bluuebunny/crossref_metadata_2025 huggingface dataset:
Prolactin stimulates prostate cell proliferation by increasing endoplasmic reticulum content due to SERCA 2b over-expression
Authors: Crépin Alexandre , Bidaux Gabriel , Vanden-Abeele Fabien , Dewailly Etienne , Goffin Vincent , Prevarskaya Natalia , Slomianny Christian
Published: December 2006

Prolactin (PRL) has been shown to be involved in the differen-tiation and proliferation of numerous tissues, including the prostate gland. Moreover, variations in [Ca2+]ER (calcium concentration within the endoplasmic reticulum) may play a role in cell growth. However, few studies have focused on the regulation of calcium homoeostasis by prolactin. The present study evaluates the regulation of calcium pools as well as the possible role of [Ca2+]ER variations as a signal for growth modulation by PRL. We show that PRL stimulates the proliferation of normal SV40 immortalized epithelial prostate (PNT1A) cells with a maximum effect at a dose of 100 ng/ml. We also show that 100 ng/ml PRL increases the [Ca2+]ER when measured either by indirect quantific-ation with Fura-2AM after application of 1 μM thapsigargin or by direct quantification with Mag-Fura-2AM within the endoplas-mic reticulum. Western blot analysis shows that the SERCA 2b (sarcoendoplasmic calcium ATPase 2b) is over-expressed in PNT1A cells treated with 100 ng/ml PRL for 24 h. A small inter-fering RNA SERCA 2a/b, used to down-regulate endogenous SERCA 2b expression, reduced both PNT1A cell proliferation and [Ca2+]ER. We thus identify [Ca2+]ER and SERCA 2b as protagonists in PRL-induced proliferation.
Pharmacological profiling of theDictyosteliumadenylate cyclases ACA, ACB and ACG
Authors: Alvarez-Curto Elisa , Weening Karin E. , Schaap Pauline
Published: December 2006

Intracellular and secreted cAMPs play crucial roles in controlling cell movement and gene regulation throughout development of the social amoeba Dictyostelium discoideum. cAMP is produced by three structurally distinct ACs (adenylate cyclases), ACA, ACG and ACB, which have distinctive but overlapping patterns of expression and, as concluded from gene disruption studies, seemingly overlapping functions. In addition to gene disruption, acute pharmacological abrogation of protein activity can be a powerful tool to identify the protein's role in the biology of the organism. We analysed the effects of a range of compounds on the activity of ACA, ACB and ACG to identify enzyme-specific modulators. Caffeine, which was previously used to specifically block ACA function, also inhibited cAMP accumulation by ACB and ACG. IPA (2′,3′-O-isopropylidene adenosine) specifically inhibits ACA when measured in intact cells, without affecting ACB or ACG. All three enzymes are inhibited by the P-site inhibitor DDA (2′,5′-dideoxyadenosine) when assayed in cell lysates, but not in intact cells. Tyrphostin A25 [α-cyano-(3,4,5-trihydroxy)cinnamonitrile] and SQ22536 [9-(tetrahydro-2′-furyl)adenine] proved to be effective and specific inhibitors for ACG and ACA respectively. Both compounds acted directly on enzyme activity assayed in cell lysates, but only SQ22536 was also a specific inhibitor when added to intact cells.
Precise mapping of an IGF-I-binding site on the IGF-1R
Authors: Keyhanfar Mehrnaz , Booker Grant W. , Whittaker Jonathan , Wallace John C. , Forbes Briony E.
Published: December 2006

The IGF-1R [type 1 IGF (insulin-like growth factor) receptor] is activated upon binding to IGF-I and IGF-II leading to cell growth, survival and migration of both normal and cancerous cells. We have characterized the binding interaction between the IGF-1R and its ligands using two high-affinity mouse anti-IGF-1R mAbs (monoclonal antibodies), 7C2 and 9E11. These mAbs both block IGF-I binding to the IGF-1R but have no effect on IGF-II binding. Epitope mapping using chimaeras of the IGF-1R and insulin receptor revealed that the mAbs bind to the CR (cysteine-rich) domain of IGF-1R. The epitope was finely mapped using single point mutations in the IGF-1R. Mutation of Phe241, Phe251 or Phe266 completely abolished 7C2 and 9E11 binding. The three-dimensional structure showed that these residues cluster on the surface of the CR-domain. BIAcore analyses revealed that IGF-I and a chimaeric IGF-II with the IGF-I C-domain competed for the binding of both mAbs with the IGF-1R, whereas neither IGF-II nor a chimaeric IGF-I with the IGF-II C-domain affected antibody binding. We therefore conclude the IGF-I C-domain interacts with the CR (cysteine-rich) domain of the receptor at the cluster of residues Phe241, Phe251 and Phe266. These results allow precise orientation of IGF-I within the IGF-I–IGF-1R complex involving the IGF-I C-domain binding to the IGF-1R CR domain. In addition, mAbs 7C2 and 9E11 inhibited both IGF-I- and IGF-II-induced cancer cell proliferation, migration and IGF-1R down-regulation, demonstrating that targeting the IGF-1R is an effective strategy for inhibition of cancer cell growth.
Inhibition of human betaine–homocysteine methyltransferase expression by S-adenosylmethionine and methylthioadenosine
Authors: Ou Xiaopeng , Yang Heping , Ramani Komal , Ara Ainhoa Iglesias , Chen Hui , Mato José M. , Lu Shelly C.
Published: December 2006

