Specialized molecular probes that light up on binding to their target allow scientists to quantify DNA samples and detect specific mutations in a single test

Over the past decade, DNA sequencing technology has become faster and more powerful while also growing more affordable and accessible. As a result, researchers have been able to chart a multitude of genomic variations that could potentially contribute to the development of various cancers as well as a host of hereditary diseases. Identifying a candidate mutation is only the beginning, however, as independent assays are required to confirm the link between gene and disease. Matthias Harbers and Kengo Usui from the Division of Genomic Technologies at the RIKEN Center for Life Science Technologies have now Figure 1: Specialized fluorescent probes allow scientists to quantify and detect mutations in developed a special class of probes that target DNA with a single PCR-based test. could accelerate the development of © iStock/Thinkstock such assays by allowing scientists to simultaneously quantify target DNA sequences while also detecting the fluorescence when in close proximity. through a technique called melting 1 presence of mutations of interest . When the ECHO binds DNA, the dye curve analysis. In contrast, PCR primers Scientists have used variations of a molecules become separated as they generally need to be a perfect match for technique called real-time polymerase insert themselves into the double-helix their target sequence to work reliably. chain reaction (PCR) to amplify target structure, generating a signal that is Harbers, Usui and their colleagues DNA while monitoring the progress of proportional to the target DNA’s ampli- therefore opted to modify ECHOs so that the amplification. These data are used to fication. To efficiently couple this quan- they serve as detection probes that act in determine the original amount of genetic titation with the ability to directly detect parallel with a separate set of real-time starting material, which can be valuable the presence or absence of mutations, the PCR primers. information in a diagnostic context. researchers set out to devise a modified The ECHO-based ‘Eprobes’ developed Real-time PCR is performed using short ECHO variant that combines both by the research team are designed to stretches of DNA called ‘primers’, which functions into a single assay. bind to potential mutation-containing bracket the target sequence of interest sites within the region being amplified, Dual-purpose probes and initiate amplification. Harbers and allowing amplification detection in real Usui previously worked with a special DNA strands that are directly time (Fig. 2). However, Eprobes also class of fluorescently labeled molecules complementary to each other bind contain a chemical group that prevents called ‘exciton-controlled hybridization- more tightly than those that contain them from being incorporated into the sensitive fluorescent oligonucleotides’ mismatches. Scientists can use targeted amplified DNA and instead causes them (ECHOs), which feature a pair of dye probes to detect the presence or absence to dissociate from the target as the sample molecules that quench each other’s of mutations based on this principle is heated during the PCR process. Once

for mapping chromosomal regions of 5’ G C G C T G C A C G 3’ Eprobe OH interest, allowing scientists to directly identify clinically relevant chromosomal abnormalities using a microscope. “Any disease for which the outcome or treatment course can be determined by mutation detection could potentially be targeted by our technology,” notes Usui.

1. Hanami, T., Delobel, D., Kanamori, H., Tanaka, Y., Kimura, Y., Nakasone, A., Figure 2: Eprobes contain a pair of dye molecules that interfere with each other’s fluorescence (top) until they bind to a complementary DNA target sequence (bottom)—a process that Soma, T., Hayashizaki, Y., Usui, K. & separates the two dyes and generates a signal. A chemical blocking group (yellow oval) prevents Harbers, M. Eprobe mediated real-time PCR the Eprobes from being incorporated in the PCR, so that they can be used for mutational analysis monitoring and melting curve analysis. after the real-time PCR reaction is complete. PLoS ONE 8, e70942 (2013).

ABOUT THE RESEARCHERS

the PCR has concluded, the Eprobes go could conduct ‘multiplexed’ assays to back to detecting mutations. “Since their look at several different mutations or fluorescence activity is still maintained genomic regions simultaneously. To after PCR, we can carry out melting curve demonstrate this concept, the research- analysis as a post-PCR assay in the same ers combined a pair of Eprobes and tube without additional modification of primer sets to simultaneously inves- the reaction mix,” says Usui. tigate both EGFR and KRAS, another As an initial demonstration, the gene prone to oncogenic mutations. researchers designed a series of Eprobes “At this point, we have two dyes that © 2013 RIKEN to recognize a segment of the gene work well and have also determined Matthias Harbers was born in encoding the epidermal growth factor that it may be possible to work with Göttingen, Germany, in 1960. He receptor (EGFR) protein, targeting a Eprobes of three different melting tem- received his PhD from the University mutation associated with cancer risk. peratures in one assay,” says Harbers. of Hamburg in 1989. Harbers worked The Eprobes performed well in initial “This would in theory enable ‘six-plex- in Sweden and France before joining experiments, achieving sensitive ing’ and could be extended once we RIKEN as a visiting scientist at the detection of amplification over the have more dyes.” Harbers further notes Omics Science Center, which was later reorganized into the RIKEN Center for course of the real-time PCR process. that the expansion of these multiplex- Life Science Technologies. As a member Importantly, these Eprobes also proved ing capabilities will be a key objective of the FANTOM Project, Harbers has to be capable of distinguishing between in enabling Eprobes to achieve their contributed to the development of samples that contain only mutant target potential as diagnostic tools. full-length cDNA cloning and analysis DNA from those that contain both The research team is currently methods (Cap Analysis of Gene normal and mutated sequences. Such working with clinicians at Gunma Expression (CAGE) technology). His discrimination is important for many University Hospital to test the sensitivity current work focuses on advancing molecular diagnostic methods. diseases, where a patient’s prognosis of these reagents for detecting relatively can differ depending on whether one scarce mutations within the highly Kengo Usui was born in Kasugai in or both copies of a chromosome carry heterogeneous context of a tumor. “The 1974. After obtaining his PhD from Gifu a particular mutation. Furthermore, frequency of mutation in samples from University in 2003, Usui worked as a unlike other fluorescent detection cancer patients is usually quite low— researcher for the Japan Science and tools, Eprobes are completely dependent under 5 per cent—and the detection Technology Agency’s CREST program, on DNA binding to generate a signal of such rare mutations is our next where he developed self-assembling proteins known as ‘Nanolego’. In 2008, and are therefore far less likely to challenge,” says Usui. This technology he joined the RIKEN Omics Science produce false positive results that could is also undergoing commercial Center and has since been conducting confound diagnosis. development through K.K.DNAFORM, a research into the development of a rapid RIKEN venture company, and scientists Monitoring multiple mutations genetic diagnostic system. Usui became may soon be able to obtain customized unit leader of the Genetic Diagnosis By combining Eprobes labeled with Eprobes for a variety of imaging Technology Unit at the RIKEN Center for different fluorescent dyes that exhibit applications. For example, sequence- Life Science Technologies in 2013. different melting behaviors, scientists specific Eprobes could be designed

Rapid recall to fight familiar foes

By tinkering with immune cell development, researchers learn how the body mounts an accelerated response to recurring threats

The immune system’s first encounter with a potential threat is a valuable learning experience. Through a process of genetic recombination, our immune B cells can potentially produce a wide array of B-cell receptor (BCR) molecules, each recogniz- ing a distinct molecular target. When a naive B cell bumps into its specific target, it initiates an immune response that yields antibodies with the same specificity as its BCR, but also gives rise to ‘memory cells’ that can quickly recognize the target if it appears in the future. Working with genetically modified mice, Tomohiro Kurosaki’s team at the RIKEN Center for

