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The surface appendages and extracellular polymeric substances of cells play an important role in the bacterial adhesion process. In this work, colloidal forces and nanomechanical properties of Acidithiobacillus ferrooxidans (A. f) interacted with silicon wafer and pyrite (FeS2) surfaces in solutions of varying salt concentrations were quantitatively examined using the bacterial probe technique with atomic force microscopy. A. f cells were cultured with either ferrous sulfate or elemental sulfur as key energy sources. Our results show that A. f cells grown with ferrous ion and elemental sulfur exhibit distinctive retraction force vs separation distance curves with stair-step and saw tooth shapes, respectively. During the approach of bacterial probes to the substrate surfaces, surface appendages and biopolymers of cells are sequentially compressed. The conformations of surface appendages and biopolymers are significantly influenced by the salt concentrations.
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http://dx.doi.org/10.1016/j.colsurfb.2015.05.026 | DOI Listing |
Nat Microbiol
September 2025
Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, USA.
During early stages of biofilm formation, Pseudomonas aeruginosa (Pa) PAO1 can sense exopolysaccharide (EPS) trails of Psl deposited on a surface by previous Pa cells to detect trajectories of other cells and to orchestrate motility. This sensory signal is transduced into cyclic diGMP second messengers, but no known Psl receptors and adhesins participate in signal transduction. Here, using bacteria-secreted Psl trails, glycopolymer-patterned surfaces, longitudinal cell tracking, second messenger dual reporters and genetic mutations targeting EPS binding and surface twitching, we find that Pa is capable of sensing EPS directly through mutually constitutive interactions between type IV pili (T4P)-powered twitching and specific adhesin-EPS bonds.
View Article and Find Full Text PDFThe ion channel-forming natural product amphotericin B (AmB) can serve as a molecular prosthetic for the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel and thereby restore host defenses in cultured cystic fibrosis (CF) airway epithelia. This is despite the fact that the permeability of AmB-based channels favors cations, and these channels lose their capacity to increase airway surface liquid (ASL) pH in CF airway epithelia at high concentrations. We hypothesize that modifying such channels to favor anion permeability would make them more CFTR-like and thus increase their potential therapeutic effects compared to AmB.
View Article and Find Full Text PDFSkin Appendage Disord
May 2025
Phillip Frost Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, Miami, FL, USA.
Introduction: Hidradenitis suppurativa (HS) is an auto-inflammatory disease characterized by recurrent painful nodules, abscesses, tunnels, and scarring, commonly seen in intertriginous body surfaces; however, an additional ulcerative phenotype has not been described and represents a specific clinical phenotype of the disease requiring special therapeutic considerations
Case Presentation: We report 4 patients with a previously undescribed, ulcerative phenotype of HS that did not respond to standard treatment but were healed with surgery. These lesions present as large, deep-dermal, erythematous, well-defined ulcers that are exquisitely tender.
Conclusion: This phenotype necessitates recognition by the clinician as a rapid path to combined pharmacologic and surgical management is crucial for the patient.
Evodevo
August 2025
Marine Biological Section, Department of Biology, University of Copenhagen, Universitetsparken 4, 2100, Copenhagen Ø, Denmark.
Background: Within the symbiont-hosting Siboglinidae (Annelida), Osedax stands out as the sole genus capable of degrading bones and displaying pronounced sexual dimorphism (except O. priapus). While macroscopic, gutless females feed on whale falls with their symbiont-housing "roots", males are microscopic and non-feeding.
View Article and Find Full Text PDFBMC Biol
August 2025
Division of Biological Sciences, The University of Montana, Missoula, MT, 59812, USA.
Background: Evolution of microbes under laboratory selection produces genetically diverse populations, owing to the continuous input of mutations and to competition among lineages. Whole-genome whole-population sequencing makes it possible to identify mutations arising in such populations, to use them to discern functional modules where adaptation occurs, and then map gene structure-function relationships. Here, we report on the use of this approach, adaptive genetics, to discover targets of selection and the mutational consequences thereof in E.
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