bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of ozone and sulfur dioxide on respiration of ectomycorrhizal fungi
Authors: Garrett H. E. , Carney J. L. , Hedrick H. G.
Published: February 2010

Oxygen-uptake determinations were made on mycelial mats of four ectomycorrhizal fungal isolates: three of Pisolithustinctorius (Pers.) Coker and Couch and one of Thelephoraterrestris (Erhr.) Fr. following a 1-h exposure to 5 and 50 parts per hundred million (pphm) O3 or SO2. Similar determinations were made on mycorrhizal (P. tinctorius and T. terrestris) and nonmyeorrhizal loblolly pine (Pinustaeda L.) root segments exposed to 5 pphm O3 and SO2. Both gases caused marked reductions in respiration rates of the pure fungal and root materials with significant species and intraspecies differences observed. However, greater inhibition was observed with SO2 than with O3. Ectomycorrhizal loblolly pine root segments were significantly more resistant to the deleterious influences of O3 and SO2 on respiration than were nonmycorrhizal roots indicating that ectomycorrhizal development may afford some protection against feeder-root damage from O3 and SO2. The greatest protection from O3 was provided by Thelephoraterrestris while Pisolithustinctorius root sections were most resistant to SO2 damage.
Production and quality of forage available to moose in southwestern Quebec
Authors: Crête Michel , Jordan Peter A.
Published: February 2010

Production of summer and of winter forage used by moose (Alcesalces Cl.) was estimated in six 530-km2 study blocks in southwestern Quebec. Annual production of summer forage (leaves of predominantly mountain maple (Acerspicatum Lam.) and beaked hazelnut (Coryluscornuta Marsh.)) averaged from 73 to 321 kg dry weight/ha, varying among 3 years and five forest types. Winter forage (twigs of deciduous species, predominantly the same two, plus needles and associated twigs of balsam fir (Abiesbalsamea (L.) Mill.)) averaged ca. 0.2 the production of summer forage. Annual production in all species, plus levels of crude protein, cellulose, Ca, and P in mountain maple and hazel, were comparable to those reported for other North American moose ranges. Among the six blocks, no relationship was found between moose density and forage factors. It was concluded that in lightly hunted regions of southwestern Quebec, further growth of moose populations was not being limited by nutritional factors.
Growth response of postfire quaking aspen (Populustremuloides Michx.) to N, P, and K fertilization
Authors: Cleve Keith Van , Oliver Lola K.
Published: February 2010

Yearly applications of N, P, and K fertilizer for a 6-year period to a young, postfire aspen forest, resulted in substantial increases in tree growth primarily in response to nitrogen. The main effect of N was to increase, by at least a factor of two, the stand leaf area index, and bole and total aboveground tree mass. Improved nitrogen nutrition appeared to reduce the efficiency of production per unit of nitrogen incorporated into tree crowns.
Examen de quelques relations allométriques chez le sapin baumier et l'épinette blanche
Authors: Zarnovican R.
Published: February 2010

An analysis of the crown morphological measurements of dominant trees of balsam fir and white spruce revealed a strong resemblance between the two. Taking advantage of a statistical relationship between crown width and dbh, we used a linear prediction model to compute the maximum efficiency rate of nominal used space in the stands studied. Once the full natural stocking density had been defined for each stand, their ordination showed the existence of a single yield level. Finally, a single-entry tree volume table to calculate solid volume from dbh is proposed.
Heritabilities and genetic and phenotypic correlations for height and diameter in coastal Douglas-fir
Authors: Yeh Francis C. , Heaman Chris
Published: February 2010

Factorial crosses of 22 seed trees and 4 pollen parents from a breeding population of 445 coastal Douglas-firs were tested at two sites. Analyses of heights and diameters after the sixth growing season indicated only the significance of additive genetic variance. The single tree heritability estimates for height and diameter were 0.10 ± 0.07 and 0.12 ± 0.08, respectively. The genetic correlation between height and diameter was 0.81 ± 0.64.
Stumpage price function for hardwoods in the Niagara district of Ontario
Authors: Nautiyal Jagdish C.
Published: February 2010

The stumpage prices for trees of various species, qualities, and diameters in the Niagara district of Ontario have been estimated. Data were obtained from the competitively sold small sale lots in the district and a nonlinear regression method was used. Results indicate that such a method can successfully be used for estimating upset prices of sales and for deciding on outlays for silvicultural operations. From the data set used, the stumpage price of all species was $0.15 per cubic foot (1 ft = 0.3048 m) for trees below 19-in. (1 in. = 25.4 mm) diameter. Most prices jumped up at this diameter to as high a figure as $1.41 for black walnut and showed another but smaller jump at 23-in. diameter.
Influence d'une éclaircie sur la croissance et le bilan hydrique d'un jeune peuplement de Douglas (Pseudotsugamenziesii (Mirb.) Franco)
Authors: Aussenac G. , Granier A. , Naud R.
Published: February 2010