Integrative Medical Sciences in Yokohama Figure 1: Memory B cells quickly recognize threats previously encountered by the immune has now gained insight into how memory system to mount a rapid and robust antibody response. 1 cells mobilize . © Hemera/Thinkstock “Memory B cells achieve rapid and robust antibody production during a secondary immune response, but its molecular mechanism was unknown,” a known antigen, nitrophenol. As a protein called Bach2. “We found that explains Kohei Kometani, a researcher expected, the former cells proliferated Bach2 is reduced in memory B cells, and in Kurosaki’s lab and lead author of in response to nitrophenol, while the is important for their enhanced antibody the study. latter promptly developed into antibody- production,” says Kometani. Naive B cells typically produce BCRs secreting plasma cells, as occurs in a By revealing this IgG-independent and antibodies that belong to the immu- typical secondary immune response. To mechanism, these results should help noglobulin M (IgM) class of proteins. determine whether IgG is specifically resolve the long-standing debate over In contrast, memory B cells produce an responsible, Kurosaki’s group generated memory cell function. However, this alternative immunoglobulin G (IgG) cloned mice derived from an IgG memory finding is just a starting point, and Kuro- subtype of BCRs and antibodies through cell that recognizes nitrophenol. saki’s group is now engaged in exploring an additional gene recombination The resulting animals produced the upstream factors that switch off process called ‘class switching’. Some nitrophenol-specific IgG naive B cells, Bach2 production in memory cells. researchers believe that the IgG form of which do not normally occur in nature. 1. Kometani, K., Nakagawa, R., Shinnakasu, BCR contains structural elements that Remarkably, these cells responded to R., Kaji, T., Rybouchkin, A., Moriyama, S., stimulate the memory B-cell response, nitrophenol by proliferating in essen- Furukawa, K., Koseki, H., Takemori, T. & while others have favored cellular mech- tially the same fashion as IgM naive Kurosaki, T. Repression of the transcription anisms besides IgG-induced signaling. cells, suggesting that IgG alone does not factor Bach2 contributes to predisposition of In initial experiments, the research- drive the memory response. A compara- IgG1 memory B cells toward plasma cell differ- ers worked with IgM naive and IgG tive analysis of gene expression revealed entiation. Immunity 39, 136–147 (2013). memory cells that specifically recognize an alternative mechanism, controlled by

6 RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp RESEARCH HIGHLIGHTS

Improvements in efficiency stack up

An unexpected but welcome change in polymer structure opens a new avenue in the search for improved organic solar cell efficiency

Solar cells based on organic polymers are of great interest because the materials are Edge-on orientation Face-on orientation both cheaper to make and easier to process than those used in traditional inorganic solar cells. To date, however, the very best power conversion efficiencies for polymer solar cells remain below the threshold for practical application. Itaru Osaka from the Emergent Molecular Function Research Group at the RIKEN Center for Emergent Matter Science and co-workers have now serendipitously discovered that changing the polymer’s structure results in a significant enhancement of power 1 conversion efficiency . When light energy is absorbed by the polymer in a polymer solar cell, electrons Polymer stacking direction Charge carrier ﬂow are excited to higher energy levels to produce a high-energy electron and a corresponding electron ‘hole’. To convert Figure 1: A small change in polymer structure affects how the polymer chains stack together the light energy into electrical current, in a thin film, resulting in a dramatic improvement in solar cell efficiency. these electrons and holes have to move © 2013 Itaru Osaka, RIKEN Center for Emergent Matter Science through the polymer to the electrodes before they recombine and the energy is lost. Much research has been devoted In the solar cells, the polymer is enhancement in other polymers in order to understanding how to improve this deposited as a thin film, and analysis to move closer to producing polymer solar conversion process. revealed that these new ‘alkylated’ cells that can truly compete with the Osaka and his colleagues had been polymers were arranged so that the 15% or greater efficiency of inorganic solar working with a particular type of polymer chains lay flat in stacks on cells. “We need a greater understanding copolymer containing a repeating naph- the surface rather than aligned per- of why this switch in polymer orienta- thodithiophene–naphthobisthiadiazole pendicular to it. This causes the charge tion occurs, and then we need to apply structure called PNNT-DT. “PNNT-DT has carriers—electrons and holes—to move it to other polymers that can absorb a very low solubility,” explains Osaka, “so perpendicular to the surface rather than wider range of visible light wavelengths,” we were interested in attaching addi- parallel, improving the power conver- he says. tional alkyl side chains to the polymer to sion efficiency (Fig. 1). “This unexpected 1. Osaka, I., Kakara, T., Takemura, N., Koganezawa, improve its processability.” As expected, change in orientation produced solar cells T. & Takiyama, K. Naphthodithiophene– this modification significantly improved with an efficiency of up to 8.2% compared naphthobisthiadiazole copolymers for solar the solubility of the polymer, but also sig- with just 5.5% for the unalkylated cells: alkylation drives the polymer backbone nificantly and unexpectedly improved the material,” says Osaka. flat and promotes efficiency. Journal of the power conversion efficiencies of solar cells Ultimately, Osaka and his co-workers American Chemical Society 135, 8834–8837 (2013). made with the polymer. hope to exploit this dramatic efficiency

RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp 7 RESEARCH HIGHLIGHTS

A new twist in plant development

An enzyme that unravels RNA molecules has a crucial role in plant development

Before messenger RNA molecules can be translated into amino acids and eventually functional proteins, the primary gene transcripts must be spliced to remove non-coding sequences. Misato Ohtani from the RIKEN Center for Sustainable Resource Science and colleagues have now identified a key protein involved in splicing and shown that it is essential for several aspects of 1 plant development . Splicing is carried out by the spliceosome, which detects the non-coding sequences—called introns—and splices the primary RNA transcripts by a precisely regulated step-by-step Figure 1: Wild-type (top row) and rid1 mutants (bottom row) grown at 22 °C for 2 weeks and process. The spliceosome itself consists then at 22 °C (left) or 28 °C (right) for an additional 2 weeks. The rid1 mutants stopped growing of five different RNA–protein complexes, and died after exposure to higher temperature. called snRNPs. These complexes have Reproduced from Ref. 1 © 2013 American Society of Plant Biologists over 50 other associated proteins, all of which are vital for proper spliceosome assembly. However, the roles of genetic engineering to introduce non- Finally, the researchers investigated only a few of these proteins have so far coding sequences into the gene encoding genetically engineered plants lacking been characterized. yellow fluorescent protein (YFP), the RID1 gene. Those with one copy of Ohtani and her colleagues investi- and then transiently introduced the the gene developed normally, but those gated one of these co-factors of spliceo- construct into normal and mutated missing both had abnormally shaped some assembly by performing genetic plant cells. In wild-type plants incubated female gametophytes, which usually analyses on mutated Arabidopsis thaliana at 22 or 28 °C, almost all of the YFP form the egg cells. plants displaying temperature-sensitive messenger RNA was spliced correctly. “We subsequently performed a developmental defects (Fig. 1). Their In the mutants, however, splicing effi- genome-wide transcriptome analysis target was the mutated gene associ- ciency was markedly reduced at 28 °C. to find out which genes were affected ated with these defects, called ROOT The researchers then examined the in our mutants,” says Ohtani. “We INITIATION DEFECTIVE1 or RID1. They distribution of the enzyme by fusing have already identified several can- found that the associated DNA sequence part of its gene to the YFP gene, or didates, and are currently testing corresponds to a protein of the DEAH-box the gene encoding an enzyme called their functions.” RNA helicase family of enzymes, which β-glucuronidase. In seedlings, RID1 1. Ohtani, M., Demura, T. & Sugiyama, M. catalyze the twisting and unraveling was found in the shoot, roots and Arabidopsis ROOT INITIATION DEFECTIVE1, a of the two strands of messenger RNA tissues that eventually form the leaves, DEAH-Box RNA helicase involved in molecules to allow splicing. and during reproductive stages in the pre-mRNA splicing, is essential for plant To confirm the RID1 enzyme’s role in flower buds and parts of the female development. The Plant Cell 25, 2056-2069 (2013). splicing, Ohtani and her colleagues used reproductive system.

