bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on semi‐conjugate direction methods for non‐symmetric systems
Authors: Dai Yu‐Hong , Yuan Jinyun
Published: June 2004

Some theoretical problems and implementation problems are studied here for the semi‐conjugate direction method established by Yuan, Golub, Plemmons and Cecilio (2002). The existence of semi‐conjugate directions is proved for almost all matrices except skew‐symmetric matrices. A new technique is proposed to overcome the breakdown problem appeared in the semi‐conjugate direction method. In the implementation of the semi‐conjugate direction method, the generation of the semi‐conjugate direction is very important and necessary, but very expensive. The technique of limited‐memory is introduced to economize the cost of the generation of the semi‐conjugate direction in the Yuan–Golub– Plemmons–Cecilio algorithm. Finally, some numerical experiments are given to confirm our theoretical results. Our results illustrate that the semi‐conjugate direction method is very nice alternative for solving non‐symmetric systems, and the limited‐memory left conjugate direction method is a good improvement of the left conjugate direction method. Copyright © 2004 John Wiley & Sons, Ltd.
The ecology of Neanderthals: preface
Authors: Burke A.
Published: June 2004

This Preface introduces a set of 13 papers that explore different aspects of our current understanding of the ecology of Neanderthal hominins. The papers derive from a session held at the 2002 ICAZ Conference, at Durham. Copyright © 2004 John Wiley & Sons, Ltd.
A matter of high resolution? The Eemian Interglacial (OIS 5e) in north‐central Europe and Middle Palaeolithic subsistence
Authors: Gaudzinski S.
Published: June 2004

The Eemian Interglacial in north‐central Europe describes a phase of ca. 10,000–11,000 years for which detailed palaeoenvironmental reconstruction is available. Hominid subsistence during this period is considered based on evidence from the German sites of Lehringen, Gröbern, Neumark‐Nord and Taubach. It is concluded that the overall subsistence strategies of the Neanderthals were directed towards highly efficient resource exploitation irrespective of the environmental context. Problems immanent to interpretations of Middle Palaeolithic hominid responses to the palaeoenvironment are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Subsistence behaviours in a Middle Palaeolithic site in Poland: the Raj Cave
Authors: Patou‐Mathis M.
Published: June 2004

This paper presents an overview of mammal remains from one of the most important Middle Palaeolithic archaeological sites in Poland: Raj cave. This site lies near Kielce. Archaeological materials in cultural layers 4 and 6 are described as belonging to the Charentian culture. The stratigraphic sequence in its entirety may have been deposited during the Wechsel Interpleniglacial, equivalent to isotopic stage 3. Layer 4 would correspond at best to an interstadial phase, and layer 6 to a stadial. The environment of layer 4 was mixed, consisting of prairie and woodland, and the climate was relatively temperate and humid. In layer 6, the forests retreated while the steppe increased, and the climate became cold and relatively dry. In the lower layer (4) cave bear (Ursus spelaeus) dominates carnivore remains. In the upper cultural layer (6), cave bear and cave hyena (Crocuta spelaea) are the best represented carnivore taxa. In layer 4, hunting appears diversified. On the other hand, in layer 6 hunting seems to be oriented towards acquisition of the horse, but reindeer and large bovids are also abundant. A large quantity of reindeer shed antlers were discovered in this layer; the role of humans as collectors has yet to be proven. Clear evidence of human modification of the bone surfaces is very rare; few cut marks are observed. Raj cave can be considered a seasonal camp, occupied from the end of spring to the beginning of autumn in the case of layer 6. Copyright © 2004 John Wiley & Sons, Ltd.
The Middle Palaeolithic and late Pleistocene Tasmania hunting behaviour: a reconsideration of the attributes of modern human behaviour
Authors: Cosgrove Richard , Pike‐Tay Anne
Published: June 2004

The murky biological status of Neanderthals has inspired many behavioural paradigms. We ask if it is possible to differentiate behavioural changes in an evolutionary sense (archaic to modern) from innovative/evolutionary changes in behaviour due to localised adaptations to changing environments. Our approach to Neanderthal ecology here is comparative. Both lithic and faunal analyses of Pleistocene Tasmanian sites dating back to 35,000 BP show patterns similar to Middle Palaeolithic Eurasia. Yet the anatomically modern humans who first populated Australia exhibited modern cultural behaviour by crossing from Southeast Asia to Greater Australia by boat and colonising every environmental zone on the continent by at least 35,000 BP. If the Tasmanian archaeological sequence parallels that of the Mousterian, then the earliest Aboriginal colonisers of Greater Australia were either archaic in a behavioural sense (a notion that does not fit with the available evidence), or the interpretation of what indicates archaic behaviour must be reassessed.

