bluuebunny/crossref_metadata_2025 huggingface dataset:
HSP70 Translocates into a cytoplasmic aggregate during lymphocyte activation
Authors: Di Yuan‐Pu , Repasky Elizabeth , Laszlo Andrei , Calderwood Stuart , Subjeck John
Published: February 2005

The percentage of T and B lymphocytes expressing a distinct cytoplasmic aggregate enriched in spectrin, ankyrin, and in several other proteins including protein kinase C greatly increases following various activation protocols. Members of the 70 kDa family of heat shock proteins (hsp70) temporarily bind to and stabilize unfolded segments of other proteins, a function apparently required for proper protein folding and assembly. Considering the multiprotein and dynamic nature of the lymphocyte aggregate, the possibility that hsp70 also might be associated with componets of this structure is considered here. Double immunofluorescence analysis indicates that hsp70 is a component of the lymphocyte aggregate and is coincident with spectrin in a subpopulation of freshly isolated, untreated lymphocytes from various murine tissues and in a T‐lymphocyte hybridoma. When cell lysates of lymph node T cells are immunoprecipitated using an antibody against hsp70 or spectrin and then analyzed by Western blot utilizing the alternate antibody, it was found that hsp70 and spectrin coprecipitated with one another. Moreover, this coprecipitation could be abolished by addition of ATP. This latter observation was extended to lymphoid cells using a transient permeabilization procedure, and it was shown that addition of exogenous ATP results in the dissipation of the aggregate structure itself. Finally, conditions that result in T‐cell activation and aggregate formation, i.e., treatment with the phorbol ester PMA or T‐cell receptor cross‐linking, also lead to the repositioning of hsp70 into the aggregate from a membrane/cytosolic locale in congruence with spectrin. These data suggest that hsp70 is an active component of the aggregate and that it may function in the interactions believed to occur in this unique activation‐associated organelle. © 1995 Wiley‐Liss, Inc.
Modulation of caffeine contractures in mammalian skeletal muscles by variation of extracellular potassium
Authors: Gallant Esther M. , Lentz Linnea R. , Taylor Stuart R.
Published: February 2005

Caffeine contractures were induced after K+ ‐conditioning of skeletal muscles from pigs and mice. K+ ‐conditioning is defined as the partial depolarization caused by increasing external potassium (K) with [K+]×[Cl−] constant. Conditioning depolarizations that rendered muscles refractory to brief electrical stimulation still enhanced the contracture tension elicited by subsequent direct caffeine stimulation of sarcoplasmic reticulum (SR) calcium release. The effects of K+ ‐conditioning on caffeine‐induced contractures of intact cell bundles reached a maximum at 15–30 mM K and then progressively declined at higher [K+]0. Conditioning with 30 mM K+ for 5 min, which inactivates excitation‐contraction (EC) coupling in response to action potentials, both increased the magnitude of caffeine contractures 2–10‐fold and shifted the contracture threshold toward lower caffeine concentrations. Enhanced sensitivity to caffeine was inhibited by dantrolene (20 μM) and its watersoluble analogue azumolene (150 μM). These drugs decreased caffeine‐induced contractures following depolarization with 4–15 mM K+ to 25–50% of control tension. The inorganic anion perchlorate (CIO), which like caffeine potentiates twitches, increased caffeine‐induced contractures ∼︁ twofold after K+ ‐conditioning (>4 mM). The results suggest that CIO and dantrolene, in addition to caffeine, also influence SR calcium release either directly or by mechanism(s) subsequent to depolarization of the sarcolemma. Moreover, since CIO is known to shift the voltage‐dependence of intramembrane charge movement, CIO may exert effects on the transverse‐tubule voltage sensors as well as the SR. © 1995 Wiley‐Liss, Inc.
Transforming growth factor β modulates growth and differentiation of fetal hepatocytes in primary culture
Authors: Sanchez Aranzazu , Alvarez Alberto M. , Benito Manuel , Fabregat Isabel
Published: February 2005

Fetal hepatocytes in primary culture are cells capable to carry out both proliferation and differentiation processes simultaneously. Previous studies have shown that these cells respond to mitogens, such as hepatocyte growth factor (HGF) or epidermal growth factor (EGF), inducing the expression of early genes, such as fos and myc. The transforming growth factor‐β (TGF‐β) family is one of the most influential groups of growth and differentiation factors. In this report, we show that TGF‐β‐1 inhibits fetal hepatocyte proliferation, arresting these cells at G1 phase of the cell cycle. In addition, TGF‐β down‐regulates the mitogen‐induced myc early expression. However, TGF‐β has no effect on the expression of other protooncogenes, such as fos and H‐ras. In addition to its inhibitory role on fetal hepatocyte growth, TGF‐β increases the mRNA levels of fibronectin, an extracellular matrix protein, and maintains the expression of some liver specific genes, such as albumin and alfafetoprotein, above control values. The analysis of the expression of some hepatocyte transcriptional factors has shown that TGF‐β increases HNF1α and HNF1β mRNA levels. We conclude that TGF‐β may modulate liver growth and differentiation throughout fetal development. © 1995 Wiley‐Liss, Inc.
Characterization of adenosine‐uridine‐rich RNA binding factors
Authors: Nakamaki Tsuyoshi , Imamura Jun , Brewer Gary , Tsuruoka Nobuyoshi , Koeffler H. Phillip
Published: February 2005