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Seeing the brain at greater depth

An agent that enhances light transmission through brain tissue enables microscopy of the mouse brain from top to bottom

Brain tissue is opaque, so classical microscopy methods require slicing the brain into ultrathin slivers to allow light to shine through. Techniques have been developed to enhance brain tissue transparency, but the chemicals used have a range of limitations. Takeshi Imai and colleagues from the Labora- tory for Sensory Circuit Formation at the RIKEN Center for Developmen- tal Biology have now developed a ‘clearing’ agent that resolves many of 1 these limitations . Existing brain clearing agents have a range of undesirable side-effects, such as causing the brain tissue to swell or shrink, quenching the signal of fluorescent probes used to label individual neurons, rendering the brain tissue Figure 1: A fluorescent cross-section of a mouse brain after treatment using the SeeDB very fragile and difficult to work with, clearing agent. or requiring very long incubation times © 2013 Takeshi Imai et al., RIKEN Center for Developmental Biology to clear the brain tissue. Some of the existing methods also require special preparation methods that are prohibitive to most researchers. advantage of the new clearing agent is SeeDB will allow researchers to obtain Imai and his colleagues searched for its ease of preparation, which allows clearer pictures of neuronal circuitry a new clearing agent by testing various researchers to produce and use it in during development and disease in many combinations of chemicals. The combi- their lab. species. The next challenge, notes Imai, nation they found to be most effective The researchers then used SeeDB to will be to accelerate the imaging process. consisted of the sugar fructose mixed clear brain tissue from an adult mouse “With existing fluorescence microscopes, with a thiol compound to prevent the containing fluorescently marked it takes a very long time—10 to 20 hours— tissue from turning brown or from neurons. Using a standard microscope to get images of just a part of the mouse fluorescing on its own. The researchers lens and brain tissue incubated in SeeDB brain,” he explains. “The development of showed that this solution, called SeeDB at room temperature, they were able to high-speed microscopes and computers (short for ‘see deep brain’), could enhance view 4 millimeters into the brain. Using for data analysis will be essential for the transparency of mouse embryos and a custom-made microscope lens and large-scale imaging in the future.” young mouse brains. Moreover, despite brain tissue incubated in SeeDB at body 1. Ke, M.-T., Fujimoto, S. & Imai, T. SeeDB: a adult brain tissue having fiber tracts temperature, they were able to obtain simple and morphology-preserving optical that cannot be cleared by other methods, images from the top to the bottom of the clearing agent for neuronal circuit reconstruc- SeeDB was able to render adult mouse adult mouse brain—about 6 millimeters tion. Nature Neuroscience 16, 1154–1161 (2013). brains completely transparent. Another in depth (Fig. 1).

RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp 9 RESEARCH HIGHLIGHTS

Drug treatment improves survival of insulin-producing cells

Pretreatment with a calcium-blocking drug improves the effectiveness of islet transplantation for diabetes in mice

The transplantation of insulin- DonorRecipient (with type 1 diabetes) producing islet cells from a donor Islets in pancreas pancreas could help diabetes sufferers Esophagus avoid the need for daily insulin Diaphragm injections. However, the use of this Common Portal vein experimental procedure is hampered by Liver bile duct an immune response in the recipient Stomach that often rejects the transplanted Gall bladder islet cells. Masaru Taniguchi from the Laboratory for Immune Regulation Pancreas at the RIKEN Center for Integrative Isolated Medical Sciences and Yohichi Yasunami islets Islets in portal vein from Fukuoka University have now led research that has improved the efficiency of the procedure by pretreating the islet cells with a Figure 1: The process of clinical islet transplantation. drug that blocks the sodium–calcium 1 Reproduced from PLoS Medicine 1, e58 (2004). Licensed under CC by 2.5 at dx.doi.org/10.1371/journal.pmed.0010058. © 2004 M. A. Naftanel and D. M. Harlan exchanger (NCX) protein . Islet transplantation often involves the use of islet cells from two or three different donors in order to achieve islet transplantation,” says Taniguchi. After transplanting pretreated and sufficient cell engraftment. “This low Notably, the method allows for untreated islets into diabetic mice, the efficiency has been a major obstacle improved engraftment efficiencies research team found that mice receiving facing clinical islet transplantation,” without requiring transplant recipi- SEA0400-treated islets displayed normal says Taniguchi. ents to take any additional anti-rejec- blood sugar control. In contrast, the Taniguchi, Yasunami and their tion drugs. “Our new strategy to target control animals, which received the same respective lab groups set out to improve donor islets does not add further risks number of untreated islets, experienced the islet transplantation procedure by to recipients,” notes Taniguchi. elevated blood sugar levels due to a lack pretreating islet cells prior to trans- The drug pretreatment is thought to of functional insulin-producing cells, plantation with a drug that blocks work by stopping NCX from boosting which presumably had been attacked by the NCX protein. This pretreatment the intracellular levels of calcium the immune system. This same effect was protected the cells from innate immune ions. Normally, this calcium influx seen whether the transplanted islets were responses in the liver, the site of islet leads to low oxygen conditions, which human or murine in origin. transplantation, which led to longer- trigger the release of a protein called 1. Mera, T., Itoh, T., Kita, S., Kodama, S., Kojima, D., term survival of the cells in mouse high-mobility group box 1 (HMGB1) Nishinakamura, H., Okamoto, K., Ohkura, M., models of diabetes. from islets soon after their trans- Nakai, J., Iyoda, T. et al. Pretreatment of donor “Pretreatment of donor islets with plantation. HMGB1 in turn activates islets with the Na+/Ca2+ exchanger inhibitor an NCX inhibitor prior to transplan- immune cells, causing the early loss of improves the efficiency of islet transplanta- tation prevents early loss of trans- transplanted islets. The NCX-blocking tion. American Journal of Transplantation 13, planted islets and affords a new drug, called SEA0400, can prevent this 2154–2160 (2013). strategy to improve the efficiency of cascade of events.

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Unraveling the secrets of the turtle shell

A long-lived controversy over the origins of the turtle shell has now been resolved

For over 200 years, scientists have been split over the developmental origins of the turtle shell, unsure if it is an elaboration of the internal skeleton or an exoskeletal structure like that in crocodiles and alliga- tors. New research by Tatsuya Hirasawa of the Laboratory for Evolutionary Morphol- ogy at the RIKEN Center for Developmen- tal Biology and colleagues has now settled this controversy by revealing that the shell develops in the embryo as a modification 1 of the rib cage and vertebrae . Through detailed observations of the embryological development of the Chinese soft-shelled turtle Pelodiscus sinensis (Fig. 1), the researchers found that the ribs initially develop just as in other ver- tebrates, attached to the backbone with intercostal muscles in between. However, they observed that the intercostal muscle tissue degenerates during further development and is invaded by bony projec- Figure 1: The Chinese soft-shelled turtle Pelodiscus sinensis. tions called trabeculae, which gradually © 2013 Tatsuya Hirasawa, RIKEN Center for Developmental Biology fuse to form a bony plate. The trabeculae are produced in an area surrounded by bone membrane outside the skin tissue, or dermis. In contrast, the exoskeletal the earliest known turtle species, Odon- the ribs and the body wall of the turtle,” components in the alligator, called osteo- tochelys, in which the carapace does not says Hirasawa. “In the embryonic devel- derms, develop in the dermis layer of the form a closed shell, is best explained by opment of the turtle, the rib does not skin. The observations confirm the evo- similar embryological development to extend ventrally, which is very strange. lutionary continuity between the axial the modern turtle. Earlier marine reptiles We call this turtle-specific phenomenon endoskeleton and the turtle carapace, already contained examples of the large the ‘axial arrest’ of the rib. The signs of bridging the gap in body plan between the plate-like ribs that eventually became axial arrest are perhaps recognizable in turtle and other tetrapods. incorporated into the carapace. Recent some fossil marine reptiles. We want to Having determined that the carapace genomic analyses support the possibility unravel the evolution of this axial arrest, develops embryologically as a modifica- that the turtles and these marine reptiles by a combination of developmental tion of the internal vertebrate skeleton, are likely to be relatively closely related in biology and paleontology.” the researchers began investigating evolutionary terms. 1. Hirasawa, T., Nagashima, H. & Kuratani, S. the evolution of the turtle carapace by The researchers are now planning to The endoskeletal origin of the turtle carapace. studying fossil turtles and earlier marine expand their work. “We will further inves- Nature Communications 4, 2107 (2013). reptiles. They found that the form seen in tigate the evolution and development of

RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp 11 RESEARCH HIGHLIGHTS

A better trigger for targeted drug delivery

Protein-based drug carriers activated by the body’s biochemical energy carrier open up new possibilities for targeted drug delivery

Cell

Esterase

Biomolecular ‘nanocarriers’ formed by Drug the careful assembly of protein subunits are common in nature and perform a Esterase range of essential roles in biological processes, powered by the biological ATP energy carrier adenosine-5’-triphosphate Drug (ATP). Takuzo Aida from the RIKEN Center for Emergent Matter Science and colleague Shuvendu Biswas from the University of Tokyo have now led the development of a prototype artificial nanocarrier that uses ATP to fuel the 1 delivery of a therapeutic payload . Targeted drug delivery using artificial nanocarriers is a burgeoning area of clinical research, particularly for the Figure 1: A chaperonin-based drug delivery system. A drug compound is attached to an treatment of cancer. Most nanocarriers irreversibly denatured protein via an ester linker. The protein sits inside the chaperonin cavity, designed to date to specifically target which opens under the action of ATP in the intracellular environment. An esterase enzyme then cleaves the ester linker, freeing the drug. tumors generally rely on subtle changes in pH to sense cancerous environments. Modified from Ref. 1 © 2013 S. Biswas et al. However, the pH difference around cancers is typically not large enough to selectively activate drug delivery by proteins linked together by magnesium retained their biological function. They the nanocarriers. ions to form tubular structures. In also showed that fluorescent dye admin- Local ATP levels, on the other hand, nature, explains Aida, chaperonins istered to tumor-carrying mice using the vary significantly throughout the body. trap denatured proteins inside their nanocarriers selectively accumulated in ATP concentrations are over 200 times cavity through hydrophobic interactions cancer tissues and also the liver. “The higher within cells compared to the and assist refolding. Once the trapped liver absorbs most of the nanocarriers to extracellular environment and inflam- proteins are refolded, the chaperonins excrete them from the body, so that only mation around diseased tissue triggers bind to ATP and undergo a machine-like a small number of carriers reaches tumor an immune response that increases local opening motion that expels the guest tissues and cells,” says Aida. ATP production. proteins out of the cavity. The goal of the The team is currently undertaking “We envisioned that if our nanocarrier researchers was to exploit this ATP-ena- further development of their system for sensed high-concentration ATP and broke bled motion in their artificial nanocarrier drug delivery. “Research for delivering up into short-chain fragments because of to control payload transport and release. real drugs is now underway,” says Aida. motions generated by its constituents, In their proof-of-concept study, the 1. Biswas, S., Kinbara, K., Niwa, T., Taguchi, H., we could develop a conceptually new researchers showed that a denatured Ishii, N., Watanabe, S., Miyata, K., Kataoka, K. drug delivery system for tumor tissues fluorescent protein loaded into the nano- & Aida, T. Biomolecular robotics for chemome- and cells,” says Aida. carrier recovered its folding and lumi- chanically driven guest delivery fuelled by intra- The researchers assembled their nano- nescent properties through the action of cellular ATP. Nature Chemistry 5, 613–620 (2013). carriers using barrel-shaped chaperonin ATP, demonstrating that the chaperonins

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An energy-efficiency lead for nitrogen fertilizer production

The production of useful nitrogen compounds from atmospheric nitrogen could become considerably less energy-intensive thanks to a novel polyhydride complex

Nitrogen and phosphorus fertilizers are essential in modern agriculture and crucial to meeting the ever-growing global food demand. Nitrogen fertilizer, in the form of ammonia, is produced now in the same way that it has been for close to a century—by the energy-intensive Haber-Bosch process, which uses high temperatures and pressures to split nitrogen gas molecules. Takanori Shima, Zhaomin Hou and colleagues from the RIKEN Center for Sustainable Resource Science have now made a discovery that could allow ammonia and other nitrogen-bearing compounds to be produced 1 energy-efficiently at room temperature .

Nitrogen gas (N2), comprised of a pair of nitrogen atoms, is abundant in the Figure 1: Worldwide production of nitrogen fertilizer for agriculture exceeds 100 million tons atmosphere, but converting it to a useful a year. solid form by breaking the triple bond © iStockphoto/Thinkstock between the nitrogen atoms consumes considerable energy. Chemists have had difficulty in finding ways to break the Drawing on their expertise in rare- simultaneously to three titanium atoms triple bond at mild temperatures without earth hydrides, the researchers produced and that the hydrides migrated from resorting to special electron- and proton- a novel complex based on titanium— titanium to the nitrogen portion of the donating reagents, which are generally a transition metal that readily forms complex. “This is unprecedented—to nonrecyclable and expensive. nitrogen bonds. Their experiments observe N2 activation, bond cleavage Hou and his colleagues instead con- involved mixing the titanium precursor and N–H bond formation steps in one sidered multinuclear transition metal with hydrogen gas and N2 in a pressure reaction,” says Shima. hydrides—cage-like compounds in reactor at room temperature. Rather than Although the researchers are still which several metals are linked together the pure metal hydride they expected, investigating why the trinuclear by multiply bonded hydrogen atoms. the reaction produced a strained cubic titanium complex has such particu-

These hydrides can generate sufficient structure containing four bridged lar affinity for N2 compounds, they are electrons to break the triple bond and titanium hydrides and, intriguingly, a certain that these materials will provide also act as a hydrogen source for the pair of nitrogen–proton (N–H) units. a unique opportunity to develop innova- fixation of nitrogen as ammonia. The To understand how this complex tive nitrogen fixation strategies. team also suspected that the metal formed, the team went back and 1. Shima, T., Hu, S., Luo, G., Kang, X., Luo, Y. & centers could enhance N2 activation monitored each step of the reaction using Hou, Z. Dinitrogen cleavage and hydrogenation through cooperative effects seen in x-ray crystallography and isotope-labeled by a trinuclear titanium polyhydride complex. biological nitrogen fixation and the spectroscopy. They determined that N2 Science 340, 1549–1552 (2013). Haber-Bosch process. was activated and cleaved by binding

RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp 13 RESEARCH HIGHLIGHTS

From a drop of blood, a clone

A process for generating clones from blood may make it easier for scientists to preserve valuable lines of research animals

Over the last few decades, scientists have drawn upon a powerful arsenal of biotechnology techniques to establish a wide variety of genetically engineered mouse strains. These animals represent invaluable resources for studying mammalian development and disease, but many of these mouse lines are infertile or challenging to breed by con- ventional means. Atsuo Ogura and colleagues at the RIKEN BioResource Center have now developed a simplified cloning strategy that should make it easier for scientists to protect their painstakingly 1 developed mouse lines . “We have been undertaking somatic cell nuclear transfer experiments for the preservation of valuable mouse genetic Figure 1: A female mouse cloned from a single peripheral blood cell. resources,” explains Ogura. Somatic cell © 2013 Atsuo Ogura, RIKEN BioResource Center nuclear transfer (SCNT) is the standard technique for mammalian cloning, in which a nucleus from a donor cell of interest is transferred into an unferti- Although the success rate was The use of peripheral blood offers lized egg from which the nucleus has generally higher with cumulus cells, notable advantages for cloning compared been removed. The resulting cell acts Ogura was pleased to find that his with the collection of other source like a fertilized egg and gives rise to a team could successfully generate tissues, which can sometimes require clone of the donor animal. clones (Fig. 1) from two different blood euthanization of the donor animal. Ogura was interested in the possi- cell types—granulocytes and lympho- Although other, non-SCNT, techniques bility of using blood to obtain nuclei cytes. “Peripheral blood cells, especially are available for rescuing ‘endangered’ for SCNT as a more straightforward granulocytes, are terminally differenti- mouse lines, such methods require viable and less invasive donor cell harvest- ated cells and have a short life span,” he male germ cells and are therefore not ing procedure. As an initial test, the explains. “It was surprising that they universally applicable. Ogura’s priority researchers collected drops of blood can give rise to a new life by nuclear now is to boost the efficiency of periph- from the tails of donor animals and transfer.” Ogura’s team successfully eral blood SCNT so that the technique’s attempted to derive clones from various used granulocyte-based SCNT to clone reliability is on par with its simplicity. subtypes of blood cells. For comparison, four different genetically modified 1. Kamimura, S., Inoue, K., Ogonuki, N., they performed parallel SCNT experi- mouse lines. These initial results Hirose, M., Oikawa, M., Yo, M., Ohara, O., ments using cumulus cells, which indicate that the technique should be Miyoshi, H. & Ogura, A. Mouse cloning using a normally act as support cells for the broadly applicable, and Ogura proposes drop of peripheral blood. Biology of Reproduction oocyte and are commonly used as donors that it could even help preserve endan- 89, 24 (2013). for cloning. gered species in the wild.