Results from dental growth‐increment analyses of large game from Franco‐Cantabrian Palaeolithic sites show shifts in human mobility and subsistence strategies. Compilation of control samples of teeth of recent animals (e.g. Cervus, Rangifer, Equus, Capreolus, Bos) of known age and date‐of‐death has been requisite to these growth‐increment studies. Here we apply skeletochronological analysis to Bennett's wallaby (Macropus rufogriseus) from Tasmania's earliest sites, presenting results of aging techniques of molar eruption and seasonal annuli growth. These suggest that hunting pressure was relatively low on wallaby populations and that hunters occupied these upland valleys principally between autumn and early spring. We expect these data to support more robust hypotheses of both mortality and seasonal hunting patterns of this principal macropod prey species, as well as consideration of the question of ‘archaic’ versus ‘modern’ ecological adaptations. Copyright © 2004 John Wiley & Sons, Ltd.
Eat what is there: hunting and gathering in the world of Neanderthals and their neighbours
Authors: Bar‐Yosef O.
Published: June 2004

The current state of our knowledge of Neanderthal hunting and gathering is reviewed, with particular emphasis on the ‘transition’ from the Middle to the Upper Palaeolithic. It is argued that the zooarchaeological data do not support any general change in strategy during this transition, and that Middle and Upper Palaeolithic hunting and gathering was largely determined by what was available seasonally in the local environment. Copyright © 2004 John Wiley & Sons, Ltd.
Women, the labor market, and the declining relative quality of teachers
Authors: Corcoran Sean P. , Evans William N. , Schwab Robert M.
Published: June 2004

School officials and policymakers have grown increasingly concerned about their ability to attract and retain talented teachers. A number of authors have shown that in recent years the brightest students—at least those with the highest verbal and math scores on standardized tests—are less likely to enter teaching. In addition, it is frequently claimed that the ability of schools to attract these top students has been steadily declining for years. There is, however, surprisingly little evidence measuring the extent to which this popular proposition is true. We have good reason to suspect that the quality of those entering teaching has fallen over time. Teaching has for years remained a predominately female profession; at the same time, the employment opportunities for talented women outside teaching have soared. In this paper, we combine data from five longitudinal surveys of high school graduates spanning the classes of 1957 to 1992 to examine how the propensity for talented women to enter teaching has changed over time. While the quality of the average new female teacher has fallen only slightly over this period, the likelihood that a female from the top of her high school class will eventually enter teaching has fallen dramatically. © 2004 by the Association for Public Policy Analysis and Management.
Alternative measures of economic success among TANF participants: Avoiding poverty, hardship, and dependence on public assistance
Authors: Cancian Maria , Meyer Daniel R.
Published: June 2004

Current debates about the success of TANF reforms have been obscured by the use of inconsistent indicators of success, as well as by measurement difficulties associated with alternative indicators. This paper considers conceptual and measurement issues associated with three different indicators of economic well‐being: independence from public assistance, having income above the poverty threshold, and freedom from material hardship. Survey and administrative data from a sample of TANF participants illustrate the sensitivity of conclusions to alternative ways of measuring each indicator. Also considered is the extent to which dependence, poverty, and hardship coincide, or capture important differences in outcomes. The principles underlying TANF reforms have implications for appropriate measures of economic well‐being, as the empirical importance of these implications demonstrates. © 2004 by the Association for Public Policy Analysis and Management.
Synthesis of block copolymers from PDMS macroinitiators
Authors: Peng Hui , Cheng Shiyuan , Feng Linxian , Fan Zhiqiang
Published: June 2004

The synthesis of polystyrene‐b‐polydimethylsiloxane‐b‐polystyrene (PSt‐b‐PDMS‐b‐PSt) copolymers is described. Commercially available difunctional PDMS containing vinylsilyl terminal species was reacted with hydrogen bromide resulting in the PDMS macroinitiators. The terminal alkyl bromide groups were then used as initiators for atom transfer radical polymerization (ATRP) to produce block copolymers. Using this technique, triblock copolymers consisting of a PDMS centre block and polystyrene terminal blocks were synthesized. ATRP of St from those macroinitiators showed linear increases in Mn with conversion, demonstrating the effectiveness of ATRP to synthesize a variety of inorganic/organic polymer hybrids. Copyright © 2004 Society of Chemical Industry
Quantitative proteome profiling during the fermentation process of pleiotropic Bacillus subtilis mutants
Authors: Antelmann Haike , Sapolsky Ron , Miller Brian , Ferrari Eugenio , Chotani Gopal , Weyler Walter , Gaertner Alfred , Hecker Michael
Published: June 2004

Using a combined quantitative proteomic and bioinformatic approach, we monitored the cytoplasmic proteome profile of the Gram‐positive bacterium Bacillus subtilis during a fermentation process in complex medium. Proteome signatures were applied to elucidate the physiological changes occurring in the gene expression profile during growth. Furthermore, we determined the significance level of quantitative proteome changes, identified relative to the threshold of scatter in replicated samples and developed a statistically rigorous method that allowed us to determine significant fold‐changes at 95% confidence between different proteomes. Different functional groups of proteins were clustered according to their pattern of significant expression changes. The largest group is induced by the exhaustion of glucose and the presence of alternative carbon and nitrogen sources. Furthermore, depletion of glucose caused the induction of the trichloroacetic acid (TCA) cycle enzymes and the downregulation of glycolytic enzymes. The onset of the transition phase may be provoked by amino acid starvation, resulting in the RelA‐dependent repression of proteins involved in the translation process and in the induction of amino acid biosynthetic pathways. Comparisons between the parental strain and two subtilisin‐hypersecreting strains revealed only small cytoplasmic differences in the main metabolic pathways. Instead, the overproduction of degradative enzymes in both of these mutants was reflected in the extracellular proteome.
Proteomic tools to characterize the protein fraction of Equidae milk
Authors: Miranda Guy , Mahé Marie‐Françoise , Leroux Christine , Martin Patrice
Published: June 2004

