bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of caesium‐137 in soils across a hillslope hollow
Authors: Morris C. D. , Loughran R. J.
Published: February 2007

The distribution of soil 137Cs in relation to selected soil and landform properties was studied across a 16 ha hillslope hollow in the Hunter valley, New South Wales, Australia. The hillslope was used as grazing for cattle. Caesium‐137 was not significantly related to the amount of sand, silt, or clay, the bulk density, the organic matter content, the slope angle or the relative distance downslope. However, 137Cs was significantly related to the thickness of the soil A horizon. Spatial variations in 137Cs were compared with topographic units and a six‐element hillslope model, but there was little correspondence. It was thought that the effects of microtopography could have masked potential interrelationships between 137Cs and broader scale landform parameters.
Similarity analysis and scaling: An application to soil infiltration properties
Authors: Li Changxing , Shen Jin
Published: February 2007

Similarity and scaling theory are applied to soil physics, specifically to several parameters of unsaturated soil water movement. Following a dimensional analysis of Richards' equation, a mechanical similarity criterion of the hydraulic parameters is developed. Dimensionless factors which conform to assumptions of kinematic and dynamic mechanical similarity in the flow system are converted to relations using the scale factor a derived under the assumption of geometric similarity. As an example, the infiltration process is assessed through scaling of the parameters in Philip's equation, using experimental data from double‐ring infiltration measurements at 54 locations in a study catchment as the scaling test.
Hydrological and hydrochemical response of mountainous basins to snow accumulation and melting in northern slovakia
Authors: Babiaková G. , Bodiš D. , Palkovič D.
Published: February 2007

Hydrological and hydrochemical parameters for two mountain basins are presented and compared. The analysis focuses on the hydrology during the winter, the cumulative outflow of sulphate and nitrate from the basin and a mass balance. An integrated model for the simulation of the amount and quality of snowmelt from seasonal snow cover is briefly described. The possible application of the model to other basins is considered.
Capturing the essential spatial variability in distributed hydrological modelling: Infiltration parameters
Authors: Farajalla Nadim S. , Vieux Baxter E.
Published: February 2007

Selecting the correct resolution in distributed hydrological modelling at the watershed scale is essential in reducing scale‐related errors. The work presented herein uses information content (entropy) to identify the resolution which captures the essential variability, at the watershed scale, of the infiltration parameters in the Green and Ampt infiltration equation. A soil map of the Little Washita watershed in south‐west Oklahoma, USA was used to investigate the effects of grid cell resolution on the distributed modelling of infiltration. Soil‐derived parameters and infiltration exhibit decreased entropy as resolutions become coarser. This is reflected in a decrease in the maximum entropy value for the reclassified/derived parameters vis a vis the original data. Moreover, the entropy curve, when plotted against resolution, shows two distinct segments: a constant section where no entropy was lost with decreasing resolution and another part which is characterized by a sharp decrease in entropy after a critical resolution of 1209 m is reached. This methodology offers a technique for assessing the largest cell size that captures the spatial variability of infiltration parameters for a particular basin. A geographical information system (GIS) based rainfall‐runoff model is used to simulate storm hydrographs using infiltration parameter maps at different resolutions as inputs. Model results up to the critical resolution are reproducible and errors are small. However, at resolutions beyond the critical resolution the results are erratic with large errors. A major finding of this study is that a large resolution (1209 m for this basin) yields reproducible model results. When modelling a river basin using a distributed model, the resolution (grid cell size) can drastically affect the model results and calibration. The error structure attributable to grid cell resolution using entropy as a spatial variability measure is shown.
Hydrochemical and water source variations across a floodplain mire, Insh Marshes, Scotland
Authors: Grieve Ian C. , Gilvear David G. , Bryant Robert G.
Published: February 2007

Groundwater heads and chemical composition were measured at approximately two week intervals during the summer of 1993 along a 1 km transect across the Insh Marshes floodplain mire in Inverness‐shire, Scotland. Groundwater heads were generally higher near the valley side slope, with lower pH values and greater dissolved organic carbon, A1 and C1 concentrations. In the centre of the transect, upward groundwater heads were identified and pH, conductivity and concentrations of base cations were much greater. Near the River Spey, pH and base cation concentrations decreased and A1 and C1 concentrations increased. Deep groundwater followed a similar spatial trend but was generally more base‐rich than shallow groundwater. These variations reflect the influence of three major water sources with different chemical signatures. Runoff from the valley side slope increased dissolved organic carbon and A1 in the shallow groundwater, the upward flow of groundwater increased the pH and Ca concentration and inundation near the river decreased the base status and increased C1 and A1.
Effects of ice‐front collapse and flood generation on a proglacial river channel near kangerlussuaq (Søndre Strømfjord), west greenland
Authors: Russell Andrew J. , Van Tatenhove Frank G. M. , Van De Wal Roderik S. W.
Published: February 2007

River discharge measurements downstream of the Russell Glacier, near Kangerlussuaq (Søndre Strømfjord), West Greenland revealed the occurrence of short‐term discharge fluctuations during the 1991 melt season. Frontal ice‐cliff collapse results in temporary river damming, producing initial decreases in discharge and subsequent sudden flood peaks on dam failure. Fluctuations are less than two hours in duration, with a maximum discharge fluctuation magnitude of 50m3s−1, double that of normal ablation‐controlled diurnal fluctuations. As such, these events are exceeded in magnitude only by periodic jökulhlaups resulting from the drainage of an ice‐dammed lake further up‐glacier. The concentration of discharge fluctuations at the beginning of the melt season, the large number of ice blocks within the flow and the confinement of flows between ice block levees all add to the effectiveness of these events in terms of channel erosion and sediment transport.
A process‐based model for colluvial soil depth and shallow landsliding using digital elevation data
Authors: Dietrich William E. , Reiss Robert , Hsu Mei‐Ling , Montgomery David R.
Published: February 2007

