bluuebunny/crossref_metadata_2025 huggingface dataset:
c-Cbl and Cbl-b ubiquitin ligases: substrate diversity and the negative regulation of signalling responses
Authors: Thien Christine B. F. , Langdon Wallace Y.
Published: February 2006

The activation of signalling pathways by ligand engagement with transmembrane receptors is responsible for determining many aspects of cellular function and fate. While these outcomes are initially determined by the nature of the ligand and its receptor, it is also essential that intracellular enzymes, adaptor proteins and transcription factors are correctly assembled to convey the intended response. In recent years, it has become evident that proteins that regulate the amplitude and duration of these signalling responses are also critical in determining the function and fate of cells. Of these, the Cbl family of E3 ubiquitin ligases and adaptor proteins has emerged as key negative regulators of signals from many types of cell-surface receptors. The array of receptors and downstream signalling proteins that are regulated by Cbl proteins is diverse; however, in most cases, the receptors have a common link in that they either possess a tyrosine kinase domain or they form associations with cytoplasmic PTKs (protein tyrosine kinases). Thus Cbl proteins become involved in signalling responses at a time when PTKs are first activated and therefore provide an initial line of defence to ensure that signalling responses proceed at the desired intensity and duration.
Phenotypic analysis of trypanothione synthetase knockdown in the African trypanosome
Authors: Ariyanayagam Mark R. , Oza Sandra L. , Guther Maria Lucia S. , Fairlamb Alan H.
Published: February 2006

Trypanothione plays a pivotal role in defence against chemical and oxidant stress, thiol redox homoeostasis, ribonucleotide metabolism and drug resistance in parasitic kinetoplastids. In Trypanosoma brucei, trypanothione is synthesized from glutathione and spermidine by a single enzyme, TryS (trypanothione synthetase), with glutathionylspermidine as an intermediate. To examine the physiological roles of trypanothione, tetracycline-inducible RNA interference was used to reduce expression of TRYS. Following induction, TryS protein was reduced >10-fold and growth rate was reduced 2-fold, with concurrent 5–10-fold decreases in glutathionylspermidine and trypanothione and an up to 14-fold increase in free glutathione content. Polyamine levels were not significantly different from non-induced controls, and neither was the intracellular thiol redox potential, indicating that these factors are not responsible for the growth defect. Compensatory changes in other pathway enzymes were associated with prolonged suppression of TryS: an increase in trypanothione reductase and γ-glutamylcysteine synthetase, and a transient decrease in ornithine decarboxylase. Depleted trypanothione levels were associated with increases in sensitivity to arsenical, antimonial and nitro drugs, implicating trypanothione metabolism in their mode of action. Escape mutants arose after 2 weeks of induction, with all parameters, including growth, returning to normal. Selective inhibitors of TryS are required to fully validate this novel drug target.
High-affinity interaction of the N-terminal myristoylation motif of the neuronal calcium sensor protein hippocalcin with phosphatidylinositol 4,5-bisphosphate
Authors: O'Callaghan Dermott W. , Haynes Lee P. , Burgoyne Robert D.
Published: February 2006

Many proteins are associated with intracellular membranes due to their N-terminal myristoylation. Not all myristoylated proteins have the same localization within cells, indicating that other factors must determine their membrane targeting. The NCS (neuronal calcium sensor) proteins are a family of Ca2+-binding proteins with diverse functions. Most members of the family are N-terminally myristoylated and are either constitutively membrane-bound or have a Ca2+/myristoyl switch that allows their reversible membrane association in response to Ca2+ signals. In the case of hippocalcin and NCS-1, or alternatively KChIP1 (K+ channel-interacting protein 1), their N-terminal myristoylation motifs are sufficient for targeting to distinct organelles. We have shown that an N-terminal myristoylated hippocalcin peptide is able to specifically reproduce the membrane targeting of hippocalcin/NCS-1 when introduced into permeabilized cells. The peptide binds to liposomes containing phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] with high affinity (Kd 50 nM). Full-length hippocalcin also bound preferentially to liposomes supplemented with PtdIns(4,5)P2. Co-expression of hippocalcin-(1–14)–ECFP (enhanced cyan fluorescent protein) or NCS-1–ECFP partially displaced the expressed PH (pleckstrin homology) domain of phospholipase δ1 from the plasma membrane in live cells, indicating that they have a higher affinity for PtdIns(4,5)P2 than does this PH domain. The Golgi localization of the PH domain of FAPP1 (four-phosphate-adaptor protein 1), which binds to phosphatidylinositol 4-phosphate, was unaffected. The localization of NCS-1 and hippocalcin is likely to be determined, therefore, by their interaction with PtdIns(4,5)P2.
Neutrophil gelatinase-associated lipocalin as a survival factor
Authors: Tong Zhimin , Wu Xuli , Ovcharenko Dmitriy , Zhu Jiuxiang , Chen Ching-Shih , Kehrer James P.
Published: February 2006