The principal components of the protein fraction in pony mare's milk have been successfully identified and partially characterized using proteomic tools. Skimmed pony mare's milk was fractionated by either reversed phase‐high‐performance liquid chromatography (RP‐HPLC) on a C4 column or a bi‐dimensional separation technique coupling RP‐HPLC in the first dimension and sodium dodecyl sulfate‐polyacrylamide electrophoresis (SDS‐PAGE) in the second dimension (two‐dimensional RP‐HPLC/SDS‐PAGE). The fractions thus obtained were analyzed by Edman N‐terminal microsequencing and mass determination, with or without tryptic digestion, on a matrix‐assisted laser desorption/ionization‐time of flight spectrometer. Based on the sequence and molecular mass information obtained, identifications were achieved through a protein database search using homology or pattern research algorithms. This methodological approach was shown to be rapid, efficient and reliable in identifying the principal proteins in pony mare's milk. κ‐, αs1‐, αs2‐, and β‐casein, lysozyme C, α‐lactalbumin and β‐lactoglobulin I and II were thus identified. αs1 and β‐caseins displayed polymorphic patterns, probably due to alternative splicing processes leading to casual exon skipping events involving exons 7 and 14 in αs1‐casein and exon 5 in β‐casein. Edman N‐terminal microsequencing over 35 amino acid residues, for pony αs1‐casein, clearly demonstrated the occurrence, in Equidae, of a splicing pattern similar to that reported in rodents, characterized by the constitutive outsplicing of exon 5. Pony mare's milk SDS‐PAGE and RP‐HPLC patterns were compared with those obtained for other milks (cow, goat and human), as were the relative levels of caseins and major whey proteins in these milks. Our results provide further evidence to support the notion that Equidae milk is closer to human breast milk than milk from bovine and caprine with respect to the casein and lysozyme C contents and casein/whey proteins ratio.
Antioxidant role of human haptoglobin
Authors: Tseng Chi Feng , Lin Chia Ching , Huang Hsing Yi , Liu Huei Chun , Mao Simon J. T.
Published: June 2004

Human plasma haptoglobin (Hp) is classified according to three phenotypes: Hp 1‐1, 2‐1, and 2‐2 attributed by their two common alleles 1 and 2. Clinically, the 2–2 phenotype is associated with the risk of cardiovascular diseases and diabetes mellitus in patients. In this study, we demonstrate that Hp is an extremely potent antioxidant, which directly protects low density lipoprotein from Cu2+‐induced oxidation. Its potency was markedly superior to probucol (one of the most potent antioxidants). Ranking of the IC50 of antioxidant activity was as follows: Hp 1‐1 ≳ Hp 2‐1 ≳ Hp 2‐2 ≳ probucol ≳ vitamin E. Blockage of disulfide linkages between Hp subunits, not only abolished the α‐helical content but also diminished the ability of Hp to form a complex with hemoglobin. The modified Hp subunits exerted almost 4 times greater antioxidant activity than that of native Hp. To investigate the antioxidant role of Hp on the cellular level, the cDNA of Hp 1‐1 was cloned, introduced into the pcDNA3.0 vector which contains the cytomega lovirus promoter and transfected into chinese hamster ovary (CHO)‐K1 cells. Following transfection, CHO cells were able to express Hp 1–1 protein and significantly (p < 0.001) elevated cell tolerance against oxidative stress. Transfected cells showed 2‐fold higher resistance to hydrogen peroxide exposure for 24 h compared to control cells. Thus, Hp plays a provocative antioxidant role as demonstrated by our in vitro and ex vivo studies.
The kinetics of the epoxy amine cure reaction from a solvation perspective
Authors: Talbot James D. R.
Published: June 2004

This article investigates the role of solvation effects in the autocatalysis reaction of the epoxy–amine cure reaction. A single‐phase three component model was developed encompassing a two‐component reaction mix and a single polymeric product. The reaction was modelled as an SN2 reaction. Association of the nucleophile with each component in the reaction was defined via a binding constant. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3579–3586, 2004
Spectroscopic studies of the conformational properties of naphthoyl chitosan in dilute solutions
Authors: Wu Yusong , Seo Toshihiro , Maeda Shiro , Dong Yanming , Sasaki Takashi , Irie Satoshi , Sakurai Kensuke
Published: June 2004

A naphthoyl chitosan derivative was prepared, and its conformations in dilute solutions were characterized with spectroscopic methods, including circular dichroism (CD) spectroscopy and fluorescence emission spectroscopy. The CD spectrum of this polymer showed a negative band at about 295 nm in dimethyl sulfoxide (DMSO), indicating that the polymer adopted a helical secondary structure. A helix reversion occurred at concentrations greater than 1 mg/mL. The intensity of the CD signal decreased with the addition of water to the solution, and this suggested a change from a helical conformation to a looser one as a result of the collapse of intramolecular hydrogen bonds. In the fluorescence emission experiments, two kinds of excimer emission bands were detected at 375 and 425 nm, and they were assigned to a partially overlapped dimer with a twisted geometry and a fully overlapped dimer with a sandwichlike geometry, respectively. Adding water to a solution of naphthoyl chitosan in DMSO resulted in a gradual reduction of the emission intensity at 375 nm, and this implied that the twisted arrangement of the chromophore was destroyed by the presence of water. The relative intensity (i.e., the ratio of the intensity of the excimer emission at 425 nm to that of the excimer emission at 375 nm) depended on the solvent (DMSO, N,N‐dimethylformamide, N,N‐dimethylacetamide, and 1‐methyl‐2‐pyrrolidinone), and this indicated that the conformation of naphthoyl chitosan was solvent‐dependent. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2747–2758, 2004
New version of the Rayleigh–Schrödinger perturbation theory: Examples
Authors: Kalhous Miloš , Skála L. , Zamastil J. , Čížek J.
Published: June 2004

