bluuebunny/crossref_metadata_2025 huggingface dataset:
A National Survey of Genetic Counselors’ Personal Values
Authors: Pirzadeh Sara M. , McCarthy Veach Patricia , Bartels Dianne M. , Kao Juihsien , LeRoy Bonnie S.
Published: September 2007

Personal values are motivational sources for an individual's actions [Hitlin and Piliavin (Annual Review of Sociology 30:359–393, 2004)]. Genetic counselors’ values may influence their behaviors in clinical practice, but a profile of their personal values has not been identified empirically. In this study, 292 genetic counselors completed the Schwartz Universal Values Questionnaire (SUVQ; Schwartz, S. H. (1992). Universals in the content and structure of values: Theoretical advances and empirical tests in 20 countries. In M. Zanna (Ed.), Advances in experimental social psychology (pp. 1–65). Boston, MA: Academic.), a widely used measure of value types, and provided information about their demographic characteristics. Results indicate that respondents highly valued benevolence, self‐direction, achievement, and universalism indicating a strong pattern of concern for the welfare of others. They placed considerably less value on stimulation, tradition, and power, which reflect personal interests. Respondents who reported practicing a religion scored significantly lower on stimulation and hedonism and higher on tradition and spirituality than those not practicing; married respondents and parents scored significantly lower on stimulation and achievement; and males scored higher on power than females. The value types are described, and training and research recommendations are provided.
Constructions of Complex Hadamard Matrices via Tiling Abelian Groups
Authors: Matolcsi Máté , Réffy Júlia , Szöllősi Ferenc
Published: September 2007

Applications in quantum information theory and quantum tomography have raised current interest in complex Hadamard matrices. In this note we investigate the connection between tiling of Abelian groups and constructions of complex Hadamard matrices. First, we recover a recent, very general construction of complex Hadamard matrices due to Dita [2] via a natural tiling construction. Then we find some necessary conditions for any given complex Hadamard matrix to be equivalent to a Dita-type matrix. Finally, using another tiling construction, due to Szabó [8], we arrive at new parametric families of complex Hadamard matrices of order 8, 12 and 16, and we use our necessary conditions to prove that these families do not arise with Dita's construction. These new families complement the recent catalogue [10] of complex Hadamard matrices of small order.
On non-Markovian Time Evolution in Open Quantum Systems
Authors: Kossakowski Andrzej , Rebolledo Rolando
Published: September 2007

Non-Markovian reduced dynamics of an open system is investigated. In the case when the initial state of the reservoir is the vacuum state, an approximation is introduced which makes it possible to construct a reduced dynamics which is completely positive.
The Code Structure of HIV-1
Authors: Sato Keiko , Fushimi Naoki , Ohya Masanori
Published: September 2007

Information of life is stored in a genome sequence and four nucleotides can be regarded as coding elements and their sequence as a certain code of life. We study what kinds of code structure the sequences of HIV-1 genes may have.
Geometric Factors in Electromagnetic Field Commutators and the Quantum Information Control of Vacuum Fluctuations
Authors: Saavedra L. G. P.
Published: September 2007

The electromagnetic field commutation relations are defined in terms of geometric factors that are double averages over two finite four-dimensional space-time regions. The square root of any of the uncertainty relations derived from the aforementioned commutators is taken as a critical field, in the sense that any electromagnetic field much larger than it can be treated as classical. Another critical electromagnetic field associated with the quantum information control of vacuum fluctuations can be chosen as the square root of the mean quadratic fluctuation of each quantity of electromagnetic field, when the number of photons is defined and is equal to zero. Any electromagnetic field expectation value could be measured if it is much greater than the last critical field. This article covers a magnitude order comparison between the critical fields and its consequences for measuring the electromagnetic field information.
Remarks on the Equivalence of Full Additivity and Monotonicity for the Entanglement Cost
Authors: Brandão F. G. S. L. , Horodecki M. , Plenio M. B. , Virmani S.
Published: September 2007

We analyse the relationship between the full additivity of the entanglement cost and its full monotonicity under local operations and classical communication. We show that the two properties are equivalent for the entanglement cost. The proof works for the regularization of any convex, subadditive, and asymptotically continuous entanglement monotone, and hence also applies to the asymptotic relative entropy of entanglement.
Production and Application of Novel Sterol Esterases from Aspergillus Strains by Solid State Fermentation
Authors: Tőke Enikő R. , Nagy Viviána , Recseg Katalin , Szakács György , Poppe László
Published: September 2007

