A conserved hub protein for coordinating peptidoglycan turnover that activates cell division amidases in .

Unlabelled: Gram-negative bacteria produce a multilayered cell envelope in which their peptidoglycan is sandwiched between two membranes, an inner membrane made of glycerophospholipids and an asymmetric outer membrane with glycerophospholipids in the inner leaflet and lipopolysaccharide (LPS) in the outer leaflet. The outer membrane contains lipooligosaccharide (LOS), a variant of LPS lacking O-antigen. LPS/LOS is typically essential, but can survive without LOS.

CadB is capable of promiscuously transporting muropeptides and contributing to peptidoglycan recycling.

The bacterial peptidoglycan (PG) cell wall is remodeled during growth and division, releasing fragments called muropeptides. Muropeptides can be internalized and reused in a process called PG recycling. is highly devoted to recycling muropeptides and is known to have at least two transporters, AmpG and OppBCDF, that import them into the cytoplasm.

Absence of YhdP, TamB, and YdbH leads to defects in glycerophospholipid transport and cell morphology in Gram-negative bacteria.

The outer membrane (OM) of Gram-negative bacteria provides the cell with a formidable barrier that excludes external threats. The two major constituents of this asymmetric barrier are lipopolysaccharide (LPS) found in the outer leaflet, and glycerophospholipids (GPLs) in the inner leaflet. Maintaining the asymmetric nature and balance of LPS to GPLs in the OM is critical for bacterial viability.

Acinetobacter baumannii Can Survive with an Outer Membrane Lacking Lipooligosaccharide Due to Structural Support from Elongasome Peptidoglycan Synthesis.

Gram-negative bacteria resist external stresses due to cell envelope rigidity, which is provided by two membranes and a peptidoglycan layer. The outer membrane (OM) surface contains lipopolysaccharide (LPS; contains O-antigen) or lipooligosaccharide (LOS). LPS/LOS are essential in most Gram-negative bacteria and may contribute to cellular rigidity.

Self-assembly of N-heterocyclic carbenes on Au(111).

Although the self-assembly of organic ligands on gold has been dominated by sulfur-based ligands for decades, a new ligand class, N-heterocyclic carbenes (NHCs), has appeared as an interesting alternative. However, fundamental questions surrounding self-assembly of this new ligand remain unanswered. Herein, we describe the effect of NHC structure, surface coverage, and substrate temperature on mobility, thermal stability, NHC surface geometry, and self-assembly.

Simulations of X-ray absorption spectroscopy and energetic conformation of N-heterocyclic carbenes on Au(111).

It has recently been demonstrated that N-heterocyclic carbenes (NHCs) form self-assembled monolayers (SAMs) on metal surfaces. Consequently, it is important to both characterize and understand their binding modes to fully exploit NHCs in functional surface systems. To assist with this effort, we have performed first-principles total energy calculations for NHCs on Au(111) and simulations of X-ray absorption near edge structure (XANES).

A Whole-Cell Screen Identifies Small Bioactives That Synergize with Polymyxin and Exhibit Antimicrobial Activities against Multidrug-Resistant Bacteria.

The threat of diminished antibiotic discovery has global health care in crisis. In the United States, it is estimated each year that over 2 million bacterial infections are resistant to first-line antibiotic treatments and cost in excess of 20 billion dollars. Many of these cases result from infection with the ESKAPE pathogens ( , , , , , and species), which are multidrug-resistant bacteria that often cause community- and hospital-acquired infections in both healthy and immunocompromised patients.

Simple direct formation of self-assembled N-heterocyclic carbene monolayers on gold and their application in biosensing.

The formation of organic films on gold employing N-heterocyclic carbenes (NHCs) has been previously shown to be a useful strategy for generating stable organic films. However, NHCs or NHC precursors typically require inert atmosphere and harsh conditions for their generation and use. Herein we describe the use of benzimidazolium hydrogen carbonates as bench stable solid precursors for the preparation of NHC films in solution or by vapour-phase deposition from the solid state.

Surface and near surface defects in δ-doped Si(1 1 1).

The B/Si(1 1 1)- (√3 x √3)R30° surface reconstruction has recently been used as a platform for supramolecular assembly. However, our understanding of the native defects in this delta-doped system and their corresponding scanning tunnelling microscopy (STM) signatures is incomplete. So we have studied this system using ab initio total energy calculations and scanning tunneling microscopy.

Ultra stable self-assembled monolayers of N-heterocyclic carbenes on gold.

Since the first report of thiol-based self-assembled monolayers (SAMs) 30 years ago, these structures have been examined in a huge variety of applications. The oxidative and thermal instabilities of these systems are widely known, however, and are an impediment to their widespread commercial use. Here, we describe the generation of N-heterocyclic carbene (NHC)-based SAMs on gold that demonstrate considerably greater resistance to heat and chemical reagents than the thiol-based counterparts.

Room temperature discrimination of adsorbed molecules and attachment sites on the Si(111)-7 × 7 surface using a qPlus sensor.

In this paper, we show that simultaneous noncontact atomic force microscopy (nc-AFM) and scanning tunneling microscopy (STM) is a powerful tool for molecular discrimination on the Si(111)-7 × 7 surface, even at room temperature. Using density functional theory modeling, we justify this approach and show that the force response allows us to distinguish straightforwardly between molecular adsorbates and common defects, such as vacancies. Finally, we prove that STM/nc-AFM method is able to determine attachment sites of molecules deposited on semiconductor surface at room temperature.