It has been shown in our preceding papers that the linear dependence of the perturbation wave functions on the perturbation energies makes possible to calculate the exact perturbation energies from the values of the perturbation wave functions corresponding to arbitrarily chosen trial perturbation energies. The resulting version of the perturbation theory is very simple and can be used at large orders. In this paper, this method is applied to a few problems and its numerical properties are discussed. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Regularity Lemma for k‐uniform hypergraphs
Authors: Rödl Vojtěch , Skokan Jozef
Published: June 2004

Szemerédi's Regularity Lemma proved to be a very powerful tool in extremal graph theory with a large number of applications. Chung [Regularity lemmas for hypergraphs and quasi‐randomness, Random Structures Algorithms 2 (1991), 241–252], Frankl and Rödl [The uniformity lemma for hypergraphs, Graphs Combin 8 (1992), 309–312; Extremal problems on set systems, Random Structures Algorithms 20 (2002), 131–164] considered several extensions of Szemerédi's Regularity Lemma to hypergraphs. In particular, [Extremal problems on set systems, Random Structures Algorithms 20 (2002), 131–164] contains a regularity lemma for 3‐uniform hypergraphs that was applied to a number of problems. In this paper, we present a generalization of this regularity lemma to k‐uniform hypergraphs. Similar results were recently independently and alternatively obtained by W. T. Gowers. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
Tragverhalten von Einfeldverbundträgern mit Stegöffnungen
Authors: Zhou Donghua
Published: June 2004

Angesichts der nur wenigen vorliegenden rechnerischen Untersuchungen von Einfeldverbundträgern mit Stegöffnungen werden hier Ergebnisse der nichtlinearen Nachrechnungen von Versuchsträgern mit einer Stegöffnung präsentiert. Hieraus lassen sich einige interessante Erkenntnisse ableiten.
Flexural strength–ductility performance of flanged beam sections cast of high‐strength concrete
Authors: KWAN A. K. H. , AU F. T. K.
Published: June 2004

Flanged sections are often used for long‐span concrete beams to maximize their structural efficiency. However, although for the same sectional area a flanged section could render a higher flexural strength, it would also lead to a lower flexural ductility, especially when heavily reinforced. Thus, when evaluating the flexural performance of a beam section, both the flexural strength and ductility need to be considered. In this study, the post‐peak flexural behaviour of flanged sections is evaluated by means of an analytical method that uses the actual stress–strain curves of the materials and takes into account strain reversal of the tension reinforcement. From the numerical results, the flexural strength–ductility performance of flanged sections is investigated by plotting the strength and ductility that could be simultaneously achieved in the form of design graphs. It is found that (1) at the same overall dimensions and with the same amount of reinforcement provided, a flanged section has lower flexural ductility than a rectangular section; (2) at the same overall dimensions, a flanged section has inferior strength–ductility performance compared to a rectangular section; and (3) at the same sectional area, a flanged section has better strength–ductility performance compared to a rectangular section. Copyright © 2003 John Wiley & Sons, Ltd.
Shaking‐table test of a friction‐damped frame structure
Authors: LIAO WEN‐I , MUALLA IMAD , LOH CHIN‐HSIUNG
Published: June 2004

This paper presents results from an international research project devoted to evaluating the seismic performance of a three‐storey steel frame structure equipped with a friction‐damping device (FDD) recently developed at the Technical University of Denmark. Experimental results indicate that the FDD performed very well in reducing the lateral storey drifts of the test frame. Numerical simulation of the seismic response of the primary and friction‐damped frame was also conducted. This paper also compares the predictions of the displacement demand from the test results with those obtained by the capacity spectrum method. Copyright © 2003 John Wiley & Sons, Ltd.
Low concentration of oxidant and nitric oxide donors stimulate proliferation of human endothelial cells in vitro
Authors: Łuczak Katarzyna , Balcerczyk Aneta , Soszyński Mirosław , Bartosz Grzegorz
Published: June 2004

Proliferation of human umbilical vein endothelial cells in vitro was inhibited by high concentrations of oxidants and nitric oxide donors but stimulated by low (micromolar or submicromolar) concentrations of hydrogen peroxide, menadione, tert‐butyl hydroperoxide, AAPH, nitroglycerin, SIN‐1 and sodium nitroprusside. The stimulation seems to be dependent upon generation of secondary reactive oxygen species as inferred from attenuation of cell proliferation by superoxide dismutase and catalase. These results point to another type of possible artefact of cell culture, viz. stimulation of cell proliferation by low concentrations of oxidants.
Accelerated Aβ aggregation in the presence of GM1‐ganglioside‐accumulated synaptosomes of aged apoE4‐knock‐in mouse brain
Authors: Yamamoto Naoki , Igbabvoa Urule , Shimada Yukiko , Ohno-Iwashita Yoshiko , Kobayashi Mariko , Wood W.Gibson , Fujita Shinobu C , Yanagisawa Katsuhiko
Published: June 2004

