Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

EPO does not promote interaction between the erythropoietin and beta-common receptors

A direct interaction between the erythropoietin (EPOR) and the beta-common (βc) receptors to form an Innate Repair Receptor (IRR) is controversial. On one hand, studies have shown a functional link between EPOR and βc receptor in tissue protection while others have shown no involvement of the βc receptor in tissue repair. To date there is no biophysical evidence to confirm a direct association of the two receptors either in vitro or in vivo. We investigated the existence of an interaction between the extracellular regions of EPOR and the βc receptor in silico and in vitro (either in the presence or absence of EPO or EPO-derived peptide ARA290). Although a possible interaction between EPOR and βc was suggested by our computational and genomic studies, our in vitro biophysical analysis demonstrates that the extracellular regions of the two receptors do not specifically associate. We also explored the involvement of the βc receptor gene (Csf2rb) under anaemic stress conditions and found no requirement for the βc receptor in mice. In light of these studies, we conclude that the extracellular regions of the EPOR and the βc receptor do not directly interact and that the IRR is not involved in anaemic stress

Author Correction: EPO does not promote interaction between the erythropoietin and beta-common receptors (Scientific Reports, (2018), 8, 1, (12457), 10.1038/s41598-018-29865-x)

In Figure 1C, Sites 1 and 2 are incorrectly labelled. The correct Figure 1 appears below.(Figure presented.)

A novel phosphocholine‐mimetic inhibits a pro‐inflammatory conformational change in C‐reactive protein

Abstract C‐reactive protein (CRP) is an early‐stage acute phase protein and highly upregulated in response to inflammatory reactions. We recently identified a novel mechanism that leads to a conformational change from the native, functionally relatively inert, pentameric CRP (pCRP) structure to a pentameric CRP intermediate (pCRP*) and ultimately to the monomeric CRP (mCRP) form, both exhibiting highly pro‐inflammatory effects. This transition in the inflammatory profile of CRP is mediated by binding of pCRP to activated/damaged cell membranes via exposed phosphocholine lipid head groups. We designed a tool compound as a low molecular weight CRP inhibitor using the structure of phosphocholine as a template. X‐ray crystallography revealed specific binding to the phosphocholine binding pockets of pCRP. We provide in vitro and in vivo proof‐of‐concept data demonstrating that the low molecular weight tool compound inhibits CRP‐driven exacerbation of local inflammatory responses, while potentially preserving pathogen‐defense functions of CRP. The inhibition of the conformational change generating pro‐inflammatory CRP isoforms via phosphocholine‐mimicking compounds represents a promising, potentially broadly applicable anti‐inflammatory therapy

Figure S1 from Distinct Assemblies of Heterodimeric Cytokine Receptors Govern Stemness Programs in Leukemia

IL3Rα/βc transcript and protein expression ratio in AML patient samples.</p

Figure S2 from Distinct Assemblies of Heterodimeric Cytokine Receptors Govern Stemness Programs in Leukemia

Key interactions between distinct residues in the IL-3R ternary complex crystal structure.</p

Figure S5 from Distinct Assemblies of Heterodimeric Cytokine Receptors Govern Stemness Programs in Leukemia

Enrichment of the IL-3R hexamer versus dodecamer gene signature in primitive normal and leukemic stem cells.</p

Figure S3 from Distinct Assemblies of Heterodimeric Cytokine Receptors Govern Stemness Programs in Leukemia

IL3Rα P248 at the IL-3R assembly interface is critical for cell differentiation.</p

Figure S4 from Distinct Assemblies of Heterodimeric Cytokine Receptors Govern Stemness Programs in Leukemia

The IL-3R dodecamer activates STAT1 to induce cell differentiation.</p