Among numerous mesophilic fungi screened for sterol esterase activity followed by the esterification reaction between plant β‐sitosterol and lauric acid in organic solvent, six Aspergillus strains were selected as the most active producers. These fungi had not been studied previously for sterol esterase production. The fungi were cultivated under solid state fermentation (SSF) conditions. The gently dried SSF cultures as such were tested in the esterification reactions, without any special enzyme isolation and purification (downstream) processes. All the six Aspergillus SSF preparations were able to synthesize sterol esters. Sterol esterase activity of these GRAS cleared Aspergillus strains was inducible by sterol ester supplementation to the SSF medium and showed remarkably different moisture optimum during growth as compared to the production of lipase (determined by pNP‐palmitate). Genome analysis revealed that sterol esterase production might be a common feature of many Aspergillus species. The synthetic usefulness of the best SSF preparations of A. oryzae NRRL 6270 and A. sojae NRRL 6271 was demonstrated by synthesis of esters of plant sterols with lauric acid resulting in 45–63% conversions (GC) and 27–38% isolated yields of steryl laurates. The isomer preference of A. oryzae NRRL 6270 towards the 10E,12Z isomer of conjugated linoleic acid (CLA) in the esterification reaction with plant sterols was also determined.
Gender-specific modulation of tumorigenesis by folic acid supply in theApc+/Minmouse during early neonatal life
Authors: McKay Jill A. , Williams Elizabeth A. , Mathers John C.
Published: September 2007

Epidemiological studies suggest an inverse association between folic acid intake and colorectal cancer risk. Conversely, conventional treatment of existing tumours includes the use of folate antagonists. This suggests that the level of exposure to folate and its timing in relation to stage of tumorigenesis may be critical in determining outcomes. We hypothesised that folic acid depletionin uteroand during early neonatal life may affect tumorigenesis in offspring. To investigate this hypothesis, female C57Bl6/J mice were randomised to a folic acid adequate (2 mg folic acid/kg diet) or folic acid depleted diet (0·4 mg folic acid/kg) from mating withApc+/Minsires and throughout pregnancy and lactation. At weaning theApc+/Minoffspring were randomised to a folic acid adequate (2 mg folic acid/kg diet) or depleted (0·26 mg folic acid/kg diet) diet, creating fourin utero/post-weaning dietary regimens. At 10 weeks post-weaning, mice were killed and the intestinal tumour number and size were recorded. Folic acid depletion during pregnancy and post-weaning reduced erythrocyte folate concentrations in offspring significantly. Folic acid depletion during pregnancy and lactation did not affect tumour multiplicity or size. However, female mice fed normal folic acid diets post-weaning had more, and larger, tumours when compared with depleted females and both depleted and adequate folic acid fed males. These data suggest that folate depletion post-weaning was protective against neoplasia in femaleApc+/Minmice and highlights the need for further investigation of the optimal timing and dose of folic acid supplementation with regard to colorectal cancer risk.
Absolute bioavailability and dose-dependent pharmacokinetic behaviour of dietary doses of the chemopreventive isothiocyanate sulforaphane in rat
Authors: Hanlon Natalya , Coldham Nick , Gielbert Adriana , Kuhnert Nikolai , Sauer Maurice J. , King Laurie J. , Ioannides Costas
Published: September 2007

Sulforaphane is a naturally occurring isothiocyanate with promising chemopreventive activity. An analytical method, utilising liquid chromatography-MS/MS, which allows the determination of sulforaphane in small volumes of rat plasma following exposure to low dietary doses, was developed and validated, and employed to determine its absolute bioavailability and pharmacokinetic characteristics. Rats were treated with either a single intravenous dose of sulforaphane (2·8 μmol/kg) or single oral doses of 2·8, 5·6 and 28 μmol/kg. Sulforaphane plasma concentrations were determined in blood samples withdrawn from the rat tail at regular time intervals. Following intravenous administration, the plasma profile of sulforaphane was best described by a two-compartment pharmacokinetic model, with a prolonged terminal phase. Sulforaphane was very well and rapidly absorbed and displayed an absolute bioavailability of 82 %, which, however, decreased at the higher doses, indicating a dose-dependent pharmacokinetic behaviour; similarly,Cmaxvalues did not rise proportionately to the dose. At the highest dose used, the rate of absorption constantkab, biological half-lifet½and apparent volume of distribution decreased significantly. It is concluded that in the rat orally administered sulforaphane is rapidly absorbed, achieving high absolute bioavailability at low dietary doses, but dose-dependent pharmacokinetics was evident, with bioavailability decreasing with increasing dose.
Dietary inulin affects the expression of intestinal enterocyte iron transporters, receptors and storage protein and alters the microbiota in the pig intestine
Authors: Tako E. , Glahn R. P. , Welch R. M. , Lei X. , Yasuda K. , Miller D. D.
Published: September 2007

Inulin, a linear β fructan, is present in a variety of plants including chicory root and wheat. It exhibits prebiotic properties and has been shown to enhance mineral absorption and increase beneficial bacteria in the colon. The aim of the present study was to assess the effect of dietary inulin on the gene expression of selected intestinal Fe transporters and binding proteins. Anaemic piglets at age 5 weeks were allocated to a standard maize–soya diet (control) or the same diet supplemented with inulin at a level of 4 %. After 6 weeks, the animals were killed and caecum contents and sections of the duodenum and colon were removed. Segments of the genes encoding for the pig divalent metal transporter 1 (DMT1) and duodenal cytochrome-b reductase (Dcytb) were isolated and sequenced. Semi-quantitative RT-PCR analyses were performed to evaluate the expression of DMT1, Dcytb, ferroportin, ferritin, transferrin receptor (TfR) and mucin genes. DMT1, Dcytb, ferroportin, ferritin and TfR mRNA levels in duodenal samples were significantly higher in the inulin group (P ≤ 0·05) compared with the control. In colon, DMT1, TfR and ferritin mRNA levels significantly increased in the inulin group. Additionally, the caecal content microflora was examined using 16S rDNA targeted probes from bacterial DNA. TheLactobacillusandBifidobacteriumpopulations were significantly increased in the inulin group (P ≤ 0·05) compared with the control group. These results indicate that dietary inulin might trigger an up regulation of genes encoding for Fe transporters in the enterocyte. The specific mechanism for this effect remains to be elucidated.
Breaking wave induced cross‐shore tracer dispersion in the surf zone: Model results and scalings
Authors: Feddersen Falk
Published: September 2007

