bluuebunny/crossref_metadata_2025 huggingface dataset:
Subcellular localization and functional expression of the glycerol uptake protein 1 (GUP1) of Saccharomyces cerevisiae tagged with green fluorescent protein
Authors: Bleve Gianluca , Zacheo Giuseppe , Cappello Maria Stella , Dellaglio Franco , Grieco Francesco
Published: August 2005

GFP (green fluorescent protein) from Aequorea victoria was used as an in vivo reporter protein when fused to the N- and C-termini of the glycerol uptake protein 1 (Gup1p) of Saccharomyces cerevisiae. The subcellular localization and functional expression of biologically active Gup1–GFP chimaeras was monitored by confocal laser scanning and electron microscopy, thus supplying the first study of GUP1 dynamics in live yeast cells. The Gup1p tagged with GFP is a functional glycerol transporter localized at the plasma membrane and endoplasmic reticulum levels of induced cells. The factors involved in proper localization and turnover of Gup1p were revealed by expression of the Gup1p–GFP fusion protein in a set of strains bearing mutations in specific steps of the secretory and endocytic pathways. The chimaerical protein was targeted to the plasma membrane through a Sec6-dependent process; on treatment with glucose, it was endocytosed through END3 and targeted for degradation in the vacuole. Gup1p belongs to the list of yeast proteins rapidly down-regulated by changing the carbon source in the culture medium, in agreement with the concept that post-translational modifications triggered by glucose affect proteins of peripheral functions. The immunoelectron microscopy assays of cells expressing either Gup1–GFP or GFP–Gup1 fusions suggested the Gup1p membrane topology: the N-terminus lies in the periplasmic space, whereas its C-terminal tail has an intracellular location. An extra cytosolic location of the N-terminal tail is not generally predicted or determined in yeast membrane transporters.
In vivo functional characterization of the Escherichia coli ammonium channel AmtB: evidence for metabolic coupling of AmtB to glutamine synthetase
Authors: Javelle Arnaud , Thomas Gavin , Marini Anne-Marie , Krämer Reinhard , Merrick Mike
Published: August 2005

The Escherichia coli AmtB protein is member of the ubiquitous Amt family of ammonium transporters. Using a variety of [14C]methylammonium-uptake assays in wild-type E. coli, together with amtB and glutamine synthetase (glnA) mutants, we have shown that the filtration method traditionally used to measure [14C]methylammonium uptake actually measures intracellular accumulation of methylglutamine and that the kinetic data deduced from such experiments refer to the activity of glutamine synthetase and not to AmtB. Furthermore, the marked difference between the Km values of glutamine synthetase calculated in vitro and those calculated in vivo from our data suggest that ammonium assimilation by glutamine synthetase is coupled to the function of AmtB. The use of a modified assay technique allows us to measure AmtB activity in vivo. In this way, we have examined the role that AmtB plays in ammonium/methylammonium transport, in the light of conflicting proposals with regard to both the mode of action of Amt proteins and their substrate, i.e. ammonia or ammonium. Our in vivo data suggest that AmtB acts as a slowly conducting channel for NH3 that is neither dependent on the membrane potential nor on ATP. Furthermore, studies on competition between ammonium and methylammonium suggest that AmtB has a binding site for NH4+ on the periplasmic face.
Evidence for mitochondrial localization of a novel human sialidase (NEU4)
Authors: Yamaguchi Kazunori , Hata Keiko , Koseki Koichi , Shiozaki Kazuhiro , Akita Hirotoshi , Wada Tadashi , Moriya Setsuko , Miyagi Taeko
Published: August 2005

Based on the human cDNA sequence predicted to represent the NEU4 sialidase gene in public databases, a cDNA covering the entire coding sequence was isolated from human brain and expressed in mammalian cells. The cDNA encodes two isoforms: one possessing an N-terminal 12-amino-acid sequence that is predicted to be a mitochondrial targeting sequence, and the other lacking these amino acids. Expression of the isoforms is tissuespecific, as assessed by reverse transcription–PCR. Brain, muscle and kidney contained both isoforms; liver showed the highest expression, and the short form was predominant in this organ. In transiently transfected COS-1 cells, enzyme activity was markedly increased with gangliosides as well as with glycoproteins and oligosaccharides as substrates compared with the control levels. This differs from findings with other human sialidases. Although the isoforms were not distinguishable with regard to substrate specificity, they exhibited differential subcellular localizations. Immunofluorescence microscopy and biochemical fractionation demonstrated that an exogenously expressed haemagglutinin-tagged long form of NEU4 was concentrated in mitochondria in several human culture cell types, whereas the short form was present in intracellular membranes, indicating that the sequence comprising the N-terminal 12 amino acid residues acts as a targeting signal for mitochondria. Co-localization of the long form to mitochondria was further supported by efficient targeting of the N-terminal region fused to enhanced green fluorescent protein, and by the targeting failure of a mutant with an amino acid substitution in this region. NEU4 is possibly involved in regulation of apoptosis by modulation of ganglioside GD3, which accumulates in mitochondria during apoptosis and is the best substrate for the sialidase.
Matriptase-3 is a novel phylogenetically preserved membrane-anchored serine protease with broad serpin reactivity
Authors: Szabo Roman , Netzel-Arnett Sarah , Hobson John P. , Antalis Toni M. , Bugge Thomas H.
Published: August 2005

