Formation of mononuclear and chloro-bridged binuclear copper(II) complexes of patellamide D, a naturally occurring cyclic peptide: influence of anion and solvent

Patellamide D (patH(4)) is a cyclic octapeptide isolated from the ascidian Lissoclinum patella. The peptide possesses a 24-azacrown-8 macrocyclic structure containing two oxazoline and two thiazole rings, each separated by an amino acid. The present spectrophotometric, electron paramagnetic resonance (EPR) and mass spectral studies show that patellamide D reacts with CuCl, and triethylamine in acetonitrile to form mononuclear and binuclear copper(II) complexes containing chloride. Molecular modelling and EPR studies suggest that the chloride anion bridges the copper(II) ions in the binuclear complex [Cu-2(patH(2))(mu-Cl)](+). These results contrast with a previous study employing both base and methanol, the latter substituting for chloride in the copper(II) complexes en route to the stable mu-carbonato binuclear copper(II) complex [Cu-2 (patH(2))(mu-CO3)]. Solvent clearly plays an important role in both stabilising these metal ion complexes and influencing their chemical reactivities. (C) 2004 Elsevier Inc. All rights reserved.

Behavioural characterization of Vitamin D receptor knockout mice

Vitamin D (calcitriol) is a nuclear transcription regulator acting via a nuclear hormone receptor (VDR). In addition to its role in the regulation of calcium and phosphate horneostasis and in bone formation, Vitamin D is also thought to be involved in brain function. The aim of this study was to behaviourally phenotype VDR knockout mice. We characterized the behaviour of VDR null mutant mice and wildtype littermate controls by subjecting them to a range of tests including a primary behavioural screen (using the SHIRPA protocol), rotarod, gait analysis, Y-maze, marble burying test, bedding test, holeboard test, elevated plus maze, open field test and prepulse inhibition of the acoustic startle response. There were no effects of genotype on most of the scores from the SHIRPA protocol except that VDR -/- mice had alopecia, were shorter and weighed less than VDR +/+ mice. VDR -/- mice had a shorter gait as well as impairments on the rotarod, in the bedding test and impaired habituation in both the open field and on the acoustic startle response. The VDR -/- mice had normal acoustic startle responses but had impaired PPI at long (256 ms) but not short (64 ms) prepulse to pulse intervals. The VDR -/- mice were less active in the open field and buried fewer marbles in the marble burying test. However, there were no differences in the time spent on the open arms of the elevated plus maze or in working memory as assessed by repeat arm entries on the Y-maze. Therefore, it appears that VDR -/- mice have muscular and motor impairments that significantly affects locomotor behaviour but seemingly no impairments in cognition as indicated by exploration, working memory or anxiety. (C) 2004 Elsevier B.V. All rights reserved.

Actin localisation and the effect of cytochalasin D on the osmotic tolerance of cauda epedidymidal kangaroo spermatozoa

This study examined the hypothesis that filamentous actin associated with the complex cytoskeleton of the kangaroo sperm head and tail may be contributing to lack of plasma membrane plasticity and a consequent loss of membrane integrity during cryopreservation. In the first study, the distribution of G and F actin within Eastern Grey Kangaroo (EGK, Macropus giganteus) cauda epididymidal spermatozoa was successfully detected using DNAse-FITC and a monoclonal F-actin antibody (ab205, Abcam), respectively. G-actin staining was most intense in the acrosome but was also observed with less intensity over the nucleus and mid-piece. F-actin was located in the sperm nucleus but was not discernable in the acrosome or sperm tail. To investigate whether cytochalasin D (a known F-actin depolymerising agent) was capable of improving the osmotic tolerance of EGK cauda epididymal spermatozoa, sperm were incubated in hypo-osmotic media (61 and 104 mOsm) containing a range of cytochalasin D concentrations (0-200 mu M). Cytochalasin D had no beneficial effect on plasma membrane integrity of sperm incubated in hypo-osmotic media. However, when EGK cauda epididymidal sperm were incubated in isosmotic media, there was a progressive loss of sperm motility with increasing cytochalasin D concentration. The results of this study indicated that the F-actin distribution in cauda epididymidal spermatozoa of the EGK was surprisingly different from that of the Tammar Wallaby (M. eugenii) and that cytochalasin-D does not appear to improve the tolerance of EGK cauda epididymidal sperm to osmotically induced injury.