A model is proposed for predicting the spatial variation in colluvial soil depth, the results of which are used in a separate model to examine the effects of root strength and vertically varying saturated conductivity on slope stability. The soil depth model solves for the mass balance between soil production from underlying bedrock and the divergence of diffusive soil transport. This model is applied using high‐resolution digital elevation data of a well‐studied site in northern California and the evolving soil depth is solved using a finite difference model under varying initial conditions. The field data support an exponential decline of soil production with increasing soil depth and a diffusivity of about 50 cm2/yr. The predicted pattern of thick and thin colluvium corresponds well with field observations. Soil thickness on ridges rapidly obtain an equilibrium depth, which suggests that detailed field observations relating soil depth to local topographic curvature could further test this model. Bedrock emerges where the curvature causes divergent transport to exceed the soil production rate, hence the spatial pattern of bedrock outcrops places constraints on the production law.

The infinite slope stability model uses the predicted soil depth to estimate the effects of root cohesion and vertically varying saturated conductivity. Low cohesion soils overlying low conductivity bedrock are shown to be least stable. The model may be most useful in analyses of slope instability associated with vegetation changes from either land use or climate change, although practical applications may be limited by the need to assign values to several spatially varying parameters. Although both the soil depth and slope stability models offer local mechanistic predictions that can be applied to large areas, representation of the finest scale valleys in the digital terrain model significantly influences local model predictions. This argues for preserving fine‐scale topographic detail and using relatively fine grid sizes even in analyses of large catchments.
Catchment‐scale runoff generation model by aggregation and similarity analyses
Authors: Robinson Justin S. , Sivapalan Murugesu
Published: February 2007

Runoff generation in natural catchments due to storm rainfall is highly complex and spatially and temporally heterogeneous. In recent work on seven small experimental catchments Larsen et al. (1994) showed that underlying the heterogeneity of runoff generation within the catchments, there is a degree of regularity between the catchments that could be quantified in terms of two dimensionless similarity parameters K0* and f*. These two parameters, constants for a catchment, were able to characterize the relative dominance of the saturation excess (Dunne‐type) and infiltration excess (Horton‐type) mechanisms of runoff generation. Given that K*0 and f* can characterize the type of runoff generation on any catchment, it may follow that they can be used to define a catchment‐scale runoff generation model. This idea is pursued in this paper. For the same catchments as studied by Larsen et al. (1994), a lumped, physically based model is developed that describes both the extent of saturated areas and the average infiltration capacity of the unsaturated areas during a storm. This is achieved by utilizing the distributed model used by Larsen et al. (1994) to aggregate the point‐scale runoff generation responses, up to the catchment scale, from which the functional form and the parameters of the catchment‐scale runoff generation model are inferred. The parameters of this lumped model are defined entirely in terms of the underlying distribution of topography, three similarity parameters K*0, f* and B*, the normalized average water‐table depth, z*, and the normalized cumulative volume of infiltration, G*.
Estimation of actual evaporation using precipitation and soil moisture records in arid climates
Authors: Sorman A. U. , Abdulrazzak M. J.
Published: February 2007

There is little knowledge available about infiltration and evaporation processes in wadi channels in arid regions. This work was conducted to determine the actual evaporation from bare soils in wadi channels in the south‐western region of the Kingdom of Saudi Arabia. The estimation of soil evaporation is highly dependent on the availability of moisture in the upper layers of alluvial wadis, in which the areal rainfall, flood hydrograph and soil properties play a significant part.

The study was conducted by estimating the actual evaporation using soil moisture data, precipitation and runoff depths in a representative basin. The results are compared with potential rates. The actual rates were 1.5 mm/day immediately after a rainy day and then decreased to 0.42 mm/day. The minimum rate was about 0.1–0.2 mm/day during the dry season. The potential rates were about 9.5 mm/day in June and July, decreasing to 3.5 mm/day in December and January.
Hydrological characteristics of a moso‐bamboo (Phyllostachys pubescens) forest in south china
Authors: Wang Yanhui , Liu Yongmin
Published: February 2007

Since 1986 the multiple benefits of moso‐bamboo forest, a special forest type found mainly in south China, have been investigated in a small 11.7 ha watershed in Fenyi County, Jiangxi Province. The mean annual precipitation in the study area is 1593.3 mm. For the 0–60 cm soil layer the average soil bulk density is 1.00 g/cm3, and the mean values for other soil properties are: total porosity 71.74%; non‐capillary porosity 5.81%; and water retention capacity 430 mm. The maximum effective water retention capacity of 313 mm is 28% higher than that for Chinese fir (Cunninghamia lanceolata) plantations and natural broadleaved forest in the neighbouring area. The parameters f0, fc and k, in Horton's infiltration equation, measured using the double‐ring method under drought conditions, are 29.10 mm/min, 8.28 mm/min and 0.2391, respectively. These infiltration properties are more favourable than those under nearby Chinese fir plantations.

Compared with a Chinese fir plantation, the canopy interception ratio of moso‐bamboo is lower, but the stemflow ratio is higher. The annual canopy interception ratio is 11.1%. Because of snowfall, the interception ratios in January, February and March are higher, with values of 12.1–17.2%, whereas during the period of leaf fall in April, May and June the interception ratios are lower with values of 9.2–9.5%. During the other months they are relatively constant. The annual stemflow ratio is 4.4%. Again, because of snowfall, the stemflow ratios in January, February and March are lower with values of 2.8–2.9%, whereas during the remaining months they are fairly constant.