The adenosine‐uridine (AU)‐rich sequences within the 3′ untranslated region (UTR) of many short‐lived mRNAs are important in their rapid degradation. We present evidence that human embryonic lung fibroblasts (W138) contain five major proteins of 70, 45, 40, 38, 32.5 kd, which specifically bind the AU‐rich region of human granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) 3′UTR containing 7 × AUUUA motifs. The 40 and 38 kd proteins also bound the 3 × and 5 × AUUUA cassettes and even more strongly bound to the AUUUUUUUA motif. All five of these proteins showed more abundant localization in the nucleus than the cytoplasm. The 32.5 kd protein was the major cytoplasmic AU‐binding protein. Incubation with actinomycin D resulted in a marked increase in binding activity of 45, 40, 38, and 32.5 kd proteins in the cytoplasm, accompanied by decreased binding activity of the 32.5 kd protein in the nucleus. Antibody against heterogeneous nuclear ribonucleoprotein C (hnRNP C) immunoprecipitated the 40 and 38 kd proteins, and antibody against the AU‐rich element RNA‐binding protein (AUF1) immunoprecipitated the 45, 40, and 38 kd proteins. The present results not only demonstrated that hnRNP C are AU‐binding proteins which are present in the cytoplasm as well as the nucleus, but another group of AU‐binding proteins (AUF1 [45, 40, 38 kd], and 32.5 kd), which are not hnRNP, have characteristics related to those of hnRNPs. Taken together with our previous results (Akashi et al., 1994, Blood, 83:3182–3187), AU‐binding factors including hnRNP C and AUF1, which bind more than 3 × AUUUA motifs, may be involved in rapid degradation of these transcripts. No significant quantitative changes of these proteins in their binding activity to AU‐rich sequences occurred in response to several stimuli that stabilize GM‐CSF mRNA, indicating that binding of these proteins to their cognate RNA is not responsible for the stabilization of these transcripts. © 1995 Wiley‐Liss Inc.
Proteoglycan synthesis by bovine myocardial endothelial cells is increased by long‐term exposure to high concentrations of glucose
Authors: Klein David J. , Cohen Robert M. , Rymaszewski Zbigniew
Published: February 2005

The role of the metabolic milieu in control of proteoglycan synthesis was investigated using bovine myocardial endothelial cells (BMEC) grown for six to eight passages in media containing either 5.6 or 25 mM glucose. Marcomolecular Na[35S]sulfate incorporation into proteoglycans was increased by exposure to 25 mM when compared with 5.6 mM glucose (7.05 ± 0.40 [SD] vs. 3.5 ± 0.50 × 10−4 dpm/μg DNA). In contrast, [3H]leucine incorporation was unaffected by glucose (11.27 ± 0.85 vs. 9.88 ± 1.23 × 10−5 dpm/μg DNA). The distribution of isotopes between media and cell layer fractions was not different in the two conditions. Addition of 19.4 mM mannitol to 5.6 mM glucose containing media had no effect on isotope incorporation. The HPLC‐DEAE and Sepharose CL‐6B elution profiles of media 35S‐proteoglycans synthesized under each condition were similar. A Sepharose CL‐4B Kav 0.08 heparan sulfate proteoglycan accounted for 20% of the total 35S‐incorporation. Perlecan domain III mRNA was identified by Northern analysis and domain I by the polymerase chain reaction (PCR) in total BMEC RNA. A mixture of chondroitin/dermatan sulfate proteoglycans accounted for 67% of 35S‐incorporation. They eluted from Sepharose CL‐6B at Kav 0 and 0.22. Two [3H]leucine labeled core proteins of 135 and 50 kD were identified in each of these 35S‐proteoglycan peaks. Biglycan but not decorin mRNAs were detected by Northern analysis and by PCR. These data demonstrate that prolonged exposure to high glucose concentrations in vitro stimulate the accumulation of [35S]sulfate into microvascular endothelial cell proteoglycans without significant alterations in their overall hydrodynamic or charge related properties. Modulation of proteoglycan synthesis by glucose may participate in the pathogenesis of the small vessel complications of diabetes. © 1995 Wiley‐Liss Inc.
Differential growth state‐dependent regulation of plasminogen activator inhibitor type‐1 expression in senescent IMR‐90 human diploid fibroblasts
Authors: Mu Xiao‐Chun , Higgins Paul J.
Published: February 2005