The dispersion of surf zone tracers including pollutants and bacteria is determined by many processes acting over a range of timescales and space scales. Breaking waves (bores) are clearly important to cross‐shore tracer dispersion in the surf zone, but little is known about the dispersal effects of bores. Here, a simple model for bore induced cross‐shore dispersion are developed based upon the diffusion equation with an eddy diffusivity that propagates with the bores. Depth‐uniform tracer and bore‐induced mixing along with alongshore uniformity are assumed. The bores are assumed well developed and the dispersion results are for a self‐similar (constant wave height to water depth ratio) surf zone. Four nondimensional parameters are identified and solution space is explored. The tracer center of mass is approximately constant, and tracer width grows with the square root of time. Tracer distribution becomes initially skewed after the passage of the first bore but becomes symmetric after multiple bores have passed. The nondimensional tracer patch growth and dilution rates depend strongly upon the nondimensional phase speed and wave period. The simple model results are consistent with the a Boussinesq wave model where the breaking‐wave eddy viscosity is used for the bore eddy diffusivity. The scaling of the dimensional parameters regarding the bore eddy diffusivity and the ranges of the nondimensional parameters are examined. Covariation of the nondimensional phase speed and wave period suggest that nondimensional tracer dispersion is largely cross‐shore independent.
On the extreme statistics of long‐crested deep water waves: Theory and experiments
Authors: Mori Nobuhito , Onorato Miguel , Janssen Peter A. E. M. , Osborne Alfred R. , Serio Marina
Published: September 2007

Quasi‐resonant four‐wave interactions may influence the statistical properties of deep water long‐crested surface gravity waves. As a consequence, the wave height exceedance probability can substantially deviate from the expected distribution obtained by assuming that waves are linear. Here the occurrence probability of extreme events recently derived by N. Mori and P. Janssen (2006) is compared with wave tank data, where strong departures from Gaussian behavior are observed. Experimental wave height, maximum wave height distribution, and probability of occurrence of freak waves are compared with theoretical expectations. The theory well predicts extreme waves in nonlinear wavefields.
Potential of Advanced Microwave Sounding Unit to identify precipitating systems and associated upper‐level features in the Mediterranean region: Case studies
Authors: Funatsu B. M. , Claud C. , Chaboureau J.‐P.
Published: September 2007

The potential of the Advanced Microwave Sounding Unit (AMSU) observations to identify and characterize precipitating systems in the Mediterranean region is explored. Single channels or combination channels from AMSU‐A are used to detect and locate upper level potential vorticity anomalies that are often associated with intensification of surface low systems and occurrence of extreme events, while AMSU‐B data is used to detect precipitating areas. The motivation for the approach presented here is the direct use of satellite data as an alternative for reanalysis data sets for climatological studies of Mediterranean lows, without relying on retrieval algorithms. AMSU‐A channel 8 was found to be more suitable to identify upper level southward intrusions of stratospheric air than the difference of channels 7 and 5, which detects only vertically deep intrusions. A combination of AMSU‐B channels 3 and 5 is able to discriminate moderate to strongly precipitating areas with good agreement with Tropical Rainfall Measuring Mission (TRMM) derived products and independent ground‐based data. A more stringent condition based on differences of channels 3 to 5 was found to be useful to detect deep convective clouds. We demonstrate the applicability of AMSU to detect upper level features and precipitating systems for selected case studies of extreme precipitation in the Mediterranean region. These tools will allow us to form a climatology of moderate to strongly precipitating systems, and to investigate their relationship with upper level features that may be precursors of extreme events, and to establish a typology of the precipitating systems in the Mediterranean region.
Temporal and spatial properties of some deep moonquake clusters
Authors: Bulow R. C. , Johnson C. L. , Bills B. G. , Shearer P. M.
Published: September 2007

Using the event search method of Bulow et al. (2005), we have found 503 new deep moonquakes among the eight largest (in terms of total number) nearside source regions, increasing the number of identified events for each cluster an average of 36% over the existing catalog. These new events provide an improved deep event catalog, with which we explore some temporal and spatial aspects of deep moonquakes. First, we examine the spectra of moonquake occurrence times at each deep source region, and observe known tidal periodicities, notably those at ∼27 days and 206 days. Application of spectral methods for the analyses of point processes (discrete events) allows us to resolve closely spaced tidal periods not previously seen in moonquake data. Second, we pick seismic phase arrival times from optimized stacks of events from each source region. We use these picks, along with published velocity models, to relocate the nine source regions. Source regions A1 and A18 are the best located, with 95% confidence bounds of less than ±5° in latitude and longitude, and consistent with estimates from different studies. The locations of source regions A8 and A9 are poorly constrained, with uncertainties in latitude of up to ±28° resulting from the absence of clear phase arrivals at station 15. Large trade‐offs exist between relocation estimates and choice of velocity model, and the lack of reliable seismic phase arrivals severely affects location error.
Probabilistic collocation method for flow in porous media: Comparisons with other stochastic methods
Authors: Li Heng , Zhang Dongxiao
Published: September 2007