NGAL (human neutrophil gelatinase-associated lipocalin) and its mouse analogue 24p3 are members of the lipocalin family of small secreted proteins. These proteins are up-regulated in a number of pathological conditions, including cancers, and may function as transporters of essential factors. Although previous publications have suggested that 24p3 has pro-apoptotic functions, other data are more suggestive of a survival function. The current study was designed to determine whether NGAL is pro- or anti-apoptotic. Apoptosis induced in human adenocarcinoma A549 cells by the 5-lipoxygenase-activating-protein inhibitor MK886, or several celecoxib-derived PDK1 (phosphoinositide-dependent kinase 1) inhibitors that are devoid of cyclo-oxygenase-2 inhibitory activity, was accompanied by a dose- and time-dependent increase of NGAL mRNA levels, as was reported previously with 24p3. A similar induction of NGAL mRNA was observed in human breast cancer MCF7 cells treated with MK886, indicating this was not a cell-specific effect. Treatment of A549 cells with up to 150 μg/106 cells of purified recombinant NGAL protein had no effect on viability, whereas antisera against the full-length NGAL protein induced apoptosis in these cells. The stable overexpression of NGAL in A549 cells had no effect on proliferation or viability. However, the cell death induced by a PDK1 inhibitor was reduced by 50% in NGAL-overexpressing cells. Decreasing NGAL mRNA and protein expression with siRNA (small interfering RNA) in A549 cells increased the toxicity of a PDK1 inhibitor by approx. 45%. These data indicate that, although the induction of NGAL correlates with apoptosis, this induction represents a survival response. Because NGAL is a secreted protein, it may play an extracellular role in cell defence against toxicants and/or facilitate the survival of the remaining cells.
Regulation of mitosis by poly(ADP-ribosyl)ation
Authors: Compton Duane A.
Published: February 2006

The spindle is a dynamic, microtubule-based structure responsible for chromosome segregation during cell division. Spindles in mammalian cells contain several thousand microtubules that are arranged into highly symmetric bipolar arrays by the actions of numerous microtubule-associated motor and non-motor proteins. In addition to these protein constituents, recent work has demonstrated that poly(ADP-ribose) is a key spindle component. Of the multitude of poly(ADP-ribose) polymerase proteins encoded in the genome, tankyrase 1 appears to be the primary enzyme responsible for building poly(ADP-ribose) in spindles during mitosis. In this issue of the Biochemical Journal, Susan Smith and co-workers show that the primary target of tankyrase 1 in dividing cells is NuMA (nuclear mitotic apparatus protein), a protein that cross-links microtubule ends at spindle poles. The impact of poly(ADP-ribosyl)ation on the biochemical function of NuMA remains murky at this time, but these new results represent the first step to clearing the view as to how poly(ADP-ribosyl)ation regulates cell division.
Q-S (complete or anticipated) synchronization backstepping scheme in a class of discrete-time chaotic (hyperchaotic) systems: A symbolic-numeric computation approach
Authors: Yan Zhenya
Published: February 2006

First, a type of Q-S (complete or anticipated) synchronization is defined in discrete-time dynamical systems. Second, based on backstepping design with a scalar controller, a systematic, concrete and automatic scheme is presented to investigate Q-S (complete or anticipated) synchronization between the discrete-time drive system and response system with strict-feedback form. Finally, the proposed scheme is used to illustrate Q-S (complete or anticipated) synchronization between the two-dimensional discrete-time Lorenz system and Fold system, as well as the three-dimensional hyperchaotic discrete-time Rössler system and generalized discrete-time Rössler system. Moreover numerical simulations are used to verify the effectiveness of the proposed scheme. Our scheme can be also extended to investigate Q-S (complete or anticipated) synchronization between other discrete-time dynamical systems with strict-feedback forms. With the aid of symbolic-numeric computation, the scheme can be performed to yield automatically the scalar controller and to verify its effectiveness in computer.
Development of modulated rf sequences for decoupling and recoupling of nuclear-spin interactions in sample-spinning solid-state NMR: Application to chemical-shift anisotropy determination
Authors: Nishiyama Yusuke , Yamazaki Toshio , Terao Takehiko
Published: February 2006

An approach to design modulated rf sequences under sample spinning which decouple/recouple a specific nuclear-spin interaction in solid-state NMR is presented. The Euler angles of the spin rotation caused by a general rf field are forced to fulfill the symmetry principle theory for selecting an interaction of interest. Then, modulated rf sequences are directly obtained from the Euler angles with a large degree of freedom. rf sequences with high performance can be selected from them by numerically optimizing rf sequence parameters. As an example of this approach, an amplitude- and phase-modulated rf sequence to recouple chemical-shift anisotropy (CSA) is developed, which is robust with respect to rf inhomogeneity. Two-dimensional (2D) experiments with this rf sequence under on and off magic-angle spinning (MAS) provide one-dimensional and 2D powder patterns, respectively. The latter enables us to determine the CSA principal values more accurately even for overlapped signals in MAS spectra. The effectiveness of this modulated rf sequence is experimentally demonstrated on [N15]-N-acetyl-D,L-alanine for determination of the N15 and CO13 CSA principal values.
Density-matrix calculation of surface-enhanced Raman scattering for p-mercaptoaniline on silver nanoshells
Authors: Gibson Joshua W. , Johnson Bruce R.
Published: February 2006

A theoretical analysis of recent experiments measuring the 782nm surface-enhanced Raman scattering of p-mercaptoaniline bound to silver nanoshells of different core and shell radii [J. B. Jackson and N. J. Halas, Proc. Natl. Acad. Sci. U.S.A. 101, 17930 (2004)] is performed. Electronic structure Hartree-Fock and density-functional theory calculations for Ag salts of p-mercaptoaniline are used to characterize observed vibrational modes and configuration-interaction singles calculations are carried out to examine excited states. Multimode vibronic density-matrix calculations are then made including one excited electronic state, using a classical description of the strong local fields and a phenomenological treatment of relaxations. The spectral behavior as a function of both nanoshell surface-plasmon resonance position and molecular electronic spacing is examined.
Multistate multimode vibronic dynamics: Entanglement of electronic and vibrational degrees of freedom in the benzene radical cation
Authors: Bâldea Ioan , Köppel Horst
Published: February 2006

