The heliothis virescens 170 kDa aminopeptidase functions as "receptor A" by mediating specific Bacillus thuringiensis Cry1A delta-endotoxin binding and pore formation

The relationship between Bacillus thuringiensis Cry1Aa, Cry1Ab and Cry1Ac delta-endotoxin binding and pore formation was investigated using a purified 170 kDa aminopeptidase N (APN) from Heliothis virescens brush border membranes. Aminopeptidases with molecular sizes of 110, 140 and 170 kDa were eluted from a Cry1Ac toxin affinity column using N-acetylgalactosamine. The 140 kDa aminopeptidase has a cross-reacting determinant typical of a cleaved glycosyl-phosphatidylinositol anchor. After mild base treatment to de-acylate the glycosyl-phosphatidylinositol linkage and incubation in phosphatidyl inositol phospholipase C, anti-cross-reacting determinant antibody recognized the 170 kDa protein. Kinetic binding characteristics of Cry1A toxins to purified 170 kDa APN were determined using surface plasmon resonance. Cry1Aa, Cry1Ab and Cry1Ac, but not Cry1C and Cry1E toxins recognized 170 kDa APN. Each Cry1A toxin recognized two binding sites: a high affinity site with KD ranging from 41 to 95 nM and a lower affinity site with KD in the 325 to 623 nM range. N-acetylgalactosamine inhibited Cry1Ac but not Cry1Aa and Cry1Ab binding to 170 kDa APN. When reconstituted into phospholipid vesicles, the 170 kDa APN promoted toxin-induced 86Rb+ release for Cry1A toxins, but not Cry1C toxin. Furthermore Cry1Ac, the Cry protein most toxic to H. virescens larvae, caused 86Rb+ release at lower concentrations, and to a greater extent than Cry1Aa and Cry1Ab toxins. The correlation between toxin-binding specificity and 86Rb+ release strongly suggests that the purified 170 kDa APN is the functional receptor A in the H. virescens midgut epithelial cell brush border membranes.     

Robust Navigation and Mapping Architecture for Large Environments

This paper addresses the problem of Simultaneous Localization and Mapping (SLAM) for very large environments. A hybrid architecture is presented that makes use of the Extended Kalman Filter to perform SLAM in a very efficient form and a Monte Carlo localizer to resolve data association problems potentially present when returning to a known location after a large exploration period. Algorithms to improve the convergence of the Monte Carlo filter are presented that consider vehicle and sensor uncertainty. The proposed algorithm incorporates significant integrity to the standard SLAM algorithms by providing the ability to handle multimodal distributions over robot pose in real time during the re‐localization process. Experimental results in outdoor environments are presented to demonstrate the performance of the algorithm proposed. © 2003 Wiley Periodicals, Inc.     

The effect of electron concentration on the thermodynamic properties of two alloy phases in the Al-Zn-Ag system

A reversible electrochemical cell was used to determine the thermodynamic activity of aluminum in a series of α-phase Al-Zn and Al-Zn-Ag alloys, and a dew-point technique was used to determine the thermodynamic activity of zinc in a series of ε-phase Ag-Zn-Al alloys. The compositions investigated for both systems included those at which previous authors had related the stability of the phase to electronic factors. The data are presented in the form of graphs showing the excess relative partial molal Gibbs free energy of aluminum, (Δ•G_A1 ^xs), and zinc, (Δ•G_Zn ^xs), as a function of both mole fraction(X _i ) and electron-to-atom ratio (e/a). The latter curves are interpreted to be indications that the effect of electron concentration upon alloy phase stability has been experimentally isolated. Equations are developed which predict the effects of ternary additions in these alloy systems. The rigid-band model is shown to be incapable of predicting the direction of the effect and an argument based upon electron screening of ion-ion interactions is offered. Formerly Graduate Students, Metallurgy Department, Washington State University, Pullman, Wash. This paper constituted a portion of the theses submitted by RONALD E. MILLER and JERRY L. STRAALSUND in partial fulfillment of the requirements of the degree of Doctor of Philosophy in Engineering Science at Washington State University.     

In-pile creep study on mixed oxide (U,Pu)O2

The in-pile creep of a mixed oxide UO₂-PuO₂ under compression was studied up to fission rate of $\text{6 × 10}{}^{13}\text{f cm}{}^{\mathrm{?3}}\text{s}{}^{\mathrm{?1}}$, for stresses up to 26.5 MN m^?2, at temperatures ranging from 700 to 900°C. The results obtained agree with those of other authors. The creep rate is proportional to the applied stress and to the fission yield. However, it is athermal within the temperature range explored and is not affected by the burn-up, which has so far reached 30000 MWd t^?1 (3.6% FIMA). When the sample is under compression the fuel swells under the action of the fission products formed in the oxide during its irradiation. The swelling rate is about that commonly accepted for a clad fuel element. Finally it seems that the oxide swells more when free from stress than when subjected to a stress field, but this point has to be confirmed.     

Anomalies in the rheological behavior of polyethylene with very broad molecular weight distribution

The rheological behavior of high density polyethylenes with very broad molecular weight distribution is studied in the molten state starting from freshly synthesized powders. The complex viscosity increases slowly up to a limiting value as a function of ageing of the polymer and faster when the molten polymer is stirred. The phenomena are explained by an heterogeneous distribution of very high molecular weight nodules in the polymer arising from the synthesis and is proved by the preparation and characterization of polymers presenting the opposite heterogeneity and behavior (very low molecular weight nodules).     

Comparative efficacy of a DA2/alpha2 agonist and a beta-blocker in reducing adrenergic drive and cardiac fibrosis in an experimental model of left ventricular dysfunction after coronary artery occlusion

In a prepilot study, eight adults with chronic PTSD underwent three 90-minute sessions of eye movement desensitization and reprocessing (EMDR) at one-week intervals in an open trial. None of the seven who completed treatment met criteria for current PTSD two months later. Significant decreases in measures of pathology and disturbance were recorded. A controlled trial of EMDR is under way.     

Resistance of butyrylcholinesterase to inactivation by ultrasound: effects of ultrasound on catalytic activity and subunit association

We previously examined Moloney murine leukemia virus-induced fusion-from-within (FFWI) and fusion-from-without (FFWO) of SC-1 mouse cells. FFWI and FFWO can be distinguished by their stimulation by ionophores and polycations, respectively. FFWI is caused by infected cells. Normally, fusion between an infected cell and uninfected cells (heterofusions) is described, but we have surprisingly found that the infected cells also caused homofusion between uninfected cells in their vicinity (named neighbor homofusions). It was shown that neighbor homofusions were not induced by free virus particles (by FFWO). Transfectants expressing envelope proteins only induced heterofusions, indicating that virus production is necessary for the formation of neighbor homofusions. Both plasma membrane fragments and easily removable material from the surface of infected cells were able to induce fusion with the same stimulation pattern as FFWI and neighbor homofusion. These materials, especially the latter, have properties in common with virions, and it is discussed whether immature virions are involved in the formation of the neighbor homofusions.     

A Sampler of Circuit Switching Networks

This overview presents several different types of circuit switching networks: concentrators, connectors, expanders, partitioners, SIMD interconnectors, and sorters.