The sequence d(GGGGTTTTGGGG) from the 3' overhang of the Oxytricha telomere has been crystallized and its three-dimensional structure solved to 2.5 A resolution. The oligonucleotide forms hairpins, two of which join to make a four-stranded helical structure with the loops containing four thymine residues at either end. The guanine residues are held together by cyclic hydrogen bonding and an ion is located in the centre. The four guanine residues in each segment have a glycosyl conformation that alternates between anti and syn. There are two four-stranded molecules in the asymmetric unit showing that the structure has some intrinsic flexibility.
Dimethylsulphoniopropionate (DMSP) is one of the Earth’s most abundant organosulphur molecules, a signalling molecule, a key nutrient for marine microorganisms, and the major precursor for gaseous dimethyl sulphide (DMS). DMS, another infochemical in signalling pathways, is important in global sulphur cycling2, and affects the Earth’s albedo, and potentially climate, via sulphate aerosol and cloud condensation nuclei production. It was thought that only eukaryotes produce significant amounts of DMSP, but here we demonstrate that many marine heterotrophic bacteria also produce DMSP, likely using the same methionine (Met) transamination pathway as macroalgae and phytoplankton10. We identify the first DMSP synthesis gene in any organism, dsyB, which encodes the key methyltransferase enzyme of this pathway and is a reliable reporter for bacterial DMSP synthesis in marine alphaproteobacteria. DMSP production and dsyB transcription are upregulated by increased salinity, nitrogen limitation and lower temperatures in our model DMSP-producing bacterium Labrenzia aggregata LZB033. With significant numbers of dsyB homologues in marine metagenomes, we propose that bacteria likely make a significant contribution to oceanic DMSP production. Furthermore, since DMSP production is not solely associated with obligate phototrophs, the process need not be confined to the photic zones of marine environments, and as such may have been underestimate
Mantle cell lymphoma (MCL) is characterized by 11q13 chromosomal translocation and CCND1 overexpression, but additional genomic changes are also important for lymphomagenesis. To identify the genomic aberrations of MCL at higher resolutions, we analysed 29 patient samples and seven cell lines using array-based comparative genomic hybridization (array CGH) consisting of 2348 artificial chromosome clones, which cover the whole genome at a 1.3 mega base resolution. The incidence of identified genomic aberrations was generally higher than that determined with chromosomal CGH. The most frequent imbalances detected by array CGH were gains of chromosomes 3q26 (48%), 7p21 (34%), 6p25 (24%), 8q24 (24%), 10p12 (21%) and 17q23 (17%), and losses of chromosomes 2p11 (83%), 11q22 (59%), 13q21 (55%), 1p21-p22 (52%), 13q34 (52%), 9q22 (45%), 17p13 (45%), 9p21 (41%), 9p24 (41%), 6q23-q24 (38%), 1p36 (31%), 8p23 (34%), 10p14 (31%), 19p13 (28%), 5q21 (21%), 22q12 (21%), 1q42 (17%) and 2q13 (17%). Our analyses also detected several novel recurrent regions of loss located at 1p36, 1q42.2-q43, 2p11.2, 2q13, 17p13.3 and 19p13.2-p13.3, as well as recurrent regions of homozygous loss such as 2p11 (Igj), 2q13 and 9p21.3-p24.1 (INK4a/ARF). Of the latter, we investigated the 2q13 loss, which led to identification of homozygous deletions of the proapoptotic gene BIM. The highresolution array CGH technology allowed for the precise identification of genomic aberrations and identification of BIM as a novel candidate tumor suppressor gene in MCL.
Sodium-ion batteries (SIBs) are still confronted with several major challenges, including low energy and power densities, short-term cycle life, and poor low-temperature performance, which severely hinder their practical applications. Here, a high-voltage cathode composed of Na V (PO ) O F nano-tetraprisms (NVPF-NTP) is proposed to enhance the energy density of SIBs. The prepared NVPF-NTP exhibits two high working plateaux at about 4.01 and 3.60 V versus the Na /Na with a specific capacity of 127.8 mA h g . The energy density of NVPF-NTP reaches up to 486 W h kg , which is higher than the majority of other cathode materials previously reported for SIBs. Moreover, due to the low strain (≈2.56% volumetric variation) and superior Na transport kinetics in Na intercalation/extraction processes, as demonstrated by in situ X-ray diffraction, galvanostatic intermittent titration technique, and cyclic voltammetry at varied scan rates, the NVPF-NTP shows long-term cycle life, superior low-temperature performance, and outstanding high-rate capabilities. The comparison of Ragone plots further discloses that NVPF-NTP presents the best power performance among the state-of-the-art cathode materials for SIBs. More importantly, when coupled with an Sb-based anode, the fabricated sodium-ion full-cells also exhibit excellent rate and cycling performances, thus providing a preview of their practical application.
