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Sample records for stand structure alter

  1. Bark beetle-induced tree mortality alters stand energy budgets due to water budget changes

    NASA Astrophysics Data System (ADS)

    Reed, David E.; Ewers, Brent E.; Pendall, Elise; Frank, John; Kelly, Robert

    2016-10-01

    Insect outbreaks are major disturbances that affect a land area similar to that of forest fires across North America. The recent mountain pine bark beetle (D endroctonus ponderosae) outbreak and its associated blue stain fungi (Grosmannia clavigera) are impacting water partitioning processes of forests in the Rocky Mountain region as the spatially heterogeneous disturbance spreads across the landscape. Water cycling may dramatically change due to increasing spatial heterogeneity from uneven mortality. Water and energy storage within trees and soils may also decrease, due to hydraulic failure and mortality caused by blue stain fungi followed by shifts in the water budget. This forest disturbance was unique in comparison to fire or timber harvesting because water fluxes were altered before significant structural change occurred to the canopy. We investigated the impacts of bark beetles on lodgepole pine (Pinus contorta) stand and ecosystem level hydrologic processes and the resulting vertical and horizontal spatial variability in energy storage. Bark beetle-impacted stands had on average 57 % higher soil moisture, 1.5 °C higher soil temperature, and 0.8 °C higher tree bole temperature over four growing seasons compared to unimpacted stands. Seasonal latent heat flux was highly correlated with soil moisture. Thus, high mortality levels led to an increase in ecosystem level Bowen ratio as sensible heat fluxes increased yearly and latent heat fluxes varied with soil moisture levels. Decline in canopy biomass (leaf, stem, and branch) was not seen, but ground-to-atmosphere longwave radiation flux increased, as the ground surface was a larger component of the longwave radiation. Variability in soil, latent, and sensible heat flux and radiation measurements increased during the disturbance. Accounting for stand level variability in water and energy fluxes will provide a method to quantify potential drivers of ecosystem processes and services as well as lead to greater

  2. Persons with unilateral transfemoral amputation have altered lumbosacral kinetics during sitting and standing movements.

    PubMed

    Hendershot, Brad D; Wolf, Erik J

    2015-07-01

    Increases in spinal loading have been related to altered movements of the lower back during gait among persons with lower limb amputation, movements which are self-perceived by these individuals as contributing factors in the development of low back pain. However, the relationships between altered trunk kinematics and associated changes in lumbosacral kinetics during sit-to-stand and stand-to-sit movements in this population have not yet been assessed. Three-dimensional lumbosacral kinetics (joint moments and powers) were compared between 9 persons with unilateral transfemoral amputation (wearing both a powered and passive knee device), and 9 uninjured controls, performing five consecutive sit-to-stand and stand-to-sit movements. During sit-to-stand movements, lumbosacral joint moments and powers were significantly larger among persons with transfemoral amputation relative to uninjured controls. During stand-to-sit movements, lumbosacral joint moments and powers were also significantly larger among persons with transfemoral amputation relative to uninjured controls, with the exception of sagittal joint powers. Minimal differences in kinetic measures were noted between the powered and passive knee devices among persons with transfemoral amputation across all conditions. Altered lumbosacral kinetics during sitting and standing movements, important activities of daily living, may play a biomechanical role in the onset and/or recurrence of low back pain or injury among persons with lower-limb amputation.

  3. Advanced Standing and Bridge Courses: Structures and Issues

    ERIC Educational Resources Information Center

    GlenMaye, Linnea F.; Lause, Timothy W.; Bolin, Brien L.

    2010-01-01

    This study explores the issue of advanced standing in MSW programs in light of the new Educational Policy and Accreditation Standards (EPAS). Advanced standing structures of MSW programs were studied using a purposive sample consisting of 203 MSW program directors with a response rate of 28% (N=58). The results indicate that slightly more than 15%…

  4. [Effects of crop tree release on stand growth and stand structure of Cunninghamia lanceolata plantation].

    PubMed

    Wu, Jian-qiang; Wang, Yi-xiang; Yang, Yi; Zhu, Ting-ting; Zhu, Xu-dan

    2015-02-01

    Crop trees were selected in a 26-year-old even-aged Cunninghamia lanceolata plantation in Lin' an, and compared in plots that were released and unreleased to examine growth and structure responses for 3 years after thinning. Crop tree release significantly increased the mean increments of diameter and volume of individual tree by 1.30 and 1.25 times relative to trees in control stands, respectively. The increments of diameter and volume of crop trees were significantly higher than those of general trees in thinning plots, crop trees and general trees in control plots, which suggested that the responses from different tree types to crop tree release treatment were different. Crop tree release increased the average distances of crop trees to the nearest neighboring trees, reducing competition among crop trees by about 68.2%. 3-year stand volume increment for thinning stands had no significant difference with that of control stands although the number of trees was only 81.5% of the control. Crop trees in thinned plots with diameters over than 14 cm reached 18.0% over 3 years, compared with 12.0% for trees without thinning, suggesting that crop tree release benefited the larger individual trees. The pattern of tree locations in thinning plots tended to be random, complying with the rule that tree distribution pattern changes with growth. Crop tree release in C. lanceolata plantation not only promoted the stand growth, but also optimized the stand structure, benefiting crop trees sustained rapid growth and larger diameter trees production.

  5. 9. "TEST STAND; STRUCTURAL; CABLE TUNNEL, PLAN, SECTIONS, DETAILS." Specifications ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. "TEST STAND; STRUCTURAL; CABLE TUNNEL, PLAN, SECTIONS, DETAILS." Specifications No. OC1-55-72-(Rev.); Drawing No. 60-09-12; sheet 43 of 148; file no. AF 1320/94, Rev. A. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract no. 4338, no change. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A Terminal Room, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

  6. 27. "TEST STAND; STRUCTURAL; SIDEWALL, NORTH WALL AND SOUTH WALL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. "TEST STAND; STRUCTURAL; SIDEWALL, NORTH WALL AND SOUTH WALL FRAMING ELEVATIONS." Specifications No. ENG-04353-55-72; Drawing No. 60-09-12; sheet 27 of 148; file no. 1320/78. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract no. 4338, Rev. B; date: 15 April 1957. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

  7. 12. "TEST STAND; STRUCTURAL; DEFLECTOR PIT DETAILS, SHEET NO. 1." ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. "TEST STAND; STRUCTURAL; DEFLECTOR PIT DETAILS, SHEET NO. 1." Specifications No. ENG-04-353-55-72; Drawing No. 60-09-12; sheet 41 of 148; file no. 1320/92, Rev. A. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract no. 4338, no change. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A Terminal Room, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

  8. 5. "TEST STAND 13, CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. "TEST STAND 1-3, CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. OC12-50-10; Drawing No. 60-09-06; no sheet number within title block. D.O. SERIES 1109/17, Rev. A. Stamped: AS BUILT; NO CHANGES. Date of Revision A: 11/1/50. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-3, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  9. The effects of partial cutting on stand structure and growth of western hemlock-Sitka spruce stands in southeast Alaska

    USGS Publications Warehouse

    Deal, R.L.; Tappeiner, J.C.

    2002-01-01

    The effects of partial cutting on species composition, new and residual-tree cohorts, tree size distribution, and tree growth was evaluated on 73 plots in 18 stands throughout southeast Alaska. These partially cut stands were harvested 12-96 years ago, when 16-96% of the former stand basal area was removed. Partial cutting maintained stand structures similar to uncut old-growth stands, and the cutting had no significant effects on tree species composition. The establishment of new-tree cohorts was positively related to the proportion of basal-area cut. The current stand basal area, tree species composition, and stand growth were significantly related to trees left after harvest (p < 0.001). Trees that were 20-80 cm dbh at the time of cutting had the greatest tree-diameter and basal-area growth and contributed the most to stand growth. Diameter growth of Sitka spruce and western hemlock was similar, and the proportion of stand basal-area growth between species was consistent for different cutting intensities. Concerns about changing tree species composition, lack of spruce regeneration, and greatly reduced stand growth and vigor with partial cuts were largely unsubstantiated. Silvicultural systems based on partial cutting can provide rapidly growing trees for timber production while maintaining complex stand structures with mixtures of spruce and hemlock trees similar to oldgrowth stands.

  10. 11. "TEST STANDS NOS. 11, 13, & 15; CONCRETE STRUCTURAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. "TEST STANDS NOS. 1-1, 1-3, & 1-5; CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. OC12-50-10; Drawing No. 60-09-04; no sheet number within title block. D.O. SERIES 1109/15, Rev. E. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, Rev. E; Date: 21 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  11. 15. "TEST STANDS NOS. 11, 13, & 15; STRUCTURAL STEEL; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. "TEST STANDS NOS. 1-1, 1-3, & 1-5; STRUCTURAL STEEL; PLAN & DETAILS." Specifications No. ENG 04-353-50-10; Drawing No. 60-09-04; no sheet number within title block. D.O. SERIES 1109/34, Rev. A. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, Rev. A, no change; Date: 21 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  12. 13. "TEST STANDS NOS. 11, 13, & 15; CONCRETE STRUCTURAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. "TEST STANDS NOS. 1-1, 1-3, & 1-5; CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. OC12-50-10; Drawing No. 60-09-04; no sheet number within title block. D.O. SERIES 1109/18, Rev. D. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, Rev. D, no change; Date: 18 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  13. 10. "TEST STANDS NOS. 11, 13, & 15; CONCRETE STRUCTURAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. "TEST STANDS NOS. 1-1, 1-3, & 1-5; CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. OC12-50-10; Drawing No. 60-09-04; no sheet number within title block. D.O. SERIES 1109/14, Rev. B. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, Rev. B; Date: 21 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  14. 12. "TEST STANDS NOS. 11, 13, & 15; CONCRETE STRUCTURAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. "TEST STANDS NOS. 1-1, 1-3, & 1-5; CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. OC12-50-10; Drawing No. 60-09-06; no sheet number within title block. D.O. SERIES 1109/16, Rev. E. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, Rev. E; Date: 26 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  15. 4. "TEST STAND NO. 13, CONCRETE STRUCTURAL PLAN AND ELEVATION." ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. "TEST STAND NO. 1-3, CONCRETE STRUCTURAL PLAN AND ELEVATION." Specifications No. OC11-50-10; Drawing No. 60-09-06; no sheet number within title block. D.O. SERIES 1109/12 REV. E. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04-353 Eng. 177, Rev. E; Date: 17 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-3, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  16. 9. "TEST STANDS NOS. 11, 13, & 15; CONCRETE STRUCTURAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. "TEST STANDS NOS. 1-1, 1-3, & 1-5; CONCRETE STRUCTURAL SECTIONS AND DETAILS." Specifications No. ENG 04-35350-10; Drawing No. 60-09-04; no sheet number within title block. D.O. SERIES 1109/13. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04353 Eng. 177, no change; Date: 17 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  17. 16. "TEST STANDS NOS. 11, 13, & 15; STRUCTURAL STEEL; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. "TEST STANDS NOS. 1-1, 1-3, & 1-5; STRUCTURAL STEEL; ELEVATIONS AND SECTIONS." Specifications No. ENG 04353-50-10; Drawing No. 60-09-04; no sheet number within title block. D.O. SERIES 1109/35, Rev. A. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract DA-04-353 Eng. 177, Rev. A; Date: 29 Dec. 1951. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  18. Impact of Acoustic Standing Waves on Structural Responses

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R.

    2014-01-01

    For several decades large reverberant chambers and most recently direct field acoustic testing have been used in the aerospace industry to test larger structures with low surface densities such as solar arrays and reflectors to qualify them and to detect faults in the design and fabrication. It has been reported that in reverberant chamber and direct acoustic testing, standing acoustic modes may strongly couple with the fundamental structural modes of the test hardware (Reference 1). In this paper results from a recent reverberant chamber acoustic test of a composite reflector are discussed. These results provide further convincing evidence of the acoustic standing wave and structural modes coupling phenomenon. The purpose of this paper is to alert test organizations to this phenomenon so that they can account for the potential increase in structural responses and ensure that flight hardware undergoes safe testing. An understanding of the coupling phenomenon may also help minimize the over and/or under testing that could pose un-anticipated structural and flight qualification issues.

  19. Free-Standing Photonic Crystal Films with Gradient Structural Colors.

    PubMed

    Ding, Haibo; Liu, Cihui; Ye, Baofen; Fu, Fanfan; Wang, Huan; Zhao, Yuanjin; Gu, Zhongze

    2016-03-23

    Hydrogel colloidal crystal composite materials have a demonstrated value in responsive photonic crystals (PhCs) via controllable stimuli. Although they have been successfully exploited to generate a gradient of color distribution, the soft hydrogels have limitations in terms of stability and storage caused by dependence on environment. Here, we present a practical strategy to fabricate free-standing PhC films with a stable gradient of structural colors using binary polymer networks. A colloidal crystal hydrogel film was prepared for this purpose, with continuously varying photonic band gaps corresponding to the gradient of the press. Then, a second polymer network was used to lock the inside non-close-packed PhC structures and color distribution of the hydrogel film. It was demonstrated that our strategy could bring about a solution to the angle-dependent structural colors of the PhC films by coating the surface with special microstructures.

  20. RF Choke for Standing Wave Structures and Flanges

    SciTech Connect

    Yeremian, Anahid; Dolgashev, Valery; Tantawi, Sami; /SLAC

    2012-07-03

    SLAC participates in the U.S. High Gradient collaboration whose charter includes basic studies of rf breakdown properties in accelerating structures. These studies include experiments with different materials and construction methods for single cell standing wave accelerating structures. The most commonly used method of joining cells of such structures is the high temperature bonding and/or brazing in hydrogen and/or vacuum. These high temperature processes may not be suitable for some of the new materials that are under consideration. We propose to build structures from cells with an rf choke, taking the cell-to-cell junction out of the electromagnetic field region. These cells may be clamped together in a vacuum enclosure, the choke joint ensuring continuity of rf currents. Next, we propose a structure with a choke joint in a high gradient cell and a view port which may allow us microscopic, in-situ observation of the metal surface during high power tests. And third, we describe the design of a TM01 choke flange for these structures.

  1. SEISMOLOGY OF STANDING KINK OSCILLATIONS OF SOLAR PROMINENCE FINE STRUCTURES

    SciTech Connect

    Soler, R.; Arregui, I.; Oliver, R.; Ballester, J. L.

    2010-10-20

    We investigate standing kink magnetohydrodynamic (MHD) oscillations in a prominence fine structure modeled as a straight and cylindrical magnetic tube only partially filled with the prominence material and with its ends fixed at two rigid walls representing the solar photosphere. The prominence plasma is partially ionized and a transverse inhomogeneous transitional layer is included between the prominence thread and the coronal medium. Thus, ion-neutral collisions and resonant absorption are the damping mechanisms considered. Approximate analytical expressions of the period, the damping time, and their ratio are derived for the fundamental mode in the thin tube and thin boundary approximations. We find that the dominant damping mechanism is resonant absorption, which provides damping ratios in agreement with the observations, whereas ion-neutral collisions are irrelevant for damping. The values of the damping ratio are independent of both the prominence thread length and its position within the magnetic tube, and coincide with the values for a tube fully filled with the prominence plasma. The implications of our results in the context of the MHD seismology technique are discussed, pointing out that the reported short-period (2-10 minutes) and short-wavelength (700-8000 km) thread oscillations may not be consistent with a standing mode interpretation and could be related to propagating waves. Finally, we show that the inversion of some prominence physical parameters, e.g., Alfven speed, magnetic field strength, transverse inhomogeneity length scale, etc., is possible using observationally determined values of the period and damping time of the oscillations along with the analytical approximations of these quantities.

  2. Bark beetle effects on fuel profiles across a range of stand structures in Douglas-fir forests of Greater Yellowstone.

    PubMed

    Donato, Daniel C; Harvey, Brian J; Romme, William H; Simard, Martin; Turner, Monica G

    2013-01-01

    Consequences of bark beetle outbreaks for forest wildfire potential are receiving heightened attention, but little research has considered ecosystems with mixed-severity fire regimes. Such forests are widespread, variable in stand structure, and often fuel limited, suggesting that beetle outbreaks could substantially alter fire potentials. We studied canopy and surface fuels in interior Douglas-fir (Pseudotsuga menziesii v. glauca) forests in Greater Yellowstone, Wyoming, USA, to determine how fuel characteristics varied with time since outbreak of the Douglas-fir beetle (Dendroctonus pseudotsugae). We sampled five stands in each of four outbreak stages, validated for pre-outbreak similarity: green (undisturbed), red (1-3 yr), gray (4-14 yr), and silver (25-30 yr). General linear models were used to compare variation in fuel profiles associated with outbreak to variation associated with the range of stand structures (dense mesic forest to open xeric parkland) characteristic of interior Douglas-fir forest. Beetle outbreak killed 38-83% of basal area within stands, generating a mix of live trees and snags over several years. Canopy fuel load and bulk density began declining in the red stage via needle drop and decreased by approximately 50% by the silver stage. The dead portion of available canopy fuels peaked in the red stage at 41%. After accounting for background variation, there was little effect of beetle outbreak on surface fuels, with differences mainly in herbaceous biomass (50% greater in red stands) and coarse woody fuels (doubled in silver stands). Within-stand spatial heterogeneity of fuels increased with time since outbreak, and surface-to-crown continuity decreased and remained low because of slow/sparse regeneration. Collectively, results suggest reduced fire potentials in post-outbreak stands, particularly for crown fire after the red stage, although abundant coarse fuels in silver stands may increase burn residence time and heat release. Outbreak

  3. Application of Lidar remote sensing to the estimation of forest canopy and stand structure

    NASA Astrophysics Data System (ADS)

    Lefsky, Michael Andrew

    A new remote sensing instrument, SLICER (Scanning Lidar Imager of Canopies by Echo Recovery), has been applied to the problem of remote sensing the canopy and stand structure of two groups of deciduous forests, Tulip Poplar-Oak stands in the vicinity of Annapolis, MD. and bottomland hardwood stands near Williamston, NC. The ability of the SLICER instrument to remotely sense the vertical distribution of canopy structure (Canopy Height Profile), bulk canopy transmittance, and several indices of canopy height has been successfully validated using twelve stands with coincident field and SLICER estimates of canopy structure. Principal components analysis has been applied to canopy height profiles from both field sites, and three significant factors were identified, each closely related to the amount of foliage in a recognizable layer of the forest, either understory, midstory, or overstory. The distribution of canopy structure to these layers is significantly correlated with the size and number of stems supporting them. The same layered structure was shown to apply to both field and SLICER remotely sensed canopy height profiles, and to apply to SLICER remotely sensed canopy profiles from both the bottomland hardwood stands in the coastal plain of North Carolina, and to mesic Tulip-Poplars stands in the upland coastal plain of Maryland. Linear regressions have demonstrated that canopy and stand structure are correlated to both a statistically significant and useful degree. Stand age and stem density is more highly correlated to stand height, while stand basal area and aboveground biomass are more closely related to a new measure of canopy structure, the quadratic mean canopy height. A geometric model of canopy structure has been shown to explain the differing relationships between canopy structure and stand basal area for stands of Eastern Deciduous Forest and Douglas Fir Forest.

  4. Groundwater Availability Alters Soil-plant Nutrient Cycling in a Stand of Invasive, N-fixing Phreatophytes

    NASA Astrophysics Data System (ADS)

    Dudley, B. D.; Miyazawa, Y.; Hughes, F.; Ostertag, R.; Kettwich, S. K.; MacKenzie, R.; Dulaiova, H.; Waters, C. A.; Bishop, J.; Giambelluca, T. W.

    2013-12-01

    N-fixing phreatophytic trees are common in arid and semi-arid regions worldwide, and can play significant roles in modifying hydrology and soil-plant nutrient cycling where they are present. In light of reductions in groundwater levels in many arid regions we estimated annual transpiration rates at a stand level, and alterations to C, N and P accretion in soils as a function of groundwater depth in a ca.120 year old stand of Prosopis pallida along an elevation gradient in coastal leeward Hawaii. We measured sapflow and stand level sapwood area to quantify transpiration, and calculated groundwater transpiration rates using P. pallida stem water δ18O values. By measuring soil resistivity, we were able to compare the volume of groundwater transpired by these trees to groundwater depth across the stand. We examined nutrient deposition and accretion in soils in lowland areas of the stand with accessible shallow groundwater, compared to upland areas with no groundwater access, as indicated by stem water δ18O values. Resistivity results suggested that groundwater was at a height close to sea level throughout the stand. Transpiration was around 1900 m3 ha-1 year-1 in the areas of the stand closest to the sea (where groundwater was at around 1-4 m below ground level) and decreased to around a tenth of that volume where groundwater was not accessible. Litterfall rates over the course of the year studied were 17 times greater at lowland sites, but this litterfall contributed ca. 24 times the N, and 35 times the P of upland sites. Thus, groundwater access contributed to the total mass of nitrogen and phosphorus deposited in the form of litter through higher litter quantity and quality. Total N content of soils was 4.7 times greater and inorganic N pools were eight times higher at lowland plots. These results suggest that groundwater depth can have strong effects on soil-plant nutrient cycling, so that reductions in the availability of shallow groundwater are likely to impact

  5. Frequent fire alters nitrogen transformations in ponderosa pine stands of the inland northwest.

    PubMed

    DeLuca, Thomas H; Sala, Anna

    2006-10-01

    Recurrent, low-severity fire in ponderosa pine (Pinus ponderosa)/interior Douglas-fir (Pseudotsuga menziesii var. glauca) forests is thought to have directly influenced nitrogen (N) cycling and availability. However, no studies to date have investigated the influence of natural fire intervals on soil processes in undisturbed forests, thereby limiting our ability to understand ecological processes and successional dynamics in this important ecosystem of the Rocky Mountain West. Here, we tested the standing hypothesis that recurrent fire in ponderosa pine/Douglas-fir forests of the Inland Northwest decreases total soil N, but increases N turnover and nutrient availability. We compared soils in stands unburned over the past 69-130 years vs. stands exposed to two or more fires over the last 130 years at seven distinct locations in two wilderness areas. Mineral soil samples were collected from each of the seven sites in June and July of 2003 and analyzed for pH, total C and N, potentially mineralizable N (PMN), and extractable NH4+, NO3-, PO4(-3), Ca+2, Mg+2, and K+. Nitrogen transformations were assessed at five sites by installing ionic resin capsules in the mineral soil in August of 2003 and by conducting laboratory assays of nitrification potential and net nitrification in aerobic incubations. Total N and PMN decreased in stands subjected to multiple fires. This loss of total N and labile N was not reflected in concentrations of extractable NH4+ and NO3-. Rather, multiple fires caused an increase in NO3 sorbed on ionic resins, nitrification potential, and net nitrification in spite of the burned stands not having been exposed to fire for at least 12-17 years. Charcoal collected from a recent fire site and added to unburned soils increased nitrification potential, suggesting that the decrease of charcoal in the absence of fire may play an important role in N transformations in fire-dependent ecosystems in the long term. Interestingly, we found no consistent effect of

  6. Post-fire stand structure impacts carbon storage within Siberian larch forests

    NASA Astrophysics Data System (ADS)

    Alexander, H. D.; Natali, S.; Loranty, M. M.; Mack, M. C.; Davydov, S. P.; Zimov, N.

    2015-12-01

    Increased fire severity within boreal forests of the Siberian Arctic has the potential to alter forest stand development thereby altering carbon (C) accumulation rates and storage during the post-fire successional interval. One potential change is increased stand density, which may result from fire consumption of the soil organic layer and changes to the seedbed that favor germination and establishment of larch trees during early succession. In this study, we evaluated above- and belowground C pools across 12 stands of varying tree density within a single 75-year old fire scar located near Cherskii, Sakha Republic, Russia. In each stand, we inventoried the size and density of larch trees and large shrubs (Salix and Betula spp.), and in combination with with allometric equations, estimated aboveground contribution to C pools. We quantified woody debris C pools using the line intercept method. We sampled belowground C pools in the soil organic layer + upper (0-10 cm) mineral soil and coarse roots (> 2 mm diameter) using sediment cores and 0.25 x 0.25-m trenches, respectively. We found that high density stands store ~ 20% more C (~7,500 g C m-2) than low density stands (~5,800 g C m-2). In high density stands, about 35% more C is stored aboveground within live larch trees (1650 g C m-2) compared to low density stands (940 g C m-2), and about 15% more C is stored in the soil organic layer and upper mineral soil. Coarse root C was 20% higher in high density stands (~475 g C m-2) compared to those with low density (~350 g C m-2). Less C was stored in large shrubs in high density stands, both in aboveground portions and coarse roots, but these amounts were relatively small (< 10% of total C pools). A fire-driven shift to denser larch stands could increase C storage, leading to a negative feedback to climate, but the combined effects of density on C dynamics, summer and winter albedo, and future fire regimes will interact to determine the magnitude of any vegetation

  7. Estimating structural attributes of Douglas-fir/western hemlock forest stands from Landsat and SPOT imagery

    NASA Technical Reports Server (NTRS)

    Cohen, Warren B.; Spies, Thomas A.

    1992-01-01

    Relationships between spectral and texture variables derived from SPOT HRV 10 m panchromatic and Landsat TM 30 m multispectral data and 16 forest stand structural attributes is evaluated to determine the utility of satellite data for analysis of hemlock forests west of the Cascade Mountains crest in Oregon and Washington, USA. Texture of the HRV data was found to be strongly related to many of the stand attributes evaluated, whereas TM texture was weakly related to all attributes. Data analysis based on regression models indicates that both TM and HRV imagery should yield equally accurate estimates of forest age class and stand structure. It is concluded that the satellite data are a valuable source for estimation of the standard deviation of tree sizes, mean size and density of trees in the upper canopy layers, a structural complexity index, and stand age.

  8. Stand Structural Controls on Evapotranspiration in Native and Invaded Tropical Montane Cloud Forest in Hawai'i

    NASA Astrophysics Data System (ADS)

    Giambelluca, T. W.; Delay, J. K.; Asner, G. P.; Martin, R. E.; Nullet, M. A.; Huang, M.; Mudd, R. G.; Takahashi, M.

    2008-12-01

    Tropical montane cloud forests (TMCFs) in Hawai'i are important zones of water input and stores of critically important native plant and animal species. Invasion by alien tree species threatens these forests and may alter the hydrological services they provide. At two TMCF sites in Hawai'i, one within native Metrosideros polymorpha forest and the other at a site heavily invaded by Psidium cattleianum, we are conducting measurements of stand-level evapotranspiration (ET), transpiration (using sapflow techniques), energy balance, and related processes. Previously presented results showed that ET as a function of available energy was 27% higher at the invaded site than the native site, with the difference rising to 53% during dry- canopy periods. In this presentation, mechanisms for the observed higher ET rate at the invaded site are explored. The difference in measured xylem flow velocities of native and alien trees cannot explain the observed stand level ET difference. Tree basal area is lower at the invaded site than the native site, again contrary to the ET difference. However, the alien trees have much smaller stem diameters, on average, than the native trees, with little or no heartwood. Hence, the cross-sectional xylem area is much greater in the invaded stand, facilitating higher transpiration rates. These results demonstrate the importance of stand structural controls on ET and raise questions about whether higher ET is a transient feature of the succession or a persistent characteristic of invasive trees.

  9. Tunable device properties of free-standing inorganic/organic flexible hybrid structures obtained by exfoliation

    NASA Astrophysics Data System (ADS)

    Shetty, Amitha; Nanda, Karuna Kar

    2012-06-01

    We report the fabrication of free-standing flexible inorganic/organic hybrid structures by exfoliating ZnO nanostructured films from the flat indium tin oxide (ITO)/silicon/sapphire substrates using poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS). Strong interaction between ZnO and PEDOT:PSS and the thermomechanical response of PEDOT:PSS are the key issues for the exfoliation to prevail. The performance of the free-standing hybrid structures as rectifiers and photodetectors is better as compared to ITO supported hybrid structures. It is also shown that device properties of hybrid structures can be tuned by using different electrode materials.

  10. 26. "TEST STAND, STRUCTURAL, FOUNDATION PLAN." Specifications No. ENG043535572; Drawing ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. "TEST STAND, STRUCTURAL, FOUNDATION PLAN." Specifications No. ENG-04-353-55-72; Drawing No. 60-0912; sheet 25 of 148; file no. 1320/76. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract no. 4338, no change. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

  11. Array structure design handbook for stand alone photovoltaic applications

    NASA Technical Reports Server (NTRS)

    Didelot, R. C.

    1980-01-01

    This handbook will permit the user to design a low-cost structure for a variety of photovoltaic system applications under 10 kW. Any presently commercially available photovoltaic modules may be used. Design alternatives are provided for different generic structure types, structural materials, and electric interfaces. The use of a hand-held calculator is sufficient to perform the necessary calculations for the array designs.

  12. Altered Structural Connectome in Temporal Lobe Epilepsy

    PubMed Central

    DeSalvo, Matthew N.; Douw, Linda; Tanaka, Naoaki; Reinsberger, Claus

    2014-01-01

    Purpose To study differences in the whole-brain structural connectomes of patients with left temporal lobe epilepsy (TLE) and healthy control subjects. Materials and Methods This study was approved by the institutional review board, and all individuals gave signed informed consent. Sixty-direction diffusion-tensor imaging and magnetization-prepared rapid acquisition gradient-echo (MP-RAGE) magnetic resonance imaging volumes were analyzed in 24 patients with left TLE and in 24 healthy control subjects. MP-RAGE volumes were segmented into 1015 regions of interest (ROIs) spanning the entire brain. Deterministic white matter tractography was performed after voxelwise tensor calculation. Weighted structural connectivity matrices were generated by using the pairwise density of connecting fibers between ROIs. Graph theoretical measures of connectivity networks were compared between groups by using linear models with permutation testing. Results Patients with TLE had 22%–45% reduced (P < .01) distant connectivity in the medial orbitofrontal cortex, temporal cortex, posterior cingulate cortex, and precuneus, compared with that in healthy subjects. However, local connectivity, as measured by means of network efficiency, was increased by 85%–270% (P < .01) in the medial and lateral frontal cortices, insular cortex, posterior cingulate cortex, precuneus, and occipital cortex in patients with TLE as compared with healthy subjects. Conclusion This study suggests that TLE involves altered structural connectivity in a network that reaches beyond the temporal lobe, especially in the default mode network. © RSNA, 2013 Online supplemental material is available for this article. PMID:24475828

  13. Modelling Variable Fire Severity in Boreal Forests: Effects of Fire Intensity and Stand Structure.

    PubMed

    Miquelajauregui, Yosune; Cumming, Steven G; Gauthier, Sylvie

    2016-01-01

    It is becoming clear that fires in boreal forests are not uniformly stand-replacing. On the contrary, marked variation in fire severity, measured as tree mortality, has been found both within and among individual fires. It is important to understand the conditions under which this variation can arise. We integrated forest sample plot data, tree allometries and historical forest fire records within a diameter class-structured model of 1.0 ha patches of mono-specific black spruce and jack pine stands in northern Québec, Canada. The model accounts for crown fire initiation and vertical spread into the canopy. It uses empirical relations between fire intensity, scorch height, the percent of crown scorched and tree mortality to simulate fire severity, specifically the percent reduction in patch basal area due to fire-caused mortality. A random forest and a regression tree analysis of a large random sample of simulated fires were used to test for an effect of fireline intensity, stand structure, species composition and pyrogeographic regions on resultant severity. Severity increased with intensity and was lower for jack pine stands. The proportion of simulated fires that burned at high severity (e.g. >75% reduction in patch basal area) was 0.80 for black spruce and 0.11 for jack pine. We identified thresholds in intensity below which there was a marked sensitivity of simulated fire severity to stand structure, and to interactions between intensity and structure. We found no evidence for a residual effect of pyrogeographic region on simulated severity, after the effects of stand structure and species composition were accounted for. The model presented here was able to produce variation in fire severity under a range of fire intensity conditions. This suggests that variation in stand structure is one of the factors causing the observed variation in boreal fire severity.

  14. Modelling Variable Fire Severity in Boreal Forests: Effects of Fire Intensity and Stand Structure

    PubMed Central

    Miquelajauregui, Yosune; Cumming, Steven G.; Gauthier, Sylvie

    2016-01-01

    It is becoming clear that fires in boreal forests are not uniformly stand-replacing. On the contrary, marked variation in fire severity, measured as tree mortality, has been found both within and among individual fires. It is important to understand the conditions under which this variation can arise. We integrated forest sample plot data, tree allometries and historical forest fire records within a diameter class-structured model of 1.0 ha patches of mono-specific black spruce and jack pine stands in northern Québec, Canada. The model accounts for crown fire initiation and vertical spread into the canopy. It uses empirical relations between fire intensity, scorch height, the percent of crown scorched and tree mortality to simulate fire severity, specifically the percent reduction in patch basal area due to fire-caused mortality. A random forest and a regression tree analysis of a large random sample of simulated fires were used to test for an effect of fireline intensity, stand structure, species composition and pyrogeographic regions on resultant severity. Severity increased with intensity and was lower for jack pine stands. The proportion of simulated fires that burned at high severity (e.g. >75% reduction in patch basal area) was 0.80 for black spruce and 0.11 for jack pine. We identified thresholds in intensity below which there was a marked sensitivity of simulated fire severity to stand structure, and to interactions between intensity and structure. We found no evidence for a residual effect of pyrogeographic region on simulated severity, after the effects of stand structure and species composition were accounted for. The model presented here was able to produce variation in fire severity under a range of fire intensity conditions. This suggests that variation in stand structure is one of the factors causing the observed variation in boreal fire severity. PMID:26919456

  15. Cold test results of a standing wave muffin-tin structure at X-band

    SciTech Connect

    Chou, P.J.; Hanna, S.M.; Henke, H.; Menegat, A.; Siemann, R.H.; Whittum, D.

    1996-11-01

    A muffin-tin structure is chosen to study high gradient acceleration in the millimeter wavelength range. In order to understand the electromagnetic field characteristics, a standing wave structure operating at a frequency around 11.4 GHz was built. Cold test measurements were performed and results are presented. Comparisons with theoretical predictions based on computer simulation are shown.

  16. Design of RF Feed System for Standing-Wave Accelerator Structures

    SciTech Connect

    Neilson, Jeffrey; Tantawi, Sami; Dolgashev, Valery

    2010-11-04

    We are investigating a standing wave structure with an rf feed to each individual cell. This approach minimizes rf power flow and electromagnetic energy absorbed by an rf breakdown. The objective of this work is a robust high-gradient (above 100 MV/m) X-band accelerator structure.

  17. Design of RF Feed System for Standing-Wave Accelerator Structures

    SciTech Connect

    Neilson, J.; Tantawi, S.; Dolgashev, V.; /SLAC

    2012-05-25

    We are investigating a standing wave accelerator structure that uses a rf feed to each individual cell. This approach minimizes rf power flow and electromagnetic energy absorbed by an rf breakdown. The objective of this work is a robust high-gradient (above 100 MV/m) X-band accelerator structure.

  18. Structural alterations of skeletal muscle in copd

    PubMed Central

    Mathur, Sunita; Brooks, Dina; Carvalho, Celso R. F.

    2014-01-01

    Background: Chronic obstructive pulmonary disease (COPD) is a respiratory disease associated with a systemic inflammatory response. Peripheral muscle dysfunction has been well characterized in individuals with COPD and results from a complex interaction between systemic and local factors. Objective: In this narrative review, we will describe muscle wasting in people with COPD, the associated structural changes, muscle regenerative capacity and possible mechanisms for muscle wasting. We will also discuss how structural changes relate to impaired muscle function and mobility in people with COPD. Key Observations: Approximately 30–40% of individuals with COPD experience muscle mass depletion. Furthermore, muscle atrophy is a predictor of physical function and mortality in this population. Associated structural changes include a decreased proportion and size of type-I fibers, reduced oxidative capacity and mitochondrial density mainly in the quadriceps. Observations related to impaired muscle regenerative capacity in individuals with COPD include a lower proportion of central nuclei in the presence or absence of muscle atrophy and decreased maximal telomere length, which has been correlated with reduced muscle cross-sectional area. Potential mechanisms for muscle wasting in COPD may include excessive production of reactive oxygen species (ROS), altered amino acid metabolism and lower expression of peroxisome proliferator-activated receptors-gamma-coactivator 1-alpha mRNA. Despite a moderate relationship between muscle atrophy and function, impairments in oxidative metabolism only seems weakly related to muscle function. Conclusion: This review article demonstrates the cellular modifications in the peripheral muscle of people with COPD and describes the evidence of its relationship to muscle function. Future research will focus on rehabilitation strategies to improve muscle wasting and maximize function. PMID:24678302

  19. Stand structural diversity rather than species diversity enhances aboveground carbon storage in secondary subtropical forests in Eastern China

    NASA Astrophysics Data System (ADS)

    Ali, Arshad; Yan, En-Rong; Chen, Han Y. H.; Chang, Scott X.; Zhao, Yan-Tao; Yang, Xiao-Dong; Xu, Ming-Shan

    2016-08-01

    Stand structural diversity, typically characterized by variances in tree diameter at breast height (DBH) and total height, plays a critical role in influencing aboveground carbon (C) storage. However, few studies have considered the multivariate relationships of aboveground C storage with stand age, stand structural diversity, and species diversity in natural forests. In this study, aboveground C storage, stand age, tree species, DBH and height diversity indices, were determined across 80 subtropical forest plots in Eastern China. We employed structural equation modelling (SEM) to test for the direct and indirect effects of stand structural diversity, species diversity, and stand age on aboveground C storage. The three final SEMs with different directions for the path between species diversity and stand structural diversity had a similar goodness of fit to the data. They accounted for 82 % of the variation in aboveground C storage, 55-59 % of the variation in stand structural diversity, and 0.1 to 9 % of the variation in species diversity. Stand age demonstrated strong positive total effects, including a positive direct effect (β = 0.41), and a positive indirect effect via stand structural diversity (β = 0.41) on aboveground C storage. Stand structural diversity had a positive direct effect on aboveground C storage (β = 0.56), whereas there was little total effect of species diversity as it had a negative direct association with, but had a positive indirect effect, via stand structural diversity, on aboveground C storage. The negligible total effect of species diversity on aboveground C storage in the forests under study may have been attributable to competitive exclusion with high aboveground biomass, or a historical logging preference for productive species. Our analyses suggested that stand structural diversity was a major determinant for variations in aboveground C storage in the secondary subtropical forests in Eastern China. Hence, maintaining tree DBH and

  20. Temporal Structure of Support Surface Translations Drive the Temporal Structure of Postural Control During Standing

    PubMed Central

    Rand, Troy J.; Myers, Sara A.; Kyvelidou, Anastasia; Mukherjee, Mukul

    2015-01-01

    A healthy biological system is characterized by a temporal structure that exhibits fractal properties and is highly complex. Unhealthy systems demonstrate lowered complexity and either greater or less predictability in the temporal structure of a time series. The purpose of this research was to determine if support surface translations with different temporal structures would affect the temporal structure of the center of pressure (COP) signal. Eight healthy young participants stood on a force platform that was translated in the anteroposterior direction for input conditions of varying complexity: white noise, pink noise, brown noise, and sine wave. Detrended fluctuation analysis was used to characterize the long-range correlations of the COP time series in the AP direction. Repeated measures ANOVA revealed differences among conditions (P < .001). The less complex support surface translations resulted in a less complex COP compared to normal standing. A quadratic trend analysis demonstrated an inverted-u shape across an increasing order of predictability of the conditions (P < .001). The ability to influence the complexity of postural control through support surface translations can have important implications for rehabilitation. PMID:25994281

  1. Bark Beetles as Significant Forest Disturbances: Estimating Susceptibility Based On Stand Structure

    NASA Astrophysics Data System (ADS)

    Hicke, J. A.; Jenkins, J. C.

    2007-12-01

    In the western United States, bark beetle outbreaks affect millions of hectares of forests. These disturbances have multiple effects on ecosystems, including modifications to biogeochemical cycles, interactions with fire, and changes in land cover type and species composition. In recent years, extensive outbreaks have occurred in multiple forest ecosystems in the West, thought to be caused by climate variability and stand structure. In this study, we focus on epidemics of mountain pine beetle. We used USDA Forest Service inventories and a model to estimate lodgepole pine susceptibility to mountain pine beetle attack in the West. The model considers stand age, stem density, and percentage of large lodgepole pine to estimate stand susceptibility. Over 150,000 trees in 4454 plots across the western United States were used to compute susceptibility at the plot scale as well as map susceptibility at the county scale. We found that regional susceptibility was high (estimated potential of losses of 34% of stand basal area) for 2.8 Mha, or 46%, of lodgepole pine forests. The highest susceptibility occurred in the Rocky Mountains, with lower susceptibility in coastal states. This study reveals that a substantial fraction of lodgepole pine forest could be subjected to bark beetle outbreaks under current climate conditions. Because climate and weather affect beetle populations, projected future warming will influence outbreak regimes. Thus, forest ecosystems in the West may experience more frequent, extensive, and/or severe disturbances than in recent decades due to current stand structure, and these disturbances may be intensified under climate change.

  2. Forest stand structure, productivity, and age mediate climatic effects on aspen decline.

    PubMed

    Bell, David M; Bradford, John B; Lauenroth, William K

    2014-08-01

    Because forest stand structure, age, and productivity can mediate the impacts of climate on quaking aspen (Populus tremuloides) mortality, ignoring stand-scale factors limits inference on the drivers of recent sudden aspen decline. Using the proportion of aspen trees that were dead as an index of recent mortality at 841 forest inventory plots, we examined the relationship of this mortality index to forest structure and climate in the Rocky Mountains and Intermountain Western United States. We found that forest structure explained most of the patterns in mortality indices, but that variation in growing-season vapor pressure deficit and winter precipitation over the last 20 years was important. Mortality index sensitivity to precipitation was highest in forests where aspen exhibited high densities, relative basal areas, quadratic mean diameters, and productivities, whereas sensitivity to vapor pressure deficit was highest in young forest stands. These results indicate that the effects of drought on mortality may be mediated by forest stand development, competition with encroaching conifers, and physiological vulnerabilities of large trees to drought. By examining mortality index responses to both forest structure and climate, we show that forest succession cannot be ignored in studies attempting to understand the causes and consequences of sudden aspen decline.

  3. Particle motion of accelerated electrons in standing-wave RF structures

    NASA Astrophysics Data System (ADS)

    Hammen, A. F. J.; Corstens, J. M.; Botman, J. I. M.; Hagedoorn, H. L.; Theuws, W. H. C.

    1999-05-01

    A Hamiltonian theory has been formulated, which is used to calculate accelerated particle motion in standing-wave RF structures. In particular, these calculations have been applied to the Eindhoven racetrack microtron accelerating cavity. The calculations are in excellent agreement with simulations performed by particle-tracking codes.

  4. Forest stand structure, productivity, and age mediate climatic effects on aspen decline

    USGS Publications Warehouse

    Bell, David M.; Bradford, John B.; Lauenroth, William K.

    2014-01-01

    Because forest stand structure, age, and productivity can mediate the impacts of climate on quaking aspen (Populus tremuloides) mortality, ignoring stand-scale factors limits inference on the drivers of recent sudden aspen decline. Using the proportion of aspen trees that were dead as an index of recent mortality at 841 forest inventory plots, we examined the relationship of this mortality index to forest structure and climate in the Rocky Mountains and Intermountain Western United States. We found that forest structure explained most of the patterns in mortality indices, but that variation in growing-season vapor pressure deficit and winter precipitation over the last 20 years was important. Mortality index sensitivity to precipitation was highest in forests where aspen exhibited high densities, relative basal areas, quadratic mean diameters, and productivities, whereas sensitivity to vapor pressure deficit was highest in young forest stands. These results indicate that the effects of drought on mortality may be mediated by forest stand development, competition with encroaching conifers, and physiological vulnerabilities of large trees to drought. By examining mortality index responses to both forest structure and climate, we show that forest succession cannot be ignored in studies attempting to understand the causes and consequences of sudden aspen decline.

  5. Stand-structural effects on Heterobasidion abietinum-related mortality following drought events in Abies pinsapo.

    PubMed

    Linares, Juan Carlos; Camarero, Jesús Julio; Bowker, Matthew A; Ochoa, Victoria; Carreira, José Antonio

    2010-12-01

    Climate change may affect tree-pathogen interactions. This possibility has important implications for drought-prone forests, where stand dynamics and disease pathogenicity are especially sensitive to climatic stress. In addition, stand structural attributes including density-dependent tree-to-tree competition may modulate the stands' resistance to drought events and pathogen outbreaks. To assess the effects of stand structure on root-rot-related mortality after severe droughts, we focused on Heterobasidion abietinum mortality in relict Spanish stands of Abies pinsapo, a drought-sensitive fir. We compared stand attributes and tree spatial patterns in three plots with H. abietinum root-rot disease and three plots without root-rot. Point-pattern analyses were used to investigate the scale and extent of mortality patterns and to test hypotheses related to the spread of the disease. Dendrochronology was used to date the year of death and to assess the association between droughts and growth decline. We applied a structural equation modelling approach to test if tree mortality occurs more rapidly than predicted by a simple distance model when trees are subjected to high tree-to-tree competition and following drought events. Contrary to expectations of drought mortality, the effect of precipitation on the year of death was strong and negative, indicating that a period of high precipitation induced an earlier tree death. Competition intensity, related to the size and density of neighbour trees, also induced an earlier tree death. The effect of distance to the disease focus was negligible except in combination with intensive competition. Our results indicate that infected trees have decreased ability to withstand drought stress, and demonstrate that tree-to-tree competition and fungal infection act as predisposing factors of forest decline and mortality.

  6. Seeing the forest for the heterogeneous trees: stand-scale resource distributions emerge from tree-scale structure.

    PubMed

    Boyden, Suzanne; Montgomery, Rebecca; Reich, Peter B; Palik, Brian

    2012-07-01

    Forest ecosystem processes depend on local interactions that are modified by the spatial pattern of trees and resources. Effects of resource supplies on processes such as regeneration are increasingly well understood, yet we have few tools to compare resource heterogeneity among forests that differ in structural complexity. We used a neighborhood approach to examine understory light and nutrient availability in a well-replicated and large-scale variable-retention harvesting experiment in a red pine forest in Minnesota, USA. The experiment included an unharvested control and three harvesting treatments with similar tree abundance but different patterns of retention (evenly dispersed as well as aggregated retention achieved by cutting 0.1- or 0.3-ha gaps). We measured light and soil nutrients across all treatments and mapped trees around each sample point to develop an index of neighborhood effects (NI). Field data and simulation modeling were used to test hypotheses that the mean and heterogeneity of resource availability would increase with patchiness because of greater variation in competitive environments. Our treatments dramatically altered the types and abundances of competitive neighborhoods (NI) in each stand and resulted in significantly nonlinear relationships of light, nitrogen and phosphorus availability to NI. Hence, the distribution of neighborhoods in each treatment had a significant impact on resource availability and heterogeneity. In dense control stands, neighborhood variation had little impact on resource availability, whereas in more open stands (retention treatments), it had large effects on light and modest effects on soil nutrients. Our results demonstrate that tree spatial pattern can affect resource availability and heterogeneity in explainable and predictable ways, and that neighborhood models provide a useful tool for scaling heterogeneity from the individual tree to the stand. These insights are needed to anticipate the outcomes of

  7. Structurally altered capsular polysaccharides produced by mutant bacteria

    NASA Technical Reports Server (NTRS)

    Kern, Roger G. (Inventor); Petersen, Gene R. (Inventor); Richards, Gil F. (Inventor)

    1995-01-01

    Structurally altered capsular polysaccharides are produced by mutant bacteria. These polysaccharides are isolated by selecting a wild type bacterial strain and a phage producing degradative enzymes that have substrate specificity for the capsular polysaccharides produced by the wild type bacteria. Phage-resistant mutants producing capsular polysaccharides are selected and the structurally altered capsular polysaccharide is isolated therefrom.

  8. Network community structure alterations in adult schizophrenia: identification and localization of alterations

    PubMed Central

    Lerman-Sinkoff, Dov B.; Barch, Deanna M.

    2015-01-01

    A growing body of literature suggests functional connectivity alterations in schizophrenia. While findings have been mixed, evidence points towards a complex pattern of hyper-connectivity and hypo-connectivity. This altered connectivity can be represented and analyzed using the mathematical frameworks provided by graph and information theory to represent functional connectivity data as graphs comprised of nodes and edges linking the nodes. One analytic technique in this framework is the determination and analysis of network community structure, which is the grouping of nodes into linked communities or modules. This data-driven technique finds a best-fit structure such that nodes in a given community have greater connectivity with nodes in their community than with nodes in other communities. These community structure representations have been found to recapitulate known neural-systems in healthy individuals, have been used to identify novel functional systems, and have identified and localized community structure alterations in a childhood onset schizophrenia cohort. In the present study, we sought to determine whether community structure alterations were present in an adult onset schizophrenia cohort while stringently controlling for sources of imaging artifacts. Group level average graphs in healthy controls and individuals with schizophrenia exhibited visually similar network community structures and high amounts of normalized mutual information (NMI). However, testing of individual subject community structures identified small but significant alterations in community structure with alterations being driven by changes in node community membership in the somatosensory, auditory, default mode, salience, and subcortical networks. PMID:26793435

  9. A Structural Weight Estimation Program (SWEEP) for Aircraft. Volume 11 - Flexible Airloads Stand-Alone Program

    DTIC Science & Technology

    1974-06-01

    load due to vertical acceleration. 35 Wing Structural Influence Coefficients For the static aeroelastic analysis , the exposed semispan of the wing...SIC^ (45) _^_ For the static aeroelastic analysis , a matrix of streamwise slopes, SIC, is required. This matrix is formed by premuldplying the SIC...and Centers of Pressure 26 3 Wing Diagram for Flexible Load Analysis 27 4 Calling-Called Matrix for Flexible Airloads Stand-Alone Program 59 5

  10. Stand dynamics and tree coexistence in an analytical structured model: the role of recruitment.

    PubMed

    Angulo, Óscar; Bravo de la Parra, Rafael; López-Marcos, Juan C; Zavala, Miguel A

    2013-09-21

    Understanding the mechanisms of coexistence and niche partitioning in plant communities is a central question in ecology. Current theories of forest dynamics range between the so-called neutral theories which assume functional equivalence among coexisting species to forest simulators that explain species assemblages as the result of tradeoffs in species individual strategies at several ontogenetic stages. Progress in these questions has been hindered by the inherent difficulties of developing analytical size-structured models of stand dynamics. This precludes examination of the relative importance of each mechanism on tree coexistence. In previous simulation and analytical studies emphasis has been given to interspecific differences at the sapling stage, and less so to interspecific variation in seedling recruitment. In this study we develop a partial differential equation model of stand dynamics in which competition takes place at the recruitment stage. Species differ in their size-dependent growth rates and constant mortality rates. Recruitment is described as proportional to the basal area of conspecifics, to account for fecundity and seed supply per unit of basal area, and is corrected with a decreasing function of species specific basal area to account for competition. We first analyze conditions for population persistence in monospecific stands and second we investigate conditions of coexistence for two species. In the monospecific case we found a stationary stand structure based on an inequality between mortality rate and seed supply. In turn, intra-specific competition does not play any role on the asymptotic extinction or population persistence. In the two-species case we found that coexistence can be attained when the reciprocal negative effect on recruitment follows a given relation with respect to intraspecific competition. Specifically a tradeoff between recruitment potential (i.e. shade tolerance or predation avoidance) and fecundity or growth rate

  11. Lightning Protection and Structural Bonding for the B2 Test Stand

    NASA Technical Reports Server (NTRS)

    Kinard, Brandon

    2015-01-01

    With the privatization of the space industry, NASA has entered a new era. To explore deeper parts of the solar system, NASA is developing a new spacecraft, the Space Launch System (SLS), capable of reaching these destinations, such as an asteroid or Mars. However, the test stand that is capable of testing the stage has been unused for many years. In addition to the updating/repair of the stand, more steel is being added to fully support the SLS. With all these modifications, the lightning protection system must be brought up to code to assure the protection of all personnel and assets. Structural bonding is a part of the lightning protection system. The focus of this project was to assure proper structural bonding. To begin, all relevant technical standards and the construction specifications were reviewed. This included both the specifications for the lightning protection and for general construction. The drawings were reviewed as well. From the drawings, bolted structural joints were reviewed to determine whether bonding was necessary. Several bolted joints were determined to need bonding according to the notes in the drawings. This exceeds the industry standards. The bolted joints are an electrically continuous joint. During tests, the stand experiences heavy vibration that may weaken the continuity of the bolted joint. Therefore, the secondary bonding is implemented to ensure that the structural joint has low resistance. If the structural joint has a high resistance because of corrosion, a potential gradient can occur that can cause a side flash. Damage, injury, or death can occur from a side flash so they are to be prevented. A list of the identified structural joints was compiled and sent to the contractor to be bonded. That covers the scope of this project.

  12. Quantitative adsorbate structure determination for quasicrystals using x-ray standing waves.

    PubMed

    Diehl, R D; Li, H I; Su, S Y; Mayer, A; Stanisha, N A; Ledieu, J; Lovelock, K R J; Jones, Robert G; Deyko, A; Wearing, L H; McGrath, R; Chaudhuri, A; Woodruff, D P

    2014-09-05

    The quantitative structure determination of adsorbed species on quasicrystal surfaces has so far appeared to present insurmountable problems. The normal incidence standing x-ray wave field technique offers a simple solution, without extensive data sets or large computations. Its application to quasicrystals raises several conceptual difficulties that are related to the phase problem in x-ray diffraction. We demonstrate their solution for the case of Si atoms adsorbed on the decagonal Co-rich modification of the Al-Co-Ni quasicrystal to determine the local structure, comprising 6-atom clusters in particular hollow sites.

  13. Quantitative Adsorbate Structure Determination for Quasicrystals Using X-Ray Standing Waves

    NASA Astrophysics Data System (ADS)

    Diehl, R. D.; Li, H. I.; Su, S. Y.; Mayer, A.; Stanisha, N. A.; Ledieu, J.; Lovelock, K. R. J.; Jones, Robert G.; Deyko, A.; Wearing, L. H.; McGrath, R.; Chaudhuri, A.; Woodruff, D. P.

    2014-09-01

    The quantitative structure determination of adsorbed species on quasicrystal surfaces has so far appeared to present insurmountable problems. The normal incidence standing x-ray wave field technique offers a simple solution, without extensive data sets or large computations. Its application to quasicrystals raises several conceptual difficulties that are related to the phase problem in x-ray diffraction. We demonstrate their solution for the case of Si atoms adsorbed on the decagonal Co-rich modification of the Al-Co-Ni quasicrystal to determine the local structure, comprising 6-atom clusters in particular hollow sites.

  14. Structural Alterations in the Cornea from Exposure to Infrared Radiation

    DTIC Science & Technology

    1985-07-01

    mylar disks that were preformed - 4- to match the corneal curvature. The disks were attached 0 at their edges to excised corneas using cyanoacrylate ...ICFIECOP JHU/APL TG 1364 JULY 1985 (0 FINAL Technical Memorandum STRUCTURAL ALTERATIONS IN THE CORNEA FROM EXPOSURE TO INFRARED RADIATION R. A...Structural Alterations in the Cornea from Exposure to Infrared Radiation 12. PERSONAL AUTHOR(S) R. A. Farrell, R. L. McCally, C. B. Bargeron, and W. R. Green

  15. Bioenergy harvesting impacts on ecologically important stand structure and habitat characteristics.

    PubMed

    Littlefield, Caitlin E; Keeton, William S

    2012-10-01

    Demand for forest bioenergy fuel is increasing in the northern forest region of eastern North America and beyond, but ecological impacts, particularly on habitat, of bioenergy harvesting remain poorly explored in the peer-reviewed literature. Here, we evaluated the impacts of bioenergy harvests on stand structure, including several characteristics considered important for biodiversity and habitat functions. We collected stand structure data from 35 recent harvests in northern hardwood-conifer forests, pairing harvested areas with unharvested reference areas. Biometrics generated from field data were analyzed using a multi-tiered nonparametric uni- and multivariate statistical approach. In analyses comparing harvested to reference areas, sites that had been whole-tree harvested demonstrated significant differences (relative negative contrasts, P < 0.05) in snag density, large live-tree density, well-decayed downed coarse woody debris volume, and structural diversity index (H) values, while sites that had not been whole-tree harvested did not exhibit significant differences. Classification and regression tree (CART) analyses suggested that the strongest predictors of structural retention, as indicated by downed woody debris volumes and H index, were silvicultural treatment and equipment type rather than the percentage of harvested volume allocated to bioenergy uses. In general, bioenergy harvesting impacts were highly variable across the study sites, suggesting a need for harvesting guidelines aimed at encouraging retention of ecologically important structural attributes.

  16. Stand structure and dynamics of sand pine differ between the Florida panhandle and peninsula

    USGS Publications Warehouse

    Drewa, P.B.; Platt, W.J.; Kwit, C.; Doyle, T.W.

    2008-01-01

    Size and age structures of stand populations of numerous tree species exhibit uneven or reverse J-distributions that can persist after non-catastrophic disturbance, especially windstorms. Among disjunct populations of conspecific trees, alternative distributions are also possible and may be attributed to more localized variation in disturbance. Regional differences in structure and demography among disjunct populations of sand pine (Pinus clausa (Chapm. ex Engelm.) Vasey ex Sarg.) in the Florida panhandle and peninsula may result from variation in hurricane regimes associated with each of these populations. We measured size, age, and growth rates of trees from panhandle and peninsula populations and then compiled size and age class distributions. We also characterized hurricanes in both regions over the past century. Size and age structures of panhandle populations were unevenly distributed and exhibited continuous recruitment; peninsula populations were evenly sized and aged and exhibited only periodic recruitment. Since hurricane regimes were similar between regions, historical fire regimes may have been responsible for regional differences in structure of sand pine populations. We hypothesize that fires were locally nonexistent in coastal panhandle populations, while periodic high intensity fires occurred in peninsula populations over the past century. Such differences in local fire regimes could have resulted in the absence of hurricane effects in the peninsula. Increased intensity of hurricanes in the panhandle and current fire suppression patterns in the peninsula may shift characteristics of sand pine stands in both regions. ?? 2007 Springer Science+Business Media B.V.

  17. BVOC emission in Norway spruce: the effect of stand structure, high temperature and ozone levels.

    NASA Astrophysics Data System (ADS)

    Pallozzi, Emanuele; Guidolotti, Gabriele; Večeřová, Kristýna; Esposito, Raffaela; Lusini, Ilaria; Juráň, Stanislav; Urban, Otmar; Calfapietra, Carlo

    2015-04-01

    Norway spruce (Picea abies L.) is a widely distributed conifer species in the boreal zone and mountain areas of central Europe and is a moderate emitter of volatile organic compounds (BVOC). Although the vaporization and diffusion processes from resin ducts were generally considered to be the main processes for monoterpene emissions in conifers, recently it has been showed that a significant portion (up to one third) of monoterpene emissions of Norway spruce can originate from novel biosynthesis, thus depending on photosynthetic processes. For this reason, both biosynthesis and emission are strongly influenced by the environment and the stand structure. They increase with both increasing light and temperature during the warmer periods, although those are the periods with the higher ozone concentration that usually act as an inhibitor of both assimilation and isoprenoids synthesis and emission. On the other hand, stand structure can play an important role, because the photosynthetic capacity is influenced by temperature and light conditions through the canopy. In order to assess the effects of stand structure, temperature and ozone on isoprenoids emission of Norway spruce we carried out field and laboratory experiments. In the experimental field campaigns we measured: assimilation and BVOC emission from needles of sun and shade layers within the canopy of the spruce forest present at the Bily Kriz experimental research site (Moravian-Silesian Beskydy Mountains, 49° 33' N, 18° 32' E, NE of Czech Republic, 908 m a.s.l.). Moreover in the same layers we measured continuously concentration of BVOCs in the air using a PTR-TOF-MS. In laboratory we analyzed the effects of short-term exposure to high temperature and high ozone concentrations on branches of spruce trees collected at the Bily Kriz experimental research site. Preliminary results show that in Norway spruce both stand structure and environmental conditions influenced the gas exchange and BVOC emission rates

  18. Altered gene expression correlates with DNA structure.

    PubMed

    Kohwi, Y; Kohwi-Shigematsu, T

    1991-12-01

    We examined the participation of triplex DNA structure in gene regulation using a poly(dG)-poly(dC) sequence as a model. We show that a poly(dG)-poly(dC) sequence, which can adopt an intramolecular dG.dG.dC triplex under superhelical strain, strongly augments gene expression when placed 5' to a promoter. The activity of this sequence exhibits a striking length dependency: dG tracts of 27-30 bp augment the expression of a reporter gene to a level comparable to that observed with the polyoma enhancer in mouse LTK- cells, whereas tracts of 35 bp and longer have virtually no effect. A supercoiled plasmid containing a dG tract of 30 bp competes in vivo for a trans-acting factor as revealed by reduction in the reporter gene transcription driven by the (dG)29/promoter of the test plasmid, while dGs of 35 bp and longer in the competition plasmid failed to compete. In purified supercoiled plasmid DNA at a superhelical density of -0.05, dG tracts of 32 bp and longer form a triplex, whereas those of 30 bp and shorter remain double-stranded under a PBS solution. These results suggest that a localized superhelical strain can exist, at least transiently, in mouse LTK- cells, and before being relaxed by topoisomerases this rapidly induces dG tracts of 35 bp and longer to adopt a triplex preventing the factor from binding. Thus, these data suggest that a poly(dG)-poly(dC) sequence can function as a negative regulator by adopting an intramolecular triple helix structure in vivo.

  19. 2013 Immune Risk Standing Review Panel Evidence Review for: The Risk of Crew Adverse Health Event Due to Altered Immune Response

    NASA Technical Reports Server (NTRS)

    Steinberg, Susan

    2014-01-01

    The 2013 Immune Risk Standing Review Panel (from here on referred to as the SRP) met for a site visit in Houston, TX on February 3-4, 2014. The SRP reviewed the new Evidence Report for the Risk of Crew Adverse Health Event Due to Altered Immune Response (from here on referred to as the 2013 Immune Evidence Report), as well as the Research Plan for this Risk that is in the current version of the Human Research Program’s (HRP) Integrated Research Plan (IRP).

  20. Population structure of Adenostoma fasciculatum in mature stands of chamise chaparral in the southern Sierra Nevada, California

    USGS Publications Warehouse

    Stohlgren, T.J.; Parsons, D.J.; Rundel, P.W.

    1984-01-01

    In the low elevation chaparral areas of Sequoia National Park, California, pure stands of chamise (Adenostoma fasciculatum) are periodically rejuvenated by fire. Mature stands showed considerable variability in density and total biomass even though a positive correlation exists between the two. Mature stands showed a preponderance of individuals in the smaller size classes (inverse-J shape distribution). Dead shrubs found in mature stands also tended to be in the smaller size classes. This relatively high mortality of small individuals is important to post-fire stand development. In addition, resprout and seedling biomass one year after fire both showed inverse-J shaped size-class structures. A positive correlation existed between the preburn basal area of a shrub and its first year resprout biomass. Shrub biomass and distance to nearest neighbor were poorly correlated. A significant correlation existed between stand density and a stand's variance-to-mean ratio, indicating a trend toward more regular spacing as density increases. Pre-burn and fire-induced mortality tended to move the stand towards a more clumped distribution. Seedlings replaced dead individuals after a fire and thus restored regular spacing.

  1. Coherence and Structural Design of Free-Standing Gratings for Atom-Wave Optics

    NASA Astrophysics Data System (ADS)

    Rooks, Michael; Tiberio, Richard; Chapman, Michael; Hammond, Troy; Smith, Edward; Lenef, Alan; Rubenstein, Richard; Pritchard, David; Adams, Scott; Ferrera, Juan; Carter, James; Smith, Henry

    1995-12-01

    Improvements in electron-beam writing techniques have allowed us to compensate for electron-beam system drift, making feasible the exposure of 800×800 µ m gratings with period as small as 0.14 µ m. Placement errors due to drift, calibration errors, and nonplanar substrates are measured with verniers. Gratings patterned with interferometric photolithography provide an absolute reference for a measure of stage nonlinearity (runout.) Simulation of fracture formation in silicon nitride films has given us a tool for the prediction of structures that will fail during fabrication, and a way of evaluating stress relief patterns in arbitrary structures. We have used two sets of simple patterns to identify the critical stress intensity factors in thin, free-standing films of nonstoichiometric silicon nitride.

  2. Damping Effect Studies for X-band Normal Conducting High Gradient Standing Wave Structures

    SciTech Connect

    Pei, S.; Li, Z.; Tantawi, S.G.; Dolgashev, V.A.; Wang, J.; /SLAC

    2009-08-03

    The Multi-TeV colliders should have the capability to accelerate low emittance beam with high rf efficiency, X-band normal conducting high gradient accelerating structure is one of the promising candidate. However, the long range transverse wake field which can cause beam emittance dilution is one of the critical issues. We examined effectiveness of dipole mode damping in three kinds of X-band, {pi}-mode standing wave structures at 11.424GHz with no detuning considered. They represent three damping schemes: damping with cylindrical iris slot, damping with choke cavity and damping with waveguide coupler. We try to reduce external Q factor below 20 in the first two dipole bands, which usually have very high (R{sub T}/Q){sub T}. The effect of damping on the acceleration mode is also discussed.

  3. Effect of Forest Structural Change on Carbon Storage in a Coastal Metasequoia glyptostroboides Stand

    PubMed Central

    Cheng, Xiangrong; Yu, Mukui; Wu, Tonggui

    2013-01-01

    Forest structural change affects the forest's growth and the carbon storage. Two treatments, thinning (30% thinning intensity) and underplanting plus thinning, are being implemented in a coastal Metasequoia glyptostroboides forest shelterbelt in Eastern China. The vegetation carbon storage significantly increased in the underplanted and thinned treatments compared with that in the unthinned treatment (P < 0.05). The soil and litterfall carbon storage in the underplanted treatment were significantly higher than those in the unthinned treatment (P < 0.05). The total forest ecosystem carbon storage in the underplanted and thinned treatments increased by 35.3% and 26.3%, respectively, compared with that in the unthinned treatment, an increase that mainly came from the growth of vegetation aboveground. Total ecosystem carbon storage showed no significant difference between the underplanted and thinned treatments (P > 0.05). The soil light fraction organic carbon (LFOC) was significantly higher at the 0–15 cm soil layer in the thinned and underplanted stands compared with that in the unthinned stand (P < 0.05). The soil respiration of the underplanted treatment was significantly higher than that of the unthinned treatment only in July (P < 0.05). This study concludes that 30% thinning and underplanting after thinning could be more favorable to carbon sequestration for M. glyptostroboides plantations in the coastal areas of Eastern China. PMID:24187525

  4. Altered resting brain function and structure in professional badminton players.

    PubMed

    Di, Xin; Zhu, Senhua; Jin, Hua; Wang, Pin; Ye, Zhuoer; Zhou, Ke; Zhuo, Yan; Rao, Hengyi

    2012-01-01

    Neuroimaging studies of professional athletic or musical training have demonstrated considerable practice-dependent plasticity in various brain structures, which may reflect distinct training demands. In the present study, structural and functional brain alterations were examined in professional badminton players and compared with healthy controls using magnetic resonance imaging (MRI) and resting-state functional MRI. Gray matter concentration (GMC) was assessed using voxel-based morphometry (VBM), and resting-brain functions were measured by amplitude of low-frequency fluctuation (ALFF) and seed-based functional connectivity. Results showed that the athlete group had greater GMC and ALFF in the right and medial cerebellar regions, respectively. The athlete group also demonstrated smaller ALFF in the left superior parietal lobule and altered functional connectivity between the left superior parietal and frontal regions. These findings indicate that badminton expertise is associated with not only plastic structural changes in terms of enlarged gray matter density in the cerebellum, but also functional alterations in fronto-parietal connectivity. Such structural and functional alterations may reflect specific experiences of badminton training and practice, including high-capacity visuo-spatial processing and hand-eye coordination in addition to refined motor skills.

  5. Post-impact alteration of the Manson impact structure

    NASA Technical Reports Server (NTRS)

    Crossey, L. J.; Mccarville, P.

    1993-01-01

    Core materials from the Manson impact site (Manson, Iowa) are examined in order to evaluate post-impact alteration processes. Diagenetic interpretation of post-impact events is based on petrologic, mineralogic, and geochemical investigation of core materials including the following: target strata, disturbed and disrupted strata, ejecta, breccias, microbreccias, and impact melt. The diagenetic study utilizes research cores obtained by the continental scientific drilling project (CSDP) at the Manson structure, as well as core and cuttings of related materials. Samples include impactites (breccias, microbreccias, and melt material), crater fill material (sedimentary clast breccias), disturbed and disrupted target rocks, and reference target material (Amoco Eisheid No. 1 materials). The study of multiple cores will permit development of a regional picture of post-impact thermal history. The specific objectives are as follows: (1) provide a detailed description of authigenic and alteration mineralogy from diverse lithologies encountered in research drill cores at the Manson impact structure, and (2) identify and relate significant post-impact mineral alteration to post-impact thermal regime (extent and duration). Results will provide mineralogical and geochemical constraints on models for post-impact processes including the following: infilling of the crater depression; cooling and hydrothermal alteration of melt rocks; and subsequent long-term, low-temperature alteration of target rocks, breccias, and melt rocks. Preliminary petrologic and x-ray diffraction examination of fracture linings and void fillings from research core M1 indicate the presence of quartz, chlorite, mixed-layer clays, gypsum/anhydrite, calcite, and minor pyrite.

  6. Electronic structure and magnetism of samarium and neodymium adatoms on free-standing graphene

    NASA Astrophysics Data System (ADS)

    Kozub, Agnieszka L.; Shick, Alexander B.; Máca, František; Kolorenč, Jindřich; Lichtenstein, Alexander I.

    2016-09-01

    The electronic structure of selected rare-earth atoms adsorbed on a free-standing graphene was investigated using methods beyond the conventional density functional theory (DFT+U , DFT+HIA, and DFT+ED). The influence of the electron correlations and the spin-orbit coupling on the magnetic properties has been examined. The DFT+U method predicts both atoms to carry local magnetic moments (spin and orbital) contrary to a nonmagnetic f6 (J =0 ) ground-state configuration of Sm in the gas phase. Application of DFT +Hubbard-I (HIA) and DFT +exact diagonalization (ED) methods cures this problem, and yields a nonmagnetic ground state with six f electrons and J =0 for the Sm adatom. Our calculations show that Nd adatom remains magnetic, with four localized f electrons and J =4.0 . These conclusions could be verified by STM and XAS experiments.

  7. Travelling and standing envelope solitons in discrete non-linear cyclic structures

    NASA Astrophysics Data System (ADS)

    Grolet, Aurelien; Hoffmann, Norbert; Thouverez, Fabrice; Schwingshackl, Christoph

    2016-12-01

    Envelope solitons are demonstrated to exist in non-linear discrete structures with cyclic symmetry. The analysis is based on the Non-Linear Schrodinger Equation for the weakly non-linear limit, and on numerical simulation of the fully non-linear equations for larger amplitudes. Envelope solitons exist for parameters in which the wave equation is focussing and they have the form of shape-conserving wave packages propagating roughly with group velocity. For the limit of maximum wave number, where the group velocity vanishes, standing wave packages result and can be linked via a bifurcation to the non-localised non-linear normal modes. Numerical applications are carried out on a simple discrete system with cyclic symmetry which can be seen as a reduced model of a bladed disk as found in turbo-machinery.

  8. A stand-alone demography and landscape structure module for Earth system models

    NASA Astrophysics Data System (ADS)

    Nieradzik, L. P.; Haverd, V.; Smith, B.; Cook, G. D.; Briggs, P.; Roxburgh, S.; Liedloff, A.; Meyer, C.; Canadell, J.

    2013-12-01

    We propose and demonstrate a new approach for the simulation of woody ecosystem stand dynamics, demography and disturbance-mediated heterogeneity suitable for continental to global applications and designed for coupling to the terrestrial ecosystem component of any earth system model (Haverd et al., 2013). The approach is encoded in a model called Populations-Order-Physiology (POP). We demonstrate the behaviour and performance of POP coupled to the Community Atmosphere Biosphere Land Exchange model (CABLE) for two contrasting applications: (i) to the Northern Australian Tropical Transect, featuring gradients in savanna vegetation cover, rainfall and fire disturbance and (ii) to a set of globally distributed forest locations coinciding with observations of forest biomass allometry. Along the Northern Australian Tropical Transect, CABLE-POP is able to simultaneously reproduce observation-based estimates of key functional and structural variables, namely gross primary production, tree foliage projective cover, basal area and maximum tree height. This application particularly demonstrates the ability of POP to quantify the contributions of drought and fire to tree mortality. Drought is manifested as an increase in mortality due to a decline in growth efficiency, while fires are treated as partial disturbance events, with tree mortality depending on tree size and fire intensity. In the application to global forests, POP is integrated with global forest data by calibrating it against paired observations of stem biomass and number density. The calibrated POP model is then coupled with CABLE and the coupled model is evaluated against leaf-stem allometry observations from forest stands ranging in age from 20 to 400 years. Results indicate that, in contrast to simulations from many global land surface models (Wolf et al., 2011), simulated biomass pools conform well with observed allometry. We conclude that POP, which can readily be coupled to the terrestrial carbon cycle

  9. Twenty-four years after theYellowstone Fires: Are postfire lodgepole pine stands converging in structure and function?

    PubMed

    Turner, Monica G; Whitby, Timothy G; Tinker, Daniel B; Romme, William H

    2016-05-01

    Disturbance and succession have long been of interest in ecology, but how landscape patterns of ecosystem structure and function evolve following large disturbances is poorly understood. After nearly 25 years, lodgepole pine (Pinus contorta var. latifolia) forests that regenerated after the 1988 Yellowstone Fires (Wyoming, USA) offer a prime opportunity to track the fate of disturbance-created heterogeneity in stand structure and function in a wilderness setting. In 2012, we resampled 72 permanent plots to ask (1) How have postfire stand structure and function changed between 11 and 24 yr postfire, and what variables explain these patterns and changes? (2) How has landscape-level (among-stand) variability in postfire stand structure and function changed between 11 and 24 yr postfire? We expected to see evidence of convergence beginning to emerge, but also that initial postfire stem density would still determine trajectories of biomass accumulation. After 24 yr, postfire lodgepole pine density remained very high (mean = 21,738 stems/ha, range = 0-344,067 stems/ha). Stem density increased in most plots between 11 and 24 yr postfire, but declined sharply where 11-yr-postfire stem density was > 72,000 stems/ha. Stems were small in high-density stands, but stand-level lodgepole pine leaf area, foliage biomass, and live aboveground biomass increased over time and with increasing stem density. After 24 yr, mean annual lodgepole pine aboveground net primary production (ANPP) was high (mean = 5 Mg · ha⁻¹ · yr⁻¹, range = 0-16.5 Mg · ha⁻¹ · yr⁻¹). Among stands, lodgepole pine ANPP increased with stem density, which explained 69% of the variation; another 8% of the variation was explained by environmental covariates. Early patterns of postfire lodgepole pine regeneration, which were contingent on prefire serotiny and fire severity, remained the dominant driver of stand structure and function. We observed mechanisms that would lead to convergence in stem density

  10. Influence of Anthropogenic Disturbances on Stand Structural Complexity in Andean Temperate Forests: Implications for Managing Key Habitat for Biodiversity.