The type‐1 inhibitor of plasminogen activator (PAI‐1) regulates pericellular proteolytic activity functioning, thereby to control matrix integrity, cell growth, and morphology. Subconfluent late‐passage IMR‐90 human fibroblasts and normal rat kidney (NRK) cells, both at the stage of replicative senescence accumulated 15‐to 30‐fold more undersurface PAI‐1 protein compared to early‐passage, actively‐proliferating, cultures. Senescence‐associated elevations in PAI‐1 expression by IMR‐90 cells reflected corresponding 11‐fold increases in the 3.0‐ and 2.2‐kb PAI‐1 mRNA species. The 2.2‐kb transcript exhibited a greater age‐dependent increase (7.2‐fold) compared to the 3.0‐kb mRNA (3.7‐fold). Since PAI‐1 expression is coupled to growth activation in serum‐deprived cultures (Ryan and Higgins, 1993, J. Cell. Physiol., 155:376–384), it was important to determine if PAI‐1 gene regulation was altered as a function of cellular aging. In contrast to early‐passage cultures, senescent IMR‐90 fibroblasts did not down‐regulate either PAI‐1 protein expression or steady‐state levels of PAI‐1 mRNA transcripts upon serum‐deprivation. Late‐passage human fibroblasts at their proliferative end‐stage, thus, appear to regulate PAI‐1 mRNA levels through different mechanisms than do young, actively‐proliferating, cells. PAI‐1 overexpression during in vitro cellular aging, therefore, may contribute to the acquisition of specific senescence‐associated phenotypic traits (e.g., enlarged cell morphology; increased adhesivity) by altering the pericellular proteolytic balance influencing, in turn, the formation or stability of cell‐to‐substrate attachment complexes. © 1995 Wiley‐Liss Inc.
Heparin binding, internalization, and metabolism in vascular smooth muscle cells: II. Degradation and secretion in sensitive and resistant cells
Authors: Letourneur Didier , Caleb Benjamin L. , Castellot John J.
Published: February 2005

Smooth muscle cell (SMC) proliferation plays a critical role in several pathological states, including atherosclerosis and hypertension. Heparin suppresses SMC proliferation in vivo and in culture, but the mechanism of action is still poorly understood. In an accompanying article in this issue (Letourneur et al. [1995] J. Cell Physiol., 165:676–686), we observed that heparin binding was up‐regulated in heparin‐sensitive SMC but was rapidly down‐regulated in heparin‐resistant SMC continuously exposed to heparin. In this communication, we examine the degradation and secretion of internalized heparin in sensitive and resistant SMC, using gel filtration chromatography to analyze heparin degradation products. Pulse‐chase experiments using radiolabeled heparin indicate that sensitive and resistant SMC secrete heparin during the first few hours after exposure. Experiments in which cells are continuously exposed to heparin indicate that degradation and secretion occur in both sensitive and resistant SMC for approximately 5–8 hr. After that time, however, binding and internalization in resistant SMC rapidly decrease and degradation and secretion stop. In contrast, heparin binding and uptake continue in sensitive SMC; degradation and secretion also continue. Chloroquine prevents degradation in both sensitive and resistant SMC, suggesting that catabolism occurs in the lysosomal compartment. The results presented in this and the accompanying article (Letourneur et al. [1995] J. Cell. Physiol., 165:676–686) suggest that heparin acts to upregulate its receptors, and that increased binding of heparin is required for the antiproliferative response. Degradation and secretion kinetics parallel the internalization kinetics and appear to be strongly linked to the binding process. © 1995 Wiley‐Liss Inc.
Characterisation of cDNA clones for rat muscle carbonic anhydrase III
Authors: Kelly C. D. , Carter N. D. , Jeffery S. , Edwards Y. H.
Published: February 2005

cDNA clones for rat muscle carbonic anhydrase III have been isolated from a λ gt-11 library and sequenced. Comparison with human CAIII cDNA showed about 90% homology to rat. The rat clones were used to estimate mRNA from liver and muscle on Northern blots and showed that the sexual dimorphism of CAIII in rat liver relates to a difference in mRNA levels.
Characterization of protein kinase C in rat and human prostates
Authors: García-Paramio P. , Carmena M. J. , Román F. , Colás B. , Prieto J. C.
Published: February 2005

The properties of protein kinase C (PKC) activity have been studied in cytosolic and membrane fractions from rat and human prostate. Ion exchange chromatography indicated the existence of different PKC isoforms, PKC from rat ventral prostate behaved as a classical Ca2+- and phospholipid-dependent enzyme and was activated by 1,2-diacylglycerol as well as by high concentrations of arachidonic acid. PKC activity in the cytosolic fraction was higher and presented different cofactor requirements than that in the membrane fraction. PKC from human benign hyperplastic prostate was also phospholipid dependent, activated by tumor-promotong phorbol esters, and appeared to belong to the group of PKC isozymes which lack Ca2+ sensitivity. Human prostatic PKC activity appeared to be of similar nature in both membrane and cytosolic fractions but the specific activity was higher in the particulate preparation which could be related to the stage of endogenous activation of the enzyme. These results extend previous observations in rat ventral prostate and present evidences on the human counterpart. Forthcoming experiments are needed to establish the exact nature of PKC isozymes and their physiological and pathophysiological role in this gland.
Characterization of serine/threonine protein phosphatases in RINm5F insulinoma cells
Authors: Sjöhom Åke , Honkanen Richard E. , Berggren Per-Olof
Published: February 2005

This study investigates the occurrence and regulation of serine/threonine protein phosphatases (PPases) in insulin-secreting RINm5F insulinoma cells. PPases types 1 and 2A were identified in crude RINm5F cell homogenates by both enzymatic assay and Western blot analysis. We then characterized and compared the inhibitory actions of several compounds isolated from cyanobacteria, marine dinoflagellates and marine sponges, (viz. okadaic acid, microcystin-LR, calyculin-A and nodularin) cation-independent PPase activities in RINm5F cell homogenates. It was found that okadaic acid was the least potent inhibitor (IC50 ≈ 10−9M, IC100 ≈ 10−6M), while the other compounds exhibited IC50 values of ≈ 5·10−10 M and IC100 ≈ 5·10−9 M. The findings indicate that the inhibitory substances employed in this study may be used pharmacologically to investigate the role of serine/threonine PPases in RINm5F cell insulin secretion, a process that is likely to be regulated to a major extent by protein phosphorylation.
Factorisation of finite state machines under strong and observational equivalences
Authors: Qin Huajun , Lewis Philip
Published: February 2005

