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High Capacity (high + capacity)
Selected AbstractsSilicon Inverse-Opal-Based Macroporous Materials as Negative Electrodes for Lithium Ion BatteriesADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Alexei Esmanski Abstract Several types of silicon-based inverse-opal films are synthesized, characterized by a range of experimental techniques, and studied in terms of electrochemical performance. Amorphous silicon inverse opals are fabricated via chemical vapor deposition. Galvanostatic cycling demonstrates that these materials possess high capacities and reasonable capacity retentions. Amorphous silicon inverse opals perform unsatisfactorily at high rates due to the low conductivity of silicon. The conductivity of silicon inverse opals can be improved by their crystallization. Nanocrystalline silicon inverse opals demonstrate much better rate capabilities but the capacities fade to zero after several cycles. Silicon,carbon composite inverse-opal materials are synthesized by depositing a thin layer of carbon via pyrolysis of a sucrose-based precursor onto the silicon inverse opals. The amount of carbon deposited proves to be insufficient to stabilize the structures and silicon,carbon composites demonstrate unsatisfactory electrochemical behavior. Carbon inverse opals are coated with amorphous silicon producing another type of macroporous composite. These electrodes demonstrate significant improvement both in capacity retentions and in rate capabilities. The inner carbon matrix not only increases the material conductivity but also results in lower silicon pulverization during cycling. [source] Low internalised restraint predicts criminal recidivism in young female prisonersCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 5 2009Ellen Kjelsberg Background,The Weinberger Adjustment Inventory (WAI) measures social-emotional adjustment along two dimensions: distress and restraint. Four types of adjustment according to this measure have been shown to correlate with criminal recidivism among young male prisoners: reactive (high distress, low restraint), suppressor (high distress, high restraint), non-reactive (low distress, low restraint) and repressor (low distress, high restraint). Aim,To evaluate the predictive potential of the WAI among young female prisoners. Methods,Women under 30 years old, consecutively admitted to one of three Norwegian prisons, were asked to complete the WAI. Most of those eligible (102, 94%) did so. Re-conviction data were collected from the National Crime Register 38 months (SD = 9.0) after release. Results,The overall re-conviction rate was 38%. Rates differed according to the four WAI types: 53% in the non-reactive, 50% in the reactive, 22% in the suppressor and 11% in the repressor group (p = 0.006). Kaplan,Meier analyses showed that group differences were explained by the WAI restraint dimension (p = 0.008). Differences on the distress dimension did not influence re-conviction. Cox regression analysis (adjusting for age at first court conviction and prior offences) found that women with low restraint scores were almost three times as likely to re-offend as women with high restraint scores. Conclusion,The WAI appears to be an effective tool for identifying women who are particularly vulnerable to re-offending. Evidence of high capacity for restraint is protective, regardless of distress levels and even after adjusting for the effect of other criminologically important factors. The findings are suggestive that there may be value in individualising ,treatment' or rehabilitation programmes for prisoners. Copyright © 2009 John Wiley & Sons, Ltd. [source] Head regeneration in HydraDEVELOPMENTAL DYNAMICS, Issue 2 2003Hans R. Bode Abstract Hydra, a primitive metazoan, has a simple structure consisting of a head, body column, and foot aligned along a single oral,aboral axis. The body column has a high capacity for regeneration of both the head and foot. Because of the tissue dynamics that take place in adult Hydra, the processes governing axial patterning are continuously active to maintain the form of the animal. Regeneration in hydra is morphallactic and closely related to these axial patterning processes. As might be expected, analysis at the molecular level indicates that the same set of genes are involved in head regeneration and the maintenance of the head in the context of the tissue dynamics of the adult. The genes analyzed so far play roles in axial patterning processes in bilaterians. Developmental Dynamics 226:225,236, 2003. © 2003 Wiley-Liss, Inc. [source] The role of food and colony size in sexual offspring production in a social insect: an experimentECOLOGICAL ENTOMOLOGY, Issue 1 2007JOUNI SORVARI Abstract 1.,Large colonies of ants are known to have a higher propensity for sexual offspring production, probably owing to their high capacity to exploit food resources. 2.,The effects of food supplementation on the propensity for sexual offspring production, and whether it is linked with colony size, were investigated in an environment with poor resources (clear-cut areas). 3.,Large colony size was associated with a higher propensity for sexual offspring production in food-supplemented colonies, whereas in non-supplemented control colonies an association with colony size was not found. 4.,The results demonstrate that large colonies seem to have a higher capacity to exploit supplemented food. In addition, the production of sexual offspring was apparently limited by food availability in clear-cuts, especially for large colonies. [source] Role of ethylenediaminetetraacetic acid on lead uptake and translocation by tumbleweed (Salsola kali L.)