14 RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp RESEARCH HIGHLIGHTS

Visualizing how infection exacerbates lung disease

A new mouse model combined with advanced three-dimensional imaging allows researchers to investigate how infection worsens emphysema

Chronic obstructive pulmonary disease (COPD) is a leading cause of death worldwide. The disease, characterized by constricted airways due to bronchi- tis and emphysema, is commonly seen in smokers but can also be brought on by environmental pollutants. The symptoms of the disease are known to be worsened by bacterial and viral infec- tions of the airways, but exactly why remains largely unclear. A research team led by Naoyuki Taniguchi from the RIKEN Global Research Cluster has now developed a mouse model that allows COPD exacerbation to be studied in 1 living animals . Figure 1: Three-dimensional visualizations of emphysema (yellow) in mice treated with Acute exacerbation of COPD as a result elastase, showing accelerated progression of disease after 12 weeks in mice exposed to LPS of infection of the airway is known to be (right) compared with mice treated only with saline solution (left). a major cause of death in COPD patients. © 2013 Reiko Fujinawa, RIKEN Global Research Cluster It is also known to accelerate the progression of the disease, but despite the disease’s prevalence, surprisingly little is visualizing three-dimensional variations The observed pathological changes known about the mechanism of exacer- in tissue density. They produced their mimic those found in human COPD bation or how to treat it. “Steroid therapy mouse model by exposing healthy mice exacerbation, meaning that this model is common for COPD exacerbation, to the chemical elastase, which results in could be used to help researchers gain a but its effectiveness is not clear,” says the development of emphysema-like lung better understanding of the underlying Taniguchi. “It is reported to be effective disease. Exacerbation of the disease was mechanisms of COPD and perhaps to in only 20% of patients, and sometimes then triggered by exposing the mice to a develop new treatments for it. “Using causes serious side effects.” single dose of lipopolysaccharide (LPS), this model mouse,” says Taniguchi, “we The development of a suitable animal a toxic component of bacterial cell walls are looking for biomarkers of the exac- model to specifically study COPD exac- that is known to cause inflammation. erbation process, and our final goal is to erbation is therefore of great interest The experiments showed that lung develop new therapeutics.” to researchers looking for clinical treat- inflammation was exacerbated in 1. Kobayashi, S., Fujinawa, R., Ota, F., ments for these acute episodes. mice exposed to LPS, with an associ- Kobayashi, S., Angata, T., Ueno, M., Maeno, T., Satoshi Kobayashi and Reiko Fujinawa ated increase in two different types of Kitazume, S., Yoshida, K., Ishii, T., et al. A single from Taniguchi’s research group inflammatory cells and an increase in dose of LPS into mice with emphysema mimics combined a simple mouse model of proinflammatory proteins and signal- human COPD exacerbation as assessed by COPD exacerbation with an imaging ling molecules. Micro-CT imaging at micro-CT. American Journal of Respiratory Cell and technique called micro-computed x-ray 3 and 12 weeks following LPS exposure Molecular Biology advance online publication, tomography (micro-CT), which allowed confirmed the acceleration of emphy- 3 July 2013 (doi:10.1165/rcmb.2013-0074OC). them to monitor pathological changes by sema-like symptoms (Fig. 1).

RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp 15 RESEARCH HIGHLIGHTS

Honing in on developmental epigenetics

A technique for investigating epigenetic modifications in small numbers of cells reveals unusual similarities in gene expression between male germ cells and certain cancer cells

Germ cells have unique molecular features that enable them to perform the important task of transmitting genetic information to the next generation. During development from their embryonic primordial state, germ cells are thought to be reprogrammed by epigenetic modification of their DNA. However, due to the significant technical challenges associated with epigenetic analysis of rare cells such as primordial germ cells, the exact nature and effect of such epigenetic changes remains poorly understood. Kuniya Abe, Rieko Ikeda and colleagues from the RIKEN BioResource Center have now developed a method that enables as few as 100 cells to be analyzed for epigenetic Figure 1: Fluorescent mouse primordial germ cells approximately 12 days after fertilization. changes, providing new insight into 1 © 2013 Kuniya Abe, RIKEN BioResource Center these processes . Epigenetic changes regulate gene expression without altering the underlying DNA sequence. They involve highly stages of development is tagged with that a change in nuclear architecture specific chemical modifications of DNA methyl groups. Looking specifically at that controls the accessibility of the and DNA-bound proteins that activate germ cells (Fig. 1), they found that large genes to the transcriptional apparatus or deactivate individual or related sets of stretches of DNA on the X chromosome of might be involved.” genes. DNA methylation is one such epi- male germ cells were depleted of methyl Abe also notes that if CTA gene expres- genetic mechanism, and the technique groups. These large ‘hypomethylated’ sion does indeed contribute to oncogen- developed by Abe’s team is an adaptation domains frequently included genes with esis, then understanding the epigenetic of an existing microarray-based assay germ cell- or testis-specific expression, regulation of these genes in germ cells method for detecting DNA methylation. including cancer testis antigen (CTA) could provide insight into the molecular “Our modification of the state-of-the- genes, which are expressed in male events that cause certain types of cancer. art approach might be useful for basic germ cells and cancer cells but not in 1. Ikeda, R., Shiura, H., Numata, K., research as well as diagnostic applica- normal somatic cells. Genes in these Sugimoto, M., Kondo, M., Mise, N., Suzuki, M., tions when less than a nanogram of regions were also expressed despite the Greally, J. M. & Abe, K. Large, male germ cell- genomic DNA is available,” says Abe. presence of a histone modification that specific hypomethylated DNA domains with Using their technique on embryonic normally suppresses gene expression. unique genomic and epigenomic features mouse cells, the researchers compared “The mechanistic basis for the rela- on the mouse X chromosome. DNA Research the extent to which the genomic DNA tionship between hypomethylation and advance online publication, 15 July 2013 of somatic cells, stem cells and both the expression of CTA genes remains to (doi:10.1093/dnares/dst030). male and female germ cells at different be established,” says Abe. “We suspect

16 RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp RIKEN PLACES

RIKEN Center for Developmental Biology Realizing the potential of regenerative biology

At the heart of biomedical research and innovation in Kobe, the Center for Developmental Biology is in an excellent position to apply its pioneering research to regenerative medicine

