bluuebunny/crossref_metadata_2025_split huggingface dataset:
Brain potentials and behavioral responses associated with attention to hard‐ and easy‐to‐discriminate passive knee joint movements
Authors: Smid H. G. O. M. , Hauser U. , Weiler H. T. , Awiszus F. , Hinrichs H. , Heinze H.‐J. 
Published: December 2004

AbstractWe investigated event‐related brain potentials (ERPs) to passive ramp movements of the knee joint. The knee movements were either attended or unattended and were either very easy or very hard to detect. We used special methods to ensure that movement only activated muscle spindle and joint receptors. The first movement‐related ERP started 20 ms after movement onset, and had a contralateral maximum. This initial ERP did not differ as a function of attention and movement discriminability. Signal detection analysis of the behavioral data suggested that hard‐to‐detect movements could be discriminated above chance level, but were not reported because of a decision bias. At 60–100 ms, an ERP was observed that discriminated detected from undetected hard‐to‐detect movements. Starting at 80 ms, we found an ERP that was unique to movements that were attended and easy to detect. We discuss that (1) the initial ERP reflects activation of preconscious sensory processors, (2) the second ERP may reflect detection that fails to attract attention, and (3) the third ERP reflects active focusing of attention on the movement.
Processing sentence context in women with schizotypal personality disorder: An ERP study
Authors: Niznikiewicz Margaret A. , Friedman Michelle , Shenton Martha E. , Voglmaier Martina , Nestor Paul G. , Frumin Melissa , Seidman Larry , Sutton John , McCarley Robert W. 
Published: December 2004

AbstractAccumulating evidence suggests that schizophrenic patients do not use context efficiently. Also, studies suggest similarities in clinical and cognitive profiles between schizophrenic and schizotypal personality disorder (SPD) individuals, and epidemiological studies point to a genetic link between the two disorders. This study examined electrophysiological correlates of processing sentence context in a group of SPD women in a classical N400 sentence paradigm. The study assessed if the dysfunction in context use found previously in schizophrenia and male SPD also exists in female SPD. We tested 17 SPD and 16 matched normal control women. The results suggest the presence of abnormality in context use in female SPD similar to that previously reported for male schizophrenic and SPD individuals, but of lesser degree of severity. In SPD women, relative to their comparison group, a more negative N400 was found only to auditory congruent sentences.
ERD as an index of anticipatory attention? Effects of stimulus degradation
Authors: Bastiaansen Marcel C.M. , Böcker Koen B.E. , Brunia Cornelis H.M. 
Published: December 2004

Previous research has suggested that the stimulus‐preceding negativity (SPN) is largely independent of stimulus modality. In contrast, the scalp topography of the event‐related desynchronization (ERD) related to the anticipation of stimuli providing knowledge of results (KR) is modality dependent. These findings, combined with functional SPN research, lead to the hypothesis that anticipatory ERD reflects anticipatory attention, whereas the SPN mainly depends on the affective‐motivational properties of the anticipated stimulus. To further investigate the prestimulus ERD, and compare this measure with the SPN, 12 participants performed a time‐estimation task, and were informed about the quality of their time estimation by an auditory or a visual stimulus providing KR. The KR stimuli could be either intact or degraded.Auditory degraded KR stimuli were less effective than other KR stimuli in guiding subsequent behavior, and were preceded by a larger SPN. There were no effects of degradation on the SPN in the visual modality. Preceding auditory KR stimuli no ERD was present, whereas preceding visual stimuli an occipital ERD was found. However, contrary to expectation, the latter was larger preceding intact than preceding degraded stimuli. It is concluded that the data largely agree with an interpretation of the pre‐KR SPN as a reflection of the anticipation of the affective‐motivational value of KR stimuli, and of the prestimulus ERD as a perceptual anticipatory attention process.
Aquaporins account for variations in hydraulic conductance for metabolically active root regions of Agave deserti in wet, dry, and rewetted soil
Authors: NORTH G. B. , MARTRE P. , NOBEL P. S. 
Published: December 2004