The factorisation problem is to construct the specification of a submoduleXwhen the specifications of the system and all submodules butXare given. It is usually described by the equation where P and X are submodules of system Q, ¦ is a composition operator, and is the equivalence criterion. In this paper we use a finite state machine (FSM) model consistent with CCS and study two factorisation problems:P|||P∼QandP|||P≈Q, where ||| is a derived CCS composition operator, ∼ and ≈ represent strong and observational equivalences. Algorithms are presented and proved correct to find the most general specification of submoduleXforP|||P∼QwithQτ-deterministic and forP|||P≈QwithQdeterministic. Conditions on the submachines of the most general solutions that remain solutions toP|||P∼Q(P|||P≈Q) are given. This paper extends and is based on the work of M. W. Shields.
EU enlargement and immigration policy in Poland and Slovakia
Authors: Vermeersch Peter
Published: February 2005

With the enlargement of the European Union (EU), Poland and Slovakia have become crucial border areas at the eastern edge of EU. This has important implications for the EU’s immigration policy. Both countries have been traditionally known as countries of emigration. In recent times, however, they have increasingly become transit and target countries for immigrants and asylum seekers. The EU has exerted pressure on both countries to tighten their borders in order to fight illegal immigration; they have also been urged to restrict their entry conditions and increasingly consolidate their asylum systems. This article shows that in adopting new immigration and asylum policies these countries have mainly responded to EU interests and less to interests linked to domestic issues.
Relativistic Landau resonances
Authors: Evangelidis E. A. , Botha G. J. J.
Published: February 2005

The possible interactions between plasma waves and relativistic charged particles are considered. An electromagnetic perturbation in the plasma is formulated as an elliptically polarized wave, and the collisionless plasma is described by a distribution in phase space, which is realized in cylindrical coordinates. The linearized Vlasov equation is solved in the semi‐relativistic limit, to obtain the distribution function in the rest frame of the observer. The perturbed currents supported by the ionized medium are then calculated, so that an expression can be written for the total amount of energy available for transfer through the Landau mechanism. It is found that only certain modes of the perturbed current are available for this energy transfer. The final expressions are presented in terms of Stokes parameters, and applied to the special cases of a thermal as well as a nonthermal plasma. The thermal plasma is described by a Maxwellian distribution, while two nonthermal distributions are considered: the kappa distribution and a generalized Weibull distribution.
Parallel temperatures in supersonic beams: Ultracooling of light atoms seeded in a heavier carrier gas
Authors: Miffre A. , Jacquey M. , Büchner M. , Trénec G. , Vigué J.
Published: February 2005

Supersonic expansion is a very powerful tool to produce an atomic beam with a well defined velocity and, by seeding a test gas in such an expansion, the energy of the test gas can be transferred, at least partially, to the very-low-temperature carrier gas. The case usually studied is the one of a heavy gas seeded in a light carrier gas and, in this case, the parallel temperature of the seeded gas is always larger than the one of the carrier gas. In the present paper, we study the opposite case which has received less attention: when a light gas is seeded in a heavier carrier gas, the parallel temperature can be substantially lower for the seeded gas than for the carrier gas. This effect has been first observed by Campargue and co-workers in 2000, in the case of atomic oxygen seeded in argon. In the present paper, we develop a theoretical analysis of this effect, in the high dilution limit, and we compare our theoretical results to several experimental observations, including a set of measurements we have made on a beam of lithium seeded in argon. The agreement between theory and experiments is good.
Survival and relaxation time, pore size distribution moments, and viscous permeability in random unidirectional fiber structures
Authors: Tomadakis Manolis M. , Robertson Teri J.
Published: February 2005

Computer simulation results are presented for the mean survival time, principal relaxation time, mean pore size, and mean square pore size, for random porous structures consisting of parallel nonoverlapping or partially overlapping fibers. The numerical procedure is based on a discrete step-by-step random walk mechanism simulating the Brownian diffusion trajectories of molecules in the porous media. Numerical results on the viscous permeability of these structures are computed with a method based on electrical conduction principles and compared to a variational bound derived from the mean survival time. The results show that nonoverlapping fiber structures exhibit lower values of the dimensionless mean survival time, principal relaxation time, mean pore size, and mean square pore size than randomly overlapping fiber structures of the same porosity, while partially overlapping fiber structures show behavior intermediate to those of the two extreme cases. The mean square pore size (second moment of the pore size distribution) is found to be a very good predictor of the mean survival time for non-, partially, and randomly overlapping fiber structures. Dimensionless groups representing the deviation of variational bounds from our simulation results vary in practically the same range as the corresponding values reported earlier for beds of spherical particles. A universal scaling expression of the literature relating the mean survival time to structural properties [S. Torquato and C. L. Y. Yeong, J. Chem. Phys. 106, 8814 (1997)] agrees very well with our results for all examined fiber structures, thus validated for the first time for porous media formed by partially overlapping particles. The permeability behavior of partially overlapping fiber structures resembles that of nonoverlapping fiber structures for flow parallel to the fibers, but not for transverse flow, where percolation phenomena prevail. The permeability results for beds of unidirectional partially overlapping fibers of moderate and low hard-core porosity compliment successfully earlier numerical data on the permeability of similar structures originating from high-porosity beds of nonoverlapping fibers.
Multireference configuration interaction based electronic Floquet states for molecules in an intense radiation field: Theory and application to Li2+
Authors: Khait Yuriy G. , Azenkeng Alexander , Wang Hefeng , Dudley Timothy J. , Hoffmann Mark R.
Published: February 2005

