Amphiphilic self-assembled polymeric copper catalyst to parts per million levels: click chemistry.

Self-assembly of copper sulfate and a poly(imidazole-acrylamide) amphiphile provided a highly active, reusable, globular, solid-phase catalyst for click chemistry. The self-assembled polymeric Cu catalyst was readily prepared from poly(N-isopropylacrylamide-co-N-vinylimidazole) and CuSO(4) via coordinative convolution. The surface of the catalyst was covered with globular particles tens of nanometers in diameter, and those sheetlike composites were layered to build an aggregated structure.

Mitochondrial fission proteins Fis1 and Mdv1, but not Dnm1, play a role in maintenance of heteroplasmy in budding yeast.

In budding yeast, the mitochondrial DNA (mtDNA) replication pathway involving the homologous DNA pairing protein Mhr1 promotes mitochondrial allele segregation. Mitochondrial fusion facilitates the recombination-mediated replication pathway; however, the role of fission remains largely unknown. By monitoring mitochondrial allele segregation during zygotic division, we found that the absence of fission proteins Fis1 or Mdv1, but not Dnm1, resulted in increased initial homoplasmy levels and decreased mtDNA copy number.

Four new bisabolane-type sesquiterpenes from Ligularia lankongensis.

The chemical constituents of the roots of two Ligularia lankongensis samples collected in Yunnan and Sichuan Provinces, China, were investigated, together with the DNA sequence of the atpB-rbcL and ITS regions. Four new highly oxygenated bisabolane-type sesquiterpenes (1 - 4) were obtained. Intraspecific diversity in the DNA sequence was found to be limited.

Optimal cellular mobility for synchronization arising from the gradual recovery of intercellular interactions.

Cell movement and intercellular signaling occur simultaneously during the development of tissues, but little is known about how movement affects signaling. Previous theoretical studies have shown that faster moving cells favor synchronization across a population of locally coupled genetic oscillators. An important assumption in these studies is that cells can immediately interact with their new neighbors after arriving at a new location.

The nucleoporin ELYS/Mel28 regulates nuclear envelope subdomain formation in HeLa cells.

In open mitosis the nuclear envelope (NE) reassembles at the end of each mitosis. This process involves the reformation of the nuclear pore complex (NPC), the inner and outer nuclear membranes, and the nuclear lamina. In human cells cell cycle-dependent NE subdomains exist, characterized as A-type lamin-rich/NPC-free or B-type lamin-rich/NPC-rich, which are initially formed as core or noncore regions on mitotic chromosomes, respectively.

Elaborate synthesis of biological macromolecules.

Egged on: Elaborate syntheses of biological macromolecules consisting of more than two different components is developing. Kajihara and co-workers have used a bio-resource to develop a new strategy for the semisynthesis of glycoproteins.

A protein switch with tunable steepness reconstructed in Escherichia coli cells with eukaryotic signaling proteins.

An important goal of synthetic biology is to construct reaction circuits with artificial responses by assembling modulated biological elements into living cells. While many such attempts have been based upon the cellular transcriptional apparatus, the use of the post-translational machinery remains relatively rare. Here we report the reconstruction in Escherichia coli of a protein-based artificial module based upon elements of a eukaryotic cell signaling pathway.

Hikeshi, a nuclear import carrier for Hsp70s, protects cells from heat shock-induced nuclear damage.

During heat shock stress, importin β family-mediated nucleocytoplasmic trafficking is downregulated, whereas nuclear import of the molecular chaperone Hsp70s is upregulated. Here, we identify a nuclear import pathway that operates during heat shock stress and is mediated by an evolutionarily conserved protein named "Hikeshi," which does not belong to the importin β family. Hikeshi binds to FG-Nups and translocates through nuclear pores on its own, showing characteristic features of nuclear transport carriers.

Effect of bisecting GlcNAc and core fucosylation on conformational properties of biantennary complex-type N-glycans in solution.

The introduction of bisecting GlcNAc and core fucosylation in N-glycans is essential for fine functional regulation of glycoproteins. In this paper, the effect of these modifications on the conformational properties of N-glycans is examined at the atomic level by performing replica-exchange molecular dynamics (REMD) simulations. We simulate four biantennary complex-type N-glycans, namely, unmodified, two single-substituted with either bisecting GlcNAc or core fucose, and disubstituted forms.

Gelation effect on the synthesis of high-aspect-ratio gold nanorods.

The growth process of high-aspect-ratio gold nanorods in gelled surfactant solution was studied. As for the application of gold nanorods, the surface plasmon is quite useful, whose absorption depends on their aspect ratio. Hence it is important to synthesize gold nanorods with favorable aspect ratio in high yield.

Surface-potential undulation of Alq3 thin films prepared on ITO, Au, and n-Si.

The surface potential (SP) morphology on thin films of tris(8-hydroxyquinolinato) aluminum (Alq3) was investigated with Kelvin probe force microscopy. Thin Alq3 films of 100 nm were prepared on ITO/glass substrates, Au/mica substrates, and n-Si substrates. Cloud-like morphologies of the SP undulation with 200-400 nm in lateral size were observed for all three types of the substrates.

A stable germanone as the first isolated heavy ketone with a terminal oxygen atom.

The carbon-oxygen double bond of ketones (R(2)C=O) makes them among the most important organic compounds, but their homologues, heavy ketones with an E=O double bond (E = Si, Ge, Sn or Pb), had not been isolated as stable compounds. Their unavailability as monomeric molecules is ascribed to their high tendency for intermolecular oligomerization or polymerization via opening of the E=O double bond. Can such an intermolecular process be inhibited by bulky protecting groups? We now report that it can, with the first isolation of a monomeric germanium ketone analogue (Eind)(2)Ge=O (Eind = 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl), stabilized by appropriately designed bulky Eind groups, with a planar tricoordinate germanium atom.

