bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of copper patinas using ion beam analysis and scanning electron microscopy
Authors: Noli F. , Misaelides P. , Pavlidou E. , Kokkoris M.
Published: January 2005

Ion beam analysis (IBA) techniques were applied successfully to the investigation of non‐corroded and artificially corroded patina layers grown on copper substrates in order to explore their potential use in the study of degradation phenomena of copper and copper alloys subjected to chemical treatment and exposed to selected environmental conditions. Rutherford backscattering spectroscopy (RBS) with deuterons as projectiles and the nuclear reactions 16O(d,p)17O and 32S(p,p′γ)32S were applied to the investigation of the depth distribution of oxygen and sulphur in near‐surface layers of synthetic patina consisting of mineral phases corresponding to chalcanthite as well as to cuprite + chalcanthite and antlerite + brochantite + chalcanthite. Electrochemical techniques (potentiodynamic polarization and cyclic voltammetry in 0.5 M Na2SO4) were used for artificial acceleration and study of the corrosion processes, and scanning electron microscopy (SEM/EDS) was used for examination of the surface morphology of the samples. A patinated roof sample from the Vienna Hofburg also was investigated using the same techniques. The measurement showed that IBA can provide valuable information for the study of patina near‐surface layers of thickness up to a few micrometres and indicated that cuprite was the mineral phase primarily formed on the copper substrates and the main component of the interface between the patina layer and the metallic substrate. The investigated copper patinas looked rather heterogeneous and were characterized by high porosity. Mixed patinas exhibited considerable stability to further corrosive attack. Copyright © 2005 John Wiley & Sons, Ltd.
Illustration of the interface between N2/CO2 plasmas and polystyrene surface
Authors: Wang Meng‐Jiy , Chang You‐Im , Poncin‐Epaillard F.
Published: January 2005

Plasma treatment results in the surface modification of materials and its effects generally can be examined by surface analytical methods such as contact angle measurement, XPS, atomic force microscopy, etc. In situ studies such as mass spectrometry and optical emission spectroscopy usually have been employed to analyse the reactive species in the plasma phase and provide information related to the mechanism of plasma treatment processes. This work shows that in situ studies not only verify the results of plasma treatment but also can provide a more effective method to analyse the mechanism of the plasma/surface interaction process, such as identification of the reactive species leading to functionalization of the surface and the species resulting from surface degradation. These real‐time diagnostic methods confirm the suitable treatment conditions for both N2 and CO2 plasmas for an applied power range of 20–40 W and a flow rate of 5–10 sccm, as shown previously with ex situ surface analyses. Copyright © 2005 John Wiley & Sons, Ltd.
Study of SHIP‐binding cell surface proteins suggests c‐kit as a SHIP‐interacting receptor in mast cells
Authors: Ott Vanessa L. , Moffitt Lisa A. , Cambier John C.
Published: January 2005

Mast cells play a central role in a wide range of immunological and pathological processes, but are most noted for their role in IgE‐dependent allergic responses. Aggregation of the high‐affinity receptor for IgE, FcηRI, stimulates mast cell degranulation, production of lipid mediators, and the synthesis and secretion of cytokines and chemokines. FcηRI‐induced mast cell activation is subject to regulation by inhibitory receptors that transduce intracellular signals via associating phosphatases. The inositol 5‐phosphatase SHIP has been implicated in FcγIIB‐mediated inhibition of FcηRI‐induced mast cell activation. However, SHIP also negatively regulates FcηRI signaling independent of FcγRIIB, suggesting the existence of additional receptors that mediate SHIP recruitment into sites where it mediates its inhibitory function. Here we show that SHIP associates with numerous phosphoproteins from pervanadate‐stimulated mast cells. Based on their sensitivity to PNGase F treatment and cell surface biotinylation, some of these molecules may represent cell surface receptors. A prominent 120−130 kDa SHIP‐binding phosphoprotein was identified in untreated RBL‐2H3 cells and BMMC stimulated with stem cell factor. Based on its molecular weight, sensitivity to PNGase F, and reactivity with an anti‐c‐kit antibody, we conclude that this phosphoprotein is c‐kit. Furthermore, tyrosine phosphorylation of SHIP is enhanced following SCF stimulation. Taken together, these data suggest that SHIP may function as a negative regulator of SCF signaling via direct association with phosphorylated c‐kit.
Effects of thematic‐based, hands‐on science teaching versus a textbook approach for students with disabilities
Authors: McCarthy Cheryl B.
Published: January 2005

Institutions of higher education, states, and local K–12 districts have been challenged to improve math and science education for our nation's students. In the past few years, there has been renewed interest in inquiry‐based, activity‐oriented instruction in science for students with disabilities. Yet, there still exists the need for further empirical evidence to support instructional improvements for students with more involved emotional and behavioral disabilities. This study describes a program in which 18 middle school students with serious emotional disturbances were instructed, over the course of 8 weeks, on “Matter” by two different instructional approaches. Students in one classroom received a traditional textbook approach to science content, whereas students in another classroom received science instruction by a hands‐on, thematic approach. Over the course of instruction, data were collected regarding students' behavior and achievement. Results indicate that, overall, students in the hands‐on instructional program performed significantly better than the students in the textbook program on two of three measures of science achievement, a hands‐on assessment and a short‐answer test. The students did not differ on a multiple‐choice format test. With regard to behavior, there were no significant differences in behavioral problems found between the two groups of students over the course of the study. Findings are discussed in relation to instructional implications for students with disabilities in the science classroom. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 42: 245–263, 2005
Regulation of the transcription factor, CTCF, by phosphorylation with protein kinase CK2
Authors: El-Kady Ayman , Klenova Elena
Published: February 2005