We report in the present study the bioinformatic identification, molecular cloning and biological characterization of matriptase-3, a novel membrane-anchored serine protease that is phylogenetically preserved in fish, birds, rodents, canines and primates. The gene encoding matriptase-3 is located on syntenic regions of human chromosome 3q13.2, mouse chromosome 16B5, rat chromosome 11q21 and chicken chromosome 1. Bioinformatic analysis combined with cDNA cloning predicts a functional TTSP (type II transmembrane serine protease) with 31% amino acid identity with both matriptase/MT-SP1 and matriptase-2. This novel protease is composed of a short N-terminal cytoplasmic region followed by a transmembrane domain, a stem region with one SEA, two CUB and three LDLRa (low-density lipoprotein receptor domain class A) domains and a C-terminal catalytic serine protease domain. Transcript analysis revealed restricted, species-conserved expression of matriptase-3, with the highest mRNA levels in brain, skin, reproductive and oropharyngeal tissues. The full-length matriptase-3 cDNA directed the expression of a 90 kDa N-glycosylated protein that localized to the cell surface, as assessed by cell-surface biotin labelling. The purified activated matriptase-3 serine protease domain expressed in insect cells hydrolysed synthetic peptide substrates, with a strong preference for Arg at position P1, and showed proteolytic activity towards several macromolecular substrates, including gelatin, casein and albumin. Interestingly, activated matriptase-3 formed stable inhibitor complexes with an array of serpins, including plasminogen activator inhibitor-1, protein C inhibitor, α1-proteinase inhibitor, α2-antiplasmin and antithrombin III. Our study identifies matriptase-3 as a novel biologically active TTSP of the matriptase subfamily having a unique expression pattern and post-translational regulation.
The N370S (Asn370→Ser) mutation affects the capacity of glucosylceramidase to interact with anionic phospholipid-containing membranes and saposin C
Authors: Salvioli Rosa , Tatti Massimo , Scarpa Susanna , Moavero Sabrina Maria , Ciaffoni Fiorella , Felicetti Federica , Kaneski Christine R. , Brady Roscoe O. , Vaccaro Anna Maria
Published: August 2005

The properties of the endolysosomal enzyme GCase (glucosylceramidase), carrying the most prevalent mutation observed in Gaucher patients, namely substitution of an asparagine residue with a serine at amino acid position 370 [N370S (Asn370→Ser) GCase], were investigated in the present study. We previously demonstrated that Sap (saposin) C, the physiological GCase activator, promotes the association of GCase with anionic phospholipid-containing membranes, reconstituting in this way the enzyme activity. In the present study, we show that, in the presence of Sap C and membranes containing high levels of anionic phospholipids, both normal and N370S GCases are able to associate with the lipid surface and to express their activity. Conversely, when the amount of anionic phospholipids in the membrane is reduced (∼20% of total lipids), Sap C is still able to promote binding and activation of the normal enzyme, but not of N370S GCase. The altered interaction of the mutated enzyme with anionic phospholipid-containing membranes and Sap C was further demonstrated in Gaucher fibroblasts by confocal microscopy, which revealed poor co-localization of N370S GCase with Sap C and lysobisphosphatidic acid, the most abundant anionic phospholipid in endolysosomes. Moreover, we found that N370S Gaucher fibroblasts accumulate endolysosomal free cholesterol, a lipid that might further interfere with the interaction of the enzyme with Sap C and lysobisphosphatidic acid-containing membranes. In summary, our results show that the N370S mutation primarily affects the interaction of GCase with its physiological activators, namely Sap C and anionic phospholipid-containing membranes. We thus propose that the poor contact between N370S GCase and its activators may be responsible for the low activity of the mutant enzyme in vivo.
Decoupling and recoupling using continuous-wave irradiation in magic-angle-spinning solid-state NMR: A unified description using bimodal Floquet theory
Authors: Ernst Matthias , Samoson Ago , Meier Beat H.
Published: August 2005

The application of two or more different time-dependent coherent perturbations with, in general, incommensurable frequencies occurs quite commonly in NMR experiments. Here we develop a unified description of the entire class of experiments using bimodal Floquet theory and van Vleck–Primas perturbation theory. This treatment leads to a time-independent effective Hamiltonian in Hilbert space and can be looked at as a generalization of average Hamiltonian theory to several incommensurate time dependencies. As a prototype experiment we treat the application of continuous-wave (cw) radio-frequency irradiation in combination with magic-angle sample spinning. Practically relevant examples of this type of experiments are heteronuclear spin decoupling and recoupling experiments using cw irradiation, e.g., rotary-resonance recoupling. Perturbations up to the third order must be taken into account to explain all experimentally observed resonance conditions.
Collisional and photoinitiated reaction dynamics in the ground electronic state of Ca–HCl
Authors: Sanz Cristina , van der Avoird Ad , Roncero O.
Published: August 2005

