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We previously developed a stress-induced premature senescence (SIPS) model in which normal human fibroblast MRC-5 cells were treated with either the proteasome inhibitor MG132 or the V-ATPase inhibitor bafilomycin A1 (BAFA1). To elucidate the involvement of mitochondrial function in our SIPS model, we treated cells with an inhibitor of electron transport chain (ETC) complexes I, III, or a mitochondrial uncoupler reagent along with MG132 or BAFA1 and evaluated the induction of premature senescence. SIPS induced by MG132 or BAFA1 was partially attenuated by co-treatment with antimycin A (AA) and rotenone, but not carbonyl cyanide 3-chlorophenylhydrazone (CCCP), in which intracellular reactive oxygen species (ROS) levels, acute mitochondrial unfolded protein responses, and accumulation of protein aggregates were remarkably suppressed. Co-treatment with AA also reversed the temporal depletion of SOD2 in the mitochondrial fraction on day 1 of MG132 treatment. Furthermore, co-treatment with AA suppressed the induction of mitophagy in MG132-treated cells and enhanced mitochondrial biogenesis. These findings provide evidence that the temporal inhibition of mitochondrial respiration exerts protective effects against the progression of premature senescence caused by impaired proteostasis.Graphical abstractGRAPHICAL ABSTRACTCellular senescence is induced by prolonged inhibition of proteasome or lysosome function using MG132 and bafilomycin A1 (BAFA1), respectively. When cells were co-treated with a mitochondrial respiration inhibitor, antimycin A, and MG132 or BAFA1, oxidative stress, mitochondrial unfolded protein response (UPRmt), accumulation of protein aggregates, and mitophagy were suppressed whereas mitochondrial biogenesis was enhanced, resulting in the attenuation of stress-induced cellular senescence (SIPS).

In vertebrate embryogenesis, elongation of the posterior body is driven by de novo production of the axial and paraxial mesoderm as well as the neural tube at the posterior end. This process is presumed to depend on the stem cell-like population in the tail bud region, but the details of the gene regulatory network involved are unknown. Previous studies suggested the involvement of pou5f3, an Oct4-type POU gene in zebrafish, in axial elongation. In the present study, we first found that pou5f3 is expressed mainly in the dorsal region of the tail bud immediately after gastrulation, and that this expression is restricted to the posterior-most region of the elongating neural tube during somitogenesis. This pou5f3 expression was complementary to the broad expression of sox3 in the neural tube, and formed a sharp boundary with specific expression of tbxta (orthologue of mammalian T/Brachyury) in the tail bud, implicating pou5f3 in the specification of tail bud-derived cells toward neural differentiation in the spinal cord. When pou5f3 was functionally impaired after gastrulation by induction of a dominant-interfering pou5f3 mutant gene (en-pou5f3), trunk and tail elongation were markedly disturbed at distinct positions along the axis depending on the stage. This finding showed involvement of pou5f3 in de novo generation of the body from the tail bud. Conditional functional abrogation also showed that pou5f3 downregulates mesoderm-forming genes but promotes neural development by activating neurogenesis genes around the tail bud. These results suggest that pou5f3 is involved in formation of the posterior spinal cord.

Proteolytic activity declines with age, resulting in the accumulation of aggregated proteins in aged organisms. To investigate how disturbance in proteostasis causes cellular senescence, we developed a stress-induced premature senescence (SIPS) model, in which normal human fibroblast MRC-5 cells were treated with the proteasome inhibitor MG132 or the vacuolar-type ATPase inhibitor bafilomycin A1 (BAFA1) for 5 days. Time-course studies revealed a significant increase in intracellular reactive oxygen species (ROS) and mitochondrial superoxide during and after drug treatment. Mitochondrial membrane potential initially decreased, suggesting temporal mitochondrial dysfunction during drug treatment, but was restored along with mitochondrial accumulation after drug treatment. AMP-activated protein kinase alpha was notably activated during treatment; thereafter, intracellular ATP levels significantly increased. SIPS induction by MG132 or BAFA1 was partially attenuated by co-treatment with vitamin E or rapamycin, in which the levels of ROS, mitochondrial accumulation, and protein aggregates were suppressed, implying the critical involvement of oxidative stress and mitochondrial function in SIPS progression. Rapamycin co-treatment also augmented the expression of HSP70 and activation of AKT, which could recover proteostasis and promote cell survival, respectively. Our study proposes a possible pathway from the disturbed proteostasis to cellular senescence via excess ROS production as well as functional and quantitative changes in mitochondria.