    PubMed

    Caviedes, Julián; Ibarra, José Tomás

    2017-01-01

    Forest attributes and their abundances define the stand structural complexity available as habitat for faunal biodiversity; however, intensive anthropogenic disturbances have the potential to degrade and simplify forest stands. In this paper we develop an index of stand structural complexity and show how anthropogenic disturbances, namely fire, logging, livestock, and their combined presence, affect stand structural complexity in a southern Global Biodiversity Hotspot. From 2011 to 2013, we measured forest structural attributes as well as the presence of anthropogenic disturbances in 505 plots in the Andean zone of the La Araucanía Region, Chile. In each plot, understory density, coarse woody debris, number of snags, tree diameter at breast height, and litter depth were measured, along with signs of the presence of anthropogenic disturbances. Ninety-five percent of the plots showed signs of anthropogenic disturbance (N = 475), with the combined presence of fire, logging, and livestock being the most common disturbance (N = 222; 44% of plots). The lowest values for the index were measured in plots combining fire, logging, and livestock. Undisturbed plots and plots with the presence of relatively old fires (> 70 years) showed the highest values for the index of stand structural complexity. Our results suggest that secondary forests < 70-year post-fire event, with the presence of habitat legacies (e.g. snags and CWD), can reach a structural complexity as high as undisturbed plots. Temperate forests should be managed to retain structural attributes, including understory density (7.2 ± 2.5 # contacts), volume of CWD (22.4 ± 25.8 m3/ha), snag density (94.4 ± 71.0 stems/ha), stand basal area (61.2 ± 31.4 m2/ha), and litter depth (7.5 ± 2.7 cm). Achieving these values will increase forest structural complexity, likely benefiting a range of faunal species in South American temperate forests.

  11. Influence of Anthropogenic Disturbances on Stand Structural Complexity in Andean Temperate Forests: Implications for Managing Key Habitat for Biodiversity

    PubMed Central

    2017-01-01

    Forest attributes and their abundances define the stand structural complexity available as habitat for faunal biodiversity; however, intensive anthropogenic disturbances have the potential to degrade and simplify forest stands. In this paper we develop an index of stand structural complexity and show how anthropogenic disturbances, namely fire, logging, livestock, and their combined presence, affect stand structural complexity in a southern Global Biodiversity Hotspot. From 2011 to 2013, we measured forest structural attributes as well as the presence of anthropogenic disturbances in 505 plots in the Andean zone of the La Araucanía Region, Chile. In each plot, understory density, coarse woody debris, number of snags, tree diameter at breast height, and litter depth were measured, along with signs of the presence of anthropogenic disturbances. Ninety-five percent of the plots showed signs of anthropogenic disturbance (N = 475), with the combined presence of fire, logging, and livestock being the most common disturbance (N = 222; 44% of plots). The lowest values for the index were measured in plots combining fire, logging, and livestock. Undisturbed plots and plots with the presence of relatively old fires (> 70 years) showed the highest values for the index of stand structural complexity. Our results suggest that secondary forests < 70-year post-fire event, with the presence of habitat legacies (e.g. snags and CWD), can reach a structural complexity as high as undisturbed plots. Temperate forests should be managed to retain structural attributes, including understory density (7.2 ± 2.5 # contacts), volume of CWD (22.4 ± 25.8 m3/ha), snag density (94.4 ± 71.0 stems/ha), stand basal area (61.2 ± 31.4 m2/ha), and litter depth (7.5 ± 2.7 cm). Achieving these values will increase forest structural complexity, likely benefiting a range of faunal species in South American temperate forests. PMID:28068349

  12. Soil Microbial Community Structure and Metabolic Activity of Pinus elliottii Plantations across Different Stand Ages in a Subtropical Area

    PubMed Central

    Wu, Zeyan; Haack, Stacey Elizabeth; Lin, Wenxiong; Li, Bailian; Wu, Linkun; Fang, Changxun; Zhang, Zhixing

    2015-01-01

    Soil microbes play an essential role in the forest ecosystem as an active component. This study examined the hypothesis that soil microbial community structure and metabolic activity would vary with the increasing stand ages in long-term pure plantations of Pinus elliottii. The phospholipid fatty acids (PLFA) combined with community level physiological profiles (CLPP) method was used to assess these characteristics in the rhizospheric soils of P. elliottii. We found that the soil microbial communities were significantly different among different stand ages of P. elliottii plantations. The PLFA analysis indicated that the bacterial biomass was higher than the actinomycic and fungal biomass in all stand ages. However, the bacterial biomass decreased with the increasing stand ages, while the fungal biomass increased. The four maximum biomarker concentrations in rhizospheric soils of P. elliottii for all stand ages were 18:1ω9c, 16:1ω7c, 18:3ω6c (6,9,12) and cy19:0, representing measures of fungal and gram negative bacterial biomass. In addition, CLPP analysis revealed that the utilization rate of amino acids, polymers, phenolic acids, and carbohydrates of soil microbial community gradually decreased with increasing stand ages, though this pattern was not observed for carboxylic acids and amines. Microbial community diversity, as determined by the Simpson index, Shannon-Wiener index, Richness index and McIntosh index, significantly decreased as stand age increased. Overall, both the PLFA and CLPP illustrated that the long-term pure plantation pattern exacerbated the microecological imbalance previously described in the rhizospheric soils of P. elliottii, and markedly decreased the soil microbial community diversity and metabolic activity. Based on the correlation analysis, we concluded that the soil nutrient and C/N ratio most significantly contributed to the variation of soil microbial community structure and metabolic activity in different stand ages of P

  13. Prolonged weight-shift and altered spinal coordination during sit-to-stand in practitioners of the Alexander Technique

    PubMed Central

    Cacciatore, Timothy W; Gurfinkel, Victor S; Horak, Fay B; Day, Brian L

    2011-01-01

    The Alexander Technique (AT) is used to improve postural and movement coordination and has been reported to be clinically beneficial, however its effect on movement coordination is not well-characterized. In this study we examined the sit-to-stand (STS) movement by comparing coordination (phasing, weight-shift and spinal movement) between AT teachers (n=15) and matched control subjects (n=14). We found AT teachers had a longer weight-shift (p<0.001) and shorter momentum transfer phase (p=0.01), than control subjects. AT teachers also increased vertical foot force monotonically, rather than unweighting the feet prior to seat-off, suggesting they generate less forward momentum with hip flexors. The prolonged weight-shift of AT teachers occurred over a greater range of trunk inclination, such that their weight shifted continuously onto the feet while bringing the body mass forward. Finally, AT teachers had greatly reduced spinal bending during STS (cervical, p<0.001; thoracic, p<0.001; lumbar, p<0.05). We hypothesize that the low hip joint stiffness and adaptive axial postural tone previously reported in AT teachers underlies this novel “continuous” STS strategy by facilitating eccentric contractions during weight-shift. PMID:21782443

  14. Climatic Stress during Stand Development Alters the Sign and Magnitude of Age-Related Growth Responses in a Subtropical Mountain Pine.

    PubMed

    Ruiz-Benito, Paloma; Madrigal-González, Jaime; Young, Sarah; Mercatoris, Pierre; Cavin, Liam; Huang, Tsurng-Juhn; Chen, Jan-Chang; Jump, Alistair S

    2015-01-01

    The modification of typical age-related growth by environmental changes is poorly understood, In part because there is a lack of consensus at individual tree level regarding age-dependent growth responses to climate warming as stands develop. To increase our current understanding about how multiple drivers of environmental change can modify growth responses as trees age we used tree ring data of a mountain subtropical pine species along an altitudinal gradient covering more than 2,200 m of altitude. We applied mixed-linear models to determine how absolute and relative age-dependent growth varies depending on stand development; and to quantify the relative importance of tree age and climate on individual tree growth responses. Tree age was the most important factor for tree growth in models parameterised using data from all forest developmental stages. Contrastingly, the relationship found between tree age and growth became non-significant in models parameterised using data corresponding to mature stages. These results suggest that although absolute tree growth can continuously increase along tree size when trees reach maturity age had no effect on growth. Tree growth was strongly reduced under increased annual temperature, leading to more constant age-related growth responses. Furthermore, young trees were the most sensitive to reductions in relative growth rates, but absolute growth was strongly reduced under increased temperature in old trees. Our results help to reconcile previous contrasting findings of age-related growth responses at the individual tree level, suggesting that the sign and magnitude of age-related growth responses vary with stand development. The different responses found to climate for absolute and relative growth rates suggest that young trees are particularly vulnerable under warming climate, but reduced absolute growth in old trees could alter the species' potential as a carbon sink in the future.

  15. On the structure and topography of free-standing chemically modified graphene

    NASA Astrophysics Data System (ADS)

    Wilson, N. R.; Pandey, P. A.; Beanland, R.; Rourke, J. P.; Lupo, U.; Rowlands, G.; Römer, R. A.

    2010-12-01

    The mechanical, electrical and chemical properties of chemically modified graphene (CMG) are intrinsically linked to its structure. Here, we report on our study of the topographic structure of free-standing CMG using atomic force microscopy (AFM) and electron diffraction. We find that, unlike graphene, suspended sheets of CMG are corrugated and distorted on nanometre length scales. AFM reveals not only long-range (100 nm) distortions induced by the support, as previously observed for graphene, but also short-range corrugations with length scales down to the resolution limit of 10 nm. These corrugations are static not dynamic, and are significantly diminished on CMG supported on atomically smooth substrates. Evidence for even shorter-range distortions, down to a few nanometres or less, is found by electron diffraction of suspended CMG. Comparison of the experimental data with simulations reveals that the mean atomic displacement from the nominal lattice position is of order 10% of the carbon-carbon bond length. Taken together, these results suggest a complex structure for CMG where heterogeneous functionalization creates local strain and distortion.

  16. Estimating stand structure using discrete-return lidar: an example from low density, fire prone ponderosa pine forests

    USGS Publications Warehouse

    Hall, S. A.; Burke, I.C.; Box, D. O.; Kaufmann, M. R.; Stoker, Jason M.

    2005-01-01

    The ponderosa pine forests of the Colorado Front Range, USA, have historically been subjected to wildfires. Recent large burns have increased public interest in fire behavior and effects, and scientific interest in the carbon consequences of wildfires. Remote sensing techniques can provide spatially explicit estimates of stand structural characteristics. Some of these characteristics can be used as inputs to fire behavior models, increasing our understanding of the effect of fuels on fire behavior. Others provide estimates of carbon stocks, allowing us to quantify the carbon consequences of fire. Our objective was to use discrete-return lidar to estimate such variables, including stand height, total aboveground biomass, foliage biomass, basal area, tree density, canopy base height and canopy bulk density. We developed 39 metrics from the lidar data, and used them in limited combinations in regression models, which we fit to field estimates of the stand structural variables. We used an information–theoretic approach to select the best model for each variable, and to select the subset of lidar metrics with most predictive potential. Observed versus predicted values of stand structure variables were highly correlated, with r2 ranging from 57% to 87%. The most parsimonious linear models for the biomass structure variables, based on a restricted dataset, explained between 35% and 58% of the observed variability. Our results provide us with useful estimates of stand height, total aboveground biomass, foliage biomass and basal area. There is promise for using this sensor to estimate tree density, canopy base height and canopy bulk density, though more research is needed to generate robust relationships. We selected 14 lidar metrics that showed the most potential as predictors of stand structure. We suggest that the focus of future lidar studies should broaden to include low density forests, particularly systems where the vertical structure of the canopy is important

  17. Photosynthetic pathway alters hydraulic structure and function in woody plants.

    PubMed

    Kocacinar, Ferit; Sage, Rowan F

    2004-04-01

    Xylem structure and function is proposed to reflect an evolutionary balance between demands for efficient movement of water to the leaf canopy and resistance to cavitation during high xylem tension. Water use efficiency (WUE) affects this balance by altering the water cost of photosynthesis. Therefore species of greater WUE, such as C(4) plants, should have altered xylem properties. To evaluate this hypothesis, we assessed the hydraulic and anatomical properties of 19 C(3) and C(4) woody species from arid regions of the American west and central Asia. Specific conductivity of stem xylem ( K(s) ) was 16%-98% lower in the C(4) than C(3) shrubs from the American west. In the Asian species, the C(3) Nitraria schoberi had similar and Halimodendron halodendron higher K(s) values compared with three C(4) species. Leaf specific conductivity ( K(L); hydraulic conductivity per leaf area) was 60%-98% lower in the C(4) than C(3) species, demonstrating that the presence of the C(4) pathway alters the relationship between leaf area and the ability of the xylem to transport water. C(4) species produced similar or smaller vessels than the C(3) shrubs except in Calligonum, and most C(4) shrubs exhibited higher wood densities than the C(3) species. Together, smaller conduit size and higher wood density indicate that in most cases, the C(4) shrubs exploited higher WUE by altering xylem structure to enhance safety from cavitation. In a minority of cases, the C(4) shrubs maintained similar xylem properties but enhanced the canopy area per branch. By establishing a link between C(4) photosynthesis and xylem structure, this study indicates that other phenomena that affect WUE, such as atmospheric CO(2) variation, may also affect the evolution of wood structure and function.

  18. The evaluation of different forest structural indices to predict the stand aboveground biomass of even-aged Scotch pine (Pinus sylvestris L.) forests in Kunduz, Northern Turkey.

    PubMed

    Ercanli, İlker; Kahriman, Aydın

    2015-03-01

    We assessed the effect of stand structural diversity, including the Shannon, improved Shannon, Simpson, McIntosh, Margelef, and Berger-Parker indices, on stand aboveground biomass (AGB) and developed statistical prediction models for the stand AGB values, including stand structural diversity indices and some stand attributes. The AGB prediction model, including only stand attributes, accounted for 85 % of the total variance in AGB (R (2)) with an Akaike's information criterion (AIC) of 807.2407, Bayesian information criterion (BIC) of 809.5397, Schwarz Bayesian criterion (SBC) of 818.0426, and root mean square error (RMSE) of 38.529 Mg. After inclusion of the stand structural diversity into the model structure, considerable improvement was observed in statistical accuracy, including 97.5 % of the total variance in AGB, with an AIC of 614.1819, BIC of 617.1242, SBC of 633.0853, and RMSE of 15.8153 Mg. The predictive fitting results indicate that some indices describing the stand structural diversity can be employed as significant independent variables to predict the AGB production of the Scotch pine stand. Further, including the stand diversity indices in the AGB prediction model with the stand attributes provided important predictive contributions in estimating the total variance in AGB.

  19. Solving surface structures from normal incidence X-ray standing wave data

    NASA Astrophysics Data System (ADS)

    Basham, Mark; Bennett, Roger A.

    2007-09-01

    A program is provided to determine structural parameters of atoms in or adsorbed on surfaces by refinement of atomistic models towards experimentally determined data generated by the normal incidence X-ray standing wave (NIXSW) technique. The method employs a combination of Differential Evolution Genetic Algorithms and Steepest Descent Line Minimisations to provide a fast, reliable and user friendly tool for experimentalists to interpret complex multidimensional NIXSW data sets. Program summaryProgram title: NIXSW Planewave Solver Catalogue identifier: ADZE_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZE_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 16 874 No. of bytes in distributed program, including test data, etc.: 1 631 874 Distribution format: tar.gz Programming language: Borland C++ Builder 5 Computer: Any Windows Compatible Operating system: Windows 2000 and XP RAM: <10 MB Classification: 7.4 Nature of problem: Using NIXSW experimental data to calculate atomic positions of adsorbates. Restrictions: Data from substrates must have cubic, tetragonal or orthorhombic crystal structures i.e. with 90° between conventional cell axes. Running time: Seconds-minutes dependant on the number of plane waves and the number of atomic sites.

  20. Effects of dwarf mistletoe on stand structure of lodgepole pine forests 21-28 years post-mountain pine beetle epidemic in central Oregon.

    PubMed

    Agne, Michelle C; Shaw, David C; Woolley, Travis J; Queijeiro-Bolaños, Mónica E

    2014-01-01

    Lodgepole pine (Pinus contorta) forests are widely distributed throughout North America and are subject to mountain pine beetle (Dendroctonus ponderosae) epidemics, which have caused mortality over millions of hectares of mature trees in recent decades. Mountain pine beetle is known to influence stand structure, and has the ability to impact many forest processes. Dwarf mistletoe (Arceuthobium americanum) also influences stand structure and occurs frequently in post-mountain pine beetle epidemic lodgepole pine forests. Few studies have incorporated both disturbances simultaneously although they co-occur frequently on the landscape. The aim of this study is to investigate the stand structure of lodgepole pine forests 21-28 years after a mountain pine beetle epidemic with varying levels of dwarf mistletoe infection in the Deschutes National Forest in central Oregon. We compared stand density, stand basal area, canopy volume, proportion of the stand in dominant/codominant, intermediate, and suppressed cohorts, average height and average diameter of each cohort, across the range of dwarf mistletoe ratings to address differences in stand structure. We found strong evidence of a decrease in canopy volume, suppressed cohort height, and dominant/codominant cohort diameter with increasing stand-level dwarf mistletoe rating. There was strong evidence that as dwarf mistletoe rating increases, proportion of the stand in the dominant/codominant cohort decreases while proportion of the stand in the suppressed cohort increases. Structural differences associated with variable dwarf mistletoe severity create heterogeneity in this forest type and may have a significant influence on stand productivity and the resistance and resilience of these stands to future biotic and abiotic disturbances. Our findings show that it is imperative to incorporate dwarf mistletoe when studying stand productivity and ecosystem recovery processes in lodgepole pine forests because of its potential to

  1. Effects of Dwarf Mistletoe on Stand Structure of Lodgepole Pine Forests 21-28 Years Post-Mountain Pine Beetle Epidemic in Central Oregon

    PubMed Central

    Agne, Michelle C.; Shaw, David C.; Woolley, Travis J.; Queijeiro-Bolaños, Mónica E.

    2014-01-01

    Lodgepole pine (Pinus contorta) forests are widely distributed throughout North America and are subject to mountain pine beetle (Dendroctonus ponderosae) epidemics, which have caused mortality over millions of hectares of mature trees in recent decades. Mountain pine beetle is known to influence stand structure, and has the ability to impact many forest processes. Dwarf mistletoe (Arceuthobium americanum) also influences stand structure and occurs frequently in post-mountain pine beetle epidemic lodgepole pine forests. Few studies have incorporated both disturbances simultaneously although they co-occur frequently on the landscape. The aim of this study is to investigate the stand structure of lodgepole pine forests 21–28 years after a mountain pine beetle epidemic with varying levels of dwarf mistletoe infection in the Deschutes National Forest in central Oregon. We compared stand density, stand basal area, canopy volume, proportion of the stand in dominant/codominant, intermediate, and suppressed cohorts, average height and average diameter of each cohort, across the range of dwarf mistletoe ratings to address differences in stand structure. We found strong evidence of a decrease in canopy volume, suppressed cohort height, and dominant/codominant cohort diameter with increasing stand-level dwarf mistletoe rating. There was strong evidence that as dwarf mistletoe rating increases, proportion of the stand in the dominant/codominant cohort decreases while proportion of the stand in the suppressed cohort increases. Structural differences associated with variable dwarf mistletoe severity create heterogeneity in this forest type and may have a significant influence on stand productivity and the resistance and resilience of these stands to future biotic and abiotic disturbances. Our findings show that it is imperative to incorporate dwarf mistletoe when studying stand productivity and ecosystem recovery processes in lodgepole pine forests because of its potential to

  2. Brain structural alterations associated with young women with subthreshold depression

    PubMed Central

    Li, Haijiang; Wei, Dongtao; Sun, Jiangzhou; Chen, Qunlin; Zhang, Qinglin; Qiu, Jiang

    2015-01-01

    Neuroanatomical abnormalities in patients with major depression disorder (MDD) have been attracted great research attention. However, the structural alterations associated with subthreshold depression (StD) remain unclear and, therefore, require further investigation. In this study, 42 young women with StD, and 30 matched non-depressed controls (NCs) were identified based on two-time Beck Depression Inventory scores. Whole-brain voxel-based morphometry (VBM) and region of interest method were used to investigate altered gray matter volume (GMV) and white matter volume (WMV) among a non-clinical sample of young women with StD. VBM results indicated that young women with StD showed significantly decreased GMV in the right inferior parietal lobule than NCs; increased GMV in the amygdala, posterior cingulate cortex, and precuneus; and increased WMV in the posterior cingulate cortex and precuneus. Together, structural alterations in specific brain regions, which are known to be involved in the fronto-limbic circuits implicated in depression may precede the occurrence of depressive episodes and influence the development of MDD. PMID:25982857

  3. A highly specific coding system for structural chromosomal alterations.

    PubMed

    Martínez-Frías, M L; Martínez-Fernández, M L

    2013-04-01

    The Spanish Collaborative Study of Congenital Malformations (ECEMC, from the name in Spanish) has developed a very simple and highly specific coding system for structural chromosomal alterations. Such a coding system would be of value at present due to the dramatic increase in the diagnosis of submicroscopic chromosomal deletions and duplications through molecular techniques. In summary, our new coding system allows the characterization of: (a) the type of structural anomaly; (b) the chromosome affected; (c) if the alteration affects the short or/and the long arm, and (d) if it is a non-pure dicentric, a non-pure isochromosome, or if it affects several chromosomes. We show the distribution of 276 newborn patients with these types of chromosomal alterations using their corresponding codes according to our system. We consider that our approach may be useful not only for other registries, but also for laboratories performing these studies to store their results on case series. Therefore, the aim of this article is to describe this coding system and to offer the opportunity for this coding to be applied by others. Moreover, as this is a SYSTEM, rather than a fixed code, it can be implemented with the necessary modifications to include the specific objectives of each program.

  4. Brain structural alterations associated with young women with subthreshold depression.

    PubMed

    Li, Haijiang; Wei, Dongtao; Sun, Jiangzhou; Chen, Qunlin; Zhang, Qinglin; Qiu, Jiang

    2015-05-18

    Neuroanatomical abnormalities in patients with major depression disorder (MDD) have been attracted great research attention. However, the structural alterations associated with subthreshold depression (StD) remain unclear and, therefore, require further investigation. In this study, 42 young women with StD, and 30 matched non-depressed controls (NCs) were identified based on two-time Beck Depression Inventory scores. Whole-brain voxel-based morphometry (VBM) and region of interest method were used to investigate altered gray matter volume (GMV) and white matter volume (WMV) among a non-clinical sample of young women with StD. VBM results indicated that young women with StD showed significantly decreased GMV in the right inferior parietal lobule than NCs; increased GMV in the amygdala, posterior cingulate cortex, and precuneus; and increased WMV in the posterior cingulate cortex and precuneus. Together, structural alterations in specific brain regions, which are known to be involved in the fronto-limbic circuits implicated in depression may precede the occurrence of depressive episodes and influence the development of MDD.

  5. Altered nuclear structure in myotonic dystrophy type 1-derived fibroblasts.

    PubMed

    Rodríguez, R; Hernández-Hernández, O; Magaña, J J; González-Ramírez, R; García-López, E S; Cisneros, B

    2015-02-01

    Myotonic dystrophy type 1 (DM1) is a multisystem genetic disorder caused by a triplet nucleotide repeat expansion in the 3' untranslated region of the Dystrophia Myotonica-Protein Kinase (DMPK) gene. DMPK gene transcripts containing CUG expanded repeats accumulate in nuclear foci and ultimately cause altered splicing/gene expression of numerous secondary genes. The study of primary cell cultures derived from patients with DM1 has allowed the identification and further characterization of molecular mechanisms underlying the pathology in the natural context of the disease. In this study we show for the first time impaired nuclear structure in fibroblasts of DM1 patients. DM1-derived fibroblasts exhibited altered localization of the nuclear envelope (NE) proteins emerin and lamins A/C and B1 with concomitant increased size and altered shape of nuclei. Abnormal NE organization is more common in DM1 fibroblasts containing abundant nuclear foci, implying expression of the expanded RNA as determinant of nuclear defects. That transient expression of the DMPK 3' UTR containing 960 CTG but not with the 3' UTR lacking CTG repeats is sufficient to generate NE disruption in normal fibroblasts confirms the direct impact of mutant RNA on NE architecture. We also evidence nucleoli distortion in DM1 fibroblasts by immunostaining of the nucleolar protein fibrillarin, implying a broader effect of the mutant RNA on nuclear structure. In summary, these findings reveal that NE disruption, a hallmark of laminopathy disorders, is a novel characteristic of DM1.

  6. Changes to oak woodland stand structure and ground flora composition caused by thinning and burning

    USGS Publications Warehouse

    Kinkead, Carter O.; Kabrick, John M.; Stambaugh, Michael C.; Grabner, Keith W.

    2013-01-01

    Our objective was to quantify the cumulative effects of prescribed burning and thinning on forest stocking and species composition at a woodland restoration experiment site in the Ozark Highlands of Missouri. Our study used four treatments (burn, harvest, harvest and burn, control) on three slope position and aspect combinations (south, north, ridge) replicated in three complete blocks. Harvested stands were thinned from below to 40 percent residual stocking. Two prescribed fires were applied to both burn and harvest-burn treatment units in a 5-year period. Results reflect changes that have taken place over a 6-year period, from pretreatment conditions to 1 year after the last fire. In this period, there was a 10-percent reduction in the stocking in burned stands compared to control and a 6-percent reduction in harvested and burned stands compared to harvested stands. Compared to the control, percentage ground cover of woodland indicators was seven times greater in burned stands, six times greater in harvested stands, and 22 percent greater in harvested and burned stands. Th ere was no significant (P > 0.05) interaction between aspect and treatment on stocking or ground flora cover. Th is study indicated that silvicultural treatments do achieve various goals that are common to managers who aim to restore woodland communities.

  7. Structure and composition of altered riparian forests in an agricultural Amazonian landscape.

    PubMed

    Nagy, R Chelsea; Porder, Stephen; Neill, Christopher; Brando, Paulo; Quintino, Raimundo Mota; do Nascimento, Sebastiâo Aviz

    2015-09-01

    Deforestation and fragmentation influence the microclimate, vegetation structure, and composition of remaining patches of tropical forest. In the southern Amazon, at the frontier of cropland expansion, forests are converted and fragmented in a pattern that leaves standing riparian forests whose dimensions are mandated by the Brazilian National Forest Code. These altered riparian forests share many characteristics of well-studied upland forest fragments, but differ because they remain connected to larger areas of forest downstream, and because they may experience wetter soil conditions because reduction of forest cover in the surrounding watershed raises groundwater levels and increases stream runoff. We compared forest regeneration, structure, composition, and diversity in four areas of intact riparian forest and four areas each of narrow, medium, and wide altered riparian forests that have been surrounded by agriculture since the early 1980s. We found that seedling abundance was reduced by as much as 64% and sapling abundance was reduced by as much as 67% in altered compared to intact riparian forests. The most pronounced differences between altered and intact forest occurred near forest edges and within the narrowest sections of altered riparian forests. Woody plant species composition differed and diversity was reduced in altered forests compared to intact riparian forests. However, despite being fragmented for several decades, large woody plant biomass and carbon storage, the number of live or dead large woody plants, mortality rates, and the size distribution of woody plants did not differ significantly between altered and intact riparian forests. Thus, even in these relatively narrow forests with high edge: area ratios, we saw no evidence of the increases in mortality and declines in biomass that have been found in other tropical forest fragment studies. However, because of the changes in both species community and reduced regeneration, it is unclear how long

  8. Model independent x-ray standing wave analysis of periodic multilayer structures

    SciTech Connect

    Yakunin, S. N.; Pashaev, E. M.; Subbotin, I. A.; Makhotkin, I. A.; Kruijs, R. W. E. van de; Zoethout, E.; Chuev, M. A.; Louis, E.; Seregin, S. Yu.; Novikov, D. V.; Bijkerk, F.; Kovalchuk, M. V.

    2014-04-07

    We present a model independent approach for the analysis of X-ray fluorescence yield modulated by an X-ray standing wave (XSW), that allow a fast reconstruction of the atomic distribution function inside a sample without fitting procedure. The approach is based on the direct regularized solution of the system of linear equations that characterizes the fluorescence yield. The suggested technique was optimized for, but not limited to, the analysis of periodic layered structures where the XSW is formed under Bragg conditions. The developed approach was applied to the reconstruction of the atomic distribution function for LaN/BN multilayers with 50 periods of 43 Å thick layers. The object is especially difficult to analyze with traditional methods, as the estimated thickness of the interface region between the constituent materials is comparable to the individual layer thicknesses. However, using the suggested technique, it was possible to reconstruct width of the La atomic distribution showing that the La atoms stay localized within the LaN layers and interfaces and do not diffuse into the BN layer. The analysis of the reconstructed profiles showed that the positions of the center of the atomic distribution function can be estimated with an accuracy of 1 Å.

  9. Free-standing nanomechanical and nanophotonic structures in single-crystal diamond

    NASA Astrophysics Data System (ADS)

    Burek, Michael John

    Realizing complex three-dimensional structures in a range of material systems is critical to a variety of emerging nanotechnologies. This is particularly true of nanomechanical and nanophotonic systems, both relying on free-standing small-scale components. In the case of nanomechanics, necessary mechanical degrees of freedom require physically isolated structures, such as suspended beams, cantilevers, and membranes. For nanophotonics, elements like waveguides and photonic crystal cavities rely on light confinement provided by total internal reflection or distributed Bragg reflection, both of which require refractive index contrast between the device and surrounding medium (often air). Such suspended nanostructures are typically fabricated in a heterolayer structure, comprising of device (top) and sacrificial (middle) layers supported by a substrate (bottom), using standard surface nanomachining techniques. A selective, isotropic etch is then used to remove the sacrificial layer, resulting in free-standing devices. While high-quality, crystalline, thin film heterolayer structures are readily available for silicon (as silicon-on-insulator (SOI)) or III-V semiconductors (i.e. GaAs/AlGaAs), there remains an extensive list of materials with attractive electro-optic, piezoelectric, quantum optical, and other properties for which high quality single-crystal thin film heterolayer structures are not available. These include complex metal oxides like lithium niobate (LiNbO3), silicon-based compounds such as silicon carbide (SiC), III-V nitrides including gallium nitride (GaN), and inert single-crystals such as diamond. Diamond is especially attractive for a variety of nanoscale technologies due to its exceptional physical and chemical properties, including high mechanical hardness, stiffness, and thermal conductivity. Optically, it is transparent over a wide wavelength range (from 220 nm to the far infrared), has a high refractive index (n ~ 2.4), and is host to a vast

  10. Estimating needle litterfall in Scots pine based on photosynthesis and stand structural development

    NASA Astrophysics Data System (ADS)

    Ťupek, Boris; Kulmala, Liisa; Peltoniemi, Mikko; Lehtonen, Aleksi

    2014-05-01

    Needle leaf litter modelled with constant foliar biomass turnover rates or with constant proportion of gross primary production (GPP) may underestimate the climate change driven impacts on ecosystem carbon balance. Changing climate may have adverse effects e.g. on the timing of the needle leaf development and shedding quantity, which means litter-induced variation may become more pronounced. In this study, we investigated whether the meteorological conditions, GPP, and fraction of absorbed photosynthetically active radiation (fAPAR) can be used to predict more precisely trends and inter-annual variation of needle litterfall. Mutual dependence of these factors would imply mechanistic linkages between precise estimation of leaf litter and precise estimates of GPP, which is driven byfAPAR. The fAPAR depends on the quantity of active foliage in canopy that depends on carbon allocation to the foliage. The needle litterfall, needle cohort counts, and basic tree measurements were conducted between 1992 and 2012 on 7 Scots pine stands across Finland. Meteorological conditions for each stand were available from the nearest weather station. The GPP was estimated with a semi-empirical ecosystem model calibrated to Finnish environment given meteorological conditions and fAPAR as inputs. The fAPAR depended on the modelled foliage and measured litterfall. Litterfall was estimated as a difference between two fAPAR estimates. First based on allometric foliage models and second based on allometric foliage models scaled annually with the needle growth model. We tested our predictions against data from two FLUXNET eddy covariance sites Hyytiälä and Sodankylä located in southern and northern Finland. We found that the non-functional longevity of the needle lifespan (sum of the period when GPP is close to zero) was strongly correlated with the mean annual GPP level, and could be used for estimating the mean number of the needle cohorts. The inter-annual variation of the number of

  11. [Soil microbial community structure of monoculture and mixed plantation stands of native tree species in south subtropical China].

    PubMed

    Luo, Da; Shi, Zuo-Min; Tang, Jing-Chao; Liu, Shi-Rong; Lu, Li-Hua

    2014-09-01

    The effects of three plantation stands, Erythrophleumf ordii (EF), Pinus massoniana (PM), and their mixed plantation (MP), on soil microbial biomass and microbial community structure in south subtropical China were studied by the method of phospholipid fatty acids (PLFAs) analysis. The results showed that the amounts of microbial total PLFAs and PLFAs of each microbial group in these three plantation stand soils were significantly higher in dry season than in rainy season. In dry season, the amounts of microbial total PLFAs, bacteria PLFAs, fungi PLFAs, and actinomycetes PLFAs were the highest in the PM soil, moderate in the MP soil, and the lowest in the EF soil. But in rainy season, the amounts of microbial total PLFAs, bacteria PLFAs, fungi PLFAs, and arbuscular mycorrhizal fungi (AMF) PLFAs in the EF soil were higher than in the MP soil, and were significantly higher than in the PM soil. Principal component analysis (PCA) indicated that the variations in soil microbial community structure composition were affected by both plantation types and seasons. Redundancy analysis (RDA) of soil microbial community structure and environmental factors showed that soil temperature and moisture, pH, total nitrogen content, and ammonium nitrogen content had significant correlations with PLFA signatures. In addition, the ratio of fungi PLFAs to bacteria PLFAs in the MP soil was the highest among the three stand soils within the whole year, indicating that mixed plantation stands could facilitate the stability of the soil ecosystem.

  12. THE PERIOD RATIO FOR STANDING KINK AND SAUSAGE MODES IN SOLAR STRUCTURES WITH SIPHON FLOW. I. MAGNETIZED SLABS

    SciTech Connect

    Li Bo; Habbal, Shadia Rifai; Chen Yanjun

    2013-04-20

    In the applications of solar magneto-seismology, the ratio of the period of the fundamental mode to twice the period of its first overtone, P{sub 1}/2P{sub 2}, plays an important role. We examine how field-aligned flows affect the dispersion properties, and hence the period ratios, of standing modes supported by magnetic slabs in the solar atmosphere. We numerically solve the dispersion relations and devise a graphic means to construct standing modes. For coronal slabs, we find that the flow effects are significant for the fast kink and sausage modes alike. For the kink ones, they may reduce P{sub 1}/2P{sub 2} by up to 23% compared with the static case, and the minimum allowed P{sub 1}/2P{sub 2} can fall below the lower limit analytically derived for static slabs. For the sausage modes, while introducing the flow reduces P{sub 1}/2P{sub 2} by typically {approx}< 5% relative to the static case, it significantly increases the threshold aspect ratio only above which standing sausage modes can be supported, meaning that their detectability is restricted to even wider slabs. In the case of photospheric slabs, the flow effect is not as strong. However, standing modes are distinct from the coronal case in that standing kink modes show a P{sub 1}/2P{sub 2} that deviates from unity even for a zero-width slab, while standing sausage modes no longer suffer from a threshold aspect ratio. We conclude that transverse structuring in plasma density and flow speed should be considered in seismological applications of multiple periodicities to solar atmospheric structures.

  13. Community Structure and Standing Stock of Epibenthic Zooplankton at Five Sites in Grays Harbor, Washington

    DTIC Science & Technology

    1981-09-01

    particularly Eurytemora americana and Acartia clausi . Density and standing crop were somewhat higher at the DODJM 1473 EJITION OF I NOV 65 IS...Eurytemora americana and Acartia clausi . Density and standing crop were somewhat higher at the 0.0-m tidal elevations than at +2.1-r, except at the Marsh...Eurytemora americansa and such. coastal marine forms as Acartia clausi . However, the harpacticoid Leimia vaga, which was dominant in the 0.0-n collection at

  14. Extinction order and altered community structure rapidly disrupt ecosystem functioning.

    PubMed

    Larsen, Trond H; Williams, Neal M; Kremen, Claire

    2005-05-01

    By causing extinctions and altering community structure, anthropogenic disturbances can disrupt processes that maintain ecosystem integrity. However, the relationship between community structure and ecosystem functioning in natural systems is poorly understood. Here we show that habitat loss appeared to disrupt ecosystem functioning by affecting extinction order, species richness and abundance. We studied pollination by bees in a mosaic of agricultural and natural habitats in California and dung burial by dung beetles on recently created islands in Venezuela. We found that large-bodied bee and beetle species tended to be both most extinction-prone and most functionally efficient, contributing to rapid functional loss. Simulations confirmed that extinction order led to greater disruption of function than predicted by random species loss. Total abundance declined with richness and also appeared to contribute to loss of function. We demonstrate conceptually and empirically how the non-random response of communities to disturbance can have unexpectedly large functional consequences.

  15. Hydrogen peroxide-induced structural alterations of RNAse A.

    PubMed

    Lasch, P; Petras, T; Ullrich, O; Backmann, J; Naumann, D; Grune, T

    2001-03-23

    Proteins exposed to oxidative stress are degraded via proteolytic pathways. In the present study, we undertook a series of in vitro experiments to establish a correlation between the structural changes induced by mild oxidation of the model protein RNase A and the proteolytic rate found upon exposure of the modified protein toward the isolated 20 S proteasome. Fourier transform infrared spectroscopy was used as a structure-sensitive probe. We report here strong experimental evidence for oxidation-induced conformational rearrangements of the model protein RNase A and, at the same time, for covalent modifications of amino acid side chains. Oxidation-related conformational changes, induced by H(2)O(2) exposure of the protein may be monitored in the amide I region, which is sensitive to changes in protein secondary structure. A comparison of the time- and H(2)O(2) concentration-dependent changes in the amide I region demonstrates a high degree of similarity to spectral alterations typical for temperature-induced unfolding of RNase A. In addition, spectral parameters of amino acid side chain marker bands (Tyr, Asp) revealed evidence for covalent modifications. Proteasome digestion measurements on oxidized RNase A revealed a specific time and H(2)O(2) concentration dependence; at low initial concentration of the oxidant, the RNase A turnover rate increases with incubation time and concentration. Based on these experimental findings, a correlation between structural alterations detected upon RNase A oxidation and proteolytic rates of RNase A is established, and possible mechanisms of the proteasome recognition process of oxidatively damaged proteins are discussed.

  16. Lignin structural alterations in thermochemical pretreatments with limited delignification

    SciTech Connect

    Pu, Yunqiao; Hu, Fan; Huang, Fang; Ragauskas, Arthur J.

    2015-08-02

    Lignocellulosic biomass has a complex and rigid cell wall structure that makes biomass recalcitrant to biological and chemical degradation. Among the three major structural biopolymers (i.e., cellulose, hemicellulose and lignin) in plant cell walls, lignin is considered the most recalcitrant component and generally plays a negative role in the biochemical conversion of biomass to biofuels. The conversion of biomass to biofuels through a biochemical platform usually requires a pretreatment stage to reduce the recalcitrance. Pretreatment renders compositional and structural changes of biomass with these changes ultimately govern the efficiency of the subsequent enzymatic hydrolysis. Dilute acid, hot water, steam explosion, and ammonia fiber expansion pretreatments are among the leading thermochemical pretreatments with a limited delignification that can reduce biomass recalcitrance. Practical applications of these pretreatment are rapidly developing as illustrated by recent commercial scale cellulosic ethanol plants. While these thermochemical pretreatments generally lead to only a limited delignification and no significant change of lignin content in the pretreated biomass, the lignin transformations that occur during these pretreatments and the roles they play in recalcitrance reduction is an important research aspect. This review highlights recent advances in our understanding of lignin alterations during these limited delignification thermochemical pretreatments, with emphasis on lignin chemical structures, molecular weights, and redistributions in the pretreated biomass.

  17. Lignin structural alterations in thermochemical pretreatments with limited delignification

    DOE PAGES

    Pu, Yunqiao; Hu, Fan; Huang, Fang; ...

    2015-08-02

    Lignocellulosic biomass has a complex and rigid cell wall structure that makes biomass recalcitrant to biological and chemical degradation. Among the three major structural biopolymers (i.e., cellulose, hemicellulose and lignin) in plant cell walls, lignin is considered the most recalcitrant component and generally plays a negative role in the biochemical conversion of biomass to biofuels. The conversion of biomass to biofuels through a biochemical platform usually requires a pretreatment stage to reduce the recalcitrance. Pretreatment renders compositional and structural changes of biomass with these changes ultimately govern the efficiency of the subsequent enzymatic hydrolysis. Dilute acid, hot water, steam explosion,more » and ammonia fiber expansion pretreatments are among the leading thermochemical pretreatments with a limited delignification that can reduce biomass recalcitrance. Practical applications of these pretreatment are rapidly developing as illustrated by recent commercial scale cellulosic ethanol plants. While these thermochemical pretreatments generally lead to only a limited delignification and no significant change of lignin content in the pretreated biomass, the lignin transformations that occur during these pretreatments and the roles they play in recalcitrance reduction is an important research aspect. This review highlights recent advances in our understanding of lignin alterations during these limited delignification thermochemical pretreatments, with emphasis on lignin chemical structures, molecular weights, and redistributions in the pretreated biomass.« less

  18. Deamidation accelerates amyloid formation and alters amylin fiber structure

    PubMed Central

    Dunkelberger, Emily B.; Buchanan, Lauren E.; Marek, Peter; Cao, Ping; Raleigh, Daniel P.; Zanni, Martin T.

    2012-01-01

    Deamidation of asparagine and glutamine is the most common non-enzymatic, post-translational modification. Deamidation can influence the structure, stability, folding, and aggregation of proteins and has been proposed to play a role in amyloid formation. However there are no structural studies of the consequences of deamidation on amyloid fibers, in large part because of the difficulty of studying these materials using conventional methods. Here we examine the effects of deamidation on the kinetics of amyloid formation by amylin, the causative agent of type 2 diabetes. We find that deamidation accelerates amyloid formation and the deamidated material is able to seed amyloid formation by unmodified amylin. Using site-specific isotope labeling and two-dimensional infrared (2D IR) spectroscopy, we show that fibers formed by samples that contain deamidated polypeptide contain reduced amounts of β-sheet. Deamidation leads to disruption of the N-terminal β-sheet between Ala-8 and Ala-13, but β-sheet is still retained near Leu-16. The C-terminal sheet is disrupted near Leu-27. Analysis of potential sites of deamidation together with structural models of amylin fibers reveals that deamidation in the N-terminal β-sheet region may be the cause for the disruption of the fiber structure at both the N- and C-terminal β-sheet. Thus, deamidation is a post-translational modification that creates fibers which have an altered structure, but can still act as a template for amylin aggregation. Deamidation is very difficult to detect with standard methods used to follow amyloid formation, but isotope labeled IR spectroscopy provides a means for monitoring sample degradation and investigating the structural consequences of deamidation. PMID:22734583

  19. Linguistic and Structural Analyses of Stand-Alone Literature Reviews: Seventy-Five Years of Change

    ERIC Educational Resources Information Center

    Wright, Heidi Rachel

    2016-01-01

    The purpose of this dissertation is to offer a multifaceted overview of stand-alone literature reviews. These texts, literature reviews published unattached to research articles, have existed for centuries but remained largely unstudied by linguists. Thus, the goal of this project is to present these reviews' situational, grammatical, and…

  20. Stand-level forest structure and avian habitat: Scale dependencies in predicting occurrence in a heterogeneous forest

    USGS Publications Warehouse

    Smith, K.M.; Keeton, W.S.; Donovan, T.M.; Mitchell, B.

    2008-01-01

    We explored the role of stand-level forest structure and spatial extent of forest sampling in models of avian occurrence in northern hardwood-conifer forests for two species: black-throated blue warbler (Dendroica caerulescens) and ovenbird (Seiurus aurocapillus). We estimated site occupancy from point counts at 20 sites and characterized the forest structure at these sites at three spatial extents (0.2, 3.0, and 12.0 ha). Weight of evidence was greatest for habitat models using forest stand structure at the 12.0-ha extent and diminished only slightly at the 3.0-ha extent, a scale that was slightly larger than the average territory size of both species. Habitat models characterized at the 0.2-ha extent had low support, yet are the closest in design to those used in many of the habitat studies we reviewed. These results suggest that the role of stand-level vegetation may have been underestimated in the past, which will be of interest to land managers who use habitat models to assess the suitability of habitat for species of concern. Copyright ?? 2008 by the Society of American Foresters.

  1. Structural brain alterations can be detected early in HIV infection

    PubMed Central

    Ochs, Renee; Wu, Ying; Sammet, Christina L.; Shoukry, Alfred; Epstein, Leon G.

    2012-01-01

    Objective: Brain changes occurring early in HIV infection are not well characterized. The Chicago Early HIV Infection Study aimed to evaluate the presence and extent of structural brain alterations using quantitative MRI. Methods: Forty-three HIV and 21 control subjects were enrolled. Mean length of infection was estimated as less than 1 year based on assay results. High-resolution neuroanatomical images were acquired. Automated image analysis was used to derive measurements for total brain, ventricular volume, and for tissue classes (total and cortical gray matter, white matter, and CSF). A separate image analysis algorithm was used to calculate measurements for individual brain regions. Cognitive function was assessed by neuropsychological evaluation. Results: Reductions were quantified in total (p = 0.0547) and cortical (p = 0.0109) gray matter in the HIV group. Analysis of individual brain regions with a separate image analysis algorithm revealed consistent findings of reductions in cerebral cortex (p = 0.042) and expansion of third ventricle (p = 0.046). The early HIV group also demonstrated weaker performance on several neuropsychological tests, with the most pronounced difference in psychomotor speed (p = 0.001). Conclusions: This cross-sectional brain volumetric study indicates structural alterations early in HIV infection. The findings challenge the prevailing assumption that the brain is spared in this period. Revisiting the question of the brain's vulnerability to processes unfolding in the initial virus-host interaction and the early natural history may yield new insights into neurologic injury in HIV infection and inform neuroprotection strategies. PMID:23197750

  2. Altered osteoblast structure and function in parabolic flight

    NASA Astrophysics Data System (ADS)

    Zhong-Quan, Dai; Ying-Hui, Li; Fen, Yang; Bai, Ding; Ying-Jun, Tan

    Introduction Bone loss has a significant impact on astronauts during spaceflight being one of the main obstacles preventing interplanetary missions However the exact mechanism is not well understood In the present study we investigated the effects of acute gravitational changes generated by parabolic flight on the structure and function of osteoblasts ROS17 2 8 carried by airbus A300 Methods The alteration of microfilament cytoskeleton was observed by the Texas red conjugated Phalloidin and Alexa Fluor 488 conjugated DNase I immunofluorescence stain ALP activity and expression COL1A1 expression osteocalcin secrete which presenting the osteoblast function were detected by modified calcium and cobalt method RT-PCR and radioimmunity methods respectively Results The changed gravity induced the reorganization of microfilament cytoskeleton of osteoblast After 3 hours parabolic flight F-actin of osteoblast cytoskeleton became more thickness and directivity whereas G-actin reduced and relatively concentrated at the edge of nucleus observed by confocal fluorescence microscopy This phenomenon is identical with structure alternation observed in hypergravity but the osteoblast function decrease The excretion of osteocalcin the activity and mRNA expression of ALP decrease but the COL1A1 expression has no changes These results were similar to the changes in simulated or real microgravity Conclusion Above results suggest that short time gravity alternative change induce osteoblast structure and function

  3. Consequential secondary structure alterations and aggregation during prolonged casein glycation.

    PubMed

    Jindal, Supriya; Naeem, Aabgeena

    2013-05-01

    Non-enzymatic glycosylation (glycation) of casein is a process used not just to ameliorate the quality of dairy products but also to increase the shelf life of canned foods, including baby milk supplements. Incubation of κ-casein with reducing sugars for 15 days at physiological temperature showed the formation of a molten globule state at day 9 and 12 during fructation and glucation respectively. This state exhibits substantial secondary structure and maximum ANS binding. Later on, glycation resulted in the formation of aggregates at day 12 in presence of fructose and day 15 in presence of glucose. Aggregates possess extensive β-sheet structure as revealed by far-UV CD and FTIR. These aggregates showed altered tryptophan environment, decrease ANS binding relative to molten globule state and increase in Thioflavin T fluorescence. Aggregates were also accompanied by the accumulation of AGEs, indicative of structural damage to the protein and formation of potentially harmful species at the physiological level. Fructose was more reactive than glucose and thus caused early and significant changes in the protein. From our studies, we conclude that controlling the extent of the Maillard reaction in the food industry is essential to counter its negative effects and expand its safety spectrum.

  4. 2013 Immune Risk Standing Review Panel Research Plan Review for: The Risk of Crew Adverse Health Event Due to Altered Immune Response

    NASA Technical Reports Server (NTRS)

    Steinberg, Susan

    2014-01-01

    The 2013 Immune Risk Standing Review Panel (from here on referred to as the SRP) participated in a meeting with representatives from the Human Research Program (HRP) Human Health Countermeasures (HHC) Element and HRP management on February 3-4, 2014 in Houston, TX to review the updated Research Plan for the Risk of Crew Adverse Health Event Due to Altered Immune Response in the HRP Integrated Research Plan. The SRP is impressed with the work the immune discipline has done since the 2012 SRP review and agrees with the new wording of the Gaps, no longer questions, now statements. The SRP also likes the addition of adding targets for closing the Gaps, but it is not clear how they got to some of the interim stages (interval percentages). A major concern that the SRP has mentioned since the initial 2009 SRP meeting is that there is still not enough emphasis on the interdisciplinary aspect of the immune risk associated with other risks (i.e., nutrition, radiation, etc.). The SRP recommends that a "translational SRP" or advisory group be developed that is composed of members from all of the HRP SRPs. The SRP also thinks that the immune discipline should consider a more systems biology approach. Lastly, the SRP is concerned that the risks observed in research from low Earth orbit (LEO) missions may not accurately reflect all the risks of longer duration flight beyond LEO. Also, there does not seem to be a concern for immune responses that may occur when someone is in space longer than six months, for example, a Mars mission would take three years. The absence of disease in past and current flight scenarios does not mean the risk may not be there in future flight settings.

  5. Addition of electrophilic lipids to actin alters filament structure

    SciTech Connect

    Gayarre, Javier; Sanchez, David; Sanchez-Gomez, Francisco J.; Terron, Maria C.; Llorca, Oscar; Perez-Sala, Dolores . E-mail: dperezsala@cib.csic.es

    2006-11-03

    Pathophysiological processes associated with oxidative stress lead to the generation of reactive lipid species. Among them, lipids bearing unsaturated aldehyde or ketone moieties can form covalent adducts with cysteine residues and modulate protein function. Through proteomic techniques we have identified actin as a target for the addition of biotinylated analogs of the cyclopentenone prostaglandins 15-deoxy-{delta}{sup 12,14}-PGJ{sub 2} (15d-PGJ{sub 2}) and PGA{sub 1} in NIH-3T3 fibroblasts. This modification could take place in vitro and mapped to the protein C-terminal end. Other electrophilic lipids, like the isoprostane 8-iso-PGA{sub 1} and 4-hydroxy-2-nonenal, also bound to actin. The C-terminal region of actin is important for monomer-monomer interactions and polymerization. Electron microscopy showed that actin treated with 15d-PGJ{sub 2} or 4-hydroxy-2-nonenal formed filaments which were less abundant and displayed shorter length and altered structure. Streptavidin-gold staining allowed mapping of biotinylated 15d-PGJ{sub 2} at sites of filament disruption. These results shed light on the structural implications of actin modification by lipid electrophiles.

  6. Roberts syndrome: New evidence supporting an altered metaphase chromatin structure

    SciTech Connect

    Shang, X.M.; Schultz, E.L.; Tonk, V.

    1994-09-01

    Roberts syndrome is a rare autosomal recessive disease clinically manifested in the newborn by mental and growth retardation, tetraphocomelia, and a variety of craniofacial abnormalities. Cell lines derived from RS patients exhibit subtle mutagen hypersensitivity and cytogenetic abnormalities which include random chromosome loss and the splaying of heterochromatic chromosomal regions. The latter, typically detected on C-banded metaphases, has been used prenatally for the diagnosis of RS. To gain further insights into the RS defect, we have examined a number of parameters related to metaphase chromatin structure, with observations as follows. (1) The heterochromatic splaying associated with RS was found to be visible on G- as well as C-banded metaphases. (2) Quantitative evaluations using fluorescence image analysis revealed that RS metaphase chromosomes bind DAPI less efficiently than chromosomes from normal cells. (3) Denaturation of chromosomal DNA with either a C-banding procedure or 70% formamide at 70{degree}C each produced an aberrant hybridization pattern on RS chromosomes in FISH experiments employing biotinylated total human DNA as probe. (4) RS cells exhibited a >3-fold increase in sensitivity to VM-26, a potent inhibitor of topoisomerase II. Collectively, the aforementioned data support the notion that the primary defect in RS results in an altered metaphase chromatin structure.

  7. Addition of electrophilic lipids to actin alters filament structure.

    PubMed

    Gayarre, Javier; Sánchez, David; Sánchez-Gómez, Francisco J; Terrón, María C; Llorca, Oscar; Pérez-Sala, Dolores

    2006-11-03

    Pathophysiological processes associated with oxidative stress lead to the generation of reactive lipid species. Among them, lipids bearing unsaturated aldehyde or ketone moieties can form covalent adducts with cysteine residues and modulate protein function. Through proteomic techniques we have identified actin as a target for the addition of biotinylated analogs of the cyclopentenone prostaglandins 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)) and PGA(1) in NIH-3T3 fibroblasts. This modification could take place in vitro and mapped to the protein C-terminal end. Other electrophilic lipids, like the isoprostane 8-iso-PGA(1) and 4-hydroxy-2-nonenal, also bound to actin. The C-terminal region of actin is important for monomer-monomer interactions and polymerization. Electron microscopy showed that actin treated with 15d-PGJ(2) or 4-hydroxy-2-nonenal formed filaments which were less abundant and displayed shorter length and altered structure. Streptavidin-gold staining allowed mapping of biotinylated 15d-PGJ(2) at sites of filament disruption. These results shed light on the structural implications of actin modification by lipid electrophiles.

  8. Postimpact hydrothermal alteration of the Manson impact structure

    NASA Astrophysics Data System (ADS)

    McCarville, P.; Crossey, L. J.

    1994-07-01

    Core materials from the Manson impact structure (MIS), Manson, Iowa, are examined in order to evaluate postimpact alteration processes. Interpretation of the high-temperature postimpact hydrothermal system is based on mineralogic investigation. MIS rocks from the M1, M7, M8, and M10 cores obtained by the continental scientific drilling project (CSDP) in 1991 and 1992 are used in this study. All lithologies, including the sedimentary clast breccias (SCB), crystalline clast breccias (CCB), and central peak crystalline peaks (CPC), have been described previously. Emphasis is placed on fluid conduits that cross-cut all these lithologies. Analytical techniques include petrography, Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD). The minerals are grouped according to their temperatures of occurrence in modern geothermal systems. The highest temperatures in the MIS are represented by a garnet and ferroactinolite assemblage (assemblage I). Assemblage II contains epidote, prehnite, and wollastonite, which represents slightly lower temperatures in the system. The existence of laumontite, quartz, and adularia defines a third assemblage. Assemblage IV is defined by calcite and clays, and represents the lowest alteration temperature at the MIS. These temperature-sensitive calc-silicates serve to constrain the fluid temperatures of the MIS hydrothermal system. Assemblage I suggests that the system reached over 300 C. Successively decreasing temperatures through time, approaching ambient temperatures, are suggested by the lower temperature assemblages II, III, and IV. A model for the cooling history of the MIS is reported elsewhere. The distribution of these high-temperature minerals points to the central uplift, not the melt sheet, as being the heat source for the system.

  9. Influence of nutrient availability, stand age, and canopy structure on isoprene flux in a Eucalyptus saligna experimental forest

    NASA Astrophysics Data System (ADS)

    Funk, Jennifer L.; Giardina, Christian P.; Knohl, Alexander; Lerdau, Manuel T.

    2006-06-01

    Eucalyptus plantations occupy approximately 10 million ha of land in the tropics and, increasingly, afforestation and reforestation projects are relying on this genus to provide rapid occupation of degraded sites, large quantities of high-quality wood products, and high rates of carbon sequestration. Members of the genus Eucalyptus are also very high emitters of isoprene, the dominant volatile organic compound emitted by trees in tropical ecosystems, which significantly influences the oxidative capacity of the atmosphere. While fertilization growth response of these trees has been intensively studied, little is known about how fertilization and tree age alter isoprene production from plantations of these trees. Here we examined the effects of fertilization and tree age on leaf-level isoprene flux from 2- and 6-year-old trees in a Eucalyptus saligna experimental forest in Hawaii. Leaf-level emission at a given canopy height did not differ between fertilized and unfertilized 6-year-old trees likely because leaf nitrogen content did not vary with fertilization. Across treatments, however, the standardized emission rate of isoprene (emission at a standard light and temperature) followed patterns of leaf N content and declined with canopy depth. Although leaf nitrogen content was similar between 2-year and 6-year fertilized trees, leaf-level emission rates declined with stand age. Surprisingly, despite differences in stand leaf area and leaf area distribution, modeled canopy-level isoprene flux was similar across stands varying in fertilization and tree age. Model results suggest that leaf area index was high enough in all treatments to absorb most of the light penetrating the canopy, leading to similar canopy flux rates despite the very different sized canopies.

  10. Phylogenetic structure of ectomycorrhizal fungal communities of western hemlock changes with forest age and stand type.

    PubMed

    Lim, SeaRa; Berbee, Mary L

    2013-08-01

    On Vancouver Island, British Columbia, fertilization with nitrogen (N) and phosphorus (P) following clearcutting increases growth of western hemlock. To explore whether fertilization also resulted in ectomycorrhizal fungal communities that were more or less similar to neighboring unlogged stands, we sampled roots from western hemlock from three replicate plots from each of five different, well-characterized, forest stand types that differed in site type, and in logging and fertilization history. We harvested four samples of 100 ectomycorrhizal root tips from each plot, a total of 60 samples per stand type. From each sample, we analyzed fungal ribosomal internal transcribed spacers and 28S DNA, sequencing 15-29 clones per sample and 60-116 clones per plot. We detected 147 fungal operational taxonomic units among a total of 1435 sequences. Craterellus tubaeformis was frequently present and resulted in a pattern of phylogenetic overdispersion in the fungal communities. Fungal species composition was strongly correlated with foliar nitrogen concentration. However, other site quality factors were also important because the fertilized regenerating hemlock and mature hemlock-amabilis fir forests had similar foliar nitrogen content but little overlap in fungal species. Compared with unfertilized regenerating forests, fungal communities in N + P-fertilized regenerating forests had significantly more species overlap with old growth forests. However, the fungal communities of all regenerating forest were similar to one another and all differed significantly from older forests. By correlating fungal clades with habitats, this research improves understanding of how forest management can contribute to maintaining diverse ectomycorrhizal fungal communities across a landscape.

  11. Edaphic, salinity, and stand structural trends in chronosequences of native and non-native dominated riparian forests along the Colorado River, USA

    USGS Publications Warehouse

    Merritt, David M.; Shafroth, Patrick B.

    2012-01-01

    Tamarix spp. are introduced shrubs that have become among the most abundant woody plants growing along western North American rivers. We sought to empirically test the long-held belief that Tamarix actively displaces native species through elevating soil salinity via salt exudation. We measured chemical and physical attributes of soils (e.g., salinity, major cations and anions, texture), litter cover and depth, and stand structure along chronosequences dominated by Tamarix and those dominated by native riparian species (Populus or Salix) along the upper and lower Colorado River in Colorado and Arizona/California, USA. We tested four hypotheses: (1) the rate of salt accumulation in soils is faster in Tamarix-dominated stands than stands dominated by native species, (2) the concentration of salts in the soil is higher in mature stands dominated by Tamarix compared to native stands, (3) soil salinity is a function of Tamarix abundance, and (4) available nutrients are more concentrated in native-dominated stands compared to Tamarix-dominated stands. We found that salt concentration increases at a faster rate in Tamarix-dominated stands along the relatively free-flowing upper Colorado but not along the heavily-regulated lower Colorado. Concentrations of ions that are known to be preferentially exuded by Tamarix (e.g., B, Na, and Cl) were higher in Tamarix stands than in native stands. Soil salt concentrations in older Tamarix stands along the upper Colorado were sufficiently high to inhibit germination, establishment, or growth of some native species. On the lower Colorado, salinity was very high in all stands and is likely due to factors associated with floodplain development and the hydrologic effects of river regulation, such as reduced overbank flooding, evaporation of shallow ground water, higher salt concentrations in surface and ground water due to agricultural practices, and higher salt concentrations in fine-textured sediments derived from naturally saline

  12. Altered structural connectivity and trait anhedonia in patients with schizophrenia.

    PubMed

    Lee, Jung Suk; Han, Kiwan; Lee, Seung-Koo; Seok, Jeong-Ho; Kim, Jae-Jin

    2014-09-05

    This study tested association between anhedonia scores and white matter integrity in order to investigate the neural basis of trait anhedonia in schizophrenia. A total of 31 patients with schizophrenia and 33 healthy controls underwent diffusion weighted imaging and scoring of trait anhedonia using the Physical Anhedonia Scale. Using tract-based spatial statistics, we found that fractional anisotropy values of some white matter regions were differently correlated with Physical Anhedonia Scale scores between the two groups. The white matter regions that were more significantly correlated with trait anhedonia in patients than in controls included the left side of the cingulum, splenium of the corpus callosum, inferior longitudinal fasciculus, superior longitudinal fasciculus I and II, anterior thalamic radiation, and optic radiation. Of these regions, fractional anisotropy values in the cingulum and superior longitudinal fasciculus II were positively correlated with trait anhedonia in patients with schizophrenia. These findings suggest that alterations in structural connectivity within large-scale brain networks, including the default mode and central executive networks, may contribute to the development of trait anhedonia in patients with schizophrenia.

  13. Alteration of Golgi Structure by Stress: A Link to Neurodegeneration?

    PubMed Central

    Alvarez-Miranda, Eduardo A.; Sinnl, Markus; Farhan, Hesso

    2015-01-01

    The Golgi apparatus is well-known for its role as a sorting station in the secretory pathway as well as for its role in regulating post-translational protein modification. Another role for the Golgi is the regulation of cellular signaling by spatially regulating kinases, phosphatases, and GTPases. All these roles make it clear that the Golgi is a central regulator of cellular homeostasis. The response to stress and the initiation of adaptive responses to cope with it are fundamental abilities of all living cells. It was shown previously that the Golgi undergoes structural rearrangements under various stress conditions such as oxidative or osmotic stress. Neurodegenerative diseases are also frequently associated with alterations of Golgi morphology and many stress factors have been described to play an etiopathological role in neurodegeneration. It is however unclear whether the stress-Golgi connection plays a role in neurodegenerative diseases. Using a combination of bioinformatics modeling and literature mining, we will investigate evidence for such a tripartite link and we ask whether stress-induced Golgi arrangements are cause or consequence in neurodegeneration. PMID:26617486

  14. Incidence, size and spatial structure of clones in second-growth stands of coast redwood, Sequoia sempervirens (Cupressaceae).

    PubMed

    Douhovnikoff, Vladimir; Cheng, Adelaide M; Dodd, Richard S

    2004-07-01

    The ecology and evolutionary potential of coast redwood (Sequoia sempervirens) is significantly influenced by the important role clonal spread plays in its reproduction and site persistence. In nine second-growth stands, amplified fragment length polymorphisms (AFLPs) were used to identify redwood clonal architecture. Clones (multistem genets) dominated sites by representing an average of 70% of stems measured, ranging in size from two to 20 stems. As a result, a relatively small number of genets can monopolize a disproportionate amount of site resources, are more likely to persist over time, and have greater on-site genetic representation. Clones were not limited to fairy-ring structures, but consisted of a wide range of shapes including concentric rings, ring chains, disjunct, and linear structures. Between-ramet distances of up to 40 m were measured, indicating that clonal reproduction is not limited to basal stump resprouting. Clonal structure in second-growth stands was similar to earlier reports from old growth, emphasizing the importance of site persistence and long-term, gradual site development. Smaller ramet numbers per genet in old growth is probably due to local within-genet self thinning. Management and conservation of redwoods will benefit from a better understanding of the dynamics and structure of clonal spread in these forests.

  15. Free-standing Si/SiO II superlattices: fabrication procedure and optical, structural, and light-emitting properties

    NASA Astrophysics Data System (ADS)

    Novikov, S.; Sinkkonen, J.; Khriachtchev, L.; Räsänen, M.; Sitnikova, A.

    2006-04-01

    The Si/SiO II superlattices were prepared by a molecular beam deposition method, high temperature furnace annealing (1100 °C), and back-side Si wafer etching in tetramethyl ammonium solution. Transmission electron microscopy and Raman spectroscopy show that the layered structure is not preserved during high temperature treatment. The etching of the substrate increases photoluminescence of the Si/SiO II material. Optical waveguiding was realized for the free-standing sample demonstrating its reasonable optical quality and providing the optical parameters.

  16. Structure and energetics of standing eddies in the winter Northern Hemisphere simulated by the NCAR Community Climate Model and the GLA Climate Model

    NASA Technical Reports Server (NTRS)

    Lee, Yen-Huei; Chen, Tsing-Chang

    1986-01-01

    The structure and maintenance of standing eddies in the NCAR Community Climate Model and the Goddard Laboratory for Atmospheres Climate Model are examined. The energy equations and data used in the study, and the differences between the two GCMs are discussed. The three-dimensional structure (height, temperature, and vertical velocity) and potential and kinetic energies and thermal and dynamic interactions of the standing eddies are described.

  17. Alterations in chromatin structure during early sea urchin embryogenesis.

    PubMed Central

    Savić, A; Richman, P; Williamson, P; Poccia, D

    1981-01-01

    Sea urchin sperm before fertilization possess the longest nucleosome repeat length yet determined for any chromatin. By the time the fertilized egg gives rise to a blastula or gastrula embryo, the chromatin has a considerably shorter repeat length and, in addition, a sequence of different histone variants of H1, H2A, and H2B has appeared. We have investigated the relationship between these variations in histone composition and concomitant alterations in chromatin structure during the earliest stages of embryogenesis in two species of sea urchin. In contrast to the long repeat distance in sperm, chromatin loaded with cleavage stage histones has a much smaller repeat. Later stages containing predominantly alpha histones display an intermediate spacing. More detailed analysis of the events in the first cell cycle was carried out with polyspermically fertilized eggs. During the first 30 min after fertilization, in which sperm-specific H1 is completely replaced by cleavage-stage H1, the male pronuclear repeat remains unchanged. The decrease toward the repeat length of cleavage stages begins at about the time of DNA synthesis. Higher degrees of polyspermy extend the length of the cell cycle, including the duration of S phase and the length of time to reach the first chromosome condensation. At these higher degrees of polyspermy, the decrease in repeat length is also slowed. We conclude that the adjustment of the arrangement of nucleosomes in embryonic chromatin from that found in sperm can occur within the first cell cycle and that its timing is cell-cycle dependent. The adjustment is separable from a corresponding change in H1 composition. Images PMID:6943576

  18. The electronic structure of quasi-free-standing germanene on monolayer MX (M = Ga, In; X = S, Se, Te).

    PubMed

    Ni, Zeyuan; Minamitani, Emi; Ando, Yasunobu; Watanabe, Satoshi

    2015-07-15

    For the first time by using the ab initio density functional theory, the stability and electronic structures of germanene on monolayer GaS, GaSe, GaTe and InSe have been investigated. Germanene preserves its buckled-honeycomb structure on all the studied substrates similar to the free-standing case. Moreover, germanene stays neutral and preserves its Dirac-cone-like band structure on monolayer GaTe and InSe. In these two cases, a bandgap of 0.14-0.16 eV opens at the Dirac point of germanene, while the effective masses remain as small as 0.05-0.06 times the free-electron mass. The estimated carrier mobility is up to 2.2 × 10(5) cm(2) V(-1) s(-1). These features show that monolayer GaTe and InSe are promising as substrates for germanene devices.

  19. Spatial Scales of Genetic Structure in Free-Standing and Strangler Figs (Ficus, Moraceae) Inhabiting Neotropical Forests

    PubMed Central

    Heer, Katrin; Albrecht, Larissa; García-Villacorta, Roosevelt; Staeps, Felix C.; Herre, Edward Allen; Dick, Christopher W.

    2015-01-01

    Wind-borne pollinating wasps (Agaonidae) can transport fig (Ficus sp., Moraceae) pollen over enormous distances (> 100 km). Because of their extensive breeding areas, Neotropical figs are expected to exhibit weak patterns of genetic structure at local and regional scales. We evaluated genetic structure at the regional to continental scale (Panama, Costa Rica, and Peru) for the free-standing fig species Ficus insipida. Genetic differentiation was detected only at distances > 300 km (Jost´s Dest = 0.68 ± 0.07 & FST = 0.30 ± 0.03 between Mesoamerican and Amazonian sites) and evidence for phylogeographic structure (RST>>permuted RST) was only significant in comparisons between Central and South America. Further, we assessed local scale spatial genetic structure (SGS, d ≤ 8 km) in Panama and developed an agent-based model parameterized with data from F. insipida to estimate minimum pollination distances, which determine the contribution of pollen dispersal on SGS. The local scale data for F. insipida was compared to SGS data collected for an additional free-standing fig, F. yoponensis (subgenus Pharmacosycea), and two species of strangler figs, F. citrifolia and F. obtusifolia (subgenus Urostigma) sampled in Panama. All four species displayed significant SGS (mean Sp = 0.014 ± 0.012). Model simulations indicated that most pollination events likely occur at distances > > 1 km, largely ruling out spatially limited pollen dispersal as the determinant of SGS in F. insipida and, by extension, the other fig species. Our results are consistent with the view that Ficus develops fine-scale SGS primarily as a result of localized seed dispersal and/or clumped seedling establishment despite extensive long-distance pollen dispersal. We discuss several ecological and life history factors that could have species- or subgenus-specific impacts on the genetic structure of Neotropical figs. PMID:26226482

  20. Spatial Scales of Genetic Structure in Free-Standing and Strangler Figs (Ficus, Moraceae) Inhabiting Neotropical Forests.

    PubMed

    Heer, Katrin; Kalko, Elisabeth K V; Albrecht, Larissa; García-Villacorta, Roosevelt; Staeps, Felix C; Herre, Edward Allen; Dick, Christopher W

    2015-01-01

    Wind-borne pollinating wasps (Agaonidae) can transport fig (Ficus sp., Moraceae) pollen over enormous distances (> 100 km). Because of their extensive breeding areas, Neotropical figs are expected to exhibit weak patterns of genetic structure at local and regional scales. We evaluated genetic structure at the regional to continental scale (Panama, Costa Rica, and Peru) for the free-standing fig species Ficus insipida. Genetic differentiation was detected only at distances > 300 km (Jost´s Dest = 0.68 ± 0.07 & FST = 0.30 ± 0.03 between Mesoamerican and Amazonian sites) and evidence for phylogeographic structure (RST>permuted RST) was only significant in comparisons between Central and South America. Further, we assessed local scale spatial genetic structure (SGS, d ≤ 8 km) in Panama and developed an agent-based model parameterized with data from F. insipida to estimate minimum pollination distances, which determine the contribution of pollen dispersal on SGS. The local scale data for F. insipida was compared to SGS data collected for an additional free-standing fig, F. yoponensis (subgenus Pharmacosycea), and two species of strangler figs, F. citrifolia and F. obtusifolia (subgenus Urostigma) sampled in Panama. All four species displayed significant SGS (mean Sp = 0.014 ± 0.012). Model simulations indicated that most pollination events likely occur at distances > > 1 km, largely ruling out spatially limited pollen dispersal as the determinant of SGS in F. insipida and, by extension, the other fig species. Our results are consistent with the view that Ficus develops fine-scale SGS primarily as a result of localized seed dispersal and/or clumped seedling establishment despite extensive long-distance pollen dispersal. We discuss several ecological and life history factors that could have species- or subgenus-specific impacts on the genetic structure of Neotropical figs.

  1. Take a Stand for Standing

    ERIC Educational Resources Information Center

    Labandz, Stephenie

    2010-01-01

    As a school-based physical therapist, the author sees children with a wide variety of diagnoses affecting their mobility and motor function. Supported standing is an important part of the routines of those who are unable to stand independently due to issues affecting the neuromuscular system. Being eye-to-eye with their peers and interacting with…

  2. [Effects of stand structure regulation on soil labile organic carbon in Pinus elliottii plantation].

    PubMed

    Tan, Gui-Xia; Liu, Yuan-Qiu; Li, Lian-Lian; Liu, Wu; Zan, Yu-Ting; Huo, Bing-Nan; He, Mu-Jiao

    2014-05-01

    Taking 21-year-old Pinus elliottii pure plantation as the control, effects of enrichment planting with broadleaf trees (Liquidambar fornosana) after thinning the conifer trees (P. elliottii) on soil labile organic carbon of different plantations, including 3-year-old, 6-year-old, 9-year-old P. elliottii and 21-year-old P. elliottii-L. fornosana mixed plantations, were investigated. The results showed that the contents of soil dissolved organic carbon (DOC), readily oxidizable organic carbon (ROC), and microbial biomass carbon (MBC) significantly increased in the 6-year-old and 9-year-old plantations compared with those in the 21-year-old P. elliottii pure plantation. Soil labile organic carbon contents in the 21-year-old P. elliottii-L. fornosana mixed plantation increased significantly than those in 3-year-old, 6-year-old, 9-year-old stands, and the DOC, ROC and MBC contents increased by 113.1%, 53.3% and 54.6%, respectively, compared with those in the 21-year-old P. elliottii pure plantation. The results suggested that replanting with broadleaf trees are an effective measure to improve the soil ecological function in pure P. elliottii plantation.

  3. 18 CFR 1304.211 - Change in ownership of grandfathered structures or alterations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... grandfathered structures or alterations. (a) When ownership of a permitted structure or other shoreline..., upon application to TVA for a permit, continue to use existing permitted docks and other shoreline... standards existing shoreline alterations constructed and maintained in accordance with the standards...

  4. Perinatal Risk Factors Altering Regional Brain Structure in the Preterm Infant

    ERIC Educational Resources Information Center

    Thompson, Deanne K.; Warfield, Simon K.; Carlin, John B.; Pavlovic, Masa; Wang, Hong X.; Bear, Merilyn; Kean, Michael J.; Doyle, Lex W.; Egan, Gary F.; Inder, Terrie E.

