The COOH terminus of the c-Abl tyrosine kinase contains distinct F- and G-actin binding domains with bundling activity

The myristoylated form of c-Abl protein, as well as the P210bcr/abl protein, have been shown by indirect immunofluorescence to associate with F-actin stress fibers in fibroblasts. Analysis of deletion mutants of c-Abl stably expressed in fibroblasts maps the domain responsible for this interaction to the extreme COOH-terminus of Abl. This domain mediates the association of a heterologous protein with F-actin filaments after microinjection into NIH 3T3 cells, and directly binds to F-actin in a cosedimentation assay. Microinjection and cosedimentation assays localize the actin-binding domain to a 58 amino acid region, including a charged motif at the extreme COOH-terminus that is important for efficient binding. F-actin binding by Abl is calcium independent, and Abl competes with gelsolin for binding to F- actin. In addition to the F-actin binding domain, the COOH-terminus of Abl contains a proline-rich region that mediates binding and sequestration of G-actin, and the Abl F- and G-actin binding domains cooperate to bundle F-actin filaments in vitro. The COOH terminus of Abl thus confers several novel localizing functions upon the protein, including actin binding, nuclear localization, and DNA binding. Abl may modify and receive signals from the F-actin cytoskeleton in vivo, and is an ideal candidate to mediate signal transduction from the cell surface and cytoskeleton to the nucleus

N-Ethylmaleimide-Sensitive Protein(s) Involved in Cortical Exocytosis in the Sea-Urchin Egg - Localization to Both Cortical Vesicles and Plasma-Membrane

The exocytotic release of secretory products from fragments of sea urchin egg cortex has been shown to be inhibited by covalent modification of membrane sulfhydryl groups with N-ethylmaleimide (NEM). Exocytotically competent preparations of reconstituted cortex, formed by recombination of purified cortical vesicles (CVs) with fragments of egg plasma membrane (PM) were also inhibited by treatment with NEM. The cellular localization of sulfhydryl-containing constituent(s) responsible for inhibition was investigated by treating CVs and/or PM with NEM prior to reconstitution. Both native cortex and cortex reconstituted with NEM-treated components were challenged with calcium-containing buffers. Exocytosis was monitored by phase-contrast microscopy, and quantitated by light scattering. Evidence for CV-PM fusion was obtained with an immunofluorescence-based assay that permits visualization of the transport of CV content proteins across the PM. Cortex reconstituted by recombination of NEM-treated CVs with untreated PM or by recombination of untreated CVs with NEM-treated PM was exocytotically competent, whereas cortex formed by recombination of NEM-treated CVs with NEM-treated PM was inactive. These results: (1) support the hypothesis that the mechanism of exocytosis in native and reconstituted cortex is the same; (2) provide evidence that both CV and plasma membranes participate in the release of CV contents from reconstituted cortex; and (3) suggest that sulfhydryl-containing protein(s) present on the surface of purified CVs and plasma membrane are involved in exocytosis

Depression, anxiety and risk of hypertension in mid-aged women::a prospective longitudinal study

The evidence for an association between depression and anxiety and increased hypertension risk is inconsistent. We aimed to investigate the association between each of depression and anxiety and incident hypertension

The REVERE project:Experiments with the application of probabilistic NLP to systems engineering

Despite natural language’s well-documented shortcomings as a medium for precise technical description, its use in software-intensive systems engineering remains inescapable. This poses many problems for engineers who must derive problem understanding and synthesise precise solution descriptions from free text. This is true both for the largely unstructured textual descriptions from which system requirements are derived, and for more formal documents, such as standards, which impose requirements on system development processes. This paper describes experiments that we have carried out in the REVERE1 project to investigate the use of probabilistic natural language processing techniques to provide systems engineering support

First-principles calculations of magnetization relaxation in pure Fe, Co, and Ni with frozen thermal lattice disorder

The effect of the electron-phonon interaction on magnetization relaxation is studied within the framework of first-principles scattering theory for Fe, Co, and Ni by displacing atoms in the scattering region randomly with a thermal distribution. This "frozen thermal lattice disorder" approach reproduces the non-monotonic damping behaviour observed in ferromagnetic resonance measurements and yields reasonable quantitative agreement between calculated and experimental values. It can be readily applied to alloys and easily extended by determining the atomic displacements from ab initio phonon spectra