CTCF is a transcription factor involved in various aspects of gene regulation. We previously reported that CTCF function is modulated by protein kinase CK2. In this report we investigate further the role of CK2 in regulating the transcriptional properties of CTCF. We demonstrate that coexpression of CTCF with CK2 switches function of CTCF from repressor to activator. The non‐phosphorylatable mutant increases repression by CTCF and potentiates the growth‐suppressive ability of the protein, whereas the phospho‐mimetic mutant behaves in the opposite fashion. Mutation of the individual serines reveals that Serine 612 is a critical residue in regulation of CTCF by CK2.
Free fatty acids increase PGC‐1α expression in isolated rat islets
Authors: Zhang Peixiang , Liu Chang , Zhang Chunni , Zhang Yan , Shen Pingping , Zhang Junfeng , Zhang Chen-Yu
Published: February 2005

PGC‐1α mRNA and protein are elevated in islets from multiple animal models of diabetes. Overexpression of PGC‐1α impairs glucose‐stimulated insulin secretion (GSIS). However, it is not well known which metabolic events lead to upregulation of PGC‐1α in the β‐cells under pathophysiological condition. In present study, we have investigated effects of chronic hyperlipidemia and hyperglycemia on PGC‐1α mRNA expression in isolated rat islets. Isolated rat islets are chronically incubated with 0, 0.2 and 0.4 mM oleic acid/palmitic acid (free fatty acids, FFA) or 5.5 and 25 mM glucose for 72 h. FFA dose‐dependently increases PGC‐1α mRNA expression level in isolated islets. FFA also increases PGC‐1α expression in mouse β‐cell‐derived βTC3 cell line. In contrast, 25 mM glucose decreases expression level of PGC‐1α. Inhibition of PGC‐1α by siRNA improves FFA‐induced impairment of GSIS in islets. These data suggest that hyperlipidemia and hyperglycemia regulate PGC‐1α expression in islets differently, and elevated PGC‐1α by FFA plays an important role in chronic hyperlipidemia‐induced β‐cell dysfunction.
High resolution DNA fingerprinting by AFLP to study the genetic variation amongOesophagostomum bifurcum(Nematoda) from human and non-human primates from Ghana
Authors: DE GRUIJTER J. M. , GASSER R. B. , POLDERMAN A. M. , ASIGRI V. , DIJKSHOORN LENIE
Published: February 2005

An AFLP approach was established to investigate genetic diversity withinOesophagostomum bifurcum(order Strongylida) from human and non-human primates. Evaluation of different combinations of restriction enzymes (n=8) and primers (n=29) demonstrated that the use ofHindIII/BglII digested templates and primers with the selective nucleotides +AG/+AC, respectively, was the most effective for the analysis ofO. bifurcumDNA. A total of 63O. bifurcumadults from human, Patas monkey, Mona monkey and Olive baboon hosts from different geographical regions in Ghana were subjected to analysis using this method. Cluster analysis revealed 4 genetically distinct groups, namelyO. bifurcumfrom the Patas monkey (I), from the Mona monkey (II), from humans (III) and from the Olive baboon (IV). These findings were concordant with those achieved previously using RAPD analysis and supports population genetic substructuring withinO. bifurcumaccording to host species. The results demonstrated the effectiveness of the present AFLP method for establishing genetic variation withinO. bifurcum, and indicates its applicability to other parasitic nematodes of human and/or veterinary health importance.
Medium-term temporal stability of the helminth component community structure in bank voles (Clethrionomys glareolus) from the Mazury Lake District region of Poland
Authors: BAJER A. , BEHNKE J. M. , PAWEŁCZYK A. , KULIŚ K. , SEREDA M. J. , SIŃSKI E.
Published: February 2005

The structure of helminth communities in wild rodents is subject to seasonal variation, and is dependent on host age within years. Although between-year variation has been monitored, seldom has it been assessed rigorously by appropriate multifactorial analysis with potentially confounding factors taken into account. In this study we tested the null hypothesis that despite seasonal, host age and sex effects, helminth communities should show relative stability between years. Over a period of 3 years (1998–2000) we sampled bank vole (Clethrionomys glareolus) populations (totaln=250) at 2 points in the year: in spring, at the start of the breeding season, and in autumn, after the cessation of breeding. In spite of seasonal differences and strong age effects, the between-year effects were surprisingly small. Measures of component community structure (Berger-Parker dominance index, the dominant species,S. petrusewiczi) did not vary, or varied only slightly from year to year. The majority of measures of infracommunity structure [Brillouin's index of diversity, prevalence of all helminths combined, prevalence and abundance ofH. mixtum(the most prevalent helminth), mean species richness] did not differ significantly between years when other factors such as age, sex and seasonal variation had been taken into account. Some between-year variations were found (at the component community level, Simpson's index of diversity; at the infracommunity level, prevalence and abundance ofS. petrusewicziand abundance of all helminths combined), but even these were modest in comparison to seasonal and age differences, and were primarily attributable toS. petrusewiczi. We conclude that despite dynamic within-year fluctuations, helminth communities in bank voles in this region of Poland show relative stability across years. The sporadic occurrence of individual platyhelminths at low prevalence, makes little difference to the overall structure, which is largely maintained by the key roles played by the dominant intestinal nematodes of bank voles and the rarer species collectively.
Wavelet Compression of Three-Dimensional Time-Lapse Biological Image Data
Authors: Stefansson H. Narfi , Eliceiri Kevin W. , Thomas Charles F. , Ron Amos , DeVore Ron , Sharpley Robert , White John G.
Published: January 2005