An earlier theoretical treatment of multimode and multistate vibronic coupling in the benzene radical cation [Köppel et al., J. Chem. Phys. 117, 2657 (2002)] is extended to investigate also the behavior of the nuclear degrees of freedom and to include additional electronic states. The five lowest doublet electronic states are considered which have been shown earlier to be all interconnected through a series of conical intersections of their potential-energy surfaces. In the most extensive calculations, they are all included simultaneously in the quantum dynamical calculations performed, which represent a system of unprecedented complexity treated in this way. The results are compared with various reduced-dimensionality treatments (i.e., employing reduced vibrational and electronic function spaces). The different temporal behavior of the various electronic populations is emphasized and traced to the different locations of the various seams of conical intersections: due to the coherent oscillations of the time-dependent wave packet this leads to an oscillatory behavior in some cases and to monotonous behavior in others. A seemingly irreversible behavior of the system dynamics in this strictly microscopic treatment is confirmed. The importance of this benchmark system to highlight complex, entangled multimode, and multistate vibronic dynamics is pointed out.
Covariant canonical formalism for four-dimensional BF theory
Authors: Mondragón Mauricio , Montesinos Merced
Published: February 2006

The covariant canonical formalism for four-dimensional BF theory is performed. The aim of the paper is to understand in the context of the covariant canonical formalism both the reducibility that some first class constraints have in Dirac’s canonical analysis and also the role that topological terms play. The analysis includes also the cases when both a cosmological constant and the second Chern character are added to the pure BF action. In the case of the BF theory supplemented with the second Chern character, the presymplectic 3-form is different to the one of the BF theory in spite of the fact both theories have the same equations of motion while on the space of solutions they both agree to each other. Moreover, the analysis of the degenerate directions shows some differences between diffeomorphisms and internal gauge symmetries.
Knotting of random ring polymers in confined spaces
Authors: Micheletti C. , Marenduzzo D. , Orlandini E. , Summers D. W.
Published: February 2006

Stochastic simulations are used to characterize the knotting distributions of random ring polymers confined in spheres of various radii. The approach is based on the use of multiple Markov chains and reweighting techniques, combined with effective strategies for simplifying the geometrical complexity of ring conformations without altering their knot type. By these means we extend previous studies and characterize in detail how the probability to form a given prime or composite knot behaves in terms of the number of ring segments N and confining radius R. For 50⩽N⩽450 we show that the probability of forming a composite knot rises significantly with the confinement, while the occurrence probability of prime knots are, in general, nonmonotonic functions of 1∕R. The dependence of other geometrical indicators, such as writhe and chirality, in terms of R and N is also characterized. It is found that the writhe distribution broadens as the confining sphere narrows.
The nuclear-spin-rotation constants of HCY, HSiY, and SiY2 (Y=F, Cl): Anab initiostudy
Authors: Rizzo Antonio , Puzzarini Cristina , Coriani Sonia , Gauss Jürgen
Published: February 2006

The nuclear-spin-rotation constants of fluoro- (HCF) and chloro- (HCCl) carbene, of the corresponding silylenes (HSiF and HSiCl), and of difluoro- and dichlorosilylene (SiF2 and SiCl2) are quantum-chemically investigated employing the coupled-cluster singles and doubles model augmented by a perturbative treatment of triple excitations together with various sequences of correlation-consistent basis sets. Theoretical best estimates are obtained through consideration of corrections for core correlation and of zero-point vibrational contributions. In addition, nuclear quadrupole coupling constants for the chlorine containing species are determined. A thorough comparison with experiment is made.
First-principles density-functional theory calculations of electron-transfer rates in azurin dimers
Authors: Migliore A. , Corni S. , Di Felice R. , Molinari E.
Published: February 2006

We have conceived and implemented a new method to calculate transfer integrals between molecular sites, which exploits few quantities derived from density-functional theory electronic structure computations and does not require the knowledge of the exact transition state coordinate. The method uses a complete multielectron scheme, thus including electronic relaxation effects. Moreover, it makes no use of empirical parameters. The computed electronic couplings can then be combined with estimates of the reorganization energy to evaluate electron-transfer rates that are measured in kinetic experiments: the latter are the basis to interpret electron-transfer mechanisms. We have applied our approach to the study of the electron self-exchange reaction of azurin, an electron-transfer protein belonging to the family of cupredoxins. The transfer integral estimates provided by the proposed method have been compared with those resulting from other computational techniques, from empirical models, and with available experimental data.
Entropy theory of polymer glass formation revisited. I. General formulation
Authors: Dudowicz Jacek , Freed Karl F. , Douglas Jack F.
Published: February 2006

A generalized entropy theory of glass formation is developed by merging the lattice cluster theory for the thermodynamics of semiflexible polymer melts at constant pressure with the Adam-Gibbs relation between the structural relaxation time and the configurational entropy. Since experimental studies have suggested that the relative rigidity of the chain backbone and the side groups is an essential parameter governing the nature of glass formation in polymers, we incorporate this rigidity disparity parameter, along with monomer structure, into our new theoretical description of the polymer fluid thermodynamics. Our entropy theory is compared with alternative theories that describe the rate of structural relaxation in glass-forming liquids in terms of an activated rate process.
Intersublevel polaron laser with InAs∕GaAs self-assembled quantum dots
Authors: Sauvage S. , Boucaud P.
Published: February 2006