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2007Guadalupe de la Rosa Abstract Tumbleweed plants (Salsola kali L.) grown in agar and liquid media demonstrated a high capacity to accumulate Pb in their different parts without affecting biomass. Whereas shoot elongation and biomass were not significantly affected by high tissue concentrations of Pb, root growth was significantly affected relative to controls. Roots, stems, and leaves demonstrated Pb concentrations of 31,000, 5,500, and 2,100 mg/kg dry weight, respectively, when plants were grown in the agar medium containing 80 mg Pb/L. Application of ethylenediaminetetraacetic acid (EDTA) to Pb-contaminated media dramatically reduced the total acquisition of Pb from both types of media. However, EDTA significantly increased the translocation of Pb from roots to the aerial parts, as evidenced by a multifold increase (23- and 155-fold for agar and liquid media, respectively) in the translocation concentration factor. The concentration of the antioxidant thiol compounds significantly increased (p < 0.05) in plants grown with uncomplexed Pb treatments relative to control plants. Scanning-electron microscopy and electron dispersive x-ray spectroscopic evaluation of leaf samples demonstrated an interesting pattern of Pb translocation in the presence or absence of EDTA. Large Pb crystals were found across the leaf tissues (palisade, spongy parenchyma, and conducting tissues) in the absence of EDTA. Lead nanoparticles also were seen when plants were grown in Pb-EDTA solution. Ultramicroscopic features of tumbleweed provide clear evidence for the unrestricted conduction of Pb from the root to the aerial parts, and this property makes the plant a good candidate for phytoremediation. [source] A Novel Cathode Material with a Concentration-Gradient for High-Energy and Safe Lithium-Ion BatteriesADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Yang-Kook Sun Abstract A high-energy functional cathode material with an average composition of Li[Ni0.72Co0.18Mn0.10]O2, mainly comprising a core material Li[Ni0.8Co0.2]O2 encapsulated completely within a stable manganese-rich concentration-gradient shell is successfully synthesized by a co-precipitation process. The Li[Ni0.72Co0.18Mn0.10]O2 with a concentration-gradient shell has a shell thickness of about 1,µm and an outer shell composition rich in manganese, Li[Ni0.55Co0.15Mn0.30]O2. The core material can deliver a very high capacity of over 200,mA h g,1, while the manganese-rich concentration-gradient shell improves the cycling and thermal stability of the material. These improvements are caused by a gradual and continuous increase of the stable tetravalent Mn in the concentration-gradient shell layer. The electrochemical and thermal properties of this cathode material are found to be far superior to those of the core Li[Ni0.8Co0.2]O2 material alone. Electron microscopy also reveals that the original crystal structure of this material remains intact after cycling. [source] Lithium Batteries: (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Mater. The cover picture is a scanning electron microscopy image of uncoated and 0.5 wt% TiO2 nanoparticle-coated LiCoO2 cathode particles, which are investigated in the research and development of lithium rechargeable batteries that require high power, high capacity, and high safety. TiO2 nanoparticles with sizes below 100 nm are mixed with LiCoO2 particles with an average particle size of 20,µm in a rotating jar at 200 rpm. The mixed particles are then fired at 1000°C for 5 h in air. The uncoated and 0.5 wt% coated particles show similar surface morphologies to each other. Despite the use of dry coating, Ti atoms appear to distribute uniformly throughout the particles. The advantage of this method is a simplified and cost-effective coating procedure, and these electrochemical enhancements can lead to versatile potential applications of the batteries, and provide breakthroughs in the power supply of mobile electronics. [source] Reversible and High-Capacity Nanostructured Electrode Materials for Li-Ion BatteriesADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Min Gyu Kim Abstract Reversible nanostructured electrode materials are at the center of research relating to rechargeable lithium batteries, which require high power, high capacity, and high safety. The higher capacities and higher rate capabilities for the nanostructured electrode materials than for the bulk counterparts can be attributed to the higher surface area, which reduces the overpotential and allows faster reaction kinetics at the electrode surface. These electrochemical enhancements can lead to versatile potential applications of the batteries and can provide breakthroughs for the currently limited power suppliers of mobile electronics. This Feature Article describes recent research advances on nanostructured cathode and anode materials, such as metals, metal oxides, metal phosphides and LiCoO2, LiNi1,xMxO2 with zero-, one-, two-, and three-dimensional morphologies. [source] Serum lipids regulate dendritic cell CD1 expression and functionIMMUNOLOGY, Issue 3 2008David S. Leslie Summary Dendritic cells (DCs) are highly potent antigen-presenting cells (APCs) and play a vital role in stimulating naďve T cells. Treatment of human blood monocytes with the cytokines granulocyte,macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-4 stimulates them to develop into immature dendritic cells (iDCs) in vitro. DCs generated by this pathway have a high capacity to prime and activate resting T cells and prominently express CD1 