Ca + H Cl ( υ , j ) reactive collisions were studied for different rovibrational states of the HCl reactant using wave-packet calculations in reactant Jacobi coordinates. A recently proposed potential-energy surface was used with a barrier of ≈0.4eV followed by a deep well. The possibility of an insertion mechanism due to this last well has been analyzed and it was found that once the wave packet passes over the barrier most of it goes directly to CaCl+H products, which shows that the reaction dynamics is essentially direct. It was also found that there is no significant change in the reaction efficiency as a function of the initial HCl rovibrational state, because CaHCl at the barrier has an only little elongated HCl bond. Near the threshold for reaction with HCl(υ=0), however, the reaction shows significant steric effects for j>0. In a complementary study, the infrared excitation from the Ca–HCl van der Waals well was simulated. The spectrum thus obtained shows several series of resonances which correspond to quasibound states correlating to excited HCl(υ) vibrations. The Ca–HCl binding energies of these quasibound states increase dramatically with υ, from 75to650cm−1, because the wave function spreads increasingly over larger HCl bond lengths. Thus it explores the region of the barrier saddle point and the deep insertion well. Although also the charge-transfer contribution increases with υ, the reaction probability for resonances of the υ=2 manifold, which are well above the reaction threshold, is still negligible. This explains the relatively long lifetimes of these υ=2 resonances. The reaction probability becomes significant at υ=3. Our simulations have shown that an experimental study of this type will allow a gradual spectroscopic probing of the barrier for the reaction.
Probing the barrier for CH2CHCO→CH2CH+CO by the velocity map imaging method
Authors: Lau K.-C. , Liu Y. , Butler L. J.
Published: August 2005

This work determines the dissociation barrier height for CH2CHCO→CH2CH+CO using two-dimensional product velocity map imaging. The CH2CHCO radical is prepared under collision-free conditions from C–Cl bond fission in the photodissociation of acryloyl chloride at 235nm. The nascent CH2CHCO radicals that do not dissociate to CH2CH+CO, about 73% of all the radicals produced, are detected using 157-nm photoionization. The Cl(P3∕22) and Cl(P1∕22) atomic fragments, momentum matched to both the stable and unstable radicals, are detected state selectively by resonance-enhanced multiphoton ionization at 235nm. By comparing the total translational energy release distribution P(ET) derived from the measured recoil velocities of the Cl atoms with that derived from the momentum-matched radical cophotofragments which do not dissociate, the energy threshold at which the CH2CHCO radicals begin to dissociate is determined. Based on this energy threshold and conservation of energy, and using calculated C–Cl bond energies for the precursor to produce CH2CHĊO or ĊH2CHCO, respectively, we have determined the forward dissociation barriers for the radical to dissociate to vinyl+CO. The experimentally determined barrier for CH2CHĊO→CH2CH+CO is 21±2kcalmol−1, and the computed energy difference between the CH2CHĊO and the ĊH2CHCO forms of the radical gives the corresponding barrier for ĊH2CHCO→CH2CH+CO to be 23±2kcalmol−1. This experimental determination is compared with predictions from electronic structure methods, including coupled-cluster, density-functional, and composite Gaussian-3-based methods. The comparison shows that density-functional theory predicts too low an energy for the ĊH2CHCO radical, and thus too high a barrier energy, whereas both the Gaussian-3 and the coupled-cluster methods yield predictions in good agreement with experiment. The experiment also shows that acryloyl chloride can be used as a photolytic precursor at 235nm of thermodynamically stable CH2CHĊO radicals, most with an internal energy distribution ranging from ≈3to≈21kcalmol−1. We discuss the results with respect to the prior work on the O(P3)+propargyl reaction and the analogous O(P3)+allyl system.
The Perron-Frobenius operators, invariant measures and representations of the Cuntz-Krieger algebras
Authors: Kawamura Katsunori
Published: August 2005

For a transformation F on a measure space (X,μ), we show that the Perron-Frobenius operator of F can be written by a representation (L2(X,μ),π) of the Cuntz-Krieger algebra OA associated with F when F satisfies some assumption. Especially, when OA is the Cuntz algebra ON and (L2(X,μ),π) in the above is some irreducible representation of ON, then there is an F-invariant measure on X which is absolutely continuous with respect to μ.
Direct imaging of the end-of-range and surface profiles of proton-beam written erbium-doped waveguide amplifiers by atomic force microscopy
Authors: Sum T. C. , Bettiol A. A. , van Kan J. A. , Venugopal Rao S. , Watt F. , Liu K. , Pun E. Y. B.
Published: August 2005

Buried channel waveguide amplifiers in erbium∕ybtterbium codoped phosphate glass were fabricated using proton-beam writing. Single-mode waveguides were fabricated with fluences ranging from 0.4to2.0×1015particles∕cm2. The end-of-range and surface profiles of the waveguides were investigated using atomic force microscopy. The waveguiding effect was investigated using the end-fire coupling technique. From the near-field mode profiles, the refractive index profiles of these waveguides were recovered using the propagation mode near-field method. From these results, it can be deduced that for phosphate glass waveguides fabricated with fluences <1.0×1015particles∕cm2, the ionization from the electronic stopping, rather than the nuclear damage processes, is the major contributing factor leading to an increase in the refractive index near the end of range.
Terahertz absorption and dispersion of fluorine-doped single-walled carbon nanotube
Authors: Jeon Tae-In , Son Joo-Hiuk , An Kay Hyeok , Lee Young Hee , Lee Young Seak
Published: August 2005