    2007-01-01

    Neuroanatomical structure appears to be altered in preterm infants, but there has been little insight into the major perinatal risk factors associated with regional cerebral structural alterations. MR images were taken to quantitatively compare regional brain tissue volumes between term and preterm infants and to investigate associations between…

  5. Period ratios for standing kink and sausage modes in magnetized structures with siphon flow on the Sun

    NASA Astrophysics Data System (ADS)

    Yu, Hui; Chen, Shao-Xia; Li, Bo; Xia, Li-Dong

    2016-06-01

    Standing oscillations with multiple periods have been found in a number of atmospheric structures on the Sun. The ratio of the period of the fundamental to twice the one of its first overtone, P 1/2P 2, is important in applications of solar magneto-seismology. We examine how field-aligned flows impact P 1/2P 2 of standing modes in solar magnetic cylinders. For coronal loops, the flow effects are significant for both fast kink and sausage modes. For kink modes, they reduce P 1/2P 2 by up to 17% relative to the static case even when the density contrast between the loop and its surroundings approaches infinity. For sausage modes, the reduction in P 1/2P 2 due to flow is typically ≲ 5.5% compared with the static case. However, the threshold aspect ratio, only above which can trapped sausage modes be supported, may increase dramatically with the flow magnitude. For photospheric tubes, the flow effect on P 1/2P 2 is not as strong. However, when applied to sausage modes, introducing field-aligned flows offers more possibilities in interpreting the multiple periods that have recently been measured. We conclude that field-aligned flows should be taken into account to help better understand what causes the departure of P 1/2P 2 from unity.

  6. FEA modeling of CMUT with membrane stand-off structures to enable selectable frequency-mode operation.

    PubMed

    Eames, Matthew D C; Reck, Theodore J; Kilroy, Joseph P; Hossack, John A

    2011-12-01

    A selectable, dual-frequency, capacitive micro- machined ultrasonic transducer (CMUT) designed for both high-frequency imaging and low-frequency therapeutic effect is presented. A validated finite element analysis (FEA) CMUT model was used to examine the performance of the proposed dual-frequency transducer. CMUT device simulations were used to design a hybrid device incorporating stand-off structures that divide a large, low-frequency membrane into smaller, high-frequency sub-membranes when the membrane is partially collapsed so that the stand-offs contact the substrate. In low-frequency operation, simulations indicated that the peak negative pressure achieved by the hybrid device, when biased by 30.0 VDC and excited by a 2-MHz signal with 30.0 V amplitude, exceeded 190 kPa, which is sufficient for microbubble rupture. Low-frequency mode bandwidth was 93% at a center frequency of 2.1 MHz. In the high-frequency mode of operation, the device was excited by 175 Vdc and 87.5 Vac, which generated a peak negative pressure of 247 kPa. Device center frequency was 44.1 MHz with a - 6-dB fractional bandwidth of 42%.

  7. Correlations of Flow Structure and Particle Deposition with Structural Alterations in Severe Asthmatic Lungs

    NASA Astrophysics Data System (ADS)

    Choi, Sanghun; Miyawaki, Shinjiro; Choi, Jiwoong; Hoffman, Eric A.; Wenzel, Sally; Lin, Ching-Long

    2014-11-01

    Severe asthmatics are characterized by alterations of bifurcation angle, hydraulic diameter, circularity of the airways, and local shift of air-volume functional change. The characteristics altered against healthy human subjects can affect flow structure and particle deposition. A large-eddy-simulation (LES) model for transitional and turbulent flows is utilized to study flow characteristics and particle deposition with representative healthy and severe asthmatic lungs. For the subject-specific boundary condition, local air-volume changes are derived with two computed tomography images at inspiration and expiration. Particle transport simulations are performed on LES-predicted flow fields. In severe asthmatics, the elevated air-volume changes of apical lung regions affect the increased particle distribution toward upper lobes, especially for small particles. The constricted airways are significantly correlated with high wall shear stress, leading to the increased pressure drop and particle deposition. The structural alterations of bifurcation angle, circularity and hydraulic diameter in severe asthmatics are associated with the increase of particle deposition, wall shear stress and wall thickness. NIH Grants: U01-HL114494, R01-HL094315 and S10-RR022421. Computer time: XSEDE.

  8. Forest structure, stand composition, and climate-growth response in montane forests of Jiuzhaigou National Nature Reserve, China.

    PubMed

    Schwartz, Mark W; Dolanc, Christopher R; Gao, Hui; Strauss, Sharon Y; Schwartz, Ari C; Williams, John N; Tang, Ya

    2013-01-01

    Montane forests of western China provide an opportunity to establish baseline studies for climate change. The region is being impacted by climate change, air pollution, and significant human impacts from tourism. We analyzed forest stand structure and climate-growth relationships from Jiuzhaigou National Nature Reserve in northwestern Sichuan province, along the eastern edge of the Tibetan plateau. We conducted a survey to characterize forest stand diversity and structure in plots occurring between 2050 and 3350 m in elevation. We also evaluated seedling and sapling recruitment and tree-ring data from four conifer species to assess: 1) whether the forest appears in transition toward increased hardwood composition; 2) if conifers appear stressed by recent climate change relative to hardwoods; and 3) how growth of four dominant species responds to recent climate. Our study is complicated by clear evidence of 20(th) century timber extraction. Focusing on regions lacking evidence of logging, we found a diverse suite of conifers (Pinus, Abies, Juniperus, Picea, and Larix) strongly dominate the forest overstory. We found population size structures for most conifer tree species to be consistent with self-replacement and not providing evidence of shifting composition toward hardwoods. Climate-growth analyses indicate increased growth with cool temperatures in summer and fall. Warmer temperatures during the growing season could negatively impact conifer growth, indicating possible seasonal climate water deficit as a constraint on growth. In contrast, however, we found little relationship to seasonal precipitation. Projected warming does not yet have a discernible signal on trends in tree growth rates, but slower growth with warmer growing season climates suggests reduced potential future forest growth.

  9. Status of High Power Tests of Normal Conducting Single-Cell Standing Wave Structures

    SciTech Connect

    Dolgashev, Valery; Tantawi, Sami; Yeremian, Anahid; Higashi, Yasuo; Spataro, Bruno; /INFN, Rome

    2012-06-25

    Our experiments are directed toward the understanding of the physics of rf breakdown in systems that can be used to accelerate electron beams at {approx}11.4 GHz. The structure geometries have apertures, stored energy per cell, and rf pulse duration close to that of the NLC or CLIC. The breakdown rate is the main parameter that we use to compare rf breakdown behavior for different structures at a given set of rf pulse parameters (pulse shape and peak power) at 60 Hz repetition rate. In our experiments, the typical range of the breakdown rate is from one per few hours to {approx}100 per hour. To date we have tested 29 structures. We consistently found that after the initial conditioning, the behavior of the breakdown rate is reproducible for structures of the same geometry and material, and the breakdown rate dependence on peak magnetic fields is stronger than on peak surface electric fields for structures of different geometries. Below we report the main results from tests of seven structures made from hard copper, soft copper alloys and hard-copper alloys. Additional details on these and other structures will be discussed in future publications.

  10. NEO Test Stand Analysis

    NASA Technical Reports Server (NTRS)

    Pike, Cody J.

    2015-01-01

    A project within SwampWorks is building a test stand to hold regolith to study how dust is ejected when exposed to the hot exhaust plume of a rocket engine. The test stand needs to be analyzed, finalized, and fabrication drawings generated to move forward. Modifications of the test stand assembly were made with Creo 2 modeling software. Structural analysis calculations were developed by hand to confirm if the structure will hold the expected loads while optimizing support positions. These calculations when iterated through MatLab demonstrated the optimized position of the vertical support to be 98'' from the far end of the stand. All remaining deflections were shown to be under the 0.6'' requirement and internal stresses to meet NASA Ground Support Equipment (GSE) Safety Standards. Though at the time of writing, fabrication drawings have yet to be generated, but are expected shortly after.

  11. Polyploidy alters advertisement call structure in gray treefrogs.

    PubMed Central

    Keller, M. J.; Gerhardt, H. C.

    2001-01-01

    Whole-genome duplication is believed to have played a significant role in the early evolution and diversification of vertebrate animals. The establishment of newly arisen polyploid lineages of sexually reproducing animals requires assortative mating between polyploids. Here, we show that genome duplication can directly alter a phenotypic trait mediating mate choice in the absence of genotypic change. Our results suggest that the direct effect of polyploidy on behaviour is a consequence of increased cell size. PMID:11270429

  12. Hydrothermal alteration in the Bosumtwi impact structure: Evidence from 2M1-muscovite, alteration veins, and fracture fillings

    NASA Astrophysics Data System (ADS)

    Petersen, Michael T.; Newsom, Horton E.; Nelson, Melissa J.; Moore, Duane M.

    Drill-core samples from the Bosumtwi impact structure (1.07 Myr old and 10.5 km in diameter) in Ghana exhibit mineralogical evidence for post-impact hydrothermal alteration. Nine samples of drill core obtained through the 2004 International Continental Scientific Drilling Project (ICDP) were studied, including an uppermost fallback layer overlying impactite breccias, and partly deformed massive meta-graywacke bedrock. The petrographic study revealed alteration veins containing secondary sericitic muscovite (comparable to 2M1-muscovite) crosscutting original bedding in meta-graywacke and forming a matrix between clasts in impactite breccias. X-ray diffraction (XRD) shows that these impactite samples are rich in 2M1-muscovite, consistent with post-impact fluid deposition and alteration. Optical analysis indicates the presence of a pre-impact stratiform chlorite in meta-graywacke samples and a secondary alteration chlorite occurring in all samples. Secondary illite was detected in upper impactites of drill core LB-08A and samples containing accretionary lapilli. The lower temperature constraint for the hydrothermal event is given by 2M1-muscovite, secondary chlorite, and illite, all of which form at temperatures greater than 280 °C. An absence of recrystallization of quartz and feldspar indicates an upper temperature constraint below 900 °C. The presence of alteration materials associated with fractures and veins in the uppermost impactites of drill cores LB-07A and LB-08A indicates that a post-impact hydrothermal system was present in and adjacent to the central uplift portion of the Bosumtwi impact structure. A sample containing accretionary lapilli obtained from drill core LB-05A exhibits limited evidence that hydrothermal processes were more widespread within the impactites on the crater floor.

  13. Altered Esophageal Mucosal Structure in Patients with Celiac Disease

    PubMed Central

    Pinto-Sánchez, María Inés; Nachman, Fabio D.; Fuxman, Claudia; Iantorno, Guido; Hwang, Hui Jer; Ditaranto, Andrés; Costa, Florencia; Longarini, Gabriela; Wang, Xuan Yu; Huang, Xianxi; Vázquez, Horacio; Moreno, María L.; Niveloni, Sonia; Bercik, Premysl; Smecuol, Edgardo; Mazure, Roberto; Bilder, Claudio; Mauriño, Eduardo C.; Verdu, Elena F.; Bai, Julio C.

    2016-01-01

    Background/Aim. Reflux symptoms (RS) are common in patients with celiac disease (CD), a chronic enteropathy that affects primarily the small intestine. We evaluated mucosal integrity and motility of the lower esophagus as mechanisms contributing to RS generation in patients with CD. Methods. We enrolled newly diagnosed CD patients with and without RS, nonceliac patients with classical reflux disease (GERD), and controls (without RS). Endoscopic biopsies from the distal esophagus were assessed for dilated intercellular space (DIS) by light microscopy and electron microscopy. Tight junction (TJ) mRNA proteins expression for zonula occludens-1 (ZO-1) and claudin-2 and claudin-3 (CLDN-2; CLDN-3) was determined using qRT-PCR. Results. DIS scores were higher in patients with active CD than in controls, but similar to GERD patients. The altered DIS was found even in CD patients without RS and normalized after one year of a gluten-free diet. CD patients with and without RS had lower expression of ZO-1 than controls. The expression of CLDN-2 and CLDN-3 was similar in CD and GERD patients. Conclusions. Our study shows that patients with active CD have altered esophageal mucosal integrity, independently of the presence of RS. The altered expression of ZO-1 may underlie loss of TJ integrity in the esophageal mucosa and may contribute to RS generation. PMID:27446827

  14. Reverberant Acoustic Testing and Direct Field Acoustic Testing Acoustic Standing Waves and their Impact on Structural Responses

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R.; Doty, Benjamin; Chang, Zensheu

    2012-01-01

    The aerospace industry has been using two methods of acoustic testing to qualify flight hardware: (1) Reverberant Acoustic Test (RAT), (2) Direct Field Acoustic Test (DFAT). The acoustic field obtained by RAT is generally understood and assumed to be diffuse, expect below Schroeder cut-of frequencies. DFAT method of testing has some distinct advantages over RAT, however the acoustic field characteristics can be strongly affected by test setup such as the speaker layouts, number and location of control microphones and control schemes. In this paper the following are discussed based on DEMO tests performed at APL and JPL: (1) Acoustic wave interference patterns and acoustic standing waves, (2) The structural responses in RAT and DFAT.

  15. Impact of Acoustic Standing Waves on Structural Responses: Reverberant Acoustic Testing (RAT) vs. Direct Field Acoustic Testing (DFAT)

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R.; Doty, Benjamin; Chang, Zensheu

    2012-01-01

    Loudspeakers have been used for acoustic qualification of spacecraft, reflectors, solar panels, and other acoustically responsive structures for more than a decade. Limited measurements from some of the recent speaker tests used to qualify flight hardware have indicated significant spatial variation of the acoustic field within the test volume. Also structural responses have been reported to differ when similar tests were performed using reverberant chambers. To address the impact of non-uniform acoustic field on structural responses, a series of acoustic tests were performed using a flat panel and a 3-ft cylinder exposed to the field controlled by speakers and repeated in a reverberant chamber. The speaker testing was performed using multi-input-single-output (MISO) and multi-input-multi-output (MIMO) control schemes with and without the test articles. In this paper the spatial variation of the acoustic field due to acoustic standing waves and their impacts on the structural responses in RAT and DFAT (both using MISO and MIMO controls for DFAT) are discussed in some detail.

  16. Estimating survival rates with time series of standing age-structure data

    USGS Publications Warehouse

    Udevitz, Mark S.; Gogan, Peter J.

    2014-01-01

    It has long been recognized that age-structure data contain useful information for assessing the status and dynamics of wildlife populations. For example, age-specific survival rates can be estimated with just a single sample from the age distribution of a stable, stationary population. For a population that is not stable, age-specific survival rates can be estimated using techniques such as inverse methods that combine time series of age-structure data with other demographic data. However, estimation of survival rates using these methods typically requires numerical optimization, a relatively long time series of data, and smoothing or other constraints to provide useful estimates. We developed general models for possibly unstable populations that combine time series of age-structure data with other demographic data to provide explicit maximum likelihood estimators of age-specific survival rates with as few as two years of data. As an example, we applied these methods to estimate survival rates for female bison (Bison bison) in Yellowstone National Park, USA. This approach provides a simple tool for monitoring survival rates based on age-structure data.

  17. Electronic Structures of Free-Standing Nanowires made from Indirect Bandgap Semiconductor Gallium Phosphide

    PubMed Central

    Liao, Gaohua; Luo, Ning; Chen, Ke-Qiu; Xu, H. Q.

    2016-01-01

    We present a theoretical study of the electronic structures of freestanding nanowires made from gallium phosphide (GaP)—a III-V semiconductor with an indirect bulk bandgap. We consider [001]-oriented GaP nanowires with square and rectangular cross sections, and [111]-oriented GaP nanowires with hexagonal cross sections. Based on tight binding models, both the band structures and wave functions of the nanowires are calculated. For the [001]-oriented GaP nanowires, the bands show anti-crossing structures, while the bands of the [111]-oriented nanowires display crossing structures. Two minima are observed in the conduction bands, while the maximum of the valence bands is always at the Γ-point. Using double group theory, we analyze the symmetry properties of the lowest conduction band states and highest valence band states of GaP nanowires with different sizes and directions. The band state wave functions of the lowest conduction bands and the highest valence bands of the nanowires are evaluated by spatial probability distributions. For practical use, we fit the confinement energies of the electrons and holes in the nanowires to obtain an empirical formula. PMID:27307081

  18. Free-standing carbon nanotube composite sensing skin for distributed strain sensing in structures

    NASA Astrophysics Data System (ADS)

    Burton, Andrew R.; Minegishi, Kaede; Kurata, Masahiro; Lynch, Jerome P.

    2014-04-01

    The technical challenges of managing the health of critical infrastructure systems necessitate greater structural sensing capabilities. Among these needs is the ability for quantitative, spatial damage detection on critical structural components. Advances in material science have now opened the door for novel and cost-effective spatial sensing solutions specially tailored for damage detection in structures. However, challenges remain before spatial damage detection can be realized. Some of the technical challenges include sensor installations and extensive signal processing requirements. This work addresses these challenges by developing a patterned carbon nanotube composite thin film sensor whose pattern has been optimized for measuring the spatial distribution of strain. The carbon nanotube-polymer nanocomposite sensing material is fabricated on a flexible polyimide substrate using a layer-by-layer deposition process. The thin film sensors are then patterned into sensing elements using optical lithography processes common to microelectromechanical systems (MEMS) technologies. The sensor array is designed as a series of sensing elements with varying width to provide insight on the limitations of such patterning and implications of pattern geometry on sensing signals. Once fabrication is complete, the substrate and attached sensor are epoxy bonded to a poly vinyl composite (PVC) bar that is then tested with a uniaxial, cyclic load pattern and mechanical response is characterized. The fabrication processes are then utilized on a larger-scale to develop and instrument a component-specific sensing skin in order to observe the strain distribution on the web of a steel beam. The instrumented beam is part of a larger steel beam-column connection with a concrete slab in composite action. The beam-column subassembly is laterally loaded and strain trends in the web are observed using the carbon nanotube composite sensing skin. The results are discussed in the context of

  19. Fishing indirectly structures macroalgal assemblages by altering herbivore behavior.

    PubMed

    Madin, Elizabeth M P; Gaines, Steven D; Madin, Joshua S; Warner, Robert R

    2010-12-01

    Fishing has clear direct effects on harvested species, but its cascading, indirect effects are less well understood. Fishing disproportionately removes larger, predatory fishes from marine food webs. Most studies of the consequent indirect effects focus on density-mediated interactions where predator removal alternately drives increases and decreases in abundances of successively lower trophic-level species. While prey may increase in number with fewer predators, they may also alter their behavior. When such behavioral responses impact the food resources of prey species, behaviorally mediated trophic cascades can dramatically shape landscapes. It remains unclear whether this pathway of change is typically triggered by ocean fishing. By coupling a simple foraging model with empirical observations from coral reefs, we provide a mechanistic basis for understanding and predicting how predator harvest can alter the landscape of risk for herbivores and consequently drive dramatic changes in primary producer distributions. These results broaden trophic cascade predictions for fisheries to include behavioral changes. They also provide a framework for detecting the presence and magnitude of behaviorally mediated cascades. This knowledge will help to reconcile the disparity between expected and observed patterns of fishing-induced cascades in the sea.

  20. A top-down approach for fabricating free-standing bio-carbon supercapacitor electrodes with a hierarchical structure

    PubMed Central

    Li, Yingzhi; Zhang, Qinghua; Zhang, Junxian; Jin, Lei; Zhao, Xin; Xu, Ting

    2015-01-01

    Biomass has delicate hierarchical structures, which inspired us to develop a cost-effective route to prepare electrode materials with rational nanostructures for use in high-performance storage devices. Here, we demonstrate a novel top-down approach for fabricating bio-carbon materials with stable structures and excellent diffusion pathways; this approach is based on carbonization with controlled chemical activation. The developed free-standing bio-carbon electrode exhibits a high specific capacitance of 204 F g−1 at 1 A g−1; good rate capability, as indicated by the residual initial capacitance of 85.5% at 10 A g−1; and a long cycle life. These performance characteristics are attributed to the outstanding hierarchical structures of the electrode material. Appropriate carbonization conditions enable the bio-carbon materials to inherit the inherent hierarchical texture of the original biomass, thereby facilitating effective channels for fast ion transfer. The macropores and mesopores that result from chemical activation significantly increase the specific surface area and also play the role of temporary ion-buffering reservoirs, further shortening the ionic diffusion distance. PMID:26394834

  1. A top-down approach for fabricating free-standing bio-carbon supercapacitor electrodes with a hierarchical structure.

    PubMed

    Li, Yingzhi; Zhang, Qinghua; Zhang, Junxian; Jin, Lei; Zhao, Xin; Xu, Ting

    2015-09-23

    Biomass has delicate hierarchical structures, which inspired us to develop a cost-effective route to prepare electrode materials with rational nanostructures for use in high-performance storage devices. Here, we demonstrate a novel top-down approach for fabricating bio-carbon materials with stable structures and excellent diffusion pathways; this approach is based on carbonization with controlled chemical activation. The developed free-standing bio-carbon electrode exhibits a high specific capacitance of 204 F g(-1) at 1 A g(-1); good rate capability, as indicated by the residual initial capacitance of 85.5% at 10 A g(-1); and a long cycle life. These performance characteristics are attributed to the outstanding hierarchical structures of the electrode material. Appropriate carbonization conditions enable the bio-carbon materials to inherit the inherent hierarchical texture of the original biomass, thereby facilitating effective channels for fast ion transfer. The macropores and mesopores that result from chemical activation significantly increase the specific surface area and also play the role of temporary ion-buffering reservoirs, further shortening the ionic diffusion distance.

  2. Development of a Laser-Powered Dielectric Structure-Based Accelerator as a Stand-Alone Particle Source

    NASA Astrophysics Data System (ADS)

    Yoder, R. B.; Travish, G.; Arab, E. R.; Fong, D.; Hoyer, Z.; Lacroix, U. H.; Vartanian, N.; Rosenzweig, J. B.

    2010-11-01

    An experimental program to develop and build a dielectric-based slab-symmetric structure (the micro-accelerator platform, or MAP) for generating and accelerating low-energy electrons is underway at UCLA and Manhattanville College. This optical acceleration structure is effectively a resonant cavity powered by a side-coupled laser, and has applications as a radiation source for medicine or industry. We present recent experimental and computational results on the accelerator, and progress toward its incorporation into a self-contained particle source. Such a particle source would incorporate a micron-scale electron emitter and a non-relativistic capture region to enable self-injection into the synchronous field within the accelerator. A prototype of the accelerator itself has been constructed from candidate dielectric materials using micromanufacturing techniques; the current status of the testing program is described. A novel electron emitter incorporating pyroelectric crystals with field-enhancing tips has been demonstrated to produce steady currents; the results are dependent on tip geometry, and appear suitable for injection into a microstructure. Extension of the MAP concept to non-relativistic velocities, as in the stand-alone source, requires a tapered structure that gives rise to numerous complications including beam defocusing and manufacturing challenges; approaches for addressing these complications are mentioned.

  3. Community stand structure of rehabilitated forest at Kenaboi Forest Reserve, Negeri Sembilan, Malaysia

    NASA Astrophysics Data System (ADS)

    Fatma, N. A. H.; Wan Juliana, W. A.; Shaharuddin, M. I.; Wickneswari, R.

    2016-11-01

    A descriptive study of species composition, community structure and biomass was conducted in compartment 107, which is a rehabilitated area at Kenaboi Forest Reserve, Jelebu, Negeri Sembilan. The objective is to determine the forest structure and species composition in a rehabilitated area of Kenaboi FR since enrichment planting had done. A sample plot of 1 hectare was censused and a total of 395 trees with diameter ≥ 5 cm DBH were recorded. A total of 285 individual trees were identified belonging to 20 families and the commonest family was Dipterocarpaceae with 193 individuals. The highest tree density per ha was Shorea acuminata at 33% followed by S. parvifolia, 10% and S. leprosula, 6%. The biggest tree was Artocarpus elasticus Reinw. ex Blume with a diameter of 101 cm. The total basal area was 34.48 m2/ha, whereby the highest basal area was between 45 - 54.9 cm DBH class that contributed 10.21 m2/ha (30%). The total biomass estimation (above ground and below ground) was 792.57 t/ha. Dipterocarpaceae contributed the highest total biomass at 545.14 t/ha with S. acuminata contributed the highest total biomass of 330.45 t/ha. This study will contribute to the knowledge of regeneration forest especially on how the ecological process restoring the biodiversity and ecosystem functioning in rehabilitated forest by practicing the enrichment planting of native species.

  4. Stage structure alters how complexity affects stability of ecological networks

    USGS Publications Warehouse

    Rudolf, V.H.W.; Lafferty, Kevin D.

    2011-01-01

    Resolving how complexity affects stability of natural communities is of key importance for predicting the consequences of biodiversity loss. Central to previous stability analysis has been the assumption that the resources of a consumer are substitutable. However, during their development, most species change diets; for instance, adults often use different resources than larvae or juveniles. Here, we show that such ontogenetic niche shifts are common in real ecological networks and that consideration of these shifts can alter which species are predicted to be at risk of extinction. Furthermore, niche shifts reduce and can even reverse the otherwise stabilizing effect of complexity. This pattern arises because species with several specialized life stages appear to be generalists at the species level but act as sequential specialists that are hypersensitive to resource loss. These results suggest that natural communities are more vulnerable to biodiversity loss than indicated by previous analyses.

  5. Effect of environmental variables and stand structure on ecosystem respiration components in a Mediterranean beech forest.

    PubMed

    Guidolotti, Gabriele; Rey, Ana; D'Andrea, Ettore; Matteucci, Giorgio; De Angelis, Paolo

    2013-09-01

    The temporal variability of ecosystem respiration (RECO) has been reported to have important effects on the temporal variability of net ecosystem exchange, the net amount of carbon exchanged between an ecosystem and the atmosphere. However, our understanding of ecosystem respiration is rather limited compared with photosynthesis or gross primary productivity, particularly in Mediterranean montane ecosystems. In order to investigate how environmental variables and forest structure (tree classes) affect different respiration components and RECO in a Mediterranean beech forest, we measured soil, stem and leaf CO2 efflux rates with dynamic chambers and RECO by the eddy-covariance technique over 1 year (2007-2008). Ecosystem respiration showed marked seasonal variation, with the highest rates in spring and autumn and the lowest in summer. We found that the soil respiration (SR) was mainly controlled by soil water content below a threshold value of 0.2 m(3) m(-3), above which the soil temperature explained temporal variation in SR. Stem CO2 effluxes were influenced by air temperature and difference between tree classes with higher rates measured in dominant trees than in co-dominant ones. Leaf respiration (LR) varied significantly between the two canopy layers considered. Non-structural carbohydrates were a very good predictor of LR variability. We used these measurements to scale up respiration components to ecosystem respiration for the whole canopy and obtained cumulative amounts of carbon losses over the year. Based on the up-scaled chamber measurements, the relative contributions of soil, stem and leaves to the total annual CO2 efflux were: 56, 8 and 36%, respectively. These results confirm that SR is the main contributor of ecosystem respiration and provided an insight on the driving factors of respiration in Mediterranean montane beech forests.

  6. Crowding-Induced Structural Alterations of Random-Loop Chromosome Model

    NASA Astrophysics Data System (ADS)

    Kim, Jun Soo; Backman, Vadim; Szleifer, Igal

    2011-04-01

    We investigate structural alterations of random-loop polymers due to changes in the crowding condition, as a model to study environmental effects on the structure of chromosome subcompartments. The polymer structure is changed in a nonmonotonic fashion with an increasing density of crowders: condensed at small volume fractions; decondensed at high crowding volume fractions. The nonmonotonic behavior is a manifestation of the nontrivial distance dependence of the depletion interactions. We also show that crowding-induced structural alterations affect the access of binding proteins to the surface of polymer segments and are distinguished from structural changes due to the increased number of specific polymer loops.

  7. A TiO2/CNT coaxial structure and standing CNT array laminated photocatalyst to enhance the photolysis efficiency of TiO2.

    PubMed

    Wang, Gou-Jen; Lee, Ming-Way; Chen, Yi-Hong

    2008-01-01

    In this study a TiO2/CNT coaxial structure and standing CNT array laminated photocatalyst to enhance the photolysis efficiency of TiO2 is presented. An electrochemical bath that used a nanoporous anodic aluminum oxide membrane as the separation grating to separate two vessels with a transmembrane concentration gradient was constructed. The catalyzed photolysis efficiency was measured in terms of the photolysis-induced ion current. The experimental results demonstrate that the photolysis efficiency of TiO2 could be increased by the high electron conductibility of the standing CNT array. The experimental results also indicate that photolysis efficiency could be enhanced by increasing the height of the standing CNT array substrate; however, it degraded as the thickness of the TiO2/CNT coaxial structure and the TiO2 shell increased.

  8. Vegetation types, dominant compositions, woody plant diversity and stand structure in Trishna Wildlife Sanctuary of Northeast India.

    PubMed

    Majumdar, Koushik; Datta, B K

    2015-03-01

    Present study was carried out to assess the vegetation types, diversity and phytosociological status of woody plants in Trishna Wildlife Sanctuary of Tripura, Northeast India. Vegetation data was derived by 25 line transects (10 m wide and 500 m length, each 0.5 ha size). All woody species at >10 cm gbh (Girth at Breast Height) within each plots were measured and counted. A total of six forest types were classified by cluster analysis using Importance Value Index (IVI) of 289 woody species. Species diversity, forest structure and woody community associations were evaluated and discussed. One way ANOVA revealed significant differences in all species diversity measures and stand structure along the forest types. Distribution of stem density at ten different gbh classes showed reverse J-shaped curves. Population status of woody plants was also examined through grouping of all individuals into four population age stages viz. sapling (<30 cm gbh), adult (> or = 30 - <120 cm gbh), mature (>120 - 210 cm gbh) and old (> or =210 cm). To observe dominant composition and species population trend, IVI of top ten dominant species from all forest types were tabulated. The present study suggested that Trishna Wildlife Sanctuary is an important habitat in Tripura from floristic point of view and it should be conserved on priority basis for remaining wildlife endurances and monitor for forest livelihoods products for sustainable biodiversity conservation in this region.

  9. Ectomycorrhizal Community Structure and Soil Characteristics of Mature Lodgepole Pine (Pinus Contorta) and Adjacent Stands of Old Growth Mixed Conifer in Yellowstone National Park, Wyoming USA

    NASA Technical Reports Server (NTRS)

    Douglas, Robert B.; Parker, V. Thomas; Cullings, Kenneth W.; Sun, Sidney (Technical Monitor)

    2003-01-01

    Forest development patterns following disturbance are known to influence the physical and chemical attributes of soils at different points in time. Changes in soil resources are thought to have a corresponding effect on ectomycorrhizal (ECM) community structure. We used molecular methods to compare below-ground ECM species richness, composition, and abundance between adjacent stands of homogenous lodgepole pine and old growth mixed conifer in Yellowstone National Park (YNP). In each stand-type we collected soil cores to both identify mycorrhizae and assess soil chemistry. Although no statistical difference was observed in the mean number of ECM root tips per core between stand types, the total number of species identified (85 versus 35) and the mean number of species per core (8.8 +/- 0.6 versus 2.5 +/- 0.3) were significantly higher in lodgepole pine. Differences between the actual and estimated species richness levels indicated that these forest types support a high number of ECM species and that undersampling was severe. Species compositions were widely disparate between stands where only four species were shared out of a total of 116. Soil analysis also revealed that mixed conifer was significantly lower in pH, but higher in organic matter, potassium, phosphorus, and ammonium when compared to lodgepole pine stands. Species richness per core was correlated with these chemical data, however, analysis of covariance indicated that stand type was the only statistically significant factor in the observed difference in species richness. Our data suggest that ECM fungal richness increases as homogenous lodgepole pine stands grow and mature, but declines after Engelmann spruce and subalpine fir colonize. Despite difficulties linking species composition with soil chemistry, there are a variety of physical and chemical factors that could be influencing ECM community structure. Future field experiments are necessary to test some of the mechanisms potentially operating

  10. Circulating Microparticles Alter Formation, Structure, and Properties of Fibrin Clots

    PubMed Central

    Zubairova, Laily D.; Nabiullina, Roza M.; Nagaswami, Chandrasekaran; Zuev, Yuriy F.; Mustafin, Ilshat G.; Litvinov, Rustem I.; Weisel, John W.

    2015-01-01

    Despite the importance of circulating microparticles in haemostasis and thrombosis, there is limited evidence for potential causative effects of naturally produced cell-derived microparticles on fibrin clot formation and its properties. We studied the significance of blood microparticles for fibrin formation, structure, and susceptibility to fibrinolysis by removing them from platelet-free plasma using filtration. Clots made in platelet-free and microparticle-depleted plasma samples from the same healthy donors were analyzed in parallel. Microparticles accelerate fibrin polymerisation and support formation of more compact clots that resist internal and external fibrinolysis. These variations correlate with faster thrombin generation, suggesting thrombin-mediated kinetic effects of microparticles on fibrin formation, structure, and properties. In addition, clots formed in the presence of microparticles, unlike clots from the microparticle-depleted plasma, contain 0.1–0.5-μm size granular and CD61-positive material on fibres, suggesting that platelet-derived microparticles attach to fibrin. Therefore, the blood of healthy individuals contains functional microparticles at the levels that have a procoagulant potential. They affect the structure and stability of fibrin clots indirectly through acceleration of thrombin generation and through direct physical incorporation into the fibrin network. Both mechanisms underlie a potential role of microparticles in haemostasis and thrombosis as modulators of fibrin formation, structure, and resistance to fibrinolysis. PMID:26635081

  11. Experimental sulfate amendment alters peatland bacterial community structure.

    PubMed

    Strickman, R J S; Fulthorpe, R R; Coleman Wasik, J K; Engstrom, D R; Mitchell, C P J

    2016-10-01

    As part of a long-term, peatland-scale sulfate addition experiment, the impact of varying sulfate deposition on bacterial community responses was assessed using 16S tag encoded pyrosequencing. In three separate areas of the peatland, sulfate manipulations included an eight year quadrupling of atmospheric sulfate deposition (experimental), a 3-year recovery to background deposition following 5years of elevated deposition (recovery), and a control area. Peat concentrations of methylmercury (MeHg), a bioaccumulative neurotoxin, were measured, the production of which is attributable to a growing list of microorganisms, including many sulfate-reducing Deltaproteobacteria. The total bacterial and Deltaproteobacterial community structures in the experimental treatment differed significantly from those in the control and recovery treatments that were either indistinguishable or very similar to one another. Notably, the relatively rapid return (within three years) of bacterial community structure in the recovery treatment to a state similar to the control, demonstrates significant resilience of the peatland bacterial community to changes in atmospheric sulfate deposition. Changes in MeHg accumulation between sulfate treatments correlated with changes in the Deltaproteobacterial community, suggesting that sulfate may affect MeHg production through changes in the community structure of this group.

  12. Repression and activation by multiprotein complexes that alter chromatin structure.

    PubMed

    Kingston, R E; Bunker, C A; Imbalzano, A N

    1996-04-15

    Recent studies have provided strong evidence that macromolecular complexes are used in the cell to remodel chromatin structure during activation and to create an inaccessible structure during repression, Although there is not yet any rigorous demonstration that modification of chromatin structure plays a direct, causal role in either activation or repression, there is sufficient smoke to indicate the presence of a blazing inferno nearby. It is clear that complexes that remodel chromatin are tractable in vitro; hopefully this will allow the establishment of systems that provide a direct analysis of the role that remodeling might play in activation. These studies indicate that establishment of functional systems to corroborate the elegant genetic studies on repression might also be tractable. As the mechanistic effects of these complexes are sorted out, it will become important to understand how the complexes are regulated. In many of the instances discussed above, the genes whose products make up these complexes were identified in genetic screens for effects on developmental processes. This implies a regulation of the activity of these complexes in response to developmental cues and further implies that the work to fully understand these complexes will occupy a generation of scientists.

  13. Temperature alters food web body-size structure.

    PubMed

    Gibert, Jean P; DeLong, John P

    2014-08-01

    The increased temperature associated with climate change may have important effects on body size and predator-prey interactions. The consequences of these effects for food web structure are unclear because the relationships between temperature and aspects of food web structure such as predator-prey body-size relationships are unknown. Here, we use the largest reported dataset for marine predator-prey interactions to assess how temperature affects predator-prey body-size relationships among different habitats ranging from the tropics to the poles. We found that prey size selection depends on predator body size, temperature and the interaction between the two. Our results indicate that (i) predator-prey body-size ratios decrease with predator size at below-average temperatures and increase with predator size at above-average temperatures, and (ii) that the effect of temperature on predator-prey body-size structure will be stronger at small and large body sizes and relatively weak at intermediate sizes. This systematic interaction may help to simplify forecasting the potentially complex consequences of warming on interaction strengths and food web stability.

  14. Alteration of Large-Scale Chromatin Structure by Estrogen Receptor

    PubMed Central

    Nye, Anne C.; Rajendran, Ramji R.; Stenoien, David L.; Mancini, Michael A.; Katzenellenbogen, Benita S.; Belmont, Andrew S.

    2002-01-01

    The estrogen receptor (ER), a member of the nuclear hormone receptor superfamily important in human physiology and disease, recruits coactivators which modify local chromatin structure. Here we describe effects of ER on large-scale chromatin structure as visualized in live cells. We targeted ER to gene-amplified chromosome arms containing large numbers of lac operator sites either directly, through a lac repressor-ER fusion protein (lac rep-ER), or indirectly, by fusing lac repressor with the ER interaction domain of the coactivator steroid receptor coactivator 1. Significant decondensation of large-scale chromatin structure, comparable to that produced by the ∼150-fold-stronger viral protein 16 (VP16) transcriptional activator, was produced by ER in the absence of estradiol using both approaches. Addition of estradiol induced a partial reversal of this unfolding by green fluorescent protein-lac rep-ER but not by wild-type ER recruited by a lac repressor-SRC570-780 fusion protein. The chromatin decondensation activity did not require transcriptional activation by ER nor did it require ligand-induced coactivator interactions, and unfolding did not correlate with histone hyperacetylation. Ligand-induced coactivator interactions with helix 12 of ER were necessary for the partial refolding of chromatin in response to estradiol using the lac rep-ER tethering system. This work demonstrates that when tethered or recruited to DNA, ER possesses a novel large-scale chromatin unfolding activity. PMID:11971975

  15. Electronic structures of [1 1 1]-oriented free-standing InAs and InP nanowires.

    PubMed

    Liao, Gaohua; Luo, Ning; Chen, Ke-Qiu; Xu, H Q

    2016-04-06

    We report on a theoretical study of the electronic structures of the [1 1 1]-oriented, free-standing, zincblende InAs and InP nanowires with hexagonal cross sections by means of an atomistic sp(3)s*, spin-orbit interaction included, nearest-neighbor, tight-binding method. The band structures and the band state wave functions of these nanowires are calculated and the symmetry properties of the bands and band states are analyzed based on the C(3v) double point group. It is shown that all bands of these nanowires are doubly degenerate at the Γ-point and some of these bands will split into non-degenerate bands when the wave vector k moves away from the Γ-point as a manifestation of spin-splitting due to spin-orbit interaction. It is also shown that the lower conduction bands of these nanowires all show simple parabolic dispersion relations, while the top valence bands show complex dispersion relations and band crossings. The band state wave functions are presented by the spatial probability distributions and it is found that all the band states show 2π/3-rotation symmetric probability distributions. The effects of quantum confinement on the band structures of the [1 1 1]-oriented InAs and InP nanowires are also examined and an empirical formula for the description of quantization energies of the lowest conduction band and the highest valence band is presented. The formula can simply be used to estimate the enhancement of the band gaps of the nanowires at different sizes as a result of quantum confinement.

  16. Abdominal Pain, the Adolescent and Altered Brain Structure and Function

    PubMed Central

    Becerra, Lino; Heinz, Nicole; Ludwick, Allison; Rasooly, Tali; Wu, Rina; Johnson, Adriana; Schechter, Neil L.; Borsook, David; Nurko, Samuel

    2016-01-01

    Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder of unknown etiology. Although relatively common in children, how this condition affects brain structure and function in a pediatric population remains unclear. Here, we investigate brain changes in adolescents with IBS and healthy controls. Imaging was performed with a Siemens 3 Tesla Trio Tim MRI scanner equipped with a 32-channel head coil. A high-resolution T1-weighted anatomical scan was acquired followed by a T2-weighted functional scan. We used a surface-based morphometric approach along with a seed-based resting-state functional connectivity (RS-FC) analysis to determine if groups differed in cortical thickness and whether areas showing structural differences also showed abnormal RS-FC patterns. Patients completed the Abdominal Pain Index and the GI Module of the Pediatric Quality of Life Inventory to assess abdominal pain severity and impact of GI symptoms on health-related quality of life (HRQOL). Disease duration and pain intensity were also assessed. Pediatric IBS patients, relative to controls, showed cortical thickening in the posterior cingulate (PCC), whereas cortical thinning in posterior parietal and prefrontal areas were found, including the dorsolateral prefrontal cortex (DLPFC). In patients, abdominal pain severity was related to cortical thickening in the intra-abdominal area of the primary somatosensory cortex (SI), whereas HRQOL was associated with insular cortical thinning. Disease severity measures correlated with cortical thickness in bilateral DLPFC and orbitofrontal cortex. Patients also showed reduced anti-correlations between PCC and DLPFC compared to controls, a finding that may reflect aberrant connectivity between default mode and cognitive control networks. We are the first to demonstrate concomitant structural and functional brain changes associated with abdominal pain severity, HRQOL related to GI-specific symptoms, and disease-specific measures in

  17. Structural alterations of fully hydrated human stratum corneum

    NASA Astrophysics Data System (ADS)

    Charalambopoulou, G. Ch.; Steriotis, Th. A.; Hauss, Th.; Stubos, A. K.; Kanellopoulos, N. K.

    2004-07-01

    The diffusional barrier function of skin is associated with the superficial epidermal layer, the stratum corneum, a highly complex biomembrane consisting of a staggered corneocyte arrangement in a lipid lamellar continuum. One of the key elements for stratum corneum barrier function is its hydration state. In the present work, the membrane neutron diffraction method is employed to reveal important stratum corneum structural changes that emanate upon water uptake. Increasing stratum corneum water content was observed to lead reversibly to the progressive disruption of the highly ordered lipid configuration and the distortion of the system's barrier function.

  18. Sensitivity of ERS-1 and JERS-1 radar data to biomass and stand structure in Alaskan boreal forest

    SciTech Connect

    Harrell, P.A.; Christensen, N.L. Jr.; Bourgeau-Chavez, L.L.; Kasischke, E.S.; French, N.H.F.

    1995-12-01

    As the boreal system is such an important component of the global carbon budget, it is important that the system and the potential changes be understood, whether from anthropogenic disturbances or global climate change. Thirty-two boreal forest sites were identified and sampled in the central region of Alaska to evaluate the sensitivity of the C-band ERS-1 and the L-band JERS-1 radar platforms to site biophysical properties. The sites selected represent black spruce (Picea mariana) and white spruce (Picea glauca) stands in a post-fire chronosequence. Black spruce biomass ranged from less than 1 kg/m{sup 2} to 5.6 kg/m{sup 2} and white spruce from 8.8 to 21.5 kg/m{sup 2}. Results indicate both ERS-1 and JERS-1 backscatter is responsive to biomass, density, and height, though other factors, principally surface moisture conditions, are often a stronger influence. Sensitivity to forest biomass and structure appears greatest when surface moisture conditions are minimized as a factor. Biomass correlations with the radar backscatter were strongest in the late winter imagery when all sites had a snow cover, and late summer when the surface is most dry. ERS-1 data may be more sensitive to surface moisture conditions than the JERS-1 data due to the shorter wavelength of the C-band sensor, though this is inconclusive because of limited JERS-1 L-band data for comparison.

  19. Ectomycorrhizal diversity and community structure in stands of Quercus oleoides in the seasonally dry tropical forests of Costa Rica

    NASA Astrophysics Data System (ADS)

    Desai, Nikhilesh S.; Wilson, Andrew W.; Powers, Jennifer S.; Mueller, Gregory M.; Egerton-Warburton, Louise M.

    2016-12-01

    Most conservation efforts in seasonally dry tropical forests have overlooked less obvious targets for conservation, such as mycorrhizal fungi, that are critical to plant growth and ecosystem structure. We documented the diversity of ectomycorrhizal (EMF) and arbuscular mycorrhizal (AMF) fungal communities in Quercus oleoides (Fagaceae) in Guanacaste province, Costa Rica. Soil cores and sporocarps were collected from regenerating Q. oleoides plots differing in stand age (early vs late regeneration) during the wet season. Sequencing of the nuclear ribosomal ITS region in EMF root tips and sporocarps identified 37 taxa in the Basidiomycota; EMF Ascomycota were uncommon. The EMF community was dominated by one species (Thelephora sp. 1; 70% of soil cores), more than half of all EMF species were found only once in an individual soil core, and there were few conspecific taxa. Most EMF taxa were also restricted to either Early or Late plots. Levels of EMF species richness and diversity, and AMF root colonization were similar between plots. Our results highlight the need for comprehensive spatiotemporal samplings of EMF communities in Q. oleoides to identify and prioritize rare EMF for conservation, and document their genetic and functional diversity.

  20. A structural study of the interaction of methanethiol with Pt (1 1 1) using X-ray standing waves

    NASA Astrophysics Data System (ADS)

    Lee, J. J.; Fisher, C. J.; Bittencourt, C.; Woodruff, D. P.; Chan, A. S. Y.; Jones, R. G.

    2002-09-01

    In combination with surface characterisation by synchrotron radiation X-ray photoelectron spectroscopy, the normal incidence X-ray standing wave (NIXSW) technique has been applied to a determination of the structure of surface phases formed on Pt(1 1 1) by reaction with methanethiol. On surfaces heated to ⩾ ≈500 K, producing only coadsorbed atomic S and C, the S atoms are found to occupy fcc hollow sites (directly above Pt atoms in the third layer) in a geometry essentially identical to that of simple ordered S overlayer phases on Pt(1 1 1) with a S-Pt layer spacing of 1.67 Å, but with possible fractional co-occupation of a complex S phase. On a surface annealed to ≈223 K only a surface methanethiolate (CH 3S-) species is believed to be present, the favoured model involves a tilted off-atop bonding such that the S atoms are located offset from the fcc hollow sites, with frustrated rotational vibrations of large amplitude, although an alternative model based on co-occupation of atop and fcc hollow sites is also consistent with the NIXSW data.

  1. Sphingomyelin induces structural alteration in canine parvovirus capsid.

    PubMed

    Pakkanen, Kirsi; Karttunen, Jenni; Virtanen, Salla; Vuento, Matti

    2008-03-01

    One of the essential steps in canine parvovirus (CPV) infection, the release from endosomal vesicles, is dominated by interactions between the virus capsid and the endosomal membranes. In this study, the effect of sphingomyelin and phosphatidyl serine on canine parvovirus capsid and on the phospholipase A(2) (PLA(2)) activity of CPV VP1 unique N-terminus was analyzed. Accordingly, a significant (P< or =0.05) shift of tryptophan fluorescence emission peak was detected at pH 5.5 in the presence of sphingomyelin, whereas at pH 7.4 a similar but minor shift was observed. This effect may relate to the exposure of VP1 N-terminus in acidic pH as well as to interactions between sphingomyelin and CPV. When the phenomenon was further characterized using circular dichroism spectroscopy, differences in CPV capsid CD spectra with and without sphingomyelin and phosphatidyl serine were detected, corresponding to data obtained with tryptophan fluorescence. However, when the enzymatic activity of CPV PLA(2) was tested in the presence of sphingomyelin, no significant effect in the function of the enzyme was detected. Thus, the structural changes observed with spectroscopic techniques appear not to manipulate the activity of CPV PLA(2), and may therefore implicate alternative interactions between CPV capsid and sphingomyelin.

  2. Endophytic fungi alter sucking bug responses to cotton reproductive structures.

    PubMed

    Sword, Gregory A; Tessnow, Ashley; Ek-Ramos, Maria Julissa

    2017-03-22

    All plants including cotton host a wide range of microorganisms as endophytes. There is a growing appreciation of the prevalence, ecological significance and management potential of facultative fungal endophytes in protecting plants from pests, pathogens and environmental stressors. Hemipteran sucking bugs have emerged as major pests across the US cotton belt, reducing yields directly by feeding on developing reproductive structures and indirectly by vectoring plant pathogens. We used no-choice and simultaneous choice assays to examine the host selection behavior of western tarnished plant bugs (Lygus hesperus) and southern green stink bugs (Nezara viridula) in response to developing flower buds and fruits from cotton plants colonized by one of two candidate beneficial fungal endophytes, Phialemonium inflatum or Beauveria bassiana. Both insect species exhibited strong negative responses to flower buds (L. hesperus) and fruits (N. viridula) from plants that had been colonized by candidate endophytic fungi relative to control plants under both no-choice and choice conditions. Behavioral responses of both species indicated that the insects were deterred prior to contact with plant tissues from endophyte-colonized plants, suggesting a putative role for volatile compounds in mediating the negative response. Our results highlight the role of fungal endophytes as plant mutualists that can have positive effects on plant resistance to pests. This article is protected by copyright. All rights reserved.

  3. 18 CFR 1304.209 - Land-based structures/alterations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 2 2010-04-01 2010-04-01 false Land-based structures... TVA-Owned Residential Access Shoreland § 1304.209 Land-based structures/alterations. (a) Except for... grading shall be allowed on TVA land. (b) Portable items such as picnic tables and hammocks may be...

  4. 18 CFR 1304.209 - Land-based structures/alterations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 2 2012-04-01 2012-04-01 false Land-based structures... TVA-Owned Residential Access Shoreland § 1304.209 Land-based structures/alterations. (a) Except for... grading shall be allowed on TVA land. (b) Portable items such as picnic tables and hammocks may be...

  5. 18 CFR 1304.209 - Land-based structures/alterations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 2 2013-04-01 2012-04-01 true Land-based structures... TVA-Owned Residential Access Shoreland § 1304.209 Land-based structures/alterations. (a) Except for... grading shall be allowed on TVA land. (b) Portable items such as picnic tables and hammocks may be...

  6. [Influence of mulching management on the relationships between foliar non-structural carbohydrates and N, P concentrations in Phyllostachys violascens stand].

    PubMed

    Guo, Zi-wu; Hu, Jun-jing; Yang, Qing-ping; Li, Ying-chun; Chen, Shuang-lin; Chen, Wei-jun

    2015-04-01

    To understand the physiological adaptive mechanism of Phyllostachys violascens to intensive mulching management, the effect of mulching management (CK, 1, 3 and 6 years) on the concentrations and ratios of non-structural carbohydrates (NSC), nitrogen (N) and phosphorus (P) in bamboo foliage, and their stoichiometry was investigated. The results showed the concentrations of NSC and soluble sugar increased, while the starch content and N/P decreased markedly in bamboo stand with 1-year mulching, compared to CK stand, which suggested the N limitation to bamboo growth was strengthened. Foliar soluble sugar content decreased significantly, while the starch content increased dramatically, and the NSC content by per unit mass of N and P reached the maximum in the bamboo stand with 3-year mulching, compared to all other treatments. Foliar NSC and soluble sugar contents decreased significantly, while foliar starch content and N/P increased dramatically in the stand with 6-year mulching, which suggested the P limitation to bamboo growth was strengthened. Foliar NSC content was positively correlated with N and P concentrations in a short-term mulching management stand (≤ 3 years), while showed negative relationship with N/P. The foliar starch content in the stand with 6-year mulching was negatively correlated with N and P contents, while was positively correlated with N/P. The results indicated that short-term mulching management accelerated the accumulation of soluble sugar and decomposition of starch in foliage, thus the growth and activity of Ph. violascens was enhanced greatly. Long-term mulching management promoted the starch accumulation, which led to the transition from N limitation to P limitation for bamboo growth. In summary, long-term (6 years) mulching management caused the decrease of growth and activity of Ph. violascens dramatically, thus enhancing the bamboo stand degradation. The utilization efficiency of N and P reached the highest in the stand with 3-year

  7. Investigating the effect of different asphaltene structures on surface topography and wettability alteration

    NASA Astrophysics Data System (ADS)

    Amin, J. Sayyad; E. Nikooee; Ghatee, M. H.; Ayatollahi, Sh.; Alamdari, A.; Sedghamiz, T.

    2011-08-01

    This paper aims at investigation of the effect of asphaltene structure on wettability and topography alteration of a glass surface as a result of asphaltene precipitation. In order to provide a better insight into the topography alteration, a bi-fractal approach was employed. Such an approach is capable of discriminating topography alteration in two different surface types, namely, macro-asperities and micro-asperities. The observed variation of the fractal dimension in the two surface types could be considered as the consequence of different asphaltene sources. Therefore, the structure of different asphaltene sources was carefully examined. The effect of asphaltene structure is more pronounced for asphaltene precipitation at higher pressure. It was revealed that asphaltene particles of high complexity and with larger poly-aromatic rings tend to be detached easier at higher pressure than those with smaller poly-aromatic rings. Another evidence to emphasize the significance of asphaltene structure was given through wettability alteration. It was found that asphaltene particles with larger poly-aromatic rings turn the surface less oil wet at higher pressure. It seems that the difference in wetting condition and surface topography alteration of different asphaltene sources roots in their different structures.

  8. Ultra-structural hair alterations in Friedreich's ataxia: A scanning electron microscopic investigation.

    PubMed

    Turkmenoglu, F Pinar; Kasirga, U Baran; Celik, H Hamdi

    2015-08-01

    Friedreich's ataxia (FRDA) is an autosomal recessive inherited disorder involving progressive damage to the central and peripheral nervous systems and cardiomyopathy. FRDA is caused by the silencing of the FXN gene and reduced levels of the encoded protein, frataxin. Frataxin is a mitochondrial protein that functions primarily in iron-sulfur cluster synthesis. Skin disorders including hair abnormalities have previously been reported in patients with mitochondrial disorders. However, to our knowledge, ultra-structural hair alterations in FRDA were not demonstrated. The purpose of this study was to determine ultra-structural alterations in the hairs of FRDA patients as well as carriers. Hair specimen from four patients, who are in different stages of the disease, and two carriers were examined by scanning electron microscope. Thin and weak hair follicles with absence of homogeneities on the cuticular surface, local damages of the cuticular layer, cuticular fractures were detected in both carriers and patients, but these alterations were much more prominent in the hair follicles of patients. In addition, erosions on the surface of the cuticle and local deep cavities just under the cuticular level were observed only in patients. Indistinct cuticular pattern, pores on the cuticular surface, and presence of concavities on the hair follicle were also detected in patients in later stages of the disease. According to our results, progression of the disease increased the alterations on hair structure. We suggest that ultra-structural alterations observed in hair samples might be due to oxidative stress caused by deficient frataxin expression in mitochondria.

  9. Mordenite and montmorillonite alteration of glass structures in a rhyolite pipe, northern Black Hills, South Dakota

    SciTech Connect

    Kirchner, J.G. )

    1991-10-01

    Green structures, 0.5 to 1.5 in. across, occur in a Tertiary rhyolite pipe in the northern Black Hills, South Dakota. The structures are of two types: angular to ellipsoidal masses and stretched or smeared structures. Thin section analysis revealed that those of the first type are massive, with no internal structure, and those of the second type are cellular and have classic flame structure characteristics. XRD indicated the composition to be a mixture of secondary mordenite (a zeolite) and montmorillonite. The first type is interpreted to be deuterically altered vitrophyre clasts and the second type to be altered vesicular structures produced by degassing of the magma in the pipe. Chemical analysis of the alteration material indicates a loss of alkalies and silica, with an increase in water, CaO, MgO and ferric iron when compared to the composition of fresh vitrophyre from the same pipe. The changes are in agreement with experimental work on the alteration of rhyolitic glass by a number of researchers. This is the first occurrence of mordenite reported for the Black Hills.

  10. DNA damage response induces structural alterations in histone H3–H4

    PubMed Central

    Izumi, Yudai; Fujii, Kentaro; Yamamoto, Satoshi; Matsuo, Koichi; Namatame, Hirofumi; Taniguchi, Masaki; Yokoya, Akinari

    2017-01-01

    Synchrotron-radiation circular-dichroism spectroscopy was used to reveal that the DNA damage response induces a decrement of α-helix and an increment of β-strand contents of histone H3–H4 extracted from X-ray–irradiated human HeLa cells. The trend of the structural alteration was qualitatively opposite to that of our previously reported results for histone H2A–H2B. These results strongly suggest that histones share roles in DNA damage responses, particularly in DNA repair processes and chromatin remodeling, via a specific structural alteration of each histone. PMID:27672100

  11. In utero and postnatal exposure to arsenic alters pulmonary structure and function

    SciTech Connect

    Lantz, R. Clark Chau, Binh; Sarihan, Priyanka; Witten, Mark L.; Pivniouk, Vadim I.; Chen, Guan Jie

    2009-02-15

    In addition to cancer endpoints, arsenic exposures can also lead to non-cancerous chronic lung disease. Exposures during sensitive developmental time points can contribute to the adult disease. Using a mouse model, in utero and early postnatal exposures to arsenic (100 ppb or less in drinking water) were found to alter airway reactivity to methacholine challenge in 28 day old pups. Removal of mice from arsenic exposure 28 days after birth did not reverse the alterations in sensitivity to methacholine. In addition, adult mice exposed to similar levels of arsenic in drinking water did not show alterations. Therefore, alterations in airway reactivity were irreversible and specific to exposures during lung development. These functional changes correlated with protein and gene expression changes as well as morphological structural changes around the airways. Arsenic increased the whole lung levels of smooth muscle actin in a dose dependent manner. The level of smooth muscle mass around airways was increased with arsenic exposure, especially around airways smaller than 100 {mu}m in diameter. This increase in smooth muscle was associated with alterations in extracellular matrix (collagen, elastin) expression. This model system demonstrates that in utero and postnatal exposure to environmentally relevant levels of arsenic can irreversibly alter pulmonary structure and function in the adults.

  12. Finite-Element Extrapolation of Myocardial Structure Alterations Across the Cardiac Cycle in Rats

    PubMed Central

    David Gomez, Arnold; Bull, David A.; Hsu, Edward W.

    2015-01-01

    Myocardial microstructures are responsible for key aspects of cardiac mechanical function. Natural myocardial deformation across the cardiac cycle induces measurable structural alteration, which varies across disease states. Diffusion tensor magnetic resonance imaging (DT-MRI) has become the tool of choice for myocardial structural analysis. Yet, obtaining the comprehensive structural information of the whole organ, in 3D and time, for subject-specific examination is fundamentally limited by scan time. Therefore, subject-specific finite-element (FE) analysis of a group of rat hearts was implemented for extrapolating a set of initial DT-MRI to the rest of the cardiac cycle. The effect of material symmetry (isotropy, transverse isotropy, and orthotropy), structural input, and warping approach was observed by comparing simulated predictions against in vivo MRI displacement measurements and DT-MRI of an isolated heart preparation at relaxed, inflated, and contracture states. Overall, the results indicate that, while ventricular volume and circumferential strain are largely independent of the simulation strategy, structural alteration predictions are generally improved with the sophistication of the material model, which also enhances torsion and radial strain predictions. Moreover, whereas subject-specific transversely isotropic models produced the most accurate descriptions of fiber structural alterations, the orthotropic models best captured changes in sheet structure. These findings underscore the need for subject-specific input data, including structure, to extrapolate DT-MRI measurements across the cardiac cycle. PMID:26299478

  13. Ultra-structural hair alterations of drug abusers: a scanning electron microscopic investigation

    PubMed Central

    Turkmenoglu, Fatma Pinar; Kasirga, Ugur Baran; Celik, Hakan Hamdi

    2015-01-01

    As drug abuse carries a societal stigma, patients do not often report their history of drug abuse to the healthcare providers. However, drug abuse is highly co-morbid with a host of other health problems such as psychiatric disorders and skin diseases, and majority of individuals with drug use disorders seek treatment in the first place for other problems. Therefore, it is very important for physicians to be aware of clinical signs and symptoms of drug use. Recently diagnostic value of dermatologic tissue alterations associated with drug abuse has become a very particular interest because skin changes were reported to be the earliest noticeable consequence of drug abuse prompting earlier intervention and treatment. Although hair is an annex of skin, alterations on hair structure due to drug use have not been demonstrated. This study represents the first report on ultra-structural hair alterations of drug abusers. We have investigated ultra-structure of the hair samples obtained from 6 cocaine, 6 heroin, 7 cannabis and 4 lysergic acid diethylamide (LSD) abusers by scanning electron microscope (SEM). SEM analysis of hair samples gave us drug-specific discriminating alterations. We suggest that results of this study will make a noteworthy contribution to cutaneous alterations associated with drug abuse which are regarded as the earliest clinical manifestations, and this SEM approach is a very specific and effective tool in the detection of abuse of respective drugs, leading early treatment. PMID:26309532

  14. In Situ Structural Studies of the Underpotential Deposition of Copper onto an Iodine Covered Platinum Surface Using X-Ray Standing Waves

    DTIC Science & Technology

    1991-01-01

    ABSTRAc C We present initial results of an in situ structural investigation of the underpotential deposition of copper on an iodine covered platinum...compare the result of surface coverage isotherms derived from both electrochemical and x-ray measurements. 1. INTRODUCIION The underpotential deposition ...the underpotential deposition of copper on an iodine covered platinum/carbon layered synthetic microstructure. 2 THEORETICAL BACKGROUND X-ray standing

  15. Temporal and structural effects of stands on litter production in Melaleuca quinquenervia dominated wetlands of South Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Melaleuca quinquenervia (melaleuca) dominates large areas of the Florida Everglades in the southeastern USA where it has transformed sedge-dominated marshes into melaleuca forests. Despite its prevalence, very little is known about the ecology and stand dynamics of this invasive tree. We delineated...

  16. How the timberline formed: altitudinal changes in stand structure and dynamics around the timberline in central Japan

    PubMed Central

    Takahashi, Koichi; Hirosawa, Tatsuru; Morishima, Ryohei

    2012-01-01

    Background and Aims Altitudinal timberlines are thought to move upward by global warming, a crucial topic in ecology. Tall tree species (the conifer Abies mariesii and the deciduous broad-leaved Betula ermanii) dominate the sub-alpine zone between 1600 and 2500 m a.s.l., the timberline, on Mount Norikura in central Japan. Dwarf pine Pinus pumila dominates above the timberline to near the summit (3026 m a.s.l.). This study evaluated how the timberline formed on Mount Norikura by examining altitudinal changes in stand structure and dynamics around the timberline. Methods One hundred and twenty-five plots of 10 m × 10 m were established around the timberline (2350–2600 m a.s.l.). Trunk diameter growth rate during 6 years was examined for A. mariesii, B. ermanii and P. pumila. Mortality during this period and mechanical damage scars on the trunks and branches due to strong wind and snow were examined for A. mariesii only. Key Results The density, maximum trunk height and diameter of A. mariesii in plots decreased with altitude. The maximum trunk height of B. ermanii decreased with altitude, but density and maximum trunk diameter did not decrease. In contrast, the density of P. pumila abruptly increased from around the timberline. A strong negative correlation was found between the densities of P. pumila and tall tree species, indicating their interspecific competition. Trunk diameter growth rates of A. mariesii and B. ermanii did not decrease with altitude, suggesting that these two tall tree species can grow at the timberline. The ratio of trees with mechanical damage scars increased with altitude for A. mariesii, a tendency more conspicuous for larger trees. The mortality of larger A. mariesii was also greater at higher altitude. Tall tree species may not increase their trunk height and survive around the timberline because of mechanical damage. Conclusions This study suggests that the altitudinal location of the timberline is mainly affected by mechanical damage

  17. 78 FR 69614 - Home Improvements and Structural Alterations (HISA) Benefits Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-20

    ... Federal Docket Management System (FDMS) at http://www.regulations.gov . FOR FURTHER INFORMATION CONTACT... VA-DoD Integrated Disability Evaluation System (IDES), which integrates disability determination... includes the diagnosis and medical justification for the improvement or structural alteration. VA relies...

  18. Discovery of structural alterations in solid tumor oligodendroglioma by single molecule analysis

    PubMed Central

    2013-01-01

    Background Solid tumors present a panoply of genomic alterations, from single base changes to the gain or loss of entire chromosomes. Although aberrations at the two extremes of this spectrum are readily defined, comprehensive discernment of the complex and disperse mutational spectrum of cancer genomes remains a significant challenge for current genome analysis platforms. In this context, high throughput, single molecule platforms like Optical Mapping offer a unique perspective. Results Using measurements from large ensembles of individual DNA molecules, we have discovered genomic structural alterations in the solid tumor oligodendroglioma. Over a thousand structural variants were identified in each tumor sample, without any prior hypotheses, and often in genomic regions deemed intractable by other technologies. These findings were then validated by comprehensive comparisons to variants reported in external and internal databases, and by selected experimental corroborations. Alterations range in size from under 5 kb to hundreds of kilobases, and comprise insertions, deletions, inversions and compound events. Candidate mutations were scored at sub-genic resolution and unambiguously reveal structural details at aberrant loci. Conclusions The Optical Mapping system provides a rich description of the complex genomes of solid tumors, including sequence level aberrations, structural alterations and copy number variants that power generation of functional hypotheses for oligodendroglioma genetics. PMID:23885787

  19. Experimental alteration of artificial and natural impact melt rock from the Chesapeake Bay impact structure

    USGS Publications Warehouse

    Declercq, J.; Dypvik, H.; Aagaard, P.; Jahren, J.; Ferrell, R.E.; Horton, J. Wright

    2009-01-01

    The alteration or transformation of impact melt rock to clay minerals, particularly smectite, has been recognized in several impact structures (e.g., Ries, Chicxulub, Mj??lnir). We studied the experimental alteration of two natural impact melt rocks from suevite clasts that were recovered from drill cores into the Chesapeake Bay impact structure and two synthetic glasses. These experiments were conducted at hydrothermal temperature (265 ??C) in order to reproduce conditions found in meltbearing deposits in the first thousand years after deposition. The experimental results were compared to geochemical modeling (PHREEQC) of the same alteration and to original mineral assemblages in the natural melt rock samples. In the alteration experiments, clay minerals formed on the surfaces of the melt particles and as fine-grained suspended material. Authigenic expanding clay minerals (saponite and Ca-smectite) and vermiculite/chlorite (clinochlore) were identified in addition to analcime. Ferripyrophyllite was formed in three of four experiments. Comparable minerals were predicted in the PHREEQC modeling. A comparison between the phases formed in our experiments and those in the cores suggests that the natural alteration occurred under hydrothermal conditions similar to those reproduced in the experiment. ?? 2009 The Geological Society of America.

  20. Structure and composition of vegetation of longleaf pine plantations compared to natural stands occurring along an environmental gradient at the Savannah River Site.

    SciTech Connect

    Smith, Gregory, P.; Shelburne, Victor, B.; Walker, Joan, L.

    2001-12-30

    Study plots in 33-43 year old longleaf pine plantations were compared to remnant longleaf plots on the Savannah River Site in South Carolina. Within these stands, the structure and composition of primarily the herb layer relative to a presumed soil moisture or soil texture gradient was studied using the North Carolina Vegetation Survey methodology. Data were also collected on soils and landform variables. Based on ordination and cluster analyses, both plantation plots and natural stand plots were separated into three distinct site units (xeric, sub-xeric, and sub-mesic). Lack of a major compositional difference between xeric plantation and natural longleaf sites suggests that restoration of the herbaceous layer may not be as complex as once thought. This provides reasonable encouragement for the restoration of the longleaf pine ecosystem.

  1. Exploring Patterns of Alteration in Alzheimer's Disease Brain Networks: A Combined Structural and Functional Connectomics Analysis

    PubMed Central

    Palesi, Fulvia; Castellazzi, Gloria; Casiraghi, Letizia; Sinforiani, Elena; Vitali, Paolo; Gandini Wheeler-Kingshott, Claudia A. M.; D'Angelo, Egidio

    2016-01-01

    Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a severe derangement of cognitive functions, primarily memory, in elderly subjects. As far as the functional impairment is concerned, growing evidence supports the “disconnection syndrome” hypothesis. Recent investigations using fMRI have revealed a generalized alteration of resting state networks (RSNs) in patients affected by AD and mild cognitive impairment (MCI). However, it was unclear whether the changes in functional connectivity were accompanied by corresponding structural network changes. In this work, we have developed a novel structural/functional connectomic approach: resting state fMRI was used to identify the functional cortical network nodes and diffusion MRI to reconstruct the fiber tracts to give a weight to internodal subcortical connections. Then, local and global efficiency were determined for different networks, exploring specific alterations of integration and segregation patterns in AD and MCI patients compared to healthy controls (HC). In the default mode network (DMN), that was the most affected, axonal loss, and reduced axonal integrity appeared to compromise both local and global efficiency along posterior-anterior connections. In the basal ganglia network (BGN), disruption of white matter integrity implied that main alterations occurred in local microstructure. In the anterior insular network (AIN), neuronal loss probably subtended a compromised communication with the insular cortex. Cognitive performance, evaluated by neuropsychological examinations, revealed a dependency on integration and segregation of brain networks. These findings are indicative of the fact that cognitive deficits in AD could be associated not only with cortical alterations (revealed by fMRI) but also with subcortical alterations (revealed by diffusion MRI) that extend beyond the areas primarily damaged by neurodegeneration, toward the support of an emerging concept of AD as a

  2. Solution and crystal structure of BA42, a protein from the Antarctic bacterium Bizionia argentinensis comprised of a stand-alone TPM domain.

    PubMed

    Aran, Martin; Smal, Clara; Pellizza, Leonardo; Gallo, Mariana; Otero, Lisandro H; Klinke, Sebastián; Goldbaum, Fernando A; Ithurralde, Esteban R; Bercovich, Andrés; Mac Cormack, Walter P; Turjanski, Adrián G; Cicero, Daniel O

    2014-11-01

    The structure of the BA42 protein belonging to the Antarctic flavobacterium Bizionia argentinensis was determined by nuclear magnetic resonance and X-ray crystallography. This is the first structure of a member of the PF04536 family comprised of a stand-alone TPM domain. The structure reveals a new topological variant of the four β-strands constituting the central β-sheet of the αβα architecture and a double metal binding site stabilizing a pair of crossing loops, not observed in previous structures of proteins belonging to this family. BA42 shows differences in structure and dynamics in the presence or absence of bound metals. The affinity for divalent metal ions is close to that observed in proteins that modulate their activity as a function of metal concentration, anticipating a possible role for BA42.

  3. Structural controls, alteration, permeability and thermal regime of Dixie Valley from new-generation MT/galvanic array profiling

    SciTech Connect

    Philip E. Wannamaker

    2007-11-30

    State-of-the-art MT array measurements in contiguous bipole deployments across the Dixie Valley thermal area have been integrated with regional MT transect data and other evidence to address several basic geothermal goals. These include 1), resolve a fundamental structural ambiguity at the Dixie Valley thermal area (single rangefront fault versus shallower, stepped pediment; 2), delineate fault zones which have experienced fluid flux as indicated by low resistivity; 3), infer ultimate heat and fluid sources for the thermal area; and 4), from a generic technique standpoint, investigate the capability of well-sampled electrical data for resolving subsurface structure. Three dense lines cross the Senator Fumaroles area, the Cottonwood Creek and main producing area, and the low-permeability region through the section 10-15 area, and have stand-alone MT soundings appended at one or both ends for local background control. Regularized 2-D inversion implies that shallow pediment basement rocks extend for a considerable distance (1-2 km) southeastward from the topographic scarp of the Stillwater Range under all three dense profiles, but especially for the Senator Fumaroles line. This result is similar to gravity interpretations in the area, but with the intrinsic depth resolution possible from EM wave propagation. Low resistivity zones flank the interpreted main offsetting fault especially toward the north end of the field which may be due to alteration from geothermal fluid outflow and upflow. The appended MT soundings help to substantiate a deep, subvertical conductor intersecting the base of Dixie Valley from the middle crust, which appears to be a hydrothermal conduit feeding from deep crustal magmatic underplating. This may supply at least part of the high temperature fluids and explain enhanced He-3 levels in those fluids.

  4. Structural hippocampal network alterations during healthy aging: a multi-modal MRI study

    PubMed Central

    Pelletier, Amandine; Periot, Olivier; Dilharreguy, Bixente; Hiba, Bassem; Bordessoules, Martine; Pérès, Karine; Amieva, Hélène; Dartigues, Jean-François; Allard, Michèle; Catheline, Gwénaëlle

    2013-01-01

    While hippocampal atrophy has been described during healthy aging, few studies have examined its relationship with the integrity of White Matter (WM) connecting tracts of the limbic system. This investigation examined WM structural damage specifically related to hippocampal atrophy in healthy aging subjects (n = 129), using morphological MRI to assess hippocampal volume and Diffusion Tensor Imaging (DTI) to assess WM integrity. Subjects with Mild Cognitive Impairment (MCI) or dementia were excluded from the analysis. In our sample, increasing age was significantly associated with reduced hippocampal volume and reduced Fractional Anisotropy (FA) at the level of the fornix and the cingulum bundle. The findings also demonstrate that hippocampal atrophy was specifically associated with reduced FA of the fornix bundle, but it was not related to alteration of the cingulum bundle. Our results indicate that the relationship between hippocampal atrophy and fornix FA values is not due to an independent effect of age on both structures. A recursive regression procedure was applied to evaluate sequential relationships between the alterations of these two brain structures. When both hippocampal atrophy and fornix FA values were included in the same model to predict age, fornix FA values remained significant whereas hippocampal atrophy was no longer significantly associated with age. According to this latter finding, hippocampal atrophy in healthy aging could be mediated by a loss of fornix connections. Structural alterations of this part of the limbic system, which have been associated with neurodegeneration in Alzheimer's disease, result at least in part from the aging process. PMID:24367331

  5. Neonatal handling alters the structure of maternal behavior and affects mother-pup bonding.

    PubMed

    Reis, A R; de Azevedo, M S; de Souza, M A; Lutz, M L; Alves, M B; Izquierdo, I; Cammarota, M; Silveira, P P; Lucion, A B

    2014-05-15

    During early life, a mother and her pups establish a very close relationship, and the olfactory learning of the nest odor is very important for the bond formation. The olfactory bulb (OB) is a structure that plays a fundamental role in the olfactory learning (OL) mechanism that also involves maternal behavior (licking and contact). We hypothesized that handling the pups would alter the structure of the maternal behavior, affect OL, and alter mother-pup relationships. Moreover, changes in the cyclic AMP-response element binding protein phosphorylation (CREB) and neurotrophic factors could be a part of the mechanism of these changes. This study aimed to analyze the effects of neonatal handling, 1 min per day from postpartum day 1 to 10 (PPD 1 to PPD 10), on the maternal behavior and pups' preference for the nest odor in a Y maze (PPD 11). We also tested CREB's phosphorylation and BDNF signaling in the OB of the pups (PPD 7) by Western blot analysis. The results showed that handling alters mother-pups interaction by decreasing mother-pups contact and changing the temporal pattern of all components of the maternal behavior especially the daily licking and nest-building. We found sex-dependent changes in the nest odor preference, CREB and BDNF levels in pups OB. Male pups were more affected by alterations in the licking pattern, and female pups were more affected by changes in the mother-pup contact (the time spent outside the nest and nursing).

  6. A stand-alone tree demography and landscape structure module for Earth system models: integration with inventory data from temperate and boreal forests

    NASA Astrophysics Data System (ADS)

    Haverd, V.; Smith, B.; Nieradzik, L. P.; Briggs, P. R.