Aging and apolipoprotein E4 (apoE4) expression are strong risk factors for the development of Alzheimer's disease (AD); however, their pathological roles remain to be clarified. In the process of AD development, the conversion of the nontoxic amyloid β‐protein (Aβ) monomer to its toxic aggregates is a fundamental process. We previously hypothesized that Aβ aggregation is accelerated through the generation of GM1 ganglioside (GM1)‐bound Aβ which acts as a seed for Aβ fibril formation. Here we report that GM1 level in detergent‐resistant membrane microdomains (DRMs) of synaptosomes increased with age and that this increase was significantly pronounced in the apoE4‐ than the apoE3‐knock‐in mouse brain. Furthermore, we show that Aβ aggregation is markedly accelerated in the presence of the synaptosomes of the aged apoE4‐knock‐in mouse brain. These observations suggest that aging and apoE4 expression cooperatively accelerate Aβ aggregation in the brain through an increase in the level of GM1 in neuronal membranes.
The selective utilization of substrates in vivo by the phosphatidylethanolamine and phosphatidylcholine biosynthetic enzymes Ept1p and Cpt1p in yeast
Authors: Boumann Henry A , de Kruijff Ben , Heck Albert J.R , de Kroon Anton I.P.M
Published: June 2004

In yeast, the aminoalcohol phosphotransferases Ept1p and Cpt1p catalyze the final steps in the CDP‐ethanolamine and CDP‐choline routes leading to phosphatidylethanolamine (PE) and phosphatidylcholine (PC), respectively. To determine how these enzymes contribute to the molecular species profiles of PE and PC in vivo, wild‐type, cpt1Δ, and ept1Δ cells were pulse labeled with deuterated ethanolamine and choline. Analysis of newly synthesized PE and PC using electrospray ionization tandem mass spectrometry revealed that PE and PC produced by Ept1p and Cpt1p have different species compositions, demonstrating that the enzymes consume distinct sets of diacylglycerol species in vivo. Using the characteristic phospholipid species profiles produced by Ept1p and Cpt1p as molecular fingerprints, it was also shown that in vivo CDP‐monomethylethanolamine is preferentially used as substrate by Ept1p, whereas CDP‐dimethylethanolamine and CDP‐propanolamine are converted by Cpt1p.
Pantothenic acid and pantothenol increase biosynthesis of glutathione by boosting cell energetics
Authors: Slyshenkov Vyacheslav S. , Dymkowska Dorota , Wojtczak Lech
Published: June 2004

We have previously observed (summarized in BioFactors 17 (2003) 61) that pantothenic acid, pantothenol and other derivatives that are precursors of CoA protect cells and whole organs against peroxidative damage by increasing the content of cell glutathione. The present investigation was aimed to elucidate the mechanism of this increase in human lymphoblastoic (Jurkat) cells. It showed that incubation of the cells with pantothenic acid or pantothenol increased mainly the content of free glutathione, with little effect on protein‐bound glutathione. Buthionine sulfoximine, an inhibitor of glutathione synthesis, prevented this increase. Increase of the content of free glutathione, as produced by pantothenic acid or pantothenol, was largely prevented by respiratory chain inhibitor rotenone, inhibitor of mitochondrial ATP synthesis oligomycin and uncoupler of oxidative phosphorylation of carbonyl cyanide 3‐chlorophenylhydrazone. These treatments also decreased the cellular content of ATP. Preincubation with pantothenic acid or pantothenol also increased cell respiration with pyruvate as the exogenous substrate. Although no significant increase of total cell CoA content could be found, it is concluded that the increase of the glutathione level was due to increased production of ATP that was, in turn, a result of the increased content of mitochondrial CoA.
High sensitivity detection of protein molecules picked up on a probe of atomic force microscope based on the fluorescence detection by a total internal reflection fluorescence microscope
Authors: Yamada Takafumi , Afrin Rehana , Arakawa Hideo , Ikai Atsushi
Published: June 2004

We developed a method to detect and identify proteins on a probe of the atomic force microscope (AFM) with a high sensitivity. Due to a low background noise of the total internal reflection fluorescence microscope employed as a detecting system, we were able to achieve a high enough sensitivity to detect zeptomole orders of protein molecules immobilized on the tip. Several different methods to immobilize protein molecules to AFM‐probes were tested, meant for a wide range of applications of this method. Furthermore, we demonstrated that different proteins were clearly distinguished by immunofluorescence microscopy on the probe using their specific antibodies.
Kinesin heads fused to hinge‐free myosin tails drive efficient motility
Authors: Eickel Verena , Drummond Douglas , Carter Nick , Lockhart Andrew , Jones John Kendrick , Cross Robert
Published: June 2004

The rat kinesin motor domain was fused at residues 433, 411, 376 or 367, respectively, to the C‐terminal 1185, 1187, 1197 or 1185 residues of the brush border myosin tail. In motility assays, K433myt and K411myt, which preserve the head‐proximal kinesin hinge, and K367myt, which deletes it, drove rapid microtubule sliding (∼0.6 μm s−1) that was optimal when the head‐pairs were spaced apart by adding 1:1 headless myosin tails. K376myt, which partially deletes the head‐proximal hinge, showed poor motility in sliding assays but wild type processivity, velocity and stall force in single molecule optical trapping. Accordingly, the head‐proximal kinesin hinge is functionally dispensable.
Localization of the Tat translocon components in Escherichia coli
Authors: Berthelmann Felix , Brüser Thomas
Published: June 2004