We present experimental and theoretical results on the absorption and dispersion of a single-walled carbon nanotube (SWNT) with and without fluorine (F) doping in the frequency range of 0.2–3THz. Under the doping conditions, the power absorption, index of refraction, and the real and imaginary parts of the conductivity are decreased compared to those for pure SWNTs because the charge transfer to the F2 molecule will be increased. Our measurement of pure SWNT agrees well with the Maxwell-Garnett and Drude models. However, the F-doped SWNT requires adding a Lorentz oscillator term for good agreement between theory and measurement.
X-ray powder diffraction of NaCl under pressure: Nanocrystals induce anomalous strains
Authors: Weber H.-J. , Keller H.-L. , Lathe C. , Popa-Varga C.
Published: August 2005

Energy-dispersive powder diffraction as a function of pressure has been used to search for elastic interactions between CuCl nanocrystals embedded in NaCl and sample surfaces. Anomalous properties have been observed only for (200) reflexes of the NaCl matrix although crystallographic structure and imposed pressure are essentially isotropic. The material shows an initial compressive strain of S(200)=−0.002 which is large compared with the low concentration of CuCl but small compared with the accuracy achieved in a high-pressure apparatus. It was necessary to identify the influences of grain morphology, sample preparation, deformation of the sample cell, uniaxial pressure component, and nonlinear elasticity to obtain reliable results. The initial strain is accompanied by an elastic hardening of NaCl. The appearance of both effects is traced back to the influence of sample surfaces. This interpretation is verified by exciton spectroscopy studied in a thin optical plate. A comparison between experimental results and elastic continuum theory demonstrates that the theory describes correctly the observed phenomena but predicts effects which are significantly smaller than the measured values. The mechanisms which are able to amplify the impact of nanocrystals on the matrix are discussed.
Influence of parasitic phases on the properties of BiFeO3 epitaxial thin films
Authors: Béa H. , Bibes M. , Barthélémy A. , Bouzehouane K. , Jacquet E. , Khodan A. , Contour J.-P. , Fusil S. , Wyczisk F. , Forget A. , Lebeugle D. , Colson D. , Viret M.
Published: August 2005

We have explored the influence of deposition pressure and temperature on the growth of BiFeO3 thin films by pulsed laser deposition onto (001)-oriented SrTiO3 substrates. Single-phase BiFeO3 films are obtained in a region close to 10−2mbar and 580°C. In nonoptimal conditions, x-ray diffraction reveals the presence of Fe oxides or of Bi2O3. We address the influence of these parasitic phases on the magnetic and electrical properties of the films and show that films with Fe2O3 systematically exhibit a ferromagnetic behavior, while single-phase films have a low bulklike magnetic moment. Conductive-tip atomic force microscopy mappings also indicate that Bi2O3 conductive outgrowths create shortcuts through the BiFeO3 films, thus preventing their practical use as ferroelectric elements in functional heterostructures.
Efficient photoconductive devices at infrared wavelengths using quantum dot-polymer nanocomposites
Authors: Choudhury K. Roy , Sahoo Y. , Ohulchanskyy T. Y. , Prasad P. N.
Published: August 2005

We report high photoconductivity and narrow luminescence in nanocomposites of PbSe quantum dots in a polymeric matrix. The nanocomposites are photoactive at infrared wavelengths with narrow emission bands, tunable with the quantum dot sizes. The quantum dots sensitize the polymer at distinct wavelengths across the infrared range between 800 nm and 2μm, by virtue of quantum-size effects. Photoconductivity measured in the nanocomposites results in a quantum efficiency of ∼3%, which is among the highest reported so far in this spectral range.
Scanning probe microscopy with quartz crystal cantilever
Authors: Ono Takahito , Lin Yu-Ching , Esashi Masayoshi
Published: August 2005

This paper reports a quartz crystal cantilever for piezoelectric vibration sensing in scanning probe microscopy (SPM). SPM imaging by a frequency modulation detection method is demonstrated in ambient atmosphere using a 22.5-μm-thick cantilevered AT-cut quartz crystal with metal electrodes on both sides. The spring constant of the cantilever is calculated to be 10N∕m. Despite the low electromechanical coupling between the piezoelectric effect and the flexural vibration, a high sensitivity of 0.07nm∕(Hz)0.5 to vibration is achieved in the second flexural mode. The cantilever self-oscillates on the basis of piezoelectric detection, and offers short-term stability of within approximately 0.5Hz in ambient atmosphere at room temperature. The force curve of the self-oscillating cantilever shows that the self-oscillation can be sustained even when in contact with a sample.
Coevolution between nonhomologous but functionally similar proteins and their conserved partners in the
Legionella
pathogenesis system
Authors: Feldman Michal , Zusman Tal , Hagag Shelly , Segal Gil
Published: August 2005