Briareolate esters from the gorgonian Briareum asbestinum.

Two new briarane diterpenoids briareolate esters J (1) and K (2) were isolated from the methanolic extract of the octocoral Briareum asbestinum collected off the coast of Boca Raton, Florida. The structures of briaranes 1 and 2 were elucidated by interpretation of spectroscopic data. Briareolate ester K (2) showed weak growth inhibition activity against human embryonic stem cells (BG02).

Stability, interaction and influence of domain boundaries in Ge/Si(111)-5 × 5.

We present a theoretical investigation of the influence of domain boundaries on the Ge/Si(111)-5 × 5 phase using both large-scale DFT simulations and an analytical model. It is shown that different boundary types modify the atomic and electronic structure of the adjoining 5 × 5 domains in very different ways. A simple theoretical model, that describes the energy interaction J between the boundaries and the 5 × 5 phase, is presented and the interaction energy decay J(x) ≈ x(-n) for different domain boundaries is estimated.

Bicyclic C21 terpenoids from the marine sponge Clathria compressa.

Three new bicyclic C(21) terpenoids, clathric acid (1) and two N-acyl taurine derivatives, clathrimides A (2) and B (3), were isolated from the marine sponge Clathria compressa. The structures of these compounds were elucidated by interpretation of spectroscopic data. Clathric acid showed mild antibacterial activity against several Gram-positive bacteria.

Methods and instrumentation for piezoelectric motors.

Because of their compact form factor and rigidity, piezoelectric motors are used in scanning probe microscopes that operate at low temperature and high magnetic field. Here we present detailed information to facilitate the assembly, operation, and characterization of inertial motors. Specifically, a model of the motor is developed and used to identify different regions of operation.

Bioactive diterpenoid containing a reversible "spring-loaded" (E,Z)-dieneone Michael acceptor.

Three new briarane diterpenoids, briareolate esters L-N (1-3), have been isolated from a gorgonian Briareum asbestinum. Briareolate esters L (1) and M (2) are the first natural products possessing a 10-membered macrocyclic ring with a (E,Z)-dieneone and exhibit growth inhibition activity against both human embryonic stem cells (BG02) and a pancreatic cancer cell line (BxPC-3). Briareolate ester L (1) was found to contain a "spring-loaded" (E,Z)-dieneone Michael acceptor group that can form a reversible covalent bond to model sulfur-based nucleophiles.

Templating an organic array with Si(111)-7×7.

We demonstrate that nearest neighbor molecular adsorption can be sterically hindered on the Si(111)-7×7 surface reconstruction. This breaks the energetic equivalence of corner and edge di-σ attachment geometries and allows a translationally ordered organic layer to be templated directly on the 7×7 reconstruction.

Hageseth's principle of extraterritorial jurisdiction and international telemedicine.

At what point does an international telemedicine transaction create a sufficient commercial nexus to allow one country the authority to impose its laws on a foreign telemedicine providers? Some light on this matter was shed by the US case of Hageseth versus Superior Court. The authority for extraterritorial jurisdiction is found in the US Constitution, which requires the states to cooperate in matters of law enforcement. Similar cooperation from foreign nations cannot be expected.

Activin a efficiently specifies definitive endoderm from human embryonic stem cells only when phosphatidylinositol 3-kinase signaling is suppressed.

Human ESCs (hESCs) respond to signals that determine their pluripotency, proliferation, survival, and differentiation status. In this report, we demonstrate that phosphatidylinositol 3-kinase (PI3K) antagonizes the ability of hESCs to differentiate in response to transforming growth factor beta family members such as Activin A and Nodal. Inhibition of PI3K signaling efficiently promotes differentiation of hESCs into mesendoderm and then definitive endoderm (DE) by allowing them to be specified by Activin/Nodal signals present in hESC cultures.

Reply to Comment on 'Bi nanolines on Si(001): registry with the substrate'.

The registry of bismuth dimers, integral components of the bismuth nanoline on Si(001), is examined. In contrast to the currently accepted view, the bismuth dimers are found to be in registry with the two-dimensional lattice created by the silicon dimers. The consequences of this finding are briefly explored.

The equilibrium geometry and electronic structure of Bi nanolines on clean and hydrogenated Si(001) surfaces.

The equilibrium geometry, electronic structure and energetic stability of Bi nanolines on clean and hydrogenated Si(001) surfaces have been examined by means of ab initio total energy calculations and scanning tunnelling microscopy. For the Bi nanolines on a clean Si surface the two most plausible structural models, the Miki or M model (Miki et al 1999 Phys. Rev.

7-Azaindolyl- and 2,2'-dipyridylamino-functionalized molecular stars with sixfold symmetry: self-assembly, luminescence, and coordination compounds.

Two novel star molecules functionalized with 7-azaindolyl and 2,2'-dipyridylamino groups have been synthesized. Both molecules possess a sixfold rotation symmetry. Molecule L1 is based on the hexaphenylbenzene core with the formula of hexa[p-(7-azaindolyl)phenyl]benzene, while molecule L2 is based on the hexakis(biphenyl)benzene core with the formula of hexa[p-(2,2'-dipyridylamino)biphenyl]benzene.