The use of multifocal-plane, time-lapse recordings of living specimens has allowed investigators to visualize dynamic events both within ensembles of cells and individual cells. Recordings of such four-dimensional (4D) data from digital optical sectioning microscopy produce very large data sets. We describe a wavelet-based data compression algorithm that capitalizes on the inherent redunancies within multidimensional data to achieve higher compression levels than can be obtained from single images. The algorithm will permit remote users to roam through large 4D data sets using communication channels of modest bandwidth at high speed. This will allow animation to be used as a powerful aid to visualizing dynamic changes in three-dimensional structures.
Microstructure Analysis of a Carbon–Carbon Composite Using
Argon Ion Etching
Authors: Pfrang Andreas , Reznik Boris , Schimmel Thomas , Gerthsen Dagmar
Published: January 2005

The microstructure of carbon–carbon composites obtained by
chemical vapor infiltration of a carbon fiber felt was comparatively
studied by reflection light microscopy, transmission electron
microscopy (TEM), scanning electron microscopy (SEM), atomic force
microscopy (AFM), and laser scanning confocal microscopy (LSCM).
Ar+ ion etching was used to reveal and distinguish
structural units of the pyrolytic carbon matrix. Mechanically polished
samples, polished and subsequently ion etched samples, and fractured
samples were compared. The values of surface roughness and surface
height after polishing or after polishing and subsequent etching
determined by AFM and LSCM correlate well with the degree of texture of
the matrix layers obtained by polarized light microscopy and selected
area electron diffraction. The carbon matrix is composed of structural
units or “cells,” which contain a carbon fiber and a
sequence of several differently textured layers around each fiber.
Within high-textured layers columnar grains are well recognizable using
polarized reflection light microscopy and confocal microscopy. The size
of depressions within high-textured carbon layers found by AFM after
ion etching correlates well with the size of differently tilted domains
detected by both TEM and SEM.
Using a phenomenological perspective in radiation therapy research
Authors: Halkett G. K. B. , Scutter S. D. , Arbon P. , Borg M.
Published: January 2005

Research in radiation therapy is developing as radiation therapists recognise the need for improved evidence-based practice and patient care. However, many radiation therapists have a limited background in the area of research practices and the methodology that may be utilised to answer specific research questions. The purpose of this paper is to describe the development of a research question and the steps involved in determining an appropriate methodology that can be used to answer that research question. To demonstrate application of the approaches and methodologies that are described, an example research question that focuses on the experience of treatment decision-making for early stage breast cancer is considered and referred to throughout the paper. Initially, quantitative and qualitative research paradigms are considered and described to demonstrate the approaches that can be used, the type of data that can be collected and the results that can be analysed and utilised to answer the research question. As a phenomenological approach was found to be appropriate to investigate the question, this approach is explored in greater detail.
Lightning location relative to storm structure in a leading‐line, trailing‐stratiform mesoscale convective system
Authors: Carey Lawrence D. , Murphy Martin J. , McCormick Tracy L. , Demetriades Nicholas W. S.
Published: January 2005

Horizontal and line‐normal, vertical cross‐sections and composite images of Dallas‐Fort Worth Lightning Detection and Ranging (LDAR II) VHF radiation sources and radar reflectivity over a 30‐min period provide a unique perspective on lightning pathways within a leading‐line, trailing‐stratiform (LLTS) mesoscale convective system (MCS) on 16 June 2002. The overwhelming majority of VHF lightning sources occurred within the leading convective line in a bimodal pattern in the vertical. Assuming that VHF source density maxima were most likely associated with positive charge, then the LDAR II observations suggest that the gross charge structure of the convective region of the MCS was characterized by a tripole with net positive charge centered at 4.5 km AGL (3°C) and 9.5 km AGL (−35°C) and net negative charge centered roughly in the relative minimum of the VHF source density maximum at 7 km AGL (−17°C). A persistent lightning pathway and inferred positive charge zone sloped rearward (by 40–50 km) and downward (by 4–5 km) from the upper VHF source maximum in the convective line, through the transition zone, and into the radar bright band of the stratiform region. In the stratiform region, VHF lightning sources and inferred positive charge were concentrated in three layers centered at 4.5, 6, and 9 km AGL (2°C, −11°C, and −31°C, respectively), consistent with past electric field studies of symmetric LLTS MCSs. Positive cloud‐to‐ground lightning flashes in the stratiform region were initiated in the convective line and followed the slanting pathway from the top of convective cores to the stratiform precipitation, where they were horizontally extensive, layered, and highly branched. The sloping lightning pathway was identical to hypothetical trajectories taken by snow particles. These observations provide further support for the advection of charge on snow along the sloping pathway and the in situ generation of charge in the horizontal lightning layers as primary contributors to electrification and positive lightning production rearward of the convective line.
Using preformed nitrate to infer decadal changes in DOM remineralization in the subtropical North Pacific
Authors: Abell Jeffrey , Emerson Steve , Keil Richard G.
Published: January 2005

