Showing papers by "Utsunomiya University published in 2013"

Dynamic behaviour of the East Antarctic ice sheet during Pliocene warmth

Abstract: Warm intervals within the Pliocene epoch (5.33–2.58 million years ago) were characterized by global temperatures comparable to those predicted for the end of this century1 and atmospheric CO2 concentrations similar to today2, 3, 4. Estimates for global sea level highstands during these times5 imply possible retreat of the East Antarctic ice sheet, but ice-proximal evidence from the Antarctic margin is scarce. Here we present new data from Pliocene marine sediments recovered offshore of Adelie Land, East Antarctica, that reveal dynamic behaviour of the East Antarctic ice sheet in the vicinity of the low-lying Wilkes Subglacial Basin during times of past climatic warmth. Sedimentary sequences deposited between 5.3 and 3.3 million years ago indicate increases in Southern Ocean surface water productivity, associated with elevated circum-Antarctic temperatures. The geochemical provenance of detrital material deposited during these warm intervals suggests active erosion of continental bedrock from within the Wilkes Subglacial Basin, an area today buried beneath the East Antarctic ice sheet. We interpret this erosion to be associated with retreat of the ice sheet margin several hundreds of kilometres inland and conclude that the East Antarctic ice sheet was sensitive to climatic warmth during the Pliocene.

The saccus vasculosus of fish is a sensor of seasonal changes in day length

Abstract: The pars tuberalis of the pituitary gland is the regulatory hub for seasonal reproduction in birds and mammals. Although fish also exhibit robust seasonal responses, they do not possess an anatomically distinct pars tuberalis. Here we report that the saccus vasculosus of fish is a seasonal sensor. We observe expression of key genes regulating seasonal reproduction and rhodopsin family genes in the saccus vasculosus of masu salmon. Immunohistochemical studies demonstrate that all of these genes are expressed in the coronet cells of the saccus vasculosus, suggesting the existence of a photoperiodic signalling pathway from light input to neuroendocrine output. In addition, isolated saccus vasculosus has the capacity to respond to photoperiodic signals, and its removal abolishes photoperiodic response of the gonad. Although the physiological role of the saccus vasculosus has been a mystery for several centuries, our findings indicate that the saccus vasculosus acts as a sensor of seasonal changes in day length in fish.

CYP714B1 and CYP714B2 encode gibberellin 13-oxidases that reduce gibberellin activity in rice

Abstract: Bioactive gibberellins (GAs) control many aspects of growth and development in plants. GA1 has been the most frequently found bioactive GA in various tissues of flowering plants, but the enzymes responsible for GA1 biosynthesis have not been fully elucidated due to the enzymes catalyzing the 13-hydroxylation step not being identified. Because of the lack of mutants defective in this enzyme, biological significance of GA 13-hydroxylation has been unknown. Here, we report that two cytochrome P450 genes, CYP714B1 and CYP714B2, encode GA 13-oxidase in rice. Transgenic Arabidopsis plants that overexpress CYP714B1 or CYP714B2 show semidwarfism. There was a trend that the levels of 13-OH GAs including GA1 were increased in these transgenic plants. Functional analysis using yeast or insect cells shows that recombinant CYP714B1 and CYP714B2 proteins can convert GA12 into GA53 (13-OH GA12) in vitro. Moreover, the levels of 13-OH GAs including GA1 were decreased, whereas those of 13-H GAs including GA4 (which is more active than GA1) were increased, in the rice cyp714b1 cyp714b2 double mutant. These results indicate that CYP714B1 and CYP714B2 play a predominant role in GA 13-hydroxylation in rice. The double mutant plants appear phenotypically normal until heading, but show elongated uppermost internode at the heading stage. Moreover, CYP714B1 and CYP714B2 expression was up-regulated by exogenous application of bioactive GAs. Our results suggest that GA 13-oxidases play a role in fine-tuning plant growth by decreasing GA bioactivity in rice and that they also participate in GA homeostasis.

