LytR-CpsA-Psr proteins in Staphylococcus aureus display partial functional redundancy and the deletion of all three severely impairs septum placement and cell separation

Staphylococcus aureus contains three members of the LytR-CpsA-Psr (LCP) family of membrane proteins: MsrR, SA0908 and SA2103. The characterization of single-, double- and triple-deletion mutants revealed distinct phenotypes for each of the three proteins. MsrR was involved in cell separation and septum formation and influenced β-lactam resistance; SA0908 protected cells from autolysis; and SA2103, although displaying no apparent phenotype by itself, enhanced the properties of msrR and sa0908 mutants when deleted. The deletion of sa0908 and sa2103 also further attenuated the virulence of msrR mutants in a nematode-killing assay. The severely defective growth phenotype of the triple mutant revealed that LytR-CpsA-Psr proteins are essential for optimal cell division in S. aureus. Growth could be rescued to varying degrees by any one of the three proteins, indicating some functional redundancy within members of this protein family. However, differing phenotypic characteristics of all single and double mutants and complemented triple mutants indicated that each protein played a distinct role(s) and contributed differently to phenotypes influencing cell separation, autolysis, cell surface properties and virulenc

Independent and combined effects of improved water, sanitation, and hygiene, and improved complementary feeding, on child stunting and anaemia in rural Zimbabwe: a cluster-randomised trial.

BACKGROUND: Child stunting reduces survival and impairs neurodevelopment. We tested the independent and combined effects of improved water, sanitation, and hygiene (WASH), and improved infant and young child feeding (IYCF) on stunting and anaemia in in Zimbabwe. METHODS: We did a cluster-randomised, community-based, 2 × 2 factorial trial in two rural districts in Zimbabwe. Clusters were defined as the catchment area of between one and four village health workers employed by the Zimbabwe Ministry of Health and Child Care. Women were eligible for inclusion if they permanently lived in clusters and were confirmed pregnant. Clusters were randomly assigned (1:1:1:1) to standard of care (52 clusters), IYCF (20 g of a small-quantity lipid-based nutrient supplement per day from age 6 to 18 months plus complementary feeding counselling; 53 clusters), WASH (construction of a ventilated improved pit latrine, provision of two handwashing stations, liquid soap, chlorine, and play space plus hygiene counselling; 53 clusters), or IYCF plus WASH (53 clusters). A constrained randomisation technique was used to achieve balance across the groups for 14 variables related to geography, demography, water access, and community-level sanitation coverage. Masking of participants and fieldworkers was not possible. The primary outcomes were infant length-for-age Z score and haemoglobin concentrations at 18 months of age among children born to mothers who were HIV negative during pregnancy. These outcomes were analysed in the intention-to-treat population. We estimated the effects of the interventions by comparing the two IYCF groups with the two non-IYCF groups and the two WASH groups with the two non-WASH groups, except for outcomes that had an important statistical interaction between the interventions. This trial is registered with ClinicalTrials.gov, number NCT01824940. FINDINGS: Between Nov 22, 2012, and March 27, 2015, 5280 pregnant women were enrolled from 211 clusters. 3686 children born to HIV-negative mothers were assessed at age 18 months (884 in the standard of care group from 52 clusters, 893 in the IYCF group from 53 clusters, 918 in the WASH group from 53 clusters, and 991 in the IYCF plus WASH group from 51 clusters). In the IYCF intervention groups, the mean length-for-age Z score was 0·16 (95% CI 0·08-0·23) higher and the mean haemoglobin concentration was 2·03 g/L (1·28-2·79) higher than those in the non-IYCF intervention groups. The IYCF intervention reduced the number of stunted children from 620 (35%) of 1792 to 514 (27%) of 1879, and the number of children with anaemia from 245 (13·9%) of 1759 to 193 (10·5%) of 1845. The WASH intervention had no effect on either primary outcome. Neither intervention reduced the prevalence of diarrhoea at 12 or 18 months. No trial-related serious adverse events, and only three trial-related adverse events, were reported. INTERPRETATION: Household-level elementary WASH interventions implemented in rural areas in low-income countries are unlikely to reduce stunting or anaemia and might not reduce diarrhoea. Implementation of these WASH interventions in combination with IYCF interventions is unlikely to reduce stunting or anaemia more than implementation of IYCF alone. FUNDING: Bill & Melinda Gates Foundation, UK Department for International Development, Wellcome Trust, Swiss Development Cooperation, UNICEF, and US National Institutes of Health.The SHINE trial is funded by the Bill & Melinda Gates Foundation (OPP1021542 and OPP113707); UK Department for International Development; Wellcome Trust, UK (093768/Z/10/Z, 108065/Z/15/Z and 203905/Z/16/Z); Swiss Agency for Development and Cooperation; US National Institutes of Health (2R01HD060338-06); and UNICEF (PCA-2017-0002)

Oxidation-Induced Dispersion of Gold on Ru(0001): A Scanning Tunneling Microscopy Study

With scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) we studied the redox properties of Au islands supported on Ru(0001) as a function of the island thickness. Both the size and the height of Au islands on Ru(0001) can be controlled by the density of the oxygen precoverage on ruthenium and the sample temperature during the deposition of gold. The oxidation of the Au islands at 300 K was accomplished by exposing atomic oxygen produced from a thermal gas cracker. Regardless of the lateral size of the three monolayer (ML) thick Au islands, the oxidation leads to a fragmentation into a number of small particles (3–5 nm) whose arrangement reflects the shape of the former intact Au islands. This oxygen-induced dispersion of Au on Ru(0001) is explained by a shoveling process. Quite in contrast, no fragmentation of the 4–5 ML thick Au islands into smaller entities is observed. Rather, the entire Au island transforms into one big particle. From Au 4f core level spectroscopy we provide evidence that the nanoparticles consist of Au oxide and metallic Au. The Au oxide/Au particles can be reduced by thermal annealing to 670 K under vacuum or by chemical reduction via CO exposure at 670 K, forming again extended Au islands. However, reduction of Au oxide/Au metal particles by CO exposure at room temperature retains the high dispersion of the prior formed nanoparticles

Nanoscale Origin of Mesoscale Roughening: Real-Time Tracking and Identification of Three Distinct Ruthenium Oxide Phases in Ruthenium Oxidation

The structural modification of the Ru(0001) surface is followed <i>in real-time</i> using low-energy electron microscopy at elevated temperatures during exposure to molecular oxygen. We observe the nucleation and growth of three different RuO₂ facets, which are unambiguously identified by single-domain microspot low-energy electron diffraction (μLEED) analysis from regions of 250 nm in diameter. Structural identification is then pushed to the true nanoscale by employing very-low-energy electron reflectivity spectra <i>R</i>(<i>E</i>) from regions down to 10 nm for structural fingerprinting of complex reactions such as the oxidation of metal surfaces. Calculations of <i>R</i>(<i>E</i>) with an <i>ab initio</i> scattering theory confirm the growth of (110), (100), and (101) orientations of RuO₂ and explain the shape of the <i>R</i>(<i>E</i>) spectra in terms of the conducting band structure. This methodology is ideally suited to identify the structure of supported ultrathin films and dynamic transformations at multicomponent interfaces down to few nanometer lateral resolution at elevated temperature and in reactive environments