The Tat system has the ability to translocate folded proteins across the bacterial cytoplasmic membrane. In Escherichia coli, three functionally different translocon components have been identified, namely TatA, TatB, and TatC. These proteins were fused to the green fluorescent protein (GFP) and their localization was determined by confocal laser scanning fluorescence microscopy. TatA‐GFP was distributed in the membrane, often with higher abundance at the poles. TatB‐GFP was found in distinct spots at the poles of the cells. The fluorescence of TatC‐GFP was very low and required a constitutive expression system to become higher than background, but then appearing polar. All three constructs complemented the chain‐formation phenotype of corresponding mutant strains, indicating the functionality of the fusion proteins. TatB‐GFP and TatC‐GFP also complemented TMAO respiration deficiency and TatA‐GFP the SDS‐sensitivity of the mutant strains. The localization of the translocon‐GFP fusions coincides with the fluorescence pattern of GFP fusions to Tat substrate signal sequences. We suggest that the active translocon complexes are mainly present at polar positions in Escherichia coli.
The Arabidopsis thaliana chloroplast inner envelope protein ARTEMIS is a functional member of the Alb3/Oxa1/YidC family of proteins
Authors: Funes Soledad , Gerdes Lars , Inaba Masami , Soll Jürgen , Herrmann Johannes M
Published: June 2004

The Arabidopsis thaliana protein ARTEMIS is an integral component of the chloroplast inner envelope required for chloroplast division. It contains a domain of significant homology to members of the Alb3/Oxa1/YidC protein family. Here, we show that upon expression in yeast mitochondria, ARTEMIS can partially take over the function of yeast Oxa1 in the insertion and assembly of mitochondrial membrane proteins. This identifies ARTEMIS as a functional member of the Alb3/Oxa1/YidC protein family and suggests the existence of a novel protein sorting pathway in chloroplasts which integrates polypeptides from the stroma into the inner envelope by an evolutionary conserved process.
Identification of a CXCR4 antagonist, a T140 analog, as an anti‐rheumatoid arthritis agent
Authors: Tamamura Hirokazu , Fujisawa Miho , Hiramatsu Kenichi , Mizumoto Makiko , Nakashima Hideki , Yamamoto Naoki , Otaka Akira , Fujii Nobutaka
Published: June 2004

Several recent papers support the involvement of an interaction between stromal cell‐derived factor‐1 (SDF‐1/CXCL12) and its receptor, chemokine receptor CXCR4, in memory T cell migration in the inflamed rheumatoid arthritis (RA) synovium. Analogs of the 14‐mer peptide T140 were previously found to be specific CXCR4 antagonists that were characterized as not only HIV‐entry inhibitors but also anti‐cancer‐metastatic agents. In this study, a T140 analog, 4F‐benzoyl‐TN14003, was proven to inhibit CXCL12‐mediated migration of human Jurkat cells and mouse splenocyte in a dose‐dependent manner in vitro (IC50=0.65 and 0.54 nM, respectively). Furthermore, slow release administration by subcutaneous injection (s.c.) of 4F‐benzoyl‐TN14003 using an Alzet osmotic pump significantly suppressed the delayed‐type hypersensitivity response induced by sheep red blood cells in mice, and significantly ameliorated clinical severity in collagen‐induced arthritis in mice. As such, T140 analogs might be attractive lead compounds for chemotherapy of RA.
A mitochondrial DNA PCR–RFLP marker for population studies of the black scabbardfish (Aphanopus carbo)
Authors: Quinta Ricardo , Gomes Laurentina , Teia dos Santos Ana
Published: June 2004

Black scabbardfish (Aphanopus carbo), a commercially valuable marine fish off Portugal and the Madeira Archipelago, was surveyed for mitochondrial DNA variation of part of the cytochrome b gene. In all, 51 fish from three Northeast Atlantic localities were examined using ten restriction enzymes. Overall nucleon diversity was 0.180. Genetic differentiation (θ=0.25) was significant; the Madeira Archipelago sample was distinguishable from samples from the other two localities. The approach should be useful for a more extensive study of black scabbardfish populations.
Neuropeptides and non‐human primate social deficits associated with pathogenic rearing experience
Authors: Winslow James T.
Published: June 2004

There is a persuasive evidence that autism is highly heritable and likely to be substantially determined by polygenic mechanisms. Nevertheless, some intriguing findings in children raised in conditions of extreme social deprivation suggest that an autistic‐like syndrome may occur as a consequence of environmental conditions. A particularly close model of this human syndrome has been studied in rhesus monkeys for almost half a century. Monkeys reared in pathogenic rearing conditions manifest considerable deficits in social interaction and increased self‐directed behaviors. We have been interested in the possibility that disruptions in normal social development in non‐human primates might be expressed in neuropeptide systems which have emerged in rodent studies as important candidates for a unique social biology. In recent studies, we have described persistently reduced CSF OT levels in male rhesus monkeys with significant social deficits. We also found that OT levels were positively related to the expression of affiliative social behaviors. Alterations were also detected in both CRH and AVP receptor binding patterns in limbic structures likely to influence social and emotional development. Taken together, these data suggest that abnormal rearing influences the development of brain systems critical to normal social and emotional competence in rhesus monkeys and may contribute to the development of autistic‐like symptomatology associated with pathogenic rearing histories.
Behavioral and growth effects induced by low dose methamphetamine administration during the neonatal period in rats
Authors: Williams Michael T. , Moran Mary S. , Vorhees Charles V.
Published: June 2004

