bluuebunny/crossref_metadata_2025 huggingface dataset:
Syntheses, Structure and Magnetic Properties of the First µ1,5‐Dicyanamido‐Bridged Dinuclear Compounds [Ni(µ1,5‐dca)(dca)(dpt)]2 and [Ni(µ1,5‐dca)(dca)(medpt)]2
Authors: Ghoshal Debajyoti , Bialas Hanna , Escuer Albert , Font‐Bardía Mercé , Maji Tapas Kumar , Ribas Joan , Solans Xavier , Vicente Ramon , Zangrando Ennio , Chaudhuri Nirmalendu Ray
Published: October 2003

The first structural determination of dinuclear compounds with μ1,5‐dicyanamide [dca, N(CN)2−] as bridging ligand has been achieved with the products of formula [Ni(µ1,5‐dca)(dca)(dpt)]2 (1) and [Ni(µ1,5‐dca)(dca)(medpt)]2 (2) [dpt = bis(3‐aminopropyl)amine and medpt = bis(3‐aminopropyl)methylamine]. The X‐ray diffraction analysis reveals dinuclear compounds with double μ1,5‐dicyanamide bridges. The nickel atoms are hexacoordinate. The small differences in the terminal ligand (dpt or medpt) create a drastic change in the magnetic behaviour: the susceptibility measurements of 1 show weak antiferromagnetic coupling (J = −1.2 cm−1, g = 2.29) whereas those of 2 show ferromagnetic coupling (J = 0.7 cm−1, g = 2.17). The related compound (μ‐terephthalato)[Ni(dca)(dpt)(H2O)]2 (3) is also described. The X‐ray diffraction analysis reveals a dinuclear terephthalato‐bridged NiII compound with terminal dca ligands. The susceptibility measurements of 3 indicate weak antiferromagnetic coupling: J = −0.3 cm−1, g = 2.13. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Conformational Studies of a Chiral Octadentate Ligand Derived from (R)‐1,1′‐Binaphthyl‐2,2′‐diamine and its Dinuclear Zinc(II) and Nickel(II) Complexes
Authors: Mimmi Maria Chiara , Gullotti Michele , Santagostini Laura , Pagliarin Roberto , De Gioia Luca , Monzani Enrico , Casella Luigi
Published: October 2003

The synthesis of the octadentate ligand (R)‐(−)‐N,N′‐dimethyl‐N,N′‐bis{3‐[bis(1‐methyl‐2‐benzimidazolylmethyl)]aminopropyl}‐1,1′‐binaphthyl‐2,2′‐diamine (L), containing a central 1,1′‐binaphthalenediamine core connected to two aminobis(benzimidazole) arms by flexible trimethylene carbon chains, and its dinuclear complexes [Zn2L](ClO4)4 and [Ni2L](ClO4)4 is reported. The structural features of the free ligand and the metal complexes have been investigated by NMR, UV/Visible, CD, and computational methods, including simulated annealing‐molecular mechanics and semiempirical PM3 calculations. The preferred conformation of the free ligand is characterized by a relatively small dihedral angle of about 75° between the two naphthyl rings, which is imposed by favorable stacking interactions between benzimidazole rings from different arms. In the dinuclear zinc(II) complex each metal ion is pseudotetrahedral and bound to three N donors of one aminobis(benzimidazole) arm and one N donor of the binaphthalenediamine residue. Coordination of the benzimidazole groups to the metal ions prevents the stacking interactions seen in the free ligand and, consequently, the dihedral angle between the naphthyl groups increases to the more usual ca. 90°. In the dinuclear nickel(II) complex, the ligand still provides four nitrogen donors to each metal centers, but the stereochemical preference of the nickel(II) ions imposes a ligand field of tetragonal symmetry, with pseudo‐octahedral metal centers, and this occurs with pronounced flattening of the dihedral angle between the naphthyl groups. The change in conformation, from L to [Zn2L]4+ to [Ni2L]4+, of the critical 1,1′‐binaphthalenediamine residue is clearly indicated by CD spectra. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Mono‐ and Dinuclear Complexes of a Flexible Schiff Base Ligand − Crystal Structures of a Bishelicate and Two Acentric Monohelicates
Authors: Sanmartín Jesús , García‐Deibe Ana M. , Bermejo Manuel R. , Novio Fernando , Navarro Debora , Fondo Matilde
Published: October 2003

Neutral NiII, PdII, CuII, AgI, ZnII, CdII, and PbII complexes of N,N′‐bis(2‐tosylaminobenzylidene)‐1,4‐diaminobutane (H2SB) have been prepared. The Schiff base seems to exist in a helically coiled state around nickel, copper and zinc ions, but not in Pd(SB)·3H2O·MeCN, Ag2(SB)·2H2O, Cd(SB)·3H2O, and Pb(SB)·3H2O, the metal ions of which seem to show planar geometries. The determination of the absolute structures of Cu(SB)·MeCN and Zn(SB)·2MeCN, which crystallise as non‐centrosymmetric racemic compounds, shows that these metal(II) ions assume distorted tetrahedral coordination geometries involving the four N atoms of the dianionic ligand. X‐ray structural characterisation also shows that this ligand behaves as a N2+N2 donor in the [4+4] bishelicate Ni2(SB)2·5MeCN. Secondary interactions between metal centres and one of the O atoms of each tosyl group are detected in these three crystal structures, being especially intense in the dimeric one. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Dioxomolybdenum(VI)‐Modified Mesoporous MCM‐41 and MCM‐48 Materials for the Catalytic Epoxidation of Olefins
Authors: Nunes Carla D. , Pillinger Martyn , Valente Anabela A. , Rocha João , Lopes André D. , Gonçalves Isabel S.
Published: October 2003

