Microbial growth rates and local external mass transfer coefficients in a porous bed biofilm system measured by F magnetic resonance imaging of structure, oxygen concentration, and flow velocity.

F nuclear magnetic resonance (NMR) oximetry and H NMR velocimetry were used to noninvasively map oxygen concentrations and hydrodynamics in space and time in a model packed bed biofilm system in the presence and absence of flow. The development of a local oxygen sink associated with a single gel bead inoculated with respiring Escherichia coli was analyzed with a phenomenological model to determine the specific growth rate of the bacteria in situ, returning a value (0.66 hr ) that was close to that measured independently in planktonic culture (0.

Non-invasive imaging of oxygen concentration in a complex in vitro biofilm infection model using F MRI: Persistence of an oxygen sink despite prolonged antibiotic therapy.

Purpose: Oxygen availability is a critical determinant of microbial biofilm activity and antibiotic susceptibility. However, measuring oxygen gradients in these systems remains difficult, with the standard microelectrode approach being both invasive and limited to single-point measurement. The goal of the study was to develop a F MRI approach for 2D oxygen mapping in biofilm systems and to visualize oxygen consumption behavior in real time during antibiotic therapy.

Spatiotemporal mapping of oxygen in a microbially-impacted packed bed using F Nuclear magnetic resonance oximetry.

F magnetic resonance has been used in the medical field for quantifying oxygenation in blood, tissues, and tumors. The F NMR oximetry technique exploits the affinity of molecular oxygen for liquid fluorocarbon phases, and the resulting linear dependence of F spin-lattice relaxation rate R on local oxygen concentration. Bacterial biofilms, aggregates of bacteria encased in a self-secreted matrix of extracellular polymers, are important in environmental, industrial, and clinical settings and oxygen gradients represent a critical determinant of biofilm function.

Structured inquiry-based learning: Drosophila GAL4 enhancer trap characterization in an undergraduate laboratory course.

We have developed and tested two linked but separable structured inquiry exercises using a set of Drosophila melanogaster GAL4 enhancer trap strains for an upper-level undergraduate laboratory methods course at Bucknell University. In the first, students learn to perform inverse PCR to identify the genomic location of the GAL4 insertion, using FlyBase to identify flanking sequences and the primary literature to synthesize current knowledge regarding the nearest gene. In the second, we cross each GAL4 strain to a UAS-CD8-GFP reporter strain, and students perform whole mount CNS dissection, immunohistochemistry, confocal imaging, and analysis of developmental expression patterns.