Runoff analysis shows that the annual runoff ratio in this research watershed is 54.8%, but the ratio for quick runoff, composed of direct runoff and surface runoff, is only 0.8%. The upper interflow ratio is 15% and the ratio for the slow runoff composed of deeper interflow and underflow is 39%. The moso‐bamboo forest is very effective in reducing peak runoff and increasing low flows.

The annual nutrient element inputs (kg/ha) to the moso‐bamboo forest ecosystem associated with throughfall and stemflow are N 17.7, P 0.38, K 56.5, Ca 31.,4, Mg 4.8 and SiO2 26.2, respectively. All the measured element inputs, with the exception of P, are higher than those associated with precipitation in the open, where typical values are N 10.1, P 0.89, K 18.8, Ca 25.8, Mg 3.1 and SiO2 10.1. The annual outputs in streamflow are N 3.0, P 0.28, K 16.6, Ca 38.9, Mg 8.3 and SiO2 125.7, indicating that for N, P and K the moso‐bamboo forest ecosystem is an accumulating system, whereas for Ca, Mg and SiO2 the reverse applies. All the pH values associated with precipitation in the open, throughfall, stemflow, surface runoff from runoff plots and streamflow in the research watershed vary between 6.45 and 7.60 and are close to neutral.
Distributed snow process modelling: An image processing approach
Authors: Davis Robert E. , McKenzie Judy Ceretha , Jordan Rachel
Published: February 2007

An approach to spatially distribute a snow process model by segmenting images of land cover, terrain and snow properties is reported. A small 1.7 ha study area with an existing database was selected for this preliminary evaluation. The methodology was carried out over a relatively flat valley bottom at Camp Grayling, Michigan. Meteorological measurements on two sides of the area showed only small differences, so uniform meteorological variables were assumed over the site. Initial snow cover conditions were reconstructed and were distributed over the area using snow maps and sparse snow pit measurements. One metre resolution terrain, soil, vegetation and snow type maps were individually processed into class maps. These layers were then combined to produce a segmented class map, where the attributes from the data layers were known for each class. A one‐dimensional model of snow processes was run for each class, then the results were mapped back into images. Shallow snow conditions provided high sensitivity of ablation patterns to meteorological conditions over a 72 h period. The model performance was assessed by comparing predicted and observed ablation patterns. The error in total snow‐covered area was less than 9%. However, the location errors were greater (predicted snow where no snow was observed and observed snow where no snow was predicted). Extensive error analysis was not justified because of the lack of multiple point measurements of snow properties.
Cytoskeleton and paclitaxel sensitivity in breast cancer: The role of β‐tubulins
Authors: Tommasi Stefania , Mangia Anita , Lacalamita Rosanna , Bellizzi Antonia , Fedele Vita , Chiriatti Annalisa , Thomssen Christopher , Kendzierski Nancy , Latorre Agnese , Lorusso Vito , Schittulli Francesco , Zito Francesco , Kavallaris Maria , Paradiso Angelo
Published: February 2007

The antineoplastic effect of paclitaxel is mainly related to its ability to bind the β subunit of tubulin, thus preventing tubulin chain depolarization and inducing apoptosis. The relevance of the Class I β‐tubulin characteristics have also been confirmed in the clinical setting where mutations of paclitaxel‐binding site of β‐tubulin Class I have been related to paclitaxel resistance in non small cell lung and ovarian cancers. In the present study, we verified the hypothesis of a relationship between molecular alterations of β‐tubulin Class I and paclitaxel sensitivity in a panel of breast cell lines with different drug IC50. The Class I β‐tubulin gene cDNA has been sequenced detecting heterozygous missense mutations (exon 1 and 4) only in MCF‐7 and SK‐BR‐3 lines. Furthermore, the expression (at both mRNA and protein level) of the different isotypes have been analyzed demonstrating an association between low cell sensitivity to paclitaxel and Class III β‐tubulin expression increasing. Antisense oligonucleotide (ODN) experiments confirmed that the inhibition of Class III β‐tubulin could at least partially increase paclitaxel‐chemosensitivity. The hypothesis of a relationship between β‐tubulin tumor expression and paclitaxel clinical response has been finally verified in a series of 92 advanced breast cancer patients treated with a first line paclitaxel‐based chemotherapy. Thirty‐five percent (95% CI: 45–31) of patients with high Class III β‐tubulin expression showed a disease progression vs. only 7% of patients with low expression (35% vs. 7%, p < 0.002). Our study suggests that Class III β‐tubulin tumor expression could be considered a predictive biomarker of paclitaxel‐clinical resistance for breast cancer patients. © 2007 Wiley‐Liss, Inc.
Bone tissue engineering with human mesenchymal stem cell sheets constructed using magnetite nanoparticles and magnetic force
Authors: Shimizu Kazunori , Ito Akira , Yoshida Tatsuro , Yamada Yoichi , Ueda Minoru , Honda Hiroyuki
Published: February 2007