    2014-08-01

    Poorly constrained rates of biomass turnover are a key limitation of Earth system models (ESMs). In light of this, we recently proposed a new approach encoded in a model called Populations-Order-Physiology (POP), for the simulation of woody ecosystem stand dynamics, demography and disturbance-mediated heterogeneity. POP is suitable for continental to global applications and designed for coupling to the terrestrial ecosystem component of any ESM. POP bridges the gap between first-generation dynamic vegetation models (DVMs) with simple large-area parameterisations of woody biomass (typically used in current ESMs) and complex second-generation DVMs that explicitly simulate demographic processes and landscape heterogeneity of forests. The key simplification in the POP approach, compared with second-generation DVMs, is to compute physiological processes such as assimilation at grid-scale (with CABLE (Community Atmosphere Biosphere Land Exchange) or a similar land surface model), but to partition the grid-scale biomass increment among age classes defined at sub-grid-scale, each subject to its own dynamics. POP was successfully demonstrated along a savanna transect in northern Australia, replicating the effects of strong rainfall and fire disturbance gradients on observed stand productivity and structure. Here, we extend the application of POP to wide-ranging temporal and boreal forests, employing paired observations of stem biomass and density from forest inventory data to calibrate model parameters governing stand demography and biomass evolution. The calibrated POP model is then coupled to the CABLE land surface model, and the combined model (CABLE-POP) is evaluated against leaf-stem allometry observations from forest stands ranging in age from 3 to 200 year. Results indicate that simulated biomass pools conform well with observed allometry. We conclude that POP represents an ecologically plausible and efficient alternative to large-area parameterisations of woody

  7. Development processes and growth pattern of Pinus densiflora stands in central eastern Korea.

    PubMed

    Park, Pil Sun; Kim, Kyung Yoon; Han, Ahreum; Jang, Woongsoon; Son, Yowhan; Yi, Myong Jong; Park, Byung Bae; Son, Yeongmo

    2010-07-01

    Stand growth and developmental processes were investigated in Pinus densiflora Siebold et Zucc. stands of different ages in the central eastern region of Korea. Stands were inventoried and five trees per stand were sampled for stem analysis, age estimation, and growth analysis. More than 80% of sampled trees in a stand were established within 3-5 years, and most stands had a single cohort structure. The initial growth of pine seedlings was slow, but the height growth accelerated beyond 2-3 m height, 5-10 years after establishment. Linear growth was maintained until 10-12 m height, at which suppressed trees fell behind and might die out. The young stand was composed of pure pines, while few pine seedlings and saplings were found in the understory of older stands. The peak of diameter growth rate occurred around 5-15 years after tree establishment, implying that competition begins during that period. The pine stand development follows four stages: (1) the young stage when the growth rate increases and peaks; (2) the height competition stage when trees focus on height growth for light while maintaining a narrow DBH and height distribution; (3) the differentiation stage when suppressed trees die out, and the DBH distribution becomes wider; and (4) the mature stage when stands have a multi-canopy structure with a wide DBH and height distribution, while the understory is dominated by other tree species. The changes in growth rates and stand structure through forest development would be implemented to predict alterations of above-ground carbon sequestration rates.

  8. Label-free optical quantification of structural alterations in Alzheimer’s disease

    NASA Astrophysics Data System (ADS)

    Lee, Moosung; Lee, Eeksung; Jung, Jaehwang; Yu, Hyeonseung; Kim, Kyoohyun; Yoon, Jonghee; Lee, Shinhwa; Jeong, Yong; Park, Yongkeun

    2016-08-01

    We present a wide-field quantitative label-free imaging of mouse brain tissue slices with sub-micrometre resolution, employing holographic microscopy and an automated scanning platform. From the measured light field images, scattering coefficients and anisotropies are quantitatively retrieved by using the modified the scattering-phase theorem, which enables access to structural information about brain tissues. As a proof of principle, we demonstrate that these scattering parameters enable us to quantitatively address structural alteration in the brain tissues of mice with Alzheimer’s disease.

  9. Label-free optical quantification of structural alterations in Alzheimer’s disease

    PubMed Central

    Lee, Moosung; Lee, Eeksung; Jung, JaeHwang; Yu, Hyeonseung; Kim, Kyoohyun; Yoon, Jonghee; Lee, Shinhwa; Jeong, Yong; Park, YongKeun

    2016-01-01

    We present a wide-field quantitative label-free imaging of mouse brain tissue slices with sub-micrometre resolution, employing holographic microscopy and an automated scanning platform. From the measured light field images, scattering coefficients and anisotropies are quantitatively retrieved by using the modified the scattering-phase theorem, which enables access to structural information about brain tissues. As a proof of principle, we demonstrate that these scattering parameters enable us to quantitatively address structural alteration in the brain tissues of mice with Alzheimer’s disease. PMID:27485313

  10. Structure and function of soil microbial community in artificially planted Sonneratia apetala and S. caseolaris forests at different stand ages in Shenzhen Bay, China.

    PubMed

    Yang, Q; Lei, A P; Li, F L; Liu, L N; Zan, Q J; Shin, P K S; Cheung, S G; Tam, N F Y

    2014-08-30

    The present study examined the relationships between soil characteristics, microbial community structure and function in the forests artificially planted with exotic Sonneratia apetala at stand ages of 1-, 2-, 7-, 10- and 14-years and Sonneratia caseolaris of 1-, 4-, 7-, 10- and 14-years in Futian National Nature Reserve, Shenzhen Bay, China. The 7-years old forests of both Sonneratia species reached peak growth and had the highest content of nitrogen and phosphorus, enzymatic activities, including dehydrogenase, cellulase, phosphatase, urease and ß-glucosidase, except arylsulphatase which increased continuously with stand ages. The microbial community structure reflected by phospholipid fatty acid (PLFA) profiles also reached the maximum value in the 7-years old forests and soil bacterial PLFAs in both forests were significantly higher than fungal PLFAs. The canonical correlation analysis revealed that differences in microbial structural variables were significantly correlated to the differences in their functional variables, and the highest correlation was found between the soil enzymatic activities and the content of carbon and nitrogen.

  11. Estimating structural alterations in animal models of lung emphysema. Is there a gold standard?

    PubMed

    Ochs, Matthias

    2014-01-01

    Chronic obstructive pulmonary disease (COPD) is one of the most common lung diseases. The major component of COPD, which affects the gas-exchanging parenchyma of the lung, emphysema, is characterized by destruction of alveolar septae leading to loss of functional surface, loss of alveoli and enlargement of remaining distal airspaces. These microstructural alterations can be modeled in animals and can be measured using stereological methods applied to imaging datasets. Many animal models of emphysema exist, but most of them are insufficiently characterized with respect to the underlying nature (e.g. destructive or developmental) and the degree of the structural alterations. The most popular parameter for assessment of emphysematous alterations, mean linear intercept length, has severe limitations. It can, therefore, not be recommended. Better design-based stereological alternatives exist but are less often applied, such as total volumes of parenchymal compartments (alveolar airspace, alveolar duct airspace, alveolar septum), total alveolar surface area, total alveolar number and mean alveolar size and its size variation. A prerequisite is the use of appropriate fixation, sampling, and specimen processing protocols. This article reviews the challenges of stereologic assessment of emphysematous alterations in the lung and illustrates possible strategies.

  12. Altered Modular Organization of Structural Cortical Networks in Children with Autism

    PubMed Central

    Shi, Feng; Wang, Li; Peng, Ziwen; Wee, Chong-Yaw; Shen, Dinggang

    2013-01-01

    Autism is a complex developmental disability that characterized by deficits in social interaction, language skills, repetitive stereotyped behaviors and restricted interests. Although great heterogeneity exists, previous findings suggest that autism has atypical brain connectivity patterns and disrupted small-world network properties. However, the organizational alterations in the autistic brain network are still poorly understood. We explored possible organizational alterations of 49 autistic children and 51 typically developing controls, by investigating their brain network metrics that are constructed upon cortical thickness correlations. Three modules were identified in controls, including cortical regions associated with brain functions of executive strategic, spatial/auditory/visual, and self-reference/episodic memory. There are also three modules found in autistic children with similar patterns. Compared with controls, autism demonstrates significantly reduced gross network modularity, and a larger number of inter-module connections. However, the autistic brain network demonstrates increased intra- and inter-module connectivity in brain regions including middle frontal gyrus, inferior parietal gyrus, and cingulate, suggesting one underlying compensatory mechanism associated with brain functions of self-reference and episodic memory. Results also show that there is increased correlation strength between regions inside frontal lobe, as well as impaired correlation strength between frontotemporal and frontoparietal regions. This alteration of correlation strength may contribute to the organization alteration of network structures in autistic brains. PMID:23675456

  13. Connectomics-based structural network alterations in obsessive-compulsive disorder

    PubMed Central

    Reess, T J; Rus, O G; Schmidt, R; de Reus, M A; Zaudig, M; Wagner, G; Zimmer, C; van den Heuvel, M P; Koch, K

    2016-01-01

    Given the strong involvement of affect in obsessive-compulsive disorder (OCD) and recent findings, the current cortico-striato-thalamo-cortical (CSTC) model of pathophysiology has repeatedly been questioned regarding the specific role of regions involved in emotion processing such as limbic areas. Employing a connectomics approach enables us to characterize structural connectivity on a whole-brain level, extending beyond the CSTC circuitry. Whole-brain structural networks of 41 patients and 42 matched healthy controls were analyzed based on 83 × 83 connectivity matrices derived from cortical and subcortical parcellation of structural T1-weighted magnetic resonance scans and deterministic fiber tracking based on diffusion tensor imaging data. To assess group differences in structural connectivity, the framework of network-based statistic (NBS) was applied. Graph theoretical measures were calculated to further assess local and global network characteristics. The NBS analysis revealed a single network consistently displaying decreased structural connectivity in patients comprising orbitofrontal, striatal, insula and temporo-limbic areas. In addition, graph theoretical measures indicated local alterations for amygdala and temporal pole while the overall topology of the network was preserved. To the best of our knowledge, this is the first study combining the NBS with graph theoretical measures in OCD. Along with regions commonly described in the CSTC model of pathophysiology, our results indicate an involvement of mainly temporo-limbic regions typically associated with emotion processing supporting their importance for neurobiological alterations in OCD. PMID:27598966

  14. Structurally Altered Hard Coal in the Areas of Tectonic Disturbances - An Initial Attempt at Classification

    NASA Astrophysics Data System (ADS)

    Godyń, Katarzyna

    2016-09-01

    As regards the exploitation of hard coal seams, the near-fault zones and faults themselves are considered to be particularly dangerous areas, which is due to a high probability of the occurrence of gasogeodynamic phenomena. Tectonic dislocations running across a seam have a destructive impact on coal. Degradation of the coal structure, particularly visible in the microscale, is reflected in the coal's strength or gas properties. Such "structurally altered" coal is characterized by the presence of numerous fracturings, crushed areas, or dislocations of some of its fragments, and sometimes even the total destruction of the original structure. The present paper provides a detailed analysis and description of near-fault coal obtained from selected seams of the Upper Silesian Coal Basin, completed due to the application of optical methods. Both the type and the degree of changes in the structure of such coal were identified. On this basis, the author attempted to systematize the nomenclature used in relation to selected Upper Silesian hard coal seams, which, in turn, resulted in a proposed classification of the "altered structures" of the near-fault coal.

  15. Altered Regional Gray Matter Volume in Obese Men: A Structural MRI Study

    PubMed Central

    Zhang, Bin; Tian, Xiao; Tian, Derun; Wang, Jinhong; Wang, Qiming; Yu, Chunshui; Li, Chunbo; Wang, Jijun

    2017-01-01

    Obesity is associated with a number of health problems, especial insulin resistance and Type 2 diabetes. Our previous study showed that obese males had decreased neural activity in the orbital frontal cortex (OFC) and increased activity in the left putamen (Zhang et al., 2015b), which could indicate altered eating behaviors in obesity related to a hyper-functioning striatum and hypo-functioning inhibitory control. Accordingly, our goal of the current study was to determine whether there are alterations in the brain structures within these two neural systems in obese individuals. Twenty obese men (age: 20–28 years) and 20 age-matched lean male subjects were involved in the current study. Plasma glucose and insulin were tested during hunger state, and homeostasis model assessment of insulin resistance (HOMA-IR) was based on the blood samples. In the study, we used structural MRI and a voxel-based morphometry (VBM) method to investigate regional structures in obese subjects and find out whether there are correlations between the insulin and the brain structures. We found that obese men only showed a significantly increased gray matter volume (GMV) in the left putamen and that the GMV of the left putamen was positively correlated with body mass index, plasma insulin and HOMA-IR. The putamen is a core region participating in insulin signal regulation, and our results showed an abnormal GMV of the putamen is a core alternation in aberrant insulin. Furthermore, the GMV of the OFC was negatively correlated with hunger rating, despite there being no significant difference between the two groups in the OFC. In conclusion, the altered structure and function of the putamen could play important roles in obesity and aberrant insulin. PMID:28197123

  16. Structural health monitoring (vibration) as a tool for identifying structural alterations of the lumbar spine: a twin control study.

    PubMed

    Kawchuk, Gregory N; Hartvigsen, Jan; Edgecombe, Tiffany; Prasad, Narasimha; van Dieen, Jaap H

    2016-03-11

    Structural health monitoring (SHM) is an engineering technique used to identify mechanical abnormalities not readily apparent through other means. Recently, SHM has been adapted for use in biological systems, but its invasive nature limits its clinical application. As such, the purpose of this project was to determine if a non-invasive form of SHM could identify structural alterations in the spines of living human subjects. Lumbar spines of 10 twin pairs were visualized by magnetic resonance imaging then assessed by a blinded radiologist to determine whether twin pairs were structurally concordant or discordant. Vibration was then applied to each subject's spine and the resulting response recorded from sensors overlying lumbar spinous processes. The peak frequency, area under the curve and the root mean square were computed from the frequency response function of each sensor. Statistical analysis demonstrated that in twins whose structural appearance was discordant, peak frequency was significantly different between twin pairs while in concordant twins, no outcomes were significantly different. From these results, we conclude that structural changes within the spine can alter its vibration response. As such, further investigation of SHM to identify spinal abnormalities in larger human populations is warranted.

  17. N6-methyladenosine alters RNA structure to regulate binding of a low-complexity protein.

    PubMed

    Liu, Nian; Zhou, Katherine I; Parisien, Marc; Dai, Qing; Diatchenko, Luda; Pan, Tao

    2017-02-25

    N6-methyladenosine (m6A) is the most abundant internal modification in eukaryotic messenger RNA (mRNA), and affects almost every stage of the mRNA life cycle. The YTH-domain proteins can specifically recognize m6A modification to control mRNA maturation, translation and decay. m6A can also alter RNA structures to affect RNA-protein interactions in cells. Here, we show that m6A increases the accessibility of its surrounding RNA sequence to bind heterogeneous nuclear ribonucleoprotein G (HNRNPG). Furthermore, HNRNPG binds m6A-methylated RNAs through its C-terminal low-complexity region, which self-assembles into large particles in vitro. The Arg-Gly-Gly repeats within the low-complexity region are required for binding to the RNA motif exposed by m6A methylation. We identified 13,191 m6A sites in the transcriptome that regulate RNA-HNRNPG interaction and thereby alter the expression and alternative splicing pattern of target mRNAs. Low-complexity regions are pervasive among mRNA binding proteins. Our results show that m6A-dependent RNA structural alterations can promote direct binding of m6A-modified RNAs to low-complexity regions in RNA binding proteins.

  18. Forest to reclaimed mine land use change leads to altered ecosystem structure and function

    SciTech Connect

    Simmons, J.A.; Currie, W.S.; Eshleman, K.N.; Kuers, K.; Monteleone, S.; Negley, T.L.; Pohlad, B.R.; Thomas, C.L.

    2008-01-15

    The United States' use of coal results in many environmental alterations. In the Appalachian coal belt region, one widespread alteration is conversion of forest to reclaimed mineland. The goal of this study was to quantify the changes to ecosystem structure and function associated with a conversion from forest to reclaimed mine grassland by comparing a small watershed containing a 15-year-old reclaimed mine with a forested, reference watershed in western Maryland. Major differences were apparent between the two watersheds in terms of biogeochemistry. Total C, N, and P pools were all substantially lower at the mined site, mainly due to the removal of woody biomass but also, in the case of P, to reductions in soil pools. Mineral soil C, N, and P pools were 96%, 79%, and 69% of native soils, respectively. Although annual runoff from the watersheds was similar, the mined watershed exhibited taller, narrower storm peaks as a result of a higher soil bulk density and decreased infiltration rates. Stream export of N was much lower in the mined watershed due to lower net nitrification rates and nitrate concentrations in soil. However, stream export of sediment and P and summer stream temperature were much higher. Stream leaf decomposition was reduced and macroinvertebrate community structure was altered as a result of these changes to the stream environment. This land use change leads to substantial, long-term changes in ecosystem capital and function.

  19. Structural alteration of carbon nanoparticle and carbon nanoparticles carrying Pt clusters

    NASA Astrophysics Data System (ADS)

    Shintaku, Masayuki; Suzuki, Hitoshi; Sato, Takeshi; Tamano, Masayuki; Matsuura, Toyoaki; Hori, Michio; Kaito, Chihiro

    2005-06-01

    Alterations of carbon particles carrying Pt clusters were studied by means of transmission electron microscopy (TEM). Carbon particles of size 20-30 nm produced in a He gas atmosphere by the conventional arc-discharge method changed into carbon tubes or ribbon-like spherules based on an onion-like structure by heating in air at 300 °C. In the case of carbon particles carrying Pt clusters, the alteration of carbon particles took place gradually at 300 °C, and the Pt clusters become partially exposed to the air as they were no longer covered by the carbon layer. The generation of electricity by using Pt clusters in fuel cell is proposed as an application for the Pt clusters.

  20. Hemin/G-quadruplex structure and activity alteration induced by magnesium cations.

    PubMed

    Kosman, J; Juskowiak, B

    2016-04-01

    The influence of metal cations on G-quadruplex structure and peroxidase-mimicking DNAzyme activity was investigated. Experiments revealed a significant role of magnesium ion, which in the presence of potassium cation influenced DNAzyme activity. This ability has been associated with alteration of G-quadruplex topology and consequently affinity to bind hemin molecule. It has been demonstrated that G-quadruplex based on PS2.M sequence under these conditions formed parallel topology, which exhibited lower activity than that observed in standard potassium-containing solution. On the other hand DNAzyme/magnesium ion system based on telomeric sequence, which did not undergo significant structural changes, exhibited higher peroxidase activity upon magnesium ion addition. In both cases, the stabilization effect of magnesium cations on G-quadruplex structure was observed. The mechanism of DNAzyme activity alteration by magnesium ion can be explained by its influence on the pKa value of DNAzyme. Magnesium ion decreased pKa for PS2.M based system but increased it for telomeric DNAzyme. Magnesium cation effect on G-quadruplex structure as well as DNAzyme activity is particularly important since this ion is one of the most common metal cations in biological samples.

  1. Use of monoclonal antibodies in the detection of structural alterations occurring in lysozyme on heating.

    PubMed

    Kenett, D; Katchalski-Katzir, E; Fleminger, G

    1990-01-01

    Seven murine anti-hen egg-white lysozyme (HEL) monoclonal antibodies (MAbs), which recognize distinct epitopes of the native enzyme, were used as macromolecular probes to detect structural or conformational alterations occurring in HEL on heating at 95 degrees C, pH 5. As the interactions of the heat-treated HEL with its corresponding MAbs were carried out at room temperature, only irreversible structural and/or conformational alterations could be detected. The transformation of the native enzyme into its denatured form was followed electrophoretically and chromatographically. The denatured enzyme was more negatively charged at pH 8.4 and exhibited a longer retention time on reverse-phase HPLC than native HEL. Its specific catalytic activity was considerably lower than that of the native enzyme. Of the seven MAbs tested in competitive ELISA assays with native and heat-treated HEL only one, MAb D74.3, failed to recognize the heat-treated enzyme. This antibody, which is directed toward the active site region of the enzyme, was ineffective in inhibiting the catalytic activity of the heat-treated HEL using M. lysodeikticus as substrate. In contrast, the monoclonal antibody D1.3, which recognizes an epitope remote from the active site of HEL, inhibited the catalytic activity of the native as well as the heat-treated enzyme. The results indicate that the active site of HEL undergoes an irreversible structural alteration on heating for 2 hr at 95 degrees C, pH 5. No irreversible structural changes could be detected in the other regions of HEL recognized by the corresponding MAbs.

  2. 2015 Sensorimotor Risk Standing Review Panel Evidence and Status Review For: the Risk of Impaired Control of Spacecraft/Associated Systems and Decreased Mobility Due to Vestibular/Sensorimotor Alterations Associated with Spaceflight

    NASA Technical Reports Server (NTRS)

    Steinberg, Susan

    2015-01-01

    The 2015 Sensorimotor Risk Standing Review Panel (from here on referred to as the SRP) participated in a WebEx/teleconference with members of the Human Health Countermeasures (HHC) Element, representatives from the Human Research Program (HRP), NASA Headquarters, and NASA Research and Education Support Services (NRESS) on December 17, 2015 (list of participants is in Section VI of this report). The SRP reviewed the new Evidence Report for the Risk of Impaired Control of Spacecraft/Associated Systems and Decreased Mobility Due to Vestibular/Sensorimotor Alterations Associated with Spaceflight (from here on referred to as the 2015 Sensorimotor Evidence Report), and also received a status review of the Risk. The opening section of the 2015 Sensorimotor Evidence Report provides written descriptions of various incidents that have occurred during space missions. In most of these incidents, the main underlying contributing factors are not easy to identify unambiguously. For example, in section 1.9, a number of falls occurred while astronauts were walking on the moon. It is not clear to the SRP, however, why they fell. It is only possible to extrapolate from likely specific psychophysical or physiological abnormalities, but how these abnormalities were determined, and how they were directly responsible for the falls is unclear to the SRP. Section 2.1.2 on proprioception is very interesting, but the functional significance of the abnormalities detected is not clear. The SRP sees this as a problem throughout the report: a mapping between the component abnormalities identified and the holistic behaviors that are most relevant, for example, controlling the vehicle, and locomotion during egress, is generally lacking. The SRP thinks the cognitive section is too strongly focused on vestibular functioning. The SRP questions the notion that the main cognitive effects are mainly attributable to reversible vestibular changes induced by spaceflight. The SRP thinks that there can also

  3. Standing equine dental surgery.

    PubMed

    Menzies, Robert A; Easley, Jack

    2014-04-01

    Dental surgeries refer to procedures that affect the dental tissues or their supporting structures. With the development of specific, efficacious, and conservative treatments, morbidity risks have been lowered and chances of benefiting the health of equids improved. Advances in quality of sedation, analgesia, and locoregional anesthesia allow a majority of dental surgeries to be performed in the standing patient. This update focuses on an orthograde endodontic technique, a minimally invasive buccotomy technique, with the potential to combine it with a transbuccal screw extraction technique, and revisits the AO pinless external fixator for fractures of the body of the mandible.

  4. Standing footprint diagnostic method

    NASA Astrophysics Data System (ADS)

    Fan, Y. F.; Fan, Y. B.; Li, Z. Y.; Newman, T.; Lv, C. S.; Fan, Y. Z.

    2013-10-01

    Center of pressure is commonly used to evaluate standing balance. Even though it is incomplete, no better evaluation method has been presented. We designed our experiment with three standing postures: standing with feet together, standing with feet shoulder width apart, and standing with feet slightly wider than shoulder width. Our platform-based pressure system collected the instantaneous plantar pressure (standing footprint). A physical quantity of instantaneous standing footprint principal axis was defined, and it was used to construct an index to evaluate standing balance. Comparison between results from our newly established index and those from the center of pressure index to evaluate the stability of different standing postures revealed that the standing footprint principal axis index could better respond to the standing posture change than the existing one. Analysis indicated that the insensitive response to the relative position between feet and to the standing posture change from the center of pressure could be better detected by the standing footprint principal axis index. This predicts a wide application of standing footprint principal axis index when evaluating standing balance.

  5. Petrography, geochemistry, and alteration of country rocks from the Bosumtwi impact structure, Ghana

    NASA Astrophysics Data System (ADS)

    Karikari, Forson; Ferrière, Ludovic; Koeberl, Christian; Reimold, Wolf Uwe; Mader, Dieter

    Samples of the country rocks that likely constituted the target rocks at the 1.07 Myr old Bosumtwi impact structure in Ghana, West Africa, collected outside of the crater rim in the northern and southern parts of the structure, were studied for their petrographic characteristics and analyzed for their major- and trace-element compositions. The country rocks, mainly meta-graywacke, shale, and phyllite of the Early Proterozoic Birimian Supergroup and some granites of similar age, are characterized by two generations of alteration. A pre-impact hydrothermal alteration, often along shear zones, is characterized by new growth of secondary minerals, such as chlorite, sericite, sulfides, and quartz, or replacement of some primary minerals, such as plagioclase and biotite, by secondary sericite and chlorite. A late, argillic alteration, mostly associated with the suevites, is characterized by alteration of the melt/glass clasts in the groundmass of suevites to phyllosilicates. Suevite, which occurs in restricted locations to the north and to the south-southwest of the crater rim, contains melt fragments, diaplectic quartz glass, ballen quartz, and clasts derived from the full variety of target rocks. No planar deformation features (PDFs) in quartz were found in the country rock samples, and only a few quartz grains in the suevite samples show PDFs, and in rare cases two sets of PDFs. Based on a total alkali element-silica (TAS) plot, the Bosumtwi granites have tonalitic to quartz-dioritic compositions. The Nb versus Y and Ta versus Yb discrimination plots show that these granites are of volcanic-arc tectonic provenance. Provenance studies of the metasedimentary rocks at the Bosumtwi crater have also indicated that the metasediments are volcanic-arc related. Compared to the average siderophile element contents of the upper continental crust, both country rocks and impact breccias of the Bosumtwi structure show elevated siderophile element contents. This, however, does not

  6. Fabrication of thickness controllable free-standing sandwich-structured hybrid carbon film for high-rate and high-power supercapacitor

    PubMed Central

    Wei, Helin; Wei, Sihang; Tian, Weifeng; Zhu, Daming; Liu, Yuhao; Yuan, Lili; Li, Xin

    2014-01-01

    Hybrid carbon films composed of graphene film and porous carbon film may give full play to the advantages of both carbon materials, and have great potential for application in energy storage and conversion devices. Unfortunately, there are very few reports on fabrication of hybrid carbon films. Here we demonstrate a simple approach to fabricate free-standing sandwich-structured hybrid carbon film composed of porous amorphous carbon film and multilayer graphene film by chemical vapor deposition in a controllable and scalable way. Hybrid carbon films reveal good electrical conductivity, excellent flexibility, and good compatibility with substrate. Supercapacitors assembled by hybrid carbon films exhibit ultrahigh rate capability, wide frequency range, good capacitance performance, and high-power density. Moreover, this approach may provide a general path for fabrication of hybrid carbon materials with different structures by using different metals with high carbon solubility, and greatly expands the application scope of carbon materials. PMID:25394410

  7. Impact of the Mountain Pine Beetle on the net Ecosystem Productivity of Lodgepole Pine Stands and the Role of Secondary Structure

    NASA Astrophysics Data System (ADS)

    Brown, M.; Black, T.; Nesic, Z.; Spilttlehouse, D.; Trofymow, T.; Fredeen, A.; Egginton, V.; Burton, P.; Grant, N.

    2009-05-01

    British Columbia, Canada is experiencing a severe mountain pine beetle (MPB) epidemic extending over an area of 135,000 km2. The widespread mortality of lodgepole pine caused by the beetle is having severe implications for Canada's carbon (C) budget. This study used the eddy-covariance technique to examine how the beetle is affecting the net ecosystem productivity (NEP) of two attacked lodgepole pine stands in the central interior of BC over 2 years. MPB-KS is an 83-year-old stand that was first attacked in 2006. By the start of 2007, roughly 60% of the canopy had been beetle attacked and by August 2008 only 21% of the canopy remained healthy. MPB-CR, a 110-year-old stand, first attacked by the beetle in 2003, had >95% pine mortality in 2007, and also differed from MPB-KS in that it had a developed secondary structure (seedlings, saplings, sub- canopy and canopy trees that survive a beetle attack) (SS) and deciduous ground layer. In 2007, MPB-KS had an annual and growing season (GS) NEP of -55 and 36 g C m-2, and in 2008, an annual and GS NEP of -42 and 34 g C m-2, respectively. MPB-CR had an annual and GS NEP of -22 and 23 g C m-2 in 2007 and 2 and 75 g C m-2 in 2008. In both years, MPB-KS was a GS C sink due to the productivity of the healthy portion of the canopy, the many seedlings and the mossy surface layer. Between 2007 and 2008, MPB-CR experienced a reduction in LAI (from 0.91 to 0.78), due to needle-fall, which led to an opening up of the canopy and resulted in a high SS C uptake in 2008. These results were confirmed by foliar CO2 exchange measurements which showed a high productivity for the SS and deciduous vegetation.

  8. A MYLK variant regulates asthmatic inflammation via alterations in mRNA secondary structure

    PubMed Central

    Wang, Ting; Zhou, Tong; Saadat, Laleh; Garcia, Joe GN

    2015-01-01

    Myosin light-chain kinase (MYLK) is a gene known to be significantly associated with severe asthma in African Americans. Here we further examine the molecular function of a single-nucleotide polymorphism (SNP), located in the non-muscle myosin light-chain kinase isoform (nmMLCK), in asthma susceptibility and pathobiology. We identified nmMLCK variant (reference SNP: rs9840993, NM_053025: 721C>T, c.439C>T) with a distinct mRNA secondary structure from the other variants. The nmMLCK variant (721C) secondary structure exhibits increased stability with an elongated half-life in the human endothelial cell, and greater efficiency in protein translation initiation owing to an increased accessibility to translation start site. Finally, nmMLCK expression of 721C- and 721T-containing MYLK transgenes were compared in nmMLCK−/− mice and confirmed deleterious effects of nmMLCK expression on asthmatic indices and implicated the augmented influence of MYLK 721C>T (c.439C>T) SNP on asthma severity. The confirmation of the novel mechanism of the regulation of asthmatic inflammation by a MYLK advances knowledge of the genetic basis for asthma disparities, and further suggests the potential of nmMLCK as a therapeutic target. Our study suggests that in addition to altering protein structure and function, non-synonymous SNPs may also lead to phenotypic disparity by altering protein expression. PMID:25271083

  9. Structural and functional alterations of catalase induced by acriflavine, a compound causing apoptosis and necrosis.

    PubMed

    Attar, Farnoosh; Khavari-Nejad, Sarah; Keyhani, Jacqueline; Keyhani, Ezzatollah

    2009-08-01

    Acriflavine is an antiseptic agent causing both apoptosis and necrosis in yeast. In this work, its effect on the structure and function of catalase, a vital enzyme actively involved in protection against oxidative stress, was investigated. In vitro kinetic studies showed that acriflavine inhibited the enzymatic activity in a competitive manner. The residual activity detectable after preincubation of catalase (1.5 nmol/L) with various concentrations of acriflavine went from 50% to 20% of the control value as the acriflavine concentration increased from 30 to 90 micromol/L. Correlatively with the decrease in activity, alterations in the enzyme's conformation were observed as indicated by fluorescence spectroscopy, circular dichroism spectroscopy, and electronic absorption spectroscopy. The enzyme's intrinsic fluorescence obtained upon excitation at either 297 nm (tryptophan residues) or 280 nm (tyrosine and tryptophan residues) decreased as a function of acriflavine concentration. Circular dichroism studies showed alterations of the protein structure by acriflavine with up to 13% decrease in alpha helix, 16% increase in beta-sheet content, 17% increase in random coil, and 4% increase in beta turns. Spectrophotometric studies showed a blueshift and modifications in the chromicity of catalase at 405 nm, corresponding to an absorbance band due to the enzyme's prosthetic group. Thus, acriflavine induced in vitro a profound change in the structure of catalase so that the enzyme could no longer function. Our results showed that acriflavine, a compound producing apoptosis and necrosis, can have a direct effect on vital functions in cells by disabling key enzymes.

  10. Rim Structure, Stratigraphy, and Aqueous Alteration Exposures Along Opportunity Rover's Traverse of the Noachian Endeavour Crater

    NASA Technical Reports Server (NTRS)

    Crumpler, L.S.; Arvidson, R. E.; Golombek, M.; Grant, J. A.; Jolliff, B. L.; Mittlefehldt, D. W.

    2017-01-01

    The Mars Exploration Rover Opportunity has traversed 10.2 kilometers along segments of the west rim of the 22-kilometer-diameter Noachian Endeavour impact crater as of sol 4608 (01/09/17). The stratigraphy, attitude of units, lithology, and degradation state of bedrock outcrops exposed on the crater rim have been examined in situ and placed in geologic context. Structures within the rim and differences in physical properties of the identified lithologies have played important roles in localizing outcrops bearing evidence of aqueous alteration.

  11. Does methyl isocyante interaction with normal hemoglobin alter its structure and function

    SciTech Connect

    Jeevaratnam, K. ); Vaidyanathan, C.S. )

    1992-01-01

    The predominant biological effect of methyl isocyanate (MIC) intoxication in mammals is severe tissue hypoxia leading to acute lactic acidosis. In rabbits administered MIC subcutaneously (s.c.) the hypoxia was shown to be of the stagnant type resulting from hypovolemic hypotension. The occurrence of carbamylation of Hb by MIC in vivo was demonstrated unequivocally. Furthermore, the characteristic observation, dark red colored (cherry red) blood in animals exposed to MIC remained unexplained. This prompted the authors to investigate whether MIC exposure caused an alteration in structure and/or function of normal Hb leading to tissue hypoxia and the change in the color of the blood.

  12. Rapid structural alterations of the active zone lead to sustained changes in neurotransmitter release.

    PubMed

    Matz, Jacob; Gilyan, Andrew; Kolar, Annette; McCarvill, Terrence; Krueger, Stefan R

    2010-05-11

    The likelihood with which an action potential elicits neurotransmitter release, the release probability (p(r)), is an important component of synaptic strength. Regulatory mechanisms controlling several steps of synaptic vesicle (SV) exocytosis may affect p(r), yet their relative importance in determining p(r) and eliciting temporal changes in neurotransmitter release at individual synapses is largely unknown. We have investigated whether the size of the active zone cytomatrix is a major determinant of p(r) and whether changes in its size lead to corresponding alterations in neurotransmitter release. We have used a fluorescent sensor of SV exocytosis, synaptophysin-pHluorin, to measure p(r) at individual synapses with high accuracy and employed a fluorescently labeled cytomatrix protein, Bassoon, to quantify the amount of active zone cytomatrix present at these synapses. We find that, for synapses made by a visually identified presynaptic neuron, p(r) is indeed strongly correlated with the amount of active zone cytomatrix present at the presynaptic specialization. Intriguingly, active zone cytomatrices are frequently subject to synapse-specific changes in size on a time scale of minutes. These spontaneous alterations in active zone size are associated with corresponding changes in neurotransmitter release. Our results suggest that the size of the active zone cytomatrix has a large influence on the reliability of synaptic transmission. Furthermore, they implicate mechanisms leading to rapid structural alterations at active zones in synapse-specific forms of plasticity.

  13. Cortical Structure Alterations and Social Behavior Impairment in p50-Deficient Mice

    PubMed Central

    Bonini, Sara Anna; Mastinu, Andrea; Maccarinelli, Giuseppina; Mitola, Stefania; Premoli, Marika; La Rosa, Luca Rosario; Ferrari-Toninelli, Giulia; Grilli, Mariagrazia; Memo, Maurizio

    2016-01-01

    Alterations in genes that regulate neurodevelopment can lead to cortical malformations, resulting in malfunction during postnatal life. The NF-κB pathway has a key role during neurodevelopment by regulating the maintenance of the neural progenitor cell pool and inhibiting neuronal differentiation. In this study, we evaluated whether mice lacking the NF-κB p50 subunit (KO) present alterations in cortical structure and associated behavioral impairment. We found that, compared with wild type (WT), KO mice at postnatal day 2 present an increase in radial glial cells, an increase in Reelin protein expression levels, in addition to an increase of specific layer thickness. Moreover, adult KO mice display abnormal columnar organization in the somatosensory cortex, a specific decrease in somatostatin- and parvalbumin-expressing interneurons, altered neurite orientation, and a decrease in Synapsin I protein levels. Concerning behavior, KO mice, in addition to an increase in locomotor and exploratory activity, display impairment in social behaviors, with a reduction in social interaction. Finally, we found that risperidone treatment decreased hyperactivity of KO mice, but had no effect on defective social interaction. Altogether, these data add complexity to a growing body of data, suggesting a link between dysregulation of the NF-κB pathway and neurodevelopmental disorders pathogenesis. PMID:26946128

  14. Cortical Structure Alterations and Social Behavior Impairment in p50-Deficient Mice.

    PubMed

    Bonini, Sara Anna; Mastinu, Andrea; Maccarinelli, Giuseppina; Mitola, Stefania; Premoli, Marika; La Rosa, Luca Rosario; Ferrari-Toninelli, Giulia; Grilli, Mariagrazia; Memo, Maurizio

    2016-06-01

    Alterations in genes that regulate neurodevelopment can lead to cortical malformations, resulting in malfunction during postnatal life. The NF-κB pathway has a key role during neurodevelopment by regulating the maintenance of the neural progenitor cell pool and inhibiting neuronal differentiation. In this study, we evaluated whether mice lacking the NF-κB p50 subunit (KO) present alterations in cortical structure and associated behavioral impairment. We found that, compared with wild type (WT), KO mice at postnatal day 2 present an increase in radial glial cells, an increase in Reelin protein expression levels, in addition to an increase of specific layer thickness. Moreover, adult KO mice display abnormal columnar organization in the somatosensory cortex, a specific decrease in somatostatin- and parvalbumin-expressing interneurons, altered neurite orientation, and a decrease in Synapsin I protein levels. Concerning behavior, KO mice, in addition to an increase in locomotor and exploratory activity, display impairment in social behaviors, with a reduction in social interaction. Finally, we found that risperidone treatment decreased hyperactivity of KO mice, but had no effect on defective social interaction. Altogether, these data add complexity to a growing body of data, suggesting a link between dysregulation of the NF-κB pathway and neurodevelopmental disorders pathogenesis.

  15. Characterization of pore structure and hydraulic property alteration in pressurized unsaturated flow tests

    SciTech Connect

    McGrail, B. Peter; Lindenmeier, Clark W.; Martin, P F.

    1999-12-01

    The pressurized unsaturated flow (PUF) test is a new experimental method for the evaluation of the long-term corrosion behavior of waste forms and other engineered barrier materials. Essentially, the technique provides a means to flow water through a porous bed of test material or materials at elevated temperature and under hydraulically unsaturated conditions. Bulk volumetric content, effluent pH and electrical conductivity are monitored in real time using a computer control and data acquisition system. In previous papers, we have reported on the changes in bulk water content, effluent chemistry, and glass corrosion rates that result from the formation of alteration products during these tests. These measurements are now supplemented through the use of the ultracentrifugation apparatus (UFA) for hydraulic property measurements and high-resolution, x-ray microtomography (XMT) to provide 3-D spatial and temporal imaging of water distribution and pore structure alteration during these tests. Quantitative changes in the water retention characteristic were correlated with the onset of zeolite formation in the tests. Extensive alteration of the glass resulted in cementation of the glass grains near the bottom of the column, which was observed in situ using the XMT.

  16. Characterization of pore structure and hydraulic property alteration in pressurized unsaturated flow tests

    SciTech Connect

    McGrail, B.P.; Lindenmeier, C.W.; Martin, P.F.

    1999-07-01

    The pressurized unsaturated flow (PUF) test is a new experimental method for the evaluation of the long-term corrosion behavior of waste forms and other engineered barrier materials. Essentially, the technique provides a means to flow water through a porous bed of test material or materials at elevated temperature and under hydraulically unsaturated conditions. Bulk volumetric content, effluent pH and electrical conductivity are monitored in real time using a computer control and data acquisition system. In previous papers, the authors have reported on the changes in bulk water content, effluent chemistry, and glass corrosion rates that result from the formation of alteration products during these tests. These measurements are now supplemented through the use of the ultracentrifugation apparatus (UFA) for hydraulic property measurements and high-resolution, x-ray microtomography (XMT) to provide 3-D spatial and temporal imaging of water distribution and pore structure alteration during these tests. Quantitative changes in the water retention characteristic were correlated with the onset of zeolite formation in the tests. Extensive alteration of the glass resulted in cementation of the glass grains near the bottom of the column, which was observed in situ using the XMT.

  17. Hyperspectral mapping of alteration assemblages within a hydrothermal vug at the Haughton impact structure, Canada

    NASA Astrophysics Data System (ADS)

    Greenberger, Rebecca N.; Mustard, John F.; Osinski, Gordon R.; Tornabene, Livio L.; Pontefract, Alexandra J.; Marion, Cassandra L.; Flemming, Roberta L.; Wilson, Janette H.; Cloutis, Edward A.

    2016-12-01

    Meteorite impacts on Earth and Mars can generate hydrothermal systems that alter the primary mineralogies of rocks and provide suitable environments for microbial colonization. We investigate a calcite-marcasite-bearing vug at the 23 km diameter Haughton impact structure, Devon Island, Nunavut, Canada, using imaging spectroscopy of the outcrop in the field (0.65-1.1 μm) and samples in the laboratory (0.4-2.5 μm), point spectroscopy (0.35-2.5 μm), major element chemistry, and X-ray diffraction analyses. The mineral assemblages mapped at the outcrop include marcasite; marcasite with minor gypsum and jarosite; fibroferrite and copiapite with minor gypsum and melanterite; gypsum, Fe3+ oxides, and jarosite; and calcite, gypsum, clay, microcline, and quartz. Hyperspectral mapping of alteration phases shows spatial patterns that illuminate changes in alteration conditions and formation of specific mineral phases. Marcasite formed from the postimpact hydrothermal system under reducing conditions, while subsequent weathering oxidized the marcasite at low temperatures and water/rock ratios. The acidic fluids resulting from the oxidation collected on flat-lying portions of the outcrop, precipitating fibroferrite + copiapite. That assemblage then likely dissolved, and the changing chemistry and pH resulting from interaction with the calcite-rich host rock formed gypsum-bearing red coatings. These results have implications for understanding water-rock interactions and habitabilities at this site and on Mars.

  18. Standing Tall: The Benefits of Standing Devices

    ERIC Educational Resources Information Center

    Warner, Mark P.

    2007-01-01

    In the author's opinion as a pediatric physical therapist, with the exception of a wheelchair, there is no other piece of assistive technology that is more beneficial to children and adults with special needs than a standing device. Postural symmetry during standing and walking activities is extremely important for everyone. Very few children…

  19. Structural alterations in the seminiferous tubules of rats treated with immunosuppressor tacrolimus

    PubMed Central

    Caneguim, Breno H; Cerri, Paulo S; Spolidório, Luís C; Miraglia, Sandra M; Sasso-Cerri, Estela

    2009-01-01

    Background Tacrolimus (FK-506) is an immunosuppressant that binds to a specific immunophilin, resulting in the suppression of the cellular immune response during transplant rejection. Except for some alterations in the spermatozoa, testicular morphological alterations have not been described in rats treated with tacrolimus. In the present study, we purpose to evaluate if the treatment with tacrolimus at long term of follow-up interferes in the integrity of the seminiferous tubules. Methods Rats aging 42-day-old received daily subcutaneous injections of 1 mg/kg/day of tacrolimus during 30 (T-30) and 60 (T-60) days; the rats from control groups (C-30 and C-60) received saline solution. The left testes were fixed in 4% formaldehyde and embedded in glycol methacrylate for morphological and morphometric analyses while right testes were fixed in Bouin's liquid and embedded in paraffin for detection of cell death by the TUNEL method. The epithelial and total tubular areas as well as the stages of the seminiferous epithelium and the number of spermatocytes, spermatids and Sertoli cells (SC) per tubule were obtained. Results In the treated groups, seminiferous tubules irregularly outlined showed disarranged cellular layers and loss of germ cells probably due to cell death, which was revealed by TUNEL method. In addition to germ cells, structural alterations in the SC and folding of the peritubular tissue were usually observed. The morphometric results revealed significant decrease in the number of SC, spermatocytes, spermatids and significant reduction in the epithelial and total tubular areas. Conclusion Tacrolimus induces significant histopathological disorders in the seminiferous tubules, resulting in spermatogenic damage and reduction in the number of Sertoli cells. A careful evaluation of the peritubular components will be necessary to clarify if these alterations are related to the effect of FK-506 on the peritubular tissue. PMID:19243597

  20. Structural brain alterations in patients with lumbar disc herniation: a preliminary study.

    PubMed

    Luchtmann, Michael; Steinecke, Yvonne; Baecke, Sebastian; Lützkendorf, Ralf; Bernarding, Johannes; Kohl, Jana; Jöllenbeck, Boris; Tempelmann, Claus; Ragert, Patrick; Firsching, Raimund

    2014-01-01

    Chronic pain is one of the most common health complaints in industrial nations. For example, chronic low back pain (cLBP) disables millions of people across the world and generates a tremendous economic burden. While previous studies provided evidence of widespread functional as well as structural brain alterations in chronic pain, little is known about cortical changes in patients suffering from lumbar disc herniation. We investigated morphometric alterations of the gray and white matter of the brain in patients suffering from LDH. The volumes of the gray and white matter of 12 LDH patients were determined in a prospective study and compared to the volumes of healthy controls to distinguish local differences. High-resolution MRI brain images of all participants were performed using a 3 Tesla MRI scanner. Voxel-based morphometry was used to investigate local differences in gray and white matter volume between patients suffering from LDH and healthy controls. LDH patients showed significantly reduced gray matter volume in the right anterolateral prefrontal cortex, the right temporal lobe, the left premotor cortex, the right caudate nucleus, and the right cerebellum as compared to healthy controls. Increased gray matter volume, however, was found in the right dorsal anterior cingulate cortex, the left precuneal cortex, the left fusiform gyrus, and the right brainstem. Additionally, small subcortical decreases of the white matter were found adjacent to the left prefrontal cortex, the right premotor cortex and in the anterior limb of the left internal capsule. We conclude that the lumbar disk herniation can lead to specific local alterations of the gray and white matter in the human brain. The investigation of LDH-induced brain alterations could provide further insight into the underlying nature of the chronification processes and could possibly identify prognostic factors that may improve the conservative as well as the operative treatment of the LDH.

  1. A non-contact technique for evaluation of elastic structures at large stand-off distances: applications to classification of fluids in steel vessels.

    PubMed

    Kaduchak, G; Sinha, D N; Lizon, D C; Kelecher, M J

    2000-01-01

    A novel technique for non-contact evaluation of structures in air at large stand-off distances (on the order of several meters) has been developed. It utilizes a recently constructed air-coupled, parametric acoustic array to excite the resonance vibrations of elastic, fluid-filled vessels. The parametric array is advantageous for NDE applications in that it is capable of producing a much narrower beamwidth and broader bandwidth than typical devices that operate under linear acoustic principles. In the present experiments, the array operates at a carrier frequency of 217 kHz, and the sound field several meters from the source is described spectrally by the envelope of the drive voltage. An operating bandwidth of more than 25 kHz at a center frequency of 15 kHz is demonstrated. For the present application, the array is used to excite vibrations of fluid-filled, steel containers at stand-off distances of greater than 3 m. The vibratory response of a container is detected with a laser vibrometer in a monostatic configuration with the acoustic source. By analyzing the change in the response of the lowest order, antisymmetric Lamb wave as the interior fluid loading conditions of the container are changed, the fluid contained within the steel vessel is classified.

  2. Soluble Endoglin Level Increase Occurs Prior to Development of Subclinical Structural Vascular Alterations in Diabetic Adolescents

    PubMed Central

    Emeksiz, Hamdi Cihan; Bideci, Aysun; Damar, Çağrı; Derinkuyu, Betül; Çelik, Nurullah; Döğer, Esra; Yüce, Özge; Özmen, Mehmet Cüneyt; Çamurdan, Mahmut Orhun; Cinaz, Peyami

    2016-01-01

    Objective: Soluble endoglin (S-endoglin) has been implicated as a potential marker of endothelial dysfunction (ED) and was reported to be elevated in diabetic adults, correlating with the severity of diabetic vasculopathy. However, circulating S-endoglin and its association with other markers of ED have not been formerly analyzed in the first decade of diabetes onset in adolescents with type 1 diabetes mellitus (T1DM). Methods: Fifty-eight adolescents with moderately/poorly controlled T1DM were included in this study and twenty-nine healthy adolescents served as controls. The diabetic group was divided into two groups based on the presence of microalbuminuria, as the microalbuminuria group (n=15) and the normoalbuminuria group (n=43). Functional vascular alterations were evaluated by measuring serum S-endoglin and plasma nitric oxide (NO) concentrations, the flow-mediated dilatation (FMD) of the brachial artery. Carotid intima media thickness (CIMT) was measured for evaluation of structural vascular alterations. Results: The S-endoglin and NO levels of both microalbuminuria and normoalbuminuria groups were higher than those of the control group (for S-endoglin, p=0.047 and p<0.001; for NO, p=0.004 and p=0.006, respectively). The FMD percent was lower in the microalbuminuria group compared to the normoalbuminuria and control groups (p=0.036 and p=0.020, respectively). There were negative correlations between S-endoglin concentration and FMD percent (r=-0.213, p=0.051) and between serum S-endoglin concentration and albumin excretion rate (r=-0.361, p=0.005). No significant differences were found in CIMT among any of the groups (p=0.443). Conclusion: In adolescents with T1DM, S-endoglin concentrations might increase in parallel to the deterioration in endothelial function before subclinical structural vascular alterations become evident. PMID:27097763

  3. Halothane-induced alterations in cellular structure and proliferation of A549 cells.

    PubMed

    Stephanova, E; Topouzova-Hristova, T; Hazarosova, R; Moskova, V

    2008-12-01

    Genotoxicity, cytotoxicity or teratogenicity are among the well-known detrimental effects of the volatile anaesthetics. The aim of the present work was to study the structural changes, proliferative activity and the possibility of alveolar A549 cells to recover after in vitro exposure to halothane at 1.5 and 2.1mM concentrations. Our data indicated significant reduction of viability, suppression of mitotic activity more than 60%, and that these alterations were accompanied by disturbances of nuclear and nucleolar structures. The most prominent negative effect was the destruction of the lamellar bodies, the main storage organelles of pulmonary surfactant, substantial for the lung physiology. In conclusion, halothane applied at clinically relevant concentrations exerts genotoxic and cytotoxic effect on the alveolar cells in vitro, most likely as a consequence of stress-induced apoptosis, thus modulating the respiratory function.

  4. Running Induces Widespread Structural Alterations in the Hippocampus and Entorhinal Cortex

    PubMed Central

    Stranahan, Alexis M.; Khalil, David; Gould, Elizabeth

    2010-01-01

    Physical activity enhances hippocampal function but its effects on neuronal structure remain relatively unexplored outside of the dentate gyrus. Using Golgi impregnation and the lipophilic tracer DiI, we show that long-term voluntary running increases the density of dendritic spines in the entorhinal cortex and hippocampus of adult rats. Exercise was associated with increased dendritic spine density not only in granule neurons of the dentate gyrus, but also in CA1 pyramidal neurons, and in layer III pyramidal neurons of the entorhinal cortex. In the CA1 region, changes in dendritic spine density are accompanied by changes in dendritic arborization and alterations in the morphology of individual spines. These findings suggest that physical activity exerts pervasive effects on neuronal morphology in the hippocampus and one of its afferent populations. These structural changes may contribute to running-induced changes in cognitive function. PMID:17636549

  5. Chloroplast Structure and Function Is Altered in the NCS2 Maize Mitochondrial Mutant 1

    PubMed Central

    Roussell, Deborah L.; Thompson, Deborah L.; Pallardy, Steve G.; Miles, Donald; Newton, Kathleen J.

    1991-01-01

    The nonchromosomal stripe 2 (NCS2) mutant of maize (Zea mays L.) has a DNA rearrangement in the mitochondrial genome that segregates with the abnormal growth phenotype. Yet, the NCS2 characteristic phenotype includes striped sectors of pale-green tissue on the leaves. This suggests a chloroplast abnormality. To characterize the chloroplasts present in the mutant sectors, we examined the chloroplast structure by electron microscopy, chloroplast function by radiolabeled carbon dioxide fixation and fluorescence induction kinetics, and thylakoid protein composition by polyacrylamide gel electrophoresis. The data from these analyses suggest abnormal or prematurely arrested chloroplast development. Deleterious effects of the NCS2 mutant mitochondria upon the cells of the leaf include structural and functional alterations in the both the bundle sheath and mesophyll chloroplasts. ImagesFigure 1Figure 2Figure 3Figure 5Figure 6 PMID:16668157

  6. [Night sleep structural alteration as a function of individual strategy of adapting to 520-isolation].

    PubMed

    Zavalko, I M; Boritko, Ya S; Kovrov, G V; Vinokhodova, A G; Chekalina, A I; Smoleevsky, A E

    2014-01-01

    Purpose of the work was to establish a relationship between trends in sleep alteration and individual adaptation to the stress-factors in the 520-day isolation study. Psychological evaluations using a battery of motivation tests and L. Sobchik's modification of the Luscher personality test, and Mirror coordinograph enabled to differentiate groups reacting to the stress on the pattern of "control" (G-1) or "search" (G-2) manifested in individual styles of behavior and operator's activity. The 2 groups showed different dynamics of the night sleep structure. Difficulties with falling asleep in G-1 arose on the eve of "landing onto Mars" and end of the experiment, whereas in G-2 they were evident prior to the end only. Besides, the micro- and segmental sleep structures were more stable in G-1 suggesting the integrity of somnogenic mechanisms despite difficult sleep initiation.

  7. Structural white matter and functional connectivity alterations in patients with shoulder apprehension

    PubMed Central

    Zanchi, Davide; Cunningham, Gregory; Lädermann, Alexandre; Ozturk, Mehmet; Hoffmeyer, Pierre; Haller, Sven

    2017-01-01

    Previous functional magnetic resonance imaging (fMRI) findings indicate that shoulder apprehension is more complex than a pure mechanical problem of the shoulder, showing a direct modification in functional brain networks associated with motor inhibition and emotional regulation. The current study extends these findings by investigating further structural alterations in patients with shoulder apprehension compared to controls. 14 aged patients with shoulder apprehension (27.3 ± 2.0 years) and 10 matched healthy controls (29.6 ± 1.3 years) underwent clinical and fMRI examination including fMRI and diffusion tensor imaging (DTI). Tract-based spatial statistics procedure was used to analyze white matter (WM) alterations. Functional images were analyzed investigating resting state network connectivity. DTI results were correlated with different shoulder clinical scores and functional connectivity networks. Fractional anisotropy (FA), representing white matter integrity, is increased in the left internal capsule and partially in the thalamus in patients compared to controls. Moreover, FA correlates negatively with simple shoulder test (SST) scores (p < .05) and positively with a functional connectivity network qualitatively replicating previous results (p < .01). This study extends previous findings, showing that in addition to functional changes, structural white matter changes are also present in patients with shoulder apprehension. PMID:28176877

  8. Altered brain structural networks in attention deficit/hyperactivity disorder children revealed by cortical thickness.

    PubMed

    Liu, Tian; Chen, Yanni; Li, Chenxi; Li, Youjun; Wang, Jue

    2017-01-18

    This study investigated the cortical thickness and topological features of human brain anatomical networks related to attention deficit/hyperactivity disorder. Data were collected from 40 attention deficit/hyperactivity disorder children and 40 normal control children. Interregional correlation matrices were established by calculating the correlations of cortical thickness between all pairs of cortical regions (68 regions) of the whole brain. Further thresholds were applied to create binary matrices to construct a series of undirected and unweighted graphs, and global, local, and nodal efficiencies were computed as a function of the network cost. These experimental results revealed abnormal cortical thickness and correlations in attention deficit/hyperactivity disorder, and showed that the brain structural networks of attention deficit/hyperactivity disorder subjects had inefficient small-world topological features. Furthermore, their topological properties were altered abnormally. In particular, decreased global efficiency combined with increased local efficiency in attention deficit/hyperactivity disorder children led to a disorder-related shift of the network topological structure toward regular networks. In addition, nodal efficiency, cortical thickness, and correlation analyses revealed that several brain regions were altered in attention deficit/hyperactivity disorder patients. These findings are in accordance with a hypothesis of dysfunctional integration and segregation of the brain in patients with attention deficit/hyperactivity disorder and provide further evidence of brain dysfunction in attention deficit/hyperactivity disorder patients by observing cortical thickness on magnetic resonance imaging.

  9. Chronic ethanol intake leads to structural and molecular alterations in the rat endometrium.

    PubMed

    Martinez, Marcelo; Milton, Flora A; Pinheiro, Patricia Fernanda F; Almeida-Francia, Camila C D; Cagnon-Quitete, Valeria H A; Tirapelli, Luiz F; Padovani, Carlos Roberto; Chuffa, Luiz Gustavo A; Martinez, Francisco Eduardo

    2016-05-01

    We described the effects of low- and high-dose ethanol intake on the structure and apoptosis signaling of the uterine endometrium of UChA and UChB rats (animals with voluntary ethanol consumption). Thirty adult female rats, 90 days old, were divided into three groups (n = 10/group): UChA rats fed with 10% (v/v) ethanol ad libitum (free choice for water or ethanol) drinking < 1.9 g/kg/day; UChB rats fed with 10% (v/v) ethanol ad libitum (free choice for water or ethanol) drinking from 2 to 5 g/kg/day; control rats without ethanol (only water). After 120 days of treatment, rats displaying estrus were euthanized. Uterine epithelial cells of the UCh rats showed dilated cisterns of the rough endoplasmic reticulum, presence of lipid droplets, altered nuclear chromatin, and disrupted mitochondria. The UCh rats exhibited intense atrophied epithelial cells with smaller areas and perimeters of cytoplasm and nuclei. The endometrium of UChA rats showed higher levels of caspase-3 while Xiap and Bcl2 varied from moderate to weak. Both UChA and UChB rats exhibited a stronger immunoreaction to Ki-67 and IGFR-1 on epithelial and stromal cells. Chronic ethanol intake leads to structural and molecular alterations in the uterine endometrium of UCh rats, regardless of low- or high-dose consumption, promoting reproductive disorders.

  10. Consumer return chronology alters recovery trajectory of stream ecosystem structure and function following drought.

    PubMed

    Murdock, Justin N; Gido, Keith B; Dodds, Walter K; Bertrand, Katie N; Whiles, Matt R

    2010-04-01

    Consumers are increasingly being recognized as important drivers of ecological succession, yet it is still hard to predict the nature and direction of consumer effects in nonequilibrium environments. We used stream consumer exclosures and large outdoor mesocosms to study the impact of macroconsumers (i.e., fish and crayfish) on recovery of intermittent prairie streams after drying. In the stream, macroconsumers altered system recovery trajectory by decreasing algal and macroinvertebrate biomass, primary productivity, and benthic nutrient uptake rates. However, macroconsumer influence was transient, and differences between exclosures and controls disappeared after 35 days. Introducing and removing macroconsumers after 28 days resulted mainly in changes to macroinvertebrates. In mesocosms, a dominant consumer (the grazing minnow Phoxinus erythrogaster) reduced macroinvertebrate biomass but had little effect on algal assemblage structure and ecosystem rates during recovery. The weak effect of P. erythrogaster in mesocosms, in contrast to the strong consumer effect in the natural stream, suggests that both timing and diversity of returning consumers are important to their overall influence on stream recovery patterns. Although we found that consumers significantly altered ecosystem structure and function in a system experiencing rapid changes in abiotic and biotic factors following disturbance, consumer effects diminished over time and trajectories converged to similar states with respect to primary producers, in spite of differences in consumer colonization history. Thus, consumer impacts can be substantial in recovering ecosystems and are likely to be dependent on the disturbance regime and diversity of the consumer community.

  11. Field-based experimental acidification alters fouling community structure and reduces diversity.

    PubMed

    Brown, Norah E M; Therriault, Thomas W; Harley, Christopher D G

    2016-09-01

    Increasing levels of CO2 in the atmosphere are affecting ocean chemistry, leading to increased acidification (i.e. decreased pH) and reductions in calcium carbonate saturation state. Many species are likely to respond to acidification, but the direction and magnitude of these responses will be based on interspecific and ontogenetic variation in physiology and the relative importance of calcification. Differential responses to ocean acidification (OA) among species will likely result in important changes in community structure and diversity. To characterize the potential impacts of OA on community composition and structure, we examined the response of a marine fouling community to experimental CO2 enrichment in field-deployed flow-through mesocosm systems. Acidification significantly altered the community structure by altering the relative abundance of species and reduced community variability, resulting in more homogenous biofouling communities from one experimental tile to the next both among and within the acidified mesocosms. Mussel (Mytilus trossulus) recruitment was reduced by over 30% in the elevated CO2 treatment compared to the ambient treatment by the end of the experiment. Strong differences in mussel cover (up to 40% lower in acidified conditions) developed over the second half of the 10-week experiment. Acidification did not appear to affect the mussel growth, as average mussel sizes were similar between treatments at the end of the experiment. Hydroid (Obelia dichotoma) cover was significantly reduced in the elevated CO2 treatment after 8 weeks. Conversely, the percentage cover of bryozoan colonies (Mebranipora membranacea) was higher under acidified conditions with differences becoming apparent after 6 weeks. Neither recruitment nor final size of barnacles (Balanus crenatus) was affected by acidification. By the end of the experiment, diversity was 41% lower in the acidified treatment relative to ambient conditions. Overall, our findings support the

  12. Structural Insight into the Altered Substrate Specificity of Human Cytochrome P450 2A6 Mutants

    PubMed Central

    Sansen, Stefaan; Hsu, Mei-Hui; Stout, C. David; Johnson, Eric F.

    2009-01-01

    Human P450 2A6 displays a small active site that is well adapted for the oxidation of small planar substrates. Mutagenesis of CYP2A6 resulted in an increased catalytic efficiency for indole biotransformation to pigments and conferred a capacity to oxidize substituted indoles (Wu, Z.-L., Podust, L.M. and Guengerich, F.P. (2005) J.Biol.Chem. 49, 41090-41100). Here, we describe the structural basis that underlies the altered metabolic profile of three mutant enzymes, P450 2A6 N297Q, L240C/N297Q and N297Q/I300V. The Asn297 substitution abolishes a potential hydrogen bonding interaction with substrates in the active site, and replaces a structural water molecule between the helix B′-C region and helix I while maintaining structural hydrogen bonding interactions. The structures of the P450 2A6 N297Q/L240C and N297Q/I300V mutants provide clues as to how the protein can adapt to fit the larger substituted indoles in the active site, and enable a comparison with other P450 family 2 enzymes for which the residue at the equivalent position was seen to function in isozyme specificity, structural integrity and protein flexibility. PMID:17540336

  13. Alterations of Functional and Structural Networks in Schizophrenia Patients with Auditory Verbal Hallucinations

    PubMed Central

    Zhu, Jiajia; Wang, Chunli; Liu, Feng; Qin, Wen; Li, Jie; Zhuo, Chuanjun

    2016-01-01

    Background: There have been many attempts at explaining the underlying neuropathological mechanisms of auditory verbal hallucinations (AVH) in schizophrenia on the basis of regional brain changes, with the most consistent findings being that AVH are associated with functional and structural impairments in auditory and speech-related regions. However, the human brain is a complex network and the global topological alterations specific to AVH in schizophrenia remain unclear. Methods: Thirty-five schizophrenia patients with AVH, 41 patients without AVH, and 50 healthy controls underwent resting-state functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). The whole-brain functional and structural networks were constructed and analyzed using graph theoretical approaches. Inter-group differences in global network metrics (including small-world properties and network efficiency) were investigated. Results: We found that three groups had a typical small-world topology in both functional and structural networks. More importantly, schizophrenia patients with and without AVH exhibited common disruptions of functional networks, characterized by decreased clustering coefficient, global efficiency and local efficiency, and increased characteristic path length; structural networks of only schizophrenia patients with AVH showed increased characteristic path length compared with those of healthy controls. Conclusion: Our findings suggest that less “small-worldization” and lower network efficiency of functional networks may be an independent trait characteristic of schizophrenia, and regularization of structural networks may be the underlying pathological process engaged in schizophrenic AVH symptom expression. PMID:27014042

  14. Structure-function relationships of brazzein variants with altered interactions with the human sweet taste receptor.

    PubMed

    Singarapu, Kiran K; Tonelli, Marco; Markley, John L; Assadi-Porter, Fariba M

    2016-03-01

    Brazzein (Brz) is a small (54 amino acid residue) sweet tasting protein with physical and taste properties superior to other non-carbohydrate sweeteners. In an investigation of sequence-dependent functional properties of the protein, we used NMR spectroscopy to determine the three-dimensional structures and dynamic properties of two Brz variants: one with a single-site substitution (D40K), which is three-fold sweeter than wild-type Brz, and one with a two-residue insertion between residues 18 and 19 (ins18 RI19 ), which is devoid of sweetness. Although the three-dimensional folds of the two variants were very similar to wild-type Brz, they exhibited local conformational and dynamic differences. The D40K substitution abolished the strong inter-stand H-bond between the side chains of residues Gln46 and Asp40 present in wild-type Brz and increased the flexibility of the protein especially at the mutation site. This increased flexibility presumably allows this site to interact more strongly with the G-protein coupled human sweet receptor. On the other hand, the Arg-Ile insertion within Loop9-19 leads to distortion of this loop and stiffening of the adjacent site whose flexibility appears to be required for productive interaction with the sweet receptor.

  15. Quantitative analysis of nanoscale intranuclear structural alterations in hippocampal cells in chronic alcoholism via transmission electron microscopy imaging

    NASA Astrophysics Data System (ADS)

    Sahay, Peeyush; Shukla, Pradeep K.; Ghimire, Hemendra M.; Almabadi, Huda M.; Tripathi, Vibha; Mohanty, Samarendra K.; Rao, Radhakrishna; Pradhan, Prabhakar

    2017-04-01

    Chronic alcoholism is known to alter the morphology of the hippocampus, an important region of cognitive function in the brain. Therefore, to understand the effect of chronic alcoholism on hippocampal neural cells, we employed a mouse model of chronic alcoholism and quantified intranuclear nanoscale structural alterations in these cells. Transmission electron microscopy (TEM) images of hippocampal neurons were obtained, and the degree of structural alteration in terms of mass density fluctuation was determined using the light-localization properties of optical media generated from TEM imaging. The results, which were obtained at length scales ranging from ~30 to 200 nm, show that 10–12 week-old mice fed a Lieber–DeCarli liquid (alcoholic) diet had a higher degree of structural alteration than control mice fed a normal diet without alcohol. The degree of structural alteration became significantly distinguishable at a sample length of ~100 nm, which is the typical length scale of the building blocks of cells, such as DNA, RNA, proteins and lipids. Interestingly, different degrees of structural alteration at such length scales suggest possible structural rearrangement of chromatin inside the nuclei in chronic alcoholism.

  16. Structural and alteration controls on gold mineralization the of the amphibolite facies Detour Lake Deposit, Canada

    NASA Astrophysics Data System (ADS)

    Dubosq, Renelle; Schneider, David

    2016-04-01

    The 15M oz Detour Lake deposit is a Neoarchean orogenic gold ore body located in the northern most region of the Abitibi district within the Superior Province. The mine is an open pit design in the high strain zone of the Sunday Lake Deformation Zone (SLDZ). The ductile-brittle SLDZ parallels the broadly E-W Abitibi greenstone belt and the deposit is situated in a dilation zone between volcanoclastic rocks of the Caopatina Assemblage and Lower Detour Lake Formation, consisting of ultramafic talc-chlorite-sericite schist. The Upper Detour Lake Formation consists of pillowed and massive flows and hyloclastic units crosscut by minor felsic to intermediate dykes. All of the formations are sub-vertical, north-dipping units with stretching lineations indicating dip-slip motion. The Detour deposit differs from other classic ore deposits in the dominantly greenschist facies Abitibi Subprovince by possessing an amphibolite facies metamorphic assemblage of actinolite-biotite-plagioclase-almandine. Consequently, the typical indicator minerals used to identify alteration and mineralization, such as secondary biotite, may not be useful. Petrological and geochemical analyses have revealed at least four populations of biotite: 1) large euhedral crystals located within quartz-carbonate veins, 2) small, euhedral zoned crystals present as alteration haloes, 3) very small, anhedral to subhedral indistinct crystal present in mafic volcanic host rock, and 4) large euhedral crystals defining the main metamorphic foliation in the metasediments. Extensive examination of mineral assemblages, alteration products, and vein structure in rock core across barren and mineralized zones has documented over a dozen vein types which can be grouped into two main categories: 1) sulfidized quartz-carbonate veins associated with biotite alteration and 2) late carbonate veins. Gold grades do not prove to be dependent on vein type but rather on the host rock composition: the highest ore grades are present

  17. The Neutron Structure of Urate Oxidase Resolves a Long-Standing Mechanistic Conundrum and Reveals Unexpected Changes in Protonation

    PubMed Central

    Oksanen, Esko; Blakeley, Matthew P.; El-Hajji, Mohamed; Ryde, Ulf; Budayova-Spano, Monika

    2014-01-01

    Urate oxidase transforms uric acid to 5-hydroxyisourate without the help of cofactors, but the catalytic mechanism has remained enigmatic, as the protonation state of the substrate could not be reliably deduced. We have determined the neutron structure of urate oxidase, providing unique information on the proton positions. A neutron crystal structure inhibited by a chloride anion at 2.3 Å resolution shows that the substrate is in fact 8-hydroxyxanthine, the enol tautomer of urate. We have also determined the neutron structure of the complex with the inhibitor 8-azaxanthine at 1.9 Å resolution, showing the protonation states of the K10–T57–H256 catalytic triad. Together with X-ray data and quantum chemical calculations, these structures allow us to identify the site of the initial substrate protonation and elucidate why the enzyme is inhibited by a chloride anion. PMID:24466188

  18. Structural and functional alterations to rat medial prefrontal cortex following chronic restraint stress and recovery

    PubMed Central

    Goldwater, Deena S.; Pavlides, Constantine; Hunter, Richard G.; Bloss, Erik B.; Hof, Patrick R.; McEwen, Bruce S.; Morrison, John H.

    2009-01-01

    Chronic stress has been shown in animal models to result in altered dendritic morphology of pyramidal neurons of the medial prefrontal cortex (mPFC). It has been hypothesized that the stress-induced dendritic retractions and spine loss lead to disrupted connectivity that results in stress-induced functional impairment of mPFC. While these alterations were initially viewed as a neurodegenerative event, it has recently been established that stress induced dendritic alterations are reversible if animals are given time to recover from chronic stress. However, whether spine growth accompanies dendritic extension remains to be demonstrated. It is also not known if recovery-phase dendritic extension allows for re-establishment of functional capacity. The goal of this study, therefore, was to characterize the structural and functional effects of chronic stress and recovery on the infralimbic (IL) region of the rat mPFC. We compared neuronal morphology of layer V IL pyramidal neurons from animals subjected to 21 days of chronic restraint stress (CRS) to those that experienced CRS followed by a 21 day recovery period. Layer V pyramidal cell functional capacity was assessed by intra-IL long-term potentiation (LTP) both in the absence and presence of SKF38393, a dopamine receptor partial agonist and a known PFC LTP modulator. We found that stress-induced IL apical dendritic retraction and spine loss co-occur with receptor-mediated impairments to catecholaminergic facilitation of synaptic plasticity. We also found that while post-stress recovery did not reverse distal dendritic retraction, it did result in over-extension of proximal dendritic neuroarchitecture and spine growth as well as a full reversal of CRS-induced impairments to catecholaminergic-mediated synaptic plasticity. Our results support the hypothesis that disease-related PFC dysfunction is a consequence of network disruption secondary to altered structural and functional plasticity and that circuitry

  19. Packaging and structural phenotype of brome mosaic virus capsid protein with altered N-terminal {beta}-hexamer structure

    SciTech Connect

    Wispelaere, Melissanne de; Chaturvedi, Sonali; Wilkens, Stephan; Rao, A.L.N.

    2011-10-10

    The first 45 amino acid region of brome mosaic virus (BMV) capsid protein (CP) contains RNA binding and structural domains that are implicated in the assembly of infectious virions. One such important structural domain encompassing amino acids {sup 28}QPVIV{sup 32}, highly conserved between BMV and cowpea chlorotic mottle virus (CCMV), exhibits a {beta}-hexamer structure. In this study we report that alteration of the {beta}-hexamer structure by mutating {sup 28}QPVIV{sup 32} to {sup 28}AAAAA{sup 32} had no effect either on symptom phenotype, local and systemic movement in Chenopodium quinoa and RNA profile of in vivo assembled virions. However, sensitivity to RNase and assembly phenotypes distinguished virions assembled with CP subunits having {beta}-hexamer from those of wild type. A comparison of 3-D models obtained by cryo electron microscopy revealed overall similar structural features for wild type and mutant virions, with small but significant differences near the 3-fold axes of symmetry.

  20. Test Stand Construction

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Construction crews install steel reinforcing rods at the base of what became the A-2 test stand. The excavation for the stand went down 50 feet with steel H-beams driven 100 feet deeper to form a foundation for the huge piers of the test stand.

  1. Implications for faunal habitat related to altered macrophyte structure in regulated lakes in northern Minnesota

    USGS Publications Warehouse

    Wilcox, Douglas A.; Meeker, James E.

    1992-01-01

    Water-level regulation has altered the plant species composition and thus the structure of nearshore aquatic macrophyte communities in two regulated lakes in northern Minnesota as compared with a nearby unregulated lake. Results of previous faunal studies in the regulated lakes were used as a basis for assessing the effects of vegetation changes on faunal communities. The unregulated lake with mean annual water-level fluctuations of 1.6 m supported structurally diverse plant communities and varied faunal habitat at all depths studied. Mean annual fluctuations on one regulated lake were reduced to 1.1 m, and dense beds of four erect aquatic macrophytes dominated the 1.75-m depth that was never dewatered. We suggest that this lack of plant diversity and structural complexity resulted in diminished habitat for invertebrates, reduced availability of invertebrates as food for waterbirds and fish, reduced winter food supplies for muskrats, and reduced feeding efficiency for adult northern pike, yellow perch, and muskellunge. Mean annual fluctuations in the other regulated lake were increased to 2.7 m, and rosette and mat-forming species dominated the 1.25-m depth that was affected by winter drawdowns. We suggest that the lack of larger canopy plants resulted in poor habitat for invertebrates, reduced availability of invertebrates as food for waterbirds and fish, and poor nursery and adult feeding habitat for many species of fish. In addition, the timing and extent of winter drawdowns reduced access to macrophytes as food for muskrats and as spawning habitat for northern pike and yellow perch. In regulated lakes throughout the world, indirect effects on aquatic fauna resulting from alteration of wetland and aquatic macrophyte communities should be considered when water-level management plans are developed.