We propose a three-level scheme to achieve intersublevel population inversion, optical gain, and intersublevel lasing effect in n-doped InAs∕GaAs self-assembled quantum dots under optical pumping. The proposed Ruby-type laser scheme uses the natural splitting of the s-p polaron intersublevel transitions around 25μm wavelength. The relaxation time engineering, which leads to optical gain in the system, relies (i) on the slow polaron relaxation from the P− state down to the S ground state, governed by the specific strong coupling regime for the electron-phonon Fröhlich interaction and (ii) on the fast nonradiative relaxation of the polaron between the P+ and P− levels through the irreversible emission of acoustic phonons. TE-polarized optical gain up to 330cm−1 is calculated for 80 quantum dot planes in an in-plane monomode waveguide geometry and a laser pump intensity threshold as low as 930W∕cm2, two orders of magnitude smaller than for quantum wells, is predicted.
Phase separation and dilution in implanted MnxGe1−x alloys
Authors: Ottaviano L. , Passacantando M. , Picozzi S. , Continenza A. , Gunnella R. , Verna A. , Bihlmayer G. , Impellizzeri G. , Priolo F.
Published: February 2006

The structural and electronic properties of MnxGe1−x alloys (x⩽0.15) fabricated by ion implantation are investigated by means of x-ray diffraction and synchrotron radiation photoemission spectroscopy. The diffraction patterns point to the presence of ferromagnetic Mn5Ge3 nanoparticles; however, valence band spectra, interpreted by means of accurate ab initio calculations including Hubbard-like correlations, show clear fingerprints of an effective substitutional Mn dilution in the Ge semiconducting host.
Leakage suppression by asymmetric area electrodes in metal-semiconductor-metal photodetectors
Authors: Okyay Ali K. , Chui Chi On , Saraswat Krishna C.
Published: February 2006

We have studied the effect of varying electrode area asymmetry on the leakage behavior of metal-semiconductor-metal photodetectors (MSM-PDs). We demonstrate, an effective suppression of dark current (Idark) with the application of asymmetric electrode area and appropriate biasing scheme in MSM-PDs. More than 2× reduction in Idark is obtained in photodetectors fabricated on silicon. Photoresponse of these detectors have also been monitored and normalized photo-to-dark current ratio (NPDR) metric is utilized for objective assessment of detector performance. Significant enhancement in NPDR is shown to be accomplished with the asymmetric Si MSM-PDs.
Crack-free GaN∕AlN distributed Bragg reflectors incorporated with GaN∕AlN superlattices grown by metalorganic chemical vapor deposition
Authors: Huang G. S. , Lu T. C. , Yao H. H. , Kuo H. C. , Wang S. C. , Lin Chih-Wei , Chang Li
Published: February 2006

A crack-free GaN∕AlN distributed Bragg reflector (DBR) incorporated with GaN∕AlN superlattice (SL) layers was grown on a c-plane sapphire substrate by metalorganic chemical vapor deposition. Three sets of half-wave layers consisting of 5.5 periods of GaN∕AlN SL layers and GaN layer were inserted in every five pairs of the 20 pair GaN∕AlN DBR structure to suppress the crack generation. The grown GaN∕AlN DBRs with SL insertion layers showed no observable cracks in the structure and achieved high peak reflectivity of 97% at 399nm with a stop band width of 14nm. Based on the x-ray analysis, the reduction in the in-plane tensile stress in the DBR structure with insertion of SL layers could be responsible for the suppression of crack formation and achievement of high reflectivity.
Shapiro steps observed in annular intrinsic Josephson junctions at low microwave frequencies
Authors: Wang H. B. , Kim S. M. , Urayama S. , Nagao M. , Hatano T. , Arisawa S. , Yamashita T. , Wu P. H.
Published: February 2006

With annular intrinsic Josephson junctions structured from a slice of Bi2Sr2CaCu2O8+δ single crystal 200nm thick, we have devised a way to inject fluxons into the junctions only by sweeping the bias current. The stacks have shown typical properties concerning Josephson fluxon conservation. These annular junctions are sensitive to microwave irradiation, and quite sharp Shapiro steps have been observed at ∼20GHz which is much lower than the plasma frequency of the junctions, indicating many applications can be possible with practically accessible microwave sources.
Low-threshold and narrow-linewidth lasing from dye-doped holographic polymer-dispersed liquid crystal transmission gratings
Authors: Liu Y. J. , Sun X. W. , Shum P. , Li H. P. , Mi J. , Ji W. , Zhang X. H.
Published: February 2006

Optically pumped lasing with low threshold and narrow linewidth was observed in a 4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran dye-doped holographic polymer-dispersed liquid crystal transmission grating structure. The results showed that the lasing peak centered at about 609 nm, with a full width at half maximum of about only 1.8 nm. The threshold pumping intensity was about 120μJ under the excitation of a frequency-doubled Nd:yttrium–aluminum–garnet laser operating at a wavelength of 532 nm. Theoretical calculation showed that the lasing from this structure happened at the band edge of the photonic band gap. The lasing modes were also investigated. The transmission grating investigated enjoys a much larger gain length compared to the reflection one.
Directed vertical alignment liquid crystal display with fast switching
Authors: Gu Mingxia , Smalyukh Ivan I. , Lavrentovich Oleg D.
Published: February 2006

