I‑Motif-Programmed Functionalization of DNA Nanocircles

The folding of various intra- and intermolecular i-motif DNAs is systematically studied to expand the toolbox for the control of mechanical operations in DNA nanoarchitectures. We analyzed i-motif DNAs with two C-tracts under acidic conditions by gel electrophoresis, circular dichroism, and thermal denaturation and show that their intra- versus intermolecular folding primarily depends on the length of the C-tracts. Two stretches of six or fewer C-residues favor the intermolecular folding of i-motifs, whereas longer C-tracts promote the formation of intramolecular i-motif structures with unusually high thermal stability. We then introduced intra- and intermolecular i-motifs formed by DNAs containing two C-tracts into single-stranded regions within otherwise double-stranded DNA nanocircles. By adjusting the length of C-tracts we can control the intra- and intermolecular folding of i-motif DNAs and achieve programmable functionalization of dsDNA nanocircles. Single-stranded gaps in the nanocircle that are functionalized with an intramolecular i-motif enable the reversible contraction and extension of the DNA circle, as monitored by fluorescence quenching. Thereby, the nanocircle behaves as a proton-fueled DNA prototype machine. In contrast, nanorings containing intermolecular i-motifs induce the assembly of defined multicomponent DNA architectures in response to proton-triggered predicted structural changes, such as dimerization, “kiss”, and cyclization. The resulting DNA nanostructures are verified by gel electrophoresis and visualized by atomic force microscopy, including different folding topologies of an intermolecular i-motif. The i-motif-functionalized DNA nanocircles may serve as a versatile tool for the formation of larger interlocked dsDNA nanostructures, like rotaxanes and catenanes, to achieve diverse mechanical operations

One-Step Fast-Synthesized Foamlike Amorphous Co(OH)₂ Flexible Film on Ti Foil by Plasma-Assisted Electrolytic Deposition as a Binder-Free Anode of a High-Capacity Lithium-Ion Battery

This research prepared an amorphous Co­(OH)₂ flexible film on Ti foil using plasma-assisted electrolytic deposition within 3.5 min. Amorphous Co­(OH)₂ structure was determined by X-ray diffraction and X-ray photoelectron spectroscopy. Its areal capacity testing as the binder and adhesive-free anode of a lithium-ion battery shows that the cycling capacity can reach 2000 μAh/cm² and remain at 930 μAh/cm² after 50 charge–discharge cycles, which benefits from the emerging Co­(OH)₂ active material and amorphous foamlike structure. The research introduced a new method to synthesize amorphous Co­(OH)₂ as the anode in a fast-manufactured low-cost lithium-ion battery

Examination of the Polypeptide Substrate Specificity for <i>Escherichia coli</i> ClpA

Enzyme-catalyzed protein unfolding is essential for a large array of biological functions, including microtubule severing, membrane fusion, morphogenesis and trafficking of endosomes, protein disaggregation, and ATP-dependent proteolysis. These enzymes are all members of the ATPases associated with various cellular activity (AAA+) superfamily of proteins. <i>Escherichia coli</i> ClpA is a hexameric ring ATPase responsible for enzyme-catalyzed protein unfolding and translocation of a polypeptide chain into the central cavity of the tetradecameric <i>E. coli</i> ClpP serine protease for proteolytic degradation. Further, ClpA also uses its protein unfolding activity to catalyze protein remodeling reactions in the absence of ClpP. ClpA recognizes and binds a variety of protein tags displayed on proteins targeted for degradation. In addition, ClpA binds unstructured or poorly structured proteins containing no specific tag sequence. Despite this, a quantitative description of the relative binding affinities for these different substrates is not available. Here we show that ClpA binds to the 11-amino acid SsrA tag with an affinity of 200 ± 30 nM. However, when the SsrA sequence is incorporated at the carboxy terminus of a 30–50-amino acid substrate exhibiting little secondary structure, the affinity constant decreases to 3–5 nM. These results indicate that additional contacts beyond the SsrA sequence are required for maximal binding affinity. Moreover, ClpA binds to various lengths of the intrinsically unstructured protein, α-casein, with an affinity of ∼30 nM. Thus, ClpA does exhibit modest specificity for SsrA when incorporated into an unstructured protein. Moreover, incorporating these results with the known structural information suggests that SsrA makes direct contact with the domain 2 loop in the axial channel and additional substrate length is required for additional contacts within domain 1

Rare damaging variants in DNA Repair and Cell Cycle pathways are associated with hippocampal and cognitive dysfunction - A combined genetic-imaging study in first-episode treatment-na飗e patients with schizophrenia

<div>94 first-episode treatment-naive schizophrenia patients and</div><div>134 normal controls  were sequenced using TruSeq Exome Enrichment Kit optimized for Illumina HiSeq2000 sequencing.The study was approved by the ethical committee in West China Hospital of Sichuan University. All participations were Han Chinese and provided written informed consent for their participation in this study.</div

Description statistics of grapevine bud burst percentage in 2012 and 2013, as well as of the statistics of soil properties in the vineyard.

<p>Description statistics of grapevine bud burst percentage in 2012 and 2013, as well as of the statistics of soil properties in the vineyard.</p

Schematic of the grafting strategy for aptamer design.

<p>The DNA duplex containing Watson-Crick base pairs of the first generation aptamer 3 is grafted onto the G-quadruplex structures of 1 and 2 to produce two new quadruplex/duplex DNA structures I and II as the second generation aptamers.</p

Calculated variograms and fitted models for the standardized bud burst percentage data in 2012 and 2013, respectively.

<p>Calculated variograms and fitted models for the standardized bud burst percentage data in 2012 and 2013, respectively.</p

Determination coefficient (R²) from partial least square regressions of bud burst percentage with soil properties, trend surface model, and combination of the two sets of variables for the low, medium and high groups as well as for the entire field of 2012 and 2013 seasons.

<p>Determination coefficient (R²) from partial least square regressions of bud burst percentage with soil properties, trend surface model, and combination of the two sets of variables for the low, medium and high groups as well as for the entire field of 2012 and 2013 seasons.</p

Comparison between the DNAzyme functions of the aptamers 1 and I.

<p>(A) UV−Vis absorption spectra (after 4 min) for analyzing 0.5 µM catalysts with the ABTS−H₂O₂ colorimetry in the detection buffer: a) hemin, b) hemin plus the aptamer 1, c) hemin plus the aptamer I, d) hemin plus a control DNA obtained by replacing the G residues of two spacers in the aptamer I with T. (B) Reaction kinetics of the H₂O₂-mediated ABTS oxidation catalyzed by: 1) the hemin−I DNAzyme, 2) the hemin−1 DNAzyme.</p

Partition of the overall spatial variation into nonspatial soil variation (NSV), spatially structured variation shared by soil variables (SV_S), spatial variation not shared by soil variables (SV_NS) and unexplained variation (UV).

<p>The calculations were based on the partial least square regressions of bud burst percentage with soil, trend surface, and combination of the two sets of variables.</p