  2. Chronic fluoxetine treatment alters the structure, connectivity and plasticity of cortical interneurons.

    PubMed

    Guirado, Ramon; Perez-Rando, Marta; Sanchez-Matarredona, David; Castrén, Eero; Nacher, Juan

    2014-10-01

    Novel hypotheses suggest that antidepressants, such as the selective serotonin reuptake inhibitor fluoxetine, induce neuronal structural plasticity, resembling that of the juvenile brain, although the underlying mechanisms of this reopening of the critical periods still remain unclear. However, recent studies suggest that inhibitory networks play an important role in this structural plasticity induced by fluoxetine. For this reason we have analysed the effects of a chronic fluoxetine treatment in the hippocampus and medial prefrontal cortex (mPFC) of transgenic mice displaying eGFP labelled interneurons. We have found an increase in the expression of molecules related to critical period plasticity, such as the polysialylated form of the neural cell adhesion molecule (PSA-NCAM), GAD67/65 and synaptophysin, as well as a reduction in the number of parvalbumin expressing interneurons surrounded by perineuronal nets. We have also described a trend towards decrease in the perisomatic inhibitory puncta on pyramidal neurons in the mPFC and an increase in the density of inhibitory puncta on eGFP interneurons. Finally, we have found that chronic fluoxetine treatment affects the structure of interneurons in the mPFC, increasing their dendritic spine density. The present study provides evidence indicating that fluoxetine promotes structural changes in the inhibitory neurons of the adult cerebral cortex, probably through alterations in plasticity-related molecules of neurons or the extracellular matrix surrounding them, which are present in interneurons and are known to be crucial for the development of the critical periods of plasticity in the juvenile brain.

  3. New insights into structural alteration of enamel apatite induced by citric acid and sodium fluoride solutions.

    PubMed

    Wang, Xiaojie; Klocke, Arndt; Mihailova, Boriana; Tosheva, Lubomira; Bismayer, Ulrich

    2008-07-24

    Attenuated total reflectance infrared spectroscopy and complementary scanning electron microscopy were applied to analyze the surface structure of enamel apatite exposed to citric acid and to investigate the protective potential of fluorine-containing reagents against citric acid-induced erosion. Enamel and, for comparison, geological hydroxylapatite samples were treated with aqueous solutions of citric acid and sodium fluoride of different concentrations, ranging from 0.01 to 0.5 mol/L for citric acid solutions and from 0.5 to 2.0% for fluoride solutions. The two solutions were applied either simultaneously or consecutively. The citric acid-induced structural modification of apatite increases with the increase in the citric acid concentration and the number of treatments. The application of sodium fluoride alone does not suppress the atomic level changes in apatite exposed to acidic agents. The addition of sodium fluoride to citric acid solutions leads to formation of surface CaF2 and considerably reduces the changes in the apatite P-O-Ca framework. However, the CaF2 globules deposited on the enamel surface seem to be insufficient to prevent the alteration of the apatite structure upon further exposure to acidic agents. No evidence for fluorine-induced recovery of the apatite structure was found.

  4. Problematic internet use is associated with structural alterations in the brain reward system in females.

    PubMed

    Altbäcker, Anna; Plózer, Enikő; Darnai, Gergely; Perlaki, Gábor; Horváth, Réka; Orsi, Gergely; Nagy, Szilvia Anett; Bogner, Péter; Schwarcz, Attila; Kovács, Norbert; Komoly, Sámuel; Clemens, Zsófia; Janszky, József

    2016-12-01

    Neuroimaging findings suggest that excessive Internet use shows functional and structural brain changes similar to substance addiction. Even though it is still under debate whether there are gender differences in case of problematic use, previous studies by-passed this question by focusing on males only or by using gender matched approach without controlling for potential gender effects. We designed our study to find out whether there are structural correlates in the brain reward system of problematic Internet use in habitual Internet user females. T1-weighted Magnetic Resonance (MR) images were collected in 82 healthy habitual Internet user females. Structural brain measures were investigated using both automated MR volumetry and voxel based morphometry (VBM). Self-reported measures of problematic Internet use and hours spent online were also assessed. According to MR volumetry, problematic Internet use was associated with increased grey matter volume of bilateral putamen and right nucleus accumbens while decreased grey matter volume of orbitofrontal cortex (OFC). Similarly, VBM analysis revealed a significant negative association between the absolute amount of grey matter OFC and problematic Internet use. Our findings suggest structural brain alterations in the reward system usually related to addictions are present in problematic Internet use.

  5. Alteration of human serum albumin tertiary structure induced by glycation. Spectroscopic study.

    PubMed

    Szkudlarek, A; Maciążek-Jurczyk, M; Chudzik, M; Równicka-Zubik, J; Sułkowska, A

    2016-01-15

    The modification of human serum albumin (HSA) structure by non-enzymatic glycation is one of the underlying factors that contribute to the development of complications of diabetes and neurodegenerative diseases. The aim of the present work was to estimate how glycation of HSA altered its tertiary structure. Changes of albumin conformation were investigated by comparison of glycated (gHSA) and non-glycated human serum albumin (HSA) absorption spectra, red edge excitation shift (REES) and synchronous spectra. Effect of glycation on human serum albumin tertiary structure was also investigated by (1)H NMR spectroscopy. Formation of gHSA Advanced Glycation End-products (AGEs) caused absorption of UV-VIS light between 310 nm and 400 nm while for non-glycated HSA in this region no absorbance has been registered. Analysis of red edge excitation shift effect allowed for observation of structural changes of gHSA in the hydrophobic pocket containing the tryptophanyl residue. Moreover changes in the microenvironment of tryptophanyl and tyrosyl residues brought about AGEs on the basis of synchronous fluorescence spectroscopy have been confirmed. The influence of glycation process on serum albumin binding to 5-dimethylaminonaphthalene-1-sulfonamide (DNSA), 2-(p-toluidino) naphthalene-6-sulfonic acid (TNS), has been studied. Fluorescence analysis showed that environment of both binding site I and II is modified by galactose glycation.

  6. Alteration of human serum albumin tertiary structure induced by glycation. Spectroscopic study

    NASA Astrophysics Data System (ADS)

    Szkudlarek, A.; Maciążek-Jurczyk, M.; Chudzik, M.; Równicka-Zubik, J.; Sułkowska, A.

    2016-01-01

    The modification of human serum albumin (HSA) structure by non-enzymatic glycation is one of the underlying factors that contribute to the development of complications of diabetes and neurodegenerative diseases. The aim of the present work was to estimate how glycation of HSA altered its tertiary structure. Changes of albumin conformation were investigated by comparison of glycated (gHSA) and non-glycated human serum albumin (HSA) absorption spectra, red edge excitation shift (REES) and synchronous spectra. Effect of glycation on human serum albumin tertiary structure was also investigated by 1H NMR spectroscopy. Formation of gHSA Advanced Glycation End-products (AGEs) caused absorption of UV-VIS light between 310 nm and 400 nm while for non-glycated HSA in this region no absorbance has been registered. Analysis of red edge excitation shift effect allowed for observation of structural changes of gHSA in the hydrophobic pocket containing the tryptophanyl residue. Moreover changes in the microenvironment of tryptophanyl and tyrosyl residues brought about AGEs on the basis of synchronous fluorescence spectroscopy have been confirmed. The influence of glycation process on serum albumin binding to 5-dimethylaminonaphthalene-1-sulfonamide (DNSA), 2-(p-toluidino) naphthalene-6-sulfonic acid (TNS), has been studied. Fluorescence analysis showed that environment of both binding site I and II is modified by galactose glycation.

  7. Is higher serum cholesterol associated with altered tendon structure or tendon pain? A systematic review

    PubMed Central

    Tilley, Benjamin J; Cook, Jill L; Docking, Sean I; Gaida, James E

    2015-01-01

    Background Tendon pain occurs in individuals with extreme cholesterol levels (familial hypercholesterolaemia). It is unclear whether the association with tendon pain is strong with less extreme elevations of cholesterol. Objective To determine whether lipid levels are associated with abnormal tendon structure or the presence of tendon pain. Methods We conducted a systematic review and meta-analysis. Relevant articles were found through an electronic search of 6 medical databases—MEDLINE, Cochrane, AMED, EMBASE, Web of Science and Scopus. We included all case–control or cross-sectional studies with data describing (1) lipid levels or use of lipid-lowering drugs and (2) tendon structure or tendon pain. Results 17 studies (2612 participants) were eligible for inclusion in the review. People with altered tendon structure or tendon pain had significantly higher total cholesterol, low-density lipoprotein cholesterol and triglycerides, as well as lower high-density lipoprotein cholesterol; with mean difference values of 0.66, 1.00, 0.33, and −0.19 mmol/L, respectively. Conclusions The results of this review indicate that a relationship exists between an individual’s lipid profile and tendon health. However, further longitudinal studies are required to determine whether a cause and effect relationship exists between tendon structure and lipid levels. This could lead to advancement in the understanding of the pathoaetiology and thus treatment of tendinopathy. PMID:26474596

  8. Molecular interactions alter clay and polymer structure in polymer clay nanocomposites.

    PubMed

    Sikdar, Debashis; Katti, Kalpana S; Katti, Dinesh R

    2008-04-01

    OMMTs with three different organic modifiers further confirm the change in structural orientation of silica tetrahedra of OMMTs by organic modifiers. Thus, from our work it is evident that organic modifiers have significant influence on the structure of polymer and clay in PCNs. It appears that in nanocomposites, in addition to strong interactions at interfaces between constituents, the structure of different phases (clay and polymer) of PCN are also altered, which does not occur in conventional composite materials. Thus, the mechanisms governing composite action in nanocomposites are quite different from that of conventional macro composites.

  9. Historical and modern disturbance regimes, stand structures, and landscape dynamics in pinon-juniper vegetation of the western United States.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Piñon–juniper is a major vegetation type in western North America. Effective management of these ecosystems has been hindered by inadequate understanding of 1) the variability in ecosystem structure and ecological processes that exists among the diverse combinations of piñons, junipers, and associat...

  10. Alzheimer's-associated Abeta oligomers show altered structure, immunoreactivity and synaptotoxicity with low doses of oleocanthal.

    PubMed

    Pitt, Jason; Roth, William; Lacor, Pascale; Smith, Amos B; Blankenship, Matthew; Velasco, Pauline; De Felice, Fernanda; Breslin, Paul; Klein, William L

    2009-10-15

    It now appears likely that soluble oligomers of amyloid-beta1-42 peptide, rather than insoluble fibrils, act as the primary neurotoxin in Alzheimer's disease (AD). Consequently, compounds capable of altering the assembly state of these oligomers (referred to as ADDLs) may have potential for AD therapeutics. Phenolic compounds are of particular interest for their ability to disrupt Abeta oligomerization and reduce pathogenicity. This study has focused on oleocanthal (OC), a naturally-occurring phenolic compound found in extra-virgin olive oil. OC increased the immunoreactivity of soluble Abeta species, when assayed with both sequence- and conformation-specific Abeta antibodies, indicating changes in oligomer structure. Analysis of oligomers in the presence of OC showed an upward shift in MW and a ladder-like distribution of SDS-stable ADDL subspecies. In comparison with control ADDLs, oligomers formed in the presence of OC (Abeta-OC) showed equivalent colocalization at synapses but exhibited greater immunofluorescence as a result of increased antibody recognition. The enhanced signal at synapses was not due to increased synaptic binding, as direct detection of fluorescently-labeled ADDLs showed an overall reduction in ADDL signal in the presence of OC. Decreased binding to synapses was accompanied by significantly less synaptic deterioration assayed by drebrin loss. Additionally, treatment with OC improved antibody clearance of ADDLs. These results indicate oleocanthal is capable of altering the oligomerization state of ADDLs while protecting neurons from the synaptopathological effects of ADDLs and suggest OC as a lead compound for development in AD therapeutics.

  11. Maternal Hyperleptinemia Is Associated with Male Offspring’s Altered Vascular Function and Structure in Mice

    PubMed Central

    Pollock, Kelly E.; Talton, Omonseigho O.; Foote, Christopher A.; Reyes-Aldasoro, Constantino C.; Wu, Ho-Hsiang; Ji, Tieming; Martinez-Lemus, Luis A.; Schulz, Laura C.

    2016-01-01

    Children of mothers with gestational diabetes have greater risk of developing hypertension but little is known about the mechanisms by which this occurs. The objective of this study was to test the hypothesis that high maternal concentrations of leptin during pregnancy, which are present in mothers with gestational diabetes and/or obesity, alter blood pressure, vascular structure and vascular function in offspring. Wildtype (WT) offspring of hyperleptinemic, normoglycemic, Leprdb/+ dams were compared to genotype matched offspring of WT-control dams. Vascular function was assessed in male offspring at 6, and at 31 weeks of age after half the offspring had been fed a high fat, high sucrose diet (HFD) for 6 weeks. Blood pressure was increased by HFD but not affected by maternal hyperleptinemia. On a standard diet, offspring of hyperleptinemic dams had outwardly remodeled mesenteric arteries and an enhanced vasodilatory response to insulin. In offspring of WT but not Leprdb/+ dams, HFD induced vessel hypertrophy and enhanced vasodilatory responses to acetylcholine, while HFD reduced insulin responsiveness in offspring of hyperleptinemic dams. Offspring of hyperleptinemic dams had stiffer arteries regardless of diet. Therefore, while maternal hyperleptinemia was largely beneficial to offspring vascular health under a standard diet, it had detrimental effects in offspring fed HFD. These results suggest that circulating maternal leptin concentrations may interact with other factors in the pre- and post -natal environments to contribute to altered vascular function in offspring of diabetic pregnancies. PMID:27187080

  12. Vorinostat differentially alters 3D nuclear structure of cancer and non-cancerous esophageal cells.

    PubMed

    Nandakumar, Vivek; Hansen, Nanna; Glenn, Honor L; Han, Jessica H; Helland, Stephanie; Hernandez, Kathryn; Senechal, Patti; Johnson, Roger H; Bussey, Kimberly J; Meldrum, Deirdre R

    2016-08-09

    The histone deacetylase (HDAC) inhibitor vorinostat has received significant attention in recent years as an 'epigenetic' drug used to treat solid tumors. However, its mechanisms of action are not entirely understood, particularly with regard to its interaction with the aberrations in 3D nuclear structure that accompany neoplastic progression. We investigated the impact of vorinostat on human esophageal epithelial cell lines derived from normal, metaplastic (pre-cancerous), and malignant tissue. Using a combination of novel optical computed tomography (CT)-based quantitative 3D absorption microscopy and conventional confocal fluorescence microscopy, we show that subjecting malignant cells to vorinostat preferentially alters their 3D nuclear architecture relative to non-cancerous cells. Optical CT (cell CT) imaging of fixed single cells showed that drug-treated cancer cells exhibit significant alterations in nuclear morphometry. Confocal microscopy revealed that vorinostat caused changes in the distribution of H3K9ac-marked euchromatin and H3K9me3-marked constitutive heterochromatin. Additionally, 3D immuno-FISH showed that drug-induced expression of the DNA repair gene MGMT was accompanied by spatial relocation toward the center of the nucleus in the nuclei of metaplastic but not in non-neoplastic cells. Our data suggest that vorinostat's differential modulation of 3D nuclear architecture in normal and abnormal cells could play a functional role in its anti-cancer action.

  13. α-Viniferin-Induced Structural and Functional Alterations in Raillietina echinobothrida, a Poultry Tapeworm.

    PubMed

    Roy, Bishnupada; Giri, Bikash R

    2015-04-01

    α-Viniferin, an active component of the plant Carex baccans L., is known for its anticancer, antidiabetic, and anti-inflammatory properties. In Northeast India, different tribes traditionally consume C. baccans to control intestinal helminth infections. Therefore, the present study was carried out to assess the extent of tegumental alteration caused by α-viniferin in Raillietina echinobothrida, a widely prevalent poultry helminth in northeast India. Helminths were exposed in vitro to various doses of α-viniferin (50, 100, and 200 µM/mL of physiological buffered saline) and their motility and mortality were recorded. Stereoscan observations on the parasite exposed to the active compound showed extensive distortion and destruction of the surface fine topography of the tegument compared with controls. The compound also caused extensive damage to the tegument by disintegration of microtriches, disorganization of muscle bundles, and loss of cellular organelles combined with distortion and disruption of the plasma membrane, nuclear membrane, nucleolus, mitochondrial membrane, and cristae. Histochemical and biochemical studies carried out parasites exposed to α-viniferin revealed a decline in the activity of vital tegumental enzymes like acid phosphatase, alkaline phosphatase, and adenosine triphosphatase. Extensive structural and functional alterations observed in the treated parasites are indicative of efficient cestocidal activity of the compound.

  14. Vorinostat differentially alters 3D nuclear structure of cancer and non-cancerous esophageal cells

    PubMed Central

    Nandakumar, Vivek; Hansen, Nanna; Glenn, Honor L.; Han, Jessica H.; Helland, Stephanie; Hernandez, Kathryn; Senechal, Patti; Johnson, Roger H.; Bussey, Kimberly J.; Meldrum, Deirdre R.

    2016-01-01

    The histone deacetylase (HDAC) inhibitor vorinostat has received significant attention in recent years as an ‘epigenetic’ drug used to treat solid tumors. However, its mechanisms of action are not entirely understood, particularly with regard to its interaction with the aberrations in 3D nuclear structure that accompany neoplastic progression. We investigated the impact of vorinostat on human esophageal epithelial cell lines derived from normal, metaplastic (pre-cancerous), and malignant tissue. Using a combination of novel optical computed tomography (CT)-based quantitative 3D absorption microscopy and conventional confocal fluorescence microscopy, we show that subjecting malignant cells to vorinostat preferentially alters their 3D nuclear architecture relative to non-cancerous cells. Optical CT (cell CT) imaging of fixed single cells showed that drug-treated cancer cells exhibit significant alterations in nuclear morphometry. Confocal microscopy revealed that vorinostat caused changes in the distribution of H3K9ac-marked euchromatin and H3K9me3-marked constitutive heterochromatin. Additionally, 3D immuno-FISH showed that drug-induced expression of the DNA repair gene MGMT was accompanied by spatial relocation toward the center of the nucleus in the nuclei of metaplastic but not in non-neoplastic cells. Our data suggest that vorinostat’s differential modulation of 3D nuclear architecture in normal and abnormal cells could play a functional role in its anti-cancer action. PMID:27503568

  15. Experience-dependent plasticity in white matter microstructure: reasoning training alters structural connectivity.

    PubMed

    Mackey, Allyson P; Whitaker, Kirstie J; Bunge, Silvia A

    2012-01-01

    Diffusion tensor imaging (DTI) techniques have made it possible to investigate white matter plasticity in humans. Changes in DTI measures, principally increases in fractional anisotropy (FA), have been observed following training programs as diverse as juggling, meditation, and working memory. Here, we sought to test whether three months of reasoning training could alter white matter microstructure. We recruited participants (n = 23) who were enrolled in a course to prepare for the Law School Admission Test (LSAT), a test that places strong demands on reasoning skills, as well as age- and IQ-matched controls planning to take the LSAT in the future (n = 22). DTI data were collected at two scan sessions scheduled three months apart. In trained participants but not controls, we observed decreases in radial diffusivity (RD) in white matter connecting frontal cortices, and in mean diffusivity (MD) within frontal and parietal lobe white matter. Further, participants exhibiting larger gains on the LSAT exhibited greater decreases in MD in the right internal capsule. In summary, reasoning training altered multiple measures of white matter structure in young adults. While the cellular underpinnings are unknown, these results provide evidence of experience-dependent white matter changes that may not be limited to myelination.

  16. Altered neurotransmitter release, vesicle recycling and presynaptic structure in the pilocarpine model of temporal lobe epilepsy

    PubMed Central

    Upreti, Chirag; Otero, Rafael; Partida, Carlos; Skinner, Frank; Thakker, Ravi; Pacheco, Luis F.; Zhou, Zhen-yu; Maglakelidze, Giorgi; Velíšková, Jana; Velíšek, Libor; Romanovicz, Dwight; Jones, Theresa; Stanton, Patric K.

    2012-01-01

    In searching for persistent seizure-induced alterations in brain function that might be causally related to epilepsy, presynaptic transmitter release has relatively been neglected. To measure directly the long-term effects of pilocarpine-induced status epilepticus on vesicular release and recycling in hippocampal mossy fibre presynaptic boutons, we used (i) two-photon imaging of FM1-43 vesicular release in rat hippocampal slices; and (ii) transgenic mice expressing the genetically encoded pH-sensitive fluorescent reporter synaptopHluorin preferentially at glutamatergic synapses. In this study we found that, 1–2 months after pilocarpine-induced status epilepticus, there were significant increases in mossy fibre bouton size, faster rates of action potential-driven vesicular release and endocytosis. We also analysed the ultrastructure of rat mossy fibre boutons using transmission electron microscopy. Pilocarpine-induced status epilepticus led to a significant increase in the number of release sites, active zone length, postsynaptic density area and number of vesicles in the readily releasable and recycling pools, all correlated with increased release probability. Our data show that presynaptic release machinery is persistently altered in structure and function by status epilepticus, which could contribute to the development of the chronic epileptic state and may represent a potential new target for antiepileptic therapies. PMID:22344585

  17. Electronic structures of [001]- and [111]-oriented InSb and GaSb free-standing nanowires

    SciTech Connect

    Liao, Gaohua; Luo, Ning; Yang, Zhihu; Chen, Keqiu; Xu, H. Q. E-mail: hongqi.xu@ftf.lth.se

    2015-09-07

    We report on a theoretical study of the electronic structures of InSb and GaSb nanowires oriented along the [001] and [111] crystallographic directions. The nanowires are described by atomistic, tight-binding models, including spin-orbit interaction. The band structures and the wave functions of the nanowires are calculated by means of a Lanczos iteration algorithm. For the [001]-oriented InSb and GaSb nanowires, the systems with both square and rectangular cross sections are considered. Here, it is found that all the energy bands are doubly degenerate. Although the lowest conduction bands in these nanowires show good parabolic dispersions, the top valence bands show rich and complex structures. In particular, the topmost valence bands of the nanowires with a square cross section show a double maximum structure. In the nanowires with a rectangular cross section, this double maximum structure is suppressed, and the top valence bands gradually develop into parabolic bands as the aspect ratio of the cross section is increased. For the [111]-oriented InSb and GaSb nanowires, the systems with hexagonal cross sections are considered. It is found that all the bands at the Γ-point are again doubly degenerate. However, some of them will split into non-degenerate bands when the wave vector moves away from the Γ-point. Although the lowest conduction bands again show good parabolic dispersions, the topmost valence bands do not show the double maximum structure. Instead, they show a single maximum structure with its maximum at a wave vector slightly away from the Γ-point. The wave functions of the band states near the band gaps of the [001]- and [111]-oriented InSb and GaSb nanowires are also calculated and are presented in terms of probability distributions in the cross sections. It is found that although the probability distributions of the band states in the [001]-oriented nanowires with a rectangular cross section could be qualitatively described by one-band effective

  18. Structural and functional alterations in Malpighian tubules as biomarkers of environmental pollution: synopsis and prospective.

    PubMed

    Giglio, Anita; Brandmayr, Pietro

    2017-03-06

    Although a number of biomarkers of pollutant exposure have been identified in invertebrate species, little is known about the effect on Malpighian tubules playing an essential role in excretion and osmoregulation. Analyses of structural and functional alterations on this organ can be useful to predict the effects at the organism and population level in monitoring studies of environmental pollution. The aim of the present review is to provide a synthesis of existing knowledge on cellular damages induced by xenobiotics in Malpighian tubules both under laboratory and field conditions. We compared studies of exposure to pesticides and heavy metals as mainly environmental contaminants from anthropogenic activities. This report provided evidence that the exposure to xenobiotics has an effect on this organ and reinforces the need for further research integrating molecular biomarkers with analysis on Malpighian tubules. Copyright © 2017 John Wiley & Sons, Ltd.

  19. Evasion of Innate Immune Responses by the Highly Virulent Cryptococcus gattii by Altering Capsule Glucuronoxylomannan Structure.

    PubMed

    Urai, Makoto; Kaneko, Yukihiro; Ueno, Keigo; Okubo, Yoichiro; Aizawa, Tomoko; Fukazawa, Hidesuke; Sugita, Takashi; Ohno, Hideaki; Shibuya, Kazutoshi; Kinjo, Yuki; Miyazaki, Yoshitsugu

    2015-01-01

    Cryptococcus neoformans causes life-threatening diseases mainly in immunosuppressed hosts such as AIDS patients; C. gattii causes disseminated infections even in healthy hosts. To identify the possible molecular mechanisms underlying this difference in virulence, we investigated the survival and histopathology of lung tissue in wild-type and CD4-depleted mice infected with C. neoformans H99 and C. gattii JP02 (the highly virulent strain isolated in Japan); we then compared dendritic cell (DC) cytokine release responses to different cell fractions from these two strains. JP02-infected mice exhibited shorter survival and fewer inflammatory cells in the lung than H99-infected control mice. Depletion of CD4-related cellular immunity reduced survival of H99-infected mice but had no effect on the survival or inflammatory cell infiltration in JP02-infected mice, suggesting that JP02 evades immune detection. To identify the molecule(s) conferring this difference, we measured cytokine production from murine DCs co-cultured with H99 and JP02 in vitro. The levels of inflammatory cytokines from DCs treated with intact JP02 cells, the extracted capsule, secreted extracellular polysaccharides, and purified glucuronoxylomannan (GXM) were markedly lower than those induced by intact H99 cells and corresponding H99 fractions. Structural analysis of GXM indicated that JP02 altered one of two O-acetyl groups detected in the H99 GXM. Deacetylated GXM lost the ability to induce inflammatory cytokine release from DCs, implicating these O-acetyl groups in immune recognition. We conclude that the highly virulent C. gattii processes a structural alteration in GXM that allows this pathogen to evade the immune response and therefore elimination.

  20. Alterations in Brain Structure and Functional Connectivity in Alcohol Dependent Patients and Possible Association with Impulsivity

    PubMed Central

    Dong, Yue; Ma, Mengying; Ma, Yi; Dong, Yuru; Niu, Yajuan; Jiang, Yin; Wang, Hong; Wang, Zhiyan; Wu, Liuzhen; Sun, Hongqiang; Cui, Cailian

    2016-01-01

    Background Previous studies have documented that heightened impulsivity likely contributes to the development and maintenance of alcohol use disorders. However, there is still a lack of studies that comprehensively detected the brain changes associated with abnormal impulsivity in alcohol addicts. This study was designed to investigate the alterations in brain structure and functional connectivity associated with abnormal impulsivity in alcohol dependent patients. Methods Brain structural and functional magnetic resonance imaging data as well as impulsive behavior data were collected from 20 alcohol dependent patients and 20 age- and sex-matched healthy controls respectively. Voxel-based morphometry was used to investigate the differences of grey matter volume, and tract-based spatial statistics was used to detect abnormal white matter regions between alcohol dependent patients and healthy controls. The alterations in resting-state functional connectivity in alcohol dependent patients were examined using selected brain areas with gray matter deficits as seed regions. Results Compared with healthy controls, alcohol dependent patients had significantly reduced gray matter volume in the mesocorticolimbic system including the dorsal posterior cingulate cortex, the dorsal anterior cingulate cortex, the medial prefrontal cortex, the orbitofrontal cortex and the putamen, decreased fractional anisotropy in the regions connecting the damaged grey matter areas driven by higher radial diffusivity value in the same areas and decreased resting-state functional connectivity within the reward network. Moreover, the gray matter volume of the left medial prefrontal cortex exhibited negative correlations with various impulse indices. Conclusions These findings suggest that chronic alcohol dependence could cause a complex neural changes linked to abnormal impulsivity. PMID:27575491

  1. Evasion of Innate Immune Responses by the Highly Virulent Cryptococcus gattii by Altering Capsule Glucuronoxylomannan Structure

    PubMed Central

    Urai, Makoto; Kaneko, Yukihiro; Ueno, Keigo; Okubo, Yoichiro; Aizawa, Tomoko; Fukazawa, Hidesuke; Sugita, Takashi; Ohno, Hideaki; Shibuya, Kazutoshi; Kinjo, Yuki; Miyazaki, Yoshitsugu

    2016-01-01

    Cryptococcus neoformans causes life-threatening diseases mainly in immunosuppressed hosts such as AIDS patients; C. gattii causes disseminated infections even in healthy hosts. To identify the possible molecular mechanisms underlying this difference in virulence, we investigated the survival and histopathology of lung tissue in wild-type and CD4-depleted mice infected with C. neoformans H99 and C. gattii JP02 (the highly virulent strain isolated in Japan); we then compared dendritic cell (DC) cytokine release responses to different cell fractions from these two strains. JP02-infected mice exhibited shorter survival and fewer inflammatory cells in the lung than H99-infected control mice. Depletion of CD4-related cellular immunity reduced survival of H99-infected mice but had no effect on the survival or inflammatory cell infiltration in JP02-infected mice, suggesting that JP02 evades immune detection. To identify the molecule(s) conferring this difference, we measured cytokine production from murine DCs co-cultured with H99 and JP02 in vitro. The levels of inflammatory cytokines from DCs treated with intact JP02 cells, the extracted capsule, secreted extracellular polysaccharides, and purified glucuronoxylomannan (GXM) were markedly lower than those induced by intact H99 cells and corresponding H99 fractions. Structural analysis of GXM indicated that JP02 altered one of two O-acetyl groups detected in the H99 GXM. Deacetylated GXM lost the ability to induce inflammatory cytokine release from DCs, implicating these O-acetyl groups in immune recognition. We conclude that the highly virulent C. gattii processes a structural alteration in GXM that allows this pathogen to evade the immune response and therefore elimination. PMID:26779451

  2. Histone H3 phosphorylation near the nucleosome dyad alters chromatin structure.

    PubMed

    North, Justin A; Šimon, Marek; Ferdinand, Michelle B; Shoffner, Matthew A; Picking, Jonathan W; Howard, Cecil J; Mooney, Alex M; van Noort, John; Poirier, Michael G; Ottesen, Jennifer J

    2014-04-01

    Nucleosomes contain ∼146 bp of DNA wrapped around a histone protein octamer that controls DNA accessibility to transcription and repair complexes. Posttranslational modification (PTM) of histone proteins regulates nucleosome function. To date, only modest changes in nucleosome structure have been directly attributed to histone PTMs. Histone residue H3(T118) is located near the nucleosome dyad and can be phosphorylated. This PTM destabilizes nucleosomes and is implicated in the regulation of transcription and repair. Here, we report gel electrophoretic mobility, sucrose gradient sedimentation, thermal disassembly, micrococcal nuclease digestion and atomic force microscopy measurements of two DNA-histone complexes that are structurally distinct from nucleosomes. We find that H3(T118ph) facilitates the formation of a nucleosome duplex with two DNA molecules wrapped around two histone octamers, and an altosome complex that contains one DNA molecule wrapped around two histone octamers. The nucleosome duplex complex forms within short ∼150 bp DNA molecules, whereas altosomes require at least ∼250 bp of DNA and form repeatedly along 3000 bp DNA molecules. These results are the first report of a histone PTM significantly altering the nucleosome structure.

  3. Structural basis for the alteration of coenzyme specificity in a malate dehydrogenase mutant

    SciTech Connect

    Tomita, Takeo; Fushinobu, Shinya; Kuzuyama, Tomohisa; Nishiyama, Makoto . E-mail: umanis@mail.ecc.u-tokyo.ac.jp

    2006-08-25

    To elucidate the structural basis for the alteration of coenzyme specificity from NADH toward NADPH in a malate dehydrogenase mutant EX7 from Thermus flavus, we determined the crystal structures at 2.0 A resolution of EX7 complexed with NADPH and NADH, respectively. In the EX7-NADPH complex, Ser42 and Ser45 form hydrogen bonds with the 2'-phosphate group of the adenine ribose of NADPH, although the adenine moiety is not seen in the electron density map. In contrast, although Ser42 and Ser45 occupy a similar position in the EX7-NADH complex structure, both the adenine and adenine ribose moieties of NADH are missing in the map. These results and kinetic analysis of site-directed mutant enzymes indicate (1) that the preference of EX7 for NADPH over NADH is ascribed to the recognition of the 2'-phosphate group by two Ser and Arg44, and (2) that the adenine moiety of NADPH is not recognized in this mutant.

  4. Resources Alter the Structure and Increase Stochasticity in Bromeliad Microfauna Communities

    PubMed Central

    Petermann, Jana S.; Kratina, Pavel; Marino, Nicholas A. C.; MacDonald, A. Andrew M.; Srivastava, Diane S.

    2015-01-01

    Although stochastic and deterministic processes have been found to jointly shape structure of natural communities, the relative importance of both forces may vary across different environmental conditions and across levels of biological organization. We tested the effects of abiotic environmental conditions, altered trophic interactions and dispersal limitation on the structure of aquatic microfauna communities in Costa Rican tank bromeliads. Our approach combined natural gradients in environmental conditions with experimental manipulations of bottom-up interactions (resources), top-down interactions (predators) and dispersal at two spatial scales in the field. We found that resource addition strongly increased the abundance and reduced the richness of microfauna communities. Community composition shifted in a predictable way towards assemblages dominated by flagellates and ciliates but with lower abundance and richness of algae and amoebae. While all functional groups responded strongly and predictably to resource addition, similarity among communities at the species level decreased, suggesting a role of stochasticity in species-level assembly processes. Dispersal limitation did not affect the communities. Since our design excluded potential priority effects we can attribute the differences in community similarity to increased demographic stochasticity of resource-enriched communities related to erratic changes in population sizes of some species. In contrast to resources, predators and environmental conditions had negligible effects on community structure. Our results demonstrate that bromeliad microfauna communities are strongly controlled by bottom-up forces. They further suggest that the relative importance of stochasticity may change with productivity and with the organizational level at which communities are examined. PMID:25775464

  5. Resources alter the structure and increase stochasticity in bromeliad microfauna communities.

    PubMed

    Petermann, Jana S; Kratina, Pavel; Marino, Nicholas A C; MacDonald, A Andrew M; Srivastava, Diane S

    2015-01-01

    Although stochastic and deterministic processes have been found to jointly shape structure of natural communities, the relative importance of both forces may vary across different environmental conditions and across levels of biological organization. We tested the effects of abiotic environmental conditions, altered trophic interactions and dispersal limitation on the structure of aquatic microfauna communities in Costa Rican tank bromeliads. Our approach combined natural gradients in environmental conditions with experimental manipulations of bottom-up interactions (resources), top-down interactions (predators) and dispersal at two spatial scales in the field. We found that resource addition strongly increased the abundance and reduced the richness of microfauna communities. Community composition shifted in a predictable way towards assemblages dominated by flagellates and ciliates but with lower abundance and richness of algae and amoebae. While all functional groups responded strongly and predictably to resource addition, similarity among communities at the species level decreased, suggesting a role of stochasticity in species-level assembly processes. Dispersal limitation did not affect the communities. Since our design excluded potential priority effects we can attribute the differences in community similarity to increased demographic stochasticity of resource-enriched communities related to erratic changes in population sizes of some species. In contrast to resources, predators and environmental conditions had negligible effects on community structure. Our results demonstrate that bromeliad microfauna communities are strongly controlled by bottom-up forces. They further suggest that the relative importance of stochasticity may change with productivity and with the organizational level at which communities are examined.

  6. The constant region affects antigen binding of antibodies to DNA by altering secondary structure.

    PubMed

    Xia, Yumin; Janda, Alena; Eryilmaz, Ertan; Casadevall, Arturo; Putterman, Chaim

    2013-11-01

    We previously demonstrated an important role of the constant region in the pathogenicity of anti-DNA antibodies. To determine the mechanisms by which the constant region affects autoantibody binding, a panel of isotype-switch variants (IgG1, IgG2a, IgG2b) was generated from the murine PL9-11 IgG3 autoantibody. The affinity of the PL9-11 antibody panel for histone was measured by surface plasmon resonance (SPR). Tryptophan fluorescence was used to determine wavelength shifts of the antibody panel upon binding to DNA and histone. Finally, circular dichroism spectroscopy was used to measure changes in secondary structure. SPR analysis revealed significant differences in histone binding affinity between members of the PL9-11 panel. The wavelength shifts of tryptophan fluorescence emission were found to be dependent on the antibody isotype, while circular dichroism analysis determined that changes in antibody secondary structure content differed between isotypes upon antigen binding. Thus, the antigen binding affinity is dependent on the particular constant region expressed. Moreover, the effects of antibody binding to antigen were also constant region dependent. Alteration of secondary structures influenced by constant regions may explain differences in fine specificity of anti-DNA antibodies between antibodies with similar variable regions, as well as cross-reactivity of anti-DNA antibodies with non-DNA antigens.

  7. Changes in carbon pool and stand structure of a native subtropical mangrove forest after inter-planting with exotic species Sonneratia apetala.

    PubMed

    Lu, Weizhi; Yang, Shengchang; Chen, Luzhen; Wang, Wenqing; Du, Xiaona; Wang, Canmou; Ma, Yan; Lin, Guangxuan; Lin, Guanghui

    2014-01-01

    In this study, we compared stand structure, biomass and soil carbon pools, and litterfall production between a mixed mangrove forest consisting of Aegiceras corniculatum inter-planted with the exotic Sonneratia apetala and a native monospecific forest dominated by A. corniculatum in the intertidal area of Zhanjiang, Guangdong Province, southeast China. The goal of this study was to test the hypothesis that inter-planting fast growing exotic mangrove S. apetala into subtropical native mangrove forests will significantly increase C sequestration. Although the tree heights and basal diameters of S. apetala were significantly higher than those of A. corniculatum, the density of the 12-year-old S. apetala trees in the mixed forest was much smaller than that of A. corniculatum in the monospecific forest. In contrast to several previous studies on S. apetala forests planted directly on mangrove-free mudflats, the mixed mangrove forest showed no significant difference in either standing biomass or soil carbon pools from the native monospecific mangrove forest (p = 0.294 and 0.073, respectively) twelve years after inter-planting with S. apetala. Moreover, carbon cycling was likely speeded up after inter-planting S. apetala due to higher litterfall input and lower C/N ratio. Thus, inter-planting fast-growing S. apetala into native mangrove forest is not an effective way to increase carbon sequestration in this subtropical mangrove forest. Given that exotic plant species may exert negative impact on native mangrove species and related epifauna, this fast-growing mangrove species is not suitable for mangrove plantation projects aiming mainly at enhancing carbon sequestration.

  8. Changes in Carbon Pool and Stand Structure of a Native Subtropical Mangrove Forest after Inter-Planting with Exotic Species Sonneratia apetala

    PubMed Central

    Lu, Weizhi; Yang, Shengchang; Chen, Luzhen; Wang, Wenqing; Du, Xiaona; Wang, Canmou; Ma, Yan; Lin, Guangxuan; Lin, Guanghui

    2014-01-01

    In this study, we compared stand structure, biomass and soil carbon pools, and litterfall production between a mixed mangrove forest consisting of Aegiceras corniculatum inter-planted with the exotic Sonneratia apetala and a native monospecific forest dominated by A. corniculatum in the intertidal area of Zhanjiang, Guangdong Province, southeast China. The goal of this study was to test the hypothesis that inter-planting fast growing exotic mangrove S. apetala into subtropical native mangrove forests will significantly increase C sequestration. Although the tree heights and basal diameters of S. apetala were significantly higher than those of A. corniculatum, the density of the 12-year-old S. apetala trees in the mixed forest was much smaller than that of A. corniculatum in the monospecific forest. In contrast to several previous studies on S. apetala forests planted directly on mangrove-free mudflats, the mixed mangrove forest showed no significant difference in either standing biomass or soil carbon pools from the native monospecific mangrove forest (p = 0.294 and 0.073, respectively) twelve years after inter-planting with S. apetala. Moreover, carbon cycling was likely speeded up after inter-planting S. apetala due to higher litterfall input and lower C/N ratio. Thus, inter-planting fast-growing S. apetala into native mangrove forest is not an effective way to increase carbon sequestration in this subtropical mangrove forest. Given that exotic plant species may exert negative impact on native mangrove species and related epifauna, this fast-growing mangrove species is not suitable for mangrove plantation projects aiming mainly at enhancing carbon sequestration. PMID:24618793

  9. Structurally similar estradiol analogs uniquely alter the regulation of intracellular signaling pathways.

    PubMed

    Yarger, James G; Babine, Robert E; Bittner, Michael; Shanle, Erin; Xu, Wei; Hershberger, Pamela; Nye, Steven H

    2013-02-01

    Ligand structure can affect the activation of nuclear receptors, such as estrogen receptors (ERs), and their control of signaling pathways for cellular responses including death and differentiation. We hypothesized that distinct biological functions of similar estradiol (E(2)) analogs could be identified by integrating gene expression patterns obtained from human tumor cell lines with receptor binding and functional data for the purpose of developing compounds for treatment of a variety of diseases. We compared the estrogen receptor subtype selectivity and impact on signaling pathways for three distinct, but structurally similar, analogs of E(2). Modifications in the core structure of E(2) led to pronounced changes in subtype selectivity for estrogen receptors, ER-α or ER-β, along with varying degrees of ER dimerization and activation. While all three E(2) analogs are predominantly ER-β agonists, the cell growth inhibitory activity commonly associated with this class of compounds was detected for only two of the analogs and might be explained by a ligand-specific pattern of gene transcription. Microarray studies using three different human tumor cell lines demonstrated that the analogs distinctly affect the transcription of genes in signaling pathways for chromosome replication, cell death, and oligodendrocyte progenitor cell differentiation. That the E(2) analogs could lower tumor cell viability and stimulate neuronal differentiation confirmed that gene expression data could accurately distinguish biological activity of the E(2) analogs. The findings reported here confirm that cellular responses can be regulated by making key structural alterations to the core structure of endogenous ER ligands.

  10. Free-standing chiral plasmonics

    NASA Astrophysics Data System (ADS)

    Leong, Eunice Sok Ping; Deng, Jie; Wu, Siji; Khoo, Eng Huat; Liu, Yan Jun

    2014-11-01

    Chiral plasmonic nanostructures offer the ability to achieve strong optical circular dichroism (CD) activity over a broad spectral range, which has been challenging for chiral molecules. Chiral plasmonic nanostructures have been extensively studied based on top-down and bottom-up fabrication techniques. Particularly, in the top-down electron-beam lithography, 3D plasmonic nanostructure fabrication involves layer-by-layer patterning and complex alignment, which is time-consuming and causes many defects in the structures. Here, we present a free-standing 3D chiral plamonic nanostructures using the electron-beam lithography technique with much simplified fabrication processes. The 3D chiral plasmonic nanostructures consist of a free-standing ultrathin silicon nitride membrane with well-aligned L-shape metal nanostructures on one side and disk-shape ones on the other side. The free-standing membrane provides an ultra-smooth metal/dielectric interface and uniformly defines the gap between the upper and lower layers in an array of chiral nanostructures. Such free-standing chiral plasmonic nanostructures exhibit strong CD at optical frequencies, which can be engineered by simply changing the disk size on one side of the membrane. Experimental results are in good agreement with the finite-difference time-domain simulations. Such free-standing chiral plasmonics holds great potential for chirality analysis of biomolecules, drugs, and chemicals.

  11. [The value of double contrast arthrotomography combined with cinematography in the diagnosis of functional and structural TMJ alterations].

    PubMed

    Engelke, W; Grossniklaus, B; Sailer, H F

    1991-01-01

    Double contrast arthrotomography combined with cinematography as a diagnostic instrument establishing functional and structural TMJ alterations is evaluated for its diagnostic value and reliability within the chain of diagnostic measures applied. In 131 patients double-contrast arthrotomography was followed by a comprehensive history of joint problems, and verification of the clinical findings as well as the arthrographic diagnosis and the post-arthrographic TMJ alterations. Our interest was focussed, among others, on the question whether arthrography alone would have any therapeutic effect or produce an alteration in TMJ function.

  12. Different methods to alter surface morphology of high aspect ratio structures

    PubMed Central

    Leber, M.; Shandhi, M. M. H.; Hogan, A.; Solzbacher, F.; Bhandari, R.; Negi, S.

    2016-01-01

    In various applications such as neural prostheses or solar cells, there is a need to alter the surface morphology of high aspect ratio structures so that the real surface area is greater than geometrical area. The change in surface morphology enhances the devices functionality. One of the applications of altering the surface morphology is of neural implants such as the Utah electrode array (UEA) that communicate with single neurons by charge injection induced stimulation or by recording electrical neural signals. For high selectivity between single cells of the nervous system, the electrode surface area is required to be as small as possible, while the impedance is required to be as low as possible for good signal to noise ratios (SNR) during neural recording. For stimulation, high charge injection and charge transfer capacities of the electrodes are required, which increase with the electrode surface. Traditionally, researchers have worked with either increasing the roughness of the existing metallization (Platinum grey, black) or other materials such as Iridium Oxide and PEDOT. All of these previously investigated methods lead to more complicated metal deposition processes that are difficult to control and often have a critical impact on the mechanical properties of the metal films. Therefore, a modification of the surface underneath the electrode’s coating will increase its surface area while maintaining the standard and well controlled metal deposition process. In this work, the surfaces of the Silicon micro-needles were engineered by creating a defined microstructure on the electrodes surface using several methods such as Laser ablation, focused ion beam, sputter etching, reactive ion etching (RIE) and deep reactive ion etching (DRIE). The surface modification processes were optimized for the high aspect ratio Silicon structures of the UEA. The increase in real surface area while maintaining the geometrical surface area was verified using scanning electron

  13. Different methods to alter surface morphology of high aspect ratio structures

    NASA Astrophysics Data System (ADS)

    Leber, M.; Shandhi, M. M. H.; Hogan, A.; Solzbacher, F.; Bhandari, R.; Negi, S.

    2016-03-01

    In various applications such as neural prostheses or solar cells, there is a need to alter the surface morphology of high aspect ratio structures so that the real surface area is greater than geometrical area. The change in surface morphology enhances the devices functionality. One of the applications of altering the surface morphology is of neural implants such as the Utah electrode array (UEA) that communicate with single neurons by charge injection induced stimulation or by recording electrical neural signals. For high selectivity between single cells of the nervous system, the electrode surface area is required to be as small as possible, while the impedance is required to be as low as possible for good signal to noise ratios (SNR) during neural recording. For stimulation, high charge injection and charge transfer capacities of the electrodes are required, which increase with the electrode surface. Traditionally, researchers have worked with either increasing the roughness of the existing metallization (platinum grey, black) or other materials such as Iridium Oxide and PEDOT. All of these previously investigated methods lead to more complicated metal deposition processes that are difficult to control and often have a critical impact on the mechanical properties of the metal films. Therefore, a modification of the surface underneath the electrode's coating will increase its surface area while maintaining the standard and well controlled metal deposition process. In this work, the surfaces of the silicon micro-needles were engineered by creating a defined microstructure on the electrodes surface using several methods such as laser ablation, focused ion beam, sputter etching, reactive ion etching (RIE) and deep reactive ion etching (DRIE). The surface modification processes were optimized for the high aspect ratio silicon structures of the UEA. The increase in real surface area while maintaining the geometrical surface area was verified using scanning electron

  14. Different methods to alter surface morphology of high aspect ratio structures.

    PubMed

    Leber, M; Shandhi, M M H; Hogan, A; Solzbacher, F; Bhandari, R; Negi, S

    2016-03-01

    In various applications such as neural prostheses or solar cells, there is a need to alter the surface morphology of high aspect ratio structures so that the real surface area is greater than geometrical area. The change in surface morphology enhances the devices functionality. One of the applications of altering the surface morphology is of neural implants such as the Utah electrode array (UEA) that communicate with single neurons by charge injection induced stimulation or by recording electrical neural signals. For high selectivity between single cells of the nervous system, the electrode surface area is required to be as small as possible, while the impedance is required to be as low as possible for good signal to noise ratios (SNR) during neural recording. For stimulation, high charge injection and charge transfer capacities of the electrodes are required, which increase with the electrode surface. Traditionally, researchers have worked with either increasing the roughness of the existing metallization (Platinum grey, black) or other materials such as Iridium Oxide and PEDOT. All of these previously investigated methods lead to more complicated metal deposition processes that are difficult to control and often have a critical impact on the mechanical properties of the metal films. Therefore, a modification of the surface underneath the electrode's coating will increase its surface area while maintaining the standard and well controlled metal deposition process. In this work, the surfaces of the Silicon micro-needles were engineered by creating a defined microstructure on the electrodes surface using several methods such as Laser ablation, focused ion beam, sputter etching, reactive ion etching (RIE) and deep reactive ion etching (DRIE). The surface modification processes were optimized for the high aspect ratio Silicon structures of the UEA. The increase in real surface area while maintaining the geometrical surface area was verified using scanning electron

  15. Alterations of CNS structure & function by charged particle radiation & resultant oxidative stress

    NASA Astrophysics Data System (ADS)

    Nelson, Gregory; Chang, Polly; Favre, Cecile; Fike, John; Komarova, Natalia; Limoli, Charles; Mao, Xiao-Wen; Obenaus, Andre; Raber, Jacob; Spigelman, Igor; Soltesz, Ivan; Song, Sheng-Kwei; Stampanoni, Marco; Vlkolinsky, Roman; Wodarz, Dominik

    The NSCOR program project is transitioning from establishing the existence of CNS responses to low doses of charged particles, to an investigation of mechanisms underlying these changes and extending the irradiation paradigm to more space-like exposures. In earlier experiments we examined radiation responses of the mouse brain (hippocampus) following exposure to 250 MeV protons and 600 MeV/n iron ions. Our key findings on structural changes were: 1) Significant dose and time dependent loss of en-dothelial cells and microvessel network remodeling occurs suggesting that vascular insufficiency is produced. 2) Significant dose dependent losses of neural precursor cells were observed in a lineage specific pattern which may be associated with cognitive impairment. 3) Evaluation of DNA damage showed dose and time dependent accumulation of mutations with region-specific mutation structures and gene expression profiling demonstrated activation of neurotrophic and adhesion factors as well as chemokine receptors associated with inflammation. Our key find-ings on functional changes were: 1) Time and dose dependent modifications to neural output expressed as enhanced excitability but reduced synaptic efficacy and plasticity (including long term potentiation). 2) Intrinsic membrane properties of neurons were not significantly modi-fied by radiation exposure but pharmacological treatments demonstrated changes in inhibitory synapses. 3) MRI imaging visualized brain structural changes based on altered water diffu-sion properties and patterns were consistent with demyelination or gliosis. Our key findings on neurodegeneration and fidelity of homeostasis were: 1) APP23 transgenic mice exhibited accelerated APP-type electrophysiological pathology over several months. 2) Microvessel net-work changes following irradiation were suggestive of poor tissue oxygenation. 3) The ability of the brain to respond a controlled septic shock was altered by irradiation; the septic shock reactions

  16. Structural and electronic properties of free standing one-sided and two-sided hydrogenated silicene: A first principle study

    SciTech Connect

    Mohan, Brij Kumar, Ashok Ahluwalia, P. K.

    2014-04-24

    We performed first-principle study of the structural and electronic properties of two-dimensional hydrogenated silicene for two configurations; one is hydrogenation along one side of silicene sheet and second is hydrogenation in both sides of silicene sheet. The one-side hydrogenated silicene is found stable at planar geometry while increased buckling of 0.725 Å is found for both-side hydrogenated silicene. The result shows that the hydrogenation occupy the extended π-bonding network of silicene, and thus it exhibits semi-conducting behaviour with a band gap of 1.77 eV and 2.19 eV for one-side hydrogenated silicene and both-side hydrogenated silicene respectively. However, both-side hydrogenated silicene of binding energy 4.56 eV is more stable than one-side hydrogenated silicene of binding energy 4.30 eV, but experimentally silicene is synthesized on substrates which interacts one side of silicene layer and only other side is available for H-atoms. Therefore, practically one-side hydrogenation is also important.

  17. Structural and electronic properties of free standing one-sided and two-sided hydrogenated silicene: A first principle study

    NASA Astrophysics Data System (ADS)

    Mohan, Brij; Kumar, Ashok; Ahluwalia, P. K.

    2014-04-01

    We performed first-principle study of the structural and electronic properties of two-dimensional hydrogenated silicene for two configurations; one is hydrogenation along one side of silicene sheet and second is hydrogenation in both sides of silicene sheet. The one-side hydrogenated silicene is found stable at planar geometry while increased buckling of 0.725 Å is found for both-side hydrogenated silicene. The result shows that the hydrogenation occupy the extended π-bonding network of silicene, and thus it exhibits semi-conducting behaviour with a band gap of 1.77 eV and 2.19 eV for one-side hydrogenated silicene and both-side hydrogenated silicene respectively. However, both-side hydrogenated silicene of binding energy 4.56 eV is more stable than one-side hydrogenated silicene of binding energy 4.30 eV, but experimentally silicene is synthesized on substrates which interacts one side of silicene layer and only other side is available for H-atoms. Therefore, practically one-side hydrogenation is also important.

  18. Diabetic polyneuropathy, sensory neurons, nuclear structure and spliceosome alterations: a role for CWC22

    PubMed Central

    Kobayashi, Masaki; Chandrasekhar, Ambika; Cheng, Chu; Martinez, Jose A.; Ng, Hilarie; de la Hoz, Cristiane

    2017-01-01

    ABSTRACT Unique deficits in the function of adult sensory neurons as part of their early neurodegeneration might account for progressive polyneuropathy during chronic diabetes mellitus. Here, we provide structural and functional evidence for aberrant pre-mRNA splicing in a chronic type 1 model of experimental diabetic polyneuropathy (DPN). Cajal bodies (CBs), unique nuclear substructures involved in RNA splicing, increased in number in diabetic sensory neurons, but their expected colocalization with survival motor neuron (SMN) proteins was reduced – a mislocalization described in motor neurons of spinal muscular atrophy. Small nuclear ribonucleoprotein particles (snRNPs), also participants in the spliceosome, had abnormal multiple nuclear foci unassociated with CBs, and their associated snRNAs were reduced. CWC22, a key spliceosome protein, was aberrantly upregulated in diabetic dorsal root ganglia (DRG), and impaired neuronal function. CWC22 attenuated sensory neuron plasticity, with knockdown in vitro enhancing their neurite outgrowth. Further, axonal delivery of CWC22 siRNA unilaterally to locally knock down the aberrant protein in diabetic nerves improved aspects of sensory function in diabetic mice. Collectively, our findings identify subtle but significant alterations in spliceosome structure and function, including dysregulated CBs and CWC22 overexpression, in diabetic sensory neurons that offer new ideas regarding diabetic sensory neurodegeneration in polyneuropathy. PMID:28250049

  19. The Rcs signal transduction pathway is triggered by enterobacterial common antigen structure alterations in Serratia marcescens.

    PubMed

    Castelli, María E; Véscovi, Eleonora García

    2011-01-01

    The enterobacterial common antigen (ECA) is a highly conserved exopolysaccharide in Gram-negative bacteria whose role remains largely uncharacterized. In a previous work, we have demonstrated that disrupting the integrity of the ECA biosynthetic pathway imposed severe deficiencies to the Serratia marcescens motile (swimming and swarming) capacity. In this work, we show that alterations in the ECA structure activate the Rcs phosphorelay, which results in the repression of the flagellar biogenesis regulatory cascade. In addition, a detailed analysis of wec cluster mutant strains, which provoke the disruption of the ECA biosynthesis at different levels of the pathway, suggests that the absence of the periplasmic ECA cyclic structure could constitute a potential signal detected by the RcsF-RcsCDB phosphorelay. We also identify SMA1167 as a member of the S. marcescens Rcs regulon and show that high osmolarity induces Rcs activity in this bacterium. These results provide a new perspective from which to understand the phylogenetic conservation of ECA among enterobacteria and the basis for the virulence attenuation detected in wec mutant strains in other pathogenic bacteria.

  20. CTCF depletion alters chromatin structure and transcription of myeloid-specific factors.

    PubMed

    Ouboussad, Lylia; Kreuz, Sarah; Lefevre, Pascal F

    2013-10-01

    Differentiation is a multistep process tightly regulated and controlled by complex transcription factor networks. Here, we show that the rate of differentiation of common myeloid precursor cells increases after depletion of CTCF, a protein emerging as a potential key factor regulating higher-order chromatin structure. We identified CTCF binding in the vicinity of important transcription factors regulating myeloid differentiation and showed that CTCF depletion impacts on the expression of these genes in concordance with the observed acceleration of the myeloid commitment. Furthermore, we observed a loss of the histone variant H2A.Z within the selected promoter regions and an increase in non-coding RNA transcription upstream of these genes. Both abnormalities suggest a global chromatin structure destabilization and an associated increase of non-productive transcription in response to CTCF depletion but do not drive the CTCF-mediated transcription alterations of the neighbouring genes. Finally, we detected a transient eviction of CTCF at the Egr1 locus in correlation with Egr1 peak of expression in response to lipopolysaccharide (LPS) treatment in macrophages. This eviction is also correlated with the expression of an antisense non-coding RNA transcribing through the CTCF-binding region indicating that non-coding RNA transcription could be the cause and the consequence of CTCF eviction.

  1. Structural alterations, pore generation, and deacetylation of α- and β-chitin submitted to steam explosion.

    PubMed

    Tan, Too Shen; Chin, Hui Yen; Tsai, Min-Lang; Liu, Chao-Lin

    2015-05-20

    The purpose of this study was to use an environmentally friendly steam explosion method to achieve α- and β-chitin structural alterations, pore generation, and deacetylation, enhancing the degree of deacetylation (DD) in chitin and extending its applications. The samples of α- and β-chitin possessing various moisture contents that were exploded at 9 kg/cm(2) exhibited higher DDs, lower densities, lower crystallinity and more porous structures compared to unexploded chitin. After explosion, β-chitin exhibited a larger expansion ratio, lower crystallinity and contained a larger proportion of small-sized particles compared to α-chitin. The highest DD values of exploded α- and β-chitin with 75% moisture content were 42.9% and 43.7%, respectively. The exploded chitin samples with lower moisture content exhibited lower DDs, densities, crystallinity indices, smaller particle sizes, and higher expansion ratios than the chitin samples with higher moisture content. The chitin samples with lower moisture content also contained larger and more numerous pores.

  2. Human hemoglobin structural and functional alterations and heme degradation upon interaction with benzene: A spectroscopic study.

    PubMed

    Hosseinzadeh, Reza; Moosavi-Movahedi, Ali Akbar

    2016-03-15

    Here, the effect of benzene on hemoglobin structure, stability and heme prosthetic group integrity was studied by different methods. These included UV-vis absorption spectrophotometry, normal and synchronous fluorescence techniques, and differential scanning calorimetry (DSC). Our results indicated that benzene has high hemolytic potential even at low concentrations. The UV-vis spectroscopic results demonstrated that benzene altered both the globin chain and the heme prosthetic group of hemoglobin increasing met- and deoxy-Hb, while decreasing oxy-Hb. However, with increasing benzene the concentration of all species decreased due to heme destruction. The spectrophotometric results show that benzene has a high potential for penetrating the hydrophobic pocket of hemoglobin. These results were consistent with the molecular docking simulation results of benzene-hHb. Aggregation and thermal denaturation studies show that the increased benzene concentration induced hemoglobin aggregation with a decrease in stability, which is consistent with the DSC results. Conventional fluorescence spectroscopy revealed that the heme degradation species were produced in the presence of benzene. The results of constant wavelength synchronous fluorescence spectroscopy (CWSFS) indicated that at least five heme-degraded species were produced. Together, our results indicated that benzene has adverse effects on hemoglobin structure and function, and heme degradation.

  3. Ultraviolet Light Catalyzed Gelation of 3-Methacryloxypropyltrimethoxysilane via Altered Silicate Spatial Structure.

    PubMed

    Wei, Li; Yonggang, Wu; Shukun, Shen; Shaofei, Song; Daodao, Hu

    2016-09-08

    The gelation of 3-methacryloxypropyltrimethoxysilane (MAPTMS) is much more difficult to achieve in conventional conditions. This article describes a novel and concise approach to acquire transparent and firm hybrid gel material by one step promptly without photoinitiator or other tetraalkoxysilane. MAPTMS was hydrolyzed in acidified aqueous solution, which became homogeneous sol in 3 min, and then the sol was irradiated with UV light for a few minutes to form gel. The experimental results indicated that MAPTMS sol gelled in the presence of UV-irradiation was mainly attributed to altering Si-O-Si skeleton structure through hydroxyl radicals, and the gelation originated from the hydrolytic polycondensation of MAPTMS rather than the polymerization of methacryloxy substituent groups. The hydroxyl radicals could break the Si-O-Si ring structure to form cross-linker like species, and these cross-linkers chemically joined linear chains together to form the gel network. This investigation offers not only the photoinduced gelation strategy for MAPTMS sol but also the new insight into the effect of UV-irradiation on the sol-gel process of organotrialkoxysilanes.

  4. Gait variability is altered in older adults when listening to auditory stimuli with differing temporal structures.

    PubMed

    Kaipust, Jeffrey P; McGrath, Denise; Mukherjee, Mukul; Stergiou, Nicholas

    2013-08-01

    Gait variability in the context of a deterministic dynamical system may be quantified using nonlinear time series analyses that characterize the complexity of the system. Pathological gait exhibits altered gait variability. It can be either too periodic and predictable, or too random and disordered, as is the case with aging. While gait therapies often focus on restoration of linear measures such as gait speed or stride length, we propose that the goal of gait therapy should be to restore optimal gait variability, which exhibits chaotic fluctuations and is the balance between predictability and complexity. In this context, our purpose was to investigate how listening to different auditory stimuli affects gait variability. Twenty-seven young and 27 elderly subjects walked on a treadmill for 5 min while listening to white noise, a chaotic rhythm, a metronome, and with no auditory stimulus. Stride length, step width, and stride intervals were calculated for all conditions. Detrended Fluctuation Analysis was then performed on these time series. A quadratic trend analysis determined that an idealized inverted-U shape described the relationship between gait variability and the structure of the auditory stimuli for the elderly group, but not for the young group. This proof-of-concept study shows that the gait of older adults may be manipulated using auditory stimuli. Future work will investigate which structures of auditory stimuli lead to improvements in functional status in older adults.

  5. Human hemoglobin structural and functional alterations and heme degradation upon interaction with benzene: A spectroscopic study

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, Reza; Moosavi-Movahedi, Ali Akbar

    2016-03-01

    Here, the effect of benzene on hemoglobin structure, stability and heme prosthetic group integrity was studied by different methods. These included UV-vis absorption spectrophotometry, normal and synchronous fluorescence techniques, and differential scanning calorimetry (DSC). Our results indicated that benzene has high hemolytic potential even at low concentrations. The UV-vis spectroscopic results demonstrated that benzene altered both the globin chain and the heme prosthetic group of hemoglobin increasing met- and deoxy-Hb, while decreasing oxy-Hb. However, with increasing benzene the concentration of all species decreased due to heme destruction. The spectrophotometric results show that benzene has a high potential for penetrating the hydrophobic pocket of hemoglobin. These results were consistent with the molecular docking simulation results of benzene-hHb. Aggregation and thermal denaturation studies show that the increased benzene concentration induced hemoglobin aggregation with a decrease in stability, which is consistent with the DSC results. Conventional fluorescence spectroscopy revealed that the heme degradation species were produced in the presence of benzene. The results of constant wavelength synchronous fluorescence spectroscopy (CWSFS) indicated that at least five heme-degraded species were produced. Together, our results indicated that benzene has adverse effects on hemoglobin structure and function, and heme degradation.

  6. An experimental disturbance alters fish size structure but not food chain length in streams.

    PubMed

    Walters, Annika W; Post, David M

    2008-12-01

    Streams experience frequent natural disturbance and are undergoing considerable anthropogenic disturbance due to dam construction and water diversion. Disturbance is known to impact community structure, but its effect on food chain length is still a matter of considerable debate. Theoretical models show that longer food chains are less resilient to disturbance, so food chain length is predicted to be shorter following a disturbance event. Here we experimentally test the effect of disturbance on food chain length in streams by diverting stream flow. We found that our experimental low-flow disturbance did not alter food chain length. We did see an effect on body-size structure in our food webs suggesting that food chain length may be an insensitive indicator of disturbance. We suggest that habitat heterogeneity and food web complexity buffer the effect of disturbance on food chain length. The theoretical predictions of disturbance on food chain length are only likely to be seen in homogeneous systems that closely approximate the linear food chains the models are based upon.

  7. Diabetic polyneuropathy, sensory neurons, nuclear structure and spliceosome alterations: a role for CWC22.

    PubMed

    Kobayashi, Masaki; Chandrasekhar, Ambika; Cheng, Chu; Martinez, Jose A; Ng, Hilarie; de la Hoz, Cristiane; Zochodne, Douglas W

    2017-03-01

    Unique deficits in the function of adult sensory neurons as part of their early neurodegeneration might account for progressive polyneuropathy during chronic diabetes mellitus. Here, we provide structural and functional evidence for aberrant pre-mRNA splicing in a chronic type 1 model of experimental diabetic polyneuropathy (DPN). Cajal bodies (CBs), unique nuclear substructures involved in RNA splicing, increased in number in diabetic sensory neurons, but their expected colocalization with survival motor neuron (SMN) proteins was reduced - a mislocalization described in motor neurons of spinal muscular atrophy. Small nuclear ribonucleoprotein particles (snRNPs), also participants in the spliceosome, had abnormal multiple nuclear foci unassociated with CBs, and their associated snRNAs were reduced. CWC22, a key spliceosome protein, was aberrantly upregulated in diabetic dorsal root ganglia (DRG), and impaired neuronal function. CWC22 attenuated sensory neuron plasticity, with knockdown in vitro enhancing their neurite outgrowth. Further, axonal delivery of CWC22 siRNA unilaterally to locally knock down the aberrant protein in diabetic nerves improved aspects of sensory function in diabetic mice. Collectively, our findings identify subtle but significant alterations in spliceosome structure and function, including dysregulated CBs and CWC22 overexpression, in diabetic sensory neurons that offer new ideas regarding diabetic sensory neurodegeneration in polyneuropathy.

  8. Faunal Drivers of Soil Flux Dynamics via Alterations in Crack Structure

    NASA Astrophysics Data System (ADS)

    DeCarlo, Keita; Caylor, Kelly

    2016-04-01

    Organismal activity, in addition to its role in ecological feedbacks, has the potential to serve as instigators or enhancers of atmospheric and hydrologic processes via alterations in soil structural regimes. We investigated the biomechanical effect of faunal activity on soil carbon dynamics via changes in soil crack structure, focusing on three dryland soil systems: bioturbated, biocompacted and undisturbed soils. Carbon fluxes were characterized using a closed-system respiration chamber, with CO2 concentration differences measured using an infrared gas analyzer (IRGA). Results show that faunal influences play a divergent biomechanics role in bulk soil cracking: bioturbation induced by belowground fauna creates "surficial" (shallow, large, well-connected) networks relative to the "systematic" (deep, moderate, poorly connected) networks created by aboveground fauna. The latter also shows a "memory" of past wetting/drying events in the consolidated soil through a crack layering effect. These morphologies further drive differences in soil carbon flux: under dry conditions, bioturbated and control soils show a persistently high and low mean carbon flux, respectively, while biocompacted soils show a large diurnal trend, with daytime lows and nighttime highs comparable to the control and bioturbated soils, respectively. Overall fluxes under wet conditions are considerably higher, but also more variable, though higher mean fluxes are observed in the biocompacted and bioturbated soils. Our results suggest that the increased surface area in the bioturbated soils create enhanced but constant diffusive processes, whereas the increased thermal gradient in the biocompacted soils create novel convective processes that create high fluxes that are diurnal in nature.

  9. Dietary cholesterol alters memory and synaptic structural plasticity in young rat brain.

    PubMed

    Ya, Bai-liu; Liu, Wen-yan; Ge, Feng; Zhang, Yan-xia; Zhu, Bao-liang; Bai, Bo

    2013-08-01

    Cholesterol plays an important role in synaptic plasticity, learning and memory. To better explore how dietary cholesterol contributes to learning and memory and the related changes in synaptic structural plasticity, rats were categorized into a regular diet (RD) group and a cholesterol-enriched diet (CD) group, and were fed with respective diet for 2 months. Dietary cholesterol impacts on learning and memory, hippocampal synaptic ultrastructure, expression levels of postsynaptic density-95 (PSD-95), synaptophysin (SYP) and cannabinoid receptor type 1 (CB1R) were investigated. We found CD rats had better performances in learning and memory using Morris water maze and object recognition test than RD rats. The memory improvement was accompanied with alterations of synaptic ultrastructure in the CA1 area of the hippocampus evaluated by electron microscopy, enhanced immunoreactivity of SYP, a presynaptic marker in hippocampus detected by immunocytochemistry, as well as increased levels of PSD-95, SYP and decreased level of CB1R in brains of CD rats determined by Western blot. Taken together, the results suggest that the improvement of learning and memory abilities of the young adult rats induced by dietary cholesterol may be linked with changes in synaptic structural plasticity in the brain.

  10. Exposure of soil microbial communities to chromium and arsenic alters their diversity and structure.

    PubMed

    Sheik, Cody S; Mitchell, Tyler W; Rizvi, Fariha Z; Rehman, Yasir; Faisal, Muhammad; Hasnain, Shahida; McInerney, Michael J; Krumholz, Lee R

    2012-01-01

    Extensive use of chromium (Cr) and arsenic (As) based preservatives from the leather tanning industry in Pakistan has had a deleterious effect on the soils surrounding production facilities. Bacteria have been shown to be an active component in the geochemical cycling of both Cr and As, but it is unknown how these compounds affect microbial community composition or the prevalence and form of metal resistance. Therefore, we sought to understand the effects that long-term exposure to As and Cr had on the diversity and structure of soil microbial communities. Soils from three spatially isolated tanning facilities in the Punjab province of Pakistan were analyzed. The structure, diversity and abundance of microbial 16S rRNA genes were highly influenced by the concentration and presence of hexavalent chromium (Cr (VI)) and arsenic. When compared to control soils, contaminated soils were dominated by Proteobacteria while Actinobacteria and Acidobacteria (which are generally abundant in pristine soils) were minor components of the bacterial community. Shifts in community composition were significant and revealed that Cr (VI)-containing soils were more similar to each other than to As contaminated soils lacking Cr (VI). Diversity of the arsenic resistance genes, arsB and ACR3 were also determined. Results showed that ACR3 becomes less diverse as arsenic concentrations increase with a single OTU dominating at the highest concentration. Chronic exposure to either Cr or As not only alters the composition of the soil bacterial community in general, but affects the arsenic resistant individuals in different ways.

  11. Structural Analysis of Alterations in Zebrafish Muscle Differentiation Induced by Simvastatin and Their Recovery with Cholesterol

    PubMed Central

    Campos, Laise M.; Rios, Eduardo A.; Midlej, Victor; Atella, Georgia C.; Herculano-Houzel, Suzana; Benchimol, Marlene; Mermelstein, Claudia; Costa, Manoel Luís

    2015-01-01

    In vitro studies show that cholesterol is essential to myogenesis. We have been using zebrafish to overcome the limitations of the in vitro approach and to study the sub-cellular structures and processes involved during myogenesis. We use simvastatin—a drug widely used to prevent high levels of cholesterol and cardiovascular disease—during zebrafish skeletal muscle formation. Simvastatin is an efficient inhibitor of cholesterol synthesis that has various myotoxic consequences. Here, we employed simvastatin concentrations that cause either mild or severe morphological disturbances to observe changes in the cytoskeleton (intermediate filaments and microfilaments), extracellular matrix and adhesion markers by confocal microscopy. With low-dose simvastatin treatment, laminin was almost normal, and alpha-actinin was reduced in the myofibrils. With high simvastatin doses, laminin and vinculin were reduced and appeared discontinuous along the septa, with almost no myofibrils, and small amounts of desmin accumulating close to the septa. We also analyzed sub-cellular alterations in the embryos by electron microscopy, and demonstrate changes in embryo and somite size, septa shape, and in myofibril structure. These effects could be reversed by the addition of exogenous cholesterol. These results contribute to the understanding of the mechanisms of action of simvastatin in muscle cells in particular, and in the study of myogenesis in general. PMID:25786435

  12. Altered sperm chromatin structure in mice exposed to sodium fluoride through drinking water.

    PubMed

    Sun, Zilong; Niu, Ruiyan; Wang, Bin; Wang, Jundong

    2014-06-01

    This study investigated the effects of sodium fluoride (NaF) on sperm abnormality, sperm chromatin structure, protamine 1 and protamine 2 (P1 and P2) mRNA expression, and histones expression in sperm in male mice. NaF was orally administrated to male mice at 30, 70, and 150 mg/l for 49 days (more than one spermatogenic cycle). Sperm head and tail abnormalities were significantly enhanced at middle and high doses. Similarly, sperm chromatin structure was also adversely affected by NaF exposure, indicating DNA integrity damage. Furthermore, middle and high NaF significantly reduced the mRNA expressions of P1 and P2, and P1/P2 ratio, whereas the sperm histones level was increased, suggesting the abnormal histone-protamine replacement. Therefore, we concluded that the mechanism by which F induced mice sperm abnormality and DNA integrity damage may involved in the alterations in P1, P2, and histones expression in sperm of mice.