Systematic thinning (alternate rows) was done in a 19-year-old Douglas-fir plantation. The principal microclimatic effect was to increase light at ground level (less than 1% in the unthinned versus 7.3% in the thinned stand) and also in the crowns (crown bases: 1% in the unthinned compared with 17.6% in the thinned stand). The other microclimatological parameters were less influenced.With reference to the water balance, the results indicate that thinning half the trees diminished the interception by only 13.1% (43.4% water intercepted in the unthinned versus 30.3% in the thinned stands). Indeed, the influence of the thinning on the actual evapotranspiration was relatively weak: the observed decrease was only 16.7% compared with the unthinned stand.The measurements also show that, as of the 1st year, the thinning increased the rate of tree growth substantially; the increase in basal area of the thinned stand was 101% of that of the unthinned stand. In other words, there was no production decrease the year of thinning.Essentially thinning benefits codominant trees. As a result of thinning, modifications to the crown cover became evident: the lower whorls of the tree crowns, remaining after the thinning, exhibited a greater mass of foliage compared with the unthinned stand owing to fewer old needles dropping.
Response of young black cherry stands to fertilization
Authors: Auchmoody L. R.
Published: February 2010

Twenty fertilizer treatments of different rates and combinations of N, P, and K were established in young black cherry (Prunusserotina Ehrh.) stands that originated after clear-cutting in northwestern Pennsylvania, U.S.A. Height, diameter, and basal area growth rates and foliar nutrient composition were evaluated annually for 5 years thereafter. Nitrogen alone and P in combination with N produced large increases in height, diameter, and basal area growth. The addition of K to N + P treatments produced no additional response. Growth responses were largest during the first 2 years after fertilization, with increases in height and diameter lasting for 4 to 5 years. In year 1, maximum growth rates were reached with 112 kg N/ha and 49 kg P/ha, but 224 kg N/ha and 49 kg P/ha were necessary to sustain responses in following years. Both seedling and sapling stands responded to fertilization with similar absolute annual increases in height and diameter, though absolute basal area response of saplings exceeded that of seedlings owing to large differences in pretreatment diameters. Nitrogen fertilization increased average foliar N from 2.51 to 3.94% in year 1, but this concentration declined sharply thereafter and was at the control level by year 4. Phosphorus fertilization increased average foliar P from 0.12 to 0.21% in year 1, with further increases through year 5. Potassium fertilization increased average foliar K from 1.01 to 1.21% over the 5-year period, though there was considerable year-to-year variation.
Vegetative phenology in a clonal seed orchard of Piceaglauca and Piceamariana in northwestern Ontario
Authors: O'Reilly Conor , Parker William H.
Published: February 2010

The vegetative phenology of Piceaglauca (Moench) Voss and P. mariana (Mill.) B.S.P. was determined in 1979 based on four ramets selected from each of 14 clones of each species located at a seed orchard in northern Ontario. The time of flushing of the leaders and four lateral branches was determined by a qualitative index of bud and shoot development; time of growth cessation was scored as the date at which 95% of shoot growth was complete. The flushing of the vegetative buds of white spruce lasted for a 10-day period compared with only 6 days for black spruce. Although the average date of flushing for white spruce clones was 9 days ahead of the average date for black spruce clones, the latest white spruce clone flushed only 3 days before the earliest black spruce clones. As well, degree-day requirements for flushing were significantly different for clones within each of the two species. These results suggest that the selection of late-flushing white spruce trees for seed orchard stock has the potential to decrease spring frost damage in this species in northern Ontario. Date of budbreak was not correlated with date of growth cessation for either white or black spruce; however, early-flushing clones of black spruce produced significantly greater leader extension than late-flushing clones.
Cognitive transfer of spatial awareness states from immersive virtual environments to reality
Authors: Mania Katerina , Badariah Shahrul , Coxon Matthew , Watten Phil
Published: February 2010

An individual's prior experience will influence how new visual information in a scene is perceived and remembered. Accuracy of memory performance per se is an imperfect reflection of the cognitive activity (awareness states) that underlies performance in memory tasks. The aim of this research is to investigate the effect of varied visual fidelity of training environments on the transfer of training to the real world after exposure to immersive simulations representing a real-world scene. A between groups experiment was carried out to explore the effect of rendering quality on measurements of location-based recognition memory for objects and associated states of awareness. The immersive simulation consisted of one room that was either rendered flat-shaded or using radiosity rendering. The simulation was displayed on a stereo head-tracked head mounted display. Post exposure to the synthetic simulation, participants completed a memory recognition task conducted in a real-world scene by physically arranging objects in their physical form in a real-world room. Participants also reported one of four states of awareness following object recognition. They were given several options of awareness states that reflected the level of visual mental imagery involved during retrieval, the familiarity of the recollection and related guesses. The scene incorporated objects that “fitted” into the specific context of the real-world scene, referred to as
consistent
objects, and objects that were not related to the specific context of the real-world scene, referred to as
inconsistent
objects. A follow-up study was conducted a week after the initial test. Interestingly, results revealed a higher proportion of correct object recognition associated with mental imagery when participants were exposed to low-fidelity flat-shaded training scenes rather than the radiosity rendered ones. Memory psychology indicates that awareness states based on visual imagery require stronger attentional processing in the first instance than those based on familiarity. A tentative claim would, therefore, be that those immersive environments that are distinctive because of their variation from “real,” such as flat-shaded environments, recruit stronger attentional resources. This additional attentional processing may bring about a change in participants' subjective experiences of “remembering” when they later transfer the training from that environment into a real-world situation.
Perception of mechanically and optically simulated bumps and holes
Authors: Mensvoort Koert Van , Vos Peter , Hermes Dik J. , Liere Robert Van
Published: February 2010