ABSTRACTThe importance of aquaporins for root hydraulic conductance (LP) was investigated along roots of the desert succulent Agave deserti in wet, dry and rewetted soil. Water channel activity was inferred from HgCl2‐induced reductions of LP that were reversible by 2‐mercaptoethanol. Under wet conditions, HgCl2 reduced LP for the distal root region by 50% and for the root region near the shoot base by 36% but did not affect LP for the mid‐root region. For all root regions, LP decreased by 30–60% during 10 d in drying soil and was not further reduced by HgCl2. After soil rewetting, LP increased to pre‐drying values and was again reduced by HgCl2 for the distal and the basal root regions but not the mid‐root region. For the distal region, water channels in the epidermis/exodermis made a disproportionately large contribution to radial hydraulic conductance of the intact segment; for the basal region, water channel activity was highest in the cortex and endodermis. The role of water channels was greatest in tissues in which cells were metabolically active both in the distal root region, where new apical growth occurs in wet soil, and in the basal region, which is the most likely root region to intercept light rainfall.
Properties of ion channels in the protoplasts of the Mediterranean seagrass Posidonia oceanica
Authors: CARPANETO A. , NASO A. , PAGANETTO A. , CORNARA L. , PESCE E.‐R. , GAMBALE F. 
Published: December 2004

ABSTRACT Posidonia oceanica (L) Delile, a seagrass endemic of the Mediterranean sea, provides food and shelter to marine organisms. As environment contamination and variation in physico‐chemical parameters may compromise the survival of the few Posidonia genotypes living in the Mediterranean, comprehending the molecular mechanisms controlling Posidonia growth and development is increasingly important. In the present study the properties of ion channels in P. oceanica plasma membranes studied by the patch‐clamp technique in protoplasts obtained from the young non‐photosynthetic leaves were investigated. In protoplasts that were presumably originated from sheath cells surrounding the vascular bundles of the leaves, an outward‐rectifying time‐dependent channel with a single channel conductance of 58 ± 2 pS which did not inactivate, was selective for potassium and impermeable to monovalent cations such as Na+, Li+ and Cs+ was identified. In the same protoplasts, an inward‐rectifying channel that has a time‐dependent component with single channel conductance of the order of 10 pS, a marked selectivity for potassium and no permeation to sodium was also identified, as was a third type of channel that did not display any ionic selectivity and was reversibly inhibited by tetraethylammonium and lanthanum. A comparison of Posidonia channel characteristics with channels identified in terrestrial plants and other halophytic plants is included.
Does turgor limit growth in tall trees?
Authors: WOODRUFF D. R. , BOND B. J. , MEINZER F. C. 
Published: December 2004

ABSTRACTThe gravitational component of water potential contributes a standing 0.01 MPa m−1to the xylem tension gradient in plants. In tall trees, this contribution can significantly reduce the water potential near the tree tops. The turgor of cells in buds and leaves is expected to decrease in direct proportion with leaf water potential along a height gradient unless osmotic adjustment occurs. The pressure–volume technique was used to characterize height‐dependent variation in leaf tissue water relations and shoot growth characteristics in young and old Douglas‐fir trees to determine the extent to which growth limitation with increasing height may be linked to the influence of the gravitational water potential gradient on leaf turgor. Values of leaf water potential (Ψl), bulk osmotic potential at full and zero turgor, and other key tissue water relations characteristics were estimated on foliage obtained at 13.5 m near the tops of young (approximately 25‐year‐old) trees and at 34.7, 44.2 and 55.6 m in the crowns of old‐growth (approximately 450‐year‐old) trees during portions of three consecutive growing seasons. The sampling periods coincided with bud swelling, expansion and maturation of new foliage. Vertical gradients ofΨland pressure–volume analyses indicated that turgor decreased with increasing height, particularly during the late spring when vegetative buds began to swell. Vertical trends in branch elongation, leaf dimensions and leaf mass per area were consistent with increasing turgor limitation on shoot growth with increasing height. During the late spring (May), no osmotic adjustment to compensate for the gravitational gradient ofΨlwas observed. By July, osmotic adjustment had occurred, but it was not sufficient to fully compensate for the vertical gradient ofΨl. In tall trees, the gravitational component ofΨlis superimposed on phenologically driven changes in leaf water relations characteristics, imposing potential constraints on turgor that may be indistinguishable from those associated with soil water deficits.
Isoprenoid emission in trees of Quercus pubescens and Quercus ilex with lifetime exposure to naturally high CO2 environment†
Authors: RAPPARINI F. , BARALDI R. , MIGLIETTA F. , LORETO F. 
Published: December 2004

