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Presentation of the variant antigen, Plasmodium falciparum erythrocyte membrane protein 1 (EMP1), at knob-like protrusions on the surface of infected red blood cells, underpins the parasite’s pathogenicity. Here we describe a protein PF3D7_0301700 (PTP7), that functions at the nexus between the intermediate trafficking organelle, the Maurer’s cleft, and the infected red blood cell surface. Genetic disruption of PTP7 leads to accumulation of vesicles at the Maurer’s clefts, grossly aberrant knob morphology, and failure to deliver EMP1 to the red blood cell surface. We show that an expanded low complexity sequence in the C-terminal region of PTP7, identified only in the Laverania clade of Plasmodium, is critical for efficient virulence protein trafficking.

Additional File 2. Supplementary methods and results for immunogenicity assessments of GAP vaccine. Text S1. Methodology for determining antibody mediated immune response to GAP vaccine. Text S2. Methodology for determining cell mediated immune response to GAP vaccine. Table S1. Antibodies used for flow cytometry. Figure S1. The gating strategy used to identify CD4+ T cells and subsets, as well as the expression of T cell activation markers. Figure S2. The anti-MSP2 IgM response over the course of the study in each subject. Figure S3. The IgG and IgM response to whole parasite lysate over the course of the study in each subject. Figure S4. The frequency of CD4+ T cells, Treg cells, Th1 cells and Tfh cells in peripheral blood mononuclear cells over the course of the study in each subject.

Additional File 3. Supplementary methods and results for in vitro assessments of GAP vaccine. Text S1. Methodology for parasite genotyping. Text S2. Methodology for cytoadherence assays. Text S3. Methodology for scanning electron microscopy. Text S4. Methodology for var gene expression analysis. Table S1. Duration of in vitro culture of P. falciparum prior to harvest for RNA extraction for var gene transcription analysis. Text S5. Results of parasite genotyping. Text S6. Results of scanning electron microscopy analysis of parasite-infected erythrocytes. Text S7. Results of cytoadherence assays. Text S8. Results of var gene expression analysis. Table S2. Most abundantly expressed var genes.

Additional File 1. Supplementary methods and results for subject eligibility and safety assessments. Text S1: Subject eligibility criteria. Table S1: Incidence of adverse events by subject. Table S2: Red blood cell alloantibody test results for Cohort 4 and phenotype of donor red blood cells used for GAP master cell bank manufacture.

Dispersion of carbon nanotubes in water with the aid of surfactants is becoming common practice, however methodologies vary greatly among the literature. Here the variables of sonication type, length of processing time and power input are examined to find optimal values for dispersion of arc-discharge nanotubes in sodium dodecylbenzene sulfonate.

The occupied valence electronic states of single-walled carbon nanotubes (SWCNTs) are responsible for their optoelectronic properties and are unique for each SWCNT chirality. Photoemission spectroscopy (PES) is one of the few methods capable of directly measuring the electron density in the valence states of materials, but there are only a few reports which have observed the valence states of SWCNTs and no examples for single-chirality SWCNTs. Here, we prepare single- and mixed-chirality SWCNT films and characterize their valence states using PES. Chirality-pure SWCNTs were isolated using both gel permeation chromatography and single-stranded DNA-facilitated aqueous two-phase extraction from starting materials consisting of mixed-chirality species. Chirality separation and purity was confirmed with UV-vis-NIR absorption spectroscopy. SWCNT films were prepared for the single-chirality species (10,3), (7,6), (7,3), (6,5), (8,3), (9,1) along with SWCNT chirality mixture of metallic and semiconducting SWCNTs, and as-synthesized mixtures possessing a range of SWCNT diameter. PES using synchrotron radiation was completed for all samples with survey and C 1s core-level spectra obtained to confirm SWCNT coverage, defect level, and purity. Valence band PES was obtained to characterize the valence electronic states and showed significant broadening of the signal, in comparison to calculated density of states, which could not be accounted for by instrument resolution. An inverse diameter dependence of the broadening was observed with greater broadening for smaller-diameter SWCNTs. The broadening is hypothesized to be related to the photohole lifetime, which was found to be significantly longer for wide-diameter SWCNTs. The diameter dependence of the broadening and photohole lifetimes is discussed in terms of both Tomonaga-Luttinger and Landau theories of Fermi liquids. Refereed/Peer-reviewed

Cantilever devices have found applications in numerous scientific fields and instruments, including the atomic force microscope (AFM), and as sensors to detect a wide range of chemical and biological species. The mechanical properties, in particular, the spring constant of these devices is crucial when quantifying adhesive forces, material properties of surfaces, and in determining deposited mass for sensing applications. A key component in the spring constant of a cantilever is the plan-view shape. In recent years, the trapezoidal plan-view shape has become available since it offers certain advantages to fast-scanning AFM and can improve sensor performance in fluid environments. Euler beam equations relating cantilever stiffness to the cantilever dimensions and Young&rsquo, s modulus have been proven useful and are used extensively to model cantilever mechanical behaviour and calibrate the spring constant. In this work, we derive a simple correction factor to the Euler beam equation for a beam-shaped cantilever that is applicable to any cantilever with a trapezoidal plan-view shape. This correction factor is based upon previous analytical work and simplifies the application of the previous researchers formula. A correction factor to the spring constant of an AFM cantilever is also required to calculate the torque produced by the tip when it contacts the sample surface, which is also dependent on the plan-view shape. In this work, we also derive a simple expression for the torque for triangular plan-view shaped cantilevers and show that for the current generation of trapezoidal plan-view shaped AFM cantilevers, this will be a good approximation. We shall apply both these correction factors to determine Young&rsquo, s modulus for a range of trapezoidal-shaped AFM cantilevers, which are specially designed for fast-scanning. These types of AFM probes are much smaller in size when compared to standard AFM probes. In the process of analysing the mechanical properties of these cantilevers, important insights are also gained into their spring constant calibration and dimensional factors that contribute to the variability in their spring constant.