It is well known that hepatocytes regenerate after liver injury, although it is difficult to reproduce this phenomenon in vitro. The goal of this research was to determine the factors that stimulate proliferation of primary mouse hepatocytes (PMHs) in vitro. We first tested knockdown (KD) of tumor protein 53 (p53) alone as well as partial hepatectomy (PH, performed 72 h prior to PMHs preparation) alone. However, neither intervention stimulated hepatocyte proliferation during the 72-h observation period in vitro. We then tested the combination of p53 KD with PH and found that these interventions together stimulated cell proliferation in vitro. Under these latter conditions we analyzed gene expression of these cells by mRNA sequencing (RNA-seq) and microRNA sequencing (miRNA-seq). TargetScan analysis, which determines the relationship between microRNAs and gene expression, found a relationship between downregulated mmu-mir-222 (miR-222) and upregulated genes such as mitogen-activated protein kinase kinase kinase 2 (Map3k2). To confirm this relationship, we performed miR-222 KD and overexpression (OE) and observed the expected changes in target gene expression. Furthermore, the finding that miR-222 KD or OE stimulates or suppresses, respectively, hepatocyte proliferation is well explained by the association between miR-222 and its target genes, which stimulate growth. Our results suggest that miR-222 is one of the key factors regulating PMH proliferation in vitro.

The five β-like globin genes (ε, Gγ, Aγ, δ and β) at the human β-globin gene locus are known to be expressed at specific developmental stages, although details of the underlying mechanism remain to be uncovered. Here we used an in vitro transcription assay to clarify the mechanisms that control this gene expression. We first tested nuclear RNA from HeLa cells using RT-qPCR and discovered a long noncoding RNAs (lncRNAs) within a 5.2-kb region beginning 4.4 kb downstream of the β-globin gene coding region. We investigated nuclear RNA from K562 cells using a primer-extension assay and determined the transcription start sites (TSSs) of these lncRNAs. To clarify their functional role, we performed knockdown (KD) of these lncRNAs in K562 cells. Hydroxyurea (HU), which induces differentiation of K562 cells, increased haemoglobin peptide production, and the effect was enhanced by KD of these lncRNAs, which also enhanced upregulation of the γ-globin expression induced by HU. To confirm these results, we performed an in vitro transcription assay. Noncoding single-stranded RNAs inhibited β-globin expression, which was upregulated by GATA1. Furthermore, lncRNAs interacted with GATA1 without sequence specificity and inhibited its binding to its target DNA response element in vitro. Our results suggest that lncRNAs downstream of the β-globin gene locus are key factors regulating globin gene expression.

The mechanisms that generate robust ionic oscillation in circadian pacemaker neurons are under investigation. Here, we demonstrate critical functions of the mitochondrial cation antiporter leucine zipper- EF-hand-containing transmembrane protein 1 (LETM1), which exchanges K+/H+ in Drosophila and Ca2+/H+ in mammals, in circadian pacemaker neurons. Letm1 knockdown in Drosophila pacemaker neurons reduced circadian cytosolic H+ rhythms and prolonged nuclear PERIOD/TIMELESS expression rhythms and locomotor activity rhythms. In rat pacemaker neurons in the hypothalamic suprachiasmatic nucleus (SCN), circadian rhythms in cytosolic Ca2+ and Bmal1 transcription were dampened by Letm1 knockdown. Mitochondrial Ca2+ uptake peaks late during the day were also observed in rat SCN neurons following photolytic elevation of cytosolic Ca2+. Since cation transport by LETM1 is coupled to mitochondrial energy synthesis, we propose that LETM1 integrates metabolic, ionic, and molecular clock rhythms in the central clock system in both invertebrates and vertebrates.