ABSTRACTThe long‐term effect of elevated atmospheric CO2 on isoprenoid emissions from adult trees of two Mediterranean oak species (the monoterpene‐emitting Quercus ilex L. and the isoprene‐emitting Quercus pubescens Willd.) native to a high‐CO2 environment was investigated. During two consecutive years, isoprenoid emission was monitored both at branch level, measuring the actual emissions under natural conditions, and at leaf level, measuring the basal emissions under the standard conditions of 30 °C and at light intensity of 1000 µmol m−2 s−1. Long‐term exposure to high atmospheric levels of CO2 did not significantly affect the actual isoprenoid emissions. However, when leaves of plants grown in the control site were exposed for a short period to an elevated CO2 level by rapidly switching the CO2 concentration in the gas‐exchange cuvette, both isoprene and monoterpene basal emissions were clearly inhibited. These results generally confirm the inhibitory effect of elevated CO2 on isoprenoid emission. The absence of a CO2 effect on actual emissions might indicate higher leaf temperature at elevated CO2, or an interaction with multiple stresses some of which (e.g. recurrent droughts) may compensate for the CO2 effect in Mediterranean ecosystems. Under elevated CO2, isoprene emission by Q. pubescens was also uncoupled from the previous day's air temperature. In addition, pronounced daily and seasonal variations of basal emission were observed under elevated CO2 underlining that correction factors may be necessary to improve the realistic estimation of isoprene emissions with empirical algorithms in the future. A positive linear correlation of isoprenoid emission with the photosynthetic electron transport and in particular with its calculated fraction used for isoprenoid synthesis was found. The slope of this relationship was different for isoprene and monoterpenes, but did not change when plants were grown in either ambient or elevated CO2. This suggests that physiological algorithms may usefully predict isoprenoid emission also under rising CO2 levels.
High growing temperatures reduce fruit carbohydrate and vitamin C in kiwifruit
Authors: RICHARDSON A. C. , MARSH K. B. , BOLDINGH H. L. , PICKERING A. H. , BULLEY S. M. , FREARSON N. J. , FERGUSON A. R. , THORNBER S. E. , BOLITHO K. M. , MACRAE E. A. 
Published: December 2004

AbstractKiwifruit vines are perennial plants grown in climates varying from maritime to continental. To determine key responses to temperature, vines were heated at different stages of fruit development, and vine growth and fruit composition examined. Heating vines during fruit starch accumulation caused a major shift in partitioning towards vegetative growth and dramatically reduced fruit carbohydrate and vitamin C. In the following season, growth and flowering were severely reduced. Heating vines during fruit cell division had minimal long‐term effects, whereas heating during fruit maturation delayed starch degradation and fruit ripening and affected growth in the following season. When vines were removed from heat, fruit dry matter, starch and sugar levels were always reduced but hexose : sucrose ratios and inositol were raised. Heating vines affected expression of two sucrose synthase genes, but this did not correlate with reduction in fruit carbohydrate. Activity and expression of l‐galactose dehydrogenase decreased as fruit developed, suggesting some vitamin C biosynthesis must take place in the fruit. Activity and expression of actinidin increased in response to heat. The results of this study have demonstrated both short and long‐term plant responses to elevated temperatures in woody perennials, and that the timing of heat exposure has severe consequences for vitamin C levels in fruit.
The uncoupling protein and the potassium channel are activated by hyperosmotic stress in mitochondria from durum wheat seedlings
Authors: TRONO D. , FLAGELLA Z. , LAUS M. N. , FONZO N. DI , PASTORE D. 
Published: December 2004

