The Francisella tularensis pathogenicity island protein IglC and its regulator MglA are essential for modulating phagosome biogenesis and subsequent bacterial escape into the cytoplasm

The Francisella tularensis subsp. novicida-containing phagosome (FCP) matures into a late endosome-like stage that acquires the late endosomal marker LAMP-2 but does not fuse to lysosomes, for the first few hours after bacterial entry. This modulation in phagosome biogenesis is followed by disruption of the phagosome and bacterial escape into the cytoplasm where they replicate. Here we examined the role of the Francisella pathogenicity island (FPI) protein IglC and its regulator MglA in the intracellular fate of F. tularensis subsp. novicida within human macrophages. We show that F. tularensis mglA and iglC mutant strains are defective for survival and replication within U937 macrophages and human monocyte-derived macrophages (hMDMs). The defect in intracellular replication of both mutants is associated with a defect in disruption of the phagosome and failure to escape into the cytoplasm. Approximately, 80-90% of the mglA and iglC mutants containing phagosomes acquire the late endosomal/lysosomal marker LAMP-2 similar to the wild-type (WT) strain. Phagosomes harbouring the mglA or iglC mutants acquire the lysosomal enzyme Cathepsin D, which is excluded from the phagosomes harbouring the WT strain. In hMDMs in which the lysosomes are preloaded with BSA-gold or Texas Red Ovalbumin, phagosomes harbouring the mglA or the iglC mutants acquire both lysosomal tracers. We conclude that the FPI protein IglC and its regulator MglA are essential for modulating phagosome biogenesis and subsequent bacterial escape into the cytoplasm. Therefore, acquisition of the FPI, within which iglC is contained, is essential for the pathogenic evolution of F. tularensis to evade lysosomal fusion within human macrophages and cause tularemia. This is the first example of specific virulence factors of F. tularensis that are essential for evasion of fusion of the FCP to lysosomes.     

Binding of madindoline A to the extracellular domain of gp130

Elevated levels of IL-6 and IL-11 are associated with multiple myeloma, rheumatoid arthritis, hypercalcemia, cancer cachexia, and Castleman's disease. Madindoline A (MadA), isolated from Streptomyces nitrosporeus K93-0711, specifically inhibits the growth of IL-6- and IL-11-dependent cell lines, most likely by interfering with the homodimerization of gp130. This raises the possibility that MadA can be used as a model compound for the development of novel chemotherapeutic agents. In this report, we demonstrate that the binding of MadA to gp130 is specific and noncovalent, and displays a relatively low affinity. Furthermore, we show that the tricyclic 3a-hydroxytetrahydrofuro[2,3-b]indole (HFI) moiety of MadA alone is not sufficient for binding. Matrix-bound MadA precipitates a protein composed of the extracellular domain of gp130 fused to the Fc region of the immunoglobulin heavy chain. Binding is inhibited in a dose-dependent manner by preincubation with free MadA. The K(D) for binding of MadA to gp130 is 288 microM, as determined by surface plasmon resonance (SPR)-based biosensor analysis. The HFI portion of MadA does not bind to gp130 in either affinity precipitation or SPR analyses. Finally, MadA, but not the HFI portion, inhibits IL-6-dependent Stat3 tyrosine phosphorylation in HepG2 cells.     

Nutritional factors affecting organic solvent-tolerant alkaline protease production by a newBacillus cereus strain 146

An organic solvent-tolerant bacterium designated as 146 capable of producing an organic solvent-stable alkaline protease was isolated from contaminated soil of a wood factory. The strain was a Gram-positive, spore-forming, nitrate-positive, rod-shaped organism capable of hydrolysing gelatine, starch, skim milk and identified asBacillus cereus. Activity of the protease was drastically increased in the presence of 1–decanol, isooctane, n-dodecane and n-tetradecane, but reduced in the presence of ethyl acetate, benzene, toluene, 1-heptanol, ethylbenzene and hexane. The bacterium was shown to require lactose as a carbon source and peptone as a nitrogen source. The optimum fermentation condition for the production of alkaline protease was in the presence of beef and yeast extract. Optimum pH was determined to be at 10.0 at incubation temperature of 37 °C for 48 h. Results from the studies suggest that 146 is a new strain of Bacillus cereus capable of producing organic solvent-tolerant alkaline protease with potential use in industries.     

