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Single molecule

Stephan Kremb, Constanze Müller, Philippe Schmitt-Kopplin, Christian R Voolstra
Marine algae represent an important source of novel natural products. While their bioactive potential has been studied to some extent, limited information is available on marine algae from the Red Sea. This study aimed at the broad discovery of new bioactivities from a collection of twelve macroalgal species from the Central Red Sea. We used imaging-based High-Content Screening (HCS) with a diverse spectrum of cellular markers for detailed cytological profiling of fractionated algal extracts. The cytological profiles for 3 out of 60 algal fractions clustered closely to reference inhibitors and showed strong inhibitory activities on the HIV-1 reverse transcriptase in a single-enzyme biochemical assay, validating the suggested biological target...
March 20, 2017: Marine Drugs
Baoyan Wu, Na Zhao
A novel targeting theranostic nanoprobe based on single-walled carbon nanotubes (SWCNTs)-natural biopolymer chitosan composites was developed for cancer cell targeting imaging and fluorescence imaging-guided photodynamic therapy. First, chitosan was respectively conjugated with a tumor-homing molecule folic acid, or a photosensitizing drug pyropheophorbide a using a water-soluble carbodiimide coupling chemistry. Chitosan was fluorescently labeled by fluorescein isothiocyanate via the covalently linkage of the isothiocyanate group with the amino group...
November 17, 2016: Nanomaterials
Guanying Chen, Zhijun Ning, Hans Ågren
We are glad to announce the Special Issue "Nanostructured Solar Cells", published in Nanomaterials. This issue consists of eight articles, two communications, and one review paper, covering major important aspects of nanostructured solar cells of varying types. From fundamental physicochemical investigations to technological advances, and from single junction solar cells (silicon solar cell, dye sensitized solar cell, quantum dots sensitized solar cell, and small molecule organic solar cell) to tandem multi-junction solar cells, all aspects are included and discussed in this issue to advance the use of nanotechnology to improve the performance of solar cells with reduced fabrication costs...
August 9, 2016: Nanomaterials
Liuyang Zhang, Xianqiao Wang
The single molecule detection associated with DNA sequencing has motivated intensive efforts to identify single DNA bases. However, little research has been reported utilizing single-layer hexagonal boron nitride (hBN) for DNA sequencing. Here we employ molecular dynamics simulations to explore pathways for single-strand DNA (ssDNA) sequencing by nanopore on the hBN sheet. We first investigate the adhesive strength between nucleobases and the hBN sheet, which provides the foundation for the hBN-base interaction and nanopore sequencing mechanism...
June 6, 2016: Nanomaterials
Fei Qi, Dmitrij Frishman
Secondary structure elements in the coding regions of mRNAs play an important role in gene expression and regulation, but distinguishing functional from non-functional structures remains challenging. Here we investigate the dependence of sequence-structure relationships in the coding regions on temperature based on the recent PARTE data by Wan et al. Our main finding is that the regions with high and low thermostability (high Tm and low Tm regions) are under evolutionary pressure to preserve RNA secondary structure and primary sequence, respectively...
March 7, 2017: Nucleic Acids Research
Ling Zhang, Jingmin Wang, Cheng Zhang, Dongxiao Li, Claudia M B Carvalho, Haoran Ji, Jianqiu Xiao, Ye Wu, Weichen Zhou, Hongyan Wang, Li Jin, Yang Luo, Xiru Wu, James R Lupski, Feng Zhang, Yuwu Jiang
Genomic disorders are the clinical conditions manifested by submicroscopic genomic rearrangements including copy number variants (CNVs). The CNVs can be identified by array-based comparative genomic hybridization (aCGH), the most commonly used technology for molecular diagnostics of genomic disorders. However, clinical aCGH only informs CNVs in the probe interrogated regions. Neither orientational information nor the resulting genomic rearrangement structure is provided, which is a key to uncovering mutational and pathogenic mechanisms underlying genomic disorders...
March 14, 2017: Human Molecular Genetics
Daniel R Burnham, Bas Nijholt, Iwijn De Vlaminck, Jinhua Quan, Timur Yusufzai, Cees Dekker
We investigate the mechanistic nature of the Snf2 family protein HARP, mutations of which are responsible for Schimke immuno-osseous dysplasia. Using a single-molecule magnetic tweezers assay, we construct RPA-stabilized DNA bubbles within torsionally constrained DNA to investigate the annealing action of HARP on a physiologically relevant substrate. We find that HARP closes RPA-stabilized bubbles in a slow reaction, taking on the order of tens of minutes for ∼600 bp of DNA to be re-annealed. The data indicate that DNA re-anneals through the removal of RPA, which is observed as clear steps in the bubble-closing traces...