ABSTRACTThe plant uncoupling mitochondrial protein (PUMP) and the plant mitochondrial potassium channel (PmitoKATP) are two recently discovered energy‐dissipating systems present in plant mitochondria, which may play a role as defence systems under environmental stress. To verify whether hyperosmotic stress affects the two dissipating systems in durum wheat (Triticum durum Desf.), their functioning was studied in early etiolated seedlings maintained under moderate and severe salt (NaCl) and osmotic (mannitol) stress. As measures of mitochondrial stress mitochondrial integrity, membrane potential maintenance and oxygen uptake coupled with ATP synthesis during succinate and proline oxidation were investigated. Both PUMP and PmitoKATP were activated under stress conditions. Activation was clearly evident even under moderate stress when proline oxidation was inhibited, although mitochondrial integrity and succinate oxidation were still unaffected. Under severe stress, which significantly affected all the tested indicators of mitochondrial integrity and functionality, PUMP and PmitoKATP activation was further enhanced. Interestingly, both systems were activated by reactive oxygen species and were able to control mitochondrial superoxide anion production. These results suggest that PUMP and PmitoKATP serve as early antioxidant defence systems in response to hyperosmotic stress and that they are involved in a prolonged response to stress.
Infection and colonization of melon roots by Monosporascus cannonballus in two cropping seasons in Arizona and California
Authors: Stanghellini M. E. , Kim D. H. , Waugh M. M. , Ferrin D. M. , Alcantara T. , Rasmussen S. L. 
Published: December 2004

Although canopy collapse of melons (one of the above‐ground symptoms of vine decline caused by Monosporascus cannonballus) occurred late in the growing season, the onset of root infection occurred much earlier. In three early winter‐spring and two late winter‐spring crops, the onset of root infection occurred 47–65 and 35–36 days after planting, respectively. In contrast, in four summer‐autumn crops, the onset of root infection occurred within 9–17 days after planting. Vine decline occurred commonly in winter‐spring crops, but did not occur in any of the summer‐autumn crops. Following the onset of root infection, the percentage of plants infected increased at rates of 0·031–0·036 and 0·038–0·070 per unit per day for winter‐spring and summer‐autumn crops, respectively, based on the monomolecular disease progress model. Root lesions were first observed 14–42 days after the onset of infection in winter‐spring crops, and 14–28 days after the onset of infection in summer‐autumn crops. Pathogen reproduction occurred primarily at the end of each growing season.
Habitat characteristics and seasonal changes ofLaurencia brongniartii(CeramiaIes, Rhodophyta) in Kagoshima, Southern Japan
Authors: Nishihara Gregory N. , Mori Yuko , Terada Ryuta , Noro Tadahide 
Published: December 2004

SUMMARYThe seasonal change in size ofLaurencia brongniartiiwas observed for the year 2002 at Banshobana Park, Satsuma Peninsula and Tsuchihama Beach, Amami Oshima, both in Kagoshima Prefecture, Japan. Additionally, the vertical distribution of this species was also studied at Tsuchihama Beach (second site), where the largest populations were found. Maximum lengths were observed in October ‐ November with a size of 100 ± 6 mm at Banshobana Park and 111 ± 5 mm at Tsuchihama Beach. Line‐transects conducted at Tsuchihama Beach, were analyzed to determine the vertical distribution ofL. brongniartiidue to depth and the slope of the substrate. Alga was found growing in areas restricted to low levels of light.
Identification and characterization of QTL controlling Agrobacterium‐mediated transient and stable transformation of Brassica oleracea
Authors: Cogan Noel O. I. , Newbury H. John , Oldacres Angela M. , Lynn James R. , Kearsey Michael J. , King Graham J. , Puddephat Ian J. 
Published: December 2004

SummaryA commonly encountered difficulty with the genetic engineering of crop plants is that different varieties of a particular species can show great variability in the efficiency with which they can be transformed. This increases the effort required to introduce transgenes into particular genetic backgrounds. The use of Substitution Lines has allowed the finer mapping of three Quantitative Trait Loci (tf1, tf2 and tf3) that explain 26% of the variation in the efficiency of Agrobacterium‐mediated transformation in Brassica oleracea. Use of an ‘orthogonal set’ of genotypes (containing all eight possible combinations of ‘positive’ and ‘negative’ alleles at the three QTL), along with time course studies of transgene expression, has allowed the determination of the stages at which these genes have their effects during transformation. With regard to control of the level of transient transgene expression, tf1 (on LGO1) alone has no detectable effect, whilst tf2 (on LGO3) and tf3 (on LGO7) have highly significant effects (P < 0.001). All three loci have highly significant (P < 0.001) effects on the levels of expression of stably integrated transgene. The use of RFLP markers has shown that tf1 and tf2 are in duplicated regions of the B. oleracea genome and appear to be paralogous in origin. Colinearity of these regions with the A. thaliana genome has been identified. The results allow the selection of progeny Brassica oleracea genotypes that are more efficiently transformed than either parent used in the original cross.
On Difference-Based Variance Estimation in Nonparametric Regression When the Covariate is High Dimensional
Authors: Munk Axel , Bissantz Nicolai , Wagner Thorsten , Freitag Gudrun 
Published: December 2004