The dioxomolybdenum(VI) complex [MoO2Cl2(L‐L)], containing the bidentate 1,4‐diazabutadiene ligand RN=C(Ph)−C(Ph)=NR [R = (CH2)3Si(OEt)3], was immobilised in the ordered mesoporous silica MCM‐41 by carrying out a grafting reaction in dichloromethane. The grafted material (3.3 wt.‐% Mo) was tested as a catalyst for the epoxidation of cyclooctene with tert‐butyl hydroperoxide (TBHP) at 55 °C. Selectivity to the epoxide was very high and the observed kinetic profile was similar to that of the complex [MoO2Cl2(L‐L)] in the homogeneous phase. On recycling several times, some activity was lost from the first to second runs, but thereafter stabilised. Tethered complexes of this type were also prepared by a stepwise approach. The mesoporous silicas MCM‐41 and MCM‐48 were first treated with a toluene solution of the ligand L‐L under reflux. Before isolating the grafted materials, the silylating agent Me3SiCl was added to remove the residual Si−OH groups on the surface of the mesoporous materials. Oxomolybdenum species were subsequently introduced into the ligand‐silicas by pore volume impregnation of a solution of the complex [MoO2Cl2(THF)2] in CH2Cl2 at room temperature. The modified materials have been characterised by powder X‐ray diffraction, N2 adsorption, and solid‐state MAS NMR (13C, 29Si). Despite having lower metal loadings (1 wt.‐% Mo), the materials exhibited similar catalytic activities for the epoxidation of cyclooctene to that of the modified MCM‐41 with 3.3 wt.‐% of Mo. However, selectivities to the epoxide were lower. The MCM supported catalysts have also been tested for the epoxidation of cyclododecene and α‐pinene with TBHP. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Characterisation of New Nickel‐Iron Complexes with an S4 Coordination Environment around the Nickel Centre
Authors: Verhagen Johanna A. W. , Lutz Martin , Spek Anthony L. , Bouwman Elisabeth
Published: October 2003

The nickel complex [Ni(xbsms)] [H2xbsms is α,α′‐bis(4‐mercapto‐3,3‐dimethyl‐2‐thiabutyl)‐o‐xylene] was reacted with FeCl2, [Fe2(CO)9], [Fe(CO)2(NO)2] and [Fe(CO)4I2]. The reaction with FeCl2 gives the heterotetranuclear nickel−iron complex [Ni(xbsms)FeCl2]2. The complex was characterised by analytical, spectroscopic and electrochemical methods and by X‐ray diffraction. [Ni(xbsms)FeCl2]2 crystallises in the monoclinic space group P21/c, with the dimer located on the inversion centre. The nickel ions are in a square‐planar S2S′2 environment, comprised of two thioether and two thiolate sulfur atoms. The thiolate sulfur atoms form a bridge between the nickel ion and the iron centre. The iron ions are in a pseudo square‐pyramidal S2Cl3 environment, with two chloride ions forming a bridge between the two iron centres. The Ni−Fe distance is 3.0403(3) Å. The reaction with [Fe2(CO)9], [Fe(CO)2(NO)2] or [Fe(CO)4I2] gives the heterodinuclear complexes [Ni(xbsms)Fe(CO)4], [Ni(xbsms)Fe(NO)2] and [Ni(xbsms)Fe(CO)2I2], respectively. These complexes were characterised by analytical, spectroscopic and electrochemical methods. In [Ni(xbsms)Fe(CO)4], one thiolate group bridges the Ni and Fe centres, whereas in [Ni(xbsms)Fe(NO)2] and [Ni(xbsms)Fe(CO)2I2], two thiolate groups form a bridge between the centres. These newly synthesised nickel−iron complexes appear to be suitable complexes for new structural models for [NiFe]‐hydrogenases. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Lacunary Wells−Dawson Sandwich Complexes − Synthesis, Characterization, and Stability Studies of Multi‐Iron Species
Authors: Mbomekalle Israel Martyr , Keita Bineta , Nadjo Louis , Neiwert Wade A. , Zhang Lei , Hardcastle Kenneth I. , Hill Craig L. , Anderson Travis M.
Published: October 2003

Reaction of α‐Na12(As2W15O56) with FeII in 1 M NaCl solution followed by air oxidation yields αααα‐H2Na14[(NaOH2)2FeIII2(As2W15O56)2] (Na2), the arsenic analogue of the divacant lacunary sandwich, αααα‐H2Na14[(NaOH2)2FeIII2(P2W15O56)2] (Na1). This complex (Na2) consists of a Na2Fe2 central unit sandwiched between two B‐α‐As2W15O5612− moieties. Both Na1 and Na2 react with one equivalent of FeIII to give ααβα‐Na14[(NaOH2)(FeIIIOH2)(FeIII)2(X2W15O56)2], where X = P (Na3) or As (Na4), or two equivalents of MnII to give αββα‐Na14[(MnIIOH2)2(FeIII)2(X2W15O56)2], where X = P (Na5) or As (Na6). A single‐crystal X‐ray diffraction analysis of Na5 has been carried out [a = 13.5387(8) Å, b = 13.9327(9) Å, c = 21.3347(13) Å, α = 92.921(1) °, β = 94.367(1) °, γ = 118.154(1) °, triclinic, P$\bar 1$
, R1 = 5.49%, based on 24662 independent reflections], which revealed a Mn2Fe2 central unit sandwiched between two B‐α‐P2W15O5612− units. All of the new complexes have been characterized by FTIR spectroscopy, UV/Visible spectroscopy, elemental analyses, and cyclic voltammetry, and they are all stable for at least 24 h over a wide pH range (0−7), except for Na4, which is unstable below pH 2. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Impact of prefractionation using Gradiflow™ on two‐dimensional gel electrophoresis and protein identification by matrix assisted laser desorption/ionization‐time of flight‐mass spectrometry
Authors: Pang Lisa , Fryksdale Beth G. , Chow Nicole , Wong David L. , Gaertner Alfred L. , Miller Brian S.
Published: October 2003

