Isolation of a cytotoxin from L-form Salmonella typhimurium

Abstract A cytotoxin protein was isolated from the sodium dodecyl sulphate (SDS)-solubilized extract of the stable L forms of Salmonella typhimurium by ion-retardation chromatography, ion-exchange chromatography, isoelectric focusing and gel filtration. The purified toxin, with a molecular mass of 32 kDa and with isoelectric point of 6.4, was thermolabile and trypsin-sensitive. Against mouse macrophages, its cytolytic effect was detectable in vitro at concentrations higher than 0.7 μg/ml, with a complete lysis obtained at 5 μg/ml. In contrast, it stimulated C3H/HeJ macrophages in the dose range of 0.1–0.5 μg/ml to allow the cell to respond to endotoxin, resulting in the significant production of tumor necrosis factor α. By Northern blot analysis, this effect was detectable at a dose as low as 0.01 μg/ml. These findings suggest that the transformation of bacillary S. typhimurium into L forms in vivo may induce alterations in host resistance against murine typhoid.     

The fate of defeated alpha male chimpanzees in relation to their social networks

Usurpation of alpha status by males is a relatively rare event among wild chimpanzees in the Mahale Mountains National Park, western Tanzania, where long-term field studies have been carried out since 1965. Here we report three such cases and compare the fate of those defeated alpha males. The formation of effective alliances with other adult males is considered to be crucial in determining what will happen to the defeated alpha male in the rank order after the loss of his status.     

The Implementation of the Iterative Diagonalization Scheme and ab initio Molecular Dynamics Simulation with the LAPW Method

Abstract

A new ab initio molecular dynamics method based on the full-potential linearized-augmented-plane-wave (LAPW) basis set has been implemented. The LAPW basis set has been successfully employed for systems containing localized electrons such as first row atoms and transition metals. In our implementation of the LAPW-MD scheme, iterative residual minimization algorithm is used to solve the electronic states problem. The atoms are moved according to forces derived from the Hellman–Feynman theorem and incomplete basis set correction terms. The performance of the program is further enhanced by parallelization. We will discuss technical details of the program implementation and present results obtained from this code to the equilibrium structures and vibrational properties of simple diatomic molecules.