The preformed nitrate distribution throughout the subtropical North Pacific is characterized by a negative anomaly between 100 m and the 25.4 σθ surface. Its presence indicates that nitrogen remineralization in the upper thermocline deviates significantly from Redfield stoichiometry. It has been previously suggested that this feature is created during the degradation of nitrogen‐poor dissolved organic matter (DOM) (Emerson and Hayward, 1995). Here we present evidence from two transects in the eastern subtropical North Pacific that degradation of DOM with a high C:N ratio is quantitatively responsible for negative preformed nitrate. We develop a simple isopycnal mass balance to determine preformed nitrate using apparent oxygen utilization (AOU), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) data. These results agree well with the traditional preformed nitrate calculation and indicate that the intensity of the anomaly is proportional to the magnitude of DOM remineralization and its C:N remineralization ratio. An analysis of preformed nitrate distributions in the eastern subtropical North Pacific between 1980 and 1997 reveals a significant increase in the negative anomaly. While a portion of this change may be attributable to a reduction in ventilation of the gyre, the majority of the signal is due to an increase in the magnitude and/or C:N ratio of DOM remineralization. This conclusion supports recent hypotheses that DOM production and cycling may have increased in this region in the past 2 decades as a result of changes in the phytoplankton community structure.
Continuous geomagnetic field models for the past 7 millennia: 2. CALS7K
Authors: Korte M. , Constable C. G.
Published: January 2005

We present two continuous global geomagnetic field models for recent millennia: CALS3K.2, covering the past 3000 years, and CALS7K.2, covering 7000 years from 5000 BC to 1950 AD. The models were determined by regularized least squares inversion of archeomagnetic and paleomagnetic data using spherical harmonics in space and cubic B splines in time. They are derived from a greatly increased number of paleomagnetic directional data, compared to previous efforts, and for the first time a significant amount of archeointensity data is used in this kind of global model, allowing the determination of evolution of geomagnetic dipole strength. While data accuracy and dating uncertainties remain a limitation, reliable low‐resolution global models can be obtained. The results agree well with previous results from virtual axial dipole moment (VADM) studies from archeomagnetic intensity data apart from a systematic offset in strength. A comparison of model predictions with the previous 3000 year model, CALS3K.1, gives general agreement but also some significant differences particularly for the early epochs. The new models suggest that the prominent two northern hemisphere flux lobes are more stationary than CALS3K.1 implied, extending considerably the time span of stationary flux lobes observed in historical models. Between 5000 BC and 2000 BC there are time intervals of weak dipole moment where dipole power is exceeded by low‐degree nondipole power at the core‐mantle boundary. Model coefficients and evaluation code can be obtained from the EarthRef Digital Archive (ERDA) together with animations and snapshots plots for every 100 years at http://www.earthref.org. Detailed URLs for the different material are listed in Appendix A.
On the use of magnetic transient hysteresis in paleomagnetism for granulometry
Authors: Yu Yongjae , Tauxe Lisa
Published: January 2005

Parameters derived from magnetic hysteresis experiments have been used as granulometric indicators in paleomagnetism. In practice, discriminating the superparamagnetic (SP) fraction from the coarse grain magnetites in parameter ratio plots is often inconclusive. To overcome this ambiguity, transient hysteresis (TH) has been recently proposed. We have carried out micromagnetic simulations to provide a fundamental rationale for the use of TH for granulometry. We found that magnetic TH results from the difference of magnetization configuration between ascending and descending hysteresis loops as a result of self‐demagnetization. The descending branch has a tendency to keep a more uniform (e.g., flower‐like) configuration, while the ascending branch prefers a less uniform (e.g., vortex‐like) structure. According to our simulations, TH increases as the grain size increases and as the aspect ratio decreases. We also carried out TH measurements for well‐defined synthetic and natural samples. It is notable that TH from the simulation for samples with aspect ratio q = 1.5 agrees well with the experimental observations for annealed magnetites of smaller sizes. In general, small TH is a clear indication for the absence of complex magnetized structures. Adding TH analysis to the hysteresis loop measurements requires a minor effort yet provides strong constraint on grain size.
A new approach for 3D cloud‐resolving simulations of large‐scale atmospheric circulation
Authors: Kuang Zhiming , Blossey Peter N. , Bretherton Christopher S.
Published: January 2005

We present a computationally efficient new method for simulating the interactions of large‐scale atmospheric circulations with deep convection in a 3D cloud‐resolving model. This is accomplished by reducing the scale difference between the large‐scale and convective circulations. Our method, Diabatic Acceleration and REscaling (DARE), consists of accelerating all diabatic processes, reducing the planetary radius and increasing its rotation rate. A second useful interpretation of this rescaling, Reduced Acceleration in the VErtical (RAVE) is also presented briefly. The DARE/RAVE approach is expected to be useful for a wide range of problems involving interactions between large‐scale circulation, deep convection, and associated cloud and radiation processes, whose investigation has long been plagued by deficiencies in cumulus/cloud parameterizations. Initial results from a near‐global scale equatorial β‐plane simulation using the DARE approach are briefly presented.
Cluster electron observations of the separatrix layer during traveling compression regions
Authors: Owen C. J. , Slavin J. A. , Fazakerley A. N. , Dunlop M. W. , Balogh A.
Published: February 2005