Prefractionation of protein samples prior to two‐dimensional electrophoresis (2‐DE) has the potential to increase the dynamic detection range for proteomic analysis. We evaluated a membrane‐based electrophoretic separation technique (Gradiflow™) for its ability to fractionate an exoproteome sample from the filamentous fungus Trichoderma reesei. The sample was separated on the basis of size and charge. Buffer optimization was found to be necessary for successful size fractionation. Fractionation by charge was used to resolve the sample into four fractions that were subjected to analysis by two‐dimensional electrophoresis (2‐DE). Enhanced detection of low‐abundance proteins with selective removal of high‐abundance species was achieved. Fractionated and unfractionated samples were examined for differences in the ability to identify proteins following 2‐DE using trypsin in‐gel digestion followed by peptide mass fingerprinting using matrix assisted laser desorption/ionization‐time of flight‐mass spectrometry (MALDI‐TOF‐MS). Fractionated samples showed marked improvement in protein identification ability and sequence coverage. This study demonstrates the utility of the Gradiflow™ for fractionation, resulting in an enhancement of resolution and characterization of a moderately complex proteome.
Proteomic analysis of transducin β‐subunit structural heterogeneity
Authors: Clack James W. , Juhl Martha , Rice Carol A. , Li Junyu , Witzmann Frank A.
Published: October 2003

Partially purified transducin was resolved using two‐dimensional gel electrophoresis (2‐DE). Peptide mass fingerprinting of several different spots believed to correspond to the 37 kDa β‐subunit of transducin (Tβ) was performed. Spots were excised and proteolyzed using modified trypsin. Matrix‐assisted laser desorption/ionization‐mass spectrometry (MALDI‐MS) was performed on the peptide mixture resulting from each spot. As many as six spots with different pI, ranging from 5.2 to 6.1, were observed when separated using 2‐DE. MALDI peptide mass fingerprinting determined with high probability that all of the spots were the same gene product, guanine nucleotide‐binding protein GI/GS/GT β‐subunit 1 (GNB1; Tβ1). This suggested that post‐translational modification was responsible for the differences in pI. Phosphorylation experiments showed that at least one Tβ1 spot was phosphorylated in vitro with [γ‐32P]ATP by an endogenous kinase. Treatment of Tβ with alkaline phosphatase caused a large change in the spot pattern of Tβ, suggesting that phosphorylated Tβ is a substrate for alkaline phosphatase. We conclude that Tβ1 constitutes over 99% of the Tβ expressed in bovine rod outer segments and displays structural heterogeneity that is due to post‐translational modification. We also conclude that some, but not all, of the heterogeneity observed is due to phosphorylation of Tb1.
High‐resolution single‐stranded DNA analysis on 4.5 cm plastic electrophoretic microchannels
Authors: Shi Yining , Anderson Rolfe C.
Published: October 2003

Plastic microchannels (4.5 cm long) fabricated from an etched glass master were tested for high‐resolution single‐stranded DNA analysis. Using replaceable denaturing linear polyacrylamide as sieving matrix, one‐color separation of a fragment sizing standard with single‐base resolution (R > 0.5) was achieved up to 275 bases. Two‐color sizing analysis of four loci short tandem repeat (STR) allelic ladder (CSF1PO, TPOX, TH01, vWA) with single‐base resolution (R = 0.62) on TH01 alleles 9.3 (198 bp) and 10 (199 bp) was demonstrated. An average standard deviation of ± 0.06 bp and ±0.11  bp in sizing 32 alleles of the CTTv ladder was attained between runs and between channels, respectively. Four‐color sequencing separation of a terminator sequencing standard showed a base‐calling accuracy of 99.1% out to 320 bases in 13 min.
Microarray‐based resequencing by apyrase‐mediated allele‐specific extension
Authors: Ericsson Olle , Sivertsson Åsa , Lundeberg Joakim , Ahmadian Afshin
Published: October 2003

We have developed an array‐based resequencing method to determine genetic alterations in putative cancer genes. The method relies on that the specificity of DNA polymerase in allele‐specific extensions can be enhanced by terminating the extension reactions with apyrase and that a tiling set of primers are synthesized covering the investigated gene sequence. We report on such apyrase‐mediated allele‐specific primer extension (AMASE) assay as a method suitable for high‐throughout resequencing and mutation detection in tumor suppressor genes and oncogenes. In the experimental setup, primers complementary to codons 12, 13 and codon 61 of the N‐ras proto‐oncogene were spotted onto glass slides. Overlapping sense and anti‐sense primers were designed so that complementary primers for all possible mutations in each base position were investigated. The extension reactions were performed in a single step following hybridization of target DNA to the immobilized primers on the array surface. Mutation detection limits and the possibility of quantifying the mutations were investigated using synthetic oligonucleotides. In addition, 64 clinical samples were sequenced and 16 of these showed mutations in the N‐ras gene.
Rice proteomics: Current status and future perspectives
Authors: Rakwal Randeep , Agrawal Ganesh Kumar
Published: October 2003