An in vitro reconstruction of three‐dimensional (3D) tissues without the use of scaffolds may be an alternative strategy for tissue engineering. We have developed a novel tissue engineering strategy, termed magnetic force‐based tissue engineering (Mag‐TE), in which magnetite cationic liposomes (MCLs) with a positive charge at the liposomal surface, and magnetic force were used to construct 3D tissue without scaffolds. In this study, human mesenchymal stem cells (MSCs) magnetically labeled with MCLs were seeded onto an ultra‐low attachment culture surface, and a magnet (4000 G) was placed on the reverse side. The MSCs formed multilayered sheet‐like structures after a 24‐h culture period. MSCs in the sheets constructed by Mag‐TE maintained an in vitro ability to differentiate into osteoblasts, adipocytes, or chondrocytes after a 21‐day culture period using each induction medium. Using an electromagnet, MSC sheets constructed by Mag‐TE were harvested and transplanted into the bone defect in the crania of nude rats. Histological observation revealed that new bone surrounded by osteoblast‐like cells was formed in the defect area 14 days after transplantation with MSC sheets, whereas no bone formation was observed in control rats without the transplant. These results indicated that Mag‐TE could be used for the transplantation of MSC sheets using magnetite nanoparticles and magnetic force, providing novel methodology for bone tissue engineering. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2007
Inhibitory effects of root canal sealers on the expression of inducible nitric oxide synthase in lipopolysaccharide‐stimulated murine macrophage cells
Authors: Lee Dong Hee , Lim Bum‐Soon , Lee Yong‐Keun , Kim Na Ryoung , Yang Hyeong‐Cheol
Published: February 2007

Excessive production of nitric oxide (NO) is associated with inflammation. In the present study, we examined the effects of root canal sealers (N2 Universal, Sealapex, and AH26) on NO production and inducible NO synthase (iNOS) expression in lipopolysaccharide (LPS)‐stimulated RAW 264.7 macrophages. Root canal sealers decreased NO synthesis in LPS‐induced RAW 264.7 macrophages in a dose‐dependent manner. RT‐PCR and Western blot analysis demonstrated markedly lower levels of iNOS mRNA and protein in LPS‐activated macrophage cells treated with root canal sealers compared with untreated cells. From these results, we conclude that root canal sealers do not inhibit NO synthesis by direct inhibition of the enzyme, but rather through inhibition of iNOS mRNA expression (leading to a decrease in iNOS protein expression). Our data, therefore, suggest that root canal sealers may be an effective inhibitor of LPS‐induced inflammatory effects in macrophage cells. Further in vitro and in vivo studies are necessary to confirm the effects of root canal sealers on the inflammatory processes. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Heparin‐induced thrombocytopenia: An autoimmune disorder regulated through dynamic autoantigen assembly/disassembly
Authors: Cines Douglas B. , Rauova Lubica , Arepally Gowthami , Reilly Michael P. , McKenzie Steven E. , Sachais Bruce S. , Poncz Mortimer
Published: February 2007

Heparin‐induced thrombocytopenia (HIT) is the most common drug‐induced, antibody‐mediated cause of thrombocytopenia and thrombosis. HIT is caused by IgG antibodies that bind to epitopes on platelet factor 4 (PF4) released from activated platelets that develop when it forms complexes with heparin. Anti‐PF4/antibodies develop in over 50% of patients undergoing surgery involving cardiopulmonary bypass (CPB), an incidence 20‐fold higher than HIT. Why might this occur? Binding of HIT IgG occurs only over a narrow molar ratio of reactants, being optimal at 1 mol PF4 tetramer to 1 mol unfractionated heparin (UFH). At these ratios, PF4 and UFH form ultralarge (>670 kD) complexes that bind multiple IgG molecules/complex, are highly antigenic, and promote platelet activation. Low molecular weight heparin (LMWH), which is less antigenic, forms ultralarge complexes less efficiently and largely at supratherapeutic concentrations. In transgenic mice that vary in expression of human PF4 on their platelets, antigenic complexes form between PF4 and endogenous chondroitin sulfate. Binding of HIT IgG to platelets and induction of thrombocytopenia in vivo is proportional to PF4 expression. Heparin prolongs the duration and exacerbates the severity of the thrombocytopenia. High doses of heparin, as used in CPB, or protamine, which competes with PF4 for heparin, disrupts antigen formation and prevents thrombocytopenia induced by HIT antibody. These studies may help explain the disparity between the incidence of antibody formation and clinical disease and may help identify patients at risk for HIT (high platelet PF4). They also demonstrate that this autoimmune disease can be modulated at the level of autoantigen formation and point to rational means to intervene proximal to thrombin generation. J. Clin. Apheresis. 22:, 2007 © 2007 Wiley‐Liss, Inc.
Cyclic voltammetry modeling, geometries, and electronic properties for metallofullerene complexes with μ3‐η2:η2:η2‐C60 bonding mode
Authors: Kim Kyoung Hoon , Jung Jaehoon , Park Bo Keun , Han Young‐Kyu , Park Joon T.
Published: February 2007

Reduction potential (Ered) values have been calculated and compared with available cyclic voltammetry (CV) data for 10 metallofullerene complexes with the μ3‐η2:η2:η2‐C60 (M3C6[C60]) bonding mode. Consideration of bulk solvent effects is essential for the calculation of the Ered values. Scaling factors for the electrostatic terms of the solvation energies have been introduced to fully describe the experimental cyclic voltammograms with a small mean deviation of 0.07 V. Multiple electron reductions induce movement of the metal cluster moieties on the C60 surface, which is accompanied with the changes in some MC[C60] bonds from π‐type to σ‐type mode. However, the changes in M3C60 distances, as well as the geometric changes of M3 and C60, are small for the reductions, which is in harmony with the high chemical and electrochemical stability of the metallofullerenes. Our population analyses reveal that the added electrons are not localized at the C60 moieties, and electron population in the metal clusters is significant, more than 20% (av. 37%), for all the reductions. Furthermore, we demonstrated that the two close one‐electron redox waves in CV diagrams are strongly correlated with significant electron delocalization, about 40–80%, to the metal‐cluster moieties in these metallofullerene complexes. © 2007 Wiley Periodicals, Inc. J Comput Chem 2007
Nanobeam electron diffraction and high resolution imaging analysis of InN films grown on sapphire
Authors: Liu Zongwen , Kinsey Robert J. , Durbin Steven M. , Ringer Simon P.
Published: February 2007