In this article, we investigate the perception of optically simulated haptic feedback. The perception of optically and mechanically simulated bumps and holes was tested experimentally. In an earlier article, we have described the active cursor technique, a method to simulate haptic feedback optically without resorting to special mechanical force feedback devices, commonly applied to produce haptic percepts in computer interfaces. The operation of the force feedback device is substituted by tiny displacements on the cursor position relative to the intended force. This method exploits the domination of the visual over the haptic modality. Results show that people can recognize optically simulated bump and hole structures and that active cursor displacements influence the haptic perception of bumps and holes. Depending on the simulated strength of the force, optically simulated haptic feedback can take precedence over mechanically simulated haptic feedback and also the other way around. When optically simulated and mechanically simulated haptic feedback counteract each other, however, the weight attributed to each source of haptic information differs from user to user. It is concluded that active cursor displacements can be used to simulate the operation of mechanical force feedback devices.
Mesh saliency and human eye fixations
Authors: Kim Youngmin , Varshney Amitabh , Jacobs David W. , Guimbretière François
Published: February 2010

Mesh saliency has been proposed as a computational model of perceptual importance for meshes, and it has been used in graphics for abstraction, simplification, segmentation, illumination, rendering, and illustration. Even though this technique is inspired by models of low-level human vision, it has not yet been validated with respect to human performance. Here, we present a user study that compares the previous mesh saliency approaches with human eye movements. To quantify the correlation between mesh saliency and fixation locations for 3D rendered images, we introduce the normalized chance-adjusted saliency by improving the previous chance-adjusted saliency measure. Our results show that the current computational model of mesh saliency can model human eye movements significantly better than a purely random model or a curvature-based model.
Perceptual organization of affective and sensorial expressive intentions in music performance
Authors: Mion Luca , Poli Giovanni De , Rapanà Ennio
Published: February 2010

Expression communication is the added value of a musical performance. It is part of the reason why music is interesting to listen to and sounds alive. Previous work on the analysis of acoustical features yielded relevant features for the recognition of different expressive intentions, inspired both by emotional and sensorial adjectives. In this article, machine learning techniques are employed to understand how expressive performances represented by the selected features are clustered on a low-dimensional space, and to define a measure of acoustical similarity. Being that expressive intentions are similar according to the features used for the recognition, and since recognition implies subjective evaluation, we hypothesized that performances are similar also from a perceptual point of view. We then compared and integrated the clustering of acoustical features with the results of two listening experiments. A first experiment aims at verifying whether subjects can distinguish different categories of expressive intentions, and a second experiment aims at understanding which expressions are perceptually clustered together in order to derive common evaluation criteria adopted by listeners, and to obtain the perceptual organization of affective and sensorial expressive intentions. An interpretation of the resulting spatial representation based on action is proposed and discussed.
Arrays of Nanoelectrodes: Critical Evaluation of Geometrical and Diffusion Characteristics with Respect to Electroanalytical Applications
Authors: Moretto Ligia M. , Tormen Massimo , Carpentiero Alessandro , Ugo Paolo
Published: February 2010

A relevant increase in the electroanalytical application of sub-micrometer sized electrodes came with the development of arrays of nanoelectrodes. In the nanoelectrode ensembles (NEEs), the spatial distribution of the nanoelectrodes is random, while in the nanoelectrode arrays (NEAs) it is ordered. NEAs are typically fabricated by top-down microfabrication techniques, such as electron-beam lithography or nano-imprinting, while bottom-up technologies, such as the template methods and self-assembly are more often used for NEEs. NEEs/NEAs can exhibit three distinct response regimes depending on the scan rate or distance between the nanoelectrode elements: Total Overlap, Pure Radial and Linear Active. In the present work, NEAs are prepared by e-beam lithography and used for voltammetric measurements.
Electrodeposition of Silicon Thin Films from Ionic Liquids
Authors: Martinez Ana M. , Osen Karen S. , Kongstein Ole Edvard , Sheridan Edel , Ulyashin Alexander G. , Haarberg Geir Martin
Published: February 2010