An efficient method for uncertainty analysis of flow in random porous media is explored in this study, on the basis of combination of Karhunen‐Loeve expansion and probabilistic collocation method (PCM). The random log transformed hydraulic conductivity field is represented by the Karhunen‐Loeve expansion and the hydraulic head is expressed by the polynomial chaos expansion. Probabilistic collocation method is used to determine the coefficients of the polynomial chaos expansion by solving for the hydraulic head fields for different sets of collocation points. The procedure is straightforward and analogous to the Monte Carlo method, but the number of simulations required in PCM is significantly reduced. Steady state flows in saturated random porous media are simulated with the probabilistic collocation method, and comparisons are made with other stochastic methods: Monte Carlo method, the traditional polynomial chaos expansion (PCE) approach based on Galerkin scheme, and the moment‐equation approach based on Karhunen‐Loeve expansion (KLME). This study reveals that PCM and KLME are more efficient than the Galerkin PCE approach. While the computational efforts are greatly reduced compared to the direct sampling Monte Carlo method, the PCM and KLME approaches are able to accurately estimate the statistical moments and probability density function of the hydraulic head.
Consistent thermodynamic formulations for multiscale hydrologic systems: Fluid pressures
Authors: Gray W. G. , Miller C. T.
Published: September 2007

Although averaging procedures to derive larger‐scale conservation equations from their microscopic counterparts have been examined and employed in a consistent manner for a range of hydrologic problems, procedures for obtaining correspondingly averaged thermodynamic relations at the larger scale have received less attention. We examine issues related to the change of scale for intensive thermodynamic quantities, such as fluid pressures and temperatures, compare formulations based upon the underlying thermodynamic theory relied upon, and produce precise, consistent definitions for fluid pressures and capillary pressures in multiphase porous medium systems. The averaged thermodynamics approach demonstrated and advocated is applicable to a wide range of hydrologic systems beyond the two‐fluid porous medium case examined in detail in this work.
Electron acceleration in the Van Allen radiation belts by fast magnetosonic waves
Authors: Horne Richard B. , Thorne Richard M. , Glauert Sarah A. , Meredith Nigel P. , Pokhotelov Dimitry , Santolík Ondřej
Published: September 2007

Local acceleration is required to explain electron flux increases in the outer Van Allen radiation belt during magnetic storms. Here we show that fast magnetosonic waves, detected by Cluster 3, can accelerate electrons between ∼10 keV and a few MeV inside the outer radiation belt. Acceleration occurs via electron Landau resonance, and not Doppler shifted cyclotron resonance, due to wave propagation almost perpendicular to the ambient magnetic field. Using quasi‐linear theory, pitch angle and energy diffusion rates are comparable to those for whistler mode chorus, suggesting that these waves are very important for local electron acceleration. Since pitch angle diffusion does not extend into the loss cone, these waves, on their own, are not important for loss to the atmosphere. We suggest that magnetosonic waves, which are generated by unstable proton ring distributions, are an important energy transfer process from the ring current to the Van Allen radiation belts.
Numerical study of the atmospheric input of anthropogenic total nitrate to the marginal seas in the western North Pacific region
Authors: Uno I. , Uematsu M. , Hara Y. , He Y. J. , Ohara T. , Mori A. , Kamaya T. , Murano K. , Sadanaga Y. , Bandow H.
Published: September 2007

Atmospheric input of anthropogenic total nitrate to marginal seas in the western North Pacific region was simulated using a regional chemical transport model over East Asia based on year‐to‐year emission estimates during 1980–2003. Seasonal cycles and concentration levels of gas and aerosol were examined using observation data from various studies. The model simulated total nitrate deposition over the East China Sea (ECS) as 140 GgN/yr, which is the same order of the annual river discharge from the Yangtze River. The ratio of dry and wet deposition over ECS was obtained as approximately 6: 4. Total nitrate deposition over ECS corresponds to 3.2% (N base) of total NOx emission in China. The total deposition at present is three times larger than that of 1980, corresponding with increased NOx emissions.
Radiative forcing of black carbon over eastern India
Authors: Sreekanth V. , Niranjan K. , Madhavan B. L.
Published: September 2007

Measurements of aerosol Black Carbon using a 7 channel Aethalometer at Visakhapatnam, a coastal tropical station on the east coast of India are used to study the temporal variation of surface BC mass concentration. The surface BC mass concentrations show a significant diurnal variation which is seasonally dependant. Analysis using the multi spectral data indicates that the BC mass does not show significant absorption due to non‐BC aerosol species which indicates that the surface BC mass is dominated by fossil fuel sources with no indication of any other strong anthropogenic source. The Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model was used in conjunction with Optical Properties of Aerosols and Clouds (OPAC) to estimate the BC radiative forcing. The results show large negative surface forcing during winter (−35.78 W/m2), moderate during summer (−16.8 W/m2) and lower forcing during monsoon (−9.9 W/m2) and post monsoon (−2.81 W/m2). The forcing at the top of the atmosphere is positive for all the seasons.
Determination of substorm onset timing and location using the THEMIS ground based observatories
Authors: Mende S. B. , Angelopoulos V. , Frey H. U. , Harris S. , Donovan E. , Jackel B. , Syrjaesuo M. , Russell C. T. , Mann I.
Published: September 2007

