Time-lapse imaging of CD63 dynamics at the HIV-1 virological synapse by using agar pads.

Time-lapse imaging provides an uninterrupted observation method that can lead to understanding protein dynamics. We previously developed a technique based on thin agar pads to keep the cells in focus during confocal laser scanning microscope imaging. Using this method, time-lapse imaging was employed to monitor CD63 fused to mCherry at the virological synapse (VS) during viral cluster transfer to acceptor cells of the human immunodeficiency virus 1 (HIV-1).

The large extracellular loop of CD63 interacts with gp41 of HIV-1 and is essential for establishing the virological synapse.

Human immunodeficiency virus type 1 (HIV-1) persists lifelong in infected individuals and has evolved unique strategies in order to evade the immune system. One of these strategies is the direct cell-to-cell spread of HIV-1. The formation of a virological synapse (VS) between donor and target cell is important for this process.

tANCHOR: a novel mammalian cell surface peptide display system.

A novel tool for the presentation of peptides and small proteins on the surface of human cells has been developed. Our tANCHOR system utilizes tetraspanin anchors containing heterologous amino acid sequences inserted instead of the large extracellular loop. This technology allows a highly effective extracellular display of epitopes for antibody binding studies and many other potential applications.

Investigating the Detrimental Effects of Low Pressure Plasma Sterilization on the Survival of Bacillus subtilis Spores Using Live Cell Microscopy.

Plasma sterilization is a promising alternative to conventional sterilization methods for industrial, clinical, and spaceflight purposes. Low pressure plasma (LPP) discharges contain a broad spectrum of active species, which lead to rapid microbial inactivation. To study the efficiency and mechanisms of sterilization by LPP, we use spores of the test organism Bacillus subtilis because of their extraordinary resistance against conventional sterilization procedures.

Easy and low-cost stable positioning of suspension cells during live-cell imaging.

Dynamic processes of cells can be best monitored when living cells are analyzed by imaging. While it is easy to observe adherent living cells it has been extremely challenging to analyze suspension cells. This cell type floats freely in the culture dish, and it is only a question of time when the focus or the observation field is lost.

Identification of Differentially Expressed Genes during Spore Outgrowth in High-Salinity Environments Using RNA Sequencing.

In its natural habitat, the soil bacterium often has to cope with fluctuating osmolality and nutrient availability. Upon nutrient depletion it can form dormant spores, which can revive to form vegetative cells when nutrients become available again. While the effects of salt stress on spore germination have been analyzed previously, detailed knowledge on the salt stress response during the subsequent outgrowth phase is lacking.

Improvement of Biological Indicators by Uniformly Distributing Bacillus subtilis Spores in Monolayers To Evaluate Enhanced Spore Decontamination Technologies.

Novel decontamination technologies, including cold low-pressure plasma and blue light (400 nm), are promising alternatives to conventional surface decontamination methods. However, the standardization of the assessment of such sterilization processes remains to be accomplished. Bacterial endospores of the genera Bacillus and Geobacillus are frequently used as biological indicators (BIs) of sterility.

A simple procedure to analyze positions of interest in infectious cell cultures by correlative light and electron microscopy.

Plastic cell culture dishes that contain a thin bottom of highest optical quality including an imprinted finder grid (μ-Dish Grid-500) are optimally suited for routine correlative light and electron microscopy using chemical fixation. Such dishes allow high-resolution fluorescence and bright-field imaging using fixed and living cells and are compatible with standard protocols for scanning and transmission electron microscopy. Ease of use during cell culture and imaging, as well as a tight cover render the dishes particularly suitable for working with infectious organisms up to the highest biosafety level.

Improved plaque assay identifies a novel anti-Chlamydia ceramide derivative with altered intracellular localization.

Chlamydia trachomatis is a medically important human pathogen causing different diseases, including trachoma, the leading cause of preventable blindness in developing countries, and sexually transmitted infections that can lead to infertility and ectopic pregnancies. There is no vaccine against C. trachomatis at present.

Role of galectin-3 in prion infections of the CNS.

Galectin-3 is a multi-functional protein and participates in mediating inflammatory reactions. The pronounced overexpression of galectin-3 in prion-infected brain tissue prompted us to study the role of this protein in a murine prion model. Immunofluorescence double-labelling identified microglia as the major cell type expressing galectin-3.

Propagation of scrapie in peripheral nerves after footpad infection in normal and neurotoxin exposed hamsters.

As is known from various animal models, the spread of agents causing transmissible spongiform encephalopathies (TSE) after peripheral infection affects peripheral nerves before reaching the central nervous system (CNS) and leading to a fatal end of the disease. The lack of therapeutic approaches for TSE is partially due to the limited amount of information available on the involvement of host biological compartments and processes in the propagation of the infectious agent. The in vivo model presented here can provide information on the spread of the scrapie agent via the peripheral nerves of hamsters under normal and altered axonal conditions.

Transcriptional activity of the host-interaction locus and a putative pilin gene of Bdellovibrio bacteriovorus in the predatory life cycle.

Bdellovibrio bacteriovorus is a predatory bacterium that grows and replicates within the periplasm of a large variety of Gram-negative bacteria. So far, the host-interaction locus (hit locus) is the only genetic locus that is implicated in the obligate predatory lifestyle. Sequence analysis revealed that upstream of the hit locus, the genomic regions of the two obligate predatory B.

The absence of D-alanine from lipoteichoic acid and wall teichoic acid alters surface charge, enhances autolysis and increases susceptibility to methicillin in Bacillus subtilis.

In the physiological consequences of depriving lipoteichoic acid and wall teichoic acid of D-alanine ester were analysed using insertional inactivation of the genes of the operon. Mutant strains which lacked positively charged D-alanine ester in teichoic acids bound more positively charged cytochrome C than other strains. These mutant strains also showed enhanced autolysis and a higher susceptibility to methicillin, which was expressed as accelerated wall lysis, a faster loss of viability and a slower recovery in the postantibiotic phase.