Differences in the activity pattern of the wild boar Sus scrofa related to human disturbance

Abstract: Over the last century, human activity has caused significant changes to the activity patterns of many wildlife species. The wild boar is one species known to change its activity pattern with the intensity of human disturbance. We conducted camera trap surveys in two study sites, Shingo and Himuro, in Tochigi, central Japan. We investigated effects of two types of human disturbance on the activity pattern of a wild boar population: ‘direct’ disturbance related to hunting activity and ‘indirect’ disturbance related to daily human activity. In the hunting season, relative abundance indices (RAI) of wild boars significantly decreased, and the proportion of activity at night increased compared with the nonhunting season. RAI of wild boars at night decreased with increasing distance from the settlement, while RAI of wild boars during the day did not. Relative proportion of activity at night was higher in cameras at 0–200 m from the settlements, while no significant pattern was found in cameras far from settlements. Both direct and indirect effects of human activity had a significant effect on the activity pattern of wild boars. A decrease in human activity may result in the rapid expansion of wild boar populations, and re-evaluation of the human factor is important for more intelligent management of wild boar populations and to solve the human–wildlife conflict.

Fourier fringe analysis and its application to metrology of extreme physical phenomena: a review [Invited]

Abstract: The paper reviews a technique for fringe analysis referred to as Fourier fringe analysis (FFA) or the Fourier transform method, with a particular focus on its application to metrology of extreme physical phenomena. Examples include the measurement of extremely small magnetic fields with subfluxon sensitivity by electron wave interferometry, subnanometer wavefront evaluation of projection optics for extreme UV lithography, the detection of sub-Angstrom distortion of a crystal lattice, and the measurement of ultrashort optical pulses in the femotsecond to attosecond range, which show how the advantages of FFA are exploited in these cutting edge applications.

Relative sea-level rise around East Antarctica during Oligocene glaciation

Abstract: During the middle and late Eocene (∼ 48-34 Myr ago), the Earth's climate cooled and an ice sheet built up on Antarctica. The stepwise expansion of ice on Antarctica induced crustal deformation and gravitational perturbations around the continent. Close to the ice sheet, sea level rose despite an overall reduction in the mass of the ocean caused by the transfer of water to the ice sheet. Here we identify the crustal response to ice-sheet growth by forcing a glacial-hydro isostatic adjustment model with an Antarctic ice-sheet model. We find that the shelf areas around East Antarctica first shoaled as upper mantle material upwelled and a peripheral forebulge developed. The inner shelf subsequently subsided as lithosphere flexure extended outwards from the ice-sheet margins. Consequently the coasts experienced a progressive relative sea-level rise. Our analysis of sediment cores from the vicinity of the Antarctic ice sheet are in agreement with the spatial patterns of relative sea-level change indicated by our simulations. Our results are consistent with the suggestion that near-field processes such as local sea-level change influence the equilibrium state obtained by an ice-sheet grounding line.

Nitrogen and phosphorus fertilization negatively affects strigolactone production and exudation in sorghum

Abstract: Strigolactones (SLs) are essential host recognition signals for both root parasitic plants and arbuscular mycorrhizal fungi, and SLs or their metabolites function as a novel class of plant hormones regulating shoot and root architecture. Our previous study indicated that nitrogen (N) deficiency as well as phosphorus (P) deficiency in sorghum enhanced root content and exudation of 5-deoxystrigol, one of the major SLs produced by sorghum. In the present study, we examined how N and P fertilization affects SL production and exudation in sorghum plants subjected to short- (5 days) or long-term (10 days) N or P deficiency and demonstrated their common and distinct features. The root contents and exudation of SLs in the N- or P-deficient sorghum plants grown for 6, 12 or 24 h with or without N or P fertilization were quantified by LC–MS/MS. In general, without fertilization, root contents and exudation of SLs stayed at similar levels at 6 and 12 h and then significantly increased at 24 h. The production of SLs responded more quickly to P fertilization than the secretion of SLs, while regulation of SL secretion began earlier after N fertilization. It is suggested that sorghum plants regulate SL production and exudation when they are subjected to nutrient deficiencies depending on the type of nutrient and degree of deficiency.

New results on νμ → ντ appearance with the OPERA experiment in the CNGS beam

Abstract: The OPERA neutrino experiment is designed to perform the first observation of neutrino oscillations in direct appearance mode in the ν μ → ν τ channel, via the detection of the τ-leptons created in charged current ν τ interactions. The detector, located in the underground Gran Sasso Laboratory, consists of an emulsion/lead target with an average mass of about 1.2 kt, complemented by electronic detectors. It is exposed to the CERN Neutrinos to Gran Sasso beam, with a baseline of 730 km and a mean energy of 17 GeV. The observation of the first ν τ candidate event and the analysis of the 2008-2009 neutrino sample have been reported in previous publications. This work describes substantial improvements in the analysis and in the evaluation of the detection efficiencies and backgrounds using new simulation tools. The analysis is extended to a sub-sample of 2010 and 2011 data, resulting from an electronic detector-based pre-selection, in which an additional ν τ candidate has been observed. The significance of the two events in terms of a ν μ → ν τ oscillation signal is of 2.40σ.