A multireference configuration interaction (CI) method which includes single and double excitations based description of adiabatic Floquet states for the electronic structure of a molecule in an intense laser field is introduced. Using a variant of a recently introduced configuration state function (CSF) based Table-CI methodology, it is shown that the multiple states of several irreducible representations required for a good description of low-lying Floquet states can be obtained using modifications of computational molecular electronic structure techniques. In particular, formulas for all components of the transition dipole moment matrix elements within the CSF-based Table-CI method are derived and presented. Moreover, the flexibility of the recently introduced macroconfiguration description of model and external configuration spaces is shown to lead to multiple potential energy surfaces of sufficiently uniform quality to allow construction of useful Floquet states. The formalism and computer programs developed are demonstrated on Li2+ in a 0.9×1012W∕cm2 field. In analogy with Na2+, the 1,2Σg+2, 1,2Σu+2, 1Πg2, and 1Πu2 states are of relevance, although the pattern of couplings is shown to be more complex. A hitherto unnoticed metastable state, which correlates asymptotically with 2Σu+2, is described.
Role of angular momentum conservation in unimolecular translational energy release: Validity of the orbiting transition state theory
Authors: Gridelet E. , Lorquet J. C. , Leyh B.
Published: February 2005

The translational kinetic energy release distribution (KERD) for the halogen loss reaction of the bromobenzene and iodobenzene cations has been reinvestigated on the microsecond time scale. Two necessary conditions of validity of the orbiting transition state theory (OTST) for the calculation of kinetic energy release distributions (KERDs) have been formulated. One of them examines the central ion-induced dipole potential approximation. As a second criterion, an adiabatic parameter is derived. The lower the released translational energy and the total angular momentum, the larger the reduced mass, the rotational constant of the molecular fragment, and the polarizability of the released atom, the more valid is the OTST. Only the low-energy dissociation of the iodobenzene ion (E≈0.45eV, where E is the internal energy above the reaction threshold) is found to fulfill the criteria of validity of the OTST. The constraints that act on the dissociation dynamics have been studied by the maximum entropy method. Calculations of entropy deficiencies (which measure the deviation from a microcanonical distribution) show that the pair of fragments does not sample the whole of the phase space that is compatible with the mere specification of the internal energy. The major constraint that results from conservation of angular momentum is related to a reduction of the dimensionality of the dynamics of the translational motion to a two-dimensional space. A second and minor constraint that affects the KERD leads to a suppression of small translational releases, i.e., accounts for threshold behavior. At high internal energies, the effects of curvature of the reaction path and of angular momentum conservation are intricately intermeddled and it is not possible to specify the share of each effect.
A constant volume diesel spray combustion facility and the corresponding experimental diagnostics
Authors: Labs J. E. , Filley J. , Jepsen E. , Parker T. E.
Published: February 2005

A facility was built to examine the diesel spray/combustion process. The facility centers around a constant volume vessel, which consists of a visible and infrared optically accessible cold-wall, heated-interior pressure vessel coupled to an injection system. The combustion vessel is capable of operation at 50atm and 1000K (before injection), was used to simulate preinjection diesel in-cylinder conditions, and was coupled to a repeatable (for each fuel type), single shot, high pressure, metering fuel injection system. A number of experimental diagnostics have been applied to the facility and will be briefly discussed and examples of typical results offered. These diagnostics include: extractive post-combustion gas concentration experiments, droplet sizing measurements, and emission/absorption temperature measurements. Results from this facility capture the critical aspects of diesel spray combustion but do not include the change in pressure associated with heat release in a small volume and volume expansion due to piston motion.
A comparative study for elastic electron collisions on the isoelectronic CNN, NCN, and CCO radicals
Authors: Michelin S. E. , Oliveira H. L. , Kroin T. , Soares L. S. S. , Veiteinheimer E. , Luz C. A. R. , Lima M. F. , Fujimoto M. M. , Lee M.-T.
Published: February 2005

In this work, we present a theoretical study on elastic electron collisions from three isoelectronic free radicals (CNN, NCN, and CCO) in the low incident energy range. More specifically, calculated differential, integral, and momentum transfer cross sections are reported in the 1–30 eV energy range. Calculations are performed in the static-exchange and static-exchange-polarization levels. The iterative Schwinger variational method is used to solve the scattering equations. Our study reveals that the calculated cross sections for the three targets are significantly different at incident energies below 10 eV. Above that energy, a remarkable similarity among the calculated results is seen.
Control of particle assisted wetting by an external magnetic field
Authors: Tierno Pietro , Goedel Werner A.
Published: February 2005