We present Cluster 4‐point observations of electrons during traveling compression regions (TCRs) on 19 September 2001. The electron and ∣B∣ signatures vary with distance from the plasma sheet, confirming that transient plasma sheet bulges propagate past Cluster. TCRs with ∣B∣ increases have either no electron signature, or unidirectional ∼1 keV electrons at the plasma sheet edge. However, spacecraft initially near the plasma sheet edge are engulfed within the bulge and observe a diamagnetic reduction in ∣B∣. In cases where the underlying plasma sheet bulge moves earthward, electrons at the plasma sheet edge stream tailward. We suggest this represents either a remote observation of electrons closing the Hall current system in an ion diffusion region located farther tailward, or the outflow jets along the separatrix formed by a second neutral line located farther earthward of the spacecraft. The latter case implies the simultaneous action of multiple X‐lines in the near‐Earth tail.
Three decades of Martian surface changes
Authors: Geissler Paul E.
Published: February 2005

The surface of Mars has changed dramatically during the three decades spanned by spacecraft exploration. Comparisons of Mars Global Surveyor images with Viking and Mariner 9 pictures suggest that more than one third of Mars' surface area has brightened or darkened by at least 10%. Such albedo changes could produce significant effects on solar heating and the global circulation of winds across the planet. All of the major changes took place in areas of moderate to high thermal inertia and rock abundance, consistent with burial of rocky surfaces by thin dust layers deposited during dust storms and subsequent exposure of the rocky surfaces by aeolian erosion. Several distinct mechanisms contribute to aeolian erosion on Mars. Prevailing winds dominate erosion at low latitudes, producing diffuse albedo boundaries and elongated wind streaks generally oriented in the direction of southern summer winds. Dust devils darken the mid to high latitudes from 45 to 70 degrees during the summer seasons, forming irregular albedo patterns consisting of dark linear tracks. Dust storms produce regional albedo variations with distinct but irregular margins. Dark sand dunes in southern high latitudes appear to be associated with regional darkening that displays diffuse albedo boundaries. No surface changes were observed to repeat regularly on an annual basis, but many of the changes took place in areas that alternate episodically between high‐ and low‐albedo states as thin mantles of dust are deposited and later stripped off. Hence the face of Mars remains recognizable after a century of telescopic observations, in spite of the enormous extent of alteration that has taken place during the era of spacecraft exploration.
Neuronal Nitric Oxide Synthase and Ischemia-Induced Neurogenesis
Authors: Sun Yunjuan , Jin Kunlin , Childs Jocelyn T , Xie Lin , Mao Xiao Ou , Greenberg David A
Published: February 2005

Nitric oxide (NO) influences infarct size after focal cerebral ischemia and also regulates neurogenesis in the adult brain. These observations suggest that therapeutic approaches to stroke that target NO signaling may provide neuroprotection and also enhance brain repair through cell replacement. However, ischemic injury and neurogenesis are both affected differently depending on which isoform of NO synthase is the source of NO. In addition, ischemia itself stimulates neurogenesis, and ischemia-induced neurogenesis may be regulated differently than neurogenesis in nonischemic brain. To determine how neuronal NO synthase affects ischemia-induced neurogenesis, transient focal cerebral ischemia was produced in wild-type mice and in knockout mice lacking neuronal NO synthase, and BrdU incorporation and doublecortin immunoreactivity were measured in the principal neuroproliferative regions of the adult brain. Knockout of neuronal NO synthase reduced infarct size and increased both basal and ischemia-induced neurogenesis, suggesting that NO from this source is an inhibitory regulator of neurogenesis in the ischemic brain. 7-Nitroindazole, an NO synthase inhibitor that preferentially affects the neuronal isoform, also increased neurogenesis in rats when administered by the intracerebroventricular route. Selective inhibition of neuronal NO synthase may have the potential to both reduce infarct size and enhance neurogenesis in stroke.
Effects of Combined Oral Conjugated Estrogens and Medroxyprogesterone Acetate on Brain Infarction Size after Experimental Stroke in Rat
Authors: Littleton-Kearney Marguerite T , Klaus Judy A , Hurn Patricia D
Published: February 2005

The reason that estrogen is strongly protective in various estrogen-deficient animal models while seemingly detrimental in postmenopausal women remains unclear. It hypothesized that prolonged oral medroxyprogesterone (MPA) plus oral conjugated equine estrogens (CEE) diminishes estrogen ability to reduce stroke damage in the rodent stroke model. To test the hypothesis, we fed ovariectomized rats CEE or MPA, or a combination of CEE and MPA (CEP), before inducing 120 min of reversible focal stroke, using the intraluminal filament model. After 22 h reperfusion, the brains were harvested and infarction volumes were quantified. Treatment with CEE alone or with CEP reduced cortical infarction volume. However, CEP failed to provide ischemic protection in subcortical regions. It was concluded that CEE alone, or with CEP, is neuroprotective in the cortex, but interactive effects between the hormones may counteract CEE beneficial effects in subcortical brain regions.
Longitudinal Diffusion Changes in Cerebral Hemispheres after MCA Infarcts
Authors: Buffon Frédérique , Molko Nicolas , Hervé Dominique , Porcher Raphaël , Denghien Isabelle , Pappata Sabina , Le Bihan Denis , Bousser Marie-Germaine , Chabriat Hugues
Published: February 2005

