Suchergebnisse

This is the final version. Available on open access from the Royal Society of Chemistry via the DOI in this record ; The dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.2863 ; We show how an asymmetric elasto-magnetic system provides a novel integrated pumping solution for lab-on-a-chip and point of care devices. This monolithic pumping solution, inspired by Purcell's 3-link swimmer, is integrated within a simple microfluidic device, bypassing the requirement of external connections. We experimentally prove that this system can provide tuneable fluid flow with a flow rate of up to 600 μL h-1. This fluid flow is achieved by actuating the pump using a weak, uniform, uniaxial, oscillating magnetic field, with field amplitudes in the range of 3-6 mT. Crucially, the fluid flow can be reversed by adjusting the driving frequency. We experimentally prove that this device can successfully operate on fluids with a range of viscosities, where pumping at higher viscosity correlates with a decreasing optimal driving frequency. The fluid flow produced by this device is understood here by examining the non-reciprocal motion of the elasto-magnetic component. This device has the capability to replace external pumping systems with a simple, integrated, lab-on-a-chip component. ; Engineering and Physical Sciences Research Council (EPSRC) ; European Union Horizon 2020 ; Medical Research Council (MRC) ; Royal Society ; Wellcome Trust

This is the final version. Available on open access from Cell Press via the DOI in this record ; Data and code availability: Source data are available at Mendeley Data: https://doi.org/10.17632/gbdfwg325y.1 This paper does not report original code. Any additional information required to reanalyse the data reported in this paper is available from the lead contact upon request. ; Phages impose strong selection on bacteria to evolve resistance against viral predation. Bacteria can rapidly evolve phage resistance via receptor mutation or using their CRISPR-Cas adaptive immune systems. Acquisition of CRISPR immunity relies on the insertion of a phage-derived sequence into CRISPR arrays in the bacterial genome. Using Pseudomonas aeruginosa and its phage DMS3vir as a model, we demonstrate that conditions that reduce bacterial growth rates, such as exposure to bacteriostatic antibiotics (which inhibit cell growth without killing), promote the evolution of CRISPR immunity. We demonstrate that this is due to slower phage development under these conditions, which provides more time for cells to acquire phage-derived sequences and mount an immune response. Our data reveal that the speed of phage development is a key determinant of the evolution of CRISPR immunity and suggest that use of bacteriostatic antibiotics can trigger elevated levels of CRISPR immunity in human-associated and natural environments. ; European Union Horizon 2020 ; Natural Environment Research Council (NERC) ; Ministry of Science and Higher Education of the Russian Federation ; National Institutes of Health (NIH) ; Russian Science Foundation

This is the final version. Available on open access from the Royal Society of Chemistry via the DOI in this record ; Data availability: All the data is available in the main text or in the supplementary materials. ; The code associated with this article is located in ORE at: http://hdl.handle.net/10871/121661 ; The double-membrane cell envelope of Gram-negative bacteria is a formidable barrier to intracellular antibiotic accumulation. A quantitative understanding of antibiotic transport in these cells is crucial for drug development, but this has proved elusive due to a dearth of suitable investigative techniques. Here we combine microfluidics and time-lapse auto-fluorescence microscopy to rapidly quantify antibiotic accumulation in hundreds of individual Escherichia coli cells. By serially manipulating the microfluidic environment, we demonstrated that stationary phase Escherichia coli, traditionally more refractory to antibiotics than growing cells, display reduced accumulation of the antibiotic ofloxacin compared to actively growing cells. Our novel microfluidic method facilitates the quantitative comparison of the role of the microenvironment versus various membrane transport pathways in cellular drug accumulation. Unlike traditional techniques, our assay is rapid, studying accumulation as the cells are dosed with the drug. This platform provides a powerful new tool for studying antibiotic accumulation in bacteria, which will be critical for the rational development of the next generation of antibiotics. ; European Commission ; Biotechnology and Biological Sciences Research Council (BBSRC) ; Engineering and Physical Sciences Research Council (EPSRC) ; University of Exeter School of Biosciences ; European Union Horizon 2020 ; Medical Research Council (MRC) ; Royal Society ; Wellcome Trust ; GW4 Initiator award

This is the final version. Available on open access from Nature Research via the DOI in this record ; Data availability; All RNA sequencing data and proteomics data is available in Supplementary Data 1–4. Exact p values, where shown on Figs. 1–5, are available in Supplementary Data 5. The source data underlying Figs. 1–5 are provided as Supplementary Data 6. Any other relevant data are available upon reasonable request. ; The interaction between a cell and its environment shapes fundamental intracellular processes such as cellular metabolism. In most cases growth rate is treated as a proximal metric for understanding the cellular metabolic status. However, changes in growth rate might not reflect metabolic variations in individuals responding to environmental fluctuations. Here we use single-cell microfluidics-microscopy combined with transcriptomics, proteomics and mathematical modelling to quantify the accumulation of glucose within Escherichia coli cells. In contrast to the current consensus, we reveal that environmental conditions which are comparatively unfavourable for growth, where both nutrients and salinity are depleted, increase glucose accumulation rates in individual bacteria and population subsets. We find that these changes in metabolic function are underpinned by variations at the translational and posttranslational level but not at the transcriptional level and are not dictated by changes in cell size. The metabolic response-characteristics identified greatly advance our fundamental understanding of the interactions between bacteria and their environment and have important ramifications when investigating cellular processes where salinity plays an important role. ; Biotechnology & Biological Sciences Research Council (BBSRC) ; Biotechnology and Biological Sciences Research Council (BBSRC) ; Medical Research Council (MRC) ; Royal Society ; QUEX Initiator grant ; European Union Horizon 2020 ; Gordon and Betty and Gordon Moore Foundation ; Wellcome Trust