Rice, the first cereal crop genome to be decoded, has attracted the attention of researchers worldwide because of its immense socio‐economic impact on human existence. With the availability of the draft genome sequence of two major types, japonica‐ and indica‐rice, “rice proteomics” has entered into the era of functional genomics. Although during the last decade an important but limited progress (mainly construction of protein datafiles) has been made in the field of rice proteomics, it is only recently that dedicated research groups have taken this challenge to systematically analyze the rice proteome at the cell (and organelle), tissue, and whole plant level. Important gains achieved by the accelerated technological progress in protein separation and identification will help in going beyond the simple cataloguing of rice proteins in realistic terms. In this review, we discuss the progress made in the field of rice proteomics to date and dwell upon the future direction/problems/approaches towards defining the rice proteome.
Detection of metals in proteins by means of polyacrylamide gel electrophoresis and laser ablation‐inductively coupled plasma‐mass spectrometry: Application to selenium
Authors: Chéry Cyrille C. , Günther Detlef , Cornelis Rita , Vanhaecke Frank , Moens Luc
Published: October 2003

The capabilities of laser ablation‐inductively coupled plasma‐mass spectrometry for the detection of trace elements in a gel after gel electrophoresis were systematically studied. Figures of merit, such as limit of detection, linearity, and repeatability, were evaluated for various elements (Li, V, Cr, Mn, Ni, Cu, Zn, As, Se, Mo, Pd, Ag, Cd, Pt, Tl, Pb). Two ablation strategies were followed: single hole drilling, relevant for ablation of spots after two‐dimensional (2‐D) separations, and ablation with translation, i.e., on a line, relevant for one‐dimensional (1‐D) separations. This technique was applied to the detection of selenoproteins in red blood cells extracts after a 1‐D separation (sodium dodecyl sulfate‐polyacrylamide gel electrophoresis) and the detection of selenium‐containing proteins in yeast after 2‐D electrophoresis (2‐DE). The detection procedure was further improved by using the dynamic reaction cell technology, which allowed the removal of the Ar_2+ interference and hence the use of the most abundant Se isotope, 80Se. Reaction gases were compared (methane, carbon monoxide, ammonia, oxygen and the combination of argon (collision gas) and hydrogen (reaction gas)). In each instance, the reaction cell parameters were optimized in order to obtain the lowest detection limit for Se (as 80Se+, 82Se+ or 77Se+; and as 80Se16O+, 82Se16O+ or 77Se16O+ with O2 as the reaction gas). Carbon monoxide was found to offer the best performance. The detection limit with the use of DRC and He as transport gas was 0.07 μg Se g−1 gel with single hole drilling and 0.15 μg Se g−1 gel for ablation with translation.
Comparative proteome analysis of culture supernatant proteins from virulent Mycobacterium tuberculosis H37Rv and attenuated M. bovis BCG Copenhagen
Authors: Mattow Jens , Schaible Ulrich E. , Schmidt Frank , Hagens Kristine , Siejak Frank , Brestrich Gordon , Haeselbarth Gisela , Müller Eva‐Christina , Jungblut Peter R. , Kaufmann Stefan H. E.
Published: October 2003

A comprehensive analysis of culture supernatant (CSN) proteins of Mycobacterium tuberculosis H37Rv was accomplished by combination of two‐dimensional electrophoresis (2‐DE), mass spectrometry, and N‐terminal sequencing by Edman degradation. Analytical 2‐DE gels resolved approximately 1250 protein spots from CSN of M. tuberculosis H37Rv, 381 of which were identified by mass spectrometry and/or Edman degradation. This study revealed 137 different proteins, 42 of which had previously been described as secreted. Comparative proteome analysis of CSN from virulent M. tuberculosis H37Rv and attenuated Mycobacterium bovis BCG Copenhagen identified 39 M. tuberculosis‐specific spots containing 27 different proteins, representing candidate antigens for novel vaccines and diagnostics in tuberculosis. These included five proteins encoded by open reading frames absent from M. bovis BCG, e.g., early secretory antigen target (Esat6), as well as 22 novel differential proteins, such as acetyl‐CoA C‐acetyltransferase (Rv0243) and two putative Esat6‐like proteins (Rv1198, Rv1793).
On‐column concentration and separation of double‐stranded DNA by gradient capillary electrophoresis
Authors: Kuo I‐Ting , Chiu Tai‐Chia , Chang Huan‐Tsung
Published: October 2003

We describe the separation of dsDNA by capillary electrophoresis in the presence of electroosmotic flow (EOF) using poly(ethylene oxide) (PEO). Using 1.0% PEO, the separation of DNA fragments with sizes ranging from 51 bp to 23 kbp has been achieved in less than 12 min, which is better than conventional methods (in the absence of EOF) in terms of speed and resolution. In order to concentrate and separate the DNA sample, gradient changes in the concentrations of PEO and ethidium bromide (EtBr) have been conducted. Different concentrations of PEO solutions are injected to the polyethylene tubes by pressure, where they enter the capillary by EOF. Because the large DNA fragments migrate faster towards the cathode end under counterflow conditions, the introduction sequence is from low to high concentrations of PEO solutions after sample injection. Using the gradient CE approach, the separations of the DNA sample injected at 30 cm height for times up to 120 s have been demonstrated. The linearity between injection time and peak height shows that the DNA fragments stacked during migration from the sample zone to PEO. We found that stacking efficiency is greater when the analysis was performed by simultaneously changing the PEO and EtBr concentration, compared to individual changes in PEO concentration.
Highly sensitive and simple fluorescence staining of proteins in sodium dodecyl sulfate‐polyacrylamide‐based gels by using hydrophobic tail‐mediated enhancement of fluorescein luminescence
Authors: Kang Chulhun , Kim Hyun Jung , Kang Donghoon , Jung Duk Young , Suh Myungkoo
Published: October 2003