Measurement of the neutrino velocity with the OPERA detector in the CNGS beam using the 2012 dedicated data

Abstract: In spring 2012 CERN provided two weeks of a short bunch proton beam dedicated to the neutrino velocity measurement over a distance of 730 km. The OPERA neutrino experiment at the underground Gran Sasso Laboratory used an upgraded setup compared to the 2011 measurements, improving the measurement time accuracy. An independent timing system based on the Resistive Plate Chambers was exploited providing a time accuracy of $\sim$1 ns. Neutrino and anti-neutrino contributions were separated using the information provided by the OPERA magnetic spectrometers. The new analysis profited from the precision geodesy measurements of the neutrino baseline and of the CNGS/LNGS clock synchronization. The neutrino arrival time with respect to the one computed assuming the speed of light in vacuum is found to be $\delta t_ u \equiv TOF_c - TOF_ u= (0.6 \pm 0.4\ (stat.) \pm 3.0\ (syst.))$ ns and $\delta t_{\bar{ u}} \equiv TOF_c - TOF_{\bar{ u}} = (1.8 \pm 1.4\ (stat.) \pm 3.2\ (syst.))$ ns for $ u_{\mu}$ and $\bar{ u}_{\mu}$, respectively. This corresponds to a limit on the muon neutrino velocity with respect to the speed of light of $-1.8 \times 10^{-6} < (v_{ u}-c)/c < 2.3 \times 10^{-6}$ at 90% C.L. This new measurement confirms with higher accuracy the revised OPERA result.

Search for νμ → νe oscillations with the OPERA experiment in the CNGS beam

Abstract: A first result of the search for umu $\rightarrow$ ue oscillations in the OPERA experiment, located at the Gran Sasso Underground Laboratory, is presented. The experiment looked for the appearance of ue in the CNGS neutrino beam using the data collected in 2008 and 2009. Data are compatible with the non-oscillation hypothesis in the three-flavour mixing model. A further analysis of the same data constrains the non-standard oscillation parameters $\theta_{new}$ and $\Delta m^2_{new}$ suggested by the LSND and MiniBooNE experiments. For large $\Delta m^{2}_{new}$ values ($>$0.1 eV$^{2}$), the OPERA 90% C.L. upper limit on sin$^{2}(2\theta_{new})$ based on a Bayesian statistical method reaches the value $7.2 \times 10^{-3}$.

Rice (Oryza sativa L.) roots have iodate reduction activity in response to iodine.

Abstract: Although iodine is not an essential nutrient for higher plants, their roots take up and transport the element. However, the exact mechanisms involved in iodine uptake and metabolism in higher plants have yet to be elucidated. In this study, we compared two cultivars differing in iodine tolerance (‘Nipponbare’ and ‘Gohyakumangoku’) to increasing levels of I - and IO 3 - in the root solutions of water-cultured rice ( Oryza sativa L.). We found that IO 3 - added to the root solutions was converted to I - in the presence of roots. Iodate reduction occurred over the course of several hours. Furthermore, the iodate reduction activity of ‘Nipponbare’ (iodine-sensitive) and ‘Gohyakumangoku’ (iodine-tolerant) roots increased after adding IO 3 - or I - . The roots of Barley and soybean also showed iodate reduction activity and the activity responded to iodine treatment either with IO 3 - and I - . This study suggests that plant roots biologically reduce iodate to iodide and indicates that the iodate reduction activity of roots responds to external iodine conditions.

