Subcellular distribution of ‘intersecting’ β-N-acetylglucosaminyltransferase in Dictyostelium discoideum. A likely marker for the Golgi apparatus

AbstractGlycoprotein processing in Dictyostelium discoideum is characterized by enzyme catalyzed steps not reported in other organisms. One of these is the formation of a β 1 → 4 linkage between GlcNAc and the mannose linked to the core mannose in the α 1 → 6 position of N-glycosides. A simple and sensitive assay for this GlcNAc transferase activity, using a tri-mannose acceptor and a low concentration of UDP-G1cNAc, was developed. Homogenates of the organism were subjected to sub-cellular fractionation by centrifugation in discontinuous sucrose gradients. The specific activity was enriched 4–5-fold in a crude membrane fraction. The transferase was purified 10–12-fold in a membrane fraction that bands on top of 1.1 M sucrose. This fraction was also enriched in nucleotidyldiphosphatase. The enriched fraction was deficient in glucose-6-phosphatase, an endoplasmic reticulum marker. Approx. 80% of the transferase activity was latent, and unavailable to protease. Purified membranes were either subjected to phase separation in Triton X-114, or sodium carbonate extraction or sonication. In each case, the transferase behaved as an intrinsic membrane protein. Several secreted and lysosomal proteins are modified by the enzyme. These data support the idea that the GlcNAc transferase is present an an integral Golgi membrane protein and that at least the catalytic center of the transferase is on the lumenal side of the vesicles

General static spherically symmetric solutions in Horava gravity

We derive general static spherically symmetric solutions in the Horava theory of gravity with nonzero shift field. These represent "hedgehog" versions of black holes with radial "hair" arising from the shift field. For the case of the standard de Witt kinetic term (lambda =1) there is an infinity of solutions that exhibit a deformed version of reparametrization invariance away from the general relativistic limit. Special solutions also arise in the anisotropic conformal point lambda = 1/3.Comment: References adde

On the evolution of the entropy and pressure profiles in X-ray luminous galaxy clusters at z > 0.4

Galaxy clusters are the most recent products of hierarchical accretion over cosmological scales. The gas accreted from the cosmic field is thermalized inside the cluster halo. Gas entropy and pressure are expected to have a self-similar behaviour with their radial distribution following a power law and a generalized Navarro-Frenk-White profile, respectively. This has been shown also in many different hydrodynamical simulations. We derive the spatially-resolved thermodynamical properties of 47 X-ray galaxy clusters observed with Chandra in the redshift range 0.4 < z < 1.2, the largest sample investigated so far in this redshift range with X-rays spectroscopy, with a particular care in reconstructing the gas entropy and pressure radial profiles. We search for deviation from the self-similar behaviour and look for possible evolution with redshift. The entropy and pressure profiles lie very close to the baseline prediction from gravitational structure formation. We show that these profiles deviate from the baseline prediction as function of redshift, in particular at z > 0.75, where, in the central regions, we observe higher values of the entropy (by a factor of 2.2) and systematically lower estimates (by a factor of 2.5) of the pressure. The effective polytropic index, which retains informations about the thermal distribution of the gas, shows a slight linear positive evolution with the redshift and the concentration of the dark matter distribution. A prevalence of non-cool-core, disturbed systems, as we observe at higher redshifts, can explain such behaviours.Comment: 14 pages, 18 figures, accepted for publication by A&

11/09/1989 - Craig Chesner

Rapporto dell'Undicesima Campagna di Scavo della Missione Archeologica del Centro di Studi Papirologici a Soknopaiou Nesos (Fayyum, Egitto)

Poverty Traps

The understanding of why some countries fail to develop is one of the most intriguing and productive challenges for the modern theory of economic growth. Although many questions remains unanswered, the theory has gone a long way to explain and reveal many of the reasons underlying the persistence of poverty traps. Multiple causes, endogeneity and country-specific differences make it difficult to explain within a unified framework why some economies, caught in a vicious cycle, suffer from persistent underdevelopment

01/24/2012 - Former Charleston Resident Honored Through Music.pdf

La Campagna di Scavo 2011 ha riguardato il necessario restauro di strutture del tempio di Soknopaios, devastato da scavatori clandestini, che, approfittando del disordine politico e sociale seguìto alla rivoluzione in Egitto, hanno compiuto diverse incursioni sul sito

Nonlinear feedback oscillations in resonant tunneling through double barriers

We analyze the dynamical evolution of the resonant tunneling of an ensemble of electrons through a double barrier in the presence of the self-consistent potential created by the charge accumulation in the well. The intrinsic nonlinearity of the transmission process is shown to lead to oscillations of the stored charge and of the transmitted and reflected fluxes. The dependence on the electrostatic feedback induced by the self-consistent potential and on the energy width of the incident distribution is discussed.Comment: 10 pages, TeX, 5 Postscript figure

Cellular Basis of Aging in the Mammalian Heart

This review is concerned with the functional and structural changes occurring in the aging heart. These changes were investigated in an integrated fashion in Fischer 344 rats at 4, 12, 20, and 29 months after birth. Mean arterial pressure, left ventricular systolic and end-diastolic pressures, as well as stroke volume remained substantially constant up to 20 months. At 29 months, however, end-diastolic pressure was significantly increased, and dP/dt and stroke volume were depressed. Focal areas of interstitial and replacement fibrosis were markedly increased at 20 and 29 months, mostly in the subendocardial region of the ventricular wall. Also the aggregate number of mononucleated and binucleated cells in the left ventricle as a function of age was determined. The number of mononucleated cells increased up to 20 months but decreased thereafter; the binucleated cells showed a reversed pattern. The aging process of the heart involves a number of interrelated events including biochemical, electrical, mechanical and structural modifications. With aging and senescence, left ventricular failure develops in the Fischer rat model, and a similar process may occur in the human as well

Особливості числового розв’язання варіаційної задачі узгодження сигналу та його нейромережева інтерпретація

The features of numerical solution of variation problem of matching of signal with band-pass filter – determination of minimum after energy input signal at the specified value of output signal - are considered. Procedure of determination of optimum input signal is based on the method of the dynamic programming. Neural network interpretation of the problem is considered