SummaryWe consider the problem of estimating the noise variance in homoscedastic nonparametric regression models. For low dimensional covariates t ∈ ℝd, d=1, 2, difference-based estimators have been investigated in a series of papers. For a given length of such an estimator, difference schemes which minimize the asymptotic mean-squared error can be computed for d=1 and d=2. However, from numerical studies it is known that for finite sample sizes the performance of these estimators may be deficient owing to a large finite sample bias. We provide theoretical support for these findings. In particular, we show that with increasing dimension d this becomes more drastic. If d⩾4, these estimators even fail to be consistent. A different class of estimators is discussed which allow better control of the bias and remain consistent when d⩾4. These estimators are compared numerically with kernel-type estimators (which are asymptotically efficient), and some guidance is given about when their use becomes necessary.
Sparsity and Smoothness Via the Fused Lasso
Authors: Tibshirani Robert , Saunders Michael , Rosset Saharon , Zhu Ji , Knight Keith 
Published: December 2004

SummaryThe lasso penalizes a least squares regression by the sum of the absolute values (L1-norm) of the coefficients. The form of this penalty encourages sparse solutions (with many coefficients equal to 0). We propose the ‘fused lasso’, a generalization that is designed for problems with features that can be ordered in some meaningful way. The fused lasso penalizes the L1-norm of both the coefficients and their successive differences. Thus it encourages sparsity of the coefficients and also sparsity of their differences—i.e. local constancy of the coefficient profile. The fused lasso is especially useful when the number of features p is much greater than N, the sample size. The technique is also extended to the ‘hinge’ loss function that underlies the support vector classifier. We illustrate the methods on examples from protein mass spectroscopy and gene expression data.
Risk-Reducing Shrinkage Estimation for Generalized Linear Models
Authors: Spitzner Dan J. 
Published: December 2004

SummaryEmpirical Bayes techniques for normal theory shrinkage estimation are extended to generalized linear models in a manner retaining the original spirit of shrinkage estimation, which is to reduce risk. The investigation identifies two classes of simple, all-purpose prior distributions, which supplement such non-informative priors as Jeffreys's prior with mechanisms for risk reduction. One new class of priors is motivated as optimizers of a core component of asymptotic risk. The methodology is evaluated in a numerical exploration and application to an existing data set.
Primary cell wall metabolism: tracking the careers of wall polymers in living plant cells
Authors: Fry Stephen C. 
Published: December 2004

SummaryNumerous examples have been presented of enzyme activities, assayed in vitro, that appear relevant to the synthesis of structural polysaccharides, and to their assembly and subsequent degradation in the primary cell walls (PCWs) of higher plants. The accumulation of the corresponding mRNAs, and of the (immunologically recognized) proteins, has often also (or instead) been reported. However, the presence of these mRNAs, antigens and enzymic activities has rarely been shown to correspond to enzyme action in the living plant cell. In some cases, apparent enzymic action is observed in vivo for which no enzyme activity can be detected in in‐vitro assays; the converse also occurs. Methods are reviewed by which reactions involving structural wall polysaccharides can be tracked in vivo. Special attention is given to xyloglucan endotransglucosylase (XET), one of the two enzymic activities exhibited in vitro by xyloglucan endotransglucosylase/hydrolase (XTH) proteins, because of its probable importance in the construction and restructuring of the PCW's major hemicellulose. Attention is also given to the possibility that some reactions observed in the PCW in vivo are not directly enzymic, possibly involving the action of hydroxyl radicals. It is concluded that some proposed wall enzymes, for example XTHs, do act in vivo, but that for other enzymes this is not proven.

Contents

I.
Primary cell walls: composition, deposition and roles
642

II.
Reactions that have been proposed to occur in primary cell walls
645

III.
Tracking the careers of wall components in vivo: evidence for action of enzymes in the walls of living plant cells
656

IV.
Evidence for the occurrence of nonenzymic polymer scission in vivo?
666

VI.
Conclusion
667

References
667