antigen-presenting molecules on the cell surface. The presence of human serum during the differentiation of iDCs from monocytes inhibits the expression of CD1a, CD1b and CD1c, but not CD1d. Correspondingly, T cells that are restricted by CD1c showed poor responses to DCs that were generated in the presence of human serum, while the responses of CD1d-restricted T cells were enhanced. We chemically fractionated human serum to isolate the bioactive factors that modulate surface expression of CD1 proteins during monocyte to DC differentiation. The human serum components that affected CD1 expression partitioned with polar organic soluble fractions. Lysophosphatidic acid and cardiolipin were identified as lipids present in normal human serum that potently modulate CD1 expression. Control of CD1 expression was mediated at the level of gene transcription and correlated with activation of the peroxisome proliferator-activated receptor (PPAR) nuclear hormone receptors. These findings indicate that the ability of human DCs to present lipid antigens to T cells through expression of CD1 molecules is sensitively regulated by lysophosphatidic acid and cardiolipin in serum, which are ligands that can activate PPAR transcription factors. [source] Capacity analysis for underlaying CDMA microcell/macrocell systemsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2001Jen-Kung Chung Abstract The CDMA system can provide more capacity than the conventional AMPS system and the hierarchical layer of cells is required for system design in the future. However, the problem is whether the same RF channels used in a CDMA underlaying macrocell/microcell structure also obtain high capacity as in the homogeneous structure. This paper investigates the interference of uplink and downlink from both the microcell and macrocell in a hierarchical structure. Downlink power control is also considered. The results show that the capacity of microcell in a hierarchical structure is 23 per cent less than in homogeneous cells. The capacity of macrocell in a hierarchical structure decreases dramatically in proportion to the number of microcells. The capacities of the microcell and macrocell are limited in downlink, and uplink, respectively. In addition, more efforts for microcell should be made, such as more power is transmitted by microcell basestation if the same RF channel is used in a hierarchical structure. The results suggest that different RF channels are used in a two-tier cellular environment. Copyright © 2001 John Wiley & Sons, Ltd. [source] Improved Hydrogen Storage Properties of Ti-Doped Sodium Alanate Using Titanium Nanoparticles as Doping Agents,ADVANCED MATERIALS, Issue 12 2003B. Bogdanovi By using nanosized doping agents, the properties of Ti-catalyzed NaAlH4 storage systems are considerably improved. Hydrogenation,dehydrogenation cyclic testing shows that with nanosized TiN dopants, storage capacities of 5 wt.-% H2 could be achieved. Doping with nanosized Ti brought hydrogenation times close to those required for practical applications, combined with high capacity (4.5 wt.-% H2, see Figure). [source] Reliable multicast via satellite: a comparison survey and taxonomyINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 1 2001Martin W. Koyabe Abstract IP multicasting is an important service, which will be provided by the next generation Internet. A range of applications has emerged which take the advantage of multicast delivery. However, several factors currently hinder large-scale deployment of terrestrial multicast services. It is particularly difficult to support delivery to large groups of users. Satellites offer a natural way to extend the multicast service to reach this large number of users. They may offer high capacity (especially when using next generation satellite systems) and also eliminate the need for a large number of intermediate routing hops. There are important differences in the way multicast applications operate over satellite. This paper therefore reviews the key design paradigm and offers a critical comparison between different reliable multicast protocol techniques based on a taxonomy. The suitability of a set of the most common reliable multicast protocols is assessed within a satellite environment and conclusions are presented. Copyright © 2001 John Wiley & Sons, Ltd. [source] Adduct-forming tendencies of cationic triarylmethane dyes with proteins: Metabolic and toxicological implicationsJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 5 2004Özden Tacal Abstract The formation of colorless adducts by four cationic triarylmethane dyes (TAM+s), methyl green (MeG+), malachite green (MG+), pararosaniline (PR+), and crystal violet (CV+) was studied spectrophotometrically at 25°C, in 50 mM 3-(N-morpholino)propanesulfonic acid (MOPS) buffer (pH 8), by monitoring the loss in TAM+ color in the absence and presence of human serum proteins as potential addends. Unfractionated serum caused a rapid bleaching of MeG+ and MG+, while PR+ and CV+ were unaffected. Sephacryl S200 HR chromatographic screening of the serum revealed two composite peaks of MeG+ -bleaching activity. The major peak (Mr range, 40,000,130,000) overlapped with and extended on either side of the albumin peak. The minor peak corresponding to ca. 10% of the total MeG+ -bleaching capacity had Mr > 230,000. MG+ -bleaching activity dominated the entire chromatographic profile and implicated a multitude of minority proteins with a high capacity to form colorless MG adducts. It is concluded that highly electrophilic TAM+s such as MeG+ and MG+ must be quantitatively trapped in the form of dye,protein adducts in biological