Probe of the Solar Magnetic Field Using the “Cosmic-Ray Shadow” of the Sun

Abstract: We report on a clear solar-cycle variation of the Sun's shadow in the 10 TeV cosmic-ray flux observed by the Tibet air shower array during a full solar cycle from 1996 to 2009. In order to clarify the physical implications of the observed solar cycle variation, we develop numerical simulations of the Sun's shadow, using the potential field source surface model and the current sheet source surface (CSSS) model for the coronal magnetic field. We find that the intensity deficit in the simulated Sun's shadow is very sensitive to the coronal magnetic field structure, and the observed variation of the Sun's shadow is better reproduced by the CSSS model. This is the first successful attempt to evaluate the coronal magnetic field models by using the Sun's shadow observed in the TeV cosmic-ray flux.

Cold‐induced organelle relocation in the liverwort Marchantia polymorpha L.

Abstract: Organelles change their subcellular positions in response to various environmental conditions. Recently, we reported that cold treatments alter the intracellular position of chloroplasts and nuclei (cold positioning) in the fern Adiantum capillus-veneris; chloroplasts and nuclei localized to the periclinal cell wall relocated to anticlinal cell wall after cold treatments. To further understand organelle positioning under cold conditions, we studied cold-induced organelle relocation in the liverwort Marchantia polymorpha L. When sporelings and gemmmalings were treated under low temperature (5 °C), chloroplast cold positioning response was successfully induced both in the sporelings and the gemmmalings of M. polymorpha. Using a genetic transformation, nuclei, mitochondria or peroxisomes were visualized with a fluorescent protein, and the transgenic gemmmalings were incubated under the cold condition. Nuclei and peroxisomes, but not mitochondria, clearly relocated from the periclinal cell wall to the anticlinal cell wall after cold treatments. Our findings suggest that several organelles concurrently change their positions in the liverwort cell to cope with cold temperature.

Characteristics of extreme ultraviolet emission from mid-infrared laser-produced rare-earth Gd plasmas

Abstract: We characterize extreme ultraviolet (EUV) emission from mid-infrared (mid-IR) laser-produced plasmas (LPPs) of the rare-earth element Gd. The energy conversion efficiency (CE) and the spectral purity in the mid-IR LPPs at λL = 10.6 μm were higher than for solid-state LPPs at λL = 1.06 μm, because the plasma produced is optically thin due to the lower critical density, resulting in a CE of 0.7%. The peak wavelength remained fixed at 6.76 nm for all laser intensities studied. Plasma parameters at a mid-IR laser intensity of 1.3×1011 W/cm2 was also evaluated by use of the hydrodynamic simulation code to produce the EUV emission at 6.76 nm.

Angular multiplex recording of data pages by dual-channel polarization holography

Abstract: Simultaneous recording of two data pages by dual-channel polarization holography is experimentally demonstrated. Two data pages are transferred as two orthogonal scalar wave components of a vector wave. The signal vector wave and reference beam are superposed on a polarization-sensitive medium. The two recorded data pages are simultaneously and independently reconstructed. Furthermore, holographic angular multiplex recording is performed.

Production and Degradation of N-Acylhomoserine Lactone Quorum Sensing Signal Molecules in Bacteria Isolated from Activated Sludge

Abstract: N-Acylhomoserine lactones (AHLs) function as quorum-sensing signaling molecules in many Gram-negative bacteria We isolated a total of 672 bacterial strains from activated sludge obtained from seven sewage treatment plants in Tochigi Prefecture, Japan, and screened for AHL-producing and degrading strains Isolates (n = 107) stimulated AHL-mediated purple pigment production in AHL reporter strains Chromobacterium violaceum CV026 and VIR07 Based on their 16S rRNA gene sequences, most of these AHL-producing isolates were assigned to the genus Aeromonas, and they were divided into six groups Isolates (n = 46) degraded N-decanoyl-L-homoserine lactone (C10-HSL) within 24 h Based on their 16S rRNA gene sequences, the most dominant AHL-degrading isolates were assigned to the genus Acinetobacter and divided into six groups Strains Ooi24, Omo91, and Uzu81, which showed higher C10-HSL-degrading activity, showed putative AHL-acylase activity

Upgrading of Bitumen in the Presence of Hydrogen and Carbon Dioxide in Supercritical Water

Abstract: Upgrading of bitumen was examined in supercritical water (SCW) and its mixtures with hydrogen and carbon dioxide using semibatch reactors. Coke formation became prominent above 673 K in SCW and 693...