The mechanisms that generate robust ionic oscillation in circadian pacemaker neurons are under investigation. Here, we demonstrate critical functions of mitochondrial cation antiporter (LETM1), which exchanges K+/H+ in Drosophila and Ca2+/H+ in mammals, in circadian pacemaker neurons. Letm1 knockdown in Drosophila pacemaker neurons reduced circadian cytosolic H+ rhythms and prolonged nuclear PER/TIM expression rhythms and locomotor activity rhythms. In rat pacemaker neurons in the hypothalamic suprachiasmatic nucleus (SCN), circadian rhythms in cytosolic Ca2+ and Bmal1 transcription were dampened by Letm1 knockdown. Mitochondrial Ca2+ uptake peaks late during the day were also observed in rat SCN neurons following photolytic elevation of cytosolic Ca2+. Since cation transport by LETM1 is coupled to mitochondrial energy synthesis, we propose that LETM1 integrates metabolic, ionic and molecular clock rhythms in the central clock system in both invertebrates and vertebrates.

Proteolytic activities decline with age, resulting in the accumulation of aggregated proteins in aged organisms. To investigate how disturbance of proteostasis causes cellular senescence in proliferating cells, we developed a stress-induced premature senescence (SIPS) model, in which normal human fibroblast MRC-5 cells were treated with either the proteasome inhibitor MG132 or V-ATPase inhibitor bafilomycin A1 (BAFA1). After 5 days of drug treatment, cells showed morphological and functional changes associated with aging along with DNA damage response. Time-course studies revealed significant increase in intracellular and mitochondrial reactive oxygen species (ROS) during and after drug treatment. We also found temporal downregulation of mitochondrial membrane potential during drug treatment, followed by an increase in mitochondrial mass, especially after drug treatment. Notable upregulation of PGC-1α and TFAM proteins confirmed enhanced mitochondrial biogenesis. Furthermore, the protein levels of SOD2 and GPx4, mitochondrial antioxidant enzymes, in the mitochondrial fraction were specifically reduced on day 1 of the treatment. Co-treatment with rapamycin along with MG132 or BAFA1 partially attenuated induction of SIPS by suppressing generation of excess ROS and mitochondrial biogenesis. In conclusion, the present study revealed that disturbance of proteostasis by the inhibitors changes the distribution of nuclear-encoded mitochondrial antioxidant enzymes at an early period of the treatment, which induces mitochondrial ROS and temporal mitochondrial dysfunction. ROS in turn activates stress responses pathways, followed by PGC-1α-mediated mitochondrial biogenesis. Hence, the excessive ROS continuously generated by increased mitochondria can cause deleterious damage to nuclear DNA, cell cycle arrest, and eventual cellular senescence.

BACKGROUND The antidiabetic drug teneligliptin is a novel dipeptidyl peptidase-4 (DPP-4) inhibitor with a thiazolidine-specific structure. This study aimed to investigate whether teneligliptin can activate PPARγ directly and/or indirectly in cell-based assays. METHODS Promoter assays using the reporter construct driven under the control of the SV40 promoter and the PPAR response element (PPRE) were performed. Luciferase activity was measured after a 3-day incubation of vector-transduced cells with various concentrations of teneligliptin. RESULTS Treatment of the cells with 50 μM teneligliptin significantly transactivated a reporter gene. The presence of the PPARγ antagonist, GW9662, did not affect the activation of PPRE-reporter expression by teneligliptin. CONCLUSION We found that teneligliptin could increase PPARγ activity in cell-based assays irrespective of the PPARγ ligand-binding domain.