BHMT (betaine–homocysteine methyltransferase) remethylates homocysteine to form methionine. SAM (S-adenosylmethionine) inhibits BHMT activity, but whether SAM modulates BHMT gene expression is unknown. Transcriptional regulation of the human BHMT is also unknown. The present study examined regulation of the human BHMT gene by SAM and its metabolite, MTA (5′-methylthioadenosine). To facilitate these studies, we cloned the 2.7 kb 5′-flanking region of the human BHMT gene (GenBank® accession number AY325901). Both SAM and MTA treatment of HepG2 cells resulted in a dose- and time-dependent decrease in BHMT mRNA levels, which paralleled their effects on the BHMT promoter activity. Maximal suppression was observed with the BHMT promoter construct −347/+33, which contains a number of NF-κB (nuclear factor κB) binding sites. SAM and MTA treatment increased NF-κB nuclear binding and NF-κB-driven luciferase activities, and increased nuclear binding activity of multiple histone deacetylase co-repressors to the NF-κB sites. Overexpression of p50 and p65 decreased BHMT promoter activity, while blocking NF-κB activation increased BHMT expression and promoter activity, and prevented SAM but not MTA's ability to inhibit BHMT expression. The NF-κB binding site at −301 is responsible, at least in part, for this effect. Lower BHMT expression can impair homocysteine metabolism, which can induce ER (endoplasmic reticulum) stress. Indeed, MTA treatment resulted in increased expression ER stress markers. In conclusion, SAM and MTA down-regulate BHMT expression in HepG2 cells in part by inducing NF-κB, which acts as a repressor for the human BHMT gene. While SAM's mechanism is NF-κB-dependent, MTA has both NF-κB-dependent and -independent mechanisms.
Calculation of nonadiabatic couplings with restricted open-shell Kohn-Sham density-functional theory
Authors: Billeter Salomon R. , Egli Daniel
Published: December 2006

This paper generalizes the recently proposed approaches for calculating the derivative couplings between adiabatic states in density-functional theory (DFT) based on a Slater transition-state density to transitions such as singlet-singlet excitations, where a single-determinant ansatz is insufficient. The proposed approach is based on restricted open-shell Frank et al. [J. Chem. Phys. 108, 4060 (1998)] theory used to describe a spin-adapted Slater transition state. To treat the dependence of electron-electron interactions on the nuclear positions, variational linear-response density-functional perturbation theory is generalized to reference states with an orbital-dependent Kohn-Sham Hamiltonian and nontrivial occupation patterns. The methods proposed in this paper are not limited to the calculation of derivative coupling vectors, but can also be used for the calculation of other transition matrix elements. Moreover, they can be used to calculate the linear response of open-shell systems to arbitrary external perturbations in DFT.
Interaction of an oblique shock wave with a pair of parallel vortices: Shock dynamics and mechanism of sound generation
Authors: Zhang Shuhai , Zhang Yong-Tao , Shu Chi-Wang
Published: December 2006

The interaction between an oblique shock wave and a pair of parallel vortices is simulated systematically through solving the two-dimensional, unsteady compressible Navier-Stokes equations using a fifth order weighted essentially nonoscillatory finite difference scheme. The main purpose of this study is to characterize the flow structure and the mechanism of sound generation in the interaction between an oblique shock wave and a pair of vortices. We study two typical shock waves of Mach number Ms=1.2 and Ms=1.05, which correspond to two typical shock structures of Mach reflection and regular reflection, respectively, in the problem of shock-vortex interaction. The effects of the strength of the vortices and the geometry parameters are investigated. In addition, we have also considered both cases of passing and colliding vortex pairs. The interaction is classified into four types for the passing case and seven types for the colliding case according to different patterns of the shock structure. Our simulation shows that the sound field is the result of three mechanisms. The first mechanism is related directly to the interaction of the shock wave and the pair of vortices. The second mechanism is related to the coupling process of the vortex pair. The third mechanism is related to the interaction of the reflected shock waves and sound waves. The first mechanism is dominating if the vortex pair is weak. The combination of the first and the second mechanisms is dominating if the vortex pair is of moderate strength. If the vortex pair is strong, the acoustic field is also significantly affected by the interaction of the reflected shock waves and sound waves.
The edge electric field of a pyroelectric and its applications
Authors: Sandomirsky V. , Schlesinger Y. , Levin R.
Published: December 2006

Following a change of temperature of a pyroelectric (PE), a depolarizing electric field appears both inside the PE as well as outside its edges, the edge depolarizing electric field (EDEF). The EDEF extends outwards up to a distance of the order of magnitude of the PE width. The mapping and the strength of the EDEF have been here calculated and analyzed for the case of a semi-infinite pyroelectric plate. We propose here the idea of utilizing the EDEF of the pyroelectric solely as the source of an electrical field. This strong EDEF (104–105V∕cm), when penetrating into the surrounding medium, creates a variety of physical effects: inducing electrical current in a semiconductor and affecting its resistance, accelerating charged and neutral particles in vacuum or in a gas, generating electromagnetic waves, modifying optical characteristics by electro-optical and photoelasic effects, generating piezoelectric deformation, and more. We discuss a number of possible applications and devices based on these EDEF induced effects.
Influence of outlet geometry on strongly swirling turbulent flow through a circular tube
Authors: Escudier M. P. , Nickson A. K. , Poole R. J.
Published: December 2006