It is shown that repulsive particles can assist wetting of a water surface by an organic liquid even at a particle density substantially less than a close packed monolayer. By applying external fields, one can change the interparticle interactions from net attractive to net repulsive and thus induce a transition from nonwetting to wetting conditions. This was achieved by applying superparamagnetic polystyrene particles together with a polymerizable organic liquid (trimethylolpropane trimethacrylate) to a water surface in the middle of a solenoid. Passing a current through the solenoid created a magnetic field perpendicular to the interface that polarized the particles and induced repulsive dipole-dipole forces. Without the field, lenses of the organic liquid that included aggregates of particles floating on the water surface were observed. In the presence of the field, the organic liquid and the particles were evenly distributed across the surface. The interparticle distance increases proportional to the square root of the area per particle and is close to the value expected for hexagonal order.
Comment on “Silver nanoparticle array structures that produce remarkably narrow plasmon line shapes” [J. Chem. Phys. 120, 10871 (2004)]
Authors: Markel Vadim A.
Published: February 2005

In this Comment I discuss two incorrect statements which were made in the paper “Silver nanoparticle array structures that produce remarkably narrow plasmon line shapes” [J. Chem. Phys.130, 10871 (2004)] by Zou, Janel, and Schatz (ZJS). The first statement is about the use of quasistatic approximation in my earlier work on the similar subject, and the second statement concerns the possibility of exact cancellation of radiative relaxation in periodical chains of nanoparticles. The relationship between the quasistatic approximation, the dipole approximation, and the approximation due to Doyle [Phys. Rev. B39, 9852 (1989)] which was used by ZJS is clarified. It is shown that the exact cancellation of radiative relaxation cannot take place in the particular geometry considered by ZJS.
Electron precession: A guide for implementation
Authors: Own C. S. , Marks L. D. , Sinkler Wharton
Published: February 2005

The design approach for electron precession systems designed at Northwestern University is described, and examples of systems retrofitted onto two different transmission electron microscopes using this method are demonstrated. The precession diffraction patterns from these instruments are of good quality while simultaneously being very easy to acquire. A 15-minute procedure for aligning these instruments is described in the appendix. Partnering this user-friendly and inexpensive hardware implementation with fast and user-friendly crystallography software offers potentially speedy and routine solution of crystal structures.
Programmable spectral interferometric microscopy
Authors: Riza Nabeel A. , Bakker Maarten , Bokhari Amana
Published: February 2005

A programmable optical sensor is proposed based on spectrally programmable heterodyne optical interferometric confocal microscopy implemented via an ultrastable in-line acousto-optic tunable filter (AOTF) based interferometer using double anisotropic acousto-optic Bragg diffraction. The design uses a tunable laser as the light source and anisotropic diffractions in an AOTF to generate two near-collinear orthogonal linear polarization and slightly displaced beams that both pass via the test sample to deliver highly sensitive sample birefringence or material optical retardation measurements. A spherical lens is used to form focused spots for high resolution confocal spatial sampling of the test object. Thus the instrument also forms a classic interferometric confocal microscope via the use of single mode fiber optics for the receive light. The laser and AOTF tuning allows birefringence measurements taken at different wavelengths, one at a time with minimal interwavelength crosstalk. Experimental demonstration of the instrument is achieved using a 1550nm center 100nm band tunable laser and variable birefringence liquid crystal and fixed retardance birefringent materials, all showing accurate retardation measurements to within a 0.5° rf phase accuracy. The instrument shows a fiber-in to fiber-out loss of 8.5dB. An alternate design via a transmissive beam generation design provides collinear co-located beams on the sample plane for superaccurate measurements.
Differential Regulation of FLOWERING LOCUS C Expression by Vernalization in Cabbage and Arabidopsis
Authors: Lin Shu-I , Wang Jhy-Gong , Poon Suk-Yean , Su Chun-lin , Wang Shyh-Shyan , Chiou Tzyy-Jen
Published: February 2005

Vernalization is required to induce flowering in cabbage (Brassica oleracea var Capitata L.). Since FLOWERING LOCUS C (FLC) was identified as a major repressor of flowering in the vernalization pathway in Arabidopsis (Arabidopsis thaliana), two homologs of AtFLC, BoFLC3-2 and BoFLC4-1, were isolated from cabbage to investigate the molecular mechanism of vernalization in cabbage flowering. In addition to the sequence homology, the genomic organization of cabbage FLC is similar to that of AtFLC, except that BoFLC has a relatively smaller intron 1 compared to that of AtFLC. A vernalization-mediated decrease in FLC transcript level was correlated with an increase in FT transcript level in the apex of cabbage. This observation is in agreement with the down-regulation of FT by FLC in Arabidopsis. Yet, unlike that in Arabidopsis, the accumulation of cabbage FLC transcript decreased after cold treatment of leafy plants but not imbibed seeds, which is consistent with the promotion of cabbage flowering by vernalizing adult plants rather than seeds. To further dissect the different regulation of FLC expression between seed-vernalization-responsive species (e.g. Arabidopsis) and plant-vernalization-responsive species (e.g. cabbage), the pBoFLC4-1∷BoFLC4-1∷GUS construct was introduced into Arabidopsis to examine its vernalization response. Down-regulation of the BoFLC4-1∷GUS construct by seed vernalization was unstable and incomplete; in addition, the expression of BoFLC4-1∷GUS was not suppressed by vernalization of transgenic rosette-stage Arabidopsis plants. We propose a hypothesis to illustrate the distinct mechanism by which vernalization regulates the expression of FLC in cabbage and Arabidopsis.
Changes in the ammonite taxonomical diversity gradient during the late Jurassic–early Cretaceous
Authors: Cecca Fabrizio , Vrielynck Bruno , Lavoyer Thibault , Gaget Hélène
Published: February 2005

Aim Changes in the latitudinal gradient of taxonomic diversity of ammonites have been studied in four time slices of the late Jurassic to early Cretaceous (1) to assess the correspondence of the distribution with the general idea of a simple gradient of diversity decreasing polewards, and (2) to offer tentative interpretations of these patterns with respect to palaeoclimatic conditions.