fluids and that the primary in vivo effects (e.g. toxicity) of such dyes most likely arise from ligand-type effects on multiple protein targets. Mechanisms that call for unmodified TAM+ structure (radical-mediated redox changes, DNA intercalation) may be more relevant to the in vivo impact of dyes such as PR+ and CV+ that have a lower tendency to form adducts. © 2004 Wiley Periodicals, Inc. J Biochem Mol Toxicol 18:253,256, 2004 Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20034 [source] The effect of superoxide dismutase deficiency on cadmium stressJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 1 2004Paula D. B. Adamis Abstract Saccharomyces cerevisiae mutant strains deficient in superoxide dismutase (Sod), an antioxidant enzyme, were used to analyze cadmium absorption and the oxidation produced by it. Cells lacking the cytosolic Sod1 removed twice as much cadmium as the control strain, while those deficient in the mitochondrial Sod2 exhibited poor metal absorption. Interestingly, the sod1 mutant did not become more oxidized after exposure to cadmium, as opposed to the control strain. We observed that the deficiency of Sod1 increases the expression of both Cup1 (a metallothionein) and Ycf1 (a vacuolar glutathione S-conjugate pump), proteins involved with protection against cadmium. Furthermore, when sod1 cells were exposed to cadmium, the ratio glutathione oxidized/glutathione reduced did not increase as expected. We propose that a high level of metallothionein expression would relieve glutathione under cadmium stress, while an increased level of Ycf1 expression would favor compartmentalization of this metal into the vacuole. Both conditions would reduce the level of glutathione-cadmium complex in cytosol, contributing to the high capacity of absorbing cadmium by the sod1 strain. Previous results showed that the glutathione-cadmium complex regulates cadmium uptake. These results indicate that, even indirectly, metallothionein also regulates cadmium transport. © 2004 Wiley Periodicals, Inc. J Biochem Mol Toxicol 18:12,17, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20000 [source] ANTIOXIDANT ACTIVITY AND TOTAL PHENOLIC CONTENTS IN PEEL AND PULP OF CHINESE JUJUBE (ZIZIPHUS JUJUBA MILL) FRUITSJOURNAL OF FOOD BIOCHEMISTRY, Issue 5 2009ZIPING XUE ABSTRACT Total phenolic contents in peel and pulp of the fruits of three Chinese jujube cultivars (Ziziphus jujuba cv. mayazao, Z. jujuba cv. dongzao and Z. jujuba cv. yuanzao) were determined. The antioxidant activities in peel and pulp of the jujube fruits were measured by different methods, including 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC). The total phenolic content in peel was five to six times higher than that in the pulp of all the three cultivars. The phenolics contents in the jujube were different with cultivars. The EC50 (Concentration of lyophilized samples needed to decrease the initial DPPH radical concentration by 50%), FRAP and TEAC values of the peel and pulp were remarkably correlated to their total phenolic contents (R = ,0.922, R = 0.985 and R = 0.997, respectively). The results indicated that the high capacity of antioxidant of Chinese jujube fruit could be attributed to the high phenolic contents in the fruit. PRACTICAL APPLICATIONS There was an expanding quest surrounding the use of antioxidant because they have the capacity to protect from the damage because of free radicals and reactive oxygen species. However, the safety of synthetic antioxidant was challenged. Much attention has been focused on the use of natural antioxidant. Interest in food phenolics had increased greatly because of their antioxidant and possible promoting-health role in human health. In this study, total phenolic contents and antioxidant capacities in vitro of Chinese jujube (Ziziphus jujuba Mill) peel and pulp were researched. The work would help to explore a natural antioxidant for possible application in food and dietary supplemental products for health promotion. [source] Genes, gene flow and adaptation of Diabrotica virgifera virgiferaAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2009Nicholas J. Miller Abstract 1,Diabrotica virgifera virgifera has emerged as a major pest of cultivated maize, due to a combination of its high capacity to inflict economic damage, adaptability to pest management techniques and invasiveness. 2,This review presents a survey of the current state of knowledge about the genetics of D. v. virgifera. In addition, the tools and resources currently available to Diabrotica geneticists are identified, as are areas where knowledge is lacking and research should be prioritized. 3,A substantial amount of information has been published concerning the molecular phylogenetic relationships of D. v. virgifera to other chrysomelids. 4,There is a growing literature focused on the population genetics and evolution of the species. Several adaptations to anthropogenic selection pressure have been studied, with resistance to synthetic insecticides providing some particularly well-characterized examples. 