The possibility of obtaining Si thin films by electrodeposition from the oxygen and water stable N-butyl-N-methyl-pyrrolidinium bis(trifluoromethyl-sulfonyl)amide ionic liquid at room temperature was investigated. The results obtained using SiCl4 and SiBr4 as precursors and aluminium and nickel as substrates were compared. Cyclic voltammetry, square wave voltammetry and chronoamperometry were used to characterize the electroreduction step of the silicon species. The results showed that the growth of the silicon layer is very slow, yielding only clusters of silicon at low cathodic potentials and short electrolysis times. At higher electrodeposition potentials and/or longer deposition times, the films became rougher and cracks appeared in the layers. This was mainly due to the accumulation of tensile strains during growth. The layers were very reactive to air and humidity, probably due to the high porosity of the film. In some cases, contamination of the layers by S and F was also observed
Electrodeposition of Ni/Co and Ni Magnetic Nanowires Using Allumina Template
Authors: Cojocaru Paula , Muscolino Fabio , Magagnin Luca , Vázquez Manuel , Badini-Confalonieri Giuseppe , Carac Geta
Published: February 2010

Nickel and nickel-cobalt alloy nanowires were fabricated through template-assisted electrochemical deposition method and sandwiched between two caps of electrodeposited pure gold. Free standing porous alumina templates were prepared and used for the synthesis of the ordered nanowires. The morphology and composition of as-deposited nanowires were determined by scanning electron microscope. Nanowires were characterized by a diameter of 70 nm, as the alumina template pores diameter, and by a length in the range of 2-3 μm. Backscattered electron signal showed the presence of Au and Ni or Ni-Co sandwich, highlighting a well defined and void free interface between the gold caps and the Ni or Ni-Co layer. Particular optimization has been considered for the subsequent magnetoresistance characterization of nanowires. Angular dependence of magnetoresistance has been measured as a function of temperature from in-plane to perpendicular magnetic field configuration. Anisotropic magnetoresistive measurements suggested a magnetization process by magnetization rotation from nanowire axis towards in-plane orientation.
Consistent Discussion of the Uncertainty of Physical Parameters Evaluated by EIS, Based on an Automatic Measurement Error Determination.
Authors: Schiller Carl-Albrecht , Kaus Rüdiger
Published: February 2010

The entire process of measurement, analysis and interpretation of EIS data usually aims to get a set of characteristic, physical parameters. Both, the quality of the experimental data as well as the uncertainties coming from the analysis procedure affect the numerical accuracy of the parameters. It is shown, that the consideration of the measurement data uncertainty predicted by the weighted harmonic analysis procedure within the overall data processing of a CNLRS fitting procedure leads to reasonable results for an error estimation of the final parameters of interest. In addition, the evaluation of an individual significance of each parameter enables a check of the physical model under test, whether each of the parameters possesses a physical meaning.
In Situ Stress Measurement of Electrodeposited Ni Films by Television Holographic Interferometry
Authors: Fukumuro Naoki , Do Takayoshi , Kakunai Satoshi , Yae Shinji , Matsuda Hitoshi
Published: February 2010

In situ stress measurements of electrodeposited Ni films from a sulfate bath during deposition were carried out by television holographic interferometry. The effect of the addition of saccharin sodium on the internal stress in the Ni films was studied. Structure change with film growth was investigated by cross-sectional TEM observation. Quantitative analysis of impurities and hydrogen in films was performed. The stress behaviors of Ni films changed drastically from a tensile direction to a compressive direction with an increase of the concentration of saccharin sodium.
In vivo exercise followed by in vitro contraction additively elevates subsequent insulin-stimulated glucose transport by rat skeletal muscle
Authors: Funai Katsuhiko , Schweitzer George G. , Castorena Carlos M. , Kanzaki Makoto , Cartee Gregory D.
Published: February 2010

The cellular mechanisms whereby prior exercise enhances insulin-stimulated glucose transport (GT) are not well understood. Previous studies suggested that a prolonged increase in phosphorylation of Akt substrate of 160 kDa (AS160) may be important for the postexercise increase in insulin sensitivity. In the current study, the effects of in vivo exercise and in vitro contraction on subsequent insulin-stimulated GT were studied separately and together. Consistent with results from previous studies, prior exercise resulted in an increase in AS160642Thr phosphorylation immediately after exercise in rat epitrochlearis muscles, and this increase remained 3 h postexercise concomitant with enhanced insulin-stimulated GT. For experiments with in vitro contraction, isolated rat epitrochlearis muscles were electrically stimulated to contract in the presence or absence of rat serum. As expected, insulin-stimulated GT measured 3 h after electrical stimulation in serum, but not after electrical stimulation without serum, exceeded resting controls. Immediately after electrical stimulation with or without serum, phosphorylation of both AS160 (detected by phospho-Akt substrate, PAS, antibody, or phospho-642Thr antibody) and its paralog TBC1D1 (detected by phospho-237Ser antibody) was increased. However, both AS160 and TBC1D1 phosphorylation had reversed to resting values at 3 h poststimulation with or without serum. Increasing the amount of exercise (from 1 to 2 h) or electrical stimulation (from 5 to 10 tetani) did not further elevate insulin-stimulated GT. In contrast, the combination of prior exercise and electrical stimulation had an additive effect on the subsequent increase in insulin-stimulated GT, suggesting that these exercise and electrical stimulation protocols may amplify insulin-stimulated GT through distinct mechanisms, with a persistent increase in AS160 phosphorylation potentially important for increased insulin sensitivity after exercise, but not after in vitro contraction.
Capacity Evaluation for IEEE 802.16e Mobile WiMAX
Authors: So-In Chakchai , Jain Raj , Tamimi Abdel-Karim
Published: February 2010