The NASA THEMIS mission is studying substorms by timing the substorm signatures at multiple satellite locations in the magnetosphere and in the aurora using 20 ground based observatories (GBO‐s). The time resolution requirement is ∼10 sec. The GBO‐s provide a near contiguous array over North America. Each contains an all sky imager (3 s exposure cadence) and a magnetometer (with 2 Hz sampling rate). In one example substorm, the onset brightening of the equatorward arc was a gradual process (>27 seconds) with minimal morphology changes until the arc break up. The break up was timed to the nearest frame (<3 sec) and occurred at 58°N latitude and 256 ± 3°E longitude geographic (67°N magnetic latitude 22.1 hours MLT). The brightening of the arc was accompanied by a slow increase of the westward electrojet but this was too gradual for accurate timing of the event. High pass filtered magnetic data showed some wave activity but with significant delay (∼40 sec) after the arc break up. Similar break up occurred in Alaska ∼10 minutes later highlighting the need for an array to distinguish prime onset.
Dust storm activity over the Tibetan Plateau recorded by a shallow ice core from the north slope of Mt. Qomolangma (Everest), Tibet‐Himal region
Authors: Xu Jianzhong , Hou Shugui , Qin Dahe , Kang Shichang , Ren Jiawen , Ming Jing
Published: September 2007

Based on a 39.8 m ice core drilled at the East Rongbuk Glacier (27°59′N, 86°55′E 6518 m a.s.l,), north slope of Mt. Qomolangma (Everest), central Himalaya, the changes of dust storm over the Tibetan Plateau (TP) recorded by insoluble particle and its possible connection with the winter (JFM) North Atlantic Oscillation (NAO) are investigated. The results show that the level of dust storm activity exhibits a significant decreasing trend during the past ∼50 years. This may be attributed, at least partly, to a decrease in wind speed over the TP and its surrounding regions. The normalized time series of the winter NAO index shows a significant inverse correlation with the mass concentration of insoluble particle implying a possible connection between the winter NAO and the dust storm activity over the TP.
The influence of climate state variables on Atlantic Tropical Cyclone occurrence rates
Authors: Sabbatelli Thomas A. , Mann Michael E.
Published: September 2007

We analyzed annual North Atlantic tropical cyclone (TC) counts from 1871‐2004, considering three climate state variables—the El Niño/Southern Oscillation (ENSO), peak (August‐October or ‘ASO’) Sea Surface Temperatures (SST) over the main development region (‘MDR’: 6‐18°N, 20‐60°W), and the North Atlantic Oscillation (NAO)—thought to influence variations in annual TC counts on interannual and longer timescales. The unconditional distribution of TC counts is observed to be inconsistent with the null hypothesis of a fixed rate random (Poisson) process. However, using two different methods, we find that conditioning TC counts on just two climate state variables, ENSO and MDR SST, can account for much or all of the apparent non‐random variations over time in TC counts. Based on statistical models of annual Atlantic TC counts developed in this study and current forecasts of climate state variables, we predicted m = 15 ± 4 total named storms for the 2007 season.
Species specific IDMS for accurate quantification of carboplatin in urine by LC-ESI-TOFMS and LC-ICP-QMS
Authors: Koellensperger G. , Stefanka Zs. , Meelich K. , Galanski M. S. , Keppler B. K. , Stingeder G. , Hann S.
Published: September 2007

Both LC-ICP-QMS and LC-ESI-TOFMS can be applied for the SSIDMS analysis of carboplatin in human urine. However, ICP-MS will always be the method of choice, especially in cases were the accuracy of quantification is the analytical focus.
Sulfur Metabolism in Plants: Are Trees Different?
Authors: Rennenberg H. , Herschbach C. , Haberer K. , Kopriva S.
Published: September 2007

Abstract: Sulfur metabolite levels and sulfur metabolism have been studied in a significant number of herbaceous and woody plant species. However, only a limited number of datasets are comparable and can be used to identify similarities and differences between these two groups of plants. From these data, it appears that large differences in sulfur metabolite levels, as well as the genetic organization of sulfate assimilation and metabolism do not exist between herbaceous plants and trees. The general response of sulfur metabolism to internal and/or external stimuli, such as oxidative stress, seems to be conserved between the two groups of plants. Thus, it can be expected that, generally, the molecular mechanisms of regulation of sulfur metabolism will also be similar. However, significant differences have been found in fine tuning of the regulation of sulfur metabolism and in developmental regulation of sulfur metabolite levels. It seems that the homeostasis of sulfur metabolism in trees is more robust than in herbaceous plants and a greater change in conditions is necessary to initiate a response in trees. This view is consistent with the requirement for highly flexible defence strategies in woody plant species as a consequence of longevity. In addition, seasonal growth of perennial plants exerts changes in sulfur metabolite levels and regulation that currently are not understood. In this review, similarities and differences in sulfur metabolite levels, sulfur assimilation and its regulation are characterized and future areas of research are identified.
Facts and Fiction about Sulfur Metabolism in Relation to Plant‐Pathogen Interactions
Authors: Bloem E. , Haneklaus S. , Salac I. , Wickenhäuser P. , Schnug E.
Published: September 2007