The results are reported for an extensive series of measurements (using laser Doppler anemometry) of the mean and fluctuating flow fields for swirling turbulent flow downstream of an orifice in a tube. The influence of a concentric outlet contraction is found to be negligible for low “supercritical” swirl. For high “subcritical” swirl, the outlet geometry is found to have a significant influence throughout the flow field and, in the case of an eccentric (i.e., offset) outlet, to lead to an asymmetric flow with a distorted core. In no case was the core found to precess or the flow to be periodic.
Analytical modeling of edge effects on the residual stresses within the film/substrate systems. I. Interfacial stresses
Authors: Zhang X. C. , Xu B. S. , Wang H. D. , Wu Y. X.
Published: December 2006

Several analytical models have been developed to derive the closed-form solutions for the residual stresses at the interface when a film was overlaid on a substrate. In these models, the film edge effects on the interfacial stresses were analyzed. However, some of the existing models do not yield good results, and sometimes, they err in a fundamental manner in the prediction of the interfacial stress distribution. In this paper, an analytical model is developed to derive the closed-form solutions for the interfacial stress distributions along the film width. Compared to the existing analytical models, the present model is more rigorous and the analytical results agree better with the finite element results.
Analytical modeling of edge effects on the residual stresses within the film/substrate systems. II. Normal stresses
Authors: Zhang X. C. , Xu B. S. , Wang H. D. , Wu Y. X.
Published: December 2006

For the film/substrate bimaterial system, some considerable efforts have been made to predict the stress distribution in the film. However, only the normal stress in the film at the position away from the edge is usually considered. Moreover, the stress gradient through the thickness in the film and the stress in the substrate are often ignored. In this paper, an analytical model is developed to analyze the edge effects on the stress gradients in the film and the substrate. In order to obtain the closed-form solutions for the stresses in the film and the substrate, the shear lag model in the planar geometry is used to solve the stress transfer problem. By comparing the results from the present model with those from the existing analytical models, finite element analysis, and the experimental measurements, it can be concluded that the present analytical model is very rigorous.
Optical absorption and photoluminescence in the ternary chalcopyrite semiconductor AgInSe2
Authors: Ozaki Shunji , Adachi Sadao
Published: December 2006

Optical-absorption and photoluminescence (PL) spectra have been measured on the ternary chalcopyrite semiconductor AgInSe2 at T=13–300K. The direct-band-gap energy Eg of AgInSe2 determined from the optical absorption measurements shows unusual temperature dependence at low temperatures. The resultant temperature coefficient ∂Eg∕∂T is found to be positive at T<125K and negative above 125K. The PL spectra show asymmetric emission bands peaking at ∼1.18 and ∼1.20eV at T=13K, which are attributed to donor-acceptor pair recombinations between exponentially tailed donor states and acceptor levels. An energy-band scheme has been proposed for the explanation of the peculiar PL emission spectra observed in AgInSe2.
Flexible piezoelectric pressure sensors using oriented aluminum nitride thin films prepared on polyethylene terephthalate films
Authors: Akiyama Morito , Morofuji Yukari , Kamohara Toshihiro , Nishikubo Keiko , Tsubai Masayoshi , Fukuda Osamu , Ueno Naohiro
Published: December 2006

We have investigated the high sensitive piezoelectric response of c-axis oriented aluminum nitride (AlN) thin films prepared on polyethylene terephthalate (PET) films. The AlN films were deposited using a radio frequency magnetron sputtering method at temperatures close to room temperature. The c axes of the AlN films were perpendicularly oriented to the PET film surfaces. The sensor consisting of the AlN and PET films is flexible like PET films and the electrical charge is linearly proportional to the stress within a wide range from 0to8.5MPa. The sensor can respond to the frequencies from 0.3 to over 100Hz and measures a clear human pulse wave form by holding the sensor between thumb and middle finger. The resolution of the pulse wave form is comparable to a sphygmomanometer at stress levels of 10kPa. We think that the origin of the high performance of the sensor is the deflection effect, the thin thickness and high elastic modulus of the AlN layer, and the thin thickness and low elastic modulus of the PET film.
Optimal piston trajectories for adiabatic processes in the presence of friction
Authors: Huleihil Mahmoud , Andresen Bjarne
Published: December 2006

Optimal piston motion is derived for adiabatic processes in the presence of different types of friction and with frictional energy dissipated externally as well as internally. The assumed model for the frictional dissipation affects the optimal motion. We consider a piston fitted in a cylinder containing an ideal gas as the working fluid. The gas starts from a given initial temperature and is assumed to complete the process in a prescribed finite time. The effect of the working gas temperature (or equivalently internal energy) on the viscosity leads to a temperature dependence of the frictional losses. The optimal piston motion then is no longer constant speed, as was concluded previously for the externally dissipative case. In the current study two objectives are considered: maximizing power output and minimizing frictional losses. It is shown that in the externally dissipative mode optimizing power or frictional losses are equivalent, while in the internally dissipative mode the optimal motions are different.
Integrated organic photovoltaic modules with a scalable voltage output
Authors: Yoo S. , Potscavage W. J. , Domercq B. , Kim J. , Holt J. , Kippelen B.
Published: December 2006