Diffusion tensor imaging can be used in vivo to assess the longitudinal and regional microstructural changes occurring after middle cerebral artery (MCA) infarcts in humans. Nine patients were investigated 1 week (D7), 1 (M1), 3 (M3), and 6 months (M6) after the occurrence of an isolated MCA infarction. First, an overall analysis was performed using histograms of mean diffusivity (MD) and fractional anisotropy (FA) in each hemisphere. Thereafter, the regional pattern of diffusion changes was investigated voxel by voxel with statistical parametric mapping 99. In the hemisphere ipsilateral to the infarction, histogram analysis revealed a significant decrease in FA between D7 and M6 associated with a progressive increase in MD from D7 to M3. Remote from the MCA territory, the voxel by voxel analyses detected a significant increase in MD within the thalamus at M3 and M6 and a reduction in FA along the pyramidal tract at M6. In the contralateral hemisphere, between D7 and M6, a significant hemispheric atrophy was observed in association with a global reduction in anisotropy, in the absence of distinctive regional diffusion changes. These results suggest that micro- and macrostructural tissue modifications can be detected with diffusion tensor imaging in regions remote from the ischemic area in both hemispheres.
Modulation of Astrocytic Activation by Arundic Acid (ONO-2506) Mitigates Detrimental Effects of the Apolipoprotein E4 Isoform after Permanent Focal Ischemia in Apolipoprotein E Knock-in Mice
Authors: Mori Takashi , Town Terrence , Tan Jun , Tateishi Narito , Asano Takao
Published: February 2005

Using homozygous human apolipoprotein E2 (apoE2) (2/2)-, apoE3 (3/3)-, or apoE4 (4/4)-knock-in (KI) mice, we have shown that delayed infarct expansion and reactive astrocytosis after permanent middle cerebral artery occlusion (pMCAO) were markedly exacerbated in 4/4-KI mice as compared with 2/2- or 3/3-KI mice. Here, we probed the putative causal relationship between enhanced astrocytic activation and exacerbation of brain damage in 4/4-KI mice using arundic acid (ONO-2506, Ono Pharmaceutical Co. Ltd), which is known to oppose astrocytic activation through its inhibitory action on S100B synthesis. In all of the KI mice, administration of arundic acid (10 mg/kg day, intraperitoneal, started immediately after pMCAO) induced significant amelioration of brain damage at 5 days after pMCAO in terms of infarct volumes (results expressed as the mean infarct volume (mm3) ±1s.d. in 2/2-, 3/3-, or 4/4-KI mice in the vehicle groups: 16±2, 15±2, or 22±2; in the arundic acid groups: 11±2 ( P<0.001), 11±2 ( P<0.001), or 12±2 ( P<0.001), as compared with the vehicle groups), neurologic deficits, and S100/glial fibrillary acidic protein burden in the peri-infarct area. The beneficial effects of arundic acid were most pronounced in 4/4-KI mice, wherein delayed infarct expansion together with deterioration of neurologic deficits was almost completely mitigated. The above results support the notion that the apoE4 isoform exacerbates brain damage during the subacute phase of pMCAO through augmentation of astrocytic activation. Thus, pharmacological modulation of astrocytic activation may confer a novel therapeutic strategy for ischemic brain damage, particularly in APOE ɛ4 carriers.
GLC analysis of Indian rapeseed-mustard to study the variability of fatty acid composition
Authors: Kaushik N. , Agnihotri A.
Published: January 2005

Rapeseed-mustard is one of the most economically important oilseed crops in India. Speciality oils having high amounts of a specific fatty acid are of immense importance for both nutritional and industrial purposes. Oil high in oleic acid has demand in commercial food-service applications due to a long shelf-life and cholesterol-reducing properties. Both linoleic and linolenic acids are essential fatty acids; however, less than 3% linolenic acid is preferred for oil stability. High erucic acid content is beneficial for the polymer industry, whereas low erucic acid is recommended for food purposes. Therefore, it is important to undertake systematic characterization of the available gene pool for its variable fatty acid profile to be utilized for specific purposes. In the present study the Indian rapeseed-mustard germplasm and some newly developed low-erucic-acid strains were analysed by GLC to study the fatty acid composition in these lines. The GLC analysis revealed that the rapeseed-mustard varieties being commonly grown in India are characterized by high erucic acid content (30–51%) in the oil with low levels of oleic acid (13–23%). However, from among the recently developed low-erucic-acid strains, several lines were identified with comparatively high oleic acid (60–70%), moderate to high linoleic acid (13–40%) and low linolenic acid (< 10%) contents. Work is in progress at TERI (New Delhi, India) to utilize these lines for development of strains with particular fatty acid compositions for specific purposes.
Effects of manipulating expression of acetyl-CoA carboxylase I in Brassica napus L. embryos
Authors: Sellwood C. , Slabas A. R. , Rawsthorne S.
Published: January 2005

Acetyl-CoA carboxylase I (ACCase I) in developing oilseed rape embryos is predominantly cystosolic, based upon measurement of its propionyl-CoA carboxylase activity. Reduction of ACCase I by antisense expression reduces seed lipid content and affects carbohydrate metabolism.
Biochemical characterization of 3-ketoacyl-acyl carrier protein synthase II from leek epidermis
Authors: Domergue F. , Post-Beittenmiller D.
Published: January 2005

