Recent advances: role of mycolactone in the pathogenesis and monitoring of Mycobacterium ulcerans infection/Buruli ulcer disease.

Infection of subcutaneous tissue with Mycobacterium ulcerans can lead to chronic skin ulceration known as Buruli ulcer. The pathogenesis of this neglected tropical disease is dependent on a lipid-like toxin, mycolactone, which diffuses through tissue away from the infecting organisms. Since its identification in 1999, this molecule has been intensely studied to elucidate its cytotoxic and immunosuppressive properties. Two recent major advances identifying the underlying molecular targets for mycolactone have been described. First, it can target scaffolding proteins (such as Wiskott Aldrich Syndrome Protein), which control actin dynamics in adherent cells and therefore lead to detachment and cell death by anoikis. Second, it prevents the co-translational translocation (and therefore production) of many proteins that pass through the endoplasmic reticulum for secretion or placement in cell membranes. These pleiotropic effects underpin the range of cell-specific functional defects in immune and other cells that contact mycolactone during infection. The dose and duration of mycolactone exposure for these different cells explains tissue necrosis and the paucity of immune cells in the ulcers. This review discusses recent advances in the field, revisits older findings in this context and highlights current developments in structure-function studies as well as methodology that make mycolactone a promising diagnostic biomarker

Mapping the Two-Component Atomic Fermi Gas to the Nuclear Shell-Model

The physics of a two-component cold fermi gas is now frequently addressed in laboratories. Usually this is done for large samples of tens to hundreds of thousands of particles. However, it is now possible to produce few-body systems (1-100 particles) in very tight traps where the shell structure of the external potential becomes important. A system of two-species fermionic cold atoms with an attractive zero-range interaction is analogous to a simple model of nucleus in which neutrons and protons interact only through a residual pairing interaction. In this article, we discuss how the problem of a two-component atomic fermi gas in a tight external trap can be mapped to the nuclear shell model so that readily available many-body techniques in nuclear physics, such as the Shell Model Monte Carlo (SMMC) method, can be directly applied to the study of these systems. We demonstrate an application of the SMMC method by estimating the pairing correlations in a small two-component Fermi system with moderate-to-strong short-range two-body interactions in a three-dimensional harmonic external trapping potential.Comment: 13 pages, 3 figures. Final versio

The Molecular Epidemiology and Evolution of Murray Valley Encephalitis Virus: Recent Emergence of Distinct Sub-lineages of the Dominant Genotype 1

© 2015 Williams et al. Background: Recent increased activity of the mosquito-borne Murray Valley encephalitis virus (MVEV) in Australia has renewed concerns regarding its potential to spread and cause disease. Methodology/Principal Findings: To better understand the genetic relationships between earlier and more recent circulating strains, patterns of virus movement, as well as the molecular basis of MVEV evolution, complete pre-membrane (prM) and Envelope (Env) genes were sequenced from sixty-six MVEV strains from different regions of the Australasian region, isolated over a sixty year period (1951–2011). Phylogenetic analyses indicated that, of the four recognized genotypes, only G1 and G2 are contemporary. G1 viruses were dominant over the sampling period and found across the known geographic range of MVEV. Two distinct sub-lineages of G1 were observed (1A and 1B). Although G1B strains have been isolated from across mainland Australia, Australian G1A strains have not been detected outside northwest Australia. Similarly, G2 is comprised of only Western Australian isolates from mosquitoes, suggesting G1B and G2 viruses have geographic or ecological restrictions. No evidence of recombination was found and a single amino acid substitution in the Env protein (S332G) was found to be under positive selection, while several others were found to be under directional evolution. Evolutionary analyses indicated that extant genotypes of MVEV began to diverge from a common ancestor approximately 200 years ago. G2 was the first genotype to diverge, followed by G3 and G4, and finally G1, from which subtypes G1A and G1B diverged between 1964 and 1994. Conclusions/Significance: The results of this study provides new insights into the genetic diversity and evolution of MVEV. The demonstration of co-circulation of all contemporary genetic lineages of MVEV in northwestern Australia, supports the contention that this region is the enzootic focus for this virus

PRELIMINARY STUDIES ON in vitro PROPAGATION OF YAM BEAN (Pachyrhizus erosus (L.) Urban)

The regeneration potential of Pachyrhizus erosus using single node culture has been investigated on Murashige and Skoog (1962) (MS) medium alone, and supplemented with each of Benzyladenine (BA), 2-isopentyladenine (2-ip), Kinetin (Kin), Zeatin and Adenine, at a 1 mg/1 concentration. The position effect of the nodes was investigated for hormone sensitivity. The basal medium must be supplemented with hormone for bud burst. Buds were stimulated by a range of cytokinins, but response was not dependent on nodal position. BA, Zeatin and Kinetin, however seem to induce multiple bud proliferation. Callus induction using leaf explants of different physiological ages was investigated on MS medium supplemented with 2, 4-dichlorophenoxyacetic acid (2,4-D); 3 indoleacetic acid (IAA) plus Kin; 1 naphthylacetic acid (NAA) plus Kin; and 2,4-D plus Kin at 1 mg/L concentration. The effect of light on callus initiation was noted. Callus was initiated on MS with 2,4-D plus Kin, also NAA plus Kin incubated in complete darkness. The quantity of callus varied with leaf age. Callus initiated with 2,4-D and Kinetin was placed on MS supplemented with BA using either fructose or glucose as the carbon/energy source, and incubated in light and dark environments. Chlorophyll formation was apparent in callus exposed to light, when the carbon source was fructose. Squash preparations of callus on BA supplemented medium indicated the presence of tracheids. Plantlet regeneration from callus has not yet been achieved