We describe a directed vertical alignment (VA) display mode based on a nematic liquid crystal (LC) doped with a chiral dopant and confined between two substrates, one of which is pretreated, say, by unidirectional rubbing or photoalignment. The design allows one to eliminate umbilical defects that appear during switching of the conventional VA cells and thus to obtain better contrast. Switching is ∼30% faster than for VA cells when optimized concentration of a chiral dopant is added and LC molecules at one of the substrates are slightly tilted from the cell normal due to the unidirectional surface treatment.
Spiral springs and microspiral springs for chemical and biological sensing
Authors: Ji Hai-Feng , Lu Yanqing , Du Hongwei , Xu Xiaohe , Thundat Thomas
Published: February 2006

This work demonstrates that a mechanical device based on spiral spring or microspiral spring has a broad range of applications for detection of chemical and biological species. The surface stress changes or polymer volume changes on one side of the spiral spring extend or contract a spiral spring. The macrosize spiral spring can be used for power-free sensor development.
Phase-conjugate mirror via two-photon thermal light imaging
Authors: Scarcelli Giuliano , Berardi Vincenzo , Shih Yanhua
Published: February 2006

We report on a two-photon imaging experiment in which a thermal light source behaves like a phase-conjugate mirror, which produces a real image of an object. The result offers a novel scheme of imaging and thus suggests useful applications.
Demonstration of a radiation resistant, high efficiency SiC betavoltaic
Authors: Eiting C. J. , Krishnamoorthy V. , Rodgers S. , George T. , Robertson J. David , Brockman John
Published: February 2006

A SiC p-i-n junction betavoltaic was fabricated, and electrical power output under irradiation from an 8.5GBq P33 source was monitored over a period of four half-lives of the radioisotope. The open-circuit voltage (VOC) of the device was 2.04±0.02V, and the peak power (Pout) was 0.58±0.02μW (2.1±0.2μW∕cm2) at 1.60V. The conversion efficiency (ηconv) was 4.5%±0.3% and the normalized power output indicates no device degradation over more than 3months (four half-lives of the source).
Factors identifying pigs predisposed to tail biting
Authors: Beattie V. E. , Breuer K. , O'Connell N. E. , Sneddon I. A. , Mercer J. T. , Rance K. A. , Sutcliffe M. E. M. , Edwards S. A.
Published: February 2006

Approximately 5% of pigs slaughtered in the UK have been tail-bitten, leading to welfare and production issues. Tail biting is sporadic and not all pigs tail bite. The aim of this study was to identify factors that are common in pigs that perform tail-biting behaviour, and that might be used in a predictive way to identify such animals.

The behaviour of 159 pigs was observed in the post-weaning period. Pigs were weaned at 4 weeks of age. In the week prior to weaning and at 6 weeks of age each pig was individually tested in a tail chew test (tail chew test 1 and 2, respectively). The tail chew test involved recording the pig's behaviour directed towards two ropes, one of which had been soaked in saline solution and the other not. The production performance of the pigs was recorded from birth to 7 weeks of age. Time spent performing tail-biting behaviour correlated positively with time in contact with the rope in tail chew test 2 (r= 0·224,P< 0·05), and time spent ear biting correlated positively with time spent in rope directed behaviour in tail chew test 1 (r= 0·248,P< 0·01). Pigs that spent as much as 1·5% of their time of more performing tail-biting behaviour were lighter at weaning (26 days) and tended to be lighter at 7 weeks of age compared with pigs that spent less than 1·5% of their time performing tail-biting behaviour (weaning weight: ≥1·5% tail biting 8·96 kg, <1·5% tail biting 9·67 kg,P< 0·05; 7-week weight: ≥1·5% tail biting 15·75 kg, <1·5% tail biting 17·09 kg,P< 0·08). There was no significant difference in birth weight between pigs that spent ≥ or <1·5% of their time performing tail-biting behaviour. Pigs that spent 1·5% of their time or more performing tail-biting behaviour showed significantly lower growth rates between birth and weaning (≥1·5% tail biting 260 g/day, <1·5% tail biting 285 g/day,P< 0·05) but not between weaning and 7 weeks of age (≥1·5% tail biting 343 g/day, <1·5% tail biting 365 g/day,P> 0·05).

The results suggest that pigs that tail bite have some nutritional deficiency that results in performance of foraging behaviour that is expressed in intensive housing as ear/tail biting.
Comparing two concentrate allowances in an automatic milking system
Authors: Halachmi I. , Ofir S. , Miron J.
Published: February 2006

This study investigated the potential for applying an automatic milking system (AMS) to the management of high-yielding cows offered a total mixed ration (TMR). The null hypothesis was that it is desirable to maintain even in AMS, the TMR feeding management practice recommended for high-yielding cows and therefore it can be attained by ‘reducing the concentrate allocation in the robot without reducing the number of milkings’. Two feeding regimes were used: the ‘candy concept’, with only 1·2 kg of food concentrate – the minimum to attract the cow – provided at each visit to the milking robot; and the provision of a maximum of 7 kg of food concentrate per day. Approximately 100 cows were subjected to one or other of these two treatments. Although the cows in the first treatment consumed approximately 3·5 kg of concentrate per day and those in the second treatment approximately 5 kg per day, no significant differences were observed in the numbers of voluntary milkings.
Effects of diet calcium: phosporus ratio and metabolizable energy content on development of osteochondrosis, foot bending and performance in blue foxes
Authors: Korhonen H. T. , Happo M. , Rekilä T. , Valaja J. , Pölönen I.
Published: February 2006