  13. Structural and Ultrastructural Alterations in Human Olfactory Pathways and Possible Associations with Herpesvirus 6 Infection

    PubMed Central

    Skuja, Sandra; Zieda, Anete; Ravina, Kristine; Chapenko, Svetlana; Roga, Silvija; Teteris, Ojars; Groma, Valerija; Murovska, Modra

    2017-01-01

    Structural and ultrastructural alterations in human olfactory pathways and putative associations with human herpesvirus 6 (HHV-6) infection were studied. The olfactory bulb/tract samples from 20 subjects with an unspecified encephalopathy determined by pathomorphological examination of the brain autopsy, 17 healthy age-matched and 16 younger controls were used. HHV-6 DNA was detected in 60, 29, and 19% of cases in these groups, respectively. In the whole encephalopathy group, significantly more HHV-6 positive neurons and oligodendrocytes were found in the gray matter, whereas, significantly more HHV-6 positive astrocytes, oligodendrocytes, microglia/macrophages and endothelial cells were found in the white matter. Additionally, significantly more HHV-6 positive astrocytes and, in particular, oligodendrocytes were found in the white matter when compared to the gray matter. Furthermore, when only HHV-6 PCR+ encephalopathy cases were studied, we observed similar but stronger associations between HHV-6 positive oligodendrocytes and CD68 positive cells in the white matter. Cellular alterations were additionally evidenced by anti-S100 immunostaining, demonstrating a significantly higher number of S100 positive cells in the gray matter of the whole encephalopathy group when compared to the young controls, and in the white matter when compared to both control groups. In spite the decreased S100 expression in the PCR+ encephalopathy group when compared to PCR- cases and controls, groups demonstrated significantly higher number of S100 positive cells in the white compared to the gray matter. Ultrastructural changes confirming the damage of myelin included irregularity of membranes and ballooning of paranodal loops. This study shows that among the cellular targets of the nervous system, HHV-6 most severely affects oligodendrocytes and the myelin made by them. PMID:28072884

  14. Dracaena arborea alleviates ultra-structural spermatogenic alterations in streptozotocin-induced diabetic rats

    PubMed Central

    2013-01-01

    Background Infertility is a common complication in diabetic men and experimental animals, mainly due to loss of germ cells by apoptotic cell death. The aim of this study was to evaluate the effects of aqueous and ethanol extracts of Dracaena arborea in streptozotocin-induced ultra-structural spermatogenic alterations in Wistar rats. Methods Diabetic animals were orally treated with Millipore water (10 ml/kg), sildenafil citrate (1.44 mg/kg) or Dracaena arborea aqueous (500 mg/kg) and ethanol (100 mg/kg) extracts for three weeks. A group of non diabetic rats received Millipore water (10 ml/kg) and served as healthy control group. Blood glucose was monitored at the beginning and the end of the study. One day after the last treatment, animals were sacrificed and the testes immediately removed were morphologically observed and prepared for electron microscopy analysis of spermatogenesis. Results Our results showed that Dracaena arborea was devoid of any anti-hyperglycemic activity. In the untreated diabetic rats, hyperglycemia severely damaged the testes morphology as well as the spermatogenic process as evidenced by the: thickness of basement membrane of the seminiferous tubule; mitochondria alteration; abnormal spermatocyte cells displaying polymorphous nuclei, cytoplasmic vacuolization and necrosis; and disorganization and degeneration of sperm germ cells. Administration of sildenafil citrate and Dracaena arborea extracts to the diabetic rats improved testes morphology and reversed, although not completely, the impairment of spermatogenesis; this alleviating effect was more pronounced in animals treated with the aqueous extract (500 mg/kg) of Dracaena arborea. Conclusion Dracaena arborea improves testes morphology and restores spermatogenesis in type 1 diabetic rats, without having major anti-hyperglycemic properties. These effects could be attributed to saponins, flavonoids, phenols and sterols revealed in this plant, which could be a useful component

  15. Increasing the Size of the Microbial Biomass Altered Bacterial Community Structure which Enhances Plant Phosphorus Uptake

    PubMed Central

    Shen, Pu; Murphy, Daniel Vaughan; George, Suman J.; Lapis-Gaza, Hazel; Xu, Minggang

    2016-01-01

    Agricultural production can be limited by low phosphorus (P) availability, with soil P being constrained by sorption and precipitation reactions making it less available for plant uptake. There are strong links between carbon (C) and nitrogen (N) availability and P cycling within soil P pools, with microorganisms being an integral component of soil P cycling mediating the availability of P to plants. Here we tested a conceptual model that proposes (i) the addition of readily-available organic substrates would increase the size of the microbial biomass thus exhausting the pool of easily-available P and (ii) this would cause the microbial biomass to access P from more recalcitrant pools. In this model it is hypothesised that the size of the microbial population is regulating access to less available P rather than the diversity of organisms contained within this biomass. To test this hypothesis we added mixtures of simple organic compounds that reflect typical root exudates at different C:N ratios to a soil microcosm experiment and assessed changes in soil P pools, microbial biomass and bacterial diversity measures. We report that low C:N ratio (C:N = 12.5:1) artificial root exudates increased the size of the microbial biomass while high C:N ratio (C:N = 50:1) artificial root exudates did not result in a similar increase in microbial biomass. Interestingly, addition of the root exudates did not alter bacterial diversity (measured via univariate diversity indices) but did alter bacterial community structure. Where C, N and P supply was sufficient to support plant growth the increase observed in microbial biomass occurred with a concurrent increase in plant yield. PMID:27893833

  16. Modeling Coniferous Canopy Structure over Extensive Areas for Ray Tracing Simulations: Scaling from the Leaf to the Stand Level

    NASA Astrophysics Data System (ADS)

    van Aardt, J. A.; van Leeuwen, M.; Kelbe, D.; Kampe, T.; Krause, K.

    2015-12-01

    Remote sensing is widely accepted as a useful technology for characterizing the Earth surface in an objective, reproducible, and economically feasible manner. To date, the calibration and validation of remote sensing data sets and biophysical parameter estimates remain challenging due to the requirements to sample large areas for ground-truth data collection, and restrictions to sample these data within narrow temporal windows centered around flight campaigns or satellite overpasses. The computer graphics community have taken significant steps to ameliorate some of these challenges by providing an ability to generate synthetic images based on geometrically and optically realistic representations of complex targets and imaging instruments. These synthetic data can be used for conceptual and diagnostic tests of instrumentation prior to sensor deployment or to examine linkages between biophysical characteristics of the Earth surface and at-sensor radiance. In the last two decades, the use of image generation techniques for remote sensing of the vegetated environment has evolved from the simulation of simple homogeneous, hypothetical vegetation canopies, to advanced scenes and renderings with a high degree of photo-realism. Reported virtual scenes comprise up to 100M surface facets; however, due to the tighter coupling between hardware and software development, the full potential of image generation techniques for forestry applications yet remains to be fully explored. In this presentation, we examine the potential computer graphics techniques have for the analysis of forest structure-function relationships and demonstrate techniques that provide for the modeling of extremely high-faceted virtual forest canopies, comprising billions of scene elements. We demonstrate the use of ray tracing simulations for the analysis of gap size distributions and characterization of foliage clumping within spatial footprints that allow for a tight matching between characteristics

  17. Multimodal neuroimaging evidence of alterations in cortical structure and function in HIV-infected older adults

    PubMed Central

    Wilson, Tony W.; Heinrichs-Graham, Elizabeth; Becker, Katherine M.; Aloi, Joey; Robertson, Kevin R.; Sandkovsky, Uriel; White, Matthew L.; O’Neill, Jennifer; Knott, Nichole L.; Fox, Howard S.; Swindells, Susan

    2015-01-01

    Combination antiretroviral therapy transformed HIV-infection from a terminal illness to a manageable condition, but these patients remain at a significantly elevated risk of developing cognitive impairments and the mechanisms are not understood. Some previous neuroimaging studies have found hyperactivation in fronto-parietal networks of HIV-infected patients, whereas others reported aberrations restricted to sensory cortices. In this study, we utilize high-resolution structural and neurophysiological imaging to determine whether alterations in brain structure, function, or both contribute to HIV-related cognitive impairments. HIV-infected adults and individually-matched controls completed 3-Tesla structural magnetic-resonance imaging (sMRI) and a mechanoreception task during magnetoencephalography (MEG). MEG data was examined using advanced beamforming methods, and sMRI data was analyzed using the latest voxel-based morphometry methods with DARTEL. We found significantly reduced theta responses in the postcentral gyrus and increased alpha activity in the prefrontal cortices of HIV-infected patients compared with controls. Patients also had reduced gray matter volume in the postcentral gyrus, parahippocampal gyrus, and other regions. Importantly, reduced gray matter volume in the left postcentral gyrus was spatially-coincident with abnormal MEG responses in HIV-infected patients. Finally, left prefrontal and postcentral gyrus activity was correlated with neuropsychological performance and, when used in conjunction, these two MEG findings had a sensitivity and specificity of over 87.5% for HIV-associated cognitive impairment. This study is the first to demonstrate abnormally increased activity in association cortices with simultaneously decreased activity in sensory areas. These MEG findings had excellent sensitivity and specificity for HIV-associated cognitive impairment, and may hold promise as a potential disease marker. PMID:25376125

  18. PERSPECTIVE VIEW LOOKING NORTHEAST AT THE TEST STAND, NOTE THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PERSPECTIVE VIEW LOOKING NORTHEAST AT THE TEST STAND, NOTE THE SERVICE AND SUPPORT BUILDINGS TO THE LEFT AND RIGHT OF THE TEST STAND. - Marshall Space Flight Center, Saturn Propulsion & Structural Test Facility, East Test Area, Huntsville, Madison County, AL

  19. Alterations in nuclear structure promote lupus autoimmunity in a mouse model

    PubMed Central

    Singh, Namrata; Johnstone, Duncan B.; Martin, Kayla A.; Tempera, Italo; Kaplan, Mariana J.

    2016-01-01

    ABSTRACT Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by the development of autoantibodies that recognize components of the cell nucleus. The vast majority of lupus research has focused on either the contributions of immune cell dysfunction or the genetics of the disease. Because granulocytes isolated from human SLE patients had alterations in neutrophil nuclear morphology that resembled the Pelger–Huet anomaly, and had prominent mis-splicing of mRNA encoding the nuclear membrane protein lamin B receptor (LBR), consistent with their Pelger–Huet-like nuclear morphology, we used a novel mouse model system to test the hypothesis that a disruption in the structure of the nucleus itself also contributes to the development of lupus autoimmunity. The lupus-prone mouse strain New Zealand White (NZW) was crossed with c57Bl/6 mice harboring a heterozygous autosomal dominant mutation in Lbr (B6.Lbric/+), and the (NZW×B6.Lbric)F1 offspring were evaluated for induction of lupus autoimmunity. Only female (NZW×B6.Lbric)F1 mice developed lupus autoimmunity, which included splenomegaly, kidney damage and autoantibodies. Kidney damage was accompanied by immune complex deposition, and perivascular and tubule infiltration of mononuclear cells. The titers of anti-chromatin antibodies exceeded those of aged female MRL-Faslpr mice, and were predominantly of the IgG2 subclasses. The anti-nuclear antibody staining profile of female (NZW×B6.Lbric)F1 sera was complex, and consisted of an anti-nuclear membrane reactivity that colocalized with the A-type lamina, in combination with a homogeneous pattern that was related to the recognition of histones with covalent modifications that are associated with gene activation. An anti-neutrophil IgM recognizing calreticulin, but not myeloperoxidase (MPO) or proteinase 3 (PR3), was also identified. Thus, alterations in nuclear structure contribute to lupus autoimmunity when expressed in the context of a lupus

  20. Alterations in nuclear structure promote lupus autoimmunity in a mouse model.

    PubMed

    Singh, Namrata; Johnstone, Duncan B; Martin, Kayla A; Tempera, Italo; Kaplan, Mariana J; Denny, Michael F

    2016-08-01

    Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by the development of autoantibodies that recognize components of the cell nucleus. The vast majority of lupus research has focused on either the contributions of immune cell dysfunction or the genetics of the disease. Because granulocytes isolated from human SLE patients had alterations in neutrophil nuclear morphology that resembled the Pelger-Huet anomaly, and had prominent mis-splicing of mRNA encoding the nuclear membrane protein lamin B receptor (LBR), consistent with their Pelger-Huet-like nuclear morphology, we used a novel mouse model system to test the hypothesis that a disruption in the structure of the nucleus itself also contributes to the development of lupus autoimmunity. The lupus-prone mouse strain New Zealand White (NZW) was crossed with c57Bl/6 mice harboring a heterozygous autosomal dominant mutation in Lbr (B6.Lbr(ic/+)), and the (NZW×B6.Lbr(ic))F1 offspring were evaluated for induction of lupus autoimmunity. Only female (NZW×B6.Lbr(ic))F1 mice developed lupus autoimmunity, which included splenomegaly, kidney damage and autoantibodies. Kidney damage was accompanied by immune complex deposition, and perivascular and tubule infiltration of mononuclear cells. The titers of anti-chromatin antibodies exceeded those of aged female MRL-Fas(lpr) mice, and were predominantly of the IgG2 subclasses. The anti-nuclear antibody staining profile of female (NZW×B6.Lbr(ic))F1 sera was complex, and consisted of an anti-nuclear membrane reactivity that colocalized with the A-type lamina, in combination with a homogeneous pattern that was related to the recognition of histones with covalent modifications that are associated with gene activation. An anti-neutrophil IgM recognizing calreticulin, but not myeloperoxidase (MPO) or proteinase 3 (PR3), was also identified. Thus, alterations in nuclear structure contribute to lupus autoimmunity when expressed in the context of a lupus

  1. Invasive symbiont bearing (and other) foraminifera altering the community structure of eastern Mediterranean rocky reefs environments

    NASA Astrophysics Data System (ADS)

    Hyams-Kaphzan, Orit; Perelis Grossowicz, Lydia; Almogi-Labin, Ahuva

    2015-04-01

    The rocky reefs of the Israeli eastern Mediterranean shelf constitute a highly diverse marine ecosystem rich in macroalgae and calcareous organisms. The benthic foraminiferal community living in this ecosystem is rapidly changing due to massive invasion of symbiont bearing foraminifera (SBF) as well as other foraminiferal species of tropical origin. This trend facilitated by the ongoing increase in temperature enables more tropical species to adjust to the eastern Mediterranean habitats. In order to document the status of the benthic foraminiferal community structure rocky reefs at Akhziv (AK) and Carmel Head (CH), northern Israel were sampled by scuba diving. Different macroalgae species, including invasive ones, accommodating the live epiphytic benthic foraminifera were sampled twice a year at AK and in each season at CH in three depth intervals between 5-20 m, during 2013-4. The numerical abundance of the group ranges between 170-3500 #/10cc (wet macroalgae volume) without any significant difference in standing stocks within regions, water depths or macroalgae preference. In total 77 benthic foraminiferal species were identified 71 in CH and only 43 at AK. Species richness per site varied between 3 and 42 with higher values at CH. 25% of all species were aliens, mostly Lessepsian, that comprise on average 70% - 84% of the numerical abundance of AK and CH respectively. Cluster analysis using benthic foraminifera relative abundance data did not correlate with the different macroalgae species, water depths or seasonality, indicating that the foraminiferal community in the two regions is quite homogenous. Amphistegina lobifera a Lessepsian migrant is by far the most common species on the Israeli rocky reefs occurring in all samples and comprising 18-93% of the foraminiferal community. Heterostegina depressa behaves similarly to A. lobifera though it occurs in lower numbers. Pararotalia calcariformata, a recently arriving SBF occupies mainly shallow water sites at CH

  2. Momentum-resolved electronic structure at a buried interface from soft X-ray standing-wave angle-resolved photoemission

    NASA Astrophysics Data System (ADS)

    Gray, A. X.; Minár, J.; Plucinski, L.; Huijben, M.; Bostwick, A.; Rotenberg, E.; Yang, S.-H.; Braun, J.; Winkelmann, A.; Conti, G.; Eiteneer, D.; Rattanachata, A.; Greer, A. A.; Ciston, J.; Ophus, C.; Rijnders, G.; Blank, D. H. A.; Doennig, D.; Pentcheva, R.; Kortright, J. B.; Schneider, C. M.; Ebert, H.; Fadley, C. S.

    2013-10-01

    Angle-resolved photoemission spectroscopy (ARPES) is a powerful technique for the study of electronic structure, but it lacks a direct ability to study buried interfaces between two materials. We address this limitation by combining ARPES with soft X-ray standing-wave (SW) excitation (SWARPES), in which the SW profile is scanned through the depth of the sample. We have studied the buried interface in a prototypical magnetic tunnel junction La0.7Sr0.3MnO3/SrTiO3. Depth-and momentum-resolved maps of Mn 3d eg and t2g states from the central, bulk-like and interface-like regions of La0.7Sr0.3MnO3 exhibit distinctly different behavior consistent with a change in the Mn bonding at the interface. We compare the experimental results to state-of-the-art density-functional and one-step photoemission theory, with encouraging agreement that suggests wide future applications of this technique.

  3. Saw gin stands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The saw gin stand is the heart of the saw ginning system. Almost from the initial filing of patents for the spiked tooth gin and the saw gin in 1794 and 1796 by Whitney and then Holmes respectively (Hughs and Holt, 2015), the saw gin stand has predominated over early roller-type gins in the U.S. co...

  4. Planter unit test stand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A planter test stand was developed to evaluate individual row-crop metering units in early 2013. This test stand provided the ability to quantify actual seed metering in terms of population, seed spacing, skips, and multiples over a range of meter RPMs and vacuum pressures. Preliminary data has been...

  5. Hypoxia reduces the efficiency of elisidepsin by inhibiting hydroxylation and altering the structure of lipid rafts.

    PubMed

    Király, Anna; Váradi, Tímea; Hajdu, Tímea; Rühl, Ralph; Galmarini, Carlos M; Szöllősi, János; Nagy, Peter

    2013-12-02

    The mechanism of action of elisidepsin (PM02734, Irvalec®) is assumed to involve membrane permeabilization via attacking lipid rafts and hydroxylated lipids. Here we investigate the role of hypoxia in the mechanism of action of elisidepsin. Culturing under hypoxic conditions increased the half-maximal inhibitory concentration and decreased the drug's binding to almost all cell lines which was reversed by incubation of cells with 2-hydroxy palmitic acid. The expression of fatty acid 2-hydroxylase was strongly correlated with the efficiency of the drug and inversely correlated with the effect of hypoxia. Number and brightness analysis and fluorescence anisotropy experiments showed that hypoxia decreased the clustering of lipid rafts and altered the structure of the plasma membrane. Although the binding of elisidepsin to the membrane is non-cooperative, its membrane permeabilizing effect is characterized by a Hill coefficient of ~3.3. The latter finding is in agreement with elisidepsin-induced clusters of lipid raft-anchored GFP visualized by confocal microscopy. We propose that the concentration of elisidepsin needs to reach a critical level in the membrane above which elisidepsin induces the disruption of the cell membrane. Testing for tumor hypoxia or the density of hydroxylated lipids could be an interesting strategy to increase the efficiency of elisidepsin.

  6. Altered Brain Function, Structure, and Developmental Trajectory in Children Born Late Preterm

    PubMed Central

    Brumbaugh, Jane E.; Conrad, Amy L.; Lee, Jessica K.; DeVolder, Ian J.; Zimmerman, M. Bridget; Magnotta, Vincent A.; Axelson, Eric D.; Nopoulos, Peggy C.

    2016-01-01

    Background Late preterm birth (34-36 weeks’ gestation) is a common occurrence with potential for altered brain development. Methods This observational cohort study compared children at age 6-13 years based on the presence or absence of the historical risk factor of late preterm birth. Children completed a battery of cognitive assessments and underwent magnetic resonance imaging of the brain. Results Late preterm children (n=52) demonstrated slower processing speed (p=0.035) and scored more poorly in visual-spatial perception (p=0.032) and memory (p=0.007) than full term children (n=74). Parents of late preterm children reported more behavioral difficulty (p=0.004). There were no group differences in cognitive ability or academic achievement. Imaging revealed similar intracranial volumes but less total tissue and more cerebrospinal fluid (p=0.004) for late preterm children compared to full term children. The tissue difference was driven by differences in the cerebrum (p=0.028) and distributed across cortical (p=0.051) and subcortical tissue (p=0.047). Late preterm children had a relatively smaller thalamus (p=0.012) than full term children. Only full term children demonstrated significant decreases in cortical tissue volume (p<0.001) and thickness (p<0.001) with age. Conclusion Late preterm birth may affect cognition, behavior, and brain structure well beyond infancy. PMID:27064239

  7. Val66Met Polymorphism of BDNF Alters Prodomain Structure to Induce Neuronal Growth Cone Retraction

    PubMed Central

    Anastasia, Agustin; Deinhardt, Katrin; Chao, Moses V.; Will, Nathan E.; Irmady, Krithi; Lee, Francis S.; Hempstead, Barbara L.; Bracken, Clay

    2013-01-01

    A common single-nucleotide polymorphism in the human brain-derived neurotrophic factor (BDNF) gene results in a Val66Met substitution in the BDNF prodomain region. This single-nucleotide polymorphism is associated with alterations in memory and with enhanced risk to develop depression and anxiety disorders in humans. Here we show that the isolated BDNF prodomain is detected in the hippocampus and that it can be secreted from neurons in an activity-dependent manner. Using nuclear magnetic resonance spectroscopy and circular dichroism we find that the prodomain is intrinsically disordered, and the Val66Met substitution induces structural changes. Surprisingly, application of Met66 (but not Val66) BDNF prodomain induces acute growth cone retraction and a decrease in Rac activity in hippocampal neurons. Expression of p75NTR and differential engagement of the Met66 prodomain to the SorCS2 receptor are required for this effect. These results identify the Met66 prodomain as a new active ligand which modulates neuronal morphology. PMID:24048383

  8. Structural Alterations of the Social Brain: A Comparison between Schizophrenia and Autism

    PubMed Central

    Radeloff, Daniel; Ciaramidaro, Angela; Siniatchkin, Michael; Hainz, Daniela; Schlitt, Sabine; Weber, Bernhard; Poustka, Fritz; Bölte, Sven; Walter, Henrik; Freitag, Christine Margarete

    2014-01-01

    Autism spectrum disorder and schizophrenia share a substantial number of etiologic and phenotypic characteristics. Still, no direct comparison of both disorders has been performed to identify differences and commonalities in brain structure. In this voxel based morphometry study, 34 patients with autism spectrum disorder, 21 patients with schizophrenia and 26 typically developed control subjects were included to identify global and regional brain volume alterations. No global gray matter or white matter differences were found between groups. In regional data, patients with autism spectrum disorder compared to typically developed control subjects showed smaller gray matter volume in the amygdala, insula, and anterior medial prefrontal cortex. Compared to patients with schizophrenia, patients with autism spectrum disorder displayed smaller gray matter volume in the left insula. Disorder specific positive correlations were found between mentalizing ability and left amygdala volume in autism spectrum disorder, and hallucinatory behavior and insula volume in schizophrenia. Results suggest the involvement of social brain areas in both disorders. Further studies are needed to replicate these findings and to quantify the amount of distinct and overlapping neural correlates in autism spectrum disorder and schizophrenia. PMID:25188200

  9. Platelet factor 4 (CXCL4) seals blood clots by altering the structure of fibrin.

    PubMed

    Amelot, Aymeric A; Tagzirt, Madjid; Ducouret, Guylaine; Kuen, René Lai; Le Bonniec, Bernard F

    2007-01-05

    Platelet factor-4 (PF4/CXCL4) is an orphan chemokine released in large quantities in the vicinity of growing blood clots. Coagulation of plasma supplemented with a matching amount of PF4 results in a translucent jelly-like clot. Saturating amounts of PF4 reduce the porosity of the fibrin network 4.4-fold and decrease the values of the elastic and loss moduli by 31- and 59-fold, respectively. PF4 alters neither the cleavage of fibrinogen by thrombin nor the cross-linking of protofibrils by activated factor XIII but binds to fibrin and dramatically transforms the structure of the ensuing network. Scanning electron microscopy showed that PF4 gives rise to a previously unreported pattern of polymerization where fibrin assembles to form a sealed network. The subunits constituting PF4 form a tetrahedron having at its corners a RPRH motif that mimics (in reverse orientation) the Gly-His-Arg-Pro-amide peptides that co-crystallize with fibrin. Molecular modeling showed that PF4 could be docked to fibrin with remarkable complementarities and absence of steric clashes, allowing the assembly of irregular polymers. Consistent with this hypothesis, as little as 50 microm the QVRPRHIT peptide derived from PF4 affects the polymerization of fibrin.

  10. FINE STRUCTURAL ALTERATIONS OF INTERPHASE NUCLEI OF LYMPHOCYTES STIMULATED TO GROWTH ACTIVITY IN VITRO

    PubMed Central

    Tokuyasu, K.; Madden, S. C.; Zeldis, L. J.

    1968-01-01

    This report describes fine structural changes of interphase nuclei of human peripheral blood lymphocytes stimulated to growth by short-term culture with phytohemagglutinin. Chromatin is found highly labile, its changes accompanying the sequential increases of RNA and DNA synthesis which are known to occur in lymphocyte cultures. In "resting" lymphocytes, abundant condensed chromatin appears as a network of large and small aggregates. Early in the response to phytohemagglutinin, small aggregates disappear during increase of diffuse chromatin regions. Small aggregates soon reappear, probably resulting from disaggregation of large masses of condensed chromatin. Loosened and highly dispersed forms then appear prior to the formation of prophase chromosomes. The loosened state is found by radioautography to be most active in DNA synthesis. Small nucleoli of resting lymphocytes have concentric agranular, fibrillar, and granular zones with small amounts of intranucleolar chromatin. Enlarging interphase nucleoli change chiefly (1) by increase in amount of intranucleolar chromatin and alteration of its state of aggregation and (2) by increase in granular components in close association with fibrillar components. PMID:5699935

  11. Structural and functional alteration of blood vessels caused by cigarette smoking: an overview of molecular mechanisms.

    PubMed

    Rahman, Mohammad M; Laher, Ismail

    2007-10-01

    Smoking is a significant independent risk factor for cardiovascular disease and is a leading cause of structural and functional alterations of the cardiovascular system. Most clinical and experimental investigations of the pathophysiology of cigarette smoking have studied the effects of smoke as a whole, while a few studies focused on specific components of cigarette smoke, e.g. nicotine and carbon monoxide, which are only 2 of the more than 4,000 different chemicals present in cigarette smoke. The findings point to some discrepancies when the effects of whole smoke are compared to nicotine alone, while there is almost uniform agreement that both active and passive smoking have detrimental effects on the cardiovascular system, although a milder effect was suggested for the latter. This review focuses on findings from clinical and experimental studies on the vascular effects of active and passive cigarette smoking and nicotine exposure. The findings are discussed in terms of tissue (conduit vs. resistance arteries and veins), species, age, gender and dosage. Although the exact pathophysiology of cigarette smoking has not been unveiled, cigarette smoking causes injury to the vascular endothelium, produces superoxide anions, reduces production and bioavailability of nitric oxide (NO), increases production and release of endothelin, causes endothelial dysfunction, thrombosis, atherosclerosis, infarction, coronary artery disease (CAD), stroke and death.

  12. Angiogenesis in the intermediate lobe of the pituitary gland alters its structure and function.

    PubMed

    Tanaka, Shigeyasu; Nakakura, Takashi; Jansen, Eric J R; Unno, Keisuke; Okada, Reiko; Suzuki, Masakazu; Martens, Gerard J M; Kikuyama, Sakae

    2013-05-01

    The pars distalis (PD) and the pars intermedia (PI) have the same embryonic origin, but their morphological and functional characteristics diverge during development. The PD is highly vascularized, whereas the highly innervated PI is essentially non-vascularized. Based on our previous finding that vascular endothelial growth factor-A (VEGF-A) is involved in vascularization of the rat PD, attempt was made to generate transgenic Xenopus expressing VEGF-A specifically in the melanotrope cells of the PI as a model system for studying the significance of vascularization or avascularization for the functional differentiation of the pituitary. The PI of the transgenic frogs, examined after metamorphosis, were distinctly vascularized but poorly innervated. The experimentally induced vascularization in the PI resulted in a marked increase in tissue volume and a decrease in the expression of both alpha-melanophore-stimulating hormone (α-MSH) and prohormone convertase 2, a cleavage enzyme essential for generating α-MSH. The transgenic animals had low plasma α-MSH concentrations and displayed incomplete adaptation to a black background. To our knowledge, this is the first report indicating that experimentally induced angiogenesis in the PI may bring about functional as well as structural alterations in this tissue.

  13. Altered gray matter organization in children and adolescents with ADHD: a structural covariance connectome study

    PubMed Central

    Griffiths, K R; Grieve, S M; Kohn, M R; Clarke, S; Williams, L M; Korgaonkar, M S

    2016-01-01

    Although multiple studies have reported structural deficits in multiple brain regions in attention-deficit hyperactivity disorder (ADHD), we do not yet know if these deficits reflect a more systematic disruption to the anatomical organization of large-scale brain networks. Here we used a graph theoretical approach to quantify anatomical organization in children and adolescents with ADHD. We generated anatomical networks based on covariance of gray matter volumes from 92 regions across the brain in children and adolescents with ADHD (n=34) and age- and sex-matched healthy controls (n=28). Using graph theory, we computed metrics that characterize both the global organization of anatomical networks (interconnectivity (clustering), integration (path length) and balance of global integration and localized segregation (small-worldness)) and their local nodal measures (participation (degree) and interaction (betweenness) within a network). Relative to Controls, ADHD participants exhibited altered global organization reflected in more clustering or network segregation. Locally, nodal degree and betweenness were increased in the subcortical amygdalae in ADHD, but reduced in cortical nodes in the anterior cingulate, posterior cingulate, mid temporal pole and rolandic operculum. In ADHD, anatomical networks were disrupted and reflected an emphasis on subcortical local connections centered around the amygdala, at the expense of cortical organization. Brains of children and adolescents with ADHD may be anatomically configured to respond impulsively to the automatic significance of stimulus input without having the neural organization to regulate and inhibit these responses. These findings provide a novel addition to our current understanding of the ADHD connectome. PMID:27824356

  14. Exercise Challenge in Gulf War Illness Reveals Two Subgroups with Altered Brain Structure and Function

    PubMed Central

    Rayhan, Rakib U.; Stevens, Benson W.; Raksit, Megna P.; Ripple, Joshua A.; Timbol, Christian R.; Adewuyi, Oluwatoyin; VanMeter, John W.; Baraniuk, James N.

    2013-01-01

    Nearly 30% of the approximately 700,000 military personnel who served in Operation Desert Storm (1990–1991) have developed Gulf War Illness, a condition that presents with symptoms such as cognitive impairment, autonomic dysfunction, debilitating fatigue and chronic widespread pain that implicate the central nervous system. A hallmark complaint of subjects with Gulf War Illness is post-exertional malaise; defined as an exacerbation of symptoms following physical and/or mental effort. To study the causal relationship between exercise, the brain, and changes in symptoms, 28 Gulf War veterans and 10 controls completed an fMRI scan before and after two exercise stress tests to investigate serial changes in pain, autonomic function, and working memory. Exercise induced two clinical Gulf War Illness subgroups. One subgroup presented with orthostatic tachycardia (n = 10). This phenotype correlated with brainstem atrophy, baseline working memory compensation in the cerebellar vermis, and subsequent loss of compensation after exercise. The other subgroup developed exercise induced hyperalgesia (n = 18) that was associated with cortical atrophy and baseline working memory compensation in the basal ganglia. Alterations in cognition, brain structure, and symptoms were absent in controls. Our novel findings may provide an understanding of the relationship between the brain and post-exertional malaise in Gulf War Illness. PMID:23798990

  15. Altered Membrane Structure and Surface Potential in Homozygous Hemoglobin C Erythrocytes

    PubMed Central

    Tokumasu, Fuyuki; Nardone, Glenn A.; Ostera, Graciela R.; Fairhurst, Rick M.; Beaudry, Steven D.; Hayakawa, Eri; Dvorak, James A.

    2009-01-01

    Background Hemoglobin C differs from normal hemoglobin A by a glutamate-to-lysine substitution at position 6 of beta globin and is oxidatively unstable. Compared to homozygous AA erythrocytes, homozygous CC erythrocytes contain higher levels of membrane-associated hemichromes and more extensively clustered band 3 proteins. These findings suggest that CC erythrocytes have a different membrane matrix than AA erythrocytes. Methodology and Findings We found that AA and CC erythrocytes differ in their membrane lipid composition, and that a subset of CC erythrocytes expresses increased levels of externalized phosphatidylserine. Detergent membrane analyses for raft marker proteins indicated that CC erythrocyte membranes are more resistant to detergent solubilization. These data suggest that membrane raft organization is modified in CC erythrocytes. In addition, the average zeta potential (a measure of surface electrochemical potential) of CC erythrocytes was ≈2 mV lower than that of AA erythrocytes, indicating that substantial rearrangements occur in the membrane matrix of CC erythrocytes. We were able to recapitulate this low zeta potential phenotype in AA erythrocytes by treating them with NaNO2 to oxidize hemoglobin A molecules and increase levels of membrane-associated hemichromes. Conclusion Our data support the possibility that increased hemichrome deposition and altered lipid composition induce molecular rearrangements in CC erythrocyte membranes, resulting in a unique membrane structure. PMID:19503809

  16. Altered gray matter organization in children and adolescents with ADHD: a structural covariance connectome study.

    PubMed

    Griffiths, K R; Grieve, S M; Kohn, M R; Clarke, S; Williams, L M; Korgaonkar, M S

    2016-11-08

    Although multiple studies have reported structural deficits in multiple brain regions in attention-deficit hyperactivity disorder (ADHD), we do not yet know if these deficits reflect a more systematic disruption to the anatomical organization of large-scale brain networks. Here we used a graph theoretical approach to quantify anatomical organization in children and adolescents with ADHD. We generated anatomical networks based on covariance of gray matter volumes from 92 regions across the brain in children and adolescents with ADHD (n=34) and age- and sex-matched healthy controls (n=28). Using graph theory, we computed metrics that characterize both the global organization of anatomical networks (interconnectivity (clustering), integration (path length) and balance of global integration and localized segregation (small-worldness)) and their local nodal measures (participation (degree) and interaction (betweenness) within a network). Relative to Controls, ADHD participants exhibited altered global organization reflected in more clustering or network segregation. Locally, nodal degree and betweenness were increased in the subcortical amygdalae in ADHD, but reduced in cortical nodes in the anterior cingulate, posterior cingulate, mid temporal pole and rolandic operculum. In ADHD, anatomical networks were disrupted and reflected an emphasis on subcortical local connections centered around the amygdala, at the expense of cortical organization. Brains of children and adolescents with ADHD may be anatomically configured to respond impulsively to the automatic significance of stimulus input without having the neural organization to regulate and inhibit these responses. These findings provide a novel addition to our current understanding of the ADHD connectome.

  17. Exercise challenge in Gulf War Illness reveals two subgroups with altered brain structure and function.

    PubMed

    Rayhan, Rakib U; Stevens, Benson W; Raksit, Megna P; Ripple, Joshua A; Timbol, Christian R; Adewuyi, Oluwatoyin; VanMeter, John W; Baraniuk, James N

    2013-01-01

    Nearly 30% of the approximately 700,000 military personnel who served in Operation Desert Storm (1990-1991) have developed Gulf War Illness, a condition that presents with symptoms such as cognitive impairment, autonomic dysfunction, debilitating fatigue and chronic widespread pain that implicate the central nervous system. A hallmark complaint of subjects with Gulf War Illness is post-exertional malaise; defined as an exacerbation of symptoms following physical and/or mental effort. To study the causal relationship between exercise, the brain, and changes in symptoms, 28 Gulf War veterans and 10 controls completed an fMRI scan before and after two exercise stress tests to investigate serial changes in pain, autonomic function, and working memory. Exercise induced two clinical Gulf War Illness subgroups. One subgroup presented with orthostatic tachycardia (n = 10). This phenotype correlated with brainstem atrophy, baseline working memory compensation in the cerebellar vermis, and subsequent loss of compensation after exercise. The other subgroup developed exercise induced hyperalgesia (n = 18) that was associated with cortical atrophy and baseline working memory compensation in the basal ganglia. Alterations in cognition, brain structure, and symptoms were absent in controls. Our novel findings may provide an understanding of the relationship between the brain and post-exertional malaise in Gulf War Illness.

  18. Exposure of Soil Microbial Communities to Chromium and Arsenic Alters Their Diversity and Structure

    PubMed Central

    Rizvi, Fariha Z.; Rehman, Yasir; Faisal, Muhammad; Hasnain, Shahida; McInerney, Michael J.; Krumholz, Lee R.

    2012-01-01

    Extensive use of chromium (Cr) and arsenic (As) based preservatives from the leather tanning industry in Pakistan has had a deleterious effect on the soils surrounding production facilities. Bacteria have been shown to be an active component in the geochemical cycling of both Cr and As, but it is unknown how these compounds affect microbial community composition or the prevalence and form of metal resistance. Therefore, we sought to understand the effects that long-term exposure to As and Cr had on the diversity and structure of soil microbial communities. Soils from three spatially isolated tanning facilities in the Punjab province of Pakistan were analyzed. The structure, diversity and abundance of microbial 16S rRNA genes were highly influenced by the concentration and presence of hexavalent chromium (Cr (VI)) and arsenic. When compared to control soils, contaminated soils were dominated by Proteobacteria while Actinobacteria and Acidobacteria (which are generally abundant in pristine soils) were minor components of the bacterial community. Shifts in community composition were significant and revealed that Cr (VI)-containing soils were more similar to each other than to As contaminated soils lacking Cr (VI). Diversity of the arsenic resistance genes, arsB and ACR3 were also determined. Results showed that ACR3 becomes less diverse as arsenic concentrations increase with a single OTU dominating at the highest concentration. Chronic exposure to either Cr or As not only alters the composition of the soil bacterial community in general, but affects the arsenic resistant individuals in different ways. PMID:22768219

  19. The rat intervertebral disk degeneration pain model: relationships between biological and structural alterations and pain

    PubMed Central

    2011-01-01

    Introduction Degeneration of the interverterbral disk is as a cause of low-back pain is increasing. To gain insight into relationships between biological processes, structural alterations and behavioral pain, we created an animal model in rats. Methods Disk degeneration was induced by removal of the nucleus pulposus (NP) from the lumbar disks (L4/L5 and L5/L6) of Sprague Dawley rats using a 0.5-mm-diameter microsurgical drill. The degree of primary hyperalgesia was assessed by using an algometer to measure pain upon external pressure on injured lumbar disks. Biochemical and histological assessments and radiographs of injured disks were used for evaluation. We investigated therapeutic modulation of chronic pain by administering pharmaceutical drugs in this animal model. Results After removal of the NP, pressure hyperalgesia developed over the lower back. Nine weeks after surgery we observed damaged or degenerated disks with proteoglycan loss and narrowing of disk height. These biological and structural changes in disks were closely related to the sustained pain hyperalgesia. A high dose of morphine (6.7 mg/kg) resulted in effective pain relief. However, high doses of pregabalin (20 mg/kg), a drug that has been used for treatment of chronic neuropathic pain, as well as the anti-inflammatory drugs celecoxib (50 mg/kg; a selective inhibitor of cyclooxygenase 2 (COX-2)) and ketorolac (20 mg/kg; an inhibitor of COX-1 and COX-2), did not have significant antihyperalgesic effects in our disk injury animal model. Conclusions Although similarities in gene expression profiles suggest potential overlap in chronic pain pathways linked to disk injury or neuropathy, drug-testing results suggest that pain pathways linked to these two chronic pain conditions are mechanistically distinct. Our findings provide a foundation for future research on new therapeutic interventions that can lead to improvements in the treatment of patients with back pain due to disk degeneration. PMID

  20. CTP:phosphocholine cytidylyltransferase α (CCTα) and lamins alter nuclear membrane structure without affecting phosphatidylcholine synthesis.

    PubMed

    Gehrig, Karsten; Ridgway, Neale D

    2011-06-01

    CTP:phosphocholine cytidylyltransferase α (CCTα) is a nuclear enzyme that catalyzes the rate-limiting step in the CDP-choline pathway for phosphatidylcholine (PC) synthesis. Lipid activation of CCTα results in its translocation to the nuclear envelope and expansion of an intranuclear membrane network termed the nucleoplasmic reticulum (NR) by a mechanism involving membrane deformation. Nuclear lamins are also required for stability and proliferation of the NR, but whether this unique structure, or the nuclear lamina in general, is required for PC synthesis is not known. To examine this relationship, the nuclear lamina was depleted by RNAi or disrupted by expression of the Hutchinson-Gilford progeria syndrome (HGPS) mutant lamin A (progerin), and the effect on CCTα and choline metabolism was analyzed. siRNA-mediated silencing of lamin A/C or lamin B1 in CHO cells to diminish the NR had no effect on PC synthesis, while double knockdown non-specifically inhibited the pathway. Confirming this minor role in PC synthesis, only 10% of transiently overexpressed choline/ethanolamine phosphotransferase was detected in the NR. In CHO cells, CCTα was nucleoplasmic and co-localized with GFP-progerin in nuclear folds and invaginations; however, HGPS fibroblasts displayed an abnormal distribution of CCTα in the cytoplasm and nuclear envelope that was accompanied by a 2-fold reduction in PC synthesis. In spite of its altered localization, choline-labeling experiments showed that CCT activity was unaffected, and inhibition of PC synthesis was traced to reduced activity of a hemicholinium-sensitive choline transporter. We conclude that CCTα and lamins specifically cooperate to form the NR, but the overall structure of the nuclear envelope has a minimal impact on CCT activity and PC synthesis.

  1. Cysteamine depletes prolactin (PRL) but does not alter the structure of PRL-containing granules in the anterior pituitary

    SciTech Connect

    Weinstein, L.A.; Landis, D.M.; Sagar, S.M.; Millard, W.J.; Martin, J.B.

    1984-10-01

    Cysteamine causes a profound depletion of PRL in the anterior pituitary and in the systemic circulation, as measured by RIA and bioassay. However, electron microscopic study of PRL-containing cells in rat anterior pituitary does not reveal changes in secretory granule or cytoplasmic structure during the interval of depressed PRL content and of subsequent recovery to normal levels. In contrast to the results obtained by RIA, PRL-like immunoreactivity as detected by immunocyto-chemistry is present and similar to that of control preparations after cysteamine administration. We suggest that cysteamine alters PRL structure in secretory granules, probably by interacting with the disulfide bonds of PRL, thereby altering bioactivity and immunoreactivity. The presence of cysteamine-altered PRL in secretory granules does not seem to trigger degradation of granules by the lysosomal system.

  2. Timelapse: Webb's Ambient Optical Assembly Stand

    NASA Video Gallery

    The clean room at NASA's Goddard Space Flight Center in Greenbelt, Md., has received a giant structural steel frame called "AOAS," the Ambient Optical Assembly Stand that will be used to assemble t...

  3. Stress analysis of down force calibration stand

    SciTech Connect

    COVERDELL, B.L.

    1998-10-01

    This document presents the stress analysis of the Down Force Calibration Stand. All structural components were evaluated and found to be adequate to withstand the applicable design loads meeting all codes and standards requirements.

  4. The human liver fatty acid binding protein T94A variant alters the structure, stability, and interaction with fibrates.

    PubMed

    Martin, Gregory G; McIntosh, Avery L; Huang, Huan; Gupta, Shipra; Atshaves, Barbara P; Landrock, Kerstin K; Landrock, Danilo; Kier, Ann B; Schroeder, Friedhelm

    2013-12-23

    Although the human liver fatty acid binding protein (L-FABP) T94A variant arises from the most commonly occurring single-nucleotide polymorphism in the entire FABP family, there is a complete lack of understanding regarding the role of this polymorphism in human disease. It has been hypothesized that the T94A substitution results in the complete loss of ligand binding ability and function analogous to that seen with L-FABP gene ablation. This possibility was addressed using the recombinant human wild-type (WT) T94T and T94A variant L-FABP and cultured primary human hepatocytes. Nonconservative replacement of the medium-sized, polar, uncharged T residue with a smaller, nonpolar, aliphatic A residue at position 94 of the human L-FABP significantly increased the L-FABP α-helical structure content at the expense of β-sheet content and concomitantly decreased the thermal stability. T94A did not alter the binding affinities for peroxisome proliferator-activated receptor α (PPARα) agonist ligands (phytanic acid, fenofibrate, and fenofibric acid). While T94A did not alter the impact of phytanic acid and only slightly altered that of fenofibrate on the human L-FABP secondary structure, the active metabolite fenofibric acid altered the T94A secondary structure much more than that of the WT T94T L-FABP. Finally, in cultured primary human hepatocytes, the T94A variant exhibited a significantly reduced extent of fibrate-mediated induction of PPARα-regulated proteins such as L-FABP, FATP5, and PPARα itself. Thus, while the T94A substitution did not alter the affinity of the human L-FABP for PPARα agonist ligands, it significantly altered the human L-FABP structure, stability, and conformational and functional response to fibrate.

  5. Population structure, density and food sources of Terebralia palustris (Potamididae: Gastropoda) in a low intertidal Avicennia marina mangrove stand (Inhaca Island, Mozambique)

    NASA Astrophysics Data System (ADS)

    Penha-Lopes, Gil; Bouillon, Steven; Mangion, Perrine; Macia, Adriano; Paula, José

    2009-09-01

    Population structure and distribution of Terebralia palustris were compared with the environmental parameters within microhabitats in a monospecific stand of Avicennia marina in southern Mozambique. Stable carbon and nitrogen isotope analyses of T. palustris and potential food sources (leaves, pneumatophore epiphytes, and surface sediments) were examined to establish the feeding preferences of T. palustris. Stable isotope signatures of individuals of different size classes and from different microhabitats were compared with local food sources. Samples of surface sediments 2.5-10 m apart showed some variation (-21.2‰ to -23.0‰) in δ13C, probably due to different contributions from seagrasses, microalgae and mangrove leaves, while δ15N values varied between 8.7‰ and 15.8‰, indicating that there is a very high variability within a small-scale microcosm. Stable isotope signatures differed significantly between the T. palustris size classes and between individuals of the same size class, collected in different microhabitats. Results also suggested that smaller individuals feed on sediment, selecting mainly benthic microalgae, while larger individuals feed on sediment, epiphytes and mangrove leaves. Correlations were found between environmental parameters and gastropod population structure and distribution vs. the feeding preferences of individuals of different size classes and in different microhabitats. While organic content and the abundance of leaves were parameters that correlated best with the total density of gastropods (>85%), the abundance of pneumatophores and leaves, as well as grain size, correlated better with the gastropod size distribution (>65%). Young individuals (height < 3 cm) occur predominantly in microhabitats characterized by a low density of leaf litter and pneumatophores, reduced organic matter and larger grain size, these being characteristic of lower intertidal open areas that favour benthic microalgal growth. With increasing shell

  6. Alteration of resonance structure of water and bioliquids in microwave band under the influence of He-Ne laser irradiation

    NASA Astrophysics Data System (ADS)

    Brill, Gregory E.; Petrosyan, Voldemar I.; Zhytenyova, Elina A.; Sinitsyn, Nickolay I.; Kiritchuk, Vyacheslav F.; Martinov, Lev A.

    2001-07-01

    By means of the new method of transmission-resonance EHF/SHF radiowave spectroscopy alteration of the resonance structure of water, whole blood, blood plasma, serum and erythrocytes haemolysate under the influence of He-Ne laser radiation was established.

  7. Characterization of 4-HNE Modified L-FABP Reveals Alterations in Structural and Functional Dynamics

    PubMed Central

    Smathers, Rebecca L.; Fritz, Kristofer S.; Galligan, James J.; Shearn, Colin T.; Reigan, Philip; Marks, Michael J.; Petersen, Dennis R.

    2012-01-01

    4-Hydroxynonenal (4-HNE) is a reactive α,β-unsaturated aldehyde produced during oxidative stress and subsequent lipid peroxidation of polyunsaturated fatty acids. The reactivity of 4-HNE towards DNA and nucleophilic amino acids has been well established. In this report, using proteomic approaches, liver fatty acid-binding protein (L-FABP) is identified as a target for modification by 4-HNE. This lipid binding protein mediates the uptake and trafficking of hydrophobic ligands throughout cellular compartments. Ethanol caused a significant decrease in L-FABP protein (P<0.001) and mRNA (P<0.05), as well as increased poly-ubiquitinated L-FABP (P<0.001). Sites of 4-HNE adduction on mouse recombinant L-FABP were mapped using MALDI-TOF/TOF mass spectrometry on apo (Lys57 and Cys69) and holo (Lys6, Lys31, His43, Lys46, Lys57 and Cys69) L-FABP. The impact of 4-HNE adduction was found to occur in a concentration-dependent manner; affinity for the fluorescent ligand, anilinonaphthalene-8-sulfonic acid, was reduced from 0.347 µM to Kd1 = 0.395 µM and Kd2 = 34.20 µM. Saturation analyses revealed that capacity for ligand is reduced by approximately 50% when adducted by 4-HNE. Thermal stability curves of apo L-FABP was also found to be significantly affected by 4-HNE adduction (ΔTm = 5.44°C, P<0.01). Computational-based molecular modeling simulations of adducted protein revealed minor conformational changes in global protein structure of apo and holo L-FABP while more apparent differences were observed within the internal binding pocket, revealing reduced area and structural integrity. New solvent accessible portals on the periphery of the protein were observed following 4-HNE modification in both the apo and holo state, suggesting an adaptive response to carbonylation. The results from this study detail the dynamic process associated with L-FABP modification by 4-HNE and provide insight as to how alterations in structural integrity and ligand binding may a

  8. Defective mitochondrial fusion, altered respiratory function, and distorted cristae structure in skin fibroblasts with heterozygous OPA1 mutations.

    PubMed

    Agier, Virginie; Oliviero, Patricia; Lainé, Jeanne; L'Hermitte-Stead, Caroline; Girard, Samantha; Fillaut, Sandrine; Jardel, Claude; Bouillaud, Frédéric; Bulteau, Anne Laure; Lombès, Anne

    2012-10-01

    Deleterious consequences of heterozygous OPA1 mutations responsible for autosomal dominant optic atrophy remain a matter of debate. Primary skin fibroblasts derived from patients have shown diverse mitochondrial alterations that were however difficult to resolve in a unifying scheme. To address the potential use of these cells as disease model, we undertook parallel and quantitative analyses of the diverse reported alterations in four fibroblast lines harboring different OPA1 mutations, nonsense or missense, in the guanosine triphosphatase or the C-terminal coiled-coil domains. We tackled several factors potentially underlying discordant reports and showed that fibroblasts with heterozygous OPA1 mutations present with several mitochondrial alterations. These included defective mitochondrial fusion during pharmacological challenge with the protonophore carbonyl cyanide m-chlorophenyl hydrazone, significant mitochondrial elongation with decreased OPA1 and DRP1 proteins, and abnormal mitochondrial fragmentation during glycolysis shortage or exogenous oxidative stress. Respiratory complex IV activity and subunits steady-state were decreased without alteration of the mitochondrial deoxyribonucleic acid size, amount or transcription. Physical link between OPA1 protein and oxidative phosphorylation was shown by reciprocal immunoprecipitation. Altered cristae structure coexisted with normal response to pro-apoptotic stimuli and expression of Bax or Bcl2 proteins. Skin fibroblasts with heterozygous OPA1 mutations thus share significant mitochondrial remodeling, and may therefore be useful for analyzing disease pathophysiology. Identifying whether the observed alterations are also present in ganglion retinal cells, and which of them underlies their degeneration process remains however an essential goal for therapeutic strategy.

  9. Structural and functional alterations in mitochondrial membrane in picrotoxin-induced epileptic rat brain.

    PubMed

    Acharya, Munjal M; Katyare, Surendra S

    2005-03-01

    Mitochondrial function is a key determinant of both excitability and viability of neurons. Present studies were carried out to decipher cerebral mitochondrial oxidative energy metabolism and membrane function in the chronic condition of generalized seizures induced by picrotoxin (PTX) in rats. PTX-induced convulsions resulted in decreased respiration rates (14-41%) with glutamate, pyruvate + malate, and succinate as substrate. The ADP phosphorylation rates were drastically reduced by 44-65%. An opposite trend was observed with ascorbate + N,N,N',N'-tetramethyl-p-phenylenediamine [corrected] (TMPD) as substrate. In general, uncoupling of the mitochondrial electron transport was observed after PTX treatment. Malate dehydrogenase (MDH) and succinate dehydrogenase (SDH) activities were decreased by 20-80%; also, there was significant reduction in cytochrome b content after PTX treatment, while the F(o)F(1) ATPase (complex V) activity increased in basal and 2,4-dinitrophenol (DNP)-stimulated condition, indicating increased membrane fragility. The substrate kinetics analysis had shown that K(m) and V(max) of the higher affinity kinetic component of ATPase increased significantly by 1.2- to 1.4-fold in epileptic condition. Temperature kinetic analysis revealed 1.2-fold increase in energies of activation with decreased transition temperature. The total phospholipid (TPL) and cholesterol (CHL) contents decreased significantly with lowering of diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylserine (PS), while lysophospholipid (lyso), sphingomyelin (SPM), and phosphatidylcholine components were found to be elevated. Brain mitochondrial membrane was somewhat more fluidized in epileptic animals. Possible consequences of mitochondrial respiratory chain (MRC) dysfunction are discussed. In conclusion, impairment of MRC function along with structural alterations suggests novel pathophysiological mechanisms important for

  10. Castration alters the number and structure of dendritic spines in the male posterodorsal medial amygdala.

    PubMed

    Zancan, Mariana; Dall'Oglio, Aline; Quagliotto, Edson; Rasia-Filho, Alberto A

    2017-02-01

    The posterodorsal medial amygdala (MePD) is responsive to androgens and participates in the integration of olfactory/vomeronasal stimuli for the display of sexual behavior in rats. Adult gonadectomy (GDX) affects the MePD structural integrity at the same time that impairs male mating behavior. At the cellular level, dendritic spines modulate excitatory synaptic transmission, strength, and plasticity. Here, we describe the effect of GDX on the number and shape of dendritic spines in the right and left MePD using confocal microscopy and 3D image reconstruction. Age-matched adult rats were intact (n = 6), submitted to a sham procedure (n = 4) or castrated and studied 90 days after GDX (n = 5). The MePD neurons have a density of 1.1 spines/dendritic μm composed of thin, mushroom-like, stubby/wide, and few ramified or atypical spines. Irrespective of brain hemisphere, GDX decreased the dendritic spine density in the MePD, but induced different effects on each spine type. That is, compared to control groups, GDX reduced (i) the number (up to 50%) of thin, mushroom-like, and ramified spines, and (ii) the size and the neck length of thin spines as well as the head diameter of ramified spines. Besides, GDX increased the number of stubby/wide and atypical spines (up to 140% and 400%, respectively). These data show that GDX promotes a cellular and synaptic reorganization in a spine-specific manner in the MePD. By altering the number and shape of these connectional elements, GDX can affect the neural transmission and hinder the function of integrated brain circuitries in the male brain.

  11. Structural and functional alterations of muscle fibres in the novel mouse model of facioscapulohumeral muscular dystrophy.

    PubMed

    D'Antona, Giuseppe; Brocca, Lorenza; Pansarasa, Orietta; Rinaldi, Chiara; Tupler, Rossella; Bottinelli, Roberto

    2007-11-01

    We recently generated a mouse model of facioscapulohumeral muscular dystrophy (FSHD) by selectively overexpressing FRG1, a candidate gene for FSHD, in skeletal muscle. The muscles of the FRG-1 mice did not show any plasmamembrane defect suggesting a novel pathogenetic mechanism for FSHD. Here, we study structure and function of muscle fibres from three lines of mice overexpressing FRG1 at different levels: FRG1-low, FRG1-med, FRG1-high. Cross-sectional area (CSA), specific force (Po/CSA) and maximum shortening velocity (V(o)) of identified types of muscle fibres from FRG1-low and FRG1-med mice were analysed and found to be lower than in WT mice. Fast fibres and especially type 2B fibres (the fastest type) were preferentially involved in the dystrophic process showing a much larger force deficit than type 1 (slow) fibres. Consistent with the latter observation, the MHC isoform distribution of several muscles of the three FRG1 lines showed a shift towards slower MHC isoforms in comparison to WT muscle. Moreover, fast muscles showed a more evident histological deterioration, a larger atrophy and a higher percentage of centrally nucleated fibres than the soleus, the slowest muscle in mice. Interestingly, loss in CSA, Po/CSA and V(o) of single muscle fibres and MHC isoform shift towards a slower phenotype can be considered early signs of muscular dystrophy (MD). They were, in fact, found also in FRG1-low mice which did not show any impairment of function in vivo and of muscle size in vitro and in soleus muscles, which had a completely preserved morphology. This study provides a detailed characterization of structure and function of muscle fibres in a novel murine model of one of the main human MDs and suggests that fundamental features of the dystrophic process, common to most MDs, such as the intrinsic loss of contractile strength of muscle fibres, the preferential involvement of fast fibres and the shift towards a slow muscle phenotype can occur independently from

  12. Pronounced alterations of cellular metabolism and structure due to hyper- or hypo-osmosis.

    PubMed

    Mao, Lei; Hartl, Daniela; Nolden, Tobias; Koppelstätter, Andrea; Klose, Joachim; Himmelbauer, Heinz; Zabel, Claus

    2008-09-01

    Cell volume alteration represents an important factor contributing to the pathology of late-onset diseases. Previously, it was reported that protein biosynthesis and degradation are inversely (trans) regulated during cell volume regulation. Upon cell shrinkage, protein biosynthesis was up-regulated and protein degradation down-regulated. Cell swelling showed opposite regulation. Recent evidence suggests a decrease of protein biodegradation activity in many neurodegenerative diseases and even during aging; both also show prominent cell shrinkage. To clarify the effect of cell volume regulation on the overall protein turnover dynamics, we investigated mouse embryonic stem cells under hyper- and hypotonic osmotic conditions using a 2-D gel based proteomics approach. These conditions cause cell swelling and shrinkage, respectively. Our results demonstrate that the adaption to altered osmotic conditions and therefore cell volume alterations affects a broad spectrum of cellular pathways, including stress response, cytoskeleton remodeling and importantly, cellular metabolism and protein degradation. Interestingly, protein synthesis and degradation appears to be cis-regulated (same direction) on a global level. Our findings also support the hypothesis that protein alterations due to osmotic stress contribute to the pathology of neurodegenerative diseases due to a 60% expression overlap with proteins found altered in Alzheimer's, Huntington's, or Parkinson's disease. Eighteen percent of the proteins altered are even shared with all three disorders.

  13. 13. Photographic copy of site plan displaying Test Stand 'C' ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. Photographic copy of site plan displaying Test Stand 'C' (4217/E-18), Test Stand 'D' (4223/E-24), and Control and Recording Center (4221/E-22) with ancillary structures, and connecting roads and services. California Institute of Technology, Jet Propulsion Laboratory, Facilities Engineering and Construction Office 'Repairs to Test Stand 'C,' Edwards Test Station, Legend & Site Plan M-1,' drawing no. ESP/115, August 14, 1987. - Jet Propulsion Laboratory Edwards Facility, Test Stand C, Edwards Air Force Base, Boron, Kern County, CA

  14. Structure and Composition of Vegetation on Longleaf Plantation Sites Compared to Natural Stands Occurring Along an Environmental Gradient at the Savannah River Site

    SciTech Connect

    Smith, G.P.

    2000-10-01

    The diversity and abundance of native grasses and herbaceous species characteristic of the longleaf savanna were compared between remnant stands that were not previously under agriculture and recent old-fields.The objective of the study was to establish a baseline for future restoration objectives and to compare the degree of degradation associated with agriculture. In most cases even the natural stands have suffered degradation as a result of fire exclusion and as such are not representative of pristine conditions. Community classification and ordination procedures were implemented to array the communities. Three distinct sub-units were identified and associated with xeric, sub-xeric, and medic types associated with texture and soil moisture. Between plantations and natural stands, the xeric group demonstrated the most similarity. The presence of a B horizon was the most important discriminate variable in both groups.

  15. Below-ambient levels of UV induce chloroplast structural change and alter starch metabolism.

    PubMed

    Fagerberg, W R

    2007-01-01

    Electromagnetic radiation (EMR) in the 400-700 nm bandwidth of photosynthetically active radiation (PAR) has been established as an important source of energy for photosynthesis and environmental signals regulating many aspects of green-plant life. Above-ambient levels of UV-B radiation (290-320 nm) under high-PAR conditions have been shown to elicit responses in chloroplasts of Brassica napus similar to those of chloroplasts at low-PAR exposure (W. Fagerberg and J. Bornman, Physiol. Plant. 101: 833-844, 1997). The question arises as to whether UV at normal levels can also evoke similar responses. Here we provide evidence that even below-ambient levels of UV-B (1/28 ambient; Durham, N.H., U.S.A., 1200 hours, March) were capable of inducing an increase in thylakoid surface area relative to the chloroplast volume typical of a low-PAR response (shade response) in sunflowers. This response occurred even though leaves were concurrently exposed to PAR levels that normally induce a "sun" or high-PAR response in the absence of UV-B. Subambient levels of UV-B were also associated with a decrease in chloroplast and starch volume. Exposure to levels of UV-A 1/10 of ambient appeared to enhance the high-PAR response of the chloroplast, characterized by an increase in the amounts of stored starch, an increase in chloroplast volume density ratio values, and a decrease in thylakoid surface area density ratios relative to the high-light controls. These effects were opposite to those seen in UV-B-exposed tissue. In a general sense, subambient levels of UV-B evoked a response similar to that elicited by low-PAR irradiance, while subambient UV-A elicited responses similar to those typical of high-PAR irradiance. The fact that below-ambient levels of UV altered a normal chloroplast structural response to PAR provides evidence that UV may be an important environmental signal for plants.

  16. Asexual endophytes and associated alkaloids alter arthropod community structure and increase herbivore abundances on a native grass.

    PubMed

    Jani, Andrea J; Faeth, Stanley H; Gardner, Dale

    2010-01-01

    Despite their minute biomass, microbial symbionts of plants potentially alter herbivory, diversity and community structure. Infection of grasses by asexual endophytic fungi often decreases herbivore loads and alters arthropod diversity. However, most studies to date have involved agronomic grasses and often consider only infection status (infected vs. uninfected), without explicitly measuring endophyte-produced alkaloids, which vary among endophyte isolates and may impact consumers. We combined field experiments and population surveys to investigate how endophyte infection and associated alkaloids influence abundances, species richness, evenness and guild structure of arthropod communities on a native grass, Achnatherum robustum (sleepygrass). Surprisingly, we found that endophyte-produced alkaloids were associated with increased herbivore abundances and species richness. Our results suggest that, unlike what has been found in agronomic grass systems, high alkaloid levels in native grasses may not protect host grasses from arthropod herbivores, and may instead more negatively affect natural enemies of herbivores.

  17. Looking northeast from Test Stand 'A' superstructure towards Test Stand ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking northeast from Test Stand 'A' superstructure towards Test Stand 'D' tower (4223/E-24, left background), Test Stand 'C' tower (4217/E-18, center), and Test Stand 'B' (4215/E-16, right foreground). - Jet Propulsion Laboratory Edwards Facility, Edwards Air Force Base, Boron, Kern County, CA

  18. Saturn IB in MSFC Dynamic Test Stand

    NASA Technical Reports Server (NTRS)

    1965-01-01

    A completely assembled Saturn IB launch vehicle stands in the Marshall Space Flight Center (MSFC) Dynamic Test Stand, April 14, 1965, for testing on the structural integrity of the vehicle. Developed by the MSFC as an interim vehicle in MSFC's 'building block' approach to Saturn rocket development, the Saturn IB utilized Saturn I technology to further develop and refine large boosters and the Apollo spacecraft capabilities required for the marned lunar missions.

  19. PPT Thrust Stand

    NASA Technical Reports Server (NTRS)

    Haag, Thomas W.

    1995-01-01

    A torsional-type thrust stand has been designed and built to test Pulsed Plasma Thrusters (PPT's) in both single shot and repetitive operating modes. Using this stand, momentum per pulse was determined strictly as a function of thrust stand deflection, spring constant, and natural frequency. No empirical corrections were required. The accuracy of the method was verified using a swinging impact pendulum. Momentum transfer data between the thrust stand and the pendulum were consistent to within 1%. Following initial calibrations, the stand was used to test a Lincoln Experimental Satellite (LES-8/9) thruster. The LES-8/9 system had a mass of approximately 7.5 kg, with a nominal thrust to weight ratio of 1.3 x 10(exp -5). A total of 34 single shot thruster pulses were individually measured. The average impulse bit per pulse was 266 microN-s, which was slightly less than the value of 300 microN-s published in previous reports on this device. Repetitive pulse measurements were performed similar to ordinary steady-state thrust measurements. The thruster was operated for 30 minutes at a repetition rate of 132 pulses per minute and yielded an average thrust of 573 microN. Using average thrust, the average impulse bit per pulse was estimated to be 260 microN-s, which was in agreement with the single shot data. Zero drift during the repetitive pulse test was found to be approximately 1% of the measured thrust.

  20. Conodont color alteration (CAI) as an aid to structural interpretation in the Black Pine Mountains, Idaho

    USGS Publications Warehouse

    Smith, Fred J.; Wardlaw, Bruce R.

    2012-01-01

    The Black Pine Mountains, southeastern Cassia County, Idaho, consist of southern and northern blocks separated by a northeast-trending, high-angle fault. Differences in conodont color alteration values distinguish the two blocks. The southern block has significantly higher organic maturation levels than the northern block and is interpreted to have been thrust northeastward adjacent to the northern block.

  1. How-to-Do-It: Herbivory-Induced Alteration of Community Structure--A Classroom Model.

    ERIC Educational Resources Information Center

    Porter, John R.

    1989-01-01

    Described is a laboratory study designed to demonstrate loss of vegetation, alterations in the species composition of a community, and the impoverishment of a community with respect to desirable food plant species when herbivore feeding exceeds the rate of vegetation regrowth. The laboratory uses a classroom aquarium. (CW)

  2. Time-Dependent Structural Alteration of Rituximab Analyzed by LC/TOF-MS after a Systemic Administration to Rats

    PubMed Central

    Otani, Yuki; Tsuda, Masahiro; Imai, Satoshi; Ikemi, Yasuaki; Nakagawa, Shunsaku; Omura, Tomohiro; Nakagawa, Takayuki; Yano, Ikuko; Matsubara, Kazuo

    2017-01-01

    Therapeutic monoclonal antibodies (mAbs) have heterogeneities in their structures. Multiple studies have reported that the variety of post-translational modifications could affect the pharmacokinetic profiles or pharmacological potencies of therapeutic mAbs. Taking into the account that the structural modification of mAbs would affect the efficacy, it is worth investigating the structural alteration of therapeutic mAbs in the blood and the relationship between their structures and pharmacological effects. Herein, we have developed the method to isolate rituximab from plasma in which endogenous IgGs interfere the detection of rituximab, and successfully developed the analytical method with a liquid chromatograph time-of-flight mass spectrometer to detect the structure of rituximab in plasma with errors less than 30 parts per millions. Eight types of carbohydrate chains in rituximab were detected by this method. Interestingly, time-dependent changes in carbohydrate chains such as AAF (G2F) and GnGn (G0) were observed in rats, although the amino acids were stable. Additionally, these structural changes were observed via incubation in plasma as in the rat experiment, suggesting that a certain type of enzyme in plasma caused the alterations of the carbohydrate chains. The present analytical methods could clarify the actual pharmacokinetics of therapeutic mAbs, and help to evaluate the interindividual variations in pharmacokinetics and efficacy. PMID:28052138

  3. Diazinon alters sperm chromatin structure in mice by phosphorylating nuclear protamines

    SciTech Connect

    Pina-Guzman, B.; Solis-Heredia, M.J.; Quintanilla-Vega, B. . E-mail: mquintan@mail.cinvestav.mx

    2005-01-15

    Organophosphorus (OP) pesticides, widely used in agriculture and pest control, are associated with male reproductive effects, including sperm chromatin alterations, but the mechanisms underlying these effects are unknown. The main toxic action of OP is related to phosphorylation of proteins. Chemical alterations in sperm nuclear proteins (protamines), which pack DNA during the last steps of spermatogenesis, contribute to male reproductive toxicity. Therefore, in the present study, we tested the ability of diazinon (DZN), an OP compound, to alter sperm chromatin by phosphorylating nuclear protamines. Mice were injected with a single dose of DZN (8.12 mg/kg, i.p.), and killed 8 and 15 days after treatment. Quality of sperm from epididymis and vas deferens was evaluated through standard methods and chromatin condensation by flow cytometry (DNA Fragmented Index parameters: DFI and DFI%) and fluorescence microscopy using chromomycin-A{sub 3} (CMA{sub 3}). Increases in DFI (15%), DFI% (4.5-fold), and CMA{sub 3} (2-fold) were observed only at 8 days post-treatment, indicating an alteration in sperm chromatin condensation and DNA damage during late spermatid differentiation. In addition, an increase of phosphorous content (approximately 50%) in protamines, especially in the phosphoserine content (approximately 73%), was found at 8 days post-treatment. Sperm viability, motility, and morphology showed significant alterations at this time. These data strongly suggest that spermatozoa exposed during the late steps of maturation were the targets of DZN exposure. The correlation observed between the phosphorous content in nuclear protamines with DFI%, DFI, and CMA{sub 3} provides evidence that phosphorylation of nuclear protamines is involved in the OP effects on sperm chromatin.

  4. Wide-area estimates of stand structure and water use of tamarix spp. on the lower colorado river: Implications for restoration and water management projects

    USGS Publications Warehouse

    Nagler, P.L.; Glenn, E.P.; Didan, K.; Osterberg, J.; Jordan, F.; Cunningham, J.

    2008-01-01

    Tamarix spp. removal has been proposed to salvage water and allow native vegetation to recolonize western U.S. riparian corridors. We conducted wide-area studies on the Lower Colorado River to answer some of the scientific questions about Tamarix water use and the consequences of removal, combining ground surveys with remote sensing methods. Tamarix stands had moderate rates of evapotranspiration (ET), based on remote sensing estimates, averaging 1.1 m/yr, similar to rates determined for other locations on the river and other rivers. Leaf area index values were also moderate, and stands were relatively open, with areas of bare soil interspersed within stands. At three Tamarix sites in the Cibola National Wildlife Refuge, groundwater salinity at the site nearest to the river (200 m) was relatively low (circa 2,250 mg/L) and was within 3 m of the surface. However, 750 and 1,500 m from the river, the groundwater salinity was 5,000-10,000 mg/L due to removal of water by the Tamarix stands. Despite the high groundwater salinity, the sites away from the river did not have saline surface soils. Only 1% of the mean annual river flow is lost to Tamarix ET on the Lower Colorado River in the United States, and the opportunities for water salvage through Tamarix removal are constrained by its modest ET rates. A possible alternative to Tamarix removal is to intersperse native plants among the stands to improve the habitat value of the riparian zone. ?? 2008 Society for Ecological Restoration International.

  5. Standing wave compressor

    DOEpatents

    Lucas, Timothy S.

    1991-01-01

    A compressor for compression-evaporation cooling systems, which requires no moving parts. A gaseous refrigerant inside a chamber is acoustically compressed and conveyed by means of a standing acoustic wave which is set up in the gaseous refrigerant. This standing acoustic wave can be driven either by a transducer, or by direct exposure of the gas to microwave and infrared sources, including solar energy. Input and output ports arranged along the chamber provide for the intake and discharge of the gaseous refrigerant. These ports can be provided with optional valve arrangements, so as to increase the compressor's pressure differential. The performance of the compressor in either of its transducer or electromagnetically driven configurations, can be optimized by a controlling circuit. This controlling circuit holds the wavelength of the standing acoustical wave constant, by changing the driving frequency in response to varying operating conditions.

  6. Standing alone with prosodic help*

    PubMed Central

    Frazier, Lyn; Clifton, Charles; Carlson, Katy; Harris, Jesse A.

    2013-01-01

    Two partially independent issues are addressed in two auditory rating studies: under what circumstances is a sub-string of a sentence identified as a stand-alone sentence, and under what circumstances do globally ill-formed but ‘locally coherent’ analyses (Tabor, Galantucci, & Richardson., 2004) emerge? A new type of locally coherent structure is established in Experiment 1, where a that-less complement clause is at least temporarily analyzed as a stand-alone sentence when it corresponds to a prosodic phrase. In Experiment 2, reduced relative clause structures like those in Tabor et al. were investigated. As in Experiment 1, the root sentence (mis-)analyses emerged most frequently when the locally coherent clause corresponded to a prosodic phrase. However, a substantial number of locally coherent analyses emerged even without prosodic help, especially in examples with for-datives (which do not grammatically permit a reduced relative clause structure for some speakers). Overall, the results suggest that prosodic grouping of constituents encourages analysis of a sub-string as a root sentence, and raise the question of whether all local coherence structures involve analysis of an utterance-final sub-string as a root sentence. PMID:24729648

  7. Standing equine sinus surgery.

    PubMed

    Barakzai, Safia Z; Dixon, Padraic M

    2014-04-01

    Trephination of the equine sinuses is a common surgical procedure in sedated standing horses. Standing sinus flap surgery has become increasingly popular in equine referral hospitals and offers several advantages over sinusotomy performed under general anesthesia, including reduced patient-associated risks and costs; less intraoperative hemorrhage, allowing better visualization of the operative site; and allows surgeons to take their time. Other minimally invasive surgical procedures include sinoscopic surgery, balloon sinuplasty, and transnasal laser sinonasal fenestration. Despite the procedure used, appropriate indications for surgery, good patient selection, and familiarity with regional anatomy and surgical techniques are imperative for good results.

  8. Altered white matter and cortical structure in neonates with antenatally diagnosed isolated ventriculomegaly

    PubMed Central

    Lockwood Estrin, G.; Kyriakopoulou, V.; Makropoulos, A.; Ball, G.; Kuhendran, L.; Chew, A.; Hagberg, B.; Martinez-Biarge, M.; Allsop, J.; Fox, M.; Counsell, S.J.; Rutherford, M.A.

    2016-01-01

    Ventriculomegaly (VM) is the most common central nervous system abnormality diagnosed antenatally, and is associated with developmental delay in childhood. We tested the hypothesis that antenatally diagnosed isolated VM represents a biological marker for altered white matter (WM) and cortical grey matter (GM) development in neonates. 25 controls and 21 neonates with antenatally diagnosed isolated VM had magnetic resonance imaging at 41.97(± 2.94) and 45.34(± 2.14) weeks respectively. T2-weighted scans were segmented for volumetric analyses of the lateral ventricles, WM and cortical GM. Diffusion tensor imaging (DTI) measures were assessed using voxel-wise methods in WM and cortical GM; comparisons were made between cohorts. Ventricular and cortical GM volumes were increased, and WM relative volume was reduced in the VM group. Regional decreases in fractional anisotropy (FA) and increases in mean diffusivity (MD) were demonstrated in WM of the VM group compared to controls. No differences in cortical DTI metrics were observed. At 2 years, neurodevelopmental delays, especially in language, were observed in 6/12 cases in the VM cohort. WM alterations in isolated VM cases may be consistent with abnormal development of WM tracts involved in language and cognition. Alterations in WM FA and MD may represent neural correlates for later neurodevelopmental deficits. PMID:26937382

  9. Altering the trajectory of early postnatal cortical development can lead to structural and behavioural features of autism

    PubMed Central

    2010-01-01

    Background Autism is a behaviourally defined neurodevelopmental disorder with unknown etiology. Recent studies in autistic children consistently point to neuropathological and functional abnormalities in the temporal association cortex (TeA) and its associated structures. It has been proposed that the trajectory of postnatal development in these regions may undergo accelerated maturational alterations that predominantly affect sensory recognition and social interaction. Indeed, the temporal association regions that are important for sensory recognition and social interaction are one of the last regions to mature suggesting a potential vulnerability to early maturation. However, direct evaluation of the emerging hypothesis that an altered time course of early postnatal development can lead to an ASD phenotype remains lacking. Results We used electrophysiological, histological, and behavioural techniques to investigate if the known neuronal maturational promoter valproate, similar to that in culture systems, can influence the normal developmental trajectory of TeA in vivo. Brain sections obtained from postnatal rat pups treated with VPA in vivo revealed that almost 40% of cortical cells in TeA prematurely exhibited adult-like intrinsic electrophysiological properties and that this was often associated with gross cortical hypertrophy and a reduced predisposition for social play behaviour. Conclusions The co-manifestation of these functional, structural and behavioural features suggests that alteration of the developmental time course in certain high-order cortical networks may play an important role in the neurophysiological basis of autism. PMID:20723245

  10. 24 CFR 3285.903 - Permits, alterations, and on-site structures.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... HOUSING AND URBAN DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Optional Information for...) Installation of on-site structures. Each accessory building and structure is designed to support all of its...