Efficient organic photovoltaic modules and cells have been fabricated based on a blend of poly(3-hexylthiophene) (P3HT) and a soluble C70 derivative, [6,6]-phenyl C71 butyric acid methyl ester (PCBM-70). Power conversion efficiency of P3HT/PCBM-70 cells is estimated at 4.1% for the AM1.5G condition from the spectra of external quantum efficiency. Integrated photovoltaic modules, in which N- individual P3HT/PCBM-70 cells (N=1–4) are connected in series, exhibit a short-circuit current ISC of 1.4±0.1mA and an open-circuit voltage VOC of N×0.621V with a maximum VOC of 2.48V for N=4 under simulated solar illumination (AM1.5G, 85mW∕cm2).
Arrays of vacuum microdiodes using uniform diamondlike-carbon tip apexes
Authors: She J. C. , Hao H. , Xu N. S. , Deng S. Z. , Chen J. , Huq S. E. , Wang L.
Published: December 2006

The authors report the fabrication and characterization of vacuum microdiode arrays using Si microtip with uniform diamondlike-carbon (DLC) apexes. The technique is based on the mass production procedure of integrated circuit devices. The typical turn-on voltage of the microdiode arrays is 50V, and it can provide emission current density up to 0.24A∕cm2 at 210V. The developed diodes with coated apexes considerably surpass the diodes with virgin Si tip (98V∕0.058A∕cm2) in their performance. Thus, the microdiode with DLC coatings on Si tip apexes are attractive for applications in charge neutralizers and microwave amplifiers. The underlying physics responsible for the device operation is discussed.
Size-dependent elastic modulus of single electroactive polymer nanofibers
Authors: Shin Min Kyoon , Kim Sun I. , Kim Seon Jeong , Kim Sung-Kyoung , Lee Haiwon , Spinks Geoffrey M.
Published: December 2006

The authors report for the first time the size dependency of the elastic modulus of well-aligned single polymeric nanofibers. The nanofibers were fabricated from electroactive polymers (EAPs) and had an ellipsoidal cross section because of impingement between a solid surface and a polymer jet during electrospinning. Although the EAPs had very weak mechanical properties in the bulk, the elastic modulus of single EAP nanofibers increased exponentially as the diameter of the EAP nanofibers decreased to diameters of a few tens of nanometers. The elastic modulus of single nanofibers was measured using three-point bending tests employing an atomic force microscope.
Analytic device model for light-emitting ambipolar organic semiconductor field-effect transistors
Authors: Smith D. L. , Ruden P. P.
Published: December 2006

Recent experiments have demonstrated ambipolar channel conduction and light emission in conjugated polymer field-effect transistors (FETs). Electrons and holes are injected from metal source and drain contacts with different work functions, propagate through the FET channel, and recombine emitting light. The position of maximum light emission is varied by changing the voltages applied to the transistor terminals. Here, we present an analytic device model for ambipolar organic field-effect transistors, based on the gradual channel approximation. Trapping of the injected carriers is found to be important. The model results are in good agreement with the experimental observations.
Fragmentation of colloidal nanoparticles by femtosecond laser-induced supercontinuum generation
Authors: Besner S. , Kabashin A. V. , Meunier M.
Published: December 2006

A femtosecond laser-based method to control the size characteristics of gold colloidal nanoparticles is reported. The method uses the supercontinuum generation produced through a strong nonlinear-optical interaction of the femtosecond radiation with a liquid to fragment relatively large colloids and reduce their agglomeration. The fragmented species then recoalesce to form smaller, less dispersed, and much more stable nanoparticles in the solution. The size of the nanoparticles after the treatment is independent of the initial characteristics of colloids, but depends strongly on laser parameters and on the presence of chemically active species in the solution.
Electro-optic effect exaltation on lithium niobate photonic crystals due to slow photons
Authors: Roussey M. , Bernal M.-P. , Courjal N. , Van Labeke D. , Baida F. I. , Salut R.
Published: December 2006

The authors demonstrate how slow group velocities that are easily attainable at the band edge of photonic crystals can drastically enhance the electro-optical effect on tunable photonic crystal components. This property opens up the possibility of microsized nonlinear devices with low power requirement. In this letter we show how these possibilities for enhancement of nonlinear effects have been used to fabricate a 13×13μm2 sized lithium niobate photonic crystal intensity modulator that shows an enhanced electro-optic effect 312 times bigger than the one predicted by the classical Pockels effect for an equivalent device in bulk material.
Study of the size effect on the optical mode frequencies of ZnO nanoparticles with nearly uniform size
Authors: Zhang S. L. , Zhang Y. , Fu Z. , Wu S. N. , Gao M. , Liu M. , Chen J. , Niu L. , Jiang J. Z. , Ling Y. , Wang Q. , Chen H.
Published: December 2006

It was found in ZnO nanoparticles of nearly uniform size that the Raman frequencies of both the polar A1(LO) and nonpolar E2(H) modes do not shift with particle sizes. This observation is in perfect agreement with previous theoretical prediction. The observed result is consistent with the prediction that the size insensitivity of optic vibration frequency in polar nanosemiconductors originates from the Fröhlich interaction, which exists only in polar nanosemiconductors.
Hugoniot-compression curve of Zr-based bulk metallic glass
Authors: Mashimo T. , Togo H. , Zhang Y. , Uemura Y. , Kinoshita T. , Kodama M. , Kawamura Y.
Published: December 2006

