An Emerging Approach for Parallel Quantification of Intracellular Protozoan Parasites and Host Cell Characterization Using TissueFAXS Cytometry

Characterization of host-pathogen interactions is a fundamental approach in microbiological and immunological oriented disciplines. It is commonly accepted that host cells start to change their phenotype after engulfing pathogens. Techniques such as real time PCR or ELISA were used to characterize the genes encoding proteins that are associated either with pathogen elimination or immune escape mechanisms. Most of such studies were performed in vitro using primary host cells or cell lines. Consequently, the data generated with such approaches reflect the global RNA expression or protein amount recovered from all cells in culture. This is justified when all host cells harbor an equal amount of pathogens under experimental conditions. However, the uptake of pathogens by phagocytic cells is not synchronized. Consequently, there are host cells incorporating different amounts of pathogens that might result in distinct pathogen-induced protein biosynthesis. Therefore, we established a technique able to detect and quantify the number of pathogens in the corresponding host cells using immunofluorescence-based high throughput analysis. Paired with multicolor staining of molecules of interest it is now possible to analyze the infection profile of host cell populations and the corresponding phenotype of the host cells as a result of parasite load.     

PspA adopts an ESCRT-III-like fold and remodels bacterial membranes

1. Download : Download high-res image (323KB)
2. Download : Download full-size image

     

Crosslinking of theDrosophila chorion involves a peroxidase

Summary TheDrosophila chorion contains an endogenous peroxidase activity which remains inactive until late stage 14 when it catalyzes the crosslinking of the chorionic proteins. Using explanted follicles developing in vitro, premature, but otherwise normal crosslinking can be induced with hydrogen peroxide and normal crosslinking can be prevented with peroxidase inhibitors. Inhibition or premature activation of the shell peroxidase allows characterization of chorionic filament specific proteins and establishes new criteria for the identification of eggshell components.     

Glycophorin-induced cholesterol-phospholipid domains in dimyristoylphosphatidylcholine bilayer vesicles.

Glycophorin has been incorporated into unilamellar cholesterol-containing dimyristoylphosphatidylcholine vesicles that were reconstituted by the freeze and thaw technique. Evidence was obtained for a protein-induced structural reorganization of these mixed membranes. By differential scanning calorimetry, we were able to construct a phase diagram for the phospholipid/cholesterol mixture consisting of a liquid-ordered, a solid-ordered, and a liquid-disordered phase. Glycophorin at low molar fractions (XG less than 3 X 10(-3)) increases the relative amount of lipid in the liquid-ordered phase, which is interpreted as an enrichment of cholesterol in the vicinity of the protein. The formation of such steroid-enriched domains could be demonstrated directly by electron paramagnetic resonance using a spin-labeled cholesterol analogue. A drastic increase of the spin-spin interaction of the labeled steroid was observed in the presence of glycophorin.     

ABCG transporters export cutin precursors for the formation of the plant cuticle

1. Download : Download high-res image (193KB)
2. Download : Download full-size image