Budding yeast Cdc13-Stn1-Ten1 (CST) complex plays an essential role in telomere protection and maintenance, and has been proposed to be a telomere-specific replication protein A (RPA)-like complex. Previous genetic and structural studies revealed a close resemblance between Stn1-Ten1 and RPA32-RPA14. However, the relationship between Cdc13 and RPA70, the largest subunit of RPA, has remained unclear. Here, we report the crystal structure of the N-terminal OB (oligonucleotide/oligosaccharide binding) fold of Cdc13. Although Cdc13 has an RPA70-like domain organization, the structures of Cdc13 OB folds are significantly different from their counterparts in RPA70, suggesting that they have distinct evolutionary origins. Furthermore, our structural and biochemical analyses revealed unexpected dimerization by the N-terminal OB fold and showed that homodimerization is probably a conserved feature of all Cdc13 proteins. We also uncovered the structural basis of the interaction between the Cdc13 N-terminal OB fold and the catalytic subunit of DNA polymerase α (Pol1), and demonstrated a role for Cdc13 dimerization in Pol1 binding. Analysis of the phenotypes of mutants defective in Cdc13 dimerization and Cdc13-Pol1 interaction revealed multiple mechanisms by which dimerization regulates telomere lengths in vivo. Collectively, our findings provide novel insights into the mechanisms and evolution of Cdc13.

We have investigated six nanomaterials for their applicability as surfaces for the analyses of peptides and proteins using surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). Gold nanoparticles (NPs) were useful nanomaterials for small analytes (e.g., glutathione); Pt nanosponges and Fe 3 O 4 NPs were efficient nanomaterials for proteins, with an upper detectable mass limit of ca. 25 kDa. Nanomaterials have several advantages over organic matrices, including lower limits of detection for small analytes and lower batch-to-batch variations (fewer problems associated with "sweet spots"), when used in laser desorption/ionization mass spectrometry. (J Am Soc Mass Spectrom 2010, 21, 1204 -1207) © 2010 American Society for Mass Spectrometry S urface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) was developed recently using nanomaterials rather than organic compounds as matrices, for the determination of analytes of interest. For example, laser desorption/ionization (LDI) of intact proteins and protein aggregates in the presence of glycerol has been demonstrated using cobalt particles (ca. 30 nm) [1]. Similar to the role played by organic matrices, the particles absorb energy from the laser irradiation and transfer it efficiently to the analytes, thereby inducing desorption and ionization. Mixtures of graphite particles (2-150 m) and glycerol have been employed in the analysis of proteins and peptides [2,3]. Several other nanomaterials, including carbon nanotubes, nanodiamonds, and various nanoparticles (NPs, namely SiO 2 , ZnS, TiO 2 , Fe 3 O 4 , Fe 3 O 4 /TiO 2 , and Au) are also useful-without the addition of glycerol-for SALDI-MS [4 -12]. Because of their unique chemical and physical properties, NPs can also act as selective probes and/or efficient ionization nanomaterials. For example, Au and TiO 2 NPs are suitable for the concentration and ionization of aminothiols and catechins, respectively, in SALDI-MS [8,11]. One other advantage of using NPs is that fewer "sweet spots" are formed, thereby maximizing reproducibility. Although NPs have been used successfully for the determination of a range of analytes (from small analytes to proteins), a review of the literature reveals that the various NPs provide quite different results in terms of sensitivity, reproducibility, and mass range. Thus, our aim in this study was to evaluate the performance of several types of NPs for the analysis of peptides and proteins. ExperimentalSix nanomaterials-Au NPs, TiO 2 NPs, Se NPs, CdTe quantum dots (QDs), Fe 3 O 4 NPs, and Pt nanosponges (NSPs)-were tested for the SALDI-MS-based analyses of peptides and proteins; they were prepared in aqueous solutions and characterized according to procedures described in the literature [8,11,[13][14][15][16]. A twolayer preparation method was applied to deposit the nanomaterials and samples onto the metal plates used in SALDI-MS. First, one of the nanomaterial solutions (1 L) was deposited into one of the wells of the MS plate and dried under ambient cond...

This study presents a new magnetic bead-based microfluidic platform, which integrates three major modules for rapid leukocytes purification, genomic DNA (gDNA) extraction and fast analysis of genetic gene. By utilizing microfluidic technologies and magnetic beads conjugated with CD 15/45 antibodies, leukocytes in a human whole blood sample can be first purified and concentrated, followed by extraction of gDNA utilizing surface-charge switchable, DNA-specific, magnetic beads in the lysis solution. Then, specific genes associated with genetic diseases can be amplified by an on-chip polymerase chain reaction (PCR) process automatically. The whole pretreatment process including the leukocytes purification and gDNA extraction can be performed in an automatic fashion with the incorporation of the built bio-separators consisting of microcoils array within less than 20 min. The detection of single nucleotide polymorphism (SNP) genotyping of methylenetetra-hydrofolate reductase (MTHFR) C677T region associated with an increased risk of genetic diseases was further performed to demonstrate the capability of the proposed system. The extracted gDNA can be transported into a micro PCR chamber for on-chip fast nucleic acid amplification of detection genes with minimum human intervention. Hence, the developed system may provide a powerful automated platform for pretreatment of human leukocytes, gDNA extraction and fast analysis of genetic gene.