A JEOL JEM‐3000F field emission, analytical, high‐resolution transmission electron microscope (HRTEM) was used to study InN films grown on sapphire substrates. It was found that, while the InN films maintained the hexagonal (wurtzite) structure, InN nanodomains with a cubic (zincblende) structure were also formed in the films. Nanobeam electron diffraction techniques were applied for identification of the cubic phase. The identification of the cubic InN was confirmed by HRTEM structural imaging. The cubic InN nanodomains are 3–10 nm in diameter, and are orientated in two different orientations with their [110]cubic and [110]cubic axes parallel to each other and their (111)cubic planes parallel to the (0001)hex plane of the hexagonal InN. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Evanescent fields—Direct measurement, modeling, and application
Authors: Huntington S.T. , Ladouceur F.
Published: February 2007

The evanescent field surrounding an exposed planar waveguide in silica is accurately measured using scanning near field optical microscopy (SNOM) and compared to models of the field distribution. Distortions in the field due to edge effects and the proximity of the mode to the surface are all detected. The characterized field is use to quantitatively explore the difference in collection efficiency between contact mode SNOM and intermittent contact mode SNOM. A strong correlation between tip oscillation amplitude and detection efficiency is determined. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
New developments in electron energy loss spectroscopy
Authors: Keast V.J. , Bosman M.
Published: February 2007

In the electron microscope, spectroscopic signals such as the characteristic X‐rays or the energy loss of the incident beam can provide an analysis of the local composition or electronic structure. Recent improvements in the energy resolution and sensitivity of electron spectrometers have improved the quality of spectra that can be obtained. Concurrently, the calculations used to simulate and interpret spectra have made major advances. These developments will be briefly reviewed. In recent years, the focus of analytical electron microscopy has moved away from single spectrum acquisition to mapping and imaging. In particular, the use of spectrum imaging (SI), where a full spectrum is acquired and stored at each pixel in the image is becoming widespread. A challenge for the application of spectrum imaging is the processing of such large datasets in order to extract the significant information. When we go beyond the mapping of composition and look to map bonding and electronic structure this becomes both more important and more difficult. Approaches to processing spectrum imaging data sets acquired using electron energy loss spectroscopy (EELS) will be explored in this paper. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Fluorescence lifetime imaging of coral fluorescent proteins
Authors: Cox Guy , Matz Mikhail , Salih Anya
Published: February 2007

Corals, like many other coelenterates, contain fluorescent pigments that show considerable homology with the well known green fluorescent protein of the jellyfish Aequoria. In corals, unlike jellyfish, multiple proteins are present and the range of excitations and emissions suggest the possibility of energy transfer. The occurrence of Förster resonant energy transfer (FRET) between fluorescent proteins in corals has already been reported and time‐resolved spectra have shown the effect on fluorescent lifetime, but without any spatial resolution. Lifetime confocal microscopy offers lower time resolution but excellent spatial resolution. Lifetimes of the isolated A. millepora pigments amilFP490, amilFP504, and amilFP593 (names indicate emission peaks) were 2.8, 2.9, and 2.9 ns, respectively. In the coral sample, imaging the entire emission spectrum from 420 nm, the mean lifetime was reduced to 1.5 ns, implying that FRET was occurring. Looking just at the fluorescence from FRET donors the lifetime was even shorter, at 1.3 ns, supporting this interpretation. In contrast, no reduction in lifetime is seen in the coral Euphyllia ancora, where the pigment distribution also suggests that the pigments are unlikely to be involved in photoprotection. This study set out to determine the extent of FRET between pigments in two corals, Acropora millepora and Euphyllia, ancora which differ in the arrangement of their pigments and hence possibly in pigment function. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Spatial Distribution of Actin and Tubulin in Human Sperm Nuclear Matrix‐intermediate Filament Whole Mounts—A New Paradigm
Authors: Kadam Kaushiki , D'souza Serena , Natraj Usha
Published: February 2007

Sperm is a highly differentiated cell streamlined for fertilization. The function is thus heavily dependent on the cytoskeletal organization. Conventional methods limit the appreciation and correlation of this intricate cytoskeletal filament network in the context of an entire sperm. Our recent successful localization of nonmuscle myosin IIA on sperm nuclear matrix‐intermediate filament (NM‐IF) preparations from fertile men by embedment‐free electron microscopy (EF‐EM), prompted us to investigate the antigenic distribution of two major cytoskeletal proteins—actin and tubulin. The NM‐IF preparations were subjected to a cocktail of buffered paraformaldehyde (2%) with a low concentration of glutaraldehyde (0.05%). These proteins were localized by indirect immunogold technique using EF‐EM on sperm NM‐IF whole mounts. Ultrastructure analysis revealed well preserved centrioles, outer dense fibers, axonemal filaments, and submitochondrial reticulum in the sperm NM‐IF. Immunoreactive actin was localized along the length of the sperm whereas β‐tubulin was present in the axoneme alone. The spatial distribution of actin and tubulin in normal human sperm NM‐IF reported here together with that of myosin on whole mount offers a powerful technique to understand sperm cytoskeletal supramolecular structure. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Selective maximization of 31P MR spectroscopic signals of in vivo human brain metabolites at 3T
Authors: Blenman Rose‐Ann M. , Port John D. , Felmlee Joel P.
Published: February 2007

Purpose

To develop a short TR, short TE, large flip angle (LFA), in vivo 31P MR spectroscopy (MRS) technique at 3T that selectively maximizes the signal‐to‐noise ratio (SNR) of long T1 human brain metabolites implicated in bipolar disorder.