Fluorescein has an extremely low luminescence intensity in acidic aqueous media. However, when it was bound to proteins, subsequent increase of luminescence intensity took place. Furthermore, when a hydrophobic tail, such as aliphatic hydrocarbons, was introduced to fluorescein, more dramatic increase of luminescence intensity was observed upon binding to proteins. In the present study, by utilizing this luminescence enhancement, three hydrophobic fluorescein dyes (5‐dodecanoyl amino fluorescein, 5‐hexadecanoyl amino fluorescein, and 5‐octadecanoyl amino fluorescein) were examined as noncovalent fluorescent stains of protein bands in sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). Effective incorporation of the dyes to proteins in gels was accomplished either simply by adding dyes at the protein fixation step, or by treating gels with a staining solution after the fixation. The sensitivity of this staining method using the fluorescein derivatives was approximately 1 ng/band for most proteins. For some cases, protein bands containing as low as 0.1 ng were successfully visualized. In addition, the detection sensitivity showed much less protein‐to‐protein variation than silver staining. This new staining method was also successfully applied to two‐dimensional electrophoresis of rat brain proteins. Its overall sensitivity was comparable to that of silver staining.
Electrophoretic dynamics of large DNA stars in polymer solutions and gels
Authors: Heuer Daniel M. , Saha Sourav , Archer Lynden A.
Published: October 2003

We have developed a procedure for synthesizing large stable branched DNA structures that enables visualization via fluorescence microscopy. Using this procedure we have synthesized large DNA stars and observed their electrophoretic behavior in polymer solutions and gels. In dilute polyacrylamide solutions, the DNA stars move as random coils and appear to experience only brief collisions with the polymer chains in solution. The effect of polymer solution concentration on the electrophoretic mobility of stars in the dilute regime is found to be in good accord with predictions of the transient entanglement coupling (TEC) model. In semidilute polymer solutions, the star arms extend in the field direction and drag the core through the matrix. The star arms form several U‐shaped conformations as they collide and engage with polyacrylamide chains. The U‐shaped conformations occasionally evolve into J‐shaped conformations as the star arms slide off the matrix chains they engage during electrophoretic migration. In concentrated polymer solutions, the arms of the star extend and form V‐shaped structures with the core as the apex. The arms then pull the core through the matrix. These V‐shaped conformations are much longer‐lived than U‐shaped ones and, unlike the latter, do not transform to J‐shaped conformations. In polyacrylamide and agarose gels, where matrix entanglements are fixed, DNA stars become trapped when entanglements with matrix molecules prevent the core from being pulled through the matrix by the extended arms. This trapping was observed at all gel concentrations and electric fields studied.
Proteomics of loosely bound cell wall proteins of Arabidopsis thaliana cell suspension cultures: A critical analysis
Authors: Borderies Gisèle , Jamet Elisabeth , Lafitte Claude , Rossignol Michel , Jauneau Alain , Boudart Georges , Monsarrat Bernard , Esquerré‐Tugayé Marie‐Thérèse , Boudet Alain , Pont‐Lezica Rafael
Published: October 2003

The complete sequencing of the Arabidopsis thaliana genome allows the use of the recently developed mass spectrometry techniques to identify the cell wall proteins (CWPs). Most proteomic approaches depend on the quality of sample preparation. Extraction of CWPs is particularly complex since the proteins may be free in the apoplast or are embedded in a polysaccharide matrix where they are retained by Van der Waals interactions, hydrogen bonds, hydrophobic or ionic interactions, or cross‐linked by covalent bonds. Specific and sequential extraction procedures thus need to be developed. We report on the sequential extraction of loosely bound CWPs from living A. thaliana cells in culture. Different salts and chelating agents were used for releasing the proteins from the wall. Their effects on the extraction of CWPs and on the integrity of the plasma membrane were evaluated. Bioinformatic software was used to identify proteins and to predict their sub‐cellular localization. The obtained data show that the plasma membrane of cells in culture was easily damaged by some steps of the extraction procedure, leading to the release of increasing amounts of intracellular proteins. Nevertheless, we identified fifty CWPs among which thirteen were new proteins for the cell wall. In addition, 76% of these CWPs were basic proteins not resolved in two‐dimensional (2‐D) gel electrophoresis. The existence of two hypothetical proteins was confirmed. The structure of three proteins could be confirmed using mass spectrometry data.
Thousandfold signal increase using field‐amplified sample stacking for on‐chip electrophoresis
Authors: Jung Byoungsok , Bharadwaj Rajiv , Santiago Juan G.
Published: October 2003

Field‐amplified sample stacking (FASS) leverages conductivity gradients between a volume of injected sample and the background buffer to increase sample concentration. A major challenge in applying FASS to on‐chip assays is the initial setup of high‐conductivity gradient boundaries in the region of the injected sample volume. We have designed, fabricated, and characterized a novel FASS‐capillary electrophoresis (CE) chip design that uses a photoinitiated porous polymer structure to facilitate sample injection and flow control for high‐gradient FASS. This polymer structure provides a region of high flow resistance that allows the electromigration of sample ions. We have demonstrated an electropherogram signal increase by a factor of 1100 in electrophoretic separations of fluorescein and Bodipy with, respectively, 2 μM and 1 μM initial concentrations.
Sequence‐dependent bending in plasmid pUC19
Authors: Stellwagen Nancy C.
Published: October 2003