5,A notable deficiency is a lack of studies directed toward the formal genetics of D. v. virgifera. [source] Chromogranins as regulators of exocytosisJOURNAL OF NEUROCHEMISTRY, Issue 2 2010Ricardo Borges J. Neurochem. (2010) 114, 335,343. Abstract Chromogranins (Cgs) constitute the main protein component in the vesicular matrix of large dense core vesicles (LDCV). These acidic proteins have been implicated in several physiological processes such as vesicle sorting, the generation of bioactive peptides and the accumulation of soluble species inside LDCV. This latter feature of Cgs accounts for the ability of vesicles to concentrate catecholamines and Ca2+. Indeed, the low affinity and high capacity of Cgs to bind solutes at the low pH of the LDCV lumen seems to be behind the delay in the neurotransmitter exit towards the extracellular milieu after vesicle fusion. The availability of new mouse strains lacking Cgs in combination with the arrival of several techniques for the direct monitoring of exocytosis (like amperometry, patch-amperometry and intracellular electrochemistry), have helped advance our understanding of how these granins concentrate catecholamines and Ca2+ in LDCV, and how they influence the kinetics of exocytosis. In this review, we will discuss the roles of Cgs A and B in maintaining the intravesicular environment of secretory vesicles and in exocytosis, bringing together the most recent findings from adrenal chromaffin cells. [source] A Novel Approach to Magnetic Nanoadsorbents with High Binding Capacity for Bovine Serum AlbuminMACROMOLECULAR RAPID COMMUNICATIONS, Issue 3 2007Yabin Sun Abstract Magnetic nanoadsorbents using Fe3O4 nanoparticles as cores and poly(methyl acrylic acid) (PMAA) as ionic exchange groups were prepared through our novel approach. Two steps were involved in this approach: the first was to functionalize the magnetic nanoparticles (MNPs) with methacrylate double bonds via the combination of ligand exchange and condensation of methacryloxypropyltrimethoxysilane(MPS); the second was to graft PMAA chains onto the surface of MNPs through radical polymerization. The success of the various surface functionalization steps was ascertained using FTIR and XPS. The as-synthesized PMAA-coated MNPs were effective in binding bovine serum albumin (BSA) with a high capacity of 1,300 mg,·,g,1. [source] Effect of exogenous DNA on bovine sperm functionality using the sperm mediated gene transfer (SMGT) techniqueMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 8 2010Sebastian Canovas Sperm mediated gene transfer (SMGT) could provide the opportunity to carry out transgenesis on a mass scale using spermatozoa as vectors for exogenous DNA. However, the efficiency of sperm-mediated DNA transfer is still questionable, and the mode of transmission to the egg has not yet been well understood. Our aim was to investigate the capacity of bovine spermatozoa to carry exogenous DNA and its relationship to sperm functionality. We studied these parameters using flow cytometry to measure viability (necrosis and apoptosis) and capacitation status, computer-assisted semen analysis (CASA) to measure motility parameters and in vitro fertilization (IVF) to assess fertilizing capacity. Furthermore, we studied the effect of capacitation status on interaction with exogenous DNA, and the role of heparin supplementation in this process. Bull spermatozoa showed a high capacity to bind DNA quickly and reached a maximum after 30,min, with approximately half of the DNA-bound spermatozoa being viable. Incubation with exogenous DNA induced a decrease in sperm viability and motility and increased the proportion of apoptotic cells, but did not affect the cleavage rate in IVF assay. Heparin increased high-lipid disorder and the number of sperm with DNA bound (viable and dead). In conclusion, this study shows that live spermatozoa can bind exogenous DNA with a slight negative effect in some parameters of sperm function that in our opinion, would not drastically compromise fertility. Mol. Reprod. Dev. 77: 687,698, 2010. © 2010 Wiley-Liss, Inc. [source] The drug transporter MgMfs1 can modulate sensitivity of field strains of the fungal wheat pathogen Mycosphaerella graminicola to the strobilurin fungicide trifloxystrobinPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 7 2008Ramin Roohparvar Abstract BACKGROUND: The major facilitator superfamily (MFS) drug transporter MgMfs1 of the wheat pathogen Mycosphaerella graminicola (Fuckel) J Schroeter is a potent multidrug transporter with high capacity to transport strobilurin fungicides in vitro. The data presented in this paper indicate that, in addition to the predominant cause of strobilurin resistance, cytochrome b G143A subsititution, MgMfs1 can play a role in sensitivity of field strains of this pathogen to trifloxystrobin. RESULTS: In a major part of field strains of M. graminicola (collected in the Netherlands in 2004) containing the cytochrome b G143A substitution, the basal level of expression of MgMfs1 was elevated as compared with sensitive strains lacking the G143A substitution. Induction of MgMfs1 expression in wild-type isolates upon treatment with trifloxystrobin at sublethal concentrations proceeded rapidly. Furthermore, in disease control experiments on wheat seedlings, disruption mutants of MgMfs1 displayed an increased sensitivity to trifloxystrobin. CONCLUSION: It is concluded that the drug transporter MgMfs1 is a determinant of strobilurin sensitivity of field strains of M. graminicola. Copyright © 2008 Society of Chemical Industry [source] The different fates of mitochondria and chloroplasts during dark-induced senescence in Arabidopsis leavesPLANT CELL & ENVIRONMENT, Issue 12 2007OLIVIER KEECH ABSTRACT Senescence is an active process allowing the reallocation of valuable nutrients from the senescing organ towards storage and/or growing tissues. Using Arabidopsis thaliana leaves from both whole darkened plants (DPs) and individually darkened leaves (IDLs), we investigated the fate of mitochondria and chloroplasts during dark-induced leaf senescence. Combining in vivo visualization of fates of the two organelles by three-dimensional reconstructions of abaxial parts of leaves with