Materials and Methods

Two pulse sequences were evaluated for efficiency. Slice profiles acquired with the scaled, sinc‐shaped, radiofrequency (RF) LFA pulses were compared to those acquired with Shinnar‐Le Roux (SLR) RF LFA pulses. The SLR‐based LFA pulse sequence was used to maximize the inorganic phosphate signal in a phantom, after which volunteer metabolite signals were selectively maximized and compared to their correlates acquired with conventional spin‐echo methods.

Results

The comparison of slice profiles acquired with sinc‐shaped RF LFA pulses vs. SLR RF LFA pulses showed that SLR‐based pulse sequences, with their improved excitation and slice profiles, yield significantly better results. In vivo LFA spin‐echo MRS implemented with SLR pulses selectively increased the 31P MRS signal, by as much as 93%, of human brain metabolites that have T1 times longer than the TR of the acquisition.

Conclusion

The data show that the LFA technique can be employed in vivo to maximize the signal of long T1
31P brain metabolites at a given TE and TR. LFAs ranging between 120° and 150° are shown to maximize the 31P signal of human brain metabolites at 3T. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Cyclic guanosine monophosphate signalling pathway plays a role in neural cell adhesion molecule‐mediated neurite outgrowth and survival
Authors: Ditlevsen Dorte Kornerup , Køhler Lene Boding , Berezin Vladimir , Bock Elisabeth
Published: February 2007

The neural cell adhesion molecule (NCAM) plays a crucial role in neuronal development, regeneration, and synaptic plasticity associated with learning and memory consolidation. Homophilic binding of NCAM leads to neurite extension and neuroprotection in various types of primary neurons through activation of a complex network of signalling cascades, including fibroblast growth factor receptor, Src‐family kinases, the mitogen‐activated protein kinase pathway, protein kinase C, phosphatidylinositol‐3 kinase, and an increase in intracellular Ca2+. Here we present data indicating an involvement of cyclic GMP in NCAM‐mediated neurite outgrowth in both hippocampal and dopaminergic neurons and in NCAM‐mediated neuroprotection of dopaminergic neurons. In addition, evidence is presented suggesting that NCAM mediates activation of cGMP via synthesis of nitric oxide (NO) by NO synthase (NOS) and activation of soluble guanylyl cyclase by NO, leading to an increased synthesis of cGMP and activation by cGMP of protein kinase G. © 2007 Wiley‐Liss, Inc.
Insulin‐like growth factor‐I ameliorates demyelination induced by tumor necrosis factor‐α in transgenic mice
Authors: Ye Ping , Kollias George , D'Ercole A. Joseph
Published: February 2007

Our groups have reported that tumor necrosis factor‐α (TNF‐α) causes myelin damage and apoptosis of oligodendrocytes and their precursors in vitro and in vivo. We also have reported that insulin‐like growth factor‐I (IGF‐I) can protect cultured oligodendrocytes and their precursors from TNF‐α‐induced damage. In this study, we investigated whether IGF‐I can protect oligodendrocytes and myelination from TNF‐α‐induced damage in vivo by cross‐breeding TNF‐α transgenic (Tg) mice with IGF‐I Tg mice that overexpress IGF‐I exclusively in brain. At 8 weeks of age, compared with those of wild‐type (WT) mice, the brain weights of TNF‐α Tg mice were decreased by ∼20%, and those of IGF‐I Tg mice were increased by ∼20%. The brain weights of mice that carry both TNF‐α and IGF‐I transgenes (TNF‐α/IGF‐I Tg mice) did not differ from those of WT mice. As judged by histochemical staining and immunostaining, myelin content in the cerebellum of TNF‐α/IGF‐I Tg mice was similar to that in WT mice and much more than that in TNF‐α Tg mice. Consistently, Western immunoblot analysis showed that myelin basic protein (MBP) abundance in the cerebellum of TNF‐α/IGF‐I Tg mice was double that in TNF‐α Tg mice. In comparison with WT mice, the number of oligodendrocytes was decreased by ∼36% in TNF‐α Tg mice, whereas it was increased in IGF‐I Tg mice by ∼40%. Oligodendrocyte number in TNF‐α/IGF‐I Tg mice was almost twice that in TNF‐α Tg mice. Furthermore, IGF‐I overexpression significantly reduced TNF‐α‐induced increases in apoptotic cell number, active caspase‐3 abundance, and degradaion of MBP. Our results indicate that IGF‐I is capable of protecting myelin and oligodendrocytes from TNF‐α‐induced damage in vivo. © 2007 Wiley‐Liss, Inc.
Oxidative damage in nucleic acids and Parkinson's disease
Authors: Nakabeppu Yusaku , Tsuchimoto Daisuke , Yamaguchi Hiroo , Sakumi Kunihiko
Published: February 2007