The graying of R&D workgroups: The effects of age diversity on developing publicly usable knowledge

Does the graying of scientific research teams matter? This study addresses how workgroup processes and external environmental factors contribute and inhibit the effect of age diversity in R&D project groups on the production of innovative publicly usable knowledge outcomes in the form of publication outputs. We examined the relationships between group age diversity (age cohort diversity, mean age, age dispersion), R&D workgroup member self-ratings of workgroup processes, their supervisor�s assessment of the external environmental factors the project groups faced, and their supervisor�s ratings of group performance, the number of scientific publicly available publications produced by the group and the use of multiple authorships on publications. Usable data was obtained from 32 R&D workgroups of a large Government Agricultural Research and Development Agency. Consistent with the literature, workgroup processes and external environmental factors were found to directly effect innovation outcomes. Contrary to expectation, but consistent with Social Identity theory, workgroup age diversity generally negatively impacted upon innovation outcomes. An exception was where multiple authorship on publications for project groups increased as the dispersion of age within groups increased. Importantly, workgroups that were both more age homogeneous and perceived to have optimally functioning work processes produced more R&D innovation outcomes than other groups. Generally, these differences appear to be related to the greater division of labor practices (and less multi-tasking) employed by the older and more homogeneous workgroups. Implications for R&D workgroup resource theory and practices are discussed.

Matrix elements of U(2n) generators in a multishell spin-orbit basis. I. The del-operator MEs in a two-shell composite Gelfand-Paldus basis

This is the first in a series of three articles which aimed to derive the matrix elements of the U(2n) generators in a multishell spin-orbit basis. This is a basis appropriate to many-electron systems which have a natural partitioning of the orbital space and where also spin-dependent terms are included in the Hamiltonian. The method is based on a new spin-dependent unitary group approach to the many-electron correlation problem due to Gould and Paldus [M. D. Gould and J. Paldus, J. Chem. Phys. 92, 7394, (1990)]. In this approach, the matrix elements of the U(2n) generators in the U(n) x U(2)-adapted electronic Gelfand basis are determined by the matrix elements of a single Ll(n) adjoint tensor operator called the del-operator, denoted by Delta(j)(i) (1 less than or equal to i, j less than or equal to n). Delta or del is a polynomial of degree two in the U(n) matrix E = [E-j(i)]. The approach of Gould and Paldus is based on the transformation properties of the U(2n) generators as an adjoint tensor operator of U(n) x U(2) and application of the Wigner-Eckart theorem. Hence, to generalize this approach, we need to obtain formulas for the complete set of adjoint coupling coefficients for the two-shell composite Gelfand-Paldus basis. The nonzero shift coefficients are uniquely determined and may he evaluated by the methods of Gould et al. [see the above reference]. In this article, we define zero-shift adjoint coupling coefficients for the two-shell composite Gelfand-Paldus basis which are appropriate to the many-electron problem. By definition, these are proportional to the corresponding two-shell del-operator matrix elements, and it is shown that the Racah factorization lemma applies. Formulas for these coefficients are then obtained by application of the Racah factorization lemma. The zero-shift adjoint reduced Wigner coefficients required for this procedure are evaluated first. All these coefficients are needed later for the multishell case, which leads directly to the two-shell del-operator matrix elements. Finally, we discuss an application to charge and spin densities in a two-shell molecular system. (C) 1998 John Wiley & Sons.

PREDBALB/c: a system for the prediction of peptide binding to H2(d) molecules, a haplotype of the BALB/c mouse

PREDBALB/c is a computational system that predicts peptides binding to the major histocompatibility complex-2 (H2(d)) of the BALB/c mouse, an important laboratory model organism. The predictions include the complete set of H2(d) class I ( H2-K-d, H2-L-d and H2-D-d) and class II (I-E-d and I-A(d)) molecules. The prediction system utilizes quantitative matrices, which were rigorously validated using experimentally determined binders and non-binders and also by in vivo studies using viral proteins. The prediction performance of PREDBALB/c is of very high accuracy. To our knowledge, this is the first online server for the prediction of peptides binding to a complete set of major histocompatibility complex molecules in a model organism (H2(d) haplotype). PREDBALB/c is available at http://antigen.i2r.a-star.edu.sg/predBalbc/.