The Hugoniot-compression curves of the Zr-based bulk metallic glass (Zr55Al10Ni5Cu30 in at. %) and the metallic compound crystal with the same composition were measured by means of the inclined-mirror photographic technique. A kink was observed on the Hugoniot curve at 14GPa for the glass probably due to phase transition, while no kink was observed for the crystal. The Hugoniot elastic limit stress (6.2GPa) of the glass was comparable to one of the crystal.
Complete set of elastic, dielectric, and piezoelectric coefficents of 0.93Pb(Zn1∕3Nb2∕3)O3–0.07PbTiO3 single crystal poled along [011]
Authors: Zhang Rui , Jiang Bei , Jiang Wenhua , Cao Wenwu
Published: December 2006

The authors report a complete set of elastic, dielectric, and piezoelectric coefficients of rhomboheral phase 0.93Pb(Zn1∕3Nb2∕3)O3–0.07PbTiO3 single crystal poled along [011] measured at room temperature. It was found that the electromechanical coupling coefficients k32 and k33 of this domain engineered single crystal can reach 0.86 and 0.87, respectively, and the piezoelectric coefficients d32 and d15 are −1460 and 1823pC∕N, respectively. This complete set of data can meet the urgent need of device designers using these super piezoelectric crystals and also provide important information for fundamental studies on domain engineering.
7
W
high-efficiency continuous-wave green light generation by intracavity frequency doubling of an end-pumped vertical external-cavity surface emitting semiconductor laser
Authors: Lee JunHo , Lee SangMoon , Kim Taek , Park YongJo
Published: December 2006

The authors report the demonstration of highly efficient continuous-wave green light at 535nm generation by intracavity frequency doubling of an end-pumped vertical external-cavity surface emitting semiconductor laser (VECSEL). The beta-barium borate (β-BaB2O4) crystals, cut for critical type I phase matching at room temperature, are used for second harmonic generation of the laser. In combination with an end-pumped VECSEL and efficient intracavity frequency doubling with a folded three-mirror cavity, more than 7W green light output power is obtained at pump power of 26W. The optical conversion efficiency of 27% is achieved from pump power to second harmonic power.
Ablation of solids using a femtosecond extreme ultraviolet free electron laser
Authors: Stojanovic N. , von der Linde D. , Sokolowski-Tinten K. , Zastrau U. , Perner F. , Förster E. , Sobierajski R. , Nietubyc R. , Jurek M. , Klinger D. , Pelka J. , Krzywinski J. , Juha L , Cihelka J. , Velyhan A. , Koptyaev S. , Hajkova V. , Chalupsky J. , Kuba J. , Tschentscher T. , Toleikis S. , Düsterer S. , Redlin H.
Published: December 2006

The ablation of solids by high energy femtosecond pulses from an extreme ultraviolet (XUV) free electron laser has been investigated using picosecond optical imaging. The time-resolved measurements are supplemented by an analysis of the permanent structural surface modifications. Compared with femtosecond optical excitation, distinct differences in the material response are found which are attributed to the increased penetration depth of the XUV radiation and the absence of any absorption nonlinearities.
Enhanced thermal stability and emission intensity of InAs quantum dots covered by an InGaAsSb strain-reducing layer
Authors: Liu Wei-Sheng , Kuo David M. T. , Chyi Jen-Inn , Chen Wen-Yen , Chang Hsing-Szu , Hsu Tzu-Min
Published: December 2006

An InGaAsSb overgrown layer, i.e., strain-reducing layer (SRL), is adopted to increase the emission intensity of InAs quantum dots (QDs) and extend the emission wavelength to as long as 1.42μm. InAs QDs capped with InGaAsSb SRL also exhibit a thermal activation energy of 534meV, which is much higher than that of InAs QDs with an InGaAs SRL. The increase in luminescence efficiency and thermal stability is attributed to the improved carrier confinement of the GaAs∕InAs∕InGaAsSb heterostructure.
The Protective Role of Dietary Calcium Against Cadmium Uptake and Toxicity in Freshwater Fish: an Important Role for the Stomach
Authors: Wood Chris M. , Franklin Natasha M. , Niyogi Som
Published: December 2006