Oxidative DNA lesions, such as 8‐oxoguanine (8‐oxoG), accumulate in nuclear and mitochondrial genomes during aging, and such accumulation can increase dramatically in patients with Parkinson's disease (PD). To counteract oxidative damage to nucleic acids, human and rodents are equipped with three distinct enzymes. One of these, MTH1, hydrolyzes oxidized purine nucleoside triphosphates, such as 8‐oxo‐2′‐deoxyguanosine triphosphate and 2‐hydroxy‐2′‐deoxyadenosine triphosphate, to their monophosphate forms. The other two enzymes are 8‐oxoG DNA glycosylase encoded by the OGG1 gene and adenine/2‐hydroxyadenine DNA glycosylase encoded by the MUTYH gene. We have shown a significant increase in 8‐oxoG in mitochondrial DNA as well as an elevated expression of MTH1, OGG1, and MUTYH in nigrostriatal dopaminergic neurons of PD patients, suggesting that the buildup of these lesions may cause dopamine neuron loss. We established MTH1‐null mice and found that MTH1‐null fibroblasts were highly susceptible to cell death caused by H2O2 characterized by pyknosis and electron‐dense deposits in the mitochondria, and that this was accompanied by an ongoing accumulation of 8‐oxoG in nuclear and mitochondrial DNA. We also showed that MTH1‐null mice exhibited an increased accumulation of 8‐oxoG in striatal mitochondrial DNA, followed by more extreme neuronal dysfunction after 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine administration than that of wild‐type mice. In conclusion, oxidative damage in nucleic acids is likely to be a major risk factor for Parkinson's disease, indicating that a solid understanding of the defense mechanisms involved will enable us to develop new strategies for protecting the brain against oxidative stress. © 2007 Wiley‐Liss, Inc.
Degradation of phenolic compounds by the yeast Candida tropicalis HP 15 I. Physiology of growth and substrate utilization
Authors: Krug M. , Ziegler H. , Straube G.
Published: February 2007

The yeast Candida tropicalis HP 15 was able to utilize phenol up to concentrations of 2.5 g/l as a sole carbon and energy source. Phenol was metabolized via the β‐ketoadipate pathway by an inducible enzyme system.

Besides phenol, resorcinol, quinol, hydroxyquinol, catechol, and to a lesser extend 4‐chloro‐catechol, protocatechuate, p‐cresol, m‐chlorophenol, and p‐chlorophenol were metabolized by the yeast. A total of 30 aromatic compounds were tested as substrates.
Eisenaufnahme durch Salmonella typhimurium‐Stämme unterschiedlicher epidemiologischer Herkunft
Authors: Rabsch W. , Reissbrodt R.
Published: February 2007

All Salmonella typhimurium strains tested were able to use iron from transferrin. In buffered nutrient broth — poor in iron‐content — the strains were tested in 59FeCl3 and 59Fe‐transferrin uptake in different growth phases. In the early log phase the strains are able to catch the 59Fe3+ in a very great amount as it is necessary for the growth. The content of 59Fe per cell was in the late log phase reduced until to a value, which seen to be enough for growth. The acquisition of 59Fe‐transferrin between the early and late log phase tested by 4 S. typhimurium strains was different.
Wachstumsuntersuchungen im substratlimitierten pH‐Auxostaten I. Bistabiles Wachstumsverhalten unter kaliumlimitierten Bedingungen
Authors: Büttner R. , Uebel B. , Genz I.‐L. , Köhler M.
Published: February 2007

The substrate‐limited pH‐auxostat as a new method of continuous culture is introduced. It is the feature of this method that two medium solutions are given to the culture. The first contains the limiting substrate only and flow to the culture with a constant rate. The second, which contains all other substrates, is given over the pH‐auxostat principle.

A bistability in the growth of yeast under potassium‐limited conditions was found and discussed.
Maintenance of the recombinant plasmid pIJ2 in chemostat cultures of Streptomyces lividans 66 (pIJ2)
Authors: Roth M. , Noack D. , Geuther R.
Published: February 2007

The maintenance of the recombinant plasmid pIJ2 in chemostat cultures of Streptomyces lividans 66 (pIJ2) was investigated. The presence of the plasmid coding for a neomycin phosphotransferase was detected by plating samples from the continuous cultures on nonselective and selective agar medium containing neomycin.

The plasmid was lost from the host strain under all conditions tested. However, the kinetics of the plasmid segregation from the chemostat populations were dependent on the growth‐limiting substrate of the medium, the dilution rate of the continuous culture and the cultivation temperature.

Size differences between the original plasmid and plasmid DNA isolated from neomycin‐resistant clones after long‐term chemostat cultivation were not observed. In neomycin‐sensitive clones no extrachromosomal DNA was found.
Regulation of chorismate mutase, prephenate dehydrogenase and prephenate dehydratase of Candida maltosa
Authors: Bode R. , Melo C. , Birnbaum D.
Published: February 2007

The enzymes of the phenylalanine‐tyrosine pathway were partially purified from Candida maltosa and the regulatory patterns were established. Chorismate mutase (Mr 63,000), prephenate dehydrogenase (Mr 75,000) and prephenate dehydratase (Mr 88,000) were separated from each other. The formation of chorismate mutase was only regulated by a general control of amino acid biosynthesis, whereas the synthesis of prephenate dehydrogenase and prephenate dehydratase was constitutive. Both chorismate mutase and prephenate dehydrogenase were activated by tryptophan and by methylated or fluorinated tryptophan analogues. l‐tyrosine as well as α‐methyl‐dl‐tyrosine inhibited the activity of both enzymes. Prephenate dehydratase activity was stimulated by l‐tryptophan and by methylated tryptophan derivatives and inhibited by d‐tryptophan or 5‐fluorotryptophan. In contrast to chorismate mutase, the double‐reciprocal curves of substrate saturation of which were hyperbolical (positive cooperativity), prephenate dehydrogenase and prephenate dehydratase showed linear curves of substrate saturation, indicating normal Mi‐chaelis kinetics.
Bacterial resistance to streptothricins
Authors: Haupt I. , Thrum H.
Published: February 2007