Abstract The study evaluates the effects of two dietary Ca: P ratios (1·5: 1v. 2·5: 1) and metabolizable energy (ME) contents (17·3 MJ/kg dry matter (DM)v. 19·2 MJ/kg DM) on the development of osteochondrosis, foot bending and performance in juvenile male blue foxes (Alopex lagopus). Four experimental groups (no. = 10 per group) were formed : (1) low energy, lagopus). low Ca: P (LELC); (2) normal energy, low Ca: P (NELC); (3) low energy, normal Ca: P (LENC); and (4) normal energy, normal Ca: P (NENC). The experiment started at weaning in mid July and finished in early October. From mid August onwards, animals on the normal energy diets (NELC, NENC) grew significantly faster (P< 0·001) than animals on the low energy diets (LELC, LENC). The final body weights of the normal energy groups were 1·5 kg higher than those of the low energy groups (P< 0·001). The dietary Ca: P ratio did not affect live-weight gain. Foot bending increased significantly from summer to autumn (P< 0·001). Changes in foot bending between initial and final evaluations showed that bending was significantly greater (P< 0·05) in animals on normal energy (NELC, NENC) than on low energy diets (LELC, LENC). Significant differences were not found in the mean degree of damage in foot and cartilage between the groups. Ulna breaking strength was significantly higher (P< 0·05) in normal energy (NELC, NENC) than in low energy (LELC, LENC) animals. Ulna calcium and phosphorus concentrations of the normal Ca: P (LENC, NENC) groups were significantly higher (P< 0·001,P< 0·05) than those of the lower Ca: P (LELC, NELC) groups. The bone (ulna) calcium and phosphorus concentrations tended to be higher in the normal energy (NELC, NENC) than in the low energy (LELC, LENC) groups (calciumP= 0·07; phosphorusP= 0·06). The bone Ca: P ratio was higher (P< 0·001) in the normal (LENC, NENC) than in the low Ca: P diet (LELC, NELC) animals. The carcass weights of normal energy animals (NELC, NENC) were significantly higher (P< 0·001) than those of low energy (LELC, LENC) animals. The fat : dry matter ratio was higher (P< 0·05) in normal (NELC, NENC) than in low energy (LELC, LENC) carcasses. We conclude that the Ca: P ratio of the diet has no effect on the development of osteochondrosis or bending of the foot. The higher body weight caused by normal as opposed to low metabolizable energy content seems, however, to increase the incidence of foot bending.
Effects of age and breed of beef bulls on growth parameters, carcass and muscle characteristics
Authors: Jurie C. , Martin J.-F. , Listrat A. , Jailler R. , Culioli J. , Picard B.
Published: February 2006

The effects of age and breed on growth parameters, carcass and muscle characteristics of bulls, slaughtered at 15, 19 and 24 months of age, were analysed in four French breeds: Aubrac (AU), Charolais (CH), Limousin (LI), and Salers (SA). Muscle characteristics were determined in three muscles: longissimus thoracis (LT), semitendinosus (ST) and triceps brachii (TB). They included: (1) the % frequency, cross-sectional area and % area of fibre types, which were classified according to the contractile nature of the fibres and their metabolic properties (SO slow oxidative, FOG fast oxidative glycolytic and FG fast glycolytic); (2) the isocitrate dehydrogenase (ICDH) and lactate dehydrogenase (LDH) activities, representative of oxidative and glycolytic metabolism respectively; and (3) the total and insoluble collagen contents.

In the four breeds, the average daily gain and the food efficiency decreased with age (P < 0·001). The carcass characteristics (muscle, fat and bone weights) increased with age (P < 0·001). The increase of muscle carcass weight with slaughter age was in parallel with the increase in cross-sectional area of individual muscle fibres. Oxidative fibre (SO and FOG) areas increased more between 15 and 24 months than glycolytic fibre (FG) area. Differences between muscles in increases in areas of muscle fibres were consistent: the increase was greater for TB than ST and LT. The muscles studied became more slow and more oxidative above 19 months of age, as evidenced by the fact that the SO % frequency (P < 0·001) and % area (P < 0·001) and ICDH activity (P < 0·05) increased, and LDH activity decreased (P < 0·01). Insoluble collagen content decreased between 15 and 19 months (P < 0·001), and both total (P < 0·01) and insoluble (P < 0·001) collagen contents increased from 19 months.

So carcass characteristics were modified between 15 and 24 months, and muscle characteristics were especially modified from 19 months of age. In addition, differences in slaughter data between breeds were clear and consistent, whereas those of muscle characteristics were few and not consistent.
Adjustment of lamb birth and weaning weights for continuous effects of ewe age
Authors: Notter D. R. , Borg R. C. , Kuehn L. A.
Published: February 2006

Procedures for continuous adjustment of lamb birth and weaning weights for effects of ewe age were developed using 18 747 birth and 13 139 weaning weight records of Polypay sheep enrolled in the US National Sheep Improvement Program. Changes in birth and weaning weights across ewe age groups were modelled using hybrid curves that combined asymptotic regression models to describe initial increases in lamb weight as ewes moved into adulthood with secondorder polynomials to describe declines in lamb weights in older ewes. Lamb birth and weaning weights were highest (and the asymptotic and polynomial forms comprising the hybrid curves intersected) at ewe ages of 76 and 52 months, respectively. Across all ewe ages, hybrid curves were superior to second- and third-order polynomials in goodness of fit, producing a parabolic form with a flat top and different decay rates on either side of the ewe ages corresponding to maximum lamb weights. Fourth- and fifth-degree polynomials were equivalent to hybrid curves in goodness of fit, but generally did not produce reasonable predictions for the oldest ewes. Adjustment factors derived from the hybrid curve predicted that lamb birth weight would increase from 76% of maximum in 11-month-old ewes to 90 and 96% of maximum in 24- and 36-month-old ewes, respectively, and then decline to 97% of maximum at 105 months. For weaning weight, 83, 95, 99, and 93% of maximum lamb weight were attained at ewe ages of 11, 24, 36, and 105 months, respectively. Resulting multiplicative adjustment factors avoid discontinuities at boundaries between ewe age categories and are particularly useful in accelerated or other multiple-season lambing systems.
Effects of microwave irradiation on ruminal degradation and in vitro digestibility of soya-bean meal
Authors: Sadeghi A. A. , Nikkhah A. , Shawrang P.
Published: February 2006