We present a simple analytical method for capacity evaluation of IEEE 802.16e Mobile WiMAX networks. Various overheads that impact the capacity are explained and methods to reduce these overheads are also presented. The advantage of a simple model is that the effect of each decision and sensitivity to various parameters can be seen easily. We illustrate the model by estimating the capacity for three sample applications—Mobile TV, VoIP, and data. The analysis process helps explain various features of IEEE 802.16e Mobile WiMAX. It is shown that proper use of overhead reducing mechanisms and proper scheduling can make an order of magnitude difference in performance. This capacity evaluation method can also be used for validation of simulation models.
Mechanical Dyssynchrony After Myocardial Infarction in Patients With Left Ventricular Dysfunction, Heart Failure, or Both
Authors: Shin Sung-Hee , Hung Chung-Lieh , Uno Hajime , Hassanein Amira H. , Verma Anil , Bourgoun Mikhail , Køber Lars , Ghali Jalal K. , Velazquez Eric J. , Califf Robert M. , Pfeffer Marc A. , Solomon Scott D.
Published: February 2010

Background—

Mechanical dyssynchrony is considered an independent predictor for adverse cardiovascular outcomes in patients with heart failure. However, its importance as a risk factor after myocardial infarction is not well defined.

Methods and Results—

We examined the influence of mechanical dyssynchrony on outcome in patients with left ventricular dysfunction, heart failure, or both after myocardial infarction who were enrolled in the Valsartan in Acute Myocardial Infarction (VALIANT) echocardiography study. B-mode speckle tracking with velocity vector imaging was used to assess ventricular synchrony in 381 patients who had image quality sufficient for analysis. Time to regional peak velocity and time to strain rate were measured among 12 left ventricular segments from the apical 4- and 2- chamber views, and the SDs between all 12 segments were used as a measure of dyssynchrony. The relationships between the SD of time to regional peak velocity and strain rate and clinical outcome of death or heart failure were assessed. In a multivariate Cox model adjusted for clinical and echocardiographic variables, the SD of time to peak velocity (hazard ratio per 10 ms, 1.10; 95% confidence interval, 1.02 to 1.18;
P
=0.010) and the SD of time to strain rate (hazard ratio per 10 ms, 1.16; 95% confidence interval, 1.06 to 1.27;
P
=0.001) were independent predictors of death or heart failure.

Conclusion—

Left ventricular dyssynchrony is independently associated with increased risk of death or heart failure after myocardial infarction, suggesting that contractile pattern may play a role in post–myocardial infarction prognosis.
Reciprocal Repression Between MicroRNA-133 and Calcineurin Regulates Cardiac Hypertrophy
Authors: Dong De-Li , Chen Chang , Huo Rong , Wang Ning , Li Zhe , Tu Yu-Jie , Hu Jun-Tao , Chu Xia , Huang Wei , Yang Bao-Feng
Published: February 2010

Cardiac hypertrophy involves a remodeling process of the heart in response to diverse pathological stimuli. Both calcineurin/nuclear factor of activated T cells pathway and microRNA-133 (
miR-133
) have been shown to play a critical role in cardiac hypertrophy. It has been recognized that the expression and activity of calcineurin increases and
miR-133
expression decreases in the hypertrophic heart, and inhibition of calcineurin or increase of
miR-133
expression protects against cardiac hypertrophy. Here we tested the interaction between
miR-133
and calcineurin in cardiac hypertrophy. Cardiac hypertrophy in vivo and in vitro was induced by transverse aortic constriction and phenylephrine treatment. mRNA levels were measured by using real-time PCR methods. Luciferase assays showed that transfection of
miR-133
in HEK293 cells downregulated calcineurin expression, which was reversed by cotransfection with the
miR-133
–specific 2′-
O
-methyl antisense inhibitory oligoribonucleotides. These results were confirmed in cultured primary cardiomyocytes.
miR-133
expression was downregulated, and calcineurin activity was enhanced in both in vivo and in vitro cardiac hypertrophy models. Treatment of cells and animals with cyclosporin A, an inhibitor of calcineurin, prevented
miR-133
downregulation. Moreover, the antisense oligodeoxynucleotides against the catalytic subunits of calcineurin Aβ and the decoy oligodeoxynucleotides targeting nuclear factor of activated T cells transcription factor, a calcineurin downstream effector, increased
miR-133
expression in cultured primary cardiomyocytes. Our data show that reciprocal repression between
miR-133
and calcineurin regulates cardiac hypertrophy.
Wnt Signaling Is Critical for Maladaptive Cardiac Hypertrophy and Accelerates Myocardial Remodeling
Authors: Malekar Pratima , Hagenmueller Marco , Anyanwu Adamma , Buss Sebastian , Streit Marcus R. , Weiss Celine S. , Wolf David , Riffel Johannes , Bauer Alexander , Katus Hugo A. , Hardt Stefan E.
Published: February 2010