functional measurements of photosynthesis and respiration, we showed that the two experimental systems displayed major differences during 6 d of dark treatment. In whole DPs, organelles were largely retained in both epidermal and mesophyll cells. However, while the photosynthetic capacity was maintained, the capacity of mitochondrial respiration decreased. In contrast, IDLs showed a rapid decline in photosynthetic capacity while maintaining a high capacity for mitochondrial respiration throughout the treatment. In addition, we noticed an unequal degradation of organelles in the different cell types of the senescing leaf. From these data, we suggest that metabolism in leaves of the whole DPs enters a ,stand-by mode' to preserve the photosynthetic machinery for as long as possible. However, in IDLs, mitochondria actively provide energy and carbon skeletons for the degradation of cell constituents, facilitating the retrieval of nutrients. Finally, the heterogeneity of the degradation processes involved during senescence is discussed with regard to the fate of mitochondria and chloroplasts in the different cell types. [source] Effects of incentive on working memory capacity: Behavioral and pupillometric dataPSYCHOPHYSIOLOGY, Issue 1 2008Richard P. Heitz Abstract We evaluated the hypothesis that individual differences in working memory capacity are explained by variation in mental effort, persons with low capacity exerting less effort than persons with high capacity. Groups previously rated high and low in working memory capacity performed the reading span task under three levels of incentive. The effort hypothesis holds that low span subjects exert less effort during task performance than do high spans. Subjects' pupil sizes were recorded online during task performance as a measure of mental effort. Both recall performance and pupil diameter were found to be increased under incentives, but were additive with span (incentives increased performance and pupil diameter equivalently for both span groups). Contrary to the effort hypothesis, task-evoked pupillary responses indicated that if anything, low span subjects exert more effort than do high spans. [source] Vitamin A distribution and content in tissues of the lamprey, Lampetra japonicaTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2004Heidi L. Wold Abstract Vitamin A (retinol and retinyl ester) distribution and content in tissues of a lamprey (Lampetra japonica) were analyzed by morphological methods, namely, gold chloride staining, fluorescence microscopy to detect specific vitamin A autofluorescence, and electron microscopy, as well as high-performance liquid chromatography (HPLC). Hepatic stellate cells showed an abundance of vitamin A stored in lipid droplets in their cytoplasm. Similar cells storing vitamin A were present in the intestine, kidney, gill, and heart in both female and male lampreys. Morphological data obtained by gold chloride staining method, fluorescence microscopy, transmission electron microscopy, and HPLC quantification of retinol were consistent. The highest level of total retinol measured by HPLC was found in the intestine. The second and third highest concentrations of vitamin A were found in the liver and the kidney, respectively. These vitamin A-storing cells were not epithelial cells, but mesoderm-derived cells. We propose as a hypothesis that these cells belong to the stellate cell system (family) that stores vitamin A and regulates homeostasis of the vitamin in the whole body in the lamprey. Fibroblastic cells in the skin and somatic muscle stored little vitamin A. These results indicate that there is difference in the vitamin A-storing capacity between the splanchnic and intermediate mesoderm-derived cells (stellate cells) and somatic and dorsal mesoderm-derived cells (fibroblasts) in the lamprey. Stellate cells derived from the splanchnic and intermediate mesoderm have high capacity and fibroblasts derived from the somatic and dorsal mesoderm have low capacity for the storage of vitamin A in the lamprey. Anat Rec Part A 276A:134,142, 2004. © 2004 Wiley-Liss, Inc. [source] Increasing amino acid supply in pea embryos reveals specific interactions of N and C metabolism, and highlights the importance of mitochondrial metabolismTHE PLANT JOURNAL, Issue 6 2008Kathleen Weigelt Summary The application of nitrogen to legumes regulates seed metabolism and composition. We recently showed that the seed-specific overexpression of amino acid permease VfAAP1 increases amino acid supply, and the levels of N and protein in the seeds. Two consecutive field trials using Pisum sativum AAP1 lines confirmed increases in the levels of N and globulin in seed; however, compensatory changes of sucrose/starch and individual seed weight were also observed. We present a comprehensive analysis of AAP1 seeds using combinatorial transcript and metabolite profiling to monitor the effects of nitrogen supply on seed metabolism. AAP1 seeds have increased amino acids and stimulated gene expression associated with storage protein synthesis, maturation, deposition and vesicle trafficking. Transcript/metabolite changes reveal the channelling of surplus N into the transient storage pools asparagine and arginine, indicating that asparagine synthase is transcriptionally activated by high N levels and/or C limitation. Increased C-acceptor demand for amino acid synthesis, resulting from elevated levels of N in seeds, initiates sucrose mobilization and sucrose-dependent pathways via sucrose synthase, glycolysis and the TCA cycle. The AAP1 seeds display a limitation in C, which leads to the catabolism of arginine, glutamic acid and