Publications by authors named "Roger Leigh"

Recalcitrant chronic infections of implanted medical devices are often linked to the presence of biofilms. The prevention and treatment of medical device-associated infections is a major source of antibiotic use and driver of antimicrobial resistance globally. Lowering the incidence of infection in patients that receive implanted medical devices could therefore significantly improve antibiotic stewardship and reduce patient morbidity.

View Article and Find Full Text PDF

Faced with the need to support a growing number of whole slide imaging (WSI) file formats, our team has extended a long-standing community file format (OME-TIFF) for use in digital pathology. The format makes use of the core TIFF specification to store multi-resolution (or "pyramidal") representations of a single slide in a flexible, performant manner. Here we describe the structure of this format, its performance characteristics, as well as an open-source library support for reading and writing pyramidal OME-TIFFs.

View Article and Find Full Text PDF

Immune responses occur as a result of stochastic interactions between a plethora of different cell types and molecules that regulate the migration and function of innate and adaptive immune cells to drive protection from pathogen infection. The trafficking of immune cells into peripheral tissues during inflammation and then subsequent migration to draining lymphoid tissues has been quantitated using radiolabelled immune cells over 40 years ago. However, how these processes lead to efficient immune responses was unclear.

View Article and Find Full Text PDF

High content screening (HCS) experiments create a classic data management challenge-multiple, large sets of heterogeneous structured and unstructured data, that must be integrated and linked to produce a set of "final" results. These different data include images, reagents, protocols, analytic output, and phenotypes, all of which must be stored, linked and made accessible for users, scientists, collaborators and where appropriate the wider community. The OME Consortium has built several open source tools for managing, linking and sharing these different types of data.

View Article and Find Full Text PDF

Imaging data are used in the life and biomedical sciences to measure the molecular and structural composition and dynamics of cells, tissues, and organisms. Datasets range in size from megabytes to terabytes and usually contain a combination of binary pixel data and metadata that describe the acquisition process and any derived results. The OMERO image data management platform allows users to securely share image datasets according to specific permissions levels: data can be held privately, shared with a set of colleagues, or made available via a public URL.

View Article and Find Full Text PDF

Calcium (Ca) is a unique macronutrient with diverse but fundamental physiological roles in plant structure and signalling. In the majority of crops the largest proportion of long-distance calcium ion (Ca(2+)) transport through plant tissues has been demonstrated to follow apoplastic pathways, although this paradigm is being increasingly challenged. Similarly, under certain conditions, apoplastic pathways can dominate the proportion of water flow through plants.

View Article and Find Full Text PDF

• Magnesium accumulates at high concentrations in dicotyledonous leaves but it is not known in which leaf cell types it accumulates, by what mechanism this occurs and the role it plays when stored in the vacuoles of these cell types. • Cell-specific vacuolar elemental profiles from Arabidopsis thaliana (Arabidopsis) leaves were analysed by X-ray microanalysis under standard and serpentine hydroponic growth conditions and correlated with the cell-specific complement of magnesium transporters identified through microarray analysis and quantitative polymerase chain reaction (qPCR). • Mesophyll cells accumulate the highest vacuolar concentration of magnesium in Arabidopsis leaves and are enriched for members of the MGT/MRS2 family of magnesium transporters.

View Article and Find Full Text PDF

The physiological role and mechanism of nutrient storage within vacuoles of specific cell types is poorly understood. Transcript profiles from Arabidopsis thaliana leaf cells differing in calcium concentration ([Ca], epidermis <10 mM versus mesophyll >60 mM) were compared using a microarray screen and single-cell quantitative PCR. Three tonoplast-localized Ca(2+) transporters, CAX1 (Ca(2+)/H(+)-antiporter), ACA4, and ACA11 (Ca(2+)-ATPases), were identified as preferentially expressed in Ca-rich mesophyll.

View Article and Find Full Text PDF

Calcium (Ca) is an essential nutrient for plants and animals, with key structural and signalling roles, and its deficiency in plants can result in poor biotic and abiotic stress tolerance, reduced crop quality and yield. Likewise, low Ca intake in humans has been linked to various diseases (e.g.

View Article and Find Full Text PDF

Naturally-occurring variation in K(+) concentrations between plant genotypes is potentially exploitable in a number of ways, including altering the relationship between K(+) accumulation and growth, enhancing salinity resistance, or improving forage quality. However, achieving these requires greater insight into the genetic basis of the variation in tissue K(+) concentrations. To this end, K(+) concentrations were measured in the shoots of 70 Arabidopsis thaliana accessions and a Cape Verdi Island/Landsberg erecta recombinant inbred line (RIL) population.

View Article and Find Full Text PDF

Citrus leaves accumulate large amounts of calcium that must be compartmented effectively to prevent stomatal closure by extracellular Ca2+ and interference with Ca(2+)-based cell signaling pathways. Using x-ray microanalysis, the distribution of calcium between vacuoles in different cell types of leaves of rough lemon (Citrus jambhiri Lush.) was investigated.

View Article and Find Full Text PDF

Storage of excess nitrate in the vacuole and its subsequent remobilization is an important aspect of a plant's nitrogen economy, but the genes controlling the underlying processes have not all been identified and characterized. Cape Verdi Island (Cvi)/Landsberg erecta (Ler) and Columbia (Col)/Landsberg erecta recombinant inbred line (RIL) populations of Arabidopsis thaliana were used to identify quantitative trait loci (QTL) controlling natural variation in nitrate concentrations. One major and two minor QTLs were found for the Cvi/Ler population and one minor QTL for the Col/Ler RIL.

View Article and Find Full Text PDF

This review discusses how the pressure probe has evolved from an instrument for measuring cell turgor and other water relations parameters into a device for sampling the contents of individual higher plant cells in situ in the living plant. Together with a suite of microanalytical techniques it has permitted the mapping of water and solute relations at the resolution of single cells and has the potential to link quantitatively the traditionally separate areas of water relations and metabolism. The development of the probe is outlined and its modification to measure root pressure and xylem tension described.

View Article and Find Full Text PDF

There are a variety of methods for characterising gene expression at the level of individual cells and for demonstrating that the cells also contain the encoded proteins. However, measuring the activity of enzymes at the resolution of single cells in complex tissues, such as leaves, is problematic. We have addressed this by using single-cell sampling to extract 10-100 pl droplets of sap from individual plant cells and then measuring enzyme activities in these droplets with nanolitre-scale fluorescence-based assays.

View Article and Find Full Text PDF

Triple-barrelled microelectrodes measuring K(+) activity (a(K)), pH and membrane potential were used to make quantitative measurements of vacuolar and cytosolic a(K) in epidermal and mesophyll cells of barley plants grown in nutrient solution with 0 or 200 mM added NaCl. Measurements of a(K) were assigned to the cytosol or vacuole based on the pH measured. In epidermal cells, the salt treatment decreased a(K) in the vacuole from 224 to 47 mM and in the cytosol from 68 to 15 mM.

View Article and Find Full Text PDF

The high affinity potassium transporter, HKT1 from wheat was introduced into Florida wheat in sense and antisense orientation under control of a ubiquitin promoter. Ten transgenic lines expressing the transgene were identified and two of these showed strong down-regulation of the native HKT1 transcript. One line (271) was expressing the antisense construct and the other (223) was expressing a truncated sense construct.

View Article and Find Full Text PDF