The circular permutation assay has been used to characterize sequence‐dependent bending in plasmid pUC19 (2686 bp). Linear, permuted sequence isomers of pUC19 exhibit different mobilities in large‐pore polyacrylamide gels, suggesting that the plasmid contains two sequence‐dependent bends, one located at ∼ 806 bp, close to the start site of transcription, and the other at ∼ 2617 bp, near the promoter of the ampicillin resistance gene. The mobility patterns are independent of the buffer in which the gels are cast and run, independent of pH over the range 6.5–8.6, and independent of the presence or absence of various monovalent ions added to the buffer, suggesting that the maxima in the mobility patterns correspond to stable bends in the helix backbone, not anisometric flexibility. Although the mobility patterns are unchanged when Ba++ or Zn++ ions are added to the buffer, several of the sequence isomers exhibit multiple sharp sub‐bands in solutions containing Mg++ or Ca++ ions, indicating the presence of multiple conformational isomers. In addition, the mobility maximum near the start site of transcription is shifted by ∼ 100 bp in the presence of Ca++ ions, suggesting that the location of the actual bend center is somewhat variable, depending on the ionic composition of the surrounding medium. The number of maxima observed in the mobility pattern can be increased by adding a bend from another plasmid, such as Litmus 28; the number of maxima can be decreased by removing one of the bends in pUC19 by restriction enzyme digestion and religation. Hence, the number of maxima in the mobility pattern is an accurate indication of the number of stable, sequence‐dependent bends present in the plasmid. The combined results indicate that the circular permutation assay in large‐pore polyacrylamide gels is a reliable method of detecting and analyzing sequence‐dependent bends in kilobase‐sized DNA molecules.
Quantitative and qualitative measure of intralaboratory two‐dimensional protein gel reproducibility and the effects of sample preparation, sample load, and image analysis
Authors: Choe Leila H. , Lee Kelvin H.
Published: October 2003

We investigate one approach to assess the quantitative variability in two‐dimensional gel electrophoresis (2‐DE) separations based on gel‐to‐gel variability, sample preparation variability, sample load differences, and the effect of automation on image analysis. We observe that 95% of spots present in three out of four replicate gels exhibit less than a 0.52 coefficient of variation (CV) in fluorescent stain intensity (% volume) for a single sample run on multiple gels. When four parallel sample preparations are performed, this value increases to 0.57. We do not observe any significant change in quantitative value for an increase or decrease in sample load of 30% when using appropriate image analysis variables. Increasing use of automation, while necessary in modern 2‐DE experiments, does change the observed level of quantitative and qualitative variability among replicate gels. The number of spots that change qualitatively for a single sample run in parallel varies from a CV = 0.03 for fully manual analysis to CV = 0.20 for a fully automated analysis. We present a systematic method by which a single laboratory can measure gel‐to‐gel variability using only three gel runs.
Longer‐term implications of responsiveness to ‘thin‐ideal’ television: support for a cumulative hypothesis of body image disturbance?
Authors: Hargreaves Duane , Tiggemann Marika
Published: October 2003

Brief exposure to thin‐ideal media images has been shown to have a small but consistent negative impact on women and girls' body dissatisfaction. The present study aimed to examine the consequence of these small changes in body dissatisfaction for the development of body image over time. A sample of 80 adolescents (mean age = 17.2 years) completed measures of body dissatisfaction, drive for thinness, and drive for muscularity. Two years earlier they had viewed either 20 appearance‐related television commercials (containing female thin ideals) or 20 non‐appearance commercials as part of an experimental study. For girls, initial body dissatisfaction change in response to viewing appearance commercials at time 1 predicted subsequent body dissatisfaction and drive for thinness 2 years later, above and beyond the variance predicted by initial body dissatisfaction. Similar results were observed for boys' drive for thinness but not for body dissatisfaction. Overall, these results are consistent with a cumulative hypothesis of media exposure and body image development. Copyright © 2003 John Wiley & Sons, Ltd and Eating Disorders Association.
Evaluation of adolescent body satisfaction and associated eating disorder pathology in two communities
Authors: Baranowksi Mandy J. , Jorga Jagoda , Djordjevic Ivana , Marinkovic Jelena , Hetherington Marion M.
Published: October 2003

Objective:

As Eastern European countries adopt Anglo‐American ideals of body size, it can be predicted that body dissatisfaction (a core feature of the eating disorders) will be similar to that observed in western cultures. The objective of the present investigation is to compare adolescent males and females in urban schools of two countries (Scotland and Yugoslavia) as part of an ongoing longitudinal study of BMI, body satisfaction, well‐being and eating pathology.

Method:

625 adolescents had their BMI recorded and completed a series of questionnaires measuring body satisfaction, depression, anxiety and eating pathology.

Results:

Significant differences emerged as a function of gender in both countries and as a function of country. Girls reported significantly higher levels of body dissatisfaction than boys and scored higher on measures of restrained eating. However, eating pathology, depression and anxiety were higher in the Scottish cohort in general, and in the Scottish girls in particular. Similarly, self‐esteem was lower in the Scottish cohort and was particularly low in the girls.

