Multiplex detection of the big five carbapenemase genes using solid-phase recombinase polymerase amplification

Five carbapenemase enzymes, coined the ‘big five’, have been identified as the biggest threat to worldwide antibiotic resistance based on their broad substrate affinity and global prevalence. Here we show the development of a molecular detection method for the gene sequences from the five carbapenemases utilising the isothermal amplification method of recombinase polymerase amplification (RPA). We demonstrate the successful detection of each of the big five carbapenemase genes with femtomolar detection limits using a spatially separated multiplex amplification strategy. The approach uses tailed oligonucleotides for hybridisation, reducing the complexity and cost of the assay compared to classical RPA detection strategies. The reporter probe, horseradish peroxidase, generates the measureable output on a benchtop microplate reader, but more notably, our study leverages the power of a portable Raman spectrometer, enabling up to a 19-fold enhancement in the limit of detection. Significantly, the development approach employed a solid-phase RPA format, wherein the forward primers targeting each of the five carbapenemase genes are immobilised to a streptavidin-coated microplate. The adoption of this solid-phase methodology is pivotal for achieving a successful developmental pathway when employing this streamlined approach. The assay takes 2 hours until result, including a 40 minutes RPA amplification step at 37 °C. This is the first example of using solid-phase RPA for the detection of the big five and represents a milestone towards the developments of an automated point-of-care diagnostic for the big five using RPA

Net landscape carbon balance of a tropical savanna: relative importance of fire and aquatic export in offsetting terrestrial production

The magnitude of the terrestrial carbon (C) sink may be overestimated globally due to the difficulty of accounting for all C losses across heterogeneous landscapes. More complete assessments of net landscape C balances (NLCB) are needed that integrate both emissions by fire and transfer to aquatic systems, two key loss pathways of terrestrial C. These pathways can be particularly significant in the wet–dry tropics, where fire plays a fundamental part in ecosystems and where intense rainfall and seasonal flooding can result in considerable aquatic C export (ΣF). Here, we determined the NLCB of a lowland catchment (~140\ua0km) in tropical Australia over 2\ua0years by evaluating net terrestrial productivity (NEP), fire-related C emissions and ΣF (comprising both downstream transport and gaseous evasion) for the two main landscape components, that is, savanna woodland and seasonal wetlands. We found that the catchment was a large C sink (NLCB 334\ua0Mg\ua0C\ua0km\ua0year), and that savanna and wetland areas contributed 84% and 16% to this sink, respectively. Annually, fire emissions (−56\ua0Mg\ua0C\ua0km\ua0year) and ΣF (−28\ua0Mg\ua0C\ua0km\ua0year) reduced NEP by 13% and 7%, respectively. Savanna burning shifted the catchment to a net C source for several months during the dry season, while ΣF significantly offset NEP during the wet season, with a disproportionate contribution by single major monsoonal events—up to 39% of annual ΣF was exported in one event. We hypothesize that wetter and hotter conditions in the wet–dry tropics in the future will increase ΣF and fire emissions, potentially further reducing the current C sink in the region. More long-term studies are needed to upscale this first NLCB estimate to less productive, yet hydrologically dynamic regions of the wet–dry tropics where our result indicating a significant C sink may not hold

PIXL: Planetary Instrument for X-Ray Lithochemistry

Planetary Instrument for X-ray Lithochemistry (PIXL) is a micro-focus X-ray fluorescence spectrometer mounted on the robotic arm of NASA’s Perseverance rover. PIXL will acquire high spatial resolution observations of rock and soil chemistry, rapidly analyzing the elemental chemistry of a target surface. In 10 seconds, PIXL can use its powerful 120 μm-diameter X-ray beam to analyze a single, sand-sized grain with enough sensitivity to detect major and minor rock-forming elements, as well as many trace elements. Over a period of several hours, PIXL can autonomously raster-scan an area of the rock surface and acquire a hyperspectral map comprised of several thousand individual measured points. When correlated to a visual image acquired by PIXL’s camera, these maps reveal the distribution and abundance variations of chemical elements making up the rock, tied accurately to the physical texture and structure of the rock, at a scale comparable to a 10X magnifying geological hand lens. The many thousands of spectra in these postage stamp-sized elemental maps may be analyzed individually or summed together to create a bulk rock analysis, or subsets of spectra may be summed, quantified, analyzed, and compared using PIXLISE data analysis software. This hand lens-scale view of the petrology and geochemistry of materials at the Perseverance landing site will provide a valuable link between the larger, centimeter- to meter-scale observations by Mastcam-Z, RIMFAX and Supercam, and the much smaller (micron-scale) measurements that would be made on returned samples in terrestrial laboratories.</p

PIXL: Planetary Instrument for X-Ray Lithochemistry

Planetary Instrument for X-ray Lithochemistry (PIXL) is a micro-focus X-ray fluorescence spectrometer mounted on the robotic arm of NASA’s Perseverance rover. PIXL will acquire high spatial resolution observations of rock and soil chemistry, rapidly analyzing the elemental chemistry of a target surface. In 10 seconds, PIXL can use its powerful 120 μm-diameter X-ray beam to analyze a single, sand-sized grain with enough sensitivity to detect major and minor rock-forming elements, as well as many trace elements. Over a period of several hours, PIXL can autonomously raster-scan an area of the rock surface and acquire a hyperspectral map comprised of several thousand individual measured points. When correlated to a visual image acquired by PIXL’s camera, these maps reveal the distribution and abundance variations of chemical elements making up the rock, tied accurately to the physical texture and structure of the rock, at a scale comparable to a 10X magnifying geological hand lens. The many thousands of spectra in these postage stamp-sized elemental maps may be analyzed individually or summed together to create a bulk rock analysis, or subsets of spectra may be summed, quantified, analyzed, and compared using PIXLISE data analysis software. This hand lens-scale view of the petrology and geochemistry of materials at the Perseverance landing site will provide a valuable link between the larger, centimeter- to meter-scale observations by Mastcam-Z, RIMFAX and Supercam, and the much smaller (micron-scale) measurements that would be made on returned samples in terrestrial laboratories

Correction to: PIXL: Planetary Instrument for X-Ray Lithochemistry (Space Science Reviews, (2020), 216, 8, (134), 10.1007/s11214-020-00767-7)

In section: 3 X-Ray Source 3.1 X-Ray Source Overview The following text should not be present: “The X-ray source combines components from multiple organizations. The high-voltage power supply (HVPS), which includes the LVCM, HVMM, and connecting cables, was designed and built by Battel Engineering and the University of Michigan Space Physics Research Laboratory (SPRL). The X-ray tube was designed and built by Moxtek Inc., and the X-ray optic was designed and built by XOS Inc. XOS aligned and integrated the X-ray tube and optic, while SPRL integrated this tube/optic assembly into the XRSA.” Please also find the corrected: Appendix A: Parameters This is a complete list of parameters that are in place when a scan is initiated that are returned in data products. All of these can be changed by uplink (Table presented.).</p