Environmental Context. Contamination of freshwater ecosystems by cadmium is of increasing concern with accumulation and toxicity in aquatic animals occurring through both waterborne and dietary routes. Increases in water calcium (‘hardness’) levels protect against waterborne uptake. Physiological research on freshwater fish has demonstrated that this occurs because cadmium moves through the calcium uptake pathway at the gills. Surprisingly, elevated dietary calcium also protects against waterborne exposure by down-regulating the calcium uptake pathway at the gills, and against dietary exposure by reducing cadmium uptake through the gastrointestinal tract. In both cases, the stomach is the critical site of action. Abstract. Waterborne cadmium causes toxicity in freshwater fish by inducing hypocalcaemia. Research on the rainbow trout (Oncorhynchus mykiss), a sensitive model species, has demonstrated that this occurs because Cd2+ ions compete with waterborne Ca2+ ions for the active branchial uptake pathway which normally ensures internal homeostasis of calcium levels. Therefore, increases in waterborne calcium concentrations (‘hardness’) protect against waterborne cadmium uptake and toxicity in both acute and chronic exposures. Increases in dietary calcium concentration also protect against waterborne exposure, because elevated gastrointestinal calcium uptake down-regulates the Ca2+ uptake pathway at the gills, thereby simultaneously reducing Cd2+ entry. Furthermore, dietary calcium also protects against dietborne cadmium exposure, although the physiological mechanisms appear to differ from those at the gills. Surprisingly, the principal site of this inhibitory action of dietary calcium on gastrointestinal cadmium uptake appears to be the stomach, which is also the major site of gastrointestinal calcium uptake, rather than the intestine as in mammals. These results underline the importance of considering not only water chemistry but also dietary chemistry in the environmental regulation of cadmium, and suggest that fish in the wild under chronic cadmium stress would benefit by switching to a more calcium-rich diet. While diet switching has been seen in the wild in fish under metal stress, its etiology remains unknown; to date, laboratory experiments have not been able to show that voluntary diet-switching of an adaptive nature actually occurs.
RETRACTED: RNA silencing of host transcripts by cauliflower mosaic virus requires coordinated action of the four
Arabidopsis
Dicer-like proteins
Authors: Moissiard Guillaume , Voinnet Olivier
Published: December 2006

RNA silencing is an ancient mechanism of gene regulation with important antiviral roles in plants and insects. Although induction of RNA silencing by RNA viruses has been well documented in plants, the interactions between DNA viruses and the host silencing machinery remain poorly understood. We investigate this question with cauliflower mosaic virus (CaMV), a dsDNA virus that expresses its genome through the polycistronic 35S RNA, which carries an unusually extensive secondary structure known as translational leader. We show that CaMV-derived siRNAs accumulate in turnip- and
Arabidopsis
-infected plants and that the leader is a major, albeit not exclusive, source for those molecules. Biogenesis of leader-derived siRNA requires the coordinated and hierarchical action of the four
Arabidopsis
Dicer-like (DCL) proteins. Our study also uncovers a “facilitating” role exerted by the microRNA biosynthetic enzyme DCL1 on accumulation of DCL2-, DCL3-, and DCL4-dependent siRNAs derived from the 35S leader. This feature of DCL1 defines a small RNA biosynthetic pathway that might have relevance for endogenous gene regulation. Several leader-derived siRNAs were found to bear near-perfect sequence complementarity to
Arabidopsis
transcripts, and, using a sensor transgene, we provide direct evidence that at least one of those molecules acts as a bona fide siRNA in infected turnip. Extensive bioinformatics searches identified >100 transcripts potentially targeted by CaMV-derived siRNAs, several of which are effectively down-regulated during infection. The implications of virus-directed silencing of host gene expression are discussed.
RAR1, a central player in plant immunity, is targeted by
Pseudomonas syringae
effector AvrB
Authors: Shang Yulei , Li Xinyan , Cui Haitao , He Ping , Thilmony Roger , Chintamanani Satya , Zwiesler-Vollick Julie , Gopalan Suresh , Tang Xiaoyan , Zhou Jian-Min
Published: December 2006

Pathogenic bacterial effectors suppress pathogen-associated molecular pattern (PAMP)-triggered host immunity, thereby promoting parasitism. In the presence of cognate resistance genes, it is proposed that plants detect the virulence activity of bacterial effectors and trigger a defense response, referred to here as effector-triggered immunity (ETI). However, the link between effector virulence and ETI at the molecular level is unknown. Here, we show that the
Pseudomonas syringae
effector AvrB suppresses PAMP-triggered immunity (PTI) through RAR1, a cochaperone of HSP90 required for ETI. AvrB expressed in plants lacking the cognate resistance gene
RPM1
suppresses cell wall defense induced by the flagellar peptide flg22, a well known PAMP, and promotes the growth of nonpathogenic bacteria in a
RAR1
-dependent manner.
rar1
mutants display enhanced cell wall defense in response to flg22, indicating that RAR1 negatively regulates PTI. Furthermore, coimmunoprecipitation experiments indicated that RAR1 and AvrB interact in the plant. The results demonstrate that RAR1 molecularly links PTI, effector virulence, and ETI. The study supports that both pathogen virulence and plant disease resistance have evolved around PTI.
Identification of a large noncoding RNA in extremophilic eubacteria
Authors: Puerta-Fernandez Elena , Barrick Jeffrey E. , Roth Adam , Breaker Ronald R.
Published: December 2006

We have discovered a large and highly conserved RNA motif that typically resides in a noncoding section of a multigene messenger RNA in extremophilic Gram-positive eubacteria. RNAs of this class adopt an ornate secondary structure, are large compared with most other noncoding RNAs, and have been identified only in certain extremophilic bacteria. These ornate, large, extremophilic (OLE) RNAs have a length of ≈610 nucleotides, and the 35 representatives examined exhibit extraordinary conservation of nucleotide sequence and base pairing. Structural probing of the OLE RNA from
Bacillus halodurans
corroborates a complex secondary structure model predicted from comparative sequence analysis. The patterns of structural conservation, and its unique phylogenetic distribution, suggest that OLE RNA carries out a complex and critical function only in certain extremophilic bacteria.
Phosphorylation of the ATP-binding loop directs oncogenicity of drug-resistant BCR-ABL mutants
Authors: Skaggs Brian J. , Gorre Mercedes E. , Ryvkin Ann , Burgess Michael R. , Xie Yongming , Han Yun , Komisopoulou Evangelia , Brown Lauren M. , Loo Joseph A. , Landaw Elliot M. , Sawyers Charles L. , Graeber Thomas G.
Published: December 2006