Locations The localities selected lie within the Boreal palaeohemisphere and most are concentrated between 10° and 45° N.

Methods The distributions of genus‐level palaeobiodiversity data have been plotted on palaeogeographical maps. Localities were selected on the basis of criteria that emphasize the accuracy of the rock dating. Palaeolatitudinal positions were obtained using software developed by one of us (BV). Data are largely derived from the literature and data sets have been built for each of the four time slices selected. Information on the palaeoenvironmental context has been included, with observations divided between four palaeoenvironmental systems: epicontinental platforms, intracratonic basins, transitional areas and distal epioceanic basins.

Results The distribution plots demonstrate changes in the steepness of the latitudinal gradient of palaeobiodiversity through time. In general the lowest diversity values are recorded in mid‐ to high‐palaeolatitudes and in epicontinental platform settings of all latitudes, whereas the highest diversities typically correspond to low‐latitude basins. However, in most cases it is difficult to determine whether the poleward decrease of diversity values is a reflection of the palaeoenvironmental context or simply conforms to the diversity gradient model. All patterns are influenced by sampling, and no data were available for equatorial and high palaeolatitudes.

Main conclusions Continental plate movements did not affect the shaping of latitudinal patterns of ammonite diversity and the palaeoenvironmental context is the most important controlling factor. For similar latitudes, the highest diversities occur in basin settings, suggesting that depth is an important influence on diversity distribution. Provincialism was enhanced by the sea‐level fall at the end of the Jurassic that fragmented and restricted ammonite biotas. The effects of climatic fluctuations on the steepness of diversity gradients are probably significant but are currently difficult to demonstrate.
Metabolic correlates of leg length in breeding arctic shorebirds: the cost of getting high
Authors: Cartar Ralph V. , Guy Morrison R. I.
Published: February 2005

Aim We test the hypothesis that tarsus length in all shorebirds breeding in the Canadian arctic shows an evolutionary response to average metabolic stress encountered across the breeding range, such that birds nesting in metabolically stressful environments have relatively shorter legs. Longer‐legged birds living in colder environments will experience greater metabolic costs because their torsos are elevated farther away from the ground's wind‐dampening boundary layer.

Methods We use weather data (temperature, wind speed, global solar radiation) from 27 arctic weather stations measured over 37 years, and a previously published model of heat transfer, to characterize the metabolic harshness over the breeding season of the ranges of each of the 17 shorebirds of the family Charadriidae nesting in the Canadian arctic.

Results After controlling for the lengths of two other body extremities (wing and bill), there was a significant negative relationship between tarsus length and mean metabolic harshness. This result was obtained whether species were treated as independent data points, or in a comparative analysis using standardized independent contrasts.

Main conclusions We support a unique extension of Allen's rule: body‐supporting appendages of homeotherms may be shorter in colder environments so as to take advantage of a boundary layer effect, thereby reducing metabolic costs.
Different apparent CO2 compensation points in nitrate‐ and ammonium‐grown Phaseolus vulgaris and the relationship to non‐photorespiratory CO2 evolution
Authors: Guo Shiwei , Schinner Katrin , Sattelmacher Burkhard , Hansen Ulf‐Peter
Published: February 2005

The classical theory of the relationship between gas fluxes and photosynthetic electron fluxes was extended by two additional terms: JL describing flux to electron sinks other than the Calvin cycle, and RL accounting for light‐induced changes in non‐photorespiratory CO2 evolution. RL comprises two main components, Rr resulting from light‐induced decrease in tricarboxylic acid activity, and RS related to extra CO2 evolution resulting from citrate‐to‐2‐oxoglutarate conversion for N‐assimilation in NO3– grown leaves. This extended theory was applied to two experiments. First, A–Ci curves (dependence of CO2 flux on stomatal CO2 concentration) revealed a higher apparent CO2 compensation point (Γ*app) in NO3–‐grown plants than in NH4+‐grown plants. Secondly, photosynthetic electron fluxes at different light intensities were determined by means of the Genty parameter of chlorophyll fluorescence and compared with those calculated from measured CO2 uptake. Curve‐fitting based on the extended theory provided a coincidence of these two measurements and resulted in higher RS in NO3–‐grown than in NH4+‐grown plants. This difference in RS (about 15% of the CO2 flux bound by carboxylation) is the same as that obtained from the analysis of Γ*app. Further, the analysis suggests that JL related to the extra electron flux used for N‐assimilation in NO3–‐grown plants is diverted to other sinks in NH4+‐grown plants. SHAM decreased photosynthetic electron flow and O2 evolution in NH4+‐grown plants, antimycin A in NO3–‐grown plants. The effect of oligomycin was small. The results are discussed in terms of different mechanisms of chloroplast/mitochondrion interaction in NO3–‐ and NH4+‐grown plants, their effects on non‐photorespiratory CO2 evolution and on Γ*app.
Effects of Three Anthelmintic Regimes on Milk Yield of Ewes and Growth of Lambs
Authors: Fthenakis G. C. , Papadopoulos E. , Himonas C.
Published: February 2005