In order to define its possible involvement in production of stearic acid for wax biosynthesis, the presence of 3-ketoacyl acyl synthase II (KAS II) activity was investigated in different tissues of leek (Allium porrum L.) leaves. KAS II activity was identified in sheath and lamina epidermis, as well as in underlying parenchyma. In all three tissues, activity was inhibited by 50% on addition of l00μM cerulenin, and showed an absolute requirement for acyl-ACP substrates. More interestingly, the different tissues did not display similar KAS II substrate specificities. Parenchyma and lamina epidermis tissues presented typical KAS II activities, since C18 0-ACP was the exclusive product. In contrast, in sheath epidermis, KAS II activity resulted in the synthesis of acyl-chains up to 22 carbons in length, suggesting the existence in this tissue of an unusual KAS II. This activity was sufficient to elongate all of the palmitoyl-ACP produced by the fatty acid synthase, suggesting that C18 0 is the substrate of the microsomal elongases involved in wax biosynthesis.
The molecular basis of the high linoleic acid content in Petunia seed oil: analysis of a seed-specific linoleic acid mutant
Authors: Verwoert I. , Meller-Harel Y. , van der Linden K. , Verbree B. , Koes R. , Stuitje A.
Published: January 2005

From a random transposon mutagenesis experiment, using Petunia line W138, a seed-specific linoleic acid mutant was isolated. The tagged gene was cloned and identified as a microsomal Δ12 desaturase. Expression of the gene, however, was constitutive and not, as might have been expected, seed-specific. Moreover, self-fertilized homozygous mutants still contain 40% 18:2 in the seed lipid fraction. This suggests that at least two (seedspecific) Δ12 desaturase genes are responsible for the high linoleic acid content in Petunia seed oil. Five members of the microsomal Δ12 desaturase gene family have been identified and isolated. Data are presented on the molecular characterization and tissue-specific expression of these genes, which suggest that, in Petunia the flux through the prokaryotic and eukaryotic pathways of lipid synthesis might be different from the situation found in Arabidopsis.
Enzymic activities and gene expression of enzymes of the acyl-CoA elongase during rapeseed development
Authors: Puyaubert J. , Garbay B. , Dieryck W. , Costaglioli P. , Roscoe T. , Cassagne C. , Lessire R.
Published: January 2005

Enzymic activities and gene expression of oleoylCoA elongase were studied during seed development using two different rapeseed cultivars, high-erucic-acid rapeseed (HEAR) and low-erucic-acid rapeseed (LEAR). The overall elongase activities were maximal in HEAR between the fourth and eighth weeks after pollination (WAP) and absent in LEAR. The 3-ketoacyl-CoA synthase (condensing enzyme, CE) mRNA levels and the developmental profiles in the two cultivars were different since maximal expression levels were detected in HEAR and LEAR at WAP 4 and WAP 6, respectively. Anti-CE antibodies revealed two proteins of 60 and 67 kDa in both cultivars and an additional reacting protein of 57 kDa in HEAR.
Polyunsaturated fatty acid-specific elongation enzymes
Authors: Das T. , Thurmond J. M. , Bobik E. , Leonard A. E. , Parker-Barnes J. M. , Huang Y.-S. , Mukerji P.
Published: January 2005

We have isolated a novel gene (GLELO) from Mortierella alpina and its homologue (CEELO1) from Caenorhabditis elegans and demonstrate the involvement of their encoded proteins in the elongation of C18 polyunsaturated fatty acids.
Carbon supply for storage-product synthesis in developing seeds of oilseed rape
Authors: Hill L. M. , Rawsthorne S.
Published: January 2005

The aim of this work was to find out how the sugars in the endosperm of oilseed rape contribute to the flux of oil synthesis. While the hexose content of the liquid endosperm decreased during development the sucrose content increased. It is important to understand the relative rates of use of the endosperm sugars for two reasons. Firstly we need to know which sugars are used, and at what stages in development, in order to understand the roles of enzymes involved in their metabolism. Secondly, changes in sugar concentration have been implicated in the regulation of expression of genes determining storage-product synthesis [see Weber, Borisjuk and Wobus (1997) Trends Plant Sci. 2, 169–174, for review]. The rate of consumption of sugar is one factor governing its concentration. We present data showing both the concentration-dependence of conversion of sugar to oil, and the in vivo concentrations of sugars; we relate these data sets to each other and discuss the effects of the intracellular pool of sucrose. Glucose, fructose and sucrose are all substrates for oil synthesis, but the rates of their use (particularly sucrose) are underestimated because of dilution by sucrose from the intracellular pool.
Towards the cloning of GLY1
Authors: Miquel M.
Published: January 2005

The Arabidopsis mutants designated gly1 exhibit a reduced carbon flux through the prokaryotic pathway that is compensated for by an increased carbon flux through the eukaryotic pathway. Biochemical approaches reveal that the gly1 phenotype cannot be explained by a deficiency in the enzymes of the prokaryotic pathway. The chemical complementation of the mutant phenotype by exogenous glycerol treatment of gly1 plants suggests a lesion affecting the glycerol 3-phosphate supply within the chloroplast. As an alternative to the biochemical study of the gly1 mutants we set out to map the GLY1 locus. The gly1 mutant being an EMS (ethyl methane sulphonate) mutant, we used a strategy based on the polymorphism existing between Arabidopsis ecotypes, here Columbia (gly1 background) and Landsberg erecta. We mapped gly1 on chromosome II. During the process of chromosome walking, the complete sequence of chromosome II was released, allowing us to make assumptions on candidate genes based on map location. We are currently sequencing the putative genes.
Plant glycerol-3-phosphate-l-acyltransferase (GPAT): structure selectivity studies
Authors: Slabas A. R. , Simon W. R. , Schierer T. , Kroon J. , Fawcett T. , Hayman M. , Gilroy J. , Nishida I. , Murata N. , Rafferty J. , Turnbull A. , Rice D.
Published: January 2005