Legionella pneumophila
, the causative agent of Legionnaires' disease, and other pathogenic
Legionella
species multiply inside protozoa and human macrophages by using the intracellular multiplication (Icm)/defect in organelle trafficking (Dot) type-IV secretion system. The IcmQ protein, which possesses pore-forming activity, and IcmR, which regulates the IcmQ activity, are two essential components of this system. Analysis of the region expected to contain these two genes from 29
Legionella
species revealed the presence of a conserved
icmQ
gene and a large hypervariable gene family [functional homologues of
icmR
(
fir
) genes], located at the
icmR
genomic position. Although hypervariable in their sequence, the
fir
genes from all 29
Legionella
species were found, together with their corresponding
icmQ
genes, to function similarly during infection. In addition, all FIR proteins we examined were found to interact with their corresponding IcmQ proteins. Detailed bioinformatic, biochemical, and genetic analysis of the interaction between the variable FIR proteins and conserved IcmQ proteins revealed that their interaction depends on a variable region located between two conserved domains of IcmQ. This variable region was also found to be critical for IcmQ self-interaction, and the region probably coevolved with the corresponding FIR protein. A FIR-IcmQ pair was also found in
Coxiella burnetii
, the only known non
-Legionella
bacterium that contains an Icm/Dot system, indicating the significance of this protein pair for the function of this type-IV secretion system. We hypothesize that this gene variation, which is probably mediated by positive selection, plays an important role in the evolutionary arms race between the protozoan host cell and the pathogen.
Female Iberian wall lizards prefer male scents that signal a better cell-mediated immune response
Authors: López Pilar , Martín José
Published: August 2005

In spite of the importance of chemoreception in sexual selection of lizards, only a few studies have examined the composition of chemical signals, and it is unknown whether and how chemicals provide honest information. Chemical signals might be honest if there were a trade-off between sexual advertisement and the immune system. Here, we show that proportions of cholesta-5,7-dien-3-ol in femoral secretions of male Iberian wall lizards (
Podarcis hispanica
) were related to their T-cell-mediated immune response. Thus, only males with a good immune system may allocate higher amounts of this chemical to signalling. Furthermore, females selected scents of males with higher proportions of cholesta-5,7-dien-3-ol and lower proportions of cholesterol. Thus, females might base their mate choice on the males' quality as indicated by the composition of their chemical signals.
Large-scale lattice Boltzmann simulations of complex fluids: advances through the advent of computational Grids
Authors: Harting Jens , Chin Jonathan , Venturoli Maddalena , Coveney Peter V
Published: August 2005

During the last 2.5 years, the RealityGrid project has allowed us to be one of the fewscientificgroups involved in the development of computational Grids. Since smoothly working production Grids are not yet available, we have been able to substantially influence the direction of software and Grid deployment within the project. In this paper, we review our results from large-scale three-dimensional lattice Boltzmann simulations performed over the last 2.5 years. We describe how the proactive use of computational steering, and advanced job migration and visualization techniques enabled us to do our scientific work more efficiently. The projects reported on in this paper are studies of complex fluid flows under shear or in porous media, as well as large-scale parameter searches, and studies of the self-organization of liquid cubic mesophases.
Characterization ofPseudomonasSpecies Isolated from the Rhizosphere of Plants Grown in Serozem Soil, Semi-Arid Region of Uzbekistan
Authors: Egamberdiyeva Dilfuza
Published: August 2005

Collections of nativePseudomonasspp. are kept at the NCAM of Uzbekistan. Some of those organisms were isolated from the rhizosphere of cotton, wheat, corn, melon, alfalfa, and tomato grown in field locations within a semi-arid region of Uzbekistan. Strains used for this study were Pseudomonas alcaligenes,P. aurantiaca,P. aureofaciens,P. denitrificans,P. mendocina,P. rathonis, andP. stutzeri. Some of the pseudomonads have been characterized in this report. These strains produced enzymes, phytohormone auxin (IAA), and were antagonist against plant pathogenic fungi inin vitroexperiments. Most of the strains were salt tolerant and temperature resistant. Some of thePseudomonas spp. isolated in this study have been found to increase the growth of wheat, corn, and tomato in pot experiments.
Adolescents with Chronic Illnesses: School Absenteeism, Perceived Peer Aggression, and Loneliness
Authors: Shute Rosalyn H. , Walsh Christine
Published: August 2005

Frequent school absence is often cited as a risk factor for peer relationship problems in youngsters with chronic illnesses, but this assumption has not been subjected to quantitative empirical examination. This issue was examined in the present study by exploring the relationship between school absenteeism, peer aggression, and loneliness in adolescents with chronic illnesses. Forty-one adolescents with chronic illnesses completed a modified version of the Direct and Indirect Aggression Scale and the Asher Loneliness Scale. Details of school absences and hospitalizations were obtained from parents and school and hospital records. No evidence was found to support the notion that peer aggression and loneliness are related to absenteeism, but social aggression (for both boys and girls) and verbal aggression (more markedly for girls) were associated with loneliness. Of the group, 19% reported experiencing verbal aggression and 12% social aggression at least weekly; informal qualitative data suggesting that such aggression is often related to limited sporting ability and appearance. Interventions at both the individual and school community level are warranted.
A Metachronous, Atypical, Multifocal Renal Oncocytoma with a Concomitant Renal Cell Carcinoma of the Contralateral Side and Bilateral Multifocal Oncocytomas: Two Case Reports and Review of Literature
Authors: Burger Maximilian , Denzinger Stefan , Filbeck Thomas , Hartmann Arndt , Rößler Wolfgang , Hammerschmied Christina
Published: August 2005