Forty ewes were allocated into one of four groups (n = 10) and were treated with albendazole (ALB) (3.8 mg kg−1) before lambing (group A), with ALB before and after lambing (group B), with moxidectin (MXD) (0.2 mg kg−1) before lambing (group C) or were untreated controls (group D). Counts of nematode eggs in faeces and coprocultures were carried out during the study, as well as ewes’ milk yield measurements and lamb weighings. Pre‐treatment mean eggs per gram (epg) counts were 640, 715, 625 and 630 for groups A, B, C and D, respectively (P > 0.05); respective counts 21 days after treatment were 5, 0, 0 and 690 epg, whilst 70 days after treatment they were 380, 145, 40 and 1120 epg. Mean lactation milk yield was 3527.5, 3893.5, 3786.4 and 3285.9 ml for groups A, B, C and D, respectively; no significant difference was evident among the four groups in milk yield collected during the suckling period, although subsequently, group B or C ewes yielded significantly more milk than controls (P < 0.05). Mean birthweight of lambs were 3.56, 3.45, 3.59 and 3.26 kg for groups A, B, C and D, respectively (P = 0.045); subsequently, lambs from treated ewes were significantly heavier than lambs from control animals (P < 0.001). We conclude that anti‐parasitic treatment during the last month of pregnancy contributed to an increased birthweight of lambs of treated ewes, whilst the cumulative effect of two doses of ALB or the long persistent efficacy of MXD provided a longer protection of animals against new parasitic infections and contributed to a lactation persistence.
Generating phenotypic variation: prospects from “evo‐devo” research on Bicyclus anynana wing patterns
Authors: Beldade Patrícia , Brakefield Paul M. , Long Anthony D.
Published: February 2005

Summary
Understanding the generation of phenotypic variation is an important challenge for modern evolutionary biology, and butterfly wing patterns are an exciting system that can shed some light on this issue. Here, we report on recent advances in the genetics of Bicyclus anynana butterflies. This system provides the potential for a fully integrated study of the evolutionary and developmental processes underlying diversity in morphology.
Hoxd13 expression in the developing limbs of the short‐tailed fruit bat, Carollia perspicillata
Authors: Chen Chih‐Hsin , Cretekos Chris J. , Rasweiler John J. , Behringer Richard R.
Published: February 2005

Summary
Bat forelimbs are highly specialized for sustained flight, providing a unique model to explore the genetic programs that regulate vertebrate limb diversity. Hoxd9–13 genes are important regulators of stylopodium, zeugopodium, and autopodium development and thus evolutionary changes in their expression profiles and biochemical activities may contribute to divergent limb morphologies in vertebrates. We have isolated the genomic region that includes Hoxd12 and Hoxd13 from Carollia perspicillata, the short‐tailed fruit bat. The bat Hoxd13 gene encodes a protein that shares 95% identity with human and mouse HOXD13. The expression pattern of bat Hoxd13 mRNA during limb development was compared with that of mouse. In bat and mouse hindlimbs, the expression patterns of Hoxd13 are relatively similar. However, although the forelimb Hoxd13 expression patterns in both organisms during early limb bud stages are similar, at later stages they diverge; the anterior expression boundary of bat Hoxd13 is posterior‐shifted relative to the mouse. These findings, compared with the Hoxd13 expression profiles of other vertebrates, suggest that divergent Hoxd13 expression patterns may contribute to limb morphological variation.
Smokers’ unrealistic optimism about their risk
Authors: Weinstein N D , Marcus S E , Moser R P
Published: February 2005

Objective:Past studies have produced ambiguous or inconsistent results when testing whether smokers actually underestimate their own risks of experiencing tobacco related illness. Whereas smokers claim that they are less at risk than the average smoker on self administered questionnaires, this unrealistic optimism has not been found in telephone or face-to-face interviews. We avoided the measurement problems of past studies and examined responses to a number of new questions to assess different aspects of smokers’ perceptions.

Methodology:A US national telephone survey (n  =  6369; 1245 current smokers) posed a variety of questions designed to examine beliefs about the risks of smoking. For key questions, separate samples of smokers were asked either about their own risk or about the risk of the average smoker.

Results:Smokers underestimated their relative risk compared to non-smokers and, contrary to previous interview surveys, believed they have a lower risk of developing lung cancer than the average smoker. Furthermore, their perceived risk of lung cancer and of cancer in general barely increases with the number of cigarettes smoked per day, and their estimates of their risk of cancer are actually slightly lower than their estimates of their risk of lung cancer. Substantial proportions of smokers and former smokers agree with several myths, more than half agreeing that exercise undoes most smoking effects.

Conclusion:Smokers underestimate their risk of lung cancer both relative to other smokers and to non-smokers and demonstrate other misunderstandings of smoking risks. Smoking cannot be interpreted as a choice made in the presence of full information about the potential harm.