Abstract: Sulfur deficiency developed into a widespread nutrient disorder in the 1980s because of the drastic decrease of SO2 emissions in western Europe after Clean Air Acts came into force. It was observed that not only the yield and quality of agricultural crops were negatively affected by sulfur deficiency but also their health status. Since the mid 1990s the physiological background of this latter phenomenon in the sulfur metabolism has been studied by different researchers. From 2001 until 2006, field trials with different varieties of oilseed rape were conducted in Germany, and also from 2001 until 2003 in Scotland, to investigate the underlying mechanisms of sulfur‐induced resistance and to develop fertiliser strategies which increase the health status of crops and minimise the requirement for chemical fungicides. A comprehensive disease assessment was conducted and a range of different sulfur‐containing metabolites and enzymes were analysed in relation to sulfur nutrition and fungal diseases. H2S emissions from field‐grown crops under different sulfur nutritional status were studied for the first time and a positive relationship was observed. Besides S fertilisation, fungal infection increased H2S emissions, too. The studies deliver new insight into the complex of sulfur‐induced resistance but many questions still remain open. This contribution will show different possible strategies to solve some of the open questions.
Characterization of Cysteine‐Degrading and H2S‐Releasing Enzymes of Higher Plants ‐ From the Field to the Test Tube and Back
Authors: Papenbrock J. , Riemenschneider A. , Kamp A. , Schulz‐Vogt H. N. , Schmidt A.
Published: September 2007

Abstract: Due to the clean air acts and subsequent reduction of emission of gaseous sulfur compounds sulfur deficiency became one of the major nutrient disorders in Northern Europe. Typical sulfur deficiency symptoms can be diagnosed. Especially plants of the Cruciferae family are more susceptible against pathogen attack. Sulfur fertilization can in part recover or even increase resistance against pathogens in comparison to sulfur‐deficient plants. The term sulfur‐induced resistance (SIR) was introduced, however, the molecular basis for SIR is largely unknown. There are several sulfur‐containing compounds in plants which might be involved in SIR, such as high levels of thiols, glucosinolates, cysteine‐rich proteins, phytoalexins, elemental sulfur, or H2S. Probably more than one strategy is used by plants. Species‐ or even variety‐dependent differences in the development of SIR are probably used. Our research focussed mainly on the release of H2S as defence strategy. In field experiments using different Brassica napus genotypes it was shown that the genetic differences among Brassica genotypes lead to differences in sulfur content and L‐cysteine desulfhydrase activity. Another field experiment demonstrated that sulfur supply and infection with Pyrenopeziza brassica influenced L‐cysteine desulfhydrase activity in Brassica napus. Cysteine‐degrading enzymes such as cysteine desulfhydrases are hypothesized to be involved in H2S release. Several L‐ and D‐cysteine‐specific desulfhydrase candidates have been isolated and partially analyzed from the model plant Arabidopsis thaliana. However, it cannot be excluded that H2S is also released in a partial back reaction of O‐acetyl‐L‐serine(thiol)lyase or enzymes not yet characterized. For the exact determination of the H2S concentration in the cell a H2S‐specific microsensor was used the first time for plant cells. The transfer of the results obtained for application back on Brassica was initiated.
Leaf Developmental Stage Affects Sulfate Depletion and Specific Sulfate Transporter Expression During Sulfur Deprivation in Brassica napus L.
Authors: Parmar S. , Buchner P. , Hawkesford M. J.
Published: September 2007

Abstract: Brassica napus was grown under hydroponic conditions and responses to the removal of the external supply of sulfur (S) were analysed in roots and in leaves of different developmental age. The concentrations of sulfate and nitrate were greatest in the older leaves and least in younger leaves, whilst phosphate was greatest in roots and youngest leaves and least in old leaves. S‐deprivation resulted in decreases in tissue sulfate concentrations at variable rates in the order: roots and young leaves > middle‐aged leaves > oldest leaves. Phosphate concentrations were unaffected and nitrate concentrations were only depleted in the oldest leaves. Expression of representative members of the sulfate transporter gene family was assessed by Northern blotting in the respective tissues. Group 1 transporters (high affinity type) were induced in response to S‐deprivation in all tissues except old leaves, where no expression was detected, and to the greatest extent in roots. Groups 2 and 5 (a Brassica Group 5 sulfate transporter is reported here, accession number: AJ311389) transporters showed either no or only a small induction by S‐deprivation. Group 4 transporters (localised in the tonoplast membrane and thought to be involved in vacuolar sulfate efflux) were induced by S‐deprivation with a complex pattern: 4;1 was expressed in root and mature leaves, was strongly induced by sulfur‐deprivation in roots, and was also induced in the middle‐aged leaves alone; 4;2 was only expressed under S‐deprivation in parallel with the observed pattern of tissue sulfate concentrations. Expression patterns indicated that both differences in intracellular sulfate pools and localised aspects of the signal transduction pathway link tissue sulfate‐status and sulfur‐nutrition regulated gene expression.
Sulfate Assimilation in Basal Land Plants ‐ What Does Genomic Sequencing Tell Us?
Authors: Kopriva S. , Wiedemann G. , Reski R.
Published: September 2007