methionine to putrescine, ,-alanine and succinate. Mitochondria are involved in the coordination of C/N metabolism, with branched-chain amino acid catabolism and a ,-amino-butyric acid shunt. AAP1 seeds contain higher levels of ABA, which is possibly involved in storage-associated gene expression and the N-dependent stimulation of sucrose mobilization, indicating that a signalling network of C, N and ABA is operating during seed maturation. These results demonstrate that legume seeds have a high capacity to regulate N:C ratios, and highlight the importance of mitochondria in the control of N,C balance and amino acid homeostasis. [source] Computed Tomography of the Lungs of the Dog by a Six-generation CT Scanner, Intravenous Contrast Medium and Different WindowsANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2005L. Cardoso Computed tomography (CT) is a modern technique of image diagnosis particularly recommended in human medicine to evaluate the existence of pulmonary pathological changes such as neoplasms, metastasis, interstitial infiltrates, etc. In veterinary medicine, however, few anatomical and clinical CT studies in the dog have used apparatus of the latest generation, including injection of intravenous contrast and application of regional specific CT windows with different window width (WW) and window level (WL) to evaluate the lungs, the pulmonary vessels and the bronchial structures. This methodology allows the obtaining of clear CT images with high capacity of tissue discrimination and different shades of attenuation. In this work we have planned a tomographic study of the lungs of the dog by using a six-generation spiral CT scanner (Toshiba Ex Vision), belonging to the private Medical Institute of Radiology ,Irion' of Porto Alegre, Brazil. Four mixed-breed mature dogs (4,6 years, 15,20 kg) were used, two males and two females. The dogs were anaesthetized and kept in a maximum inspiration when obtaining the images. Dogs were placed in a stretcher in a ventral or sternal recumbency. Previously, the contrast urografin® was injected in the cephalic vein. Different CT windows were applied in order to increase the quality of the images: pulmonary window (WW 928; WL -680), high-resolution pulmonary window (WW 1085; WL -750), and soft tissue window (WW 652; WL -34). The use of intravenous contrast, different CT windows and a modern CT apparatus produced excellent images of the pulmonary parenchyma, the pleural cavity, the pulmonary veins, the lobular rami of the pulmonary artery and the lobular bronchi. [source] Apparent digestibility of selected feed ingredients for white shrimp Litopenaeus vannamei, BooneAQUACULTURE RESEARCH, Issue 1 2009Qihui Yang Abstract Apparent digestibility coefficients of dry matter (DM), crude protein, crude lipid, gross energy, phosphorus and amino acids in Peruvian fish meal (FM), fermented soybean meal, extruded soybean meal, soybean meal, peanut meal, wheat gluten meal, corn gluten meal, shrimp byproduct meal, meat and bone meal (MBM), poultry meat meal and plasma protein meal (PPM) were determined for white shrimp (Litopenaeus vannamei). A reference diet (RF) and test diets (consisting of 70% RF diet and 30% of the feedstuff) were used with 0.5% chromic oxide as an external indicator. A total of 1440 shrimp (initial mean body weight 1.05 ± 0.01 g) were randomly stocked into thirty-six 500-L fibreglass tanks with 40 shrimp per tank and three tanks per diet. Faeces were collected from triplicate groups of shrimp by a faecal collection vessel attached to the shrimp-rearing tank. The shrimp were fed to apparent satiation four times a day and the feeding experiment lasted for 6 weeks. Statistics indicate that apparent DM digestibilities for white shrimp (L. vannamei) were the highest for FM, ranged 52.83,71.23% for other animal products and 69.98,77.10% for plant products. The protein and lipid from plant and animal sources were well digested by white shrimp. Apparent protein and lipid digestibility were in the range 87.89,93.18% and 91.57,95.28%, respectively, in plant products, and 75.00,92.34% and 83.72,92.79%, respectively, for animal products. The white shrimp demonstrated a high capacity to utilize phosphorus in the ingredients. The apparent phosphorus digestibility ranges of animal feedstuffs and plant feedstuffs were 58.90,71.61% and 75.77,82.30% respectively. Amino acid availability reflected protein digestibility, except that in MBM, for which the availability of some amino acid was lower, possibly due to protein damage during processing. Digestibility information could promote the use of ingredient substitution in least-cost formulated diets for white shrimp. [source] Effect of dietary protein and energy levels on growth, oxygen consumption, haemolymph and digestive gland carbohydrates, nitrogen excretion and osmotic pressure of Litopenaeus vannamei (Boone) and L. setiferus (Linne) juveniles (Crustacea, Decapoda; Penaeidae)AQUACULTURE RESEARCH, Issue 7 2001C Rosas Abstract The influence of protein and energy levels on growth rate, survival, pre- and post-prandial oxygen consumption, ammonia excretion, haemolymph glucose (HG), glycogen in digestive gland and osmotic pressure (OP) in white shrimp Litopenaeus vannamei (Boone) and L. setiferus (Linne) juveniles was studied. Diets containing a high-quality protein at a protein/energy (P/E) ratio of 16, 26, 31 and 36 mg kJ,1 were fed at 20% of shrimp body weight of two sizes: < 1 g and >,1 g. Both species showed a optimum P/E ratio of 36 mg kJ,1 (33,44% protein and 6,23% carbohydrate) in juveniles <,1 g. For shrimp >,1 g, L. setiferus showed a higher growth rate in the diet with 