The investigation of methamphetamine exposure during neonatal development in rats has demonstrated that long‐term spatial learning deficits are induced. A previous dose–response study showed that administration of 5 mg/kg methamphetamine, four times daily from postnatal days 11 to 20 produced these deficits, although the effects were not as severe as at higher doses of 10 or 15 mg/kg. This study examined concentrations of methamphetamine at or below 5 mg/kg given over the same period of time. Five different concentrations of methamphetamine (i.e., 5, 2.5, 1.25, 0.625, or 0) were administered every 2 h four times daily from postnatal days 11 to 20. Body weights, zero maze performance, and Morris water maze learning were examined. A dose‐dependent decrease in body weight was observed during the period of methamphetamine administration and these lower weights continued throughout adulthood for the 5, 2.5, and 1.25 mg/kg concentrations, although the adult decreases were negligible. No differences were noted in the zero maze. In the Morris water maze during the acquisition period, dose‐dependent differences in spatial orientation were seen, however non‐dose related deficits were observed for other parameters. During the shifted platform phase (“reversal”), a similar dose‐dependent difference in spatial orientation was observed, although no other effects were noted during this phase. Females performed worse than males regardless of treatment or the phase of learning in the Morris water maze. These data suggest that even lower doses of methamphetamine can alter learning and memory in adulthood, although with less consistent results than with doses higher than 5 mg/kg/dose. These data would caution against even casual use of methamphetamine by women during pregnancy since even low doses could alter the ability of the child to learn.
Anabolic and catabolic mRNA levels of the intervertebral disc vary with the magnitude and frequency of in vivo dynamic compression
Authors: MacLean Jeffery J. , Lee Cynthia R. , Alini Mauro , Iatridis James C.
Published: June 2004

The goal of this study was to characterize the anabolic and catabolic mRNA response of the disc to dynamic loading to determine if variations in the magnitude and/or frequency of loading could elicit different cellular responses. Sixty‐eight Wistar rats were instrumented with an Ilizarov‐type device spanning caudal disc 8–9. Seventy‐two hours after surgery, animals were anesthetized and loaded at either 1 or 0.2 MPa at a frequency of 1, 0.2 or 0.01 Hz for 2 h (6 groups). The surgical control (Sham) animals underwent anesthesia with no loading. Loaded (c8‐9) and internal‐control discs (c6‐7 and c10‐11) were dissected and annulus and nucleus tissue were separately analyzed by real‐time RT‐PCR for levels of anabolic (collagen‐1A1, collagen‐2A1, aggrecan) and catabolic (MMP‐3, MMP‐13, ADAMTs‐4) mRNA. In the nucleus, a frequency‐dependent response was seen at 1 MPa with anabolic genes stimulated at 0.01 Hz and catabolic genes at 1 Hz. In the annulus all frequencies resulted in significant up‐regulation of catabolic mRNA at 1 MPa loading. In general loading at 0.2 MPa or 0.2 Hz had little effect on gene expression. The results suggest that gene expression of the annulus appears to be more dependent on the magnitude of applied stress, while the nucleus is both magnitude‐ and frequency‐dependent. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Which Matters Most? Comparing the Impact of Issues and the Economy in American, British and Canadian Elections
Authors: BLAIS ANDRÉ , TURGEON MATHIEU , GIDENGIL ELISABETH , NEVITTE NEIL , NADEAU RICHARD
Published: June 2004

The objective of this study is to assess and compare the relative impact of issues and the economy on the vote in democratic elections. There is a rich and vast literature dealing with issue voting and an equally impressive literature concerning economic voting. For the most part, however, these amount to two separate streams of research. Relatively little attention has been paid to where these literatures overlap and less still to the simple but basic question: which matters most, the issues or the economy?

The main debate in the issue voting literature recently has been between the directional and proximity models. That debate, engaging both technical and conceptual issues, has focused entirely on how issues play in an election, whether voters prefer the party that is closest to their own position or the party that is the strongest defender of their side on an issue. The question of how much issues affect the vote, however, has been neglected. Indeed, both the proximity and directional schools implicitly agree that issues matter, and so challenge the Michigan school's strong scepticism on the import of issues. Given that the difference between the two models is often quite small, a more fruitful line of investigation might be to return to the equally fundamental ‘how much’ question.
Retroflex fricatives in Slavic languages
Authors: Hamann Silke
Published: June 2004

The present study explores the phonetic and phonological grounds on which postalveolar fricatives in Polish can be analysed as retroflex, and considers whether postalveolar fricatives in other Slavic languages are retroflex as well. Velarization and incompatibility with front vowels are introduced as articulatory criteria for retroflexion, based on cross-linguistic data. According to these criteria, Polish and Russian have retroflex fricatives (i.e., /[small s with hook]/ and /[small z with retroflex hook]/), whereas Bulgarian has a laminal palatoalveolar fricative ((/[small Esh]/). In addition, it is illustrated that palatalization of retroflex fricatives in Slavic languages (and in general) causes a phonetic and phonological change to a non-retroflex fricative.
Realizing the potential of electron cryo-microscopy
Authors: Henderson Richard
Published: June 2004

1. Introduction 3

2. Background 5

3. 2D crystals 7

4. 1D crystals (helical arrays) 8

5. Icosahedral single particles 8

6. Single particles with lower symmetry 9

7. Cellular and subcellular electron tomography 10

8. Conclusion and future prospects 10

9. References 11

Structural analysis by electron microscopy of biological macromolecules or macromolecular assemblies embedded in rapidly frozen, vitreous ice has made great advances during the last few years. Electron cryo-microscopy, or cryo-EM, can now be used to analyse the structures of molecules arranged in the form of two-dimensional crystals, helical arrays or as single particles with or without symmetry. Although it has been possible, using crystalline or helical specimens, to reach a resolution adequate to build atomic models (4 Å), there is every hope this will soon also be possible with single particles. Small and large single particles present different obstacles to progress.
The QRB Essay
Authors: Goldstein Steve A. N.
Published: June 2004