Concentration of metabolites from low-density planktonic communities for environmental metabolomics using nuclear magnetic resonance spectroscopy.

Environmental metabolomics is an emerging field that is promoting new understanding in how organisms respond to and interact with the environment and each other at the biochemical level. Nuclear magnetic resonance (NMR) spectroscopy is one of several technologies, including gas chromatography-mass spectrometry (GC-MS), with considerable promise for such studies. Advantages of NMR are that it is suitable for untargeted analyses, provides structural information and spectra can be queried in quantitative and statistical manners against recently available databases of individual metabolite spectra.

Synthesis of optically pure norcantharidin analogue NCA-01, a highly selective protein phosphatase 2B inhibitor, and its derivatives.

An efficient synthetic route to optically pure norcantharidin analogue NCA-01, a highly selective inhibitor of protein phosphatase 2B (PP2B; calcineurin), has been developed. The absolute stereochemistry of the enantiomers was determined by X-ray crystallographic analysis. Optically pure NCA derivatives that had various substituents at the C1 position were synthesized in a similar manner.

Comprehensive predictions of target proteins based on protein-chemical interaction using virtual screening and experimental verifications.

Background: Identification of the target proteins of bioactive compounds is critical for elucidating the mode of action; however, target identification has been difficult in general, mostly due to the low sensitivity of detection using affinity chromatography followed by CBB staining and MS/MS analysis.

Results: We applied our protocol of predicting target proteins combining in silico screening and experimental verification for incednine, which inhibits the anti-apoptotic function of Bcl-xL by an unknown mechanism. One hundred eighty-two target protein candidates were computationally predicted to bind to incednine by the statistical prediction method, and the predictions were verified by in vitro binding of incednine to seven proteins, whose expression can be confirmed in our cell system.

Paraspeckle nuclear bodies--useful uselessness?

The nucleus of higher eukaryotes, such as humans and mice, is compartmentalized into multiple nuclear bodies, an organization that allows for the regulation of complex gene expression pathways that are characteristic of these organisms. Paraspeckles are recently discovered, mammalian-specific nuclear bodies built on a long, non-protein-coding RNA, NEAT1 (nuclear-enriched abundant transcript 1), which assembles various protein components including RNA-binding proteins of the DBHS (Drosophila behavior and human splicing) family. Paraspeckles have been proposed to control several biological processes, such as stress responses and cellular differentiation, but their function at the whole animal level remains unclear.

High-curvature domains of the ER are important for the organization of ER exit sites in Saccharomyces cerevisiae.

Protein export from the endoplasmic reticulum (ER) to the Golgi apparatus occurs at specialized regions known as the ER exit sites (ERES). In Saccharomyces cerevisiae, ERES appear as numerous scattered puncta throughout the ER. We examined ERES within the peripheral ER, finding that the proteins comprising the ERES localize on high-curvature ER domains where curvature-stabilizing protein Rtn1 is present.

Hydrophilic Double-Network Polymers that Sustain High Mechanical Modulus under 80% Humidity.

The effects of water on the mechanical properties of synthetic hydrophilic polymers with double-network (DN) structures were studied under different relative humidities (RH). It was found that they could sustain nearly the same high Young's modulus as dry DN polymers in the RH range 10-80% (water content 3-17 wt %), that is, more than 10 MPa. However, when the RH exceeds 80%, DN polymers abruptly absorb large amounts of water (water content 90 wt %) and transform to a highly water-swollen "gel state" with a decrease in the Young's modulus of 3 orders of magnitude.

Polydioxythiophene nanodots, nonowires, nano-networks, and tubular structures: the effect of functional groups and temperature in template-free electropolymerization.

Various nanostructures, including nanofibers, nanodots, nanonetwork, and nano- to microsize tubes of functionalized poly(3,4-ethylenedioxythiophene) (EDOT) and poly(3,4-propylenedioxythiophene) (ProDOT) are created by using a template-free electropolymerization method on indium-tin-oxide substrates. By investigating conducting polymer nanostructures containing various functional groups prepared at different polymerization temperature, we conclude a synergistic effect of functional groups and temperature on the formation of polymer nanostructures when a template-free electropolymerization method is applied. For unfunctionalized EDOT and ProDOT, or EDOT containing alkyl functional groups, nanofibers and nanoporous structures are usually found.

Rotation-free holographic imaging with extended arc reference.

We proposed and experimentally demonstrated a rotation-free approach of holographic imaging by using an extended arc reference. From the diffraction intensity, the objects were retrieved using a two-step algorithm without a prior knowledge of the information of the sample and reference. This scheme alleviates the convergence problem of coherent diffractive imaging and also promises to achieve a high resolution.

Protein disulfide isomerase-mediated disulfide bonds regulate the gelatinolytic activity and secretion of matrix metalloproteinase-9.

Matrix metalloproteinase-9 (MMP-9) is one of the major MMPs that can degrade extracellular matrix. Besides normal physiological functions, MMP-9 is involved in metastasis and tumor angiogenesis. Although several inhibitors of MMP-9 have been identified, in vivo regulators of MMP-9 activation are unknown.

Construction of a microbial natural product library for chemical biology studies.

The RIKEN Natural Products Depository (NPDepo) is a public depository of small molecules. Currently, the NPDepo chemical library contains 39,200 pure compounds, half of which are natural products and their derivatives. In order to reinforce the uniqueness of our chemical library, we have improved our strategies for the collection of microbial natural products.