Small beginnings: Metal nanoparticle/CNT nanohybrids are synthesized from carbon nanotubes (CNTs) functionalized with an ionic-liquid polymer. The Pt and PtRu nanoparticles with narrow size distribution (average diameter: (1.3+/-0.4) nm for PtRu, (1.9+/-0.5) nm for Pt) are dispersed uniformly on the CNTs (see images) and show good performance in methanol electrooxidation.
Carbon-nanotube (CNT) fibers integrate such properties as high mechanical strength, extraordinary structural flexibility, high thermal and electrical conductivities, novel corrosion and oxidation resistivities, and high surface area, which makes them a very promising candidate for next-generation smart textiles and wearable devices. A brief review of the preparation of CNT fibers and recently developed CNT-fiber-based flexible and functional devices, which include artificial muscles, electrochemical double-layer capacitors, lithium-ion batteries, solar cells, and memristors, is presented.
Dimethylsulfoniopropionate (DMSP) and its catabolite dimethyl sulfide (DMS) are key marine nutrients 1,2 , with roles in global sulfur cycling 2 , atmospheric chemistry 3 , signalling 4,5 and, potentially, climate regulation 6,7. DMSP production was previously thought to be an oxic and photic process, mainly confined to the surface oceans. 2 However, here we show that DMSP concentrations and DMSP/DMS synthesis rates were higher in surface marine sediment from e.g., saltmarsh ponds, estuaries and the deep ocean than in the overlying seawater. A quarter of bacterial strains isolated from saltmarsh sediment produced DMSP (up to 73 mM), and previously unknown DMSPproducers were identified. Most DMSP-producing isolates contained dsyB 8 , but some alphaproteobacteria, gammaproteobacteria and actinobacteria utilised a methionine methylation pathway independent of DsyB, previously only associated with higher plants. These bacteria contained a methionine methyltransferase 'mmtN' gene-a marker for bacterial DMSP synthesis via this pathway. DMSP-producing bacteria and their dsyB and/or mmtN transcripts were present in all tested seawater samples and Tara Oceans bacterioplankton datasets, but were far more abundant in marine surface sediment. Approximately 10 8 bacteria per gram of surface marine sediment are predicted to produce DMSP, and their contribution to this process should be included in future models of global DMSP production. We propose that coastal and marine sediments, which cover a large part of the Earth's surface, are environments with high DMSP and DMS productivity, and that bacteria are important producers within them. Approximately eight billion tonnes of DMSP is produced by phytoplankton in the Earth's surface oceans annually 9. However, surface sediment from saltmarsh ponds, an estuary and the deep ocean (with high pressures and no light) contained DMSP levels (5-128 nmol DMSP g-1) that were up to ~three orders of magnitude higher than the overlying seawater (0.01-0.70 nmol DMSP ml-1) (Fig. 1a-b, Supplementary Tables 1a and 2), a phenomenon also observed in 10,11. DMSP concentration decreased with depth, being much lower in anoxic sediment, but even in deeper sediments the concentration was approximately an order of magnitude higher than in the overlying seawater (Supplementary Table 1a). This study focused on DMSP synthesis in coastal surface sediments, where DMSP concentrations were highest. The
The crystal structure of human platelet factor 4 (PF4) has been solved to a resolution of 2.4 A by molecular replacement and refined to an R-factor of 24.1%. The structure consists of four polypeptide chains which form a tetrameric unit. N-terminal residues, previously defined as a random coil or extended loop region, form antiparallel beta-sheet-like structures that form noncovalent associations between dimers. These antiparallel beta-sheet-like structures are positioned lateral to the beta-bilayer motif and stabilize the tetrameric unit. A positively charged ring of lysine and arginine side chains encircles the PF4 tetramer sphere, presenting multiple potential sites and orientations for heparin binding. The electrostatic interactions of multiply charged amino acid side chains and hydrogen bonding interactions at the AB/CD dimer interface serve to stabilize the tetrameric structure further.
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