The accumulation and growth of Pseudomonas aeruginosa on surfaces is modulated by surface mechanics via cyclic-di-GMP signaling.

Attachment of bacteria onto a surface, consequent signaling, and accumulation and growth of the surface-bound bacterial population are key initial steps in the formation of pathogenic biofilms. While recent reports have hinted that surface mechanics may affect the accumulation of bacteria on that surface, the processes that underlie bacterial perception of surface mechanics and modulation of accumulation in response to surface mechanics remain largely unknown. We use thin and thick hydrogels coated on glass to create composite materials with different mechanics (higher elasticity for thin composites; lower elasticity for thick composites) but with the same surface adhesivity and chemistry.

Nanofiber-Based Substrate for a Triboelectric Nanogenerator: High-Performance Flexible Energy Fiber Mats.

Flexible and stretchable triboelectric nanogenerators (TENGs) are the next-generation systems for wearable and portable electronics. In this study, we have demonstrated an all nanofiber-based TENG for energy harvesting and biomechanical sensing applications. The TENG was prepared using the Forcespinning (FS) method to produce poly(vinylidene fluoride) (PVDF) and thermoplastic polyurethane (TPU) nanofiber (NF) membranes.

Mechanosensing of shear by leads to increased levels of the cyclic-di-GMP signal initiating biofilm development.

Biofilms are communities of sessile microbes that are phenotypically distinct from their genetically identical, free-swimming counterparts. Biofilms initiate when bacteria attach to a solid surface. Attachment triggers intracellular signaling to change gene expression from the planktonic to the biofilm phenotype.

Neuroprotection of medial septal cholinergic neurons by memantine after intralateral septal injection of Aβ1-40.

Alzheimer's disease (AD) is a progressive disorder of the brain that leads to memory loss, dementia, and death. Several lines of evidence suggest that the accumulation of amyloid-β (Aβ) peptides may trigger the dysfunction and degeneration observed in the AD brain. The basal forebrain, including the septal region, which regulates the excitability of the hippocampus and neocortex, is affected early in AD because its neurons are vulnerable to Aβ peptides.

The extracellular polysaccharide Pel makes the attachment of to surfaces symmetric and short-ranged.

Biofilms are surface-mounted, multicellular communities of microbes. Biofilms are often associated with chronic infections that resist treatment, evade the immune system, and damage host tissue. An essential characteristic of the biofilm state is that constituent organisms are bound in a polymeric matrix.

Amyloid β peptides modify the expression of antioxidant repair enzymes and a potassium channel in the septohippocampal system.

Alzheimer's disease (AD) is a progressive, neurodegenerative brain disorder characterized by extracellular accumulations of amyloid β (Aβ) peptides, intracellular accumulation of abnormal proteins, and early loss of basal forebrain neurons. Recent studies have indicated that the conformation of Aβ is crucial for neuronal toxicity, with intermediate misfolded forms such as oligomers being more toxic than the final fibrillar forms. Our previous work shows that Aβ blocks the potassium (K(+)) currents IM and IA in septal neurons, increasing firing rates, diminishing rhythmicity and firing coherence.

Intrahippocampal amyloid-β (1-40) injections injure medial septal neurons in rats.

Alzheimer's disease (AD) is a devastating disorder that leads to memory loss and dementia. Neurodegeneration of cholinergic neurons in the septum and other basal forebrain areas is evident in early stages of AD. Glutamatergic neurons are also affected early in AD.

Subcellular Min oscillations as a single-cell reporter of the action of polycations, protamine, and gentamicin on Escherichia coli.

Background: In Escherichia coli, MinD-GFP fusion proteins show rapid pole to pole oscillations. The objective was to investigate the effects of extracellular cations on the subcellular oscillation of cytoplasmic MinD within Escherichia coli.

Methodology/principal Findings: We exposed bacteria to the extracellular cations Ca(++), Mg(++), the cationic antimicrobial peptide (CAP) protamine, and the cationic aminoglycoside gentamicin.