This study was carried out to determine ruminal dry matter (DM) and crude protein (CP) degradation characteristics of untreated, 2-, 4- and 6-min microwave-treated soya-bean meal (SBM) by using nylon bags and sodium dodecyl sulphatepolyacrylamide gel electrophoresis (SDS-PAGE) techniques. Nylon bags of untreated or treated SBM were suspended into the rumen of three Holstein steers from 0 to 48 h, and data were fitted to non-linear degradation characteristics to calculate effective rumen degradation (ERD). There were significant differences (P < 0·05) for DM and CP degradation parameters between untreated and microwave-treated SBM. Microwave treatments decreased the water-soluble fraction and increased the potentially degradable fraction of CP. The degradation rate of the latter fraction decreased with these treatments. As a consequence, microwave treatments decreased (P < 0·05) ERD of CP. From densitometric scanning, SBM proteins were seen to be composed of two major components; β-conglycinin and glycinin, accounting for proportionately 0·30 and 0·40 of buffer-soluble SBM proteins, respectively. Electrophoretic analysis of untreated, 2-, 4- and 6-min microwave-treated SBM protein residues revealed that two of the subunits of β-conglycinin (α -and α) were degraded completely after 2, 4, 24 and 48 h, respectively, whereas the α subunit of this protein was more resistant to degradation. In untreated SBM, the two subunits of glycinin (acidic and basic polypeptides) were degraded in the middle of the incubation period, but in microwave-treated SBM were not degraded until 48 h of incubation. In vitro digestibility of ruminally undegraded CP of untreated and treated SBM increased (P < 0·05) with increases in rumen incubation time from 8 to 24 h. In conclusion, SBM proteins appeared to be effectively protected from ruminal degradation by a 4-min microwave treatment. SDS-PAGE results indicated that ruminally undegraded protein from untreated SBM was mainly composed of the basic subunit of glycinin, whereas that from microwave-treated SBM was composed of β-conglycinin and both basic and acidic subunits of glycinin.
Feeding mulberry leaves to fattening rabbits: effects on growth, carcass characteristics and meat quality
Authors: Martínez M. , Motta W. , Cervera C. , Pla M.
Published: February 2006

One hundred and thirty-two young rabbits were divided into two groups at weaning and given ad libitum a control diet (C), or an experimental diet (M) in which lucerne hay was substituted by mulberry leaves in order to examine their effects on fattening rabbit performance, carcass characteristics and meat quality.

Digestibility coefficients of dry matter (DM), crude protein and gross energy were similar in both groups but digestibility of crude fibre in the experimental diet was higher in line with a lower food intake in this group of animals, while ether extract digestibility of mulberry leaves was very low.

Food conversion ratio was similar in the two groups (3.1 g DM per g gain) but rabbits given the experimental diet had lower food intake (102 v. 144 g/day) and impaired live-weight gain. The rate of mortality was similar in the two groups. The substitution of lucerne with mulberry in the diet may have induced a higher retention time of digesta, as seems to be indicated by a higher weight of digestive tract contents recorded at slaughter (proportionately 0.32 more) in mulberry group. Live weight at slaughter of animals in control group was higher (2680 v. 2211 g) and also skin weight was proportionately 0.5 higher and its carcasses were proportionately 0.41 heavier than those of animals in experimental group (dressing yield 587 v. 503 g/kg). At constant carcass weight, the carcasses of rabbits of the mulberry group were longer than the lucerne group, but lumbar circumference tended also to be higher (P = 0.09) and no differences were found in the length: circumference ratio. No differences were found in the weights of kidneys or thoracic viscera, but livers of rabbits of the lucerne group were heavier (proportionately 0.3 heavier). The more remarkable difference was that carcasses of rabbits given the experimental diet had markedly less fat in scapular (5.8 v. 10.0 g) and perirenal fat (9.0 v. 22.3 g) deposits.

No differences in cooking losses or water-holding capacity of the meat were found and also the colour was similar, but the b* parameter was a little lower for meat of the M group rabbits.

The proportion of protein in the meat was the same for rabbits of the two groups, but rabbits given the experimental diet which had leaner carcasses also had leaner meat (19 v. 37 g lipids per kg meat) and a little more moisture (755 v. 736 g/kg meat). Intra and intermuscular fat of hindleg meat from rabbits of group M was less saturated and more unsaturated than that of the conventional rabbits mainly due to its higher proportion of polyunsaturated fatty acids, ω6 (37·3 v. 29·1 g/100 g lipids) and ω3 (3·4 v. 2·2 g/ 100 g lipids). Polyunsaturated: saturated ratio was higher in the mulberry group than in the lucerne group (1·15 v. 0·85) indicating a more desirable value in rabbits given the experimental diet, so meat of these rabbits could be considered preferable for human nutrition from this point of view.
Feeding behaviour and diet choices and diet choices of cattle with physical and temporal constraints on forage accessibility: an indoor experiment
Authors: Ginane C. , Petit M.
Published: February 2006

An indoor choice experiment was conducted to assess the extent to which heifers offered two forages of different quality will attempt to consume the better quality forage when the weight/number of constraints applied on its harvesting increase. The experiment involved six Salers heifers, a leafy (L) and a coarse (C) hay, and two combined or single accessibility constraints. A physical constraint consisted of reducing the prehensibility of L by covering the trough with a steel grid of either 4 cm or 6 cm mesh size (L4 or L6 v. L ∞ for no grid). A temporal constraint limited the daily access time to both hays to 4 v. 24 h. The hays were either offered alone or together over 2-week periods. Dry-matter intake and feeding time were recorded daily.