Discussion:

Overall, body dissatisfaction appears to be a normative experience despite normal weight status for girls in both countries. However, risk factors for developing eating disorders appear higher in the western cohort. Results from the longitudinal assessments will highlight whether this trend is maintained over time. Copyright © 2003 John Wiley & Sons, Ltd and Eating Disorders Association.
Measurement and data analysis methods for field‐scale wind erosion studies and model validation
Authors: Zobeck Ted M. , Sterk Geert , Funk Roger , Rajot Jean Louis , Stout John E. , Van Pelt R. Scott
Published: October 2003

Accurate and reliable methods of measuring windblown sediment are needed to conﬁrm, validate, and improve erosion models, assess the intensity of aeolian processes and related damage, determine the source of pollutants, and for other applications. This paper outlines important principles to consider in conducting ﬁeld‐scale wind erosion studies and proposes strategies of ﬁeld data collection for use in model validation and development. Detailed discussions include consideration of ﬁeld characteristics, sediment sampling, and meteorological stations. The ﬁeld shape used in ﬁeld‐scale wind erosion research is generally a matter of preference and in many studies may not have practical signiﬁcance. Maintaining a clear non‐erodible boundary is necessary to accurately determine erosion fetch distance. A ﬁeld length of about 300 m may be needed in many situations to approach transport capacity for saltation ﬂux in bare agricultural ﬁelds. Field surface conditions affect the wind proﬁle and other processes such as sediment emission, transport, and deposition and soil erodibility. Knowledge of the temporal variation in surface conditions is necessary to understand aeolian processes. Temporal soil properties that impact aeolian processes include surface roughness, dry aggregate size distribution, dry aggregate stability, and crust characteristics. Use of a portable 2 tall anemometer tower should be considered to quantify variability of friction velocity and aerodynamic roughness caused by surface conditions in ﬁeld‐scale studies. The types of samplers used for sampling aeolian sediment will vary depending upon the type of sediment to be measured. The Big Spring Number Eight (BSNE) and Modiﬁed Wilson and Cooke (MWAC) samplers appear to be the most popular for ﬁeld studies of saltation. Suspension ﬂux may be measured with commercially available instruments after modiﬁcations are made to ensure isokinetic conditions at high wind speeds. Meteorological measurements should include wind speed and direction, air temperature, solar radiation, relative humidity, rain amount, soil temperature and moisture. Careful consideration of the climatic, sediment, and soil surface characteristics observed in future ﬁeld‐scale wind erosion studies will ensure maximum use of the data collected. Copyright © 2003 John Wiley & Sons, Ltd.
Wind and water erosion and transport in semi‐arid shrubland, grassland and forest ecosystems: quantifying dominance of horizontal wind‐driven transport
Authors: Breshears David D. , Whicker Jeffrey J. , Johansen Mathew P. , Pinder John E.
Published: October 2003

Soil erosion is an important process in dryland ecosystems, yet measurements and comparisons of wind and water erosion within and among such ecosystems are lacking. Here we compare wind erosion and transport ﬁeld measurements with water erosion and transport from rainfall‐simulation for three different semi‐arid ecosystems: a shrubland near Carlsbad, New Mexico; a grassland near Denver, Colorado; and a forest near Los Alamos, New Mexico. In addition to comparing erosion loss from an area, we propose a framework for comparing horizontal mass transport of wind‐ and water‐driven materials as a metric for local soil redistribution. Median erosion rates from wind for vertical mass ﬂux measurements (g m−2 d−1) were 1·5 × 10−2 for the shrubland, 8·3 × 10−3 for the grassland, and 9·1 × 10−3 for the forest. Wind‐driven transport from horizontal mass ﬂux measurements was greatest in the shrubland (15·0 g m−2 d−1) followed by the grassland (1·5 g m−2 d−1) and the forest sites (0·17 g m−2 d−1). Annual projections accounting for longer‐term site meteorology suggest that wind erosion exceeds water erosion at the shrubland by c. 33 times and by c. ﬁve times at the forest, but not the grassland site, where the high clay content of the soils contributed to greater amounts of water erosion: water erosion exceeded wind erosion by about three times. Horizontal transport by wind was greater than that by water for all three systems, overwhelmingly so in the shrubland (factor of c. 2200). Our results, which include some of the only wind erosion measurements to date for semi‐arid grasslands and forests, provide a basis for hypothesizing trends in wind and water erosion among ecosystems, highlight the importance of wind erosion and transport in semi‐arid ecosystems, and have implications for land surface geomorphology, contaminant transport, and ecosystem biogeochemistry. Copyright © 2003 John Wiley & Sons, Ltd.
Accurate water delivery using a simplified automated farm turnout
Authors: Stringam Blair L. , Sauer Brian W. , Pugh Clifford A.
Published: October 2003

A simplified automated farm turnout was designed to maintain constant turnout flowrates from canal delivery systems to individual farm fields. Off‐the‐shelf components were combined to fabricate this device. The cost of all the components totaled less than $2300. All of these components work together to maintain turnout flowrates to the specified amount plus or minus 3% error. These turnouts are recommended for canal systems where the canal levels typically fluctuate throughout the day. Four of these automated turnouts have been installed; three on farms near Boise, Idaho, and one in Yuma, Arizona. Copyright © 2003 John Wiley & Sons, Ltd.
A Markov chain simulation model for predicting critical wet and dry spells in Kenya: analysing rainfall events in the Kano Plains
Authors: Ochola W. O. , Kerkides P.
Published: October 2003