The Center for Developmental Biology (CDB) investigate whether differentiated cell Over the next five years, the CDB will is dedicated to uncovering the fundamental sheets derived from induced pluripotent continue to advance research in its core processes that underlie animal develop- stem (iPS) cells can be safely transplanted areas of developmental and stem cell ment as well as the complex mechanisms into elderly patients suffering from a biology. Exciting projects are underway involved in organ formation and stem cell degenerative eye disease. Led by the CDB’s in the emerging field of self-organizing and regenerative biology, with the ultimate Laboratory for Retinal Regeneration, the embryonic stem cells, and the center goal of applying the latest research to study takes advantage of the center’s is enhancing its use of mathematical regenerative medicine. A core institute for close proximity to hospitals and research methods to better understand the prin- basic research and the inaugural center institutions that specialize in clinical ciples that determine an organism’s size of RIKEN’s Kobe campus, the CDB was trials. The CDB’s strategic location at the and shape. launched in 2000. core of Kobe’s biomedical cluster on Kobe Additionally, the CDB plans to Port Island—home to over 200 biomedical strengthen and expand mutual partner- Eying stem cell research companies—offers many opportunities for ships at home and abroad, such as the Researchers at the CDB have access to collaboration with industry and places the cooperative research agreements it signed supporting laboratories that specialize center in an ideal position to translate its with three Spanish institutes in 2012. in mutant mouse production, genetic research into clinical therapies. Through its summer schools for high school sequencing and microbial analysis, which students and Joint International Graduate Embracing young talent helps them to achieve their research School Program, the center continues to aims. Consequently, several CDB projects. With an annual budget of over 3 billion yen, welcome the next generation of Japanese are at the forefront of stem cell research the CDB supports 30 active research labo- and foreign researchers. By encouraging For example, building on their work with ratories and employs 435 staff members, a constant influx of new talent and ideas, mouse embryonic stem cells, researchers including 213 women and 43 foreign the CDB will ensure its long-term sustain- at the CDB’s Laboratory for Organogenesis researchers. The center also hosts postgrad- ability and, with it, enduring innovation and Neurogenesis have induced human uate students and even offers young scien- in the field of developmental biology. embryonic stem cells to self-organize into tists the opportunity to become principal CONTACT INFORMATION retinal tissue. investigators. The annual CDB Symposium In 2013, the CDB launched a joint draws an international audience, and Website: www.cdb.riken.jp/en/index.html clinical study with the Institute of Bio- seminars throughout the year create regular Email: [email protected] medical Research and Innovation to opportunities for knowledge sharing.

RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp 17 FRONTLINE

KAZUO MAKISHIMA Monitoring the rapidly Team Leader changing Universe MAXI Team RIKEN Global Research Cluster

To the naked eye, stars appear unchanging for many decades or even hundreds of years. Yet in the x-ray spectrum, celestial bodies emerge suddenly and change brightness and shape on the order of days or even seconds. RIKEN developed the Monitor of All-sky X-ray Image (MAXI) experiment to observe these unpredictable x-ray objects. Using MAXI, a team led by Kazuo Makishima has observed many different phenomena, including stars spiraling into a black hole, and discovered traces of hypernova explosions.

MAXI monitors the whole sky Laboratory at RIKEN at that time, predict when and where an x-ray object The origin of MAXI dates back to the proposed equipment for observing the will emerge and how it will change, so 1980s. In 1985, Japan joined the Inter- whole sky in x-rays—an idea that would all-sky observation is an effective tool for national Space Station (ISS) project and eventually become MAXI. detecting x-ray objects.” the National Space Development Agency Makishima explains: “The ISS orbits In 1997, it was officially decided that of Japan (NASDA, currently the Japan the Earth about once every 92 minutes, MAXI would be mounted on the Exposed Aerospace Exploration Agency (JAXA)) with its bottom side facing the Earth. Facility of Kibo. Matsuoka moved to NASDA began to develop the Japanese Experi- As a result, to observe a single celestial in 1999, and in 2001 Makishima was ment Module (JEM), also known as the body, a telescope in the ISS must be appointed as chief scientist of the Cosmic Kibo laboratory. Kibo, which continues moved in the opposite direction so as Radiation Laboratory, taking over the as an active part of the ISS, includes two to cancel out the movement of the ISS. development of the x-ray detector at the experimental areas: an inboard pressur- Thus, many astronomers thought that heart of the MAXI system. In June 2009, ized cabin and an outboard experimental the ISS was unsuitable for astronomical MAXI was launched by a US space shuttle platform exposed to space (the Exposed observation. Dr. Matsuoka, however, and began operation in August 2009. Facility). In 1996, NASDA solicited ideas thought the opposite and conceived of At present, JAXA is in charge of MAXI’s from the public as to the equipment mounting the observation equipment operation and the RIKEN MAXI team is that should be mounted in the Exposed on the side opposite to the Earth so that providing support as well as managing, Facility, and Masaru Matsuoka, chief the whole sky could be observed in a releasing and analyzing observed data scientist of the Cosmic Radiation single orbit around the Earth. We cannot in collaboration with JAXA, Osaka

appears to be the traces of a hypernova

© 2013 JAXA explosion in the constellation Cygnus. The discovery was achieved through View of the the use of one of the two types of x-ray Solid-state Slit Camera detector mounted on MAXI: the Solid- state Slit Camera (SSC) that has lower sensitivity but higher energy resolution

Direction of than the other detector, the Gas Slit View of the movement Camera (GSC), which is used to watch Gas Slit Camera the varying x-ray sky. By analyzing data from the SSC, researchers can perform Figure 1: The Monitor of All-sky X-ray Image (MAXI) experiment detailed diagnostics of x-ray-emitting The monitor is mounted on the extravehicular experimental platform (Exposed Facility) of Japan’s Kibo laboratory, part of the International Space Station (ISS). MAXI observes the whole sky as the ISS orbits astrophysical plasmas because the SSC the Earth. is able to detect atomic emission lines. The energies of these emission lines can University, Tokyo Institute of Technology, Swift detected x-rays in the direction of reveal which elements are involved and Aoyama Gakuin University, Nihon Uni- the constellation Draco. After receiving their respective temperatures. versity, Kyoto University, the University a report of the detection, the MAXI A MAXI all-sky image created from of Miyazaki and Chuo University. For each team reviewed their observation data observations made over the course of orbit of the ISS around the Earth, MAXI and found an increase in x-ray intensity 30 months showed a superbubble—a collects a single complete set of observation several hours before the discovery was massive structure that emits low-energy data for the whole sky (Fig. 1). The new made by the Swift satellite (Fig. 2). “The x-rays—in the direction of the constella- dataset is then compared with previous celestial body was named Swift J1644+57 tion Cygnus (Fig. 4). The MAXI team first datasets. Whenever any celestial body and found to be at a distance of 3.9 billion confirmed that the superbubble was not a is observed to be different in brightness light years from Earth. This discovery is supernova explosion, which occurs when or emerges suddenly, MAXI’s findings considered to be a star spiraling into a star with a mass exceeding eight times are sent out as alerts and followed up by a massive black hole in the center of a that of the Sun collapses at the end of its detailed observations using ground-based galaxy because intense x-ray radiation life. According to Makishima: “The super- telescopes and artificial satellites. has been repeatedly observed since bubble in the constellation Cygnus has a then,” notes Makishima (Fig. 3). linear dimension 40 times larger than our Stars spiraling into a massive Moon, which is too large for a remnant of black hole Discovering the traces of a a single supernova explosion.” hypernova explosion “RIKEN is strongly associated with the The group further determined that the K computer and the life sciences, so MAXI was also key to the discovery in superbubble was not the result of a series many people are surprised to hear that March 2013 of a celestial structure that of supernova explosions. “If that was the RIKEN is also studying the Universe,” says Makishima. “Actually, RIKEN has a long

history in space research. RIKEN’s Yoshio © 2013 RIKEN Nishina (1890–1951) pioneered cosmic-ray research in Japan, and I heard that it was Minoru Oda (1923–2001), director of RIKEN from 1988 to 1993, who advised creating the Exposed Facility on the Kibo laboratory. I would like more people to know that RIKEN performs space research.” MAXI is indeed helping to raise the profile of RIKEN’s space research and has contributed to many dis-

coveries since it commenced operation. Figure 2: Part of an all-sky image captured by MAXI before and after the appearance “MAXI’s most dramatic achievement,” of Swift J1644+57 The supermassive black hole Swift J1644+57 was discovered by the Swift satellite on 28 March says Makishima, “was the observation of 2011. The left image shows part of the all-sky image captured by MAXI and an enlarged view around an x-ray object in 2011.” Swift J1644+57 on 21 March 2011—a week before the discovery; no x-ray sources are observed. The right At 21:57 jst on 28 March 2011, the US image shows the same enlarged view on 29 March 2011; Swift J1644+57 can be seen in the middle of the enlarged view (indicated by an arrow). gamma-ray-burst observation satellite

the strength of the magnetic field that is ten trillion times stronger than the produced them. magnetic field of the Earth. Makishima used MAXI data to study the Makishima is also using his observations magnetic field of many different neutron of the magnetic fields of many different stars and also to search for undiscovered neutron stars to clarify whether a neutron neutron stars. “In September 2009, MAXI star can be regarded as an electromagnet