The evolutionary conserved Wnt signaling pathway regulates cardiogenesis. However, members of the Wnt pathway are also expressed in the adult heart. Although Wnt-signaling is quiescent under normal conditions, we noticed activation on pathological stress of the heart, such as chronic afterload increase. To examine the role of Wnt signaling on the postnatal heart, we modified the expression and function of the Wnt regulator dishevelled 1 (Dvl-1) both in transgenic mice with cardiac-specific overexpression of Dvl-1 (Dvl-1-Tg) and in cultured cardiac myocytes. Dvl-1-Tg mice (3 months) had severe cardiac hypertrophy (heart weight:body weight ratio: 5.2±0.3 mg/g wild-type [WT] versus 6.4±0.7 mg/g Dvl-1-Tg;
P
<0.01), an increase in cardiomyocyte size (86% increase in Dvl-1-Tg compared with WT;
P
<0.01) and marked raise of atrial natriuretic factor expression (12-fold increase versus WT;
P
<0.01). Hypertrophy was associated with left ventricular dilatation in Dvl-1-Tg and a reduction of ejection fraction (4.4±0.1 mm versus 5.5±0.2 mm, 80±2% and 43±4% in WT versus Dvl-1-Tg, respectively;
P
<0.01). Transgenic animals died prematurely before 6 months of age. Both canonical as well as noncanonical Wnt signaling branches were activated in the Dvl-1-Tg animals. Small interfering RNA–mediated depletion of Dvl-1 was used to further characterize the role of Dvl-1 in cardiac myocytes. Whereas baseline parameters were unaltered, β-adrenergic hypertrophic response was abrogated in Dvl-1 knockdown cardiac myocytes, indicating a mandatory role in β-adrenergic stimulation. Therefore, activation of Wnt signaling is sufficient and critical for the induction of myocardial hypertrophy and cardiomyopathy.
Bilingual Education and English Proficiency
Authors: Jepsen Christopher
Published: February 2010

In 2001, California instituted a statewide test measuring English proficiency for English learners, students who are not proficient in English. In 2003 and 2004, nearly 500,000 English learners in grades 1–5 took this test each year. The relationship between bilingual education receipt and English proficiency is estimated using value-added regression models for each section of the test—listening and speaking, reading, and writing. In these regression models, students in bilingual education have substantially lower English proficiency of 0.3 standard deviations or more compared with other English learners in first and second grades. In contrast, the difference between bilingual education and other programs is usually less than 0.1 standard deviations for students in grades 3–5. These results hold for ordinary least squares, school fixed effects, and propensity score models.
Improved Terrestrial Hydrologic Representation in Mesoscale Land Surface Models
Authors: Choi Hyun I. , Liang Xin-Zhong
Published: February 2010

This study addresses several deficiencies in the existing formulations for terrestrial hydrologic processes in the Common Land Model (CLM) and presents improved solutions, focusing on runoff prediction. In particular, this paper has 1) incorporated a realistic geographic distribution of bedrock depth to improve estimates of the actual soil water capacity; 2) replaced an equilibrium approximation with a dynamic prediction of the water table to produce more reasonable variations of the saturated zone depth; 3) used an exponential decay function with soil depth for the saturated hydraulic conductivity to consider the effect of macropores near the ground surface; 4) formulated an effective hydraulic conductivity of the liquid part at the frozen soil interface and imposed a maximum surface infiltration limit to eliminate numerically generated negative or excessive soil moisture solution; and 5) examined an additional contribution to subsurface runoff from saturation lateral runoff or baseflow controlled by topography. To assess the performance of these modifications, runoff results from a set of offline simulations are validated at a catchment-scaled study domain around the Ohio Valley region. Together, these new schemes enable the CLM to capture well the major characteristics of the observed total runoff variations. The improvement is especially significant at peak discharges under high flow conditions.
Effect of uric acid on nephrotoxicity induced by mercuric chloride in rats
Authors: Durante Paula , Romero Freddy , Pérez Mariela , Chávez Maribel , Parra Gustavo
Published: February 2010

Oxidative stress is an important mechanism in mercury poisoning. We studied the effect of uric acid, a natural and potent reactive oxygen species and peroxynitrite scavenger, in HgCl2-induced nephrotoxicity. Rats were injected with a unique dose of HgCl2(2.5 mg/kg body weight, subcutaneously) and then vehicle (for 3 days, twice daily) or HgCl2(unique dose) and intraperitoneal uric acid suspension (250 mg/kg body weight, twice daily, for 3 days), and then killed at 24, 48 and 72 hours after HgCl2administration (n = 5 for each group). At the end of the experimental study, kidneys and blood samples were taken. Tissues were prepared and examined under light microscopy. Uric acid significantly prevented the increase in plasma levels of creatinine and blood urea nitrogen (BUN); it helped maintain systemic nitrate/nitrite concentration and total antioxidant capacity. Uric acid attenuated the increase of renal lipid peroxidation and it markedly diminished nitrotyrosine signal and histopathological changes as early as 24 hours after HgCl2administration. Uric acid did not prevent a decrease in β-actin signal caused by mercuric chloride, but it promoted a faster recovery when compared to the HgCl2alone group. Our results indicate that UA could play a beneficial role against HgCl2toxicity by preventing systemic and renal oxidative stress and tissue damage.
Digital gene expression analysis of two life cycle stages of the human-infective parasite, Trypanosoma brucei gambiense reveals differentially expressed clusters of co-regulated genes
Authors: Veitch Nicola J , Johnson Paul CD , Trivedi Urmi , Terry Sandra , Wildridge David , MacLeod Annette
Published: February 2010