16 mg kJ,1 (27% protein; 32% carbohydrate) and L. vannamei between 26 and 36 mg kJ,1 (33,44% protein and 6,23% carbohydrate). In both experiments, the growth rate of L. vannamei was 2,3 times that observed in L. setiferus. Routine oxygen consumption and apparent heat increment (AHI) of L. setiferus juveniles was two times higher than that observed in L. vannamei juveniles, which could indicate that L. setiferus has a higher metabolic rate. The O/N ratio varied according to protein level, with higher values (O/N = 180) with a 16-mg kJ,1 diet and lower values (O/N = 73) with a 36-mg kJ,1 diet in L. setiferus juveniles. A similar variation in O/N ratio was obtained in L. vannamei fed with all diets with an interval between 22 and 50. An inverse relation between ammonia excretion and HG, and digestive gland glycogen (DGG) in relation to an increase in the P/E ratio indicate that both shrimp species are well adapted to use carbohydrates and/or proteins from their diet. The higher values of hyper-osmotic capacity (hyper-OC) were observed in L. setiferus <,1 g fed with 36 mg kJ,1 and the lowest in L. vannamei <,1 g fed with 31 mg kJ,1. Intermediate values of hyper-OC were observed in both species fed all diets indicating that osmotic factors of juveniles <,1 g of both species are more affected by the P/E ratio than juveniles >,1 g. All results showed that juveniles >,1 g of both species are less dependent of P/E ratio than juveniles <,1 g. Litopenaeus vannamei is a most tolerant shrimp species with a high capacity to use a wide range of dietary P/E ratios for growth, which may be due to its lower energy requirements. Litopenaeus setiferus showed a lower capacity to accept different P/E ratios but the optimum P/E ratio obtained with this species shows that L. setiferus accept diets with a high carbohydrate level as well. These results demonstrate that there are nutritional and physiological differences that explain the differences that have been observed when both species were cultured in commercial ponds. [source] Small-scale spatial dynamics of vegetation in a grazed Uruguayan grasslandAUSTRAL ECOLOGY, Issue 4 2009MARCOS TEXEIRA Abstract We explored the small-scale plant species mobility in a subhumid native grassland subjected to grazing by cattle in south-western Uruguay. We established four permanent plots of 40 × 40 cm, divided in 16 × 16 cells. In each cell, the presence of species was seasonally recorded for 2 years and annually recorded for 4 years. By nesting the cells, we studied the mobility at different scales, from 6.25 cm2 to 400 cm2. At each scale we measured species richness, cumulative richness and the turnover rates of the dominant species. We found that the cumulative species richness was an increasing power function, with higher accumulation rates with smaller spatial scale. Although species richness showed seasonal fluctuations, the mean species richness was constant during the study period. We detected significant spatio-temporal variability in mobility patterns among species. Certain species showed a high capacity to colonize new sites, whereas other species rotate among sites that they previously occupied. Grazed communities in Uruguayan Campos are structured as a dense matrix of perennials grasses and forbs, where vegetative propagation is the main form of growth of the species. The small-scale dynamics and the high variability in the mobility characteristics could be linked with the diversity of growth forms and spatial strategies of the species in this community. We believe that a high degree of small-scale spatial dynamics contribute to explain the species coexistence and the apparent stability of communities at local scales. [source] Visualisation of human dental pulp vasculature by immunohistochemical and immunofluorescent detection of CD34: A comparative studyAUSTRALIAN ENDODONTIC JOURNAL, Issue 3 2006Anna Digka Abstract CD34 is considered a pan-endothelial cell marker for paraffin-embedded sections. In this study, both immunohistochemistry and immunofluorescence were applied in human dental pulp specimens of moderate thickness (10 µm) in order to observe the vasculature of this tissue using CD34. Both techniques revealed a homogenous staining pattern with capillaries and larger vessels showing complete and strong membrane staining reflecting the high capacity of the pulp for regeneration and response to different stimuli. A novel approach in the identification of the pulpal vasculature by Cy5-conjugated anti-CD34 is introduced in this study. By this technique the dense capillary plexus of the sub-odontoblastic region, which is responsible for the reaction of the tissue to any physical or chemical stimuli or pathological condition, can be clearly identified, while immunohistochemistry did not reveal such a detailed staining pattern. [source] Polycomb, trithorax and the decision to differentiateBIOESSAYS, Issue 4 2006Leonie Ringrose For stem cells, life is full of potential: they have a high capacity to proliferate and a wide choice of future identities. When they differentiate, cells leave behind this freedom and become ever more committed to a single fate. Intriguingly, the Polycomb and Trithorax groups of proteins are vital to the very different natures of both stem cells and differentiated cells, but little is known about how they make the transition from one cell type to the other. A recent paper1 throws light on this mystery, showing that the Polycomb proteins dramatically change their behaviour at a crucial moment of differentiation. BioEssays 28: 330,334, 2006. © 2006 Wiley Periodicals, Inc. [source] | |||||||||||||||||||||||||||||||||||||