As expected, the physical constraint (only L4 was efficient) made the heifers decrease their choice (proportion of feeding time or intake) for L regardless of access time, whereas the temporal constraint had no significant effect on choice. The heifers greatly modulated their intake rate of L even under strong physical constraint (L4), and then unexpectedly managed to ingest L faster than C. This emphasizes their motivation to keep ingesting the better quality forage, and underlines the difficulties in comparing diet choices with the optimal foraging theory predictions based on the relative values of a behavioural component subject to large variation, i.e. intake rate. In a very constraining situation (L4 and 4-h access), heifers made a choice that allowed them to increase their total daily digestible organic matter (DOM) intake compared with L4 or C offered alone because of an inverse relationship between feeding time and intake rate on L4. They did not however maximize their total daily DOM intake in a less constraining situation (L ∞ or L6 and C, with 4-h access), since they did not consume L exclusively and showed a marked preference for a mixed diet.
Management strategies to maximize pigmeat output: effect of group size and split-marketing
Authors: O'Connell M. K. , Lynch P. B. , O'Doherty J. V.
Published: February 2006

Two experiments were completed with grower-finisher pigs to determine if pigmeat output, as measured by carcass gain per m2 per year, could be increased, by 1: increasing group size or 2: split-marketing pen groups. In experiment 1, 390 pigs (mean initial live weight 36·7 (s.d. 1·99) kg) were assigned to one of three treatments each with 10 replicates: 11, 13 or 15 pigs per single-sex group in pens measuring 11·04 m2. Space allowance was 1·00, 0·85 and 0·74 m2 per pig, respectively. Pelleted food was provided ad libitum. There were no differences (P > 0·05) between group sizes in growth rate, food intake, food conversion ratio, carcass growth and carcass food conversion ratio, backfat and muscle depth or carcass lean content. Pigmeat output per unit area increased with each increase in group size (234, 279 and 314 kg/m2 per year for 11, 13 and 15 pigs: P < 0·001). In experiment 2, 26 groups of 13 pigs (mean initial live weight 38·3 (s.d. 2·15) kg) were assigned to one of three treatments: 1D - group sold on 1 day (no. = 9), 2D - group sold over 2 days (14 days apart, no. = 10), or 3D - group sold over 3 days (each 7 days apart, no. = 7). Pigs were given a standard liquid diet three times daily. No differences (P > 0·05) were observed between treatments for overall growth rate, food intake, food conversion ratio, carcass weight, carcass lean content, backfat and muscle depth, carcass growth and carcass food conversion ratio or killing-out proportion of pigs. Split-marketing increased cycle length (67·7, 75·9 and 76·8 days for 1D, 2D and 3D, respectively; P < 0·001). Live and carcass daily growth rates per pig place decreased with increase in number of sale days (live: 772, 680, 670 g/day and carcass: 658, 575, 571 g/day; P < 0·001). Carcass gain per unit area decreased in split-marketed groups (358, 318, 312 kg/m2 per year for 1D, 2D and 3D, respectively: P < 0·05). Carcass weight variation (s.d.) within pen decreased with each increase in number of sale days (s. d. 5·28, 3·81 and 1·74, respectively; P < 0·001). In conclusion, pigmeat output, as measured by carcass gains per m2 per year, was improved with increase in group size and by marketing all pigs in a group on a single day.
Metabolic response of pigs supplemented with incremental levels of leguminousAcacia karroo,Acacia niloticaandColophospermum mopaneleaf meals
Authors: Halimani1 T. E. , Ndlovu L. R. , Dzama K. , Chimonyo M. , Miller B. G.
Published: February 2006

The nutritional effects of varying levels of leguminous leaf meal inclusion were investigated using 40 mixed weaner pigs of average weight 31·4 (s.d. 4·19) kg offered diets which included leguminous leaf meals (Acacia karroo,Acacia niloticaandColophospermum mopane) over 18 days. The leaf meals were included at 100, 200 and 300 g/kg of dry matter. Leaf meals increased daily live-weight gain (P> 0·05) at low inclusion levels. They were also shown to increase food intake and food conversion ratio. There was an increase in digestibility of dry matter and protein at low inclusion level of leaf meals (P< 0·05), then a decrease in the digestibility as the level of leaf meals increased. Inclusion of leaf meals induced production of proline-rich proteins (molecular weights of 24 600, 54 000, 66 000 and 74 000 Da) in the parotid salivary glands of pigs but not in the mandibular glands (P> 0·05). The activity of hepatic microsomal uridine diphosphate glucuronyl transferase increased significantly (P< 0·05) for pigs offered diets supplemented withA. niloticaandC. mopanebut not withA. karroo(P< 0·05). Intestinal parameters (crypt depth, villus height and villus-crypt ratio) were not significantly affected by leaf meal inclusion (P> 0·05) except crypt depth at the proximal position of the small intestine, which decreased with increasing leaf meal levels (P< 0·05).