MnO 2 has been considered as the most promising bifunctional electrocatalyst toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Despite their highly active ORR performance, the OER catalytic activity of MnO 2 species is still far from satisfying. Herein, for the first time, highly active OER catalytic NiFe layered double hydroxides (NiFe LDHs) are combined with MnO 2 via a selective electrodeposition method to form a Janus electrode in which the MnO 2 and NiFe LDHs are in situ grown on two sides of a porous nickel foam (MnO 2 -NiFe/Ni). The MnO 2 -NiFe/Ni electrode exhibits excellent bifunctional catalytic activity and stability for both ORR and OER compared to bare MnO 2 on account of the rational design of the Janus bifunctional configuration separating OER and ORR active materials. Moreover, such a Janus MnO 2 -NiFe air electrode endows the zinc−air battery with better cycling stability and energy efficiency than the bare MnO 2 electrode. Our work demonstrates a novel Janus electrode configuration to design high-performance electrocatalysts for energy storage and conversion applications.

The preparation of efficient and low‐cost bifunctional catalysts with superior stability for water splitting is a topic of significant current interest for hydrogen generation. A facile strategy has been developed to fabricate highly active electrodes with hierarchical porous structures by using a two‐step electrodeposition method, in which NiFe layered double hydroxide is grown in situ on a three‐dimensional hierarchical Ni mesh (NiFe/Ni/Ni). The as‐prepared NiFe/Ni/Ni electrodes demonstrate remarkable structural stability with high surface areas, effective gas transportation, and fast electron transfer. Benefiting from the unique structure, the self‐supported NiFe/Ni/Ni electrodes exhibit overpotentials of 190 mV and 300 mV for the oxygen evolution reaction (OER) at current densities of 10 and 500 mA cm−2, respectively. Furthermore, the self‐supported NiFe/Ni/Ni electrodes also exhibit high performance in the hydrogen evolution reaction (HER) and excellent stability at a current density of 500 mA cm−2 for both OER and HER. Remarkably, using NiFe/Ni/Ni as both the cathode and anode for alkaline water electrolysis, a current density of 500 mA cm−2 is attained at a cell voltage of 1.96 V. Additionally, the water electrolyzer demonstrates superior stability even at a large current density (500 mA cm−2) when subjected to high temperatures.

Localization microscopy has shown to be capable of systematic investigations on the arrangement and counting of cellular uptake of gold nanoparticles (GNP) with nanometer resolution. In this article, we show that the application of specially modified RNA targeting gold nanoparticles ("SmartFlares") can result in ring like shaped GNP arrangements around the cell nucleus. Transmission electron microscopy revealed GNP accumulation in vicinity to the intracellular membrane structures including them of the endoplasmatic reticulum. A quantification of the radio therapeutic dose enhancement as a proof of principle was conducted with γH2AX foci analysis: The application of both-SmartFlares and unmodified GNPs-lead to a significant dose enhancement with a factor of up to 1.2 times the dose deposition compared to non-treated breast cancer cells. This enhancement effect was even more pronounced for SmartFlares. Furthermore, it was shown that a magnetic field of 1 Tesla simultaneously applied during irradiation has no detectable influence on neither the structure nor the dose enhancement dealt by gold nanoparticles.

In this paper we describe the preparation of CdTe quantum dot-sensitized solar cells (QDSSCs). We coated FTO substrates with 21 nm-diameter TiO 2 nanoparticles (NPs) and then immersed the system in poly(dimethyldiallylammonium chloride) (PDDA) solution under ambient conditions. The treated substrates were then subjected to 3 nm-diameter CdTe NP solution at 100 C for various periods of times. To increase the degree of deposition and to obtain CdTe QDs of various sizes, we performed the coating of the CdTe QDs through three heating cycles for 24, 12, or 6 h. The as-prepared (TiO 2 ) 3 -PDDA-(QD CdTe ) 3 -FTO electrodes were then used to fabricate (TiO 2 ) 3 -PDDA-(QD CdTe ) 3 -FTO QDSSCs employing 1-ethyl-3-methylimidazolium thiocyanate incorporating 1.0 M LiI and 0.1 M I 2 as electrolytes. The heating treatment allows the QDSSCs to harvest energy at a higher efficiency in the visible region of solar light. As a result, the as-prepared QDSSCs feature a high energy conversion efficiency (h ¼ 2.02%) and a high open-circuit photovoltage (V oc ¼ 850 mV) at 100% sunlight (AM1.5, 100 mW/cm 2 ). À redox couple. [20][21][22] RTILs such as 1-dodecyl-3-methylimidazolium iodide, 1-propyl-3-methylimidazolium iodide, and

Electrochemical water splitting is deemed as an important and sustainable technology for hydrogen generation. Searching for low-cost and efficient electrocatalysts toward hydrogen/oxygen evolution reaction (HER/OER) is of great importance for commercial application of water electrolysis. Cobased phosphides and oxides/hydroxides are extensively developed as HER and OER electrocatalysts, respectively. Herein, a novel strategy is developed to prepare a self-supported N-doped CoP ultrathin nanosheets (namely N−Co−Ni−P/Ni) for HER and Fedoped CoOOH nanosheets (namely Fe−Co−OOH/Ni) for OER based on the MOF-derived Co(OH) 2 nanosheets, along with short lateral size caused by Co-MOF confinement growth. The selfsupported N−Co−Ni−P demands an overpotential of 50 mV to deliver a current density of 10 mA cm −2 in alkaline conditions (1M) for HER. The self-supported Fe−Co−OOH nanosheet electrocatalysts also exhibit high catalytic activity for OER. The experimental measurements demonstrate that the increased positive charge of Co atoms caused by the introduction of N atoms can significantly enhance HER performance. Moreover, the large surface areas, high exposure of active sites, and effective mass transport channels are also favorable to improved catalytic activity. The electrolyzer with N−Co−Ni−P/Ni and Fe−Co−OOH shows excellent activity with an electrolysis voltage of 1.51 V at 10 mA cm −2 , which is superior to the Pt(−)//Ir/Ta (+) electrolyzer (1.62 V).