Illustrated by Shigeyuki Yoshihara. © 2013 RIKEN Yoshihara. Illustrated by Shigeyuki captured an unfamiliar x-ray object. On or a permanent magnet. The most widely examination, the object was found to be held theory is that a neutron star is an GX 304-1, which had been observed for electric magnet and that a flowing electric the first time in 28 years. I knew the name current generates its magnetic field. If this because GX 304-1 was in an x-ray source is true, the intensity of the magnetic field catalog that I used when I was younger. It of neutron stars must be distributed con- felt like meeting an old friend again.” tinuously from high to low. GX 304-1 is a binary system in which a “However, past measurements of Figure 3: Illustration of stars spiraling into a massive black hole neutron star orbits a particular type of star neutron stars reveal that the magnetic field (Fig. 5, left) that spins rapidly, forming intensity is clustered over a narrow range,” a gaseous disc. When the neutron star says Makishima. “Thus, we think that a case, elemental abundance and tempera- passes through the gaseous disc, the gas neutron star could be better explained as ture should vary with location,” continues flows onto the neutron star, emitting a permanent magnet. Such a condition, Makishima. “Our investigation, however, x-rays. However, during the past 28 years, or ‘ferromagnetic state’, could be realized revealed that they are almost the same there could not have been any gas flow if the huge number of neutrons that con- throughout the bubble. We think that fueling GX 304-1. stitute a neutron star were aligned in the the superbubble represents a remnant of a The MAXI data showed that GX 304-1 same direction. We are investigating how massive supernova explosion attributable emits x-rays at an interval of about this could happen.” So far, Makishima to a single, very heavy star with a mass of 132 days (Fig. 5, right). Makishima’s team has measured the magnetic field of about as much as dozens of times the mass of the predicted when strong x-rays would be 20 neutron stars. By increasing the sample Sun.” Such a massive supernova explosion emitted from GX 304-1 and observed the number, he hopes to be able to resolve is known as a ‘hypernova explosion’. x-ray emission using Suzaku, a Japanese the origin of magnetic fields in neutron Although several hypernova explosions x-ray astronomy satellite. Makishima stars, while attracting the interest of have been discovered, the MAXI team’s emphasizes that Japan’s MAXI and nuclear scientists. finding seems to be the first discovery of Suzaku projects complement each other— Extending the MAXI project the traces of a hypernova explosion within MAXI excels in all-sky observation while our Galaxy. Suzaku can observe a single celestial body MAXI was initially planned to be in in detail. After analyzing the Suzaku data service for only two years. However, The magnetic nature of a for GX 304-1, the group determined that thanks to a succession of exceptional neutron star the magnetic field of the neutron star results, MAXI’s operation is set to be MAXI has also made possible the success- ful measurement of the magnetic field of a neutron star, a research theme that Makishima has been working on for a © 2013 RIKEN and JAXA long time together with Takehiro Mihara, a senior research scientist at RIKEN. A neutron star is a superdense stellar Superbubble in Cygnus remnant of the supernova explosion of a heavy star and is strongly magnetic. When charged particles such as electrons and protons gyrate in a magnetic field,

they emit or absorb electromagnetic waves Figure 4: Superbubble in the constellation Cygnus that is considered to be the traces of a of a specific wavelength. In a very strong hypernova explosion An all-sky image obtained from 30 months of observations by the Solid-state Slit Camera (SSC) of MAXI. magnetic field like the one created by a Red indicates that low-energy x-rays are emitted from a region, whereas blue shows that high-energy neutron star, this resonant electromag- x-rays are being emitted. Researchers believe that the superbubble in the constellation Cygnus was netic frequency falls within the x-ray created when a star with a mass of dozens of times that of the Sun underwent a hypernova explosion 2 to 3 million years ago. range, which can be used to calculate

Neutron star (about 1111 NovemberNovember 20092009 6 August 2010 1.4 times the mass 2

ounts/second) ounts/second) 132132 daysdays 132132 daysdays X X (c (c 0

Modiﬁed Julian Date 55100 55150 55200 5525055300 5535055400 55450 Gaseous disc 1414 AugustAugust 20092009 11 OctoberOctober 20102010

Figure 5: X-ray object GX 304-1 and variations in x-ray intensity observed by MAXI The x-ray object GX 304-1 is a binary system consisting of an ordinary star and a neutron star. The star rotates at a high speed, producing a gaseous disc around it. When the neutron star passes through the gaseous disc (red line in the left image), gas flows onto the neutron star, causing it to emit intense x-rays. Observations by MAXI clarified that the x-ray intensity from GX 304-1 varies with a period of about 132 days (right).

extended to March 2015. Makishima has Makishima makes the following pre- phenomena. With a much larger field of big plans for the extra time. “I want to diction: galaxies moving through the view, the new Wide-Field MAXI will make take advantage of the synergy between x-ray emitting gas experience friction, important contributions to phenomena MAXI and Suzaku to do three things,” which may produce the heat necessary to such as gamma-ray bursts. he says. “The first is to measure the prevent the gas from cooling. If Makishi- Makishima’s overall space research magnetic field of more neutron stars ma’s prediction is correct, galaxies would goals are wide in scope. “To be honest, to settle the debate about the origin of slow down and gradually fall to the center in addition to my main research focus their magnetism. The second is to find of their galaxy cluster. To verify this novel on x-ray astronomy, I am interested evidence of black hole mergers.” view, Makishima is examining in closer in astrobiology,” he says. “I believe It is known that there is a massive detail whether the hot gas is actually that there is life somewhere else in the black hole at the center of many galaxies, dragged by moving galaxies. Although Universe besides Earth. Many scientists but the origin of these black holes is Suzaku is not sensitive enough to detect from many different fields of science still unknown. One idea postulates that this, Makishima has high expectations are working at RIKEN. Wouldn’t it be many intermediate black holes with for ASTRO-H, Japan’s next-generation interesting for RIKEN to draw on this masses of between 100 to 1,000 times x-ray astronomy satellite, which is expertise to explore the potential for the mass of the Sun merged into a single scheduled to be launched in 2015. extraterrestrial life?” massive black hole. “We think that the Future directions very bright x-ray sources observed in the ABOUT THE RESEARCHER arm regions of nearby spiral galaxies are Makishima is participating in the develop- Kazuo Makishima was born in strong candidates for intermediate black ment of ASTRO-H as a professor at the Uni- 1949 in Tokyo, Japan. In 1974, he holes,” says Makishima. “Some massive versity of Tokyo’s School of Science, and the obtained his undergraduate degree black holes are now speculated to be High Energy Astrophysics Laboratory led from the University of Tokyo, in the final phase of completing their by Toru Tamagawa at the RIKEN Nishina followed by a master’s degree in mergers. Their x-ray intensity is expected Center for Accelerator-Based Science is also 1978 from the Graduate School of Science at the same university. to show a periodic change as the black involved in the project. “I would like to After working as a research holes circle each other. I want to capture extend the operation of MAXI and use it in assistant at the Institute of Space those changes with MAXI.” collaboration with ASTRO-H,” Makishima and Astronautical Science in Tokyo, Makishima’s third aim relates to heat says. “That way, x-ray astronomy will be he returned to the University sources in galaxy clusters. “A galaxy able to make further progress.” of Tokyo’s Graduate School of cluster, which is a collection of galaxies, In addition, a replacement for MAXI, Science in 1986 as an associate is filled with high-temperature gases the Wide-Field MAXI, is under discussion professor and completed his PhD. that emit strong x-rays. Since x-rays are and is also likely to be mounted on the Kibo He was promoted to full professor in 1995. From 2001 to 2009, he emitted, the gases should gradually cool laboratory’s Exposed Facility. Some x-ray jointly served as a chief scientist down with time. However, they show objects become brighter only for several at the RIKEN Cosmic Radiation no signs of cooling—something we dis- seconds and unfortunately MAXI only has Laboratory. Since 2010, he has been covered with the Advanced Satellite for a narrow viewing field. Therefore, the team leader of the MAXI team and Cosmology and Astronomy (ASCA or area that can be instantaneously captured group director of the Coordinated ASTRO-D), the predecessor of Suzaku. We by MAXI accounts for less than 2% of the Space Observation and Experiment therefore wish to clarify the heat sources whole sky, which makes it difficult to suc- Research Group at RIKEN. in galaxy clusters.” cessfully observe such short-lived celestial