Zebrafish pou5f3 (previously named pou2), a close homologue of mouse Oct4, encodes a PouV-family transcription factor. pou5f3 has been implicated in diverse aspects of developmental regulation during embryogenesis. In the present study, we addressed the molecular function of Pou5f3 as a transcriptional regulator and the mechanism by which pou5f3 expression is transcriptionally regulated. We examined the influence of effector genes on the expression of the luciferase gene under the control of the upstream 2.1-kb regulatory DNA of pou5f3 (Luc-2.2) in HEK293T and P19 cells. We first confirmed that Pou5f3 functions as a transcriptional activator both in cultured cells and embryos, which confirmed autoregulation of pou5f3 in embryos. It was further shown that Luc-2.2 was activated synergistically by pou5f3 and sox3, which is similar to the co-operative activity of Oct4 and Sox2 in mice, although synergy between pou5f3 and sox2 was less obvious in this zebrafish system. The effects of pou5f3 deletion constructs on the regulation of Luc-2.2 expression revealed different roles for the three subregions of the N-terminal region in Pou5f3 in terms of its regulatory functions and co-operativity with Sox3. Electrophoretic mobility shift assays confirmed that Pou5f3 and Sox3 proteins specifically bind to adjacent sites in the 2.1-kb DNA and that there is an interaction between the two proteins. The synergy with sox3 was unique to pou5f3-the other POU factor genes examined did not show such synergy in Luc-2.2 regulation. Finally, functional interaction was observed between pou5f3 and sox3 in embryos in terms of the regulation of dorsoventral patterning and convergent extension movement. These findings together demonstrate co-operative functions of pou5f3 and sox3, which are frequently coexpressed in early embryos, in the regulation of early development.

Oct4 is a master regulator of the induction and maintenance of cellular pluripotency, and has crucial roles in early stages of differentiation. It is the only factor that cannot be substituted by other members of the same protein family to induce pluripotency. However, although Oct4 nuclear transport and delivery to target DNA are critical events for reprogramming to pluripotency, little is known about the molecular mechanism. Oct4 is imported to the nucleus by the classical nuclear transport mechanism, which requires importin α as an adaptor to bind the nuclear localization signal (NLS). Although there are structures of complexes of the NLS of transcription factors (TFs) in complex with importin α, there are no structures available for complexes involving intact TFs. We have therefore modeled the structure of the complex of the whole Oct4 POU domain and importin α2 using protein-protein docking and molecular dynamics. The model explains how the Ebola virus VP24 protein has a negative effect on the nuclear import of STAT1 by importin α but not on Oct4, and how Nup 50 facilitates cargo release from importin α. The model demonstrates the structural differences between the Oct4 importin α bound and DNA bound crystal states. We propose that the 'expanded linker' between the two DNA-binding domains of Oct4 is an intrinsically disordered region and that its conformational changes have a key role in the recognition/binding to both DNA and importin α. Moreover, we propose that this structural change enables efficient delivery to DNA after release from importin α.

This paper experimentally investigates the influence on the propulsive performance by the difference in the fin shape of a robotic manta. Five kinds of fin shapes, i.e., a rectangle, a triangle, a trapezoid, and two right triangles, are used in experiment to measure the forward speed of the robot, where two types of right triangle are discriminated, depending on the arrangement of the right angle part and each fin area is assumed to be approximately equal, and the number of fin rays is the same at all the fins. It is proved that a significant difference in propulsive speed arises depending on the difference in the fin shape. Some experiments are additionally conducted to examine the influence on the propulsive speed and its efficiency, due to the parameter change of a progressive wave in the fin.

We have previously reported the abundant and ubiquitous expression of a newly identified splicing variant of mouse peroxisome proliferator-activated receptor-γ (Pparγ), namely Pparγ1sv that encodes PPARγ1 protein, and plays an important role in adipogenesis. Pparγ1sv has a unique 5’UTR sequence, compared to those of mouse Pparγ1 and Pparγ2 mRNAs. This implies the presence of a novel transcriptional initiation site and promoter for Pparγ1sv. We found that DNA methylation of 42 CpG sites in the proximal promoter region (−733 to −76) of Pparγ1sv was largely unchanged five days after adipocyte differentiation, whereas chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) using antibodies against H3K4me3 and H3K27ac revealed that these modifications significantly elevated at the transcription start sites of Pparγ1sv and Pparγ2 after differentiation.