We present one case of a metachronous, atypical, multifocal renal oncocytoma with a concomitant chromophobe renal cell carcinoma (RCC) of the contralateral side and one case of bilateral and multifocal oncocytomas. Oncocytomas are benign renal tumours that rarely appear bilateral or multifocal or with coexisting RCC. A common pathogenic denominator of oncoytomas and RCC is being discussed. The first case was a 63 years old patient presenting with a history of nephrectomy for a pT1 G1 pN0 R0 papillary RCC 4 years prior to presentation, showed two tumours of a singular kidney. Upon nephron-sparing surgery one typical and one atypical oncocytoma with an invasion of the perinephric fat were found. Comparative genomic hybridisation was performed. Both tumours revealed genetic alterations with loss of genetic material on chromosome 1p. The second case was a 62 years old patient presenting with multifocal and bilateral renal tumours of undeclared dignity upon imaging. During open exploration all tumours could be removed by nephron-sparing surgery and were identified as oncocytomas. Again comparative genomic hybridisation was performed. All 4 tumours revealed genetic alterations with loss of genetic material on chromosome 1p, one of the tumours an additional loss of chromosome 10.
A novel tetracationic phthalocyanine as a potential skin phototherapeutic agent
Authors: Fabris Clara , Soncin Marina , Mazzon Emanuela , Calzavara‐Pinton Piergiacomo , Lia Fantetti , Giacomo Chiti , Dei Donata , Tampucci Silvia , Roncucci Gabrio , Jori Giulio
Published: August 2005

Abstract:  An amphiphilic tetracationic derivative of Zn(II)‐phthalocyanine (RLP068) was prepared by means of chemical synthesis and was showed to possess efficient photophysical and photosensitizing properties against model biological substrates. RLP068 was incorporated into a gel formulation, which allowed its ready penetration into the epidermal layers, but not into the dermis, of both Balb/c and hairless SKH1 mice after 1–2 h of topical deposition. Pharmacokinetic studies showed that the phthalocyanine thus formulated does not enter the general blood circulation. The epidermis‐associated amount of phthalocyanine was sufficient to cause an important cutaneous damage upon irradiation with red light (600–700 nm; 100–180 mW/cm2, 160 J/cm2); the latter was confined to the epidermal area with no apparent diffusion to the underlying dermal layers or appearance of photosensitivity in distal skin areas. A systematic investigation of the interplay among the different parameters (deposition time of the formulated phthalocyanine on mouse skin, irradiation fluence rate and total light fluence) allowed us to identify the minimal phototoxic dose, as well as to define irradiation protocols allowing the repeatability of the phototherapeutic treatment. The potential of RLP068 to act as a PDT agent for cutaneous diseases is briefly discussed.
The relation between the moisture‐release curve and the structure of soil
Authors: CRAWFORD J.W. , MATSUI N. , YOUNG I.M.
Published: August 2005

The limit to the precision with which moisture‐release data may be related to soil structure is examined. Thin sections in two orthogonal planes were prepared from cores for which moisture release data and saturated conductivity measurements were also collected. Structural parameters are inferred indirectly through estimation of the mass fractal dimension from the moisture‐release curve, and directly through measurement of the scaling properties of the pore space and solid matrix from the thin sections using image analysis. Theoretical results are presented which show that, in the absence of additional information, the interpretation of the moisture‐release curve is ambiguous for several reasons. A power‐law exponent is a consequence of either a fractal pore volume; a fractal solid volume; a fractal pore wall; or a non‐fractal, self‐similar pore wall, and one cannot infer from the measurement which is the case. Experimental results are presented which confirm that direct measurement of the fractal dimension of the solid matrix is a good predictor of the Brooks–Corey exponent for the soils studied here. Therefore, although a specific structural parameter characterizes the moisture‐release curve, the latter cannot be used as a detailed measure of soil structure.
Humic acid–proton equilibria: A comparison of two models and assessment of titration error
Authors: MARSHALL S.J. , YOUNG S.D. , GREGSON K.
Published: August 2005

Charge development curves, obtained by potentiometric titration of ten soil–derived humic acids, are described using two modelling approaches: a simple electrostatic model with limited functional group heterogeneity (model A), and an implementation of an alternative from the literature, model V, incorporating up to 12 functional group types. Both models provide excellent descriptions of charge dependence on pH and ionic strength. However, for model A, 11 fitted parameters were required to describe the data across the full range of ionic strength (0.01–3.0), compared with seven for model V. Although model A required more parameters, it was conceptually simpler than model V, requiring only two functional group types, which may have advantages in describing the formation of metal complexes.

Error in the determination of humic charge from titration data was shown to increase markedly for data obtained at pH<3. The apparently anomalous trends in humic charge at low pH reported in the literature are explained in terms of this error.

Investigation of the kinetics of protonation and deprotonation reactions of humic acids suggested that titration hysteresis was the result of dis–equilibrium, especially at high pH. The use of a 7‐day batch titration technique, instead of continuous titration apparently eliminated hysteresis from the data.
Phosphorus forms in a sandy soil (Torripsamment) under palm orchards of different age in Saudi Arabia
Authors: HEAKAL M.S. , AL‐AWAJY M.H. , AL‐SEWAILEM M.S. , BARAKAH F.N. , AL‐ASHEIKH A.
Published: August 2005