Abstract: Sulfate assimilation is a pathway providing reduced sulfur for the synthesis of cysteine, methionine, co‐enzymes such as iron‐sulfur centres, thiamine, lipoic acid, or Coenzyme A, and many secondary metabolites, e.g., glucosinolates or alliins. The pathway is relatively well understood in flowering plants, but very little information exists on sulfate assimilation in basal land plants. Since the finding of a putative 3′‐phosphoadenosine 5′‐phosphosulfate reductase in Physcomitrella patens, an enigmatic enzyme thought to exist in fungi and some bacteria only, it has been evident that sulfur metabolism in lower plants may substantially differ from seed plant models. The genomic sequencing of two basal plant species, the Bryophyte Physcomitrella patens, and the Lycophyte Selaginella moellendorffii, opens up the possibility to search for differences between lower and higher plants at the genomic level. Here we describe the similarities and differences in the organisation of the sulfate assimilation pathway between basal and advanced land plants derived from genome comparisons of these two species with Arabidopsis thaliana and Oryza sativa, two seed plants with sequenced genomes. We found differences in the number of genes encoding sulfate transporters, adenosine 5′‐phosphosulfate reductase, and sulfite reductase between the lower and higher plants. The consequences for regulation of the pathway and evolution of sulfate assimilation in plants are discussed.
The Effect of Sulfur Nutrition on Plant Glucosinolate Content: Physiology and Molecular Mechanisms
Authors: Falk K. L. , Tokuhisa J. G. , Gershenzon J.
Published: September 2007

Abstract: Glucosinolates are sulfur‐rich plant metabolites of the order Brassicales that function in the defense of plants against pests and pathogens. They are also important in human society as flavor components, cancer‐prevention agents, and crop biofumigants. Since glucosinolates may represent up to 30 % of the total sulfur content of plant organs, their accumulation should depend intimately on the sulfur status of the entire plant. Here we review the literature on how sulfur supply affects glucosinolate content. In field and greenhouse experiments involving soil, hydroponic and tissue culture media, sulfur fertilisation usually led to an increase in glucosinolate content ranging from 25 % to more than 50‐fold, depending on the plant species, amount of sulfur applied, and type of treatment. The effect was greater on glucosinolates derived from the sulfur amino acid, methionine, than on glucosinolates derived from tryptophan. These changes are regulated not by simple mass action effects, but by extensive changes in gene transcription. In sulfur‐deficient plants, there is a general down‐regulation of glucosinolate biosynthetic genes which accompanies an up‐regulation of genes controlling sulfur uptake and assimilation. Glucosinolates may be considered a potential source of sulfur for other metabolic processes under low‐sulfur conditions, since increased breakdown of glucosinolates has been reported under sulfur deficiency. However, the pathway for sulfur mobilisation from glucosinolates has not been determined. The breakdown of indolic glucosinolates to form auxin in roots under sulfur‐deficient conditions may help stimulate root formation for sulfur uptake.
Sulfur‐Enhanced Defence: Effects of Sulfur Metabolism, Nitrogen Supply, and Pathogen Lifestyle
Authors: Kruse C. , Jost R. , Lipschis M. , Kopp B. , Hartmann M. , Hell R.
Published: September 2007

Abstract: Evidence from field experiments indicates differential roles of sulfur and nitrogen supply for plant resistance against pathogens. Dissection of these observations in defined pathosystems and controlled nutritional conditions indicates an activation of plant sulfur metabolism in several incompatible and compatible interactions. Contents of cysteine and glutathione as markers of primary sulfate assimilation and stress response show increases in Arabidopsis thaliana upon infection, coinciding with the synthesis of sulfur‐containing defence compounds. Similar increases of thiols were observed with necrotrophic, biotrophic, and hemibiotrophic pathogens. Sulfate supply was found to be neutral or beneficial for tolerance against fungal but neutral for bacterial pathogens under in vitro conditions. According to various reports and own observations the effects of nitrogen supply appeared to be neutral or harmful, depending on the pathogen. The activation of sulfur metabolism was a consequence of activation of gene expression as revealed by macroarray analysis of an A. thaliana/Alternaria brassicicola pathosystem. This activation appeared to be largely independent from sufficient or optimal sulfate supply and from the established sulfate deficiency response. The data suggest that plant‐pathogen interactions and sulfur metabolism are linked by jasmonic acid as signal.
Evaluation of the Metal Phytoextraction Potential of Crop Legumes. Regulation of the Expression of O‐Acetylserine (Thiol)Lyase under Metal Stress
Authors: Pajuelo E. , Carrasco J. A. , Romero L. C. , Chamber M. A. , Gotor C.
Published: September 2007