In early vertebrate embryos, the dorsal ectoderm is induced by the axial mesendoderm to form the neural plate, which is given competence to form neural cells by soxB1 genes. Subsequently, neurogenesis proceeds in proneural clusters that are generated by a gene network involving proneural genes and Notch signaling. However, what occurs between early neural induction and the later initiation of neurogenesis has not been fully revealed. In the present study, we demonstrated that during gastrulation, the expression of the Oct4-related PouV gene pou5f3 (also called pou2), which is widely observed at earlier stages, was rapidly localized to an array of isolated spotted domains, each of which coincided with individual proneural clusters. Two-color in situ hybridization confirmed that each pou5f3-expressing domain included a proneural cluster. Further analysis demonstrated that anterior pou5f3 domains straddled the boundaries between rhombomere 1 (r1) and r2, whereas posterior domains were included in r4. The effects of forced expression of an inducible negative dominant-interfering pou5f3 gene suggested that pou5f3 activated early proneural genes, such as neurog1 and ebf2, and also soxB1, but repressed the late proneural genes atoh1a and ascl1b. Furthermore, pou5f3 was considered to repress her4.1, a Notch-dependent Hairy/E(spl) gene involved in lateral inhibition in proneural clusters. These results suggest that pou5f3 promotes early neurogenesis in proneural clusters, but negatively regulates later neurogenesis. Suppression of pou5f3 also altered the expression of other her genes, including her3, her5, and her9, further supporting a role for pou5f3 in neurogenesis. In vitro reporter assays in P19 cells showed that pou5f3 was repressed by neurog1, but activated by Notch signaling. These findings together demonstrate the importance of the pou5f3-mediated gene regulatory network in neural development in vertebrate embryos.

Bone remodeling is an important factor in orthodontic tooth movement. During orthodontic treatment, osteoclasts are subjected to various mechanical stimuli, and this promotes or inhibits osteoclast differentiation and fusion. It has been previously reported that the release from tensile force induces osteoclast differentiation. However, little is known about how release from compressive force affects osteoclasts. The present study investigated the effects of release from compressive force on osteoclasts. The number of tartrate-resistant acid phosphatase (TRAP) -positive multinucleated osteoclasts derived from RAW264.7 cells was counted, and gene expression associated with osteoclast differentiation and fusion in response to release from compressive force was evaluated by reverse transcription-quantitative polymerase chain reaction. Osteoclast number was increased by optimal compressive force application. On release from this force, osteoclast differentiation and fusion were suppressed. mRNA expression of NFATc1 was inhibited for 6 h subsequent to release from compressive force. mRNA expression of the other osteoclast-specific genes, TRAP, RANK, matrix metalloproteinase-9, cathepsin-K, chloride channel 7, ATPase H+ transporting vacuolar proton pump member I, dendritic cell-specific transmembrane protein and osteoclast stimulatory transmembrane protein (OC-STAMP) was significantly inhibited at 3 h following release from compressive force compared with control cells. These findings suggest that release from optimal compressive force suppresses osteoclast differentiation and fusion, which may be important for developing orthodontic treatments.

Several cables in safety-related systems in nuclear power plants are required to maintain their intended electrical insulating function while they are exposed to harsh environmental conditions in the primary containment vessel during assumed accidents. This must be satisfied even after the cables are operated for their full service period. For such cables, the behavior of their insulation under accidents is a matter of concern. In this research, after silicone rubber insulated cables were pre-aged by simultaneous thermal and radiation exposure, they were irradiated or exposed to high temperature steam to simulate the environmental conditions during the accident, or subjected to the combination of these conditions. The resultant changes in various properties were analyzed by instrumental analyses. As a result, it has been confirmed that the pre-aging and radiation exposure induce cross-linking and depolymerization of siloxane chains to produce cyclic siloxanes, whereas the steam exposure causes significant depolymerization and the generation of low-molecular cyclic siloxanes.

To examine electrical insulation behavior of cables under severe accident environmental conditions, safety-related low voltage cables used as severe accident management equipment were subjected to two tests that simulated two environments: 1) at 155°C, which is the simulated highest assumed temperature when proper accident management measures are taken, 2) at 200°C, which is the maximum durable temperature of a primary containment vessel. In addition, electrical insulation resistance was measured for the cables during steam exposure in the two tests. As a result, all the cables passed the acceptance criteria of the tests. The minimum volume resistivity of the cables during the test at 155°C was around 108Om, confirming that the cables have a sufficient insulation performance. On the other hand, the minimum volume resistivity during the severer test at 200°C was around 105Om due to the increase in leak current.