February 28, 2017: Nucleic Acids Research
Yu-Ting Chen, Kai-Chun Chang, Hao-Teng Hu, Yi-Lan Chen, You-Hsin Lin, Chiung-Fang Hsu, Cheng-Fu Chang, Kung-Yao Chang, Jin-Der Wen
Frameshifting is an essential process that regulates protein synthesis in many viruses. The ribosome may slip backward when encountering a frameshift motif on the messenger RNA, which usually contains a pseudoknot structure involving tertiary base pair interactions. Due to the lack of detailed molecular explanations, previous studies investigating which features of the pseudoknot are important to stimulate frameshifting have presented diverse conclusions. Here we constructed a bimolecular pseudoknot to dissect the interior tertiary base pairs and used single-molecule approaches to assess the structure targeted by ribosomes...
February 21, 2017: Nucleic Acids Research
Kyung-Won Min, Myung Hyun Jo, Soochul Shin, Sylvia Davila, Richard W Zealy, Soo Im Kang, Lawson T Lloyd, Sungchul Hohng, Je-Hyun Yoon
Eukaryotic mRNA decay is tightly modulated by RNA-binding proteins (RBPs) and microRNAs (miRNAs). RBP AU-binding factor 1 (AUF1) has four isoforms resulting from alternative splicing and is critical for miRNA-mediated gene silencing with a distinct preference of target miRNAs. Previously, we have shown that AUF1 facilitates miRNA loading to Argonaute 2 (AGO2), the catalytic component of the RNA-induced silencing complex. Here, we further demonstrate that depletion of AUF1 abolishes the global interaction of miRNAs and AGO2...
February 28, 2017: Nucleic Acids Research
Jian Zhang, Lukasz Kurgan
Understanding of molecular mechanisms that govern protein-protein interactions and accurate modeling of protein-protein docking rely on accurate identification and prediction of protein-binding partners and protein-binding residues. We review over 40 methods that predict protein-protein interactions from protein sequences including methods that predict interacting protein pairs, protein-binding residues for a pair of interacting sequences and protein-binding residues in a single protein chain. We focus on the latter methods that provide residue-level annotations and that can be broadly applied to all protein sequences...
March 1, 2017: Briefings in Bioinformatics
Tomasz Magdziarz, Karolina Mitusinska, Sandra Goldowska, Alicja Pluciennik, Michal Stolarczyk, Magdalena Lugowska, Artur Góra
Motivation: The identification and tracking of molecules which enter active site cavity requires screening the positions of thousands of single molecules along several thousand molecular dynamic steps. To fill the existing gap between tools searching for tunnels and pathways and advanced tools employed for accelerated water flux investigations, we have developed AQUA-DUCT. Results: AQUA-DUCT is an easy-to-use tool that facilitates analysis of the behaviour of molecules that penetrate any selected region in a protein...
March 2, 2017: Bioinformatics
Jia-Wen Ye, Jiao-Min Lin, Zong-Wen Mo, Chun-Ting He, Hao-Long Zhou, Jie-Peng Zhang, Xiao-Ming Chen
Luminescent porous coordination polymers (PCPs) are emerging as attractive oxygen-sensing materials, but they are mostly based on single-wavelength luminometry. Here, we report a special mixed-lanthanide strategy for self-referenced ratiometric oxygen sensing. A series of isostructural, pure-lanthanide, or mixed-lanthanide PCPs, MCF-53(Tb/Eux), were synthesized by solvothermal reactions. Single-crystal X-ray diffraction revealed that MCF-53(Tb/Eux) is composed of complicated two-dimensional coordination networks, which interdigitate to form a three-dimensional supramolecular structure retaining one-dimensional ultra-micropores...
March 23, 2017: Inorganic Chemistry
Georgios I Angelis, William Ryder, John Gillam, Frederic Boisson, Andre Kyme, Roger Fulton, Steven Meikle, Peter Kench
Awake and/or freely moving small animal single photon emission imaging allows the continuous study of molecules exhibiting slow kinetics without the need to restrain or anaesthetise the animals. Estimating motion free projections in freely moving small animal planar imaging can be considered as a limited angle tomography problem, except that we wish to estimate the 2D planar projections rather than the 3D volume, where the angular sampling in all three axes depends on the rotational motion of the animal. In this study, we hypothesise that the motion corrected planar projections estimated by reconstructing an estimate of the 3D volume using an iterative motion compensating reconstruction algorithm and integrating it along the projection path, will closely match the true, motion-less, planar distribution regardless of the object motion...