Validity of effective material parameters for optical fishnet metamaterials

Although optical metamaterials that show artificial magnetism are mesoscopic systems, they are frequently described in terms of effective material parameters. But due to intrinsic nonlocal (or spatially dispersive) effects it may be anticipated that this approach is usually only a crude approximation and is physically meaningless. In order to study the limitations regarding the assignment of effective material parameters, we present a technique to retrieve the frequency-dependent elements of the effective permittivity and permeability tensors for arbitrary angles of incidence and apply the method exemplarily to the fishnet metamaterial. It turns out that for the fishnet metamaterial, genuine effective material parameters can only be introduced if quite stringent constraints are imposed on the wavelength/unit cell size ratio. Unfortunately they are only met far away from the resonances that induce a magnetic response required for many envisioned applications of such a fishnet metamaterial. Our work clearly indicates that the mesoscopic nature and the related spatial dispersion of contemporary optical metamaterials that show artificial magnetism prohibits the meaningful introduction of conventional effective material parameters

Mass and dust in the disk of a spiral lens galaxy

Gravitational lensing is a potentially important probe of spiral galaxy structure, but only a few cases of lensing by spiral galaxies are known. We present Hubble Space Telescope and Magellan observations of the two-image quasar PMN J2004-1349, revealing that the lens galaxy is a spiral galaxy. One of the quasar images passes through a spiral arm of the galaxy and suffers 3 magnitudes of V-band extinction. Using simple lens models, we show that the mass quadrupole is well-aligned with the observed galaxy disk. A more detailed model with components representing the bulge and disk gives a bulge-to-disk mass ratio of 0.16 +/- 0.05. The addition of a spherical dark halo, tailored to produce an overall flat rotation curve, does not change this conclusion.Comment: ApJ, in press [9pp, 7 figs

The role of social and/or ecological contexts influences assessment strategy use in Tilapia

Animals engage in costly agonistic contests during which winners procure resources. During these interactions, the combatants obtain and use information to make decisions on whether to persist or to withdraw from the fight, which is termed assessment. Recent theory and work have suggested that the types of assessment employed may be more variable than previously thought, with the use of different strategies possibly being influenced by social and ecological conditions during priming. This study addresses the contextual components (social and ecological) that affect the utilization of one assessment strategy over another. Male tilapia were primed with different combinations of social (large and small animals) and ecological (resource rich or poor) contexts 24 hr prior to fighting in staged, dyadic contests. When opponents were primed with the same context, a clear assessment strategy emerged and differed as a function of priming treatment. Conversely, when fish were primed with different treatment contexts, there was no discernible assessment. In addition, priming conditions had differing effects for large and small fish. Thus, assessment strategies in cichlids are dependent upon a combination of social, ecological contexts and size of the animal. Since assessment strategies change as a function of both of these contexts, as well as others, future framework investigating assessment strategies should include both intrinsic and extrinsic factors that may shape fighting dynamics.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151902/1/eth12936_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151902/2/eth12936.pd

Improved Constraints on Isotropic Shift and Anisotropies of the Speed of Light using Rotating Cryogenic Sapphire Oscillators

We demonstrate that Michelson-Morley tests, which detect direction-dependent anisotropies in the speed of light, can also be used to place limits upon isotropic deviations of the vacuum speed of light from $c$, as described by the photon sector Standard Model Extension (SME) parameter $\tilde{\kappa}_{tr}$. A shift in the speed of light that is isotropic in one inertial frame implies anisotropic shifts in others. Using observer Lorentz covariance, we derive the time-dependent variations in the relative resonance frequencies of a pair of electromagnetic resonators that would be generated by such a shift in the rest frame of the Sun. A new analysis of a recent experimental test of relativity using this result constrains $\tilde{\kappa}_{tr}$ with a precision of $7.4\times10^{-9}$. This represents the first constraint on $\tilde{\kappa}_{tr}$ by a Michelson-Morley experiment and the first analysis of a single experiment to simultaneously set limits on all nine non-birefringent terms in the photon sector of the SME

In Vitro Reconstitution of Exocytosis from Sea Urchin Egg Plasma Membrane and Isolated Cortical Vesicles

We have succeeded in reconstituting an exocytotically active egg cortex fraction by recombining purified cortical vesicles (CVs) with egg plasma membrane (PM). CVs were dislodged from a suspension of egg cortex by gentle homogenization in a dissociative buffer with a pH of 9.1, and purified by two rounds of differential centrifugation. Egg PM was prepared by shearing the cortical vesicles from a cortical lawn preparation with a jet of isotonic buffer. PM lawns produced by this procedure consist of an array of CV-free PM fragments attached via their extracellular surface to a polylysine coated glass slide. When a neutralized suspension of CVs was recombined with a PM lawn, CVs reassociated with the cytoplasmic face of the plasma membrane to form a reconstituted lawn (RL). RLs undergo a morphological change in response to Ca2+-containing buffers that is similar to the exocytotic release of CV contents from cortical lawns. In both reactions CV contents are vectorially transferred from the cytoplasmic to the extracytoplasmic face of the egg PM. A quantitative binding assay was developed and used to show that adherence of CVs to a heterologous PM lawn prepared from human red blood cells is minimal