Background

The evolutionarily ancient parasite, Trypanosoma brucei, is unusual in that the majority of its genes are regulated post-transcriptionally, leading to the suggestion that transcript abundance of most genes does not vary significantly between different life cycle stages despite the fact that the parasite undergoes substantial cellular remodelling and metabolic changes throughout its complex life cycle. To investigate this in the clinically relevant sub-species, Trypanosoma brucei gambiense, which is the causative agent of the fatal human disease African sleeping sickness, we have compared the transcriptome of two different life cycle stages, the potentially human-infective bloodstream forms with the non-human-infective procyclic stage using digital gene expression (DGE) analysis.

Results

Over eleven million unique tags were generated, producing expression data for 7360 genes, covering 81% of the genes in the genome. Compared to microarray analysis of the related T. b. brucei parasite, approximately 10 times more genes with a 2.5-fold change in expression levels were detected. The transcriptome analysis revealed the existence of several differentially expressed gene clusters within the genome, indicating that contiguous genes, presumably from the same polycistronic unit, are co-regulated either at the level of transcription or transcript stability.

Conclusions

DGE analysis is extremely sensitive for detecting gene expression differences, revealing firstly that a far greater number of genes are stage-regulated than had previously been identified and secondly and more importantly, this analysis has revealed the existence of several differentially expressed clusters of genes present on what appears to be the same polycistronic units, a phenomenon which had not previously been observed in microarray studies. These differentially regulated clusters of genes are in addition to the previously identified RNA polymerase I polycistronic units of variant surface glycoproteins and procyclin expression sites, which encode the major surface proteins of the parasite. This raises a number of questions regarding the function and regulation of the gene clusters that clearly warrant further study.
Comparative gene expression profiling between human cultured myotubes and skeletal muscle tissue
Authors: Raymond Frederic , Métairon Sylviane , Kussmann Martin , Colomer Jaume , Nascimento Andres , Mormeneo Emma , García-Martínez Cèlia , Gómez-Foix Anna M
Published: February 2010

Background

A high-sensitivity DNA microarray platform requiring nanograms of RNA input facilitates the application of transcriptome analysis to individual skeletal muscle (SM) tissue samples. Culturing myotubes from SM-biopsies enables investigating transcriptional defects and assaying therapeutic strategies. This study compares the transcriptome of aneurally cultured human SM cells versus that of tissue biopsies.

Results

We used the Illumina expression BeadChips to determine the transcriptomic differences between tissue and cultured SM samples from five individuals. Changes in the expression of several genes were confirmed by QuantiGene Plex assay or reverse transcription real-time PCR. In cultured myotubes compared to the tissue, 1216 genes were regulated: 583 down and 633 up. Gene ontology analysis showed that downregulated genes were mainly associated with cytoplasm, particularly mitochondria, and involved in metabolism and the muscle-system/contraction process. Upregulated genes were predominantly related to cytoplasm, endoplasmic reticulum, and extracellular matrix. The most significantly regulated pathway was mitochondrial dysfunction. Apoptosis genes were also modulated. Among the most downregulated genes detected in this study were genes encoding metabolic proteins AMPD1, PYGM, CPT1B and UCP3, muscle-system proteins TMOD4, MYBPC1, MYOZ1 and XIRP2, the proteolytic CAPN3 and the myogenic regulator MYF6. Coordinated reduced expression of five members of the GIMAP gene family, which form a cluster on chromosome 7, was shown, and the GIMAP4-reduction was validated. Within the most upregulated group were genes encoding senescence/apoptosis-related proteins CDKN1A and KIAA1199 and potential regulatory factors HIF1A, TOP2A and CCDC80.

Conclusions

Cultured muscle cells display reductive metabolic and muscle-system transcriptome adaptations as observed in muscle atrophy and they activate tissue-remodeling and senescence/apoptosis processes.
Mechanistic insights from a quantitative analysis of pollen tube guidance
Authors: Stewman Shannon F , Jones-Rhoades Matthew , Bhimalapuram Prabhakar , Tchernookov Martin , Preuss Daphne , Dinner Aaron R
Published: February 2010

Background

Plant biologists have long speculated about the mechanisms that guide pollen tubes to ovules. Although there is now evidence that ovules emit a diffusible attractant, little is known about how this attractant mediates interactions between the pollen tube and the ovules.

Results

We employ a semi-in vitro assay, in which ovules dissected from Arabidopsis thaliana are arranged around a cut style on artificial medium, to elucidate how ovules release the attractant and how pollen tubes respond to it. Analysis of microscopy images of the semi-in vitro system shows that pollen tubes are more attracted to ovules that are incubated on the medium for longer times before pollen tubes emerge from the cut style. The responses of tubes are consistent with their sensing a gradient of an attractant at 100-150 μm, farther than previously reported. Our microscopy images also show that pollen tubes slow their growth near the micropyles of functional ovules with a spatial range that depends on ovule incubation time.