Resistance to streptothricin was studied in bacteria with different resistance mechanisms. The laboratory‐induced streptothricin‐resistant mutant E. coli A19 Stcr 2/2/1 showed a high level of cross‐resistance to aminoglycosides and other miscoding inducing antibiotics. In contrast, amino‐glycosid‐resistant E. coli strains with plasmid‐determined aminoglycoside modifying enzymes were sensitive to streptothricin. Enzymatic inactivation of streptothricin by acetylation was demonstrated for the streptothricin producing Streptomyces noursei, strain NG13. This strain showed no cross‐resistance to miscoding inducing aminoglycosides.
Synthese der alkalischen Phosphatase in einem stringent und relaxed kontrollierten Stamm von Escherichia coli nach Aminosäuren‐ und Phosphatlimitation
Authors: Hecker M. , Schroeter A.
Published: February 2007

Synthesis of alkaline phosphatase in Escherichia coli is derepressed under phosphate starvation in the stringent strain CP78 as well as in its relaxed counterpart CP79. During limitation of phosphate as well as of amino acids a decrease of enzyme activity is observed, especially in the relaxed strain, which can not produce ppGpp under this conditions.

After phosphate limitation synthesis of ppGpp is not stimulated and the kinetics of RNA synthesis is similar in both strains.

We suggest that ppGpp is not directly involved in the regulation of gene expression during phosphate starvation.
Immobilisierung partikelgebundener Aldehyddehydrogenase aus Acinetobacter calcoaceticus EB 104
Authors: Klossek P. , Kirchner M. , Kurth J.
Published: February 2007

Particle‐bound aldehyde dehydrogenase from Acinetobacter calcoaceticus was attached to octylsepharose by hydrophobic membrane proteins without previous solubilization. To optimize this method, the influence of the pH‐value of immobilization, ammonium sulfate concentration, presence of tensides, and some other substances on relative activity and yield was investigated. Best results were obtained when immobilization was carried out for 1–2 h at 4°C in 2moles/l KCl, pH 7.5. The optimum pH for storage was 9.0 and the maximum half‐life 40 days at 4°C or 18 days at 25°C.
Conjugation of tomatine with l(+)‐lactic acid by Nocardia restricta
Authors: Komel R. , Karlovšek M.
Published: February 2007

Nocardia restricta conjugates tomatines with l(+)‐lactic acid, which represents a new mode of bioconversion of steroid glycosides. The specifity in cell‐free homogenate was not restricted to α‐tomatine, since δ‐tomatine was transformed to the conjugated metabolite as well. It was shown with inhibitors of protein synthesis that the enzymes responsible for this reaction are constitutive. By using protoplasts and centrifugation it was found that the conjugating activity and the reaction products were bound to the membrane part of the 10,000 × g sediment of the cell‐free homogenate. Possible mechanisms as well as the biological significance of this reaction are discussed.
Wechselwirkungen zwischen Lektinen und Mikroorganismen I. Bestimmung der Agglutinationsgeschwindigkeit durch Extinktionsmessungen: Agglutination von Hefezellen (Saccharomyces cerevisiae H155) durch Concanavalin A
Authors: Flemming Ch. , Gabert A. , Flemming Ingeborg
Published: February 2007

A simple photometric method for the determination of the agglutination rate of cells by lectins in a continuously stirred suspension is presented. Besides the agglutination rate the method allows the estimation of an average degree of agglutination, i.e. the number of cells per aggregate. The influence of the Con A‐concentration, cell number, temperature, and pH on the agglutination rate of Saccharomyces cerevisiae H155 have been studied.

The results are of good reproducibility and, therefore, the methods is suitable to describe interactions between cell‐bound receptors and receptor‐specific proteins, e.g. lectins and antibodies.
Regulation of lipid biosynthesis in Chlorella kessleri by clomiphene
Authors: Řezanka T. , Lívanský K. , Podojil M.
Published: February 2007

During autotrophic cultivation of the alga Chlorella kessleri clomiphene1) regulated both the quantitative and qualitative production of lipids (sterols, hydrocarbons and fatty acids). Their content decreased to 57% as compared with the production of sterols in cultures without clomiphene. The production of hydrocarbons and fatty acids was similar to that on the control.

Among the sterols the variety of which enhanced the presence of clomiphene, those prevailed which carried either a double bond in position 8 or were devoid of it in position 22. In the mixture of hydrocarbons a significant increase was observed towards n‐heptadecane production. Oleic acid predominated among fatty acids.
Detection of two ornithine carbamoyltransferases in a phaseolotoxin‐producing strain of Pseudomonas syringae pv. phaseolicola
Authors: Jahn O. , Sauerstein J. , Reuter G.
Published: February 2007

The phaseolotoxin‐producing Pseudomonas syringae pv. phaseolicola strain 1321 contains two ornithine carbamoyltransferases which differ in resistance to phaseolotoxin. Whereas ornithine carbamoyltransferase 1 (OCT 1) is inhibited at low concentrations of phaseolotoxin, ornithine carbamoyltransferase 2 (OCT 2) is insensitive to phaseolotoxin. The activity of the insensitive enzyme is correlated with the amount of toxin formed.