Polarization distribution control of parallel femtosecond pulses with spatial light modulators

Abstract: A parallel femtosecond pulse irradiation method using a computer-generated hologram displayed on a spatial light modulator provides the advantages of high throughput and high energy-use efficiency. Polarization control of the femtosecond pulse enables some unique properties, for example, selective excitation of an anisotropic molecule, focusing at a size beyond the diffraction limit owing to the longitudinal vector component of a radially polarized beam focused by a high-numerical-aperture objective lens, and fabrication of periodic nanostructures with femtosecond laser light. In this study, we propose a parallel femtosecond laser irradiation system with arbitrary polarization distribution control using a pair of spatial light modulators. By using the system, the interval between the diffraction spots was the closest yet reported by avoiding mutual interference among their side lobes. The interval was improved to half compared with our previous work. We also demonstrated the parallel fabrication of periodic nanostructures with orientation control, which, to our knowledge, is the first reported demonstration of its kind.

Seasonal changes and altitudinal variation in deer fecal pellet decay

Abstract: Surveying dung pellet groups to estimate population size requires knowledge of the dung decay rates in different environmental conditions. We evaluated seasonal and elevational differences in the decay rates of fresh deer pellets in the Ashio–Nikko Mountains, Japan. At each of four sites (1,500, 1,200, 900, and 600 m above sea level), we set out four replicates of 50 fresh deer pellets each month from September 2008 to August 2009. Dung pellet groups were evaluated after 24 h and again monthly. We also monitored the dung beetle fauna monthly using pitfall traps. Dung beetle activity was positively correlated with temperature, and the rate of dung decay was strongly correlated with dung beetle dry weight. Decay was most rapid during summer and at lower altitudes; pellets set out during winter did not decay until the following spring. Resource managers who use dung surveys to estimate population sizes in mountainous regions should consider the decay rates at different altitudes.

Henle Fiber Layer Phase Retardation Measured With Polarization-Sensitive Optical Coherence Tomography

Abstract: We developed a method based on polarization-sensitive optical coherence tomography (PS-OCT) to quantify the double pass phase retardation (DPPR) induced by Henle fiber layer in three subjects. Measurements of the retina were performed at a mean wavelength of 840 nm using two polarization states that were perpendicular in a Poincare sphere representation and phase retardation contributions from tissue layers above and below the Henle fiber layer were excluded using appropriately placed reference and measurement points. These points were semi-automatically segmented from intensity data. Using a new algorithm to determine DPPR, the Henle fiber layer in three healthy subjects aged 50-60 years showed elevated DPPR in a concentric ring about the fovea, with an average maximum DPPR for the three subjects of 22.0° (range: 20.4° to 23.0°) occurring at an average retinal eccentricity of 1.8° (range: 1.5° to 2.25°). Outside the ring, a floor of approximately 6.8° was measured, which we show can mainly be attributed to phase noise that is induced in the polarization states. We also demonstrate the method can determine fast axis orientation of the retardation, which is found consistent with the known radial pattern of Henle fibers.

Efficacy of AiiM, an N-Acylhomoserine Lactonase, against Pseudomonas aeruginosa in a Mouse Model of Acute Pneumonia

Abstract: Quorum sensing (QS) in Pseudomonas aeruginosa regulates the production of many virulence factors and plays an important role in the pathogenesis of P. aeruginosa infection. N-acyl homoserine lactones (AHL) are major QS signal molecules. Recently, a novel AHL-lactonase enzyme, AiiM, has been identified. The aim of this study was to evaluate the effect of AiiM on the virulence of P. aeruginosa in a mouse model of acute pneumonia. We developed a P. aeruginosa PAO1 strain harboring an AiiM-expressing plasmid. The production of several virulence factors by the AiiM-expressing strain was examined. Mice were intratracheally infected with an AiiM-expressing PAO1 strain. Lung histopathology, bacterial burden, and bronchoalveolar lavage (BAL) fluid were assessed at 24 h postinfection. AiiM expression in PAO1 reduced production of AHL-mediated virulence factors and attenuated cytotoxicity against human lung epithelial cells. In a mouse model of acute pneumonia, AiiM expression reduced lung injury and greatly improved the survival rates. The levels of proinflammatory cytokines and myeloperoxidase activity in BAL fluid were significantly lower in mice infected with AiiM-expressing PAO1. Thus, AiiM can strongly attenuate P. aeruginosa virulence in a mammalian model and is a potential candidate for use as a therapeutic agent against P. aeruginosa infection.