Conclusions

We propose a stochastic model that captures these dynamics. In the model, a pollen tube senses a difference in the fraction of receptors bound to an attractant and changes its direction of growth in response; the attractant is continuously released from ovules and spreads isotropically on the medium. The model suggests that the observed slowing greatly enhances the ability of pollen tubes to successfully target ovules. The relation of the results to guidance in vivo is discussed.
STIL, a peculiar molecule from styles, specifically dephosphorylates the pollen receptor kinase LePRK2 and stimulates pollen tube growth in vitro
Authors: Wengier Diego L , Mazzella María A , Salem Tamara M , McCormick Sheila , Muschietti Jorge P
Published: February 2010

Background

LePRK1 and LePRK2 are two pollen receptor kinases localized to the plasma membrane, where they are present in a high molecular weight complex (LePRK complex). LePRK2 is phosphorylated in mature and germinated pollen, but is dephosphorylated when pollen membranes are incubated with tomato or tobacco style extracts.

Results

Here we show that LePRK2 dephosphorylation is mediated by a heat-, acid-, base-, DTT- and protease-resistant component from tobacco styles. Using LePRK2 phosphorylation as a tracking assay for purification, style exudates were subjected to chloroform extraction, anionic exchange, and C18 reverse-phase chromatography columns. We finally obtained a single ~3,550 Da compound (as determined by UV-MALDI-TOF MS) that we named STIL (for Style Interactor for LePRKs). STIL increased pollen tube lengths of in vitro germinated pollen in a dose-dependent manner.

Conclusion

We propose that the LePRK complex perceives STIL, resulting in LePRK2 dephosphorylation and an increase in pollen tube growth.
Genetic diversity of NS5A protein from hepatitis C virus genotype 3a and its relationship to therapy response
Authors: Bittar Cíntia , Jardim Ana Carolina G , Yamasaki Lilian HT , de Queiróz Artur TL , Carareto Claudia MA , Pinho João Renato R , de Carvalho-Mello Isabel Maria VG , Rahal Paula
Published: February 2010

Background

The quasispecies nature of HCV may have important implications for viral persistence, pathogenicity and resistance to antiviral agents. The variability of one of the viral proteins, NS5A, is believed to be related to the response to IFN therapy, the standard treatment for infection. In this study we analyzed the quasispecies composition of NS5A protein in patients infected with HCV genotype 3a, before IFN therapy.

Methods

Viral RNA was isolated from samples of 12 patients: four sustained virological responders (SVR), four non-responders (NR), and four end-of-treatment responders (ETR). cDNA was synthesized, the NS5A region was amplified and the fragments obtained were cloned. Fifteen clones from each patient were sequenced with eight primers, generating 179 contigs.

Results

Higher values for substitution (either synonymous or non-synonymous) and for distance were found in the SVR group. However, the NR group showed relatively more non-synonymous mutations than the other groups, owing to the higher values of dN/dS in complete NS5A and most specific regions. Overall, NS5A protein is undergoing purifying selection, since all dN/dS ratios values are below 0.5.

Conclusions

Our study provides an overview of the genetic variability of complete NS5A protein in HCV genotype 3a.
Activated CD4+T cells enhance radiation effect through the cooperation of interferon-γ and TNF-α
Authors: Wang Yixiang , Radfar Soroosh , Khong Hung T
Published: February 2010

Background

Approaches that enhance radiation effect may lead to improved clinical outcome and decrease toxicity. Here we investigated whether activated CD4+ T cells (aCD4) can serve as an effective radiosensitizer.

Methods

CD4+ T cells were activated with anti-CD3 and anti-CD28 mAbs. Hela cells were presensitized with aCD4 or conditioned supernatant (aCD4S) or recombinant cytokines for 2 days, followed γ-irradiation. The treated cells were cultured for an additional 2 to 5 days for cell proliferation, cell cycle, and western blot assays. For confirmation, other cancer cell lines were also used.

Results

Presensitization of tumor cells with aCD4 greatly increased tumor cell growth inhibition. Soluble factors secreted from activated CD4+T cells were primarily responsible for the observed effect. IFN-γ seemed to play a major role. TNF-α, though inactive by itself, significantly augmented the radiosensitizing activity of IFN-γ. aCD4S, but not IFN-γ or IFN-γ/TNF-α combination, was found to enhance the γ-irradiation-induced G2/M phase arrest. Bax expression was highly upregulated in Hela cells presensitized with aCD4S followed by γ-irradiation. The radio-sensitizing activity of aCD4 is not uniquely observed with Hela cell line, but also seen with other cancer cell lines of various histology.

Conclusions

Our findings suggest possible molecular and cellular mechanisms that may help explain the radio-sensitization effect of activated lymphocytes, and may provide an improved strategy in the treatment of cancer with radiotherapy.