  11. Free-Standing Canes.

    ERIC Educational Resources Information Center

    Ehresman, Paul

    1995-01-01

    A precane device, called the "free-standing cane," was developed to help children with blindness along with other disabilities. The cane detects obstacles; guides the user's hands into a relaxed, static position in front of the hips; facilitates postural security and control; and offers tactile and kinesthetic feedback. (JDD)

  12. View looking west at Test Stand 'A' complex in morning ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View looking west at Test Stand 'A' complex in morning sun. View shows Monitor Building 4203/E-4 at left, barrier (Building 4216/E-17) to right of 4203/E-4, and Test Stand 'A' tower. Attached structure to lower left of tower is Test Stand 'A' machine room which contained refrigeration equipment. Building in right background with Test Stand 'A' tower shadow on it is Assembly Building 4288/E-89, built in 1984. Row of ground-mounted brackets in foreground was used to carry electrical cable and/or fuel lines. - Jet Propulsion Laboratory Edwards Facility, Test Stand A, Edwards Air Force Base, Boron, Kern County, CA

  13. Chronic N-amended soils exhibit an altered bacterial community structure in Harvard Forest, MA, USA.

    PubMed

    Turlapati, Swathi A; Minocha, Rakesh; Bhiravarasa, Premsai S; Tisa, Louis S; Thomas, William K; Minocha, Subhash C

    2013-02-01

    At the Harvard Forest, Petersham, MA, the impact of 20 years of annual ammonium nitrate application to the mixed hardwood stand on soil bacterial communities was studied using 16S rRNA genes pyrosequencing. Amplification of 16S rRNA genes was done using DNA extracted from 30 soil samples (three treatments × two horizons × five subplots) collected from untreated (control), low N-amended (50 kg ha(-1) year(-1)) and high N-amended (150 kg ha(-1) year(-1)) plots. A total of 1.3 million sequences were processed using qiime. Although Acidobacteria represented the most abundant phylum based on the number of sequences, Proteobacteria were the most diverse in terms of operational taxonomic units (OTUs). UniFrac analyses revealed that the bacterial communities differed significantly among soil horizons and treatments. Microsite variability among the five subplots was also evident. Nonmetric multidimensional scaling ordination of normalized OTU data followed by permutational manova further confirmed these observations. Richness indicators and indicator species analyses revealed higher bacterial diversity associated with N amendment. Differences in bacterial diversity and community composition associated with the N treatments were also observed at lower phylogenetic levels. Only 28-35% of the 6 936 total OTUs identified were common to three treatments, while the rest were specific to one treatment or common to two.

  14. Role of Altered Structure and Function of NMDA Receptors in Development of Alcohol Dependence

    PubMed Central

    Nagy, József; Kolok, Sándor; Boros, András; Dezső, Péter

    2005-01-01

    Long-term alcohol exposure gives rise to development of physical dependence on alcohol in consequence of changes in certain neurotransmitter functions. Accumulating evidence suggests that the glutamatergic neurotransmitter system, especially the N-methyl-D-aspartate (NMDA) type of glutamate receptors is a particularly important site of ethanol’s action, since ethanol is a potent inhibitor of the NMDA receptors (NMDARs) and prolonged ethanol exposition leads to a compensatory “upregulation” of NMDAR mediated functions supposedly contributing to the occurrence of ethanol tolerance, dependence as well as the acute and delayed signs of ethanol withdrawal. Recently, expression of different types of NMDAR subunits was found altered after long-term ethanol exposure. Especially, the expression of the NR2B and certain splice variant forms of the NR1 subunits were increased in primary neuronal cultures treated intermittently with ethanol. Since NMDA ion channels with such an altered subunit composition have increased permeability for calcium ions, increased agonist sensitivity, and relatively slow closing kinetics, the abovementioned alterations may underlie the enhanced NMDAR activation observed after long-term ethanol exposure. In accordance with these changes, the inhibitory potential of NR2B subunit-selective NMDAR antagonists is also increased, demonstrating excellent potency against alcohol withdrawal-induced in vitro cytotoxicity. Although in vivo data are few with these compounds, according to the effectiveness of the classic NMDAR antagonists in attenuation, not only the physical symptoms, but also some affective and motivational components of alcohol withdrawal, novel NR2B subunit selective NMDAR antagonists may offer a preferable alternative in the pharmacotherapy of alcohol dependence. PMID:18369402

  15. Structural Brain Alterations Associated with Rapid Eye Movement Sleep Behavior Disorder in Parkinson’s Disease

    PubMed Central

    Boucetta, Soufiane; Salimi, Ali; Dadar, Mahsa; Jones, Barbara E.; Collins, D. Louis; Dang-Vu, Thien Thanh

    2016-01-01

    Characterized by dream-enactment motor manifestations arising from rapid eye movement (REM) sleep, REM sleep behavior disorder (RBD) is frequently encountered in Parkinson’s disease (PD). Yet the specific neurostructural changes associated with RBD in PD patients remain to be revealed by neuroimaging. Here we identified such neurostructural alterations by comparing large samples of magnetic resonance imaging (MRI) scans in 69 PD patients with probable RBD, 240 patients without RBD and 138 healthy controls, using deformation-based morphometry (p < 0.05 corrected for multiple comparisons). All data were extracted from the Parkinson’s Progression Markers Initiative. PD patients with probable RBD showed smaller volumes than patients without RBD and than healthy controls in the pontomesencephalic tegmentum, medullary reticular formation, hypothalamus, thalamus, putamen, amygdala and anterior cingulate cortex. These results demonstrate that RBD is associated with a prominent loss of volume in the pontomesencephalic tegmentum, where cholinergic, GABAergic and glutamatergic neurons are located and implicated in the promotion of REM sleep and muscle atonia. It is additionally associated with more widespread atrophy in other subcortical and cortical regions whose loss also likely contributes to the altered regulation of sleep-wake states and motor activity underlying RBD in PD patients. PMID:27245317

  16. Functional network alterations and their structural substrate in drug-resistant epilepsy

    PubMed Central

    Caciagli, Lorenzo; Bernhardt, Boris C.; Hong, Seok-Jun; Bernasconi, Andrea; Bernasconi, Neda

    2014-01-01

    The advent of MRI has revolutionized the evaluation and management of drug-resistant epilepsy by allowing the detection of the lesion associated with the region that gives rise to seizures. Recent evidence indicates marked chronic alterations in the functional organization of lesional tissue and large-scale cortico-subcortical networks. In this review, we focus on recent methodological developments in functional MRI (fMRI) analysis techniques and their application to the two most common drug-resistant focal epilepsies, i.e., temporal lobe epilepsy related to mesial temporal sclerosis and extra-temporal lobe epilepsy related to focal cortical dysplasia. We put particular emphasis on methodological developments in the analysis of task-free or “resting-state” fMRI to probe the integrity of intrinsic networks on a regional, inter-regional, and connectome-wide level. In temporal lobe epilepsy, these techniques have revealed disrupted connectivity of the ipsilateral mesiotemporal lobe, together with contralateral compensatory reorganization and striking reconfigurations of large-scale networks. In cortical dysplasia, initial observations indicate functional alterations in lesional, peri-lesional, and remote neocortical regions. While future research is needed to critically evaluate the reliability, sensitivity, and specificity, fMRI mapping promises to lend distinct biomarkers for diagnosis, presurgical planning, and outcome prediction. PMID:25565942

  17. [Some aspects of structural alterations of erythrocyte membranes under the effect of uranyl chloride at low concentrations].

    PubMed

    Shevchenko, O G

    2015-01-01

    The influence of nanomolar concentrations of the uranyl ion on the parameters of some membrane structures of rodent erythrocytes (laboratory mice and tundra voles--classical objects of radioecological monitoring) was investigated in vitro. A high sensitivity of the tundra vole red blood cells to the uranyl influence was shown. This fact may be determined by the cross-species difference in the membrane structures of erythrocytes--the low sphingomyelin content in tundra voles. Investigation into the phospholipid composition of the erythrocytes incubated in vitro with uranyl ions demonstrates the absence of the membrane lipid component reactions "typical" for the cells circulating in blood and also the changes pointing to the initial stages of eryptosis. Latent alterations in the membrane structure of red blood cells of both species induced by a short time contact with uranyl ions were confirmed by the increase in their sensitivity to nonionic detergent Triton X-100 and indicate the changes in orderliness of the membrane lipid phase.

  18. 20. Building 202, detail of stand A, rocket test stand ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. Building 202, detail of stand A, rocket test stand in test cell. View looking southeast. - Rocket Engine Testing Facility, GRC Building No. 202, NASA Glenn Research Center, Cleveland, Cuyahoga County, OH

  19. Global analysis of somatic structural genomic alterations and their impact on gene expression in diverse human cancers

    PubMed Central

    Alaei-Mahabadi, Babak; Karlsson, Joakim W.; Nilsson, Jonas A.; Larsson, Erik

    2016-01-01

    Tumor genomes are mosaics of somatic structural variants (SVs) that may contribute to the activation of oncogenes or inactivation of tumor suppressors, for example, by altering gene copy number amplitude. However, there are multiple other ways in which SVs can modulate transcription, but the general impact of such events on tumor transcriptional output has not been systematically determined. Here we use whole-genome sequencing data to map SVs across 600 tumors and 18 cancers, and investigate the relationship between SVs, copy number alterations (CNAs), and mRNA expression. We find that 34% of CNA breakpoints can be clarified structurally and that most amplifications are due to tandem duplications. We observe frequent swapping of strong and weak promoters in the context of gene fusions, and find that this has a measurable global impact on mRNA levels. Interestingly, several long noncoding RNAs were strongly activated by this mechanism. Additionally, SVs were confirmed in telomere reverse transcriptase (TERT) upstream regions in several cancers, associated with elevated TERT mRNA levels. We also highlight high-confidence gene fusions supported by both genomic and transcriptomic evidence, including a previously undescribed paired box 8 (PAX8)–nuclear factor, erythroid 2 like 2 (NFE2L2) fusion in thyroid carcinoma. In summary, we combine SV, CNA, and expression data to provide insights into the structural basis of CNAs as well as the impact of SVs on gene expression in tumors. PMID:27856756

  20. Breast cancer cell cyclooxygenase-2 expression alters extracellular matrix structure and function and numbers of cancer associated fibroblasts.

    PubMed

    Krishnamachary, Balaji; Stasinopoulos, Ioannis; Kakkad, Samata; Penet, Marie-France; Jacob, Desmond; Wildes, Flonne; Mironchik, Yelena; Pathak, Arvind P; Solaiyappan, Meiyappan; Bhujwalla, Zaver M

    2017-01-31

    Cyclooxygenase-2 (COX-2) is a critically important mediator of inflammation that significantly influences tumor angiogenesis, invasion, and metastasis. We investigated the role of COX-2 expressed by triple negative breast cancer cells in altering the structure and function of the extracellular matrix (ECM). COX-2 downregulation effects on ECM structure and function were investigated using magnetic resonance imaging (MRI) and second harmonic generation (SHG) microscopy of tumors derived from triple negative MDA-MB-231 breast cancer cells, and a derived clone stably expressing a short hairpin (shRNA) molecule downregulating COX-2. MRI of albumin-GdDTPA was used to characterize macromolecular fluid transport in vivo and SHG microscopy was used to quantify collagen 1 (Col1) fiber morphology. COX-2 downregulation decreased Col1 fiber density and altered macromolecular fluid transport. Immunohistochemistry identified significantly fewer activated cancer associated fibroblasts (CAFs) in low COX-2 expressing tumors. Metastatic lung nodules established by COX-2 downregulated cells were infrequent, smaller, and contained fewer Col1 fibers.COX-2 overexpression studies were performed with tumors derived from triple negative SUM-149 breast cancer cells lentivirally transduced to overexpress COX-2. SHG microscopy identified significantly higher Col1 fiber density in COX-2 overexpressing tumors with an increase of CAFs. These data expand upon the roles of COX-2 in shaping the structure and function of the ECM in primary and metastatic tumors, and identify the potential role of COX-2 in modifying the number of CAFs in tumors that may have contributed to the altered ECM.

  1. Structural alterations in rat liver proteins due to streptozotocin-induced diabetes and the recovery effect of selenium: Fourier transform infrared microspectroscopy and neural network study

    NASA Astrophysics Data System (ADS)

    Bozkurt, Ozlem; Haman Bayari, Sevgi; Severcan, Mete; Krafft, Christoph; Popp, Jürgen; Severcan, Feride

    2012-07-01

    The relation between protein structural alterations and tissue dysfunction is a major concern as protein fibrillation and/or aggregation due to structural alterations has been reported in many disease states. In the current study, Fourier transform infrared microspectroscopic imaging has been used to investigate diabetes-induced changes on protein secondary structure and macromolecular content in streptozotocin-induced diabetic rat liver. Protein secondary structural alterations were predicted using neural network approach utilizing the amide I region. Moreover, the role of selenium in the recovery of diabetes-induced alterations on macromolecular content and protein secondary structure was also studied. The results revealed that diabetes induced a decrease in lipid to protein and glycogen to protein ratios in diabetic livers. Significant alterations in protein secondary structure were observed with a decrease in α-helical and an increase in β-sheet content. Both doses of selenium restored diabetes-induced changes in lipid to protein and glycogen to protein ratios. However, low-dose selenium supplementation was not sufficient to recover the effects of diabetes on protein secondary structure, while a higher dose of selenium fully restored diabetes-induced alterations in protein structure.

  2. The tomato res mutant which accumulates JA in roots in non-stressed conditions restores cell structure alterations under salinity.

    PubMed

    Garcia-Abellan, José O; Fernandez-Garcia, Nieves; Lopez-Berenguer, Carmen; Egea, Isabel; Flores, Francisco B; Angosto, Trinidad; Capel, Juan; Lozano, Rafael; Pineda, Benito; Moreno, Vicente; Olmos, Enrique; Bolarin, Maria C

    2015-11-01

    Jasmonic acid (JA) regulates a wide spectrum of plant biological processes, from plant development to stress defense responses. The role of JA in plant response to salt stress is scarcely known, and even less known is the specific response in root, the main plant organ responsible for ionic uptake and transport to the shoot. Here we report the characterization of the first tomato (Solanum lycopersicum) mutant, named res (restored cell structure by salinity), that accumulates JA in roots prior to exposure to stress. The res tomato mutant presented remarkable growth inhibition and displayed important morphological alterations and cellular disorganization in roots and leaves under control conditions, while these alterations disappeared when the res mutant plants were grown under salt stress. Reciprocal grafting between res and wild type (WT) (tomato cv. Moneymaker) indicated that the main organ responsible for the development of alterations was the root. The JA-signaling pathway is activated in res roots prior to stress, with transcripts levels being even higher in control condition than in salinity. Future studies on this mutant will provide significant advances in the knowledge of JA role in root in salt-stress tolerance response, as well as in the energy trade-off between plant growth and response to stress.

  3. Is meditation associated with altered brain structure? A systematic review and meta-analysis of morphometric neuroimaging in meditation practitioners.

    PubMed

    Fox, Kieran C R; Nijeboer, Savannah; Dixon, Matthew L; Floman, James L; Ellamil, Melissa; Rumak, Samuel P; Sedlmeier, Peter; Christoff, Kalina

    2014-06-01

    Numerous studies have begun to address how the brain's gray and white matter may be shaped by meditation. This research is yet to be integrated, however, and two fundamental questions remain: Is meditation associated with altered brain structure? If so, what is the magnitude of these differences? To address these questions, we reviewed and meta-analyzed 123 brain morphology differences from 21 neuroimaging studies examining ∼300 meditation practitioners. Anatomical likelihood estimation (ALE) meta-analysis found eight brain regions consistently altered in meditators, including areas key to meta-awareness (frontopolar cortex/BA 10), exteroceptive and interoceptive body awareness (sensory cortices and insula), memory consolidation and reconsolidation (hippocampus), self and emotion regulation (anterior and mid cingulate; orbitofrontal cortex), and intra- and interhemispheric communication (superior longitudinal fasciculus; corpus callosum). Effect size meta-analysis (calculating 132 effect sizes from 16 studies) suggests a global 'medium' effect size (Cohen's d¯=0.46; r¯=.19). Publication bias and methodological limitations are strong concerns, however. Further research using rigorous methods is required to definitively link meditation practice to altered brain morphology.

  4. Get up, Stand up

    ERIC Educational Resources Information Center

    Melia, Ed

    2009-01-01

    Ignorance about dyslexia meant a miserable school experience for Barrie Hughes. He was in his 50s when he found the courage to stand up in front of a classroom of learners and admit he couldn't read. Barrie, who is now 59 and works for the parks department of Brighton and Hove Council, only began to learn how to read words in the last three years…

  5. Beam optics test stand

    NASA Astrophysics Data System (ADS)

    Humphries, S., Jr.; Hess, G.

    1988-04-01

    The design and construction of the Beam Optics Test Stand (BOTS) is presented. A variety of computer compatible diagnostics has been developed to facilitate experiments. Extensive theoretical work is presented leading to the identification of two potential methods to correct aberrations in magnetic optics: biased grid arrays and space charge corrected solenoidal lenses. A series of experiments is presented which demonstrates, for the first time, the feasibility of space charge corrected optics.

  6. Guitar Strings as Standing Waves: A Demonstration

    NASA Astrophysics Data System (ADS)

    Davis, Michael

    2007-08-01

    An undergraduate student's first exposure to modern atomic theory tends to start with Bohr's model of the atom. This familiar introduction to atomic structure also marks a general chemistry student's first foray into waves. Many popular chemistry textbooks illustrate the concept of a standing wave in the development of the modern quantum model by using the phrase “as seen on a guitar string”. In these illustrations, the wave itself is often small and difficult to discern. The same phenomenon, however, can be easily and audibly observed. This demonstration uses an acoustic guitar to produce three unique harmonic vibrations, each of which is representative of a standing wave and illustrates the concept of quantization. Manipulation of the guitar string to produce a standing wave is pervasive in popular music and is audibly recognizable. Lightly placing a finger on the 12th, 7th, or 5th fret and strumming any one or all six strings can produce an audible example of a standing wave on a guitar. This corresponds to a standing wave with 1, 2, or 3 nodes, respectively. Attempting to induce a node at other points on a guitar string does not generate a standing wave, due to destructive interference, thus no audible tone is produced.

  7. Thyroid status alters structure of VLDL secreted by perfused rat liver.

    PubMed

    Schroeder, F; Keyes, W G; Wilcox, H G; Heimberg, M

    1982-01-01

    The interaction of thyroid status and oleic acid infusion rate on the thermal behavior of the very low density lipoprotein (VLDL) secreted by isolated perfused rat liver was examined. The livers were infused at 37 degrees C with oleate at rates of 0, 83, 166, or 332 mumoles/hr for 4 hours and VLDL was isolated from the perfusate at 12 degrees C. The lipid composition of the VLDL secreted by the perfused liver from hyperthyroid animals was dramatically different from controls at all infusion rates of oleate. Significant changes in the ratio of [phospholipid + cholesterol]/[triglyceride] and in fatty composition of secreted triglycerides occurred. Differential scanning calorimetry of the intact VLDL and extracted triglycerides secreted by euthyroid rats suggested the existence of four thermotropic endothermic transitions centered at -20.5, -14.0, -3.0, and 9.0 degrees C. Both the total enthalpies and the temperatures at which the phase alterations occurred in the triglyceride fraction from VLDL secreted by livers from euthyroid rats were highly dependent on the rate of infusion of oleate. Pretreatment of the rats with triiodothyronine and infusion of 332 mumoles oleate/hr abolished in the intact VLDL the temperature transitions centered at -20.8 and at 10.5 degrees C and decreased the total enthalpy from 8.13 to 38.5 cal/gm. Livers from rats pretreated with propylthiouracil and infused with oleate at 332 mumoles/hr secreted VLDL in which only one transition centered at -5.0 degrees C remained. The total enthalpy was unaffected. At all rates of infusion of oleate, the phase behavior of the intact VLDL or triglycerides extracted from the VLDL was altered by prior treatment of the rats with triiodothyronine or propylthiouracil. The thyroid state of the rat profoundly affected the thermal properties of the VLDL secreted by the perfused liver infused with the unsaturated fatty acid oleate.

  8. Rainfall and hydrological stability alter the impact of top predators on food web structure and function.

    PubMed

    Marino, Nicholas A C; Srivastava, Diane S; MacDonald, A Andrew M; Leal, Juliana S; Campos, Alice B A; Farjalla, Vinicius F

    2017-02-01

    Climate change will alter the distribution of rainfall, with potential consequences for the hydrological dynamics of aquatic habitats. Hydrological stability can be an important determinant of diversity in temporary aquatic habitats, affecting species persistence and the importance of predation on community dynamics. As such, prey are not only affected by drought-induced mortality but also the risk of predation [a non-consumptive effect (NCE)] and actual consumption by predators [a consumptive effect (CE)]. Climate-induced changes in rainfall may directly, or via altered hydrological stability, affect predator-prey interactions and their cascading effects on the food web, but this has rarely been explored, especially in natural food webs. To address this question, we performed a field experiment using tank bromeliads and their aquatic food web, composed of predatory damselfly larvae, macroinvertebrate prey and bacteria. We manipulated the presence and consumption ability of damselfly larvae under three rainfall scenarios (ambient, few large rainfall events and several small rainfall events), recorded the hydrological dynamics within bromeliads and examined the effects on macroinvertebrate colonization, nutrient cycling and bacterial biomass and turnover. Despite our large perturbations of rainfall, rainfall scenario had no effect on the hydrological dynamics of bromeliads. As a result, macroinvertebrate colonization and nutrient cycling depended on the hydrological stability of bromeliads, with no direct effect of rainfall or predation. In contrast, rainfall scenario determined the direction of the indirect effects of predators on bacteria, driven by both predator CEs and NCEs. These results suggest that rainfall and the hydrological stability of bromeliads had indirect effects on the food web through changes in the CEs and NCEs of predators. We suggest that future studies should consider the importance of the variability in hydrological dynamics among habitats as

  9. Analysis of microtubule growth dynamics arising from altered actin network structure and contractility in breast tumor cells.

    PubMed

    Ory, Eleanor; Bhandary, Lekhana; Boggs, Amanda; Chakrabarti, Kristi; Parker, Joshua; Losert, Wolfgang; Martin, Stuart S

    2017-01-16

    The periphery of epithelial cells is shaped by opposing cytoskeletal physical forces generated predominately by two dynamic force generating systems - growing microtubule ends push against the boundary from the cell center, and the actin cortex contracts the attached plasma membrane. Here we investigate how changes to the structure and dynamics of the actin cortex alter the dynamics of microtubules. Current drugs target actin polymerization and contraction to reduce cell division and invasiveness; however, the impacts on microtubule dynamics remain incompletely understood. Using human MCF-7 breast tumor cells expressing GFP-tagged microtubule end-binding-protein-1 (EB1) and coexpression of cytoplasmic fluorescent protein mCherry, we map the trajectories of growing microtubule ends and cytoplasmic boundary respectively. Based on EB1 tracks and cytoplasmic boundary outlines, we calculate the speed, distance from cytoplasmic boundary, and straightness of microtubule growth. Actin depolymerization with Latrunculin-A reduces EB1 growth speed as well as allows the trajectories to extend beyond the cytoplasmic boundary. Blebbistatin, a direct myosin-II inhibitor, reduced EB1 speed and yielded less straight EB1 trajectories. Inhibiting signaling upstream of myosin-II contractility via the Rho-kinase inhibitor, Y-27632, altered EB1 dynamics differently from Blebbistatin. These results indicate that reduced actin cortex integrity can induce distinct alterations in microtubule dynamics. Given recent findings that tumor stem cell characteristics are increased by drugs which reduce actin contractility or stabilize microtubules, it remains important to clearly define how cytoskeletal drugs alter the interactions between these two filament systems in tumor cells.

  10. ONTOGENETIC ALTERATIONS IN MOLECULAR AND STRUCTURAL CORRELATES OF DENDRITIC GROWTH FOLLOWING DEVELOPMENTAL EXPOSURE TO POLYCHLORINATED BIPHENYLS.

    EPA Science Inventory

    This is the first report showing both molecular and structural changes in brain following developmental exposure to a neurotoxicant. It is known that perinatal exposure to a neurotoxicant, polychlorinated biphenyls (PCBs), is associated with decreased IQ scores, impaired learnin...

  11. STRUCTURE AND FUNCTION OF ANTHROPOGENICALLY ALTERED MICROBIAL COMMUNITIES IN COASTAL WATERS. (R825243)

    EPA Science Inventory

    Human-based (anthropogenic) nutrient and other pollutant enrichment of the world's coastal waters is causing unprecedented changes in microbial community structure and function. Symptoms of these changes include accelerating eutrophication, the proliferation of harmful microal...

  12. Alteration of blood clot structures by interleukin-1 beta in association with bone defects healing

    PubMed Central

    Wang, Xin; Friis, Thor E.; Masci, Paul P.; Crawford, Ross W.; Liao, Wenbo; Xiao, Yin

    2016-01-01

    The quality of hematomas are crucial for successful early bone defect healing, as the structure of fibrin clots can significantly influence the infiltration of cells, necessary for bone regeneration, from adjacent tissues into the fibrin network. This study investigated if there were structural differences between hematomas from normal and delayed healing bone defects and whether such differences were linked to changes in the expression of IL-1β. Using a bone defect model in rats, we found that the hematomas in the delayed healing model had thinner fibers and denser clot structures. Moreover, IL-1β protein levels were significantly higher in the delayed healing hematomas. The effects of IL-1β on the structural properties of human whole blood clots were evaluated by thrombelastograph (TEG), scanning electronic microscopy (SEM), compressive study, and thrombolytic assays. S-nitrosoglutathione (GSNO) was applied to modulate de novo hematoma structure and the impact on bone healing was evaluated in the delayed healing model. We found that GSNO produced more porous hematomas with thicker fibers and resulted in significantly enhanced bone healing. This study demonstrated that IL-1β and GSNO had opposing effects on clot architecture, the structure of which plays a pivotal role in early bone healing. PMID:27767056

  13. Canopy light transmittance in Douglas-fir--western hemlock stands.

    PubMed

    Parker, Geoffrey G; Davis, Melinda M; Chapotin, Saharah Moon

    2002-02-01

    We measured vertical and horizontal variation in canopy transmittance of photosynthetically active radiation in five Pseudotsuga menziesii (Mirb.) Franco-Tsuga heterophylla (Raf.) Sarg. (Douglas-fir-western hemlock) stands in the central Cascades of southern Washington to determine how stand structure and age affect the forest light environment. The shape of the mean transmittance profile was related to stand height, but height of mean maximum transmittance was progressively lower than maximum tree height in older stands. The vertical rate of attenuation declined with stand age in both the overstory and understory. A classification of vertical light zones based on the mean and variance of transmittance showed a progressive widening of the bright (low variance and high mean) and transition (high variance and rapid vertical change) zones in older stands, whereas the dim zone (low variance and mean) narrowed. The zone of maximum canopy surface area in height profiles, estimated by inversion of transmittance profiles, changed from relatively high in the canopy in most young stands ("top-heavy") to lower in the canopy in older stands ("bottom-heavy"). In the understory, all stands had similar mean transmittances, but the spatial scale of variation increased with stand age and increasing crown size. The angular distribution of openness was similar in all stands, though the older stands were less open at all angles than the younger stands. Understory openness was generally unrelated to transmittance in the canopy above. Whole-canopy leaf area indices, estimated using three methods of inverting light measurements, showed little correspondence across methods. The observed patterns in light environment are consistent with structural changes occurring during stand development, particularly the diversification of crowns, the creation of openings of various sizes and the elaboration of the outer canopy surface. The ensemble of measurements has potential use in distinguishing

  14. Measuring and Altering Ferroelectric Domain Structures in Lead Perovskite Single-Crystals

    NASA Astrophysics Data System (ADS)

    Harker, John Chamberlain

    Relaxor ferroelectric single-crystal materials PMN-PT and PZN-PT are currently of interest to the scientific community due to their enhanced properties and possible role as next-generation piezoelectric transducers in applications such as sonar and medical ultrasound. One key phenomenon affecting both the properties and the mechanical integrity of these materials is the ferroelectric domain structure within the material. In this work we examine the morphology and behavior of domain structures in PMN-29%PT. In order to do this we first present details of the construction and testing of a working piezo-response force microscope (PFM), and then use the PFM to verify a new domain observation technique called "relief polishing". Relief polishing is shown to reveal surface domains in the same manner as acid etching, preserving domain details as small as 0.5mum. Using these two techniques, we then determine that cutting and polishing strongly affect the surface and subsurface ferroelectric domain structures in PMN-29%PT. Specifically, we show that saw cutting can create characteristic striated domain structures as deep as 130mum within a sample, while straight polishing creates a characteristic domain structure known as the "fingerprint" pattern to a depth proportional to the size of the polishing grit, on the order of 0--12mum for grits as large as 15mum. We hypothesize that most samples contain these "skin effect" domain structures. In consequence, it is suggested that researchers presenting experimental results on domain structures should report the physical treatment history of the samples along with the experimental data.

  15. Phospholipid and cholesterol alterations accompany structural disarray in myelin membrane of rats with hepatic encephalopathy induced by thioacetamide.

    PubMed

    Swapna, I; Kumar, K V Sathya Sai; Reddy, P Vijaya Bhaskar; Murthy, Ch R K; Reddanna, P; Senthilkumaran, B

    2006-08-01

    Fulminant hepatic failure is often associated with a wide range of neurological symptoms which are collectively referred to as hepatic encephalopathy. Fulminant hepatic failure with associated hepatic encephalopathy has a poor prognosis with the currently available sure treatment being only liver transplantation. This is largely owing to the lack of understanding of critical factors involved in the etiology of the condition. Lipid changes have been implicated in cerebral derangements characteristic of hepatic encephalopathy. About 79% of the brain lipid is concentrated in the myelin fraction where they play an important role in ion balance and conduction of nerve impulses. Hence, in the present study we aimed to investigate changes in myelin lipid composition and structure. Myelin was isolated by sucrose density gradient centrifugation from cerebral cortex of male Wistar rats (250-300 g body weight) treated with 300 mg/kg body weight thioacetamide administered twice at 24h interval to induce hepatic encephalopathy. Significant decrease was observed in the cholesterol and phospholipids content of myelin from treated rats. Sphingomyelin, phosphatidylserine and phosphatidylethanolamine content also decreased significantly following 18 h of thioacetamide administration. However, phosphatidylcholine levels remained unaltered. Transmission electron microscopic observation of myelin membrane from cerebral cortex sections showed considerable disorganization in myelin structure. Increase in malondialdehyde levels precede lipid changes leading to the speculation that oxidative damage may be the critical factor leading to decrease in the anionic phospholipids. Changes in myelin were evident only in later stages of hepatic encephalopathy indicating that myelin alteration may not play a role in early stages of hepatic encephalopathy. Nevertheless, myelin alteration may have a crucial role to play in various psycho-motor alterations during later stages of hepatic encephalopathy.

  16. Altered functional-structural coupling of large-scale brain networks in idiopathic generalized epilepsy.

    PubMed

    Zhang, Zhiqiang; Liao, Wei; Chen, Huafu; Mantini, Dante; Ding, Ju-Rong; Xu, Qiang; Wang, Zhengge; Yuan, Cuiping; Chen, Guanghui; Jiao, Qing; Lu, Guangming

    2011-10-01

    The human brain is a large-scale integrated network in the functional and structural domain. Graph theoretical analysis provides a novel framework for analysing such complex networks. While previous neuroimaging studies have uncovered abnormalities in several specific brain networks in patients with idiopathic generalized epilepsy characterized by tonic-clonic seizures, little is known about changes in whole-brain functional and structural connectivity networks. Regarding functional and structural connectivity, networks are intimately related and share common small-world topological features. We predict that patients with idiopathic generalized epilepsy would exhibit a decoupling between functional and structural networks. In this study, 26 patients with idiopathic generalized epilepsy characterized by tonic-clonic seizures and 26 age- and sex-matched healthy controls were recruited. Resting-state functional magnetic resonance imaging signal correlations and diffusion tensor image tractography were used to generate functional and structural connectivity networks. Graph theoretical analysis revealed that the patients lost optimal topological organization in both functional and structural connectivity networks. Moreover, the patients showed significant increases in nodal topological characteristics in several cortical and subcortical regions, including mesial frontal cortex, putamen, thalamus and amygdala relative to controls, supporting the hypothesis that regions playing important roles in the pathogenesis of epilepsy may display abnormal hub properties in network analysis. Relative to controls, patients showed further decreases in nodal topological characteristics in areas of the default mode network, such as the posterior cingulate gyrus and inferior temporal gyrus. Most importantly, the degree of coupling between functional and structural connectivity networks was decreased, and exhibited a negative correlation with epilepsy duration in patients. Our findings

  17. Regional vulnerability of longitudinal cortical association connectivity: Associated with structural network topology alterations in preterm children with cerebral palsy.

    PubMed

    Ceschin, Rafael; Lee, Vince K; Schmithorst, Vince; Panigrahy, Ashok

    2015-01-01

    alteration in eigenvector centrality, clustering coefficient (inter-regional) and participation co-efficient (inter-modular) alterations of frontal-striatal and fronto-limbic nodes suggesting re-organization of these pathways. Both along tract and structural topology network measurements correlated strongly with motor and visual clinical outcome scores. This study shows the value of combining along-tract analysis and structural network topology in depicting not only selective parietal occipital regional vulnerability but also reorganization of frontal-striatal and frontal-limbic pathways in preterm children with cerebral palsy. These finding also support the concept that widespread, but selective posterior-anterior neural network connectivity alterations in preterm children with cerebral palsy likely contribute to the pathogenesis of neurosensory and cognitive impairment in this group.

  18. Neonatal focal denervation of the rat olfactory bulb alters cell structure and survival: a Golgi, Nissl and confocal study.

    PubMed

    Couper Leo, J M; Brunjes, P C

    2003-02-16

    Contact between sensory axons and their targets is critical for the development and maintenance of normal neural circuits. Previous work indicates that the removal of afferent contact to the olfactory bulb affects bulb organization, neurophenotypic expression, and cell survival. The studies also suggested changes to the structure of individual cell types. The current work examines the effects of denervation on the morphology of mitral/tufted, periglomerular, and granule cells. Focal denervation drastically changed mitral/tufted cell structure but had only subtle effects on periglomerular and granule cells. Denervated mitral/tufted cells lacked apical tufts and, in most cases, a primary dendrite. In addition, the denervated cells had more secondary processes whose orientation with respect to the bulb surface was altered. Our results suggest that contact between olfactory axons and the bulb is necessary for cell maintenance and may be critical for the ability of mitral/tufted cells to achieve adult morphology

  19. Discoidin domain receptor 2 germline gene deletion leads to altered heart structure and function in the mouse.

    PubMed

    Cowling, Randy T; Yeo, Seon Ju; Kim, In Jai; Park, Joong Il; Gu, Yusu; Dalton, Nancy D; Peterson, Kirk L; Greenberg, Barry H

    2014-09-01

    Discoidin domain receptor 2 (DDR2) is a fibrillar collagen receptor that is expressed in mesenchymal cells throughout the body. In the heart, DDR2 is selectively expressed on cardiac fibroblasts. We generated a germline DDR2 knockout mouse and used this mouse to examine the role of DDR2 deletion on heart structure and function. Echocardiographic measurements from null mice were consistent with those from a smaller heart, with reduced left ventricular chamber dimensions and little change in wall thickness. Fractional shortening appeared normal. Left ventricular pressure measurements revealed mild inotropic and lusitropic abnormalities that were accentuated by dobutamine infusion. Both body and heart weights from 10-wk-old male mice were ~20% smaller in null mice. The reduced heart size was not simply due to reduced body weight, since cardiomyocyte lengths were atypically shorter in null mice. Although normalized cardiac collagen mass (assayed by hydroxyproline content) was not different in null mice, the collagen area fraction was statistically higher, suggesting a reduced collagen density from altered collagen deposition and cross-linking. Cultured cardiac fibroblasts from null mice deposited collagen at a slower rate than wild-type littermates, possibly due to the expression of lower prolyl 4-hydroxylase α-isoform 1 enzyme levels. We conclude that genetic deletion of the DDR2 collagen receptor alters cardiac fibroblast function. The resulting perturbations in collagen deposition can influence the structure and function of mature cardiomyocytes.

  20. Intracranial structural alteration predicts treatment outcome in patients with spontaneous intracranial hypotension.

    PubMed

    Choi, Hanna; Lee, Mi Ji; Choi, Hyun Ah; Cha, Jihoon; Chung, Chin-Sang

    2017-01-01

    Background Intracranial structural dislocation in spontaneous intracranial hypotension (SIH) can be measured by various intracranial angles and distances. We aimed to identify the clinical significance of structural dislocation in relation to treatment outcome in patients with SIH. Methods In this retrospective analysis, we identified patients with SIH who received an epidural blood patch (EBP) at Samsung Medical Center from January 2005 to March 2015. Structural dislocation in pretreatment MRIs of SIH patients was assessed by measuring tonsillar herniation, mamillopontine distance, the angle between the vein of Galen and straight sinus (vG/SS angle), the pontomesencephalic angle, and the lateral ventricular angle. After the first EBP, poor response was defined as the persistence of symptoms that prompted a repeat EBP. Results Out of the 95 patients included, 31 (32.6%) showed poor response. Among the radiological markers of structural dislocation, the vG/SS angle was associated with poor response (49.82 ± 16.40° vs 66.58 ± 26.08°, p = 0.002). Among clinical variables, premorbid migraine ( p = 0.036) was related to poor response. In multivariate analysis, reduced vG/SS angle was independently associated with poor response (OR 1.04 [95% CI 1.01 - 1.07] per 1° decrease, p = 0.006). In 23 patients who underwent MRI after successful treatment, the vG/SS angle significantly increased after the EBP ( p < 0.001, by paired t-test), while two patients with aggravation or recurrence showed a further reduction of their vG/SS angles. Conclusions Intracranial structural dislocation, measured by the vG/SS angle, is associated with poor response to the first EBP in patients with SIH. Successful treatment can reverse the structural dislocation.

  1. Bioaugmentation of Hydrogenispora ethanolica LX-B affects hydrogen production through altering indigenous bacterial community structure.

    PubMed

    Yang, Zhiman; Guo, Rongbo; Shi, Xiaoshuang; He, Shuai; Wang, Lin; Dai, Meng; Qiu, Yanling; Dang, Xiaoxiao

    2016-07-01

    Bioaugmentation can facilitate hydrogen production from complex organic substrates, but it still is unknown how indigenous microbial communities respond to the added bacteria. Here, using a Hydrogenispora ethanolica LX-B (named as LX-B) bioaugmentation experiments, the distribution of metabolites and the responses of indigenous bacterial communities were investigated via batch cultivation (BC) and repeated batch cultivation (RBC). In BC the LX-B/sludge ratio of 0.12 achieved substantial high hydrogen yield, which was over twice that of control. In RBC one-time bioaugmentation and repeated batch bioaugmentation of LX-B resulted in the hydrogen yield that was average 1.2-fold and 0.8-fold higher than that in control, respectively. This improved hydrogen production performance mainly benefited from a shift in composition of the indigenous bacterial community caused by LX-B bioaugmentation. The findings represented an important step in understanding the relationship between bioaugmentation, a shift in bacterial communities, and altered bioreactor performance.

  2. Localisation of Neuregulin 1-{beta}3 to different sub-nuclear structures alters gene expression

    SciTech Connect

    Wang, Ming; Trim, Carol M.; Gullick, William J.

    2011-02-15

    Neuregulins are growth factors that signal via the ErbB3 and ErbB4 receptors. Here we show using immunohistochemistry that they are often expressed in the nucleus of a range of tumour types including soft tissue and breast. The Neuregulin 1 type I-{beta}3 (NRG1-{beta}3) isoform localises to two sub-nuclear compartments in animal cells, nucleoli and spliceosomes. We used NRG1-{beta}3 tagged with photoactivatable GFP and demonstrated that this re-localised from nucleoli to spliceosomes over 90 min. Tyrosine kinase activity was not required for retaining the NRG1-{beta}3 within the nucleus. Mutation of the lysines 14 and 16 or 15 and 16 together prevented nucleolar uptake while four positively charged residues were identified which were required for spliceosome uptake. Molecular modelling suggests that three of these may form a binding site. We showed using a kinome array that NRG1-{beta}3 and a mutant exclusively localising to spliceosomes increased phosphorylation and/or expression of the HER4 and HER2 receptors. Using a transcriptomic analysis the same two constructs induced expression of several messenger RNAs and we confirmed the increased expression at the protein level of the most highly induced, Heat Shock Protein 70B'. These results suggest that Neuregulin activates receptor signalling in spliceosomes leading to altered gene expression.

  3. STRUCTURAL MECHANISM FOR ALTERATION OF COLLAGEN GEL MECHANICS BY GLUTARALDEHYDE CROSSLINKING

    PubMed Central

    Chandran, Preethi L.; Paik, David C.; Holmes, Jeffrey W.

    2013-01-01

    Soft collagenous tissues that are loaded in vivo undergo crosslinking during aging and wound healing. Bio-prosthetic tissues implanted in vivo are also commonly crosslinked with glutaraldehyde. While crosslinking changes the mechanical properties of the tissue, the nature of the mechanical changes and the underlying microstructural mechanism is poorly understood. In this study, a combined mechanical, biochemical and simulation approach was employed to identify the microstructural mechanism by which crosslinking alters mechanical properties. The model collagenous tissue used was an anisotropic cell-compacted collagen gel, and the model crosslinking agent was monomeric glutaraldehyde. The collagen gels were incrementally crosslinked by either increasing the glutaraldehyde concentration or by increasing the crosslinking time. In biaxial loading experiments, increased crosslinking produced: (1) decreased strain response to a small equibiaxial preload, with little change in response to subsequent loading, and (2) decreased coupling between the fiber and cross-fiber direction. The mechanical trend was found to be better described by the lysine consumption data than by the shrinkage temperature. The biaxial loading of incrementally-crosslinked collagen gels was simulated computationally with a previously published network model. Crosslinking was represented by increased fibril stiffness or by increased resistance to fibril rotation. Only the latter produced mechanical trends similar to that observed experimentally. Representing crosslinking as increased fibril stiffness did not reproduce the decreased coupling between the fiber and cross-fiber directions. The study concludes that the mechanical changes in crosslinked collagen gels are caused by the microstructural mechanism of increased resistance to fibril rotation. PMID:22775003

  4. Altered structural connectivity of cortico-striato-pallido-thalamic networks in Gilles de la Tourette syndrome

    PubMed Central

    Marrakchi-Kacem, Linda; Lecomte, Sophie; Valabregue, Romain; Poupon, Fabrice; Guevara, Pamela; Tucholka, Alan; Mangin, Jean-François; Vidailhet, Marie; Lehericy, Stephane; Hartmann, Andreas; Poupon, Cyril

    2015-01-01

    Gilles de la Tourette syndrome is a childhood-onset syndrome characterized by the presence and persistence of motor and vocal tics. A dysfunction of cortico-striato-pallido-thalamo-cortical networks in this syndrome has been supported by convergent data from neuro-pathological, electrophysiological as well as structural and functional neuroimaging studies. Here, we addressed the question of structural integration of cortico-striato-pallido-thalamo-cortical networks in Gilles de la Tourette syndrome. We specifically tested the hypothesis that deviant brain development in Gilles de la Tourette syndrome could affect structural connectivity within the input and output basal ganglia structures and thalamus. To this aim, we acquired data on 49 adult patients and 28 gender and age-matched control subjects on a 3 T magnetic resonance imaging scanner. We used and further implemented streamline probabilistic tractography algorithms that allowed us to quantify the structural integration of cortico-striato-pallido-thalamo-cortical networks. To further investigate the microstructure of white matter in patients with Gilles de la Tourette syndrome, we also evaluated fractional anisotropy and radial diffusivity in these pathways, which are both sensitive to axonal package and to myelin ensheathment. In patients with Gilles de la Tourette syndrome compared to control subjects, we found white matter abnormalities in neuronal pathways connecting the cerebral cortex, the basal ganglia and the thalamus. Specifically, striatum and thalamus had abnormally enhanced structural connectivity with primary motor and sensory cortices, as well as paracentral lobule, supplementary motor area and parietal cortices. This enhanced connectivity of motor cortex positively correlated with severity of tics measured by the Yale Global Tics Severity Scale and was not influenced by current medication status, age or gender of patients. Independently of the severity of tics, lateral and medial orbito

  5. Oxidation of gonadotrophin (PMSG) by oxygen free radicals alters its structure and hormonal activity.

    PubMed

    Ortega-Camarillo, C; Guzmán-Grenfell, A M; Hicks, J J

    1999-03-01

    The effect of oxygen free radicals produced by the Fenton reaction was used to induce oxidation and other structural changes in pregnant mare serum gonadotrophin (PMSG). Modifications in the spectrophotometric scan, an increase in exposed carbonyl groups, and the ability to reduce nitroblue tetrazolium, was achieved by the oxidized hormone when compared to the control PMSG. PMSG loses its biological activity when coming in contact with the free-radical generating system. This lack of activity is manifested as a loss of ovulation and a decrease in the weight of the ovaries and uterus. It was demonstrated that oxygen free radicals can induce structural and biological changes in the gonadotrophin.

  6. Altered structural connectivity of cortico-striato-pallido-thalamic networks in Gilles de la Tourette syndrome.

    PubMed

    Worbe, Yulia; Marrakchi-Kacem, Linda; Lecomte, Sophie; Valabregue, Romain; Poupon, Fabrice; Guevara, Pamela; Tucholka, Alan; Mangin, Jean-François; Vidailhet, Marie; Lehericy, Stephane; Hartmann, Andreas; Poupon, Cyril

    2015-02-01

    Gilles de la Tourette syndrome is a childhood-onset syndrome characterized by the presence and persistence of motor and vocal tics. A dysfunction of cortico-striato-pallido-thalamo-cortical networks in this syndrome has been supported by convergent data from neuro-pathological, electrophysiological as well as structural and functional neuroimaging studies. Here, we addressed the question of structural integration of cortico-striato-pallido-thalamo-cortical networks in Gilles de la Tourette syndrome. We specifically tested the hypothesis that deviant brain development in Gilles de la Tourette syndrome could affect structural connectivity within the input and output basal ganglia structures and thalamus. To this aim, we acquired data on 49 adult patients and 28 gender and age-matched control subjects on a 3 T magnetic resonance imaging scanner. We used and further implemented streamline probabilistic tractography algorithms that allowed us to quantify the structural integration of cortico-striato-pallido-thalamo-cortical networks. To further investigate the microstructure of white matter in patients with Gilles de la Tourette syndrome, we also evaluated fractional anisotropy and radial diffusivity in these pathways, which are both sensitive to axonal package and to myelin ensheathment. In patients with Gilles de la Tourette syndrome compared to control subjects, we found white matter abnormalities in neuronal pathways connecting the cerebral cortex, the basal ganglia and the thalamus. Specifically, striatum and thalamus had abnormally enhanced structural connectivity with primary motor and sensory cortices, as well as paracentral lobule, supplementary motor area and parietal cortices. This enhanced connectivity of motor cortex positively correlated with severity of tics measured by the Yale Global Tics Severity Scale and was not influenced by current medication status, age or gender of patients. Independently of the severity of tics, lateral and medial orbito

  7. Fibronectin alters the rate of formation and structure of the fibrin matrix.

    PubMed

    Ramanathan, Anand; Karuri, Nancy

    2014-01-10

    Plasma fibronectin is a vital component of the fibrin clot; however its role on clot structure is not clearly understood. The goal of this study was to examine the influence of fibronectin on the kinetics of formation, structural characteristics and composition of reconstituted fibrin clots or fibrin matrices. Fibrin matrices were formed by adding thrombin to 1, 2 or 4 mg/ml fibrinogen supplemented with 0-0.4 mg/ml fibronectin. The rate of fibrin matrix formation was then monitored by measuring light absorbance properties at different time points. Confocal microscopy of fluorescein conjugated fibrinogen was used to visualize the structural characteristics of fibrin matrices. The amount of fibronectin in fibrin matrices was determined through electrophoresis and immunoblotting of solubilized matrices. Fibronectin concentration positively correlated with the initial rate of fibrin matrix formation and with steady state light absorbance values of fibrin matrices. An increase in fibronectin concentration resulted in thinner and denser fibers in the fibrin matrices. Electrophoresis and immunoblotting showed that fibronectin was covalently and non-covalently bound to fibrin matrices and in the form of high molecular weight multimers. The formation of fibronectin multimers was attributed to cross-linking of fibronectin by trace amounts Factor XIIIa. These findings are novel because they link results from light absorbance studies to microcopy analyses and demonstrate an influence of fibronectin on fibrin matrix structural characteristics. This data is important in developing therapies that destabilize fibrin clots.

  8. Alteration of hepatic structure and oxidative stress induced by intravenous nanoceria

    SciTech Connect

    Tseng, Michael T.; Lu, Xiaoqin; Duan, Xiaoxian; Hardas, Sarita S.; Sultana, Rukhsana; Wu, Peng; Unrine, Jason M.; Graham, Uschi; Butterfield, D. Allan; Grulke, Eric A.; Yokel, Robert A.

    2012-04-15

    Beyond the traditional use of ceria as an abrasive, the scope of nanoceria applications now extends into fuel cell manufacturing, diesel fuel additives, and for therapeutic intervention as a putative antioxidant. However, the biological effects of nanoceria exposure have yet to be fully defined, which gave us the impetus to examine its systemic biodistribution and biological responses. An extensively characterized nanoceria (5 nm) dispersion was vascularly infused into rats, which were terminated 1 h, 20 h or 30 days later. Light and electron microscopic tissue characterization was conducted and hepatic oxidative stress parameters determined. We observed acute ceria nanoparticle sequestration by Kupffer cells with subsequent bioretention in parenchymal cells as well. The internalized ceria nanoparticles appeared as spherical agglomerates of varying dimension without specific organelle penetration. In hepatocytes, the agglomerated nanoceria frequently localized to the plasma membrane facing bile canaliculi. Hepatic stellate cells also sequestered nanoceria. Within the sinusoids, sustained nanoceria bioretention was associated with granuloma formations comprised of Kupffer cells and intermingling CD3{sup +} T cells. A statistically significant elevation of serum aspartate aminotransferase (AST) level was seen at 1 and 20 h, but subsided by 30 days after ceria administration. Further, elevated apoptosis was observed on day 30. These findings, together with increased hepatic protein carbonyl levels on day 30, indicate ceria-induced hepatic injury and oxidative stress, respectively. Such observations suggest a single vascular infusion of nanoceria can lead to persistent hepatic retention of particles with possible implications for occupational and therapeutic exposures. -- Highlights: ► Time course study on nanoceria induced hepatic alterations in rats. ► Serum AST elevation indicated acute hepatotoxicity. ► Ceria is retained for up to 30 days in Kupffer cells

  9. Helminth infection alters IgE responses to allergens structurally related to parasite proteins.

    PubMed

    Santiago, Helton da Costa; Ribeiro-Gomes, Flávia L; Bennuru, Sasisekhar; Nutman, Thomas B

    2015-01-01

    Immunological cross-reactivity between environmental allergens and helminth proteins has been demonstrated, although the clinically related implications of this cross-reactivity have not been addressed. To investigate the impact of molecular similarity among allergens and cross-reactive homologous helminth proteins in IgE-based serologic assessment of allergic disorders in a helminth-infected population, we performed ImmunoCAP tests in filarial-infected and noninfected individuals for IgE measurements to allergen extracts that contained proteins with high levels of homology with helminth proteins as well as IgE against representative recombinant allergens with and without helminth homologs. The impact of helminth infection on the levels and function of the IgE to these specific homologous and nonhomologous allergens was corroborated in an animal model. We found that having a tissue-invasive filarial infection increased the serological prevalence of ImmunoCAP-identified IgE directed against house dust mite and cockroach, but not against timothy grass, the latter with few allergens with homologs in helminth infection. IgE ELISA confirmed that filaria-infected individuals had higher IgE prevalences to those recombinant allergens that had homologs in helminths. Mice infected with the helminth Heligmosomoides polygyrus displayed increased levels of IgE and positive skin tests to allergens with homologs in the parasite. These results show that cross-reactivity among allergens and helminth proteins can have practical implications, altering serologic approaches to allergen testing and bringing a new perspective to the "hygiene hypothesis."

  10. Alterations in gill structure in tropical reef fishes as a result of elevated temperatures

    PubMed Central

    Bowden, A.J.; Gardiner, N.M.; Couturier, C.S.; Stecyk, J.A.W.; Nilsson, G.E.; Munday, P.L.; Rummer, J.L.

    2015-01-01

    Tropical regions are expected to be some of the most affected by rising sea surface temperatures (SSTs) because seasonal temperature variations are minimal. As temperatures rise, less oxygen dissolves in water, but metabolic requirements of fish and thus, the demand for effective oxygen uptake, increases. Gill remodelling is an acclimation strategy well documented in freshwater cyprinids experiencing large seasonal variations in temperature and oxygen as well as an amphibious killifish upon air exposure. However, no study has investigated whether tropical reef fishes remodel their gills to allow for increased oxygen demands at elevated temperatures. We tested for gill remodelling in five coral reef species (Acanthochromis polyacanthus, Chromis atripectoralis, Pomacentrus moluccensis, Dascyllus melanurus and Cheilodipterus quinquelineatus) from populations in northern Papua New Guinea (2° 35.765′ S; 150° 46.193′ E). Fishes were acclimated for 12-14 days to 29 and 31 °C, encompassing their seasonal range (29-31 °C), and 33 and 34 °C to account for end-of-century predicted temperatures. We measured lamellar perimeter, cross-sectional area, base thickness, and length for five filaments on the 2nd gill arches and qualitatively assessed 3rd gill arches via scanning electron microscopy (SEM). All species exhibited significant differences in the quantitative measurements made on the lamellae, but no consistent trends with temperature were observed. SEM only revealed alterations in gill morphology in P. moluccensis. The overall lack of changes in gill morphology with increasing temperature suggests that these near-equatorial reef fishes may fail to maintain adequate O2 uptake under future climate scenarios unless other adaptive mechanisms are employed. PMID:24862962

  11. Sit-to-Stand and Stand-to-Sit Control Mechanisms of Two-Wheeled Wheelchair.

    PubMed

    Abdul Ghani, N M; Tokhi, M O

    2016-04-01

    This paper presents a mechanism for standing and sitting transformation of a wheelchair using a two-wheeled inverted pendulum concept with reduced torque requirement, in simulation studies. The motivation of this work is to design a compact standing mechanism to help an elderly/disabled person with functional limitation in lower extremities to maneuver in small and confined spaces and enable them to perform standard daily life routines independently. The wheelchair system at the upright standing position is tested with different travel distances, and the challenge is to control both sit-to-stand and stand-to-sit operations in a stable manner using flexible-joint humanoid. An additional spring/damping element is incorporated at each wheel to provide a comfortable ride for the user especially during stand-to-sit transformation task. A PD-fuzzy control with modular structure is implemented, and the performance of the system is observed through visual nastran 4d (vn4d) visualization software and simulation in matlab. The stand-to-sit performance tests have shown more than 38% reduction in tilt and back seat angles fluctuation in linear travel motion using a suspension system, while the initial tilt torque needed is 50% less than the amount required in previous designs.

  12. Multiple Meningioma in a Patient of Bipolar Disorder: The Dilemma of Detecting Structural Brain Lesions in the Backdrop of a Long Standing Psychiatric Illness

    PubMed Central

    Sood, Mamta; Khandelwal, Sudhir Kumar

    2016-01-01

    Multiple meningioma often can be clinically silent and may present with only psychiatric symptoms. We report a case of 43-year-old, right handed woman with a 23 year history of long standing bipolar affective disorder, who presented with a mixed episode with psychotic symptoms which did not respond to usual treatment and was further complicated with a different set of symptomatology. MRI brain revealed multiple dural based mass lesions identified to be multiple meningiomas. Patient’s symptoms improved after gamma knife stereotactic radiosurgery for the multiple meningioma. Our finding illustrates the need to assess for brain lesions in presence of atypical symptoms, along with unresponsiveness to traditional management with psychotropic medications in patients with bipolar affective disorders. PMID:27656537

  13. Automated measurement of lysosomal structure alterations in oocytes of mussels exposed to petroleum hydrocarbons.

    PubMed

    Cajaraville, M P; Marigómez, J A; Angulo, E

    1991-09-01

    The present study examines the structure of the lysosomal system of mature oocytes in mussels, Mytilus galloprovincialis, after a 21 day exposure to the water accommodated fraction (WAF) of two crude oils (types Ural and Maya) and of a commercial lubricant oil. The automated image analysis indicates that lysosomes, showing cytochemically demonstrable beta-glucuronidase activity, are smaller and much more numerous in oocytes of mussels treated with a 40% dose of Ural- and Lubricant-WAF when compared to controls. It is suggested that the structure of the lysosomal system of oocytes is different from that of somatic cells (i.e., digestive cells) and that budding or "fission" into smaller bodies occurs in oocyte lysosomes under certain petroleum hydrocarbon-exposure conditions. These changes in the lysosomal compartment appear to be associated to the process of gamete release or spawning.

  14. Potential Activity, Size, and Structure of Sulfate-Reducing Microbial Communities in an Exposed, Grazed and a Sheltered, Non-Grazed Mangrove Stand at the Red Sea Coast

    PubMed Central

    Balk, Melike; Keuskamp, Joost A.; Laanbroek, Hendrikus J.

    2015-01-01

    After oxygen, sulfate is the most important oxidant for the oxidation of organic matter in mangrove forest soils. As sulfate reducers are poor competitors for common electron donors, their relative success depends mostly on the surplus of carbon that is left by aerobic organisms due to oxygen depletion. We therefore hypothesized that sulfate-cycling in mangrove soils is influenced by the size of net primary production, and hence negatively affected by mangrove degradation and exploitation, as well as by carbon-exporting waves. To test this, we compared quantitative and qualitative traits of sulfate-reducing communities in two Saudi-Arabian mangrove stands near Jeddah, where co-occurring differences in camel-grazing pressure and tidal exposure led to a markedly different stand height and hence primary production. Potential sulfate reduction rates measured in anoxic flow-through reactors in the absence and presence of additional carbon sources were significantly higher in the samples from the non-grazed site. Near the surface (0–2 cm depth), numbers of dsrB gene copies and culturable cells also tended to be higher in the non-grazed sites, while these differences were not detected in the sub-surface (4–6 cm depth). It was concluded that sulfate-reducing microbes at the surface were indeed repressed at the low-productive site as could be expected from our hypothesis. At both sites, sulfate reduction rates as well as numbers of the dsrB gene copies and viable cells increased with depth suggesting repression of sulfate reduction near the surface in both irrespective of production level. Additionally, sequence analysis of DNA bands obtained from DGGE gels based on the dsrB gene, showed a clear difference in dominance of sulfate-reducing genera belonging to the Deltaproteobacteria and the Firmicutes between sampling sites and depths. PMID:26733999

  15. Wildfires alter rodent community structure across four vegetation types in southern California, USA

    USGS Publications Warehouse

    Brehme, Cheryl S.; Clark, Denise R.; Rochester, Carlton J.; Fisher, Robert N.

    2011-01-01

    We surveyed burned and unburned plots across four habitat reserves in San Diego County, California, USA, in 2005 and 2006, to assess the effects of the 2003 wildfires on the community structure and relative abundance of rodent species. The reserves each contained multiple vegetation types (coastal sage scrub, chaparral, woodland, and grassland) and spanned from 250 m to 1078 m in elevation. Multivariate analyses revealed a more simplified rodent community structure in all burned habitats in comparison to unburned habitats. Reduction in shrub and tree cover was highly predictive of changes in post-fire rodent community structure in the burned coastal sage scrub and chaparral habitats. Reduction in cover was not predictive for the less substantially burned woodlands and grasslands, for which we hypothesized that interspecific competition played a greater role in post-fire community structure. Across vegetation types, generalists and open habitat specialists typically increased in relative abundance, whereas closed habitat specialists decreased. We documented significant increases in relative abundance of the deer mouse (Peromyscus maniculatus Wagner) and Dulzura kangaroo rat (Dipodomys simulans Merriam). In contrast, we found significant decreases in relative abundance for the California mouse (Peromyscus californicus Gambel), San Diego pocket mouse (Chaetodipus fallax Merriam), desert woodrat (Neotoma lepida Thomas), and brush mouse (Peromyscus boylii Baird). Currently, our research program involves assessment of whether habitat conservation plans (HCPs) in southern California provide long-term protection to HCP covered species, as well as preserve ecosystem function. The scenario of increased wildfires needs to be incorporated into this assessment. We discuss our results in relation to management and conservation planning under a future scenario of larger and more frequent wildfires in southern California.

  16. Deamidation alters the structure and decreases the stability of human lens betaA3-crystallin.

    PubMed

    Takata, Takumi; Oxford, Julie T; Brandon, Theodore R; Lampi, Kirsten J

    2007-07-31

    According to the World Health Organization, cataracts account for half of the blindness in the world, with the majority occurring in developing countries. A cataract is a clouding of the lens of the eye due to light scattering of precipitated lens proteins or aberrant cellular debris. The major proteins in the lens are crystallins, and they are extensively deamidated during aging and cataracts. Deamidation has been detected at the domain and monomer interfaces of several crystallins during aging. The purpose of this study was to determine the effects of two potential deamidation sites at the predicted interface of the betaA3-crystallin dimer on its structure and stability. The glutamine residues at the reported in vivo deamidation sites of Q180 in the C-terminal domain and at the homologous site Q85 in the N-terminal domain were substituted with glutamic acid residues by site-directed mutagenesis. Far-UV and near-UV circular dichroism spectroscopy indicated that there were subtle differences in the secondary structure and more notable differences in the tertiary structure of the mutant proteins compared to that of the wild type betaA3-crystallin. The Q85E/Q180E mutant also was more susceptible to enzymatic digestion, suggesting increased solvent accessibility. These structural changes in the deamidated mutants led to decreased stability during unfolding in urea and increased precipitation during heat denaturation. When simulating deamidation at both residues, there was a further decrease in stability and loss of cooperativity. However, multiangle-light scattering and quasi-elastic light scattering experiments showed that dimer formation was not disrupted, nor did higher-order oligomers form. These results suggest that introducing charges at the predicted domain interface in the betaA3 homodimer may contribute to the insolubilization of lens crystallins or favor other, more stable, crystallin subunit interactions.

  17. Altered Trabecular Bone Structure and Delayed Cartilage Degeneration in the Knees of Collagen VI Null Mice

    PubMed Central

    Christensen, Susan E.; Coles, Jeffrey M.; Zelenski, Nicole A.; Furman, Bridgette D.; Leddy, Holly A.; Zauscher, Stefan; Bonaldo, Paolo; Guilak, Farshid

    2012-01-01

    Mutation or loss of collagen VI has been linked to a variety of musculoskeletal abnormalities, particularly muscular dystrophies, tissue ossification and/or fibrosis, and hip osteoarthritis. However, the role of collagen VI in bone and cartilage structure and function in the knee is unknown. In this study, we examined the role of collagen VI in the morphology and physical properties of bone and cartilage in the knee joint of Col6a1−/− mice by micro-computed tomography (microCT), histology, atomic force microscopy (AFM), and scanning microphotolysis (SCAMP). Col6a1−/− mice showed significant differences in trabecular bone structure, with lower bone volume, connectivity density, trabecular number, and trabecular thickness but higher structure model index and trabecular separation compared to Col6a1+/+ mice. Subchondral bone thickness and mineral content increased significantly with age in Col6a1+/+ mice, but not in Col6a1−/− mice. Col6a1−/− mice had lower cartilage degradation scores, but developed early, severe osteophytes compared to Col6a1+/+mice. In both groups, cartilage roughness increased with age, but neither the frictional coefficient nor compressive modulus of the cartilage changed with age or genotype, as measured by AFM. Cartilage diffusivity, measured via SCAMP, varied minimally with age or genotype. The absence of type VI collagen has profound effects on knee joint structure and morphometry, yet minimal influences on the physical properties of the cartilage. Together with previous studies showing accelerated hip osteoarthritis in Col6a1−/− mice, these findings suggest different roles for collagen VI at different sites in the body, consistent with clinical data. PMID:22448243

  18. Physical disturbance to ecological niches created by soil structure alters community composition of methanotrophs.

    PubMed

    Kumaresan, Deepak; Stralis-Pavese, Nancy; Abell, Guy C J; Bodrossy, Levente; Murrell, J Colin

    2011-10-01

    Aggregates of different sizes and stability in soil create a composite of ecological niches differing in terms of physico-chemical and structural characteristics. The aim of this study was to identify, using DNA-SIP and mRNA-based microarray analysis, whether shifts in activity and community composition of methanotrophs occur when ecological niches created by soil structure are physically perturbed. Landfill cover soil was subject to three treatments termed: 'control' (minimal structural disruption), 'sieved' (sieved soil using 2 mm mesh) and 'ground' (grinding using mortar and pestle). 'Sieved' and 'ground' soil treatments exhibited higher methane oxidation potentials compared with the 'control' soil treatment. Analysis of the active community composition revealed an effect of physical disruption on active methanotrophs. Type I methanotrophs were the most active methanotrophs in 'sieved' and 'ground' soil treatments, whereas both Type I and Type II methanotrophs were active in the 'control' soil treatment. The result emphasize that changes to a particular ecological niche may not result in an immediate change to the active bacterial composition and change in composition will depend on the ability of the bacterial communities to respond to the perturbation.

  19. The N(2)-Furfuryl-deoxyguanosine Adduct Does Not Alter the Structure of B-DNA.

    PubMed

    Ghodke, Pratibha P; Gore, Kiran R; Harikrishna, S; Samanta, Biswajit; Kottur, Jithesh; Nair, Deepak T; Pradeepkumar, P I

    2016-01-15

    N(2)-Furfuryl-deoxyguanosine (fdG) is carcinogenic DNA adduct that originates from furfuryl alcohol. It is also a stable structural mimic of the damage induced by the nitrofurazone family of antibiotics. For the structural and functional studies of this model N(2)-dG adduct, reliable and rapid access to fdG-modified DNAs are warranted. Toward this end, here we report the synthesis of fdG-modified DNAs using phosphoramidite chemistry involving only three steps. The functional integrity of the modified DNA has been verified by primer extension studies with DNA polymerases I and IV from E. coli. Introduction of fdG into a DNA duplex decreases the Tm by ∼1.6 °C/modification. Molecular dynamics simulations of a DNA duplex bearing the fdG adduct revealed that though the overall B-DNA structure is maintained, this lesion can disrupt W-C H-bonding, stacking interactions, and minor groove hydrations to some extent at the modified site, and these effects lead to slight variations in the local base pair parameters. Overall, our studies show that fdG is tolerated at the minor groove of the DNA to a better extent compared with other bulky DNA damages, and this property will make it difficult for the DNA repair pathways to detect this adduct.

  20. Alteration of citrine structure by hydrostatic pressure explains the accompanying spectral shift

    PubMed Central

    Barstow, Buz; Ando, Nozomi; Kim, Chae Un; Gruner, Sol M.

    2008-01-01

    A protein molecule is an intricate system whose function is highly sensitive to small external perturbations. However, no examples that correlate protein function with progressive subangstrom structural perturbations have thus far been presented. To elucidate this relationship, we have investigated a fluorescent protein, citrine, as a model system under high-pressure perturbation. The protein has been compressed to produce deformations of its chromophore by applying a high-pressure cryocooling technique. A closely spaced series of x-ray crystallographic structures reveals that the chromophore undergoes a progressive deformation of up to 0.8 Å at an applied pressure of 500 MPa. It is experimentally demonstrated that the structural motion is directly correlated with the progressive fluorescence shift of citrine from yellow to green under these conditions. This protein is therefore highly sensitive to subangstrom deformations and its function must be understood at the subangstrom level. These results have significant implications for protein function prediction and biomolecule design and engineering, because they suggest methods to tune protein function by modification of the protein scaffold. PMID:18768811

  1. Structure-Based Alteration of Substrate Specificity and Catalytic Activity of Sulfite Oxidase from Sulfite Oxidation to Nitrate Reduction

    SciTech Connect

    Qiu, James A.; Wilson, Heather L.; Rajagopalan, K.V.

    2012-04-18

    Eukaryotic sulfite oxidase is a dimeric protein that contains the molybdenum cofactor and catalyzes the metabolically essential conversion of sulfite to sulfate as the terminal step in the metabolism of cysteine and methionine. Nitrate reductase is an evolutionarily related molybdoprotein in lower organisms that is essential for growth on nitrate. In this study, we describe human and chicken sulfite oxidase variants in which the active site has been modified to alter substrate specificity and activity from sulfite oxidation to nitrate reduction. On the basis of sequence alignments and the known crystal structure of chicken sulfite oxidase, two residues are conserved in nitrate reductases that align with residues in the active site of sulfite oxidase. On the basis of the crystal structure of yeast nitrate reductase, both positions were mutated in human sulfite oxidase and chicken sulfite oxidase. The resulting double-mutant variants demonstrated a marked decrease in sulfite oxidase activity but gained nitrate reductase activity. An additional methionine residue in the active site was proposed to be important in nitrate catalysis, and therefore, the triple variant was also produced. The nitrate reducing ability of the human sulfite oxidase triple mutant was nearly 3-fold greater than that of the double mutant. To obtain detailed structural data for the active site of these variants, we introduced the analogous mutations into chicken sulfite oxidase to perform crystallographic analysis. The crystal structures of the Mo domains of the double and triple mutants were determined to 2.4 and 2.1 {angstrom} resolution, respectively.

  2. Vestibular dysfunction, altered macular structure and trait localization in A/J inbred mice.

    PubMed

    Vijayakumar, Sarath; Lever, Teresa E; Pierce, Jessica; Zhao, Xing; Bergstrom, David; Lundberg, Yunxia Wang; Jones, Timothy A; Jones, Sherri M

    2015-04-01

    A/J mice develop progressive hearing loss that begins before 1 month of age and is attributed to cochlear hair cell degeneration. Screening tests indicated that this strain also develops early onset vestibular dysfunction and has otoconial deficits. The purpose of this study was to characterize the vestibular dysfunction and macular structural pathology over the lifespan of A/J mice. Vestibular function was measured using linear vestibular evoked potentials (VsEPs). Macular structural pathology was evaluated using light microscopy, scanning electron microscopy, transmission electron microscopy, confocal microscopy and Western blotting. Individually, vestibular functional deficits in mice ranged from mild to profound. On average, A/J mice had significantly reduced vestibular sensitivity (elevated VsEP response thresholds and smaller amplitudes), whereas VsEP onset latency was prolonged compared to age-matched controls (C57BL/6). A limited age-related vestibular functional loss was also present. Structural analysis identified marked age-independent otoconial abnormalities in concert with some stereociliary bundle defects. Macular epithelia were incompletely covered by otoconial membranes with significantly reduced opacity and often contained abnormally large or giant otoconia as well as normal-appearing otoconia. Elevated expression of key otoconins (i.e., otoconin 90, otolin and keratin sulfate proteoglycan) ruled out the possibility of reduced levels contributing to otoconial dysgenesis. The phenotype of A/J was partially replicated in a consomic mouse strain (C57BL/6J-Chr 17(A/J)/NaJ), thus indicating that Chr 17(A/J) contained a trait locus for a new gene variant responsible to some extent for the A/J vestibular phenotype. Quantitative trait locus analysis identified additional epistatic influences associated with chromosomes 1, 4, 9 and X. Results indicate that the A/J phenotype represents a complex trait, and the A/J mouse strain presents a new model for the

  3. Altered Wiring of the Human Structural Connectome in Adults with Mild Traumatic Brain Injury.

    PubMed

    van der Horn, Harm Jan; Kok, Jelmer G; de Koning, Myrthe E; Scheenen, Myrthe E; Leemans, Alexander; Spikman, Jacoba M; van der Naalt, Joukje

    2017-03-01

    In this study, structural connectivity after mild traumatic brain injury (mTBI) was examined from a network perspective, with a particular focus on post-traumatic complaints. Fifty-three patients with and without self-reported complaints at 2 weeks after uncomplicated mTBI were included, in addition to 20 matched healthy controls. Diffusion weighted imaging was performed at 4 weeks post-injury, and neuropsychological tests measuring processing speed and verbal memory were administered at 3 months post-injury to determine cognitive outcome. Structural connectivity was investigated using whole brain tractography and subsequent graph theory analysis. In patients with mTBI, eigenvector centrality within the left temporal pole was lower than in healthy controls. In patients without complaints, global and mean local efficiency were lower than in patients with complaints, although no differences were found between either subgroup and the group of healthy controls. Neuropsychological test scores were similar for patients with mTBI and healthy controls. However, patients with complaints showed higher processing speed than patients without complaints. Within the total mTBI group, a trend was found toward a correlation between lower network clustering and higher processing speed. Additionally, significant correlations were found between higher betweenness centrality values of language areas and lower verbal memory scores in patients with mTBI. In conclusion, our findings may indicate that global graph measures of the structural connectome are associated with pre- and/or non-injury-related factors that determine the susceptibility to developing (persistent) complaints after mTBI. Further, correlations between graph measures and neuropsychological test scores could suggest early compensatory mechanisms to maintain adequate cognitive performance.

  4. Disturbance alters the phylogenetic composition and structure of plant communities in an old field system.

    PubMed

    Dinnage, Russell

    2009-09-18

    The changes in phylogenetic composition and structure of communities during succession following disturbance can give us insights into the forces that are shaping communities over time. In abandoned agricultural fields, community composition changes rapidly when a field is plowed, and is thought to reflect a relaxation of competition due to the elimination of dominant species which take time to re-establish. Competition can drive phylogenetic overdispersion, due to phylogenetic conservation of 'niche' traits that allow species to partition resources. Therefore, undisturbed old field communities should exhibit higher phylogenetic dispersion than recently disturbed systems, which should be relatively 'clustered' with respect to phylogenetic relationships. Several measures of phylogenetic structure between plant communities were measured in recently plowed areas and nearby 'undisturbed' sites. There was no difference in the absolute values of these measures between disturbed and 'undisturbed' sites. However, there was a difference in the 'expected' phylogenetic structure between habitats, leading to significantly lower than expected phylogenetic diversity in disturbed plots, and no difference from random expectation in 'undisturbed' plots. This suggests that plant species characteristic of each habitat are fairly evenly distributed on the shared species pool phylogeny, but that once the initial sorting of species into the two habitat types has occurred, the processes operating on them affect each habitat differently. These results were consistent with an analysis of correlation between phylogenetic distance and co-occurrence indices of species pairs in the two habitat types. This study supports the notion that disturbed plots are more clustered than expected, rather than 'undisturbed' plots being more overdispersed, suggesting that disturbed plant communities are being more strongly influenced by environmental filtering of conserved niche traits.