A study on medicinal plants from Malaysia focused on Acalypha siamensis Oliv. ex Gage. isolation and structure of a new tetraterpene, acalyphaser A

As a part of our chemical studies on Malaysian medicinal plants, five Malaysian plant species were evaluated by cytotoxicity assays using P388 murine leukemia cells. Since Acalypha siamensis exhibited the strongest growth inhibition, its constituents were studied as the object of search for bioactive materials. A novel tetraterpene, acalyphaser A (1), was isolated in the course of the purification. Its structure was elucidated on the basis of 1D- and 2D-NMR techniques, and mass spectrometry.     

Biodegradation of hydrocarbon contamination by immobilized bacterial cells

This study examined the capacity of immobilized bacteria to degrade petroleum hydrocarbons. A mixture of hydrocarbon-degrading bacterial strains was immobilized in alginate and incubated in crude oil-contaminated artificial seawater (ASW). Analysis of hydrocarbon residues following a 30-day incubation period demonstrated that the biodegradation capacity of the microorganisms was not compromised by the immobilization. Removal of n-alkanes was similar in immobilized cells and control cells. To test reusability, the immobilized bacteria were incubated for sequential increments of 30 days. No decline in biodegradation capacity of the immobilized consortium of bacterial cells was noted over its repeated use. We conclude that immobilized hydrocarbon-degrading bacteria represent a promising application in the bioremediation of hydrocarbon-contaminated areas.     

Dipalmitoylation of a cellular uptake-mediating apolipoprotein E-derived peptide as a promising modification for stable anchorage in liposomal drug carriers

Liposomes equipped with cellular uptake-mediating peptidic vector compounds have attracted much attention as target-specific drug delivery systems. Aside from the development of the target recognition motif itself, vector coupling to liposomes while conserving the active conformation constitutes an important element in carrier development. To elucidate the most efficient way for adsorptive peptide binding to liposomes, we synthesized and characterized two-domain peptides comprising a cationic sequence derived from the binding domain of apolipoprotein E (apoE) for the low-density lipoprotein receptor and different lipid-binding motifs, that is, an amphipathic helix, a transmembrane helix, single fatty acids or two palmitoyl chains. Peptide properties considered relevant for peptide-liposome complexes to initiate an endocytotic cellular uptake such as lipid binding, helicity, stability of anchorage, bilayer-disturbing activity, and toxicity showed that the dipalmitoyl derivative was the most suitable to associate the apoE peptide to the surface of liposomes. The peptide showed pronounced lipid affinity and was stably anchored within the lipid bilayer on a time scale of at least 30 min. The helicity of about 40% in the lipid-bound state and the location of the amphipathic helix on the liposomal surface provided the prerequisites for interaction of the complex with the cell surface-located receptor. The concentration of the dipalmitoylated peptide to permeabilize neutral lipid bilayers (lipid concentration 25 microM) was 0.06 microM and a 2 microM concentration reduced cell viability to about 80%. Efficient internalization of liposomes bearing about 180 peptide derivatives on the surface into brain capillary endothelial cells was monitored by confocal laser scanning microscopy. The concept of complexation using dipalmitoylated peptides may offer an efficient substitute to covalent vector coupling and a prospective way to optimize the capacity of liposomes as drug delivery systems also for different targets.     

Biomechanical evaluation of the relationship between postural control and body mass index

Postural stability is crucial in maintaining body balance during quiet standing, locomotion, and any activities that require a high degree of balance performance, such as participating in sports and dancing. Research has shown that there is a relationship between stability and body mass. The aims of this study were to examine the impact that two variables had on static postural control: body mass index (BMI) and gender. Eighty healthy young adults (age=21.7±1.8 yr; height=1.65±0.09 m; mass=67.5±19.0 kg) participated in the study and the static postural control was assessed using the Biodex Balance System, with a 20 Hz sampling rate in the bipedic stance (BLS) and unipedic stance (ULS) for 30s. Five test evaluations were performed for each balance test. Postural control was found to be negatively correlated with increased adiposity, as the obese BMI group performed significantly poorer than the underweight, normal weight and overweight groups during BLS and ULS tests. The underweight, normal weight and overweight groups exhibited greater anterior-posterior stability in postural control during quiet stance. In addition, female displayed a trend of having a greater postural sway than male young adults, although it was evidenced in only some BMI groups. This study revealed that BMI do have an impact on postural control during both BLS and ULS. As such, BMI and gender-specific effects should be taken into consideration when selecting individuals for different types of sporting activities, especially those that require quiet standing.