Abstract: The metal phytoextraction potential of three legumes belonging to different genera has been studied under greenhouse conditions. Legumes accumulate As and metals mainly in roots, although translocation to shoot is observed. Alfalfa did accumulate the highest concentrations of As and metals in shoots and aerial biomass was less affected by the toxic elements, indicating its good behaviour in phytoextraction. Clover accumulated less metal, but showed larger biomass. EDTA addition enhanced Pb phytoextraction up to levels similar to those described for plants proposed in phytoremediation. The regulation of O‐acetylserine (thiol)lyase from legumes under metal stress has been analysed to test the possibility of establishing a possible correlation between the expression of OASTL in the presence of the metals and the metal accumulation in legume plant tissues. Cd and Pb(EDTA) produce the strongest increases of OASTL activity, with the higher enhancement seen in roots, in parallel with the higher metal accumulation. Arsenic produced an increase of root enzyme activity, whereas Cu produced a decrease, mainly in shoots. Western blots using antibodies against an A. thaliana cytosolic OAS‐TL recognised up to five protein bands in crude extracts from Lotus and clover. A low molecular weight isoform of 32 kDa was induced in the presence of Cd and Pb. A partial RT‐PCR sequence from clover has been obtained, showing 86 ‐ 97 % identity with other described OASTLs. The PCR fragment has been used to analyse OASTL mRNA levels of legumes under metal stress. OASTL transcripts were increased by As, Cd, and Pb, especially in roots, where metal accumulation was maximal, while Cu produced a decrease in the transcript levels.
Chromate Differentially Affects the Expression of a High‐Affinity Sulfate Transporter and Isoforms of Components of the Sulfate Assimilatory Pathway in Zea mays (L.)
Authors: Schiavon M. , Wirtz M. , Borsa P. , Quaggiotti S. , Hell R. , Malagoli M.
Published: September 2007

Abstract: In this study the chromate accumulation and tolerance were investigated in Zea mays L. in relation to sulfur availability since sulfate may interact with chromate for transport into the cells. Chromate inhibited sulfate uptake when supplied to plants for a short‐term period, whereas phosphate uptake remained unchanged. Sulfate absorption was also reduced in S‐starved (‐S) and S‐supplied (+S) plants treated for 2 d with 0.2 mM chromate and the concomitant repression of the root high‐affinity sulfate root transporter ZmST1;1 transcript accumulation was observed. Conversely, the plasma membrane H+‐ATPase Mha2 was unaffected by chromate in +S plants, allowing to exclude a general effect of chromate on the active membrane transport. As observed for sulfate uptake, chromate uptake was enhanced in ‐S condition and decreased in both +S and ‐S plants after 2 d of Cr treatment. Chromate reduced the concentration of sulfur and sulfate in +S plants to the basal level of ‐S plants, and maximum chromium accumulation was recorded in S‐deprived plants. Analysis of transcript abundance of genes involved in sulfate assimilation revealed differential regulation by chromate, which was only partly related to sulfur availability and to the levels of thiols. This work shows for the first time that chromate specifically represses sulfate uptake, and such repression occurs without the implication of the candidate regulatory metabolites of the sulfate transport system in plants.
Calculated spectroscopic and electric properties of the alkali metal-ammonia complexes from Kn–NH3 to Frn–NH3 (n=,+1)
Authors: Lim Ivan S. , Botschwina Peter , Oswald Rainer , Barone Vincenzo , Stoll Hermann , Schwerdtfeger Peter
Published: September 2007

The newly developed Stuttgart small-core scalar relativistic pseudopotentials for the alkali metals are used to study spectroscopic and electric properties of the heavier alkali metal-ammonia complexes from Kn–NH3 to Frn–NH3 (n=0,+1) at the second-order Møller-Plesset (MP2) and coupled cluster [CCSD(T)] levels of theory. Equilibrium geometries and dissociation energies computed at the MP2 level are in reasonable agreement with their CCSD(T) counterparts, whereas for the dipole polarizabilities MP2 is not performing well overestimating significantly electron correlation effects. The bond distances increase monotonically with increasing mass of the metal atom as relativistic effects are small in these systems. However, the dipole polarizabilities are more sensitive to such effects and we find a decrease in this property from Cs–NH3 to Fr–NH3. Combination of CCSD(T) harmonic frequencies and MP2 anharmonic corrections obtained from a perturbative vibrational treatment leads to fundamental frequencies in good agreement with experimental results obtained by Süzer and Andrews [J. Am. Chem. Soc. 109, 300 (1986)]. We also present the results of variational calculations with a three-dimensional vibrational Hamiltonian, making use of CCSD(T) potential energy and electric dipole moment surfaces. Complexation of NH3 to the metal causes a strong infrared intensification of the symmetric NH3 stretching mode in the neutral complexes, which is absent in the charged species.
Convergence of resonances on thin branched quantum waveguides
Authors: Exner Pavel , Post Olaf
Published: September 2007

We prove an abstract criterion stating resolvent convergence in the case of operators acting in different Hilbert spaces. This result is then applied to the case of Laplacians on a family Xε of branched quantum waveguides. Combining it with an exterior complex scaling we show, in particular, that the resonances on Xε approximate those of the Laplacian with “free” boundary conditions on X0, the skeleton graph of Xε.