March 23, 2017: Physics in Medicine and Biology
Eitan Lerner, Antonino Ingargiola, Jookyung J Lee, Sergei Borukhov, Xavier Michalet, Shimon Weiss
In many cases, initiation is rate limiting to transcription. This due in part to the multiple cycles of abortive transcription that delay promoter escape and the transition from initiation to elongation. Pausing of transcription in initiation can further delay promoter escape. The previously hypothesized pausing in initiation was confirmed by two recent studies from Duchi et al. (1) and from Lerner, Chung et al. (2) In both studies, pausing is attributed to lack of forward translocation of the nascent transcript during initiation...
March 23, 2017: Transcription
Hua Tian, David A Six, Thomas Krucker, Jennifer A Leeds, Nicholas Winograd
The inherent difficulty of discovering new and effective antibacterials and the rapid development of resistance particularly in Gram-negative bacteria, illustrates the urgent need for new methods that enable rational drug design. Here we report the development of 3D imaging cluster secondary ion mass spectrometry (SIMS) as a label-free approach to chemically map small molecules in aggregated and single Escherichia coli cells, with ~300 nm spatial resolution and high chemical sensitivity. The feasibility of quantitative analysis was explored, and a non-linear relationship between treatment dose and signal for tetracycline and ampicillin, two clinically-used antibacterials, was observed...
March 23, 2017: Analytical Chemistry
Tapas Paul, Subhas C Bera, Padmaja P Mishra
The detailed conformational dynamics of the melted region in double-stranded DNA has been studied using a combination of ensemble and single-molecule FRET techniques. We monitored the millisecond time scale fluctuation kinetics of the two strands at the bubble region that varies with the size of the bubble. As the individual strands at the melting bubble behave as single-stranded DNA, and hence fluctuate dynamically to attain energetically favored configurations, the rates of these fluctuations increase with increase in the bubble size...
March 23, 2017: Nanoscale
Thomas Kroneis, Emma Jonasson, Daniel Andersson, Soheila Dolatabadi, Anders Ståhlberg
The need to perform gene expression profiling using next generation sequencing and quantitative real-time PCR (qPCR) on small sample sizes and single cells is rapidly expanding. However, to analyse few molecules, preamplification is required. Here, we studied global and target-specific preamplification using 96 optimised qPCR assays. To evaluate the preamplification strategies, we monitored the reactions in real-time using SYBR Green I detection chemistry followed by melting curve analysis. Next, we compared yield and reproducibility of global preamplification to that of target-specific preamplification by qPCR using the same amount of total RNA...
March 23, 2017: Scientific Reports
Yen-Ming Chen, Li-Hua Chen, Meng-Pei Li, Hsing-Fen Li, Akon Higuchi, S Suresh Kumar, Qing-Dong Ling, Abdullah A Alarfaj, Murugan A Munusamy, Yung Chang, Giovanni Benelli, Kadarkarai Murugan, Akihiro Umezawa
Establishing cultures of human embryonic (ES) and induced pluripotent (iPS) stem cells in xeno-free conditions is essential for producing clinical-grade cells. Development of cell culture biomaterials for human ES and iPS cells is critical for this purpose. We designed several structures of oligopeptide-grafted poly (vinyl alcohol-co-itaconic acid) hydrogels with optimal elasticity, and prepared them in formations of single chain, single chain with joint segment, dual chain with joint segment, and branched-type chain...
March 23, 2017: Scientific Reports
Soo Chan Lee, Alexander Idnurm
Although at the level of resolution of genes and molecules most information about mating in fungi is from a single lineage, the Dikarya, many fundamental discoveries about mating in fungi have been made in the earlier branches of the fungi. These are nonmonophyletic groups that were once classified into the chytrids and zygomycetes. Few species in these lineages offer the potential of genetic tractability, thereby hampering the ability to identify the genes that underlie those fundamental insights. Research performed during the past decade has now established the genes required for mating type determination and pheromone synthesis in some species in the phylum Mucoromycota, especially in the order Mucorales...
March 2017: Microbiology Spectrum
Ying Qing, Zhiqi Tian, Ying Bi, Yongyao Wang, Jiangang Long, Chun-Xiao Song, Jiajie Diao
We here review primary methods used in quantifying and mapping 5-hydroxymethylcytosine (5hmC), including global quantification, restriction enzyme-based detection, and methods involving DNA-enrichment strategies and the genome-wide sequencing of 5hmC. As discovered in the mammalian genome in 2009, 5hmC, oxidized from 5-methylcytosine (5mC) by ten-eleven translocation (TET) dioxygenases, is increasingly being recognized as a biomarker in biological processes from development to pathogenesis, as its various detection methods have shown...
March 23, 2017: BioEssays: News and Reviews in Molecular, Cellular and Developmental Biology
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