Contribution of type IV pili to the virulence of Aeromonas salmonicida subsp. salmonicida in Atlantic salmon (Salmo salar L.).

Aeromonas salmonicida subsp. salmonicida, a bacterial pathogen of Atlantic salmon, has no visible pili, yet its genome contains genes for three type IV pilus systems. One system, Tap, is similar to the Pseudomonas aeruginosa Pil system, and a second, Flp, resembles the Actinobacillus actinomycetemcomitans Flp pilus, while the third has homology to the mannose-sensitive hemagglutinin pilus of Vibrio cholerae.

Molecular recognition forces between immunoglobulin G and a surface protein adhesin on living Staphylococcus aureus.

We report AFM measurements of binding events between immunoglobulin G (IgG) and protein A (PA) on the surface of live Staphylococcus aureus bacteria. The experiments were carried out with IgG molecules tethered via CM-amylose linkers to thiol SAMs on gold-coated AFM tips. For comparison, a model system consisting of protein A molecules tethered to thiol SAMs on gold-coated silicon substrates was also investigated.

The p14 fusion-associated small transmembrane (FAST) protein effects membrane fusion from a subset of membrane microdomains.

The reovirus fusion-associated small transmembrane (FAST) proteins are a unique family of viral membrane fusion proteins. These nonstructural viral proteins induce efficient cell-cell rather than virus-cell membrane fusion. We analyzed the lipid environment in which the reptilian reovirus p14 FAST protein resides to determine the influence of the cell membrane on the fusion activity of the FAST proteins.

Temperature dependence of MinD oscillation in Escherichia coli: running hot and fast.

We observed that the oscillation period of MinD within rod-like and filamentous cells of Escherichia coli varied by a factor of 4 in the temperature range from 20 degrees C to 40 degrees C. The detailed dependence was Arrhenius, with a slope similar to the overall temperature-dependent growth curve of E. coli.

Nanoscale characterization and determination of adhesion forces of Pseudomonas aeruginosa pili by using atomic force microscopy.

Type IV pili play an important role in bacterial adhesion, motility, and biofilm formation. Here we present high-resolution atomic force microscopy (AFM) images of type IV pili from Pseudomonas aeruginosa bacteria. An individual pilus ranges in length from 0.

Liposome reconstitution of a minimal protein-mediated membrane fusion machine.

Biological membrane fusion is dependent on protein catalysts to mediate localized restructuring of lipid bilayers. A central theme in current models of protein-mediated membrane fusion involves the sequential refolding of complex homomeric or heteromeric protein fusion machines. The structural features of a new family of fusion-associated small transmembrane (FAST) proteins appear incompatible with existing models of membrane fusion protein function.

Atomic force microscopy of cell growth and division in Staphylococcus aureus.

The growth and division of Staphylococcus aureus was monitored by atomic force microscopy (AFM) and thin-section transmission electron microscopy (TEM). A good correlation of the structural events of division was found using the two microscopies, and AFM was able to provide new additional information. AFM was performed under water, ensuring that all structures were in the hydrated condition.

Aggregation of yeast cells: direct measurement of discrete lectin-carbohydrate interactions.

Aggregation of microbial cells mediated by specific interactions plays a pivotal role in the natural environment, in medicine and in biotechnological processes. Here we used atomic force microscopy (AFM) to measure individual lectin-carbohydrate interactions involved in the flocculation of yeast cells, an aggregation event of crucial importance in fermentation technology. AFM probes functionalized with oligoglucose carbohydrates were used to record force-distance curves on living yeast cells at a rate of 0.

Real-time imaging of the surface topography of living yeast cells by atomic force microscopy.

Atomic force microscopy (AFM) was used to image the surface topography of living Saccharomyces cerevisiae cells at high resolution and to monitor enzyme digestion of the cell wall in real time. Apart from the presence of bud scars, the surface of native cells imaged in aqueous solution was homogeneous and smooth. Topographic images of the surface were recorded to a lateral resolution of 2 nm without significant modification of the surface morphology.