  5. Structural alteration of cofactor specificity in Corynebacterium 2,5-diketo-D-gluconic acid reductase

    PubMed Central

    Sanli, Gulsah; Banta, Scott; Anderson, Stephen; Blaber, Michael

    2004-01-01

    Corynebacterium 2,5-Diketo-D-gluconic acid reductase (2,5-DKGR) catalyzes the reduction of 2,5-diketo-D-gluconic acid (2,5-DKG) to 2-Keto-L-gulonic acid (2-KLG). 2-KLG is an immediate precursor to L-ascorbic acid (vitamin C), and 2,5-DKGR is, therefore, an important enzyme in a novel industrial method for the production of vitamin C. 2,5-DKGR, as with most other members of the aldo-keto reductase (AKR) superfamily, exhibits a preference for NADPH compared to NADH as a cofactor in the stereo-specific reduction of substrate. The application of 2,5-DKGR in the industrial production of vitamin C would be greatly enhanced if NADH could be efficiently utilized as a cofactor. A mutant form of 2,5-DKGR has previously been identified that exhibits two orders of magnitude higher activity with NADH in comparison to the wild-type enzyme, while retaining a high level of activity with NADPH. We report here an X-ray crystal structure of the holo form of this mutant in complex with NADH cofactor, as well as thermodynamic stability data. By comparing the results to our previously reported X-ray structure of the holo form of wild-type 2,5-DKGR in complex with NADPH, the structural basis of the differential NAD(P)H selectivity of wild-type and mutant 2,5-DKGR enzymes has been identified. PMID:14718658

  6. Wheat and Rice Growth Stages and Fertilization Regimes Alter Soil Bacterial Community Structure, But Not Diversity.

    PubMed

    Wang, Jichen; Xue, Chao; Song, Yang; Wang, Lei; Huang, Qiwei; Shen, Qirong

    2016-01-01

    Maintaining soil fertility and the microbial communities that determine fertility is critical to sustainable agricultural strategies, and the use of different organic fertilizer (OF) regimes represents an important practice in attempts to preserve soil quality. However, little is known about the dynamic response of bacterial communities to fertilization regimes across crop growth stages. In this study, we examined microbial community structure and diversity across eight representative growth stages of wheat-rice rotation under four different fertilization treatments: no nitrogen fertilizer (NNF), chemical fertilizer (CF), organic-inorganic mixed fertilizer (OIMF), and OF. Quantitative PCR (QPCR) and high-throughput sequencing of bacterial 16S rRNA gene fragments revealed that growth stage as the best predictor of bacterial community abundance and structure. Additionally, bacterial community compositions differed between wheat and rice rotations. Relative to soils under wheat rotation, soils under rice rotation contained higher relative abundances (RA) of anaerobic and mesophilic microbes and lower RA of aerophilic microbes. With respect to fertilization regime, NNF plots had a higher abundance of nitrogen-fixing Cyanobacteria. OIMF had a lower abundance of ammonia-oxidizing Thaumarchaeota compared with CF. Application of chemical fertilizers (CF and OIMF treatments) significantly increased the abundance of some generally oligotrophic bacteria such those belonging to the Acidobacteria, while more copiotrophic of the phylum Proteobacteria increased with OF application. A high correlation coefficient was found when comparing RA of Acidobacteria based upon QPCR vs. sequence analysis, yet poor correlations were found for the α- and β- Proteobacteria, highlighting the caution required when interpreting these molecular data. In total, crop, fertilization scheme and plant developmental stage all influenced soil microbial community structure, but not total levels of alpha

  7. Wheat and Rice Growth Stages and Fertilization Regimes Alter Soil Bacterial Community Structure, But Not Diversity

    PubMed Central

    Wang, Jichen; Xue, Chao; Song, Yang; Wang, Lei; Huang, Qiwei; Shen, Qirong

    2016-01-01

    Maintaining soil fertility and the microbial communities that determine fertility is critical to sustainable agricultural strategies, and the use of different organic fertilizer (OF) regimes represents an important practice in attempts to preserve soil quality. However, little is known about the dynamic response of bacterial communities to fertilization regimes across crop growth stages. In this study, we examined microbial community structure and diversity across eight representative growth stages of wheat-rice rotation under four different fertilization treatments: no nitrogen fertilizer (NNF), chemical fertilizer (CF), organic–inorganic mixed fertilizer (OIMF), and OF. Quantitative PCR (QPCR) and high-throughput sequencing of bacterial 16S rRNA gene fragments revealed that growth stage as the best predictor of bacterial community abundance and structure. Additionally, bacterial community compositions differed between wheat and rice rotations. Relative to soils under wheat rotation, soils under rice rotation contained higher relative abundances (RA) of anaerobic and mesophilic microbes and lower RA of aerophilic microbes. With respect to fertilization regime, NNF plots had a higher abundance of nitrogen–fixing Cyanobacteria. OIMF had a lower abundance of ammonia-oxidizing Thaumarchaeota compared with CF. Application of chemical fertilizers (CF and OIMF treatments) significantly increased the abundance of some generally oligotrophic bacteria such those belonging to the Acidobacteria, while more copiotrophic of the phylum Proteobacteria increased with OF application. A high correlation coefficient was found when comparing RA of Acidobacteria based upon QPCR vs. sequence analysis, yet poor correlations were found for the α- and β- Proteobacteria, highlighting the caution required when interpreting these molecular data. In total, crop, fertilization scheme and plant developmental stage all influenced soil microbial community structure, but not total levels of

  8. A low-voltage alterable EEPROM with Metal-Oxide-Nitride-Oxide-Semiconductor /MONOS/ structures

    NASA Astrophysics Data System (ADS)

    Suzuki, E.; Ishii, K.; Hayashi, Y.; Hiraishi, H.

    1983-02-01

    Theoretical and experimental investigations to obtain lower voltage Electrically Erasable and Programmable ROM's (EEPROM's) than conventional devices have been performed. The scaled-down Metal-Oxide-Nitride-Oxide semiconductor (MONOS) structure is proposed to realize an extremely low-voltage programmable device. The proposed scaled down MONOS devices enjoy several advantages over MNOS devices, e.g., enlargement of the memory window, elimination of degradation phenomena, and drastic improvement in device yield. Low voltage operation with + or - 6-V supplies is demonstrated by the fabricated scaled down MONOS transistors.

  9. A-3 Test Stand construction update

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The concrete foundation placed Dec. 18 (foreground) for Stennis Space Center's future A-3 Test Stand has almost completely cured by early January, according to Bo Clarke, NASA's contracting officer technical representative for the foundation contract. By late December, construction on foundations for many of the test stand's support structures - diffuser, liquid oxygen, isopropyl alcohol and water tanks and gaseous nitrogen bottle battery - had begun with the installation of (background) `mud slabs.' The slabs provide a working surface for the reinforcing steel and foundation forms.

  10. Gestational exposure to diethylstilbestrol alters cardiac structure/function, protein expression and DNA methylation in adult male mice progeny

    SciTech Connect

    Haddad, Rami; Kasneci, Amanda; Mepham, Kathryn; Sebag, Igal A.; and others

    2013-01-01

    Pregnant women, and thus their fetuses, are exposed to many endocrine disruptor compounds (EDCs). Fetal cardiomyocytes express sex hormone receptors making them potentially susceptible to re-programming by estrogenizing EDCs. Diethylstilbestrol (DES) is a proto-typical, non-steroidal estrogen. We hypothesized that changes in adult cardiac structure/function after gestational exposure to the test compound DES would be a proof in principle for the possibility of estrogenizing environmental EDCs to also alter the fetal heart. Vehicle (peanut oil) or DES (0.1, 1.0 and 10.0 μg/kg/da.) was orally delivered to pregnant C57bl/6n dams on gestation days 11.5–14.5. At 3 months, male progeny were left sedentary or were swim trained for 4 weeks. Echocardiography of isoflurane anesthetized mice revealed similar cardiac structure/function in all sedentary mice, but evidence of systolic dysfunction and increased diastolic relaxation after swim training at higher DES doses. The calcium homeostasis proteins, SERCA2a, phospholamban, phospho-serine 16 phospholamban and calsequestrin 2, are important for cardiac contraction and relaxation. Immunoblot analyses of ventricle homogenates showed increased expression of SERCA2a and calsequestrin 2 in DES mice and greater molecular remodeling of these proteins and phospho-serine 16 phospholamban in swim trained DES mice. DES increased cardiac DNA methyltransferase 3a expression and DNA methylation in the CpG island within the calsequestrin 2 promoter in heart. Thus, gestational DES epigenetically altered ventricular DNA, altered cardiac function and expression, and reduced the ability of adult progeny to cardiac remodel when physically challenged. We conclude that gestational exposure to estrogenizing EDCs may impact cardiac structure/function in adult males. -- Highlights: ► Gestational DES changes cardiac SERCA2a and CASQ2 expression. ► Echocardiography identified systolic dysfunction and increased diastolic relaxation. ► DES

  11. Alcohol dehydrogenase, SDR and MDR structural stages, present update and altered era.

    PubMed

    Jörnvall, Hans; Landreh, Michael; Östberg, Linus J

    2015-06-05

    It is now about half a century since molecular research on alcohol dehydrogenase (ADH), short-chain dehydrogenase/reductase (SDR) and medium-chain dehydrogenase/reductase (MDR) started. During this time, at least four stages of research can be distinguished, which led to many ADH, SDR and MDR structures from which their origins could be traced. An introductory summary of these stages is given, followed by a current update on the now known structures, including the present pattern of mammalian MDR-ADH enzymes into six classes and their evolutionary relationships. In spite of the wide spread in evolutionary changes from the "constant" class III to the more "variable" other classes, the change in class V (only confirmed as a transcript in humans) and class VI (absent in humans) are also restricted. Such spread in variability is visible also in other dehydrogenases, but not always so restricted in other co-evolving proteins we have studied. Finally, the shift in era of present ADH research is highlighted, as well as levels of likely future continuation.

  12. Physiological characterization of an Escherichia coli mutant altered in the structure of murein lipoprotein.

    PubMed Central

    Yem, D W; Wu, H C

    1978-01-01

    Studies using isogenic transductant strains mlpA+ and mlpA as well as reversion analysis suggested that the physiological consequences of a structural gene mutation in murein lipoprotein include (i) increased sensitivity toward chelating agents ethylenediaminetetraacetic acid and ethyleneglycol-bis (beta-aminoethyl ether)-N,N-tetraacetic acid, (ii) leakage of periplasmic enzyme ribonuclease, (iii) weakened association between the outer membrane and the rigid layer accentuated by Mg2+ starvation, resulting in the formation of outer membrane blebs, and (iv) decreased growth rate in media of low ionic strength or low osmolarity. It is suggested that the bound form of lipoprotein plays an important role in the maintenance of the structural integrity of the outer membrane of the Escherichia coli cell envelope. Other outer membrane components may also contribute to the anchorage of outer membrane to the rigid layer, probably through ionic interactions with divalent cations. Using the phenotype of ribonuclease leakage as an unselected marker in a three-factor cross with P1 transduction, we were able to establish the gene order of man mlpA aroD pps on the E. coli chromosome. Images PMID:417067

  13. Alterations in White Matter Structure in Young Children With Type 1 Diabetes

    PubMed Central

    Barnea-Goraly, Naama; Raman, Mira; Mazaika, Paul; Marzelli, Matthew; Hershey, Tamara; Weinzimer, Stuart A.; Aye, Tandy; Buckingham, Bruce; Mauras, Nelly; White, Neil H.; Fox, Larry A.; Tansey, Michael; Beck, Roy W.; Ruedy, Katrina J.; Kollman, Craig; Cheng, Peiyao; Reiss, Allan L.

    2014-01-01

    OBJECTIVE To investigate whether type 1 diabetes affects white matter (WM) structure in a large sample of young children. RESEARCH DESIGN AND METHODS Children (ages 4 to <10 years) with type 1 diabetes (n = 127) and age-matched nondiabetic control subjects (n = 67) had diffusion weighted magnetic resonance imaging scans in this multisite neuroimaging study. Participants with type 1 diabetes were assessed for HbA1c history and lifetime adverse events, and glucose levels were monitored using a continuous glucose monitor (CGM) device and standardized measures of cognition. RESULTS Between-group analysis showed that children with type 1 diabetes had significantly reduced axial diffusivity (AD) in widespread brain regions compared with control subjects. Within the type 1 diabetes group, earlier onset of diabetes was associated with increased radial diffusivity (RD) and longer duration was associated with reduced AD, reduced RD, and increased fractional anisotropy (FA). In addition, HbA1c values were significantly negatively associated with FA values and were positively associated with RD values in widespread brain regions. Significant associations of AD, RD, and FA were found for CGM measures of hyperglycemia and glucose variability but not for hypoglycemia. Finally, we observed a significant association between WM structure and cognitive ability in children with type 1 diabetes but not in control subjects. CONCLUSIONS These results suggest vulnerability of the developing brain in young children to effects of type 1 diabetes associated with chronic hyperglycemia and glucose variability. PMID:24319123

  14. Structure-Guided Engineering of Plant Phytochrome B with Altered Photochemistry and Light Signaling1[W][OA

    PubMed Central

    Zhang, Junrui; Stankey, Robert J.; Vierstra, Richard D.

    2013-01-01

    Phytochromes (phys) encompass a diverse collection of biliproteins that enable cellular light perception by photoconverting between a red-light-absorbing ground state (Pr) and a far-red light-absorbing active state (Pfr). Based on the central role of plant phys in controlling numerous agriculturally important processes, their rational redesign offers great promise toward accelerating crop improvement. Employing as templates the available three-dimensional models of the photosensory module within bacterial phys, we report here our initial attempt to apply structure-guided mutagenesis to phy engineering using Arabidopsis (Arabidopsis thaliana) phyB, the dominant isoform in light-grown plants, as the example. A collection of phyB mutants was generated affecting the bilin-binding pocket that altered photochemistry, thermal stability, and/or nuclear localization patterns, some of which also impacted phenotypic outputs. Of particular interest are the Y361F substitution, which created Arabidopsis plants with greatly enhanced light sensitivity, mutants variably altered in Pfr-to-Pr thermal reversion and nuclear aggregation, and the D307A substitution, which failed to photoconvert from Pr to Pfr and display light-induced nuclear aggregation but retained some biological activity and accelerated turnover in red light. Taken together, this collection provides variants potentially useful to agriculture as well as new tools to better understand the molecular mechanisms underpinning phy signaling. PMID:23321421

  15. Malaria Parasite Proteins and Their Role in Alteration of the Structure and Function of Red Blood Cells.

    PubMed

    Proellocks, Nicholas I; Coppel, Ross L; Mohandas, Narla; Cooke, Brian M

    2016-01-01

    Malaria, caused by Plasmodium spp., continues to be a major threat to human health and a significant cause of socioeconomic hardship in many countries. Almost half of the world's population live in malaria-endemic regions and many of them suffer one or more, often life-threatening episodes of malaria every year, the symptoms of which are attributable to replication of the parasite within red blood cells (RBCs). In the case of Plasmodium falciparum, the species responsible for most malaria-related deaths, parasite replication within RBCs is accompanied by striking alterations to the morphological, biochemical and biophysical properties of the host cell that are essential for the parasites' survival. To achieve this, the parasite establishes a unique and extensive protein export network in the infected RBC, dedicating at least 6% of its genome to the process. Understanding the full gamut of proteins involved in this process and the mechanisms by which P. falciparum alters the structure and function of RBCs is important both for a more complete understanding of the pathogenesis of malaria and for development of new therapeutic strategies to prevent or treat this devastating disease. This review focuses on what is currently known about exported parasite proteins, their interactions with the RBC and their likely pathophysiological consequences.

  16. Fourier analysis of wing beat signals: assessing the effects of genetic alterations of flight muscle structure in Diptera.

    PubMed Central

    Hyatt, C J; Maughan, D W

    1994-01-01

    A method for determining and analyzing the wing beat frequency in Diptera is presented. This method uses an optical tachometer to measure Diptera wing movement during flight. The resulting signal from the optical measurement is analyzed using a Fast Fourier Transform (FFT) technique, and the dominant frequency peak in the Fourier spectrum is selected as the wing beat frequency. Also described is a method for determining quantitatively the degree of variability of the wing beat frequency about the dominant frequency. This method is based on determination of a quantity called the Hindex, which is derived using data from the FFT analysis. Calculation of the H index allows computer-based selection of the most suitable segment of recorded data for determination of the representative wing beat frequency. Experimental data suggest that the H index can also prove useful in examining wing beat frequency variability in Diptera whose flight muscle structure has been genetically altered. Examples from Drosophila indirect flight muscle studies as well as examples of artificial data are presented to illustrate the method. This method fulfills a need for a standardized method for determining wing beat frequencies and examining wing beat frequency variability in insects whose flight muscles have been altered by protein engineering methods. PMID:7811927

  17. Progressive alterations of central nervous system structure and function are caused by charged particle radiation

    NASA Astrophysics Data System (ADS)

    Nelson, G. A.; Cns Nscor Team

    A new NASA-sponsored program project (NSCOR) has been organized to conduct the first comprehensive investigation of the response of a mammalian brain structure (mouse hippocampus) to charged-particle radiation. The NSCOR collaboration has three main goals. The first goal is to quantify the time- and dose-dependent changes in cellular composition and architecture. By using stereology on preserved brains, subsets of cells (neurons, glia, endothelia and stem cells) will be quantified out to 2 years after irradiation with accelerated protons and iron ions. To further characterize changes in vasculature architecture a polymer infusion technique will be used to produce a three-dimensional vasculature cast that then will be mapped by x-ray tomography to determine topological changes, and microscopic infarcts associated with amyloid protein deposits. The 2nd goal is to quantify hippocampal function(s). The primary measurement of function will be extracellular electrical recordings from hippocampal ``brain slices'' that reflect underlying functions such as connectivity, action potential generation & conduction, and neurotransmitter formation, secretion, and uptake. Individual nerve membrane properties will be assessed by ``patch clamp'' recordings. Two non-invasive methods will evaluate brain function and the evolution of changes with time. Electroencephalograms will map macroscopic spontaneous electrical activity while two state-of-the-art MRI magnetization sequences will visualize and quantify local oxygen utilization and white matter fiber tracts structural integrity. To quantify the brains' overall performance under stress, animals will receive a systemic shock mediated by the immune system in the form of a reaction to lipopolysaccharide. A second strategy will employ the APP23 transgenic mouse that develops the pathological changes associated with Alzheimer's disease. Measurements of irradiated mice will determine whether radiation exposure affects the latency and

  18. Microbial functional diversity alters the structure and sensitivity of oxygen deficient zones

    NASA Astrophysics Data System (ADS)

    Penn, Justin; Weber, Thomas; Deutsch, Curtis

    2016-09-01

    Oxygen deficient zones (ODZs) below the ocean surface regulate marine productivity by removing bioavailable nitrogen (N). A complex microbial community mediates N loss, but the interplay of its diverse metabolisms is poorly understood. We present an ecosystem model of the North Pacific ODZ that reproduces observed chemical distributions yet predicts different ODZ structure, rates, and climatic sensitivity compared to traditional geochemical models. An emergent lower O2 limit for aerobic nitrification lies below the upper O2 threshold for anaerobic denitrification, creating a zone of microbial coexistence that causes a larger ODZ but slower total rates of N loss. The O2-dependent competition for the intermediate nitrite produces gradients in its oxidation versus reduction, anammox versus heterotrophic denitrification, and the net ecological stoichiometry of N loss. The latter effect implies that an externally driven ODZ expansion should favor communities that more efficiently remove N, increasing the sensitivity of the N cycle to climate change.

  19. Altered cohesin gene dosage affects Mammalian meiotic chromosome structure and behavior.

    PubMed

    Murdoch, Brenda; Owen, Nichole; Stevense, Michelle; Smith, Helen; Nagaoka, So; Hassold, Terry; McKay, Michael; Xu, Huiling; Fu, Jun; Revenkova, Ekaterina; Jessberger, Rolf; Hunt, Patricia

    2013-01-01

    Based on studies in mice and humans, cohesin loss from chromosomes during the period of protracted meiotic arrest appears to play a major role in chromosome segregation errors during female meiosis. In mice, mutations in meiosis-specific cohesin genes cause meiotic disturbances and infertility. However, the more clinically relevant situation, heterozygosity for mutations in these genes, has not been evaluated. We report here evidence from the mouse that partial loss of gene function for either Smc1b or Rec8 causes perturbations in the formation of the synaptonemal complex (SC) and affects both synapsis and recombination between homologs during meiotic prophase. Importantly, these defects increase the frequency of chromosomally abnormal eggs in the adult female. These findings have important implications for humans: they suggest that women who carry mutations or variants that affect cohesin function have an elevated risk of aneuploid pregnancies and may even be at increased risk of transmitting structural chromosome abnormalities.

  20. Prolonged space flight-induced alterations in the structure and function of human skeletal muscle fibres

    PubMed Central

    Fitts, R H; Trappe, S W; Costill, D L; Gallagher, P M; Creer, A C; Colloton, P A; Peters, J R; Romatowski, J G; Bain, J L; Riley, D A

    2010-01-01

    The primary goal of this study was to determine the effects of prolonged space flight (∼180 days) on the structure and function of slow and fast fibres in human skeletal muscle. Biopsies were obtained from the gastrocnemius and soleus muscles of nine International Space Station crew members ∼45 days pre- and on landing day (R+0) post-flight. The main findings were that prolonged weightlessness produced substantial loss of fibre mass, force and power with the hierarchy of the effects being soleus type I > soleus type II > gastrocnemius type I > gastrocnemius type II. Structurally, the quantitatively most important adaptation was fibre atrophy, which averaged 20% in the soleus type I fibres (98 to 79 μm diameter). Atrophy was the main contributor to the loss of peak force (P0), which for the soleus type I fibre declined 35% from 0.86 to 0.56 mN. The percentage decrease in fibre diameter was correlated with the initial pre-flight fibre size (r = 0.87), inversely with the amount of treadmill running (r = 0.68), and was associated with an increase in thin filament density (r = 0.92). The latter correlated with reduced maximal velocity (V0) (r = −0.51), and is likely to have contributed to the 21 and 18% decline in V0 in the soleus and gastrocnemius type I fibres. Peak power was depressed in all fibre types with the greatest loss (∼55%) in the soleus. An obvious conclusion is that the exercise countermeasures employed were incapable of providing the high intensity needed to adequately protect fibre and muscle mass, and that the crew's ability to perform strenuous exercise might be seriously compromised. Our results highlight the need to study new exercise programmes on the ISS that employ high resistance and contractions over a wide range of motion to mimic the range occurring in Earth's 1 g environment. PMID:20660569

  1. Experimental Diabetes Alters the Morphology and Nano-Structure of the Achilles Tendon

    PubMed Central

    de Oliveira, Rodrigo Ribeiro; Medina de Mattos, Rômulo; Magalhães Rebelo, Luciana; Guimarães Meireles Ferreira, Fernanda; Tovar-Moll, Fernanda; Eurico Nasciutti, Luiz; de Castro Brito, Gerly Anne

    2017-01-01

    Although of several studies that associate chronic hyperglycemia with tendinopathy, the connection between morphometric changes as witnessed by magnetic resonance (MR) images, nanostructural changes, and inflammatory markers have not yet been fully established. Therefore, the present study has as a hypothesis that the Achilles tendons of rats with diabetes mellitus (DM) exhibit structural changes. The animals were randomly divided into two experimental groups: Control Group (n = 06) injected with a vehicle (sodium citrate buffer solution) and Diabetic Group (n = 06) consisting of rats submitted to intraperitoneal administration of streptozotocin. MR was performed 24 days after the induction of diabetes and images were used for morphometry using ImageJ software. Morphology of the collagen fibers within tendons was examined using Atomic Force microscopy (AFM). An increase in the dimension of the coronal plane area was observed in the diabetic group (8.583 ± 0.646 mm2/100g) when compared to the control group (4.823 ± 0.267 mm2/100g) resulting in a significant difference (p = 0.003) upon evaluating the Achilles tendons. Similarly, our analysis found an increase in the size of the transverse section area in the diabetic group (1.328 ± 0.103 mm2/100g) in comparison to the control group (0.940 ± 0.01 mm2/100g) p = 0.021. The tendons of the diabetic group showed great irregularity in fiber bundles, including modified grain direction and jagged junctions and deformities in the form of collagen fibrils bulges. Despite the morphological changes observed in the Achilles tendon of diabetic animals, IL1 and TNF-α did not change. Our results suggest that DM promotes changes to the Achilles tendon with important structural modifications as seen by MR and AFM, excluding major inflammatory changes. PMID:28095484

  2. A Longitudinal Assessment of Structural and Chemical Alterations in Mixed Martial Arts Fighters.

    PubMed

    Mayer, Andrew R; Ling, Josef M; Dodd, Andrew B; Gasparovic, Charles; Klimaj, Stefan D; Meier, Timothy B

    2015-11-15

    Growing evidence suggests that temporally proximal acute concussions and repetitive subconcussive head injuries may lead to long-term neurological deficits. However, the underlying mechanisms of injury and their relative time-scales are not well documented in human injury models. The current study therefore investigated whether biomarkers of brain chemistry (magnetic resonance [MR] spectroscopy: N-acetylaspartate [NAA], combined glutamate and glutamine [Glx], total creatine [Cre], choline compounds [Cho], and myo-inositol [mI]) and structure (cortical thickness, white matter [WM]/subcortical volume) differed between mixed martial artists (MMA; n = 13) and matched healthy controls (HC) without a history of contact sport participation (HC; n = 14). A subset of participants (MMA = 9; HC = 10) returned for follow-up visits, with MMA (n = 3) with clinician-documented acute concussions also scanned serially. As expected, MMA self-reported a higher incidence of previous concussions and significantly more cognitive symptoms during prior concussion recovery. Fighters also exhibited reduced memory and processing speed relative to controls on neuropsychological testing coupled with cortical thinning in the left posterior cingulate gyrus and right occipital cortex at baseline assessment. Over a 1-year follow-up period, MMA experienced a significant decrease in both WM volume and NAA concentration, as well as relative thinning in the left middle and superior frontal gyri. These longitudinal changes did not correlate with self-reported metrics of injury (i.e., fight diary). In contrast, HC did not exhibit significant longitudinal changes over a 4-month follow-up period (p > 0.05). Collectively, current results provide preliminary evidence of progressive changes in brain chemistry and structure over a relatively short time period in individuals with high exposure to repetitive head hits. These findings require replication in independent samples.

  3. The Skinny on Success: Body Mass, Gender and Occupational Standing Across the Life Course

    PubMed Central

    Glass, Christy M.; Haas, Steven A.; Reither, Eric N.

    2010-01-01

    Several studies have analyzed the impact of obesity on occupational standing. This study extends previous research by estimating the influence of body mass on occupational attainment over three decades of the career using data from the Wisconsin Longitudinal Study. In a series of covariance structure analyses, we considered three mechanisms that may alter the career trajectories of heavy individuals: (1. employment-based discrimination, (2. educational attainment, and (3. marriage market processes. Unlike previous studies, we found limited evidence that employment-based discrimination impaired the career trajectories of either men or women. Instead, we found that heavy women received less post-secondary schooling than their thinner peers, which in turn adversely affected their occupational standing at each point in their careers. PMID:20936045

  4. Effect of feet hyperpronation on pelvic alignment in a standing position.

    PubMed

    Khamis, Sam; Yizhar, Ziva

    2007-01-01

    Hyperpronation may cause malalignment of the lower extremity, frequently leading to structural and functional deficits both in standing and walking. Our aim was to study the effect of induced foot hyperpronation on pelvic and lower limb alignment while standing. Thirty-five healthy subjects were requested to remain in a natural standing position for 20s in four different modes: feet flat on the floor, and on wedges angled at 10 degrees, 15 degrees and 20 degrees, designed to induce hyperpronation. Sequencing was random, repeated three times and captured by eight computerized cameras using the VICON three-dimensional motion analysis system. We found that standing on the wedges at various angles, induced hyperpronation, with 41% to 90% of the changes attributable to the intervention. In addition, a statistically significant increase (paired t-test) in internal shank rotation (p<0.0001), internal hip rotation (p<0.0001) and anterior pelvic tilt (p<0.0001) was identified. A strong correlation was found between segmental alignment in every two consecutive modes at all levels (r=0.612-0.985; p<0.0001). These findings suggest that alignment of the lower extremity up to the pelvic girdle, can be altered, due to forces acting on the foot. Interaction between the foot and pelvis occurs in a kinematic chain reaction manner. Although this study was limited to healthy subjects, clinicians should be aware that when addressing pelvis and lower back dysfunction, foot alignment should be examined as a contributing factor.

  5. Study on the Explainable Ability by Using Airborne LIDAR in Stand Value and Stand Competition

    NASA Astrophysics Data System (ADS)

    Huang, S. C.; Yeh, J. Y.; Chen, C. T.; Chen, J. C.

    2016-06-01

    Forest canopy structure is composed by the various species. Sun light is a main factor to affect the crown structures after tree competition. However, thinning operation is an appropriate way to control canopy density, which can adjust the competition conditions in the different crown structures. Recently, Airborne Light Detection and Ranging (LiDAR), has been established as a standard technology for high precision three dimensional forest data acquisition; it could get stand characteristics with three-dimensional information that had develop potential for the structure characteristics of forest canopy. The 65 years old, different planting density of Cryptomeria japonica experiment area was selected for this study in Nanytou, Taiwan. Use the LiDAR image to estimate LiDAR characteristic values by constructed CHM, voxel-based LiDAR, mu0ltiple echoes, and assess the accuracy of stand characteristics with intensity values and field data. The competition index was calculated with field data, and estimate competition index of LiDAR via multiple linear regression. The results showed that the highest accuracy with stand characteristics was stand high which estimate by LiDAR, its average accuracy of 91.03%. LiDAR raster grid size was 20 m × 20 m for the correlation was the best, however, the higher canopy density will reduce the accuracy of the LiDAR characteristic values to estimate the stand characteristics. The significantly affect canopy thickness and the degree of competition in different planting distances.

  6. Low Concentration of Silver Nanoparticles Not Only Enhances the Activity of Horseradish Peroxidase but Alter the Structure Also

    PubMed Central

    Karim, Zoheb; Adnan, Rohana; Ansari, Mohd Saquib

    2012-01-01

    Chemical synthesis of Ag-NPs was carried out using reduction method. The reduction mechanistic approach of silver ions was found to be a basic clue for the formation of the Ag-NPs. The nanoparticles were characterized by UV-vis, FT-IR and TEM analysis. We had designed some experiments in support of our hypothesis, “low concentrations of novel nanoparticles (silver and gold) increases the activity of plant peroxidases and alter their structure also”, we had used Ag-NPs and HRP as models. The immobilization/interaction experiment had demonstrated the specific concentration range of the Ag-NPs and within this range, an increase in HRP activity was reported. At 0.08 mM concentration of Ag-NPs, 50% increase in the activity yield was found. The U.V-vis spectra had demonstrated the increase in the absorbance of HRP within the reported concentration range (0.06–0.12 mM). Above and below this concentration range there was a decrease in the activity of HRP. The results that we had found from the fluorescence spectra were also in favor of our hypothesis. There was a maximum increase in ellipticity and α-helix contents in the presence of 0.08 mM concentration of Ag-NPs, demonstrated by circular dichroism (CD) spectra. Finally, incubation of a plant peroxidase, HRP with Ag-NPs, within the reported concentration range not only enhances the activity but also alter the structure. PMID:22848490

  7. Structure-Guided Mutations in the Terminal Organelle Protein MG491 Cause Major Motility and Morphologic Alterations on Mycoplasma genitalium

    PubMed Central

    Querol, Enrique; Piñol, Jaume; Fita, Ignacio; Calisto, Bárbara M.

    2016-01-01

    The emergent human pathogen Mycoplasma genitalium, with one of the smallest genomes among cells capable of growing in axenic cultures, presents a flask-shaped morphology due to a protrusion of the cell membrane, known as the terminal organelle, that is involved in cell adhesion and motility and is an important virulence factor of this microorganism. The terminal organelle is supported by a cytoskeleton complex of about 300 nm in length that includes three substructures: the terminal button, the rod and the wheel complex. The crystal structure of the MG491 protein, a proposed component of the wheel complex, has been determined at ~3 Å resolution. MG491 subunits are composed of a 60-residue N-terminus, a central three-helix-bundle spanning about 150 residues and a C-terminal region that appears to be quite flexible and contains the region that interacts with MG200, another key protein of the terminal organelle. The MG491 molecule is a tetramer presenting a unique organization as a dimer of asymmetric pairs of subunits. The asymmetric arrangement results in two very different intersubunit interfaces between the central three-helix-bundle domains, which correlates with the formation of only ~50% of the intersubunit disulfide bridges of the single cysteine residue found in MG491 (Cys87). Moreover, M. genitalium cells with a point mutation in the MG491 gene causing the change of Cys87 to Ser present a drastic reduction in motility (as determined by microcinematography) and important alterations in morphology (as determined by electron microscopy), while preserving normal levels of the terminal organelle proteins. Other variants of MG491, designed also according to the structural information, altered significantly the motility and/or the cell morphology. Together, these results indicate that MG491 plays a key role in the functioning, organization and stabilization of the terminal organelle. PMID:27082435

  8. Early alterations in functional connectivity and white matter structure in a transgenic mouse model of cerebral amyloidosis.

    PubMed

    Grandjean, Joanes; Schroeter, Aileen; He, Pan; Tanadini, Matteo; Keist, Ruth; Krstic, Dimitrije; Konietzko, Uwe; Klohs, Jan; Nitsch, Roger M; Rudin, Markus

    2014-10-08

    Impairment of brain functional connectivity (FC) is thought to be an early event occurring in diseases with cerebral amyloidosis, such as Alzheimer's disease. Regions sustaining altered functional networks have been shown to colocalize with regions marked with amyloid plaques burden suggesting a strong link between FC and amyloidosis. Whether the decline in FC precedes amyloid plaque deposition or is a consequence thereof is currently unknown. The sequence of events during early stages of the disease is difficult to capture in humans due to the difficulties in providing an early diagnosis and also in view of the heterogeneity among patients. Transgenic mouse lines overexpressing amyloid precursor proteins develop cerebral amyloidosis and constitute an attractive model system for studying the relationship between plaque and functional changes. In this study, ArcAβ transgenic and wild-type mice were imaged using resting-state fMRI methods across their life-span in a cross-sectional design to analyze changes in FC in relation to the pathology. Transgenic mice show compromised development of FC during the first months of postnatal life compared with wild-type animals, resulting in functional impairments that affect in particular the sensory-motor cortex already in preplaque stage. These functional alterations were accompanied by structural changes as reflected by reduced fractional anisotropy values, as derived from diffusion tensor imaging. Our results suggest cerebral amyloidosis in mice is preceded by impairment of neuronal networks and white matter structures. FC analysis in mice is an attractive tool for studying the implications of impaired neuronal networks in models of cerebral amyloid pathology.

  9. Heat-induced alterations in monkey erythrocyte membrane phospholipid organization and skeletal protein structure and interactions.

    PubMed

    Kumar, A; Gudi, S R; Gokhale, S M; Bhakuni, V; Gupta, C M

    1990-12-14

    Rhesus monkey erythrocytes were subjected to heating at 50 degrees C for 5-15 min, and the heat-induced effects on the membrane structure were ascertained by analysing the membrane phospholipid organization and membrane skeleton dynamics and interactions in the heated cells. Membrane skeleton dynamics and interactions were determined by measuring the Tris-induced dissociation of the Triton-insoluble membrane skeleton (Triton shells), the spectrin-actin extractability at low ionic strength, spectrin self-association and spectrin binding to normal monkey erythrocyte membrane inside-out vesicles (IOVs). The Tris-induced Triton shell dissociation and spectrin-actin extractability were markedly decreased by the erythrocyte heating. Also, the binding of the heated erythrocyte membrane spectrin-actin with the IOVs was much smaller than that observed with the normal erythrocyte spectrin-actin. Further, the spectrin structure was extensively modified in the heated cells, as compared to the normal erythrocytes. Transbilayer phospholipid organization was ascertained by employing bee venom and pancreatic phospholipases A2, fluorescamine, and Merocyanine 540 as the external membrane probes. The amounts of aminophospholipids hydrolysed by phospholipases A2 or labeled by fluorescamine in intact erythrocytes considerably increased after subjecting them to heating at 50 degrees C for 15 min. Also, the fluorescent dye Merocyanine 540 readily stained the 15-min-heated cells but not the fresh erythrocytes. Unlike these findings, the extent of aminophospholipid hydrolysis in 5-min-heated cells by phospholipases A2 depended on the incubation time. While no change in the membrane phospholipid organization could be detected in 10 min, prolonged incubations led to the increased aminophospholipid hydrolysis. Similarly, fluorescamine failed to detect any change in the transbilayer phospholipid distribution soon after the 5 min heating, but it labeled greater amounts of aminophospholipids in

  10. A high-grain diet alters the omasal epithelial structure and expression of tight junction proteins in a goat model.

    PubMed

    Liu, Jun-Hua; Xu, Ting-Ting; Zhu, Wei-Yun; Mao, Sheng-Yong

    2014-07-01

    The omasal epithelial barrier plays important roles in maintaining nutrient absorption and immune homeostasis in ruminants. However, little information is currently available about the changes in omasal epithelial barrier function at the structural and molecular levels during feeding of a high-grain (HG) diet. Ten male goats were randomly assigned to two groups, fed either a hay diet (0% grain; n = 5) or HG diet (65% grain; n = 5). Changes in omasal epithelial structure and expression of tight junction (TJ) proteins were determined via electron microscopy and Western blot analysis. After 7 weeks on each diet, omasal contents in the HG group showed significantly lower pH (P <0.001) and significantly higher concentrations of free lipopolysaccharides (LPS; P = 0.001) than the hay group. The goats fed a HG diet showed profound alterations in omasal epithelial structure and TJ proteins, corresponding to depression of thickness of total epithelia, stratum granulosum, and the sum of the stratum spinosum and stratum basale, marked epithelial cellular damage, erosion of intercellular junctions and down-regulation in expression of the TJ proteins, claudin-4 and occludin. The study demonstrates that feeding a HG diet is associated with omasal epithelial cellular damage and changes in expression of TJ proteins. These research findings provide an insight into the possible significance of diet on the omasal epithelial barrier in ruminants.

  11. Prenatal cocaine exposure alters functional activation in the ventral prefrontal cortex and its structural connectivity with the amygdala.

    PubMed

    Li, Zhihao; Santhanam, Priya; Coles, Claire D; Ellen Lynch, Mary; Hamann, Stephan; Peltier, Scott; Hu, Xiaoping

    2013-07-30

    Prenatal cocaine exposure (PCE) is associated with arousal dysregulation, and alterations of amygdala activity in response to emotional arousal have previously been reported. However, voluntary regulation of emotional affect, enabling appropriate neural response to different streams of stimuli, must also engage prefrontal regions, yet the impact of PCE on these prefrontal mechanisms has not been investigated. Recent neuroimaging studies have shown the involvement of ventral prefrontal cortex (vPFC) in the modulation of amygdala reactivity and the mediation of effective emotional regulation. Based on these findings, using functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), the present study compared functional activations of the vPFC as well as its structural connectivity with the amygdala between groups of PCE and control adolescents. In a working memory task with emotional distracters, the PCE adolescents exhibited less capability of increasing their vPFC activation in response to increased memory load, which corresponded with their less suppressed amygdala activation. Reduced structural connectivity between the vPFC and the amygdala was also observed from DTI measurement in the PCE group. In addition, correlations between amygdala activation and (i) vPFC activation, as well as (ii) amygdala-vPFC structural connectivity, were observed in the control but not in the PCE group. These data complement previous findings of the impact of PCE on the activity of the amygdala and extend our understanding of the neurobiological mechanisms underlying the effect of PCE on arousal dysregulation reported in human and animal studies.

  12. Differential Progression of Structural and Functional Alterations in Distinct Retinal Ganglion Cell Types in a Mouse Model of Glaucoma

    PubMed Central

    Della Santina, Luca; Inman, Denise M.; Lupien, Caroline B.; Horner, Philip J.

    2013-01-01

    Intraocular pressure (IOP) elevation is a principal risk factor for glaucoma. Using a microbead injection technique to chronically raise IOP for 15 or 30 d in mice, we identified the early changes in visual response properties of different types of retinal ganglion cells (RGCs) and correlated these changes with neuronal morphology before cell death. Microbead-injected eyes showed reduced optokinetic tracking as well as cell death. In such eyes, multielectrode array recordings revealed that four RGC types show diverse alterations in their light responses upon IOP elevation. OFF-transient RGCs exhibited a more rapid decline in both structural and functional organizations compared with other RGCs. In contrast, although the light-evoked responses of OFF-sustained RGCs were perturbed, the dendritic arbor of this cell type remained intact. ON-transient and ON-sustained RGCs had normal functional receptive field sizes but their spontaneous and light-evoked firing rates were reduced. ON- and OFF-sustained RGCs lost excitatory synapses across an otherwise structurally normal dendritic arbor. Together, our observations indicate that there are changes in spontaneous activity and light-evoked responses in RGCs before detectable dendritic loss. However, when dendrites retract, we found corresponding changes in receptive field center size. Importantly, the effects of IOP elevation are not uniformly manifested in the structure and function of diverse RGC populations, nor are distinct RGC types perturbed within the same time-frame by such a challenge. PMID:24174678

  13. Stanniocalcin in the euryhaline flounder (Platichthys flesus): primary structure, tissue distribution, and response to altered salinity.

    PubMed

    Hang, Xiaoming; Balment, Richard John

    2005-11-01

    Stanniocalcin (STC) is a homodimeric glycoprotein hormone that was first discovered in fish, where it is largely produced by a unique endocrine gland, the corpuscles of Stannius (CS). In bony fish, it is thought to be an important regulator of calcium and phosphate uptake from the aquatic environment. This report describes the molecular cloning of STC from euryhaline flounder (Platichthys flesus) CS cDNA and genomic DNA. The flounder STC encodes a prehormone of 251 amino acids (aa) with a signal peptide of 17 aa, followed by another 15 aa sequence before the mature protein of 219 aa. The deduced aa sequence of flounder STC shows 62.9-89.0% similarity and 50.4-83.1% identity with other known fish STC sequences, but only 42.3% identity with mouse STC1, 24.4% identity with fugu and zebrafish STC2, and 22.3% identity with mouse STC2. Primary structural analysis demonstrated that flounder STC gene contains five exons in contrast to the four exons present in mammalian STC gene. RT-PCR revealed the expression of flounder STC mRNA to be widely spread in many tissues and organs, similar to the situation in mammals and other fish. Quantitative PCR (Q-PCR) was conducted to measure relative STC expression levels in the CS, which showed STC mRNA expression levels in seawater-adapted fish CS were about 3-fold higher than in freshwater-adapted fish CS.

  14. Elevated atmospheric CO{sub 2} alters root-microbe interactions and belowground trophic structure

    SciTech Connect

    Klironomos, J.N.; Rillig, M.C.; Allen, M.F.

    1995-09-01

    Various aspects of plant and ecosystem responses to elevated atmospheric carbon dioxide have been described. However, very little is known about the fate of carbon allocated belowground, microbial activity, and trophic structure in the rhizosphere. Rhizosphere microbes are fed primarily by root-derived substrates, fulfill functions such as mineralization, immobilization, decomposition, pathogeneity, and improvement of plant nutrition, and form the base of the below-ground food web. Belowground processes have so far been monitored using a black-box approach, thereby ignoring effects of global change at a finer (functional group) level of resolution. This study is the first to describe shifts in the activity and dominance between microbial functional groups, and the results of this on higher trophic levels. We observed that, in a nutrient-rich soil, carbon flow in the plant-soil system was shunted from a mutualistic-closed, mycorrhizal dominated flow to an opportunist-open, saprobe/pathogen dominated one. This indicates that elevated atmospheric CO{sub 2} may lead to far less predictable consequences than previously thought.

  15. Changes in the distribution of sustained attention alter the perceived structure of visual space.

    PubMed

    Fortenbaugh, Francesca C; Robertson, Lynn C; Esterman, Michael

    2017-02-01

    Visual spatial attention is a critical process that allows for the selection and enhanced processing of relevant objects and locations. While studies have shown attentional modulations of perceived location and the representation of distance information across multiple objects, there remains disagreement regarding what influence spatial attention has on the underlying structure of visual space. The present study utilized a method of magnitude estimation in which participants must judge the location of briefly presented targets within the boundaries of their individual visual fields in the absence of any other objects or boundaries. Spatial uncertainty of target locations was used to assess perceived locations across distributed and focused attention conditions without the use of external stimuli, such as visual cues. Across two experiments we tested locations along the cardinal and 45° oblique axes. We demonstrate that focusing attention within a region of space can expand the perceived size of visual space; even in cases where doing so makes performance less accurate. Moreover, the results of the present studies show that when fixation is actively maintained, focusing attention along a visual axis leads to an asymmetrical stretching of visual space that is predominantly focused across the central half of the visual field, consistent with an expansive gradient along the focus of voluntary attention. These results demonstrate that focusing sustained attention peripherally during active fixation leads to an asymmetrical expansion of visual space within the central visual field.

  16. Modulating cellular recombination potential through alterations in RecA structure and regulation.

    PubMed

    Bakhlanova, Irina V; Dudkina, Alexandra V; Baitin, Dima M; Knight, Kendall L; Cox, Michael M; Lanzov, Vladislav A

    2010-12-01

    The wild-type Escherichia coli RecA protein is a recombinase platform with unrealized recombination potential. We have explored the factors affecting recombination during conjugation with a quantitative assay. Regulatory proteins that affect RecA function have the capacity to increase or decrease recombination frequencies by factors up to sixfold. Autoinhibition by the RecA C-terminus can affect recombination frequency by factors up to fourfold. The greatest changes in recombination frequency measured here are brought about by point mutations in the recA gene. RecA variants can increase recombination frequencies by more than 50-fold. The RecA protein thus possesses an inherently broad functional range. The RecA protein of E. coli (EcRecA) is not optimized for recombination function. Instead, much of the recombination potential of EcRecA is structurally suppressed, probably reflecting cellular requirements. One point mutation in EcRecA with a particularly dramatic effect on recombination frequency, D112R, exhibits an enhanced capacity to load onto SSB-coated ssDNA, overcome the effects of regulatory proteins such as PsiB and RecX, and to pair homologous DNAs. Comparisons of key RecA protein mutants reveal two components to RecA recombination function - filament formation and the inherent DNA pairing activity of the formed filaments.

  17. Altered lumbar spine structure, biochemistry and biomechanical properties in a canine model of mucopolysaccharidosis type VII

    PubMed Central

    Smith, Lachlan J; Martin, John T; Szczesny, Spencer E; Ponder, Katherine P; Haskins, Mark E; Elliott, Dawn M

    2010-01-01

    Mucopolysaccharidosis VII (MPS VII) is a lysosomal storage disorder characterized by a deficiency in β-glucuronidase activity, leading to systemic accumulation of poorly degraded glycosaminoglycans (GAG). Along with other morbidities, MPS VII is associated with paediatric spinal deformity. The objective of this study was to examine potential associations between abnormal lumbar spine matrix structure and composition in MPS VII, and spine segment and tissue-level mechanical properties, using a naturally occurring canine model with a similar clinical phenotype to the human form of the disorder. Segments from juvenile MPS VII and unaffected dogs were allocated to: radiography, gross morphology, histology, biochemistry, and mechanical testing. MPS VII spines had radiolucent lesions in the vertebral body epiphyses. Histologically, this corresponded to a GAG-rich cartilaginous region in place of bone, and elevated GAG staining was seen in the annulus fibrosus. Biochemically, MPS VII samples had elevated GAG in the outer annulus fibrosus and epiphyses, low calcium in the epiphyses, and high water content in all regions except the nucleus pulposus. MPS VII spine segments had higher range of motion and lower stiffness than controls. Endplate indentation stiffness and failure loads were significantly lower in MPS VII samples, while annulus fibrosus tensile mechanical properties were normal. Vertebral body lesions in MPS VII spines suggest a failure to convert cartilage to bone during development. Low stiffness in these regions likely contributes to mechanical weakness in motion segments and is a potential factor in the progression of spinal deformity. PMID:19918911

  18. Electronic Structure Evolution with Composition Alteration of RhxCuy Alloy Nanoparticles

    PubMed Central

    Palina, Natalia; Sakata, Osami; Kumara, L. S. R.; Song, Chulho; Sato, Katsutoshi; Nagaoka, Katsutoshi; Komatsu, Tokutaro; Kobayashi, Hirokazu; Kusada, Kohei; Kitagawa, Hiroshi

    2017-01-01

    The change in electronic structure of extremely small RhxCuy alloy nanoparticles (NPs) with composition variation was investigated by core-level (CL) and valence-band (VB) hard X-ray photoelectron spectroscopy. A combination of CL and VB spectra analyses confirmed that intermetallic charge transfer occurs between Rh and Cu. This is an important compensation mechanism that helps to explain the relationship between the catalytic activity and composition of RhxCuy alloy NPs. For monometallic Rh and Rh-rich alloy (Rh0.77Cu0.23) NPs, the formation of Rh surface oxide with a non-integer oxidation state (Rh(3−δ)+) resulted in high catalytic activity. Conversely, for alloy NPs with comparable Rh:Cu ratio (Rh0.53Cu0.47 and Rh0.50Cu0.50), the decreased fraction of catalytically active Rh(3−δ)+ oxide is compensated by charge transfer from Cu to Rh. As a result, ensuring negligible change in the catalytic activities of the NPs with comparable Rh:Cu ratio to those of Rh-rich and monometallic Rh NPs. PMID:28120907

  19. Electronic Structure Evolution with Composition Alteration of RhxCuy Alloy Nanoparticles

    NASA Astrophysics Data System (ADS)

    Palina, Natalia; Sakata, Osami; Kumara, L. S. R.; Song, Chulho; Sato, Katsutoshi; Nagaoka, Katsutoshi; Komatsu, Tokutaro; Kobayashi, Hirokazu; Kusada, Kohei; Kitagawa, Hiroshi

    2017-01-01

    The change in electronic structure of extremely small RhxCuy alloy nanoparticles (NPs) with composition variation was investigated by core-level (CL) and valence-band (VB) hard X-ray photoelectron spectroscopy. A combination of CL and VB spectra analyses confirmed that intermetallic charge transfer occurs between Rh and Cu. This is an important compensation mechanism that helps to explain the relationship between the catalytic activity and composition of RhxCuy alloy NPs. For monometallic Rh and Rh-rich alloy (Rh0.77Cu0.23) NPs, the formation of Rh surface oxide with a non-integer oxidation state (Rh(3‑δ)+) resulted in high catalytic activity. Conversely, for alloy NPs with comparable Rh:Cu ratio (Rh0.53Cu0.47 and Rh0.50Cu0.50), the decreased fraction of catalytically active Rh(3‑δ)+ oxide is compensated by charge transfer from Cu to Rh. As a result, ensuring negligible change in the catalytic activities of the NPs with comparable Rh:Cu ratio to those of Rh-rich and monometallic Rh NPs.

  20. Structural imaging reveals anatomical alterations in inferotemporal cortex in congenital prosopagnosia.

    PubMed

    Behrmann, Marlene; Avidan, Galia; Gao, Fuqiang; Black, Sandra

    2007-10-01

    Congenital prosopagnosia (CP) refers to the lifelong impairment in face recognition in individuals who have intact low-level visual processing, normal cognitive abilities, and no known neurological disorder. Although the face recognition impairment is profound and debilitating, its neural basis remains elusive. To investigate this, we conducted detailed morphometric and volumetric analyses of the occipitotemporal (OT) cortex in a group of CP individuals and matched control subjects using high-spatial resolution magnetic resonance imaging. Although there were no significant group differences in the depth or deviation from the midline of the OT or collateral sulci, the CP individuals evince a larger anterior and posterior middle temporal gyrus and a significantly smaller anterior fusiform (aF) gyrus. Interestingly, this volumetric reduction in the aF gyrus is correlated with the behavioral decrement in face recognition. These findings implicate a specific cortical structure as the neural basis of CP and, in light of the familial history of CP, target the aF gyrus as a potential site for further, focused genetic investigation.

  1. Altered Structural Correlates of Impulsivity in Adolescents with Internet Gaming Disorder

    PubMed Central

    Du, Xin; Qi, Xin; Yang, Yongxin; Du, Guijin; Gao, Peihong; Zhang, Yang; Qin, Wen; Li, Xiaodong; Zhang, Quan

    2016-01-01

    Recent studies suggested that internet gaming disorder (IGD) was associated with impulsivity and structural abnormalities in brain gray matter (GM). However, no morphometric study has examined the association between GM and impulsivity in IGD individuals. In this study, 25 adolescents with IGD and 27 healthy controls (HCs) were recruited, and the relationship between Barratt impulsiveness scale-11 (BIS) score and gray matter volume (GMV) was investigated with the voxel-based morphometric (VBM) correlation analysis. Then, the intergroup differences in correlation between BIS score and GMV were tested across all GM voxels. Our results showed that the correlations between BIS score and GMV of the right dorsomedial prefrontal cortex (dmPFC), the bilateral insula and the orbitofrontal cortex (OFC), the right amygdala and the left fusiform gyrus decreased in the IGD group compared to the HCs. Region-of-interest (ROI) analysis revealed that GMV in all these clusters showed significant positive correlations with BIS score in the HCs, while no significant correlation was found in the IGD group. Our findings demonstrated that dysfunction of these brain areas involved in the behavior inhibition, attention and emotion regulation might contribute to impulse control problems in IGD adolescents. PMID:26858620

  2. Soft lithographic printing and transfer of photosensitive polymers: facile fabrication of free-standing structures and patterning fragile and unconventional substrates

    NASA Astrophysics Data System (ADS)

    Zhang, Yaozhong; Han, Jea-Hyeoung; Zhu, Likun; Shannon, Mark A.; Yeom, Junghoon

    2014-11-01

    Dry film photoresists (DF PRs) are widely used to perform photolithography on non-traditional substrates such as printing circuit boards, plastic sheets, or non-planar surfaces. Commercially available DF PRs are usually in a negative tone and rather thick, limiting lithographic resolution and versatility. The relatively large pressure required for lamination also prevents the technology from being used for delicate substrates. Here we present a modified soft-lithographic process, namely photoresist blanket transfer (PR BT), transferring a spin-coated PR film from a flat elastomeric stamp to a substrate. The elastomeric stamp is highly compliant, bringing the PR film into intimate contact with the substrate and eliminating the need for a large lamination pressure. Photolithography on unconventional substrates such as etched, fragile, and porous ones is demonstrated. Single or multiple transfers of PRs by BT are utilized to fabricate multilayer, free-standing, and re-entrant polymeric microstructures. A fragile and porous substrate such as an anodized aluminum oxide membrane can also be patterned using PR BT. Moreover, a reliable method to create metal electrodes and high surface area catalysts inside microchannels is discussed for novel microfluidic applications.

  3. Chemical-shift X-ray standing wavefield determination of the local structure of methanethiolate phases on Ni( 1 1 1 )

    NASA Astrophysics Data System (ADS)

    Fisher, C. J.; Woodruff, D. P.; Jones, R. G.; Cowie, B. C. C.; Formoso, V.

    2002-01-01

    By monitoring the X-ray absorption through the chemically-shifted components of the S 1s photoemission signal, normal-incidence X-ray standing wavefield absorption at the (1 1 1) and ( 1¯ 1 1) scatterer planes has been used to determine the local adsorption geometry of the two distinct methanethiolate (CH 3S-) species which occur on Ni(1 1 1) following exposure to methanethiol. The species which is favoured at low temperatures is found to occupy either mixed hollow or bridge sites on a non-reconstructed Ni(1 1 1) surface, whereas that seen at higher temperatures is shown to involve Ni surface layer reconstruction and the data are consistent with hollow site adsorption on a reduced density outermost Ni layer. The relative merits of alternative reconstruction models based on that which occurs due to methanethiolate adsorption on Cu(1 1 1), or the (5√3×2)rect. phase formed by atomic S on Ni(1 1 1), are discussed. Both of these models are based on local square or `pseudo-(1 0 0)' outermost Ni layers. Co-adsorbed atomic sulphur, to which the methanethiolate species decompose at higher temperatures, appears to occupy mainly fcc hollow sites at low temperatures, but is partially converted to the local geometry of the ordered reconstructed (5√3×2)rect.-S phase after higher temperature annealing.

  4. 21. Building 202, underside of test stand A, detail of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. Building 202, underside of test stand A, detail of junction of scrubber structure and test stand with water pipes and valves visible. View looking southeast. - Rocket Engine Testing Facility, GRC Building No. 202, NASA Glenn Research Center, Cleveland, Cuyahoga County, OH

  5. CLOSEUP VIEW LOOKING SOUTH AT THE SATURN I TEST STAND, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CLOSE-UP VIEW LOOKING SOUTH AT THE SATURN I TEST STAND, NOTE THE INTERPRETIVE SIGN EXPLAINING THE HISTORIC NATURE OF THE SATURN I TEST STAND. - Marshall Space Flight Center, Saturn Propulsion & Structural Test Facility, East Test Area, Huntsville, Madison County, AL

  6. Triclocarban Influences Antibiotic Resistance and Alters Anaerobic Digester Microbial Community Structure.

    PubMed

    Carey, Daniel E; Zitomer, Daniel H; Hristova, Krassimira R; Kappell, Anthony D; McNamara, Patrick J

    2016-01-05

    Triclocarban (TCC) is one of the most abundant organic micropollutants detected in biosolids. Lab-scale anaerobic digesters were amended with TCC at concentrations ranging from the background concentration of seed biosolids (30 mg/kg) to toxic concentrations of 850 mg/kg to determine the effect on methane production, relative abundance of antibiotic resistance genes, and microbial community structure. Additionally, the TCC addition rate was varied to determine the impacts of acclimation time. At environmentally relevant TCC concentrations (max detect = 440 mg/kg), digesters maintained function. Digesters receiving 450 mg/kg of TCC maintained function under gradual TCC addition, but volatile fatty acid concentrations increased, pH decreased, and methane production ceased when immediately fed this concentration. The concentrations of the mexB gene (encoding for a multidrug efflux pump) were higher with all concentrations of TCC compared to a control, but higher TCC concentrations did not correlate with increased mexB abundance. The relative abundance of the gene tet(L) was greater in the digesters that no longer produced methane, and no effect on the relative abundance of the class 1 integron integrase encoding gene (intI1) was observed. Illumina sequencing revealed substantial community shifts in digesters that functionally failed from increased levels of TCC. More subtle, yet significant, community shifts were observed in digesters amended with TCC levels that did not inhibit function. This research demonstrates that TCC can select for a multidrug resistance encoding gene in mixed community anaerobic environments, and this selection occurs at concentrations (30 mg/kg) that can be found in full-scale anaerobic digesters (U.S. median concentration = 22 mg/kg, mean = 39 mg/kg).

  7. Overexpression of the OsERF71 Transcription Factor Alters Rice Root Structure and Drought Resistance.

    PubMed

    Lee, Dong-Keun; Jung, Harin; Jang, Geupil; Jeong, Jin Seo; Kim, Youn Shic; Ha, Sun-Hwa; Do Choi, Yang; Kim, Ju-Kon

    2016-09-01

    Plant responses to drought stress require the regulation of transcriptional networks via drought-responsive transcription factors, which mediate a range of morphological and physiological changes. AP2/ERF transcription factors are known to act as key regulators of drought resistance transcriptional networks; however, little is known about the associated molecular mechanisms that give rise to specific morphological and physiological adaptations. In this study, we functionally characterized the rice (Oryza sativa) drought-responsive AP2/ERF transcription factor OsERF71, which is expressed predominantly in the root meristem, pericycle, and endodermis. Overexpression of OsERF71, either throughout the entire plant or specifically in roots, resulted in a drought resistance phenotype at the vegetative growth stage, indicating that overexpression in roots was sufficient to confer drought resistance. The root-specific overexpression was more effective in conferring drought resistance at the reproductive stage, such that grain yield was increased by 23% to 42% over wild-type plants or whole-body overexpressing transgenic lines under drought conditions. OsERF71 overexpression in roots elevated the expression levels of genes related to cell wall loosening and lignin biosynthetic genes, which correlated with changes in root structure, the formation of enlarged aerenchyma, and high lignification levels. Furthermore, OsERF71 was found to directly bind to the promoter of OsCINNAMOYL-COENZYME A REDUCTASE1, a key gene in lignin biosynthesis. These results indicate that the OsERF71-mediated drought resistance pathway recruits factors involved in cell wall modification to enable root morphological adaptations, thereby providing a mechanism for enhancing drought resistance.

  8. Extrafloral nectaries alter arthropod community structure and mediate peach (Prunus persica) plant defense.

    PubMed

    Mathews, Clarissa R; Bottrell, Dale G; Brown, Mark W

    2009-04-01

    We investigated the role of extrafloral nectaries (EFNs) in mediating plant defense for newly established peach (Prunus persica) trees. We used peaches of a single cultivar ("Lovell") that varied with respect to EFN leaf phenotype (with or without EFNs) to determine if the EFNs affected the structure of the arthropod community colonizing newly planted seedlings. We also tested if the plants producing EFNs benefited from reduced herbivory or enhanced productivity. In the first year following planting, the young peach trees with EFNs were dominated by ants, and arthropod community diversity was lower than for trees without EFNs. The young trees with EFNs harbored fewer herbivores and experienced a twofold reduction in folivory compared to trees without EFNs. Productivity was also enhanced for the trees with EFNs, which attained significantly higher rates of trunk growth, greater terminal carbon composition, and a threefold increase in buds produced in subsequent years. In the second year of the field study, ants remained numerically dominant on trees with EFNs, but arthropod community diversity was higher than for trees without EFNs. An additional study revealed that folivory rates in May increased dramatically for trees with EFNs if ants were excluded from their canopies, indicating that ants have a protective function when the perennial trees produce new leaves. However, in later months, regardless of ants' presence, the trees with EFNs suffered less folivory than trees lacking EFNs. The diversity and richness of the predator trophic group increased when ants were excluded from trees with EFNs, but overall community diversity (i.e., herbivores and predators combined) was not affected by the ants' presence. Our research indicates that the EFNs play an important role in attracting predators that protect the trees from herbivores, and the EFN host-plant characteristic should be retained in future peach cultivar selections. Furthermore, peach production programs aimed

  9. Huanglongbing alters the structure and functional diversity of microbial communities associated with citrus rhizosphere

    PubMed Central

    Trivedi, Pankaj; He, Zhili; Van Nostrand, Joy D; Albrigo, Gene; Zhou, Jizhong; Wang, Nian

    2012-01-01

    The diversity and stability of bacterial communities present in the rhizosphere heavily influence soil and plant quality and ecosystem sustainability. The goal of this study is to understand how ‘Candidatus Liberibacter asiaticus' (known to cause Huanglongbing, HLB) influences the structure and functional potential of microbial communities associated with the citrus rhizosphere. Clone library sequencing and taxon/group-specific quantitative real-time PCR results showed that ‘Ca. L. asiaticus' infection restructured the native microbial community associated with citrus rhizosphere. Within the bacterial community, phylum Proteobacteria with various genera typically known as successful rhizosphere colonizers were significantly greater in clone libraries from healthy samples, whereas phylum Acidobacteria, Actinobacteria and Firmicutes, typically more dominant in the bulk soil were higher in ‘Ca. L. asiaticus'-infected samples. A comprehensive functional microarray GeoChip 3.0 was used to determine the effects of ‘Ca. L. asiaticus' infection on the functional diversity of rhizosphere microbial communities. GeoChip analysis showed that HLB disease has significant effects on various functional guilds of bacteria. Many genes involved in key ecological processes such as nitrogen cycling, carbon fixation, phosphorus utilization, metal homeostasis and resistance were significantly greater in healthy than in the ‘Ca. L. asiaticus'-infected citrus rhizosphere. Our results showed that the microbial community of the ‘Ca. L. asiaticus'-infected citrus rhizosphere has shifted away from using more easily degraded sources of carbon to the more recalcitrant forms. Overall, our study provides evidence that the change in plant physiology mediated by ‘Ca. L. asiaticus' infection could elicit shifts in the composition and functional potential of rhizosphere microbial communities. In the long term, these fluctuations might have important implications for the productivity and

  10. Outer Plexiform Layer Structures Are Not Altered Following AAV-Mediated Gene Transfer in Healthy Rat Retina

    PubMed Central

    Giers, Bert C.; Klein, Daniela; Mendes-Madeira, Alexandra; Isiegas, Carolina; Lorenz, Birgit; Haverkamp, Silke; Stieger, Knut

    2017-01-01

    Ocular gene therapy approaches have been developed for a variety of different diseases. In particular, clinical gene therapy trials for RPE65 mutations, X-linked retinoschisis, and choroideremia have been conducted at different centers in recent years, showing that adeno-associated virus (AAV)-mediated gene therapy is safe, but limitations exist as to the therapeutic benefit and long-term duration of the treatment. The technique of vector delivery to retinal cells relies on subretinal injection of the vector solution, causing a transient retinal detachment. Although retinal detachments are known to cause remodeling of retinal neuronal structures as well as significant cell loss, the possible effects of this short-term therapeutic retinal detachment on retinal structure and circuitry have not yet been studied in detail. In this study, retinal morphology and apoptotic status were examined in healthy rat retinas following AAV-mediated gene transfer via subretinal injection with AAV2/5.CMV.d2GFP or sham injection with fluorescein. Outer plexiform layer (OPL) morphology was assessed by immunohistochemical labeling, laser scanning confocal microscopy, and electron microscopy. The number of synaptic contacts in the OPL was quantified after labeling with structural markers. To assess the apoptotic status, inflammatory and pro-apoptotic markers were tested and TUNEL assay for the detection of apoptotic nuclei was performed. Pre- and postsynaptic structures in the OPL, such as synaptic ribbons or horizontal and bipolar cell processes, did not differ in size or shape in injected versus non-injected areas and control retinas. Absolute numbers of synaptic ribbons were not altered. No signs of relevant gliosis were detected. TUNEL labeling of retinal cells did not vary between injected and non-injected areas, and apoptosis-inducing factor was not delocalized to the nucleus in transduced areas. The neuronal circuits in the OPL of healthy rat retinas undergoing AAV-mediated gene

  11. Outer Plexiform Layer Structures Are Not Altered Following AAV-Mediated Gene Transfer in Healthy Rat Retina.

    PubMed

    Giers, Bert C; Klein, Daniela; Mendes-Madeira, Alexandra; Isiegas, Carolina; Lorenz, Birgit; Haverkamp, Silke; Stieger, Knut

    2017-01-01

    Ocular gene therapy approaches have been developed for a variety of different diseases. In particular, clinical gene therapy trials for RPE65 mutations, X-linked retinoschisis, and choroideremia have been conducted at different centers in recent years, showing that adeno-associated virus (AAV)-mediated gene therapy is safe, but limitations exist as to the therapeutic benefit and long-term duration of the treatment. The technique of vector delivery to retinal cells relies on subretinal injection of the vector solution, causing a transient retinal detachment. Although retinal detachments are known to cause remodeling of retinal neuronal structures as well as significant cell loss, the possible effects of this short-term therapeutic retinal detachment on retinal structure and circuitry have not yet been studied in detail. In this study, retinal morphology and apoptotic status were examined in healthy rat retinas following AAV-mediated gene transfer via subretinal injection with AAV2/5.CMV.d2GFP or sham injection with fluorescein. Outer plexiform layer (OPL) morphology was assessed by immunohistochemical labeling, laser scanning confocal microscopy, and electron microscopy. The number of synaptic contacts in the OPL was quantified after labeling with structural markers. To assess the apoptotic status, inflammatory and pro-apoptotic markers were tested and TUNEL assay for the detection of apoptotic nuclei was performed. Pre- and postsynaptic structures in the OPL, such as synaptic ribbons or horizontal and bipolar cell processes, did not differ in size or shape in injected versus non-injected areas and control retinas. Absolute numbers of synaptic ribbons were not altered. No signs of relevant gliosis were detected. TUNEL labeling of retinal cells did not vary between injected and non-injected areas, and apoptosis-inducing factor was not delocalized to the nucleus in transduced areas. The neuronal circuits in the OPL of healthy rat retinas undergoing AAV-mediated gene

  12. Biochar affects soil organic matter cycling and microbial functions but does not alter microbial community structure in a paddy soil.

    PubMed

    Tian, Jing; Wang, Jingyuan; Dippold, Michaela; Gao, Yang; Blagodatskaya, Evgenia; Kuzyakov, Yakov

    2016-06-15

    The application of biochar (BC) in conjunction with mineral fertilizers is one of the most promising management practices recommended to improve soil quality. However, the interactive mechanisms of BC and mineral fertilizer addition affecting microbial communities and functions associated with soil organic matter (SOM) cycling are poorly understood. We investigated the SOM in physical and chemical fractions, microbial community structure (using phospholipid fatty acid analysis, PLFA) and functions (by analyzing enzymes involved in C and N cycling and Biolog) in a 6-year field experiment with BC and NPK amendment. BC application increased total soil C and particulate organic C for 47.4-50.4% and 63.7-74.6%, respectively. The effects of BC on the microbial community and C-cycling enzymes were dependent on fertilization. Addition of BC alone did not change the microbial community compared with the control, but altered the microbial community structure in conjunction with NPK fertilization. SOM fractions accounted for 55% of the variance in the PLFA-related microbial community structure. The particulate organic N explained the largest variation in the microbial community structure. Microbial metabolic activity strongly increased after BC addition, particularly the utilization of amino acids and amines due to an increase in the activity of proteolytic (l-leucine aminopeptidase) enzymes. These results indicate that microorganisms start to mine N from the SOM to compensate for high C:N ratios after BC application, which consequently accelerate cycling of stable N. Concluding, BC in combination with NPK fertilizer application strongly affected microbial community composition and functions, which consequently influenced SOM cycling.

  13. Evaluation of changes in macrobenthic standing stock and polychaete community structure along the south eastern Arabian Sea shelf during the monsoon trawl-ban

    NASA Astrophysics Data System (ADS)

    Abdul Jaleel, K. U.; Parameswaran, Usha V.; Gopal, Aiswarya; Khader, Chippy; Ganesh, T.; Sanjeevan, V. N.; Shunmugaraj, T.; Vijayan, Anil Kumar; Gupta, G. V. M.

    2015-07-01

    The south eastern Arabian Sea is characterized by moderate coastal upwelling, high biological production and subsurface oxygen depletion during the southwest monsoon (June-September). Concurrently, a seasonal closure to trawling activities (15th June-31st July) is implemented here, as a sustainable ecosystem management practise. The effects of monsoon driven environmental changes and consequences of trawling cessation on macrofauna were assessed, based on surveys at 12 sites (30-200 m) preceding and during different phases of the southwest monsoon. Macrofaunal density and biomass increased considerably towards the mid and late monsoon along the inner shelf (30-50 m) where trawling is intense, while no temporal changes were observed along the outer shelf (100-200 m). Density increased four-folds at the 30 m contour and three-folds at 50 m, while biomass nearly doubled at both depths, reflecting a marked increase in density of polychaetes (61-87% of macrofauna). The disproportionate increase in faunal density and biomass along the inner shelf (30-50 m) was due to abundance of juvenile polychaetes and dominance of small-sized opportunists towards late monsoon (August-September). A concurrent hike in nominal species count of polychaetes was also observed in the study area. The increase in polychaete standing stock and high density of planktonic larvae during onset and peak monsoon, coupled with occurrence of juveniles as well as gamete-bearing adults in sediments, indicates that the southwest monsoon is a peak breeding season for the dominant polychaetes in the region. The trawl-ban during this period facilitates the recoupment of benthos by maximising spawning success and larval settlement, thereby enhancing overall ecosystem integrity.

  14. Structure-Function Analysis of the ϕX174 DNA-Piloting Protein Using Length-Altering Mutations

    PubMed Central

    Roznowski, Aaron P.

    2016-01-01

    ABSTRACT Although the ϕX174 H protein is monomeric during procapsid morphogenesis, 10 proteins oligomerize to form a DNA translocating conduit (H-tube) for penetration. However, the timing and location of H-tube formation are unknown. The H-tube's highly repetitive primary and quaternary structures made it amenable to a genetic analysis using in-frame insertions and deletions. Length-altered proteins were characterized for the ability to perform the protein's three known functions: participation in particle assembly, genome translocation, and stimulation of viral protein synthesis. Insertion mutants were viable. Theoretically, these proteins would produce an assembled tube exceeding the capsid's internal diameter, suggesting that virions do not contain a fully assembled tube. Lengthened proteins were also used to test the biological significance of the crystal structure. Particles containing H proteins of two different lengths were significantly less infectious than both parents, indicating an inability to pilot DNA. Shortened H proteins were not fully functional. Although they could still stimulate viral protein synthesis, they either were not incorporated into virions or, if incorporated, failed to pilot the genome. Mutant proteins that failed to incorporate contained deletions within an 85-amino-acid segment, suggesting the existence of an incorporation domain. The revertants of shortened H protein mutants fell into two classes. The first class duplicated sequences neighboring the deletion, restoring wild-type length but not wild-type sequence. The second class suppressed an incorporation defect, allowing the use of the shortened protein. IMPORTANCE The H-tube crystal structure represents the first high-resolution structure of a virally encoded DNA-translocating conduit. It has similarities with other viral proteins through which DNA must travel, such as the α-helical barrel domains of P22 portal proteins and T7 proteins that form tail tube extensions during

  15. Structural Mutants of the Spindle Pole Body Cause Distinct Alteration of Cytoplasmic Microtubules and Nuclear Dynamics in Multinucleated Hyphae

    PubMed Central

    Lang, Claudia; Grava, Sandrine; Finlayson, Mark; Trimble, Rhonda; Philippsen, Peter

    2010-01-01

    In the multinucleate fungus Ashbya gossypii, cytoplasmic microtubules (cMTs) emerge from the spindle pole body outer plaque (OP) in perpendicular and tangential directions. To elucidate the role of cMTs in forward/backward movements (oscillations) and bypassing of nuclei, we constructed mutants potentially affecting cMT nucleation or stability. Hyphae lacking the OP components AgSpc72, AgNud1, AgCnm67, or the microtubule-stabilizing factor AgStu2 grew like wild- type but showed substantial alterations in the number, length, and/or nucleation sites of cMTs. These mutants differently influenced nuclear oscillation and bypassing. In Agspc72Δ, only long cMTs were observed, which emanate tangentially from reduced OPs; nuclei mainly moved with the cytoplasmic stream but some performed rapid bypassing. Agnud1Δ and Agcnm67Δ lack OPs; short and long cMTs emerged from the spindle pole body bridge/half-bridge structures, explaining nuclear oscillation and bypassing in these mutants. In Agstu2Δ only very short cMTs emanated from structurally intact OPs; all nuclei moved with the cytoplasmic stream. Therefore, long tangential cMTs promote nuclear bypassing and short cMTs are important for nuclear oscillation. Our electron microscopy ultrastructural analysis also indicated that assembly of the OP occurs in a stepwise manner, starting with AgCnm67, followed by AgNud1 and lastly AgSpc72. PMID:20053682

  16. Albumin Homodimers in Patients with Cirrhosis: Clinical and Prognostic Relevance of a Novel Identified Structural Alteration of the Molecule

    PubMed Central

    Baldassarre, Maurizio; Domenicali, Marco; Naldi, Marina; Laggetta, Maristella; Giannone, Ferdinando A.; Biselli, Maurizio; Patrono, Daniela; Bertucci, Carlo; Bernardi, Mauro; Caraceni, Paolo

    2016-01-01

    Decompensated cirrhosis is associated to extensive post-transcriptional changes of human albumin (HA). This study aims to characterize the occurrence of HA homodimerization in a large cohort of patients with decompensated cirrhosis and to evaluate its association with clinical features and prognosis. HA monomeric and dimeric isoforms were identified in peripheral blood by using a HPLC-ESI-MS technique in 123 cirrhotic patients hospitalized for acute decompensation and 50 age- and sex-comparable healthy controls. Clinical and biochemical parameters were recorded and patients followed up to one year. Among the monomeric isoforms identified, the N- and C-terminal truncated and the native HA underwent homodimerization. All three homodimers were significantly more abundant in patients with cirrhosis, acute-on-chronic liver failure and correlate with the prognostic scores. The homodimeric N-terminal truncated isoform was independently associated to disease complications and was able to stratify 1-year survival. As a result of all these changes, the monomeric native HA was significantly decreased in patients with cirrhosis, being also associated with a poorer prognosis. In conclusion homodimerization is a novel described structural alteration of the HA molecule in decompensated cirrhosis and contributes to the progressive reduction of the monomeric native HA, the only isoform provided of structural and functional integrity. PMID:27782157