In this issue, we introduce a new format. To meet reader demand, QRB will augment its long-standing commitment to Reviews with Essays. Essays will be brief, timely commentaries considering one or more of the following: a new idea, a new argument about an old idea, the answer to an outstanding question, a new method, a new interpretation, or a subject otherwise of importance to biophysicists. Whereas Reviews are intellectually rigorous reports that stand as definitive statements on a subject for many years, Essays will seek to apply the same high standard to highlighting a moment in time, to show us where we stand and, so, to infer our trajectory. Essays will appear as deemed appropriate; this inaugural year will be replete with an Essay each quarter. The Board is pleased to announce that our Essayists for 2004 will be Richard Henderson (this issue), Donald Crothers (May), Christopher Miller (August) and Brian Matthews (November).
A missing ingredient - more active participation by younger scientists
Authors: CHOWN STEVEN L.
Published: June 2004

The title of this editorial is virtually a refrain of modern international organizations. What some have called “the frozen demographics” seems to threaten the future of science in many fields, not least Antarctic science.
Reproductive biology of female Antarctic spiny plunderfish Harpagifer spinosus (Notothenioidei: Harpagiferidae), from Îles Crozet
Authors: VAN DER MOLEN SILVINA , MATALLANAS JESÚS
Published: June 2004

On the basis of histological examination, we present the first description of oogenesis in H. spinosus. Eight stages of oocyte development were identified using morphological and histochemical criteria. The development of the oocytes is synchronous, and two clutches grow simultaneously in the ovary. Spawning takes place during the end of summer and the beginning of autumn. Absolute fecundity is low, ranging from 787 to 1504 oocytes. The low fecundity is probably related to parental behaviour. Our data indicate that the features of the reproductive biology of H. spinosus, in spite of its unusual environment, are similar to those observed in other teleost fish.
Discovery of the first known benthic invasive species in the Southern Ocean: the North Atlantic spider crab Hyas araneus found in the Antarctic Peninsula
Authors: TAVARES MARCOS , DE MELO GUSTAVO A. S.
Published: June 2004

The Southern Ocean around Antarctica is no longer free from invasive marine species. The North Atlantic spider crab Hyas araneus (Linnaeus, 1758) (Crustacea: Decapoda: Majidae) has been recorded for the first time from the Antarctic Peninsula. Isolated for at least 25 million years, the endemic Antarctic Southern Ocean marine fauna is now being exposed to human-mediated influx of exotic species. Invasive species and polar warming combined can foster the probability of arrival and colonization by non-indigenous species, with unpredictable consequences for the Antarctic marine biota.
Bacteria-algae relationships in Antarctic sea ice
Authors: STEWART F.J. , FRITSEN C.H.
Published: June 2004

Energy transfer in microbial food webs is partly quantified by the relationship between bacterial and algal biomass. Tight spatial relationships suggest active bacterial assimilation of dissolved photosynthate in temperate marine and fresh waters. However, studies in the Antarctic suggest that bacterial biomass generation from algal-derived dissolved organic matter is highly variable across seasons and habitats. Regression analysis was used to measure how bacteria covaried with algae in sea ice and water column habitats at three sites around Antarctica. Bacteria and algae were positively related in sea ice of the Weddell Sea during early winter 1992 (r2 = 0.16, slope = 0.24) and across sea ice and upper water column habitats of the Ross Sea during summer 1999 (r2 = 0.52, slope = 0.50). Conversely, bacteria and algae exhibited no discernible relationship in the water column and first year ice habitats of the Western Antarctic Peninsula region in winter 2001 (r2 = 0.003, slope = −0.04). Low algal production and residual biomass probably limited bacterial production and facilitated bacteria-algae uncoupling in winter sea ice of the Western Antarctic Peninsula. Winter sea ice algal biomass was probably limited by a relatively late date of initial ice formation, reduced multi-year ice coverage, and a lack of radiant energy in the winter ice pack.
Diet components in the food of Antarctic ascidians living at low levels of primary production
Authors: TATIÁN MARCOS , SAHADE RICARDO , ESNAL GRACIELA B.
Published: June 2004

Coupling between pelagic and benthic systems has been described in numerous shallow water communities. In Potter Cove, where pelagic primary production is low (not only during the Antarctic winter but also during the summer), the rich benthic community present there must depend on other food sources than phytoplankton. Over a year-round period we determined the abundance of the different seston particles which constituted the stomach contents of the Antarctic ascidian Cnemidocarpa verrucosa (Lesson, 1830) at Potter Cove. Stomach repletion was highest in November and lowest in June. Ascidians took in a wide range of particles from large detritus (macroalgal debris and faecal pellets) to minute particles < 5 μm. Large detritus and minute particles together represent the main percentage of contents throughout the year (mean 91%). Diatoms were a low percentage (mean 4.5%). Unidentified flagellates, dinoflagellates and coccolithophorids were scarce, with mean values lower than 4%. Among diatoms benthic species were more abundant in summer and pelagic ones prevailed from March to November. Resuspension of benthic material due to wind mixing and the input of allochthonous particles by currents are important mechanisms that ensure food for ascidians and the community of suspension feeders in Potter Cove.