The occurrence of wet and dry spells is a phenomenon most often used to identify the arid and semi‐arid lands (ASAL) in Kenya. The use of first‐order Markov processes that are embedded into a computer model to determine the critical climate extremes is presented. The model uses the concepts of conditional probability, Poisson probability distribution function and chi‐square testing to predict the critical spells. The daily rainfall data (1981–2000) for two weather stations in the Kano Plains (Kenya) have been used to illustrate model application. For example, based upon the bimodal rainfall pattern in the study area, the model revealed the length of the critical dry spell to be 14 days in the long rainy season and 12 days in the short rainy season, while the critical wet spell was found to be 12 and 8 days, for the long and short rains respectively for Ahero Irrigation Scheme. It is recommended that a climate and environmental audit in the Kano Plains for the determination of land and water management strategies include critical dry and wet spell determination. This will enhance more sustainable planning and utilization of the crucial water and land resources in the region and in other tropical rangelands. There are possibilities of integrating the model with other agro‐ecosystems models and other natural resource management decision support systems. Copyright © 2003 John Wiley & Sons, Ltd.
Farm water and soil management for improved water use in the North China Plain
Authors: Pereira L. S. , Cai L. G. , Hann M. J.
Published: October 2003

The rapid development of industry and urban areas, population growth and rising living standards have all resulted in an increased water demand for non‐agricultural uses in the North China Plain, therefore decreasing the water availability for irrigation. Technologies that favour a reduced demand and water‐saving practices in irrigation are required to assure the sustainability of water use in agricultural production. This paper presents main research results relative to the integration of water and soil management technologies which may contribute to improving the use of water and land in agricultural production, reducing demand for irrigation, and more efficient use of groundwater. Improved estimates of crop irrigation requirements, better irrigation scheduling for the winter wheat crop and improved surface irrigation systems, result in water saving corresponding to about 100 mm in very dry years and up to 250 mm in average years with a small yield increase. These savings represent 16–33% of water use during the wheat crop season. Improvements in soil management lead to improved soil fertility and physical properties (including hydraulic conductivity). These improvements produce potential increases in summer maize yields of between 10 and 20%. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of osteogenic protein‐1 (OP‐1, BMP‐7) on gene expression in cultured medial collateral ligament cells
Authors: Tsai Alicia D. , Yeh Lee‐Chuan C. , Lee John C.
Published: October 2003

Osteogenic protein‐1 (OP‐1, also called BMP‐7), a member of the BMP family and the TGF‐β superfamily, induces formation of new bone and cartilage, but also regulates a wide array of processes. In the present study, the expression of several characteristic biochemical markers of ligaments, such as Six1, Scleraxis, aggrecan, and type I collagen in primary cultures of adult rat medial collateral ligament (MCL) cells was determined. The effects of OP‐1 on cell proliferation and on gene expression were subsequently examined. OP‐1 stimulated cell proliferation, alkaline phosphatase (AP) activity, and the steady‐state mRNA levels of the transcription factor Runx2/Cbfa1 in a dose‐ and time‐dependent manner. The mRNA levels of type I collagen only increased slightly, but the activity of the cloned collagen promoter increased by 2‐fold in transiently transfected MCL cells. OP‐1 also stimulated aggrecan mRNA expression. The mRNA levels of Six1 and Scleraxis were not detectably altered by OP‐1. In control cultures, the steady‐state mRNA levels of ActR‐I, BMPR‐IA, BMPR‐IB, and BMPR‐II increased as a function of time in culture. The mRNA levels of BMP‐1 and ‐4 increased significantly after 12 days, but those of BMP‐2 and ‐6 did not change. The GDF‐1, ‐3, ‐5, ‐6, and ‐8 mRNA levels in the control cultures also increased as a function of time. OP‐1 treatment stimulated mRNA expression of BMPR‐IA and BMPR‐II, but had little effect on ActR‐I and BMPR‐IB mRNA expression. OP‐1 lowered the BMP‐1, ‐2, and ‐6 mRNA levels without changing the BMP‐4 mRNA level. OP‐1 treatment also reduced the mRNA levels of GDFs detected. In summary, the present study demonstrated that OP‐1 stimulated cell proliferation and mRNA expression of several biochemical markers in this ligament cell culture model and established the spatial and temporal appearance of several members of the TGF‐β superfamily. © 2003 Wiley‐Liss, Inc.
Strong induction of p73 protein in vivo coincides with the onset of apoptosis in rat liver after treatment with the hepatocarcinogen N‐nitrosomorpholine (NNM)
Authors: Tudzarova‐Trajkovska Slavica , Wȩsierska‐Ga̧dek Józefa
Published: October 2003

Treatment of rats with genotoxic hepatocarcinogens such as N‐nitrosomorpholine (NNM) causes severe hepatotoxicity associated with apoptosis of hepatocytes beginning after 12 h. Previously, we reported that after a single administration of high NNM dose p53 protein level increased in liver but not in testis and that the first wave of apoptosis preceded the induction of p53 indicating that apoptosis in liver was driven by a p53‐independent pathway. We now show a pronounced upregulation of p73 protein, a p53‐related gene product. The increase of p73 α and β occurred already 6 h after NNM administration and preceded the onset of apoptosis by 6 h. Very strong p73 signals appeared 20 and 40 h post‐treatment and persisted for a few days, whereas p53 was induced only transiently at 20 and 40 h post‐treatment. Immunohistochemical analysis revealed that unlike p53, p73 was detected in the nuclei of hepatocytes undergoing apoptosis. Following the upregulation of p73 levels, the products of several genes regulating DNA repair, e.g., GADD‐45 and p53R2 and mediating apoptosis such as apoptosis inducing factor (AIF) were rapidly induced, whereas transient elevation of MDM‐2 protein was delayed and coincided temporary with activation of p53 protein. Interestingly, NF‐κB another transcription factor responding to cellular stress was activated at 20 h after NNM administration and reached a maximum after an additional 20 h. Our data indicate that activated p73 protein may positively affect the induction and execution of apoptosis in response to genotoxic action of NNM. © 2003 Wiley‐Liss, Inc.