Flood irrigated date‐palm orchards annually manured for 10 (=U10), 50 (=U50, 110 (=U110) and 230 (U230) years together with a barren site in a nearby desert (=U0) all on sandy soils, were analysed for total P (TP), organic P (OP), inorganic P extracted by 0.5mH2SO4(Ca‐P), inorganic P not extracted by 0.5mH2SO4(NP), total N (TN) and organic C (TC). Watering resulted in continuing CaCO3accumulation in the soils. TC and TN to 160 cm depth increased rapidly over the first 50 years (120 g C m−2a−1and 9.7 g N m−2a−1), then the increases slowed. In contrast, TP continued to accumulate steadily (4.8 g P m−2a−1). AtU0, TP to 160 cm depth was very small (= 88 mg kg−1) and dominated by Ca‐P with OP as a minor component. AtU10, OP and Ca‐P were in equal proportions. The latter acquired increasing dominance with increasing period of treatment whereas OP reached a steady state. NP increased at a rate which decreased with time. It is likely that most of OP compounds have been leached down the profile where mineralization and subsequent immobilization, probably by Ca2+ions from irrigation waters, have occurred.
Evidence for microbial decomposition of organic acids during podzolization
Authors: LUNDSTRÖM U.S. , VAN BREEMEN N. , JONGMANS A.G.
Published: August 2005

Microbial aspects of podzolization were studied by percolating organic acids through sterile and non‐sterile soil in columns. Six columns containing sand from a fluvioglacial sediment were percolated (90 mm d−1) with mor extract and an oxalate‐citrate solution. In three of these, sterilized soil solutions were used. Weathering was enhanced by organic acids which formed complexes with aluminium and iron. In the non‐sterile soil columns weathering by organic acids was inhibited at 7–8 cm because the acids were degraded by microorganisms. Weathering was evident from colour change, contents of extractable aluminium and iron, and the micromorphology. Enhanced weathering in the sterile columns was also suggested by larger amounts of aluminium, iron, silica and base cations leached from the columns. Comparison of the output of aluminium, iron and silica from the sterile soil with that from the non‐sterile soil, suggests that probably an aluminium‐iron‐silicate phase was formed in the deeper parts of the non‐sterile columns.
Nitrous oxide fluxes from grassland in the Netherlands: I. Statistical analysis of flux‐chamber measurements
Authors: VELTHOF G.L. , OENEMA O.
Published: August 2005

Accurate estimates of total nitrous oxide (N2O) losses from grasslands derived from flux‐chamber measurements are hampered by the large spatial and temporal variability of N2O fluxes from these sites. In this study, four methods for the calculation of mean N2O fluxes (n= 6) on total N2O losses are compared, namely the arithmetic mean, the geometric mean, the lognormal mean and the mean derived from Finney's method. Mean fluxes were calculated from weekly flux measurements on grassland at four contrasting sites in the Netherlands with three management treatments each. Total losses were calculated by interpolation of the mean fluxes and integration over time. Spatial variation of N2O fluxes was large. The geometric mean was generally much smaller, up to a factor of 7, than the arithmetic mean. The lognormal mean was much larger, up to a factor of 11, than the arithmetic mean, possibly because this estimator is biased for small sample size. Arithmetic means and Finney's method were generally in reasonable agreement. The order in estimated N2O loss increased in the order geometric mean<arithmetic mean≤Finney's mean<lognormal mean. Because of the small sample size (n =6), the uncertainty about the precise frequency distribution, the sensitivity of estimators based on logtransformed data, and the problems associated with negative fluxes, the arithmetic mean was preferred as the most appropriate estimator. Evidently, the choice of an estimator of the mean can have great effects on the estimation of total N2O losses.
Effects of organic and inorganic calcium compounds on soil‐solution pH and aluminium concentration
Authors: SMITH C. J. , GOH K. M. , BOND W. J. , FRENEY J. R.
Published: August 2005

The reactions of two organic (citrate and fulvate) and two inorganic (chloride and phosphogypsum) calcium compounds were studied during leaching of columns of unsaturated acidic soil. The potential of these compounds to decrease the aluminium concentration in the soil solution and remove exchangeable aluminium, and their effects on soil acidity are described.

The calcium citrate solution increased the soil solution pH from 5 to a maximum value of 7 in the upper portion of the column. In contrast, the fulvate, calcium chloride and phosphogypsum solutions had little effect on soil‐solution pH. Treatment with calcium citrate, or fulvate solution that contained 51 mm Na, removed most of the exchangeable aluminium from the column. The cation exchange sites in the upper portion of the column were saturated with calcium, and the cation exchange capacity of the soil was increased from 35 to c. 80 mmolc kg−1 in the calcium citrate treatment. Leachate from this treatment contained low (< 2 mm) calcium concentrations and high aluminium concentrations. In contrast, the above changes were not shown by the calcium chloride and phosphogypsum treatments. In these treatments the calcium concentration in the leachate was equal to that in the inflowing solution, which indicated that calcium was transported through the entire column. These results suggest that calcium alone was ineffective in displacing aluminium from the cation exchange sites and a strong complexing agent such as citrate or fulvate is needed to mobilize the exchangeable aluminium.
Theoretical analyses of interactions between inorganic nitrogen and soil organic matter
Authors: BOSATTA E. , ÅGREN G.I.
Published: August 2005