Vertebrate eyes are known to contain circadian clocks, however, the intracellular mechanisms regulating the retinal clockwork remain largely unknown. To address this, we generated a cell line (hRPE-YC) from human retinal pigmental epithelium, which stably co-expressed reporters for molecular clock oscillations (Bmal1-luciferase) and intracellular Ca2+ concentrations (YC3.6). The hRPE-YC cells demonstrated circadian rhythms in Bmal1 transcription. Also, these cells represented circadian rhythms in Ca2+-spiking frequencies, which were canceled by dominant-negative Bmal1 transfections. The muscarinic agonist carbachol, but not photic stimulation, phase-shifted Bmal1 transcriptional rhythms with a type-1 phase response curve. This is consistent with significant M3 muscarinic receptor expression and little photo-sensor (Cry2 and Opn4) expression in these cells. Moreover, forskolin phase-shifted Bmal1 transcriptional rhythm with a type-0 phase response curve, in accordance with long-lasting CREB phosphorylation levels after forskolin exposure. Interestingly, the hRPE-YC cells demonstrated apparent circadian rhythms in phagocytic activities, which were abolished by carbachol or dominant-negative Bmal1 transfection. Because phagocytosis in RPE cells determines photoreceptor disc shedding, molecular clock oscillations and cytosolic Ca2+ signaling may be the driving forces for disc-shedding rhythms known in various vertebrates. In conclusion, the present study provides a cellular model to understand molecular and intracellular signaling mechanisms underlying human retinal circadian clocks.

The hypothalamic suprachiasmatic nucleus (SCN) plays a pivotal role in the mammalian circadian clock system.Bmal1is a clock gene that drives transcriptional-translational feedback loops (TTFLs) for itself and other genes, and is expressed in nearly all SCN neurons. Despite strong evidence thatBmal1-null mutant mice display arrhythmic behavior under constant darkness, the function ofBmal1in neuronal activity is unknown. Recently, periodic changes in the levels of intracellular signaling messengers, such as cytosolic Ca2+and cAMP, were suggested to regulate TTFLs. However, the opposite aspect of how clock gene TTFLs regulate cytosolic signaling remains unclear. To investigate intracellular Ca2+dynamics underBmal1perturbations, we cotransfected some SCN neurons withyellow cameleontogether with wild-type or dominant-negativeBmal1using a gene-gun applied for mouse organotypic cultures. Immunofluorescence staining for a tag protein linked to BMAL1 showed nuclear expression of wild-type BMAL1 and its degradation within 1 week after transfection in SCN neurons. However, dominant-negative BMAL1 did not translocate into the nucleus and the cytosolic signals persisted beyond 1 week. Consistently, circadian Ca2+rhythms in SCN neurons were inhibited for longer periods by dominant-negativeBmal1overexpression. Furthermore, SCN neurons transfected with aBmal1shRNA lengthened, whereas those overexpressing wild-typeBmal1shortened, the periods of Ca2+rhythms, with a significant reduction in their amplitude. BMAL1 expression was intact in the majority of neighboring neurons in organotypic cultures. Therefore, we conclude that proper intrinsicBmal1expression, but not passive signaling via cell-to-cell interactions, is the determinant of circadian Ca2+rhythms in SCN neurons.