Squash glycerol-3-phospate-1-acyltransferase has been crystallized and the structure of the enzyme determined, at 1.9-Å resolution, using multiple isomorphous replacement of the wild type and a series of individual cysteine mutants. Competitive in vitro substrate selectivity assays have been established that differentiate between selective and non-selective forms of the enzyme. Particular care was taken to use near-physiological concentrations of both substrates. Clear substrate selectivity can be demonstrated with the natural substrate acyl-acyl carrier protein but not with the substrate analogue acyl-CoA. The use of site-directed mutagenesis, coupled to three-dimensional structural determinations, should provide a rational basis for elucidating structural components important in determining the substrate selectivity of this enzyme.
Differential expression of diacylglycerol acyltransferase (DGAT) genes in olive tissues
Authors: Giannoulia K. , Haralampidis K. , Poghosyan Z. , Murphy D. J. , Hatzopoulos P.
Published: January 2005

Fatty acids are accumulated in triacylglycerols (TAGs), in specialized organelles of seeds named oil bodies. The major site of TAG accumulation is detected in developing seed and mesocarp of certain species. We have isolated two cDNAs encoding DGAT enzymes from olives. The deduced polypeptides differ by 26 amino acids in size. However, they have high homology and almost identical hydropathy profiles. The DGAT gene is expressed in all tissues that synthesize TAGs. However, higher levels of DGAT transcripts have been detected in seed tissues of developing olive drupe. DGAT expression and mRNA accumulation in drupe tissues is developmentally regulated. Each DGAT transcript shows a distinct profile of accumulation. The existence of two different DGAT transcripts might reflect two different enzymes with discrete function and/or localization.
Does triacylglycerol biosynthesis require diacylglycerol acyltransferase (DAGAT)?
Authors: Fraser T. , Waters A. , Chatrattanakunchai S. , Stobart K.
Published: January 2005

Microsomal membrane preparations from the developing seeds of sunflower (Helianthus annuus L.) catalyse the conversion of sn-glycerol-3-phosphate and acyl-CoA to triacylglycerol via phosphatidic acid and diacylglycerol. The formation of diacylglycerol from phosphatidic acid was Mg2+ dependent and in the presence of EDTA phosphatidic acid accumulated. This property was used to generate large quantities of endogenous radioactive phosphatidic acid in the membranes. On addition of Mg2+ the phosphatidic acid was used in triacylglycerol formation. Acyl-CoA had little effect on the label which accumulated in triacylglycerol from phosphatidic acid. Diacylglycerol acyltransferase, therefore, may not play a major role in oil formation as originally envisaged and other enzymes, including diacylglycerol: diacylglycerol transacylase [Stobart, Mancha, Lenman, Dahlqvist and Stymne (1997) Planta 203, 58–66] may have important biosynthetic functions.
Solubilization of the plastidial lysophosphatidyfcholine acyltransferase from Allium porrum leaves: towards plants devoid of eukaryotic plastid lipids?
Authors: Akermoun M. , Testet E. , Cassagne C. , Bessoule J.-J.
Published: January 2005

To analyse the involvement of the plastidial lysophosphatidylcholine (lyso-PC) acyltransferase in the import of the extraplastidial lipid precursors required for eukaryotic plastid lipid synthesis, we plan to obtain transgenic plants. Since no sequence of lyso-PC acyltransferase is known, the purification of this enzyme has been undertaken to establish its sequence. First we determined the conditions allowing the solubilization of this membrane-bound enzyme. It is shown that by using CHAPS as a detergent, a lyso-PC acyltransferase activity is associated with the solubilized proteins.
Can digalactosyldiacylglycerol substitute for phosphatidylcholine upon phosphate deprivation in leaves and roots of Arabidopsis?
Authors: Härtel H. , Benning C.
Published: January 2005

To explore the role of digalactosyldiacylglycerol (DGDG) in plants the dgd1 mutant of Arabidopsis thaliana was grown in the presence and absence of inorganic phosphate. Phosphate deficiency in the dgd1 mutant causes a strong decrease in all phospholipids accompanied by an increase in DGDG and sulpholipid. Moreover, a significant DGDG accumulation was found in roots upon phosphate deprivation as well. Our data indicate that DGDG accumulation upon phosphate deprivation is due to the activation of a specific eukaryotic dgd1-independent biosynthetic pathway. We propose that DGDG may substitute for phosphatidylcholine upon phosphate deprivation.
Characterization of sphingolipid long-chain base kinase in Arabidopsis thaliana
Authors: Nishiura H. , Tamura K. , Morimoto Y. , Imai H.
Published: January 2005

Sphingolipid long-chain base (LCB) kinase catalyses the phosphorylation of sphingolipid LCB to form LCB 1-phosphate. Based on sequence identity to a murine sphingosine kinase (murine SPHK1a), we isolated and characterized a LCB kinase-like cDNA in Arabidopsis thaliana. The deduced amino acid sequence of the homologous cDNA shows several regions that are highly conserved in LCB kinases from mouse, yeast, human and Caenorhabditis elegans. These regions are not similar to those of other known kinase families. For a functional identification, the homologous cDNA from A. thaliana was expressed in Escherichia coli and LCB kinase activity was measured. The recombinant AtLcbk1 protein was found to utilize ATP and sphinganine. These results indicate the first identification of a gene coding for a LCB kinase in plants.