The organic matter of the soil has a large potential to retain inorganic nitrogen by means of both biotic (microbially mediated) and abiotic (chemical) reactions. We derive one equation with which we analyse the nitrogen retention due to these mechanisms in terms of organic matter properties. We first of all show how to separate gross mineralization from immobilization. We then show that our equation can reproduce studies of microbially–mediated or purely inorganic immobilization. We then apply the theory to soils of different characteristics (typical agricultural and forest soils) and find that the major factor determining the fraction of added inorganic nitrogen that is immobilized is the ratio between soil carbon and inorganic nitrogen concentration.
Decomposition of15N‐labelled catch‐crop residues in soil: evaluation of N mineralization and plant‐N uptake potentials under controlled conditions
Authors: NICOLARDOT B. , DENYS D. , LAGACHERIE B. , CHENEBY D. , MARIOTTI M.
Published: August 2005

The decomposition of15N‐labelled catch‐crop materials (rape, radish and rye), obtained from field experiments, was studied in a chalky Champagne soil during a 60‐week incubation at 28°C. Mineralized N was assumed to come from either labile or recalcitrant fractions of plant residues. The labile fraction represented about one‐third of the catch‐crop N; its mineralization rate constant varied from 0.06 to 0.12 d−1. The decomposition rate of the recalcitrant N fraction ranged from 0.03 × 10−2to 0.06 × 10−2d−1. Catch‐crop species and rate of incorporation had no effect on N residue mineralized at the end of incubation.

The decomposition of labelled rye was monitored in the same soil during a 5‐month pot experiment to determine the N availability to an Italian ryegrass crop and the effect of plants on the decomposition processes. The15N‐rye decomposed rapidly both in the presence or absence of Italian ryegrass, but the amounts of N mineralized were influenced by the presence of living roots: 42% of the15N in labelled rye was present as inorganic N in the pots without plants after 5 months, compared with only 32% in the ryegrass crop. Comparison of microbial‐biomass dynamics in both treatments suggested that there had been preferential utilization by soil micro‐organisms of materials released from the living roots than the labelled plant residues.
Solubility characteristics of proto‐imogolite sols: how silicic acid can de‐toxify aluminium solutions
Authors: LUMSDON D.G. , FARMER V.C.
Published: August 2005

Proto‐imogolite sols can be considered as highly dispersed forms of proto‐imogolite allophane, the most widespread type of allophane in volcanic and non‐volcanic soils world‐wide. The solubility characteristics of such sols define the conditions of precipitation of allophanes in soils, and the maximum concentrations of aluminium released during acidic episodes from soils, such as podzols, that contain allophane. Direct measurement of Al, Si and pH values in equilibrium with proto‐imogolite sols, approached from higher and lower pH, indicated a solubility equation:
image

where log*Kso lay in the range 7.14 to 7.23 after equilibration for 4–24 weeks at 22 + 2°C in 17 of the 20 systems studied. The mean value of log *KSO at 298 K was calculated as 7.02. This value indicates that proto‐imogolite will be more stable than amorphous aluminium hydroxides at H4SiO4 concentrations above 5 × 10−6m, but less stable than bayerite below 10−3m H4SiO4, and than gibbsite below 10−2m. Proto‐imogolite is more stable than micro‐crystalline gibbsite in 10−4m H4SiO4, a typical minimum concentration in soil solutions and streams in landscapes where podzols are present. The rapid formation of proto‐imogolite effectively prevents the formation of gibbsite seeds in soil, except in highly leached and warm environments, i.e. in older landscapes in the tropics.

Although the presence of 10−4m silicic acid has been found to eliminate the acute toxicity to fish exhibited by solutions containing 6–7 μm Al at pH 4.96, little or no proto‐imogolite would form under these conditions. Silicic acid would, however, prevent the precipitation of aluminium hydroxides, and could inhibit the formation of the A113 polycation. These polymeric species are a likely cause of the increased toxicity exhibited by partially neutralized aluminium solutions.
Partitioning of polycyclic aromatic hydrocarbons (PAH) to water‐soluble soil organic matter
Authors: MAXIN C.R. , KÖGEL‐KNABNER I.
Published: August 2005

The mobility of polycyclic aromatic hydrocarbons (PAH) in soils can be influenced by the presence of dissolved organic matter. Partition coefficients of selected polycyclic aromatic hydrocarbons, ranging from 3‐ring to 6‐ring compounds, to water‐soluble soil organic matter (WSSOM) were determined. Partition coefficients were determined for WSSOM obtained from two soils under agricultural use and forest and for commercially available humic acid (Aldrich), taking advantage of a reversed phase (C18) separation method. The WSSOM was characterised with regard to charge and hydrophilic/hydrophobic properties with a dissolved organic matter (DOM) fractionation method. No sorption to WSSOM was found for the tri‐ and tetracyclic PAH, whereas the penta‐ and hexacyclic PAH showed a significant binding to both types of WSSOM and to Aldrich humic acid. The affinity of penta‐ and hexacyclic PAH to WSSOM was considerably lower compared to the affinity to Aldrich humic acid. This is suggested to be due to the lower amount of hydrophobic fractions, c. 30%, in the natural WSSOM as compared to Aldrich humic acid. Effective partition coefficients (Koceff) for the sorption of PAH to bulk soil calculated from KDOC and DOM in the naturally occurring concentration range were only 60–70% of the Koc values in pure water. The impact of DOM on pollutant transport is further influenced by non‐equilibrium behaviour of PAH in soils and by sorption of DOM to the solid‐soil matrix. Several scenarios are described in which the effect of DOM on pollutant transport may become important.