KENJI ITO Promoting sound management at RIKEN Auditor RIKEN Board of Executive Directors

What is your role at RIKEN? What is your impression of RIKEN’s staff? I arrived at RIKEN, the staff in each office As an auditor, I examine RIKEN’s finan- offered detailed explanations of their Researchers at RIKEN feel that they are cial dealings and oversee its activities roles, helping me to gain the informa- able to make significant contributions as a whole. In cooperation with other tion and knowledge necessary for an to society and are extremely proud of departments, such as the Auditing effective audit. what they do. RIKEN develops technolo- and Compliance Office, I audit the gies for the production of important What have you learned about RIKEN appropriateness of RIKEN’s governance products used around the world—some- during your time here so far? and management. thing that must make our administra- Due to the ongoing adverse financial tive staff proud of working at Japan’s How did you join RIKEN, and what kind situation in Japan, RIKEN has faced best research institute. Administrative of support did RIKEN provide? a number of difficulties. Although I staff also take pride in their own work, I have always worked in finance, and have only been working here for four especially since RIKEN’s projects cannot in a previous position at The Industrial months, I have learned that RIKEN has be carried out without their support. Bank of Japan, I was in charge of financ- approached these issues with a sincere Prior to joining RIKEN, you worked in a ing the Riken Electric Wire Co., Ltd, a attitude. Hence, I would like to express credit rating company. How would you RIKEN business concern. During this my respect for President Noyori’s leader- ‘rate’ RIKEN? period, I learned a lot about RIKEN ship and the support offered by all the and discovered the critical contribu- managerial staff. As more than 90 per cent of RIKEN’s tion it has made to Japan’s rapid budget comes from government grants What is the best thing about working economic growth. and subsidies, and RIKEN gains addi- at RIKEN? Though my knowledge is limited tional income from renting out large when it comes to the technical aspects I was very impressed by RIKEN’s out- facilities, it is in fact unnecessary to rate of what RIKEN does, I thought that my standing research, including the dis- RIKEN. But if RIKEN did need to tempo- management experience would be ben- covery of element 113 and the studies rarily borrow a large amount of money eficial for the organization. Good man- of induced pluripotent stem (iPS) cells from a bank, its rating would be excellent. agement is a common challenge in any and plant breeding with heavy-ion CONTACT INFORMATION industry, and it is important and useful beams. Researchers at RIKEN are often For details about working at RIKEN, please to review an organization’s situation behind notable Japanese research contact the RIKEN Global Relations and from an unconventional point of view. findings. I am particularly excited Research Coordination Office: Regarding the actual execution of about these achievements when the Tel: +81 48 462 1225 audits, I receive the full support of the results are important and I know the E-mail: [email protected] Auditing and Compliance Office. When researchers involved.

22 RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp NEWS ROUNDUP

RIKEN forges new ties in India

In September 2013, Ryoji Noyori, president of RIKEN, embarked on a whirlwind tour of India to sign a series of agreements © 2013 RIKEN intended to strengthen RIKEN’s ties with scientific organizations in the country. Through these collaborations, RIKEN hopes to advance science and technology in Japan and India over the long term. President Noyori first visited the Indian government’s Department of Science & Technology and Department of Biotechnol- ogy—both part of the Ministry of Science & Technology—to enter into a Memorandum of Understanding. At the signing ceremony, Noyori delivered a lecture entitled “Science Shapes Our Future,” where he proposed President Noyori (center) with professors M. R. S. Rao (left) and C. N. R. Rao (right) of the Jawaharlal a number of themes of importance to Nehru Centre for Advanced Scientific Research, Bangalore, during a visit designed to strengthen scientific ties between RIKEN and India. humanity as potential areas of cooperation between the two countries—namely, energy, food, health and the environment. Platforms (C-CAMP). The agreement with the Jawaharlal Nehru Centre for Noyori then traveled to Bangalore in included plans to establish a RIKEN–NCBS Advanced Scientific Research and the southern India to sign a comprehensive joint research center, which will initially Indian Institute of Science—two of India’s research agreement with three organiza- focus on cell, developmental and regenera- most prestigious scientific institutions— tions: the National Centre for Biological tive biology and may later expand into other to launch a joint research center between Sciences (NCBS), the Institute for Stem Cell fields, such as brain science. the three organizations that will special- Biology and Regenerative Medicine (inStem) While in Bangalore, President Noyori ize in research into materials science and and the Centre for Cellular and Molecular also signed a supplementary agreement the life sciences.

RIKEN–Shanghai Jiao Tong included students with a keen interest in University joint workshop this area of research. A joint workshop organized by RIKEN and RIKEN and SJTU have been collaborat- © 2013 RIKEN Shanghai Jiao Tong University (SJTU) took ing since 2008, when the two institutions place on 11 September 2013 in Shanghai. first entered into a general agreement for Aimed at students and researchers with cooperation. The partnership has now been interests in computer simulation, laser extended with another workshop—expected science and neutron science, the workshop to be held in October and focusing on energy offered an opportunity for attendees to and the environment. meet, exchange views and sow the seeds of future research collaborations. RIKEN’s Katsumi Midorikawa (front left) and Ruxin Li (front right), director of the SIOM, at During an open discussion at the RIKEN signs Memorandum of the MoU signing ceremony. workshop, Jie Zhang, president of SJTU, Understanding with Shanghai agreed to establish a joint research center Institute of Optics and and a collaboration framework, which will Fine Mechanics RIKEN–SIOM Joint Laboratory. Established include support for young researchers. On 10 September 2013, RIKEN and the in 1964 as part of the Chinese Academy To close the day, Shoji Nagamiya, science Shanghai Institute of Optics and Fine of Sciences (CAS), the SIOM is China’s advisor to RIKEN, delivered a talk on accel- Mechanics (SIOM) signed a Memorandum first and largest institute specializing in erator science in Japan to an audience that of Understanding (MoU) and launched the laser research. Attendees at the signing ceremony—including representatives from the CAS and China’s Ministry of Science and Technology—listened to congratulatory © 2013 RIKEN speeches and toured the new facilities. The joint laboratory will be RIKEN’s first with the CAS since the two institutions signed a research cooperation agreement in 1982. Building on several years of combined study into optics and fine mechanics by Katsumi Midorikawa, chief scientist at the RIKEN Laser Technology Laboratory, and Ruxin Li, director of the SIOM, the laboratory aims to accelerate SJTU President Jie Zhang (center) and RIKEN Science Advisor Shoji Nagamiya (right of President research into laser science and develop Zhang) at the joint RIKEN–SJTU workshop in Shanghai in September. related technologies.

RIKEN RESEARCH | VOL. 8 | NUMBER 11 | NOVEMBER 2013 | www.rikenresearch.riken.jp 23 www.rikenresearch.riken.jp

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