The success of targeting kinases in cancer with small molecule inhibitors has been tempered by the emergence of drug-resistant kinase domain mutations. In patients with chronic myeloid leukemia treated with ABL inhibitors, BCR-ABL kinase domain mutations are the principal mechanism of relapse. Certain mutations are occasionally detected before treatment, suggesting increased fitness relative to wild-type p210 BCR-ABL. We evaluated the oncogenicity of eight kinase inhibitor-resistant BCR-ABL mutants and found a spectrum of potencies greater or less than p210. Although most fitness alterations correlate with changes in kinase activity, this is not the case with the T315I BCR-ABL mutation that confers clinical resistance to all currently approved ABL kinase inhibitors. Through global phosphoproteome analysis, we identified a unique phosphosubstrate signature associated with each drug-resistant allele, including a shift in phosphorylation of two tyrosines (Tyr
253
and Tyr
257
) in the ATP binding loop (P-loop) of BCR-ABL when Thr
315
is Ile or Ala. Mutational analysis of these tyrosines in the context of Thr
315
mutations demonstrates that the identity of the gatekeeper residue impacts oncogenicity by altered P-loop phosphorylation. Therefore, mutations that confer clinical resistance to kinase inhibitors can substantially alter kinase function and confer novel biological properties that may impact disease progression.
Global mammal distributions, biodiversity hotspots, and conservation
Authors: Ceballos Gerardo , Ehrlich Paul R.
Published: December 2006

Hotspots, which have played a central role in the selection of sites for reserves, require careful rethinking. We carried out a global examination of distributions of all nonmarine mammals to determine patterns of species richness, endemism, and endangerment, and to evaluate the degree of congruence among hotspots of these three measures of diversity in mammals. We then compare congruence of hotspots in two animal groups (mammals and birds) to assess the generality of these patterns. We defined hotspots as the richest 2.5% of cells in a global equal-area grid comparable to 1° latitude × 1° longitude. Hotspots of species richness, “endemism,” and extinction threat were noncongruent. Only 1% of cells and 16% of species were common to the three types of mammalian hotspots. Congruence increased with increases in both the geographic scope of the analysis and the percentage of cells defined as being hotspots. The within-mammal hotspot noncongruence was similar to the pattern recently found for birds. Thus, assigning global conservation priorities based on hotspots is at best a limited strategy.
High-sensitivity detection of TNT
Authors: Pushkarsky Michael B. , Dunayevskiy Ilya G. , Prasanna Manu , Tsekoun Alexei G. , Go Rowel , Patel C. Kumar N.
Published: December 2006

We report high-sensitivity detection of 2,4,6-trinitrotoluene (TNT) by using laser photoacoustic spectroscopy where the laser radiation is obtained from a continuous-wave room temperature high-power quantum cascade laser in an external grating cavity geometry. The external grating cavity quantum cascade laser is continuously tunable over ≈400 nm around 7.3 μm and produces a maximum continuous-wave power of ≈200 mW. The IR spectroscopic signature of TNT is sufficiently different from that of nitroglycerine so that unambiguous detection of TNT without false positives from traces of nitroglycerine is possible. We also report the results of spectroscopy of acetylene in the 7.3-μm region to demonstrate continuous tunability of the IR source.
Challenging collective violence: A scientific strategy
Authors: Mattaini Mark A. , Strickland Joseph
Published: December 2006

Collective violence (war, terrorism, violent political conflicts, genocide, repression, organized criminal activity, disappearances, torture, and a range of other abuses of human rights) killed at least 200 million persons directly or indirectly, and injured many more, during the 20th century (Krug, Dahlberg, Mercy, Zwi, & Lozano, 2002). Recent advances in the science of behaviour can help to explain why humans turn so quickly to collective violent actions in response to threat or opportunity, and why such actions are in a real sense “natural.” However, in the contemporary world the potential costs of relying on these nearly automatic responses are unacceptably high. This paper explores the roots of this violence from the perspective of the natural science of behaviour. Strategies for modifying collective violence should take into consideration motivational factors such as verbal processes and cultural perceptions, shifting motivating antecedents, etc. Rules, models, and structural conditions are also relevant. The potential contribution of behaviour science in changing collective violence is very important. The analysis suggests that policy‐makers often rely on responses and preventive strategies that are inherently weak or counterproductive, and often politically manipulated. Potentially more powerful strategies, meanwhile, remain largely unrecognized. Programs of research that expand strategic options could meaningfully contribute to human well‐being, but pursuing this work will require courageous scholarship conducted in solidarity with those at risk.
Recombinative generalization: Some theoretical and practical remarks
Authors: Suchowierska Monika
Published: December 2006