Here, we describe the isolation of two nickel-induced genes in Paramecium caudatum , NCI16 and Pc GST1 , by subtractive hybridization. NCI16 encoded a predicted four-transmembrane domain protein (∼16 kDa) of unknown function, and Pc GST1 encoded glutathione S -transferase (GST; ∼25 kDa) with GST and glutathione peroxidase (GPx) activities. Exposing cells to cobalt chloride also caused the moderate upregulation of NCI16 and Pc GST1 mRNAs. Both nickel sulfate and cobalt chloride dose dependently induced NCI16 and Pc GST1 mRNAs, but with different profiles. Nickel treatment caused a continuous increase in Pc GST1 and NCI16 mRNA levels for up to 3 and 6 days, respectively, and a notable increase in H 2 O 2 concentrations in P. caudatum . NCI16 expression was significantly enhanced by incubating cells with H 2 O 2 , implying that NCI16 induction in the presence of nickel ions is caused by reactive oxygen species (ROS). On the other hand, Pc GST1 was highly induced by the antioxidant tert -butylhydroquinone (tBHQ) but not by H 2 O 2 , suggesting that different mechanisms mediate the induction of NCI16 and Pc GST1 . We introduced a luciferase reporter vector with an ∼0.42-kb putative Pc GST1 promoter into cells and then exposed the transformants to nickel sulfate. This resulted in significant luciferase upregulation, indicating that the putative Pc GST1 promoter contains a nickel-responsive element. Our nickel-inducible system also may be applicable to the efficient expression of proteins that are toxic to host cells or require temporal control.

Although, Autonomous Underwater Vehicles (AUVs) used for investigating underwater ecology have attracted the attention of underwater researchers, conventional AUVs moved underwater by screw propellers generate loud noise thatmay disturb the underwater environments and inhabitants to be observed. This paper discusses the development of an AUV that mimics the manta ray. Central Pattern Generators (CPGs) are also proposed to generate the motion of pectoral fins for Manta robot. The practicality of the robot is checked in underwater propulsion experiments, and the effectiveness of the proposed motion generation method is demonstrated in numerical simulations.

In this paper, we analyze a propulsive force generated from pectoral fins for a rajiform-type fish robot from fluid dynamic aspects. A pectoral fin of the rajiform-type fish robot is constructed by multiple fin rays, which move independently, and a film of pushing water. Then, the propulsive force of the fish robot is analyzed from the momentum of the fluid surrounding for every fin between fin rays. The total propulsive force for one pectoral fin is the sum of these momenta. The propulsive speed of a fish robot is determined from the difference of the propulsive force generated from pectoral fins, and the resistance force that the fish robot receives from the water when moving forward. The effectiveness of the proposed method is examined through numerical simulation and actual experimental results.

Low-voltage-driven organic thin-film transistors (organic TFTs) with spatially controlled threshold voltages (-1.2 and -0.36 V) were fabricated for the first time. Using the microcontact printing method, tetradecylphosphonic acid (HC14-PA)and pentadecylfluoro-octadecylpho-sphonic acid (FC18-PA) were transferred to form ultrathin layers in different regions on a substrate. Together with plasma-grown aluminum oxide (AIOx) layer, the stamped layers were shown to have equal insulating ability as the dipped method monolayer. The feasibility of the area-selective stamping method was displayed using locally controlled inverter circuits. The shift of turn-on voltage for those transistors was consistent with the threshold voltage shift of the transistors.

Organic thin-film transistors based on the vacuum-deposited small-molecule conjugated semiconductor dinaphtho(2,3-b:2 0,30-f)thieno(3,2-b)thiophene (DNTT) have been fabri- cated and characterized. The transistors have field-effect mobilities as large as 2 cm 2 /V s and an on/off ratio of 10 8 . Owing to the large ionization potential of DNTT, the TFTs show excellent stability for periods of several months of storage in ambient air. Unipolar ring oscillators based on DNTT TFTs with a channel length of 10 lm oscillate with a signal prop- agation delay as short as 7 lsec per stage at a supply voltage of 5 V. We also show that DNTT TFTs with usefully small channel width/length ratio are able to drive blue organic LEDs to a brightness well above that required for active-matrix displays.

We have successfully achieved a transconductance of 0.76 S/m for organic thin-film transistors with 4 V operation, which is the largest value reported for organic transistors fabricated using printing methods. Using a subfemtoliter inkjet, silver electrodes with a line width of 1 µm and a channel length of 1 µm were printed directly onto an air-stable, high-mobility organic semiconductor that was deposited on a singlemolecule self-assembled monolayer-based gatedielectric. Onreducingthe droplet volume(0.5 fl) ejectedfromthe inkjet nozzle,which reduces sintering temperatures down to 90 °C, the inkjet printing of silver electrodes was accomplished without damage to the organic semiconductor.