Aprimary goal of behavioural interventions aimed at teaching skills is to establish generative responding. Recombinative generalization, which has been defined as the demonstration of novel arrangements of previously established linguistic units, is a process involved in generative responding. Successful recombinations contribute to the development of a functional, not rote, language repertoire that often generalizes across stimuli, responses, and time. Although research on recombinative generalization began some 80 years ago, understanding of this process is still not complete. Furthermore, programming for successful recombinations when teaching language and reading to typically and not‐typically developing children is still minimal. The early recombinative generalization studies worked on a “miniature linguistic system”; the referential stimuli (words) were arranged in a pattern that included all possible combinations of the dimensions of interest. Matrix training approaches to recombinative generalization showed how to produce functional language. In the present paper, I will (1) review research on recombinative generalization, (2) discuss conditions necessary for successful recombinations, and (3) make suggestions for practice relating to recombinative generalization. The discrimination required for successful recombinations fits well in the definition of “abstraction”: a discrimination based on a single property of a stimulus, independent of other properties; thus, generalization to other stimuli with that property. Abstraction is demonstrated when an individual correctly identifies untrained stimuli based on property of interest. Recombinative generalization contributes to achieving functional language. Further research on recombinative generalization will broaden the understanding of basic processes and their application to teaching language and early literacy skills.
Training parents and professionals to help children with autism in China: The contribution of behaviour analysis
Authors: Yanqing Guo
Published: December 2006

Atraining programme is presented with two parts. (1) Professional training is received by graduate students at the Institute for Mental Health of Beijing University, based on the principles of behaviour assessment and modification, radical behaviourism, and applied research methods. (2) Parent training focused on parents with autistic children, using the behaviour analysis and modification methods. China has between 400,000 and 800,000 children with autism. In comparison to its fast economic growth the development of social welfare and social insurance systems are far behind. Once the child is diagnosed with autism, the parents or the primary caregivers of the child, not the government or the community, take the responsibility for the child's rehabilitation. The diagnosis of autism was first introduced in China in 1982, and for years the work was based on clinical appearances and diagnosis. The main mission of child psychiatrists was early diagnosis, but there was little change obtained with autistic children. From the year 2000 more people were interested in rehabilitation rather than in diagnosis and medical treatments. Behaviour analysis methods are now extensively used in interventions in children with autism in this country. There is a great need in China for this kind of work, but there are few professionals with the appropriate scientific knowledge and skills to work with autistic children. These professionals will help to further develop the area of behaviour analysis in China.
Operant conditioning and errorless learning procedures in the treatment of chronic aphasia
Authors: Sigurðardóttir Zuilma Gabriela , Sighvatsson Magnús Blöndahl
Published: December 2006

In the field of aphasia, the processes that enable improvements in fluent speech, e.g., in naming, reading, sentence structure, etc., are not well understood. At the present time the fields of cognitive psychology, clinical neuropsychology, and cognitive neuropsychology are limited with regard to explaining the causes of different symptoms of aphasia. Treatment based on operant conditioning or stimulus control procedures seems to be very promising. In the present study, four participants with chronic aphasia, aged between 52 and 62 years, received treatment based on errorless learning procedures and operant conditioning for 7 months. Treatment effects were evaluated with a multiple‐baseline design across behaviours. The performances that were treated varied across participants but were two or three of the following in each case: naming people or objects, making sentences, sequencing stimuli, discriminating written words, and unassisted recall. Treatment variables were clearly defined and systematically used in standard ways across participants with flexibility for adaptation to individual outcomes using clearly defined criteria. Prompts that were used in training faded out as performances improved. The performances of all participants improved significantly in all tasks; they all reached 100% correct performance without any prompts from the experimenter in at least one task. Generalization measures across stimuli and settings demonstrated that their improved performances generalized to novel stimuli and novel settings.
Addressing organizational complexity: A behavioural systems analysis application to higher education
Authors: Malott Maria E. , Martinez Wilfredo Salas
Published: December 2006

Countless demonstrations across a variety of settings have shown how behaviour analysis can alter the behaviour of individuals by manipulating behavioural contingencies. However, changing organizations is more complex than changing specific behaviours. Organizations involve different units of analysis and require distinct interventions. This article describes a higher education change initiative based on a behavioural systems analysis approach. The work was carried out at the National Pedagogical University at Veracruz (México). This large institution presented significant problems, as well as low productivity: enrolment was declining, programs were outdated, and complaints about the administrative processes were frequent. Three types of complexity were analysed: environmental, hierarchical, and component. From the analysis, four improvement strategies were identified and implemented: (1) the incorporation of adult literacy training at the macro system level to attend to the high adult illiteracy and the academic failure of children; (2) the addition of various options to the thesis requirement at the organizational level to increase graduation rate; (3) the development of new programs at the process level to combat the downward enrolment trend; and (4) the re‐engineering of the student‐centred administrative processes, also at the process level, to tackle the inefficient administration. The designed procedures were partially implemented with great success. This case study points out the application of behaviour analysis to the organizational level.
Metropolitan Out-migration in England and Wales, 1980-81
Authors: Boyle Paul
Published: December 2006

A Poisson regression approach is used to model the out-migration from metropolitan districts in England and Wales down the urban hierarchy using flow data extracted from the 1981 British Census. Particular attention is focused upon the counter-urbanisation debate and an original classification of districts is used to examine the extent to which migrants originating in metropolitan origins choose peripheral destinations. The study also distinguishes between origins and destinations in the north and south of England and Wales. It is shown that the extent of population decentralisation from metropolitan districts varies considerably between inner and outer metropolitan areas, that migration down the urban hierarchy is an important feature of population redistribution and that flows into the periphery are primarily a southern phenomenon emanating principally from outer London.